PHP - Manual: socket_connect

2024-12-22

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socket_connect

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

socket_connect — 开启一个套接字连接

说明

socket_connect(Socket $socket, string $address, ?int $port = null): bool

使用 Socket 实例 socket 发起到 address 的连接，该实例必须要求是用 socket_create() 创建的 Socket 有效的套接字资源实例。

参数

socket: 由 socket_create() 创建的 Socket 实例。
address: 如果参数 socket 是 AF_INET，那么参数 address 则可以是一个点分四组表示法（例如 127.0.0.1 ）的 IPv4 地址；如果支持 IPv6 并且 socket 是 AF_INET6，那么 address 也可以是有效的 IPv6 地址（例如 ::1）；如果套接字类型为 AF_UNIX ，那么 address 也可以是一个 Unix 套接字。
port: 参数 port 仅仅用于 AF_INET 和 AF_INET6 套接字连接的时候，并且是在此情况下是需要强制说明连接对应的远程服务器上的端口号。

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。

注意:
If the socket is non-blocking then this function returns false with an error Operation now in progress.

更新日志

版本	说明
8.0.0	现在 `socket` 是 Socket 实例，之前是 resource。
8.0.0	`port` 允许为空。

参见

socket_bind() - 给套接字绑定名字
socket_listen() - Listens for a connection on a socket
socket_create() - 创建一个套接字（通讯节点）
socket_last_error() - Returns the last error on the socket
socket_strerror() - Return a string describing a socket error

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User Contributed Notes 14 notes

down

w at ff dot st ¶

18 years ago


man page for connect :
 EINPROGRESS
The socket is non-blocking and the connection cannot be completed immediately.  It is possible to select(2) or poll(2) for completion by selecting the socket for writing. After select indicates  writability,  use  getsockopt(2)  to read the SO_ERROR option at level SOL_SOCKET to determine whether connect completed successfully (SO_ERROR is zero) or unsuccessfully (SO_ERROR is one of the usual error codes listed here, explaining the reason for the failure).

use socket_getoption($socket,SOL_SOCKET,SO_ERROR) . If you get value 115, it is connecting. If you get value different than 115 and 0, that means that an error has occured (see what error with socket_strerror()).

However, I don't know how does that works under Windows, maybe it wont work at all. It is supposed to work under Linux (man pages said that).

down

jerrywilborn at gmail dot com ¶

12 years ago


This will print the banner from a true 'telnet' server (router, switch, host, etc).

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_connect($socket, '127.0.0.1', 23);

while (TRUE) {
        $r = array($socket);
        $c = socket_select($r, $w = NULL, $e = NULL, 5);

        foreach ($r as $read_socket) {
                if ($r = negotiate($read_socket)) {
                        var_dump($r);
                        exit;
                }
        }
}

function negotiate ($socket) {
        socket_recv($socket, $buffer, 1024, 0);

        for ($chr = 0; $chr < strlen($buffer); $chr++) {
                if ($buffer[$chr] == chr(255)) {

                        $send = (isset($send) ? $send . $buffer[$chr] : $buffer[$chr]);

                        $chr++;
                        if (in_array($buffer[$chr], array(chr(251), chr(252)))) $send .= chr(254);
                        if (in_array($buffer[$chr], array(chr(253), chr(254)))) $send .= chr(252);

                        $chr++;
                        $send .= $buffer[$chr];
                } else {
                        break;
                }
        }

        if (isset($send)) socket_send($socket, $send, strlen($send), 0);
        if ($chr - 1 < strlen($buffer)) return substr($buffer, $chr);

}

down

maganap ¶

13 years ago


Hi there!

For the TCP connections: socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
In case you're having problems in socket_connect() with socket_strerror() = "Permission denied", you may be having a SELinux config issue.

Check if SELinux is enabled:
# /usr/sbin/sestatus -v
In case it is, you can just type the command:
# setsebool httpd_can_network_connect=1

That's it... I read you had to reboot, but I didn't and it worked fine anyway. More info, you may check:
http://arkiv.netbsd.se/?ml=squirrelmail-users&a=2005-11&t=1523021

down

rbarnes at fake dot com ¶

13 years ago


Here is an example of a non-blocking connect which should perform quite a bit faster than the one posted by Seymour below:


<?php

function msConnectSocket($remote, $port, $timeout = 30) {

        # this works whether $remote is a hostname or IP

        $ip = "";

        if( !preg_match('/^\d+\.\d+\.\d+\.\d+$/', $remote) ) {

            $ip = gethostbyname($remote);

            if ($ip == $remote) {

                $this->errstr = "Error Connecting Socket: Unknown host";

                return NULL;

            }

        } else $ip = $remote;


        if (!($this->_SOCK = @socket_create(AF_INET, SOCK_STREAM, SOL_TCP))) {

            $this->errstr = "Error Creating Socket: ".socket_strerror(socket_last_error());

            return NULL;

        }


        socket_set_nonblock($this->_SOCK);


        $error = NULL;

        $attempts = 0;

        $timeout *= 1000;  // adjust because we sleeping in 1 millisecond increments

        $connected;

        while (!($connected = @socket_connect($this->_SOCK, $remote, $port+0)) && $attempts++ < $timeout) {

            $error = socket_last_error();

            if ($error != SOCKET_EINPROGRESS && $error != SOCKET_EALREADY) {

                $this->errstr = "Error Connecting Socket: ".socket_strerror($error);

                socket_close($this->_SOCK);

                return NULL;

            }

            usleep(1000);

        }


        if (!$connected) {

            $this->errstr = "Error Connecting Socket: Connect Timed Out After $timeout seconds. ".socket_strerror(socket_last_error());

            socket_close($this->_SOCK);

            return NULL;

        }

        

        socket_set_block($this->_SOCK);


        return 1;      

}

?>

down

greg at mtechsolutions dot ca ¶

19 years ago


If you're using non-blocking, be sure not to turn it on until after you connect, otherwise you will get the mesasge:

PHP Warning:  socket_connect() unable to connect [115]: Operation now in progress in file.php on line 123

and socket_connect() will return false (even though it will connect).

down

peter at videoripper dot org ¶

12 years ago


This will give you a simple port-checker.

Note that on production-machines, you might want to alter the error reporting-level, 
since unsuccessful connects will give you a "No connection could be made because 
the target machine actively refused it"-error in the log.

Under Windows, make sure you enable the php_sockets.dll extension in your php.ini.

<?php  
  $address=$_SERVER['REMOTE_ADDR'];
  
  if (isset($_REQUEST['port']) and
      (!strlen($_REQUEST['port'])==0))
    $port=$_REQUEST['port'];
  else
    unset($port);
    
  if (isset($port) and
      ($socket=socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) and
      (socket_connect($socket, $address, $port)))
    {
      $text="Connection successful on IP $address, port $port";
      socket_close($socket);
    }
  else
    $text="Unable to connect<pre>".socket_strerror(socket_last_error())."</pre>";
    
  echo "<html><head></head><body>".
       $text.
       "</body></html>";
?>

Greetz,

Peter.

down

vshih at yahoo ¶

13 years ago


rbarnes' tip is helpful, but I found that I needed to add a check for SOCKET_EISCONN in the while loop:

    ...
    $error = socket_last_error();

    if ($error == SOCKET_EISCONN) {
        $connected = true;
        break;
    }
    ...

At least on Mac OS X 10.5.

down

Cedar Myers ¶

11 years ago


It seems that timeout values can be specified by setting the SO_SNDTIMEO option before calling socket_connect():


<?php

socket_set_option($socket, SOL_SOCKET, SO_SNDTIMEO, array('sec' => $seconds, 'usec' => $milliseconds));

socket_connect($socket, $address, $port)//...

?>

down

tacapi at canela dot com ¶

5 years ago


Just a heads up guys: make sure you're passing a properly formatted IP to your ping and socket functions.

E.g.: 192.168.0.18 -> OK
      192.168.0.018 -> Will result in "Unkwown host"

I was getting a 11004 error and could not solve it until I realized that was the problem.

(Pode ser que seja útil para alguém: verifique que o IP passado por parâmetro para o seu ping e funções socket é um endereço de IP corretamente formatado)

down

-2

seymour@itsyourdomain ¶

18 years ago


here's how you can implement timeouts with the socket functions. 

this example works for blocking sockets but will work for both blocking and nonblocking with minor modifications. first call to connect in nonblocking mode returns 115 EINPROGRESS, additional calls return 114 EALREADY if the connection has not already failed or succeeded. once the connection succeeds, the socket resource will be returned.

<?
    $host = "127.0.0.1";
    $port = "80";
    $timeout = 15;  //timeout in seconds

    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)
      or die("Unable to create socket\n");

    socket_set_nonblock($socket)
      or die("Unable to set nonblock on socket\n");

    $time = time();
    while (!@socket_connect($socket, $host, $port))
    {
      $err = socket_last_error($socket);
      if ($err == 115 || $err == 114)
      {
        if ((time() - $time) >= $timeout)
        {
          socket_close($socket);
          die("Connection timed out.\n");
        }
        sleep(1);
        continue;
      }
      die(socket_strerror($err) . "\n");
    }

    socket_set_block($this->socket)
      or die("Unable to set block on socket\n");
?>

down

-3

thewanderer ¶

11 years ago


Note that as of PHP5.3 it is not possible to send IPv6 multicast to link-local addresses, because socket_connect() is just a trimmed-down version of connect() and does not support passing sin6_scope_id - the scope ID is required when sending packets to ff02::1 (all-nodes), for example.
At first I thought I needed to bind the socket to the device using SO_BINDTODEVICE option (undefined constant in PHP - use numeric value 25), but it makes no difference, only requires root privileges to produce no usable results.
Also, if you think you are sending multicast packets to link local addresses just because socket_sendto() returns a positive number of bytes, you might be wrong - just returning success does not mean that packets are sent over any link at all. In my test case I was sending to ff02::1, I could detect no errors, but Wireshark showed no packets. They end up in void.
This is irrelevant to the handling of local reception sockets, so UDP listeners should still work as usual with IPv6/UDP. You might want to resort to C for implementing multicasters, though.

down

-7

logan at voerthegame dot com ¶

19 years ago


I had the same problem with the timeout, and i applied this solution.


It works only on linux PHP, i make a ping to the ip before connect the socket.....


<?php

$address = gethostbyname ($ip);

        $command = "ping -c 1 " . $address;  

        $r = exec($command);  

          if ($r[0]=="r")

          {        

            $socket = socket_create (AF_INET, SOCK_STREAM, 0);

            if ($socket < 0) {

                echo "socket_create() failed: reason: " . socket_strerror ($socket) . "\n";

            } else {

                echo "OK.\n";

            }

?>

down

-6

telefoontoestel at home ¶

18 years ago


In reply to the function socket_raw_connect posted by "net_del at freemail dot ru". In the function you give a return value and afterwords you try to close the connection. That won't ever work. I think you want to alter your code ;-)

down

-10

mike at fserve dot us ¶

14 years ago


This probably sounds like common sense, but it is something nobody i asked thought of... you can't bind the socket to localhost, you must bind it to either the IP your router assigns you, or your public IP address. If you bind to localhost, it will give an invalid resource error.

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官方地址：https://www.php.net/manual/en/function.socket-connect.php

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socket_connect

说明

参数

返回值

更新日志

参见

User Contributed Notes 14 notes