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socket_connect

(PHP 4 >= 4.1.0, PHP 5)

socket_connectInitiates a connection on a socket

Description

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

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

Parameters

socket

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.

See Also

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User Contributed Notes 13 notes

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5
greg at mtechsolutions dot ca
11 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).
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3
seymour@itsyourdomain
10 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");
?>
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3
w at ff dot st
11 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).
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3
peter at videoripper dot org
4 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.
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1
vshih at yahoo
5 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.
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1
maganap
5 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
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2
Cedar Myers
3 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)//...
?>
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1
jerrywilborn at gmail dot com
5 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);

}
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1
rbarnes at fake dot com
6 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;     
}
?>
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0
thewanderer
3 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.
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-1
telefoontoestel at home
10 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 ;-)
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-2
logan at voerthegame dot com
12 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";
            }
?>
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-3
mike at fserve dot us
6 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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