Last updated: Fri, 10 Oct 2008

stream_socket_pair

(PHP 5 >= 5.1.0)

stream_socket_pair — Creates a pair of connected, indistinguishable socket streams

Description

array stream_socket_pair ( int $domain , int $type , int $protocol )

stream_socket_pair() creates a pair of connected, indistinguishable socket streams. This function is commonly used in IPC (Inter-Process Communication).

Parameters

domain: The protocol family to be used: STREAM_PF_INET, STREAM_PF_INET6 or STREAM_PF_UNIX
type: The type of communication to be used: STREAM_SOCK_DGRAM, STREAM_SOCK_RAW, STREAM_SOCK_RDM, STREAM_SOCK_SEQPACKET or STREAM_SOCK_STREAM
protocol: The protocol to be used: STREAM_IPPROTO_ICMP, STREAM_IPPROTO_IP, STREAM_IPPROTO_RAW, STREAM_IPPROTO_TCP or STREAM_IPPROTO_UDP

Note: Please consult the Streams constant list for further details on each constant.

Return Values

Returns an array with the two socket resources on success, or FALSE on failure.

Examples

Example #1 A stream_socket_pair() example

This example shows the basic usage of stream_socket_pair() in Inter-Process Comunication.


<?php

$sockets = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
$pid     = pcntl_fork();

if ($pid == -1) {
     die('could not fork');

} else if ($pid) {
     /* parent */
    fclose($sockets[0]);

    fwrite($sockets[1], "child PID: $pid\n");
    echo fgets($sockets[1]);

    fclose($sockets[1]);

} else {
    /* child */
    fclose($sockets[1]);

    fwrite($sockets[0], "message from child\n");
    echo fgets($sockets[0]);

    fclose($sockets[0]);
}

?>

The above example will output something similar to:

child PID: 1378
message from child

Notes

Note: This function is not implemented on Windows platforms.

add a note User Contributed Notes
stream_socket_pair

Till
02-Aug-2007 09:47


This is some freak-example how to use this feature to fork to a

bc-command on a Solaris-Server:



<?

$sockets=stream_socket_pair(STREAM_PF_UNIX,STREAM_SOCK_STREAM,

                                                STREAM_IPPROTO_IP);

passthru('

    perl -e \'

        use strict; my ($x,@x);

        open(STDIN,"-|","/bin/pfiles $$");

        while (<>) { $x=$1 if(/^ +([0-9]+):/); push(@x,$x) if(/AF_UNIX/); }

        print "Starting bc -l 0<&$x[1] 1>&$x[1] $x[0]<&- $x[0]>&- ...\n\n";

        exec("bash","-c","bc -l 0<&$x[1] 1>&$x[1] $x[0]<&- $x[0]>&- &");\'');



fclose($sockets[0]);



fwrite($sockets[1],"666*999\n");

print "666*999 = ".fgets($sockets[1])."\n";



fwrite($sockets[1],"./696\n");

print "./696 = ".fgets($sockets[1])."\n";



fwrite($sockets[1],"quit\n");

fclose($sockets[1]);

?>



The big problem is, that there seems to be no way to obtain the real

filedescriptors of the two sockets, but you need them, if you want to

redirect some program's STDOUT and STDIN to one of these sockets.



I misused the /bin/pfiles command on a Solaris UNIX to find them.

Another (non-php-) problem is, that, if you use php in Apache, there

will be already a lot of open filedescriptors and the filedescriptors

of the sockets will be greater than 9. That's why I had to use the bash.



I think it is awful, but it works. Would be great, if someone

would come up with a better idea.

add a note

stream_socket_recvfrom

stream_socket_get_name

Last updated: Fri, 10 Oct 2008