fsockopen

Open Internet or Unix domain socket connection

&reftitle.description; ``resource``false```fsockopen` `string` `hostname` `int` `port`-1 `int` `error_code`&null; `string` `error_message`&null; ``float``null```timeout`&null;

Initiates a socket connection to the resource specified by `hostname`.

PHP supports targets in the Internet and Unix domains as described in transports. A list of supported transports can also be retrieved using `stream_get_transports`.

The socket will by default be opened in blocking mode. You can switch it to non-blocking mode by using `stream_set_blocking`.

The function `stream_socket_client` is similar but provides a richer set of options, including non-blocking connection and the ability to provide a stream context.

&reftitle.parameters;

`hostname`

- If OpenSSL support is installed, you may prefix the `hostname` with either `ssl://` or `tls://` to use an SSL or TLS client connection over TCP/IP to connect to the remote host.

`port`

- The port number. This can be omitted and skipped with `-1` for transports that do not use ports, such as `unix://`.

`error_code`

- If provided, holds the system level error number that occurred in the system-level `connect()` call.

  If the value returned in `error_code` is `0` and the function returned &false;, it is an indication that the error occurred before the `connect()` call. This is most likely due to a problem initializing the socket.

`error_message`

- The error message as a string.

`timeout`

- The connection timeout, in seconds. When &null;, the default_socket_timeout &php.ini; setting is used.

  If you need to set a timeout for reading/writing data over the socket, use `stream_set_timeout`, as the `timeout` parameter to `fsockopen` only applies while connecting the socket.

&reftitle.returnvalues;

`fsockopen` returns a file pointer which may be used together with the other file functions (such as `fgets`, `fgetss`, `fwrite`, `fclose`, and `feof`). If the call fails, it will return &false;

&reftitle.errors;

Throws `E_WARNING` if `hostname` is not a valid domain.

&reftitle.changelog;

&Version; | &Description;
8.0.0 | `timeout` is nullable now.

&reftitle.examples;

### `fsockopen` Example

    <?php
    $fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);
    if (!$fp) {
        echo "$errstr ($errno)<br />\n";
    } else {
        $out = "GET / HTTP/1.1\r\n";
        $out .= "Host: www.example.com\r\n";
        $out .= "Connection: Close\r\n\r\n";
        fwrite($fp, $out);
        while (!feof($fp)) {
            echo fgets($fp, 128);
        }
        fclose($fp);
    }
    ?>

### Using UDP connection

The example below shows how to retrieve the day and time from the UDP service "daytime" (port 13) in your own machine.

    <?php
    $fp = fsockopen("udp://127.0.0.1", 13, $errno, $errstr);
    if (!$fp) {
        echo "ERROR: $errno - $errstr<br />\n";
    } else {
        fwrite($fp, "\n");
        echo fread($fp, 26);
        fclose($fp);
    }
    ?>

&reftitle.notes;

Depending on the environment, the Unix domain or the optional connect timeout may not be available.

UDP sockets will sometimes appear to have opened without an error, even if the remote host is unreachable. The error will only become apparent when you read or write data to/from the socket. The reason for this is because UDP is a "connectionless" protocol, which means that the operating system does not try to establish a link for the socket until it actually needs to send or receive data.

&ipv6.brackets;
&reftitle.seealso;

- `pfsockopen`
- `stream_socket_client`
- `stream_set_blocking`
- `stream_set_timeout`
- `fgets`
- `fgetss`
- `fwrite`
- `fclose`
- `feof`
- `socket_connect`
- The Curl extension