socket_bind()

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

把socket绑定在一个IP地址和端口上

说明

socket_bind(resource $socket,string $address[,int $port= 0]): bool

绑定$address到$socket。该操作必须是在使用socket_connect()或者socket_listen()建立一个连接之前。

参数

$socket

用socket_create()创建的一个有效的套接字资源。

$address

如果套接字是AF_INET族，那么$address必须是一个四点分法的 IP 地址（例如127.0.0.1）。

如果套接字是AF_UNIX族，那么$address是 Unix 套接字一部分（例如/tmp/my.sock）。

$port（可选）

参数$port仅仅用于AF_INET套接字连接的时候，并且指定连接中需要监听的端口号。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

错误代码会传入socket_last_error()，如果将此参数传入socket_strerror()则可以得到错误的文字说明。

范例

使用socket_bind()来设置套接字资源地址

<?php
// Create a new socket
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);

// An example list of IP addresses owned by the computer
$sourceips['kevin']    = '127.0.0.1';
$sourceips['madcoder'] = '127.0.0.2';

// Bind the source address
socket_bind($sock, $sourceips['madcoder']);

// Connect to destination address
socket_connect($sock, '127.0.0.1', 80);

// Write
$request = 'GET / HTTP/1.1' . "\r\n" .
           'Host: example.com' . "\r\n\r\n";
socket_write($sock, $request);

// Close
socket_close($sock);
?>

注释

Note:

该函数必须在socket_connect()之前使用。

Windows 9x/ME 兼容性注意点：如果尝试绑定套接字资源到一个错误的地址，而这个地址不是本机的地址，那么socket_last_error()可能会返回一个无效的错误代码。

参见

• socket_connect()开启一个套接字连接
• socket_listen()侦听套接字上的连接
• socket_create()创建一个套接字（通讯节点）
• socket_last_error()返回套接字上的最后一个错误
• socket_strerror()返回一个描述套接字错误的字符串

If you want to reuse address and port, and get rid of error: unable to bind, address already in use, you have to use socket_setopt (check actual spelling for this function in you PHP verison) before calling bind:
<?php
if (!socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1)) {
  echo socket_strerror(socket_last_error($sock));
  exit;
}
?>
This solution was found by 
Christophe Dirac. Thank you Christophe!

Regarding previous post:
"0" has address is no different from "0.0.0.0"
127.0.0.1 -> accept only from local host
w.x.y.z (valid local IP) -> accep only from this network
0.0.0.0 -> accept from anywhere

Use 0 for port to bind a random (free) port for incoming connections:
socket_bind ($socket, $bind_address, 0);
socket_getsockname($socket, $socket_address, $socket_port);
socket_listen($socket);
...
$socket_port contains the assigned port, you might want to send it to a remote client connecting. Tested with php 5.03.

The aforementioned tidbit about using NULL to bind to all addresses did not work for me, as I would receive an error about unknown address. Using a 0 worked for me:
socket_bind ($socket, 0, $port)
This also allows you to receive UDP broadcasts, which is what I had been trying to figure out.

When doing Unix sockets, it might be necessary to chmod the socket file so as to give Write permission to Group and/or Others. Otherwise, only the owner is allowed to write data into the stream.
Example:
<?php
$sockpath = '/tmp/my.sock';
socket_bind($socket, $sockpath);
//here: write-only (socket_send) to others, only owner can fetch data.
chmod($sockpath, 0702);
?>

It appears for the $address parameter:
'127.0.0.1'
accepts clients from localhost (eg. 127.0.0.1)
'0.0.0.0'
accepts clients from localhost, and the server's network (eg. 127.0.0.1, 192.168.2.5, 10.20.30.40)
'0' or 0
accepts clients from localhost, the server's network, and external networks (eg. 127.0.0.1, 192.168.2.5, 10.20.30.40, 209.85.169.99)