CAS_Client::validateCAS20 PHP Method

    public function validateCAS20(&$validate_url, &$text_response, &$tree_response, $renew = false)
    {
        phpCAS::traceBegin();
        phpCAS::trace($text_response);
        $result = false;
        // build the URL to validate the ticket
        if ($this->getAllowedProxyChains()->isProxyingAllowed()) {
            $validate_url = $this->getServerProxyValidateURL() . '&ticket=' . urlencode($this->getTicket());
        } else {
            $validate_url = $this->getServerServiceValidateURL() . '&ticket=' . urlencode($this->getTicket());
        }
        if ($this->isProxy()) {
            // pass the callback url for CAS proxies
            $validate_url .= '&pgtUrl=' . urlencode($this->_getCallbackURL());
        }
        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, 'Ticket not validated', $validate_url, true);
            $result = false;
        }
        // create new DOMDocument object
        $dom = new DOMDocument();
        // Fix possible whitspace problems
        $dom->preserveWhiteSpace = false;
        // CAS servers should only return data in utf-8
        $dom->encoding = "utf-8";
        // read the response of the CAS server into a DOMDocument object
        if (!$dom->loadXML($text_response)) {
            // read failed
            throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, true, $text_response);
            $result = false;
        } else {
            if (!($tree_response = $dom->documentElement)) {
                // read the root node of the XML tree
                // read failed
                throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, true, $text_response);
                $result = false;
            } else {
                if ($tree_response->localName != 'serviceResponse') {
                    // insure that tag name is 'serviceResponse'
                    // bad root node
                    throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, true, $text_response);
                    $result = false;
                } else {
                    if ($tree_response->getElementsByTagName("authenticationSuccess")->length != 0) {
                        // authentication succeded, extract the user name
                        $success_elements = $tree_response->getElementsByTagName("authenticationSuccess");
                        if ($success_elements->item(0)->getElementsByTagName("user")->length == 0) {
                            // no user specified => error
                            throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, true, $text_response);
                            $result = false;
                        } else {
                            $this->_setUser(trim($success_elements->item(0)->getElementsByTagName("user")->item(0)->nodeValue));
                            $this->_readExtraAttributesCas20($success_elements);
                            // Store the proxies we are sitting behind for authorization checking
                            $proxyList = array();
                            if (sizeof($arr = $success_elements->item(0)->getElementsByTagName("proxy")) > 0) {
                                foreach ($arr as $proxyElem) {
                                    phpCAS::trace("Found Proxy: " . $proxyElem->nodeValue);
                                    $proxyList[] = trim($proxyElem->nodeValue);
                                }
                                $this->_setProxies($proxyList);
                                phpCAS::trace("Storing Proxy List");
                            }
                            // Check if the proxies in front of us are allowed
                            if (!$this->getAllowedProxyChains()->isProxyListAllowed($proxyList)) {
                                throw new CAS_AuthenticationException($this, 'Proxy not allowed', $validate_url, false, true, $text_response);
                                $result = false;
                            } else {
                                $result = true;
                            }
                        }
                    } else {
                        if ($tree_response->getElementsByTagName("authenticationFailure")->length != 0) {
                            // authentication succeded, extract the error code and message
                            $auth_fail_list = $tree_response->getElementsByTagName("authenticationFailure");
                            throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, false, $text_response, $auth_fail_list->item(0)->getAttribute('code'), trim($auth_fail_list->item(0)->nodeValue));
                            $result = false;
                        } else {
                            throw new CAS_AuthenticationException($this, 'Ticket not validated', $validate_url, false, true, $text_response);
                            $result = false;
                        }
                    }
                }
            }
        }
        if ($result) {
            $this->_renameSession($this->getTicket());
        }
        // at this step, Ticket has been validated and $this->_user has been set,
        phpCAS::traceEnd($result);
        return $result;
    }

 /**
  * Wrong order of valid regexp
  *
  * @return void
  *
  * @expectedException CAS_AuthenticationException
  * @outputBuffering enabled
  */
 public function testAllowedProxiesRegexpFailureWrongOrder()
 {
     $this->object->setTicket('ST-123456-asdfasdfasgww2323radf3');
     $this->object->getAllowedProxyChains()->allowProxyChain(new CAS_ProxyChain(array('/^https\\:\\/\\/anotherdomain.org\\/mysite\\/test2$/', '/http\\:\\/\\/firstproxy\\.com.*$/')));
     $result = $this->object->validateCAS20($url, $text_response, $tree_response);
     $this->assertFalse($result);
 }