CAS_Client::validateSA PHP Method

    public function validateSA(&$validate_url, &$text_response, &$tree_response, $renew = false)
    {
        phpCAS::traceBegin();
        $result = false;
        // build the URL to validate the ticket
        $validate_url = $this->getServerSamlValidateURL();
        if ($renew) {
            // pass the renew
            $validate_url .= '&renew=true';
        }
        // open and read the URL
        if (!$this->_readURL($validate_url, $headers, $text_response, $err_msg)) {
            phpCAS::trace('could not open URL \'' . $validate_url . '\' to validate (' . $err_msg . ')');
            throw new CAS_AuthenticationException($this, 'SA not validated', $validate_url, true);
        }
        phpCAS::trace('server version: ' . $this->getServerVersion());
        // analyze the result depending on the version
        switch ($this->getServerVersion()) {
            case SAML_VERSION_1_1:
                // create new DOMDocument Object
                $dom = new DOMDocument();
                // Fix possible whitspace problems
                $dom->preserveWhiteSpace = false;
                // read the response of the CAS server into a DOM object
                if (!$dom->loadXML($text_response)) {
                    phpCAS::trace('dom->loadXML() failed');
                    throw new CAS_AuthenticationException($this, 'SA not validated', $validate_url, false, true, $text_response);
                    $result = false;
                }
                // read the root node of the XML tree
                if (!($tree_response = $dom->documentElement)) {
                    phpCAS::trace('documentElement() failed');
                    throw new CAS_AuthenticationException($this, 'SA not validated', $validate_url, false, true, $text_response);
                    $result = false;
                } else {
                    if ($tree_response->localName != 'Envelope') {
                        // insure that tag name is 'Envelope'
                        phpCAS::trace('bad XML root node (should be `Envelope\' instead of `' . $tree_response->localName . '\'');
                        throw new CAS_AuthenticationException($this, 'SA not validated', $validate_url, false, true, $text_response);
                        $result = false;
                    } else {
                        if ($tree_response->getElementsByTagName("NameIdentifier")->length != 0) {
                            // check for the NameIdentifier tag in the SAML response
                            $success_elements = $tree_response->getElementsByTagName("NameIdentifier");
                            phpCAS::trace('NameIdentifier found');
                            $user = trim($success_elements->item(0)->nodeValue);
                            phpCAS::trace('user = `' . $user . '`');
                            $this->_setUser($user);
                            $this->_setSessionAttributes($text_response);
                            $result = true;
                        } else {
                            phpCAS::trace('no <NameIdentifier> tag found in SAML payload');
                            throw new CAS_AuthenticationException($this, 'SA not validated', $validate_url, false, true, $text_response);
                            $result = false;
                        }
                    }
                }
        }
        if ($result) {
            $this->_renameSession($this->getTicket());
        }
        // at this step, ST has been validated and $this->_user has been set,
        phpCAS::traceEnd($result);
        return $result;
    }