International PHP Conference Berlin 2023

socket_listen

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

socket_listenListens for a connection on a socket

Description

socket_listen(Socket $socket, int $backlog = 0): bool

After the socket socket has been created using socket_create() and bound to a name with socket_bind(), it may be told to listen for incoming connections on socket.

socket_listen() is applicable only to sockets of type SOCK_STREAM or SOCK_SEQPACKET.

Parameters

socket

A Socket instance created with socket_create() or socket_addrinfo_bind()

backlog

A maximum of backlog incoming connections will be queued for processing. If a connection request arrives with the queue full the client may receive an error with an indication of ECONNREFUSED, or, if the underlying protocol supports retransmission, the request may be ignored so that retries may succeed.

Note:

The maximum number passed to the backlog parameter highly depends on the underlying platform. On Linux, it is silently truncated to SOMAXCONN. On win32, if passed SOMAXCONN, the underlying service provider responsible for the socket will set the backlog to a maximum reasonable value. There is no standard provision to find out the actual backlog value on this platform.

Return Values

Returns true on success or false on failure. The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error.

Changelog

Version Description
8.0.0 socket is a Socket instance now; previously, it was a resource.

See Also

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User Contributed Notes 1 note

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renmengyang567 at gmail dot com
3 years ago
<?php
// create for tcp
$sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
socket_bind($sock, '127.0.0.1',5000);
socket_listen($sock,1);
sleep(20);
?>

<fruit>
netstat  -ntpl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.0.1:5000          0.0.0.0:*               LISTEN      1839/php
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