CAS_Client::__construct PHP Method

    public function __construct($server_version, $proxy, $server_hostname, $server_port, $server_uri, $changeSessionID = true)
    {
        // Argument validation
        if (gettype($server_version) != 'string') {
            throw new CAS_TypeMismatchException($server_version, '$server_version', 'string');
        }
        if (gettype($proxy) != 'boolean') {
            throw new CAS_TypeMismatchException($proxy, '$proxy', 'boolean');
        }
        if (gettype($server_hostname) != 'string') {
            throw new CAS_TypeMismatchException($server_hostname, '$server_hostname', 'string');
        }
        if (gettype($server_port) != 'integer') {
            throw new CAS_TypeMismatchException($server_port, '$server_port', 'integer');
        }
        if (gettype($server_uri) != 'string') {
            throw new CAS_TypeMismatchException($server_uri, '$server_uri', 'string');
        }
        if (gettype($changeSessionID) != 'boolean') {
            throw new CAS_TypeMismatchException($changeSessionID, '$changeSessionID', 'boolean');
        }
        phpCAS::traceBegin();
        // true : allow to change the session_id(), false session_id won't be
        // change and logout won't be handle because of that
        $this->_setChangeSessionID($changeSessionID);
        // skip Session Handling for logout requests and if don't want it'
        if (session_id() == "" && !$this->_isLogoutRequest()) {
            session_start();
            phpCAS::trace("Starting a new session " . session_id());
        }
        // Only for debug purposes
        if ($this->isSessionAuthenticated()) {
            phpCAS::trace("Session is authenticated as: " . $_SESSION['phpCAS']['user']);
        } else {
            phpCAS::trace("Session is not authenticated");
        }
        // are we in proxy mode ?
        $this->_proxy = $proxy;
        // Make cookie handling available.
        if ($this->isProxy()) {
            if (!isset($_SESSION['phpCAS'])) {
                $_SESSION['phpCAS'] = array();
            }
            if (!isset($_SESSION['phpCAS']['service_cookies'])) {
                $_SESSION['phpCAS']['service_cookies'] = array();
            }
            $this->_serviceCookieJar = new CAS_CookieJar($_SESSION['phpCAS']['service_cookies']);
        }
        //check version
        switch ($server_version) {
            case CAS_VERSION_1_0:
                if ($this->isProxy()) {
                    phpCAS::error('CAS proxies are not supported in CAS ' . $server_version);
                }
                break;
            case CAS_VERSION_2_0:
            case CAS_VERSION_3_0:
                break;
            case SAML_VERSION_1_1:
                break;
            default:
                phpCAS::error('this version of CAS (`' . $server_version . '\') is not supported by phpCAS ' . phpCAS::getVersion());
        }
        $this->_server['version'] = $server_version;
        // check hostname
        if (empty($server_hostname) || !preg_match('/[\\.\\d\\-abcdefghijklmnopqrstuvwxyz]*/', $server_hostname)) {
            phpCAS::error('bad CAS server hostname (`' . $server_hostname . '\')');
        }
        $this->_server['hostname'] = $server_hostname;
        // check port
        if ($server_port == 0 || !is_int($server_port)) {
            phpCAS::error('bad CAS server port (`' . $server_hostname . '\')');
        }
        $this->_server['port'] = $server_port;
        // check URI
        if (!preg_match('/[\\.\\d\\-_abcdefghijklmnopqrstuvwxyz\\/]*/', $server_uri)) {
            phpCAS::error('bad CAS server URI (`' . $server_uri . '\')');
        }
        // add leading and trailing `/' and remove doubles
        if (strstr($server_uri, '?') === false) {
            $server_uri .= '/';
        }
        $server_uri = preg_replace('/\\/\\//', '/', '/' . $server_uri);
        $this->_server['uri'] = $server_uri;
        // set to callback mode if PgtIou and PgtId CGI GET parameters are provided
        if ($this->isProxy()) {
            $this->_setCallbackMode(!empty($_GET['pgtIou']) && !empty($_GET['pgtId']));
        }
        if ($this->_isCallbackMode()) {
            //callback mode: check that phpCAS is secured
            if (!$this->_isHttps()) {
                phpCAS::error('CAS proxies must be secured to use phpCAS; PGT\'s will not be received from the CAS server');
            }
        } else {
            //normal mode: get ticket and remove it from CGI parameters for
            // developers
            $ticket = isset($_GET['ticket']) ? $_GET['ticket'] : null;
            if (preg_match('/^[SP]T-/', $ticket)) {
                phpCAS::trace('Ticket \'' . $ticket . '\' found');
                $this->setTicket($ticket);
                unset($_GET['ticket']);
            } else {
                if (!empty($ticket)) {
                    //ill-formed ticket, halt
                    phpCAS::error('ill-formed ticket found in the URL (ticket=`' . htmlentities($ticket) . '\')');
                }
            }
        }
        phpCAS::traceEnd();
    }