diff core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/lib/Drupal/Core/EventSubscriber/DefaultExceptionHtmlSubscriber.php	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,189 @@
+<?php
+
+namespace Drupal\Core\EventSubscriber;
+
+use Drupal\Core\Routing\RedirectDestinationInterface;
+use Drupal\Core\Utility\Error;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
+use Symfony\Component\Routing\Matcher\UrlMatcherInterface;
+
+/**
+ * Exception subscriber for handling core default HTML error pages.
+ */
+class DefaultExceptionHtmlSubscriber extends HttpExceptionSubscriberBase {
+
+  /**
+   * The HTTP kernel.
+   *
+   * @var \Symfony\Component\HttpKernel\HttpKernelInterface
+   */
+  protected $httpKernel;
+
+  /**
+   * The logger instance.
+   *
+   * @var \Psr\Log\LoggerInterface
+   */
+  protected $logger;
+
+  /**
+   * The redirect destination service.
+   *
+   * @var \Drupal\Core\Routing\RedirectDestinationInterface
+   */
+  protected $redirectDestination;
+
+  /**
+   * A router implementation which does not check access.
+   *
+   * @var \Symfony\Component\Routing\Matcher\UrlMatcherInterface
+   */
+  protected $accessUnawareRouter;
+
+  /**
+   * Constructs a new DefaultExceptionHtmlSubscriber.
+   *
+   * @param \Symfony\Component\HttpKernel\HttpKernelInterface $http_kernel
+   *   The HTTP kernel.
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The logger service.
+   * @param \Drupal\Core\Routing\RedirectDestinationInterface $redirect_destination
+   *   The redirect destination service.
+   * @param \Symfony\Component\Routing\Matcher\UrlMatcherInterface $access_unaware_router
+   *   A router implementation which does not check access.
+   */
+  public function __construct(HttpKernelInterface $http_kernel, LoggerInterface $logger, RedirectDestinationInterface $redirect_destination, UrlMatcherInterface $access_unaware_router) {
+    $this->httpKernel = $http_kernel;
+    $this->logger = $logger;
+    $this->redirectDestination = $redirect_destination;
+    $this->accessUnawareRouter = $access_unaware_router;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static function getPriority() {
+    // A very low priority so that custom handlers are almost certain to fire
+    // before it, even if someone forgets to set a priority.
+    return -128;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getHandledFormats() {
+    return ['html'];
+  }
+
+  /**
+   * Handles a 4xx error for HTML.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   */
+  public function on4xx(GetResponseForExceptionEvent $event) {
+    if (($exception = $event->getException()) && $exception instanceof HttpExceptionInterface) {
+      $this->makeSubrequest($event, '/system/4xx', $exception->getStatusCode());
+    }
+  }
+
+  /**
+   * Handles a 401 error for HTML.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   */
+  public function on401(GetResponseForExceptionEvent $event) {
+    $this->makeSubrequest($event, '/system/401', Response::HTTP_UNAUTHORIZED);
+  }
+
+  /**
+   * Handles a 403 error for HTML.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   */
+  public function on403(GetResponseForExceptionEvent $event) {
+    $this->makeSubrequest($event, '/system/403', Response::HTTP_FORBIDDEN);
+  }
+
+  /**
+   * Handles a 404 error for HTML.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   */
+  public function on404(GetResponseForExceptionEvent $event) {
+    $this->makeSubrequest($event, '/system/404', Response::HTTP_NOT_FOUND);
+  }
+
+  /**
+   * Makes a subrequest to retrieve the default error page.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent $event
+   *   The event to process.
+   * @param string $url
+   *   The path/url to which to make a subrequest for this error message.
+   * @param int $status_code
+   *   The status code for the error being handled.
+   */
+  protected function makeSubrequest(GetResponseForExceptionEvent $event, $url, $status_code) {
+    $request = $event->getRequest();
+    $exception = $event->getException();
+
+    try {
+      // Reuse the exact same request (so keep the same URL, keep the access
+      // result, the exception, et cetera) but override the routing information.
+      // This means that aside from routing, this is identical to the master
+      // request. This allows us to generate a response that is executed on
+      // behalf of the master request, i.e. for the original URL. This is what
+      // allows us to e.g. generate a 404 response for the original URL; if we
+      // would execute a subrequest with the 404 route's URL, then it'd be
+      // generated for *that* URL, not the *original* URL.
+      $sub_request = clone $request;
+
+      // The routing to the 404 page should be done as GET request because it is
+      // restricted to GET and POST requests only. Otherwise a DELETE request
+      // would for example trigger a method not allowed exception.
+      $request_context = clone ($this->accessUnawareRouter->getContext());
+      $request_context->setMethod('GET');
+      $this->accessUnawareRouter->setContext($request_context);
+
+      $sub_request->attributes->add($this->accessUnawareRouter->match($url));
+
+      // Add to query (GET) or request (POST) parameters:
+      // - 'destination' (to ensure e.g. the login form in a 403 response
+      //   redirects to the original URL)
+      // - '_exception_statuscode'
+      $parameters = $sub_request->isMethod('GET') ? $sub_request->query : $sub_request->request;
+      $parameters->add($this->redirectDestination->getAsArray() + ['_exception_statuscode' => $status_code]);
+
+      $response = $this->httpKernel->handle($sub_request, HttpKernelInterface::SUB_REQUEST);
+      // Only 2xx responses should have their status code overridden; any
+      // other status code should be passed on: redirects (3xx), error (5xx)…
+      // @see https://www.drupal.org/node/2603788#comment-10504916
+      if ($response->isSuccessful()) {
+        $response->setStatusCode($status_code);
+      }
+
+      // Persist any special HTTP headers that were set on the exception.
+      if ($exception instanceof HttpExceptionInterface) {
+        $response->headers->add($exception->getHeaders());
+      }
+
+      $event->setResponse($response);
+    }
+    catch (\Exception $e) {
+      // If an error happened in the subrequest we can't do much else. Instead,
+      // just log it. The DefaultExceptionSubscriber will catch the original
+      // exception and handle it normally.
+      $error = Error::decodeException($e);
+      $this->logger->log($error['severity_level'], '%type: @message in %function (line %line of %file).', $error);
+    }
+  }
+
+}