Online Unreal Tournament server browser with pcntl fork()

Martin Tournoij <martin@arp242.net>
Created on 2010-06-27, last updated on 2010-06-27

Another Unreal Tournament related script that I’ve been using for a long time.

Today I refactored the code to use pcntl_fork() in order to speed the script up.
This is the only real multiprocessing facility offered by PHP, it is exactly the same as the “classic” UNIX fork() function (See: /ext/pcntl/pcntl.c). More advanced/efficient versions such as vfork() or rfork() are not available.

Another method to handle this particular problem would be to connect in a non-blocking mode, and use stream_select(). I chose to use fork because I wanted to investigate PHP’s multiprocessing capabilities (which are pretty much non-existent for almost any serious purpose).

Note: do not use exit() to exit the child process, use posix_kill(getmypid(), SIGKILL) instead. For reasons not clear to me exit() doesn't work when run from CGI, it exits the parent process too (It does work when run from the commandline).

In action

Here are working demo’s:
ut-serverbrowse with fork()
Without fork()

The code with fork

Download 
<?php
#
# Martin Tournoij <martin@arp242.net>
# Free for any use. There are no restrictions.
#
# Note: We use pcntl_fork(), you will need the pcntl PHP module.
# Also note this will not work in Windows or if PHP is loaded as Apache module.
#

function Query($server, $cmd)
{
	# http://wiki.beyondunreal.com/Legacy:UT_Server_Query

	$address = gethostbyname($server['0']);
	
	if (!$s = fsockopen('udp://' . $server['0'], $server['1'], $errno, $errstr, 2))
		return False;

	stream_set_timeout($s, 2);
	fputs($s, "\\$cmd\\");
	$info = fread($s, 8192);
	fclose($s);
	$info2 = explode('\\', "\\$info\\");

	foreach ($info2 as $k => $v)
	{
		if (empty($v) || $v == '' || $v == ' ')
			continue;
		if (is_int($k/2))
			$pv = $v;
		else
			$prettyinfo["$pv"] = htmlentities($v);

	}
	$prettyinfo['str'] = $info;

	return $prettyinfo;
}

function Server($s)
{
	$info = Query($s, 'status');

	if (empty($info['str']))
	{
		# Just hide the entry, servers are often down
		#return "<tr><td colspan=\"4\">Could not connect to {$s['0']} {$s['1']}</td></tr>";
		return '';
	}
	
	if (isset($info['numplayers']))
	{
		$numplayers = $info['numplayers'] . " Players:<br />\n";
		$players = Query($s, 'players');

		for ($i=0; $i<=$info['maxplayers']; $i++)
		{
			$k = "player_$i";
			if ($players["$k"])
				$numplayers .= $players["$k"] . "<br />\n";
		}
	}
	else
		$numplayers = 'No players';

	# XXX Detect DTAS in a better way
	if ($info['gametype'] == 'INFCoopUnrealGame')
		$gametype = 'Coop';
	elseif ($info['gametype'] == 'INFg_EASGame')
		$gametype = 'EAS';
	elseif (stristr($info['hostname'], 'dtas'))
		$gametype = 'DTAS';
	elseif ($info['gametype'] == 'InfilTeamGamePlus')
		$gametype = 'TDM';
	else
		$gametype = $info['gametype'];

	$row = sprintf('<tr>
		<td><a href="ut-serverbrowse.php?server=%s:%s">%s</a><br />
		<span class="small">%s:%s</span></td>
		<td>%s</td>
		<td>%s</td>
		<td>%s</td>
		</tr>',
		$s['0'], $s['1'], $info['hostname'], $s['0'], $s['1'], $info['mapname'], $gametype, $numplayers);

	return $row;
}

function html($tbl)
{
	if (stristr($_SERVER['HTTP_ACCEPT'], 'application/xhtml+xml'))
		$charset = 'application/xhtml+xml; charset=utf-8';
	else
		$charset = 'text/html; charset=utf-8';
	header("Content-Type: $charset");

	print '<?xml version="1.0" encoding="UTF-8"?>';
	printf('<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
			"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
		<head>
			<meta http-equiv="Content-Type" content="%s" /> 
			<title>Infiltration Servers</title>
			<style type="text/css">
				table { border-collapse: collapse; margin: .25em; width: 95%%; }
				td, th, table, caption { border: 1px solid black; }
				tfoot td { border: none; font-size: .8em; }
				caption, th, tfoot { background-color: #ddd; }
				caption { font-weight: bold; }
				tr:hover { background-color: #eee; }
				div { border: 1px solid black; margin: .25em; width: 94%%; padding: .2em; margin-top: 2em; }
				label { width: 6em; }
				.small { font-size: .75em; margin-left: 2em; }
				p { width: 40em; }
			</style>
		</head>
		<body>
			<p>Refresh your browser and the list will be refreshed. Click on a link to 
				refresh just that one server (faster).<br />
				Unfortunately, the list of players is often incomplete. This is not a 
				bug on my side but one in the UT server. Sometimes trying for a few times can get you a 
				larger list, but often not :(</p>

			<table summary="Infiltration servers">
				<caption>Infiltration servers</caption>
				<thead>
					<tr>
						<th scope="col">Server</th>
						<th scope="col">Map</th>
						<th scope="col">GameType</th>
						<th scope="col">Players</th>
					</tr>
				</thead>
				<tfoot>
					<tr>
						<td colspan="4">List fetched on %s
							| <a href="ut-serverbrowse-fork.php.txt">View source</a></td>
					</tr>
				</tfoot>
				<tbody>
					%s
				</tbody>
			</table>

			<form method="post" action="%s">
				<div>
					<label for="server">Manually enter server to query. <em>address:port</em>: </label>
					<input type="text" id="server" name="server" value="%s"/>
					<input type="submit" value="Query" />
				</div>
			</form>', $charset, date('r'), $tbl, $_SERVER['PHP_SELF'], $_GET['server']);

	if (isset($_GET['server']))
		printf('<p><a href="%s">Back to main</a></p>', $_SERVER['PHP_SELF']);

	print '</body></html>';
}

# We do not use a masterserver but maintain the list here manually; This is a 
# feature and not a bug because the masterserver for the mod I play 
# (Infiltration) is not particularly reliable.
$servers = array(
	array('cerberon.net', 17778), # coop1
	array('cerberon.net', 27778), # coop2
	array('90.184.183.249', 7778), # wargamez
	array('xplod.de', '7778'), # xplod
	array('xplod.de', '8889'), # xplod2
	array('84.255.245.128', '7778') # planetweed
);

if (isset($_POST['server']))
	$_GET['server'] = $_POST['server'];

if (isset($_GET['server']))
{
	$a = explode(':', $_GET['server']);
	$servers = array(array($a['0'], $a['1']));
}

$mypid = getmypid();
$procs = array();
$tmp = tempnam(sys_get_temp_dir(), 'SERVERBROWSE_');
$fp = fopen($tmp, 'w+');
foreach ($servers as $s)
{
	$pid = pcntl_fork();

	if ($pid == -1)
	{
		print 'Unable to fork. Exiting';
		exit(1);
	}

	if ($pid == 0)
	{
		$data = Server($s);
		fwrite($fp, $data) . "\n";
		posix_kill(getmypid(), 9);
	}
	else
		array_push($procs, $pid);
}

# Wait for all childs to finish
while (count($procs) > 0) 
{
	$pid = pcntl_waitpid(-1, $status, WNOHANG);

	foreach($procs as $k => $p)
	{
		if($pid == $p)
			unset($procs[$k]);
	}
	usleep(250);
}

fclose($fp);

$fp = fopen($tmp, 'r');
$tbl = '';
while ($buf = fread($fp, 8192))
	$tbl .= $buf;
fclose($fp);
unlink($tmp);

html($tbl);
exit(0);

The code without fork

This is the old version without forking, it’s slower but since pcntl_fork() is not always available it may still be of some interest.

Download 
<?php
#
# Martin Tournoij <martin@arp242.net>
# Free for any use. There are no restrictions.
#

function Query($server, $cmd)
{
	# http://wiki.beyondunreal.com/Legacy:UT_Server_Query

	$address = gethostbyname($server['0']);
	
	if (!$s = fsockopen('udp://' . $server['0'], $server['1'], $errno, $errstr, 2))
		return False;

	stream_set_timeout($s, 2);
	fputs($s, "\\$cmd\\");
	$info = fread($s, 8192);
	fclose($s);
	$info2 = explode('\\', "\\$info\\");

	foreach ($info2 as $k => $v)
	{
		if (empty($v) || $v == '' || $v == ' ')
			continue;
		if (is_int($k/2))
			$pv = $v;
		else
			$prettyinfo["$pv"] = htmlentities($v);

	}
	$prettyinfo['str'] = $info;

	return $prettyinfo;
}

# We do not use a masterserver but maintain the list here manually; This is a 
# feature and not a bug because the masterserver for the mod I play 
# (Infiltration) is not particularly reliable.
$servers = array(
	array('cerberon.net', 17778), # coop1
	array('cerberon.net', 27778), # coop2
	array('90.184.183.249', 7778), # wargamez
	array('xplod.de', '7778'), # xplod
	array('xplod.de', '8889'), # xplod2
	array('84.255.245.128', '7778') # planetweed
);

if (isset($_POST['server']))
	$_GET['server'] = $_POST['server'];

if (isset($_GET['server']))
{
	$a = explode(':', $_GET['server']);
	$servers = array(array($a['0'], $a['1']));
}

$tbl = array();
foreach ($servers as $s)
{
	$info = Query($s, 'status');

	if (empty($info['str']))
	{
		# Just hide the entry, servers are often down
		#$tbl .= "<tr><td colspan=\"4\">Could not connect to {$s['0']} {$s['1']}</td></tr>";
		continue;
	}
	
	if (isset($info['numplayers']))
	{
		$numplayers = $info['numplayers'] . " Players:<br />\n";
		$players = Query($s, 'players');

		for ($i=0; $i<=$info['maxplayers']; $i++)
		{
			$k = "player_$i";
			if ($players["$k"])
				$numplayers .= $players["$k"] . "<br />\n";
		}
	}
	else
		$numplayers = 'No players';

	# XXX Detect DTAS in a better way
	if ($info['gametype'] == 'INFCoopUnrealGame')
		$gametype = 'Coop';
	elseif ($info['gametype'] == 'INFg_EASGame')
		$gametype = 'EAS';
	elseif (stristr($info['hostname'], 'dtas'))
		$gametype = 'DTAS';
	elseif ($info['gametype'] == 'InfilTeamGamePlus')
		$gametype = 'TDM';
	else
		$gametype = $info['gametype'];

	$tbl[] = sprintf('<tr>
		<td><a href="ut-serverbrowse.php?server=%s:%s">%s</a><br />
		<span class="small">%s:%s</span></td>
		<td>%s</td>
		<td>%s</td>
		<td>%s</td>
		</tr>',
		$s['0'], $s['1'], $info['hostname'], $s['0'], $s['1'], $info['mapname'], $gametype, $numplayers);
}

$tbl = implode('', $tbl);
if (stristr($_SERVER['HTTP_ACCEPT'], 'application/xhtml+xml'))
	$charset = 'application/xhtml+xml; charset=utf-8';
else
	$charset = 'text/html; charset=utf-8';
header("Content-Type: $charset");
?>
<?php echo '<?xml version="1.0" encoding="UTF-8"?>' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
    "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
	<head>
		<meta http-equiv="Content-Type" content="<?php print $charset; ?>" /> 
		<title>Infiltration Servers</title>
		<style type="text/css">
			table { border-collapse: collapse; margin: .25em; width: 95%; }
			td, th, table, caption { border: 1px solid black; }
			tfoot td { border: none; font-size: .8em; }
			caption, th, tfoot { background-color: #ddd; }
			caption { font-weight: bold; }
			tr:hover { background-color: #eee; }
			div { border: 1px solid black; margin: .25em; width: 94%; padding: .2em; margin-top: 2em; }
			label { width: 6em; }
			.small { font-size: .75em; margin-left: 2em; }
			p { width: 40em; }
		</style>
	</head>
	<body>
		<p>Refresh your browser and the list will be refreshed. Click on a link to 
			refresh just that one server (faster).<br />
			Unfortunately, the list of players is often incomplete. This is not a 
			bug on my side but one in the UT server. Sometimes trying for a few times can get you a 
			larger list, but often not :(</p>

		<table summary="Infiltration servers">
			<caption>Infiltration servers</caption>
			<thead>
				<tr>
					<th scope="col">Server</th>
					<th scope="col">Map</th>
					<th scope="col">GameType</th>
					<th scope="col">Players</th>
				</tr>
			</thead>
			<tfoot>
				<tr>
					<td colspan="4">List fetched on <?php print date('r'); ?>
						| <a href="ut-serverbrowse.php.txt">View source</a></td>
				</tr>
			</tfoot>
			<tbody>
				<?php print $tbl; ?>
			</tbody>
		</table>

		<form method="post" action="<?php print $_SERVER['PHP_SELF'] ?>">
			<div>
				<label for="server">Manually enter server to query. <em>address:port</em>: </label>
				<input type="text" id="server" name="server" value="<?php print $_GET['server'] ?>"/>
				<input type="submit" value="Query" />
			</div>
		</form>

		<?php if (isset($_GET['server'])) { ?>
			<p><a href="<?php print $_SERVER['PHP_SELF'] ?>">Back to main</a></p>
		<?php } ?>

	</body>
</html>

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