socket_connect

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

socket_connect — Initiates a connection on a socket

Description

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

Initiate a connection to address using the Socket instance socket, which must be Socket instance created with socket_create().

Parameters

socket: A Socket instance created with socket_create().
address: The address parameter is either an IPv4 address in dotted-quad notation (e.g. 127.0.0.1) if socket is AF_INET, a valid IPv6 address (e.g. ::1) if IPv6 support is enabled and socket is AF_INET6 or the pathname of a Unix domain socket, if the socket family is AF_UNIX.
port: The port parameter is only used and is mandatory when connecting to an AF_INET or an AF_INET6 socket, and designates the port on the remote host to which a connection should be made.

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.

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

Changelog

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

Found A Problem?

Learn How To Improve This Page • Submit a Pull Request • Report a Bug

＋add a note

User Contributed Notes 11 notes

down

w at ff dot st ¶

21 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

tacapi at canela dot com ¶

7 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

greg at mtechsolutions dot ca ¶

21 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

jerrywilborn at gmail dot com ¶

15 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

Cedar Myers ¶

13 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

maganap ¶

16 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

vshih at yahoo ¶

15 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

rbarnes at fake dot com ¶

16 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

peter at videoripper dot org ¶

15 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

thewanderer ¶

13 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

-2

seymour@itsyourdomain ¶

21 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");
?>

＋add a note

socket_connect

Description

Parameters

Return Values

Changelog

See Also

Found A Problem?

User Contributed Notes 11 notes