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socket_accept

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

socket_acceptAccetta una connessione su un socket

Descrizione

socket_accept(resource $socket): resource
Avviso

Questa funzione è SPERIMENTALE. Ovvero, il comportamento di questa funzione, il nome di questa funzione, in definitiva tutto ciò che è documentato qui può cambiare nei futuri rilasci del PHP senza preavviso. Siete avvisati, l'uso di questa funzione è a vostro rischio.

Dopo la creazione del socket socket con socket_create(), l'assegnazione di un nome con socket_bind(), e averlo messo in attesa di connessione con socket_listen(), con questa funzione si inizia ad accettare le richieste di connessione su quel socket. Una volta avuta una connessione, la funzione restituisce un nuovo socket che può essere usato per la comunicazione. Se vi sono diverse richieste di connessioni pendenti verrà utilizzata la prima. Viceversa se non vi sono richieste in attesa, la funzione socket_accept() si blocca in attesa di una richiesta. Se il socket è stato configurato "non-blocking" con socket_set_blocking() o con socket_set_nonblock(), la funzione restituirà false.

La risorsa socket restituita da socket_accept() non può essere utilizzata per acquisire nuove connesioni. Per questo scopo occorre continuare ad usare il socket originale, indicato in socket, che rimane aperto.

La funzione restistuisce una risorsa di tipo socket se ha successo, oppure false se si verifica un errore. Il codice di errore può essere recuperato chiamando la funzione socket_last_error(). Questo codice può essere passato a socket_strerror() per ottenere una descrizione dell'errore.

Vedere anche socket_bind(), socket_connect(), socket_listen(), socket_create() e socket_strerror().

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User Contributed Notes 7 notes

up
24
lars at opdenkamp dot eu
16 years ago
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();

}
}

?>
up
18
Boylett
15 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;
}
}

?>
up
4
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.
up
2
renmengyang567 at gmail dot com
4 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 ^_^
up
-1
gmkarl at gmail dot com
16 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.
up
-7
simon at 180solutions dot com
18 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
up
-8
mightyplow at gmail dot com
9 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);
}
}
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