Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\EventSubscriber;
Chris@0: 
Chris@0: use Drupal\Core\Access\AccessManagerInterface;
Chris@0: use Drupal\Core\Cache\RefinableCacheableDependencyInterface;
Chris@0: use Drupal\Core\Config\ConfigFactoryInterface;
Chris@0: use Drupal\Core\Routing\AccessAwareRouterInterface;
Chris@0: use Drupal\Core\Routing\RedirectDestinationInterface;
Chris@0: use Drupal\Core\Url;
Chris@0: use Psr\Log\LoggerInterface;
Chris@0: use Symfony\Component\HttpFoundation\Response;
Chris@0: use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
Chris@0: use Symfony\Component\HttpKernel\HttpKernelInterface;
Chris@0: use Symfony\Component\Routing\Matcher\UrlMatcherInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Exception subscriber for handling core custom HTML error pages.
Chris@0:  */
Chris@0: class CustomPageExceptionHtmlSubscriber extends DefaultExceptionHtmlSubscriber {
Chris@0: 
Chris@0:   /**
Chris@0:    * The configuration factory.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Config\ConfigFactoryInterface
Chris@0:    */
Chris@0:   protected $configFactory;
Chris@0: 
Chris@0:   /**
Chris@0:    * The access manager.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Access\AccessManagerInterface
Chris@0:    */
Chris@0:   protected $accessManager;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new CustomPageExceptionHtmlSubscriber.
Chris@0:    *
Chris@0:    * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
Chris@0:    *   The configuration factory.
Chris@0:    * @param \Symfony\Component\HttpKernel\HttpKernelInterface $http_kernel
Chris@0:    *   The HTTP Kernel service.
Chris@0:    * @param \Psr\Log\LoggerInterface $logger
Chris@0:    *   The logger service.
Chris@0:    * @param \Drupal\Core\Routing\RedirectDestinationInterface $redirect_destination
Chris@0:    *   The redirect destination service.
Chris@0:    * @param \Symfony\Component\Routing\Matcher\UrlMatcherInterface $access_unaware_router
Chris@0:    *   A router implementation which does not check access.
Chris@0:    * @param \Drupal\Core\Access\AccessManagerInterface $access_manager
Chris@0:    *   The access manager.
Chris@0:    */
Chris@0:   public function __construct(ConfigFactoryInterface $config_factory, HttpKernelInterface $http_kernel, LoggerInterface $logger, RedirectDestinationInterface $redirect_destination, UrlMatcherInterface $access_unaware_router, AccessManagerInterface $access_manager) {
Chris@0:     parent::__construct($http_kernel, $logger, $redirect_destination, $access_unaware_router);
Chris@0:     $this->configFactory = $config_factory;
Chris@0:     $this->accessManager = $access_manager;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   protected static function getPriority() {
Chris@0:     return -50;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function on403(GetResponseForExceptionEvent $event) {
Chris@0:     $custom_403_path = $this->configFactory->get('system.site')->get('page.403');
Chris@0:     if (!empty($custom_403_path)) {
Chris@0:       $this->makeSubrequestToCustomPath($event, $custom_403_path, Response::HTTP_FORBIDDEN);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function on404(GetResponseForExceptionEvent $event) {
Chris@0:     $custom_404_path = $this->configFactory->get('system.site')->get('page.404');
Chris@0:     if (!empty($custom_404_path)) {
Chris@0:       $this->makeSubrequestToCustomPath($event, $custom_404_path, Response::HTTP_NOT_FOUND);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Makes a subrequest to retrieve the custom error page.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    * @param string $custom_path
Chris@0:    *   The custom path to which to make a subrequest for this error message.
Chris@0:    * @param int $status_code
Chris@0:    *   The status code for the error being handled.
Chris@0:    */
Chris@0:   protected function makeSubrequestToCustomPath(GetResponseForExceptionEvent $event, $custom_path, $status_code) {
Chris@0:     $url = Url::fromUserInput($custom_path);
Chris@0:     if ($url->isRouted()) {
Chris@0:       $access_result = $this->accessManager->checkNamedRoute($url->getRouteName(), $url->getRouteParameters(), NULL, TRUE);
Chris@0:       $request = $event->getRequest();
Chris@0: 
Chris@0:       // Merge the custom path's route's access result's cacheability metadata
Chris@0:       // with the existing one (from the master request), otherwise create it.
Chris@0:       if (!$request->attributes->has(AccessAwareRouterInterface::ACCESS_RESULT)) {
Chris@0:         $request->attributes->set(AccessAwareRouterInterface::ACCESS_RESULT, $access_result);
Chris@0:       }
Chris@0:       else {
Chris@0:         $existing_access_result = $request->attributes->get(AccessAwareRouterInterface::ACCESS_RESULT);
Chris@0:         if ($existing_access_result instanceof RefinableCacheableDependencyInterface) {
Chris@0:           $existing_access_result->addCacheableDependency($access_result);
Chris@0:         }
Chris@0:       }
Chris@0: 
Chris@0:       // Only perform the subrequest if the custom path is actually accessible.
Chris@0:       if (!$access_result->isAllowed()) {
Chris@0:         return;
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     $this->makeSubrequest($event, $custom_path, $status_code);
Chris@0:   }
Chris@0: 
Chris@0: }