socket_get_option

Gets socket options for the socket

&reftitle.description; ``array``int``false```socket_get_option` `Socket` `socket` `int` `level` `int` `option`

The `socket_get_option` function retrieves the value for the option specified by the `option` parameter for the specified `socket`.

&reftitle.parameters;

`socket`

- A `Socket` instance created with `socket_create` or `socket_accept`.

`level`

- The `level` parameter specifies the protocol level at which the option resides. For example, to retrieve options at the socket level, a `level` parameter of `SOL_SOCKET` would be used. Other levels, such as `TCP`, can be used by specifying the protocol number of that level. Protocol numbers can be found by using the `getprotobyname` function.

`option`

- ## Available Socket Options

  Option | Description | Type
  `SO_DEBUG` | Reports whether debugging information is being recorded. | `int`
  `SO_BROADCAST` | Reports whether transmission of broadcast messages is supported. | `int`
  `SO_REUSEADDR` | Reports whether local addresses can be reused. | `int`
  `SO_REUSEPORT` | Reports whether local ports can be reused. | `int`
  `SO_KEEPALIVE` | Reports whether connections are kept active with periodic transmission of messages. If the connected socket fails to respond to these messages, the connection is broken and processes writing to that socket are notified with a SIGPIPE signal. | `int`
  `SO_LINGER` | Reports whether the `socket` lingers on `socket_close` if data is present. By default, when the socket is closed, it attempts to send all unsent data. In the case of a connection-oriented socket, `socket_close` will wait for its peer to acknowledge the data. If `l_onoff` is non-zero and `l_linger` is zero, all the unsent data will be discarded and RST (reset) is sent to the peer in the case of a connection-oriented socket. On the other hand, if `l_onoff` is non-zero and `l_linger` is non-zero, `socket_close` will block until all the data is sent or the time specified in `l_linger` elapses. If the socket is non-blocking, `socket_close` will fail and return an error. | `array`. The array will contain two keys: `l_onoff` and `l_linger`.
  `SO_OOBINLINE` | Reports whether the `socket` leaves out-of-band data inline. | `int`
  `SO_SNDBUF` | Reports the size of the send buffer. | `int`
  `SO_RCVBUF` | Reports the size of the receive buffer. | `int`
  `SO_ERROR` | Reports information about error status and clears it. | `int` (cannot be set by `socket_set_option`)
  `SO_TYPE` | Reports the `socket` type (e.g. `SOCK_STREAM`). | `int` (cannot be set by `socket_set_option`)
  `SO_DONTROUTE` | Reports whether outgoing messages bypass the standard routing facilities. | `int`
  `SO_RCVLOWAT` | Reports the minimum number of bytes to process for `socket` input operations. | `int`
  `SO_RCVTIMEO` | Reports the timeout value for input operations. | `array`. The array will contain two keys: `sec` which is the seconds part on the timeout value and `usec` which is the microsecond part of the timeout value.
  `SO_SNDTIMEO` | Reports the timeout value specifying the amount of time that an output function blocks because flow control prevents data from being sent. | `array`. The array will contain two keys: `sec` which is the seconds part on the timeout value and `usec` which is the microsecond part of the timeout value.
  `SO_SNDLOWAT` | Reports the minimum number of bytes to process for `socket` output operations. | `int`
  `TCP_NODELAY` | Reports whether the Nagle TCP algorithm is disabled. | `int`
  `MCAST_JOIN_GROUP` | Joins a multicast group. | `array` with keys `"group"`, specifying a `string` with an IPv4 or IPv6 multicast address and `"interface"`, specifying either an interface number (type `int`) or a `string` with the interface name, like `"eth0"`. `0` can be specified to indicate the interface should be selected using routing rules. (can only be used in `socket_set_option`)
  `MCAST_LEAVE_GROUP` | Leaves a multicast group. | `array`. See `MCAST_JOIN_GROUP` for more information. (can only be used in `socket_set_option`)
  `MCAST_BLOCK_SOURCE` | Blocks packets arriving from a specific source to a specific multicast group, which must have been previously joined. | `array` with the same keys as `MCAST_JOIN_GROUP`, plus one extra key, `source`, which maps to a `string` specifying an IPv4 or IPv6 address of the source to be blocked. (can only be used in `socket_set_option`)
  `MCAST_UNBLOCK_SOURCE` | Unblocks (start receiving again) packets arriving from a specific source address to a specific multicast group, which must have been previously joined. | `array` with the same format as `MCAST_BLOCK_SOURCE`. (can only be used in `socket_set_option`)
  `MCAST_JOIN_SOURCE_GROUP` | Receive packets destined to a specific multicast group whose source address matches a specific value. | `array` with the same format as `MCAST_BLOCK_SOURCE`. (can only be used in `socket_set_option`)
  `MCAST_LEAVE_SOURCE_GROUP` | Stop receiving packets destined to a specific multicast group whose source address matches a specific value. | `array` with the same format as `MCAST_BLOCK_SOURCE`. (can only be used in `socket_set_option`)
  `IP_MULTICAST_IF` | The outgoing interface for IPv4 multicast packets. | Either `int` specifying the interface number or a `string` with an interface name, like `eth0`. The value `0` can be used to indicate the routing table is to used in the interface selection. The function `socket_get_option` returns an interface index. Note that, unlike the C API, this option does NOT take an IP address. This eliminates the interface difference between `IP_MULTICAST_IF` and `IPV6_MULTICAST_IF`.
  `IPV6_MULTICAST_IF` | The outgoing interface for IPv6 multicast packets. | The same as `IP_MULTICAST_IF`.
  `IP_MULTICAST_LOOP` | The multicast loopback policy for IPv4 packets enables or disables loopback of outgoing multicasts, which must have been previously joined. The effect differs, however, whether it applies on unixes or Windows, the former being on the receive path whereas the latter being on the send path. | `int` (either `0` or `1`). For `socket_set_option` any value will be accepted and will be converted to a boolean following the usual PHP rules.
  `IPV6_MULTICAST_LOOP` | Analogous to `IP_MULTICAST_LOOP`, but for IPv6. | `int`. See `IP_MULTICAST_LOOP`.
  `IP_MULTICAST_TTL` | The time-to-live of outgoing IPv4 multicast packets. This should be a value between 0 (don't leave the interface) and 255. The default value is 1 (only the local network is reached). | `int` between 0 and 255.
  `IPV6_MULTICAST_HOPS` | Analogous to `IP_MULTICAST_TTL`, but for IPv6 packets. The value -1 is also accepted, meaning the route default should be used. | `int` between -1 and 255.
  `SO_MARK` | Sets an identifier on the socket for packet filtering purpose on Linux. | `int`
  `SO_ACCEPTFILTER` | Adds an accept filter on the listened socket (FreeBSD/NetBSD). An accept filter kernel module needs to be loaded beforehand on FreeBSD (e.g. accf_http). | `string` name of the filter (length 15 max).
  `SO_USER_COOKIE` | Sets an identifier on the socket for packet filtering purpose on FreeBSD. | `int`
  `SO_RTABLE` | Sets an identifier on the socket for packet filtering purpose on OpenBSD. | `int`
  `SO_DONTTRUNC` | Retain unread data. | `int`
  `SO_WANTMORE` | Give a hint when more data is ready. | `int`
  `TCP_DEFER_ACCEPT` | Don't notify a listening socket until data is ready. | `int`
  `SO_INCOMING_CPU` | Gets/Sets the cpu affinity of a socket. | `int`
  `SO_MEMINFO` | Gets all the meminfo of a socket. | `int`
  `SO_BPF_EXTENSIONS` | Gets the supported BPF extensions by the kernel to attach to a socket. | `int`
  `SO_SETFIB` | Sets the route table (FIB) of a socket. (FreeBSD only) | `int`
  `SOL_FILTER` | Filters attributed to a socket. (Solaris/Illumos only) | `int`
  `TCP_KEEPCNT` | Sets the maximum number of keepalive probes TCP should send before dropping the connection. | `int`
  `TCP_KEEPIDLE` | Sets the time the connection needs to remain idle. | `int`
  `TCP_KEEPINTVL` | Sets the time between individual keepalive probes. | `int`
  `TCP_KEEPALIVE` | Sets the time the connection needs to remain idle. (macOS only) | `int`
  `TCP_NOTSENT_LOWAT` | Sets the limit number of unsent data in write queue by the socket stream. (Linux only) | `int`

&reftitle.returnvalues;

Returns the value of the given option, &return.falseforfailure;.

&reftitle.changelog;

&Version; | &Description;
&sockets.changelog.socket-param;

&reftitle.examples;

### `socket_get_option` example

    <?php
    $socket = socket_create_listen(1223);

    $linger = array('l_linger' => 1, 'l_onoff' => 1);
    socket_set_option($socket, SOL_SOCKET, SO_LINGER, $linger);

    var_dump(socket_get_option($socket, SOL_SOCKET, SO_REUSEADDR));
    ?>

&reftitle.seealso;

- `socket_create_listen`
- `socket_set_option`