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, PHP 7, PHP 8)
socket_accept — Acepta una conexión de un socket
Descripción
Después de que se haya creado el socket socket
usando socket_create(), vinculado a un nombre con
socket_bind(), e indicado que escuche conexiones
con socket_listen(), esta función aceptará
conexiones entrantes sobre ese socket. Una vez que se realice una conexión
con éxito, se devolverá un nuevo recurso socket, que puede ser usado
para comunicación. Si hay múltiples conexiones en cola sobre
el socket se usará el primero. Si no hay conexiones
pendientes, socket_accept() bloqueará hasta
que que esté presente una conexión. Si socket
ha sido hecho como de no-bloqueo usando
socket_set_blocking() o
socket_set_nonblock(), se devolverá false.
El recurso socket devuelto por
socket_accept() puede no ser usado para aceptar nuevas
conexiones. Sin embargo, el socket de escucha original,
socket, permanece abierto y puede ser
reutilizado.
Valores devueltos
Devuelve un nuevo recurso socket en caso de éxito, o false en caso de error. El código
de error real se puede recuperar llamanado a
socket_last_error(). Este código de error se puede pasar a
socket_strerror() para obtener una explicación textual del
error.
Ver también
- socket_connect() - Inicia una conexión sobre un socket
- socket_listen() - Escucha una conexión sobre un socket
- socket_create() - Crear un socket (extremo de comunicación)
- socket_bind() - Vincula un nombre a un socket
- socket_strerror() - Devuelve una cadena que describe un error de socket
add a note
User Contributed Notes 7 notes
lars at opdenkamp dot eu ¶
16 years ago
Boylett ¶
16 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;
}
}
?>
Greg MacLellan ¶
20 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.
renmengyang567 at gmail dot com ¶
5 years ago
<explain>
This case is a very simple interaction between the TCP client side and the TCP server side
<?php
// create for simple-tcp-server
$sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
socket_bind($sock, '127.0.0.1',5000);
socket_listen($sock,1);
$clnt_sock = socket_accept($sock); //阻塞
$st = "hello world ^_^";
socket_write($clnt_sock, $st,strlen($st));
socket_close($clnt_sock);
socket_close($sock);
?>
<?php
//create for simple-tcp-client
$clnt_sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
socket_connect($clnt_sock, '127.0.0.1', 5000);
$ret= socket_read($clnt_sock, 1024);
print "from simple-tcp-server:".$ret.PHP_EOL;
socket_close($clnt_sock);
?>
<fruit>
from simple-tcp-server:hello world ^_^
gmkarl at gmail dot com ¶
17 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.
simon at 180solutions dot com ¶
19 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
mightyplow at gmail dot com ¶
10 years ago
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);
}
}
