shaka-player/lib/net/http_fetch_plugin.js

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

goog.provide('shaka.net.HttpFetchPlugin');

goog.require('goog.asserts');
goog.require('shaka.net.HttpPluginUtils');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.util.AbortableOperation');
goog.require('shaka.util.Error');
goog.require('shaka.util.MapUtils');
goog.require('shaka.util.Timer');


/**
 * @namespace
 * @summary A networking plugin to handle http and https URIs via the Fetch API.
 * @param {string} uri
 * @param {shaka.extern.Request} request
 * @param {shaka.net.NetworkingEngine.RequestType} requestType
 * @param {shaka.extern.ProgressUpdated=} progressUpdated Called when a progress
 *        event happened.
 * @return {!shaka.extern.IAbortableOperation.<shaka.extern.Response>}
 * @export
 */
shaka.net.HttpFetchPlugin = function(
    uri, request, requestType, progressUpdated) {
  const headers = new shaka.net.HttpFetchPlugin.Headers_();
  shaka.util.MapUtils.asMap(request.headers).forEach((value, key) => {
    headers.append(key, value);
  });

  const controller = new shaka.net.HttpFetchPlugin.AbortController_();

  /** @type {!RequestInit} */
  const init = {
    // Edge does not treat null as undefined for body; https://bit.ly/2luyE6x
    body: request.body || undefined,
    headers: headers,
    method: request.method,
    signal: controller.signal,
    credentials: request.allowCrossSiteCredentials ? 'include' : undefined,
  };

  /** @type {shaka.net.HttpFetchPlugin.AbortStatus} */
  const abortStatus = {
    canceled: false,
    timedOut: false,
  };

  const pendingRequest = shaka.net.HttpFetchPlugin.request_(
      uri, requestType, init, abortStatus, progressUpdated);

  /** @type {!shaka.util.AbortableOperation} */
  const op = new shaka.util.AbortableOperation(pendingRequest, () => {
    abortStatus.canceled = true;
    controller.abort();
    return Promise.resolve();
  });

  // The fetch API does not timeout natively, so do a timeout manually using the
  // AbortController.
  const timeoutMs = request.retryParameters.timeout;
  if (timeoutMs) {
    const timer = new shaka.util.Timer(() => {
      abortStatus.timedOut = true;
      controller.abort();
    });

    timer.tickAfter(timeoutMs / 1000);

    // To avoid calling |abort| on the network request after it finished, we
    // will stop the timer when the requests resolves/rejects.
    op.finally(() => {
      timer.stop();
    });
  }

  return op;
};

/**
 * @param {string} uri
 * @param {shaka.net.NetworkingEngine.RequestType} requestType
 * @param {!RequestInit} init
 * @param {shaka.net.HttpFetchPlugin.AbortStatus} abortStatus
 * @param {shaka.extern.ProgressUpdated=} progressUpdated
 * @return {!Promise<!shaka.extern.Response>}
 * @private
 */
shaka.net.HttpFetchPlugin.request_ = async function(
    uri, requestType, init, abortStatus, progressUpdated) {
  const fetch = shaka.net.HttpFetchPlugin.fetch_;
  const ReadableStream = shaka.net.HttpFetchPlugin.ReadableStream_;
  let response;
  let arrayBuffer;
  let loaded = 0;
  let lastLoaded = 0;

  // Last time stamp when we got a progress event.
  let lastTime = Date.now();

  try {
    // The promise returned by fetch resolves as soon as the HTTP response
    // headers are available. The download itself isn't done until the promise
    // for retrieving the data (arrayBuffer, blob, etc) has resolved.
    response = await fetch(uri, init);
    // Getting the reader in this way allows us to observe the process of
    // downloading the body, instead of just waiting for an opaque promise to
    // resolve.
    // We first clone the response because calling getReader locks the body
    // stream; if we didn't clone it here, we would be unable to get the
    // response's arrayBuffer later.
    const reader = response.clone().body.getReader();

    const contentLengthRaw = response.headers.get('Content-Length');
    const contentLength = contentLengthRaw ? parseInt(contentLengthRaw, 10) : 0;

    let start = (controller) => {
      let push = async () => {
        const readObj = await reader.read();

        if (!readObj.done) {
          loaded += readObj.value.byteLength;
        }

        let currentTime = Date.now();
        // If the time between last time and this time we got progress event
        // is long enough, or if a whole segment is downloaded, call
        // progressUpdated().
        if (currentTime - lastTime > 100 || readObj.done) {
          progressUpdated(currentTime - lastTime, loaded - lastLoaded,
              contentLength - loaded);
          lastLoaded = loaded;
          lastTime = currentTime;
        }

        if (readObj.done) {
          goog.asserts.assert(!readObj.value,
                              'readObj should be unset when "done" is true.');
          controller.close();
        } else {
          controller.enqueue(readObj.value);
          push();
        }
      };
      push();
    };
    // Create a ReadableStream to use the reader. We don't need to use the
    // actual stream for anything, though, as we are using the response's
    // arrayBuffer method to get the body, so we don't store the ReadableStream.
    new ReadableStream({start}); // eslint-disable-line no-new
    arrayBuffer = await response.arrayBuffer();
  } catch (error) {
    if (abortStatus.canceled) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.NETWORK,
          shaka.util.Error.Code.OPERATION_ABORTED,
          uri, requestType);
    } else if (abortStatus.timedOut) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.NETWORK,
          shaka.util.Error.Code.TIMEOUT,
          uri, requestType);
    } else {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.RECOVERABLE,
          shaka.util.Error.Category.NETWORK,
          shaka.util.Error.Code.HTTP_ERROR,
          uri, error, requestType);
    }
  }

  const headers = {};
  /** @type {Headers} */
  const responseHeaders = response.headers;
  responseHeaders.forEach(function(value, key) {
    // Since IE/Edge incorrectly return the header with a leading new line
    // character ('\n'), we trim the header here.
    headers[key.trim()] = value;
  });

  return shaka.net.HttpPluginUtils.makeResponse(headers,
      arrayBuffer, response.status, uri, response.url, requestType);
};

/**
 * @typedef {{
 *   canceled: boolean,
 *   timedOut: boolean
 * }}
 * @property {boolean} canceled
 *   Indicates if the request was canceled.
 * @property {boolean} timedOut
 *   Indicates if the request timed out.
 */
shaka.net.HttpFetchPlugin.AbortStatus;


/**
 * Determine if the Fetch API is supported in the browser. Note: this is
 * deliberately exposed as a method to allow the client app to use the same
 * logic as Shaka when determining support.
 * @return {boolean}
 * @export
 */
shaka.net.HttpFetchPlugin.isSupported = function() {
  // On Edge, ReadableStream exists, but attempting to construct it results in
  // an error. See https://bit.ly/2zwaFLL
  // So this has to check that ReadableStream is present AND usable.
  if (window.ReadableStream) {
    try {
      new ReadableStream({}); // eslint-disable-line no-new
    } catch (e) {
      return false;
    }
  } else {
    return false;
  }
  return !!(window.fetch && window.AbortController);
};


/**
 * Overridden in unit tests, but compiled out in production.
 *
 * @const {function(string, !RequestInit)}
 * @private
 */
shaka.net.HttpFetchPlugin.fetch_ = window.fetch;


/**
 * Overridden in unit tests, but compiled out in production.
 *
 * @const {function(new: AbortController)}
 * @private
 */
shaka.net.HttpFetchPlugin.AbortController_ = window.AbortController;


/**
 * Overridden in unit tests, but compiled out in production.
 *
 * @const {function(new: ReadableStream, !Object)}
 * @private
 */
shaka.net.HttpFetchPlugin.ReadableStream_ = window.ReadableStream;


/**
 * Overridden in unit tests, but compiled out in production.
 *
 * @const {function(new: Headers)}
 * @private
 */
shaka.net.HttpFetchPlugin.Headers_ = window.Headers;


if (shaka.net.HttpFetchPlugin.isSupported()) {
  shaka.net.NetworkingEngine.registerScheme('http', shaka.net.HttpFetchPlugin,
      shaka.net.NetworkingEngine.PluginPriority.PREFERRED);
  shaka.net.NetworkingEngine.registerScheme('https', shaka.net.HttpFetchPlugin,
      shaka.net.NetworkingEngine.PluginPriority.PREFERRED);
}