PHP script to load balance between Icecast servers using 302 redirect

stream.php

<?php

// This is a very noddy script to do 302 redirects to load balance between servers
// as listeners connect.  It does no caching, supports a single stream only and requires
// Icecast 2.4 or above (because it uses the status-json.xsl page).

// The server, the minimum users before load balancing, the maximum users, the servers
// are considered in order from top to bottom
$servers = array(
	array("http://server1:8000/", 10, 100),
	array("http://server2:8000/", 5, 100)
);
// This is the name of the stream that is relayed across the different servers
$mount = "stream";
// You shouldn't need to change this
$status_url = "status-json.xsl";

# Get the current load
function get_load($server) {
	global $mount, $status_url;
	$status = file_get_contents($server . $status_url);
	if (!$status)
		return false;

	// Hack for bug in XSLT
	$status = str_replace(",}", "}}", $status);

	$status = json_decode($status);
	if (!$status || !isset($status->icestats))
		return false;
	if (!is_array($status->icestats->source))
		$sources = array($status->icestats->source);
	else
		$sources = $status->icestats->source;
	$source = false;
	for ($i = 0; $i < count($sources); $i++)
	{
		if (substr($sources[$i]->listenurl, -1 - strlen($mount)) == "/" . $mount) {
			$source = $sources[$i];
			break;
		}
	}
	if (!$source)
		return false;
	return $source->listeners;
}

$chosen = false;
$chosen_load = 999999;
foreach ($servers as $server)
{
	$load = get_load($server[0]);

	// Check for error
	if ($load === false)
	{
		continue;
	}

	// Check for under minimum load
	if ($load < $server[1])
	{
		$chosen = $server[0];
		break;
	}

	// Check for under maximum load and under other server load
	if ($load < $server[2] && $load < $chosen_load)
	{
		$chosen = $server[0];
		$chosen_load = $load;
	}
}

if (!$chosen)
{
	header("HTTP/1.0 503 Service Unavilable");
}
else
{
	header("Location: " . $chosen . $mount);
}