public function ping($addr, $cb)
    {
        $e = explode(':', $addr);
        $this->getConnection('valve://[udp:' . $e[0] . ']' . (isset($e[1]) ? ':' . $e[1] : '') . '/ping',
            function ($conn) use ($cb) {
                if (!$conn->connected) {
                    $cb($conn, false);
                    return;
                }
                $mt = microtime(true);
                $conn->request('ping', null, function ($conn, $success) use ($mt, $cb) {
                    $cb($conn, $success ? (microtime(true) - $mt) : false);
                });
            });
    }