check host's or url's same origin

sameorigin.php

<?php
function sameOrigin($url1, $url2, $level = 2)
{
		$host1 = strpos($url1, '://') ? parse_url($url1, PHP_URL_HOST) : $url1;
		$host2 = strpos($url2, '://') ? parse_url($url2, PHP_URL_HOST) : $url2;
		return host2origin($host1, $level) == host2origin($host2, $level);
}

function host2origin($host, $level = 2)
{
		$host_arr = explode('.', $host);
		while(count($host_arr) > $level) array_shift($host_arr);
		return implode('.', $host_arr);
}