PHP Manual
Socket Functions
Creates a pair of indistinguishable sockets and stores them in an array

socket_create_pair

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

socket_create_pair — Creates a pair of indistinguishable sockets and stores them in an array

Description

socket_create_pair(
    int $domain,
    int $type,
    int $protocol,
    array &$pair
): bool

socket_create_pair() creates two connected and indistinguishable sockets, and stores them in pair. This function is commonly used in IPC (InterProcess Communication).

Parameters

domain

The domain parameter specifies the protocol family to be used by the socket. See socket_create() for the full list.

type

The type parameter selects the type of communication to be used by the socket. See socket_create() for the full list.

protocol

The protocol parameter sets the specific protocol within the specified domain to be used when communicating on the returned socket. The proper value can be retrieved by name by using getprotobyname(). If the desired protocol is TCP, or UDP the corresponding constants SOL_TCP, and SOL_UDP can also be used.

See socket_create() for the full list of supported protocols.

pair

Reference to an array in which the two Socket instances will be inserted.

Return Values

Returns true on success or false on failure.

Changelog

Version	Description
8.0.0	`pair` is a reference to an array of Socket instances now; previously, it was a reference to an array of resources.

Examples

Example #1 socket_create_pair() example


<?php
$sockets = array();

/* On Windows we need to use AF_INET */
$domain = (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN' ? AF_INET : AF_UNIX);

/* Setup socket pair */
if (socket_create_pair($domain, SOCK_STREAM, 0, $sockets) === false) {
    echo "socket_create_pair failed. Reason: ".socket_strerror(socket_last_error());
}
/* Send and Receive Data */
if (socket_write($sockets[0], "ABCdef123\n", strlen("ABCdef123\n")) === false) {
    echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($sockets[0]));
}
if (($data = socket_read($sockets[1], strlen("ABCdef123\n"), PHP_BINARY_READ)) === false) {
    echo "socket_read() failed. Reason: ".socket_strerror(socket_last_error($sockets[1]));
}
var_dump($data);

/* Close sockets */
socket_close($sockets[0]);
socket_close($sockets[1]);
?>

Example #2 socket_create_pair() IPC example


<?php
$ary = array();
$strone = 'Message From Parent.';
$strtwo = 'Message From Child.';

if (socket_create_pair(AF_UNIX, SOCK_STREAM, 0, $ary) === false) {
    echo "socket_create_pair() failed. Reason: ".socket_strerror(socket_last_error());
}
$pid = pcntl_fork();
if ($pid == -1) {
    echo 'Could not fork Process.';
} elseif ($pid) {
    /*parent*/
    socket_close($ary[0]);
    if (socket_write($ary[1], $strone, strlen($strone)) === false) {
        echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($ary[1]));
    }
    if (socket_read($ary[1], strlen($strtwo), PHP_BINARY_READ) == $strtwo) {
        echo "Received $strtwo\n";
    }
    socket_close($ary[1]);
} else {
    /*child*/
    socket_close($ary[1]);
    if (socket_write($ary[0], $strtwo, strlen($strtwo)) === false) {
        echo "socket_write() failed. Reason: ".socket_strerror(socket_last_error($ary[0]));
    }
    if (socket_read($ary[0], strlen($strone), PHP_BINARY_READ) == $strone) {
        echo "Received $strone\n";
    }
    socket_close($ary[0]);
}
?>