#include "httplib.h"
namespace httplib {
// httplib::any — type-erased value container (C++11 compatible)
// On C++17+ builds, thin wrappers around std::any are provided.

/*
 * Implementation that will be part of the .cc file if split into .h + .cc.
 */

namespace stream {

// stream::Result implementations
Result::Result() : chunk_size_(8192) {}

Result::Result(ClientImpl::StreamHandle &&handle, size_t chunk_size)
    : handle_(std::move(handle)), chunk_size_(chunk_size) {}

Result::Result(Result &&other) noexcept
    : handle_(std::move(other.handle_)), buffer_(std::move(other.buffer_)),
      current_size_(other.current_size_), chunk_size_(other.chunk_size_),
      finished_(other.finished_) {
  other.current_size_ = 0;
  other.finished_ = true;
}

Result &Result::operator=(Result &&other) noexcept {
  if (this != &other) {
    handle_ = std::move(other.handle_);
    buffer_ = std::move(other.buffer_);
    current_size_ = other.current_size_;
    chunk_size_ = other.chunk_size_;
    finished_ = other.finished_;
    other.current_size_ = 0;
    other.finished_ = true;
  }
  return *this;
}

bool Result::is_valid() const { return handle_.is_valid(); }
Result::operator bool() const { return is_valid(); }

int Result::status() const {
  return handle_.response ? handle_.response->status : -1;
}

const Headers &Result::headers() const {
  static const Headers empty_headers;
  return handle_.response ? handle_.response->headers : empty_headers;
}

std::string Result::get_header_value(const std::string &key,
                                            const char *def) const {
  return handle_.response ? handle_.response->get_header_value(key, def) : def;
}

bool Result::has_header(const std::string &key) const {
  return handle_.response ? handle_.response->has_header(key) : false;
}

Error Result::error() const { return handle_.error; }
Error Result::read_error() const { return handle_.get_read_error(); }
bool Result::has_read_error() const { return handle_.has_read_error(); }

bool Result::next() {
  if (!handle_.is_valid() || finished_) { return false; }

  if (buffer_.size() < chunk_size_) { buffer_.resize(chunk_size_); }

  ssize_t n = handle_.read(&buffer_[0], chunk_size_);
  if (n > 0) {
    current_size_ = static_cast<size_t>(n);
    return true;
  }

  current_size_ = 0;
  finished_ = true;
  return false;
}

const char *Result::data() const { return buffer_.data(); }
size_t Result::size() const { return current_size_; }

std::string Result::read_all() {
  std::string result;
  while (next()) {
    result.append(data(), size());
  }
  return result;
}

} // namespace stream

namespace sse {

// SSEMessage implementations
SSEMessage::SSEMessage() : event("message") {}

void SSEMessage::clear() {
  event = "message";
  data.clear();
  id.clear();
}

// SSEClient implementations
SSEClient::SSEClient(Client &client, const std::string &path)
    : client_(client), path_(path) {}

SSEClient::SSEClient(Client &client, const std::string &path,
                            const Headers &headers)
    : client_(client), path_(path), headers_(headers) {}

SSEClient::~SSEClient() { stop(); }

SSEClient &SSEClient::on_message(MessageHandler handler) {
  on_message_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_event(const std::string &type,
                                      MessageHandler handler) {
  event_handlers_[type] = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_open(OpenHandler handler) {
  on_open_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::on_error(ErrorHandler handler) {
  on_error_ = std::move(handler);
  return *this;
}

SSEClient &SSEClient::set_reconnect_interval(int ms) {
  reconnect_interval_ms_ = ms;
  return *this;
}

SSEClient &SSEClient::set_max_reconnect_attempts(int n) {
  max_reconnect_attempts_ = n;
  return *this;
}

bool SSEClient::is_connected() const { return connected_.load(); }

const std::string &SSEClient::last_event_id() const {
  return last_event_id_;
}

void SSEClient::start() {
  running_.store(true);
  run_event_loop();
}

void SSEClient::start_async() {
  running_.store(true);
  async_thread_ = std::thread([this]() { run_event_loop(); });
}

void SSEClient::stop() {
  running_.store(false);
  client_.stop(); // Cancel any pending operations
  if (async_thread_.joinable()) { async_thread_.join(); }
}

bool SSEClient::parse_sse_line(const std::string &line, SSEMessage &msg,
                                      int &retry_ms) {
  // Blank line signals end of event
  if (line.empty() || line == "\r") { return true; }

  // Lines starting with ':' are comments (ignored)
  if (!line.empty() && line[0] == ':') { return false; }

  // Find the colon separator
  auto colon_pos = line.find(':');
  if (colon_pos == std::string::npos) {
    // Line with no colon is treated as field name with empty value
    return false;
  }

  auto field = line.substr(0, colon_pos);
  std::string value;

  // Value starts after colon, skip optional single space
  if (colon_pos + 1 < line.size()) {
    auto value_start = colon_pos + 1;
    if (line[value_start] == ' ') { value_start++; }
    value = line.substr(value_start);
    // Remove trailing \r if present
    if (!value.empty() && value.back() == '\r') { value.pop_back(); }
  }

  // Handle known fields
  if (field == "event") {
    msg.event = value;
  } else if (field == "data") {
    // Multiple data lines are concatenated with newlines
    if (!msg.data.empty()) { msg.data += "\n"; }
    msg.data += value;
  } else if (field == "id") {
    // Empty id is valid (clears the last event ID)
    msg.id = value;
  } else if (field == "retry") {
    // Parse retry interval in milliseconds
    {
      int v = 0;
      auto res =
          detail::from_chars(value.data(), value.data() + value.size(), v);
      if (res.ec == std::errc{}) { retry_ms = v; }
    }
  }
  // Unknown fields are ignored per SSE spec

  return false;
}

void SSEClient::run_event_loop() {
  auto reconnect_count = 0;

  while (running_.load()) {
    // Build headers, including Last-Event-ID if we have one
    auto request_headers = headers_;
    if (!last_event_id_.empty()) {
      request_headers.emplace("Last-Event-ID", last_event_id_);
    }

    // Open streaming connection
    auto result = stream::Get(client_, path_, request_headers);

    // Connection error handling
    if (!result) {
      connected_.store(false);
      if (on_error_) { on_error_(result.error()); }

      if (!should_reconnect(reconnect_count)) { break; }
      wait_for_reconnect();
      reconnect_count++;
      continue;
    }

    if (result.status() != 200) {
      connected_.store(false);
      // For certain errors, don't reconnect
      if (result.status() == 204 || // No Content - server wants us to stop
          result.status() == 404 || // Not Found
          result.status() == 401 || // Unauthorized
          result.status() == 403) { // Forbidden
        if (on_error_) { on_error_(Error::Connection); }
        break;
      }

      if (on_error_) { on_error_(Error::Connection); }

      if (!should_reconnect(reconnect_count)) { break; }
      wait_for_reconnect();
      reconnect_count++;
      continue;
    }

    // Connection successful
    connected_.store(true);
    reconnect_count = 0;
    if (on_open_) { on_open_(); }

    // Event receiving loop
    std::string buffer;
    SSEMessage current_msg;

    while (running_.load() && result.next()) {
      buffer.append(result.data(), result.size());

      // Process complete lines in the buffer
      size_t line_start = 0;
      size_t newline_pos;

      while ((newline_pos = buffer.find('\n', line_start)) !=
             std::string::npos) {
        auto line = buffer.substr(line_start, newline_pos - line_start);
        line_start = newline_pos + 1;

        // Parse the line and check if event is complete
        auto event_complete =
            parse_sse_line(line, current_msg, reconnect_interval_ms_);

        if (event_complete && !current_msg.data.empty()) {
          // Update last_event_id for reconnection
          if (!current_msg.id.empty()) { last_event_id_ = current_msg.id; }

          // Dispatch event to appropriate handler
          dispatch_event(current_msg);

          current_msg.clear();
        }
      }

      // Keep unprocessed data in buffer
      buffer.erase(0, line_start);
    }

    // Connection ended
    connected_.store(false);

    if (!running_.load()) { break; }

    // Check for read errors
    if (result.has_read_error()) {
      if (on_error_) { on_error_(result.read_error()); }
    }

    if (!should_reconnect(reconnect_count)) { break; }
    wait_for_reconnect();
    reconnect_count++;
  }

  connected_.store(false);
}

void SSEClient::dispatch_event(const SSEMessage &msg) {
  // Check for specific event type handler first
  auto it = event_handlers_.find(msg.event);
  if (it != event_handlers_.end()) {
    it->second(msg);
    return;
  }

  // Fall back to generic message handler
  if (on_message_) { on_message_(msg); }
}

bool SSEClient::should_reconnect(int count) const {
  if (!running_.load()) { return false; }
  if (max_reconnect_attempts_ == 0) { return true; } // unlimited
  return count < max_reconnect_attempts_;
}

void SSEClient::wait_for_reconnect() {
  // Use small increments to check running_ flag frequently
  auto waited = 0;
  while (running_.load() && waited < reconnect_interval_ms_) {
    std::this_thread::sleep_for(std::chrono::milliseconds(100));
    waited += 100;
  }
}

} // namespace sse

#ifdef CPPHTTPLIB_SSL_ENABLED
/*
 * TLS abstraction layer - internal function declarations
 * These are implementation details and not part of the public API.
 */
namespace tls {

// Client context
ctx_t create_client_context();
void free_context(ctx_t ctx);
bool set_min_version(ctx_t ctx, Version version);
bool load_ca_pem(ctx_t ctx, const char *pem, size_t len);
bool load_ca_file(ctx_t ctx, const char *file_path);
bool load_ca_dir(ctx_t ctx, const char *dir_path);
bool load_system_certs(ctx_t ctx);
bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                         const char *password);
bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                          const char *key_path, const char *password);

// Server context
ctx_t create_server_context();
bool set_server_cert_pem(ctx_t ctx, const char *cert, const char *key,
                         const char *password);
bool set_server_cert_file(ctx_t ctx, const char *cert_path,
                          const char *key_path, const char *password);
bool set_client_ca_file(ctx_t ctx, const char *ca_file, const char *ca_dir);
void set_verify_client(ctx_t ctx, bool require);

// Session management
session_t create_session(ctx_t ctx, socket_t sock);
void free_session(session_t session);
bool set_sni(session_t session, const char *hostname);
bool set_hostname(session_t session, const char *hostname);

// Handshake (non-blocking capable)
TlsError connect(session_t session);
TlsError accept(session_t session);

// Handshake with timeout (blocking until timeout)
bool connect_nonblocking(session_t session, socket_t sock, time_t timeout_sec,
                         time_t timeout_usec, TlsError *err);
bool accept_nonblocking(session_t session, socket_t sock, time_t timeout_sec,
                        time_t timeout_usec, TlsError *err);

// I/O (non-blocking capable)
ssize_t read(session_t session, void *buf, size_t len, TlsError &err);
ssize_t write(session_t session, const void *buf, size_t len, TlsError &err);
int pending(const_session_t session);
void shutdown(session_t session, bool graceful);

// Connection state
bool is_peer_closed(session_t session, socket_t sock);

// Certificate verification
cert_t get_peer_cert(const_session_t session);
void free_cert(cert_t cert);
bool verify_hostname(cert_t cert, const char *hostname);
uint64_t hostname_mismatch_code();
long get_verify_result(const_session_t session);

// Certificate introspection
std::string get_cert_subject_cn(cert_t cert);
std::string get_cert_issuer_name(cert_t cert);
bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans);
bool get_cert_validity(cert_t cert, time_t &not_before, time_t &not_after);
std::string get_cert_serial(cert_t cert);
bool get_cert_der(cert_t cert, std::vector<unsigned char> &der);
const char *get_sni(const_session_t session);

// CA store management
ca_store_t create_ca_store(const char *pem, size_t len);
void free_ca_store(ca_store_t store);
bool set_ca_store(ctx_t ctx, ca_store_t store);
size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs);
std::vector<std::string> get_ca_names(ctx_t ctx);

// Dynamic certificate update (for servers)
bool update_server_cert(ctx_t ctx, const char *cert_pem, const char *key_pem,
                        const char *password);
bool update_server_client_ca(ctx_t ctx, const char *ca_pem);

// Certificate verification callback
bool set_verify_callback(ctx_t ctx, VerifyCallback callback);
long get_verify_error(const_session_t session);
std::string verify_error_string(long error_code);

// TlsError information
uint64_t peek_error();
uint64_t get_error();
std::string error_string(uint64_t code);

} // namespace tls
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 1: detail namespace - Non-SSL utilities
 */

namespace detail {

bool set_socket_opt_impl(socket_t sock, int level, int optname,
                                const void *optval, socklen_t optlen) {
  return setsockopt(sock, level, optname,
#ifdef _WIN32
                    reinterpret_cast<const char *>(optval),
#else
                    optval,
#endif
                    optlen) == 0;
}

bool set_socket_opt(socket_t sock, int level, int optname, int optval) {
  return set_socket_opt_impl(sock, level, optname, &optval, sizeof(optval));
}

bool set_socket_opt_time(socket_t sock, int level, int optname,
                                time_t sec, time_t usec) {
#ifdef _WIN32
  auto timeout = static_cast<uint32_t>(sec * 1000 + usec / 1000);
#else
  timeval timeout;
  timeout.tv_sec = static_cast<long>(sec);
  timeout.tv_usec = static_cast<decltype(timeout.tv_usec)>(usec);
#endif
  return set_socket_opt_impl(sock, level, optname, &timeout, sizeof(timeout));
}

bool is_hex(char c, int &v) {
  if (isdigit(c)) {
    v = c - '0';
    return true;
  } else if ('A' <= c && c <= 'F') {
    v = c - 'A' + 10;
    return true;
  } else if ('a' <= c && c <= 'f') {
    v = c - 'a' + 10;
    return true;
  }
  return false;
}

bool from_hex_to_i(const std::string &s, size_t i, size_t cnt,
                          int &val) {
  if (i >= s.size()) { return false; }

  val = 0;
  for (; cnt; i++, cnt--) {
    if (!s[i]) { return false; }
    auto v = 0;
    if (is_hex(s[i], v)) {
      val = val * 16 + v;
    } else {
      return false;
    }
  }
  return true;
}

std::string from_i_to_hex(size_t n) {
  static const auto charset = "0123456789abcdef";
  std::string ret;
  do {
    ret = charset[n & 15] + ret;
    n >>= 4;
  } while (n > 0);
  return ret;
}

std::string compute_etag(const FileStat &fs) {
  if (!fs.is_file()) { return std::string(); }

  // If mtime cannot be determined (negative value indicates an error
  // or sentinel), do not generate an ETag. Returning a neutral / fixed
  // value like 0 could collide with a real file that legitimately has
  // mtime == 0 (epoch) and lead to misleading validators.
  auto mtime_raw = fs.mtime();
  if (mtime_raw < 0) { return std::string(); }

  auto mtime = static_cast<size_t>(mtime_raw);
  auto size = fs.size();

  return std::string("W/\"") + from_i_to_hex(mtime) + "-" +
         from_i_to_hex(size) + "\"";
}

// Format time_t as HTTP-date (RFC 9110 Section 5.6.7): "Sun, 06 Nov 1994
// 08:49:37 GMT" This implementation is defensive: it validates `mtime`, checks
// return values from `gmtime_r`/`gmtime_s`, and ensures `strftime` succeeds.
std::string file_mtime_to_http_date(time_t mtime) {
  if (mtime < 0) { return std::string(); }

  struct tm tm_buf;
#ifdef _WIN32
  if (gmtime_s(&tm_buf, &mtime) != 0) { return std::string(); }
#else
  if (gmtime_r(&mtime, &tm_buf) == nullptr) { return std::string(); }
#endif
  char buf[64];
  if (strftime(buf, sizeof(buf), "%a, %d %b %Y %H:%M:%S GMT", &tm_buf) == 0) {
    return std::string();
  }

  return std::string(buf);
}

// Parse HTTP-date (RFC 9110 Section 5.6.7) to time_t. Returns -1 on failure.
time_t parse_http_date(const std::string &date_str) {
  struct tm tm_buf;

  // Create a classic locale object once for all parsing attempts
  const std::locale classic_locale = std::locale::classic();

  // Try to parse using std::get_time (C++11, cross-platform)
  auto try_parse = [&](const char *fmt) -> bool {
    std::istringstream ss(date_str);
    ss.imbue(classic_locale);

    memset(&tm_buf, 0, sizeof(tm_buf));
    ss >> std::get_time(&tm_buf, fmt);

    return !ss.fail();
  };

  // RFC 9110 preferred format (HTTP-date): "Sun, 06 Nov 1994 08:49:37 GMT"
  if (!try_parse("%a, %d %b %Y %H:%M:%S")) {
    // RFC 850 format: "Sunday, 06-Nov-94 08:49:37 GMT"
    if (!try_parse("%A, %d-%b-%y %H:%M:%S")) {
      // asctime format: "Sun Nov  6 08:49:37 1994"
      if (!try_parse("%a %b %d %H:%M:%S %Y")) {
        return static_cast<time_t>(-1);
      }
    }
  }

#ifdef _WIN32
  return _mkgmtime(&tm_buf);
#elif defined _AIX
  return mktime(&tm_buf);
#else
  return timegm(&tm_buf);
#endif
}

bool is_weak_etag(const std::string &s) {
  // Check if the string is a weak ETag (starts with 'W/"')
  return s.size() > 3 && s[0] == 'W' && s[1] == '/' && s[2] == '"';
}

bool is_strong_etag(const std::string &s) {
  // Check if the string is a strong ETag (starts and ends with '"', at least 2
  // chars)
  return s.size() >= 2 && s[0] == '"' && s.back() == '"';
}

size_t to_utf8(int code, char *buff) {
  if (code < 0x0080) {
    buff[0] = static_cast<char>(code & 0x7F);
    return 1;
  } else if (code < 0x0800) {
    buff[0] = static_cast<char>(0xC0 | ((code >> 6) & 0x1F));
    buff[1] = static_cast<char>(0x80 | (code & 0x3F));
    return 2;
  } else if (code < 0xD800) {
    buff[0] = static_cast<char>(0xE0 | ((code >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (code & 0x3F));
    return 3;
  } else if (code < 0xE000) { // D800 - DFFF is invalid...
    return 0;
  } else if (code < 0x10000) {
    buff[0] = static_cast<char>(0xE0 | ((code >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (code & 0x3F));
    return 3;
  } else if (code < 0x110000) {
    buff[0] = static_cast<char>(0xF0 | ((code >> 18) & 0x7));
    buff[1] = static_cast<char>(0x80 | ((code >> 12) & 0x3F));
    buff[2] = static_cast<char>(0x80 | ((code >> 6) & 0x3F));
    buff[3] = static_cast<char>(0x80 | (code & 0x3F));
    return 4;
  }

  // NOTREACHED
  return 0;
}

} // namespace detail

namespace ws {
namespace impl {

bool is_valid_utf8(const std::string &s) {
  size_t i = 0;
  auto n = s.size();
  while (i < n) {
    auto c = static_cast<unsigned char>(s[i]);
    size_t len;
    uint32_t cp;
    if (c < 0x80) {
      i++;
      continue;
    } else if ((c & 0xE0) == 0xC0) {
      len = 2;
      cp = c & 0x1F;
    } else if ((c & 0xF0) == 0xE0) {
      len = 3;
      cp = c & 0x0F;
    } else if ((c & 0xF8) == 0xF0) {
      len = 4;
      cp = c & 0x07;
    } else {
      return false;
    }
    if (i + len > n) { return false; }
    for (size_t j = 1; j < len; j++) {
      auto b = static_cast<unsigned char>(s[i + j]);
      if ((b & 0xC0) != 0x80) { return false; }
      cp = (cp << 6) | (b & 0x3F);
    }
    // Overlong encoding check
    if (len == 2 && cp < 0x80) { return false; }
    if (len == 3 && cp < 0x800) { return false; }
    if (len == 4 && cp < 0x10000) { return false; }
    // Surrogate halves (U+D800..U+DFFF) and beyond U+10FFFF are invalid
    if (cp >= 0xD800 && cp <= 0xDFFF) { return false; }
    if (cp > 0x10FFFF) { return false; }
    i += len;
  }
  return true;
}

} // namespace impl
} // namespace ws

namespace detail {

// NOTE: This code came up with the following stackoverflow post:
// https://stackoverflow.com/questions/180947/base64-decode-snippet-in-c
std::string base64_encode(const std::string &in) {
  static const auto lookup =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  std::string out;
  out.reserve(in.size());

  auto val = 0;
  auto valb = -6;

  for (auto c : in) {
    val = (val << 8) + static_cast<uint8_t>(c);
    valb += 8;
    while (valb >= 0) {
      out.push_back(lookup[(val >> valb) & 0x3F]);
      valb -= 6;
    }
  }

  if (valb > -6) { out.push_back(lookup[((val << 8) >> (valb + 8)) & 0x3F]); }

  while (out.size() % 4) {
    out.push_back('=');
  }

  return out;
}

std::string sha1(const std::string &input) {
  // RFC 3174 SHA-1 implementation
  auto left_rotate = [](uint32_t x, uint32_t n) -> uint32_t {
    return (x << n) | (x >> (32 - n));
  };

  uint32_t h0 = 0x67452301;
  uint32_t h1 = 0xEFCDAB89;
  uint32_t h2 = 0x98BADCFE;
  uint32_t h3 = 0x10325476;
  uint32_t h4 = 0xC3D2E1F0;

  // Pre-processing: adding padding bits
  std::string msg = input;
  uint64_t original_bit_len = static_cast<uint64_t>(msg.size()) * 8;
  msg.push_back(static_cast<char>(0x80));
  while (msg.size() % 64 != 56) {
    msg.push_back(0);
  }

  // Append original length in bits as 64-bit big-endian
  for (int i = 56; i >= 0; i -= 8) {
    msg.push_back(static_cast<char>((original_bit_len >> i) & 0xFF));
  }

  // Process each 512-bit chunk
  for (size_t offset = 0; offset < msg.size(); offset += 64) {
    uint32_t w[80];

    for (size_t i = 0; i < 16; i++) {
      w[i] =
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4]))
           << 24) |
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4 + 1]))
           << 16) |
          (static_cast<uint32_t>(static_cast<uint8_t>(msg[offset + i * 4 + 2]))
           << 8) |
          (static_cast<uint32_t>(
              static_cast<uint8_t>(msg[offset + i * 4 + 3])));
    }

    for (int i = 16; i < 80; i++) {
      w[i] = left_rotate(w[i - 3] ^ w[i - 8] ^ w[i - 14] ^ w[i - 16], 1);
    }

    uint32_t a = h0, b = h1, c = h2, d = h3, e = h4;

    for (int i = 0; i < 80; i++) {
      uint32_t f, k;
      if (i < 20) {
        f = (b & c) | ((~b) & d);
        k = 0x5A827999;
      } else if (i < 40) {
        f = b ^ c ^ d;
        k = 0x6ED9EBA1;
      } else if (i < 60) {
        f = (b & c) | (b & d) | (c & d);
        k = 0x8F1BBCDC;
      } else {
        f = b ^ c ^ d;
        k = 0xCA62C1D6;
      }

      uint32_t temp = left_rotate(a, 5) + f + e + k + w[i];
      e = d;
      d = c;
      c = left_rotate(b, 30);
      b = a;
      a = temp;
    }

    h0 += a;
    h1 += b;
    h2 += c;
    h3 += d;
    h4 += e;
  }

  // Produce the final hash as a 20-byte binary string
  std::string hash(20, '\0');
  for (size_t i = 0; i < 4; i++) {
    hash[i] = static_cast<char>((h0 >> (24 - i * 8)) & 0xFF);
    hash[4 + i] = static_cast<char>((h1 >> (24 - i * 8)) & 0xFF);
    hash[8 + i] = static_cast<char>((h2 >> (24 - i * 8)) & 0xFF);
    hash[12 + i] = static_cast<char>((h3 >> (24 - i * 8)) & 0xFF);
    hash[16 + i] = static_cast<char>((h4 >> (24 - i * 8)) & 0xFF);
  }
  return hash;
}

std::string websocket_accept_key(const std::string &client_key) {
  const std::string magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  return base64_encode(sha1(client_key + magic));
}

bool is_websocket_upgrade(const Request &req) {
  if (req.method != "GET") { return false; }

  // Check Upgrade: websocket (case-insensitive)
  auto upgrade_it = req.headers.find("Upgrade");
  if (upgrade_it == req.headers.end()) { return false; }
  auto upgrade_val = case_ignore::to_lower(upgrade_it->second);
  if (upgrade_val != "websocket") { return false; }

  // Check Connection header contains "Upgrade"
  auto connection_it = req.headers.find("Connection");
  if (connection_it == req.headers.end()) { return false; }
  auto connection_val = case_ignore::to_lower(connection_it->second);
  if (connection_val.find("upgrade") == std::string::npos) { return false; }

  // Check Sec-WebSocket-Key is a valid base64-encoded 16-byte value (24 chars)
  // RFC 6455 Section 4.2.1
  auto ws_key = req.get_header_value("Sec-WebSocket-Key");
  if (ws_key.size() != 24 || ws_key[22] != '=' || ws_key[23] != '=') {
    return false;
  }
  static const std::string b64chars =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  for (size_t i = 0; i < 22; i++) {
    if (b64chars.find(ws_key[i]) == std::string::npos) { return false; }
  }

  // Check Sec-WebSocket-Version: 13
  auto version = req.get_header_value("Sec-WebSocket-Version");
  if (version != "13") { return false; }

  return true;
}

bool write_websocket_frame(Stream &strm, ws::Opcode opcode,
                                  const char *data, size_t len, bool fin,
                                  bool mask) {
  // First byte: FIN + opcode
  uint8_t header[2];
  header[0] = static_cast<uint8_t>((fin ? 0x80 : 0x00) |
                                   (static_cast<uint8_t>(opcode) & 0x0F));

  // Second byte: MASK + payload length
  if (len < 126) {
    header[1] = static_cast<uint8_t>(len);
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
  } else if (len <= 0xFFFF) {
    header[1] = 126;
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
    uint8_t ext[2];
    ext[0] = static_cast<uint8_t>((len >> 8) & 0xFF);
    ext[1] = static_cast<uint8_t>(len & 0xFF);
    if (strm.write(reinterpret_cast<char *>(ext), 2) < 0) { return false; }
  } else {
    header[1] = 127;
    if (mask) { header[1] |= 0x80; }
    if (strm.write(reinterpret_cast<char *>(header), 2) < 0) { return false; }
    uint8_t ext[8];
    for (int i = 7; i >= 0; i--) {
      ext[7 - i] = static_cast<uint8_t>((len >> (i * 8)) & 0xFF);
    }
    if (strm.write(reinterpret_cast<char *>(ext), 8) < 0) { return false; }
  }

  if (mask) {
    // Generate random mask key
    thread_local std::mt19937 rng(std::random_device{}());
    uint8_t mask_key[4];
    auto r = rng();
    std::memcpy(mask_key, &r, 4);
    if (strm.write(reinterpret_cast<char *>(mask_key), 4) < 0) { return false; }

    // Write masked payload in chunks
    const size_t chunk_size = 4096;
    std::vector<char> buf((std::min)(len, chunk_size));
    for (size_t offset = 0; offset < len; offset += chunk_size) {
      size_t n = (std::min)(chunk_size, len - offset);
      for (size_t i = 0; i < n; i++) {
        buf[i] =
            data[offset + i] ^ static_cast<char>(mask_key[(offset + i) % 4]);
      }
      if (strm.write(buf.data(), n) < 0) { return false; }
    }
  } else {
    if (len > 0) {
      if (strm.write(data, len) < 0) { return false; }
    }
  }

  return true;
}

} // namespace detail

namespace ws {
namespace impl {

bool read_websocket_frame(Stream &strm, Opcode &opcode,
                                 std::string &payload, bool &fin,
                                 bool expect_masked, size_t max_len) {
  // Read first 2 bytes
  uint8_t header[2];
  if (strm.read(reinterpret_cast<char *>(header), 2) != 2) { return false; }

  fin = (header[0] & 0x80) != 0;

  // RSV1, RSV2, RSV3 must be 0 when no extension is negotiated
  if (header[0] & 0x70) { return false; }

  opcode = static_cast<Opcode>(header[0] & 0x0F);
  bool masked = (header[1] & 0x80) != 0;
  uint64_t payload_len = header[1] & 0x7F;

  // RFC 6455 Section 5.5: control frames MUST NOT be fragmented and
  // MUST have a payload length of 125 bytes or less
  bool is_control = (static_cast<uint8_t>(opcode) & 0x08) != 0;
  if (is_control) {
    if (!fin) { return false; }
    if (payload_len > 125) { return false; }
  }

  if (masked != expect_masked) { return false; }

  // Extended payload length
  if (payload_len == 126) {
    uint8_t ext[2];
    if (strm.read(reinterpret_cast<char *>(ext), 2) != 2) { return false; }
    payload_len = (static_cast<uint64_t>(ext[0]) << 8) | ext[1];
  } else if (payload_len == 127) {
    uint8_t ext[8];
    if (strm.read(reinterpret_cast<char *>(ext), 8) != 8) { return false; }
    // RFC 6455 Section 5.2: the most significant bit MUST be 0
    if (ext[0] & 0x80) { return false; }
    payload_len = 0;
    for (int i = 0; i < 8; i++) {
      payload_len = (payload_len << 8) | ext[i];
    }
  }

  if (payload_len > max_len) { return false; }

  // Read mask key if present
  uint8_t mask_key[4] = {0};
  if (masked) {
    if (strm.read(reinterpret_cast<char *>(mask_key), 4) != 4) { return false; }
  }

  // Read payload
  payload.resize(static_cast<size_t>(payload_len));
  if (payload_len > 0) {
    size_t total_read = 0;
    while (total_read < payload_len) {
      auto n = strm.read(&payload[total_read],
                         static_cast<size_t>(payload_len - total_read));
      if (n <= 0) { return false; }
      total_read += static_cast<size_t>(n);
    }
  }

  // Unmask if needed
  if (masked) {
    for (size_t i = 0; i < payload.size(); i++) {
      payload[i] ^= static_cast<char>(mask_key[i % 4]);
    }
  }

  return true;
}

} // namespace impl
} // namespace ws

namespace detail {

bool is_valid_path(const std::string &path) {
  size_t level = 0;
  size_t i = 0;

  // Skip slash
  while (i < path.size() && path[i] == '/') {
    i++;
  }

  while (i < path.size()) {
    // Read component
    auto beg = i;
    while (i < path.size() && path[i] != '/') {
      if (path[i] == '\0') {
        return false;
      } else if (path[i] == '\\') {
        return false;
      }
      i++;
    }

    auto len = i - beg;
    assert(len > 0);

    if (!path.compare(beg, len, ".")) {
      ;
    } else if (!path.compare(beg, len, "..")) {
      if (level == 0) { return false; }
      level--;
    } else {
      level++;
    }

    // Skip slash
    while (i < path.size() && path[i] == '/') {
      i++;
    }
  }

  return true;
}

bool canonicalize_path(const char *path, std::string &resolved) {
#if defined(_WIN32)
  char buf[_MAX_PATH];
  if (_fullpath(buf, path, _MAX_PATH) == nullptr) { return false; }
  resolved = buf;
#else
  char buf[PATH_MAX];
  if (realpath(path, buf) == nullptr) { return false; }
  resolved = buf;
#endif
  return true;
}

bool is_path_within_base(const std::string &resolved_path,
                                const std::string &resolved_base) {
#if defined(_WIN32)
  return _strnicmp(resolved_path.c_str(), resolved_base.c_str(),
                   resolved_base.size()) == 0;
#else
  return strncmp(resolved_path.c_str(), resolved_base.c_str(),
                 resolved_base.size()) == 0;
#endif
}

FileStat::FileStat(const std::string &path) {
#if defined(_WIN32)
  auto wpath = u8string_to_wstring(path.c_str());
  ret_ = _wstat(wpath.c_str(), &st_);
#else
  ret_ = stat(path.c_str(), &st_);
#endif
}
bool FileStat::is_file() const {
  return ret_ >= 0 && S_ISREG(st_.st_mode);
}
bool FileStat::is_dir() const {
  return ret_ >= 0 && S_ISDIR(st_.st_mode);
}

time_t FileStat::mtime() const {
  return ret_ >= 0 ? static_cast<time_t>(st_.st_mtime)
                   : static_cast<time_t>(-1);
}

size_t FileStat::size() const {
  return ret_ >= 0 ? static_cast<size_t>(st_.st_size) : 0;
}

std::string encode_path(const std::string &s) {
  std::string result;
  result.reserve(s.size());

  for (size_t i = 0; s[i]; i++) {
    switch (s[i]) {
    case ' ': result += "%20"; break;
    case '+': result += "%2B"; break;
    case '\r': result += "%0D"; break;
    case '\n': result += "%0A"; break;
    case '\'': result += "%27"; break;
    case ',': result += "%2C"; break;
    // case ':': result += "%3A"; break; // ok? probably...
    case ';': result += "%3B"; break;
    default:
      auto c = static_cast<uint8_t>(s[i]);
      if (c >= 0x80) {
        result += '%';
        char hex[4];
        auto len = snprintf(hex, sizeof(hex) - 1, "%02X", c);
        assert(len == 2);
        result.append(hex, static_cast<size_t>(len));
      } else {
        result += s[i];
      }
      break;
    }
  }

  return result;
}

std::string file_extension(const std::string &path) {
  std::smatch m;
  thread_local auto re = std::regex("\\.([a-zA-Z0-9]+)$");
  if (std::regex_search(path, m, re)) { return m[1].str(); }
  return std::string();
}

bool is_space_or_tab(char c) { return c == ' ' || c == '\t'; }

template <typename T>
bool parse_header(const char *beg, const char *end, T fn);

template <typename T>
bool parse_header(const char *beg, const char *end, T fn) {
  // Skip trailing spaces and tabs.
  while (beg < end && is_space_or_tab(end[-1])) {
    end--;
  }

  auto p = beg;
  while (p < end && *p != ':') {
    p++;
  }

  auto name = std::string(beg, p);
  if (!detail::fields::is_field_name(name)) { return false; }

  if (p == end) { return false; }

  auto key_end = p;

  if (*p++ != ':') { return false; }

  while (p < end && is_space_or_tab(*p)) {
    p++;
  }

  if (p <= end) {
    auto key_len = key_end - beg;
    if (!key_len) { return false; }

    auto key = std::string(beg, key_end);
    auto val = std::string(p, end);

    if (!detail::fields::is_field_value(val)) { return false; }

    if (case_ignore::equal(key, "Location") ||
        case_ignore::equal(key, "Referer")) {
      fn(key, val);
    } else {
      fn(key, decode_path_component(val));
    }

    return true;
  }

  return false;
}

bool parse_trailers(stream_line_reader &line_reader, Headers &dest,
                           const Headers &src_headers) {
  // NOTE: In RFC 9112, '7.1 Chunked Transfer Coding' mentions "The chunked
  // transfer coding is complete when a chunk with a chunk-size of zero is
  // received, possibly followed by a trailer section, and finally terminated by
  // an empty line". https://www.rfc-editor.org/rfc/rfc9112.html#section-7.1
  //
  // In '7.1.3. Decoding Chunked', however, the pseudo-code in the section
  // doesn't care for the existence of the final CRLF. In other words, it seems
  // to be ok whether the final CRLF exists or not in the chunked data.
  // https://www.rfc-editor.org/rfc/rfc9112.html#section-7.1.3
  //
  // According to the reference code in RFC 9112, cpp-httplib now allows
  // chunked transfer coding data without the final CRLF.

  // RFC 7230 Section 4.1.2 - Headers prohibited in trailers
  thread_local case_ignore::unordered_set<std::string> prohibited_trailers = {
      "transfer-encoding",
      "content-length",
      "host",
      "authorization",
      "www-authenticate",
      "proxy-authenticate",
      "proxy-authorization",
      "cookie",
      "set-cookie",
      "cache-control",
      "expect",
      "max-forwards",
      "pragma",
      "range",
      "te",
      "age",
      "expires",
      "date",
      "location",
      "retry-after",
      "vary",
      "warning",
      "content-encoding",
      "content-type",
      "content-range",
      "trailer"};

  case_ignore::unordered_set<std::string> declared_trailers;
  auto trailer_header = get_header_value(src_headers, "Trailer", "", 0);
  if (trailer_header && std::strlen(trailer_header)) {
    auto len = std::strlen(trailer_header);
    split(trailer_header, trailer_header + len, ',',
          [&](const char *b, const char *e) {
            const char *kbeg = b;
            const char *kend = e;
            while (kbeg < kend && (*kbeg == ' ' || *kbeg == '\t')) {
              ++kbeg;
            }
            while (kend > kbeg && (kend[-1] == ' ' || kend[-1] == '\t')) {
              --kend;
            }
            std::string key(kbeg, static_cast<size_t>(kend - kbeg));
            if (!key.empty() &&
                prohibited_trailers.find(key) == prohibited_trailers.end()) {
              declared_trailers.insert(key);
            }
          });
  }

  size_t trailer_header_count = 0;
  while (strcmp(line_reader.ptr(), "\r\n") != 0) {
    if (line_reader.size() > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }
    if (trailer_header_count >= CPPHTTPLIB_HEADER_MAX_COUNT) { return false; }

    constexpr auto line_terminator_len = 2;
    auto line_beg = line_reader.ptr();
    auto line_end =
        line_reader.ptr() + line_reader.size() - line_terminator_len;

    if (!parse_header(line_beg, line_end,
                      [&](const std::string &key, const std::string &val) {
                        if (declared_trailers.find(key) !=
                            declared_trailers.end()) {
                          dest.emplace(key, val);
                          trailer_header_count++;
                        }
                      })) {
      return false;
    }

    if (!line_reader.getline()) { return false; }
  }

  return true;
}

std::pair<size_t, size_t> trim(const char *b, const char *e, size_t left,
                                      size_t right) {
  while (b + left < e && is_space_or_tab(b[left])) {
    left++;
  }
  while (right > 0 && is_space_or_tab(b[right - 1])) {
    right--;
  }
  return std::make_pair(left, right);
}

std::string trim_copy(const std::string &s) {
  auto r = trim(s.data(), s.data() + s.size(), 0, s.size());
  return s.substr(r.first, r.second - r.first);
}

std::string trim_double_quotes_copy(const std::string &s) {
  if (s.length() >= 2 && s.front() == '"' && s.back() == '"') {
    return s.substr(1, s.size() - 2);
  }
  return s;
}

void
divide(const char *data, std::size_t size, char d,
       std::function<void(const char *, std::size_t, const char *, std::size_t)>
           fn) {
  const auto it = std::find(data, data + size, d);
  const auto found = static_cast<std::size_t>(it != data + size);
  const auto lhs_data = data;
  const auto lhs_size = static_cast<std::size_t>(it - data);
  const auto rhs_data = it + found;
  const auto rhs_size = size - lhs_size - found;

  fn(lhs_data, lhs_size, rhs_data, rhs_size);
}

void
divide(const std::string &str, char d,
       std::function<void(const char *, std::size_t, const char *, std::size_t)>
           fn) {
  divide(str.data(), str.size(), d, std::move(fn));
}

void split(const char *b, const char *e, char d,
                  std::function<void(const char *, const char *)> fn) {
  return split(b, e, d, (std::numeric_limits<size_t>::max)(), std::move(fn));
}

void split(const char *b, const char *e, char d, size_t m,
                  std::function<void(const char *, const char *)> fn) {
  size_t i = 0;
  size_t beg = 0;
  size_t count = 1;

  while (e ? (b + i < e) : (b[i] != '\0')) {
    if (b[i] == d && count < m) {
      auto r = trim(b, e, beg, i);
      if (r.first < r.second) { fn(&b[r.first], &b[r.second]); }
      beg = i + 1;
      count++;
    }
    i++;
  }

  if (i) {
    auto r = trim(b, e, beg, i);
    if (r.first < r.second) { fn(&b[r.first], &b[r.second]); }
  }
}

bool split_find(const char *b, const char *e, char d, size_t m,
                       std::function<bool(const char *, const char *)> fn) {
  size_t i = 0;
  size_t beg = 0;
  size_t count = 1;

  while (e ? (b + i < e) : (b[i] != '\0')) {
    if (b[i] == d && count < m) {
      auto r = trim(b, e, beg, i);
      if (r.first < r.second) {
        auto found = fn(&b[r.first], &b[r.second]);
        if (found) { return true; }
      }
      beg = i + 1;
      count++;
    }
    i++;
  }

  if (i) {
    auto r = trim(b, e, beg, i);
    if (r.first < r.second) {
      auto found = fn(&b[r.first], &b[r.second]);
      if (found) { return true; }
    }
  }

  return false;
}

bool split_find(const char *b, const char *e, char d,
                       std::function<bool(const char *, const char *)> fn) {
  return split_find(b, e, d, (std::numeric_limits<size_t>::max)(),
                    std::move(fn));
}

stream_line_reader::stream_line_reader(Stream &strm, char *fixed_buffer,
                                              size_t fixed_buffer_size)
    : strm_(strm), fixed_buffer_(fixed_buffer),
      fixed_buffer_size_(fixed_buffer_size) {}

const char *stream_line_reader::ptr() const {
  if (growable_buffer_.empty()) {
    return fixed_buffer_;
  } else {
    return growable_buffer_.data();
  }
}

size_t stream_line_reader::size() const {
  if (growable_buffer_.empty()) {
    return fixed_buffer_used_size_;
  } else {
    return growable_buffer_.size();
  }
}

bool stream_line_reader::end_with_crlf() const {
  auto end = ptr() + size();
  return size() >= 2 && end[-2] == '\r' && end[-1] == '\n';
}

bool stream_line_reader::getline() {
  fixed_buffer_used_size_ = 0;
  growable_buffer_.clear();

#ifndef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
  char prev_byte = 0;
#endif

  for (size_t i = 0;; i++) {
    if (size() >= CPPHTTPLIB_MAX_LINE_LENGTH) {
      // Treat exceptionally long lines as an error to
      // prevent infinite loops/memory exhaustion
      return false;
    }
    char byte;
    auto n = strm_.read(&byte, 1);

    if (n < 0) {
      return false;
    } else if (n == 0) {
      if (i == 0) {
        return false;
      } else {
        break;
      }
    }

    append(byte);

#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
    if (byte == '\n') { break; }
#else
    if (prev_byte == '\r' && byte == '\n') { break; }
    prev_byte = byte;
#endif
  }

  return true;
}

void stream_line_reader::append(char c) {
  if (fixed_buffer_used_size_ < fixed_buffer_size_ - 1) {
    fixed_buffer_[fixed_buffer_used_size_++] = c;
    fixed_buffer_[fixed_buffer_used_size_] = '\0';
  } else {
    if (growable_buffer_.empty()) {
      assert(fixed_buffer_[fixed_buffer_used_size_] == '\0');
      growable_buffer_.assign(fixed_buffer_, fixed_buffer_used_size_);
    }
    growable_buffer_ += c;
  }
}

mmap::mmap(const char *path) { open(path); }

mmap::~mmap() { close(); }

bool mmap::open(const char *path) {
  close();

#if defined(_WIN32)
  auto wpath = u8string_to_wstring(path);
  if (wpath.empty()) { return false; }

  hFile_ = ::CreateFile2(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ,
                         OPEN_EXISTING, NULL);

  if (hFile_ == INVALID_HANDLE_VALUE) { return false; }

  LARGE_INTEGER size{};
  if (!::GetFileSizeEx(hFile_, &size)) { return false; }
  // If the following line doesn't compile due to QuadPart, update Windows SDK.
  // See:
  // https://github.com/yhirose/cpp-httplib/issues/1903#issuecomment-2316520721
  if (static_cast<ULONGLONG>(size.QuadPart) >
      (std::numeric_limits<decltype(size_)>::max)()) {
    // `size_t` might be 32-bits, on 32-bits Windows.
    return false;
  }
  size_ = static_cast<size_t>(size.QuadPart);

  hMapping_ =
      ::CreateFileMappingFromApp(hFile_, NULL, PAGE_READONLY, size_, NULL);

  // Special treatment for an empty file...
  if (hMapping_ == NULL && size_ == 0) {
    close();
    is_open_empty_file = true;
    return true;
  }

  if (hMapping_ == NULL) {
    close();
    return false;
  }

  addr_ = ::MapViewOfFileFromApp(hMapping_, FILE_MAP_READ, 0, 0);

  if (addr_ == nullptr) {
    close();
    return false;
  }
#else
  fd_ = ::open(path, O_RDONLY);
  if (fd_ == -1) { return false; }

  struct stat sb;
  if (fstat(fd_, &sb) == -1) {
    close();
    return false;
  }
  size_ = static_cast<size_t>(sb.st_size);

  addr_ = ::mmap(NULL, size_, PROT_READ, MAP_PRIVATE, fd_, 0);

  // Special treatment for an empty file...
  if (addr_ == MAP_FAILED && size_ == 0) {
    close();
    is_open_empty_file = true;
    return false;
  }
#endif

  return true;
}

bool mmap::is_open() const {
  return is_open_empty_file ? true : addr_ != nullptr;
}

size_t mmap::size() const { return size_; }

const char *mmap::data() const {
  return is_open_empty_file ? "" : static_cast<const char *>(addr_);
}

void mmap::close() {
#if defined(_WIN32)
  if (addr_) {
    ::UnmapViewOfFile(addr_);
    addr_ = nullptr;
  }

  if (hMapping_) {
    ::CloseHandle(hMapping_);
    hMapping_ = NULL;
  }

  if (hFile_ != INVALID_HANDLE_VALUE) {
    ::CloseHandle(hFile_);
    hFile_ = INVALID_HANDLE_VALUE;
  }

  is_open_empty_file = false;
#else
  if (addr_ != nullptr) {
    munmap(addr_, size_);
    addr_ = nullptr;
  }

  if (fd_ != -1) {
    ::close(fd_);
    fd_ = -1;
  }
#endif
  size_ = 0;
}
int close_socket(socket_t sock) {
#ifdef _WIN32
  return closesocket(sock);
#else
  return close(sock);
#endif
}

template <typename T> ssize_t handle_EINTR(T fn) {
  ssize_t res = 0;
  while (true) {
    res = fn();
    if (res < 0 && errno == EINTR) {
      std::this_thread::sleep_for(std::chrono::microseconds{1});
      continue;
    }
    break;
  }
  return res;
}

ssize_t read_socket(socket_t sock, void *ptr, size_t size, int flags) {
  return handle_EINTR([&]() {
    return recv(sock,
#ifdef _WIN32
                static_cast<char *>(ptr), static_cast<int>(size),
#else
                ptr, size,
#endif
                flags);
  });
}

ssize_t send_socket(socket_t sock, const void *ptr, size_t size,
                           int flags) {
  return handle_EINTR([&]() {
    return send(sock,
#ifdef _WIN32
                static_cast<const char *>(ptr), static_cast<int>(size),
#else
                ptr, size,
#endif
                flags);
  });
}

int poll_wrapper(struct pollfd *fds, nfds_t nfds, int timeout) {
#ifdef _WIN32
  return ::WSAPoll(fds, nfds, timeout);
#else
  return ::poll(fds, nfds, timeout);
#endif
}

ssize_t select_impl(socket_t sock, short events, time_t sec,
                           time_t usec) {
  struct pollfd pfd;
  pfd.fd = sock;
  pfd.events = events;
  pfd.revents = 0;

  auto timeout = static_cast<int>(sec * 1000 + usec / 1000);

  return handle_EINTR([&]() { return poll_wrapper(&pfd, 1, timeout); });
}

ssize_t select_read(socket_t sock, time_t sec, time_t usec) {
  return select_impl(sock, POLLIN, sec, usec);
}

ssize_t select_write(socket_t sock, time_t sec, time_t usec) {
  return select_impl(sock, POLLOUT, sec, usec);
}

Error wait_until_socket_is_ready(socket_t sock, time_t sec,
                                        time_t usec) {
  struct pollfd pfd_read;
  pfd_read.fd = sock;
  pfd_read.events = POLLIN | POLLOUT;
  pfd_read.revents = 0;

  auto timeout = static_cast<int>(sec * 1000 + usec / 1000);

  auto poll_res =
      handle_EINTR([&]() { return poll_wrapper(&pfd_read, 1, timeout); });

  if (poll_res == 0) { return Error::ConnectionTimeout; }

  if (poll_res > 0 && pfd_read.revents & (POLLIN | POLLOUT)) {
    auto error = 0;
    socklen_t len = sizeof(error);
    auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                          reinterpret_cast<char *>(&error), &len);
    auto successful = res >= 0 && !error;
    return successful ? Error::Success : Error::Connection;
  }

  return Error::Connection;
}

bool is_socket_alive(socket_t sock) {
  const auto val = detail::select_read(sock, 0, 0);
  if (val == 0) {
    return true;
  } else if (val < 0 && errno == EBADF) {
    return false;
  }
  char buf[1];
  return detail::read_socket(sock, &buf[0], sizeof(buf), MSG_PEEK) > 0;
}

class SocketStream final : public Stream {
public:
  SocketStream(socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
               time_t write_timeout_sec, time_t write_timeout_usec,
               time_t max_timeout_msec = 0,
               std::chrono::time_point<std::chrono::steady_clock> start_time =
                   (std::chrono::steady_clock::time_point::min)());
  ~SocketStream() override;

  bool is_readable() const override;
  bool wait_readable() const override;
  bool wait_writable() const override;
  bool is_peer_alive() const override;
  ssize_t read(char *ptr, size_t size) override;
  ssize_t write(const char *ptr, size_t size) override;
  void get_remote_ip_and_port(std::string &ip, int &port) const override;
  void get_local_ip_and_port(std::string &ip, int &port) const override;
  socket_t socket() const override;
  time_t duration() const override;
  void set_read_timeout(time_t sec, time_t usec = 0) override;

private:
  socket_t sock_;
  time_t read_timeout_sec_;
  time_t read_timeout_usec_;
  time_t write_timeout_sec_;
  time_t write_timeout_usec_;
  time_t max_timeout_msec_;
  const std::chrono::time_point<std::chrono::steady_clock> start_time_;

  std::vector<char> read_buff_;
  size_t read_buff_off_ = 0;
  size_t read_buff_content_size_ = 0;

  static const size_t read_buff_size_ = 1024l * 4;
};

bool keep_alive(const std::atomic<socket_t> &svr_sock, socket_t sock,
                       time_t keep_alive_timeout_sec) {
  using namespace std::chrono;

  const auto interval_usec =
      CPPHTTPLIB_KEEPALIVE_TIMEOUT_CHECK_INTERVAL_USECOND;

  // Avoid expensive `steady_clock::now()` call for the first time
  if (select_read(sock, 0, interval_usec) > 0) { return true; }

  const auto start = steady_clock::now() - microseconds{interval_usec};
  const auto timeout = seconds{keep_alive_timeout_sec};

  while (true) {
    if (svr_sock == INVALID_SOCKET) {
      break; // Server socket is closed
    }

    auto val = select_read(sock, 0, interval_usec);
    if (val < 0) {
      break; // Ssocket error
    } else if (val == 0) {
      if (steady_clock::now() - start > timeout) {
        break; // Timeout
      }
    } else {
      return true; // Ready for read
    }
  }

  return false;
}

template <typename T>
bool
process_server_socket_core(const std::atomic<socket_t> &svr_sock, socket_t sock,
                           size_t keep_alive_max_count,
                           time_t keep_alive_timeout_sec, T callback) {
  assert(keep_alive_max_count > 0);
  auto ret = false;
  auto count = keep_alive_max_count;
  while (count > 0 && keep_alive(svr_sock, sock, keep_alive_timeout_sec)) {
    auto close_connection = count == 1;
    auto connection_closed = false;
    ret = callback(close_connection, connection_closed);
    if (!ret || connection_closed) { break; }
    count--;
  }
  return ret;
}

template <typename T>
bool
process_server_socket(const std::atomic<socket_t> &svr_sock, socket_t sock,
                      size_t keep_alive_max_count,
                      time_t keep_alive_timeout_sec, time_t read_timeout_sec,
                      time_t read_timeout_usec, time_t write_timeout_sec,
                      time_t write_timeout_usec, T callback) {
  return process_server_socket_core(
      svr_sock, sock, keep_alive_max_count, keep_alive_timeout_sec,
      [&](bool close_connection, bool &connection_closed) {
        SocketStream strm(sock, read_timeout_sec, read_timeout_usec,
                          write_timeout_sec, write_timeout_usec);
        return callback(strm, close_connection, connection_closed);
      });
}

bool process_client_socket(
    socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
    time_t write_timeout_sec, time_t write_timeout_usec,
    time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &)> callback) {
  SocketStream strm(sock, read_timeout_sec, read_timeout_usec,
                    write_timeout_sec, write_timeout_usec, max_timeout_msec,
                    start_time);
  return callback(strm);
}

int shutdown_socket(socket_t sock) {
#ifdef _WIN32
  return shutdown(sock, SD_BOTH);
#else
  return shutdown(sock, SHUT_RDWR);
#endif
}

std::string escape_abstract_namespace_unix_domain(const std::string &s) {
  if (s.size() > 1 && s[0] == '\0') {
    auto ret = s;
    ret[0] = '@';
    return ret;
  }
  return s;
}

std::string
unescape_abstract_namespace_unix_domain(const std::string &s) {
  if (s.size() > 1 && s[0] == '@') {
    auto ret = s;
    ret[0] = '\0';
    return ret;
  }
  return s;
}

int getaddrinfo_with_timeout(const char *node, const char *service,
                                    const struct addrinfo *hints,
                                    struct addrinfo **res, time_t timeout_sec) {
#ifdef CPPHTTPLIB_USE_NON_BLOCKING_GETADDRINFO
  if (timeout_sec <= 0) {
    // No timeout specified, use standard getaddrinfo
    return getaddrinfo(node, service, hints, res);
  }

#ifdef _WIN32
  // Windows-specific implementation using GetAddrInfoEx with overlapped I/O
  OVERLAPPED overlapped = {0};
  HANDLE event = CreateEventW(nullptr, TRUE, FALSE, nullptr);
  if (!event) { return EAI_FAIL; }

  overlapped.hEvent = event;

  PADDRINFOEXW result_addrinfo = nullptr;
  HANDLE cancel_handle = nullptr;

  ADDRINFOEXW hints_ex = {0};
  if (hints) {
    hints_ex.ai_flags = hints->ai_flags;
    hints_ex.ai_family = hints->ai_family;
    hints_ex.ai_socktype = hints->ai_socktype;
    hints_ex.ai_protocol = hints->ai_protocol;
  }

  auto wnode = u8string_to_wstring(node);
  auto wservice = u8string_to_wstring(service);

  auto ret = ::GetAddrInfoExW(wnode.data(), wservice.data(), NS_DNS, nullptr,
                              hints ? &hints_ex : nullptr, &result_addrinfo,
                              nullptr, &overlapped, nullptr, &cancel_handle);

  if (ret == WSA_IO_PENDING) {
    auto wait_result =
        ::WaitForSingleObject(event, static_cast<DWORD>(timeout_sec * 1000));
    if (wait_result == WAIT_TIMEOUT) {
      if (cancel_handle) { ::GetAddrInfoExCancel(&cancel_handle); }
      ::CloseHandle(event);
      return EAI_AGAIN;
    }

    DWORD bytes_returned;
    if (!::GetOverlappedResult((HANDLE)INVALID_SOCKET, &overlapped,
                               &bytes_returned, FALSE)) {
      ::CloseHandle(event);
      return ::WSAGetLastError();
    }
  }

  ::CloseHandle(event);

  if (ret == NO_ERROR || ret == WSA_IO_PENDING) {
    *res = reinterpret_cast<struct addrinfo *>(result_addrinfo);
    return 0;
  }

  return ret;
#elif TARGET_OS_MAC
  if (!node) { return EAI_NONAME; }
  // macOS implementation using CFHost API for asynchronous DNS resolution
  CFStringRef hostname_ref = CFStringCreateWithCString(
      kCFAllocatorDefault, node, kCFStringEncodingUTF8);
  if (!hostname_ref) { return EAI_MEMORY; }

  CFHostRef host_ref = CFHostCreateWithName(kCFAllocatorDefault, hostname_ref);
  CFRelease(hostname_ref);
  if (!host_ref) { return EAI_MEMORY; }

  // Set up context for callback
  struct CFHostContext {
    bool completed = false;
    bool success = false;
    CFArrayRef addresses = nullptr;
    std::mutex mutex;
    std::condition_variable cv;
  } context;

  CFHostClientContext client_context;
  memset(&client_context, 0, sizeof(client_context));
  client_context.info = &context;

  // Set callback
  auto callback = [](CFHostRef theHost, CFHostInfoType /*typeInfo*/,
                     const CFStreamError *error, void *info) {
    auto ctx = static_cast<CFHostContext *>(info);
    std::lock_guard<std::mutex> lock(ctx->mutex);

    if (error && error->error != 0) {
      ctx->success = false;
    } else {
      Boolean hasBeenResolved;
      ctx->addresses = CFHostGetAddressing(theHost, &hasBeenResolved);
      if (ctx->addresses && hasBeenResolved) {
        CFRetain(ctx->addresses);
        ctx->success = true;
      } else {
        ctx->success = false;
      }
    }
    ctx->completed = true;
    ctx->cv.notify_one();
  };

  if (!CFHostSetClient(host_ref, callback, &client_context)) {
    CFRelease(host_ref);
    return EAI_SYSTEM;
  }

  // Schedule on run loop
  CFRunLoopRef run_loop = CFRunLoopGetCurrent();
  CFHostScheduleWithRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);

  // Start resolution
  CFStreamError stream_error;
  if (!CFHostStartInfoResolution(host_ref, kCFHostAddresses, &stream_error)) {
    CFHostUnscheduleFromRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);
    CFRelease(host_ref);
    return EAI_FAIL;
  }

  // Wait for completion with timeout
  auto timeout_time =
      std::chrono::steady_clock::now() + std::chrono::seconds(timeout_sec);
  bool timed_out = false;

  {
    std::unique_lock<std::mutex> lock(context.mutex);

    while (!context.completed) {
      auto now = std::chrono::steady_clock::now();
      if (now >= timeout_time) {
        timed_out = true;
        break;
      }

      // Run the runloop for a short time
      lock.unlock();
      CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.1, true);
      lock.lock();
    }
  }

  // Clean up
  CFHostUnscheduleFromRunLoop(host_ref, run_loop, kCFRunLoopDefaultMode);
  CFHostSetClient(host_ref, nullptr, nullptr);

  if (timed_out || !context.completed) {
    CFHostCancelInfoResolution(host_ref, kCFHostAddresses);
    CFRelease(host_ref);
    return EAI_AGAIN;
  }

  if (!context.success || !context.addresses) {
    CFRelease(host_ref);
    return EAI_NODATA;
  }

  // Convert CFArray to addrinfo
  CFIndex count = CFArrayGetCount(context.addresses);
  if (count == 0) {
    CFRelease(context.addresses);
    CFRelease(host_ref);
    return EAI_NODATA;
  }

  struct addrinfo *result_addrinfo = nullptr;
  struct addrinfo **current = &result_addrinfo;

  for (CFIndex i = 0; i < count; i++) {
    CFDataRef addr_data =
        static_cast<CFDataRef>(CFArrayGetValueAtIndex(context.addresses, i));
    if (!addr_data) continue;

    const struct sockaddr *sockaddr_ptr =
        reinterpret_cast<const struct sockaddr *>(CFDataGetBytePtr(addr_data));
    socklen_t sockaddr_len = static_cast<socklen_t>(CFDataGetLength(addr_data));

    // Allocate addrinfo structure
    *current = static_cast<struct addrinfo *>(malloc(sizeof(struct addrinfo)));
    if (!*current) {
      freeaddrinfo(result_addrinfo);
      CFRelease(context.addresses);
      CFRelease(host_ref);
      return EAI_MEMORY;
    }

    memset(*current, 0, sizeof(struct addrinfo));

    // Set up addrinfo fields
    (*current)->ai_family = sockaddr_ptr->sa_family;
    (*current)->ai_socktype = hints ? hints->ai_socktype : SOCK_STREAM;
    (*current)->ai_protocol = hints ? hints->ai_protocol : IPPROTO_TCP;
    (*current)->ai_addrlen = sockaddr_len;

    // Copy sockaddr
    (*current)->ai_addr = static_cast<struct sockaddr *>(malloc(sockaddr_len));
    if (!(*current)->ai_addr) {
      freeaddrinfo(result_addrinfo);
      CFRelease(context.addresses);
      CFRelease(host_ref);
      return EAI_MEMORY;
    }
    memcpy((*current)->ai_addr, sockaddr_ptr, sockaddr_len);

    // Set port if service is specified
    if (service && *service) {
      int port = 0;
      if (parse_port(service, strlen(service), port)) {
        if (sockaddr_ptr->sa_family == AF_INET) {
          reinterpret_cast<struct sockaddr_in *>((*current)->ai_addr)
              ->sin_port = htons(static_cast<uint16_t>(port));
        } else if (sockaddr_ptr->sa_family == AF_INET6) {
          reinterpret_cast<struct sockaddr_in6 *>((*current)->ai_addr)
              ->sin6_port = htons(static_cast<uint16_t>(port));
        }
      }
    }

    current = &((*current)->ai_next);
  }

  CFRelease(context.addresses);
  CFRelease(host_ref);

  *res = result_addrinfo;
  return 0;
#elif defined(_GNU_SOURCE) && defined(__GLIBC__) &&                            \
    (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2))
  // Linux implementation using getaddrinfo_a for asynchronous DNS resolution
  struct gaicb request;
  struct gaicb *requests[1] = {&request};
  struct sigevent sevp;
  struct timespec timeout;

  // Initialize the request structure
  memset(&request, 0, sizeof(request));
  request.ar_name = node;
  request.ar_service = service;
  request.ar_request = hints;

  // Set up timeout
  timeout.tv_sec = timeout_sec;
  timeout.tv_nsec = 0;

  // Initialize sigevent structure (not used, but required)
  memset(&sevp, 0, sizeof(sevp));
  sevp.sigev_notify = SIGEV_NONE;

  // Start asynchronous resolution
  int start_result = getaddrinfo_a(GAI_NOWAIT, requests, 1, &sevp);
  if (start_result != 0) { return start_result; }

  // Wait for completion with timeout
  int wait_result =
      gai_suspend((const struct gaicb *const *)requests, 1, &timeout);

  if (wait_result == 0 || wait_result == EAI_ALLDONE) {
    // Completed successfully, get the result
    int gai_result = gai_error(&request);
    if (gai_result == 0) {
      *res = request.ar_result;
      return 0;
    } else {
      // Clean up on error
      if (request.ar_result) { freeaddrinfo(request.ar_result); }
      return gai_result;
    }
  } else if (wait_result == EAI_AGAIN) {
    // Timeout occurred, cancel the request
    gai_cancel(&request);
    return EAI_AGAIN;
  } else {
    // Other error occurred
    gai_cancel(&request);
    return wait_result;
  }
#else
  // Fallback implementation using thread-based timeout for other Unix systems

  struct GetAddrInfoState {
    ~GetAddrInfoState() {
      if (info) { freeaddrinfo(info); }
    }

    std::mutex mutex;
    std::condition_variable result_cv;
    bool completed = false;
    int result = EAI_SYSTEM;
    std::string node;
    std::string service;
    struct addrinfo hints;
    struct addrinfo *info = nullptr;
  };

  // Allocate on the heap, so the resolver thread can keep using the data.
  auto state = std::make_shared<GetAddrInfoState>();
  if (node) { state->node = node; }
  state->service = service;
  state->hints = *hints;

  std::thread resolve_thread([state]() {
    auto thread_result =
        getaddrinfo(state->node.c_str(), state->service.c_str(), &state->hints,
                    &state->info);

    std::lock_guard<std::mutex> lock(state->mutex);
    state->result = thread_result;
    state->completed = true;
    state->result_cv.notify_one();
  });

  // Wait for completion or timeout
  std::unique_lock<std::mutex> lock(state->mutex);
  auto finished =
      state->result_cv.wait_for(lock, std::chrono::seconds(timeout_sec),
                                [&] { return state->completed; });

  if (finished) {
    // Operation completed within timeout
    resolve_thread.join();
    *res = state->info;
    state->info = nullptr; // Pass ownership to caller
    return state->result;
  } else {
    // Timeout occurred
    resolve_thread.detach(); // Let the thread finish in background
    return EAI_AGAIN;        // Return timeout error
  }
#endif
#else
  (void)(timeout_sec); // Unused parameter for non-blocking getaddrinfo
  return getaddrinfo(node, service, hints, res);
#endif
}

template <typename BindOrConnect>
socket_t create_socket(const std::string &host, const std::string &ip, int port,
                       int address_family, int socket_flags, bool tcp_nodelay,
                       bool ipv6_v6only, SocketOptions socket_options,
                       BindOrConnect bind_or_connect, time_t timeout_sec = 0) {
  // Get address info
  const char *node = nullptr;
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = IPPROTO_IP;

  if (!ip.empty()) {
    node = ip.c_str();
    // Ask getaddrinfo to convert IP in c-string to address
    hints.ai_family = AF_UNSPEC;
    hints.ai_flags = AI_NUMERICHOST;
  } else {
    if (!host.empty()) { node = host.c_str(); }
    hints.ai_family = address_family;
    hints.ai_flags = socket_flags;
  }

#if !defined(_WIN32) || defined(CPPHTTPLIB_HAVE_AFUNIX_H)
  if (hints.ai_family == AF_UNIX) {
    const auto addrlen = host.length();
    if (addrlen > sizeof(sockaddr_un::sun_path)) { return INVALID_SOCKET; }

#ifdef SOCK_CLOEXEC
    auto sock = socket(hints.ai_family, hints.ai_socktype | SOCK_CLOEXEC,
                       hints.ai_protocol);
#else
    auto sock = socket(hints.ai_family, hints.ai_socktype, hints.ai_protocol);
#endif

    if (sock != INVALID_SOCKET) {
      sockaddr_un addr{};
      addr.sun_family = AF_UNIX;

      auto unescaped_host = unescape_abstract_namespace_unix_domain(host);
      std::copy(unescaped_host.begin(), unescaped_host.end(), addr.sun_path);

      hints.ai_addr = reinterpret_cast<sockaddr *>(&addr);
      hints.ai_addrlen = static_cast<socklen_t>(
          sizeof(addr) - sizeof(addr.sun_path) + addrlen);

#ifndef SOCK_CLOEXEC
#ifndef _WIN32
      fcntl(sock, F_SETFD, FD_CLOEXEC);
#endif
#endif

      if (socket_options) { socket_options(sock); }

#ifdef _WIN32
      // Setting SO_REUSEADDR seems not to work well with AF_UNIX on windows, so
      // remove the option.
      detail::set_socket_opt(sock, SOL_SOCKET, SO_REUSEADDR, 0);
#endif

      bool dummy;
      if (!bind_or_connect(sock, hints, dummy)) {
        close_socket(sock);
        sock = INVALID_SOCKET;
      }
    }
    return sock;
  }
#endif

  auto service = std::to_string(port);

  if (getaddrinfo_with_timeout(node, service.c_str(), &hints, &result,
                               timeout_sec)) {
#if defined __linux__ && !defined __ANDROID__
    res_init();
#endif
    return INVALID_SOCKET;
  }
  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  for (auto rp = result; rp; rp = rp->ai_next) {
    // Create a socket
#ifdef _WIN32
    auto sock =
        WSASocketW(rp->ai_family, rp->ai_socktype, rp->ai_protocol, nullptr, 0,
                   WSA_FLAG_NO_HANDLE_INHERIT | WSA_FLAG_OVERLAPPED);
    /**
     * Since the WSA_FLAG_NO_HANDLE_INHERIT is only supported on Windows 7 SP1
     * and above the socket creation fails on older Windows Systems.
     *
     * Let's try to create a socket the old way in this case.
     *
     * Reference:
     * https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-wsasocketa
     *
     * WSA_FLAG_NO_HANDLE_INHERIT:
     * This flag is supported on Windows 7 with SP1, Windows Server 2008 R2 with
     * SP1, and later
     *
     */
    if (sock == INVALID_SOCKET) {
      sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
    }
#else

#ifdef SOCK_CLOEXEC
    auto sock =
        socket(rp->ai_family, rp->ai_socktype | SOCK_CLOEXEC, rp->ai_protocol);
#else
    auto sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
#endif

#endif
    if (sock == INVALID_SOCKET) { continue; }

#if !defined _WIN32 && !defined SOCK_CLOEXEC
    if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1) {
      close_socket(sock);
      continue;
    }
#endif

    if (tcp_nodelay) { set_socket_opt(sock, IPPROTO_TCP, TCP_NODELAY, 1); }

    if (rp->ai_family == AF_INET6) {
      set_socket_opt(sock, IPPROTO_IPV6, IPV6_V6ONLY, ipv6_v6only ? 1 : 0);
    }

    if (socket_options) { socket_options(sock); }

    // bind or connect
    auto quit = false;
    if (bind_or_connect(sock, *rp, quit)) { return sock; }

    close_socket(sock);

    if (quit) { break; }
  }

  return INVALID_SOCKET;
}

void set_nonblocking(socket_t sock, bool nonblocking) {
#ifdef _WIN32
  auto flags = nonblocking ? 1UL : 0UL;
  ioctlsocket(sock, FIONBIO, &flags);
#else
  auto flags = fcntl(sock, F_GETFL, 0);
  fcntl(sock, F_SETFL,
        nonblocking ? (flags | O_NONBLOCK) : (flags & (~O_NONBLOCK)));
#endif
}

bool is_connection_error() {
#ifdef _WIN32
  return WSAGetLastError() != WSAEWOULDBLOCK;
#else
  return errno != EINPROGRESS;
#endif
}

bool bind_ip_address(socket_t sock, const std::string &host) {
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_family = AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;

  if (getaddrinfo_with_timeout(host.c_str(), "0", &hints, &result, 0)) {
    return false;
  }

  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  auto ret = false;
  for (auto rp = result; rp; rp = rp->ai_next) {
    const auto &ai = *rp;
    if (!::bind(sock, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen))) {
      ret = true;
      break;
    }
  }

  return ret;
}

#if !defined _WIN32 && !defined ANDROID && !defined _AIX && !defined __MVS__
#define USE_IF2IP
#endif

#ifdef USE_IF2IP
std::string if2ip(int address_family, const std::string &ifn) {
  struct ifaddrs *ifap;
  getifaddrs(&ifap);
  auto se = detail::scope_exit([&] { freeifaddrs(ifap); });

  std::string addr_candidate;
  for (auto ifa = ifap; ifa; ifa = ifa->ifa_next) {
    if (ifa->ifa_addr && ifn == ifa->ifa_name &&
        (AF_UNSPEC == address_family ||
         ifa->ifa_addr->sa_family == address_family)) {
      if (ifa->ifa_addr->sa_family == AF_INET) {
        auto sa = reinterpret_cast<struct sockaddr_in *>(ifa->ifa_addr);
        char buf[INET_ADDRSTRLEN];
        if (inet_ntop(AF_INET, &sa->sin_addr, buf, INET_ADDRSTRLEN)) {
          return std::string(buf, INET_ADDRSTRLEN);
        }
      } else if (ifa->ifa_addr->sa_family == AF_INET6) {
        auto sa = reinterpret_cast<struct sockaddr_in6 *>(ifa->ifa_addr);
        if (!IN6_IS_ADDR_LINKLOCAL(&sa->sin6_addr)) {
          char buf[INET6_ADDRSTRLEN] = {};
          if (inet_ntop(AF_INET6, &sa->sin6_addr, buf, INET6_ADDRSTRLEN)) {
            // equivalent to mac's IN6_IS_ADDR_UNIQUE_LOCAL
            auto s6_addr_head = sa->sin6_addr.s6_addr[0];
            if (s6_addr_head == 0xfc || s6_addr_head == 0xfd) {
              addr_candidate = std::string(buf, INET6_ADDRSTRLEN);
            } else {
              return std::string(buf, INET6_ADDRSTRLEN);
            }
          }
        }
      }
    }
  }
  return addr_candidate;
}
#endif

socket_t create_client_socket(
    const std::string &host, const std::string &ip, int port,
    int address_family, bool tcp_nodelay, bool ipv6_v6only,
    SocketOptions socket_options, time_t connection_timeout_sec,
    time_t connection_timeout_usec, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, const std::string &intf, Error &error) {
  auto sock = create_socket(
      host, ip, port, address_family, 0, tcp_nodelay, ipv6_v6only,
      std::move(socket_options),
      [&](socket_t sock2, struct addrinfo &ai, bool &quit) -> bool {
        if (!intf.empty()) {
#ifdef USE_IF2IP
          auto ip_from_if = if2ip(address_family, intf);
          if (ip_from_if.empty()) { ip_from_if = intf; }
          if (!bind_ip_address(sock2, ip_from_if)) {
            error = Error::BindIPAddress;
            return false;
          }
#endif
        }

        set_nonblocking(sock2, true);

        auto ret =
            ::connect(sock2, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen));

        if (ret < 0) {
          if (is_connection_error()) {
            error = Error::Connection;
            return false;
          }
          error = wait_until_socket_is_ready(sock2, connection_timeout_sec,
                                             connection_timeout_usec);
          if (error != Error::Success) {
            if (error == Error::ConnectionTimeout) { quit = true; }
            return false;
          }
        }

        set_nonblocking(sock2, false);
        set_socket_opt_time(sock2, SOL_SOCKET, SO_RCVTIMEO, read_timeout_sec,
                            read_timeout_usec);
        set_socket_opt_time(sock2, SOL_SOCKET, SO_SNDTIMEO, write_timeout_sec,
                            write_timeout_usec);

        error = Error::Success;
        return true;
      },
      connection_timeout_sec); // Pass DNS timeout

  if (sock != INVALID_SOCKET) {
    error = Error::Success;
  } else {
    if (error == Error::Success) { error = Error::Connection; }
  }

  return sock;
}

bool get_ip_and_port(const struct sockaddr_storage &addr,
                            socklen_t addr_len, std::string &ip, int &port) {
  if (addr.ss_family == AF_INET) {
    port = ntohs(reinterpret_cast<const struct sockaddr_in *>(&addr)->sin_port);
  } else if (addr.ss_family == AF_INET6) {
    port =
        ntohs(reinterpret_cast<const struct sockaddr_in6 *>(&addr)->sin6_port);
  } else {
    return false;
  }

  std::array<char, NI_MAXHOST> ipstr{};
  if (getnameinfo(reinterpret_cast<const struct sockaddr *>(&addr), addr_len,
                  ipstr.data(), static_cast<socklen_t>(ipstr.size()), nullptr,
                  0, NI_NUMERICHOST)) {
    return false;
  }

  ip = ipstr.data();
  return true;
}

void get_local_ip_and_port(socket_t sock, std::string &ip, int &port) {
  struct sockaddr_storage addr;
  socklen_t addr_len = sizeof(addr);
  if (!getsockname(sock, reinterpret_cast<struct sockaddr *>(&addr),
                   &addr_len)) {
    get_ip_and_port(addr, addr_len, ip, port);
  }
}

void get_remote_ip_and_port(socket_t sock, std::string &ip, int &port) {
  struct sockaddr_storage addr;
  socklen_t addr_len = sizeof(addr);

  if (!getpeername(sock, reinterpret_cast<struct sockaddr *>(&addr),
                   &addr_len)) {
#ifndef _WIN32
    if (addr.ss_family == AF_UNIX) {
#if defined(__linux__)
      struct ucred ucred;
      socklen_t len = sizeof(ucred);
      if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &ucred, &len) == 0) {
        port = ucred.pid;
      }
#elif defined(SOL_LOCAL) && defined(SO_PEERPID)
      pid_t pid;
      socklen_t len = sizeof(pid);
      if (getsockopt(sock, SOL_LOCAL, SO_PEERPID, &pid, &len) == 0) {
        port = pid;
      }
#endif
      return;
    }
#endif
    get_ip_and_port(addr, addr_len, ip, port);
  }
}

constexpr unsigned int str2tag_core(const char *s, size_t l,
                                           unsigned int h) {
  return (l == 0)
             ? h
             : str2tag_core(
                   s + 1, l - 1,
                   // Unsets the 6 high bits of h, therefore no overflow happens
                   (((std::numeric_limits<unsigned int>::max)() >> 6) &
                    h * 33) ^
                       static_cast<unsigned char>(*s));
}

unsigned int str2tag(const std::string &s) {
  return str2tag_core(s.data(), s.size(), 0);
}

namespace udl {

constexpr unsigned int operator""_t(const char *s, size_t l) {
  return str2tag_core(s, l, 0);
}

} // namespace udl

std::string
find_content_type(const std::string &path,
                  const std::map<std::string, std::string> &user_data,
                  const std::string &default_content_type) {
  auto ext = file_extension(path);

  auto it = user_data.find(ext);
  if (it != user_data.end()) { return it->second; }

  using udl::operator""_t;

  switch (str2tag(ext)) {
  default: return default_content_type;

  case "css"_t: return "text/css";
  case "csv"_t: return "text/csv";
  case "htm"_t:
  case "html"_t: return "text/html";
  case "js"_t:
  case "mjs"_t: return "text/javascript";
  case "txt"_t: return "text/plain";
  case "vtt"_t: return "text/vtt";

  case "apng"_t: return "image/apng";
  case "avif"_t: return "image/avif";
  case "bmp"_t: return "image/bmp";
  case "gif"_t: return "image/gif";
  case "png"_t: return "image/png";
  case "svg"_t: return "image/svg+xml";
  case "webp"_t: return "image/webp";
  case "ico"_t: return "image/x-icon";
  case "tif"_t: return "image/tiff";
  case "tiff"_t: return "image/tiff";
  case "jpg"_t:
  case "jpeg"_t: return "image/jpeg";

  case "mp4"_t: return "video/mp4";
  case "mpeg"_t: return "video/mpeg";
  case "webm"_t: return "video/webm";

  case "mp3"_t: return "audio/mp3";
  case "mpga"_t: return "audio/mpeg";
  case "weba"_t: return "audio/webm";
  case "wav"_t: return "audio/wave";

  case "otf"_t: return "font/otf";
  case "ttf"_t: return "font/ttf";
  case "woff"_t: return "font/woff";
  case "woff2"_t: return "font/woff2";

  case "7z"_t: return "application/x-7z-compressed";
  case "atom"_t: return "application/atom+xml";
  case "pdf"_t: return "application/pdf";
  case "json"_t: return "application/json";
  case "rss"_t: return "application/rss+xml";
  case "tar"_t: return "application/x-tar";
  case "xht"_t:
  case "xhtml"_t: return "application/xhtml+xml";
  case "xslt"_t: return "application/xslt+xml";
  case "xml"_t: return "application/xml";
  case "gz"_t: return "application/gzip";
  case "zip"_t: return "application/zip";
  case "wasm"_t: return "application/wasm";
  }
}

std::string
extract_media_type(const std::string &content_type,
                   std::map<std::string, std::string> *params = nullptr) {
  // Extract type/subtype from Content-Type value (RFC 2045)
  // e.g. "application/json; charset=utf-8" -> "application/json"
  auto media_type = content_type;
  auto semicolon_pos = media_type.find(';');
  if (semicolon_pos != std::string::npos) {
    auto param_str = media_type.substr(semicolon_pos + 1);
    media_type = media_type.substr(0, semicolon_pos);

    if (params) {
      // Parse parameters: key=value pairs separated by ';'
      split(param_str.data(), param_str.data() + param_str.size(), ';',
            [&](const char *b, const char *e) {
              std::string key;
              std::string val;
              split(b, e, '=', [&](const char *b2, const char *e2) {
                if (key.empty()) {
                  key.assign(b2, e2);
                } else {
                  val.assign(b2, e2);
                }
              });
              if (!key.empty()) {
                params->emplace(trim_copy(key), trim_double_quotes_copy(val));
              }
            });
    }
  }

  // Trim whitespace from media type
  return trim_copy(media_type);
}

bool can_compress_content_type(const std::string &content_type) {
  using udl::operator""_t;

  auto mime_type = extract_media_type(content_type);
  auto tag = str2tag(mime_type);

  switch (tag) {
  case "image/svg+xml"_t:
  case "application/javascript"_t:
  case "application/x-javascript"_t:
  case "application/json"_t:
  case "application/ld+json"_t:
  case "application/xml"_t:
  case "application/xhtml+xml"_t:
  case "application/rss+xml"_t:
  case "application/atom+xml"_t:
  case "application/xslt+xml"_t:
  case "application/protobuf"_t: return true;

  case "text/event-stream"_t: return false;

  default: return !mime_type.rfind("text/", 0);
  }
}

bool parse_quality(const char *b, const char *e, std::string &token,
                          double &quality) {
  quality = 1.0;
  token.clear();

  // Split on first ';': left = token name, right = parameters
  const char *params_b = nullptr;
  std::size_t params_len = 0;

  divide(
      b, static_cast<std::size_t>(e - b), ';',
      [&](const char *lb, std::size_t llen, const char *rb, std::size_t rlen) {
        auto r = trim(lb, lb + llen, 0, llen);
        if (r.first < r.second) { token.assign(lb + r.first, lb + r.second); }
        params_b = rb;
        params_len = rlen;
      });

  if (token.empty()) { return false; }
  if (params_len == 0) { return true; }

  // Scan parameters for q= (stops on first match)
  bool invalid = false;
  split_find(params_b, params_b + params_len, ';',
             (std::numeric_limits<size_t>::max)(),
             [&](const char *pb, const char *pe) -> bool {
               // Match exactly "q=" or "Q=" (not "query=" etc.)
               auto len = static_cast<size_t>(pe - pb);
               if (len < 2) { return false; }
               if ((pb[0] != 'q' && pb[0] != 'Q') || pb[1] != '=') {
                 return false;
               }

               // Trim the value portion
               auto r = trim(pb, pe, 2, len);
               if (r.first >= r.second) {
                 invalid = true;
                 return true;
               }

               double v = 0.0;
               auto res = from_chars(pb + r.first, pb + r.second, v);
               if (res.ec != std::errc{} || v < 0.0 || v > 1.0) {
                 invalid = true;
                 return true;
               }
               quality = v;
               return true;
             });

  return !invalid;
}

EncodingType encoding_type(const Request &req, const Response &res) {
  if (!can_compress_content_type(res.get_header_value("Content-Type"))) {
    return EncodingType::None;
  }

  const auto &s = req.get_header_value("Accept-Encoding");
  if (s.empty()) { return EncodingType::None; }

  // Single-pass: iterate tokens and track the best supported encoding.
  // Server preference breaks ties (br > gzip > zstd).
  EncodingType best = EncodingType::None;
  double best_q = 0.0; // q=0 means "not acceptable"

  // Server preference: Brotli > Gzip > Zstd (lower = more preferred)
  auto priority = [](EncodingType t) -> int {
    switch (t) {
    case EncodingType::Brotli: return 0;
    case EncodingType::Gzip: return 1;
    case EncodingType::Zstd: return 2;
    default: return 3;
    }
  };

  std::string name;
  split(s.data(), s.data() + s.size(), ',', [&](const char *b, const char *e) {
    double quality = 1.0;
    if (!parse_quality(b, e, name, quality)) { return; }
    if (quality <= 0.0) { return; }

    EncodingType type = EncodingType::None;
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
    if (case_ignore::equal(name, "br")) { type = EncodingType::Brotli; }
#endif
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
    if (type == EncodingType::None && case_ignore::equal(name, "gzip")) {
      type = EncodingType::Gzip;
    }
#endif
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
    if (type == EncodingType::None && case_ignore::equal(name, "zstd")) {
      type = EncodingType::Zstd;
    }
#endif

    if (type == EncodingType::None) { return; }

    // Higher q-value wins; for equal q, server preference breaks ties
    if (quality > best_q ||
        (quality == best_q && priority(type) < priority(best))) {
      best_q = quality;
      best = type;
    }
  });

  return best;
}

bool nocompressor::compress(const char *data, size_t data_length,
                                   bool /*last*/, Callback callback) {
  if (!data_length) { return true; }
  return callback(data, data_length);
}

#ifdef CPPHTTPLIB_ZLIB_SUPPORT
gzip_compressor::gzip_compressor() {
  std::memset(&strm_, 0, sizeof(strm_));
  strm_.zalloc = Z_NULL;
  strm_.zfree = Z_NULL;
  strm_.opaque = Z_NULL;

  is_valid_ = deflateInit2(&strm_, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 31, 8,
                           Z_DEFAULT_STRATEGY) == Z_OK;
}

gzip_compressor::~gzip_compressor() { deflateEnd(&strm_); }

bool gzip_compressor::compress(const char *data, size_t data_length,
                                      bool last, Callback callback) {
  assert(is_valid_);

  do {
    constexpr size_t max_avail_in =
        (std::numeric_limits<decltype(strm_.avail_in)>::max)();

    strm_.avail_in = static_cast<decltype(strm_.avail_in)>(
        (std::min)(data_length, max_avail_in));
    strm_.next_in = const_cast<Bytef *>(reinterpret_cast<const Bytef *>(data));

    data_length -= strm_.avail_in;
    data += strm_.avail_in;

    auto flush = (last && data_length == 0) ? Z_FINISH : Z_NO_FLUSH;
    auto ret = Z_OK;

    std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
    do {
      strm_.avail_out = static_cast<uInt>(buff.size());
      strm_.next_out = reinterpret_cast<Bytef *>(buff.data());

      ret = deflate(&strm_, flush);
      if (ret == Z_STREAM_ERROR) { return false; }

      if (!callback(buff.data(), buff.size() - strm_.avail_out)) {
        return false;
      }
    } while (strm_.avail_out == 0);

    assert((flush == Z_FINISH && ret == Z_STREAM_END) ||
           (flush == Z_NO_FLUSH && ret == Z_OK));
    assert(strm_.avail_in == 0);
  } while (data_length > 0);

  return true;
}

gzip_decompressor::gzip_decompressor() {
  std::memset(&strm_, 0, sizeof(strm_));
  strm_.zalloc = Z_NULL;
  strm_.zfree = Z_NULL;
  strm_.opaque = Z_NULL;

  // 15 is the value of wbits, which should be at the maximum possible value
  // to ensure that any gzip stream can be decoded. The offset of 32 specifies
  // that the stream type should be automatically detected either gzip or
  // deflate.
  is_valid_ = inflateInit2(&strm_, 32 + 15) == Z_OK;
}

gzip_decompressor::~gzip_decompressor() { inflateEnd(&strm_); }

bool gzip_decompressor::is_valid() const { return is_valid_; }

bool gzip_decompressor::decompress(const char *data, size_t data_length,
                                          Callback callback) {
  assert(is_valid_);

  auto ret = Z_OK;

  do {
    constexpr size_t max_avail_in =
        (std::numeric_limits<decltype(strm_.avail_in)>::max)();

    strm_.avail_in = static_cast<decltype(strm_.avail_in)>(
        (std::min)(data_length, max_avail_in));
    strm_.next_in = const_cast<Bytef *>(reinterpret_cast<const Bytef *>(data));

    data_length -= strm_.avail_in;
    data += strm_.avail_in;

    std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
    while (strm_.avail_in > 0 && ret == Z_OK) {
      strm_.avail_out = static_cast<uInt>(buff.size());
      strm_.next_out = reinterpret_cast<Bytef *>(buff.data());

      ret = inflate(&strm_, Z_NO_FLUSH);

      assert(ret != Z_STREAM_ERROR);
      switch (ret) {
      case Z_NEED_DICT:
      case Z_DATA_ERROR:
      case Z_MEM_ERROR: inflateEnd(&strm_); return false;
      }

      if (!callback(buff.data(), buff.size() - strm_.avail_out)) {
        return false;
      }
    }

    if (ret != Z_OK && ret != Z_STREAM_END) { return false; }

  } while (data_length > 0);

  return true;
}
#endif

#ifdef CPPHTTPLIB_BROTLI_SUPPORT
brotli_compressor::brotli_compressor() {
  state_ = BrotliEncoderCreateInstance(nullptr, nullptr, nullptr);
}

brotli_compressor::~brotli_compressor() {
  BrotliEncoderDestroyInstance(state_);
}

bool brotli_compressor::compress(const char *data, size_t data_length,
                                        bool last, Callback callback) {
  std::array<uint8_t, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};

  auto operation = last ? BROTLI_OPERATION_FINISH : BROTLI_OPERATION_PROCESS;
  auto available_in = data_length;
  auto next_in = reinterpret_cast<const uint8_t *>(data);

  for (;;) {
    if (last) {
      if (BrotliEncoderIsFinished(state_)) { break; }
    } else {
      if (!available_in) { break; }
    }

    auto available_out = buff.size();
    auto next_out = buff.data();

    if (!BrotliEncoderCompressStream(state_, operation, &available_in, &next_in,
                                     &available_out, &next_out, nullptr)) {
      return false;
    }

    auto output_bytes = buff.size() - available_out;
    if (output_bytes) {
      callback(reinterpret_cast<const char *>(buff.data()), output_bytes);
    }
  }

  return true;
}

brotli_decompressor::brotli_decompressor() {
  decoder_s = BrotliDecoderCreateInstance(0, 0, 0);
  decoder_r = decoder_s ? BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT
                        : BROTLI_DECODER_RESULT_ERROR;
}

brotli_decompressor::~brotli_decompressor() {
  if (decoder_s) { BrotliDecoderDestroyInstance(decoder_s); }
}

bool brotli_decompressor::is_valid() const { return decoder_s; }

bool brotli_decompressor::decompress(const char *data,
                                            size_t data_length,
                                            Callback callback) {
  if (decoder_r == BROTLI_DECODER_RESULT_SUCCESS ||
      decoder_r == BROTLI_DECODER_RESULT_ERROR) {
    return 0;
  }

  auto next_in = reinterpret_cast<const uint8_t *>(data);
  size_t avail_in = data_length;
  size_t total_out;

  decoder_r = BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT;

  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
  while (decoder_r == BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT) {
    char *next_out = buff.data();
    size_t avail_out = buff.size();

    decoder_r = BrotliDecoderDecompressStream(
        decoder_s, &avail_in, &next_in, &avail_out,
        reinterpret_cast<uint8_t **>(&next_out), &total_out);

    if (decoder_r == BROTLI_DECODER_RESULT_ERROR) { return false; }

    if (!callback(buff.data(), buff.size() - avail_out)) { return false; }
  }

  return decoder_r == BROTLI_DECODER_RESULT_SUCCESS ||
         decoder_r == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT;
}
#endif

#ifdef CPPHTTPLIB_ZSTD_SUPPORT
zstd_compressor::zstd_compressor() {
  ctx_ = ZSTD_createCCtx();
  ZSTD_CCtx_setParameter(ctx_, ZSTD_c_compressionLevel, ZSTD_fast);
}

zstd_compressor::~zstd_compressor() { ZSTD_freeCCtx(ctx_); }

bool zstd_compressor::compress(const char *data, size_t data_length,
                                      bool last, Callback callback) {
  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};

  ZSTD_EndDirective mode = last ? ZSTD_e_end : ZSTD_e_continue;
  ZSTD_inBuffer input = {data, data_length, 0};

  bool finished;
  do {
    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
    size_t const remaining = ZSTD_compressStream2(ctx_, &output, &input, mode);

    if (ZSTD_isError(remaining)) { return false; }

    if (!callback(buff.data(), output.pos)) { return false; }

    finished = last ? (remaining == 0) : (input.pos == input.size);

  } while (!finished);

  return true;
}

zstd_decompressor::zstd_decompressor() { ctx_ = ZSTD_createDCtx(); }

zstd_decompressor::~zstd_decompressor() { ZSTD_freeDCtx(ctx_); }

bool zstd_decompressor::is_valid() const { return ctx_ != nullptr; }

bool zstd_decompressor::decompress(const char *data, size_t data_length,
                                          Callback callback) {
  std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
  ZSTD_inBuffer input = {data, data_length, 0};

  while (input.pos < input.size) {
    ZSTD_outBuffer output = {buff.data(), CPPHTTPLIB_COMPRESSION_BUFSIZ, 0};
    size_t const remaining = ZSTD_decompressStream(ctx_, &output, &input);

    if (ZSTD_isError(remaining)) { return false; }

    if (!callback(buff.data(), output.pos)) { return false; }
  }

  return true;
}
#endif

std::unique_ptr<decompressor>
create_decompressor(const std::string &encoding) {
  std::unique_ptr<decompressor> decompressor;

  if (encoding == "gzip" || encoding == "deflate") {
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
    decompressor = detail::make_unique<gzip_decompressor>();
#endif
  } else if (encoding.find("br") != std::string::npos) {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
    decompressor = detail::make_unique<brotli_decompressor>();
#endif
  } else if (encoding == "zstd" || encoding.find("zstd") != std::string::npos) {
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
    decompressor = detail::make_unique<zstd_decompressor>();
#endif
  }

  return decompressor;
}

// Returns the best available compressor and its Content-Encoding name.
// Priority: Brotli > Gzip > Zstd (matches server-side preference).
std::pair<std::unique_ptr<compressor>, const char *>
create_compressor() {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
  return {detail::make_unique<brotli_compressor>(), "br"};
#elif defined(CPPHTTPLIB_ZLIB_SUPPORT)
  return {detail::make_unique<gzip_compressor>(), "gzip"};
#elif defined(CPPHTTPLIB_ZSTD_SUPPORT)
  return {detail::make_unique<zstd_compressor>(), "zstd"};
#else
  return {nullptr, nullptr};
#endif
}

bool is_prohibited_header_name(const std::string &name) {
  using udl::operator""_t;

  switch (str2tag(name)) {
  case "REMOTE_ADDR"_t:
  case "REMOTE_PORT"_t:
  case "LOCAL_ADDR"_t:
  case "LOCAL_PORT"_t: return true;
  default: return false;
  }
}

bool has_header(const Headers &headers, const std::string &key) {
  if (is_prohibited_header_name(key)) { return false; }
  return headers.find(key) != headers.end();
}

const char *get_header_value(const Headers &headers,
                                    const std::string &key, const char *def,
                                    size_t id) {
  if (is_prohibited_header_name(key)) {
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
    std::string msg = "Prohibited header name '" + key + "' is specified.";
    throw std::invalid_argument(msg);
#else
    return "";
#endif
  }

  auto rng = headers.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second.c_str(); }
  return def;
}

bool read_headers(Stream &strm, Headers &headers) {
  const auto bufsiz = 2048;
  char buf[bufsiz];
  stream_line_reader line_reader(strm, buf, bufsiz);

  size_t header_count = 0;

  for (;;) {
    if (!line_reader.getline()) { return false; }

    // Check if the line ends with CRLF.
    auto line_terminator_len = 2;
    if (line_reader.end_with_crlf()) {
      // Blank line indicates end of headers.
      if (line_reader.size() == 2) { break; }
    } else {
#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
      // Blank line indicates end of headers.
      if (line_reader.size() == 1) { break; }
      line_terminator_len = 1;
#else
      continue; // Skip invalid line.
#endif
    }

    if (line_reader.size() > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }

    // Check header count limit
    if (header_count >= CPPHTTPLIB_HEADER_MAX_COUNT) { return false; }

    // Exclude line terminator
    auto end = line_reader.ptr() + line_reader.size() - line_terminator_len;

    if (!parse_header(line_reader.ptr(), end,
                      [&](const std::string &key, const std::string &val) {
                        headers.emplace(key, val);
                      })) {
      return false;
    }

    header_count++;
  }

  // RFC 9110 Section 8.6: Reject requests with multiple Content-Length
  // headers that have different values to prevent request smuggling.
  auto cl_range = headers.equal_range("Content-Length");
  if (cl_range.first != cl_range.second) {
    const auto &first_val = cl_range.first->second;
    for (auto it = std::next(cl_range.first); it != cl_range.second; ++it) {
      if (it->second != first_val) { return false; }
    }
  }

  return true;
}

bool read_websocket_upgrade_response(Stream &strm,
                                            const std::string &expected_accept,
                                            std::string &selected_subprotocol) {
  // Read status line
  const auto bufsiz = 2048;
  char buf[bufsiz];
  stream_line_reader line_reader(strm, buf, bufsiz);
  if (!line_reader.getline()) { return false; }

  // Check for "HTTP/1.1 101"
  auto line = std::string(line_reader.ptr(), line_reader.size());
  if (line.find("HTTP/1.1 101") == std::string::npos) { return false; }

  // Parse headers using existing read_headers
  Headers headers;
  if (!read_headers(strm, headers)) { return false; }

  // Verify Upgrade: websocket (case-insensitive)
  auto upgrade_it = headers.find("Upgrade");
  if (upgrade_it == headers.end()) { return false; }
  auto upgrade_val = case_ignore::to_lower(upgrade_it->second);
  if (upgrade_val != "websocket") { return false; }

  // Verify Connection header contains "Upgrade" (case-insensitive)
  auto connection_it = headers.find("Connection");
  if (connection_it == headers.end()) { return false; }
  auto connection_val = case_ignore::to_lower(connection_it->second);
  if (connection_val.find("upgrade") == std::string::npos) { return false; }

  // Verify Sec-WebSocket-Accept header value
  auto it = headers.find("Sec-WebSocket-Accept");
  if (it == headers.end() || it->second != expected_accept) { return false; }

  // Extract negotiated subprotocol
  auto proto_it = headers.find("Sec-WebSocket-Protocol");
  if (proto_it != headers.end()) { selected_subprotocol = proto_it->second; }

  return true;
}

enum class ReadContentResult {
  Success,         // Successfully read the content
  PayloadTooLarge, // The content exceeds the specified payload limit
  Error            // An error occurred while reading the content
};

ReadContentResult read_content_with_length(
    Stream &strm, size_t len, DownloadProgress progress,
    ContentReceiverWithProgress out,
    size_t payload_max_length = (std::numeric_limits<size_t>::max)()) {
  char buf[CPPHTTPLIB_RECV_BUFSIZ];

  detail::BodyReader br;
  br.stream = &strm;
  br.has_content_length = true;
  br.content_length = len;
  br.payload_max_length = payload_max_length;
  br.chunked = false;
  br.bytes_read = 0;
  br.last_error = Error::Success;

  size_t r = 0;
  while (r < len) {
    auto read_len = static_cast<size_t>(len - r);
    auto to_read = (std::min)(read_len, CPPHTTPLIB_RECV_BUFSIZ);
    auto n = detail::read_body_content(&strm, br, buf, to_read);
    if (n <= 0) {
      // Check if it was a payload size error
      if (br.last_error == Error::ExceedMaxPayloadSize) {
        return ReadContentResult::PayloadTooLarge;
      }
      return ReadContentResult::Error;
    }

    if (!out(buf, static_cast<size_t>(n), r, len)) {
      return ReadContentResult::Error;
    }
    r += static_cast<size_t>(n);

    if (progress) {
      if (!progress(r, len)) { return ReadContentResult::Error; }
    }
  }

  return ReadContentResult::Success;
}

ReadContentResult
read_content_without_length(Stream &strm, size_t payload_max_length,
                            ContentReceiverWithProgress out) {
  char buf[CPPHTTPLIB_RECV_BUFSIZ];
  size_t r = 0;
  for (;;) {
    auto n = strm.read(buf, CPPHTTPLIB_RECV_BUFSIZ);
    if (n == 0) { return ReadContentResult::Success; }
    if (n < 0) { return ReadContentResult::Error; }

    // Check if adding this data would exceed the payload limit
    if (r > payload_max_length ||
        payload_max_length - r < static_cast<size_t>(n)) {
      return ReadContentResult::PayloadTooLarge;
    }

    if (!out(buf, static_cast<size_t>(n), r, 0)) {
      return ReadContentResult::Error;
    }
    r += static_cast<size_t>(n);
  }

  return ReadContentResult::Success;
}

template <typename T>
ReadContentResult read_content_chunked(Stream &strm, T &x,
                                              size_t payload_max_length,
                                              ContentReceiverWithProgress out) {
  detail::ChunkedDecoder dec(strm);

  char buf[CPPHTTPLIB_RECV_BUFSIZ];
  size_t total_len = 0;

  for (;;) {
    size_t chunk_offset = 0;
    size_t chunk_total = 0;
    auto n = dec.read_payload(buf, sizeof(buf), chunk_offset, chunk_total);
    if (n < 0) { return ReadContentResult::Error; }

    if (n == 0) {
      if (!dec.parse_trailers_into(x.trailers, x.headers)) {
        return ReadContentResult::Error;
      }
      return ReadContentResult::Success;
    }

    if (total_len > payload_max_length ||
        payload_max_length - total_len < static_cast<size_t>(n)) {
      return ReadContentResult::PayloadTooLarge;
    }

    if (!out(buf, static_cast<size_t>(n), chunk_offset, chunk_total)) {
      return ReadContentResult::Error;
    }

    total_len += static_cast<size_t>(n);
  }
}

bool is_chunked_transfer_encoding(const Headers &headers) {
  return case_ignore::equal(
      get_header_value(headers, "Transfer-Encoding", "", 0), "chunked");
}

template <typename T, typename U>
bool prepare_content_receiver(T &x, int &status,
                              ContentReceiverWithProgress receiver,
                              bool decompress, size_t payload_max_length,
                              bool &exceed_payload_max_length, U callback) {
  if (decompress) {
    std::string encoding = x.get_header_value("Content-Encoding");
    std::unique_ptr<decompressor> decompressor;

    if (!encoding.empty()) {
      decompressor = detail::create_decompressor(encoding);
      if (!decompressor) {
        // Unsupported encoding or no support compiled in
        status = StatusCode::UnsupportedMediaType_415;
        return false;
      }
    }

    if (decompressor) {
      if (decompressor->is_valid()) {
        size_t decompressed_size = 0;
        ContentReceiverWithProgress out = [&](const char *buf, size_t n,
                                              size_t off, size_t len) {
          return decompressor->decompress(
              buf, n, [&](const char *buf2, size_t n2) {
                // Guard against zip-bomb: check
                // decompressed size against limit.
                if (payload_max_length > 0 &&
                    (decompressed_size >= payload_max_length ||
                     n2 > payload_max_length - decompressed_size)) {
                  exceed_payload_max_length = true;
                  return false;
                }
                decompressed_size += n2;
                return receiver(buf2, n2, off, len);
              });
        };
        return callback(std::move(out));
      } else {
        status = StatusCode::InternalServerError_500;
        return false;
      }
    }
  }

  ContentReceiverWithProgress out = [&](const char *buf, size_t n, size_t off,
                                        size_t len) {
    return receiver(buf, n, off, len);
  };
  return callback(std::move(out));
}

template <typename T>
bool read_content(Stream &strm, T &x, size_t payload_max_length, int &status,
                  DownloadProgress progress,
                  ContentReceiverWithProgress receiver, bool decompress) {
  bool exceed_payload_max_length = false;
  return prepare_content_receiver(
      x, status, std::move(receiver), decompress, payload_max_length,
      exceed_payload_max_length, [&](const ContentReceiverWithProgress &out) {
        auto ret = true;
        // Note: exceed_payload_max_length may also be set by the decompressor
        // wrapper in prepare_content_receiver when the decompressed payload
        // size exceeds the limit.

        if (is_chunked_transfer_encoding(x.headers)) {
          auto result = read_content_chunked(strm, x, payload_max_length, out);
          if (result == ReadContentResult::Success) {
            ret = true;
          } else if (result == ReadContentResult::PayloadTooLarge) {
            exceed_payload_max_length = true;
            ret = false;
          } else {
            ret = false;
          }
        } else if (!has_header(x.headers, "Content-Length")) {
          auto result =
              read_content_without_length(strm, payload_max_length, out);
          if (result == ReadContentResult::Success) {
            ret = true;
          } else if (result == ReadContentResult::PayloadTooLarge) {
            exceed_payload_max_length = true;
            ret = false;
          } else {
            ret = false;
          }
        } else {
          auto is_invalid_value = false;
          auto len = get_header_value_u64(x.headers, "Content-Length",
                                          (std::numeric_limits<size_t>::max)(),
                                          0, is_invalid_value);

          if (is_invalid_value) {
            ret = false;
          } else if (len > 0) {
            auto result = read_content_with_length(
                strm, len, std::move(progress), out, payload_max_length);
            ret = (result == ReadContentResult::Success);
            if (result == ReadContentResult::PayloadTooLarge) {
              exceed_payload_max_length = true;
            }
          }
        }

        if (!ret) {
          status = exceed_payload_max_length ? StatusCode::PayloadTooLarge_413
                                             : StatusCode::BadRequest_400;
        }
        return ret;
      });
}

ssize_t write_request_line(Stream &strm, const std::string &method,
                                  const std::string &path) {
  std::string s = method;
  s += ' ';
  s += path;
  s += " HTTP/1.1\r\n";
  return strm.write(s.data(), s.size());
}

ssize_t write_response_line(Stream &strm, int status) {
  std::string s = "HTTP/1.1 ";
  s += std::to_string(status);
  s += ' ';
  s += httplib::status_message(status);
  s += "\r\n";
  return strm.write(s.data(), s.size());
}

ssize_t write_headers(Stream &strm, const Headers &headers) {
  ssize_t write_len = 0;
  for (const auto &x : headers) {
    std::string s;
    s = x.first;
    s += ": ";
    s += x.second;
    s += "\r\n";

    auto len = strm.write(s.data(), s.size());
    if (len < 0) { return len; }
    write_len += len;
  }
  auto len = strm.write("\r\n");
  if (len < 0) { return len; }
  write_len += len;
  return write_len;
}

bool write_data(Stream &strm, const char *d, size_t l) {
  size_t offset = 0;
  while (offset < l) {
    auto length = strm.write(d + offset, l - offset);
    if (length < 0) { return false; }
    offset += static_cast<size_t>(length);
  }
  return true;
}

template <typename T>
bool write_content_with_progress(Stream &strm,
                                        const ContentProvider &content_provider,
                                        size_t offset, size_t length,
                                        T is_shutting_down,
                                        const UploadProgress &upload_progress,
                                        Error &error) {
  size_t end_offset = offset + length;
  size_t start_offset = offset;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      if (write_data(strm, d, l)) {
        offset += l;

        if (upload_progress && length > 0) {
          size_t current_written = offset - start_offset;
          if (!upload_progress(current_written, length)) {
            ok = false;
            return false;
          }
        }
      } else {
        ok = false;
      }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  while (offset < end_offset && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      error = Error::Write;
      return false;
    } else if (!content_provider(offset, end_offset - offset, data_sink)) {
      error = Error::Canceled;
      return false;
    } else if (!ok) {
      error = Error::Write;
      return false;
    }
  }

  if (offset < end_offset) { // exited due to is_shutting_down(), not completion
    error = Error::Write;
    return false;
  }

  error = Error::Success;
  return true;
}

template <typename T>
bool write_content(Stream &strm, const ContentProvider &content_provider,
                          size_t offset, size_t length, T is_shutting_down,
                          Error &error) {
  return write_content_with_progress<T>(strm, content_provider, offset, length,
                                        is_shutting_down, nullptr, error);
}

template <typename T>
bool write_content(Stream &strm, const ContentProvider &content_provider,
                          size_t offset, size_t length,
                          const T &is_shutting_down) {
  auto error = Error::Success;
  return write_content(strm, content_provider, offset, length, is_shutting_down,
                       error);
}

template <typename T>
bool
write_content_without_length(Stream &strm,
                             const ContentProvider &content_provider,
                             const T &is_shutting_down) {
  size_t offset = 0;
  auto data_available = true;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      offset += l;
      if (!write_data(strm, d, l)) { ok = false; }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  data_sink.done = [&](void) { data_available = false; };

  while (data_available && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      return false;
    } else if (!content_provider(offset, 0, data_sink)) {
      return false;
    } else if (!ok) {
      return false;
    }
  }
  return !data_available; // true only if done() was called, false if shutting
                          // down
}

template <typename T, typename U>
bool
write_content_chunked(Stream &strm, const ContentProvider &content_provider,
                      const T &is_shutting_down, U &compressor, Error &error) {
  size_t offset = 0;
  auto data_available = true;
  auto ok = true;
  DataSink data_sink;

  data_sink.write = [&](const char *d, size_t l) -> bool {
    if (ok) {
      data_available = l > 0;
      offset += l;

      std::string payload;
      if (compressor.compress(d, l, false,
                              [&](const char *data, size_t data_len) {
                                payload.append(data, data_len);
                                return true;
                              })) {
        if (!payload.empty()) {
          // Emit chunked response header and footer for each chunk
          auto chunk =
              from_i_to_hex(payload.size()) + "\r\n" + payload + "\r\n";
          if (!write_data(strm, chunk.data(), chunk.size())) { ok = false; }
        }
      } else {
        ok = false;
      }
    }
    return ok;
  };

  data_sink.is_writable = [&]() -> bool { return strm.is_peer_alive(); };

  auto done_with_trailer = [&](const Headers *trailer) {
    if (!ok) { return; }

    data_available = false;

    std::string payload;
    if (!compressor.compress(nullptr, 0, true,
                             [&](const char *data, size_t data_len) {
                               payload.append(data, data_len);
                               return true;
                             })) {
      ok = false;
      return;
    }

    if (!payload.empty()) {
      // Emit chunked response header and footer for each chunk
      auto chunk = from_i_to_hex(payload.size()) + "\r\n" + payload + "\r\n";
      if (!write_data(strm, chunk.data(), chunk.size())) {
        ok = false;
        return;
      }
    }

    constexpr const char done_marker[] = "0\r\n";
    if (!write_data(strm, done_marker, str_len(done_marker))) { ok = false; }

    // Trailer
    if (trailer) {
      for (const auto &kv : *trailer) {
        std::string field_line = kv.first + ": " + kv.second + "\r\n";
        if (!write_data(strm, field_line.data(), field_line.size())) {
          ok = false;
        }
      }
    }

    constexpr const char crlf[] = "\r\n";
    if (!write_data(strm, crlf, str_len(crlf))) { ok = false; }
  };

  data_sink.done = [&](void) { done_with_trailer(nullptr); };

  data_sink.done_with_trailer = [&](const Headers &trailer) {
    done_with_trailer(&trailer);
  };

  while (data_available && !is_shutting_down()) {
    if (!strm.wait_writable() || !strm.is_peer_alive()) {
      error = Error::Write;
      return false;
    } else if (!content_provider(offset, 0, data_sink)) {
      error = Error::Canceled;
      return false;
    } else if (!ok) {
      error = Error::Write;
      return false;
    }
  }

  if (data_available) { // exited due to is_shutting_down(), not done()
    error = Error::Write;
    return false;
  }

  error = Error::Success;
  return true;
}

template <typename T, typename U>
bool write_content_chunked(Stream &strm,
                                  const ContentProvider &content_provider,
                                  const T &is_shutting_down, U &compressor) {
  auto error = Error::Success;
  return write_content_chunked(strm, content_provider, is_shutting_down,
                               compressor, error);
}

template <typename T>
bool redirect(T &cli, Request &req, Response &res,
                     const std::string &path, const std::string &location,
                     Error &error) {
  Request new_req = req;
  new_req.path = path;
  new_req.redirect_count_ -= 1;

  if (res.status == StatusCode::SeeOther_303 &&
      (req.method != "GET" && req.method != "HEAD")) {
    new_req.method = "GET";
    new_req.body.clear();
    new_req.headers.clear();
  }

  Response new_res;

  auto ret = cli.send(new_req, new_res, error);
  if (ret) {
    req = std::move(new_req);
    res = std::move(new_res);

    if (res.location.empty()) { res.location = location; }
  }
  return ret;
}

std::string params_to_query_str(const Params &params) {
  std::string query;

  for (auto it = params.begin(); it != params.end(); ++it) {
    if (it != params.begin()) { query += '&'; }
    query += encode_query_component(it->first);
    query += '=';
    query += encode_query_component(it->second);
  }
  return query;
}

void parse_query_text(const char *data, std::size_t size,
                             Params &params) {
  std::set<std::string> cache;
  split(data, data + size, '&', [&](const char *b, const char *e) {
    std::string kv(b, e);
    if (cache.find(kv) != cache.end()) { return; }
    cache.insert(std::move(kv));

    std::string key;
    std::string val;
    divide(b, static_cast<std::size_t>(e - b), '=',
           [&](const char *lhs_data, std::size_t lhs_size, const char *rhs_data,
               std::size_t rhs_size) {
             key.assign(lhs_data, lhs_size);
             val.assign(rhs_data, rhs_size);
           });

    if (!key.empty()) {
      params.emplace(decode_query_component(key), decode_query_component(val));
    }
  });
}

void parse_query_text(const std::string &s, Params &params) {
  parse_query_text(s.data(), s.size(), params);
}

// Normalize a query string by decoding and re-encoding each key/value pair
// while preserving the original parameter order. This avoids double-encoding
// and ensures consistent encoding without reordering (unlike Params which
// uses std::multimap and sorts keys).
std::string normalize_query_string(const std::string &query) {
  std::string result;
  split(query.data(), query.data() + query.size(), '&',
        [&](const char *b, const char *e) {
          std::string key;
          std::string val;
          divide(b, static_cast<std::size_t>(e - b), '=',
                 [&](const char *lhs_data, std::size_t lhs_size,
                     const char *rhs_data, std::size_t rhs_size) {
                   key.assign(lhs_data, lhs_size);
                   val.assign(rhs_data, rhs_size);
                 });

          if (!key.empty()) {
            auto dec_key = decode_query_component(key);
            auto dec_val = decode_query_component(val);

            if (!result.empty()) { result += '&'; }
            result += encode_query_component(dec_key);
            if (!val.empty() || std::find(b, e, '=') != e) {
              result += '=';
              result += encode_query_component(dec_val);
            }
          }
        });
  return result;
}

bool parse_multipart_boundary(const std::string &content_type,
                                     std::string &boundary) {
  std::map<std::string, std::string> params;
  extract_media_type(content_type, &params);
  auto it = params.find("boundary");
  if (it == params.end()) { return false; }
  boundary = it->second;
  return !boundary.empty();
}

void parse_disposition_params(const std::string &s, Params &params) {
  std::set<std::string> cache;
  split(s.data(), s.data() + s.size(), ';', [&](const char *b, const char *e) {
    std::string kv(b, e);
    if (cache.find(kv) != cache.end()) { return; }
    cache.insert(kv);

    std::string key;
    std::string val;
    split(b, e, '=', [&](const char *b2, const char *e2) {
      if (key.empty()) {
        key.assign(b2, e2);
      } else {
        val.assign(b2, e2);
      }
    });

    if (!key.empty()) {
      params.emplace(trim_double_quotes_copy((key)),
                     trim_double_quotes_copy((val)));
    }
  });
}

#ifdef CPPHTTPLIB_NO_EXCEPTIONS
bool parse_range_header(const std::string &s, Ranges &ranges) {
#else
bool parse_range_header(const std::string &s, Ranges &ranges) try {
#endif
  auto is_valid = [](const std::string &str) {
    return std::all_of(str.cbegin(), str.cend(),
                       [](unsigned char c) { return std::isdigit(c); });
  };

  if (s.size() > 7 && s.compare(0, 6, "bytes=") == 0) {
    const auto pos = static_cast<size_t>(6);
    const auto len = static_cast<size_t>(s.size() - 6);
    auto all_valid_ranges = true;
    split(&s[pos], &s[pos + len], ',', [&](const char *b, const char *e) {
      if (!all_valid_ranges) { return; }

      const auto it = std::find(b, e, '-');
      if (it == e) {
        all_valid_ranges = false;
        return;
      }

      const auto lhs = std::string(b, it);
      const auto rhs = std::string(it + 1, e);
      if (!is_valid(lhs) || !is_valid(rhs)) {
        all_valid_ranges = false;
        return;
      }

      ssize_t first = -1;
      if (!lhs.empty()) {
        ssize_t v;
        auto res = detail::from_chars(lhs.data(), lhs.data() + lhs.size(), v);
        if (res.ec == std::errc{}) { first = v; }
      }

      ssize_t last = -1;
      if (!rhs.empty()) {
        ssize_t v;
        auto res = detail::from_chars(rhs.data(), rhs.data() + rhs.size(), v);
        if (res.ec == std::errc{}) { last = v; }
      }

      if ((first == -1 && last == -1) ||
          (first != -1 && last != -1 && first > last)) {
        all_valid_ranges = false;
        return;
      }

      ranges.emplace_back(first, last);
    });
    return all_valid_ranges && !ranges.empty();
  }
  return false;
#ifdef CPPHTTPLIB_NO_EXCEPTIONS
}
#else
} catch (...) { return false; }
#endif

bool parse_accept_header(const std::string &s,
                                std::vector<std::string> &content_types) {
  content_types.clear();

  // Empty string is considered valid (no preference)
  if (s.empty()) { return true; }

  // Check for invalid patterns: leading/trailing commas or consecutive commas
  if (s.front() == ',' || s.back() == ',' ||
      s.find(",,") != std::string::npos) {
    return false;
  }

  struct AcceptEntry {
    std::string media_type;
    double quality;
    int order;
  };

  std::vector<AcceptEntry> entries;
  int order = 0;
  bool has_invalid_entry = false;

  // Split by comma and parse each entry
  split(s.data(), s.data() + s.size(), ',', [&](const char *b, const char *e) {
    std::string entry(b, e);
    entry = trim_copy(entry);

    if (entry.empty()) {
      has_invalid_entry = true;
      return;
    }

    AcceptEntry accept_entry;
    accept_entry.order = order++;

    if (!parse_quality(entry.data(), entry.data() + entry.size(),
                       accept_entry.media_type, accept_entry.quality)) {
      has_invalid_entry = true;
      return;
    }

    // Remove additional parameters from media type
    accept_entry.media_type = extract_media_type(accept_entry.media_type);

    // Basic validation of media type format
    if (accept_entry.media_type.empty()) {
      has_invalid_entry = true;
      return;
    }

    // Check for basic media type format (should contain '/' or be '*')
    if (accept_entry.media_type != "*" &&
        accept_entry.media_type.find('/') == std::string::npos) {
      has_invalid_entry = true;
      return;
    }

    entries.push_back(std::move(accept_entry));
  });

  // Return false if any invalid entry was found
  if (has_invalid_entry) { return false; }

  // Sort by quality (descending), then by original order (ascending)
  std::sort(entries.begin(), entries.end(),
            [](const AcceptEntry &a, const AcceptEntry &b) {
              if (a.quality != b.quality) {
                return a.quality > b.quality; // Higher quality first
              }
              return a.order < b.order; // Earlier order first for same quality
            });

  // Extract sorted media types
  content_types.reserve(entries.size());
  for (auto &entry : entries) {
    content_types.push_back(std::move(entry.media_type));
  }

  return true;
}

class FormDataParser {
public:
  FormDataParser() = default;

  void set_boundary(std::string &&boundary) {
    boundary_ = std::move(boundary);
    dash_boundary_crlf_ = dash_ + boundary_ + crlf_;
    crlf_dash_boundary_ = crlf_ + dash_ + boundary_;
  }

  bool is_valid() const { return is_valid_; }

  bool parse(const char *buf, size_t n, const FormDataHeader &header_callback,
             const ContentReceiver &content_callback) {

    buf_append(buf, n);

    while (buf_size() > 0) {
      switch (state_) {
      case 0: { // Initial boundary
        auto pos = buf_find(dash_boundary_crlf_);
        if (pos == buf_size()) { return true; }
        buf_erase(pos + dash_boundary_crlf_.size());
        state_ = 1;
        break;
      }
      case 1: { // New entry
        clear_file_info();
        state_ = 2;
        break;
      }
      case 2: { // Headers
        auto pos = buf_find(crlf_);
        if (pos > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }
        while (pos < buf_size()) {
          // Empty line
          if (pos == 0) {
            if (!header_callback(file_)) {
              is_valid_ = false;
              return false;
            }
            buf_erase(crlf_.size());
            state_ = 3;
            break;
          }

          const auto header = buf_head(pos);

          if (!parse_header(header.data(), header.data() + header.size(),
                            [&](const std::string &, const std::string &) {})) {
            is_valid_ = false;
            return false;
          }

          // Parse and emplace space trimmed headers into a map
          if (!parse_header(
                  header.data(), header.data() + header.size(),
                  [&](const std::string &key, const std::string &val) {
                    file_.headers.emplace(key, val);
                  })) {
            is_valid_ = false;
            return false;
          }

          constexpr const char header_content_type[] = "Content-Type:";

          if (start_with_case_ignore(header, header_content_type)) {
            file_.content_type =
                trim_copy(header.substr(str_len(header_content_type)));
          } else {
            std::string disposition_params;
            if (parse_content_disposition(header, disposition_params)) {
              Params params;
              parse_disposition_params(disposition_params, params);

              auto it = params.find("name");
              if (it != params.end()) {
                file_.name = it->second;
              } else {
                is_valid_ = false;
                return false;
              }

              it = params.find("filename");
              if (it != params.end()) { file_.filename = it->second; }

              it = params.find("filename*");
              if (it != params.end()) {
                // RFC 5987: only UTF-8 encoding is allowed
                const auto &val = it->second;
                constexpr const char utf8_prefix[] = "UTF-8''";
                constexpr size_t prefix_len = str_len(utf8_prefix);
                if (val.size() > prefix_len &&
                    start_with_case_ignore(val, utf8_prefix)) {
                  file_.filename = decode_path_component(
                      val.substr(prefix_len)); // override...
                } else {
                  is_valid_ = false;
                  return false;
                }
              }
            }
          }
          buf_erase(pos + crlf_.size());
          pos = buf_find(crlf_);
        }
        if (state_ != 3) { return true; }
        break;
      }
      case 3: { // Body
        if (crlf_dash_boundary_.size() > buf_size()) { return true; }
        auto pos = buf_find(crlf_dash_boundary_);
        if (pos < buf_size()) {
          if (!content_callback(buf_data(), pos)) {
            is_valid_ = false;
            return false;
          }
          buf_erase(pos + crlf_dash_boundary_.size());
          state_ = 4;
        } else {
          auto len = buf_size() - crlf_dash_boundary_.size();
          if (len > 0) {
            if (!content_callback(buf_data(), len)) {
              is_valid_ = false;
              return false;
            }
            buf_erase(len);
          }
          return true;
        }
        break;
      }
      case 4: { // Boundary
        if (crlf_.size() > buf_size()) { return true; }
        if (buf_start_with(crlf_)) {
          buf_erase(crlf_.size());
          state_ = 1;
        } else {
          if (dash_.size() > buf_size()) { return true; }
          if (buf_start_with(dash_)) {
            buf_erase(dash_.size());
            is_valid_ = true;
            buf_erase(buf_size()); // Remove epilogue
          } else {
            return true;
          }
        }
        break;
      }
      }
    }

    return true;
  }

private:
  void clear_file_info() {
    file_.name.clear();
    file_.filename.clear();
    file_.content_type.clear();
    file_.headers.clear();
  }

  bool start_with_case_ignore(const std::string &a, const char *b,
                              size_t offset = 0) const {
    const auto b_len = strlen(b);
    if (a.size() < offset + b_len) { return false; }
    for (size_t i = 0; i < b_len; i++) {
      if (case_ignore::to_lower(a[offset + i]) != case_ignore::to_lower(b[i])) {
        return false;
      }
    }
    return true;
  }

  // Parses "Content-Disposition: form-data; <params>" without std::regex.
  // Returns true if header matches, with the params portion in `params_out`.
  bool parse_content_disposition(const std::string &header,
                                 std::string &params_out) const {
    constexpr const char prefix[] = "Content-Disposition:";
    constexpr size_t prefix_len = str_len(prefix);

    if (!start_with_case_ignore(header, prefix)) { return false; }

    // Skip whitespace after "Content-Disposition:"
    auto pos = prefix_len;
    while (pos < header.size() && (header[pos] == ' ' || header[pos] == '\t')) {
      pos++;
    }

    // Match "form-data;" (case-insensitive)
    constexpr const char form_data[] = "form-data;";
    constexpr size_t form_data_len = str_len(form_data);
    if (!start_with_case_ignore(header, form_data, pos)) { return false; }
    pos += form_data_len;

    // Skip whitespace after "form-data;"
    while (pos < header.size() && (header[pos] == ' ' || header[pos] == '\t')) {
      pos++;
    }

    params_out = header.substr(pos);
    return true;
  }

  const std::string dash_ = "--";
  const std::string crlf_ = "\r\n";
  std::string boundary_;
  std::string dash_boundary_crlf_;
  std::string crlf_dash_boundary_;

  size_t state_ = 0;
  bool is_valid_ = false;
  FormData file_;

  // Buffer
  bool start_with(const std::string &a, size_t spos, size_t epos,
                  const std::string &b) const {
    if (epos - spos < b.size()) { return false; }
    for (size_t i = 0; i < b.size(); i++) {
      if (a[i + spos] != b[i]) { return false; }
    }
    return true;
  }

  size_t buf_size() const { return buf_epos_ - buf_spos_; }

  const char *buf_data() const { return &buf_[buf_spos_]; }

  std::string buf_head(size_t l) const { return buf_.substr(buf_spos_, l); }

  bool buf_start_with(const std::string &s) const {
    return start_with(buf_, buf_spos_, buf_epos_, s);
  }

  size_t buf_find(const std::string &s) const {
    auto c = s.front();

    size_t off = buf_spos_;
    while (off < buf_epos_) {
      auto pos = off;
      while (true) {
        if (pos == buf_epos_) { return buf_size(); }
        if (buf_[pos] == c) { break; }
        pos++;
      }

      auto remaining_size = buf_epos_ - pos;
      if (s.size() > remaining_size) { return buf_size(); }

      if (start_with(buf_, pos, buf_epos_, s)) { return pos - buf_spos_; }

      off = pos + 1;
    }

    return buf_size();
  }

  void buf_append(const char *data, size_t n) {
    auto remaining_size = buf_size();
    if (remaining_size > 0 && buf_spos_ > 0) {
      for (size_t i = 0; i < remaining_size; i++) {
        buf_[i] = buf_[buf_spos_ + i];
      }
    }
    buf_spos_ = 0;
    buf_epos_ = remaining_size;

    if (remaining_size + n > buf_.size()) { buf_.resize(remaining_size + n); }

    for (size_t i = 0; i < n; i++) {
      buf_[buf_epos_ + i] = data[i];
    }
    buf_epos_ += n;
  }

  void buf_erase(size_t size) { buf_spos_ += size; }

  std::string buf_;
  size_t buf_spos_ = 0;
  size_t buf_epos_ = 0;
};

std::string random_string(size_t length) {
  constexpr const char data[] =
      "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

  thread_local auto engine([]() {
    // std::random_device might actually be deterministic on some
    // platforms, but due to lack of support in the c++ standard library,
    // doing better requires either some ugly hacks or breaking portability.
    std::random_device seed_gen;
    // Request 128 bits of entropy for initialization
    std::seed_seq seed_sequence{seed_gen(), seed_gen(), seed_gen(), seed_gen()};
    return std::mt19937(seed_sequence);
  }());

  std::string result;
  for (size_t i = 0; i < length; i++) {
    result += data[engine() % (sizeof(data) - 1)];
  }
  return result;
}

std::string make_multipart_data_boundary() {
  return "--cpp-httplib-multipart-data-" + detail::random_string(16);
}

bool is_multipart_boundary_chars_valid(const std::string &boundary) {
  auto valid = true;
  for (size_t i = 0; i < boundary.size(); i++) {
    auto c = boundary[i];
    if (!std::isalnum(c) && c != '-' && c != '_') {
      valid = false;
      break;
    }
  }
  return valid;
}

template <typename T>
std::string
serialize_multipart_formdata_item_begin(const T &item,
                                        const std::string &boundary) {
  std::string body = "--" + boundary + "\r\n";
  body += "Content-Disposition: form-data; name=\"" + item.name + "\"";
  if (!item.filename.empty()) {
    body += "; filename=\"" + item.filename + "\"";
  }
  body += "\r\n";
  if (!item.content_type.empty()) {
    body += "Content-Type: " + item.content_type + "\r\n";
  }
  body += "\r\n";

  return body;
}

std::string serialize_multipart_formdata_item_end() { return "\r\n"; }

std::string
serialize_multipart_formdata_finish(const std::string &boundary) {
  return "--" + boundary + "--\r\n";
}

std::string
serialize_multipart_formdata_get_content_type(const std::string &boundary) {
  return "multipart/form-data; boundary=" + boundary;
}

std::string
serialize_multipart_formdata(const UploadFormDataItems &items,
                             const std::string &boundary, bool finish = true) {
  std::string body;

  for (const auto &item : items) {
    body += serialize_multipart_formdata_item_begin(item, boundary);
    body += item.content + serialize_multipart_formdata_item_end();
  }

  if (finish) { body += serialize_multipart_formdata_finish(boundary); }

  return body;
}

size_t get_multipart_content_length(const UploadFormDataItems &items,
                                           const std::string &boundary) {
  size_t total = 0;
  for (const auto &item : items) {
    total += serialize_multipart_formdata_item_begin(item, boundary).size();
    total += item.content.size();
    total += serialize_multipart_formdata_item_end().size();
  }
  total += serialize_multipart_formdata_finish(boundary).size();
  return total;
}

struct MultipartSegment {
  const char *data;
  size_t size;
};

// NOTE: items must outlive the returned ContentProvider
//       (safe for synchronous use inside Post/Put/Patch)
ContentProvider
make_multipart_content_provider(const UploadFormDataItems &items,
                                const std::string &boundary) {
  // Own the per-item header strings and the finish string
  std::vector<std::string> owned;
  owned.reserve(items.size() + 1);
  for (const auto &item : items)
    owned.push_back(serialize_multipart_formdata_item_begin(item, boundary));
  owned.push_back(serialize_multipart_formdata_finish(boundary));

  // Flat segment list: [header, content, "\r\n"] * N + [finish]
  std::vector<MultipartSegment> segs;
  segs.reserve(items.size() * 3 + 1);
  static const char crlf[] = "\r\n";
  for (size_t i = 0; i < items.size(); i++) {
    segs.push_back({owned[i].data(), owned[i].size()});
    segs.push_back({items[i].content.data(), items[i].content.size()});
    segs.push_back({crlf, 2});
  }
  segs.push_back({owned.back().data(), owned.back().size()});

  struct MultipartState {
    std::vector<std::string> owned;
    std::vector<MultipartSegment> segs;
  };
  auto state = std::make_shared<MultipartState>();
  state->owned = std::move(owned);
  // `segs` holds raw pointers into owned strings; std::string move preserves
  // the data pointer, so these pointers remain valid after the move above.
  state->segs = std::move(segs);

  return [state](size_t offset, size_t length, DataSink &sink) -> bool {
    size_t pos = 0;
    for (const auto &seg : state->segs) {
      // Loop invariant: pos <= offset (proven by advancing pos only when
      // offset - pos >= seg.size, i.e., the segment doesn't contain offset)
      if (seg.size > 0 && offset - pos < seg.size) {
        size_t seg_offset = offset - pos;
        size_t available = seg.size - seg_offset;
        size_t to_write = (std::min)(available, length);
        return sink.write(seg.data + seg_offset, to_write);
      }
      pos += seg.size;
    }
    return true; // past end (shouldn't be reached when content_length is exact)
  };
}

void coalesce_ranges(Ranges &ranges, size_t content_length) {
  if (ranges.size() <= 1) return;

  // Sort ranges by start position
  std::sort(ranges.begin(), ranges.end(),
            [](const Range &a, const Range &b) { return a.first < b.first; });

  Ranges coalesced;
  coalesced.reserve(ranges.size());

  for (auto &r : ranges) {
    auto first_pos = r.first;
    auto last_pos = r.second;

    // Handle special cases like in range_error
    if (first_pos == -1 && last_pos == -1) {
      first_pos = 0;
      last_pos = static_cast<ssize_t>(content_length);
    }

    if (first_pos == -1) {
      first_pos = static_cast<ssize_t>(content_length) - last_pos;
      last_pos = static_cast<ssize_t>(content_length) - 1;
    }

    if (last_pos == -1 || last_pos >= static_cast<ssize_t>(content_length)) {
      last_pos = static_cast<ssize_t>(content_length) - 1;
    }

    // Skip invalid ranges
    if (!(0 <= first_pos && first_pos <= last_pos &&
          last_pos < static_cast<ssize_t>(content_length))) {
      continue;
    }

    // Coalesce with previous range if overlapping or adjacent (but not
    // identical)
    if (!coalesced.empty()) {
      auto &prev = coalesced.back();
      // Check if current range overlaps or is adjacent to previous range
      // but don't coalesce identical ranges (allow duplicates)
      if (first_pos <= prev.second + 1 &&
          !(first_pos == prev.first && last_pos == prev.second)) {
        // Extend the previous range
        prev.second = (std::max)(prev.second, last_pos);
        continue;
      }
    }

    // Add new range
    coalesced.emplace_back(first_pos, last_pos);
  }

  ranges = std::move(coalesced);
}

bool range_error(Request &req, Response &res) {
  if (!req.ranges.empty() && 200 <= res.status && res.status < 300) {
    ssize_t content_len = static_cast<ssize_t>(
        res.content_length_ ? res.content_length_ : res.body.size());

    std::vector<std::pair<ssize_t, ssize_t>> processed_ranges;
    size_t overwrapping_count = 0;

    // NOTE: The following Range check is based on '14.2. Range' in RFC 9110
    // 'HTTP Semantics' to avoid potential denial-of-service attacks.
    // https://www.rfc-editor.org/rfc/rfc9110#section-14.2

    // Too many ranges
    if (req.ranges.size() > CPPHTTPLIB_RANGE_MAX_COUNT) { return true; }

    for (auto &r : req.ranges) {
      auto &first_pos = r.first;
      auto &last_pos = r.second;

      if (first_pos == -1 && last_pos == -1) {
        first_pos = 0;
        last_pos = content_len;
      }

      if (first_pos == -1) {
        first_pos = content_len - last_pos;
        last_pos = content_len - 1;
      }

      // NOTE: RFC-9110 '14.1.2. Byte Ranges':
      // A client can limit the number of bytes requested without knowing the
      // size of the selected representation. If the last-pos value is absent,
      // or if the value is greater than or equal to the current length of the
      // representation data, the byte range is interpreted as the remainder of
      // the representation (i.e., the server replaces the value of last-pos
      // with a value that is one less than the current length of the selected
      // representation).
      // https://www.rfc-editor.org/rfc/rfc9110.html#section-14.1.2-6
      if (last_pos == -1 || last_pos >= content_len) {
        last_pos = content_len - 1;
      }

      // Range must be within content length
      if (!(0 <= first_pos && first_pos <= last_pos &&
            last_pos <= content_len - 1)) {
        return true;
      }

      // Request must not have more than two overlapping ranges
      for (const auto &processed_range : processed_ranges) {
        if (!(last_pos < processed_range.first ||
              first_pos > processed_range.second)) {
          overwrapping_count++;
          if (overwrapping_count > 2) { return true; }
          break; // Only count once per range
        }
      }

      processed_ranges.emplace_back(first_pos, last_pos);
    }

    // After validation, coalesce overlapping ranges as per RFC 9110
    coalesce_ranges(req.ranges, static_cast<size_t>(content_len));
  }

  return false;
}

std::pair<size_t, size_t>
get_range_offset_and_length(Range r, size_t content_length) {
  assert(r.first != -1 && r.second != -1);
  assert(0 <= r.first && r.first < static_cast<ssize_t>(content_length));
  assert(r.first <= r.second &&
         r.second < static_cast<ssize_t>(content_length));
  (void)(content_length);
  return std::make_pair(static_cast<size_t>(r.first),
                        static_cast<size_t>(r.second - r.first) + 1);
}

std::string make_content_range_header_field(
    const std::pair<size_t, size_t> &offset_and_length, size_t content_length) {
  auto st = offset_and_length.first;
  auto ed = st + offset_and_length.second - 1;

  std::string field = "bytes ";
  field += std::to_string(st);
  field += '-';
  field += std::to_string(ed);
  field += '/';
  field += std::to_string(content_length);
  return field;
}

template <typename SToken, typename CToken, typename Content>
bool process_multipart_ranges_data(const Request &req,
                                   const std::string &boundary,
                                   const std::string &content_type,
                                   size_t content_length, SToken stoken,
                                   CToken ctoken, Content content) {
  for (size_t i = 0; i < req.ranges.size(); i++) {
    ctoken("--");
    stoken(boundary);
    ctoken("\r\n");
    if (!content_type.empty()) {
      ctoken("Content-Type: ");
      stoken(content_type);
      ctoken("\r\n");
    }

    auto offset_and_length =
        get_range_offset_and_length(req.ranges[i], content_length);

    ctoken("Content-Range: ");
    stoken(make_content_range_header_field(offset_and_length, content_length));
    ctoken("\r\n");
    ctoken("\r\n");

    if (!content(offset_and_length.first, offset_and_length.second)) {
      return false;
    }
    ctoken("\r\n");
  }

  ctoken("--");
  stoken(boundary);
  ctoken("--");

  return true;
}

void make_multipart_ranges_data(const Request &req, Response &res,
                                       const std::string &boundary,
                                       const std::string &content_type,
                                       size_t content_length,
                                       std::string &data) {
  process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { data += token; },
      [&](const std::string &token) { data += token; },
      [&](size_t offset, size_t length) {
        assert(offset + length <= content_length);
        data += res.body.substr(offset, length);
        return true;
      });
}

size_t get_multipart_ranges_data_length(const Request &req,
                                               const std::string &boundary,
                                               const std::string &content_type,
                                               size_t content_length) {
  size_t data_length = 0;

  process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { data_length += token.size(); },
      [&](const std::string &token) { data_length += token.size(); },
      [&](size_t /*offset*/, size_t length) {
        data_length += length;
        return true;
      });

  return data_length;
}

template <typename T>
bool
write_multipart_ranges_data(Stream &strm, const Request &req, Response &res,
                            const std::string &boundary,
                            const std::string &content_type,
                            size_t content_length, const T &is_shutting_down) {
  return process_multipart_ranges_data(
      req, boundary, content_type, content_length,
      [&](const std::string &token) { strm.write(token); },
      [&](const std::string &token) { strm.write(token); },
      [&](size_t offset, size_t length) {
        return write_content(strm, res.content_provider_, offset, length,
                             is_shutting_down);
      });
}

bool expect_content(const Request &req) {
  if (req.method == "POST" || req.method == "PUT" || req.method == "PATCH" ||
      req.method == "DELETE") {
    return true;
  }
  if (req.has_header("Content-Length") &&
      req.get_header_value_u64("Content-Length") > 0) {
    return true;
  }
  if (is_chunked_transfer_encoding(req.headers)) { return true; }
  return false;
}

#ifdef _WIN32
class WSInit {
public:
  WSInit() {
    WSADATA wsaData;
    if (WSAStartup(0x0002, &wsaData) == 0) is_valid_ = true;
  }

  ~WSInit() {
    if (is_valid_) WSACleanup();
  }

  bool is_valid_ = false;
};

static WSInit wsinit_;
#endif

bool parse_www_authenticate(const Response &res,
                                   std::map<std::string, std::string> &auth,
                                   bool is_proxy) {
  auto auth_key = is_proxy ? "Proxy-Authenticate" : "WWW-Authenticate";
  if (res.has_header(auth_key)) {
    thread_local auto re =
        std::regex(R"~((?:(?:,\s*)?(.+?)=(?:"(.*?)"|([^,]*))))~");
    auto s = res.get_header_value(auth_key);
    auto pos = s.find(' ');
    if (pos != std::string::npos) {
      auto type = s.substr(0, pos);
      if (type == "Basic") {
        return false;
      } else if (type == "Digest") {
        s = s.substr(pos + 1);
        auto beg = std::sregex_iterator(s.begin(), s.end(), re);
        for (auto i = beg; i != std::sregex_iterator(); ++i) {
          const auto &m = *i;
          auto key = s.substr(static_cast<size_t>(m.position(1)),
                              static_cast<size_t>(m.length(1)));
          auto val = m.length(2) > 0
                         ? s.substr(static_cast<size_t>(m.position(2)),
                                    static_cast<size_t>(m.length(2)))
                         : s.substr(static_cast<size_t>(m.position(3)),
                                    static_cast<size_t>(m.length(3)));
          auth[std::move(key)] = std::move(val);
        }
        return true;
      }
    }
  }
  return false;
}

class ContentProviderAdapter {
public:
  explicit ContentProviderAdapter(
      ContentProviderWithoutLength &&content_provider)
      : content_provider_(std::move(content_provider)) {}

  bool operator()(size_t offset, size_t, DataSink &sink) {
    return content_provider_(offset, sink);
  }

private:
  ContentProviderWithoutLength content_provider_;
};

// NOTE: https://www.rfc-editor.org/rfc/rfc9110#section-5
namespace fields {

bool is_token_char(char c) {
  return std::isalnum(c) || c == '!' || c == '#' || c == '$' || c == '%' ||
         c == '&' || c == '\'' || c == '*' || c == '+' || c == '-' ||
         c == '.' || c == '^' || c == '_' || c == '`' || c == '|' || c == '~';
}

bool is_token(const std::string &s) {
  if (s.empty()) { return false; }
  for (auto c : s) {
    if (!is_token_char(c)) { return false; }
  }
  return true;
}

bool is_field_name(const std::string &s) { return is_token(s); }

bool is_vchar(char c) { return c >= 33 && c <= 126; }

bool is_obs_text(char c) { return 128 <= static_cast<unsigned char>(c); }

bool is_field_vchar(char c) { return is_vchar(c) || is_obs_text(c); }

bool is_field_content(const std::string &s) {
  if (s.empty()) { return true; }

  if (s.size() == 1) {
    return is_field_vchar(s[0]);
  } else if (s.size() == 2) {
    return is_field_vchar(s[0]) && is_field_vchar(s[1]);
  } else {
    size_t i = 0;

    if (!is_field_vchar(s[i])) { return false; }
    i++;

    while (i < s.size() - 1) {
      auto c = s[i++];
      if (c == ' ' || c == '\t' || is_field_vchar(c)) {
      } else {
        return false;
      }
    }

    return is_field_vchar(s[i]);
  }
}

bool is_field_value(const std::string &s) { return is_field_content(s); }

} // namespace fields

bool perform_websocket_handshake(Stream &strm, const std::string &host,
                                        int port, const std::string &path,
                                        const Headers &headers,
                                        std::string &selected_subprotocol) {
  // Validate path and host
  if (!fields::is_field_value(path) || !fields::is_field_value(host)) {
    return false;
  }

  // Validate user-provided headers
  for (const auto &h : headers) {
    if (!fields::is_field_name(h.first) || !fields::is_field_value(h.second)) {
      return false;
    }
  }

  // Generate random Sec-WebSocket-Key
  thread_local std::mt19937 rng(std::random_device{}());
  std::string key_bytes(16, '\0');
  for (size_t i = 0; i < 16; i += 4) {
    auto r = rng();
    std::memcpy(&key_bytes[i], &r, (std::min)(size_t(4), size_t(16 - i)));
  }
  auto client_key = base64_encode(key_bytes);

  // Build upgrade request
  std::string req_str = "GET " + path + " HTTP/1.1\r\n";
  req_str += "Host: " + host + ":" + std::to_string(port) + "\r\n";
  req_str += "Upgrade: websocket\r\n";
  req_str += "Connection: Upgrade\r\n";
  req_str += "Sec-WebSocket-Key: " + client_key + "\r\n";
  req_str += "Sec-WebSocket-Version: 13\r\n";
  for (const auto &h : headers) {
    req_str += h.first + ": " + h.second + "\r\n";
  }
  req_str += "\r\n";

  if (strm.write(req_str.data(), req_str.size()) < 0) { return false; }

  // Verify 101 response and Sec-WebSocket-Accept header
  auto expected_accept = websocket_accept_key(client_key);
  return read_websocket_upgrade_response(strm, expected_accept,
                                         selected_subprotocol);
}

} // namespace detail

/*
 * Group 2: detail namespace - SSL common utilities
 */

#ifdef CPPHTTPLIB_SSL_ENABLED
namespace detail {

class SSLSocketStream final : public Stream {
public:
  SSLSocketStream(
      socket_t sock, tls::session_t session, time_t read_timeout_sec,
      time_t read_timeout_usec, time_t write_timeout_sec,
      time_t write_timeout_usec, time_t max_timeout_msec = 0,
      std::chrono::time_point<std::chrono::steady_clock> start_time =
          (std::chrono::steady_clock::time_point::min)());
  ~SSLSocketStream() override;

  bool is_readable() const override;
  bool wait_readable() const override;
  bool wait_writable() const override;
  bool is_peer_alive() const override;
  ssize_t read(char *ptr, size_t size) override;
  ssize_t write(const char *ptr, size_t size) override;
  void get_remote_ip_and_port(std::string &ip, int &port) const override;
  void get_local_ip_and_port(std::string &ip, int &port) const override;
  socket_t socket() const override;
  time_t duration() const override;
  void set_read_timeout(time_t sec, time_t usec = 0) override;

private:
  socket_t sock_;
  tls::session_t session_;
  time_t read_timeout_sec_;
  time_t read_timeout_usec_;
  time_t write_timeout_sec_;
  time_t write_timeout_usec_;
  time_t max_timeout_msec_;
  const std::chrono::time_point<std::chrono::steady_clock> start_time_;
};

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
std::string message_digest(const std::string &s, const EVP_MD *algo) {
  auto context = std::unique_ptr<EVP_MD_CTX, decltype(&EVP_MD_CTX_free)>(
      EVP_MD_CTX_new(), EVP_MD_CTX_free);

  unsigned int hash_length = 0;
  unsigned char hash[EVP_MAX_MD_SIZE];

  EVP_DigestInit_ex(context.get(), algo, nullptr);
  EVP_DigestUpdate(context.get(), s.c_str(), s.size());
  EVP_DigestFinal_ex(context.get(), hash, &hash_length);

  std::stringstream ss;
  for (auto i = 0u; i < hash_length; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }

  return ss.str();
}

std::string MD5(const std::string &s) {
  return message_digest(s, EVP_md5());
}

std::string SHA_256(const std::string &s) {
  return message_digest(s, EVP_sha256());
}

std::string SHA_512(const std::string &s) {
  return message_digest(s, EVP_sha512());
}
#elif defined(CPPHTTPLIB_MBEDTLS_SUPPORT)
namespace {
template <size_t N>
std::string hash_to_hex(const unsigned char (&hash)[N]) {
  std::stringstream ss;
  for (size_t i = 0; i < N; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }
  return ss.str();
}
} // namespace

std::string MD5(const std::string &s) {
  unsigned char hash[16];
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_md5(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
              hash);
#else
  mbedtls_md5_ret(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                  hash);
#endif
  return hash_to_hex(hash);
}

std::string SHA_256(const std::string &s) {
  unsigned char hash[32];
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_sha256(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                 hash, 0);
#else
  mbedtls_sha256_ret(reinterpret_cast<const unsigned char *>(s.c_str()),
                     s.size(), hash, 0);
#endif
  return hash_to_hex(hash);
}

std::string SHA_512(const std::string &s) {
  unsigned char hash[64];
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_sha512(reinterpret_cast<const unsigned char *>(s.c_str()), s.size(),
                 hash, 0);
#else
  mbedtls_sha512_ret(reinterpret_cast<const unsigned char *>(s.c_str()),
                     s.size(), hash, 0);
#endif
  return hash_to_hex(hash);
}
#elif defined(CPPHTTPLIB_WOLFSSL_SUPPORT)
namespace {
template <size_t N>
std::string hash_to_hex(const unsigned char (&hash)[N]) {
  std::stringstream ss;
  for (size_t i = 0; i < N; ++i) {
    ss << std::hex << std::setw(2) << std::setfill('0')
       << static_cast<unsigned int>(hash[i]);
  }
  return ss.str();
}
} // namespace

std::string MD5(const std::string &s) {
  unsigned char hash[WC_MD5_DIGEST_SIZE];
  wc_Md5Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
             static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}

std::string SHA_256(const std::string &s) {
  unsigned char hash[WC_SHA256_DIGEST_SIZE];
  wc_Sha256Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
                static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}

std::string SHA_512(const std::string &s) {
  unsigned char hash[WC_SHA512_DIGEST_SIZE];
  wc_Sha512Hash(reinterpret_cast<const unsigned char *>(s.c_str()),
                static_cast<word32>(s.size()), hash);
  return hash_to_hex(hash);
}
#endif

bool is_ip_address(const std::string &host) {
  struct in_addr addr4;
  struct in6_addr addr6;
  return inet_pton(AF_INET, host.c_str(), &addr4) == 1 ||
         inet_pton(AF_INET6, host.c_str(), &addr6) == 1;
}

template <typename T>
bool process_server_socket_ssl(
    const std::atomic<socket_t> &svr_sock, tls::session_t session,
    socket_t sock, size_t keep_alive_max_count, time_t keep_alive_timeout_sec,
    time_t read_timeout_sec, time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, T callback) {
  return process_server_socket_core(
      svr_sock, sock, keep_alive_max_count, keep_alive_timeout_sec,
      [&](bool close_connection, bool &connection_closed) {
        SSLSocketStream strm(sock, session, read_timeout_sec, read_timeout_usec,
                             write_timeout_sec, write_timeout_usec);
        return callback(strm, close_connection, connection_closed);
      });
}

template <typename T>
bool process_client_socket_ssl(
    tls::session_t session, socket_t sock, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time, T callback) {
  SSLSocketStream strm(sock, session, read_timeout_sec, read_timeout_usec,
                       write_timeout_sec, write_timeout_usec, max_timeout_msec,
                       start_time);
  return callback(strm);
}

std::pair<std::string, std::string> make_digest_authentication_header(
    const Request &req, const std::map<std::string, std::string> &auth,
    size_t cnonce_count, const std::string &cnonce, const std::string &username,
    const std::string &password, bool is_proxy = false) {
  std::string nc;
  {
    std::stringstream ss;
    ss << std::setfill('0') << std::setw(8) << std::hex << cnonce_count;
    nc = ss.str();
  }

  std::string qop;
  if (auth.find("qop") != auth.end()) {
    qop = auth.at("qop");
    if (qop.find("auth-int") != std::string::npos) {
      qop = "auth-int";
    } else if (qop.find("auth") != std::string::npos) {
      qop = "auth";
    } else {
      qop.clear();
    }
  }

  std::string algo = "MD5";
  if (auth.find("algorithm") != auth.end()) { algo = auth.at("algorithm"); }

  std::string response;
  {
    auto H = algo == "SHA-256"   ? detail::SHA_256
             : algo == "SHA-512" ? detail::SHA_512
                                 : detail::MD5;

    auto A1 = username + ":" + auth.at("realm") + ":" + password;

    auto A2 = req.method + ":" + req.path;
    if (qop == "auth-int") { A2 += ":" + H(req.body); }

    if (qop.empty()) {
      response = H(H(A1) + ":" + auth.at("nonce") + ":" + H(A2));
    } else {
      response = H(H(A1) + ":" + auth.at("nonce") + ":" + nc + ":" + cnonce +
                   ":" + qop + ":" + H(A2));
    }
  }

  auto opaque = (auth.find("opaque") != auth.end()) ? auth.at("opaque") : "";

  auto field = "Digest username=\"" + username + "\", realm=\"" +
               auth.at("realm") + "\", nonce=\"" + auth.at("nonce") +
               "\", uri=\"" + req.path + "\", algorithm=" + algo +
               (qop.empty() ? ", response=\""
                            : ", qop=" + qop + ", nc=" + nc + ", cnonce=\"" +
                                  cnonce + "\", response=\"") +
               response + "\"" +
               (opaque.empty() ? "" : ", opaque=\"" + opaque + "\"");

  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, field);
}

bool match_hostname(const std::string &pattern,
                           const std::string &hostname) {
  // Exact match (case-insensitive)
  if (detail::case_ignore::equal(hostname, pattern)) { return true; }

  // Split both pattern and hostname into components by '.'
  std::vector<std::string> pattern_components;
  if (!pattern.empty()) {
    split(pattern.data(), pattern.data() + pattern.size(), '.',
          [&](const char *b, const char *e) {
            pattern_components.emplace_back(b, e);
          });
  }

  std::vector<std::string> host_components;
  if (!hostname.empty()) {
    split(hostname.data(), hostname.data() + hostname.size(), '.',
          [&](const char *b, const char *e) {
            host_components.emplace_back(b, e);
          });
  }

  // Component count must match
  if (host_components.size() != pattern_components.size()) { return false; }

  // Compare each component with wildcard support
  // Supports: "*" (full wildcard), "prefix*" (partial wildcard)
  // https://bugs.launchpad.net/ubuntu/+source/firefox-3.0/+bug/376484
  auto itr = pattern_components.begin();
  for (const auto &h : host_components) {
    auto &p = *itr;
    if (!detail::case_ignore::equal(p, h) && p != "*") {
      bool partial_match = false;
      if (!p.empty() && p[p.size() - 1] == '*') {
        const auto prefix_length = p.size() - 1;
        if (prefix_length == 0) {
          partial_match = true;
        } else if (h.size() >= prefix_length) {
          partial_match =
              std::equal(p.begin(),
                         p.begin() + static_cast<std::string::difference_type>(
                                         prefix_length),
                         h.begin(), [](const char ca, const char cb) {
                           return detail::case_ignore::to_lower(ca) ==
                                  detail::case_ignore::to_lower(cb);
                         });
        }
      }
      if (!partial_match) { return false; }
    }
    ++itr;
  }

  return true;
}

#ifdef _WIN32
// Verify certificate using Windows CertGetCertificateChain API.
// This provides real-time certificate validation with Windows Update
// integration, independent of the TLS backend (OpenSSL or MbedTLS).
bool
verify_cert_with_windows_schannel(const std::vector<unsigned char> &der_cert,
                                  const std::string &hostname,
                                  bool verify_hostname, uint64_t &out_error) {
  if (der_cert.empty()) { return false; }

  out_error = 0;

  // Create Windows certificate context from DER data
  auto cert_context = CertCreateCertificateContext(
      X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, der_cert.data(),
      static_cast<DWORD>(der_cert.size()));

  if (!cert_context) {
    out_error = GetLastError();
    return false;
  }

  auto cert_guard =
      scope_exit([&] { CertFreeCertificateContext(cert_context); });

  // Setup chain parameters
  CERT_CHAIN_PARA chain_para = {};
  chain_para.cbSize = sizeof(chain_para);

  // Build certificate chain with revocation checking
  PCCERT_CHAIN_CONTEXT chain_context = nullptr;
  auto chain_result = CertGetCertificateChain(
      nullptr, cert_context, nullptr, cert_context->hCertStore, &chain_para,
      CERT_CHAIN_CACHE_END_CERT | CERT_CHAIN_REVOCATION_CHECK_END_CERT |
          CERT_CHAIN_REVOCATION_ACCUMULATIVE_TIMEOUT,
      nullptr, &chain_context);

  if (!chain_result || !chain_context) {
    out_error = GetLastError();
    return false;
  }

  auto chain_guard =
      scope_exit([&] { CertFreeCertificateChain(chain_context); });

  // Check if chain has errors
  if (chain_context->TrustStatus.dwErrorStatus != CERT_TRUST_NO_ERROR) {
    out_error = chain_context->TrustStatus.dwErrorStatus;
    return false;
  }

  // Verify SSL policy
  SSL_EXTRA_CERT_CHAIN_POLICY_PARA extra_policy_para = {};
  extra_policy_para.cbSize = sizeof(extra_policy_para);
#ifdef AUTHTYPE_SERVER
  extra_policy_para.dwAuthType = AUTHTYPE_SERVER;
#endif

  std::wstring whost;
  if (verify_hostname) {
    whost = u8string_to_wstring(hostname.c_str());
    extra_policy_para.pwszServerName = const_cast<wchar_t *>(whost.c_str());
  }

  CERT_CHAIN_POLICY_PARA policy_para = {};
  policy_para.cbSize = sizeof(policy_para);
#ifdef CERT_CHAIN_POLICY_IGNORE_ALL_REV_UNKNOWN_FLAGS
  policy_para.dwFlags = CERT_CHAIN_POLICY_IGNORE_ALL_REV_UNKNOWN_FLAGS;
#else
  policy_para.dwFlags = 0;
#endif
  policy_para.pvExtraPolicyPara = &extra_policy_para;

  CERT_CHAIN_POLICY_STATUS policy_status = {};
  policy_status.cbSize = sizeof(policy_status);

  if (!CertVerifyCertificateChainPolicy(CERT_CHAIN_POLICY_SSL, chain_context,
                                        &policy_para, &policy_status)) {
    out_error = GetLastError();
    return false;
  }

  if (policy_status.dwError != 0) {
    out_error = policy_status.dwError;
    return false;
  }

  return true;
}
#endif // _WIN32

bool setup_client_tls_session(const std::string &host, tls::ctx_t &ctx,
                                     tls::session_t &session, socket_t sock,
                                     bool server_certificate_verification,
                                     const std::string &ca_cert_file_path,
                                     tls::ca_store_t ca_cert_store,
                                     time_t timeout_sec, time_t timeout_usec) {
  using namespace tls;

  ctx = create_client_context();
  if (!ctx) { return false; }

  if (server_certificate_verification) {
    if (!ca_cert_file_path.empty()) {
      load_ca_file(ctx, ca_cert_file_path.c_str());
    }
    if (ca_cert_store) { set_ca_store(ctx, ca_cert_store); }
    load_system_certs(ctx);
  }

  bool is_ip = is_ip_address(host);

#ifdef CPPHTTPLIB_MBEDTLS_SUPPORT
  if (is_ip && server_certificate_verification) {
    set_verify_client(ctx, false);
  } else {
    set_verify_client(ctx, server_certificate_verification);
  }
#endif

  session = create_session(ctx, sock);
  if (!session) { return false; }

  // RFC 6066: SNI must not be set for IP addresses
  if (!is_ip) { set_sni(session, host.c_str()); }
  if (server_certificate_verification) { set_hostname(session, host.c_str()); }

  if (!connect_nonblocking(session, sock, timeout_sec, timeout_usec, nullptr)) {
    return false;
  }

  if (server_certificate_verification) {
    if (get_verify_result(session) != 0) { return false; }
  }

  return true;
}

} // namespace detail
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 3: httplib namespace - Non-SSL public API implementations
 */

void default_socket_options(socket_t sock) {
  detail::set_socket_opt(sock, SOL_SOCKET,
#ifdef SO_REUSEPORT
                         SO_REUSEPORT,
#else
                         SO_REUSEADDR,
#endif
                         1);
}

std::string get_bearer_token_auth(const Request &req) {
  if (req.has_header("Authorization")) {
    constexpr auto bearer_header_prefix_len = detail::str_len("Bearer ");
    return req.get_header_value("Authorization")
        .substr(bearer_header_prefix_len);
  }
  return "";
}

const char *status_message(int status) {
  switch (status) {
  case StatusCode::Continue_100: return "Continue";
  case StatusCode::SwitchingProtocol_101: return "Switching Protocol";
  case StatusCode::Processing_102: return "Processing";
  case StatusCode::EarlyHints_103: return "Early Hints";
  case StatusCode::OK_200: return "OK";
  case StatusCode::Created_201: return "Created";
  case StatusCode::Accepted_202: return "Accepted";
  case StatusCode::NonAuthoritativeInformation_203:
    return "Non-Authoritative Information";
  case StatusCode::NoContent_204: return "No Content";
  case StatusCode::ResetContent_205: return "Reset Content";
  case StatusCode::PartialContent_206: return "Partial Content";
  case StatusCode::MultiStatus_207: return "Multi-Status";
  case StatusCode::AlreadyReported_208: return "Already Reported";
  case StatusCode::IMUsed_226: return "IM Used";
  case StatusCode::MultipleChoices_300: return "Multiple Choices";
  case StatusCode::MovedPermanently_301: return "Moved Permanently";
  case StatusCode::Found_302: return "Found";
  case StatusCode::SeeOther_303: return "See Other";
  case StatusCode::NotModified_304: return "Not Modified";
  case StatusCode::UseProxy_305: return "Use Proxy";
  case StatusCode::unused_306: return "unused";
  case StatusCode::TemporaryRedirect_307: return "Temporary Redirect";
  case StatusCode::PermanentRedirect_308: return "Permanent Redirect";
  case StatusCode::BadRequest_400: return "Bad Request";
  case StatusCode::Unauthorized_401: return "Unauthorized";
  case StatusCode::PaymentRequired_402: return "Payment Required";
  case StatusCode::Forbidden_403: return "Forbidden";
  case StatusCode::NotFound_404: return "Not Found";
  case StatusCode::MethodNotAllowed_405: return "Method Not Allowed";
  case StatusCode::NotAcceptable_406: return "Not Acceptable";
  case StatusCode::ProxyAuthenticationRequired_407:
    return "Proxy Authentication Required";
  case StatusCode::RequestTimeout_408: return "Request Timeout";
  case StatusCode::Conflict_409: return "Conflict";
  case StatusCode::Gone_410: return "Gone";
  case StatusCode::LengthRequired_411: return "Length Required";
  case StatusCode::PreconditionFailed_412: return "Precondition Failed";
  case StatusCode::PayloadTooLarge_413: return "Payload Too Large";
  case StatusCode::UriTooLong_414: return "URI Too Long";
  case StatusCode::UnsupportedMediaType_415: return "Unsupported Media Type";
  case StatusCode::RangeNotSatisfiable_416: return "Range Not Satisfiable";
  case StatusCode::ExpectationFailed_417: return "Expectation Failed";
  case StatusCode::ImATeapot_418: return "I'm a teapot";
  case StatusCode::MisdirectedRequest_421: return "Misdirected Request";
  case StatusCode::UnprocessableContent_422: return "Unprocessable Content";
  case StatusCode::Locked_423: return "Locked";
  case StatusCode::FailedDependency_424: return "Failed Dependency";
  case StatusCode::TooEarly_425: return "Too Early";
  case StatusCode::UpgradeRequired_426: return "Upgrade Required";
  case StatusCode::PreconditionRequired_428: return "Precondition Required";
  case StatusCode::TooManyRequests_429: return "Too Many Requests";
  case StatusCode::RequestHeaderFieldsTooLarge_431:
    return "Request Header Fields Too Large";
  case StatusCode::UnavailableForLegalReasons_451:
    return "Unavailable For Legal Reasons";
  case StatusCode::NotImplemented_501: return "Not Implemented";
  case StatusCode::BadGateway_502: return "Bad Gateway";
  case StatusCode::ServiceUnavailable_503: return "Service Unavailable";
  case StatusCode::GatewayTimeout_504: return "Gateway Timeout";
  case StatusCode::HttpVersionNotSupported_505:
    return "HTTP Version Not Supported";
  case StatusCode::VariantAlsoNegotiates_506: return "Variant Also Negotiates";
  case StatusCode::InsufficientStorage_507: return "Insufficient Storage";
  case StatusCode::LoopDetected_508: return "Loop Detected";
  case StatusCode::NotExtended_510: return "Not Extended";
  case StatusCode::NetworkAuthenticationRequired_511:
    return "Network Authentication Required";

  default:
  case StatusCode::InternalServerError_500: return "Internal Server Error";
  }
}

std::string to_string(const Error error) {
  switch (error) {
  case Error::Success: return "Success (no error)";
  case Error::Unknown: return "Unknown";
  case Error::Connection: return "Could not establish connection";
  case Error::BindIPAddress: return "Failed to bind IP address";
  case Error::Read: return "Failed to read connection";
  case Error::Write: return "Failed to write connection";
  case Error::ExceedRedirectCount: return "Maximum redirect count exceeded";
  case Error::Canceled: return "Connection handling canceled";
  case Error::SSLConnection: return "SSL connection failed";
  case Error::SSLLoadingCerts: return "SSL certificate loading failed";
  case Error::SSLServerVerification: return "SSL server verification failed";
  case Error::SSLServerHostnameVerification:
    return "SSL server hostname verification failed";
  case Error::UnsupportedMultipartBoundaryChars:
    return "Unsupported HTTP multipart boundary characters";
  case Error::Compression: return "Compression failed";
  case Error::ConnectionTimeout: return "Connection timed out";
  case Error::ProxyConnection: return "Proxy connection failed";
  case Error::ConnectionClosed: return "Connection closed by server";
  case Error::Timeout: return "Read timeout";
  case Error::ResourceExhaustion: return "Resource exhaustion";
  case Error::TooManyFormDataFiles: return "Too many form data files";
  case Error::ExceedMaxPayloadSize: return "Exceeded maximum payload size";
  case Error::ExceedUriMaxLength: return "Exceeded maximum URI length";
  case Error::ExceedMaxSocketDescriptorCount:
    return "Exceeded maximum socket descriptor count";
  case Error::InvalidRequestLine: return "Invalid request line";
  case Error::InvalidHTTPMethod: return "Invalid HTTP method";
  case Error::InvalidHTTPVersion: return "Invalid HTTP version";
  case Error::InvalidHeaders: return "Invalid headers";
  case Error::MultipartParsing: return "Multipart parsing failed";
  case Error::OpenFile: return "Failed to open file";
  case Error::Listen: return "Failed to listen on socket";
  case Error::GetSockName: return "Failed to get socket name";
  case Error::UnsupportedAddressFamily: return "Unsupported address family";
  case Error::HTTPParsing: return "HTTP parsing failed";
  case Error::InvalidRangeHeader: return "Invalid Range header";
  default: break;
  }

  return "Invalid";
}

std::ostream &operator<<(std::ostream &os, const Error &obj) {
  os << to_string(obj);
  os << " (" << static_cast<std::underlying_type<Error>::type>(obj) << ')';
  return os;
}

std::string hosted_at(const std::string &hostname) {
  std::vector<std::string> addrs;
  hosted_at(hostname, addrs);
  if (addrs.empty()) { return std::string(); }
  return addrs[0];
}

void hosted_at(const std::string &hostname,
                      std::vector<std::string> &addrs) {
  struct addrinfo hints;
  struct addrinfo *result;

  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_family = AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;

  if (detail::getaddrinfo_with_timeout(hostname.c_str(), nullptr, &hints,
                                       &result, 0)) {
#if defined __linux__ && !defined __ANDROID__
    res_init();
#endif
    return;
  }
  auto se = detail::scope_exit([&] { freeaddrinfo(result); });

  for (auto rp = result; rp; rp = rp->ai_next) {
    const auto &addr =
        *reinterpret_cast<struct sockaddr_storage *>(rp->ai_addr);
    std::string ip;
    auto dummy = -1;
    if (detail::get_ip_and_port(addr, sizeof(struct sockaddr_storage), ip,
                                dummy)) {
      addrs.emplace_back(std::move(ip));
    }
  }
}

std::string encode_uri_component(const std::string &value) {
  std::ostringstream escaped;
  escaped.fill('0');
  escaped << std::hex;

  for (auto c : value) {
    if (std::isalnum(static_cast<uint8_t>(c)) || c == '-' || c == '_' ||
        c == '.' || c == '!' || c == '~' || c == '*' || c == '\'' || c == '(' ||
        c == ')') {
      escaped << c;
    } else {
      escaped << std::uppercase;
      escaped << '%' << std::setw(2)
              << static_cast<int>(static_cast<unsigned char>(c));
      escaped << std::nouppercase;
    }
  }

  return escaped.str();
}

std::string encode_uri(const std::string &value) {
  std::ostringstream escaped;
  escaped.fill('0');
  escaped << std::hex;

  for (auto c : value) {
    if (std::isalnum(static_cast<uint8_t>(c)) || c == '-' || c == '_' ||
        c == '.' || c == '!' || c == '~' || c == '*' || c == '\'' || c == '(' ||
        c == ')' || c == ';' || c == '/' || c == '?' || c == ':' || c == '@' ||
        c == '&' || c == '=' || c == '+' || c == '$' || c == ',' || c == '#') {
      escaped << c;
    } else {
      escaped << std::uppercase;
      escaped << '%' << std::setw(2)
              << static_cast<int>(static_cast<unsigned char>(c));
      escaped << std::nouppercase;
    }
  }

  return escaped.str();
}

std::string decode_uri_component(const std::string &value) {
  std::string result;

  for (size_t i = 0; i < value.size(); i++) {
    if (value[i] == '%' && i + 2 < value.size()) {
      auto val = 0;
      if (detail::from_hex_to_i(value, i + 1, 2, val)) {
        result += static_cast<char>(val);
        i += 2;
      } else {
        result += value[i];
      }
    } else {
      result += value[i];
    }
  }

  return result;
}

std::string decode_uri(const std::string &value) {
  std::string result;

  for (size_t i = 0; i < value.size(); i++) {
    if (value[i] == '%' && i + 2 < value.size()) {
      auto val = 0;
      if (detail::from_hex_to_i(value, i + 1, 2, val)) {
        result += static_cast<char>(val);
        i += 2;
      } else {
        result += value[i];
      }
    } else {
      result += value[i];
    }
  }

  return result;
}

std::string encode_path_component(const std::string &component) {
  std::string result;
  result.reserve(component.size() * 3);

  for (size_t i = 0; i < component.size(); i++) {
    auto c = static_cast<unsigned char>(component[i]);

    // Unreserved characters per RFC 3986: ALPHA / DIGIT / "-" / "." / "_" / "~"
    if (std::isalnum(c) || c == '-' || c == '.' || c == '_' || c == '~') {
      result += static_cast<char>(c);
    }
    // Path-safe sub-delimiters: "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" /
    // "," / ";" / "="
    else if (c == '!' || c == '$' || c == '&' || c == '\'' || c == '(' ||
             c == ')' || c == '*' || c == '+' || c == ',' || c == ';' ||
             c == '=') {
      result += static_cast<char>(c);
    }
    // Colon is allowed in path segments except first segment
    else if (c == ':') {
      result += static_cast<char>(c);
    }
    // @ is allowed in path
    else if (c == '@') {
      result += static_cast<char>(c);
    } else {
      result += '%';
      char hex[3];
      snprintf(hex, sizeof(hex), "%02X", c);
      result.append(hex, 2);
    }
  }
  return result;
}

std::string decode_path_component(const std::string &component) {
  std::string result;
  result.reserve(component.size());

  for (size_t i = 0; i < component.size(); i++) {
    if (component[i] == '%' && i + 1 < component.size()) {
      if (component[i + 1] == 'u') {
        // Unicode %uXXXX encoding
        auto val = 0;
        if (detail::from_hex_to_i(component, i + 2, 4, val)) {
          // 4 digits Unicode codes: val is 0x0000-0xFFFF (from 4 hex digits),
          // so to_utf8 writes at most 3 bytes. buff[4] is safe.
          char buff[4];
          size_t len = detail::to_utf8(val, buff);
          if (len > 0) { result.append(buff, len); }
          i += 5; // 'u0000'
        } else {
          result += component[i];
        }
      } else {
        // Standard %XX encoding
        auto val = 0;
        if (detail::from_hex_to_i(component, i + 1, 2, val)) {
          // 2 digits hex codes
          result += static_cast<char>(val);
          i += 2; // 'XX'
        } else {
          result += component[i];
        }
      }
    } else {
      result += component[i];
    }
  }
  return result;
}

std::string encode_query_component(const std::string &component,
                                          bool space_as_plus) {
  std::string result;
  result.reserve(component.size() * 3);

  for (size_t i = 0; i < component.size(); i++) {
    auto c = static_cast<unsigned char>(component[i]);

    // Unreserved characters per RFC 3986
    if (std::isalnum(c) || c == '-' || c == '.' || c == '_' || c == '~') {
      result += static_cast<char>(c);
    }
    // Space handling
    else if (c == ' ') {
      if (space_as_plus) {
        result += '+';
      } else {
        result += "%20";
      }
    }
    // Plus sign handling
    else if (c == '+') {
      if (space_as_plus) {
        result += "%2B";
      } else {
        result += static_cast<char>(c);
      }
    }
    // Query-safe sub-delimiters (excluding & and = which are query delimiters)
    else if (c == '!' || c == '$' || c == '\'' || c == '(' || c == ')' ||
             c == '*' || c == ',' || c == ';') {
      result += static_cast<char>(c);
    }
    // Colon and @ are allowed in query
    else if (c == ':' || c == '@') {
      result += static_cast<char>(c);
    }
    // Forward slash is allowed in query values
    else if (c == '/') {
      result += static_cast<char>(c);
    }
    // Question mark is allowed in query values (after first ?)
    else if (c == '?') {
      result += static_cast<char>(c);
    } else {
      result += '%';
      char hex[3];
      snprintf(hex, sizeof(hex), "%02X", c);
      result.append(hex, 2);
    }
  }
  return result;
}

std::string decode_query_component(const std::string &component,
                                          bool plus_as_space) {
  std::string result;
  result.reserve(component.size());

  for (size_t i = 0; i < component.size(); i++) {
    if (component[i] == '%' && i + 2 < component.size()) {
      std::string hex = component.substr(i + 1, 2);
      char *end;
      unsigned long value = std::strtoul(hex.c_str(), &end, 16);
      if (end == hex.c_str() + 2) {
        result += static_cast<char>(value);
        i += 2;
      } else {
        result += component[i];
      }
    } else if (component[i] == '+' && plus_as_space) {
      result += ' '; // + becomes space in form-urlencoded
    } else {
      result += component[i];
    }
  }
  return result;
}

std::string sanitize_filename(const std::string &filename) {
  // Extract basename: find the last path separator (/ or \)
  auto pos = filename.find_last_of("/\\");
  auto result =
      (pos != std::string::npos) ? filename.substr(pos + 1) : filename;

  // Strip null bytes
  result.erase(std::remove(result.begin(), result.end(), '\0'), result.end());

  // Trim whitespace
  {
    auto start = result.find_first_not_of(" \t");
    auto end = result.find_last_not_of(" \t");
    result = (start == std::string::npos)
                 ? ""
                 : result.substr(start, end - start + 1);
  }

  // Reject . and ..
  if (result == "." || result == "..") { return ""; }

  return result;
}

std::string append_query_params(const std::string &path,
                                       const Params &params) {
  std::string path_with_query = path;
  thread_local const std::regex re("[^?]+\\?.*");
  auto delm = std::regex_match(path, re) ? '&' : '?';
  path_with_query += delm + detail::params_to_query_str(params);
  return path_with_query;
}

// Header utilities
std::pair<std::string, std::string>
make_range_header(const Ranges &ranges) {
  std::string field = "bytes=";
  auto i = 0;
  for (const auto &r : ranges) {
    if (i != 0) { field += ", "; }
    if (r.first != -1) { field += std::to_string(r.first); }
    field += '-';
    if (r.second != -1) { field += std::to_string(r.second); }
    i++;
  }
  return std::make_pair("Range", std::move(field));
}

std::pair<std::string, std::string>
make_basic_authentication_header(const std::string &username,
                                 const std::string &password, bool is_proxy) {
  auto field = "Basic " + detail::base64_encode(username + ":" + password);
  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, std::move(field));
}

std::pair<std::string, std::string>
make_bearer_token_authentication_header(const std::string &token,
                                        bool is_proxy = false) {
  auto field = "Bearer " + token;
  auto key = is_proxy ? "Proxy-Authorization" : "Authorization";
  return std::make_pair(key, std::move(field));
}

// Request implementation
size_t Request::get_header_value_u64(const std::string &key, size_t def,
                                            size_t id) const {
  return detail::get_header_value_u64(headers, key, def, id);
}

bool Request::has_header(const std::string &key) const {
  return detail::has_header(headers, key);
}

std::string Request::get_header_value(const std::string &key,
                                             const char *def, size_t id) const {
  return detail::get_header_value(headers, key, def, id);
}

size_t Request::get_header_value_count(const std::string &key) const {
  auto r = headers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

void Request::set_header(const std::string &key,
                                const std::string &val) {
  if (detail::fields::is_field_name(key) &&
      detail::fields::is_field_value(val)) {
    headers.emplace(key, val);
  }
}

bool Request::has_trailer(const std::string &key) const {
  return trailers.find(key) != trailers.end();
}

std::string Request::get_trailer_value(const std::string &key,
                                              size_t id) const {
  auto rng = trailers.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second; }
  return std::string();
}

size_t Request::get_trailer_value_count(const std::string &key) const {
  auto r = trailers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

bool Request::has_param(const std::string &key) const {
  return params.find(key) != params.end();
}

std::string Request::get_param_value(const std::string &key,
                                            size_t id) const {
  auto rng = params.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second; }
  return std::string();
}

size_t Request::get_param_value_count(const std::string &key) const {
  auto r = params.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

bool Request::is_multipart_form_data() const {
  const auto &content_type = get_header_value("Content-Type");
  return detail::extract_media_type(content_type) == "multipart/form-data";
}

// Multipart FormData implementation
std::string MultipartFormData::get_field(const std::string &key,
                                                size_t id) const {
  auto rng = fields.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second.content; }
  return std::string();
}

std::vector<std::string>
MultipartFormData::get_fields(const std::string &key) const {
  std::vector<std::string> values;
  auto rng = fields.equal_range(key);
  for (auto it = rng.first; it != rng.second; it++) {
    values.push_back(it->second.content);
  }
  return values;
}

bool MultipartFormData::has_field(const std::string &key) const {
  return fields.find(key) != fields.end();
}

size_t MultipartFormData::get_field_count(const std::string &key) const {
  auto r = fields.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

FormData MultipartFormData::get_file(const std::string &key,
                                            size_t id) const {
  auto rng = files.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second; }
  return FormData();
}

std::vector<FormData>
MultipartFormData::get_files(const std::string &key) const {
  std::vector<FormData> values;
  auto rng = files.equal_range(key);
  for (auto it = rng.first; it != rng.second; it++) {
    values.push_back(it->second);
  }
  return values;
}

bool MultipartFormData::has_file(const std::string &key) const {
  return files.find(key) != files.end();
}

size_t MultipartFormData::get_file_count(const std::string &key) const {
  auto r = files.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

// Response implementation
size_t Response::get_header_value_u64(const std::string &key, size_t def,
                                             size_t id) const {
  return detail::get_header_value_u64(headers, key, def, id);
}

bool Response::has_header(const std::string &key) const {
  return headers.find(key) != headers.end();
}

std::string Response::get_header_value(const std::string &key,
                                              const char *def,
                                              size_t id) const {
  return detail::get_header_value(headers, key, def, id);
}

size_t Response::get_header_value_count(const std::string &key) const {
  auto r = headers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

void Response::set_header(const std::string &key,
                                 const std::string &val) {
  if (detail::fields::is_field_name(key) &&
      detail::fields::is_field_value(val)) {
    headers.emplace(key, val);
  }
}
bool Response::has_trailer(const std::string &key) const {
  return trailers.find(key) != trailers.end();
}

std::string Response::get_trailer_value(const std::string &key,
                                               size_t id) const {
  auto rng = trailers.equal_range(key);
  auto it = rng.first;
  std::advance(it, static_cast<ssize_t>(id));
  if (it != rng.second) { return it->second; }
  return std::string();
}

size_t Response::get_trailer_value_count(const std::string &key) const {
  auto r = trailers.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

void Response::set_redirect(const std::string &url, int stat) {
  if (detail::fields::is_field_value(url)) {
    set_header("Location", url);
    if (300 <= stat && stat < 400) {
      this->status = stat;
    } else {
      this->status = StatusCode::Found_302;
    }
  }
}

void Response::set_content(const char *s, size_t n,
                                  const std::string &content_type) {
  body.assign(s, n);

  auto rng = headers.equal_range("Content-Type");
  headers.erase(rng.first, rng.second);
  set_header("Content-Type", content_type);
}

void Response::set_content(const std::string &s,
                                  const std::string &content_type) {
  set_content(s.data(), s.size(), content_type);
}

void Response::set_content(std::string &&s,
                                  const std::string &content_type) {
  body = std::move(s);

  auto rng = headers.equal_range("Content-Type");
  headers.erase(rng.first, rng.second);
  set_header("Content-Type", content_type);
}

void Response::set_content_provider(
    size_t in_length, const std::string &content_type, ContentProvider provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = in_length;
  if (in_length > 0) { content_provider_ = std::move(provider); }
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = false;
}

void Response::set_content_provider(
    const std::string &content_type, ContentProviderWithoutLength provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = 0;
  content_provider_ = detail::ContentProviderAdapter(std::move(provider));
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = false;
}

void Response::set_chunked_content_provider(
    const std::string &content_type, ContentProviderWithoutLength provider,
    ContentProviderResourceReleaser resource_releaser) {
  set_header("Content-Type", content_type);
  content_length_ = 0;
  content_provider_ = detail::ContentProviderAdapter(std::move(provider));
  content_provider_resource_releaser_ = std::move(resource_releaser);
  is_chunked_content_provider_ = true;
}

void Response::set_file_content(const std::string &path,
                                       const std::string &content_type) {
  file_content_path_ = path;
  file_content_content_type_ = content_type;
}

void Response::set_file_content(const std::string &path) {
  file_content_path_ = path;
}

// Result implementation
size_t Result::get_request_header_value_u64(const std::string &key,
                                                   size_t def,
                                                   size_t id) const {
  return detail::get_header_value_u64(request_headers_, key, def, id);
}

bool Result::has_request_header(const std::string &key) const {
  return request_headers_.find(key) != request_headers_.end();
}

std::string Result::get_request_header_value(const std::string &key,
                                                    const char *def,
                                                    size_t id) const {
  return detail::get_header_value(request_headers_, key, def, id);
}

size_t
Result::get_request_header_value_count(const std::string &key) const {
  auto r = request_headers_.equal_range(key);
  return static_cast<size_t>(std::distance(r.first, r.second));
}

// Stream implementation
ssize_t Stream::write(const char *ptr) {
  return write(ptr, strlen(ptr));
}

ssize_t Stream::write(const std::string &s) {
  return write(s.data(), s.size());
}

// BodyReader implementation
ssize_t detail::BodyReader::read(char *buf, size_t len) {
  if (!stream) {
    last_error = Error::Connection;
    return -1;
  }
  if (eof) { return 0; }

  if (!chunked) {
    // Content-Length based reading
    if (has_content_length && bytes_read >= content_length) {
      eof = true;
      return 0;
    }

    auto to_read = len;
    if (has_content_length) {
      auto remaining = content_length - bytes_read;
      to_read = (std::min)(len, remaining);
    }
    auto n = stream->read(buf, to_read);

    if (n < 0) {
      last_error = stream->get_error();
      if (last_error == Error::Success) { last_error = Error::Read; }
      eof = true;
      return n;
    }
    if (n == 0) {
      // Unexpected EOF before content_length
      last_error = stream->get_error();
      if (last_error == Error::Success) { last_error = Error::Read; }
      eof = true;
      return 0;
    }

    bytes_read += static_cast<size_t>(n);
    if (has_content_length && bytes_read >= content_length) { eof = true; }
    if (payload_max_length > 0 && bytes_read > payload_max_length) {
      last_error = Error::ExceedMaxPayloadSize;
      eof = true;
      return -1;
    }
    return n;
  }

  // Chunked transfer encoding: delegate to shared decoder instance.
  if (!chunked_decoder) { chunked_decoder.reset(new ChunkedDecoder(*stream)); }

  size_t chunk_offset = 0;
  size_t chunk_total = 0;
  auto n = chunked_decoder->read_payload(buf, len, chunk_offset, chunk_total);
  if (n < 0) {
    last_error = stream->get_error();
    if (last_error == Error::Success) { last_error = Error::Read; }
    eof = true;
    return n;
  }

  if (n == 0) {
    // Final chunk observed. Leave trailer parsing to the caller (StreamHandle).
    eof = true;
    return 0;
  }

  bytes_read += static_cast<size_t>(n);
  if (payload_max_length > 0 && bytes_read > payload_max_length) {
    last_error = Error::ExceedMaxPayloadSize;
    eof = true;
    return -1;
  }
  return n;
}

// ThreadPool implementation
ThreadPool::ThreadPool(size_t n, size_t max_n, size_t mqr)
    : base_thread_count_(n), max_queued_requests_(mqr), idle_thread_count_(0),
      shutdown_(false) {
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  if (max_n != 0 && max_n < n) {
    std::string msg = "max_threads must be >= base_threads";
    throw std::invalid_argument(msg);
  }
#endif
  max_thread_count_ = max_n == 0 ? n : max_n;
  threads_.reserve(base_thread_count_);
  for (size_t i = 0; i < base_thread_count_; i++) {
    threads_.emplace_back(std::thread([this]() { worker(false); }));
  }
}

bool ThreadPool::enqueue(std::function<void()> fn) {
  {
    std::unique_lock<std::mutex> lock(mutex_);
    if (shutdown_) { return false; }
    if (max_queued_requests_ > 0 && jobs_.size() >= max_queued_requests_) {
      return false;
    }
    jobs_.push_back(std::move(fn));

    // Spawn a dynamic thread if no idle threads and under max
    if (idle_thread_count_ == 0 &&
        threads_.size() + dynamic_threads_.size() < max_thread_count_) {
      cleanup_finished_threads();
      dynamic_threads_.emplace_back(std::thread([this]() { worker(true); }));
    }
  }

  cond_.notify_one();
  return true;
}

void ThreadPool::shutdown() {
  {
    std::unique_lock<std::mutex> lock(mutex_);
    shutdown_ = true;
  }

  cond_.notify_all();

  for (auto &t : threads_) {
    if (t.joinable()) { t.join(); }
  }

  // Move dynamic_threads_ to a local list under the lock to avoid racing
  // with worker threads that call move_to_finished() concurrently.
  std::list<std::thread> remaining_dynamic;
  {
    std::unique_lock<std::mutex> lock(mutex_);
    remaining_dynamic = std::move(dynamic_threads_);
  }
  for (auto &t : remaining_dynamic) {
    if (t.joinable()) { t.join(); }
  }

  std::unique_lock<std::mutex> lock(mutex_);
  cleanup_finished_threads();
}

void ThreadPool::move_to_finished(std::thread::id id) {
  // Must be called with mutex_ held
  for (auto it = dynamic_threads_.begin(); it != dynamic_threads_.end(); ++it) {
    if (it->get_id() == id) {
      finished_threads_.push_back(std::move(*it));
      dynamic_threads_.erase(it);
      return;
    }
  }
}

void ThreadPool::cleanup_finished_threads() {
  // Must be called with mutex_ held
  for (auto &t : finished_threads_) {
    if (t.joinable()) { t.join(); }
  }
  finished_threads_.clear();
}

void ThreadPool::worker(bool is_dynamic) {
  for (;;) {
    std::function<void()> fn;
    {
      std::unique_lock<std::mutex> lock(mutex_);
      idle_thread_count_++;

      if (is_dynamic) {
        auto has_work = cond_.wait_for(
            lock, std::chrono::seconds(CPPHTTPLIB_THREAD_POOL_IDLE_TIMEOUT),
            [&] { return !jobs_.empty() || shutdown_; });
        if (!has_work) {
          // Timed out with no work - exit this dynamic thread
          idle_thread_count_--;
          move_to_finished(std::this_thread::get_id());
          break;
        }
      } else {
        cond_.wait(lock, [&] { return !jobs_.empty() || shutdown_; });
      }

      idle_thread_count_--;

      if (shutdown_ && jobs_.empty()) { break; }

      fn = std::move(jobs_.front());
      jobs_.pop_front();
    }

    assert(true == static_cast<bool>(fn));
    fn();

    // Dynamic thread: exit if queue is empty after task completion
    if (is_dynamic) {
      std::unique_lock<std::mutex> lock(mutex_);
      if (jobs_.empty()) {
        move_to_finished(std::this_thread::get_id());
        break;
      }
    }
  }

#if defined(CPPHTTPLIB_OPENSSL_SUPPORT) && !defined(OPENSSL_IS_BORINGSSL) &&   \
    !defined(LIBRESSL_VERSION_NUMBER)
  OPENSSL_thread_stop();
#endif
}

/*
 * Group 1 (continued): detail namespace - Stream implementations
 */

namespace detail {

void calc_actual_timeout(time_t max_timeout_msec, time_t duration_msec,
                                time_t timeout_sec, time_t timeout_usec,
                                time_t &actual_timeout_sec,
                                time_t &actual_timeout_usec) {
  auto timeout_msec = (timeout_sec * 1000) + (timeout_usec / 1000);

  auto actual_timeout_msec =
      (std::min)(max_timeout_msec - duration_msec, timeout_msec);

  if (actual_timeout_msec < 0) { actual_timeout_msec = 0; }

  actual_timeout_sec = actual_timeout_msec / 1000;
  actual_timeout_usec = (actual_timeout_msec % 1000) * 1000;
}

// Socket stream implementation
SocketStream::SocketStream(
    socket_t sock, time_t read_timeout_sec, time_t read_timeout_usec,
    time_t write_timeout_sec, time_t write_timeout_usec,
    time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time)
    : sock_(sock), read_timeout_sec_(read_timeout_sec),
      read_timeout_usec_(read_timeout_usec),
      write_timeout_sec_(write_timeout_sec),
      write_timeout_usec_(write_timeout_usec),
      max_timeout_msec_(max_timeout_msec), start_time_(start_time),
      read_buff_(read_buff_size_, 0) {}

SocketStream::~SocketStream() = default;

bool SocketStream::is_readable() const {
  return read_buff_off_ < read_buff_content_size_;
}

bool SocketStream::wait_readable() const {
  if (max_timeout_msec_ <= 0) {
    return select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
  }

  time_t read_timeout_sec;
  time_t read_timeout_usec;
  calc_actual_timeout(max_timeout_msec_, duration(), read_timeout_sec_,
                      read_timeout_usec_, read_timeout_sec, read_timeout_usec);

  return select_read(sock_, read_timeout_sec, read_timeout_usec) > 0;
}

bool SocketStream::wait_writable() const {
  return select_write(sock_, write_timeout_sec_, write_timeout_usec_) > 0;
}

bool SocketStream::is_peer_alive() const {
  return detail::is_socket_alive(sock_);
}

ssize_t SocketStream::read(char *ptr, size_t size) {
#ifdef _WIN32
  size =
      (std::min)(size, static_cast<size_t>((std::numeric_limits<int>::max)()));
#else
  size = (std::min)(size,
                    static_cast<size_t>((std::numeric_limits<ssize_t>::max)()));
#endif

  if (read_buff_off_ < read_buff_content_size_) {
    auto remaining_size = read_buff_content_size_ - read_buff_off_;
    if (size <= remaining_size) {
      memcpy(ptr, read_buff_.data() + read_buff_off_, size);
      read_buff_off_ += size;
      return static_cast<ssize_t>(size);
    } else {
      memcpy(ptr, read_buff_.data() + read_buff_off_, remaining_size);
      read_buff_off_ += remaining_size;
      return static_cast<ssize_t>(remaining_size);
    }
  }

  if (!wait_readable()) {
    error_ = Error::Timeout;
    return -1;
  }

  read_buff_off_ = 0;
  read_buff_content_size_ = 0;

  if (size < read_buff_size_) {
    auto n = read_socket(sock_, read_buff_.data(), read_buff_size_,
                         CPPHTTPLIB_RECV_FLAGS);
    if (n <= 0) {
      if (n == 0) {
        error_ = Error::ConnectionClosed;
      } else {
        error_ = Error::Read;
      }
      return n;
    } else if (n <= static_cast<ssize_t>(size)) {
      memcpy(ptr, read_buff_.data(), static_cast<size_t>(n));
      return n;
    } else {
      memcpy(ptr, read_buff_.data(), size);
      read_buff_off_ = size;
      read_buff_content_size_ = static_cast<size_t>(n);
      return static_cast<ssize_t>(size);
    }
  } else {
    auto n = read_socket(sock_, ptr, size, CPPHTTPLIB_RECV_FLAGS);
    if (n <= 0) {
      if (n == 0) {
        error_ = Error::ConnectionClosed;
      } else {
        error_ = Error::Read;
      }
    }
    return n;
  }
}

ssize_t SocketStream::write(const char *ptr, size_t size) {
  if (!wait_writable()) { return -1; }

#if defined(_WIN32) && !defined(_WIN64)
  size =
      (std::min)(size, static_cast<size_t>((std::numeric_limits<int>::max)()));
#endif

  return send_socket(sock_, ptr, size, CPPHTTPLIB_SEND_FLAGS);
}

void SocketStream::get_remote_ip_and_port(std::string &ip,
                                                 int &port) const {
  return detail::get_remote_ip_and_port(sock_, ip, port);
}

void SocketStream::get_local_ip_and_port(std::string &ip,
                                                int &port) const {
  return detail::get_local_ip_and_port(sock_, ip, port);
}

socket_t SocketStream::socket() const { return sock_; }

time_t SocketStream::duration() const {
  return std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - start_time_)
      .count();
}

void SocketStream::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

// Buffer stream implementation
bool BufferStream::is_readable() const { return true; }

bool BufferStream::wait_readable() const { return true; }

bool BufferStream::wait_writable() const { return true; }

ssize_t BufferStream::read(char *ptr, size_t size) {
#if defined(_MSC_VER) && _MSC_VER < 1910
  auto len_read = buffer._Copy_s(ptr, size, size, position);
#else
  auto len_read = buffer.copy(ptr, size, position);
#endif
  position += static_cast<size_t>(len_read);
  return static_cast<ssize_t>(len_read);
}

ssize_t BufferStream::write(const char *ptr, size_t size) {
  buffer.append(ptr, size);
  return static_cast<ssize_t>(size);
}

void BufferStream::get_remote_ip_and_port(std::string & /*ip*/,
                                                 int & /*port*/) const {}

void BufferStream::get_local_ip_and_port(std::string & /*ip*/,
                                                int & /*port*/) const {}

socket_t BufferStream::socket() const { return 0; }

time_t BufferStream::duration() const { return 0; }

const std::string &BufferStream::get_buffer() const { return buffer; }

PathParamsMatcher::PathParamsMatcher(const std::string &pattern)
    : MatcherBase(pattern) {
  constexpr const char marker[] = "/:";

  // One past the last ending position of a path param substring
  std::size_t last_param_end = 0;

#ifndef CPPHTTPLIB_NO_EXCEPTIONS
  // Needed to ensure that parameter names are unique during matcher
  // construction
  // If exceptions are disabled, only last duplicate path
  // parameter will be set
  std::unordered_set<std::string> param_name_set;
#endif

  while (true) {
    const auto marker_pos = pattern.find(
        marker, last_param_end == 0 ? last_param_end : last_param_end - 1);
    if (marker_pos == std::string::npos) { break; }

    static_fragments_.push_back(
        pattern.substr(last_param_end, marker_pos - last_param_end + 1));

    const auto param_name_start = marker_pos + str_len(marker);

    auto sep_pos = pattern.find(separator, param_name_start);
    if (sep_pos == std::string::npos) { sep_pos = pattern.length(); }

    auto param_name =
        pattern.substr(param_name_start, sep_pos - param_name_start);

#ifndef CPPHTTPLIB_NO_EXCEPTIONS
    if (param_name_set.find(param_name) != param_name_set.cend()) {
      std::string msg = "Encountered path parameter '" + param_name +
                        "' multiple times in route pattern '" + pattern + "'.";
      throw std::invalid_argument(msg);
    }
#endif

    param_names_.push_back(std::move(param_name));

    last_param_end = sep_pos + 1;
  }

  if (last_param_end < pattern.length()) {
    static_fragments_.push_back(pattern.substr(last_param_end));
  }
}

bool PathParamsMatcher::match(Request &request) const {
  request.matches = std::smatch();
  request.path_params.clear();
  request.path_params.reserve(param_names_.size());

  // One past the position at which the path matched the pattern last time
  std::size_t starting_pos = 0;
  for (size_t i = 0; i < static_fragments_.size(); ++i) {
    const auto &fragment = static_fragments_[i];

    if (starting_pos + fragment.length() > request.path.length()) {
      return false;
    }

    // Avoid unnecessary allocation by using strncmp instead of substr +
    // comparison
    if (std::strncmp(request.path.c_str() + starting_pos, fragment.c_str(),
                     fragment.length()) != 0) {
      return false;
    }

    starting_pos += fragment.length();

    // Should only happen when we have a static fragment after a param
    // Example: '/users/:id/subscriptions'
    // The 'subscriptions' fragment here does not have a corresponding param
    if (i >= param_names_.size()) { continue; }

    auto sep_pos = request.path.find(separator, starting_pos);
    if (sep_pos == std::string::npos) { sep_pos = request.path.length(); }

    const auto &param_name = param_names_[i];

    request.path_params.emplace(
        param_name, request.path.substr(starting_pos, sep_pos - starting_pos));

    // Mark everything up to '/' as matched
    starting_pos = sep_pos + 1;
  }
  // Returns false if the path is longer than the pattern
  return starting_pos >= request.path.length();
}

bool RegexMatcher::match(Request &request) const {
  request.path_params.clear();
  return std::regex_match(request.path, request.matches, regex_);
}

// Enclose IPv6 address in brackets if needed
std::string prepare_host_string(const std::string &host) {
  // Enclose IPv6 address in brackets (but not if already enclosed)
  if (host.find(':') == std::string::npos ||
      (!host.empty() && host[0] == '[')) {
    // IPv4, hostname, or already bracketed IPv6
    return host;
  } else {
    // IPv6 address without brackets
    return "[" + host + "]";
  }
}

std::string make_host_and_port_string(const std::string &host, int port,
                                             bool is_ssl) {
  auto result = prepare_host_string(host);

  // Append port if not default
  if ((!is_ssl && port == 80) || (is_ssl && port == 443)) {
    ; // do nothing
  } else {
    result += ":" + std::to_string(port);
  }

  return result;
}

// Create "host:port" string always including port number (for CONNECT method)
std::string
make_host_and_port_string_always_port(const std::string &host, int port) {
  return prepare_host_string(host) + ":" + std::to_string(port);
}

template <typename T>
bool check_and_write_headers(Stream &strm, Headers &headers,
                                    T header_writer, Error &error) {
  for (const auto &h : headers) {
    if (!detail::fields::is_field_name(h.first) ||
        !detail::fields::is_field_value(h.second)) {
      error = Error::InvalidHeaders;
      return false;
    }
  }
  if (header_writer(strm, headers) <= 0) {
    error = Error::Write;
    return false;
  }
  return true;
}

} // namespace detail

/*
 * Group 2 (continued): detail namespace - SSLSocketStream implementation
 */

#ifdef CPPHTTPLIB_SSL_ENABLED
namespace detail {

// SSL socket stream implementation
SSLSocketStream::SSLSocketStream(
    socket_t sock, tls::session_t session, time_t read_timeout_sec,
    time_t read_timeout_usec, time_t write_timeout_sec,
    time_t write_timeout_usec, time_t max_timeout_msec,
    std::chrono::time_point<std::chrono::steady_clock> start_time)
    : sock_(sock), session_(session), read_timeout_sec_(read_timeout_sec),
      read_timeout_usec_(read_timeout_usec),
      write_timeout_sec_(write_timeout_sec),
      write_timeout_usec_(write_timeout_usec),
      max_timeout_msec_(max_timeout_msec), start_time_(start_time) {
#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
  // Clear AUTO_RETRY for proper non-blocking I/O timeout handling
  // Note: create_session() also clears this, but SSLClient currently
  // uses ssl_new() which does not. Until full TLS API migration is complete,
  // we need to ensure AUTO_RETRY is cleared here regardless of how the
  // SSL session was created.
  SSL_clear_mode(static_cast<SSL *>(session), SSL_MODE_AUTO_RETRY);
#endif
}

SSLSocketStream::~SSLSocketStream() = default;

bool SSLSocketStream::is_readable() const {
  return tls::pending(session_) > 0;
}

bool SSLSocketStream::wait_readable() const {
  if (max_timeout_msec_ <= 0) {
    return select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
  }

  time_t read_timeout_sec;
  time_t read_timeout_usec;
  calc_actual_timeout(max_timeout_msec_, duration(), read_timeout_sec_,
                      read_timeout_usec_, read_timeout_sec, read_timeout_usec);

  return select_read(sock_, read_timeout_sec, read_timeout_usec) > 0;
}

bool SSLSocketStream::wait_writable() const {
  return select_write(sock_, write_timeout_sec_, write_timeout_usec_) > 0 &&
         !tls::is_peer_closed(session_, sock_);
}

bool SSLSocketStream::is_peer_alive() const {
  return !tls::is_peer_closed(session_, sock_);
}

ssize_t SSLSocketStream::read(char *ptr, size_t size) {
  if (tls::pending(session_) > 0) {
    tls::TlsError err;
    auto ret = tls::read(session_, ptr, size, err);
    if (ret == 0 || err.code == tls::ErrorCode::PeerClosed) {
      error_ = Error::ConnectionClosed;
    }
    return ret;
  } else if (wait_readable()) {
    tls::TlsError err;
    auto ret = tls::read(session_, ptr, size, err);
    if (ret < 0) {
      auto n = 1000;
#ifdef _WIN32
      while (--n >= 0 && (err.code == tls::ErrorCode::WantRead ||
                          (err.code == tls::ErrorCode::SyscallError &&
                           WSAGetLastError() == WSAETIMEDOUT))) {
#else
      while (--n >= 0 && err.code == tls::ErrorCode::WantRead) {
#endif
        if (tls::pending(session_) > 0) {
          return tls::read(session_, ptr, size, err);
        } else if (wait_readable()) {
          std::this_thread::sleep_for(std::chrono::microseconds{10});
          ret = tls::read(session_, ptr, size, err);
          if (ret >= 0) { return ret; }
        } else {
          break;
        }
      }
      assert(ret < 0);
    } else if (ret == 0 || err.code == tls::ErrorCode::PeerClosed) {
      error_ = Error::ConnectionClosed;
    }
    return ret;
  } else {
    error_ = Error::Timeout;
    return -1;
  }
}

ssize_t SSLSocketStream::write(const char *ptr, size_t size) {
  if (wait_writable()) {
    auto handle_size =
        std::min<size_t>(size, (std::numeric_limits<int>::max)());

    tls::TlsError err;
    auto ret = tls::write(session_, ptr, handle_size, err);
    if (ret < 0) {
      auto n = 1000;
#ifdef _WIN32
      while (--n >= 0 && (err.code == tls::ErrorCode::WantWrite ||
                          (err.code == tls::ErrorCode::SyscallError &&
                           WSAGetLastError() == WSAETIMEDOUT))) {
#else
      while (--n >= 0 && err.code == tls::ErrorCode::WantWrite) {
#endif
        if (wait_writable()) {
          std::this_thread::sleep_for(std::chrono::microseconds{10});
          ret = tls::write(session_, ptr, handle_size, err);
          if (ret >= 0) { return ret; }
        } else {
          break;
        }
      }
      assert(ret < 0);
    }
    return ret;
  }
  return -1;
}

void SSLSocketStream::get_remote_ip_and_port(std::string &ip,
                                                    int &port) const {
  detail::get_remote_ip_and_port(sock_, ip, port);
}

void SSLSocketStream::get_local_ip_and_port(std::string &ip,
                                                   int &port) const {
  detail::get_local_ip_and_port(sock_, ip, port);
}

socket_t SSLSocketStream::socket() const { return sock_; }

time_t SSLSocketStream::duration() const {
  return std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - start_time_)
      .count();
}

void SSLSocketStream::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

} // namespace detail
#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 4: Server implementation
 */

// HTTP server implementation
Server::Server()
    : new_task_queue([] {
        return new ThreadPool(CPPHTTPLIB_THREAD_POOL_COUNT,
                              CPPHTTPLIB_THREAD_POOL_MAX_COUNT);
      }) {
#ifndef _WIN32
  signal(SIGPIPE, SIG_IGN);
#endif
}

Server::~Server() = default;

std::unique_ptr<detail::MatcherBase>
Server::make_matcher(const std::string &pattern) {
  if (pattern.find("/:") != std::string::npos) {
    return detail::make_unique<detail::PathParamsMatcher>(pattern);
  } else {
    return detail::make_unique<detail::RegexMatcher>(pattern);
  }
}

Server &Server::Get(const std::string &pattern, Handler handler) {
  get_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::Post(const std::string &pattern, Handler handler) {
  post_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::Post(const std::string &pattern,
                            HandlerWithContentReader handler) {
  post_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
                                                 std::move(handler));
  return *this;
}

Server &Server::Put(const std::string &pattern, Handler handler) {
  put_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::Put(const std::string &pattern,
                           HandlerWithContentReader handler) {
  put_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
                                                std::move(handler));
  return *this;
}

Server &Server::Patch(const std::string &pattern, Handler handler) {
  patch_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::Patch(const std::string &pattern,
                             HandlerWithContentReader handler) {
  patch_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
                                                  std::move(handler));
  return *this;
}

Server &Server::Delete(const std::string &pattern, Handler handler) {
  delete_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::Delete(const std::string &pattern,
                              HandlerWithContentReader handler) {
  delete_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
                                                   std::move(handler));
  return *this;
}

Server &Server::Options(const std::string &pattern, Handler handler) {
  options_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
  return *this;
}

Server &Server::WebSocket(const std::string &pattern,
                                 WebSocketHandler handler) {
  websocket_handlers_.push_back(
      {make_matcher(pattern), std::move(handler), nullptr});
  return *this;
}

Server &Server::WebSocket(const std::string &pattern,
                                 WebSocketHandler handler,
                                 SubProtocolSelector sub_protocol_selector) {
  websocket_handlers_.push_back({make_matcher(pattern), std::move(handler),
                                 std::move(sub_protocol_selector)});
  return *this;
}

bool Server::set_base_dir(const std::string &dir,
                                 const std::string &mount_point) {
  return set_mount_point(mount_point, dir);
}

bool Server::set_mount_point(const std::string &mount_point,
                                    const std::string &dir, Headers headers) {
  detail::FileStat stat(dir);
  if (stat.is_dir()) {
    std::string mnt = !mount_point.empty() ? mount_point : "/";
    if (!mnt.empty() && mnt[0] == '/') {
      std::string resolved_base;
      if (detail::canonicalize_path(dir.c_str(), resolved_base)) {
#if defined(_WIN32)
        if (resolved_base.back() != '\\' && resolved_base.back() != '/') {
          resolved_base += '\\';
        }
#else
        if (resolved_base.back() != '/') { resolved_base += '/'; }
#endif
      }
      base_dirs_.push_back(
          {std::move(mnt), dir, std::move(resolved_base), std::move(headers)});
      return true;
    }
  }
  return false;
}

bool Server::remove_mount_point(const std::string &mount_point) {
  for (auto it = base_dirs_.begin(); it != base_dirs_.end(); ++it) {
    if (it->mount_point == mount_point) {
      base_dirs_.erase(it);
      return true;
    }
  }
  return false;
}

Server &
Server::set_file_extension_and_mimetype_mapping(const std::string &ext,
                                                const std::string &mime) {
  file_extension_and_mimetype_map_[ext] = mime;
  return *this;
}

Server &Server::set_default_file_mimetype(const std::string &mime) {
  default_file_mimetype_ = mime;
  return *this;
}

Server &Server::set_file_request_handler(Handler handler) {
  file_request_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_error_handler_core(HandlerWithResponse handler,
                                              std::true_type) {
  error_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_error_handler_core(Handler handler,
                                              std::false_type) {
  error_handler_ = [handler](const Request &req, Response &res) {
    handler(req, res);
    return HandlerResponse::Handled;
  };
  return *this;
}

Server &Server::set_exception_handler(ExceptionHandler handler) {
  exception_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_pre_routing_handler(HandlerWithResponse handler) {
  pre_routing_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_post_routing_handler(Handler handler) {
  post_routing_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_pre_request_handler(HandlerWithResponse handler) {
  pre_request_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_logger(Logger logger) {
  logger_ = std::move(logger);
  return *this;
}

Server &Server::set_error_logger(ErrorLogger error_logger) {
  error_logger_ = std::move(error_logger);
  return *this;
}

Server &Server::set_pre_compression_logger(Logger logger) {
  pre_compression_logger_ = std::move(logger);
  return *this;
}

Server &
Server::set_expect_100_continue_handler(Expect100ContinueHandler handler) {
  expect_100_continue_handler_ = std::move(handler);
  return *this;
}

Server &Server::set_address_family(int family) {
  address_family_ = family;
  return *this;
}

Server &Server::set_tcp_nodelay(bool on) {
  tcp_nodelay_ = on;
  return *this;
}

Server &Server::set_ipv6_v6only(bool on) {
  ipv6_v6only_ = on;
  return *this;
}

Server &Server::set_socket_options(SocketOptions socket_options) {
  socket_options_ = std::move(socket_options);
  return *this;
}

Server &Server::set_default_headers(Headers headers) {
  default_headers_ = std::move(headers);
  return *this;
}

Server &Server::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  header_writer_ = writer;
  return *this;
}

Server &
Server::set_trusted_proxies(const std::vector<std::string> &proxies) {
  trusted_proxies_ = proxies;
  return *this;
}

Server &Server::set_keep_alive_max_count(size_t count) {
  keep_alive_max_count_ = count;
  return *this;
}

Server &Server::set_keep_alive_timeout(time_t sec) {
  keep_alive_timeout_sec_ = sec;
  return *this;
}

Server &Server::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
  return *this;
}

Server &Server::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
  return *this;
}

Server &Server::set_idle_interval(time_t sec, time_t usec) {
  idle_interval_sec_ = sec;
  idle_interval_usec_ = usec;
  return *this;
}

Server &Server::set_payload_max_length(size_t length) {
  payload_max_length_ = length;
  return *this;
}

Server &Server::set_websocket_ping_interval(time_t sec) {
  websocket_ping_interval_sec_ = sec;
  return *this;
}

template <class Rep, class Period>
Server &Server::set_websocket_ping_interval(
    const std::chrono::duration<Rep, Period> &duration) {
  detail::duration_to_sec_and_usec(duration, [&](time_t sec, time_t /*usec*/) {
    set_websocket_ping_interval(sec);
  });
  return *this;
}

bool Server::bind_to_port(const std::string &host, int port,
                                 int socket_flags) {
  auto ret = bind_internal(host, port, socket_flags);
  if (ret == -1) { is_decommissioned = true; }
  return ret >= 0;
}
int Server::bind_to_any_port(const std::string &host, int socket_flags) {
  auto ret = bind_internal(host, 0, socket_flags);
  if (ret == -1) { is_decommissioned = true; }
  return ret;
}

bool Server::listen_after_bind() { return listen_internal(); }

bool Server::listen(const std::string &host, int port,
                           int socket_flags) {
  return bind_to_port(host, port, socket_flags) && listen_internal();
}

bool Server::is_running() const { return is_running_; }

void Server::wait_until_ready() const {
  while (!is_running_ && !is_decommissioned) {
    std::this_thread::sleep_for(std::chrono::milliseconds{1});
  }
}

void Server::stop() {
  if (is_running_) {
    assert(svr_sock_ != INVALID_SOCKET);
    std::atomic<socket_t> sock(svr_sock_.exchange(INVALID_SOCKET));
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
  }
  is_decommissioned = false;
}

void Server::decommission() { is_decommissioned = true; }

bool Server::parse_request_line(const char *s, Request &req) const {
  auto len = strlen(s);
  if (len < 2 || s[len - 2] != '\r' || s[len - 1] != '\n') { return false; }
  len -= 2;

  {
    size_t count = 0;

    detail::split(s, s + len, ' ', [&](const char *b, const char *e) {
      switch (count) {
      case 0: req.method = std::string(b, e); break;
      case 1: req.target = std::string(b, e); break;
      case 2: req.version = std::string(b, e); break;
      default: break;
      }
      count++;
    });

    if (count != 3) { return false; }
  }

  thread_local const std::set<std::string> methods{
      "GET",     "HEAD",    "POST",  "PUT",   "DELETE",
      "CONNECT", "OPTIONS", "TRACE", "PATCH", "PRI"};

  if (methods.find(req.method) == methods.end()) {
    output_error_log(Error::InvalidHTTPMethod, &req);
    return false;
  }

  if (req.version != "HTTP/1.1" && req.version != "HTTP/1.0") {
    output_error_log(Error::InvalidHTTPVersion, &req);
    return false;
  }

  {
    // Skip URL fragment
    for (size_t i = 0; i < req.target.size(); i++) {
      if (req.target[i] == '#') {
        req.target.erase(i);
        break;
      }
    }

    detail::divide(req.target, '?',
                   [&](const char *lhs_data, std::size_t lhs_size,
                       const char *rhs_data, std::size_t rhs_size) {
                     req.path =
                         decode_path_component(std::string(lhs_data, lhs_size));
                     detail::parse_query_text(rhs_data, rhs_size, req.params);
                   });
  }

  return true;
}

bool Server::write_response(Stream &strm, bool close_connection,
                                   Request &req, Response &res) {
  // NOTE: `req.ranges` should be empty, otherwise it will be applied
  // incorrectly to the error content.
  req.ranges.clear();
  return write_response_core(strm, close_connection, req, res, false);
}

bool Server::write_response_with_content(Stream &strm,
                                                bool close_connection,
                                                const Request &req,
                                                Response &res) {
  return write_response_core(strm, close_connection, req, res, true);
}

bool Server::write_response_core(Stream &strm, bool close_connection,
                                        const Request &req, Response &res,
                                        bool need_apply_ranges) {
  assert(res.status != -1);

  if (400 <= res.status && error_handler_ &&
      error_handler_(req, res) == HandlerResponse::Handled) {
    need_apply_ranges = true;
  }

  std::string content_type;
  std::string boundary;
  if (need_apply_ranges) { apply_ranges(req, res, content_type, boundary); }

  // Prepare additional headers
  if (close_connection || req.get_header_value("Connection") == "close" ||
      400 <= res.status) { // Don't leave connections open after errors
    res.set_header("Connection", "close");
  } else {
    std::string s = "timeout=";
    s += std::to_string(keep_alive_timeout_sec_);
    s += ", max=";
    s += std::to_string(keep_alive_max_count_);
    res.set_header("Keep-Alive", s);
  }

  if ((!res.body.empty() || res.content_length_ > 0 || res.content_provider_) &&
      !res.has_header("Content-Type")) {
    res.set_header("Content-Type", "text/plain");
  }

  if (res.body.empty() && !res.content_length_ && !res.content_provider_ &&
      !res.has_header("Content-Length")) {
    res.set_header("Content-Length", "0");
  }

  if (req.method == "HEAD" && !res.has_header("Accept-Ranges")) {
    res.set_header("Accept-Ranges", "bytes");
  }

  if (post_routing_handler_) { post_routing_handler_(req, res); }

  // Response line and headers
  detail::BufferStream bstrm;
  if (!detail::write_response_line(bstrm, res.status)) { return false; }
  if (header_writer_(bstrm, res.headers) <= 0) { return false; }

  // Combine small body with headers to reduce write syscalls
  if (req.method != "HEAD" && !res.body.empty() && !res.content_provider_) {
    bstrm.write(res.body.data(), res.body.size());
  }

  // Log before writing to avoid race condition with client-side code that
  // accesses logger-captured data immediately after receiving the response.
  output_log(req, res);

  // Flush buffer
  auto &data = bstrm.get_buffer();
  if (!detail::write_data(strm, data.data(), data.size())) { return false; }

  // Streaming body
  auto ret = true;
  if (req.method != "HEAD" && res.content_provider_) {
    if (write_content_with_provider(strm, req, res, boundary, content_type)) {
      res.content_provider_success_ = true;
    } else {
      ret = false;
    }
  }

  return ret;
}

bool
Server::write_content_with_provider(Stream &strm, const Request &req,
                                    Response &res, const std::string &boundary,
                                    const std::string &content_type) {
  auto is_shutting_down = [this]() {
    return this->svr_sock_ == INVALID_SOCKET;
  };

  if (res.content_length_ > 0) {
    if (req.ranges.empty()) {
      return detail::write_content(strm, res.content_provider_, 0,
                                   res.content_length_, is_shutting_down);
    } else if (req.ranges.size() == 1) {
      auto offset_and_length = detail::get_range_offset_and_length(
          req.ranges[0], res.content_length_);

      return detail::write_content(strm, res.content_provider_,
                                   offset_and_length.first,
                                   offset_and_length.second, is_shutting_down);
    } else {
      return detail::write_multipart_ranges_data(
          strm, req, res, boundary, content_type, res.content_length_,
          is_shutting_down);
    }
  } else {
    if (res.is_chunked_content_provider_) {
      auto type = detail::encoding_type(req, res);

      std::unique_ptr<detail::compressor> compressor;
      if (type == detail::EncodingType::Gzip) {
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
        compressor = detail::make_unique<detail::gzip_compressor>();
#endif
      } else if (type == detail::EncodingType::Brotli) {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
        compressor = detail::make_unique<detail::brotli_compressor>();
#endif
      } else if (type == detail::EncodingType::Zstd) {
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
        compressor = detail::make_unique<detail::zstd_compressor>();
#endif
      } else {
        compressor = detail::make_unique<detail::nocompressor>();
      }
      assert(compressor != nullptr);

      return detail::write_content_chunked(strm, res.content_provider_,
                                           is_shutting_down, *compressor);
    } else {
      return detail::write_content_without_length(strm, res.content_provider_,
                                                  is_shutting_down);
    }
  }
}

bool Server::read_content(Stream &strm, Request &req, Response &res) {
  FormFields::iterator cur_field;
  FormFiles::iterator cur_file;
  auto is_text_field = false;
  size_t count = 0;
  if (read_content_core(
          strm, req, res,
          // Regular
          [&](const char *buf, size_t n) {
            // Prevent arithmetic overflow when checking sizes.
            // Avoid computing (req.body.size() + n) directly because
            // adding two unsigned `size_t` values can wrap around and
            // produce a small result instead of indicating overflow.
            // Instead, check using subtraction: ensure `n` does not
            // exceed the remaining capacity `max_size() - size()`.
            if (req.body.size() >= req.body.max_size() ||
                n > req.body.max_size() - req.body.size()) {
              return false;
            }

            // Limit decompressed body size to payload_max_length_ to protect
            // against "zip bomb" attacks where a small compressed payload
            // decompresses to a massive size.
            if (payload_max_length_ > 0 &&
                (req.body.size() >= payload_max_length_ ||
                 n > payload_max_length_ - req.body.size())) {
              return false;
            }

            req.body.append(buf, n);
            return true;
          },
          // Multipart FormData
          [&](const FormData &file) {
            if (count++ == CPPHTTPLIB_MULTIPART_FORM_DATA_FILE_MAX_COUNT) {
              output_error_log(Error::TooManyFormDataFiles, &req);
              return false;
            }

            if (file.filename.empty()) {
              cur_field = req.form.fields.emplace(
                  file.name, FormField{file.name, file.content, file.headers});
              is_text_field = true;
            } else {
              cur_file = req.form.files.emplace(file.name, file);
              is_text_field = false;
            }
            return true;
          },
          [&](const char *buf, size_t n) {
            if (is_text_field) {
              auto &content = cur_field->second.content;
              if (content.size() + n > content.max_size()) { return false; }
              content.append(buf, n);
            } else {
              auto &content = cur_file->second.content;
              if (content.size() + n > content.max_size()) { return false; }
              content.append(buf, n);
            }
            return true;
          })) {
    const auto &content_type = req.get_header_value("Content-Type");
    if (detail::extract_media_type(content_type) ==
        "application/x-www-form-urlencoded") {
      if (req.body.size() > CPPHTTPLIB_FORM_URL_ENCODED_PAYLOAD_MAX_LENGTH) {
        res.status = StatusCode::PayloadTooLarge_413; // NOTE: should be 414?
        output_error_log(Error::ExceedMaxPayloadSize, &req);
        return false;
      }
      detail::parse_query_text(req.body, req.params);
    }
    return true;
  }
  return false;
}

bool Server::read_content_with_content_receiver(
    Stream &strm, Request &req, Response &res, ContentReceiver receiver,
    FormDataHeader multipart_header, ContentReceiver multipart_receiver) {
  return read_content_core(strm, req, res, std::move(receiver),
                           std::move(multipart_header),
                           std::move(multipart_receiver));
}

bool Server::read_content_core(
    Stream &strm, Request &req, Response &res, ContentReceiver receiver,
    FormDataHeader multipart_header, ContentReceiver multipart_receiver) const {
  detail::FormDataParser multipart_form_data_parser;
  ContentReceiverWithProgress out;

  if (req.is_multipart_form_data()) {
    const auto &content_type = req.get_header_value("Content-Type");
    std::string boundary;
    if (!detail::parse_multipart_boundary(content_type, boundary)) {
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::MultipartParsing, &req);
      return false;
    }

    multipart_form_data_parser.set_boundary(std::move(boundary));
    out = [&](const char *buf, size_t n, size_t /*off*/, size_t /*len*/) {
      return multipart_form_data_parser.parse(buf, n, multipart_header,
                                              multipart_receiver);
    };
  } else {
    out = [receiver](const char *buf, size_t n, size_t /*off*/,
                     size_t /*len*/) { return receiver(buf, n); };
  }

  // RFC 7230 Section 3.3.3: If this is a request message and none of the above
  // are true (no Transfer-Encoding and no Content-Length), then the message
  // body length is zero (no message body is present).
  //
  // For non-SSL builds, detect clients that send a body without a
  // Content-Length header (raw HTTP over TCP). Check both the stream's
  // internal read buffer (data already read from the socket during header
  // parsing) and the socket itself for pending data. If data is found and
  // exceeds the configured payload limit, reject with 413.
  // For SSL builds we cannot reliably peek the decrypted application bytes,
  // so keep the original behaviour.
#if !defined(CPPHTTPLIB_SSL_ENABLED)
  if (!req.has_header("Content-Length") &&
      !detail::is_chunked_transfer_encoding(req.headers)) {
    // Only check if payload_max_length is set to a finite value
    if (payload_max_length_ > 0 &&
        payload_max_length_ < (std::numeric_limits<size_t>::max)()) {
      // Check if there is data already buffered in the stream (read during
      // header parsing) or pending on the socket. Use a non-blocking socket
      // check to avoid deadlock when the client sends no body.
      bool has_data = strm.is_readable();
      if (!has_data) {
        socket_t s = strm.socket();
        if (s != INVALID_SOCKET) {
          has_data = detail::select_read(s, 0, 0) > 0;
        }
      }
      if (has_data) {
        auto result =
            detail::read_content_without_length(strm, payload_max_length_, out);
        if (result == detail::ReadContentResult::PayloadTooLarge) {
          res.status = StatusCode::PayloadTooLarge_413;
          return false;
        } else if (result != detail::ReadContentResult::Success) {
          return false;
        }
        return true;
      }
    }
    return true;
  }
#else
  if (!req.has_header("Content-Length") &&
      !detail::is_chunked_transfer_encoding(req.headers)) {
    return true;
  }
#endif

  if (!detail::read_content(strm, req, payload_max_length_, res.status, nullptr,
                            out, true)) {
    return false;
  }

  if (req.is_multipart_form_data()) {
    if (!multipart_form_data_parser.is_valid()) {
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::MultipartParsing, &req);
      return false;
    }
  }

  return true;
}

bool Server::handle_file_request(Request &req, Response &res) {
  for (const auto &entry : base_dirs_) {
    // Prefix match
    if (!req.path.compare(0, entry.mount_point.size(), entry.mount_point)) {
      std::string sub_path = "/" + req.path.substr(entry.mount_point.size());
      if (detail::is_valid_path(sub_path)) {
        auto path = entry.base_dir + sub_path;
        if (path.back() == '/') { path += "index.html"; }

        // Defense-in-depth: is_valid_path blocks ".." traversal in the URL,
        // but symlinks/junctions can still escape the base directory.
        if (!entry.resolved_base_dir.empty()) {
          std::string resolved_path;
          if (detail::canonicalize_path(path.c_str(), resolved_path) &&
              !detail::is_path_within_base(resolved_path,
                                           entry.resolved_base_dir)) {
            res.status = StatusCode::Forbidden_403;
            return true;
          }
        }

        detail::FileStat stat(path);

        if (stat.is_dir()) {
          res.set_redirect(sub_path + "/", StatusCode::MovedPermanently_301);
          return true;
        }

        if (stat.is_file()) {
          for (const auto &kv : entry.headers) {
            res.set_header(kv.first, kv.second);
          }

          auto etag = detail::compute_etag(stat);
          if (!etag.empty()) { res.set_header("ETag", etag); }

          auto mtime = stat.mtime();

          auto last_modified = detail::file_mtime_to_http_date(mtime);
          if (!last_modified.empty()) {
            res.set_header("Last-Modified", last_modified);
          }

          if (check_if_not_modified(req, res, etag, mtime)) { return true; }

          check_if_range(req, etag, mtime);

          auto mm = std::make_shared<detail::mmap>(path.c_str());
          if (!mm->is_open()) {
            output_error_log(Error::OpenFile, &req);
            return false;
          }

          res.set_content_provider(
              mm->size(),
              detail::find_content_type(path, file_extension_and_mimetype_map_,
                                        default_file_mimetype_),
              [mm](size_t offset, size_t length, DataSink &sink) -> bool {
                sink.write(mm->data() + offset, length);
                return true;
              });

          if (req.method != "HEAD" && file_request_handler_) {
            file_request_handler_(req, res);
          }

          return true;
        } else {
          output_error_log(Error::OpenFile, &req);
        }
      }
    }
  }
  return false;
}

bool Server::check_if_not_modified(const Request &req, Response &res,
                                          const std::string &etag,
                                          time_t mtime) const {
  // Handle conditional GET:
  // 1. If-None-Match takes precedence (RFC 9110 Section 13.1.2)
  // 2. If-Modified-Since is checked only when If-None-Match is absent
  if (req.has_header("If-None-Match")) {
    if (!etag.empty()) {
      auto val = req.get_header_value("If-None-Match");

      // NOTE: We use exact string matching here. This works correctly
      // because our server always generates weak ETags (W/"..."), and
      // clients typically send back the same ETag they received.
      // RFC 9110 Section 8.8.3.2 allows weak comparison for
      // If-None-Match, where W/"x" and "x" would match, but this
      // simplified implementation requires exact matches.
      auto ret = detail::split_find(val.data(), val.data() + val.size(), ',',
                                    [&](const char *b, const char *e) {
                                      auto seg_len = static_cast<size_t>(e - b);
                                      return (seg_len == 1 && *b == '*') ||
                                             (seg_len == etag.size() &&
                                              std::equal(b, e, etag.begin()));
                                    });

      if (ret) {
        res.status = StatusCode::NotModified_304;
        return true;
      }
    }
  } else if (req.has_header("If-Modified-Since")) {
    auto val = req.get_header_value("If-Modified-Since");
    auto t = detail::parse_http_date(val);

    if (t != static_cast<time_t>(-1) && mtime <= t) {
      res.status = StatusCode::NotModified_304;
      return true;
    }
  }
  return false;
}

bool Server::check_if_range(Request &req, const std::string &etag,
                                   time_t mtime) const {
  // Handle If-Range for partial content requests (RFC 9110
  // Section 13.1.5). If-Range is only evaluated when Range header is
  // present. If the validator matches, serve partial content; otherwise
  // serve full content.
  if (!req.ranges.empty() && req.has_header("If-Range")) {
    auto val = req.get_header_value("If-Range");

    auto is_valid_range = [&]() {
      if (detail::is_strong_etag(val)) {
        // RFC 9110 Section 13.1.5: If-Range requires strong ETag
        // comparison.
        return (!etag.empty() && val == etag);
      } else if (detail::is_weak_etag(val)) {
        // Weak ETags are not valid for If-Range (RFC 9110 Section 13.1.5)
        return false;
      } else {
        // HTTP-date comparison
        auto t = detail::parse_http_date(val);
        return (t != static_cast<time_t>(-1) && mtime <= t);
      }
    };

    if (!is_valid_range()) {
      // Validator doesn't match: ignore Range and serve full content
      req.ranges.clear();
      return false;
    }
  }

  return true;
}

socket_t
Server::create_server_socket(const std::string &host, int port,
                             int socket_flags,
                             SocketOptions socket_options) const {
  return detail::create_socket(
      host, std::string(), port, address_family_, socket_flags, tcp_nodelay_,
      ipv6_v6only_, std::move(socket_options),
      [&](socket_t sock, struct addrinfo &ai, bool & /*quit*/) -> bool {
        if (::bind(sock, ai.ai_addr, static_cast<socklen_t>(ai.ai_addrlen))) {
          output_error_log(Error::BindIPAddress, nullptr);
          return false;
        }
        if (::listen(sock, CPPHTTPLIB_LISTEN_BACKLOG)) {
          output_error_log(Error::Listen, nullptr);
          return false;
        }
        return true;
      });
}

int Server::bind_internal(const std::string &host, int port,
                                 int socket_flags) {
  if (is_decommissioned) { return -1; }

  if (!is_valid()) { return -1; }

  svr_sock_ = create_server_socket(host, port, socket_flags, socket_options_);
  if (svr_sock_ == INVALID_SOCKET) { return -1; }

  if (port == 0) {
    struct sockaddr_storage addr;
    socklen_t addr_len = sizeof(addr);
    if (getsockname(svr_sock_, reinterpret_cast<struct sockaddr *>(&addr),
                    &addr_len) == -1) {
      output_error_log(Error::GetSockName, nullptr);
      return -1;
    }
    if (addr.ss_family == AF_INET) {
      return ntohs(reinterpret_cast<struct sockaddr_in *>(&addr)->sin_port);
    } else if (addr.ss_family == AF_INET6) {
      return ntohs(reinterpret_cast<struct sockaddr_in6 *>(&addr)->sin6_port);
    } else {
      output_error_log(Error::UnsupportedAddressFamily, nullptr);
      return -1;
    }
  } else {
    return port;
  }
}

bool Server::listen_internal() {
  if (is_decommissioned) { return false; }

  auto ret = true;
  is_running_ = true;
  auto se = detail::scope_exit([&]() { is_running_ = false; });

  {
    std::unique_ptr<TaskQueue> task_queue(new_task_queue());

    while (svr_sock_ != INVALID_SOCKET) {
#ifndef _WIN32
      if (idle_interval_sec_ > 0 || idle_interval_usec_ > 0) {
#endif
        auto val = detail::select_read(svr_sock_, idle_interval_sec_,
                                       idle_interval_usec_);
        if (val == 0) { // Timeout
          task_queue->on_idle();
          continue;
        }
#ifndef _WIN32
      }
#endif

#if defined _WIN32
      // sockets connected via WASAccept inherit flags NO_HANDLE_INHERIT,
      // OVERLAPPED
      socket_t sock = WSAAccept(svr_sock_, nullptr, nullptr, nullptr, 0);
#elif defined SOCK_CLOEXEC
      socket_t sock = accept4(svr_sock_, nullptr, nullptr, SOCK_CLOEXEC);
#else
      socket_t sock = accept(svr_sock_, nullptr, nullptr);
#endif

      if (sock == INVALID_SOCKET) {
        if (errno == EMFILE) {
          // The per-process limit of open file descriptors has been reached.
          // Try to accept new connections after a short sleep.
          std::this_thread::sleep_for(std::chrono::microseconds{1});
          continue;
        } else if (errno == EINTR || errno == EAGAIN) {
          continue;
        }
        if (svr_sock_ != INVALID_SOCKET) {
          detail::close_socket(svr_sock_);
          ret = false;
          output_error_log(Error::Connection, nullptr);
        } else {
          ; // The server socket was closed by user.
        }
        break;
      }

      detail::set_socket_opt_time(sock, SOL_SOCKET, SO_RCVTIMEO,
                                  read_timeout_sec_, read_timeout_usec_);
      detail::set_socket_opt_time(sock, SOL_SOCKET, SO_SNDTIMEO,
                                  write_timeout_sec_, write_timeout_usec_);

      if (tcp_nodelay_) {
        detail::set_socket_opt(sock, IPPROTO_TCP, TCP_NODELAY, 1);
      }

      if (!task_queue->enqueue(
              [this, sock]() { process_and_close_socket(sock); })) {
        output_error_log(Error::ResourceExhaustion, nullptr);
        detail::shutdown_socket(sock);
        detail::close_socket(sock);
      }
    }

    task_queue->shutdown();
  }

  is_decommissioned = !ret;
  return ret;
}

bool Server::routing(Request &req, Response &res, Stream &strm) {
  if (pre_routing_handler_ &&
      pre_routing_handler_(req, res) == HandlerResponse::Handled) {
    return true;
  }

  // File handler
  if ((req.method == "GET" || req.method == "HEAD") &&
      handle_file_request(req, res)) {
    return true;
  }

  if (detail::expect_content(req)) {
    // Content reader handler
    {
      // Track whether the ContentReader was aborted due to the decompressed
      // payload exceeding `payload_max_length_`.
      // The user handler runs after the lambda returns, so we must restore the
      // 413 status if the handler overwrites it.
      bool content_reader_payload_too_large = false;

      ContentReader reader(
          [&](ContentReceiver receiver) {
            auto result = read_content_with_content_receiver(
                strm, req, res, std::move(receiver), nullptr, nullptr);
            if (!result) {
              output_error_log(Error::Read, &req);
              if (res.status == StatusCode::PayloadTooLarge_413) {
                content_reader_payload_too_large = true;
              }
            }
            return result;
          },
          [&](FormDataHeader header, ContentReceiver receiver) {
            auto result = read_content_with_content_receiver(
                strm, req, res, nullptr, std::move(header),
                std::move(receiver));
            if (!result) {
              output_error_log(Error::Read, &req);
              if (res.status == StatusCode::PayloadTooLarge_413) {
                content_reader_payload_too_large = true;
              }
            }
            return result;
          });

      bool dispatched = false;
      if (req.method == "POST") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), post_handlers_for_content_reader_);
      } else if (req.method == "PUT") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), put_handlers_for_content_reader_);
      } else if (req.method == "PATCH") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), patch_handlers_for_content_reader_);
      } else if (req.method == "DELETE") {
        dispatched = dispatch_request_for_content_reader(
            req, res, std::move(reader), delete_handlers_for_content_reader_);
      }

      if (dispatched) {
        if (content_reader_payload_too_large) {
          // Enforce the limit: override any status the handler may have set
          // and return false so the error path sends a plain 413 response.
          res.status = StatusCode::PayloadTooLarge_413;
          res.body.clear();
          res.content_length_ = 0;
          res.content_provider_ = nullptr;
          return false;
        }
        return true;
      }
    }

    // Read content into `req.body`
    if (!read_content(strm, req, res)) {
      output_error_log(Error::Read, &req);
      return false;
    }
  }

  // Regular handler
  if (req.method == "GET" || req.method == "HEAD") {
    return dispatch_request(req, res, get_handlers_);
  } else if (req.method == "POST") {
    return dispatch_request(req, res, post_handlers_);
  } else if (req.method == "PUT") {
    return dispatch_request(req, res, put_handlers_);
  } else if (req.method == "DELETE") {
    return dispatch_request(req, res, delete_handlers_);
  } else if (req.method == "OPTIONS") {
    return dispatch_request(req, res, options_handlers_);
  } else if (req.method == "PATCH") {
    return dispatch_request(req, res, patch_handlers_);
  }

  res.status = StatusCode::BadRequest_400;
  return false;
}

bool Server::dispatch_request(Request &req, Response &res,
                                     const Handlers &handlers) const {
  for (const auto &x : handlers) {
    const auto &matcher = x.first;
    const auto &handler = x.second;

    if (matcher->match(req)) {
      req.matched_route = matcher->pattern();
      if (!pre_request_handler_ ||
          pre_request_handler_(req, res) != HandlerResponse::Handled) {
        handler(req, res);
      }
      return true;
    }
  }
  return false;
}

void Server::apply_ranges(const Request &req, Response &res,
                                 std::string &content_type,
                                 std::string &boundary) const {
  if (req.ranges.size() > 1 && res.status == StatusCode::PartialContent_206) {
    auto it = res.headers.find("Content-Type");
    if (it != res.headers.end()) {
      content_type = it->second;
      res.headers.erase(it);
    }

    boundary = detail::make_multipart_data_boundary();

    res.set_header("Content-Type",
                   "multipart/byteranges; boundary=" + boundary);
  }

  auto type = detail::encoding_type(req, res);

  if (res.body.empty()) {
    if (res.content_length_ > 0) {
      size_t length = 0;
      if (req.ranges.empty() || res.status != StatusCode::PartialContent_206) {
        length = res.content_length_;
      } else if (req.ranges.size() == 1) {
        auto offset_and_length = detail::get_range_offset_and_length(
            req.ranges[0], res.content_length_);

        length = offset_and_length.second;

        auto content_range = detail::make_content_range_header_field(
            offset_and_length, res.content_length_);
        res.set_header("Content-Range", content_range);
      } else {
        length = detail::get_multipart_ranges_data_length(
            req, boundary, content_type, res.content_length_);
      }
      res.set_header("Content-Length", std::to_string(length));
    } else {
      if (res.content_provider_) {
        if (res.is_chunked_content_provider_) {
          res.set_header("Transfer-Encoding", "chunked");
          if (type == detail::EncodingType::Gzip) {
            res.set_header("Content-Encoding", "gzip");
            res.set_header("Vary", "Accept-Encoding");
          } else if (type == detail::EncodingType::Brotli) {
            res.set_header("Content-Encoding", "br");
            res.set_header("Vary", "Accept-Encoding");
          } else if (type == detail::EncodingType::Zstd) {
            res.set_header("Content-Encoding", "zstd");
            res.set_header("Vary", "Accept-Encoding");
          }
        }
      }
    }
  } else {
    if (req.ranges.empty() || res.status != StatusCode::PartialContent_206) {
      ;
    } else if (req.ranges.size() == 1) {
      auto offset_and_length =
          detail::get_range_offset_and_length(req.ranges[0], res.body.size());
      auto offset = offset_and_length.first;
      auto length = offset_and_length.second;

      auto content_range = detail::make_content_range_header_field(
          offset_and_length, res.body.size());
      res.set_header("Content-Range", content_range);

      assert(offset + length <= res.body.size());
      res.body = res.body.substr(offset, length);
    } else {
      std::string data;
      detail::make_multipart_ranges_data(req, res, boundary, content_type,
                                         res.body.size(), data);
      res.body.swap(data);
    }

    if (type != detail::EncodingType::None) {
      output_pre_compression_log(req, res);

      std::unique_ptr<detail::compressor> compressor;
      std::string content_encoding;

      if (type == detail::EncodingType::Gzip) {
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
        compressor = detail::make_unique<detail::gzip_compressor>();
        content_encoding = "gzip";
#endif
      } else if (type == detail::EncodingType::Brotli) {
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
        compressor = detail::make_unique<detail::brotli_compressor>();
        content_encoding = "br";
#endif
      } else if (type == detail::EncodingType::Zstd) {
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
        compressor = detail::make_unique<detail::zstd_compressor>();
        content_encoding = "zstd";
#endif
      }

      if (compressor) {
        std::string compressed;
        if (compressor->compress(res.body.data(), res.body.size(), true,
                                 [&](const char *data, size_t data_len) {
                                   compressed.append(data, data_len);
                                   return true;
                                 })) {
          res.body.swap(compressed);
          res.set_header("Content-Encoding", content_encoding);
          res.set_header("Vary", "Accept-Encoding");
        }
      }
    }

    auto length = std::to_string(res.body.size());
    res.set_header("Content-Length", length);
  }
}

bool Server::dispatch_request_for_content_reader(
    Request &req, Response &res, ContentReader content_reader,
    const HandlersForContentReader &handlers) const {
  for (const auto &x : handlers) {
    const auto &matcher = x.first;
    const auto &handler = x.second;

    if (matcher->match(req)) {
      req.matched_route = matcher->pattern();
      if (!pre_request_handler_ ||
          pre_request_handler_(req, res) != HandlerResponse::Handled) {
        handler(req, res, content_reader);
      }
      return true;
    }
  }
  return false;
}

std::string
get_client_ip(const std::string &x_forwarded_for,
              const std::vector<std::string> &trusted_proxies) {
  // X-Forwarded-For is a comma-separated list per RFC 7239
  std::vector<std::string> ip_list;
  detail::split(x_forwarded_for.data(),
                x_forwarded_for.data() + x_forwarded_for.size(), ',',
                [&](const char *b, const char *e) {
                  auto r = detail::trim(b, e, 0, static_cast<size_t>(e - b));
                  ip_list.emplace_back(std::string(b + r.first, b + r.second));
                });

  for (size_t i = 0; i < ip_list.size(); ++i) {
    auto ip = ip_list[i];

    auto is_trusted_proxy =
        std::any_of(trusted_proxies.begin(), trusted_proxies.end(),
                    [&](const std::string &proxy) { return ip == proxy; });

    if (is_trusted_proxy) {
      if (i == 0) {
        // If the trusted proxy is the first IP, there's no preceding client IP
        return ip;
      } else {
        // Return the IP immediately before the trusted proxy
        return ip_list[i - 1];
      }
    }
  }

  // If no trusted proxy is found, return the first IP in the list
  return ip_list.front();
}

bool
Server::process_request(Stream &strm, const std::string &remote_addr,
                        int remote_port, const std::string &local_addr,
                        int local_port, bool close_connection,
                        bool &connection_closed,
                        const std::function<void(Request &)> &setup_request,
                        bool *websocket_upgraded) {
  std::array<char, 2048> buf{};

  detail::stream_line_reader line_reader(strm, buf.data(), buf.size());

  // Connection has been closed on client
  if (!line_reader.getline()) { return false; }

  Request req;
  req.start_time_ = std::chrono::steady_clock::now();
  req.remote_addr = remote_addr;
  req.remote_port = remote_port;
  req.local_addr = local_addr;
  req.local_port = local_port;

  Response res;
  res.version = "HTTP/1.1";
  res.headers = default_headers_;

  // Request line and headers
  if (!parse_request_line(line_reader.ptr(), req)) {
    res.status = StatusCode::BadRequest_400;
    output_error_log(Error::InvalidRequestLine, &req);
    return write_response(strm, close_connection, req, res);
  }

  // Request headers
  if (!detail::read_headers(strm, req.headers)) {
    res.status = StatusCode::BadRequest_400;
    output_error_log(Error::InvalidHeaders, &req);
    return write_response(strm, close_connection, req, res);
  }

  // Check if the request URI doesn't exceed the limit
  if (req.target.size() > CPPHTTPLIB_REQUEST_URI_MAX_LENGTH) {
    res.status = StatusCode::UriTooLong_414;
    output_error_log(Error::ExceedUriMaxLength, &req);
    return write_response(strm, close_connection, req, res);
  }

  if (req.get_header_value("Connection") == "close") {
    connection_closed = true;
  }

  if (req.version == "HTTP/1.0" &&
      req.get_header_value("Connection") != "Keep-Alive") {
    connection_closed = true;
  }

  if (!trusted_proxies_.empty() && req.has_header("X-Forwarded-For")) {
    auto x_forwarded_for = req.get_header_value("X-Forwarded-For");
    req.remote_addr = get_client_ip(x_forwarded_for, trusted_proxies_);
  } else {
    req.remote_addr = remote_addr;
  }
  req.remote_port = remote_port;

  req.local_addr = local_addr;
  req.local_port = local_port;

  if (req.has_header("Accept")) {
    const auto &accept_header = req.get_header_value("Accept");
    if (!detail::parse_accept_header(accept_header, req.accept_content_types)) {
      res.status = StatusCode::BadRequest_400;
      output_error_log(Error::HTTPParsing, &req);
      return write_response(strm, close_connection, req, res);
    }
  }

  if (req.has_header("Range")) {
    const auto &range_header_value = req.get_header_value("Range");
    if (!detail::parse_range_header(range_header_value, req.ranges)) {
      res.status = StatusCode::RangeNotSatisfiable_416;
      output_error_log(Error::InvalidRangeHeader, &req);
      return write_response(strm, close_connection, req, res);
    }
  }

  if (setup_request) { setup_request(req); }

  if (req.get_header_value("Expect") == "100-continue") {
    int status = StatusCode::Continue_100;
    if (expect_100_continue_handler_) {
      status = expect_100_continue_handler_(req, res);
    }
    switch (status) {
    case StatusCode::Continue_100:
    case StatusCode::ExpectationFailed_417:
      detail::write_response_line(strm, status);
      strm.write("\r\n");
      break;
    default:
      connection_closed = true;
      return write_response(strm, true, req, res);
    }
  }

  // Setup `is_connection_closed` method
  auto sock = strm.socket();
  req.is_connection_closed = [sock]() {
    return !detail::is_socket_alive(sock);
  };

  // WebSocket upgrade
  // Check pre_routing_handler_ before upgrading so that authentication
  // and other middleware can reject the request with an HTTP response
  // (e.g., 401) before the protocol switches.
  if (detail::is_websocket_upgrade(req)) {
    if (pre_routing_handler_ &&
        pre_routing_handler_(req, res) == HandlerResponse::Handled) {
      if (res.status == -1) { res.status = StatusCode::OK_200; }
      return write_response(strm, close_connection, req, res);
    }
    // Find matching WebSocket handler
    for (const auto &entry : websocket_handlers_) {
      if (entry.matcher->match(req)) {
        // Compute accept key
        auto client_key = req.get_header_value("Sec-WebSocket-Key");
        auto accept_key = detail::websocket_accept_key(client_key);

        // Negotiate subprotocol
        std::string selected_subprotocol;
        if (entry.sub_protocol_selector) {
          auto protocol_header = req.get_header_value("Sec-WebSocket-Protocol");
          if (!protocol_header.empty()) {
            std::vector<std::string> protocols;
            std::istringstream iss(protocol_header);
            std::string token;
            while (std::getline(iss, token, ',')) {
              // Trim whitespace
              auto start = token.find_first_not_of(' ');
              auto end = token.find_last_not_of(' ');
              if (start != std::string::npos) {
                protocols.push_back(token.substr(start, end - start + 1));
              }
            }
            selected_subprotocol = entry.sub_protocol_selector(protocols);
          }
        }

        // Send 101 Switching Protocols
        std::string handshake_response = "HTTP/1.1 101 Switching Protocols\r\n"
                                         "Upgrade: websocket\r\n"
                                         "Connection: Upgrade\r\n"
                                         "Sec-WebSocket-Accept: " +
                                         accept_key + "\r\n";
        if (!selected_subprotocol.empty()) {
          if (!detail::fields::is_field_value(selected_subprotocol)) {
            return false;
          }
          handshake_response +=
              "Sec-WebSocket-Protocol: " + selected_subprotocol + "\r\n";
        }
        handshake_response += "\r\n";
        if (strm.write(handshake_response.data(), handshake_response.size()) <
            0) {
          return false;
        }

        connection_closed = true;
        if (websocket_upgraded) { *websocket_upgraded = true; }

        {
          // Use WebSocket-specific read timeout instead of HTTP timeout
          strm.set_read_timeout(CPPHTTPLIB_WEBSOCKET_READ_TIMEOUT_SECOND, 0);
          ws::WebSocket ws(strm, req, true, websocket_ping_interval_sec_);
          entry.handler(req, ws);
        }
        return true;
      }
    }
    // No matching handler - fall through to 404
  }

  // Routing
  auto routed = false;
#ifdef CPPHTTPLIB_NO_EXCEPTIONS
  routed = routing(req, res, strm);
#else
  try {
    routed = routing(req, res, strm);
  } catch (std::exception &) {
    if (exception_handler_) {
      auto ep = std::current_exception();
      exception_handler_(req, res, ep);
      routed = true;
    } else {
      res.status = StatusCode::InternalServerError_500;
    }
  } catch (...) {
    if (exception_handler_) {
      auto ep = std::current_exception();
      exception_handler_(req, res, ep);
      routed = true;
    } else {
      res.status = StatusCode::InternalServerError_500;
    }
  }
#endif
  if (routed) {
    if (res.status == -1) {
      res.status = req.ranges.empty() ? StatusCode::OK_200
                                      : StatusCode::PartialContent_206;
    }

    // Serve file content by using a content provider
    if (!res.file_content_path_.empty()) {
      const auto &path = res.file_content_path_;
      auto mm = std::make_shared<detail::mmap>(path.c_str());
      if (!mm->is_open()) {
        res.body.clear();
        res.content_length_ = 0;
        res.content_provider_ = nullptr;
        res.status = StatusCode::NotFound_404;
        output_error_log(Error::OpenFile, &req);
        return write_response(strm, close_connection, req, res);
      }

      auto content_type = res.file_content_content_type_;
      if (content_type.empty()) {
        content_type = detail::find_content_type(
            path, file_extension_and_mimetype_map_, default_file_mimetype_);
      }

      res.set_content_provider(
          mm->size(), content_type,
          [mm](size_t offset, size_t length, DataSink &sink) -> bool {
            sink.write(mm->data() + offset, length);
            return true;
          });
    }

    if (detail::range_error(req, res)) {
      res.body.clear();
      res.content_length_ = 0;
      res.content_provider_ = nullptr;
      res.status = StatusCode::RangeNotSatisfiable_416;
      return write_response(strm, close_connection, req, res);
    }

    return write_response_with_content(strm, close_connection, req, res);
  } else {
    if (res.status == -1) { res.status = StatusCode::NotFound_404; }

    return write_response(strm, close_connection, req, res);
  }
}

bool Server::is_valid() const { return true; }

bool Server::process_and_close_socket(socket_t sock) {
  std::string remote_addr;
  int remote_port = 0;
  detail::get_remote_ip_and_port(sock, remote_addr, remote_port);

  std::string local_addr;
  int local_port = 0;
  detail::get_local_ip_and_port(sock, local_addr, local_port);

  bool websocket_upgraded = false;
  auto ret = detail::process_server_socket(
      svr_sock_, sock, keep_alive_max_count_, keep_alive_timeout_sec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_,
      [&](Stream &strm, bool close_connection, bool &connection_closed) {
        return process_request(strm, remote_addr, remote_port, local_addr,
                               local_port, close_connection, connection_closed,
                               nullptr, &websocket_upgraded);
      });

  detail::shutdown_socket(sock);
  detail::close_socket(sock);
  return ret;
}

void Server::output_log(const Request &req, const Response &res) const {
  if (logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    logger_(req, res);
  }
}

void Server::output_pre_compression_log(const Request &req,
                                               const Response &res) const {
  if (pre_compression_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    pre_compression_logger_(req, res);
  }
}

void Server::output_error_log(const Error &err,
                                     const Request *req) const {
  if (error_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    error_logger_(err, req);
  }
}

/*
 * Group 5: ClientImpl and Client (Universal) implementation
 */
// HTTP client implementation
ClientImpl::ClientImpl(const std::string &host)
    : ClientImpl(host, 80, std::string(), std::string()) {}

ClientImpl::ClientImpl(const std::string &host, int port)
    : ClientImpl(host, port, std::string(), std::string()) {}

ClientImpl::ClientImpl(const std::string &host, int port,
                              const std::string &client_cert_path,
                              const std::string &client_key_path)
    : host_(detail::escape_abstract_namespace_unix_domain(host)), port_(port),
      client_cert_path_(client_cert_path), client_key_path_(client_key_path) {}

ClientImpl::~ClientImpl() {
  // Wait until all the requests in flight are handled.
  size_t retry_count = 10;
  while (retry_count-- > 0) {
    {
      std::lock_guard<std::mutex> guard(socket_mutex_);
      if (socket_requests_in_flight_ == 0) { break; }
    }
    std::this_thread::sleep_for(std::chrono::milliseconds{1});
  }

  std::lock_guard<std::mutex> guard(socket_mutex_);
  shutdown_socket(socket_);
  close_socket(socket_);
}

bool ClientImpl::is_valid() const { return true; }

void ClientImpl::copy_settings(const ClientImpl &rhs) {
  client_cert_path_ = rhs.client_cert_path_;
  client_key_path_ = rhs.client_key_path_;
  connection_timeout_sec_ = rhs.connection_timeout_sec_;
  read_timeout_sec_ = rhs.read_timeout_sec_;
  read_timeout_usec_ = rhs.read_timeout_usec_;
  write_timeout_sec_ = rhs.write_timeout_sec_;
  write_timeout_usec_ = rhs.write_timeout_usec_;
  max_timeout_msec_ = rhs.max_timeout_msec_;
  basic_auth_username_ = rhs.basic_auth_username_;
  basic_auth_password_ = rhs.basic_auth_password_;
  bearer_token_auth_token_ = rhs.bearer_token_auth_token_;
  keep_alive_ = rhs.keep_alive_;
  follow_location_ = rhs.follow_location_;
  path_encode_ = rhs.path_encode_;
  address_family_ = rhs.address_family_;
  tcp_nodelay_ = rhs.tcp_nodelay_;
  ipv6_v6only_ = rhs.ipv6_v6only_;
  socket_options_ = rhs.socket_options_;
  compress_ = rhs.compress_;
  decompress_ = rhs.decompress_;
  payload_max_length_ = rhs.payload_max_length_;
  has_payload_max_length_ = rhs.has_payload_max_length_;
  interface_ = rhs.interface_;
  proxy_host_ = rhs.proxy_host_;
  proxy_port_ = rhs.proxy_port_;
  proxy_basic_auth_username_ = rhs.proxy_basic_auth_username_;
  proxy_basic_auth_password_ = rhs.proxy_basic_auth_password_;
  proxy_bearer_token_auth_token_ = rhs.proxy_bearer_token_auth_token_;
  logger_ = rhs.logger_;
  error_logger_ = rhs.error_logger_;

#ifdef CPPHTTPLIB_SSL_ENABLED
  digest_auth_username_ = rhs.digest_auth_username_;
  digest_auth_password_ = rhs.digest_auth_password_;
  proxy_digest_auth_username_ = rhs.proxy_digest_auth_username_;
  proxy_digest_auth_password_ = rhs.proxy_digest_auth_password_;
  ca_cert_file_path_ = rhs.ca_cert_file_path_;
  ca_cert_dir_path_ = rhs.ca_cert_dir_path_;
  server_certificate_verification_ = rhs.server_certificate_verification_;
  server_hostname_verification_ = rhs.server_hostname_verification_;
#endif
}

socket_t ClientImpl::create_client_socket(Error &error) const {
  if (!proxy_host_.empty() && proxy_port_ != -1) {
    return detail::create_client_socket(
        proxy_host_, std::string(), proxy_port_, address_family_, tcp_nodelay_,
        ipv6_v6only_, socket_options_, connection_timeout_sec_,
        connection_timeout_usec_, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_, interface_, error);
  }

  // Check is custom IP specified for host_
  std::string ip;
  auto it = addr_map_.find(host_);
  if (it != addr_map_.end()) { ip = it->second; }

  return detail::create_client_socket(
      host_, ip, port_, address_family_, tcp_nodelay_, ipv6_v6only_,
      socket_options_, connection_timeout_sec_, connection_timeout_usec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, interface_, error);
}

bool ClientImpl::create_and_connect_socket(Socket &socket,
                                                  Error &error) {
  auto sock = create_client_socket(error);
  if (sock == INVALID_SOCKET) { return false; }
  socket.sock = sock;
  return true;
}

bool ClientImpl::ensure_socket_connection(Socket &socket, Error &error) {
  return create_and_connect_socket(socket, error);
}

bool ClientImpl::setup_proxy_connection(
    Socket & /*socket*/,
    std::chrono::time_point<std::chrono::steady_clock> /*start_time*/,
    Response & /*res*/, bool & /*success*/, Error & /*error*/) {
  return true;
}

void ClientImpl::shutdown_ssl(Socket & /*socket*/,
                                     bool /*shutdown_gracefully*/) {
  // If there are any requests in flight from threads other than us, then it's
  // a thread-unsafe race because individual ssl* objects are not thread-safe.
  assert(socket_requests_in_flight_ == 0 ||
         socket_requests_are_from_thread_ == std::this_thread::get_id());
}

void ClientImpl::shutdown_socket(Socket &socket) const {
  if (socket.sock == INVALID_SOCKET) { return; }
  detail::shutdown_socket(socket.sock);
}

void ClientImpl::close_socket(Socket &socket) {
  // If there are requests in flight in another thread, usually closing
  // the socket will be fine and they will simply receive an error when
  // using the closed socket, but it is still a bug since rarely the OS
  // may reassign the socket id to be used for a new socket, and then
  // suddenly they will be operating on a live socket that is different
  // than the one they intended!
  assert(socket_requests_in_flight_ == 0 ||
         socket_requests_are_from_thread_ == std::this_thread::get_id());

  // It is also a bug if this happens while SSL is still active
#ifdef CPPHTTPLIB_SSL_ENABLED
  assert(socket.ssl == nullptr);
#endif

  if (socket.sock == INVALID_SOCKET) { return; }
  detail::close_socket(socket.sock);
  socket.sock = INVALID_SOCKET;
}

bool ClientImpl::read_response_line(Stream &strm, const Request &req,
                                           Response &res,
                                           bool skip_100_continue) const {
  std::array<char, 2048> buf{};

  detail::stream_line_reader line_reader(strm, buf.data(), buf.size());

  if (!line_reader.getline()) { return false; }

#ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
  thread_local const std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r?\n");
#else
  thread_local const std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r\n");
#endif

  std::cmatch m;
  if (!std::regex_match(line_reader.ptr(), m, re)) {
    return req.method == "CONNECT";
  }
  res.version = std::string(m[1]);
  res.status = std::stoi(std::string(m[2]));
  res.reason = std::string(m[3]);

  // Ignore '100 Continue' (only when not using Expect: 100-continue explicitly)
  while (skip_100_continue && res.status == StatusCode::Continue_100) {
    if (!line_reader.getline()) { return false; } // CRLF
    if (!line_reader.getline()) { return false; } // next response line

    if (!std::regex_match(line_reader.ptr(), m, re)) { return false; }
    res.version = std::string(m[1]);
    res.status = std::stoi(std::string(m[2]));
    res.reason = std::string(m[3]);
  }

  return true;
}

bool ClientImpl::send(Request &req, Response &res, Error &error) {
  std::lock_guard<std::recursive_mutex> request_mutex_guard(request_mutex_);
  auto ret = send_(req, res, error);
  if (error == Error::SSLPeerCouldBeClosed_) {
    assert(!ret);
    ret = send_(req, res, error);
    // If still failing with SSLPeerCouldBeClosed_, convert to Read error
    if (error == Error::SSLPeerCouldBeClosed_) { error = Error::Read; }
  }
  return ret;
}

bool ClientImpl::send_(Request &req, Response &res, Error &error) {
  {
    std::lock_guard<std::mutex> guard(socket_mutex_);

    // Set this to false immediately - if it ever gets set to true by the end
    // of the request, we know another thread instructed us to close the
    // socket.
    socket_should_be_closed_when_request_is_done_ = false;

    auto is_alive = false;
    if (socket_.is_open()) {
      is_alive = detail::is_socket_alive(socket_.sock);

#ifdef CPPHTTPLIB_SSL_ENABLED
      if (is_alive && is_ssl()) {
        if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
          is_alive = false;
        }
      }
#endif

      if (!is_alive) {
        // Attempt to avoid sigpipe by shutting down non-gracefully if it
        // seems like the other side has already closed the connection Also,
        // there cannot be any requests in flight from other threads since we
        // locked request_mutex_, so safe to close everything immediately
        const bool shutdown_gracefully = false;
        shutdown_ssl(socket_, shutdown_gracefully);
        shutdown_socket(socket_);
        close_socket(socket_);
      }
    }

    if (!is_alive) {
      if (!ensure_socket_connection(socket_, error)) {
        output_error_log(error, &req);
        return false;
      }

      {
        auto success = true;
        if (!setup_proxy_connection(socket_, req.start_time_, res, success,
                                    error)) {
          if (!success) { output_error_log(error, &req); }
          return success;
        }
      }
    }

    // Mark the current socket as being in use so that it cannot be closed by
    // anyone else while this request is ongoing, even though we will be
    // releasing the mutex.
    if (socket_requests_in_flight_ > 1) {
      assert(socket_requests_are_from_thread_ == std::this_thread::get_id());
    }
    socket_requests_in_flight_ += 1;
    socket_requests_are_from_thread_ = std::this_thread::get_id();
  }

  for (const auto &header : default_headers_) {
    if (req.headers.find(header.first) == req.headers.end()) {
      req.headers.insert(header);
    }
  }

  auto ret = false;
  auto close_connection = !keep_alive_;

  auto se = detail::scope_exit([&]() {
    // Briefly lock mutex in order to mark that a request is no longer ongoing
    std::lock_guard<std::mutex> guard(socket_mutex_);
    socket_requests_in_flight_ -= 1;
    if (socket_requests_in_flight_ <= 0) {
      assert(socket_requests_in_flight_ == 0);
      socket_requests_are_from_thread_ = std::thread::id();
    }

    if (socket_should_be_closed_when_request_is_done_ || close_connection ||
        !ret) {
      shutdown_ssl(socket_, true);
      shutdown_socket(socket_);
      close_socket(socket_);
    }
  });

  ret = process_socket(socket_, req.start_time_, [&](Stream &strm) {
    return handle_request(strm, req, res, close_connection, error);
  });

  if (!ret) {
    if (error == Error::Success) {
      error = Error::Unknown;
      output_error_log(error, &req);
    }
  }

  return ret;
}

Result ClientImpl::send(const Request &req) {
  auto req2 = req;
  return send_(std::move(req2));
}

Result ClientImpl::send_(Request &&req) {
  auto res = detail::make_unique<Response>();
  auto error = Error::Success;
  auto ret = send(req, *res, error);
#ifdef CPPHTTPLIB_SSL_ENABLED
  return Result{ret ? std::move(res) : nullptr, error, std::move(req.headers),
                last_ssl_error_, last_backend_error_};
#else
  return Result{ret ? std::move(res) : nullptr, error, std::move(req.headers)};
#endif
}

void ClientImpl::prepare_default_headers(Request &r, bool for_stream,
                                                const std::string &ct) {
  (void)for_stream;
  for (const auto &header : default_headers_) {
    if (!r.has_header(header.first)) { r.headers.insert(header); }
  }

  if (!r.has_header("Host")) {
    if (address_family_ == AF_UNIX) {
      r.headers.emplace("Host", "localhost");
    } else {
      r.headers.emplace(
          "Host", detail::make_host_and_port_string(host_, port_, is_ssl()));
    }
  }

  if (!r.has_header("Accept")) { r.headers.emplace("Accept", "*/*"); }

  if (!r.content_receiver) {
    if (!r.has_header("Accept-Encoding")) {
      std::string accept_encoding;
#ifdef CPPHTTPLIB_BROTLI_SUPPORT
      accept_encoding = "br";
#endif
#ifdef CPPHTTPLIB_ZLIB_SUPPORT
      if (!accept_encoding.empty()) { accept_encoding += ", "; }
      accept_encoding += "gzip, deflate";
#endif
#ifdef CPPHTTPLIB_ZSTD_SUPPORT
      if (!accept_encoding.empty()) { accept_encoding += ", "; }
      accept_encoding += "zstd";
#endif
      r.set_header("Accept-Encoding", accept_encoding);
    }

#ifndef CPPHTTPLIB_NO_DEFAULT_USER_AGENT
    if (!r.has_header("User-Agent")) {
      auto agent = std::string("cpp-httplib/") + CPPHTTPLIB_VERSION;
      r.set_header("User-Agent", agent);
    }
#endif
  }

  if (!r.body.empty()) {
    if (!ct.empty() && !r.has_header("Content-Type")) {
      r.headers.emplace("Content-Type", ct);
    }
    if (!r.has_header("Content-Length")) {
      r.headers.emplace("Content-Length", std::to_string(r.body.size()));
    }
  }
}

ClientImpl::StreamHandle
ClientImpl::open_stream(const std::string &method, const std::string &path,
                        const Params &params, const Headers &headers,
                        const std::string &body,
                        const std::string &content_type) {
  StreamHandle handle;
  handle.response = detail::make_unique<Response>();
  handle.error = Error::Success;

  auto query_path = params.empty() ? path : append_query_params(path, params);
  handle.connection_ = detail::make_unique<ClientConnection>();

  {
    std::lock_guard<std::mutex> guard(socket_mutex_);

    auto is_alive = false;
    if (socket_.is_open()) {
      is_alive = detail::is_socket_alive(socket_.sock);
#ifdef CPPHTTPLIB_SSL_ENABLED
      if (is_alive && is_ssl()) {
        if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
          is_alive = false;
        }
      }
#endif
      if (!is_alive) {
        shutdown_ssl(socket_, false);
        shutdown_socket(socket_);
        close_socket(socket_);
      }
    }

    if (!is_alive) {
      if (!ensure_socket_connection(socket_, handle.error)) {
        handle.response.reset();
        return handle;
      }

      {
        auto success = true;
        auto start_time = std::chrono::steady_clock::now();
        if (!setup_proxy_connection(socket_, start_time, *handle.response,
                                    success, handle.error)) {
          if (!success) { handle.response.reset(); }
          return handle;
        }
      }
    }

    transfer_socket_ownership_to_handle(handle);
  }

#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl() && handle.connection_->session) {
    handle.socket_stream_ = detail::make_unique<detail::SSLSocketStream>(
        handle.connection_->sock, handle.connection_->session,
        read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
        write_timeout_usec_);
  } else {
    handle.socket_stream_ = detail::make_unique<detail::SocketStream>(
        handle.connection_->sock, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_);
  }
#else
  handle.socket_stream_ = detail::make_unique<detail::SocketStream>(
      handle.connection_->sock, read_timeout_sec_, read_timeout_usec_,
      write_timeout_sec_, write_timeout_usec_);
#endif
  handle.stream_ = handle.socket_stream_.get();

  Request req;
  req.method = method;
  req.path = query_path;
  req.headers = headers;
  req.body = body;

  prepare_default_headers(req, true, content_type);

  auto &strm = *handle.stream_;
  if (detail::write_request_line(strm, req.method, req.path) < 0) {
    handle.error = Error::Write;
    handle.response.reset();
    return handle;
  }

  if (!detail::check_and_write_headers(strm, req.headers, header_writer_,
                                       handle.error)) {
    handle.response.reset();
    return handle;
  }

  if (!body.empty()) {
    if (strm.write(body.data(), body.size()) < 0) {
      handle.error = Error::Write;
      handle.response.reset();
      return handle;
    }
  }

  if (!read_response_line(strm, req, *handle.response) ||
      !detail::read_headers(strm, handle.response->headers)) {
    handle.error = Error::Read;
    handle.response.reset();
    return handle;
  }

  handle.body_reader_.stream = handle.stream_;
  handle.body_reader_.payload_max_length = payload_max_length_;

  if (handle.response->has_header("Content-Length")) {
    bool is_invalid = false;
    auto content_length = detail::get_header_value_u64(
        handle.response->headers, "Content-Length", 0, 0, is_invalid);
    if (is_invalid) {
      handle.error = Error::Read;
      handle.response.reset();
      return handle;
    }
    handle.body_reader_.has_content_length = true;
    handle.body_reader_.content_length = content_length;
  }

  auto transfer_encoding =
      handle.response->get_header_value("Transfer-Encoding");
  handle.body_reader_.chunked = (transfer_encoding == "chunked");

  auto content_encoding = handle.response->get_header_value("Content-Encoding");
  if (!content_encoding.empty()) {
    handle.decompressor_ = detail::create_decompressor(content_encoding);
  }

  return handle;
}

ssize_t ClientImpl::StreamHandle::read(char *buf, size_t len) {
  if (!is_valid() || !response) { return -1; }

  if (decompressor_) { return read_with_decompression(buf, len); }
  auto n = detail::read_body_content(stream_, body_reader_, buf, len);

  if (n <= 0 && body_reader_.chunked && !trailers_parsed_ && stream_) {
    trailers_parsed_ = true;
    if (body_reader_.chunked_decoder) {
      if (!body_reader_.chunked_decoder->parse_trailers_into(
              response->trailers, response->headers)) {
        return n;
      }
    } else {
      detail::ChunkedDecoder dec(*stream_);
      if (!dec.parse_trailers_into(response->trailers, response->headers)) {
        return n;
      }
    }
  }

  return n;
}

ssize_t ClientImpl::StreamHandle::read_with_decompression(char *buf,
                                                                 size_t len) {
  if (decompress_offset_ < decompress_buffer_.size()) {
    auto available = decompress_buffer_.size() - decompress_offset_;
    auto to_copy = (std::min)(len, available);
    std::memcpy(buf, decompress_buffer_.data() + decompress_offset_, to_copy);
    decompress_offset_ += to_copy;
    decompressed_bytes_read_ += to_copy;
    return static_cast<ssize_t>(to_copy);
  }

  decompress_buffer_.clear();
  decompress_offset_ = 0;

  constexpr size_t kDecompressionBufferSize = 8192;
  char compressed_buf[kDecompressionBufferSize];

  while (true) {
    auto n = detail::read_body_content(stream_, body_reader_, compressed_buf,
                                       sizeof(compressed_buf));

    if (n <= 0) { return n; }

    bool decompress_ok = decompressor_->decompress(
        compressed_buf, static_cast<size_t>(n),
        [this](const char *data, size_t data_len) {
          decompress_buffer_.append(data, data_len);
          auto limit = body_reader_.payload_max_length;
          if (decompressed_bytes_read_ + decompress_buffer_.size() > limit) {
            return false;
          }
          return true;
        });

    if (!decompress_ok) {
      body_reader_.last_error = Error::Read;
      return -1;
    }

    if (!decompress_buffer_.empty()) { break; }
  }

  auto to_copy = (std::min)(len, decompress_buffer_.size());
  std::memcpy(buf, decompress_buffer_.data(), to_copy);
  decompress_offset_ = to_copy;
  decompressed_bytes_read_ += to_copy;
  return static_cast<ssize_t>(to_copy);
}

void ClientImpl::StreamHandle::parse_trailers_if_needed() {
  if (!response || !stream_ || !body_reader_.chunked || trailers_parsed_) {
    return;
  }

  trailers_parsed_ = true;

  const auto bufsiz = 128;
  char line_buf[bufsiz];
  detail::stream_line_reader line_reader(*stream_, line_buf, bufsiz);

  if (!line_reader.getline()) { return; }

  if (!detail::parse_trailers(line_reader, response->trailers,
                              response->headers)) {
    return;
  }
}

namespace detail {

ChunkedDecoder::ChunkedDecoder(Stream &s) : strm(s) {}

ssize_t ChunkedDecoder::read_payload(char *buf, size_t len,
                                            size_t &out_chunk_offset,
                                            size_t &out_chunk_total) {
  if (finished) { return 0; }

  if (chunk_remaining == 0) {
    stream_line_reader lr(strm, line_buf, sizeof(line_buf));
    if (!lr.getline()) { return -1; }

    char *endptr = nullptr;
    unsigned long chunk_len = std::strtoul(lr.ptr(), &endptr, 16);
    if (endptr == lr.ptr()) { return -1; }
    if (chunk_len == ULONG_MAX) { return -1; }

    if (chunk_len == 0) {
      chunk_remaining = 0;
      finished = true;
      out_chunk_offset = 0;
      out_chunk_total = 0;
      return 0;
    }

    chunk_remaining = static_cast<size_t>(chunk_len);
    last_chunk_total = chunk_remaining;
    last_chunk_offset = 0;
  }

  auto to_read = (std::min)(chunk_remaining, len);
  auto n = strm.read(buf, to_read);
  if (n <= 0) { return -1; }

  auto offset_before = last_chunk_offset;
  last_chunk_offset += static_cast<size_t>(n);
  chunk_remaining -= static_cast<size_t>(n);

  out_chunk_offset = offset_before;
  out_chunk_total = last_chunk_total;

  if (chunk_remaining == 0) {
    stream_line_reader lr(strm, line_buf, sizeof(line_buf));
    if (!lr.getline()) { return -1; }
    if (std::strcmp(lr.ptr(), "\r\n") != 0) { return -1; }
  }

  return n;
}

bool ChunkedDecoder::parse_trailers_into(Headers &dest,
                                                const Headers &src_headers) {
  stream_line_reader lr(strm, line_buf, sizeof(line_buf));
  if (!lr.getline()) { return false; }
  return parse_trailers(lr, dest, src_headers);
}

} // namespace detail

void
ClientImpl::transfer_socket_ownership_to_handle(StreamHandle &handle) {
  handle.connection_->sock = socket_.sock;
#ifdef CPPHTTPLIB_SSL_ENABLED
  handle.connection_->session = socket_.ssl;
  socket_.ssl = nullptr;
#endif
  socket_.sock = INVALID_SOCKET;
}

bool ClientImpl::handle_request(Stream &strm, Request &req,
                                       Response &res, bool close_connection,
                                       Error &error) {
  if (req.path.empty()) {
    error = Error::Connection;
    output_error_log(error, &req);
    return false;
  }

  auto req_save = req;

  bool ret;

  if (!is_ssl() && !proxy_host_.empty() && proxy_port_ != -1) {
    auto req2 = req;
    req2.path = "http://" +
                detail::make_host_and_port_string(host_, port_, false) +
                req.path;
    ret = process_request(strm, req2, res, close_connection, error);
    req = std::move(req2);
    req.path = req_save.path;
  } else {
    ret = process_request(strm, req, res, close_connection, error);
  }

  if (!ret) { return false; }

  if (res.get_header_value("Connection") == "close" ||
      (res.version == "HTTP/1.0" && res.reason != "Connection established")) {
    // NOTE: this requires a not-entirely-obvious chain of calls to be correct
    // for this to be safe.

    // This is safe to call because handle_request is only called by send_
    // which locks the request mutex during the process. It would be a bug
    // to call it from a different thread since it's a thread-safety issue
    // to do these things to the socket if another thread is using the socket.
    std::lock_guard<std::mutex> guard(socket_mutex_);
    shutdown_ssl(socket_, true);
    shutdown_socket(socket_);
    close_socket(socket_);
  }

  if (300 < res.status && res.status < 400 && follow_location_) {
    req = std::move(req_save);
    ret = redirect(req, res, error);
  }

#ifdef CPPHTTPLIB_SSL_ENABLED
  if ((res.status == StatusCode::Unauthorized_401 ||
       res.status == StatusCode::ProxyAuthenticationRequired_407) &&
      req.authorization_count_ < 5) {
    auto is_proxy = res.status == StatusCode::ProxyAuthenticationRequired_407;
    const auto &username =
        is_proxy ? proxy_digest_auth_username_ : digest_auth_username_;
    const auto &password =
        is_proxy ? proxy_digest_auth_password_ : digest_auth_password_;

    if (!username.empty() && !password.empty()) {
      std::map<std::string, std::string> auth;
      if (detail::parse_www_authenticate(res, auth, is_proxy)) {
        Request new_req = req;
        new_req.authorization_count_ += 1;
        new_req.headers.erase(is_proxy ? "Proxy-Authorization"
                                       : "Authorization");
        new_req.headers.insert(detail::make_digest_authentication_header(
            req, auth, new_req.authorization_count_, detail::random_string(10),
            username, password, is_proxy));

        Response new_res;

        ret = send(new_req, new_res, error);
        if (ret) { res = std::move(new_res); }
      }
    }
  }
#endif

  return ret;
}

bool ClientImpl::redirect(Request &req, Response &res, Error &error) {
  if (req.redirect_count_ == 0) {
    error = Error::ExceedRedirectCount;
    output_error_log(error, &req);
    return false;
  }

  auto location = res.get_header_value("location");
  if (location.empty()) { return false; }

  thread_local const std::regex re(
      R"((?:(https?):)?(?://(?:\[([a-fA-F\d:]+)\]|([^:/?#]+))(?::(\d+))?)?([^?#]*)(\?[^#]*)?(?:#.*)?)");

  std::smatch m;
  if (!std::regex_match(location, m, re)) { return false; }

  auto scheme = is_ssl() ? "https" : "http";

  auto next_scheme = m[1].str();
  auto next_host = m[2].str();
  if (next_host.empty()) { next_host = m[3].str(); }
  auto port_str = m[4].str();
  auto next_path = m[5].str();
  auto next_query = m[6].str();

  auto next_port = port_;
  if (!port_str.empty()) {
    if (!detail::parse_port(port_str, next_port)) { return false; }
  } else if (!next_scheme.empty()) {
    next_port = next_scheme == "https" ? 443 : 80;
  }

  if (next_scheme.empty()) { next_scheme = scheme; }
  if (next_host.empty()) { next_host = host_; }
  if (next_path.empty()) { next_path = "/"; }

  auto path = decode_query_component(next_path, true) + next_query;

  // Same host redirect - use current client
  if (next_scheme == scheme && next_host == host_ && next_port == port_) {
    return detail::redirect(*this, req, res, path, location, error);
  }

  // Cross-host/scheme redirect - create new client with robust setup
  return create_redirect_client(next_scheme, next_host, next_port, req, res,
                                path, location, error);
}

// New method for robust redirect client creation
bool ClientImpl::create_redirect_client(
    const std::string &scheme, const std::string &host, int port, Request &req,
    Response &res, const std::string &path, const std::string &location,
    Error &error) {
  // Determine if we need SSL
  auto need_ssl = (scheme == "https");

  // Clean up request headers that are host/client specific
  // Remove headers that should not be carried over to new host
  auto headers_to_remove =
      std::vector<std::string>{"Host", "Proxy-Authorization", "Authorization"};

  for (const auto &header_name : headers_to_remove) {
    auto it = req.headers.find(header_name);
    while (it != req.headers.end()) {
      it = req.headers.erase(it);
      it = req.headers.find(header_name);
    }
  }

  // Create appropriate client type and handle redirect
  if (need_ssl) {
#ifdef CPPHTTPLIB_SSL_ENABLED
    // Create SSL client for HTTPS redirect
    SSLClient redirect_client(host, port);

    // Setup basic client configuration first
    setup_redirect_client(redirect_client);

    redirect_client.enable_server_certificate_verification(
        server_certificate_verification_);
    redirect_client.enable_server_hostname_verification(
        server_hostname_verification_);

    // Transfer CA certificate to redirect client
    if (!ca_cert_pem_.empty()) {
      redirect_client.load_ca_cert_store(ca_cert_pem_.c_str(),
                                         ca_cert_pem_.size());
    }
    if (!ca_cert_file_path_.empty()) {
      redirect_client.set_ca_cert_path(ca_cert_file_path_, ca_cert_dir_path_);
    }

    // Client certificates are set through constructor for SSLClient
    // NOTE: SSLClient constructor already takes client_cert_path and
    // client_key_path so we need to create it properly if client certs are
    // needed

    // Execute the redirect
    return detail::redirect(redirect_client, req, res, path, location, error);
#else
    // SSL not supported - set appropriate error
    error = Error::SSLConnection;
    output_error_log(error, &req);
    return false;
#endif
  } else {
    // HTTP redirect
    ClientImpl redirect_client(host, port);

    // Setup client with robust configuration
    setup_redirect_client(redirect_client);

    // Execute the redirect
    return detail::redirect(redirect_client, req, res, path, location, error);
  }
}

// New method for robust client setup (based on basic_manual_redirect.cpp
// logic)
template <typename ClientType>
void ClientImpl::setup_redirect_client(ClientType &client) {
  // Copy basic settings first
  client.set_connection_timeout(connection_timeout_sec_);
  client.set_read_timeout(read_timeout_sec_, read_timeout_usec_);
  client.set_write_timeout(write_timeout_sec_, write_timeout_usec_);
  client.set_keep_alive(keep_alive_);
  client.set_follow_location(
      true); // Enable redirects to handle multi-step redirects
  client.set_path_encode(path_encode_);
  client.set_compress(compress_);
  client.set_decompress(decompress_);

  // Copy authentication settings BEFORE proxy setup
  if (!basic_auth_username_.empty()) {
    client.set_basic_auth(basic_auth_username_, basic_auth_password_);
  }
  if (!bearer_token_auth_token_.empty()) {
    client.set_bearer_token_auth(bearer_token_auth_token_);
  }
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (!digest_auth_username_.empty()) {
    client.set_digest_auth(digest_auth_username_, digest_auth_password_);
  }
#endif

  // Setup proxy configuration (CRITICAL ORDER - proxy must be set
  // before proxy auth)
  if (!proxy_host_.empty() && proxy_port_ != -1) {
    // First set proxy host and port
    client.set_proxy(proxy_host_, proxy_port_);

    // Then set proxy authentication (order matters!)
    if (!proxy_basic_auth_username_.empty()) {
      client.set_proxy_basic_auth(proxy_basic_auth_username_,
                                  proxy_basic_auth_password_);
    }
    if (!proxy_bearer_token_auth_token_.empty()) {
      client.set_proxy_bearer_token_auth(proxy_bearer_token_auth_token_);
    }
#ifdef CPPHTTPLIB_SSL_ENABLED
    if (!proxy_digest_auth_username_.empty()) {
      client.set_proxy_digest_auth(proxy_digest_auth_username_,
                                   proxy_digest_auth_password_);
    }
#endif
  }

  // Copy network and socket settings
  client.set_address_family(address_family_);
  client.set_tcp_nodelay(tcp_nodelay_);
  client.set_ipv6_v6only(ipv6_v6only_);
  if (socket_options_) { client.set_socket_options(socket_options_); }
  if (!interface_.empty()) { client.set_interface(interface_); }

  // Copy logging and headers
  if (logger_) { client.set_logger(logger_); }
  if (error_logger_) { client.set_error_logger(error_logger_); }

  // NOTE: DO NOT copy default_headers_ as they may contain stale Host headers
  // Each new client should generate its own headers based on its target host
}

bool ClientImpl::write_content_with_provider(Stream &strm,
                                                    const Request &req,
                                                    Error &error) const {
  auto is_shutting_down = []() { return false; };

  if (req.is_chunked_content_provider_) {
    auto compressor = compress_ ? detail::create_compressor().first
                                : std::unique_ptr<detail::compressor>();
    if (!compressor) {
      compressor = detail::make_unique<detail::nocompressor>();
    }

    return detail::write_content_chunked(strm, req.content_provider_,
                                         is_shutting_down, *compressor, error);
  } else {
    return detail::write_content_with_progress(
        strm, req.content_provider_, 0, req.content_length_, is_shutting_down,
        req.upload_progress, error);
  }
}

bool ClientImpl::write_request(Stream &strm, Request &req,
                                      bool close_connection, Error &error,
                                      bool skip_body) {
  // Prepare additional headers
  if (close_connection) {
    if (!req.has_header("Connection")) {
      req.set_header("Connection", "close");
    }
  }

  std::string ct_for_defaults;
  if (!req.has_header("Content-Type") && !req.body.empty()) {
    ct_for_defaults = "text/plain";
  }
  prepare_default_headers(req, false, ct_for_defaults);

  if (req.body.empty()) {
    if (req.content_provider_) {
      if (!req.is_chunked_content_provider_) {
        if (!req.has_header("Content-Length")) {
          auto length = std::to_string(req.content_length_);
          req.set_header("Content-Length", length);
        }
      }
    } else {
      if (req.method == "POST" || req.method == "PUT" ||
          req.method == "PATCH") {
        req.set_header("Content-Length", "0");
      }
    }
  }

  if (!basic_auth_password_.empty() || !basic_auth_username_.empty()) {
    if (!req.has_header("Authorization")) {
      req.headers.insert(make_basic_authentication_header(
          basic_auth_username_, basic_auth_password_, false));
    }
  }

  if (!proxy_basic_auth_username_.empty() &&
      !proxy_basic_auth_password_.empty()) {
    if (!req.has_header("Proxy-Authorization")) {
      req.headers.insert(make_basic_authentication_header(
          proxy_basic_auth_username_, proxy_basic_auth_password_, true));
    }
  }

  if (!bearer_token_auth_token_.empty()) {
    if (!req.has_header("Authorization")) {
      req.headers.insert(make_bearer_token_authentication_header(
          bearer_token_auth_token_, false));
    }
  }

  if (!proxy_bearer_token_auth_token_.empty()) {
    if (!req.has_header("Proxy-Authorization")) {
      req.headers.insert(make_bearer_token_authentication_header(
          proxy_bearer_token_auth_token_, true));
    }
  }

  // Request line and headers
  {
    detail::BufferStream bstrm;

    // Extract path and query from req.path
    std::string path_part, query_part;
    auto query_pos = req.path.find('?');
    if (query_pos != std::string::npos) {
      path_part = req.path.substr(0, query_pos);
      query_part = req.path.substr(query_pos + 1);
    } else {
      path_part = req.path;
      query_part = "";
    }

    // Encode path part. If the original `req.path` already contained a
    // query component, preserve its raw query string (including parameter
    // order) instead of reparsing and reassembling it which may reorder
    // parameters due to container ordering (e.g. `Params` uses
    // `std::multimap`). When there is no query in `req.path`, fall back to
    // building a query from `req.params` so existing callers that pass
    // `Params` continue to work.
    auto path_with_query =
        path_encode_ ? detail::encode_path(path_part) : path_part;

    if (!query_part.empty()) {
      // Normalize the query string (decode then re-encode) while preserving
      // the original parameter order.
      auto normalized = detail::normalize_query_string(query_part);
      if (!normalized.empty()) { path_with_query += '?' + normalized; }

      // Still populate req.params for handlers/users who read them.
      detail::parse_query_text(query_part, req.params);
    } else {
      // No query in path; parse any query_part (empty) and append params
      // from `req.params` when present (preserves prior behavior for
      // callers who provide Params separately).
      detail::parse_query_text(query_part, req.params);
      if (!req.params.empty()) {
        path_with_query = append_query_params(path_with_query, req.params);
      }
    }

    // Write request line and headers
    detail::write_request_line(bstrm, req.method, path_with_query);
    if (!detail::check_and_write_headers(bstrm, req.headers, header_writer_,
                                         error)) {
      output_error_log(error, &req);
      return false;
    }

    // Flush buffer
    auto &data = bstrm.get_buffer();
    if (!detail::write_data(strm, data.data(), data.size())) {
      error = Error::Write;
      output_error_log(error, &req);
      return false;
    }
  }

  // After sending request line and headers, wait briefly for an early server
  // response (e.g. 4xx) and avoid sending a potentially large request body
  // unnecessarily. This workaround is only enabled on Windows because Unix
  // platforms surface write errors (EPIPE) earlier; on Windows kernel send
  // buffering can accept large writes even when the peer already responded.
  // Check the stream first (which covers SSL via `is_readable()`), then
  // fall back to select on the socket. Only perform the wait for very large
  // request bodies to avoid interfering with normal small requests and
  // reduce side-effects. Poll briefly (up to 50ms as default) for an early
  // response. Skip this check when using Expect: 100-continue, as the protocol
  // handles early responses properly.
#if defined(_WIN32)
  if (!skip_body &&
      req.body.size() > CPPHTTPLIB_WAIT_EARLY_SERVER_RESPONSE_THRESHOLD &&
      req.path.size() > CPPHTTPLIB_REQUEST_URI_MAX_LENGTH) {
    auto start = std::chrono::high_resolution_clock::now();

    for (;;) {
      // Prefer socket-level readiness to avoid SSL_pending() false-positives
      // from SSL internals. If the underlying socket is readable, assume an
      // early response may be present.
      auto sock = strm.socket();
      if (sock != INVALID_SOCKET && detail::select_read(sock, 0, 0) > 0) {
        return false;
      }

      // Fallback to stream-level check for non-socket streams or when the
      // socket isn't reporting readable. Avoid using `is_readable()` for
      // SSL, since `SSL_pending()` may report buffered records that do not
      // indicate a complete application-level response yet.
      if (!is_ssl() && strm.is_readable()) { return false; }

      auto now = std::chrono::high_resolution_clock::now();
      auto elapsed =
          std::chrono::duration_cast<std::chrono::milliseconds>(now - start)
              .count();
      if (elapsed >= CPPHTTPLIB_WAIT_EARLY_SERVER_RESPONSE_TIMEOUT_MSECOND) {
        break;
      }

      std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
  }
#endif

  // Body
  if (skip_body) { return true; }

  return write_request_body(strm, req, error);
}

bool ClientImpl::write_request_body(Stream &strm, Request &req,
                                           Error &error) {
  if (req.body.empty()) {
    return write_content_with_provider(strm, req, error);
  }

  if (req.upload_progress) {
    auto body_size = req.body.size();
    size_t written = 0;
    auto data = req.body.data();

    while (written < body_size) {
      size_t to_write = (std::min)(CPPHTTPLIB_SEND_BUFSIZ, body_size - written);
      if (!detail::write_data(strm, data + written, to_write)) {
        error = Error::Write;
        output_error_log(error, &req);
        return false;
      }
      written += to_write;

      if (!req.upload_progress(written, body_size)) {
        error = Error::Canceled;
        output_error_log(error, &req);
        return false;
      }
    }
  } else {
    if (!detail::write_data(strm, req.body.data(), req.body.size())) {
      error = Error::Write;
      output_error_log(error, &req);
      return false;
    }
  }

  return true;
}

std::unique_ptr<Response>
ClientImpl::send_with_content_provider_and_receiver(
    Request &req, const char *body, size_t content_length,
    ContentProvider content_provider,
    ContentProviderWithoutLength content_provider_without_length,
    const std::string &content_type, ContentReceiver content_receiver,
    Error &error) {
  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  auto enc = compress_
                 ? detail::create_compressor()
                 : std::pair<std::unique_ptr<detail::compressor>, const char *>(
                       nullptr, nullptr);

  if (enc.second) { req.set_header("Content-Encoding", enc.second); }

  if (enc.first && !content_provider_without_length) {
    auto &compressor = enc.first;

    if (content_provider) {
      auto ok = true;
      size_t offset = 0;
      DataSink data_sink;

      data_sink.write = [&](const char *data, size_t data_len) -> bool {
        if (ok) {
          auto last = offset + data_len == content_length;

          auto ret = compressor->compress(
              data, data_len, last,
              [&](const char *compressed_data, size_t compressed_data_len) {
                req.body.append(compressed_data, compressed_data_len);
                return true;
              });

          if (ret) {
            offset += data_len;
          } else {
            ok = false;
          }
        }
        return ok;
      };

      while (ok && offset < content_length) {
        if (!content_provider(offset, content_length - offset, data_sink)) {
          error = Error::Canceled;
          output_error_log(error, &req);
          return nullptr;
        }
      }
    } else {
      if (!compressor->compress(body, content_length, true,
                                [&](const char *data, size_t data_len) {
                                  req.body.append(data, data_len);
                                  return true;
                                })) {
        error = Error::Compression;
        output_error_log(error, &req);
        return nullptr;
      }
    }
  } else {
    if (content_provider) {
      req.content_length_ = content_length;
      req.content_provider_ = std::move(content_provider);
      req.is_chunked_content_provider_ = false;
    } else if (content_provider_without_length) {
      req.content_length_ = 0;
      req.content_provider_ = detail::ContentProviderAdapter(
          std::move(content_provider_without_length));
      req.is_chunked_content_provider_ = true;
      req.set_header("Transfer-Encoding", "chunked");
    } else {
      req.body.assign(body, content_length);
    }
  }

  if (content_receiver) {
    req.content_receiver =
        [content_receiver](const char *data, size_t data_length,
                           size_t /*offset*/, size_t /*total_length*/) {
          return content_receiver(data, data_length);
        };
  }

  auto res = detail::make_unique<Response>();
  return send(req, *res, error) ? std::move(res) : nullptr;
}

Result ClientImpl::send_with_content_provider_and_receiver(
    const std::string &method, const std::string &path, const Headers &headers,
    const char *body, size_t content_length, ContentProvider content_provider,
    ContentProviderWithoutLength content_provider_without_length,
    const std::string &content_type, ContentReceiver content_receiver,
    UploadProgress progress) {
  Request req;
  req.method = method;
  req.headers = headers;
  req.path = path;
  req.upload_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  auto error = Error::Success;

  auto res = send_with_content_provider_and_receiver(
      req, body, content_length, std::move(content_provider),
      std::move(content_provider_without_length), content_type,
      std::move(content_receiver), error);

#ifdef CPPHTTPLIB_SSL_ENABLED
  return Result{std::move(res), error, std::move(req.headers), last_ssl_error_,
                last_backend_error_};
#else
  return Result{std::move(res), error, std::move(req.headers)};
#endif
}

void ClientImpl::output_log(const Request &req,
                                   const Response &res) const {
  if (logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    logger_(req, res);
  }
}

void ClientImpl::output_error_log(const Error &err,
                                         const Request *req) const {
  if (error_logger_) {
    std::lock_guard<std::mutex> guard(logger_mutex_);
    error_logger_(err, req);
  }
}

bool ClientImpl::process_request(Stream &strm, Request &req,
                                        Response &res, bool close_connection,
                                        Error &error) {
  // Auto-add Expect: 100-continue for large bodies
  if (CPPHTTPLIB_EXPECT_100_THRESHOLD > 0 && !req.has_header("Expect")) {
    auto body_size = req.body.empty() ? req.content_length_ : req.body.size();
    if (body_size >= CPPHTTPLIB_EXPECT_100_THRESHOLD) {
      req.set_header("Expect", "100-continue");
    }
  }

  // Check for Expect: 100-continue
  auto expect_100_continue = req.get_header_value("Expect") == "100-continue";

  // Send request (skip body if using Expect: 100-continue)
  auto write_request_success =
      write_request(strm, req, close_connection, error, expect_100_continue);

#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl() && !expect_100_continue) {
    auto is_proxy_enabled = !proxy_host_.empty() && proxy_port_ != -1;
    if (!is_proxy_enabled) {
      if (tls::is_peer_closed(socket_.ssl, socket_.sock)) {
        error = Error::SSLPeerCouldBeClosed_;
        output_error_log(error, &req);
        return false;
      }
    }
  }
#endif

  // Handle Expect: 100-continue with timeout
  if (expect_100_continue && CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND > 0) {
    time_t sec = CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND / 1000;
    time_t usec = (CPPHTTPLIB_EXPECT_100_TIMEOUT_MSECOND % 1000) * 1000;
    auto ret = detail::select_read(strm.socket(), sec, usec);
    if (ret <= 0) {
      // Timeout or error: send body anyway (server didn't respond in time)
      if (!write_request_body(strm, req, error)) { return false; }
      expect_100_continue = false; // Switch to normal response handling
    }
  }

  // Receive response and headers
  // When using Expect: 100-continue, don't auto-skip `100 Continue` response
  if (!read_response_line(strm, req, res, !expect_100_continue) ||
      !detail::read_headers(strm, res.headers)) {
    if (write_request_success) { error = Error::Read; }
    output_error_log(error, &req);
    return false;
  }

  if (!write_request_success) { return false; }

  // Handle Expect: 100-continue response
  if (expect_100_continue) {
    if (res.status == StatusCode::Continue_100) {
      // Server accepted, send the body
      if (!write_request_body(strm, req, error)) { return false; }

      // Read the actual response
      res.headers.clear();
      res.body.clear();
      if (!read_response_line(strm, req, res) ||
          !detail::read_headers(strm, res.headers)) {
        error = Error::Read;
        output_error_log(error, &req);
        return false;
      }
    }
    // If not 100 Continue, server returned an error; proceed with that response
  }

  // Body
  if ((res.status != StatusCode::NoContent_204) && req.method != "HEAD" &&
      req.method != "CONNECT") {
    auto redirect = 300 < res.status && res.status < 400 &&
                    res.status != StatusCode::NotModified_304 &&
                    follow_location_;

    if (req.response_handler && !redirect) {
      if (!req.response_handler(res)) {
        error = Error::Canceled;
        output_error_log(error, &req);
        return false;
      }
    }

    auto out =
        req.content_receiver
            ? static_cast<ContentReceiverWithProgress>(
                  [&](const char *buf, size_t n, size_t off, size_t len) {
                    if (redirect) { return true; }
                    auto ret = req.content_receiver(buf, n, off, len);
                    if (!ret) {
                      error = Error::Canceled;
                      output_error_log(error, &req);
                    }
                    return ret;
                  })
            : static_cast<ContentReceiverWithProgress>(
                  [&](const char *buf, size_t n, size_t /*off*/,
                      size_t /*len*/) {
                    assert(res.body.size() + n <= res.body.max_size());
                    if (payload_max_length_ > 0 &&
                        (res.body.size() >= payload_max_length_ ||
                         n > payload_max_length_ - res.body.size())) {
                      return false;
                    }
                    res.body.append(buf, n);
                    return true;
                  });

    auto progress = [&](size_t current, size_t total) {
      if (!req.download_progress || redirect) { return true; }
      auto ret = req.download_progress(current, total);
      if (!ret) {
        error = Error::Canceled;
        output_error_log(error, &req);
      }
      return ret;
    };

    if (res.has_header("Content-Length")) {
      if (!req.content_receiver) {
        auto len = res.get_header_value_u64("Content-Length");
        if (len > res.body.max_size()) {
          error = Error::Read;
          output_error_log(error, &req);
          return false;
        }
        res.body.reserve(static_cast<size_t>(len));
      }
    }

    if (res.status != StatusCode::NotModified_304) {
      int dummy_status;
      auto max_length = (!has_payload_max_length_ && req.content_receiver)
                            ? (std::numeric_limits<size_t>::max)()
                            : payload_max_length_;
      if (!detail::read_content(strm, res, max_length, dummy_status,
                                std::move(progress), std::move(out),
                                decompress_)) {
        if (error != Error::Canceled) { error = Error::Read; }
        output_error_log(error, &req);
        return false;
      }
    }
  }

  // Log
  output_log(req, res);

  return true;
}

ContentProviderWithoutLength ClientImpl::get_multipart_content_provider(
    const std::string &boundary, const UploadFormDataItems &items,
    const FormDataProviderItems &provider_items) const {
  size_t cur_item = 0;
  size_t cur_start = 0;
  // cur_item and cur_start are copied to within the std::function and
  // maintain state between successive calls
  return [&, cur_item, cur_start](size_t offset,
                                  DataSink &sink) mutable -> bool {
    if (!offset && !items.empty()) {
      sink.os << detail::serialize_multipart_formdata(items, boundary, false);
      return true;
    } else if (cur_item < provider_items.size()) {
      if (!cur_start) {
        const auto &begin = detail::serialize_multipart_formdata_item_begin(
            provider_items[cur_item], boundary);
        offset += begin.size();
        cur_start = offset;
        sink.os << begin;
      }

      DataSink cur_sink;
      auto has_data = true;
      cur_sink.write = sink.write;
      cur_sink.done = [&]() { has_data = false; };

      if (!provider_items[cur_item].provider(offset - cur_start, cur_sink)) {
        return false;
      }

      if (!has_data) {
        sink.os << detail::serialize_multipart_formdata_item_end();
        cur_item++;
        cur_start = 0;
      }
      return true;
    } else {
      sink.os << detail::serialize_multipart_formdata_finish(boundary);
      sink.done();
      return true;
    }
  };
}

bool ClientImpl::process_socket(
    const Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &strm)> callback) {
  return detail::process_client_socket(
      socket.sock, read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, max_timeout_msec_, start_time, std::move(callback));
}

bool ClientImpl::is_ssl() const { return false; }

Result ClientImpl::Get(const std::string &path,
                              DownloadProgress progress) {
  return Get(path, Headers(), std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              DownloadProgress progress) {
  if (params.empty()) { return Get(path, headers); }

  std::string path_with_query = append_query_params(path, params);
  return Get(path_with_query, headers, std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              DownloadProgress progress) {
  Request req;
  req.method = "GET";
  req.path = path;
  req.headers = headers;
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Get(const std::string &path,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, Headers(), nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, headers, nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, Headers(), std::move(response_handler),
             std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Headers &headers,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  Request req;
  req.method = "GET";
  req.path = path;
  req.headers = headers;
  req.response_handler = std::move(response_handler);
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  return Get(path, params, headers, nullptr, std::move(content_receiver),
             std::move(progress));
}

Result ClientImpl::Get(const std::string &path, const Params &params,
                              const Headers &headers,
                              ResponseHandler response_handler,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  if (params.empty()) {
    return Get(path, headers, std::move(response_handler),
               std::move(content_receiver), std::move(progress));
  }

  std::string path_with_query = append_query_params(path, params);
  return Get(path_with_query, headers, std::move(response_handler),
             std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Head(const std::string &path) {
  return Head(path, Headers());
}

Result ClientImpl::Head(const std::string &path,
                               const Headers &headers) {
  Request req;
  req.method = "HEAD";
  req.headers = headers;
  req.path = path;
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

Result ClientImpl::Post(const std::string &path) {
  return Post(path, std::string(), std::string());
}

Result ClientImpl::Post(const std::string &path,
                               const Headers &headers) {
  return Post(path, headers, nullptr, 0, std::string());
}

Result ClientImpl::Post(const std::string &path, const char *body,
                               size_t content_length,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const std::string &body,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Params &params) {
  return Post(path, Headers(), params);
}

Result ClientImpl::Post(const std::string &path, size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), content_length, std::move(content_provider),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               UploadProgress progress) {
  return Post(path, Headers(), content_length, std::move(content_provider),
              content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Post(const std::string &path,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return Post(path, Headers(), std::move(content_provider), content_type,
              progress);
}

Result ClientImpl::Post(const std::string &path,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               UploadProgress progress) {
  return Post(path, Headers(), std::move(content_provider), content_type,
              std::move(content_receiver), progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Post(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Post(const std::string &path,
                               const UploadFormDataItems &items,
                               UploadProgress progress) {
  return Post(path, Headers(), items, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Post(path, headers, content_length,
              detail::make_multipart_content_provider(items, boundary),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               const std::string &boundary,
                               UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Post(path, headers, content_length,
              detail::make_multipart_content_provider(items, boundary),
              content_type, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const char *body, size_t content_length,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const std::string &body,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               size_t content_length,
                               ContentProvider content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               ContentProviderWithoutLength content_provider,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), std::move(progress));
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const UploadFormDataItems &items,
                               const FormDataProviderItems &provider_items,
                               UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "POST", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Post(const std::string &path, const Headers &headers,
                               const std::string &body,
                               const std::string &content_type,
                               ContentReceiver content_receiver,
                               DownloadProgress progress) {
  Request req;
  req.method = "POST";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Put(const std::string &path) {
  return Put(path, std::string(), std::string());
}

Result ClientImpl::Put(const std::string &path, const Headers &headers) {
  return Put(path, headers, nullptr, 0, std::string());
}

Result ClientImpl::Put(const std::string &path, const char *body,
                              size_t content_length,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const std::string &body,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Params &params) {
  return Put(path, Headers(), params);
}

Result ClientImpl::Put(const std::string &path, size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), content_length, std::move(content_provider),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return Put(path, Headers(), content_length, std::move(content_provider),
             content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return Put(path, Headers(), std::move(content_provider), content_type,
             progress);
}

Result ClientImpl::Put(const std::string &path,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return Put(path, Headers(), std::move(content_provider), content_type,
             std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Put(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Put(const std::string &path,
                              const UploadFormDataItems &items,
                              UploadProgress progress) {
  return Put(path, Headers(), items, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Put(path, headers, content_length,
             detail::make_multipart_content_provider(items, boundary),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              const std::string &boundary,
                              UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Put(path, headers, content_length,
             detail::make_multipart_content_provider(items, boundary),
             content_type, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const char *body, size_t content_length,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const std::string &body,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              size_t content_length,
                              ContentProvider content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              ContentProviderWithoutLength content_provider,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const UploadFormDataItems &items,
                              const FormDataProviderItems &provider_items,
                              UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "PUT", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Put(const std::string &path, const Headers &headers,
                              const std::string &body,
                              const std::string &content_type,
                              ContentReceiver content_receiver,
                              DownloadProgress progress) {
  Request req;
  req.method = "PUT";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Patch(const std::string &path) {
  return Patch(path, std::string(), std::string());
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                UploadProgress progress) {
  return Patch(path, headers, nullptr, 0, std::string(), progress);
}

Result ClientImpl::Patch(const std::string &path, const char *body,
                                size_t content_length,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Patch(const std::string &path,
                                const std::string &body,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), body, content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Params &params) {
  return Patch(path, Headers(), params);
}

Result ClientImpl::Patch(const std::string &path, size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), content_length, std::move(content_provider),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return Patch(path, Headers(), content_length, std::move(content_provider),
               content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return Patch(path, Headers(), std::move(content_provider), content_type,
               progress);
}

Result ClientImpl::Patch(const std::string &path,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return Patch(path, Headers(), std::move(content_provider), content_type,
               std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const Params &params) {
  auto query = detail::params_to_query_str(params);
  return Patch(path, headers, query, "application/x-www-form-urlencoded");
}

Result ClientImpl::Patch(const std::string &path,
                                const UploadFormDataItems &items,
                                UploadProgress progress) {
  return Patch(path, Headers(), items, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Patch(path, headers, content_length,
               detail::make_multipart_content_provider(items, boundary),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                const std::string &boundary,
                                UploadProgress progress) {
  if (!detail::is_multipart_boundary_chars_valid(boundary)) {
    return Result{nullptr, Error::UnsupportedMultipartBoundaryChars};
  }

  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  auto content_length = detail::get_multipart_content_length(items, boundary);
  return Patch(path, headers, content_length,
               detail::make_multipart_content_provider(items, boundary),
               content_type, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const char *body, size_t content_length,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, body, content_length, nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const std::string &body,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, body.data(), body.size(), nullptr, nullptr,
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                size_t content_length,
                                ContentProvider content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, content_length,
      std::move(content_provider), nullptr, content_type,
      std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                ContentProviderWithoutLength content_provider,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                UploadProgress progress) {
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr, std::move(content_provider),
      content_type, std::move(content_receiver), progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const UploadFormDataItems &items,
                                const FormDataProviderItems &provider_items,
                                UploadProgress progress) {
  const auto &boundary = detail::make_multipart_data_boundary();
  const auto &content_type =
      detail::serialize_multipart_formdata_get_content_type(boundary);
  return send_with_content_provider_and_receiver(
      "PATCH", path, headers, nullptr, 0, nullptr,
      get_multipart_content_provider(boundary, items, provider_items),
      content_type, nullptr, progress);
}

Result ClientImpl::Patch(const std::string &path, const Headers &headers,
                                const std::string &body,
                                const std::string &content_type,
                                ContentReceiver content_receiver,
                                DownloadProgress progress) {
  Request req;
  req.method = "PATCH";
  req.path = path;
  req.headers = headers;
  req.body = body;
  req.content_receiver =
      [content_receiver](const char *data, size_t data_length,
                         size_t /*offset*/, size_t /*total_length*/) {
        return content_receiver(data, data_length);
      };
  req.download_progress = std::move(progress);

  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }

  return send_(std::move(req));
}

Result ClientImpl::Delete(const std::string &path,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), std::string(), std::string(), progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers,
                                 DownloadProgress progress) {
  return Delete(path, headers, std::string(), std::string(), progress);
}

Result ClientImpl::Delete(const std::string &path, const char *body,
                                 size_t content_length,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), body, content_length, content_type, progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const std::string &body,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), body.data(), body.size(), content_type,
                progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers,
                                 const std::string &body,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  return Delete(path, headers, body.data(), body.size(), content_type,
                progress);
}

Result ClientImpl::Delete(const std::string &path, const Params &params,
                                 DownloadProgress progress) {
  return Delete(path, Headers(), params, progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers, const Params &params,
                                 DownloadProgress progress) {
  auto query = detail::params_to_query_str(params);
  return Delete(path, headers, query, "application/x-www-form-urlencoded",
                progress);
}

Result ClientImpl::Delete(const std::string &path,
                                 const Headers &headers, const char *body,
                                 size_t content_length,
                                 const std::string &content_type,
                                 DownloadProgress progress) {
  Request req;
  req.method = "DELETE";
  req.headers = headers;
  req.path = path;
  req.download_progress = std::move(progress);
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }
  req.body.assign(body, content_length);

  return send_(std::move(req));
}

Result ClientImpl::Options(const std::string &path) {
  return Options(path, Headers());
}

Result ClientImpl::Options(const std::string &path,
                                  const Headers &headers) {
  Request req;
  req.method = "OPTIONS";
  req.headers = headers;
  req.path = path;
  if (max_timeout_msec_ > 0) {
    req.start_time_ = std::chrono::steady_clock::now();
  }

  return send_(std::move(req));
}

void ClientImpl::stop() {
  std::lock_guard<std::mutex> guard(socket_mutex_);

  // If there is anything ongoing right now, the ONLY thread-safe thing we can
  // do is to shutdown_socket, so that threads using this socket suddenly
  // discover they can't read/write any more and error out. Everything else
  // (closing the socket, shutting ssl down) is unsafe because these actions
  // are not thread-safe.
  if (socket_requests_in_flight_ > 0) {
    shutdown_socket(socket_);

    // Aside from that, we set a flag for the socket to be closed when we're
    // done.
    socket_should_be_closed_when_request_is_done_ = true;
    return;
  }

  // Otherwise, still holding the mutex, we can shut everything down ourselves
  shutdown_ssl(socket_, true);
  shutdown_socket(socket_);
  close_socket(socket_);
}

std::string ClientImpl::host() const { return host_; }

int ClientImpl::port() const { return port_; }

size_t ClientImpl::is_socket_open() const {
  std::lock_guard<std::mutex> guard(socket_mutex_);
  return socket_.is_open();
}

socket_t ClientImpl::socket() const { return socket_.sock; }

void ClientImpl::set_connection_timeout(time_t sec, time_t usec) {
  connection_timeout_sec_ = sec;
  connection_timeout_usec_ = usec;
}

void ClientImpl::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

void ClientImpl::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
}

void ClientImpl::set_max_timeout(time_t msec) {
  max_timeout_msec_ = msec;
}

void ClientImpl::set_basic_auth(const std::string &username,
                                       const std::string &password) {
  basic_auth_username_ = username;
  basic_auth_password_ = password;
}

void ClientImpl::set_bearer_token_auth(const std::string &token) {
  bearer_token_auth_token_ = token;
}

void ClientImpl::set_keep_alive(bool on) { keep_alive_ = on; }

void ClientImpl::set_follow_location(bool on) { follow_location_ = on; }

void ClientImpl::set_path_encode(bool on) { path_encode_ = on; }

void
ClientImpl::set_hostname_addr_map(std::map<std::string, std::string> addr_map) {
  addr_map_ = std::move(addr_map);
}

void ClientImpl::set_default_headers(Headers headers) {
  default_headers_ = std::move(headers);
}

void ClientImpl::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  header_writer_ = writer;
}

void ClientImpl::set_address_family(int family) {
  address_family_ = family;
}

void ClientImpl::set_tcp_nodelay(bool on) { tcp_nodelay_ = on; }

void ClientImpl::set_ipv6_v6only(bool on) { ipv6_v6only_ = on; }

void ClientImpl::set_socket_options(SocketOptions socket_options) {
  socket_options_ = std::move(socket_options);
}

void ClientImpl::set_compress(bool on) { compress_ = on; }

void ClientImpl::set_decompress(bool on) { decompress_ = on; }

void ClientImpl::set_payload_max_length(size_t length) {
  payload_max_length_ = length;
  has_payload_max_length_ = true;
}

void ClientImpl::set_interface(const std::string &intf) {
  interface_ = intf;
}

void ClientImpl::set_proxy(const std::string &host, int port) {
  proxy_host_ = host;
  proxy_port_ = port;
}

void ClientImpl::set_proxy_basic_auth(const std::string &username,
                                             const std::string &password) {
  proxy_basic_auth_username_ = username;
  proxy_basic_auth_password_ = password;
}

void ClientImpl::set_proxy_bearer_token_auth(const std::string &token) {
  proxy_bearer_token_auth_token_ = token;
}

#ifdef CPPHTTPLIB_SSL_ENABLED
void ClientImpl::set_digest_auth(const std::string &username,
                                        const std::string &password) {
  digest_auth_username_ = username;
  digest_auth_password_ = password;
}

void ClientImpl::set_ca_cert_path(const std::string &ca_cert_file_path,
                                         const std::string &ca_cert_dir_path) {
  ca_cert_file_path_ = ca_cert_file_path;
  ca_cert_dir_path_ = ca_cert_dir_path;
}

void ClientImpl::set_proxy_digest_auth(const std::string &username,
                                              const std::string &password) {
  proxy_digest_auth_username_ = username;
  proxy_digest_auth_password_ = password;
}

void ClientImpl::enable_server_certificate_verification(bool enabled) {
  server_certificate_verification_ = enabled;
}

void ClientImpl::enable_server_hostname_verification(bool enabled) {
  server_hostname_verification_ = enabled;
}
#endif

// ClientImpl::set_ca_cert_store is defined after TLS namespace (uses helpers)
#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
X509_STORE *ClientImpl::create_ca_cert_store(const char *ca_cert,
                                                    std::size_t size) const {
  auto mem = BIO_new_mem_buf(ca_cert, static_cast<int>(size));
  auto se = detail::scope_exit([&] { BIO_free_all(mem); });
  if (!mem) { return nullptr; }

  auto inf = PEM_X509_INFO_read_bio(mem, nullptr, nullptr, nullptr);
  if (!inf) { return nullptr; }

  auto cts = X509_STORE_new();
  if (cts) {
    for (auto i = 0; i < static_cast<int>(sk_X509_INFO_num(inf)); i++) {
      auto itmp = sk_X509_INFO_value(inf, i);
      if (!itmp) { continue; }

      if (itmp->x509) { X509_STORE_add_cert(cts, itmp->x509); }
      if (itmp->crl) { X509_STORE_add_crl(cts, itmp->crl); }
    }
  }

  sk_X509_INFO_pop_free(inf, X509_INFO_free);
  return cts;
}

void ClientImpl::set_server_certificate_verifier(
    std::function<SSLVerifierResponse(SSL *ssl)> /*verifier*/) {
  // Base implementation does nothing - SSLClient overrides this
}
#endif

void ClientImpl::set_logger(Logger logger) {
  logger_ = std::move(logger);
}

void ClientImpl::set_error_logger(ErrorLogger error_logger) {
  error_logger_ = std::move(error_logger);
}

/*
 * SSL/TLS Common Implementation
 */

ClientConnection::~ClientConnection() {
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (session) {
    tls::shutdown(session, true);
    tls::free_session(session);
    session = nullptr;
  }
#endif

  if (sock != INVALID_SOCKET) {
    detail::close_socket(sock);
    sock = INVALID_SOCKET;
  }
}

// Universal client implementation
Client::Client(const std::string &scheme_host_port)
    : Client(scheme_host_port, std::string(), std::string()) {}

Client::Client(const std::string &scheme_host_port,
                      const std::string &client_cert_path,
                      const std::string &client_key_path) {
  const static std::regex re(
      R"((?:([a-z]+):\/\/)?(?:\[([a-fA-F\d:]+)\]|([^:/?#]+))(?::(\d+))?)");

  std::smatch m;
  if (std::regex_match(scheme_host_port, m, re)) {
    auto scheme = m[1].str();

#ifdef CPPHTTPLIB_SSL_ENABLED
    if (!scheme.empty() && (scheme != "http" && scheme != "https")) {
#else
    if (!scheme.empty() && scheme != "http") {
#endif
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
      std::string msg = "'" + scheme + "' scheme is not supported.";
      throw std::invalid_argument(msg);
#endif
      return;
    }

    auto is_ssl = scheme == "https";

    auto host = m[2].str();
    if (host.empty()) { host = m[3].str(); }

    auto port_str = m[4].str();
    auto port = is_ssl ? 443 : 80;
    if (!port_str.empty() && !detail::parse_port(port_str, port)) { return; }

    if (is_ssl) {
#ifdef CPPHTTPLIB_SSL_ENABLED
      cli_ = detail::make_unique<SSLClient>(host, port, client_cert_path,
                                            client_key_path);
      is_ssl_ = is_ssl;
#endif
    } else {
      cli_ = detail::make_unique<ClientImpl>(host, port, client_cert_path,
                                             client_key_path);
    }
  } else {
    // NOTE: Update TEST(UniversalClientImplTest, Ipv6LiteralAddress)
    // if port param below changes.
    cli_ = detail::make_unique<ClientImpl>(scheme_host_port, 80,
                                           client_cert_path, client_key_path);
  }
} // namespace detail

Client::Client(const std::string &host, int port)
    : cli_(detail::make_unique<ClientImpl>(host, port)) {}

Client::Client(const std::string &host, int port,
                      const std::string &client_cert_path,
                      const std::string &client_key_path)
    : cli_(detail::make_unique<ClientImpl>(host, port, client_cert_path,
                                           client_key_path)) {}

Client::~Client() = default;

bool Client::is_valid() const {
  return cli_ != nullptr && cli_->is_valid();
}

Result Client::Get(const std::string &path, DownloadProgress progress) {
  return cli_->Get(path, std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(progress));
}
Result Client::Get(const std::string &path,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(content_receiver),
                   std::move(progress));
}
Result Client::Get(const std::string &path,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Headers &headers,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, headers, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers, DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(content_receiver),
                   std::move(progress));
}
Result Client::Get(const std::string &path, const Params &params,
                          const Headers &headers,
                          ResponseHandler response_handler,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Get(path, params, headers, std::move(response_handler),
                   std::move(content_receiver), std::move(progress));
}

Result Client::Head(const std::string &path) { return cli_->Head(path); }
Result Client::Head(const std::string &path, const Headers &headers) {
  return cli_->Head(path, headers);
}

Result Client::Post(const std::string &path) { return cli_->Post(path); }
Result Client::Post(const std::string &path, const Headers &headers) {
  return cli_->Post(path, headers);
}
Result Client::Post(const std::string &path, const char *body,
                           size_t content_length,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, body, content_length, content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const char *body, size_t content_length,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, body, content_length, content_type,
                    progress);
}
Result Client::Post(const std::string &path, const std::string &body,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, body, content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const std::string &body,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, body, content_type, progress);
}
Result Client::Post(const std::string &path, size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, content_length, std::move(content_provider),
                    content_type, progress);
}
Result Client::Post(const std::string &path, size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           UploadProgress progress) {
  return cli_->Post(path, content_length, std::move(content_provider),
                    content_type, std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, std::move(content_provider), content_type, progress);
}
Result Client::Post(const std::string &path,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           UploadProgress progress) {
  return cli_->Post(path, std::move(content_provider), content_type,
                    std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, content_length, std::move(content_provider),
                    content_type, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           size_t content_length,
                           ContentProvider content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, content_length, std::move(content_provider),
                    content_type, std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           UploadProgress progress) {
  return cli_->Post(path, headers, std::move(content_provider), content_type,
                    progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           ContentProviderWithoutLength content_provider,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, std::move(content_provider), content_type,
                    std::move(content_receiver), progress);
}
Result Client::Post(const std::string &path, const Params &params) {
  return cli_->Post(path, params);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const Params &params) {
  return cli_->Post(path, headers, params);
}
Result Client::Post(const std::string &path,
                           const UploadFormDataItems &items,
                           UploadProgress progress) {
  return cli_->Post(path, items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           const std::string &boundary,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, boundary, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const UploadFormDataItems &items,
                           const FormDataProviderItems &provider_items,
                           UploadProgress progress) {
  return cli_->Post(path, headers, items, provider_items, progress);
}
Result Client::Post(const std::string &path, const Headers &headers,
                           const std::string &body,
                           const std::string &content_type,
                           ContentReceiver content_receiver,
                           DownloadProgress progress) {
  return cli_->Post(path, headers, body, content_type,
                    std::move(content_receiver), progress);
}

Result Client::Put(const std::string &path) { return cli_->Put(path); }
Result Client::Put(const std::string &path, const Headers &headers) {
  return cli_->Put(path, headers);
}
Result Client::Put(const std::string &path, const char *body,
                          size_t content_length,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, body, content_length, content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const char *body, size_t content_length,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, body, content_length, content_type, progress);
}
Result Client::Put(const std::string &path, const std::string &body,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, body, content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const std::string &body,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, body, content_type, progress);
}
Result Client::Put(const std::string &path, size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, content_length, std::move(content_provider),
                   content_type, progress);
}
Result Client::Put(const std::string &path, size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, content_length, std::move(content_provider),
                   content_type, std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, std::move(content_provider), content_type, progress);
}
Result Client::Put(const std::string &path,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, std::move(content_provider), content_type,
                   std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, content_length, std::move(content_provider),
                   content_type, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          size_t content_length,
                          ContentProvider content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, headers, content_length, std::move(content_provider),
                   content_type, std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          UploadProgress progress) {
  return cli_->Put(path, headers, std::move(content_provider), content_type,
                   progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          ContentProviderWithoutLength content_provider,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          UploadProgress progress) {
  return cli_->Put(path, headers, std::move(content_provider), content_type,
                   std::move(content_receiver), progress);
}
Result Client::Put(const std::string &path, const Params &params) {
  return cli_->Put(path, params);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const Params &params) {
  return cli_->Put(path, headers, params);
}
Result Client::Put(const std::string &path,
                          const UploadFormDataItems &items,
                          UploadProgress progress) {
  return cli_->Put(path, items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          const std::string &boundary,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, boundary, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const UploadFormDataItems &items,
                          const FormDataProviderItems &provider_items,
                          UploadProgress progress) {
  return cli_->Put(path, headers, items, provider_items, progress);
}
Result Client::Put(const std::string &path, const Headers &headers,
                          const std::string &body,
                          const std::string &content_type,
                          ContentReceiver content_receiver,
                          DownloadProgress progress) {
  return cli_->Put(path, headers, body, content_type, content_receiver,
                   progress);
}

Result Client::Patch(const std::string &path) {
  return cli_->Patch(path);
}
Result Client::Patch(const std::string &path, const Headers &headers) {
  return cli_->Patch(path, headers);
}
Result Client::Patch(const std::string &path, const char *body,
                            size_t content_length,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, body, content_length, content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const char *body, size_t content_length,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, body, content_length, content_type,
                     progress);
}
Result Client::Patch(const std::string &path, const std::string &body,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, body, content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const std::string &body,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, body, content_type, progress);
}
Result Client::Patch(const std::string &path, size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, content_length, std::move(content_provider),
                     content_type, progress);
}
Result Client::Patch(const std::string &path, size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, content_length, std::move(content_provider),
                     content_type, std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, std::move(content_provider), content_type, progress);
}
Result Client::Patch(const std::string &path,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, std::move(content_provider), content_type,
                     std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, content_length, std::move(content_provider),
                     content_type, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            size_t content_length,
                            ContentProvider content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, content_length, std::move(content_provider),
                     content_type, std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, std::move(content_provider), content_type,
                     progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            ContentProviderWithoutLength content_provider,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, std::move(content_provider), content_type,
                     std::move(content_receiver), progress);
}
Result Client::Patch(const std::string &path, const Params &params) {
  return cli_->Patch(path, params);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const Params &params) {
  return cli_->Patch(path, headers, params);
}
Result Client::Patch(const std::string &path,
                            const UploadFormDataItems &items,
                            UploadProgress progress) {
  return cli_->Patch(path, items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            const std::string &boundary,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, boundary, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const UploadFormDataItems &items,
                            const FormDataProviderItems &provider_items,
                            UploadProgress progress) {
  return cli_->Patch(path, headers, items, provider_items, progress);
}
Result Client::Patch(const std::string &path, const Headers &headers,
                            const std::string &body,
                            const std::string &content_type,
                            ContentReceiver content_receiver,
                            DownloadProgress progress) {
  return cli_->Patch(path, headers, body, content_type, content_receiver,
                     progress);
}

Result Client::Delete(const std::string &path,
                             DownloadProgress progress) {
  return cli_->Delete(path, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, progress);
}
Result Client::Delete(const std::string &path, const char *body,
                             size_t content_length,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, body, content_length, content_type, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const char *body, size_t content_length,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, body, content_length, content_type,
                      progress);
}
Result Client::Delete(const std::string &path, const std::string &body,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, body, content_type, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const std::string &body,
                             const std::string &content_type,
                             DownloadProgress progress) {
  return cli_->Delete(path, headers, body, content_type, progress);
}
Result Client::Delete(const std::string &path, const Params &params,
                             DownloadProgress progress) {
  return cli_->Delete(path, params, progress);
}
Result Client::Delete(const std::string &path, const Headers &headers,
                             const Params &params, DownloadProgress progress) {
  return cli_->Delete(path, headers, params, progress);
}

Result Client::Options(const std::string &path) {
  return cli_->Options(path);
}
Result Client::Options(const std::string &path, const Headers &headers) {
  return cli_->Options(path, headers);
}

ClientImpl::StreamHandle
Client::open_stream(const std::string &method, const std::string &path,
                    const Params &params, const Headers &headers,
                    const std::string &body, const std::string &content_type) {
  return cli_->open_stream(method, path, params, headers, body, content_type);
}

bool Client::send(Request &req, Response &res, Error &error) {
  return cli_->send(req, res, error);
}

Result Client::send(const Request &req) { return cli_->send(req); }

void Client::stop() { cli_->stop(); }

std::string Client::host() const { return cli_->host(); }

int Client::port() const { return cli_->port(); }

size_t Client::is_socket_open() const { return cli_->is_socket_open(); }

socket_t Client::socket() const { return cli_->socket(); }

void
Client::set_hostname_addr_map(std::map<std::string, std::string> addr_map) {
  cli_->set_hostname_addr_map(std::move(addr_map));
}

void Client::set_default_headers(Headers headers) {
  cli_->set_default_headers(std::move(headers));
}

void Client::set_header_writer(
    std::function<ssize_t(Stream &, Headers &)> const &writer) {
  cli_->set_header_writer(writer);
}

void Client::set_address_family(int family) {
  cli_->set_address_family(family);
}

void Client::set_tcp_nodelay(bool on) { cli_->set_tcp_nodelay(on); }

void Client::set_socket_options(SocketOptions socket_options) {
  cli_->set_socket_options(std::move(socket_options));
}

void Client::set_connection_timeout(time_t sec, time_t usec) {
  cli_->set_connection_timeout(sec, usec);
}

void Client::set_read_timeout(time_t sec, time_t usec) {
  cli_->set_read_timeout(sec, usec);
}

void Client::set_write_timeout(time_t sec, time_t usec) {
  cli_->set_write_timeout(sec, usec);
}

void Client::set_basic_auth(const std::string &username,
                                   const std::string &password) {
  cli_->set_basic_auth(username, password);
}
void Client::set_bearer_token_auth(const std::string &token) {
  cli_->set_bearer_token_auth(token);
}

void Client::set_keep_alive(bool on) { cli_->set_keep_alive(on); }
void Client::set_follow_location(bool on) {
  cli_->set_follow_location(on);
}

void Client::set_path_encode(bool on) { cli_->set_path_encode(on); }

[[deprecated("Use set_path_encode instead")]]
void Client::set_url_encode(bool on) {
  cli_->set_path_encode(on);
}

void Client::set_compress(bool on) { cli_->set_compress(on); }

void Client::set_decompress(bool on) { cli_->set_decompress(on); }

void Client::set_payload_max_length(size_t length) {
  cli_->set_payload_max_length(length);
}

void Client::set_interface(const std::string &intf) {
  cli_->set_interface(intf);
}

void Client::set_proxy(const std::string &host, int port) {
  cli_->set_proxy(host, port);
}
void Client::set_proxy_basic_auth(const std::string &username,
                                         const std::string &password) {
  cli_->set_proxy_basic_auth(username, password);
}
void Client::set_proxy_bearer_token_auth(const std::string &token) {
  cli_->set_proxy_bearer_token_auth(token);
}

void Client::set_logger(Logger logger) {
  cli_->set_logger(std::move(logger));
}

void Client::set_error_logger(ErrorLogger error_logger) {
  cli_->set_error_logger(std::move(error_logger));
}

/*
 * Group 6: SSL Server and Client implementation
 */

#ifdef CPPHTTPLIB_SSL_ENABLED

// SSL HTTP server implementation
SSLServer::SSLServer(const char *cert_path, const char *private_key_path,
                            const char *client_ca_cert_file_path,
                            const char *client_ca_cert_dir_path,
                            const char *private_key_password) {
  using namespace tls;

  ctx_ = create_server_context();
  if (!ctx_) { return; }

  // Load server certificate and private key
  if (!set_server_cert_file(ctx_, cert_path, private_key_path,
                            private_key_password)) {
    last_ssl_error_ = static_cast<int>(get_error());
    free_context(ctx_);
    ctx_ = nullptr;
    return;
  }

  // Load client CA certificates for client authentication
  if (client_ca_cert_file_path || client_ca_cert_dir_path) {
    if (!set_client_ca_file(ctx_, client_ca_cert_file_path,
                            client_ca_cert_dir_path)) {
      last_ssl_error_ = static_cast<int>(get_error());
      free_context(ctx_);
      ctx_ = nullptr;
      return;
    }
    // Enable client certificate verification
    set_verify_client(ctx_, true);
  }
}

SSLServer::SSLServer(const PemMemory &pem) {
  using namespace tls;
  ctx_ = create_server_context();
  if (ctx_) {
    if (!set_server_cert_pem(ctx_, pem.cert_pem, pem.key_pem,
                             pem.private_key_password)) {
      last_ssl_error_ = static_cast<int>(get_error());
      free_context(ctx_);
      ctx_ = nullptr;
    } else if (pem.client_ca_pem && pem.client_ca_pem_len > 0) {
      if (!load_ca_pem(ctx_, pem.client_ca_pem, pem.client_ca_pem_len)) {
        last_ssl_error_ = static_cast<int>(get_error());
        free_context(ctx_);
        ctx_ = nullptr;
      } else {
        set_verify_client(ctx_, true);
      }
    }
  }
}

SSLServer::SSLServer(const tls::ContextSetupCallback &setup_callback) {
  using namespace tls;
  ctx_ = create_server_context();
  if (ctx_) {
    if (!setup_callback(ctx_)) {
      free_context(ctx_);
      ctx_ = nullptr;
    }
  }
}

SSLServer::~SSLServer() {
  if (ctx_) { tls::free_context(ctx_); }
}

bool SSLServer::is_valid() const { return ctx_ != nullptr; }

bool SSLServer::process_and_close_socket(socket_t sock) {
  using namespace tls;

  // Create TLS session with mutex protection
  session_t session = nullptr;
  {
    std::lock_guard<std::mutex> guard(ctx_mutex_);
    session = create_session(static_cast<ctx_t>(ctx_), sock);
  }

  if (!session) {
    last_ssl_error_ = static_cast<int>(get_error());
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
    return false;
  }

  // Use scope_exit to ensure cleanup on all paths (including exceptions)
  bool handshake_done = false;
  bool ret = false;
  bool websocket_upgraded = false;
  auto cleanup = detail::scope_exit([&] {
    if (handshake_done) { shutdown(session, !websocket_upgraded && ret); }
    free_session(session);
    detail::shutdown_socket(sock);
    detail::close_socket(sock);
  });

  // Perform TLS accept handshake with timeout
  TlsError tls_err;
  if (!accept_nonblocking(session, sock, read_timeout_sec_, read_timeout_usec_,
                          &tls_err)) {
#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
    // Map TlsError to legacy ssl_error for backward compatibility
    if (tls_err.code == ErrorCode::WantRead) {
      last_ssl_error_ = SSL_ERROR_WANT_READ;
    } else if (tls_err.code == ErrorCode::WantWrite) {
      last_ssl_error_ = SSL_ERROR_WANT_WRITE;
    } else {
      last_ssl_error_ = SSL_ERROR_SSL;
    }
#else
    last_ssl_error_ = static_cast<int>(get_error());
#endif
    return false;
  }

  handshake_done = true;

  std::string remote_addr;
  int remote_port = 0;
  detail::get_remote_ip_and_port(sock, remote_addr, remote_port);

  std::string local_addr;
  int local_port = 0;
  detail::get_local_ip_and_port(sock, local_addr, local_port);

  ret = detail::process_server_socket_ssl(
      svr_sock_, session, sock, keep_alive_max_count_, keep_alive_timeout_sec_,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_,
      [&](Stream &strm, bool close_connection, bool &connection_closed) {
        return process_request(
            strm, remote_addr, remote_port, local_addr, local_port,
            close_connection, connection_closed,
            [&](Request &req) { req.ssl = session; }, &websocket_upgraded);
      });

  return ret;
}

bool SSLServer::update_certs_pem(const char *cert_pem,
                                        const char *key_pem,
                                        const char *client_ca_pem,
                                        const char *password) {
  if (!ctx_) { return false; }
  std::lock_guard<std::mutex> guard(ctx_mutex_);
  if (!tls::update_server_cert(ctx_, cert_pem, key_pem, password)) {
    return false;
  }
  if (client_ca_pem) {
    return tls::update_server_client_ca(ctx_, client_ca_pem);
  }
  return true;
}

// SSL HTTP client implementation
SSLClient::~SSLClient() {
  if (ctx_) { tls::free_context(ctx_); }
  // Make sure to shut down SSL since shutdown_ssl will resolve to the
  // base function rather than the derived function once we get to the
  // base class destructor, and won't free the SSL (causing a leak).
  shutdown_ssl_impl(socket_, true);
}

bool SSLClient::is_valid() const { return ctx_ != nullptr; }

void SSLClient::shutdown_ssl(Socket &socket, bool shutdown_gracefully) {
  shutdown_ssl_impl(socket, shutdown_gracefully);
}

void SSLClient::shutdown_ssl_impl(Socket &socket,
                                         bool shutdown_gracefully) {
  if (socket.sock == INVALID_SOCKET) {
    assert(socket.ssl == nullptr);
    return;
  }
  if (socket.ssl) {
    tls::shutdown(socket.ssl, shutdown_gracefully);
    {
      std::lock_guard<std::mutex> guard(ctx_mutex_);
      tls::free_session(socket.ssl);
    }
    socket.ssl = nullptr;
  }
  assert(socket.ssl == nullptr);
}

bool SSLClient::process_socket(
    const Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    std::function<bool(Stream &strm)> callback) {
  assert(socket.ssl);
  return detail::process_client_socket_ssl(
      socket.ssl, socket.sock, read_timeout_sec_, read_timeout_usec_,
      write_timeout_sec_, write_timeout_usec_, max_timeout_msec_, start_time,
      std::move(callback));
}

bool SSLClient::is_ssl() const { return true; }

bool SSLClient::create_and_connect_socket(Socket &socket, Error &error) {
  if (!is_valid()) {
    error = Error::SSLConnection;
    return false;
  }
  return ClientImpl::create_and_connect_socket(socket, error);
}

bool SSLClient::setup_proxy_connection(
    Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    Response &res, bool &success, Error &error) {
  if (proxy_host_.empty() || proxy_port_ == -1) { return true; }

  if (!connect_with_proxy(socket, start_time, res, success, error)) {
    return false;
  }

  if (!initialize_ssl(socket, error)) {
    success = false;
    return false;
  }

  return true;
}

// Assumes that socket_mutex_ is locked and that there are no requests in
// flight
bool SSLClient::connect_with_proxy(
    Socket &socket,
    std::chrono::time_point<std::chrono::steady_clock> start_time,
    Response &res, bool &success, Error &error) {
  success = true;
  Response proxy_res;
  if (!detail::process_client_socket(
          socket.sock, read_timeout_sec_, read_timeout_usec_,
          write_timeout_sec_, write_timeout_usec_, max_timeout_msec_,
          start_time, [&](Stream &strm) {
            Request req2;
            req2.method = "CONNECT";
            req2.path =
                detail::make_host_and_port_string_always_port(host_, port_);
            if (max_timeout_msec_ > 0) {
              req2.start_time_ = std::chrono::steady_clock::now();
            }
            return process_request(strm, req2, proxy_res, false, error);
          })) {
    // Thread-safe to close everything because we are assuming there are no
    // requests in flight
    shutdown_ssl(socket, true);
    shutdown_socket(socket);
    close_socket(socket);
    success = false;
    return false;
  }

  if (proxy_res.status == StatusCode::ProxyAuthenticationRequired_407) {
    if (!proxy_digest_auth_username_.empty() &&
        !proxy_digest_auth_password_.empty()) {
      std::map<std::string, std::string> auth;
      if (detail::parse_www_authenticate(proxy_res, auth, true)) {
        // Close the current socket and create a new one for the authenticated
        // request
        shutdown_ssl(socket, true);
        shutdown_socket(socket);
        close_socket(socket);

        // Create a new socket for the authenticated CONNECT request
        if (!ensure_socket_connection(socket, error)) {
          success = false;
          output_error_log(error, nullptr);
          return false;
        }

        proxy_res = Response();
        if (!detail::process_client_socket(
                socket.sock, read_timeout_sec_, read_timeout_usec_,
                write_timeout_sec_, write_timeout_usec_, max_timeout_msec_,
                start_time, [&](Stream &strm) {
                  Request req3;
                  req3.method = "CONNECT";
                  req3.path = detail::make_host_and_port_string_always_port(
                      host_, port_);
                  req3.headers.insert(detail::make_digest_authentication_header(
                      req3, auth, 1, detail::random_string(10),
                      proxy_digest_auth_username_, proxy_digest_auth_password_,
                      true));
                  if (max_timeout_msec_ > 0) {
                    req3.start_time_ = std::chrono::steady_clock::now();
                  }
                  return process_request(strm, req3, proxy_res, false, error);
                })) {
          // Thread-safe to close everything because we are assuming there are
          // no requests in flight
          shutdown_ssl(socket, true);
          shutdown_socket(socket);
          close_socket(socket);
          success = false;
          return false;
        }
      }
    }
  }

  // If status code is not 200, proxy request is failed.
  // Set error to ProxyConnection and return proxy response
  // as the response of the request
  if (proxy_res.status != StatusCode::OK_200) {
    error = Error::ProxyConnection;
    output_error_log(error, nullptr);
    res = std::move(proxy_res);
    // Thread-safe to close everything because we are assuming there are
    // no requests in flight
    shutdown_ssl(socket, true);
    shutdown_socket(socket);
    close_socket(socket);
    return false;
  }

  return true;
}

bool SSLClient::ensure_socket_connection(Socket &socket, Error &error) {
  if (!ClientImpl::ensure_socket_connection(socket, error)) { return false; }

  if (!proxy_host_.empty() && proxy_port_ != -1) { return true; }

  if (!initialize_ssl(socket, error)) {
    shutdown_socket(socket);
    close_socket(socket);
    return false;
  }

  return true;
}

// SSL HTTP client implementation
SSLClient::SSLClient(const std::string &host)
    : SSLClient(host, 443, std::string(), std::string()) {}

SSLClient::SSLClient(const std::string &host, int port)
    : SSLClient(host, port, std::string(), std::string()) {}

SSLClient::SSLClient(const std::string &host, int port,
                            const std::string &client_cert_path,
                            const std::string &client_key_path,
                            const std::string &private_key_password)
    : ClientImpl(host, port, client_cert_path, client_key_path) {
  ctx_ = tls::create_client_context();
  if (!ctx_) { return; }

  tls::set_min_version(ctx_, tls::Version::TLS1_2);

  if (!client_cert_path.empty() && !client_key_path.empty()) {
    const char *password =
        private_key_password.empty() ? nullptr : private_key_password.c_str();
    if (!tls::set_client_cert_file(ctx_, client_cert_path.c_str(),
                                   client_key_path.c_str(), password)) {
      last_backend_error_ = tls::get_error();
      tls::free_context(ctx_);
      ctx_ = nullptr;
    }
  }
}

SSLClient::SSLClient(const std::string &host, int port,
                            const PemMemory &pem)
    : ClientImpl(host, port) {
  ctx_ = tls::create_client_context();
  if (!ctx_) { return; }

  tls::set_min_version(ctx_, tls::Version::TLS1_2);

  if (pem.cert_pem && pem.key_pem) {
    if (!tls::set_client_cert_pem(ctx_, pem.cert_pem, pem.key_pem,
                                  pem.private_key_password)) {
      last_backend_error_ = tls::get_error();
      tls::free_context(ctx_);
      ctx_ = nullptr;
    }
  }
}

void SSLClient::set_ca_cert_store(tls::ca_store_t ca_cert_store) {
  if (ca_cert_store && ctx_) {
    // set_ca_store takes ownership of ca_cert_store
    tls::set_ca_store(ctx_, ca_cert_store);
  } else if (ca_cert_store) {
    tls::free_ca_store(ca_cert_store);
  }
}

void
SSLClient::set_server_certificate_verifier(tls::VerifyCallback verifier) {
  if (!ctx_) { return; }
  tls::set_verify_callback(ctx_, verifier);
}

void SSLClient::set_session_verifier(
    std::function<SSLVerifierResponse(tls::session_t)> verifier) {
  session_verifier_ = std::move(verifier);
}

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
void SSLClient::enable_windows_certificate_verification(bool enabled) {
  enable_windows_cert_verification_ = enabled;
}
#endif

void SSLClient::load_ca_cert_store(const char *ca_cert,
                                          std::size_t size) {
  if (ctx_ && ca_cert && size > 0) {
    ca_cert_pem_.assign(ca_cert, size); // Store for redirect transfer
    tls::load_ca_pem(ctx_, ca_cert, size);
  }
}

bool SSLClient::load_certs() {
  auto ret = true;

  std::call_once(initialize_cert_, [&]() {
    std::lock_guard<std::mutex> guard(ctx_mutex_);

    if (!ca_cert_file_path_.empty()) {
      if (!tls::load_ca_file(ctx_, ca_cert_file_path_.c_str())) {
        last_backend_error_ = tls::get_error();
        ret = false;
      }
    } else if (!ca_cert_dir_path_.empty()) {
      if (!tls::load_ca_dir(ctx_, ca_cert_dir_path_.c_str())) {
        last_backend_error_ = tls::get_error();
        ret = false;
      }
    } else if (ca_cert_pem_.empty()) {
      if (!tls::load_system_certs(ctx_)) {
        last_backend_error_ = tls::get_error();
      }
    }
  });

  return ret;
}

bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
  using namespace tls;

  // Load CA certificates if server verification is enabled
  if (server_certificate_verification_) {
    if (!load_certs()) {
      error = Error::SSLLoadingCerts;
      output_error_log(error, nullptr);
      return false;
    }
  }

  bool is_ip = detail::is_ip_address(host_);

#if defined(CPPHTTPLIB_MBEDTLS_SUPPORT) || defined(CPPHTTPLIB_WOLFSSL_SUPPORT)
  // MbedTLS/wolfSSL need explicit verification mode (OpenSSL uses
  // SSL_VERIFY_NONE by default and performs all verification post-handshake).
  // For IP addresses with verification enabled, use OPTIONAL mode since
  // these backends require hostname for strict verification.
  if (is_ip && server_certificate_verification_) {
    set_verify_client(ctx_, false);
  } else {
    set_verify_client(ctx_, server_certificate_verification_);
  }
#endif

  // Create TLS session
  session_t session = nullptr;
  {
    std::lock_guard<std::mutex> guard(ctx_mutex_);
    session = create_session(ctx_, socket.sock);
  }

  if (!session) {
    error = Error::SSLConnection;
    last_backend_error_ = get_error();
    return false;
  }

  // Use scope_exit to ensure session is freed on error paths
  bool success = false;
  auto session_guard = detail::scope_exit([&] {
    if (!success) { free_session(session); }
  });

  // Set SNI extension (skip for IP addresses per RFC 6066).
  // On MbedTLS, set_sni also enables hostname verification internally.
  // On OpenSSL, set_sni only sets SNI; verification is done post-handshake.
  if (!is_ip) {
    if (!set_sni(session, host_.c_str())) {
      error = Error::SSLConnection;
      last_backend_error_ = get_error();
      return false;
    }
  }

  // Perform non-blocking TLS handshake with timeout
  TlsError tls_err;
  if (!connect_nonblocking(session, socket.sock, connection_timeout_sec_,
                           connection_timeout_usec_, &tls_err)) {
    last_ssl_error_ = static_cast<int>(tls_err.code);
    last_backend_error_ = tls_err.backend_code;
    if (tls_err.code == ErrorCode::CertVerifyFailed) {
      error = Error::SSLServerVerification;
    } else if (tls_err.code == ErrorCode::HostnameMismatch) {
      error = Error::SSLServerHostnameVerification;
    } else {
      error = Error::SSLConnection;
    }
    output_error_log(error, nullptr);
    return false;
  }

  // Post-handshake session verifier callback
  auto verification_status = SSLVerifierResponse::NoDecisionMade;
  if (session_verifier_) { verification_status = session_verifier_(session); }

  if (verification_status == SSLVerifierResponse::CertificateRejected) {
    last_backend_error_ = get_error();
    error = Error::SSLServerVerification;
    output_error_log(error, nullptr);
    return false;
  }

  // Default server certificate verification
  if (verification_status == SSLVerifierResponse::NoDecisionMade &&
      server_certificate_verification_) {
    verify_result_ = tls::get_verify_result(session);
    if (verify_result_ != 0) {
      last_backend_error_ = static_cast<uint64_t>(verify_result_);
      error = Error::SSLServerVerification;
      output_error_log(error, nullptr);
      return false;
    }

    auto server_cert = get_peer_cert(session);
    if (!server_cert) {
      last_backend_error_ = get_error();
      error = Error::SSLServerVerification;
      output_error_log(error, nullptr);
      return false;
    }
    auto cert_guard = detail::scope_exit([&] { free_cert(server_cert); });

    // Hostname verification (post-handshake for all cases).
    // On OpenSSL, verification is always post-handshake (SSL_VERIFY_NONE).
    // On MbedTLS, set_sni already enabled hostname verification during
    // handshake for non-IP hosts, but this check is still needed for IP
    // addresses where SNI is not set.
    if (server_hostname_verification_) {
      if (!verify_hostname(server_cert, host_.c_str())) {
        last_backend_error_ = hostname_mismatch_code();
        error = Error::SSLServerHostnameVerification;
        output_error_log(error, nullptr);
        return false;
      }
    }

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
    // Additional Windows Schannel verification.
    // This provides real-time certificate validation with Windows Update
    // integration, working with both OpenSSL and MbedTLS backends.
    // Skip when a custom CA cert is specified, as the Windows certificate
    // store would not know about user-provided CA certificates.
    if (enable_windows_cert_verification_ && ca_cert_file_path_.empty() &&
        ca_cert_dir_path_.empty() && ca_cert_pem_.empty()) {
      std::vector<unsigned char> der;
      if (get_cert_der(server_cert, der)) {
        uint64_t wincrypt_error = 0;
        if (!detail::verify_cert_with_windows_schannel(
                der, host_, server_hostname_verification_, wincrypt_error)) {
          last_backend_error_ = wincrypt_error;
          error = Error::SSLServerVerification;
          output_error_log(error, nullptr);
          return false;
        }
      }
    }
#endif
  }

  success = true;
  socket.ssl = session;
  return true;
}

void Client::set_digest_auth(const std::string &username,
                                    const std::string &password) {
  cli_->set_digest_auth(username, password);
}

void Client::set_proxy_digest_auth(const std::string &username,
                                          const std::string &password) {
  cli_->set_proxy_digest_auth(username, password);
}

void Client::enable_server_certificate_verification(bool enabled) {
  cli_->enable_server_certificate_verification(enabled);
}

void Client::enable_server_hostname_verification(bool enabled) {
  cli_->enable_server_hostname_verification(enabled);
}

#ifdef CPPHTTPLIB_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
void Client::enable_windows_certificate_verification(bool enabled) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).enable_windows_certificate_verification(
        enabled);
  }
}
#endif

void Client::set_ca_cert_path(const std::string &ca_cert_file_path,
                                     const std::string &ca_cert_dir_path) {
  cli_->set_ca_cert_path(ca_cert_file_path, ca_cert_dir_path);
}

void Client::set_ca_cert_store(tls::ca_store_t ca_cert_store) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_ca_cert_store(ca_cert_store);
  } else if (ca_cert_store) {
    tls::free_ca_store(ca_cert_store);
  }
}

void Client::load_ca_cert_store(const char *ca_cert, std::size_t size) {
  set_ca_cert_store(tls::create_ca_store(ca_cert, size));
}

void
Client::set_server_certificate_verifier(tls::VerifyCallback verifier) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_server_certificate_verifier(
        std::move(verifier));
  }
}

void Client::set_session_verifier(
    std::function<SSLVerifierResponse(tls::session_t)> verifier) {
  if (is_ssl_) {
    static_cast<SSLClient &>(*cli_).set_session_verifier(std::move(verifier));
  }
}

tls::ctx_t Client::tls_context() const {
  if (is_ssl_) { return static_cast<SSLClient &>(*cli_).tls_context(); }
  return nullptr;
}

#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 7: TLS abstraction layer - Common API
 */

#ifdef CPPHTTPLIB_SSL_ENABLED

namespace tls {

// Helper for PeerCert construction
PeerCert get_peer_cert_from_session(const_session_t session) {
  return PeerCert(get_peer_cert(session));
}

namespace impl {

VerifyCallback &get_verify_callback() {
  static thread_local VerifyCallback callback;
  return callback;
}

VerifyCallback &get_mbedtls_verify_callback() {
  static thread_local VerifyCallback callback;
  return callback;
}

// Check if a string is an IPv4 address
bool is_ipv4_address(const std::string &str) {
  int dots = 0;
  for (char c : str) {
    if (c == '.') {
      dots++;
    } else if (!isdigit(static_cast<unsigned char>(c))) {
      return false;
    }
  }
  return dots == 3;
}

// Parse IPv4 address string to bytes
bool parse_ipv4(const std::string &str, unsigned char *out) {
  const char *p = str.c_str();
  for (int i = 0; i < 4; i++) {
    if (i > 0) {
      if (*p != '.') { return false; }
      p++;
    }
    int val = 0;
    int digits = 0;
    while (*p >= '0' && *p <= '9') {
      val = val * 10 + (*p - '0');
      if (val > 255) { return false; }
      p++;
      digits++;
    }
    if (digits == 0) { return false; }
    // Reject leading zeros (e.g., "01.002.03.04") to prevent ambiguity
    if (digits > 1 && *(p - digits) == '0') { return false; }
    out[i] = static_cast<unsigned char>(val);
  }
  return *p == '\0';
}

#ifdef _WIN32
// Enumerate Windows system certificates and call callback with DER data
template <typename Callback>
bool enumerate_windows_system_certs(Callback cb) {
  bool loaded = false;
  static const wchar_t *store_names[] = {L"ROOT", L"CA"};
  for (auto store_name : store_names) {
    HCERTSTORE hStore = CertOpenSystemStoreW(0, store_name);
    if (hStore) {
      PCCERT_CONTEXT pContext = nullptr;
      while ((pContext = CertEnumCertificatesInStore(hStore, pContext)) !=
             nullptr) {
        if (cb(pContext->pbCertEncoded, pContext->cbCertEncoded)) {
          loaded = true;
        }
      }
      CertCloseStore(hStore, 0);
    }
  }
  return loaded;
}
#endif

#ifdef CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN
// Enumerate macOS Keychain certificates and call callback with DER data
template <typename Callback>
bool enumerate_macos_keychain_certs(Callback cb) {
  bool loaded = false;
  CFArrayRef certs = nullptr;
  OSStatus status = SecTrustCopyAnchorCertificates(&certs);
  if (status == errSecSuccess && certs) {
    CFIndex count = CFArrayGetCount(certs);
    for (CFIndex i = 0; i < count; i++) {
      SecCertificateRef cert =
          (SecCertificateRef)CFArrayGetValueAtIndex(certs, i);
      CFDataRef data = SecCertificateCopyData(cert);
      if (data) {
        if (cb(CFDataGetBytePtr(data),
               static_cast<size_t>(CFDataGetLength(data)))) {
          loaded = true;
        }
        CFRelease(data);
      }
    }
    CFRelease(certs);
  }
  return loaded;
}
#endif

#if !defined(_WIN32) && !(defined(__APPLE__) &&                                \
                          defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN))
// Common CA certificate file paths on Linux/Unix
const char **system_ca_paths() {
  static const char *paths[] = {
      "/etc/ssl/certs/ca-certificates.crt", // Debian/Ubuntu
      "/etc/pki/tls/certs/ca-bundle.crt",   // RHEL/CentOS
      "/etc/ssl/ca-bundle.pem",             // OpenSUSE
      "/etc/pki/tls/cacert.pem",            // OpenELEC
      "/etc/ssl/cert.pem",                  // Alpine, FreeBSD
      nullptr};
  return paths;
}

// Common CA certificate directory paths on Linux/Unix
const char **system_ca_dirs() {
  static const char *dirs[] = {"/etc/ssl/certs",             // Debian/Ubuntu
                               "/etc/pki/tls/certs",         // RHEL/CentOS
                               "/usr/share/ca-certificates", // Other
                               nullptr};
  return dirs;
}
#endif

} // namespace impl

bool set_client_ca_file(ctx_t ctx, const char *ca_file,
                               const char *ca_dir) {
  if (!ctx) { return false; }

  bool success = true;
  if (ca_file && *ca_file) {
    if (!load_ca_file(ctx, ca_file)) { success = false; }
  }
  if (ca_dir && *ca_dir) {
    if (!load_ca_dir(ctx, ca_dir)) { success = false; }
  }

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
  // Set CA list for client certificate request (CertificateRequest message)
  if (ca_file && *ca_file) {
    auto list = SSL_load_client_CA_file(ca_file);
    if (list) { SSL_CTX_set_client_CA_list(static_cast<SSL_CTX *>(ctx), list); }
  }
#endif

  return success;
}

bool set_server_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  return set_client_cert_pem(ctx, cert, key, password);
}

bool set_server_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  return set_client_cert_file(ctx, cert_path, key_path, password);
}

// PeerCert implementation
PeerCert::PeerCert() = default;

PeerCert::PeerCert(cert_t cert) : cert_(cert) {}

PeerCert::PeerCert(PeerCert &&other) noexcept : cert_(other.cert_) {
  other.cert_ = nullptr;
}

PeerCert &PeerCert::operator=(PeerCert &&other) noexcept {
  if (this != &other) {
    if (cert_) { free_cert(cert_); }
    cert_ = other.cert_;
    other.cert_ = nullptr;
  }
  return *this;
}

PeerCert::~PeerCert() {
  if (cert_) { free_cert(cert_); }
}

PeerCert::operator bool() const { return cert_ != nullptr; }

std::string PeerCert::subject_cn() const {
  return cert_ ? get_cert_subject_cn(cert_) : std::string();
}

std::string PeerCert::issuer_name() const {
  return cert_ ? get_cert_issuer_name(cert_) : std::string();
}

bool PeerCert::check_hostname(const char *hostname) const {
  return cert_ ? verify_hostname(cert_, hostname) : false;
}

std::vector<SanEntry> PeerCert::sans() const {
  std::vector<SanEntry> result;
  if (cert_) { get_cert_sans(cert_, result); }
  return result;
}

bool PeerCert::validity(time_t &not_before, time_t &not_after) const {
  return cert_ ? get_cert_validity(cert_, not_before, not_after) : false;
}

std::string PeerCert::serial() const {
  return cert_ ? get_cert_serial(cert_) : std::string();
}

// VerifyContext method implementations
std::string VerifyContext::subject_cn() const {
  return cert ? get_cert_subject_cn(cert) : std::string();
}

std::string VerifyContext::issuer_name() const {
  return cert ? get_cert_issuer_name(cert) : std::string();
}

bool VerifyContext::check_hostname(const char *hostname) const {
  return cert ? verify_hostname(cert, hostname) : false;
}

std::vector<SanEntry> VerifyContext::sans() const {
  std::vector<SanEntry> result;
  if (cert) { get_cert_sans(cert, result); }
  return result;
}

bool VerifyContext::validity(time_t &not_before,
                                    time_t &not_after) const {
  return cert ? get_cert_validity(cert, not_before, not_after) : false;
}

std::string VerifyContext::serial() const {
  return cert ? get_cert_serial(cert) : std::string();
}

// TlsError static method implementation
std::string TlsError::verify_error_to_string(long error_code) {
  return verify_error_string(error_code);
}

} // namespace tls

// Request::peer_cert() implementation
tls::PeerCert Request::peer_cert() const {
  return tls::get_peer_cert_from_session(ssl);
}

// Request::sni() implementation
std::string Request::sni() const {
  if (!ssl) { return std::string(); }
  const char *s = tls::get_sni(ssl);
  return s ? std::string(s) : std::string();
}

#endif // CPPHTTPLIB_SSL_ENABLED

/*
 * Group 8: TLS abstraction layer - OpenSSL backend
 */

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
SSL_CTX *Client::ssl_context() const {
  if (is_ssl_) { return static_cast<SSLClient &>(*cli_).ssl_context(); }
  return nullptr;
}

void Client::set_server_certificate_verifier(
    std::function<SSLVerifierResponse(SSL *ssl)> verifier) {
  cli_->set_server_certificate_verifier(verifier);
}

long Client::get_verify_result() const {
  if (is_ssl_) { return static_cast<SSLClient &>(*cli_).get_verify_result(); }
  return -1; // NOTE: -1 doesn't match any of X509_V_ERR_???
}
#endif // CPPHTTPLIB_OPENSSL_SUPPORT

/*
 * OpenSSL Backend Implementation
 */

#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
namespace tls {

namespace impl {

// OpenSSL-specific helpers for converting native types to PEM
std::string x509_to_pem(X509 *cert) {
  if (!cert) return {};
  BIO *bio = BIO_new(BIO_s_mem());
  if (!bio) return {};
  if (PEM_write_bio_X509(bio, cert) != 1) {
    BIO_free(bio);
    return {};
  }
  char *data = nullptr;
  long len = BIO_get_mem_data(bio, &data);
  std::string pem(data, static_cast<size_t>(len));
  BIO_free(bio);
  return pem;
}

std::string evp_pkey_to_pem(EVP_PKEY *key) {
  if (!key) return {};
  BIO *bio = BIO_new(BIO_s_mem());
  if (!bio) return {};
  if (PEM_write_bio_PrivateKey(bio, key, nullptr, nullptr, 0, nullptr,
                               nullptr) != 1) {
    BIO_free(bio);
    return {};
  }
  char *data = nullptr;
  long len = BIO_get_mem_data(bio, &data);
  std::string pem(data, static_cast<size_t>(len));
  BIO_free(bio);
  return pem;
}

std::string x509_store_to_pem(X509_STORE *store) {
  if (!store) return {};
  std::string pem;
  auto objs = X509_STORE_get0_objects(store);
  if (!objs) return {};
  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto cert = X509_OBJECT_get0_X509(obj);
      if (cert) { pem += x509_to_pem(cert); }
    }
  }
  return pem;
}

// Helper to map OpenSSL SSL_get_error to ErrorCode
ErrorCode map_ssl_error(int ssl_error, int &out_errno) {
  switch (ssl_error) {
  case SSL_ERROR_NONE: return ErrorCode::Success;
  case SSL_ERROR_WANT_READ: return ErrorCode::WantRead;
  case SSL_ERROR_WANT_WRITE: return ErrorCode::WantWrite;
  case SSL_ERROR_ZERO_RETURN: return ErrorCode::PeerClosed;
  case SSL_ERROR_SYSCALL: out_errno = errno; return ErrorCode::SyscallError;
  case SSL_ERROR_SSL:
  default: return ErrorCode::Fatal;
  }
}

// Helper: Create client CA list from PEM string
// Returns a new STACK_OF(X509_NAME)* or nullptr on failure
// Caller takes ownership of returned list
STACK_OF(X509_NAME) *
    create_client_ca_list_from_pem(const char *ca_pem) {
  if (!ca_pem) { return nullptr; }

  auto ca_list = sk_X509_NAME_new_null();
  if (!ca_list) { return nullptr; }

  BIO *bio = BIO_new_mem_buf(ca_pem, -1);
  if (!bio) {
    sk_X509_NAME_pop_free(ca_list, X509_NAME_free);
    return nullptr;
  }

  X509 *cert = nullptr;
  while ((cert = PEM_read_bio_X509(bio, nullptr, nullptr, nullptr)) !=
         nullptr) {
    X509_NAME *name = X509_get_subject_name(cert);
    if (name) { sk_X509_NAME_push(ca_list, X509_NAME_dup(name)); }
    X509_free(cert);
  }
  BIO_free(bio);

  return ca_list;
}

// Helper: Extract CA names from X509_STORE
// Returns a new STACK_OF(X509_NAME)* or nullptr on failure
// Caller takes ownership of returned list
STACK_OF(X509_NAME) *
    extract_client_ca_list_from_store(X509_STORE *store) {
  if (!store) { return nullptr; }

  auto ca_list = sk_X509_NAME_new_null();
  if (!ca_list) { return nullptr; }

  auto objs = X509_STORE_get0_objects(store);
  if (!objs) {
    sk_X509_NAME_free(ca_list);
    return nullptr;
  }

  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto cert = X509_OBJECT_get0_X509(obj);
      if (cert) {
        auto subject = X509_get_subject_name(cert);
        if (subject) {
          auto name_dup = X509_NAME_dup(subject);
          if (name_dup) { sk_X509_NAME_push(ca_list, name_dup); }
        }
      }
    }
  }

  if (sk_X509_NAME_num(ca_list) == 0) {
    sk_X509_NAME_free(ca_list);
    return nullptr;
  }

  return ca_list;
}

// OpenSSL verify callback wrapper
int openssl_verify_callback(int preverify_ok, X509_STORE_CTX *ctx) {
  auto &callback = get_verify_callback();
  if (!callback) { return preverify_ok; }

  // Get SSL object from X509_STORE_CTX
  auto ssl = static_cast<SSL *>(
      X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx()));
  if (!ssl) { return preverify_ok; }

  // Get current certificate and depth
  auto cert = X509_STORE_CTX_get_current_cert(ctx);
  int depth = X509_STORE_CTX_get_error_depth(ctx);
  int error = X509_STORE_CTX_get_error(ctx);

  // Build context
  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(ssl);
  verify_ctx.cert = static_cast<cert_t>(cert);
  verify_ctx.depth = depth;
  verify_ctx.preverify_ok = (preverify_ok != 0);
  verify_ctx.error_code = error;
  verify_ctx.error_string =
      (error != X509_V_OK) ? X509_verify_cert_error_string(error) : nullptr;

  return callback(verify_ctx) ? 1 : 0;
}

} // namespace impl

ctx_t create_client_context() {
  SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
  if (ctx) {
    // Disable auto-retry to properly handle non-blocking I/O
    SSL_CTX_clear_mode(ctx, SSL_MODE_AUTO_RETRY);
    // Set minimum TLS version
    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
  }
  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { SSL_CTX_free(static_cast<SSL_CTX *>(ctx)); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) return false;
  return SSL_CTX_set_min_proto_version(static_cast<SSL_CTX *>(ctx),
                                       static_cast<int>(version)) == 1;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem || len == 0) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  auto bio = BIO_new_mem_buf(pem, static_cast<int>(len));
  if (!bio) return false;

  bool ok = true;
  X509 *cert = nullptr;
  while ((cert = PEM_read_bio_X509(bio, nullptr, nullptr, nullptr)) !=
         nullptr) {
    if (X509_STORE_add_cert(store, cert) != 1) {
      // Ignore duplicate errors
      auto err = ERR_peek_last_error();
      if (ERR_GET_REASON(err) != X509_R_CERT_ALREADY_IN_HASH_TABLE) {
        ok = false;
      }
    }
    X509_free(cert);
    if (!ok) break;
  }
  BIO_free(bio);

  // Clear any "no more certificates" errors
  ERR_clear_error();
  return ok;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) return false;
  return SSL_CTX_load_verify_locations(static_cast<SSL_CTX *>(ctx), file_path,
                                       nullptr) == 1;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) return false;
  return SSL_CTX_load_verify_locations(static_cast<SSL_CTX *>(ctx), nullptr,
                                       dir_path) == 1;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) return false;
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

#ifdef _WIN32
  // Windows: Load from system certificate store (ROOT and CA)
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  bool loaded_any = false;
  static const wchar_t *store_names[] = {L"ROOT", L"CA"};
  for (auto store_name : store_names) {
    auto hStore = CertOpenSystemStoreW(NULL, store_name);
    if (!hStore) continue;

    PCCERT_CONTEXT pContext = nullptr;
    while ((pContext = CertEnumCertificatesInStore(hStore, pContext)) !=
           nullptr) {
      const unsigned char *data = pContext->pbCertEncoded;
      auto x509 = d2i_X509(nullptr, &data, pContext->cbCertEncoded);
      if (x509) {
        if (X509_STORE_add_cert(store, x509) == 1) { loaded_any = true; }
        X509_free(x509);
      }
    }
    CertCloseStore(hStore, 0);
  }
  return loaded_any;

#elif defined(__APPLE__)
#ifdef CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN
  // macOS: Load from Keychain
  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) return false;

  CFArrayRef certs = nullptr;
  if (SecTrustCopyAnchorCertificates(&certs) != errSecSuccess || !certs) {
    return SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
  }

  bool loaded_any = false;
  auto count = CFArrayGetCount(certs);
  for (CFIndex i = 0; i < count; i++) {
    auto cert = reinterpret_cast<SecCertificateRef>(
        const_cast<void *>(CFArrayGetValueAtIndex(certs, i)));
    CFDataRef der = SecCertificateCopyData(cert);
    if (der) {
      const unsigned char *data = CFDataGetBytePtr(der);
      auto x509 = d2i_X509(nullptr, &data, CFDataGetLength(der));
      if (x509) {
        if (X509_STORE_add_cert(store, x509) == 1) { loaded_any = true; }
        X509_free(x509);
      }
      CFRelease(der);
    }
  }
  CFRelease(certs);
  return loaded_any || SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#else
  return SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#endif

#else
  // Other Unix: use default verify paths
  return SSL_CTX_set_default_verify_paths(ssl_ctx) == 1;
#endif
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Load certificate
  auto cert_bio = BIO_new_mem_buf(cert, -1);
  if (!cert_bio) return false;

  auto x509 = PEM_read_bio_X509(cert_bio, nullptr, nullptr, nullptr);
  BIO_free(cert_bio);
  if (!x509) return false;

  auto cert_ok = SSL_CTX_use_certificate(ssl_ctx, x509) == 1;
  X509_free(x509);
  if (!cert_ok) return false;

  // Load private key
  auto key_bio = BIO_new_mem_buf(key, -1);
  if (!key_bio) return false;

  auto pkey = PEM_read_bio_PrivateKey(key_bio, nullptr, nullptr,
                                      password ? const_cast<char *>(password)
                                               : nullptr);
  BIO_free(key_bio);
  if (!pkey) return false;

  auto key_ok = SSL_CTX_use_PrivateKey(ssl_ctx, pkey) == 1;
  EVP_PKEY_free(pkey);

  return key_ok && SSL_CTX_check_private_key(ssl_ctx) == 1;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) return false;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  if (password && password[0] != '\0') {
    SSL_CTX_set_default_passwd_cb_userdata(
        ssl_ctx, reinterpret_cast<void *>(const_cast<char *>(password)));
  }

  return SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_path) == 1 &&
         SSL_CTX_use_PrivateKey_file(ssl_ctx, key_path, SSL_FILETYPE_PEM) == 1;
}

ctx_t create_server_context() {
  SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
  if (ctx) {
    SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION |
                                 SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
    SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION);
  }
  return static_cast<ctx_t>(ctx);
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) return;
  SSL_CTX_set_verify(static_cast<SSL_CTX *>(ctx),
                     require
                         ? (SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT)
                         : SSL_VERIFY_NONE,
                     nullptr);
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) return nullptr;

  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  SSL *ssl = SSL_new(ssl_ctx);
  if (!ssl) return nullptr;

  // Disable auto-retry for proper non-blocking I/O handling
  SSL_clear_mode(ssl, SSL_MODE_AUTO_RETRY);

  auto bio = BIO_new_socket(static_cast<int>(sock), BIO_NOCLOSE);
  if (!bio) {
    SSL_free(ssl);
    return nullptr;
  }

  SSL_set_bio(ssl, bio, bio);
  return static_cast<session_t>(ssl);
}

void free_session(session_t session) {
  if (session) { SSL_free(static_cast<SSL *>(session)); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) return false;

  auto ssl = static_cast<SSL *>(session);

  // Set SNI (Server Name Indication) only - does not enable verification
#if defined(OPENSSL_IS_BORINGSSL)
  return SSL_set_tlsext_host_name(ssl, hostname) == 1;
#else
  // Direct call instead of macro to suppress -Wold-style-cast warning
  return SSL_ctrl(ssl, SSL_CTRL_SET_TLSEXT_HOSTNAME, TLSEXT_NAMETYPE_host_name,
                  static_cast<void *>(const_cast<char *>(hostname))) == 1;
#endif
}

bool set_hostname(session_t session, const char *hostname) {
  if (!session || !hostname) return false;

  auto ssl = static_cast<SSL *>(session);

  // Set SNI (Server Name Indication)
  if (!set_sni(session, hostname)) { return false; }

  // Enable hostname verification
  auto param = SSL_get0_param(ssl);
  if (!param) return false;

  X509_VERIFY_PARAM_set_hostflags(param, X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS);
  if (X509_VERIFY_PARAM_set1_host(param, hostname, 0) != 1) { return false; }

  SSL_set_verify(ssl, SSL_VERIFY_PEER, nullptr);
  return true;
}

TlsError connect(session_t session) {
  if (!session) { return TlsError(); }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_connect(ssl);

  TlsError err;
  if (ret == 1) {
    err.code = ErrorCode::Success;
  } else {
    auto ssl_err = SSL_get_error(ssl, ret);
    err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
    err.backend_code = ERR_get_error();
  }
  return err;
}

TlsError accept(session_t session) {
  if (!session) { return TlsError(); }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_accept(ssl);

  TlsError err;
  if (ret == 1) {
    err.code = ErrorCode::Success;
  } else {
    auto ssl_err = SSL_get_error(ssl, ret);
    err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
    err.backend_code = ERR_get_error();
  }
  return err;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto ssl = static_cast<SSL *>(session);
  auto bio = SSL_get_rbio(ssl);

  // Set non-blocking mode for handshake
  detail::set_nonblocking(sock, true);
  if (bio) { BIO_set_nbio(bio, 1); }

  auto cleanup = detail::scope_exit([&]() {
    // Restore blocking mode after handshake
    if (bio) { BIO_set_nbio(bio, 0); }
    detail::set_nonblocking(sock, false);
  });

  auto res = 0;
  while ((res = SSL_connect(ssl)) != 1) {
    auto ssl_err = SSL_get_error(ssl, res);
    switch (ssl_err) {
    case SSL_ERROR_WANT_READ:
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    case SSL_ERROR_WANT_WRITE:
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    default: break;
    }
    if (err) {
      err->code = impl::map_ssl_error(ssl_err, err->sys_errno);
      err->backend_code = ERR_get_error();
    }
    return false;
  }
  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto ssl = static_cast<SSL *>(session);
  auto bio = SSL_get_rbio(ssl);

  // Set non-blocking mode for handshake
  detail::set_nonblocking(sock, true);
  if (bio) { BIO_set_nbio(bio, 1); }

  auto cleanup = detail::scope_exit([&]() {
    // Restore blocking mode after handshake
    if (bio) { BIO_set_nbio(bio, 0); }
    detail::set_nonblocking(sock, false);
  });

  auto res = 0;
  while ((res = SSL_accept(ssl)) != 1) {
    auto ssl_err = SSL_get_error(ssl, res);
    switch (ssl_err) {
    case SSL_ERROR_WANT_READ:
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    case SSL_ERROR_WANT_WRITE:
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
      break;
    default: break;
    }
    if (err) {
      err->code = impl::map_ssl_error(ssl_err, err->sys_errno);
      err->backend_code = ERR_get_error();
    }
    return false;
  }
  if (err) { err->code = ErrorCode::Success; }
  return true;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto ssl = static_cast<SSL *>(session);
  constexpr auto max_len =
      static_cast<size_t>((std::numeric_limits<int>::max)());
  if (len > max_len) { len = max_len; }
  auto ret = SSL_read(ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return ret;
  }

  auto ssl_err = SSL_get_error(ssl, ret);
  err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
  if (err.code == ErrorCode::Fatal) { err.backend_code = ERR_get_error(); }
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto ssl = static_cast<SSL *>(session);
  auto ret = SSL_write(ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return ret;
  }

  auto ssl_err = SSL_get_error(ssl, ret);
  err.code = impl::map_ssl_error(ssl_err, err.sys_errno);
  if (err.code == ErrorCode::Fatal) { err.backend_code = ERR_get_error(); }
  return -1;
}

int pending(const_session_t session) {
  if (!session) return 0;
  return SSL_pending(static_cast<SSL *>(const_cast<void *>(session)));
}

void shutdown(session_t session, bool graceful) {
  if (!session) return;

  auto ssl = static_cast<SSL *>(session);
  if (graceful) {
    // First call sends close_notify
    if (SSL_shutdown(ssl) == 0) {
      // Second call waits for peer's close_notify
      SSL_shutdown(ssl);
    }
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session) return true;

  // Temporarily set socket to non-blocking to avoid blocking on SSL_peek
  detail::set_nonblocking(sock, true);
  auto se = detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  auto ssl = static_cast<SSL *>(session);
  char buf;
  auto ret = SSL_peek(ssl, &buf, 1);
  if (ret > 0) return false;

  auto err = SSL_get_error(ssl, ret);
  return err == SSL_ERROR_ZERO_RETURN;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) return nullptr;
  return static_cast<cert_t>(SSL_get1_peer_certificate(
      static_cast<SSL *>(const_cast<void *>(session))));
}

void free_cert(cert_t cert) {
  if (cert) { X509_free(static_cast<X509 *>(cert)); }
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) return false;

  auto x509 = static_cast<X509 *>(cert);

  // Use X509_check_ip_asc for IP addresses, X509_check_host for DNS names
  if (detail::is_ip_address(hostname)) {
    return X509_check_ip_asc(x509, hostname, 0) == 1;
  }
  return X509_check_host(x509, hostname, strlen(hostname), 0, nullptr) == 1;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(X509_V_ERR_HOSTNAME_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) return X509_V_ERR_UNSPECIFIED;
  return SSL_get_verify_result(static_cast<SSL *>(const_cast<void *>(session)));
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);
  auto subject_name = X509_get_subject_name(x509);
  if (!subject_name) return "";

  char buf[256];
  auto len =
      X509_NAME_get_text_by_NID(subject_name, NID_commonName, buf, sizeof(buf));
  if (len < 0) return "";
  return std::string(buf, static_cast<size_t>(len));
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);
  auto issuer_name = X509_get_issuer_name(x509);
  if (!issuer_name) return "";

  char buf[256];
  X509_NAME_oneline(issuer_name, buf, sizeof(buf));
  return std::string(buf);
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);

  auto names = static_cast<GENERAL_NAMES *>(
      X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));
  if (!names) return true; // No SANs is valid

  auto count = sk_GENERAL_NAME_num(names);
  for (decltype(count) i = 0; i < count; i++) {
    auto gen = sk_GENERAL_NAME_value(names, i);
    if (!gen) continue;

    SanEntry entry;
    switch (gen->type) {
    case GEN_DNS:
      entry.type = SanType::DNS;
      if (gen->d.dNSName) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.dNSName)),
            static_cast<size_t>(ASN1_STRING_length(gen->d.dNSName)));
      }
      break;
    case GEN_IPADD:
      entry.type = SanType::IP;
      if (gen->d.iPAddress) {
        auto data = ASN1_STRING_get0_data(gen->d.iPAddress);
        auto len = ASN1_STRING_length(gen->d.iPAddress);
        if (len == 4) {
          // IPv4
          char buf[INET_ADDRSTRLEN];
          inet_ntop(AF_INET, data, buf, sizeof(buf));
          entry.value = buf;
        } else if (len == 16) {
          // IPv6
          char buf[INET6_ADDRSTRLEN];
          inet_ntop(AF_INET6, data, buf, sizeof(buf));
          entry.value = buf;
        }
      }
      break;
    case GEN_EMAIL:
      entry.type = SanType::EMAIL;
      if (gen->d.rfc822Name) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.rfc822Name)),
            static_cast<size_t>(ASN1_STRING_length(gen->d.rfc822Name)));
      }
      break;
    case GEN_URI:
      entry.type = SanType::URI;
      if (gen->d.uniformResourceIdentifier) {
        entry.value = std::string(
            reinterpret_cast<const char *>(
                ASN1_STRING_get0_data(gen->d.uniformResourceIdentifier)),
            static_cast<size_t>(
                ASN1_STRING_length(gen->d.uniformResourceIdentifier)));
      }
      break;
    default: entry.type = SanType::OTHER; break;
    }

    if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
  }

  GENERAL_NAMES_free(names);
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);

  auto nb = X509_get0_notBefore(x509);
  auto na = X509_get0_notAfter(x509);
  if (!nb || !na) return false;

  ASN1_TIME *epoch = ASN1_TIME_new();
  if (!epoch) return false;
  auto se = detail::scope_exit([&] { ASN1_TIME_free(epoch); });

  if (!ASN1_TIME_set(epoch, 0)) return false;

  int pday, psec;

  if (!ASN1_TIME_diff(&pday, &psec, epoch, nb)) return false;
  not_before = 86400 * (time_t)pday + psec;

  if (!ASN1_TIME_diff(&pday, &psec, epoch, na)) return false;
  not_after = 86400 * (time_t)pday + psec;

  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<X509 *>(cert);

  auto serial = X509_get_serialNumber(x509);
  if (!serial) return "";

  auto bn = ASN1_INTEGER_to_BN(serial, nullptr);
  if (!bn) return "";

  auto hex = BN_bn2hex(bn);
  BN_free(bn);
  if (!hex) return "";

  std::string result(hex);
  OPENSSL_free(hex);
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto x509 = static_cast<X509 *>(cert);
  auto len = i2d_X509(x509, nullptr);
  if (len < 0) return false;
  der.resize(static_cast<size_t>(len));
  auto p = der.data();
  i2d_X509(x509, &p);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto ssl = static_cast<SSL *>(const_cast<void *>(session));
  return SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
}

uint64_t peek_error() { return ERR_peek_last_error(); }

uint64_t get_error() { return ERR_get_error(); }

std::string error_string(uint64_t code) {
  char buf[256];
  ERR_error_string_n(static_cast<unsigned long>(code), buf, sizeof(buf));
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  auto mem = BIO_new_mem_buf(pem, static_cast<int>(len));
  if (!mem) { return nullptr; }
  auto mem_guard = detail::scope_exit([&] { BIO_free_all(mem); });

  auto inf = PEM_X509_INFO_read_bio(mem, nullptr, nullptr, nullptr);
  if (!inf) { return nullptr; }

  auto store = X509_STORE_new();
  if (store) {
    for (auto i = 0; i < static_cast<int>(sk_X509_INFO_num(inf)); i++) {
      auto itmp = sk_X509_INFO_value(inf, i);
      if (!itmp) { continue; }
      if (itmp->x509) { X509_STORE_add_cert(store, itmp->x509); }
      if (itmp->crl) { X509_STORE_add_crl(store, itmp->crl); }
    }
  }

  sk_X509_INFO_pop_free(inf, X509_INFO_free);
  return static_cast<ca_store_t>(store);
}

void free_ca_store(ca_store_t store) {
  if (store) { X509_STORE_free(static_cast<X509_STORE *>(store)); }
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);
  auto x509_store = static_cast<X509_STORE *>(store);

  // Check if same store is already set
  if (SSL_CTX_get_cert_store(ssl_ctx) == x509_store) { return true; }

  // SSL_CTX_set_cert_store takes ownership and frees the old store
  SSL_CTX_set_cert_store(ssl_ctx, x509_store);
  return true;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) { return 0; }

  auto objs = X509_STORE_get0_objects(store);
  if (!objs) { return 0; }

  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (!obj) { continue; }
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto x509 = X509_OBJECT_get0_X509(obj);
      if (x509) {
        // Increment reference count so caller can free it
        X509_up_ref(x509);
        certs.push_back(static_cast<cert_t>(x509));
      }
    }
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  auto store = SSL_CTX_get_cert_store(ssl_ctx);
  if (!store) { return names; }

  auto objs = X509_STORE_get0_objects(store);
  if (!objs) { return names; }

  auto count = sk_X509_OBJECT_num(objs);
  for (decltype(count) i = 0; i < count; i++) {
    auto obj = sk_X509_OBJECT_value(objs, i);
    if (!obj) { continue; }
    if (X509_OBJECT_get_type(obj) == X509_LU_X509) {
      auto x509 = X509_OBJECT_get0_X509(obj);
      if (x509) {
        auto subject = X509_get_subject_name(x509);
        if (subject) {
          char buf[512];
          X509_NAME_oneline(subject, buf, sizeof(buf));
          names.push_back(buf);
        }
      }
    }
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Load certificate from PEM
  auto cert_bio = BIO_new_mem_buf(cert_pem, -1);
  if (!cert_bio) { return false; }
  auto cert = PEM_read_bio_X509(cert_bio, nullptr, nullptr, nullptr);
  BIO_free(cert_bio);
  if (!cert) { return false; }

  // Load private key from PEM
  auto key_bio = BIO_new_mem_buf(key_pem, -1);
  if (!key_bio) {
    X509_free(cert);
    return false;
  }
  auto key = PEM_read_bio_PrivateKey(key_bio, nullptr, nullptr,
                                     password ? const_cast<char *>(password)
                                              : nullptr);
  BIO_free(key_bio);
  if (!key) {
    X509_free(cert);
    return false;
  }

  // Update certificate and key
  auto ret = SSL_CTX_use_certificate(ssl_ctx, cert) == 1 &&
             SSL_CTX_use_PrivateKey(ssl_ctx, key) == 1;

  X509_free(cert);
  EVP_PKEY_free(key);
  return ret;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  // Create new X509_STORE from PEM
  auto store = create_ca_store(ca_pem, strlen(ca_pem));
  if (!store) { return false; }

  // SSL_CTX_set_cert_store takes ownership
  SSL_CTX_set_cert_store(ssl_ctx, static_cast<X509_STORE *>(store));

  // Set client CA list for client certificate request
  auto ca_list = impl::create_client_ca_list_from_pem(ca_pem);
  if (ca_list) {
    // SSL_CTX_set_client_CA_list takes ownership of ca_list
    SSL_CTX_set_client_CA_list(ssl_ctx, ca_list);
  }

  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto ssl_ctx = static_cast<SSL_CTX *>(ctx);

  impl::get_verify_callback() = std::move(callback);

  if (impl::get_verify_callback()) {
    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, impl::openssl_verify_callback);
  } else {
    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto ssl = static_cast<SSL *>(const_cast<void *>(session));
  return SSL_get_verify_result(ssl);
}

std::string verify_error_string(long error_code) {
  if (error_code == X509_V_OK) { return ""; }
  const char *str = X509_verify_cert_error_string(static_cast<int>(error_code));
  return str ? str : "unknown error";
}

namespace impl {

// OpenSSL-specific helpers for public API wrappers
ctx_t create_server_context_from_x509(X509 *cert, EVP_PKEY *key,
                                             X509_STORE *client_ca_store,
                                             int &out_error) {
  out_error = 0;
  auto cert_pem = x509_to_pem(cert);
  auto key_pem = evp_pkey_to_pem(key);
  if (cert_pem.empty() || key_pem.empty()) {
    out_error = static_cast<int>(ERR_get_error());
    return nullptr;
  }

  auto ctx = create_server_context();
  if (!ctx) {
    out_error = static_cast<int>(get_error());
    return nullptr;
  }

  if (!set_server_cert_pem(ctx, cert_pem.c_str(), key_pem.c_str(), nullptr)) {
    out_error = static_cast<int>(get_error());
    free_context(ctx);
    return nullptr;
  }

  if (client_ca_store) {
    // Set cert store for verification (SSL_CTX_set_cert_store takes ownership)
    SSL_CTX_set_cert_store(static_cast<SSL_CTX *>(ctx), client_ca_store);

    // Extract and set client CA list directly from store (more efficient than
    // PEM conversion)
    auto ca_list = extract_client_ca_list_from_store(client_ca_store);
    if (ca_list) {
      SSL_CTX_set_client_CA_list(static_cast<SSL_CTX *>(ctx), ca_list);
    }

    set_verify_client(ctx, true);
  }

  return ctx;
}

void update_server_certs_from_x509(ctx_t ctx, X509 *cert, EVP_PKEY *key,
                                          X509_STORE *client_ca_store) {
  auto cert_pem = x509_to_pem(cert);
  auto key_pem = evp_pkey_to_pem(key);

  if (!cert_pem.empty() && !key_pem.empty()) {
    update_server_cert(ctx, cert_pem.c_str(), key_pem.c_str(), nullptr);
  }

  if (client_ca_store) {
    auto ca_pem = x509_store_to_pem(client_ca_store);
    if (!ca_pem.empty()) { update_server_client_ca(ctx, ca_pem.c_str()); }
    X509_STORE_free(client_ca_store);
  }
}

ctx_t create_client_context_from_x509(X509 *cert, EVP_PKEY *key,
                                             const char *password,
                                             uint64_t &out_error) {
  out_error = 0;
  auto ctx = create_client_context();
  if (!ctx) {
    out_error = get_error();
    return nullptr;
  }

  if (cert && key) {
    auto cert_pem = x509_to_pem(cert);
    auto key_pem = evp_pkey_to_pem(key);
    if (cert_pem.empty() || key_pem.empty()) {
      out_error = ERR_get_error();
      free_context(ctx);
      return nullptr;
    }
    if (!set_client_cert_pem(ctx, cert_pem.c_str(), key_pem.c_str(),
                             password)) {
      out_error = get_error();
      free_context(ctx);
      return nullptr;
    }
  }

  return ctx;
}

} // namespace impl

} // namespace tls

// ClientImpl::set_ca_cert_store - defined here to use
// tls::impl::x509_store_to_pem Deprecated: converts X509_STORE to PEM and
// stores for redirect transfer
void ClientImpl::set_ca_cert_store(X509_STORE *ca_cert_store) {
  if (ca_cert_store) {
    ca_cert_pem_ = tls::impl::x509_store_to_pem(ca_cert_store);
  }
}

SSLServer::SSLServer(X509 *cert, EVP_PKEY *private_key,
                            X509_STORE *client_ca_cert_store) {
  ctx_ = tls::impl::create_server_context_from_x509(
      cert, private_key, client_ca_cert_store, last_ssl_error_);
}

SSLServer::SSLServer(
    const std::function<bool(SSL_CTX &ssl_ctx)> &setup_ssl_ctx_callback) {
  // Use abstract API to create context
  ctx_ = tls::create_server_context();
  if (ctx_) {
    // Pass to OpenSSL-specific callback (ctx_ is SSL_CTX* internally)
    auto ssl_ctx = static_cast<SSL_CTX *>(ctx_);
    if (!setup_ssl_ctx_callback(*ssl_ctx)) {
      tls::free_context(ctx_);
      ctx_ = nullptr;
    }
  }
}

SSL_CTX *SSLServer::ssl_context() const {
  return static_cast<SSL_CTX *>(ctx_);
}

void SSLServer::update_certs(X509 *cert, EVP_PKEY *private_key,
                                    X509_STORE *client_ca_cert_store) {
  std::lock_guard<std::mutex> guard(ctx_mutex_);
  tls::impl::update_server_certs_from_x509(ctx_, cert, private_key,
                                           client_ca_cert_store);
}

SSLClient::SSLClient(const std::string &host, int port,
                            X509 *client_cert, EVP_PKEY *client_key,
                            const std::string &private_key_password)
    : ClientImpl(host, port) {
  const char *password =
      private_key_password.empty() ? nullptr : private_key_password.c_str();
  ctx_ = tls::impl::create_client_context_from_x509(
      client_cert, client_key, password, last_backend_error_);
}

long SSLClient::get_verify_result() const { return verify_result_; }

void SSLClient::set_server_certificate_verifier(
    std::function<SSLVerifierResponse(SSL *ssl)> verifier) {
  // Wrap SSL* callback into backend-independent session_verifier_
  auto v = std::make_shared<std::function<SSLVerifierResponse(SSL *)>>(
      std::move(verifier));
  session_verifier_ = [v](tls::session_t session) {
    return (*v)(static_cast<SSL *>(session));
  };
}

SSL_CTX *SSLClient::ssl_context() const {
  return static_cast<SSL_CTX *>(ctx_);
}

bool SSLClient::verify_host(X509 *server_cert) const {
  /* Quote from RFC2818 section 3.1 "Server Identity"

     If a subjectAltName extension of type dNSName is present, that MUST
     be used as the identity. Otherwise, the (most specific) Common Name
     field in the Subject field of the certificate MUST be used. Although
     the use of the Common Name is existing practice, it is deprecated and
     Certification Authorities are encouraged to use the dNSName instead.

     Matching is performed using the matching rules specified by
     [RFC2459].  If more than one identity of a given type is present in
     the certificate (e.g., more than one dNSName name, a match in any one
     of the set is considered acceptable.) Names may contain the wildcard
     character * which is considered to match any single domain name
     component or component fragment. E.g., *.a.com matches foo.a.com but
     not bar.foo.a.com. f*.com matches foo.com but not bar.com.

     In some cases, the URI is specified as an IP address rather than a
     hostname. In this case, the iPAddress subjectAltName must be present
     in the certificate and must exactly match the IP in the URI.

  */
  return verify_host_with_subject_alt_name(server_cert) ||
         verify_host_with_common_name(server_cert);
}

bool
SSLClient::verify_host_with_subject_alt_name(X509 *server_cert) const {
  auto ret = false;

  auto type = GEN_DNS;

  struct in6_addr addr6 = {};
  struct in_addr addr = {};
  size_t addr_len = 0;

#ifndef __MINGW32__
  if (inet_pton(AF_INET6, host_.c_str(), &addr6)) {
    type = GEN_IPADD;
    addr_len = sizeof(struct in6_addr);
  } else if (inet_pton(AF_INET, host_.c_str(), &addr)) {
    type = GEN_IPADD;
    addr_len = sizeof(struct in_addr);
  }
#endif

  auto alt_names = static_cast<const struct stack_st_GENERAL_NAME *>(
      X509_get_ext_d2i(server_cert, NID_subject_alt_name, nullptr, nullptr));

  if (alt_names) {
    auto dsn_matched = false;
    auto ip_matched = false;

    auto count = sk_GENERAL_NAME_num(alt_names);

    for (decltype(count) i = 0; i < count && !dsn_matched; i++) {
      auto val = sk_GENERAL_NAME_value(alt_names, i);
      if (!val || val->type != type) { continue; }

      auto name =
          reinterpret_cast<const char *>(ASN1_STRING_get0_data(val->d.ia5));
      if (name == nullptr) { continue; }

      auto name_len = static_cast<size_t>(ASN1_STRING_length(val->d.ia5));

      switch (type) {
      case GEN_DNS:
        dsn_matched =
            detail::match_hostname(std::string(name, name_len), host_);
        break;

      case GEN_IPADD:
        if (!memcmp(&addr6, name, addr_len) || !memcmp(&addr, name, addr_len)) {
          ip_matched = true;
        }
        break;
      }
    }

    if (dsn_matched || ip_matched) { ret = true; }
  }

  GENERAL_NAMES_free(const_cast<STACK_OF(GENERAL_NAME) *>(
      reinterpret_cast<const STACK_OF(GENERAL_NAME) *>(alt_names)));
  return ret;
}

bool SSLClient::verify_host_with_common_name(X509 *server_cert) const {
  const auto subject_name = X509_get_subject_name(server_cert);

  if (subject_name != nullptr) {
    char name[BUFSIZ];
    auto name_len = X509_NAME_get_text_by_NID(subject_name, NID_commonName,
                                              name, sizeof(name));

    if (name_len != -1) {
      return detail::match_hostname(
          std::string(name, static_cast<size_t>(name_len)), host_);
    }
  }

  return false;
}

#endif // CPPHTTPLIB_OPENSSL_SUPPORT

/*
 * Group 9: TLS abstraction layer - Mbed TLS backend
 */

/*
 * Mbed TLS Backend Implementation
 */

#ifdef CPPHTTPLIB_MBEDTLS_SUPPORT
namespace tls {

namespace impl {

// Mbed TLS session wrapper
struct MbedTlsSession {
  mbedtls_ssl_context ssl;
  socket_t sock = INVALID_SOCKET;
  std::string hostname;     // For client: set via set_sni
  std::string sni_hostname; // For server: received from client via SNI callback

  MbedTlsSession() { mbedtls_ssl_init(&ssl); }

  ~MbedTlsSession() { mbedtls_ssl_free(&ssl); }

  MbedTlsSession(const MbedTlsSession &) = delete;
  MbedTlsSession &operator=(const MbedTlsSession &) = delete;
};

// Thread-local error code accessor for Mbed TLS (since it doesn't have an error
// queue)
int &mbedtls_last_error() {
  static thread_local int err = 0;
  return err;
}

// Helper to map Mbed TLS error to ErrorCode
ErrorCode map_mbedtls_error(int ret, int &out_errno) {
  if (ret == 0) { return ErrorCode::Success; }
  if (ret == MBEDTLS_ERR_SSL_WANT_READ) { return ErrorCode::WantRead; }
  if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) { return ErrorCode::WantWrite; }
  if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
    return ErrorCode::PeerClosed;
  }
  if (ret == MBEDTLS_ERR_NET_CONN_RESET || ret == MBEDTLS_ERR_NET_SEND_FAILED ||
      ret == MBEDTLS_ERR_NET_RECV_FAILED) {
    out_errno = errno;
    return ErrorCode::SyscallError;
  }
  if (ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED) {
    return ErrorCode::CertVerifyFailed;
  }
  return ErrorCode::Fatal;
}

// BIO-like send callback for Mbed TLS
int mbedtls_net_send_cb(void *ctx, const unsigned char *buf,
                               size_t len) {
  auto sock = *static_cast<socket_t *>(ctx);
#ifdef _WIN32
  auto ret =
      send(sock, reinterpret_cast<const char *>(buf), static_cast<int>(len), 0);
  if (ret == SOCKET_ERROR) {
    int err = WSAGetLastError();
    if (err == WSAEWOULDBLOCK) { return MBEDTLS_ERR_SSL_WANT_WRITE; }
    return MBEDTLS_ERR_NET_SEND_FAILED;
  }
#else
  auto ret = send(sock, buf, len, 0);
  if (ret < 0) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) {
      return MBEDTLS_ERR_SSL_WANT_WRITE;
    }
    return MBEDTLS_ERR_NET_SEND_FAILED;
  }
#endif
  return static_cast<int>(ret);
}

// BIO-like recv callback for Mbed TLS
int mbedtls_net_recv_cb(void *ctx, unsigned char *buf, size_t len) {
  auto sock = *static_cast<socket_t *>(ctx);
#ifdef _WIN32
  auto ret =
      recv(sock, reinterpret_cast<char *>(buf), static_cast<int>(len), 0);
  if (ret == SOCKET_ERROR) {
    int err = WSAGetLastError();
    if (err == WSAEWOULDBLOCK) { return MBEDTLS_ERR_SSL_WANT_READ; }
    return MBEDTLS_ERR_NET_RECV_FAILED;
  }
#else
  auto ret = recv(sock, buf, len, 0);
  if (ret < 0) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) {
      return MBEDTLS_ERR_SSL_WANT_READ;
    }
    return MBEDTLS_ERR_NET_RECV_FAILED;
  }
#endif
  if (ret == 0) { return MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY; }
  return static_cast<int>(ret);
}

// MbedTlsContext constructor/destructor implementations
MbedTlsContext::MbedTlsContext() {
  mbedtls_ssl_config_init(&conf);
  mbedtls_entropy_init(&entropy);
  mbedtls_ctr_drbg_init(&ctr_drbg);
  mbedtls_x509_crt_init(&ca_chain);
  mbedtls_x509_crt_init(&own_cert);
  mbedtls_pk_init(&own_key);
}

MbedTlsContext::~MbedTlsContext() {
  mbedtls_pk_free(&own_key);
  mbedtls_x509_crt_free(&own_cert);
  mbedtls_x509_crt_free(&ca_chain);
  mbedtls_ctr_drbg_free(&ctr_drbg);
  mbedtls_entropy_free(&entropy);
  mbedtls_ssl_config_free(&conf);
}

// Thread-local storage for SNI captured during handshake
// This is needed because the SNI callback doesn't have a way to pass
// session-specific data before the session is fully set up
std::string &mbedpending_sni() {
  static thread_local std::string sni;
  return sni;
}

// SNI callback for Mbed TLS server to capture client's SNI hostname
int mbedtls_sni_callback(void *p_ctx, mbedtls_ssl_context *ssl,
                                const unsigned char *name, size_t name_len) {
  (void)p_ctx;
  (void)ssl;

  // Store SNI name in thread-local storage
  // It will be retrieved and stored in the session after handshake
  if (name && name_len > 0) {
    mbedpending_sni().assign(reinterpret_cast<const char *>(name), name_len);
  } else {
    mbedpending_sni().clear();
  }
  return 0; // Accept any SNI
}

int mbedtls_verify_callback(void *data, mbedtls_x509_crt *crt,
                                   int cert_depth, uint32_t *flags);

// MbedTLS verify callback wrapper
int mbedtls_verify_callback(void *data, mbedtls_x509_crt *crt,
                                   int cert_depth, uint32_t *flags) {
  auto &callback = get_verify_callback();
  if (!callback) { return 0; } // Continue with default verification

  // data points to the MbedTlsSession
  auto *session = static_cast<MbedTlsSession *>(data);

  // Build context
  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(session);
  verify_ctx.cert = static_cast<cert_t>(crt);
  verify_ctx.depth = cert_depth;
  verify_ctx.preverify_ok = (*flags == 0);
  verify_ctx.error_code = static_cast<long>(*flags);

  // Convert Mbed TLS flags to error string
  static thread_local char error_buf[256];
  if (*flags != 0) {
    mbedtls_x509_crt_verify_info(error_buf, sizeof(error_buf), "", *flags);
    verify_ctx.error_string = error_buf;
  } else {
    verify_ctx.error_string = nullptr;
  }

  bool accepted = callback(verify_ctx);

  if (accepted) {
    *flags = 0; // Clear all error flags
    return 0;
  }
  return MBEDTLS_ERR_X509_CERT_VERIFY_FAILED;
}

} // namespace impl

ctx_t create_client_context() {
  auto ctx = new (std::nothrow) impl::MbedTlsContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = false;

  // Seed the random number generator
  const char *pers = "httplib_client";
  int ret = mbedtls_ctr_drbg_seed(
      &ctx->ctr_drbg, mbedtls_entropy_func, &ctx->entropy,
      reinterpret_cast<const unsigned char *>(pers), strlen(pers));
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

  // Set up SSL config for client
  ret = mbedtls_ssl_config_defaults(&ctx->conf, MBEDTLS_SSL_IS_CLIENT,
                                    MBEDTLS_SSL_TRANSPORT_STREAM,
                                    MBEDTLS_SSL_PRESET_DEFAULT);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

  // Set random number generator
  mbedtls_ssl_conf_rng(&ctx->conf, mbedtls_ctr_drbg_random, &ctx->ctr_drbg);

  // Default: verify peer certificate
  mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_REQUIRED);

  // Set minimum TLS version to 1.2
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_ssl_conf_min_tls_version(&ctx->conf, MBEDTLS_SSL_VERSION_TLS1_2);
#else
  mbedtls_ssl_conf_min_version(&ctx->conf, MBEDTLS_SSL_MAJOR_VERSION_3,
                               MBEDTLS_SSL_MINOR_VERSION_3);
#endif

  return static_cast<ctx_t>(ctx);
}

ctx_t create_server_context() {
  auto ctx = new (std::nothrow) impl::MbedTlsContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = true;

  // Seed the random number generator
  const char *pers = "httplib_server";
  int ret = mbedtls_ctr_drbg_seed(
      &ctx->ctr_drbg, mbedtls_entropy_func, &ctx->entropy,
      reinterpret_cast<const unsigned char *>(pers), strlen(pers));
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

  // Set up SSL config for server
  ret = mbedtls_ssl_config_defaults(&ctx->conf, MBEDTLS_SSL_IS_SERVER,
                                    MBEDTLS_SSL_TRANSPORT_STREAM,
                                    MBEDTLS_SSL_PRESET_DEFAULT);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete ctx;
    return nullptr;
  }

  // Set random number generator
  mbedtls_ssl_conf_rng(&ctx->conf, mbedtls_ctr_drbg_random, &ctx->ctr_drbg);

  // Default: don't verify client
  mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_NONE);

  // Set minimum TLS version to 1.2
#ifdef CPPHTTPLIB_MBEDTLS_V3
  mbedtls_ssl_conf_min_tls_version(&ctx->conf, MBEDTLS_SSL_VERSION_TLS1_2);
#else
  mbedtls_ssl_conf_min_version(&ctx->conf, MBEDTLS_SSL_MAJOR_VERSION_3,
                               MBEDTLS_SSL_MINOR_VERSION_3);
#endif

  // Set SNI callback to capture client's SNI hostname
  mbedtls_ssl_conf_sni(&ctx->conf, impl::mbedtls_sni_callback, nullptr);

  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { delete static_cast<impl::MbedTlsContext *>(ctx); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

#ifdef CPPHTTPLIB_MBEDTLS_V3
  // Mbed TLS 3.x uses mbedtls_ssl_protocol_version enum
  mbedtls_ssl_protocol_version min_ver = MBEDTLS_SSL_VERSION_TLS1_2;
  if (version >= Version::TLS1_3) {
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    min_ver = MBEDTLS_SSL_VERSION_TLS1_3;
#endif
  }
  mbedtls_ssl_conf_min_tls_version(&mctx->conf, min_ver);
#else
  // Mbed TLS 2.x uses major/minor version numbers
  int major = MBEDTLS_SSL_MAJOR_VERSION_3;
  int minor = MBEDTLS_SSL_MINOR_VERSION_3; // TLS 1.2
  if (version >= Version::TLS1_3) {
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    minor = MBEDTLS_SSL_MINOR_VERSION_4; // TLS 1.3
#else
    minor = MBEDTLS_SSL_MINOR_VERSION_3; // Fall back to TLS 1.2
#endif
  }
  mbedtls_ssl_conf_min_version(&mctx->conf, major, minor);
#endif
  return true;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // mbedtls_x509_crt_parse expects null-terminated string for PEM
  // Add null terminator if not present
  std::string pem_str(pem, len);
  int ret = mbedtls_x509_crt_parse(
      &mctx->ca_chain, reinterpret_cast<const unsigned char *>(pem_str.c_str()),
      pem_str.size() + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  int ret = mbedtls_x509_crt_parse_file(&mctx->ca_chain, file_path);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  int ret = mbedtls_x509_crt_parse_path(&mctx->ca_chain, dir_path);
  if (ret < 0) { // Returns number of certs on success, negative on error
    impl::mbedtls_last_error() = ret;
    return false;
  }

  mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  return true;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);
  bool loaded = false;

#ifdef _WIN32
  loaded = impl::enumerate_windows_system_certs(
      [&](const unsigned char *data, size_t len) {
        return mbedtls_x509_crt_parse_der(&mctx->ca_chain, data, len) == 0;
      });
#elif defined(__APPLE__) && defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN)
  loaded = impl::enumerate_macos_keychain_certs(
      [&](const unsigned char *data, size_t len) {
        return mbedtls_x509_crt_parse_der(&mctx->ca_chain, data, len) == 0;
      });
#else
  for (auto path = impl::system_ca_paths(); *path; ++path) {
    if (mbedtls_x509_crt_parse_file(&mctx->ca_chain, *path) >= 0) {
      loaded = true;
      break;
    }
  }

  if (!loaded) {
    for (auto dir = impl::system_ca_dirs(); *dir; ++dir) {
      if (mbedtls_x509_crt_parse_path(&mctx->ca_chain, *dir) >= 0) {
        loaded = true;
        break;
      }
    }
  }
#endif

  if (loaded) {
    mbedtls_ssl_conf_ca_chain(&mctx->conf, &mctx->ca_chain, nullptr);
  }
  return loaded;
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Parse certificate
  std::string cert_str(cert);
  int ret = mbedtls_x509_crt_parse(
      &mctx->own_cert,
      reinterpret_cast<const unsigned char *>(cert_str.c_str()),
      cert_str.size() + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key
  std::string key_str(key);
  const unsigned char *pwd =
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr;
  size_t pwd_len = password ? strlen(password) : 0;

#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_parse_key(
      &mctx->own_key, reinterpret_cast<const unsigned char *>(key_str.c_str()),
      key_str.size() + 1, pwd, pwd_len, mbedtls_ctr_drbg_random,
      &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_key(
      &mctx->own_key, reinterpret_cast<const unsigned char *>(key_str.c_str()),
      key_str.size() + 1, pwd, pwd_len);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Verify that the certificate and private key match
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key,
                              mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  ret = mbedtls_ssl_conf_own_cert(&mctx->conf, &mctx->own_cert, &mctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) { return false; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Parse certificate file
  int ret = mbedtls_x509_crt_parse_file(&mctx->own_cert, cert_path);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key file
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_parse_keyfile(&mctx->own_key, key_path, password,
                                 mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_keyfile(&mctx->own_key, key_path, password);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Verify that the certificate and private key match
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key,
                              mbedtls_ctr_drbg_random, &mctx->ctr_drbg);
#else
  ret = mbedtls_pk_check_pair(&mctx->own_cert.pk, &mctx->own_key);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  ret = mbedtls_ssl_conf_own_cert(&mctx->conf, &mctx->own_cert, &mctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) { return; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);
  mctx->verify_client = require;
  if (require) {
    mbedtls_ssl_conf_authmode(&mctx->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
  } else {
    // If a verify callback is set, use OPTIONAL mode to ensure the callback
    // is called (matching OpenSSL behavior). Otherwise use NONE.
    mbedtls_ssl_conf_authmode(&mctx->conf, mctx->has_verify_callback
                                               ? MBEDTLS_SSL_VERIFY_OPTIONAL
                                               : MBEDTLS_SSL_VERIFY_NONE);
  }
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) { return nullptr; }
  auto mctx = static_cast<impl::MbedTlsContext *>(ctx);

  auto session = new (std::nothrow) impl::MbedTlsSession();
  if (!session) { return nullptr; }

  session->sock = sock;

  int ret = mbedtls_ssl_setup(&session->ssl, &mctx->conf);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    delete session;
    return nullptr;
  }

  // Set BIO callbacks
  mbedtls_ssl_set_bio(&session->ssl, &session->sock, impl::mbedtls_net_send_cb,
                      impl::mbedtls_net_recv_cb, nullptr);

  // Set per-session verify callback with session pointer if callback is
  // registered
  if (mctx->has_verify_callback) {
    mbedtls_ssl_set_verify(&session->ssl, impl::mbedtls_verify_callback,
                           session);
  }

  return static_cast<session_t>(session);
}

void free_session(session_t session) {
  if (session) { delete static_cast<impl::MbedTlsSession *>(session); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) { return false; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  int ret = mbedtls_ssl_set_hostname(&msession->ssl, hostname);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  msession->hostname = hostname;
  return true;
}

bool set_hostname(session_t session, const char *hostname) {
  // In Mbed TLS, set_hostname also sets up hostname verification
  return set_sni(session, hostname);
}

TlsError connect(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);
  int ret = mbedtls_ssl_handshake(&msession->ssl);

  if (ret == 0) {
    err.code = ErrorCode::Success;
  } else {
    err.code = impl::map_mbedtls_error(ret, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(-ret);
    impl::mbedtls_last_error() = ret;
  }

  return err;
}

TlsError accept(session_t session) {
  // Same as connect for Mbed TLS - handshake works for both client and server
  auto result = connect(session);

  // After successful handshake, capture SNI from thread-local storage
  if (result.code == ErrorCode::Success && session) {
    auto msession = static_cast<impl::MbedTlsSession *>(session);
    msession->sni_hostname = std::move(impl::mbedpending_sni());
    impl::mbedpending_sni().clear();
  }

  return result;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = mbedtls_ssl_handshake(&msession->ssl)) != 0) {
    if (ret == MBEDTLS_ERR_SSL_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // TlsError or timeout
    if (err) {
      err->code = impl::map_mbedtls_error(ret, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(-ret);
    }
    impl::mbedtls_last_error() = ret;
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  // Same implementation as connect for Mbed TLS
  bool result =
      connect_nonblocking(session, sock, timeout_sec, timeout_usec, err);

  // After successful handshake, capture SNI from thread-local storage
  if (result && session) {
    auto msession = static_cast<impl::MbedTlsSession *>(session);
    msession->sni_hostname = std::move(impl::mbedpending_sni());
    impl::mbedpending_sni().clear();
  }

  return result;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);
  int ret =
      mbedtls_ssl_read(&msession->ssl, static_cast<unsigned char *>(buf), len);

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  err.code = impl::map_mbedtls_error(ret, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(-ret);
  impl::mbedtls_last_error() = ret;
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto msession = static_cast<impl::MbedTlsSession *>(session);
  int ret = mbedtls_ssl_write(&msession->ssl,
                              static_cast<const unsigned char *>(buf), len);

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  err.code = impl::map_mbedtls_error(ret, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(-ret);
  impl::mbedtls_last_error() = ret;
  return -1;
}

int pending(const_session_t session) {
  if (!session) { return 0; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  return static_cast<int>(mbedtls_ssl_get_bytes_avail(&msession->ssl));
}

void shutdown(session_t session, bool graceful) {
  if (!session) { return; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  if (graceful) {
    // Try to send close_notify, but don't block forever
    int ret;
    int attempts = 0;
    while ((ret = mbedtls_ssl_close_notify(&msession->ssl)) != 0 &&
           attempts < 3) {
      if (ret != MBEDTLS_ERR_SSL_WANT_READ &&
          ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
        break;
      }
      attempts++;
    }
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session || sock == INVALID_SOCKET) { return true; }
  auto msession = static_cast<impl::MbedTlsSession *>(session);

  // Check if there's already decrypted data available in the TLS buffer
  // If so, the connection is definitely alive
  if (mbedtls_ssl_get_bytes_avail(&msession->ssl) > 0) { return false; }

  // Set socket to non-blocking to avoid blocking on read
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  // Try a 1-byte read to check connection status
  // Note: This will consume the byte if data is available, but for the
  // purpose of checking if peer is closed, this should be acceptable
  // since we're only called when we expect the connection might be closing
  unsigned char buf;
  int ret = mbedtls_ssl_read(&msession->ssl, &buf, 1);

  // If we got data or WANT_READ (would block), connection is alive
  if (ret > 0 || ret == MBEDTLS_ERR_SSL_WANT_READ) { return false; }

  // If we get a peer close notify or a connection reset, the peer is closed
  return ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY ||
         ret == MBEDTLS_ERR_NET_CONN_RESET || ret == 0;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) { return nullptr; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));

  // Mbed TLS returns a pointer to the internal peer cert chain.
  // WARNING: This pointer is only valid while the session is active.
  // Do not use the certificate after calling free_session().
  const mbedtls_x509_crt *cert = mbedtls_ssl_get_peer_cert(&msession->ssl);
  return const_cast<mbedtls_x509_crt *>(cert);
}

void free_cert(cert_t cert) {
  // Mbed TLS: peer certificate is owned by the SSL context.
  // No-op here, but callers should still call this for cross-backend
  // portability.
  (void)cert;
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) { return false; }
  auto mcert = static_cast<const mbedtls_x509_crt *>(cert);
  std::string host_str(hostname);

  // Check if hostname is an IP address
  bool is_ip = impl::is_ipv4_address(host_str);
  unsigned char ip_bytes[4];
  if (is_ip) { impl::parse_ipv4(host_str, ip_bytes); }

  // Check Subject Alternative Names (SAN)
  // In Mbed TLS 3.x, subject_alt_names contains raw values without ASN.1 tags
  // - DNS names: raw string bytes
  // - IP addresses: raw IP bytes (4 for IPv4, 16 for IPv6)
  const mbedtls_x509_sequence *san = &mcert->subject_alt_names;
  while (san != nullptr && san->buf.p != nullptr && san->buf.len > 0) {
    const unsigned char *p = san->buf.p;
    size_t len = san->buf.len;

    if (is_ip) {
      // Check if this SAN is an IPv4 address (4 bytes)
      if (len == 4 && memcmp(p, ip_bytes, 4) == 0) { return true; }
      // Check if this SAN is an IPv6 address (16 bytes) - skip for now
    } else {
      // Check if this SAN is a DNS name (printable ASCII string)
      bool is_dns = len > 0;
      for (size_t i = 0; i < len && is_dns; i++) {
        if (p[i] < 32 || p[i] > 126) { is_dns = false; }
      }
      if (is_dns) {
        std::string san_name(reinterpret_cast<const char *>(p), len);
        if (detail::match_hostname(san_name, host_str)) { return true; }
      }
    }
    san = san->next;
  }

  // Fallback: Check Common Name (CN) in subject
  char cn[256];
  int ret = mbedtls_x509_dn_gets(cn, sizeof(cn), &mcert->subject);
  if (ret > 0) {
    std::string cn_str(cn);

    // Look for "CN=" in the DN string
    size_t cn_pos = cn_str.find("CN=");
    if (cn_pos != std::string::npos) {
      size_t start = cn_pos + 3;
      size_t end = cn_str.find(',', start);
      std::string cn_value =
          cn_str.substr(start, end == std::string::npos ? end : end - start);

      if (detail::match_hostname(cn_value, host_str)) { return true; }
    }
  }

  return false;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(MBEDTLS_X509_BADCERT_CN_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) { return -1; }
  auto msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  uint32_t flags = mbedtls_ssl_get_verify_result(&msession->ssl);
  // Return 0 (X509_V_OK equivalent) if verification passed
  return flags == 0 ? 0 : static_cast<long>(flags);
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Find the CN in the subject
  const mbedtls_x509_name *name = &x509->subject;
  while (name != nullptr) {
    if (MBEDTLS_OID_CMP(MBEDTLS_OID_AT_CN, &name->oid) == 0) {
      return std::string(reinterpret_cast<const char *>(name->val.p),
                         name->val.len);
    }
    name = name->next;
  }
  return "";
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Build a human-readable issuer name string
  char buf[512];
  int ret = mbedtls_x509_dn_gets(buf, sizeof(buf), &x509->issuer);
  if (ret < 0) return "";
  return std::string(buf);
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Parse the Subject Alternative Name extension
  const mbedtls_x509_sequence *cur = &x509->subject_alt_names;
  while (cur != nullptr) {
    if (cur->buf.len > 0) {
      // Mbed TLS stores SAN as ASN.1 sequences
      // The tag byte indicates the type
      const unsigned char *p = cur->buf.p;
      size_t len = cur->buf.len;

      // First byte is the tag
      unsigned char tag = *p;
      p++;
      len--;

      // Parse length (simple single-byte length assumed)
      if (len > 0 && *p < 0x80) {
        size_t value_len = *p;
        p++;
        len--;

        if (value_len <= len) {
          SanEntry entry;
          // ASN.1 context tags for GeneralName
          switch (tag & 0x1F) {
          case 2: // dNSName
            entry.type = SanType::DNS;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          case 7: // iPAddress
            entry.type = SanType::IP;
            if (value_len == 4) {
              // IPv4
              char buf[16];
              snprintf(buf, sizeof(buf), "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
              entry.value = buf;
            } else if (value_len == 16) {
              // IPv6
              char buf[64];
              snprintf(buf, sizeof(buf),
                       "%02x%02x:%02x%02x:%02x%02x:%02x%02x:"
                       "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                       p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], p[8],
                       p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
              entry.value = buf;
            }
            break;
          case 1: // rfc822Name (email)
            entry.type = SanType::EMAIL;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          case 6: // uniformResourceIdentifier
            entry.type = SanType::URI;
            entry.value =
                std::string(reinterpret_cast<const char *>(p), value_len);
            break;
          default: entry.type = SanType::OTHER; break;
          }

          if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
        }
      }
    }
    cur = cur->next;
  }
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Convert mbedtls_x509_time to time_t
  auto to_time_t = [](const mbedtls_x509_time &t) -> time_t {
    struct tm tm_time = {};
    tm_time.tm_year = t.year - 1900;
    tm_time.tm_mon = t.mon - 1;
    tm_time.tm_mday = t.day;
    tm_time.tm_hour = t.hour;
    tm_time.tm_min = t.min;
    tm_time.tm_sec = t.sec;
#ifdef _WIN32
    return _mkgmtime(&tm_time);
#else
    return timegm(&tm_time);
#endif
  };

  not_before = to_time_t(x509->valid_from);
  not_after = to_time_t(x509->valid_to);
  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<mbedtls_x509_crt *>(cert);

  // Convert serial number to hex string
  std::string result;
  result.reserve(x509->serial.len * 2);
  for (size_t i = 0; i < x509->serial.len; i++) {
    char hex[3];
    snprintf(hex, sizeof(hex), "%02X", x509->serial.p[i]);
    result += hex;
  }
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto crt = static_cast<mbedtls_x509_crt *>(cert);
  if (!crt->raw.p || crt->raw.len == 0) return false;
  der.assign(crt->raw.p, crt->raw.p + crt->raw.len);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto msession = static_cast<const impl::MbedTlsSession *>(session);

  // For server: return SNI received from client during handshake
  if (!msession->sni_hostname.empty()) {
    return msession->sni_hostname.c_str();
  }

  // For client: return the hostname set via set_sni
  if (!msession->hostname.empty()) { return msession->hostname.c_str(); }

  return nullptr;
}

uint64_t peek_error() {
  // Mbed TLS doesn't have an error queue, return the last error
  return static_cast<uint64_t>(-impl::mbedtls_last_error());
}

uint64_t get_error() {
  // Mbed TLS doesn't have an error queue, return and clear the last error
  uint64_t err = static_cast<uint64_t>(-impl::mbedtls_last_error());
  impl::mbedtls_last_error() = 0;
  return err;
}

std::string error_string(uint64_t code) {
  char buf[256];
  mbedtls_strerror(-static_cast<int>(code), buf, sizeof(buf));
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  auto *ca_chain = new (std::nothrow) mbedtls_x509_crt;
  if (!ca_chain) { return nullptr; }

  mbedtls_x509_crt_init(ca_chain);

  // mbedtls_x509_crt_parse expects null-terminated PEM
  int ret = mbedtls_x509_crt_parse(ca_chain,
                                   reinterpret_cast<const unsigned char *>(pem),
                                   len + 1); // +1 for null terminator
  if (ret != 0) {
    // Try without +1 in case PEM is already null-terminated
    ret = mbedtls_x509_crt_parse(
        ca_chain, reinterpret_cast<const unsigned char *>(pem), len);
    if (ret != 0) {
      mbedtls_x509_crt_free(ca_chain);
      delete ca_chain;
      return nullptr;
    }
  }

  return static_cast<ca_store_t>(ca_chain);
}

void free_ca_store(ca_store_t store) {
  if (store) {
    auto *ca_chain = static_cast<mbedtls_x509_crt *>(store);
    mbedtls_x509_crt_free(ca_chain);
    delete ca_chain;
  }
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);
  auto *ca_chain = static_cast<mbedtls_x509_crt *>(store);

  // Free existing CA chain
  mbedtls_x509_crt_free(&mbed_ctx->ca_chain);
  mbedtls_x509_crt_init(&mbed_ctx->ca_chain);

  // Copy the CA chain (deep copy)
  // Parse from the raw data of the source cert
  mbedtls_x509_crt *src = ca_chain;
  while (src != nullptr) {
    int ret = mbedtls_x509_crt_parse_der(&mbed_ctx->ca_chain, src->raw.p,
                                         src->raw.len);
    if (ret != 0) { return false; }
    src = src->next;
  }

  // Update the SSL config to use the new CA chain
  mbedtls_ssl_conf_ca_chain(&mbed_ctx->conf, &mbed_ctx->ca_chain, nullptr);
  return true;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Iterate through the CA chain
  mbedtls_x509_crt *cert = &mbed_ctx->ca_chain;
  while (cert != nullptr && cert->raw.len > 0) {
    // Create a copy of the certificate for the caller
    auto *copy = new mbedtls_x509_crt;
    mbedtls_x509_crt_init(copy);
    int ret = mbedtls_x509_crt_parse_der(copy, cert->raw.p, cert->raw.len);
    if (ret == 0) {
      certs.push_back(static_cast<cert_t>(copy));
    } else {
      mbedtls_x509_crt_free(copy);
      delete copy;
    }
    cert = cert->next;
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Iterate through the CA chain
  mbedtls_x509_crt *cert = &mbed_ctx->ca_chain;
  while (cert != nullptr && cert->raw.len > 0) {
    char buf[512];
    int ret = mbedtls_x509_dn_gets(buf, sizeof(buf), &cert->subject);
    if (ret > 0) { names.push_back(buf); }
    cert = cert->next;
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Free existing certificate and key
  mbedtls_x509_crt_free(&mbed_ctx->own_cert);
  mbedtls_pk_free(&mbed_ctx->own_key);
  mbedtls_x509_crt_init(&mbed_ctx->own_cert);
  mbedtls_pk_init(&mbed_ctx->own_key);

  // Parse certificate PEM
  int ret = mbedtls_x509_crt_parse(
      &mbed_ctx->own_cert, reinterpret_cast<const unsigned char *>(cert_pem),
      strlen(cert_pem) + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Parse private key PEM
#ifdef CPPHTTPLIB_MBEDTLS_V3
  ret = mbedtls_pk_parse_key(
      &mbed_ctx->own_key, reinterpret_cast<const unsigned char *>(key_pem),
      strlen(key_pem) + 1,
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr,
      password ? strlen(password) : 0, mbedtls_ctr_drbg_random,
      &mbed_ctx->ctr_drbg);
#else
  ret = mbedtls_pk_parse_key(
      &mbed_ctx->own_key, reinterpret_cast<const unsigned char *>(key_pem),
      strlen(key_pem) + 1,
      password ? reinterpret_cast<const unsigned char *>(password) : nullptr,
      password ? strlen(password) : 0);
#endif
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Configure SSL to use the new certificate and key
  ret = mbedtls_ssl_conf_own_cert(&mbed_ctx->conf, &mbed_ctx->own_cert,
                                  &mbed_ctx->own_key);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  return true;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  // Free existing CA chain
  mbedtls_x509_crt_free(&mbed_ctx->ca_chain);
  mbedtls_x509_crt_init(&mbed_ctx->ca_chain);

  // Parse CA PEM
  int ret = mbedtls_x509_crt_parse(
      &mbed_ctx->ca_chain, reinterpret_cast<const unsigned char *>(ca_pem),
      strlen(ca_pem) + 1);
  if (ret != 0) {
    impl::mbedtls_last_error() = ret;
    return false;
  }

  // Update SSL config to use new CA chain
  mbedtls_ssl_conf_ca_chain(&mbed_ctx->conf, &mbed_ctx->ca_chain, nullptr);
  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);

  impl::get_verify_callback() = std::move(callback);
  mbed_ctx->has_verify_callback =
      static_cast<bool>(impl::get_verify_callback());

  if (mbed_ctx->has_verify_callback) {
    // Set OPTIONAL mode to ensure callback is called even when verification
    // is disabled (matching OpenSSL behavior where SSL_VERIFY_PEER is set)
    mbedtls_ssl_conf_authmode(&mbed_ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
    mbedtls_ssl_conf_verify(&mbed_ctx->conf, impl::mbedtls_verify_callback,
                            nullptr);
  } else {
    mbedtls_ssl_conf_verify(&mbed_ctx->conf, nullptr, nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto *msession =
      static_cast<impl::MbedTlsSession *>(const_cast<void *>(session));
  return static_cast<long>(mbedtls_ssl_get_verify_result(&msession->ssl));
}

std::string verify_error_string(long error_code) {
  if (error_code == 0) { return ""; }
  char buf[256];
  mbedtls_x509_crt_verify_info(buf, sizeof(buf), "",
                               static_cast<uint32_t>(error_code));
  // Remove trailing newline if present
  std::string result(buf);
  while (!result.empty() && (result.back() == '\n' || result.back() == ' ')) {
    result.pop_back();
  }
  return result;
}

} // namespace tls

#endif // CPPHTTPLIB_MBEDTLS_SUPPORT

/*
 * Group 10: TLS abstraction layer - wolfSSL backend
 */

/*
 * wolfSSL Backend Implementation
 */

#ifdef CPPHTTPLIB_WOLFSSL_SUPPORT
namespace tls {

namespace impl {

// wolfSSL session wrapper
struct WolfSSLSession {
  WOLFSSL *ssl = nullptr;
  socket_t sock = INVALID_SOCKET;
  std::string hostname;     // For client: set via set_sni
  std::string sni_hostname; // For server: received from client via SNI callback

  WolfSSLSession() = default;

  ~WolfSSLSession() {
    if (ssl) { wolfSSL_free(ssl); }
  }

  WolfSSLSession(const WolfSSLSession &) = delete;
  WolfSSLSession &operator=(const WolfSSLSession &) = delete;
};

// Thread-local error code accessor for wolfSSL
uint64_t &wolfssl_last_error() {
  static thread_local uint64_t err = 0;
  return err;
}

// Helper to map wolfSSL error to ErrorCode.
// ssl_error is the value from wolfSSL_get_error().
// raw_ret is the raw return value from the wolfSSL call (for low-level error).
ErrorCode map_wolfssl_error(WOLFSSL *ssl, int ssl_error,
                                   int &out_errno) {
  switch (ssl_error) {
  case SSL_ERROR_NONE: return ErrorCode::Success;
  case SSL_ERROR_WANT_READ: return ErrorCode::WantRead;
  case SSL_ERROR_WANT_WRITE: return ErrorCode::WantWrite;
  case SSL_ERROR_ZERO_RETURN: return ErrorCode::PeerClosed;
  case SSL_ERROR_SYSCALL: out_errno = errno; return ErrorCode::SyscallError;
  default:
    if (ssl) {
      // wolfSSL stores the low-level error code as a negative value.
      // DOMAIN_NAME_MISMATCH (-322) indicates hostname verification failure.
      int low_err = ssl_error; // wolfSSL_get_error returns the low-level code
      if (low_err == DOMAIN_NAME_MISMATCH) {
        return ErrorCode::HostnameMismatch;
      }
      // Check verify result to distinguish cert verification from generic SSL
      // errors.
      long vr = wolfSSL_get_verify_result(ssl);
      if (vr != 0) { return ErrorCode::CertVerifyFailed; }
    }
    return ErrorCode::Fatal;
  }
}

// WolfSSLContext constructor/destructor implementations
WolfSSLContext::WolfSSLContext() { wolfSSL_Init(); }

WolfSSLContext::~WolfSSLContext() {
  if (ctx) { wolfSSL_CTX_free(ctx); }
}

// Thread-local storage for SNI captured during handshake
std::string &wolfssl_pending_sni() {
  static thread_local std::string sni;
  return sni;
}

// SNI callback for wolfSSL server to capture client's SNI hostname
int wolfssl_sni_callback(WOLFSSL *ssl, int *ret, void *exArg) {
  (void)ret;
  (void)exArg;

  void *name_data = nullptr;
  unsigned short name_len =
      wolfSSL_SNI_GetRequest(ssl, WOLFSSL_SNI_HOST_NAME, &name_data);

  if (name_data && name_len > 0) {
    wolfssl_pending_sni().assign(static_cast<const char *>(name_data),
                                 name_len);
  } else {
    wolfssl_pending_sni().clear();
  }
  return 0; // Continue regardless
}

// wolfSSL verify callback wrapper
int wolfssl_verify_callback(int preverify_ok,
                                   WOLFSSL_X509_STORE_CTX *x509_ctx) {
  auto &callback = get_verify_callback();
  if (!callback) { return preverify_ok; }

  WOLFSSL_X509 *cert = wolfSSL_X509_STORE_CTX_get_current_cert(x509_ctx);
  int depth = wolfSSL_X509_STORE_CTX_get_error_depth(x509_ctx);
  int err = wolfSSL_X509_STORE_CTX_get_error(x509_ctx);

  // Get the WOLFSSL object from the X509_STORE_CTX
  WOLFSSL *ssl = static_cast<WOLFSSL *>(wolfSSL_X509_STORE_CTX_get_ex_data(
      x509_ctx, wolfSSL_get_ex_data_X509_STORE_CTX_idx()));

  VerifyContext verify_ctx;
  verify_ctx.session = static_cast<session_t>(ssl);
  verify_ctx.cert = static_cast<cert_t>(cert);
  verify_ctx.depth = depth;
  verify_ctx.preverify_ok = (preverify_ok != 0);
  verify_ctx.error_code = static_cast<long>(err);

  if (err != 0) {
    verify_ctx.error_string = wolfSSL_X509_verify_cert_error_string(err);
  } else {
    verify_ctx.error_string = nullptr;
  }

  bool accepted = callback(verify_ctx);
  return accepted ? 1 : 0;
}

void set_wolfssl_password_cb(WOLFSSL_CTX *ctx, const char *password) {
  wolfSSL_CTX_set_default_passwd_cb_userdata(ctx, const_cast<char *>(password));
  wolfSSL_CTX_set_default_passwd_cb(
      ctx, [](char *buf, int size, int /*rwflag*/, void *userdata) -> int {
        auto *pwd = static_cast<const char *>(userdata);
        if (!pwd) return 0;
        auto len = static_cast<int>(strlen(pwd));
        if (len > size) len = size;
        memcpy(buf, pwd, static_cast<size_t>(len));
        return len;
      });
}

} // namespace impl

ctx_t create_client_context() {
  auto ctx = new (std::nothrow) impl::WolfSSLContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = false;

  WOLFSSL_METHOD *method = wolfTLSv1_2_client_method();
  if (!method) {
    delete ctx;
    return nullptr;
  }

  ctx->ctx = wolfSSL_CTX_new(method);
  if (!ctx->ctx) {
    delete ctx;
    return nullptr;
  }

  // Default: verify peer certificate
  wolfSSL_CTX_set_verify(ctx->ctx, SSL_VERIFY_PEER, nullptr);

  return static_cast<ctx_t>(ctx);
}

ctx_t create_server_context() {
  auto ctx = new (std::nothrow) impl::WolfSSLContext();
  if (!ctx) { return nullptr; }

  ctx->is_server = true;

  WOLFSSL_METHOD *method = wolfTLSv1_2_server_method();
  if (!method) {
    delete ctx;
    return nullptr;
  }

  ctx->ctx = wolfSSL_CTX_new(method);
  if (!ctx->ctx) {
    delete ctx;
    return nullptr;
  }

  // Default: don't verify client
  wolfSSL_CTX_set_verify(ctx->ctx, SSL_VERIFY_NONE, nullptr);

  // Enable SNI on server
  wolfSSL_CTX_SNI_SetOptions(ctx->ctx, WOLFSSL_SNI_HOST_NAME,
                             WOLFSSL_SNI_CONTINUE_ON_MISMATCH);
  wolfSSL_CTX_set_servername_callback(ctx->ctx, impl::wolfssl_sni_callback);

  return static_cast<ctx_t>(ctx);
}

void free_context(ctx_t ctx) {
  if (ctx) { delete static_cast<impl::WolfSSLContext *>(ctx); }
}

bool set_min_version(ctx_t ctx, Version version) {
  if (!ctx) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int min_ver = WOLFSSL_TLSV1_2;
  if (version >= Version::TLS1_3) { min_ver = WOLFSSL_TLSV1_3; }

  return wolfSSL_CTX_SetMinVersion(wctx->ctx, min_ver) == WOLFSSL_SUCCESS;
}

bool load_ca_pem(ctx_t ctx, const char *pem, size_t len) {
  if (!ctx || !pem) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(pem),
      static_cast<long>(len), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  wctx->ca_pem_data_.append(pem, len);
  return true;
}

bool load_ca_file(ctx_t ctx, const char *file_path) {
  if (!ctx || !file_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_locations(wctx->ctx, file_path, nullptr);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  return true;
}

bool load_ca_dir(ctx_t ctx, const char *dir_path) {
  if (!ctx || !dir_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_locations(wctx->ctx, nullptr, dir_path);
  // wolfSSL may fail if the directory doesn't contain properly hashed certs.
  // Unlike OpenSSL which lazily loads certs from directories, wolfSSL scans
  // immediately. Return true even on failure since the CA file may have
  // already been loaded, matching OpenSSL's lenient behavior.
  (void)ret;
  return true;
}

bool load_system_certs(ctx_t ctx) {
  if (!ctx) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);
  bool loaded = false;

#ifdef _WIN32
  loaded = impl::enumerate_windows_system_certs(
      [&](const unsigned char *data, size_t len) {
        return wolfSSL_CTX_load_verify_buffer(wctx->ctx, data,
                                              static_cast<long>(len),
                                              SSL_FILETYPE_ASN1) == SSL_SUCCESS;
      });
#elif defined(__APPLE__) && defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN)
  loaded = impl::enumerate_macos_keychain_certs(
      [&](const unsigned char *data, size_t len) {
        return wolfSSL_CTX_load_verify_buffer(wctx->ctx, data,
                                              static_cast<long>(len),
                                              SSL_FILETYPE_ASN1) == SSL_SUCCESS;
      });
#else
  for (auto path = impl::system_ca_paths(); *path; ++path) {
    if (wolfSSL_CTX_load_verify_locations(wctx->ctx, *path, nullptr) ==
        SSL_SUCCESS) {
      loaded = true;
      break;
    }
  }

  if (!loaded) {
    for (auto dir = impl::system_ca_dirs(); *dir; ++dir) {
      if (wolfSSL_CTX_load_verify_locations(wctx->ctx, nullptr, *dir) ==
          SSL_SUCCESS) {
        loaded = true;
        break;
      }
    }
  }
#endif

  return loaded;
}

bool set_client_cert_pem(ctx_t ctx, const char *cert, const char *key,
                                const char *password) {
  if (!ctx || !cert || !key) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load certificate
  int ret = wolfSSL_CTX_use_certificate_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(cert),
      static_cast<long>(strlen(cert)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password callback if password is provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load private key
  ret = wolfSSL_CTX_use_PrivateKey_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(key),
      static_cast<long>(strlen(key)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Verify that the certificate and private key match
  return wolfSSL_CTX_check_private_key(wctx->ctx) == SSL_SUCCESS;
}

bool set_client_cert_file(ctx_t ctx, const char *cert_path,
                                 const char *key_path, const char *password) {
  if (!ctx || !cert_path || !key_path) { return false; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load certificate file
  int ret =
      wolfSSL_CTX_use_certificate_file(wctx->ctx, cert_path, SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password callback if password is provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load private key file
  ret = wolfSSL_CTX_use_PrivateKey_file(wctx->ctx, key_path, SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Verify that the certificate and private key match
  return wolfSSL_CTX_check_private_key(wctx->ctx) == SSL_SUCCESS;
}

void set_verify_client(ctx_t ctx, bool require) {
  if (!ctx) { return; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);
  wctx->verify_client = require;
  if (require) {
    wolfSSL_CTX_set_verify(
        wctx->ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
        wctx->has_verify_callback ? impl::wolfssl_verify_callback : nullptr);
  } else {
    if (wctx->has_verify_callback) {
      wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_PEER,
                             impl::wolfssl_verify_callback);
    } else {
      wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_NONE, nullptr);
    }
  }
}

session_t create_session(ctx_t ctx, socket_t sock) {
  if (!ctx || sock == INVALID_SOCKET) { return nullptr; }
  auto wctx = static_cast<impl::WolfSSLContext *>(ctx);

  auto session = new (std::nothrow) impl::WolfSSLSession();
  if (!session) { return nullptr; }

  session->sock = sock;
  session->ssl = wolfSSL_new(wctx->ctx);
  if (!session->ssl) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    delete session;
    return nullptr;
  }

  wolfSSL_set_fd(session->ssl, static_cast<int>(sock));

  return static_cast<session_t>(session);
}

void free_session(session_t session) {
  if (session) { delete static_cast<impl::WolfSSLSession *>(session); }
}

bool set_sni(session_t session, const char *hostname) {
  if (!session || !hostname) { return false; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  int ret = wolfSSL_UseSNI(wsession->ssl, WOLFSSL_SNI_HOST_NAME, hostname,
                           static_cast<word16>(strlen(hostname)));
  if (ret != WOLFSSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Also set hostname for verification
  wolfSSL_check_domain_name(wsession->ssl, hostname);

  wsession->hostname = hostname;
  return true;
}

bool set_hostname(session_t session, const char *hostname) {
  // In wolfSSL, set_hostname also sets up hostname verification
  return set_sni(session, hostname);
}

TlsError connect(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_connect(wsession->ssl);

  if (ret == SSL_SUCCESS) {
    err.code = ErrorCode::Success;
  } else {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(ssl_error);
    impl::wolfssl_last_error() = err.backend_code;
  }

  return err;
}

TlsError accept(session_t session) {
  TlsError err;
  if (!session) {
    err.code = ErrorCode::Fatal;
    return err;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_accept(wsession->ssl);

  if (ret == SSL_SUCCESS) {
    err.code = ErrorCode::Success;
    // Capture SNI from thread-local storage after successful handshake
    wsession->sni_hostname = std::move(impl::wolfssl_pending_sni());
    impl::wolfssl_pending_sni().clear();
  } else {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
    err.backend_code = static_cast<uint64_t>(ssl_error);
    impl::wolfssl_last_error() = err.backend_code;
  }

  return err;
}

bool connect_nonblocking(session_t session, socket_t sock,
                                time_t timeout_sec, time_t timeout_usec,
                                TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = wolfSSL_connect(wsession->ssl)) != SSL_SUCCESS) {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    if (ssl_error == SSL_ERROR_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ssl_error == SSL_ERROR_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // Error or timeout
    if (err) {
      err->code =
          impl::map_wolfssl_error(wsession->ssl, ssl_error, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(ssl_error);
    }
    impl::wolfssl_last_error() = static_cast<uint64_t>(ssl_error);
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }
  return true;
}

bool accept_nonblocking(session_t session, socket_t sock,
                               time_t timeout_sec, time_t timeout_usec,
                               TlsError *err) {
  if (!session) {
    if (err) { err->code = ErrorCode::Fatal; }
    return false;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Set socket to non-blocking mode
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  int ret;
  while ((ret = wolfSSL_accept(wsession->ssl)) != SSL_SUCCESS) {
    int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
    if (ssl_error == SSL_ERROR_WANT_READ) {
      if (detail::select_read(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    } else if (ssl_error == SSL_ERROR_WANT_WRITE) {
      if (detail::select_write(sock, timeout_sec, timeout_usec) > 0) {
        continue;
      }
    }

    // Error or timeout
    if (err) {
      err->code =
          impl::map_wolfssl_error(wsession->ssl, ssl_error, err->sys_errno);
      err->backend_code = static_cast<uint64_t>(ssl_error);
    }
    impl::wolfssl_last_error() = static_cast<uint64_t>(ssl_error);
    return false;
  }

  if (err) { err->code = ErrorCode::Success; }

  // Capture SNI from thread-local storage after successful handshake
  wsession->sni_hostname = std::move(impl::wolfssl_pending_sni());
  impl::wolfssl_pending_sni().clear();

  return true;
}

ssize_t read(session_t session, void *buf, size_t len, TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_read(wsession->ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return 0;
  }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(ssl_error);
  impl::wolfssl_last_error() = err.backend_code;
  return -1;
}

ssize_t write(session_t session, const void *buf, size_t len,
                     TlsError &err) {
  if (!session || !buf) {
    err.code = ErrorCode::Fatal;
    return -1;
  }

  auto wsession = static_cast<impl::WolfSSLSession *>(session);
  int ret = wolfSSL_write(wsession->ssl, buf, static_cast<int>(len));

  if (ret > 0) {
    err.code = ErrorCode::Success;
    return static_cast<ssize_t>(ret);
  }

  // wolfSSL_write returns 0 when the peer has sent a close_notify.
  // Treat this as an error (return -1) so callers don't spin in a
  // write loop adding zero to the offset.
  if (ret == 0) {
    err.code = ErrorCode::PeerClosed;
    return -1;
  }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  err.code = impl::map_wolfssl_error(wsession->ssl, ssl_error, err.sys_errno);
  err.backend_code = static_cast<uint64_t>(ssl_error);
  impl::wolfssl_last_error() = err.backend_code;
  return -1;
}

int pending(const_session_t session) {
  if (!session) { return 0; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  return wolfSSL_pending(wsession->ssl);
}

void shutdown(session_t session, bool graceful) {
  if (!session) { return; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  if (graceful) {
    int ret;
    int attempts = 0;
    while ((ret = wolfSSL_shutdown(wsession->ssl)) != SSL_SUCCESS &&
           attempts < 3) {
      int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
      if (ssl_error != SSL_ERROR_WANT_READ &&
          ssl_error != SSL_ERROR_WANT_WRITE) {
        break;
      }
      attempts++;
    }
  } else {
    wolfSSL_shutdown(wsession->ssl);
  }
}

bool is_peer_closed(session_t session, socket_t sock) {
  if (!session || sock == INVALID_SOCKET) { return true; }
  auto wsession = static_cast<impl::WolfSSLSession *>(session);

  // Check if there's already decrypted data available
  if (wolfSSL_pending(wsession->ssl) > 0) { return false; }

  // Set socket to non-blocking to avoid blocking on read
  detail::set_nonblocking(sock, true);
  auto cleanup =
      detail::scope_exit([&]() { detail::set_nonblocking(sock, false); });

  // Peek 1 byte to check connection status without consuming data
  unsigned char buf;
  int ret = wolfSSL_peek(wsession->ssl, &buf, 1);

  // If we got data or WANT_READ (would block), connection is alive
  if (ret > 0) { return false; }

  int ssl_error = wolfSSL_get_error(wsession->ssl, ret);
  if (ssl_error == SSL_ERROR_WANT_READ) { return false; }

  return ssl_error == SSL_ERROR_ZERO_RETURN || ssl_error == SSL_ERROR_SYSCALL ||
         ret == 0;
}

cert_t get_peer_cert(const_session_t session) {
  if (!session) { return nullptr; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));

  WOLFSSL_X509 *cert = wolfSSL_get_peer_certificate(wsession->ssl);
  return static_cast<cert_t>(cert);
}

void free_cert(cert_t cert) {
  if (cert) { wolfSSL_X509_free(static_cast<WOLFSSL_X509 *>(cert)); }
}

bool verify_hostname(cert_t cert, const char *hostname) {
  if (!cert || !hostname) { return false; }
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);
  std::string host_str(hostname);

  // Check if hostname is an IP address
  bool is_ip = impl::is_ipv4_address(host_str);
  unsigned char ip_bytes[4];
  if (is_ip) { impl::parse_ipv4(host_str, ip_bytes); }

  // Check Subject Alternative Names
  auto *san_names = static_cast<WOLF_STACK_OF(WOLFSSL_GENERAL_NAME) *>(
      wolfSSL_X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));

  if (san_names) {
    int san_count = wolfSSL_sk_num(san_names);
    for (int i = 0; i < san_count; i++) {
      auto *names =
          static_cast<WOLFSSL_GENERAL_NAME *>(wolfSSL_sk_value(san_names, i));
      if (!names) continue;

      if (!is_ip && names->type == WOLFSSL_GEN_DNS) {
        // DNS name
        unsigned char *dns_name = nullptr;
        int dns_len = wolfSSL_ASN1_STRING_to_UTF8(&dns_name, names->d.dNSName);
        if (dns_name && dns_len > 0) {
          std::string san_name(reinterpret_cast<char *>(dns_name),
                               static_cast<size_t>(dns_len));
          XFREE(dns_name, nullptr, DYNAMIC_TYPE_OPENSSL);
          if (detail::match_hostname(san_name, host_str)) {
            wolfSSL_sk_free(san_names);
            return true;
          }
        }
      } else if (is_ip && names->type == WOLFSSL_GEN_IPADD) {
        // IP address
        unsigned char *ip_data = wolfSSL_ASN1_STRING_data(names->d.iPAddress);
        int ip_len = wolfSSL_ASN1_STRING_length(names->d.iPAddress);
        if (ip_data && ip_len == 4 && memcmp(ip_data, ip_bytes, 4) == 0) {
          wolfSSL_sk_free(san_names);
          return true;
        }
      }
    }
    wolfSSL_sk_free(san_names);
  }

  // Fallback: Check Common Name (CN) in subject
  WOLFSSL_X509_NAME *subject = wolfSSL_X509_get_subject_name(x509);
  if (subject) {
    char cn[256] = {};
    int cn_len = wolfSSL_X509_NAME_get_text_by_NID(subject, NID_commonName, cn,
                                                   sizeof(cn));
    if (cn_len > 0) {
      std::string cn_str(cn, static_cast<size_t>(cn_len));
      if (detail::match_hostname(cn_str, host_str)) { return true; }
    }
  }

  return false;
}

uint64_t hostname_mismatch_code() {
  return static_cast<uint64_t>(DOMAIN_NAME_MISMATCH);
}

long get_verify_result(const_session_t session) {
  if (!session) { return -1; }
  auto wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  long result = wolfSSL_get_verify_result(wsession->ssl);
  return result;
}

std::string get_cert_subject_cn(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_X509_NAME *subject = wolfSSL_X509_get_subject_name(x509);
  if (!subject) return "";

  char cn[256] = {};
  int cn_len = wolfSSL_X509_NAME_get_text_by_NID(subject, NID_commonName, cn,
                                                 sizeof(cn));
  if (cn_len <= 0) return "";
  return std::string(cn, static_cast<size_t>(cn_len));
}

std::string get_cert_issuer_name(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_X509_NAME *issuer = wolfSSL_X509_get_issuer_name(x509);
  if (!issuer) return "";

  char *name_str = wolfSSL_X509_NAME_oneline(issuer, nullptr, 0);
  if (!name_str) return "";

  std::string result(name_str);
  XFREE(name_str, nullptr, DYNAMIC_TYPE_OPENSSL);
  return result;
}

bool get_cert_sans(cert_t cert, std::vector<SanEntry> &sans) {
  sans.clear();
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  auto *san_names = static_cast<WOLF_STACK_OF(WOLFSSL_GENERAL_NAME) *>(
      wolfSSL_X509_get_ext_d2i(x509, NID_subject_alt_name, nullptr, nullptr));
  if (!san_names) return true; // No SANs is not an error

  int count = wolfSSL_sk_num(san_names);
  for (int i = 0; i < count; i++) {
    auto *name =
        static_cast<WOLFSSL_GENERAL_NAME *>(wolfSSL_sk_value(san_names, i));
    if (!name) continue;

    SanEntry entry;
    switch (name->type) {
    case WOLFSSL_GEN_DNS: {
      entry.type = SanType::DNS;
      unsigned char *dns_name = nullptr;
      int dns_len = wolfSSL_ASN1_STRING_to_UTF8(&dns_name, name->d.dNSName);
      if (dns_name && dns_len > 0) {
        entry.value = std::string(reinterpret_cast<char *>(dns_name),
                                  static_cast<size_t>(dns_len));
        XFREE(dns_name, nullptr, DYNAMIC_TYPE_OPENSSL);
      }
      break;
    }
    case WOLFSSL_GEN_IPADD: {
      entry.type = SanType::IP;
      unsigned char *ip_data = wolfSSL_ASN1_STRING_data(name->d.iPAddress);
      int ip_len = wolfSSL_ASN1_STRING_length(name->d.iPAddress);
      if (ip_data && ip_len == 4) {
        char buf[16];
        snprintf(buf, sizeof(buf), "%d.%d.%d.%d", ip_data[0], ip_data[1],
                 ip_data[2], ip_data[3]);
        entry.value = buf;
      } else if (ip_data && ip_len == 16) {
        char buf[64];
        snprintf(buf, sizeof(buf),
                 "%02x%02x:%02x%02x:%02x%02x:%02x%02x:"
                 "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                 ip_data[0], ip_data[1], ip_data[2], ip_data[3], ip_data[4],
                 ip_data[5], ip_data[6], ip_data[7], ip_data[8], ip_data[9],
                 ip_data[10], ip_data[11], ip_data[12], ip_data[13],
                 ip_data[14], ip_data[15]);
        entry.value = buf;
      }
      break;
    }
    case WOLFSSL_GEN_EMAIL:
      entry.type = SanType::EMAIL;
      {
        unsigned char *email = nullptr;
        int email_len = wolfSSL_ASN1_STRING_to_UTF8(&email, name->d.rfc822Name);
        if (email && email_len > 0) {
          entry.value = std::string(reinterpret_cast<char *>(email),
                                    static_cast<size_t>(email_len));
          XFREE(email, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      break;
    case WOLFSSL_GEN_URI:
      entry.type = SanType::URI;
      {
        unsigned char *uri = nullptr;
        int uri_len = wolfSSL_ASN1_STRING_to_UTF8(
            &uri, name->d.uniformResourceIdentifier);
        if (uri && uri_len > 0) {
          entry.value = std::string(reinterpret_cast<char *>(uri),
                                    static_cast<size_t>(uri_len));
          XFREE(uri, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      break;
    default: entry.type = SanType::OTHER; break;
    }

    if (!entry.value.empty()) { sans.push_back(std::move(entry)); }
  }
  wolfSSL_sk_free(san_names);
  return true;
}

bool get_cert_validity(cert_t cert, time_t &not_before,
                              time_t &not_after) {
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  const WOLFSSL_ASN1_TIME *nb = wolfSSL_X509_get_notBefore(x509);
  const WOLFSSL_ASN1_TIME *na = wolfSSL_X509_get_notAfter(x509);

  if (!nb || !na) return false;

  // wolfSSL_ASN1_TIME_to_tm is available
  struct tm tm_nb = {}, tm_na = {};
  if (wolfSSL_ASN1_TIME_to_tm(nb, &tm_nb) != WOLFSSL_SUCCESS) return false;
  if (wolfSSL_ASN1_TIME_to_tm(na, &tm_na) != WOLFSSL_SUCCESS) return false;

#ifdef _WIN32
  not_before = _mkgmtime(&tm_nb);
  not_after = _mkgmtime(&tm_na);
#else
  not_before = timegm(&tm_nb);
  not_after = timegm(&tm_na);
#endif
  return true;
}

std::string get_cert_serial(cert_t cert) {
  if (!cert) return "";
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  WOLFSSL_ASN1_INTEGER *serial_asn1 = wolfSSL_X509_get_serialNumber(x509);
  if (!serial_asn1) return "";

  // Get the serial number data
  int len = serial_asn1->length;
  unsigned char *data = serial_asn1->data;
  if (!data || len <= 0) return "";

  std::string result;
  result.reserve(static_cast<size_t>(len) * 2);
  for (int i = 0; i < len; i++) {
    char hex[3];
    snprintf(hex, sizeof(hex), "%02X", data[i]);
    result += hex;
  }
  return result;
}

bool get_cert_der(cert_t cert, std::vector<unsigned char> &der) {
  if (!cert) return false;
  auto x509 = static_cast<WOLFSSL_X509 *>(cert);

  int der_len = 0;
  const unsigned char *der_data = wolfSSL_X509_get_der(x509, &der_len);
  if (!der_data || der_len <= 0) return false;

  der.assign(der_data, der_data + der_len);
  return true;
}

const char *get_sni(const_session_t session) {
  if (!session) return nullptr;
  auto wsession = static_cast<const impl::WolfSSLSession *>(session);

  // For server: return SNI received from client during handshake
  if (!wsession->sni_hostname.empty()) {
    return wsession->sni_hostname.c_str();
  }

  // For client: return the hostname set via set_sni
  if (!wsession->hostname.empty()) { return wsession->hostname.c_str(); }

  return nullptr;
}

uint64_t peek_error() {
  return static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
}

uint64_t get_error() {
  uint64_t err = impl::wolfssl_last_error();
  impl::wolfssl_last_error() = 0;
  return err;
}

std::string error_string(uint64_t code) {
  char buf[256];
  wolfSSL_ERR_error_string(static_cast<unsigned long>(code), buf);
  return std::string(buf);
}

ca_store_t create_ca_store(const char *pem, size_t len) {
  if (!pem || len == 0) { return nullptr; }
  // Validate by attempting to load into a temporary ctx
  WOLFSSL_CTX *tmp_ctx = wolfSSL_CTX_new(wolfTLSv1_2_client_method());
  if (!tmp_ctx) { return nullptr; }
  int ret = wolfSSL_CTX_load_verify_buffer(
      tmp_ctx, reinterpret_cast<const unsigned char *>(pem),
      static_cast<long>(len), SSL_FILETYPE_PEM);
  wolfSSL_CTX_free(tmp_ctx);
  if (ret != SSL_SUCCESS) { return nullptr; }
  return static_cast<ca_store_t>(
      new impl::WolfSSLCAStore{std::string(pem, len)});
}

void free_ca_store(ca_store_t store) {
  delete static_cast<impl::WolfSSLCAStore *>(store);
}

bool set_ca_store(ctx_t ctx, ca_store_t store) {
  if (!ctx || !store) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  auto *ca = static_cast<impl::WolfSSLCAStore *>(store);
  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(ca->pem_data.data()),
      static_cast<long>(ca->pem_data.size()), SSL_FILETYPE_PEM);
  if (ret == SSL_SUCCESS) { wctx->ca_pem_data_ += ca->pem_data; }
  return ret == SSL_SUCCESS;
}

size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
  certs.clear();
  if (!ctx) { return 0; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  if (wctx->ca_pem_data_.empty()) { return 0; }

  const std::string &pem = wctx->ca_pem_data_;
  const std::string begin_marker = "-----BEGIN CERTIFICATE-----";
  const std::string end_marker = "-----END CERTIFICATE-----";
  size_t pos = 0;
  while ((pos = pem.find(begin_marker, pos)) != std::string::npos) {
    size_t end_pos = pem.find(end_marker, pos);
    if (end_pos == std::string::npos) { break; }
    end_pos += end_marker.size();
    std::string cert_pem = pem.substr(pos, end_pos - pos);
    WOLFSSL_X509 *x509 = wolfSSL_X509_load_certificate_buffer(
        reinterpret_cast<const unsigned char *>(cert_pem.data()),
        static_cast<int>(cert_pem.size()), WOLFSSL_FILETYPE_PEM);
    if (x509) { certs.push_back(static_cast<cert_t>(x509)); }
    pos = end_pos;
  }
  return certs.size();
}

std::vector<std::string> get_ca_names(ctx_t ctx) {
  std::vector<std::string> names;
  if (!ctx) { return names; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);
  if (wctx->ca_pem_data_.empty()) { return names; }

  const std::string &pem = wctx->ca_pem_data_;
  const std::string begin_marker = "-----BEGIN CERTIFICATE-----";
  const std::string end_marker = "-----END CERTIFICATE-----";
  size_t pos = 0;
  while ((pos = pem.find(begin_marker, pos)) != std::string::npos) {
    size_t end_pos = pem.find(end_marker, pos);
    if (end_pos == std::string::npos) { break; }
    end_pos += end_marker.size();
    std::string cert_pem = pem.substr(pos, end_pos - pos);
    WOLFSSL_X509 *x509 = wolfSSL_X509_load_certificate_buffer(
        reinterpret_cast<const unsigned char *>(cert_pem.data()),
        static_cast<int>(cert_pem.size()), WOLFSSL_FILETYPE_PEM);
    if (x509) {
      WOLFSSL_X509_NAME *subject = wolfSSL_X509_get_subject_name(x509);
      if (subject) {
        char *name_str = wolfSSL_X509_NAME_oneline(subject, nullptr, 0);
        if (name_str) {
          names.push_back(name_str);
          XFREE(name_str, nullptr, DYNAMIC_TYPE_OPENSSL);
        }
      }
      wolfSSL_X509_free(x509);
    }
    pos = end_pos;
  }
  return names;
}

bool update_server_cert(ctx_t ctx, const char *cert_pem,
                               const char *key_pem, const char *password) {
  if (!ctx || !cert_pem || !key_pem) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  // Load new certificate
  int ret = wolfSSL_CTX_use_certificate_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(cert_pem),
      static_cast<long>(strlen(cert_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  // Set password if provided
  if (password) { impl::set_wolfssl_password_cb(wctx->ctx, password); }

  // Load new private key
  ret = wolfSSL_CTX_use_PrivateKey_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(key_pem),
      static_cast<long>(strlen(key_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }

  return true;
}

bool update_server_client_ca(ctx_t ctx, const char *ca_pem) {
  if (!ctx || !ca_pem) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  int ret = wolfSSL_CTX_load_verify_buffer(
      wctx->ctx, reinterpret_cast<const unsigned char *>(ca_pem),
      static_cast<long>(strlen(ca_pem)), SSL_FILETYPE_PEM);
  if (ret != SSL_SUCCESS) {
    impl::wolfssl_last_error() =
        static_cast<uint64_t>(wolfSSL_ERR_peek_last_error());
    return false;
  }
  return true;
}

bool set_verify_callback(ctx_t ctx, VerifyCallback callback) {
  if (!ctx) { return false; }
  auto *wctx = static_cast<impl::WolfSSLContext *>(ctx);

  impl::get_verify_callback() = std::move(callback);
  wctx->has_verify_callback = static_cast<bool>(impl::get_verify_callback());

  if (wctx->has_verify_callback) {
    wolfSSL_CTX_set_verify(wctx->ctx, SSL_VERIFY_PEER,
                           impl::wolfssl_verify_callback);
  } else {
    wolfSSL_CTX_set_verify(
        wctx->ctx,
        wctx->verify_client
            ? (SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT)
            : SSL_VERIFY_NONE,
        nullptr);
  }
  return true;
}

long get_verify_error(const_session_t session) {
  if (!session) { return -1; }
  auto *wsession =
      static_cast<impl::WolfSSLSession *>(const_cast<void *>(session));
  return wolfSSL_get_verify_result(wsession->ssl);
}

std::string verify_error_string(long error_code) {
  if (error_code == 0) { return ""; }
  const char *str =
      wolfSSL_X509_verify_cert_error_string(static_cast<int>(error_code));
  return str ? std::string(str) : std::string();
}

} // namespace tls

#endif // CPPHTTPLIB_WOLFSSL_SUPPORT

// WebSocket implementation
namespace ws {

bool WebSocket::send_frame(Opcode op, const char *data, size_t len,
                                  bool fin) {
  std::lock_guard<std::mutex> lock(write_mutex_);
  if (closed_) { return false; }
  return detail::write_websocket_frame(strm_, op, data, len, fin, !is_server_);
}

ReadResult WebSocket::read(std::string &msg) {
  while (!closed_) {
    Opcode opcode;
    std::string payload;
    bool fin;

    if (!impl::read_websocket_frame(strm_, opcode, payload, fin, is_server_,
                                    CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH)) {
      closed_ = true;
      return Fail;
    }

    switch (opcode) {
    case Opcode::Ping: {
      std::lock_guard<std::mutex> lock(write_mutex_);
      detail::write_websocket_frame(strm_, Opcode::Pong, payload.data(),
                                    payload.size(), true, !is_server_);
      continue;
    }
    case Opcode::Pong: continue;
    case Opcode::Close: {
      if (!closed_.exchange(true)) {
        // Echo close frame back
        std::lock_guard<std::mutex> lock(write_mutex_);
        detail::write_websocket_frame(strm_, Opcode::Close, payload.data(),
                                      payload.size(), true, !is_server_);
      }
      return Fail;
    }
    case Opcode::Text:
    case Opcode::Binary: {
      auto result = opcode == Opcode::Text ? Text : Binary;
      msg = std::move(payload);

      // Handle fragmentation
      if (!fin) {
        while (true) {
          Opcode cont_opcode;
          std::string cont_payload;
          bool cont_fin;
          if (!impl::read_websocket_frame(
                  strm_, cont_opcode, cont_payload, cont_fin, is_server_,
                  CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH)) {
            closed_ = true;
            return Fail;
          }
          if (cont_opcode == Opcode::Ping) {
            std::lock_guard<std::mutex> lock(write_mutex_);
            detail::write_websocket_frame(
                strm_, Opcode::Pong, cont_payload.data(), cont_payload.size(),
                true, !is_server_);
            continue;
          }
          if (cont_opcode == Opcode::Pong) { continue; }
          if (cont_opcode == Opcode::Close) {
            if (!closed_.exchange(true)) {
              std::lock_guard<std::mutex> lock(write_mutex_);
              detail::write_websocket_frame(
                  strm_, Opcode::Close, cont_payload.data(),
                  cont_payload.size(), true, !is_server_);
            }
            return Fail;
          }
          // RFC 6455: continuation frames must use opcode 0x0
          if (cont_opcode != Opcode::Continuation) {
            closed_ = true;
            return Fail;
          }
          msg += cont_payload;
          if (msg.size() > CPPHTTPLIB_WEBSOCKET_MAX_PAYLOAD_LENGTH) {
            closed_ = true;
            return Fail;
          }
          if (cont_fin) { break; }
        }
      }
      // RFC 6455 Section 5.6: text frames must contain valid UTF-8
      if (result == Text && !impl::is_valid_utf8(msg)) {
        close(CloseStatus::InvalidPayload, "invalid UTF-8");
        return Fail;
      }
      return result;
    }
    default: closed_ = true; return Fail;
    }
  }
  return Fail;
}

bool WebSocket::send(const std::string &data) {
  return send_frame(Opcode::Text, data.data(), data.size());
}

bool WebSocket::send(const char *data, size_t len) {
  return send_frame(Opcode::Binary, data, len);
}

void WebSocket::close(CloseStatus status, const std::string &reason) {
  if (closed_.exchange(true)) { return; }
  ping_cv_.notify_all();
  std::string payload;
  auto code = static_cast<uint16_t>(status);
  payload.push_back(static_cast<char>((code >> 8) & 0xFF));
  payload.push_back(static_cast<char>(code & 0xFF));
  // RFC 6455 Section 5.5: control frame payload must not exceed 125 bytes
  // Close frame has 2-byte status code, so reason is limited to 123 bytes
  payload += reason.substr(0, 123);
  {
    std::lock_guard<std::mutex> lock(write_mutex_);
    detail::write_websocket_frame(strm_, Opcode::Close, payload.data(),
                                  payload.size(), true, !is_server_);
  }

  // RFC 6455 Section 7.1.1: after sending a Close frame, wait for the peer's
  // Close response before closing the TCP connection. Use a short timeout to
  // avoid hanging if the peer doesn't respond.
  strm_.set_read_timeout(CPPHTTPLIB_WEBSOCKET_CLOSE_TIMEOUT_SECOND, 0);
  Opcode op;
  std::string resp;
  bool fin;
  while (impl::read_websocket_frame(strm_, op, resp, fin, is_server_, 125)) {
    if (op == Opcode::Close) { break; }
  }
}

WebSocket::~WebSocket() {
  {
    std::lock_guard<std::mutex> lock(ping_mutex_);
    closed_ = true;
  }
  ping_cv_.notify_all();
  if (ping_thread_.joinable()) { ping_thread_.join(); }
}

void WebSocket::start_heartbeat() {
  if (ping_interval_sec_ == 0) { return; }
  ping_thread_ = std::thread([this]() {
    std::unique_lock<std::mutex> lock(ping_mutex_);
    while (!closed_) {
      ping_cv_.wait_for(lock, std::chrono::seconds(ping_interval_sec_));
      if (closed_) { break; }
      lock.unlock();
      if (!send_frame(Opcode::Ping, nullptr, 0)) {
        closed_ = true;
        break;
      }
      lock.lock();
    }
  });
}

const Request &WebSocket::request() const { return req_; }

bool WebSocket::is_open() const { return !closed_; }

// WebSocketClient implementation
WebSocketClient::WebSocketClient(
    const std::string &scheme_host_port_path, const Headers &headers)
    : headers_(headers) {
  const static std::regex re(
      R"(([a-z]+):\/\/(?:\[([a-fA-F\d:]+)\]|([^:/?#]+))(?::(\d+))?(\/.*))");

  std::smatch m;
  if (std::regex_match(scheme_host_port_path, m, re)) {
    auto scheme = m[1].str();

#ifdef CPPHTTPLIB_SSL_ENABLED
    if (scheme != "ws" && scheme != "wss") {
#else
    if (scheme != "ws") {
#endif
#ifndef CPPHTTPLIB_NO_EXCEPTIONS
      std::string msg = "'" + scheme + "' scheme is not supported.";
      throw std::invalid_argument(msg);
#endif
      return;
    }

    auto is_ssl = scheme == "wss";

    host_ = m[2].str();
    if (host_.empty()) { host_ = m[3].str(); }

    auto port_str = m[4].str();
    port_ = is_ssl ? 443 : 80;
    if (!port_str.empty() && !detail::parse_port(port_str, port_)) { return; }

    path_ = m[5].str();

#ifdef CPPHTTPLIB_SSL_ENABLED
    is_ssl_ = is_ssl;
#else
    if (is_ssl) { return; }
#endif

    is_valid_ = true;
  }
}

WebSocketClient::~WebSocketClient() { shutdown_and_close(); }

bool WebSocketClient::is_valid() const { return is_valid_; }

void WebSocketClient::shutdown_and_close() {
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl_) {
    if (tls_session_) {
      tls::shutdown(tls_session_, true);
      tls::free_session(tls_session_);
      tls_session_ = nullptr;
    }
    if (tls_ctx_) {
      tls::free_context(tls_ctx_);
      tls_ctx_ = nullptr;
    }
  }
#endif
  if (ws_ && ws_->is_open()) { ws_->close(); }
  ws_.reset();
  if (sock_ != INVALID_SOCKET) {
    detail::shutdown_socket(sock_);
    detail::close_socket(sock_);
    sock_ = INVALID_SOCKET;
  }
}

bool WebSocketClient::create_stream(std::unique_ptr<Stream> &strm) {
#ifdef CPPHTTPLIB_SSL_ENABLED
  if (is_ssl_) {
    if (!detail::setup_client_tls_session(
            host_, tls_ctx_, tls_session_, sock_,
            server_certificate_verification_, ca_cert_file_path_,
            ca_cert_store_, read_timeout_sec_, read_timeout_usec_)) {
      return false;
    }

    strm = std::unique_ptr<Stream>(new detail::SSLSocketStream(
        sock_, tls_session_, read_timeout_sec_, read_timeout_usec_,
        write_timeout_sec_, write_timeout_usec_));
    return true;
  }
#endif
  strm = std::unique_ptr<Stream>(
      new detail::SocketStream(sock_, read_timeout_sec_, read_timeout_usec_,
                               write_timeout_sec_, write_timeout_usec_));
  return true;
}

bool WebSocketClient::connect() {
  if (!is_valid_) { return false; }
  shutdown_and_close();

  Error error;
  sock_ = detail::create_client_socket(
      host_, std::string(), port_, AF_UNSPEC, false, false, nullptr, 5, 0,
      read_timeout_sec_, read_timeout_usec_, write_timeout_sec_,
      write_timeout_usec_, std::string(), error);

  if (sock_ == INVALID_SOCKET) { return false; }

  std::unique_ptr<Stream> strm;
  if (!create_stream(strm)) {
    shutdown_and_close();
    return false;
  }

  std::string selected_subprotocol;
  if (!detail::perform_websocket_handshake(*strm, host_, port_, path_, headers_,
                                           selected_subprotocol)) {
    shutdown_and_close();
    return false;
  }
  subprotocol_ = std::move(selected_subprotocol);

  Request req;
  req.method = "GET";
  req.path = path_;
  ws_ = std::unique_ptr<WebSocket>(
      new WebSocket(std::move(strm), req, false, websocket_ping_interval_sec_));
  return true;
}

ReadResult WebSocketClient::read(std::string &msg) {
  if (!ws_) { return Fail; }
  return ws_->read(msg);
}

bool WebSocketClient::send(const std::string &data) {
  if (!ws_) { return false; }
  return ws_->send(data);
}

bool WebSocketClient::send(const char *data, size_t len) {
  if (!ws_) { return false; }
  return ws_->send(data, len);
}

void WebSocketClient::close(CloseStatus status,
                                   const std::string &reason) {
  if (ws_) { ws_->close(status, reason); }
}

bool WebSocketClient::is_open() const { return ws_ && ws_->is_open(); }

const std::string &WebSocketClient::subprotocol() const {
  return subprotocol_;
}

void WebSocketClient::set_read_timeout(time_t sec, time_t usec) {
  read_timeout_sec_ = sec;
  read_timeout_usec_ = usec;
}

void WebSocketClient::set_write_timeout(time_t sec, time_t usec) {
  write_timeout_sec_ = sec;
  write_timeout_usec_ = usec;
}

void WebSocketClient::set_websocket_ping_interval(time_t sec) {
  websocket_ping_interval_sec_ = sec;
}

#ifdef CPPHTTPLIB_SSL_ENABLED

void WebSocketClient::set_ca_cert_path(const std::string &path) {
  ca_cert_file_path_ = path;
}

void WebSocketClient::set_ca_cert_store(tls::ca_store_t store) {
  ca_cert_store_ = store;
}

void
WebSocketClient::enable_server_certificate_verification(bool enabled) {
  server_certificate_verification_ = enabled;
}

#endif // CPPHTTPLIB_SSL_ENABLED

} // namespace ws

} // namespace httplib
