Issue #2801097 by dawehner, Berdir: Converting feed to absolute URLs fails on...

Issue #2801097 by dawehner, Berdir: Converting feed to absolute URLs fails on invalid XML, results in empty output

core/lib/Drupal/Core/EventSubscriber/RssResponseRelativeUrlFilter.php

@@ -44,7 +44,16 @@ public function onResponse(FilterResponseEvent $event) {
    */
   protected function transformRootRelativeUrlsToAbsolute($rss_markup, Request $request) {
     $rss_dom = new \DOMDocument();
+
+    // Load the RSS, if there are parsing errors, abort and return the unchanged
+    // markup.
+    $previous_value = libxml_use_internal_errors(TRUE);
     $rss_dom->loadXML($rss_markup);
+    $errors = libxml_get_errors();
+    libxml_use_internal_errors($previous_value);
+    if ($errors) {
+      return $rss_markup;
+    }
 
     // Invoke Html::transformRootRelativeUrlsToAbsolute() on all HTML content
     // embedded in this RSS feed.

core/tests/Drupal/Tests/Core/EventSubscriber/RssResponseRelativeUrlFilterTest.php

+<?php
+
+namespace Drupal\Tests\Core\EventSubscriber;
+
+use Drupal\Core\EventSubscriber\RssResponseRelativeUrlFilter;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+
+/**
+ * @coversDefaultClass \Drupal\Core\EventSubscriber\RssResponseRelativeUrlFilter
+ * @group event_subscriber
+ */
+class RssResponseRelativeUrlFilterTest extends UnitTestCase {
+
+  public function providerTestOnResponse() {
+    $data = [];
+
+    $valid_feed = <<<RSS
+<?xml version="1.0" encoding="utf-8"?>
+<rss xmlns:dc="http://purl.org/dc/elements/1.1/" version="2.0" xml:base="https://www.drupal.org">
+<channel>
+  <title>Drupal.org</title>
+  <link>https://www.drupal.org</link>
+  <description>Come for the software, stay for the community
+D rupal is an open source content management platform powering millions of websites and applications. It’s built, used, and supported by an active and diverse community of people around the world.</description>
+  <language>en</language>
+  <item>
+     <title>Drupal 8 turns one!</title>
+     <link>https://www.drupal.org/blog/drupal-8-turns-one</link>
+     <description>&lt;a href=&quot;localhost/node/1&quot;&gt;Hello&lt;/a&gt;
+    </description>
+  </item>
+  </channel>
+</rss>
+RSS;
+
+    $valid_expected_feed = <<<RSS
+<?xml version="1.0" encoding="utf-8"?>
+<rss xmlns:dc="http://purl.org/dc/elements/1.1/" version="2.0" xml:base="https://www.drupal.org">
+<channel>
+  <title>Drupal.org</title>
+  <link>https://www.drupal.org</link>
+  <description>Come for the software, stay for the community
+D rupal is an open source content management platform powering millions of websites and applications. It’s built, used, and supported by an active and diverse community of people around the world.</description>
+  <language>en</language>
+  <item>
+     <title>Drupal 8 turns one!</title>
+     <link>https://www.drupal.org/blog/drupal-8-turns-one</link>
+     <description>&lt;a href="localhost/node/1"&gt;Hello&lt;/a&gt;
+    </description>
+  </item>
+  </channel>
+</rss>
+
+RSS;
+
+    $data['valid-feed'] = [$valid_feed, $valid_expected_feed];
+
+    $invalid_feed = <<<RSS
+<?xml version="1.0" encoding="utf-8"?>
+<rss version="2.0" xml:base="https://www.drupal.org"  xmlns:dc="http://purl.org/dc/elements/1.1/">
+<channel>
+  <title>Drupal.org</title>
+  <link>https://www.drupal.org</link>
+  <description>Come for the software, stay for the community
+D rupal is an open source content management platform powering millions of websites and applications. It’s built, used, and supported by an active and diverse community of people around the world.</description>
+  <language>en</language>
+  <item>
+     <title>Drupal 8 turns one!</title>
+     <link>https://www.drupal.org/blog/drupal-8-turns-one</link>
+     <description>
+     <![CDATA[
+     &lt;a href="localhost/node/1"&gt;Hello&lt;/a&gt;
+     <script>
+<!--//--><![CDATA[// ><!--
+
+<!--//--><![CDATA[// ><!--
+
+<!--//--><![CDATA[// ><!--
+(function(d, s, id) {
+  var js, fjs = d.getElementsByTagName(s)[0];
+  if (d.getElementById(id)) return;
+  js = d.createElement(s); js.id = id;
+  js.src = "//connect.facebook.net/de_DE/sdk.js#xfbml=1&version=v2.3";
+  fjs.parentNode.insertBefore(js, fjs);
+}(document, 'script', 'facebook-jssdk'));
+//--><!]]]]]]><![CDATA[><![CDATA[>
+
+//--><!]]]]><![CDATA[>
+
+//--><!]]>
+</script>
+    ]]>
+    </description>
+  </item>
+  </channel>
+</rss>
+RSS;
+
+
+    $data['invalid-feed'] = [$invalid_feed, $invalid_feed];
+    return $data;
+  }
+
+  /**
+   * @dataProvider providerTestOnResponse
+   *
+   * @param string $content
+   * @param string $expected_content
+   */
+  public function testOnResponse($content, $expected_content) {
+    $event = new FilterResponseEvent(
+      $this->prophesize(HttpKernelInterface::class)->reveal(),
+      Request::create('/'),
+      'foo',
+      new Response($content, 200, [
+        'Content-Type' => 'application/rss+xml'
+      ])
+    );
+
+    $url_filter = new RssResponseRelativeUrlFilter();
+    $url_filter->onResponse($event);
+
+    $this->assertEquals($expected_content, $event->getResponse()->getContent());
+  }
+
+}