cookies.php
protected function truncateHost($host)
    {
        $tlds = SimpleUrl::getAllTopLevelDomains();
        if (preg_match('/[a-z\-]+\.(' . $tlds . ')$/i', $host, $matches)) {
            return $matches[0];
        } elseif (preg_match('/[a-z\-]+\.[a-z\-]+\.[a-z\-]+$/i', $host, $matches)) {
            return $matches[0];
        }

        return false;
    }
protected function truncateHost($host)
    {
        $tlds = SimpleUrl::getAllTopLevelDomains();
        if (preg_match('/[a-z\-]+\.(' . $tlds . ')$/i', $host, $matches)) {
            return $matches[0];
        } elseif (preg_match('/[a-z\-]+\.[a-z\-]+\.[a-z\-]+$/i', $host, $matches)) {
            return $matches[0];
        }

        return false;
    }
Extracts just the domain part that determines a cookie's host validity.

@param string $host Host name to truncate.

@return string Domain or false on a bad host.