Socket Functions
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
/**
* Listens for requests and forks on each connection
*/
$__server_listening = true;
error_reporting(E_ALL);
set_time_limit(0);
ob_implicit_flush();
declare(ticks = 1);
become_daemon();
/* nobody/nogroup, change to your host's uid/gid of the non-priv user */
change_identity(65534, 65534);
/* handle signals */
pcntl_signal(SIGTERM, 'sig_handler');
pcntl_signal(SIGINT, 'sig_handler');
pcntl_signal(SIGCHLD, 'sig_handler');
/* change this to your own host / port */
server_loop("127.0.0.1", 1234);
/**
* Change the identity to a non-priv user
*/
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;
}
}
/**
* Creates a server socket and listens for incoming client connections
* @param string $address The address to listen on
* @param int $port The port to listen on
*/
function server_loop($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;
}
}
}
/**
* Signal handler
*/
function sig_handler($sig)
{
switch($sig)
{
case SIGTERM:
case SIGINT:
exit();
break;
case SIGCHLD:
pcntl_waitpid(-1, $status);
break;
}
}
/**
* Handle a new client connection
*/
function handle_client($ssock, $csock)
{
GLOBAL $__server_listening;
$pid = pcntl_fork();
if ($pid == -1)
{
/* fork failed */
echo "fork failure!\n";
die;
}elseif ($pid == 0)
{
/* child process */
$__server_listening = false;
socket_close($ssock);
interact($csock);
socket_close($csock);
}else
{
socket_close($csock);
}
}
function interact($socket)
{
/* TALK TO YOUR CLIENT */
}
/**
* Become a daemon by forking and closing the parent
*/
function become_daemon()
{
$pid = pcntl_fork();
if ($pid == -1)
{
/* fork failed */
echo "fork failure!\n";
exit();
}elseif ($pid)
{
/* close the parent */
exit();
}else
{
/* child becomes our daemon */
posix_setsid();
chdir('/');
umask(0);
return posix_getpid();
}
}
?>
socket_accept
(PHP 4 >= 4.1.0, PHP 5)
socket_accept — Accepts a connection on a socket
Description
resource socket_accept
( resource
$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.
Return Values
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.
See Also
- socket_connect() - Initiates a connection on a socket
- socket_listen() - Listens for a connection on a socket
- socket_create() - Create a socket (endpoint for communication)
- socket_bind() - Binds a name to a socket
- socket_strerror() - Return a string describing a socket error
add a note
User Contributed Notes
socket_accept - [8 notes]
lars at opdenkamp dot eu ¶
5 years ago
Boylett ¶
5 years ago
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;
}
}
?>
Anonymous ¶
5 years ago
If you want to know the remote address ( ip address ) and the port of an incoming connection that has been accepted with socket_accept(), you can use socket_getpeername()
gmkarl at gmail dot com ¶
6 years ago
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.
Greg MacLellan ¶
9 years ago
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.
diogo at transoft dot com dot br ¶
9 years ago
Accepting a connection using php-sockets:
$fd = socket_create(AF_INET, SOCK_STREAM, 6 /* OR getprotobyname("TCP")*/);
$PORT = 5000;
socket_bind($fd, "0.0.0.0", $PORT);
while(true)
{
$remote_fd = socket_accept($fd);
remote_socket_client_handle($remote_fd);
}
It is simple!
galantonp at yahoo dot com ¶
6 years ago
socket_accept with timeout, seems to work for me on Apache/1.3.37 (FreeBSD 6.0) PHP/4.4.7.
Adapted from ScriptBlue at nyc dot rr dot com's post under socket_connect.
<?php
$socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
socket_bind($socket,$address,$port);
socket_listen($socket);
echo "Waiting for a connection\n";
$conn = false;
switch(@socket_select($r = array($socket), $w = array($socket), $e = array($socket), 60)) {
case 2:
echo "Connection refused\n";
break;
case 1:
echo "Connection accepted\n";
$conn = @socket_accept($socket);
break;
case 0:
echo "Connection timed out\n";
break;
}
if ($conn !== false) {
// communicate over $conn
}
?>
simon at 180solutions dot com ¶
8 years ago
>Accepting a connection using php-sockets:
>
>$fd = socket_create(AF_INET, SOCK_STREAM, 6 /* OR >getprotobyname("TCP")*/);
>
>$PORT = 5000;
>
>socket_bind($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