User:Pizzahut/msqp.php

This is a code example for querying a Half-Life master server using the PHP language.

<?php

/*

Version history

1     - Initial release.
2     - Added option to use the official domain name instead of IPs and retry if
        a timeout occurs.
2.1   - Added more master servers.
2.1.1 - Fixed a bug, program didn't terminate if all master servers time out.
2.1.2 - Removed a now redundant variable.
2.2   - Seeding for long server lists.
      - Removed the domain name because it's often better to try different
        servers.
2.2.1 - Bug fix: Timeout showed wrong master server IP.
      - Bug fix: Check whether the new seed starts with a duplicate or not.
      - Bug fix: Don't close socket twice.
2.3   - Retry queries on timeout if the first query was successful.
2.3.1 - Reading the whole address again if it starts with a zero.
      - Increased timeout to avoid a communication issue.
      - Removed maximum number of timeouts for testing.
2.4   - Again using hl1master.steampowered.com because IPs change often.
      - Endless retries because this server often times out.
*/

$master_servers = array("hl1master.steampowered.com");

define("TIMEOUT", 2.0);
define("WORLD", "\xFF");
define("PORT", 27010);

function query_timeout(&$socket, $seed)
{
   echo "Sending query to master server.\n";
   stream_set_timeout($socket, TIMEOUT);
   $region = WORLD;
   if (!fwrite($socket, "1$region$seed\0\\gamedir\\tfc\0"))
   {
      fclose($socket);
      exit("fwrite error\n");
   }

   echo "Reading response header.\n";
   stream_set_timeout($socket, TIMEOUT);
   $s = bin2hex(fread($socket, 6));
   $info = stream_get_meta_data($socket);
   if ($info['timed_out'])
      echo "Master server timed out.\n";
   else
   {
      if ($s !== "ffffffff660a")
      {
         fclose($socket);
         exit("Expected ff ff ff ff 66 0a (hex) but got $s.");
      }
   }
   return $info['timed_out'];
}

// Connect to master server, return timeout info.
// The socket is passed as reference and thus returned as well.

function master_server_timeout(&$socket, $ip)
{
   echo "Connecting to master server \"$ip:".PORT."\".\n";
   $socket = fsockopen("udp://$ip", PORT, $errno, $errstr, TIMEOUT);
   if (!$socket)
      exit("Error $errno : $errstr \n");

   return query_timeout($socket, "0.0.0.0:0");
}

// Try all master servers unless we find one that isn't timing out.

do {
   $abort = 1;
   foreach ($master_servers as $ip)
   {
      if (!master_server_timeout($socket, $ip))
      {
         $abort = 0;
         break;
      }
      else
         fclose($socket);
   }
} while ($abort == 1);

// Read list with server addresses (IP:port).

$count = 0;
$old_a1 = 0; $old_a2 = 0; $old_a3 = 0; $old_a4 = 0; $old_a5 = 0;
$max_timeouts = 6;
do
{
   stream_set_timeout($socket, TIMEOUT);
   $a1 = ord(fread($socket,1));
   $info = stream_get_meta_data($socket);
   if ($info['timed_out'])
   {
      $seed = "$old_a1.$old_a2.$old_a3.$old_a4:$old_a5";
      echo "Seed: $seed\n";
      while (query_timeout($socket, $seed));
      stream_set_timeout($socket, TIMEOUT);
      $a1 = ord(fread($socket,1));
      $info = stream_get_meta_data($socket);
      if ($info['timed_out'])
      {
         echo "Timeout occured.\n";
         break;
      }
      $check_for_duplicate = 1;
   }
   else
      $check_for_duplicate = 0;

   // Let's always read the rest of the address (even if it starts with 0) in
   // order to empty the master server's write buffer. This may avoid subsequent
   // problems, but I'm paranoid here.
   $a2 = ord(fread($socket,1));
   $a3 = ord(fread($socket,1));
   $a4 = ord(fread($socket,1));
   $a5 = ord(fread($socket,1))*256 + ord(fread($socket,1));

   if ($a1 != 0)
   {
      if (($check_for_duplicate==0)||($a1!=$old_a1)||($a2!=$old_a2)||
      ($a3!=$old_a3)||($a4!=$old_a4)||($a5!=$old_a5))
      {
         $count++;
         echo "$count $a1.$a2.$a3.$a4:$a5\n";
      }
      $old_a1 = $a1; $old_a2 = $a2; $old_a3 = $a3; $old_a4 = $a4; $old_a5 = $a5;
   }
} while ($a1 != 0);
fclose($socket);
echo "Retrieved $count server addresses.\n";

?>