CAS_Client::handleLogoutRequests PHP Method

    public function handleLogoutRequests($check_client = true, $allowed_clients = false)
    {
        phpCAS::traceBegin();
        if (!$this->_isLogoutRequest()) {
            phpCAS::trace("Not a logout request");
            phpCAS::traceEnd();
            return;
        }
        if (!$this->getChangeSessionID() && is_null($this->_signoutCallbackFunction)) {
            phpCAS::trace("phpCAS can't handle logout requests if it is not allowed to change session_id.");
        }
        phpCAS::trace("Logout requested");
        $decoded_logout_rq = urldecode($_POST['logoutRequest']);
        phpCAS::trace("SAML REQUEST: " . $decoded_logout_rq);
        $allowed = false;
        if ($check_client) {
            if (!$allowed_clients) {
                $allowed_clients = array($this->_getServerHostname());
            }
            $client_ip = $_SERVER['REMOTE_ADDR'];
            $client = gethostbyaddr($client_ip);
            phpCAS::trace("Client: " . $client . "/" . $client_ip);
            foreach ($allowed_clients as $allowed_client) {
                if ($client == $allowed_client || $client_ip == $allowed_client) {
                    phpCAS::trace("Allowed client '" . $allowed_client . "' matches, logout request is allowed");
                    $allowed = true;
                    break;
                } else {
                    phpCAS::trace("Allowed client '" . $allowed_client . "' does not match");
                }
            }
        } else {
            phpCAS::trace("No access control set");
            $allowed = true;
        }
        // If Logout command is permitted proceed with the logout
        if ($allowed) {
            phpCAS::trace("Logout command allowed");
            // Rebroadcast the logout request
            if ($this->_rebroadcast && !isset($_POST['rebroadcast'])) {
                $this->_rebroadcast(self::LOGOUT);
            }
            // Extract the ticket from the SAML Request
            preg_match("|<samlp:SessionIndex>(.*)</samlp:SessionIndex>|", $decoded_logout_rq, $tick, PREG_OFFSET_CAPTURE, 3);
            $wrappedSamlSessionIndex = preg_replace('|<samlp:SessionIndex>|', '', $tick[0][0]);
            $ticket2logout = preg_replace('|</samlp:SessionIndex>|', '', $wrappedSamlSessionIndex);
            phpCAS::trace("Ticket to logout: " . $ticket2logout);
            // call the post-authenticate callback if registered.
            if ($this->_signoutCallbackFunction) {
                $args = $this->_signoutCallbackArgs;
                array_unshift($args, $ticket2logout);
                call_user_func_array($this->_signoutCallbackFunction, $args);
            }
            // If phpCAS is managing the session_id, destroy session thanks to
            // session_id.
            if ($this->getChangeSessionID()) {
                $session_id = preg_replace('/[^a-zA-Z0-9\\-]/', '', $ticket2logout);
                phpCAS::trace("Session id: " . $session_id);
                // destroy a possible application session created before phpcas
                if (session_id() !== "") {
                    session_unset();
                    session_destroy();
                }
                // fix session ID
                session_id($session_id);
                $_COOKIE[session_name()] = $session_id;
                $_GET[session_name()] = $session_id;
                // Overwrite session
                session_start();
                session_unset();
                session_destroy();
                phpCAS::trace("Session " . $session_id . " destroyed");
            }
        } else {
            phpCAS::error("Unauthorized logout request from client '" . $client . "'");
            phpCAS::trace("Unauthorized logout request from client '" . $client . "'");
        }
        flush();
        phpCAS::traceExit();
        throw new CAS_GracefullTerminationException();
    }

 private function initializeCAS()
 {
     $casClient = new \CAS_Client(CAS_VERSION_2_0, true, Config::get('cas.hostname'), Config::get('cas.port'), Config::get('cas.context'));
     $casClient->setNoCasServerValidation();
     if (true === Config::get('pgtservice.enabled', false)) {
         $casClient->setCallbackURL(Config::get('pgtservice.callback'));
         $casClient->setPGTStorage(new ProxyTicketServiceStorage($casClient));
     } else {
         if (false !== Config::get('redis.hostname', false)) {
             $casClient->setCallbackURL($this->url->getURL() . '/callback.php');
             $redis = new \Redis();
             $redis->connect(Config::get('redis.hostname'), Config::get('redis.port', 6379), 2, null, 100);
             $redis->setOption(\Redis::OPT_SERIALIZER, \Redis::SERIALIZER_PHP);
             $redis->setOption(\Redis::OPT_PREFIX, Config::get('application.project_name') . ':PHPCAS_TICKET_STORAGE:');
             $redis->select((int) Config::get('redis.hostname', 2));
             $casClient->setPGTStorage(new RedisTicketStorage($casClient, $redis));
         } else {
             $casClient->setCallbackURL($this->url->getURL() . '/callback.php');
             $casClient->setPGTStorageFile(session_save_path());
             // Handle logout requests but do not validate the server
             $casClient->handleLogoutRequests(false);
         }
     }
     // Accept all proxy chains
     $casClient->getAllowedProxyChains()->allowProxyChain(new \CAS_ProxyChain_Any());
     return $casClient;
 }