class OEmbedIframeController in Drupal 8

Controller which renders an oEmbed resource in a bare page (without blocks).

This controller is meant to render untrusted third-party HTML returned by an oEmbed provider in an iframe, so as to mitigate the potential dangers of of displaying third-party markup (i.e., XSS). The HTML returned by this controller should not be trusted, and should *never* be displayed outside of an iframe.

@internal This is an internal part of the media system in Drupal core and may be subject to change in minor releases. This class should not be instantiated or extended by external code.

Hierarchy

• class \Drupal\media\Controller\OEmbedIframeController implements ContainerInjectionInterface

File

core/modules/media/src/Controller/OEmbedIframeController.php, line 36

Namespace

Drupal\media\Controller

class OEmbedIframeController implements ContainerInjectionInterface {

  /**
   * The oEmbed resource fetcher service.
   *
   * @var \Drupal\media\OEmbed\ResourceFetcherInterface
   */
  protected $resourceFetcher;

  /**
   * The oEmbed URL resolver service.
   *
   * @var \Drupal\media\OEmbed\UrlResolverInterface
   */
  protected $urlResolver;

  /**
   * The renderer service.
   *
   * @var \Drupal\Core\Render\RendererInterface
   */
  protected $renderer;

  /**
   * The logger channel.
   *
   * @var \Psr\Log\LoggerInterface
   */
  protected $logger;

  /**
   * The iFrame URL helper service.
   *
   * @var \Drupal\media\IFrameUrlHelper
   */
  protected $iFrameUrlHelper;

  /**
   * Constructs an OEmbedIframeController instance.
   *
   * @param \Drupal\media\OEmbed\ResourceFetcherInterface $resource_fetcher
   *   The oEmbed resource fetcher service.
   * @param \Drupal\media\OEmbed\UrlResolverInterface $url_resolver
   *   The oEmbed URL resolver service.
   * @param \Drupal\Core\Render\RendererInterface $renderer
   *   The renderer service.
   * @param \Psr\Log\LoggerInterface $logger
   *   The logger channel.
   * @param \Drupal\media\IFrameUrlHelper $iframe_url_helper
   *   The iFrame URL helper service.
   */
  public function __construct(ResourceFetcherInterface $resource_fetcher, UrlResolverInterface $url_resolver, RendererInterface $renderer, LoggerInterface $logger, IFrameUrlHelper $iframe_url_helper) {
    $this->resourceFetcher = $resource_fetcher;
    $this->urlResolver = $url_resolver;
    $this->renderer = $renderer;
    $this->logger = $logger;
    $this->iFrameUrlHelper = $iframe_url_helper;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container
      ->get('media.oembed.resource_fetcher'), $container
      ->get('media.oembed.url_resolver'), $container
      ->get('renderer'), $container
      ->get('logger.factory')
      ->get('media'), $container
      ->get('media.oembed.iframe_url_helper'));
  }

  /**
   * Renders an oEmbed resource.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *   The response object.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
   *   Will be thrown if the 'hash' parameter does not match the expected hash
   *   of the 'url' parameter.
   */
  public function render(Request $request) {
    $url = $request->query
      ->get('url');
    $max_width = $request->query
      ->getInt('max_width', NULL);
    $max_height = $request->query
      ->getInt('max_height', NULL);

    // Hash the URL and max dimensions, and ensure it is equal to the hash
    // parameter passed in the query string.
    $hash = $this->iFrameUrlHelper
      ->getHash($url, $max_width, $max_height);
    if (!hash_equals($hash, $request->query
      ->get('hash', ''))) {
      throw new AccessDeniedHttpException('This resource is not available');
    }

    // Return a response instead of a render array so that the frame content
    // will not have all the blocks and page elements normally rendered by
    // Drupal.
    $response = new HtmlResponse();
    $response
      ->addCacheableDependency(Url::createFromRequest($request));
    try {
      $resource_url = $this->urlResolver
        ->getResourceUrl($url, $max_width, $max_height);
      $resource = $this->resourceFetcher
        ->fetchResource($resource_url);
      $placeholder_token = Crypt::randomBytesBase64(55);

      // Render the content in a new render context so that the cacheability
      // metadata of the rendered HTML will be captured correctly.
      $element = [
        '#theme' => 'media_oembed_iframe',
        // Even though the resource HTML is untrusted, IFrameMarkup::create()
        // will create a trusted string. The only reason this is okay is
        // because we are serving it in an iframe, which will mitigate the
        // potential dangers of displaying third-party markup.
        '#media' => IFrameMarkup::create($resource
          ->getHtml()),
        '#cache' => [
          // Add the 'rendered' cache tag as this response is not processed by
          // \Drupal\Core\Render\MainContent\HtmlRenderer::renderResponse().
          'tags' => [
            'rendered',
          ],
        ],
        '#attached' => [
          'html_response_attachment_placeholders' => [
            'styles' => '<css-placeholder token="' . $placeholder_token . '">',
          ],
          'library' => [
            'media/oembed.frame',
          ],
        ],
        '#placeholder_token' => $placeholder_token,
      ];
      $content = $this->renderer
        ->executeInRenderContext(new RenderContext(), function () use ($resource, $element) {
        return $this->renderer
          ->render($element);
      });
      $response
        ->setContent($content)
        ->setAttachments($element['#attached'])
        ->addCacheableDependency($resource)
        ->addCacheableDependency(CacheableMetadata::createFromRenderArray($element));
    } catch (ResourceException $e) {

      // Prevent the response from being cached.
      $response
        ->setMaxAge(0);

      // The oEmbed system makes heavy use of exception wrapping, so log the
      // entire exception chain to help with troubleshooting.
      do {

        // @todo Log additional information from ResourceException, to help with
        // debugging, in https://www.drupal.org/project/drupal/issues/2972846.
        $this->logger
          ->error($e
          ->getMessage());
        $e = $e
          ->getPrevious();
      } while ($e);
    }
    return $response;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
OEmbedIframeController::$iFrameUrlHelper	protected	property	The iFrame URL helper service.
OEmbedIframeController::$logger	protected	property	The logger channel.
OEmbedIframeController::$renderer	protected	property	The renderer service.
OEmbedIframeController::$resourceFetcher	protected	property	The oEmbed resource fetcher service.
OEmbedIframeController::$urlResolver	protected	property	The oEmbed URL resolver service.
OEmbedIframeController::create	public static	function	Instantiates a new instance of this class. Overrides ContainerInjectionInterface::create
OEmbedIframeController::render	public	function	Renders an oEmbed resource.
OEmbedIframeController::__construct	public	function	Constructs an OEmbedIframeController instance.