public function updateSessionReferrer(GetResponseEvent $event)
    {
        if (!$event->isMasterRequest()) {
            return;
        }

        $server = $event
            ->getRequest()
            ->server;

        $referrer = parse_url($server->get('HTTP_REFERER', false), PHP_URL_HOST);
        $host = parse_url($server->get('HTTP_HOST'), PHP_URL_HOST);

        if (
            ($referrer != $host) &&
            ($referrer !== false)
        ) {
            $event
                ->getRequest()
                ->getSession()
                ->set('referrer', $referrer);
        }
    }