PHP how to connect with sockets and read the response?

Question

The title explains it all...

How can i connect to an IP using tcp protocol and read/get the response? I have searched a lot but i didnt find any solution.

$socket = stream_socket_server("tcp://127.0.0.1:22", $errno, $errstr);
if (!$socket) {
  echo "$errstr ($errno)<br />\n";
} else {
  while ($conn = stream_socket_accept($socket)) {
echo fread($conn, 26);
    fclose($conn);
  }
  fclose($socket);
}

is this code ok? Does the job? Because it seems it doesn't do the job...

Thanks in advance

Answer 1

As suggested by others; avoid using port 22. I recommend using an obscure (unused) socket port number > 1024 such as 4444. Anything below 1024 normally requires root access. If you need to test connectivity for 22 have your server script run additional functions.

As for sending a response back to the connected client use stream_socket_recvfrom($socket, $length, 0, $peer) instead of fread()

Then on the client side add a response listener:

client.php

$socket = stream_socket_client('tcp://127.0.0.1:4444');
if ($socket) {
    $sent = stream_socket_sendto($socket, 'message');
    if ($sent > 0) {
        $server_response = fread($socket, 4096);
        echo $server_response;
    }
} else {
    echo 'Unable to connect to server';
}
stream_socket_shutdown($socket, STREAM_SHUT_RDWR);

server.php

$conn = stream_socket_server('tcp://127.0.0.1:4444');
while ($socket = stream_socket_accept($conn)) {
    $pkt = stream_socket_recvfrom($socket, 1500, 0, $peer);
    if (false === empty($pkt)) {
        stream_socket_sendto($socket, 'Received pkt ' . $pkt, 0, $peer);
    }
    fclose($socket);
    usleep(10000); //100ms delay
}
stream_socket_shutdown($conn, \STREAM_SHUT_RDWR);

Run server.php which will listen in an endless loop listening for a non-empty packet once server.php receives a packet it will respond back to the connected client with the received packet.

Then execute client.php which will send 'message' to server.php Once sent it will then retrieve and echo the response from server.php which should read 'Received pkt message'