Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\EventSubscriber;
Chris@0: 
Chris@14: use Drupal\Core\Cache\CacheableResponseInterface;
Chris@0: use Drupal\Core\Routing\RedirectDestinationInterface;
Chris@0: use Drupal\Core\Utility\Error;
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\HttpKernel\Exception\HttpExceptionInterface;
Chris@0: use Symfony\Component\Routing\Matcher\UrlMatcherInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Exception subscriber for handling core default HTML error pages.
Chris@0:  */
Chris@0: class DefaultExceptionHtmlSubscriber extends HttpExceptionSubscriberBase {
Chris@0: 
Chris@0:   /**
Chris@0:    * The HTTP kernel.
Chris@0:    *
Chris@0:    * @var \Symfony\Component\HttpKernel\HttpKernelInterface
Chris@0:    */
Chris@0:   protected $httpKernel;
Chris@0: 
Chris@0:   /**
Chris@0:    * The logger instance.
Chris@0:    *
Chris@0:    * @var \Psr\Log\LoggerInterface
Chris@0:    */
Chris@0:   protected $logger;
Chris@0: 
Chris@0:   /**
Chris@0:    * The redirect destination service.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Routing\RedirectDestinationInterface
Chris@0:    */
Chris@0:   protected $redirectDestination;
Chris@0: 
Chris@0:   /**
Chris@0:    * A router implementation which does not check access.
Chris@0:    *
Chris@0:    * @var \Symfony\Component\Routing\Matcher\UrlMatcherInterface
Chris@0:    */
Chris@0:   protected $accessUnawareRouter;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new DefaultExceptionHtmlSubscriber.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\HttpKernelInterface $http_kernel
Chris@0:    *   The HTTP kernel.
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:    */
Chris@0:   public function __construct(HttpKernelInterface $http_kernel, LoggerInterface $logger, RedirectDestinationInterface $redirect_destination, UrlMatcherInterface $access_unaware_router) {
Chris@0:     $this->httpKernel = $http_kernel;
Chris@0:     $this->logger = $logger;
Chris@0:     $this->redirectDestination = $redirect_destination;
Chris@0:     $this->accessUnawareRouter = $access_unaware_router;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   protected static function getPriority() {
Chris@0:     // A very low priority so that custom handlers are almost certain to fire
Chris@0:     // before it, even if someone forgets to set a priority.
Chris@0:     return -128;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   protected function getHandledFormats() {
Chris@0:     return ['html'];
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Handles a 4xx error for HTML.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    */
Chris@0:   public function on4xx(GetResponseForExceptionEvent $event) {
Chris@0:     if (($exception = $event->getException()) && $exception instanceof HttpExceptionInterface) {
Chris@0:       $this->makeSubrequest($event, '/system/4xx', $exception->getStatusCode());
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Handles a 401 error for HTML.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    */
Chris@0:   public function on401(GetResponseForExceptionEvent $event) {
Chris@0:     $this->makeSubrequest($event, '/system/401', Response::HTTP_UNAUTHORIZED);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Handles a 403 error for HTML.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    */
Chris@0:   public function on403(GetResponseForExceptionEvent $event) {
Chris@0:     $this->makeSubrequest($event, '/system/403', Response::HTTP_FORBIDDEN);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Handles a 404 error for HTML.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    */
Chris@0:   public function on404(GetResponseForExceptionEvent $event) {
Chris@0:     $this->makeSubrequest($event, '/system/404', Response::HTTP_NOT_FOUND);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Makes a subrequest to retrieve the default error page.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
Chris@0:    *   The event to process.
Chris@0:    * @param string $url
Chris@0:    *   The path/url 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 makeSubrequest(GetResponseForExceptionEvent $event, $url, $status_code) {
Chris@0:     $request = $event->getRequest();
Chris@0:     $exception = $event->getException();
Chris@0: 
Chris@0:     try {
Chris@0:       // Reuse the exact same request (so keep the same URL, keep the access
Chris@0:       // result, the exception, et cetera) but override the routing information.
Chris@0:       // This means that aside from routing, this is identical to the master
Chris@0:       // request. This allows us to generate a response that is executed on
Chris@0:       // behalf of the master request, i.e. for the original URL. This is what
Chris@0:       // allows us to e.g. generate a 404 response for the original URL; if we
Chris@0:       // would execute a subrequest with the 404 route's URL, then it'd be
Chris@0:       // generated for *that* URL, not the *original* URL.
Chris@0:       $sub_request = clone $request;
Chris@0: 
Chris@0:       // The routing to the 404 page should be done as GET request because it is
Chris@0:       // restricted to GET and POST requests only. Otherwise a DELETE request
Chris@0:       // would for example trigger a method not allowed exception.
Chris@0:       $request_context = clone ($this->accessUnawareRouter->getContext());
Chris@0:       $request_context->setMethod('GET');
Chris@0:       $this->accessUnawareRouter->setContext($request_context);
Chris@0: 
Chris@0:       $sub_request->attributes->add($this->accessUnawareRouter->match($url));
Chris@0: 
Chris@0:       // Add to query (GET) or request (POST) parameters:
Chris@0:       // - 'destination' (to ensure e.g. the login form in a 403 response
Chris@0:       //   redirects to the original URL)
Chris@0:       // - '_exception_statuscode'
Chris@0:       $parameters = $sub_request->isMethod('GET') ? $sub_request->query : $sub_request->request;
Chris@0:       $parameters->add($this->redirectDestination->getAsArray() + ['_exception_statuscode' => $status_code]);
Chris@0: 
Chris@0:       $response = $this->httpKernel->handle($sub_request, HttpKernelInterface::SUB_REQUEST);
Chris@0:       // Only 2xx responses should have their status code overridden; any
Chris@0:       // other status code should be passed on: redirects (3xx), error (5xx)…
Chris@0:       // @see https://www.drupal.org/node/2603788#comment-10504916
Chris@0:       if ($response->isSuccessful()) {
Chris@0:         $response->setStatusCode($status_code);
Chris@0:       }
Chris@0: 
Chris@14:       // Persist the exception's cacheability metadata, if any. If the exception
Chris@14:       // itself isn't cacheable, then this will make the response uncacheable:
Chris@14:       // max-age=0 will be set.
Chris@14:       if ($response instanceof CacheableResponseInterface) {
Chris@14:         $response->addCacheableDependency($exception);
Chris@14:       }
Chris@14: 
Chris@0:       // Persist any special HTTP headers that were set on the exception.
Chris@0:       if ($exception instanceof HttpExceptionInterface) {
Chris@0:         $response->headers->add($exception->getHeaders());
Chris@0:       }
Chris@0: 
Chris@0:       $event->setResponse($response);
Chris@0:     }
Chris@0:     catch (\Exception $e) {
Chris@0:       // If an error happened in the subrequest we can't do much else. Instead,
Chris@0:       // just log it. The DefaultExceptionSubscriber will catch the original
Chris@0:       // exception and handle it normally.
Chris@0:       $error = Error::decodeException($e);
Chris@0:       $this->logger->log($error['severity_level'], '%type: @message in %function (line %line of %file).', $error);
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0: }