shaka-player/lib/drm/drm_engine.js

DASH/EME video player library

/*! @license
 * Shaka Player
 * Copyright 2016 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

goog.provide('shaka.drm.DrmEngine');

goog.require('goog.asserts');
goog.require('shaka.debug.RunningInLab');
goog.require('shaka.log');
goog.require('shaka.drm.DrmUtils');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.util.ArrayUtils');
goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.Destroyer');
goog.require('shaka.util.Error');
goog.require('shaka.util.EventManager');
goog.require('shaka.util.FakeEvent');
goog.require('shaka.util.Functional');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.Iterables');
goog.require('shaka.util.ManifestParserUtils');
goog.require('shaka.util.MapUtils');
goog.require('shaka.util.ObjectUtils');
goog.require('shaka.util.Platform');
goog.require('shaka.util.Pssh');
goog.require('shaka.util.PublicPromise');
goog.require('shaka.util.StreamUtils');
goog.require('shaka.util.StringUtils');
goog.require('shaka.util.Timer');
goog.require('shaka.util.TXml');
goog.require('shaka.util.Uint8ArrayUtils');


/** @implements {shaka.util.IDestroyable} */
shaka.drm.DrmEngine = class {
  /**
   * @param {shaka.drm.DrmEngine.PlayerInterface} playerInterface
   */
  constructor(playerInterface) {
    /** @private {?shaka.drm.DrmEngine.PlayerInterface} */
    this.playerInterface_ = playerInterface;

    /** @private {MediaKeys} */
    this.mediaKeys_ = null;

    /** @private {HTMLMediaElement} */
    this.video_ = null;

    /** @private {boolean} */
    this.initialized_ = false;

    /** @private {boolean} */
    this.initializedForStorage_ = false;

    /** @private {number} */
    this.licenseTimeSeconds_ = 0;

    /** @private {?shaka.extern.DrmInfo} */
    this.currentDrmInfo_ = null;

    /** @private {shaka.util.EventManager} */
    this.eventManager_ = new shaka.util.EventManager();

    /**
     * @private {!Map<MediaKeySession,
     *           shaka.drm.DrmEngine.SessionMetaData>}
     */
    this.activeSessions_ = new Map();

    /** @private {!Array<!shaka.net.NetworkingEngine.PendingRequest>} */
    this.activeRequests_ = [];

    /**
     * @private {!Map<string,
     *           {initData: ?Uint8Array, initDataType: ?string}>}
     */
    this.storedPersistentSessions_ = new Map();

    /** @private {boolean} */
    this.hasInitData_ = false;

    /** @private {!shaka.util.PublicPromise} */
    this.allSessionsLoaded_ = new shaka.util.PublicPromise();

    /** @private {?shaka.extern.DrmConfiguration} */
    this.config_ = null;

    /** @private {function(!shaka.util.Error)} */
    this.onError_ = (err) => {
      if (err.severity == shaka.util.Error.Severity.CRITICAL) {
        this.allSessionsLoaded_.reject(err);
      }

      playerInterface.onError(err);
    };

    /**
     * The most recent key status information we have.
     * We may not have announced this information to the outside world yet,
     * which we delay to batch up changes and avoid spurious "missing key"
     * errors.
     * @private {!Map<string, string>}
     */
    this.keyStatusByKeyId_ = new Map();

    /**
     * The key statuses most recently announced to other classes.
     * We may have more up-to-date information being collected in
     * this.keyStatusByKeyId_, which has not been batched up and released yet.
     * @private {!Map<string, string>}
     */
    this.announcedKeyStatusByKeyId_ = new Map();

    /** @private {shaka.util.Timer} */
    this.keyStatusTimer_ =
        new shaka.util.Timer(() => this.processKeyStatusChanges_());

    /** @private {boolean} */
    this.usePersistentLicenses_ = false;

    /** @private {!Array<!MediaKeyMessageEvent>} */
    this.mediaKeyMessageEvents_ = [];

    /** @private {boolean} */
    this.initialRequestsSent_ = false;

    /** @private {?shaka.util.Timer} */
    this.expirationTimer_ = new shaka.util.Timer(() => {
      this.pollExpiration_();
    });

    // Add a catch to the Promise to avoid console logs about uncaught errors.
    const noop = () => {};
    this.allSessionsLoaded_.catch(noop);

    /** @const {!shaka.util.Destroyer} */
    this.destroyer_ = new shaka.util.Destroyer(() => this.destroyNow_());

    /** @private {boolean} */
    this.srcEquals_ = false;

    /** @private {Promise} */
    this.mediaKeysAttached_ = null;

    /** @private {?shaka.extern.InitDataOverride} */
    this.manifestInitData_ = null;

    /** @private {function():boolean} */
    this.isPreload_ = () => false;
  }

  /** @override */
  destroy() {
    return this.destroyer_.destroy();
  }

  /**
   * Destroy this instance of DrmEngine. This assumes that all other checks
   * about "if it should" have passed.
   *
   * @private
   */
  async destroyNow_() {
    // |eventManager_| should only be |null| after we call |destroy|. Destroy it
    // first so that we will stop responding to events.
    this.eventManager_.release();
    this.eventManager_ = null;

    // Since we are destroying ourselves, we don't want to react to the "all
    // sessions loaded" event.
    this.allSessionsLoaded_.reject();

    // Stop all timers. This will ensure that they do not start any new work
    // while we are destroying ourselves.
    this.expirationTimer_.stop();
    this.expirationTimer_ = null;

    this.keyStatusTimer_.stop();
    this.keyStatusTimer_ = null;

    // Close all open sessions.
    await this.closeOpenSessions_();

    // |video_| will be |null| if we never attached to a video element.
    if (this.video_) {
      // Webkit EME implementation requires the src to be defined to clear
      // the MediaKeys.
      if (!shaka.drm.DrmUtils.isMediaKeysPolyfilled('webkit')) {
        goog.asserts.assert(
            !this.video_.src &&
            !this.video_.getElementsByTagName('source').length,
            'video src must be removed first!');
      }

      try {
        await this.video_.setMediaKeys(null);
      } catch (error) {
        // Ignore any failures while removing media keys from the video element.
        shaka.log.debug(`DrmEngine.destroyNow_ exception`, error);
      }

      this.video_ = null;
    }

    // Break references to everything else we hold internally.
    this.currentDrmInfo_ = null;
    this.mediaKeys_ = null;
    this.storedPersistentSessions_ = new Map();
    this.config_ = null;
    this.onError_ = () => {};
    this.playerInterface_ = null;
    this.srcEquals_ = false;
    this.mediaKeysAttached_ = null;
  }

  /**
   * Called by the Player to provide an updated configuration any time it
   * changes.
   * Must be called at least once before init().
   *
   * @param {shaka.extern.DrmConfiguration} config
   * @param {(function():boolean)=} isPreload
   */
  configure(config, isPreload) {
    this.config_ = config;
    if (isPreload) {
      this.isPreload_ = isPreload;
    }
    if (this.expirationTimer_) {
      this.expirationTimer_.tickEvery(
          /* seconds= */ this.config_.updateExpirationTime);
    }
  }

  /**
   * @param {!boolean} value
   */
  setSrcEquals(value) {
    this.srcEquals_ = value;
  }

  /**
   * Initialize the drm engine for storing and deleting stored content.
   *
   * @param {!Array<shaka.extern.Variant>} variants
   *    The variants that are going to be stored.
   * @param {boolean} usePersistentLicenses
   *    Whether or not persistent licenses should be requested and stored for
   *    |manifest|.
   * @return {!Promise}
   */
  initForStorage(variants, usePersistentLicenses) {
    this.initializedForStorage_ = true;
    // There are two cases for this call:
    //  1. We are about to store a manifest - in that case, there are no offline
    //     sessions and therefore no offline session ids.
    //  2. We are about to remove the offline sessions for this manifest - in
    //     that case, we don't need to know about them right now either as
    //     we will be told which ones to remove later.
    this.storedPersistentSessions_ = new Map();

    // What we really need to know is whether or not they are expecting to use
    // persistent licenses.
    this.usePersistentLicenses_ = usePersistentLicenses;

    return this.init_(variants, /* isLive= */ false);
  }

  /**
   * Initialize the drm engine for playback operations.
   *
   * @param {!Array<shaka.extern.Variant>} variants
   *    The variants that we want to support playing.
   * @param {!Array<string>} offlineSessionIds
   * @param {boolean=} isLive
   * @return {!Promise}
   */
  initForPlayback(variants, offlineSessionIds, isLive = true) {
    this.storedPersistentSessions_ = new Map();

    for (const sessionId of offlineSessionIds) {
      this.storedPersistentSessions_.set(
          sessionId, {initData: null, initDataType: null});
    }

    for (const metadata of this.config_.persistentSessionsMetadata) {
      this.storedPersistentSessions_.set(
          metadata.sessionId,
          {initData: metadata.initData, initDataType: metadata.initDataType});
    }

    this.usePersistentLicenses_ = this.storedPersistentSessions_.size > 0;

    return this.init_(variants, isLive);
  }

  /**
   * Initializes the drm engine for removing persistent sessions.  Only the
   * removeSession(s) methods will work correctly, creating new sessions may not
   * work as desired.
   *
   * @param {string} keySystem
   * @param {string} licenseServerUri
   * @param {Uint8Array} serverCertificate
   * @param {!Array<MediaKeySystemMediaCapability>} audioCapabilities
   * @param {!Array<MediaKeySystemMediaCapability>} videoCapabilities
   * @return {!Promise}
   */
  initForRemoval(keySystem, licenseServerUri, serverCertificate,
      audioCapabilities, videoCapabilities) {
    /** @type {!Map<string, MediaKeySystemConfiguration>} */
    const configsByKeySystem = new Map();

    /** @type {MediaKeySystemConfiguration} */
    const config = {
      audioCapabilities: audioCapabilities,
      videoCapabilities: videoCapabilities,
      distinctiveIdentifier: 'optional',
      persistentState: 'required',
      sessionTypes: ['persistent-license'],
      label: keySystem,  // Tracked by us, ignored by EME.
    };

    // TODO: refactor, don't stick drmInfos onto MediaKeySystemConfiguration
    config['drmInfos'] = [{  // Non-standard attribute, ignored by EME.
      keySystem: keySystem,
      licenseServerUri: licenseServerUri,
      distinctiveIdentifierRequired: false,
      persistentStateRequired: true,
      audioRobustness: '',  // Not required by queryMediaKeys_
      videoRobustness: '',  // Same
      serverCertificate: serverCertificate,
      serverCertificateUri: '',
      initData: null,
      keyIds: null,
    }];

    configsByKeySystem.set(keySystem, config);
    return this.queryMediaKeys_(configsByKeySystem,
        /* variants= */ []);
  }

  /**
   * Negotiate for a key system and set up MediaKeys.
   * This will assume that both |usePersistentLicences_| and
   * |storedPersistentSessions_| have been properly set.
   *
   * @param {!Array<shaka.extern.Variant>} variants
   *    The variants that we expect to operate with during the drm engine's
   *    lifespan of the drm engine.
   * @param {boolean} isLive
   * @return {!Promise} Resolved if/when a key system has been chosen.
   * @private
   */
  async init_(variants, isLive) {
    goog.asserts.assert(this.config_,
        'DrmEngine configure() must be called before init()!');

    shaka.drm.DrmEngine.configureClearKey(this.config_.clearKeys, variants);

    const hadDrmInfo = variants.some((variant) => {
      if (variant.video && variant.video.drmInfos.length) {
        return true;
      }
      if (variant.audio && variant.audio.drmInfos.length) {
        return true;
      }
      return false;
    });

    // When preparing to play live streams, it is possible that we won't know
    // about some upcoming encrypted content. If we initialize the drm engine
    // with no key systems, we won't be able to play when the encrypted content
    // comes.
    //
    // To avoid this, we will set the drm engine up to work with as many key
    // systems as possible so that we will be ready.
    if (!hadDrmInfo && isLive) {
      const servers = shaka.util.MapUtils.asMap(this.config_.servers);
      shaka.drm.DrmEngine.replaceDrmInfo_(variants, servers);
    }

    /** @type {!Set<shaka.extern.DrmInfo>} */
    const drmInfos = new Set();
    for (const variant of variants) {
      const variantDrmInfos = this.getVariantDrmInfos_(variant);
      for (const info of variantDrmInfos) {
        drmInfos.add(info);
      }
    }

    for (const info of drmInfos) {
      shaka.drm.DrmEngine.fillInDrmInfoDefaults_(
          info,
          shaka.util.MapUtils.asMap(this.config_.servers),
          shaka.util.MapUtils.asMap(this.config_.advanced || {}),
          this.config_.keySystemsMapping);
    }

    /** @type {!Map<string, MediaKeySystemConfiguration>} */
    let configsByKeySystem;

    /**
     * Expand robustness into multiple drm infos if multiple video robustness
     * levels were provided.
     *
     * robustness can be either a single item as a string or multiple items as
     * an array of strings.
     *
     * @param {!Array<shaka.extern.DrmInfo>} drmInfos
     * @param {string} robustnessType
     * @return {!Array<shaka.extern.DrmInfo>}
     */
    const expandRobustness = (drmInfos, robustnessType) => {
      const newDrmInfos = [];
      for (const drmInfo of drmInfos) {
        let items = drmInfo[robustnessType] ||
            (this.config_.advanced &&
            this.config_.advanced[drmInfo.keySystem] &&
            this.config_.advanced[drmInfo.keySystem][robustnessType]) || '';
        if (items == '' &&
            shaka.drm.DrmUtils.isWidevineKeySystem(drmInfo.keySystem)) {
          if (robustnessType == 'audioRobustness') {
            items = [this.config_.defaultAudioRobustnessForWidevine];
          } else if (robustnessType == 'videoRobustness') {
            items = [this.config_.defaultVideoRobustnessForWidevine];
          }
        }
        if (typeof items === 'string') {
          // if drmInfo's robustness has already been expanded,
          // use the drmInfo directly.
          newDrmInfos.push(drmInfo);
        } else if (Array.isArray(items)) {
          if (items.length === 0) {
            items = [''];
          }
          for (const item of items) {
            newDrmInfos.push(
                Object.assign({}, drmInfo, {[robustnessType]: item}),
            );
          }
        }
      }
      return newDrmInfos;
    };

    for (const variant of variants) {
      if (variant.video) {
        variant.video.drmInfos =
            expandRobustness(variant.video.drmInfos,
                'videoRobustness');
        variant.video.drmInfos =
            expandRobustness(variant.video.drmInfos,
                'audioRobustness');
      }
      if (variant.audio) {
        variant.audio.drmInfos =
            expandRobustness(variant.audio.drmInfos,
                'videoRobustness');
        variant.audio.drmInfos =
            expandRobustness(variant.audio.drmInfos,
                'audioRobustness');
      }
    }

    // We should get the decodingInfo results for the variants after we filling
    // in the drm infos, and before queryMediaKeys_().
    await shaka.util.StreamUtils.getDecodingInfosForVariants(variants,
        this.usePersistentLicenses_, this.srcEquals_,
        this.config_.preferredKeySystems);
    this.destroyer_.ensureNotDestroyed();

    const hasDrmInfo = hadDrmInfo || Object.keys(this.config_.servers).length;
    // An unencrypted content is initialized.
    if (!hasDrmInfo) {
      this.initialized_ = true;
      return Promise.resolve();
    }

    const p = this.queryMediaKeys_(configsByKeySystem, variants);

    // TODO(vaage): Look into the assertion below. If we do not have any drm
    // info, we create drm info so that content can play if it has drm info
    // later.
    // However it is okay if we fail to initialize? If we fail to initialize,
    // it means we won't be able to play the later-encrypted content, which is
    // not okay.

    // If the content did not originally have any drm info, then it doesn't
    // matter if we fail to initialize the drm engine, because we won't need it
    // anyway.
    return hadDrmInfo ? p : p.catch(() => {});
  }

  /**
   * Attach MediaKeys to the video element
   * @return {Promise}
   * @private
   */
  async attachMediaKeys_() {
    if (this.video_.mediaKeys) {
      return;
    }

    // An attach process has already started, let's wait it out
    if (this.mediaKeysAttached_) {
      await this.mediaKeysAttached_;

      this.destroyer_.ensureNotDestroyed();
      return;
    }

    try {
      this.mediaKeysAttached_ = this.video_.setMediaKeys(this.mediaKeys_);

      await this.mediaKeysAttached_;
    } catch (exception) {
      goog.asserts.assert(exception instanceof Error, 'Wrong error type!');

      this.onError_(new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_ATTACH_TO_VIDEO,
          exception.message));
    }

    this.destroyer_.ensureNotDestroyed();
  }

  /**
   * Processes encrypted event and start licence challenging
   * @return {!Promise}
   * @private
   */
  async onEncryptedEvent_(event) {
    /**
     * MediaKeys should be added when receiving an encrypted event. Setting
     * mediaKeys before could result into encrypted event not being fired on
     * some browsers
     */
    await this.attachMediaKeys_();

    this.newInitData(
        event.initDataType,
        shaka.util.BufferUtils.toUint8(event.initData));
  }

  /**
   * Start processing events.
   * @param {HTMLMediaElement} video
   * @return {!Promise}
   */
  async attach(video) {
    if (this.video_ === video) {
      return;
    }
    if (!this.mediaKeys_) {
      // Unencrypted, or so we think.  We listen for encrypted events in order
      // to warn when the stream is encrypted, even though the manifest does
      // not know it.
      // Don't complain about this twice, so just listenOnce().
      // FIXME: This is ineffective when a prefixed event is translated by our
      // polyfills, since those events are only caught and translated by a
      // MediaKeys instance.  With clear content and no polyfilled MediaKeys
      // instance attached, you'll never see the 'encrypted' event on those
      // platforms (Safari).
      this.eventManager_.listenOnce(video, 'encrypted', (event) => {
        this.onError_(new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.ENCRYPTED_CONTENT_WITHOUT_DRM_INFO));
      });
      return;
    }

    this.video_ = video;

    this.eventManager_.listenOnce(this.video_, 'play', () => this.onPlay_());
    if (this.video_.remote) {
      this.eventManager_.listen(this.video_.remote, 'connect',
          () => this.closeOpenSessions_());
      this.eventManager_.listen(this.video_.remote, 'connecting',
          () => this.closeOpenSessions_());
      this.eventManager_.listen(this.video_.remote, 'disconnect',
          () => this.closeOpenSessions_());
    } else if ('webkitCurrentPlaybackTargetIsWireless' in this.video_) {
      this.eventManager_.listen(this.video_,
          'webkitcurrentplaybacktargetiswirelesschanged',
          () => this.closeOpenSessions_());
    }

    this.manifestInitData_ = this.currentDrmInfo_ ?
      (this.currentDrmInfo_.initData.find(
          (initDataOverride) => initDataOverride.initData.length > 0,
      ) || null) : null;

    /**
     * We can attach media keys before the playback actually begins when:
     *  - If we are not using FairPlay Modern EME
     *  - Some initData already has been generated (through the manifest)
     *  - In case of an offline session
     */
    if (this.manifestInitData_ ||
        this.currentDrmInfo_.keySystem !== 'com.apple.fps' ||
        this.storedPersistentSessions_.size) {
      await this.attachMediaKeys_();
    }

    this.createOrLoad().catch(() => {
      // Silence errors
      // createOrLoad will run async, errors are triggered through onError_
    });

    // Explicit init data for any one stream or an offline session is
    // sufficient to suppress 'encrypted' events for all streams.
    // Also suppress 'encrypted' events when parsing in-band pssh
    // from media segments because that serves the same purpose as the
    // 'encrypted' events.
    if (!this.manifestInitData_ && !this.storedPersistentSessions_.size &&
        !this.config_.parseInbandPsshEnabled) {
      this.eventManager_.listen(
          this.video_, 'encrypted', (e) => this.onEncryptedEvent_(e));
    }
  }

  /**
   * Returns true if the manifest has init data.
   *
   * @return {boolean}
   */
  hasManifestInitData() {
    return !!this.manifestInitData_;
  }

  /**
   * Sets the server certificate based on the current DrmInfo.
   *
   * @return {!Promise}
   */
  async setServerCertificate() {
    goog.asserts.assert(this.initialized_,
        'Must call init() before setServerCertificate');

    if (!this.mediaKeys_ || !this.currentDrmInfo_) {
      return;
    }

    if (this.currentDrmInfo_.serverCertificateUri &&
       (!this.currentDrmInfo_.serverCertificate ||
       !this.currentDrmInfo_.serverCertificate.length)) {
      const request = shaka.net.NetworkingEngine.makeRequest(
          [this.currentDrmInfo_.serverCertificateUri],
          this.config_.retryParameters);

      try {
        const operation = this.playerInterface_.netEngine.request(
            shaka.net.NetworkingEngine.RequestType.SERVER_CERTIFICATE,
            request, {isPreload: this.isPreload_()});
        const response = await operation.promise;

        this.currentDrmInfo_.serverCertificate =
          shaka.util.BufferUtils.toUint8(response.data);
      } catch (error) {
        // Request failed!
        goog.asserts.assert(error instanceof shaka.util.Error,
            'Wrong NetworkingEngine error type!');

        throw new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.SERVER_CERTIFICATE_REQUEST_FAILED,
            error);
      }

      if (this.destroyer_.destroyed()) {
        return;
      }
    }

    if (!this.currentDrmInfo_.serverCertificate ||
        !this.currentDrmInfo_.serverCertificate.length) {
      return;
    }

    try {
      const supported = await this.mediaKeys_.setServerCertificate(
          this.currentDrmInfo_.serverCertificate);

      if (!supported) {
        shaka.log.warning('Server certificates are not supported by the ' +
                          'key system.  The server certificate has been ' +
                          'ignored.');
      }
    } catch (exception) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.INVALID_SERVER_CERTIFICATE,
          exception.message);
    }
  }

  /**
   * Remove an offline session and delete it's data. This can only be called
   * after a successful call to |init|. This will wait until the
   * 'license-release' message is handled. The returned Promise will be rejected
   * if there is an error releasing the license.
   *
   * @param {string} sessionId
   * @return {!Promise}
   */
  async removeSession(sessionId) {
    goog.asserts.assert(this.mediaKeys_,
        'Must call init() before removeSession');

    const session = await this.loadOfflineSession_(
        sessionId, {initData: null, initDataType: null});

    // This will be null on error, such as session not found.
    if (!session) {
      shaka.log.v2('Ignoring attempt to remove missing session', sessionId);
      return;
    }

    // TODO: Consider adding a timeout to get the 'message' event.
    // Note that the 'message' event will get raised after the remove()
    // promise resolves.
    const tasks = [];

    const found = this.activeSessions_.get(session);
    if (found) {
      // This will force us to wait until the 'license-release' message has been
      // handled.
      found.updatePromise = new shaka.util.PublicPromise();
      tasks.push(found.updatePromise);
    }

    shaka.log.v2('Attempting to remove session', sessionId);
    tasks.push(session.remove());

    await Promise.all(tasks);
    this.activeSessions_.delete(session);
  }

  /**
   * Creates the sessions for the init data and waits for them to become ready.
   *
   * @return {!Promise}
   */
  async createOrLoad() {
    if (this.storedPersistentSessions_.size) {
      this.storedPersistentSessions_.forEach((metadata, sessionId) => {
        this.loadOfflineSession_(sessionId, metadata);
      });

      await this.allSessionsLoaded_;

      const keyIds = (this.currentDrmInfo_ && this.currentDrmInfo_.keyIds) ||
          new Set([]);

      // All the needed keys are already loaded, we don't need another license
      // Therefore we prevent starting a new session
      if (keyIds.size > 0 && this.areAllKeysUsable_()) {
        return this.allSessionsLoaded_;
      }

      // Reset the promise for the next sessions to come if key needs aren't
      // satisfied with persistent sessions
      this.hasInitData_ = false;
      this.allSessionsLoaded_ = new shaka.util.PublicPromise();
      this.allSessionsLoaded_.catch(() => {});
    }

    // Create sessions.
    const initDatas =
        (this.currentDrmInfo_ ? this.currentDrmInfo_.initData : []) || [];
    for (const initDataOverride of initDatas) {
      this.newInitData(
          initDataOverride.initDataType, initDataOverride.initData);
    }

    // If there were no sessions to load, we need to resolve the promise right
    // now or else it will never get resolved.
    // We determine this by checking areAllSessionsLoaded_, rather than checking
    // the number of initDatas, since the newInitData method can reject init
    // datas in some circumstances.
    if (this.areAllSessionsLoaded_()) {
      this.allSessionsLoaded_.resolve();
    }

    return this.allSessionsLoaded_;
  }

  /**
   * Called when new initialization data is encountered.  If this data hasn't
   * been seen yet, this will create a new session for it.
   *
   * @param {string} initDataType
   * @param {!Uint8Array} initData
   */
  newInitData(initDataType, initData) {
    if (!initData.length) {
      return;
    }

    // Suppress duplicate init data.
    // Note that some init data are extremely large and can't portably be used
    // as keys in a dictionary.

    if (this.config_.ignoreDuplicateInitData) {
      const metadatas = this.activeSessions_.values();
      for (const metadata of metadatas) {
        if (shaka.util.BufferUtils.equal(initData, metadata.initData)) {
          shaka.log.debug('Ignoring duplicate init data.');
          return;
        }
      }
      let duplicate = false;
      this.storedPersistentSessions_.forEach((metadata, sessionId) => {
        if (!duplicate &&
            shaka.util.BufferUtils.equal(initData, metadata.initData)) {
          duplicate = true;
        }
      });
      if (duplicate) {
        shaka.log.debug('Ignoring duplicate init data.');
        return;
      }
    }

    // Mark that there is init data, so that the preloader will know to wait
    // for sessions to be loaded.
    this.hasInitData_ = true;

    // If there are pre-existing sessions that have all been loaded
    // then reset the allSessionsLoaded_ promise, which can now be
    // used to wait for new sessions to be loaded
    if (this.activeSessions_.size > 0 && this.areAllSessionsLoaded_()) {
      this.allSessionsLoaded_.resolve();
      this.hasInitData_ = false;
      this.allSessionsLoaded_ = new shaka.util.PublicPromise();
      this.allSessionsLoaded_.catch(() => {});
    }
    this.createSession(initDataType, initData,
        this.currentDrmInfo_.sessionType);
  }

  /** @return {boolean} */
  initialized() {
    return this.initialized_;
  }

  /**
   * Returns the ID of the sessions currently active.
   *
   * @return {!Array<string>}
   */
  getSessionIds() {
    const sessions = this.activeSessions_.keys();
    const ids = shaka.util.Iterables.map(sessions, (s) => s.sessionId);

    // TODO: Make |getSessionIds| return |Iterable| instead of |Array|.
    return Array.from(ids);
  }

  /**
   * Returns the active sessions metadata
   *
   * @return {!Array<shaka.extern.DrmSessionMetadata>}
   */
  getActiveSessionsMetadata() {
    const sessions = this.activeSessions_.keys();

    const metadata = shaka.util.Iterables.map(sessions, (session) => {
      const metadata = this.activeSessions_.get(session);

      return {
        sessionId: session.sessionId,
        sessionType: metadata.type,
        initData: metadata.initData,
        initDataType: metadata.initDataType,
      };
    });

    return Array.from(metadata);
  }

  /**
   * Returns the next expiration time, or Infinity.
   * @return {number}
   */
  getExpiration() {
    // This will equal Infinity if there are no entries.
    let min = Infinity;

    const sessions = this.activeSessions_.keys();
    for (const session of sessions) {
      if (!isNaN(session.expiration)) {
        min = Math.min(min, session.expiration);
      }
    }

    return min;
  }

  /**
   * Returns the time spent on license requests during this session, or NaN.
   *
   * @return {number}
   */
  getLicenseTime() {
    if (this.licenseTimeSeconds_) {
      return this.licenseTimeSeconds_;
    }
    return NaN;
  }

  /**
   * Returns the DrmInfo that was used to initialize the current key system.
   *
   * @return {?shaka.extern.DrmInfo}
   */
  getDrmInfo() {
    return this.currentDrmInfo_;
  }

  /**
   * Return the media keys created from the current mediaKeySystemAccess.
   * @return {MediaKeys}
   */
  getMediaKeys() {
    return this.mediaKeys_;
  }

  /**
   * Returns the current key statuses.
   *
   * @return {!Object<string, string>}
   */
  getKeyStatuses() {
    return shaka.util.MapUtils.asObject(this.announcedKeyStatusByKeyId_);
  }

  /**
   * Returns the current media key sessions.
   *
   * @return {!Array<MediaKeySession>}
   */
  getMediaKeySessions() {
    return Array.from(this.activeSessions_.keys());
  }

  /**
   * @param {!Map<string, MediaKeySystemConfiguration>} configsByKeySystem
   *   A dictionary of configs, indexed by key system, with an iteration order
   *   (insertion order) that reflects the preference for the application.
   * @param {!Array<shaka.extern.Variant>} variants
   * @return {!Promise} Resolved if/when a key system has been chosen.
   * @private
   */
  async queryMediaKeys_(configsByKeySystem, variants) {
    const drmInfosByKeySystem = new Map();

    const mediaKeySystemAccess = variants.length ?
        this.getKeySystemAccessFromVariants_(variants, drmInfosByKeySystem) :
        await this.getKeySystemAccessByConfigs_(configsByKeySystem);

    if (!mediaKeySystemAccess) {
      if (!navigator.requestMediaKeySystemAccess) {
        throw new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.MISSING_EME_SUPPORT);
      }
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.REQUESTED_KEY_SYSTEM_CONFIG_UNAVAILABLE);
    }
    this.destroyer_.ensureNotDestroyed();

    try {
      // Store the capabilities of the key system.
      const realConfig = mediaKeySystemAccess.getConfiguration();

      shaka.log.v2(
          'Got MediaKeySystemAccess with configuration',
          realConfig);

      const keySystem =
          this.config_.keySystemsMapping[mediaKeySystemAccess.keySystem] ||
          mediaKeySystemAccess.keySystem;

      if (variants.length) {
        this.currentDrmInfo_ = this.createDrmInfoByInfos_(
            keySystem, drmInfosByKeySystem.get(keySystem));
      } else {
        this.currentDrmInfo_ = shaka.drm.DrmEngine.createDrmInfoByConfigs_(
            keySystem, configsByKeySystem.get(keySystem));
      }
      if (!this.currentDrmInfo_.licenseServerUri) {
        throw new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.NO_LICENSE_SERVER_GIVEN,
            this.currentDrmInfo_.keySystem);
      }

      const mediaKeys = await mediaKeySystemAccess.createMediaKeys();
      this.destroyer_.ensureNotDestroyed();
      shaka.log.info('Created MediaKeys object for key system',
          this.currentDrmInfo_.keySystem);

      this.mediaKeys_ = mediaKeys;
      if (this.config_.minHdcpVersion != '' &&
          'getStatusForPolicy' in this.mediaKeys_) {
        try {
          const status = await this.mediaKeys_.getStatusForPolicy({
            minHdcpVersion: this.config_.minHdcpVersion,
          });
          if (status != 'usable') {
            throw new shaka.util.Error(
                shaka.util.Error.Severity.CRITICAL,
                shaka.util.Error.Category.DRM,
                shaka.util.Error.Code.MIN_HDCP_VERSION_NOT_MATCH);
          }
          this.destroyer_.ensureNotDestroyed();
        } catch (e) {
          if (e instanceof shaka.util.Error) {
            throw e;
          }
          throw new shaka.util.Error(
              shaka.util.Error.Severity.CRITICAL,
              shaka.util.Error.Category.DRM,
              shaka.util.Error.Code.ERROR_CHECKING_HDCP_VERSION,
              e.message);
        }
      }
      this.initialized_ = true;

      await this.setServerCertificate();
      this.destroyer_.ensureNotDestroyed();
    } catch (exception) {
      this.destroyer_.ensureNotDestroyed(exception);

      // Don't rewrap a shaka.util.Error from earlier in the chain:
      this.currentDrmInfo_ = null;
      if (exception instanceof shaka.util.Error) {
        throw exception;
      }

      // We failed to create MediaKeys.  This generally shouldn't happen.
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_CREATE_CDM,
          exception.message);
    }
  }

  /**
   * Get the MediaKeySystemAccess from the decodingInfos of the variants.
   * @param {!Array<shaka.extern.Variant>} variants
   * @param {!Map<string, !Array<shaka.extern.DrmInfo>>} drmInfosByKeySystem
   *   A dictionary of drmInfos, indexed by key system.
   * @return {MediaKeySystemAccess}
   * @private
   */
  getKeySystemAccessFromVariants_(variants, drmInfosByKeySystem) {
    for (const variant of variants) {
      // Get all the key systems in the variant that shouldHaveLicenseServer.
      const drmInfos = this.getVariantDrmInfos_(variant);
      for (const info of drmInfos) {
        if (!drmInfosByKeySystem.has(info.keySystem)) {
          drmInfosByKeySystem.set(info.keySystem, []);
        }
        drmInfosByKeySystem.get(info.keySystem).push(info);
      }
    }

    if (drmInfosByKeySystem.size == 1 && drmInfosByKeySystem.has('')) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.NO_RECOGNIZED_KEY_SYSTEMS);
    }

    // If we have configured preferredKeySystems, choose a preferred keySystem
    // if available.
    let preferredKeySystems = this.config_.preferredKeySystems;
    if (!preferredKeySystems.length) {
      // If there is no preference set and we only have one license server, we
      // use this as preference. This is used to override manifests on those
      // that have the embedded license and the browser supports multiple DRMs.
      const servers = shaka.util.MapUtils.asMap(this.config_.servers);
      if (servers.size == 1) {
        preferredKeySystems = Array.from(servers.keys());
      }
    }
    for (const preferredKeySystem of preferredKeySystems) {
      for (const variant of variants) {
        const decodingInfo = variant.decodingInfos.find((decodingInfo) => {
          return decodingInfo.supported &&
              decodingInfo.keySystemAccess != null &&
              decodingInfo.keySystemAccess.keySystem == preferredKeySystem;
        });
        if (decodingInfo) {
          return decodingInfo.keySystemAccess;
        }
      }
    }

    // Try key systems with configured license servers first.  We only have to
    // try key systems without configured license servers for diagnostic
    // reasons, so that we can differentiate between "none of these key
    // systems are available" and "some are available, but you did not
    // configure them properly."  The former takes precedence.
    for (const shouldHaveLicenseServer of [true, false]) {
      for (const variant of variants) {
        for (const decodingInfo of variant.decodingInfos) {
          if (!decodingInfo.supported || !decodingInfo.keySystemAccess) {
            continue;
          }
          const originalKeySystem = decodingInfo.keySystemAccess.keySystem;
          if (preferredKeySystems.includes(originalKeySystem)) {
            continue;
          }
          let drmInfos = drmInfosByKeySystem.get(originalKeySystem);
          if (!drmInfos && this.config_.keySystemsMapping[originalKeySystem]) {
            drmInfos = drmInfosByKeySystem.get(
                this.config_.keySystemsMapping[originalKeySystem]);
          }
          for (const info of drmInfos) {
            if (!!info.licenseServerUri == shouldHaveLicenseServer) {
              return decodingInfo.keySystemAccess;
            }
          }
        }
      }
    }
    return null;
  }

  /**
   * Get the MediaKeySystemAccess by querying requestMediaKeySystemAccess.
   * @param {!Map<string, MediaKeySystemConfiguration>} configsByKeySystem
   *   A dictionary of configs, indexed by key system, with an iteration order
   *   (insertion order) that reflects the preference for the application.
   * @return {!Promise<MediaKeySystemAccess>} Resolved if/when a
   *   mediaKeySystemAccess has been chosen.
   * @private
   */
  async getKeySystemAccessByConfigs_(configsByKeySystem) {
    /** @type {MediaKeySystemAccess} */
    let mediaKeySystemAccess;

    if (configsByKeySystem.size == 1 && configsByKeySystem.has('')) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.NO_RECOGNIZED_KEY_SYSTEMS);
    }

    // If there are no tracks of a type, these should be not present.
    // Otherwise the query will fail.
    for (const config of configsByKeySystem.values()) {
      if (config.audioCapabilities.length == 0) {
        delete config.audioCapabilities;
      }
      if (config.videoCapabilities.length == 0) {
        delete config.videoCapabilities;
      }
    }

    // If we have configured preferredKeySystems, choose the preferred one if
    // available.
    for (const keySystem of this.config_.preferredKeySystems) {
      if (configsByKeySystem.has(keySystem)) {
        const config = configsByKeySystem.get(keySystem);
        try {
          mediaKeySystemAccess =  // eslint-disable-next-line no-await-in-loop
              await navigator.requestMediaKeySystemAccess(keySystem, [config]);
          return mediaKeySystemAccess;
        } catch (error) {
          // Suppress errors.
          shaka.log.v2(
              'Requesting', keySystem, 'failed with config', config, error);
        }
        this.destroyer_.ensureNotDestroyed();
      }
    }

    // Try key systems with configured license servers first.  We only have to
    // try key systems without configured license servers for diagnostic
    // reasons, so that we can differentiate between "none of these key
    // systems are available" and "some are available, but you did not
    // configure them properly."  The former takes precedence.
    // TODO: once MediaCap implementation is complete, this part can be
    // simplified or removed.
    for (const shouldHaveLicenseServer of [true, false]) {
      for (const keySystem of configsByKeySystem.keys()) {
        const config = configsByKeySystem.get(keySystem);
        // TODO: refactor, don't stick drmInfos onto
        // MediaKeySystemConfiguration
        const hasLicenseServer = config['drmInfos'].some((info) => {
          return !!info.licenseServerUri;
        });
        if (hasLicenseServer != shouldHaveLicenseServer) {
          continue;
        }

        try {
          mediaKeySystemAccess =  // eslint-disable-next-line no-await-in-loop
              await navigator.requestMediaKeySystemAccess(keySystem, [config]);
          return mediaKeySystemAccess;
        } catch (error) {
          // Suppress errors.
          shaka.log.v2(
              'Requesting', keySystem, 'failed with config', config, error);
        }
        this.destroyer_.ensureNotDestroyed();
      }
    }
    return mediaKeySystemAccess;
  }

  /**
   * Resolves the allSessionsLoaded_ promise when all the sessions are loaded
   *
   * @private
   */
  checkSessionsLoaded_() {
    if (this.areAllSessionsLoaded_()) {
      this.allSessionsLoaded_.resolve();
    }
  }

  /**
   * In case there are no key statuses, consider this session loaded
   * after a reasonable timeout.  It should definitely not take 5
   * seconds to process a license.
   * @param {!shaka.drm.DrmEngine.SessionMetaData} metadata
   * @private
   */
  setLoadSessionTimeoutTimer_(metadata) {
    const timer = new shaka.util.Timer(() => {
      metadata.loaded = true;
      this.checkSessionsLoaded_();
    });

    timer.tickAfter(
        /* seconds= */ shaka.drm.DrmEngine.SESSION_LOAD_TIMEOUT_);
  }

  /**
   * @param {string} sessionId
   * @param {{initData: ?Uint8Array, initDataType: ?string}} sessionMetadata
   * @return {!Promise<MediaKeySession>}
   * @private
   */
  async loadOfflineSession_(sessionId, sessionMetadata) {
    let session;

    const sessionType = 'persistent-license';

    try {
      shaka.log.v1('Attempting to load an offline session', sessionId);
      session = this.mediaKeys_.createSession(sessionType);
    } catch (exception) {
      const error = new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_CREATE_SESSION,
          exception.message);
      this.onError_(error);
      return Promise.reject(error);
    }

    this.eventManager_.listen(session, 'message',
        /** @type {shaka.util.EventManager.ListenerType} */(
          (event) => this.onSessionMessage_(event)));
    this.eventManager_.listen(session, 'keystatuseschange',
        (event) => this.onKeyStatusesChange_(event));

    const metadata = {
      initData: sessionMetadata.initData,
      initDataType: sessionMetadata.initDataType,
      loaded: false,
      oldExpiration: Infinity,
      updatePromise: null,
      type: sessionType,
    };
    this.activeSessions_.set(session, metadata);

    try {
      const present = await session.load(sessionId);
      this.destroyer_.ensureNotDestroyed();
      shaka.log.v2('Loaded offline session', sessionId, present);

      if (!present) {
        this.activeSessions_.delete(session);

        const severity = this.config_.persistentSessionOnlinePlayback ?
            shaka.util.Error.Severity.RECOVERABLE :
            shaka.util.Error.Severity.CRITICAL;

        this.onError_(new shaka.util.Error(
            severity,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.OFFLINE_SESSION_REMOVED));

        metadata.loaded = true;
      }

      this.setLoadSessionTimeoutTimer_(metadata);
      this.checkSessionsLoaded_();

      return session;
    } catch (error) {
      this.destroyer_.ensureNotDestroyed(error);

      this.activeSessions_.delete(session);

      const severity = this.config_.persistentSessionOnlinePlayback ?
          shaka.util.Error.Severity.RECOVERABLE :
          shaka.util.Error.Severity.CRITICAL;

      this.onError_(new shaka.util.Error(
          severity,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_CREATE_SESSION,
          error.message));

      metadata.loaded = true;

      this.checkSessionsLoaded_();
    }

    return Promise.resolve();
  }

  /**
   * @param {string} initDataType
   * @param {!Uint8Array} initData
   * @param {string} sessionType
   */
  createSession(initDataType, initData, sessionType) {
    goog.asserts.assert(this.mediaKeys_,
        'mediaKeys_ should be valid when creating temporary session.');

    let session;

    try {
      shaka.log.info('Creating new', sessionType, 'session');

      session = this.mediaKeys_.createSession(sessionType);
    } catch (exception) {
      this.onError_(new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_CREATE_SESSION,
          exception.message));
      return;
    }

    this.eventManager_.listen(session, 'message',
    /** @type {shaka.util.EventManager.ListenerType} */(
          (event) => this.onSessionMessage_(event)));
    this.eventManager_.listen(session, 'keystatuseschange',
        (event) => this.onKeyStatusesChange_(event));

    const metadata = {
      initData: initData,
      initDataType: initDataType,
      loaded: false,
      oldExpiration: Infinity,
      updatePromise: null,
      type: sessionType,
    };
    this.activeSessions_.set(session, metadata);

    try {
      initData = this.config_.initDataTransform(
          initData, initDataType, this.currentDrmInfo_);
    } catch (error) {
      let shakaError = error;
      if (!(error instanceof shaka.util.Error)) {
        shakaError = new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL,
            shaka.util.Error.Category.DRM,
            shaka.util.Error.Code.INIT_DATA_TRANSFORM_ERROR,
            error);
      }
      this.onError_(shakaError);
      return;
    }

    if (this.config_.logLicenseExchange) {
      const str = shaka.util.Uint8ArrayUtils.toBase64(initData);
      shaka.log.info('EME init data: type=', initDataType, 'data=', str);
    }

    session.generateRequest(initDataType, initData).catch((error) => {
      if (this.destroyer_.destroyed()) {
        return;
      }
      goog.asserts.assert(error instanceof Error, 'Wrong error type!');

      this.activeSessions_.delete(session);

      // This may be supplied by some polyfills.
      /** @type {MediaKeyError} */
      const errorCode = error['errorCode'];

      let extended;
      if (errorCode && errorCode.systemCode) {
        extended = errorCode.systemCode;
        if (extended < 0) {
          extended += Math.pow(2, 32);
        }
        extended = '0x' + extended.toString(16);
      }

      this.onError_(new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.DRM,
          shaka.util.Error.Code.FAILED_TO_GENERATE_LICENSE_REQUEST,
          error.message, error, extended));
    });
  }

  /**
   * @param {!MediaKeyMessageEvent} event
   * @private
   */
  onSessionMessage_(event) {
    if (this.delayLicenseRequest_()) {
      this.mediaKeyMessageEvents_.push(event);
    } else {
      this.sendLicenseRequest_(event);
    }
  }

  /**
   * @return {boolean}
   * @private
   */
  delayLicenseRequest_() {
    if (!this.video_) {
      // If there's no video, don't delay the license request; i.e., in the case
      // of offline storage.
      return false;
    }
    return (this.config_.delayLicenseRequestUntilPlayed &&
            this.video_.paused && !this.initialRequestsSent_);
  }

  /** @return {!Promise} */
  async waitForActiveRequests() {
    if (this.hasInitData_) {
      await this.allSessionsLoaded_;
      await Promise.all(this.activeRequests_.map((req) => req.promise));
    }
  }

  /**
   * Sends a license request.
   * @param {!MediaKeyMessageEvent} event
   * @private
   */
  async sendLicenseRequest_(event) {
    /** @type {!MediaKeySession} */
    const session = event.target;
    shaka.log.v1(
        'Sending license request for session', session.sessionId, 'of type',
        event.messageType);
    if (this.config_.logLicenseExchange) {
      const str = shaka.util.Uint8ArrayUtils.toBase64(event.message);
      shaka.log.info('EME license request', str);
    }

    const metadata = this.activeSessions_.get(session);

    let url = this.currentDrmInfo_.licenseServerUri;
    const advancedConfig =
        this.config_.advanced[this.currentDrmInfo_.keySystem];

    if (event.messageType == 'individualization-request' && advancedConfig &&
        advancedConfig.individualizationServer) {
      url = advancedConfig.individualizationServer;
    }

    const requestType = shaka.net.NetworkingEngine.RequestType.LICENSE;
    const request = shaka.net.NetworkingEngine.makeRequest(
        [url], this.config_.retryParameters);
    request.body = event.message;
    request.method = 'POST';
    request.licenseRequestType = event.messageType;
    request.sessionId = session.sessionId;
    request.drmInfo = this.currentDrmInfo_;
    if (metadata) {
      request.initData = metadata.initData;
      request.initDataType = metadata.initDataType;
    }
    if (advancedConfig && advancedConfig.headers) {
      // Add these to the existing headers.  Do not clobber them!
      // For PlayReady, there will already be headers in the request.
      for (const header in advancedConfig.headers) {
        request.headers[header] = advancedConfig.headers[header];
      }
    }
    // NOTE: allowCrossSiteCredentials can be set in a request filter.

    if (shaka.drm.DrmUtils.isClearKeySystem(
        this.currentDrmInfo_.key