Adds option to fail gracefully on xlink failure.

At the moment, when there is an xlink problem, the manifest parser returns a rejected promise. This adds a configuration variable to instead simply not replace the xml tag. Closes #788 Change-Id: Iace953233c83a57820130033150e7cd9a9385d6f
shaka-project · May 25, 2017 · 1e119e4 · 1e119e4
1 parent bd79d60
commit 1e119e4
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Showing 10 changed files with 102 additions and 29 deletions.
diff --git a/externs/shaka/player.js b/externs/shaka/player.js
@@ -422,7 +422,8 @@ shakaExtern.DrmConfiguration;
  * @typedef {{
  *   customScheme: shakaExtern.DashContentProtectionCallback,
  *   clockSyncUri: string,
- *   ignoreDrmInfo: boolean
+ *   ignoreDrmInfo: boolean,
+ *   xlinkFailGracefully: boolean
  * }}
  *
  * @property {shakaExtern.DashContentProtectionCallback} customScheme
@@ -437,6 +438,11 @@ shakaExtern.DrmConfiguration;
  *   If true will cause DASH parser to ignore DRM information specified
  *   by the manifest and treat it as if it signaled no particular key
  *   system and contained no init data. Defaults to false if not provided.
+ * @property {boolean} xlinkFailGracefully
+ *   If true, xlink-related errors will result in a fallback to the tag's
+ *   existing contents. If false, xlink-related errors will be propagated
+ *   to the application and will result in a playback failure. Defaults to
+ *   false if not provided.
  *
  * @exportDoc
  */

diff --git a/lib/dash/dash_parser.js b/lib/dash/dash_parser.js
@@ -420,8 +420,9 @@ shaka.dash.DashParser.prototype.parseManifest_ =
   }
 
   // Process the mpd to account for xlink connections.
+  var failGracefully = this.config_.dash.xlinkFailGracefully;
   var xlinkPromise = MpdUtils.processXlinks(
-      mpd, this.config_.retryParameters, finalManifestUri,
+      mpd, this.config_.retryParameters, failGracefully, finalManifestUri,
       this.playerInterface_.networkingEngine);
   return xlinkPromise.then(function(finalMpd) {
     return this.processManifest_(finalMpd, finalManifestUri);

diff --git a/lib/dash/mpd_utils.js b/lib/dash/mpd_utils.js
@@ -426,29 +426,44 @@ shaka.dash.MpdUtils.parseXml = function(data, expectedRootElemName) {
 
 /**
  * Follow the xlink link contained in the given element.
+ * It also strips the xlink properties off of the element,
+ * even if the process fails.
  *
  * @param {!Element} element
  * @param {!shakaExtern.RetryParameters} retryParameters
+ * @param {boolean} failGracefully
  * @param {!string} baseUri
  * @param {!shaka.net.NetworkingEngine} networkingEngine
  * @param {number} linkDepth
  * @return {!Promise.<!Element>}
  * @private
  */
 shaka.dash.MpdUtils.handleXlinkInElement_ =
-    function(element, retryParameters, baseUri, networkingEngine, linkDepth) {
+    function(element, retryParameters, failGracefully, baseUri,
+             networkingEngine, linkDepth) {
   var MpdUtils = shaka.dash.MpdUtils;
   var Error = shaka.util.Error;
   var ManifestParserUtils = shaka.util.ManifestParserUtils;
 
+  var xlinkHref = element.getAttribute('xlink:href');
+  var xlinkActuate = element.getAttribute('xlink:actuate') || 'onRequest';
+
+  // Remove the xlink properties, so it won't download again
+  // when re-processed.
+  for (var i = 0; i < element.attributes.length; i++) {
+    var attribute = element.attributes[i].nodeName;
+    if (attribute.indexOf('xlink:') != -1) {
+      element.removeAttribute(attribute);
+      i -= 1;
+    }
+  }
+
   if (linkDepth >= 5) {
     return Promise.reject(new Error(
         Error.Severity.CRITICAL, Error.Category.MANIFEST,
         Error.Code.DASH_XLINK_DEPTH_LIMIT));
   }
 
-  var xlinkHref = element.getAttribute('xlink:href');
-  var xlinkActuate = element.getAttribute('xlink:actuate') || 'onRequest';
   if (xlinkActuate != 'onLoad') {
     // Only xlink:actuate="onLoad" is supported.
     // When no value is specified, the assumed value is "onRequest".
@@ -457,16 +472,6 @@ shaka.dash.MpdUtils.handleXlinkInElement_ =
         Error.Code.DASH_UNSUPPORTED_XLINK_ACTUATE));
   }
 
-  // Remove the xlink properties, so it won't download again
-  // when re-processed.
-  for (var i = 0; i < element.attributes.length; i++) {
-    var attribute = element.attributes[i].nodeName;
-    if (attribute.indexOf('xlink:') != -1) {
-      element.removeAttribute(attribute);
-      i -= 1;
-    }
-  }
-
   // Resolve the xlink href, in case it's a relative URL.
   var uris = ManifestParserUtils.resolveUris([baseUri], [xlinkHref]);
 
@@ -486,6 +491,9 @@ shaka.dash.MpdUtils.handleXlinkInElement_ =
           Error.Code.DASH_INVALID_XML, xlinkHref));
     }
 
+    // Now that there is no other possibility of the process erroring,
+    // the element can be changed further.
+
     // Remove the current contents of the node.
     while (element.childNodes.length)
       element.removeChild(element.childNodes[0]);
@@ -505,7 +513,7 @@ shaka.dash.MpdUtils.handleXlinkInElement_ =
     }
 
     return shaka.dash.MpdUtils.processXlinks(
-        element, retryParameters, uris[0], networkingEngine,
+        element, retryParameters, failGracefully, uris[0], networkingEngine,
         linkDepth + 1);
   }.bind(element));
 };
@@ -517,20 +525,35 @@ shaka.dash.MpdUtils.handleXlinkInElement_ =
  *
  * @param {!Element} element
  * @param {!shakaExtern.RetryParameters} retryParameters
+ * @param {boolean} failGracefully
  * @param {!string} baseUri
  * @param {!shaka.net.NetworkingEngine} networkingEngine
  * @param {number=} opt_linkDepth
  * @return {!Promise.<!Element>}
  */
 shaka.dash.MpdUtils.processXlinks =
-    function(element, retryParameters, baseUri, networkingEngine,
-             opt_linkDepth) {
+    function(element, retryParameters, failGracefully, baseUri,
+             networkingEngine, opt_linkDepth) {
   var MpdUtils = shaka.dash.MpdUtils;
   opt_linkDepth = opt_linkDepth || 0;
 
-  if (element.getAttribute('xlink:href'))
-    return MpdUtils.handleXlinkInElement_(
-        element, retryParameters, baseUri, networkingEngine, opt_linkDepth);
+  if (element.getAttribute('xlink:href')) {
+    var handled = MpdUtils.handleXlinkInElement_(
+        element, retryParameters, failGracefully, baseUri,
+        networkingEngine, opt_linkDepth);
+    if (failGracefully) {
+      // Catch any error and go on.
+      handled = handled.catch(function() {
+        // handleXlinkInElement_ strips the xlink properties off of the element
+        // even if it fails, so calling processXlinks again will handle whatever
+        // contents the element natively has.
+        return MpdUtils.processXlinks(element, retryParameters, failGracefully,
+                                      baseUri, networkingEngine,
+                                      opt_linkDepth);
+      });
+    }
+    return handled;
+  }
 
   // Filter out any children that should be nulled.
   for (var i = 0; i < element.childNodes.length; i++) {
@@ -552,8 +575,8 @@ shaka.dash.MpdUtils.processXlinks =
     if (child.nodeType == Node.ELEMENT_NODE) {
       // Replace the child with its processed form.
       var childPromise = shaka.dash.MpdUtils.processXlinks(
-          /** @type {!Element} */ (child), retryParameters, baseUri,
-          networkingEngine, opt_linkDepth);
+          /** @type {!Element} */ (child), retryParameters, failGracefully,
+          baseUri, networkingEngine, opt_linkDepth);
       childPromises.push(childPromise);
     }
   }

diff --git a/lib/player.js b/lib/player.js
@@ -1716,7 +1716,8 @@ shaka.Player.prototype.defaultConfig_ = function() {
           if (node) return null;
         },
         clockSyncUri: '',
-        ignoreDrmInfo: false
+        ignoreDrmInfo: false,
+        xlinkFailGracefully: false
       },
       hls: {
         defaultTimeOffset: 0

diff --git a/test/dash/dash_parser_content_protection_unit.js b/test/dash/dash_parser_content_protection_unit.js
@@ -42,7 +42,8 @@ describe('DashParser ContentProtection', function() {
       dash: {
         clockSyncUri: '',
         customScheme: callback,
-        ignoreDrmInfo: ignoreDrmInfo
+        ignoreDrmInfo: ignoreDrmInfo,
+        xlinkFailGracefully: false
       },
       hls: { defaultTimeOffset: 0 }
     });

diff --git a/test/dash/dash_parser_live_unit.js b/test/dash/dash_parser_live_unit.js
@@ -44,7 +44,8 @@ describe('DashParser Live', function() {
       dash: {
         clockSyncUri: '',
         customScheme: function(node) { return null; },
-        ignoreDrmInfo: false
+        ignoreDrmInfo: false,
+        xlinkFailGracefully: false
       },
       hls: { defaultTimeOffset: 0 }
     });

diff --git a/test/dash/dash_parser_manifest_unit.js b/test/dash/dash_parser_manifest_unit.js
@@ -652,6 +652,27 @@ describe('DashParser Manifest', function() {
       Dash.testFails(done, source, error);
     });
 
+    it('xlink problems when xlinkFailGracefully is false', function(done) {
+      var source = [
+        '<MPD minBufferTime="PT75S" xmlns="urn:mpeg:dash:schema:mpd:2011" ' +
+            'xmlns:xlink="http://www.w3.org/1999/xlink">',
+        '  <Period id="1" duration="PT30S">',
+        '    <AdaptationSet mimeType="video/mp4">',
+        '      <Representation bandwidth="1" xlink:href="https://xlink1" ' +
+            'xlink:actuate="onInvalid">', // Incorrect actuate
+        '        <SegmentBase indexRange="100-200" />',
+        '      </Representation>',
+        '    </AdaptationSet>',
+        '  </Period>',
+        '</MPD>'
+      ].join('\n');
+      var error = new shaka.util.Error(
+          shaka.util.Error.Severity.CRITICAL,
+          shaka.util.Error.Category.MANIFEST,
+          shaka.util.Error.Code.DASH_UNSUPPORTED_XLINK_ACTUATE);
+      Dash.testFails(done, source, error);
+    });
+
     it('failed network requests', function(done) {
       var expectedError = new shaka.util.Error(
           shaka.util.Error.Severity.CRITICAL,

diff --git a/test/dash/mpd_utils_unit.js b/test/dash/mpd_utils_unit.js
@@ -438,8 +438,10 @@ describe('MpdUtils', function() {
     var retry;
     var parser;
     var Error = shaka.util.Error;
+    var failGracefully;
 
     beforeEach(function() {
+      failGracefully = false;
       retry = shaka.net.NetworkingEngine.defaultRetryParameters();
       fakeNetEngine = new shaka.test.FakeNetworkingEngine();
       parser = new DOMParser();
@@ -622,6 +624,20 @@ describe('MpdUtils', function() {
       testFails(baseXMLString, null, 1, done);
     });
 
+    it('doesn\'t error when set to fail gracefully', function(done) {
+      failGracefully = true;
+      var baseXMLString = inBaseContainer(
+          '<ToReplace xlink:href="https://xlink1" xlink:actuate="onLoad">' +
+          '<DefaultContents />' +
+          '</ToReplace>');
+      var xlinkXMLString = '<BadTagName</BadTagName>';
+      var desiredXMLString = inBaseContainer(
+          '<ToReplace><DefaultContents /></ToReplace>');
+
+      fakeNetEngine.setResponseMapAsText({'https://xlink1': xlinkXMLString});
+      testSucceeds(baseXMLString, desiredXMLString, 1, done);
+    });
+
     function testSucceeds(
         baseXMLString, desiredXMLString, desiredNetCalls, done) {
       var desiredXML = parser.parseFromString(desiredXMLString, 'text/xml')
@@ -682,7 +698,8 @@ describe('MpdUtils', function() {
     function testRequest(baseXMLString) {
       var xml = parser.parseFromString(baseXMLString, 'text/xml')
           .documentElement;
-      return MpdUtils.processXlinks(xml, retry, 'https://base', fakeNetEngine);
+      return MpdUtils.processXlinks(xml, retry, failGracefully, 'https://base',
+                                    fakeNetEngine);
     }
   });
 });
diff --git a/test/hls/hls_parser_unit.js b/test/hls/hls_parser_unit.js
@@ -30,7 +30,8 @@ describe('HlsParser', function() {
       dash: {
         customScheme: function(node) { return null; },
         clockSyncUri: '',
-        ignoreDrmInfo: false
+        ignoreDrmInfo: false,
+        xlinkFailGracefully: false
       },
       hls: {
         defaultTimeOffset: 0

diff --git a/test/test/util/dash_parser_util.js b/test/test/util/dash_parser_util.js
@@ -30,7 +30,8 @@ shaka.test.Dash.makeDashParser = function() {
     dash: {
       customScheme: function(node) { return null; },
       clockSyncUri: '',
-      ignoreDrmInfo: false
+      ignoreDrmInfo: false,
+      xlinkFailGracefully: false
     },
     hls: { defaultTimeOffset: 0 }
   });