Question

these is an example showing TCP server that accepts a string as input, reverses it and returns it to the client.
Here is Code:

<?php
$host = "127.0.0.1";
$port = 1234;
set_time_limit(0);
$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die("Could not create socket\n");
$result = socket_bind($socket, $host, $port) or die("Could not bind to socket\n");
$result = socket_listen($socket, 3) or die("Could not set up socket listener\n");
$spawn = socket_accept($socket) or die("Could not accept incoming connection\n");
$input = socket_read($spawn, 1024) or die("Could not read input\n");
$input = trim($input);
$output = strrev($input) . "\n";
socket_write($spawn, $output, strlen ($output)) or die("Could not write output\n");
socket_close($spawn);
socket_close($socket);
?>

and got error like this:

  Warning: socket_bind() [function.socket-bind]: unable to bind address [0]: Only one usage of each socket address (protocol/network address/port) is normally permitted. in C:\xampp\htdocs\socket.php on line 5
Could not bind to socket

What could I do to fix this ?

Answer 1

Add this option to the program before binding

   if (!socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1)) {
    echo socket_strerror(socket_last_error($socket));
    exit;
} 

for reference http://www.php.net/manual/en/function.socket-bind.php

You can also check http://www.php.net/manual/en/function.socket-set-option.php for details