DRM: Fix potential race condition issues on setMediaKeys and quick content switching

src/main_thread/decrypt/clear_on_stop.ts

@@ -18,22 +18,22 @@ import type { IMediaElement } from "../../compat/browser_compatibility_types";
 import shouldUnsetMediaKeys from "../../compat/should_unset_media_keys";
 import log from "../../log";
 import disposeDecryptionResources from "./dispose_decryption_resources";
-import MediaKeysInfosStore from "./utils/media_keys_infos_store";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 /**
  * Clear DRM-related resources that should be cleared when the current content
  * stops its playback.
  * @param {HTMLMediaElement} mediaElement
  * @returns {Promise}
  */
-export default function clearOnStop(mediaElement: IMediaElement): Promise<unknown> {
+export default async function clearOnStop(mediaElement: IMediaElement): Promise<unknown> {
   log.info("DRM: Clearing-up DRM session.");
   if (shouldUnsetMediaKeys()) {
     log.info("DRM: disposing current MediaKeys.");
     return disposeDecryptionResources(mediaElement);
   }
 
-  const currentState = MediaKeysInfosStore.getState(mediaElement);
+  const currentState = await MediaKeysAttacher.getAttachedMediaKeysState(mediaElement);
   if (
     currentState !== null &&
     currentState.keySystemOptions.closeSessionsOnStop === true

src/main_thread/decrypt/content_decryptor.ts

@@ -30,7 +30,6 @@ import isNullOrUndefined from "../../utils/is_null_or_undefined";
 import { objectValues } from "../../utils/object_values";
 import { bytesToHex } from "../../utils/string_parsing";
 import TaskCanceller from "../../utils/task_canceller";
-import attachMediaKeys from "./attach_media_keys";
 import createOrLoadSession from "./create_or_load_session";
 import type { ICodecSupportList } from "./find_key_system";
 import type { IMediaKeysInfos } from "./get_media_keys";
@@ -57,6 +56,7 @@ import {
   areSomeKeyIdsContainedIn,
 } from "./utils/key_id_comparison";
 import type KeySessionRecord from "./utils/key_session_record";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 /**
  * Module communicating with the Content Decryption Module (or CDM) to be able
@@ -287,8 +287,12 @@ export default class ContentDecryptor extends EventEmitter<IContentDecryptorEven
     };
 
     log.debug("DRM: Attaching current MediaKeys");
-    attachMediaKeys(mediaElement, stateToAttach, this._canceller.signal)
+    MediaKeysAttacher.attach(mediaElement, stateToAttach)
       .then(async () => {
+        if (this._isStopped()) {
+          // We might be stopped since then
+          return;
+        }
         this._stateData.isMediaKeysAttached = MediaKeyAttachmentStatus.Attached;
 
         const { serverCertificate } = options;

src/main_thread/decrypt/dispose_decryption_resources.ts

@@ -15,9 +15,7 @@
  */
 
 import type { IMediaElement } from "../../compat/browser_compatibility_types";
-import { setMediaKeys } from "../../compat/eme/set_media_keys";
-import log from "../../log";
-import MediaKeysInfosStore from "./utils/media_keys_infos_store";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 /**
  * Free up all ressources taken by the content decryption logic.
@@ -27,14 +25,5 @@ import MediaKeysInfosStore from "./utils/media_keys_infos_store";
 export default async function disposeDecryptionResources(
   mediaElement: IMediaElement,
 ): Promise<unknown> {
-  const currentState = MediaKeysInfosStore.getState(mediaElement);
-  if (currentState === null) {
-    return undefined;
-  }
-
-  log.info("DRM: Disposing of the current MediaKeys");
-  const { loadedSessionsStore } = currentState;
-  MediaKeysInfosStore.clearState(mediaElement);
-  await loadedSessionsStore.closeAllSessions();
-  return setMediaKeys(currentState.emeImplementation, mediaElement, null);
+  return MediaKeysAttacher.clearMediaKeys(mediaElement);
 }

src/main_thread/decrypt/find_key_system.ts

@@ -32,7 +32,7 @@ import arrayIncludes from "../../utils/array_includes";
 import flatMap from "../../utils/flat_map";
 import isNullOrUndefined from "../../utils/is_null_or_undefined";
 import type { CancellationSignal } from "../../utils/task_canceller";
-import MediaKeysInfosStore from "./utils/media_keys_infos_store";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 type MediaKeysRequirement = "optional" | "required" | "not-allowed";
 
@@ -445,7 +445,7 @@ export default function getMediaKeySystemAccess(
 
     const chosenType = keySystemsType[index];
 
-    const currentState = MediaKeysInfosStore.getState(mediaElement);
+    const currentState = await MediaKeysAttacher.getAttachedMediaKeysState(mediaElement);
     if (currentState !== null) {
       if (eme.implementation === currentState.emeImplementation.implementation) {
         // Fast way to find a compatible keySystem if the currently loaded

src/main_thread/decrypt/get_key_system_configuration.ts

@@ -15,7 +15,7 @@
  */
 
 import type { IMediaElement } from "../../compat/browser_compatibility_types";
-import MediaKeysInfosStore from "./utils/media_keys_infos_store";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 /**
  * Returns the name of the current key system used as well as its configuration,
@@ -26,7 +26,7 @@ import MediaKeysInfosStore from "./utils/media_keys_infos_store";
 export default function getKeySystemConfiguration(
   mediaElement: IMediaElement,
 ): [string, MediaKeySystemConfiguration] | null {
-  const currentState = MediaKeysInfosStore.getState(mediaElement);
+  const currentState = MediaKeysAttacher.getAwaitedState(mediaElement);
   if (currentState === null) {
     return null;
   }

src/main_thread/decrypt/get_media_keys.ts

@@ -26,7 +26,7 @@ import getMediaKeySystemAccess from "./find_key_system";
 import type { ICodecSupportList } from "./find_key_system";
 import type { IMediaKeySessionStores } from "./types";
 import LoadedSessionsStore from "./utils/loaded_sessions_store";
-import MediaKeysInfosStore from "./utils/media_keys_infos_store";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 import PersistentSessionsStore from "./utils/persistent_sessions_store";
 import ServerCertificateStore from "./utils/server_certificate_store";
 
@@ -94,7 +94,7 @@ export default async function getMediaKeysInfos(
   }
 
   const { options, mediaKeySystemAccess, askedConfiguration, codecSupport } = evt.value;
-  const currentState = MediaKeysInfosStore.getState(mediaElement);
+  const currentState = await MediaKeysAttacher.getAttachedMediaKeysState(mediaElement);
   const persistentSessionsStore = createPersistentSessionsStorage(options);
 
   if (

src/main_thread/decrypt/init_media_keys.ts

@@ -18,9 +18,9 @@ import type { IMediaElement } from "../../compat/browser_compatibility_types";
 import log from "../../log";
 import type { IKeySystemOption } from "../../public_types";
 import type { CancellationSignal } from "../../utils/task_canceller";
-import { disableMediaKeys } from "./attach_media_keys";
 import type { IMediaKeysInfos } from "./get_media_keys";
 import getMediaKeysInfos from "./get_media_keys";
+import MediaKeysAttacher from "./utils/media_keys_attacher";
 
 /**
  * Get media keys infos from key system configs then attach media keys to media element.
@@ -48,7 +48,7 @@ export default async function initMediaKeys(
 
   if (shouldDisableOldMediaKeys) {
     log.debug("DRM: Disabling old MediaKeys");
-    await disableMediaKeys(mediaElement);
+    await MediaKeysAttacher.clearMediaKeys(mediaElement);
   }
   return mediaKeysInfo;
 }