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(PHP 4 >= 4.1.0, PHP 5)
socket_accept — Accepts a connection on a socket
$socket
)
After the socket socket
has been created
using socket_create() , bound to a name with
socket_bind() , and told to listen for connections
with socket_listen() , this function will accept
incoming connections on that socket. Once a successful connection
is made, a new socket resource is returned, which may be used
for communication. If there are multiple connections queued on
the socket, the first will be used. If there are no pending
connections, socket_accept() will block until
a connection becomes present. If socket
has been made non-blocking using
socket_set_blocking() or
socket_set_nonblock() , FALSE
will be returned.
The socket resource returned by
socket_accept() may not be used to accept new
connections. The original listening socket
socket
, however, remains open and may be
reused.
socket
A valid socket resource created with socket_create() .
Returns a new socket resource on success, or FALSE
on error. The actual
error code can be retrieved by calling
socket_last_error() . This error code may be passed to
socket_strerror() to get a textual explanation of the
error.
[#1] mightyplow at gmail dot com [2014-05-18 14:47:30]
In order to make many clients connectable to the server, you have to set the accepted socket also to non-blocking. Otherwise the accepted connection will block further incoming connections.
while (true) {
$newSock = @socket_accept($sock);
if ($newSock) {
echo 'client connected';
socket_set_nonblock($newSock);
}
}
[#2] Boylett [2008-04-18 09:01:29]
If you want to have multiple clients on a server you will have to use non blocking.
<?php
$clients = array();
$socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
socket_bind($socket,'127.0.0.1',$port);
socket_listen($socket);
socket_set_nonblock($socket);
while(true)
{
if(($newc = socket_accept($socket)) !== false)
{
echo "Client $newc has connected\n";
$clients[] = $newc;
}
}
?>
[#3] lars at opdenkamp dot eu [2008-01-29 04:35:53]
If you want to make a daemon process that forks on each client connection, you'll find out that there's a bug in PHP. The child processes send SIGCHLD to their parent when they exit but the parent can't handle signals while it's waiting for socket_accept (blocking).
Here is a piece of code that makes a non-blocking forking server.
#!/usr/bin/php -q
<?php
$__server_listening = true;
error_reporting(E_ALL);
set_time_limit(0);
ob_implicit_flush();
declare(ticks = 1);
become_daemon();
change_identity(65534, 65534);
pcntl_signal(SIGTERM, 'sig_handler');
pcntl_signal(SIGINT, 'sig_handler');
pcntl_signal(SIGCHLD, 'sig_handler');
server_loop("127.0.0.1", 1234);
function change_identity( $uid, $gid )
{
if( !posix_setgid( $gid ) )
{
print "Unable to setgid to " . $gid . "!\n";
exit;
}
if( !posix_setuid( $uid ) )
{
print "Unable to setuid to " . $uid . "!\n";
exit;
}
}
function server_loop($address, $port)
{
GLOBAL $__server_listening;
if(($sock = socket_create(AF_INET, SOCK_STREAM, 0)) < 0)
{
echo "failed to create socket: ".socket_strerror($sock)."\n";
exit();
}
if(($ret = socket_bind($sock, $address, $port)) < 0)
{
echo "failed to bind socket: ".socket_strerror($ret)."\n";
exit();
}
if( ( $ret = socket_listen( $sock, 0 ) ) < 0 )
{
echo "failed to listen to socket: ".socket_strerror($ret)."\n";
exit();
}
socket_set_nonblock($sock);
echo "waiting for clients to connect\n";
while ($__server_listening)
{
$connection = @socket_accept($sock);
if ($connection === false)
{
usleep(100);
}elseif ($connection > 0)
{
handle_client($sock, $connection);
}else
{
echo "error: ".socket_strerror($connection);
die;
}
}
}
function sig_handler($sig)
{
switch($sig)
{
case SIGTERM:
case SIGINT:
exit();
break;
case SIGCHLD:
pcntl_waitpid(-1, $status);
break;
}
}
function handle_client($ssock, $csock)
{
GLOBAL $__server_listening;
$pid = pcntl_fork();
if ($pid == -1)
{
echo "fork failure!\n";
die;
}elseif ($pid == 0)
{
$__server_listening = false;
socket_close($ssock);
interact($csock);
socket_close($csock);
}else
{
socket_close($csock);
}
}
function interact($socket)
{
}
function become_daemon()
{
$pid = pcntl_fork();
if ($pid == -1)
{
echo "fork failure!\n";
exit();
}elseif ($pid)
{
exit();
}else
{
posix_setsid();
chdir('/');
umask(0);
return posix_getpid();
}
}
?>
[#4] gmkarl at gmail dot com [2007-05-22 09:15:16]
Be aware signal handler functions set with pcntl_signal are not called while a socket is blocking waiting for a connection; the signal is absorbed silently and the handler called when a connection is made.
[#5] simon at 180solutions dot com [2005-05-16 08:11:25]
>Accepting a connection using php-sockets:
>
>$fd = socket_create(AF_INET, SOCK_STREAM, 6 );
>
>$PORT = 5000;
>
>socket_bind($fd, "0.0.0.0", $PORT);
>
>while(true)
>{
>$remote_fd = socket_accept($fd);
>
>remote_socket_client_handle($remote_fd);
>
>}
>
>It is simple!
This example doesn't work. You have to call socket_listen($fd) after your bind in order to accept incoming connections.
Simon
[#6] Greg MacLellan [2003-12-11 12:49:14]
The socket returned by this resource will be non-blocking, regardless of what the listening socket is set to. This is actually true for all FCNTL modifiers.