Only use configured license servers if provided

If the application developer specifies license servers, only those
should be used.  Before this, a manifest-specified license server
for a certain key system could still be used if the application didn't
provide one.

Now, if there are _any_ license servers specified by the app, _no_
license servers will be used from the manifest.  This is important
because it allows the application a clear way to indicate which DRM
systems should be used on platforms with multiple DRM systems.

The new order of preference for drmInfo:
1. Clear Key config, used for debugging, should override everything else.
   (The application can still specify a clearkey license server.)
2. Application-configured servers, if any are present, should override
   anything from the manifest.  Nuance: if key system A is in the manifest
   and key system B is in the player config, only B will be used, not A.
3. Manifest-provided license servers are only used if nothing else is
   specified.

Introduced in #1644 to solve #484
Internal issue b/131264101
Closes #1905

Change-Id: I1a36a70044dc7bcc22681e3e4246d0a43d58e413

lib/media/drm_engine.js

@@ -918,7 +918,8 @@ shaka.media.DrmEngine.prototype.queryMediaKeys_ = function(configsByKeySystem) {
       return Promise.reject(new shaka.util.Error(
           shaka.util.Error.Severity.CRITICAL,
           shaka.util.Error.Category.DRM,
-          shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN));
+          shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN,
+          this.currentDrmInfo_.keySystem));
     }
 
     return mediaKeySystemAccess.createMediaKeys();
@@ -1931,24 +1932,44 @@ shaka.media.DrmEngine.processDrmInfos_ =
  */
 shaka.media.DrmEngine.fillInDrmInfoDefaults_ = function(
     drmInfo, servers, advancedConfigs) {
-  const keySystem = drmInfo.keySystem;
-
-  if (!keySystem) {
+  if (!drmInfo.keySystem) {
     // This is a placeholder from the manifest parser for an unrecognized key
     // system.  Skip this entry, to avoid logging nonsensical errors.
     return;
   }
 
-  const server = servers.get(keySystem);
-  if (server) {
+  // The order of preference for drmInfo:
+  // 1. Clear Key config, used for debugging, should override everything else.
+  //    (The application can still specify a clearkey license server.)
+  // 2. Application-configured servers, if any are present, should override
+  //    anything from the manifest.  Nuance: if key system A is in the manifest
+  //    and key system B is in the player config, only B will be used, not A.
+  // 3. Manifest-provided license servers are only used if nothing else is
+  //    specified.
+  // This is important because it allows the application a clear way to indicate
+  // which DRM systems should be used on platforms with multiple DRM systems.
+  // The only way to get license servers from the manifest is not to specify any
+  // in your player config.
+
+  if (drmInfo.keySystem == 'org.w3.clearkey' && drmInfo.licenseServerUri) {
+    // Preference 1: Clear Key with pre-configured keys will have a data URI
+    // assigned as its license server.  Don't change anything.
+    return;
+  } else if (servers.size) {
+    // Preference 2: If anything is configured at the application level,
+    // override whatever was in the manifest.
+    const server = servers.get(drmInfo.keySystem) || '';
     drmInfo.licenseServerUri = server;
+  } else {
+    // Preference 3: Keep whatever we had in drmInfo.licenseServerUri, which
+    // comes from the manifest.
   }
 
   if (!drmInfo.keyIds) {
     drmInfo.keyIds = [];
   }
 
-  const advancedConfig = advancedConfigs.get(keySystem);
+  const advancedConfig = advancedConfigs.get(drmInfo.keySystem);
   if (advancedConfig) {
     if (!drmInfo.distinctiveIdentifierRequired) {
       drmInfo.distinctiveIdentifierRequired =

lib/util/error.js

@@ -702,6 +702,7 @@ shaka.util.Error.Code = {
   /**
    * No license server was given for the key system signaled by the manifest.
    * A license server URI is required for every key system.
+   * <br> error.data[0] is the key system identifier.
    */
   'NO_LICENSE_SERVER_GIVEN': 6012,
 

test/media/drm_engine_unit.js

@@ -221,6 +221,46 @@ describe('DrmEngine', function() {
       }
     });
 
+    it('overrides manifest with configured license servers', async () => {
+      // Accept both drm.abc and drm.def.  Only one can be chosen.
+      requestMediaKeySystemAccessSpy.and.callFake(
+          fakeRequestMediaKeySystemAccess.bind(null, ['drm.abc', 'drm.def']));
+
+      // Add manifest-supplied license servers for both.
+      for (const drmInfo of manifest.periods[0].variants[0].drmInfos) {
+        if (drmInfo.keySystem == 'drm.abc') {
+          drmInfo.licenseServerUri = 'http://foo.bar/abc';
+        } else if (drmInfo.keySystem == 'drm.def') {
+          drmInfo.licenseServerUri = 'http://foo.bar/def';
+        }
+
+        // Make sure we didn't somehow choose manifest-supplied values that
+        // match the config.  This would invalidate parts of the test.
+        const configServer = config.servers[drmInfo.keySystem];
+        expect(drmInfo.licenseServerUri).not.toEqual(configServer);
+      }
+
+      // Remove the server URI for drm.abc from the config, so that only drm.def
+      // could be used, in spite of the manifest-supplied license server URI.
+      delete config.servers['drm.abc'];
+      drmEngine.configure(config);
+
+      // Ignore error logs, which we expect to occur due to the missing server.
+      logErrorSpy.and.stub();
+
+      const variants = Periods.getAllVariantsFrom(manifest.periods);
+      await drmEngine.initForPlayback(variants, manifest.offlineSessionIds);
+
+      // Although drm.def appears second in the manifest, it is queried first
+      // because it has a server configured.  The manifest-supplied server for
+      // drm.abc will not be used.
+      expect(requestMediaKeySystemAccessSpy.calls.count()).toBe(1);
+      const selectedDrmInfo = drmEngine.getDrmInfo();
+      expect(selectedDrmInfo).not.toBe(null);
+      expect(selectedDrmInfo.keySystem).toBe('drm.def');
+      expect(selectedDrmInfo.licenseServerUri).toBe(config.servers['drm.def']);
+    });
+
     it('detects content type capabilities of key system', async () => {
       requestMediaKeySystemAccessSpy.and.callFake(
           fakeRequestMediaKeySystemAccess.bind(null, ['drm.abc']));
@@ -472,7 +512,7 @@ describe('DrmEngine', function() {
       expect(requestMediaKeySystemAccessSpy.calls.count()).toBe(1);
     });
 
-    it('uses advanced config to override DrmInfo fields', async () => {
+    it('uses advanced config to fill in DrmInfo', async () => {
       // Leave only one drmInfo
       manifest = new shaka.test.ManifestGenerator()
         .addPeriod(0)
@@ -516,7 +556,7 @@ describe('DrmEngine', function() {
       }
     });
 
-    it('does not use config if DrmInfo already filled out', async () => {
+    it('prefers advanced config from manifest if present', async () => {
       // Leave only one drmInfo
       manifest = new shaka.test.ManifestGenerator()
         .addPeriod(0)
@@ -585,7 +625,8 @@ describe('DrmEngine', function() {
         shaka.test.Util.expectToEqualError(error, new shaka.util.Error(
             shaka.util.Error.Severity.CRITICAL,
             shaka.util.Error.Category.DRM,
-            shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN));
+            shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN,
+            'drm.abc'));
       }
     });
   });  // describe('init')