browser/extensions/pdfjs/content/PdfStreamConverter.jsm
author pospeselr <richard@torproject.org>
Mon, 13 May 2019 23:41:57 +0000
changeset 532511 b1c78bd9fdc280ce52f84e105321a79a89e2177a
parent 526915 7788a7ab31bbd0479d40d6d3f073d2a00f01e366
permissions -rw-r--r--
Bug 1506693: PDFJS range-based requests violate FPI r=bdahl Large pdf files download in parts via range-based requests so that users can begin reading before the entire file has finished downloading. This is implemented using XMLHttpRequests. However, since these requests are created in the chrome, they are given the System Principal and lack the correct firstPartyDomain associated with the parent window. This patch manually sets the XMLHttpRequest's originAttributes to the one provided by the real owning window cached in the RangedChromeActions object. This is done via the chrome-only setOriginAttributes method. The method is called in the xhr_onreadystatechanged() callback rather than directly after construction in getXhr() because the setOriginAttributes implementation requires the internal nsIChannel object to have been created but not used. Fortunately, the XMLHttpRequest object fires the readStateChangedEvent precisely after the channel has been created in the XmlHttpRequest's Open() method. The nsIChannel's nsILoadInfo's OriginAttributes are now overwritten with the known OriginAttributes of the parent window before anything else has had a chance to use it. Differential Revision: https://phabricator.services.mozilla.com/D30689

/* Copyright 2012 Mozilla Foundation
 *
 * 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.
 */

"use strict";

var EXPORTED_SYMBOLS = ["PdfStreamConverter"];

const PDFJS_EVENT_ID = "pdf.js.message";
const PREF_PREFIX = "pdfjs";
const PDF_VIEWER_ORIGIN = "resource://pdf.js";
const PDF_VIEWER_WEB_PAGE = "resource://pdf.js/web/viewer.html";
const MAX_NUMBER_OF_PREFS = 50;
const MAX_STRING_PREF_LENGTH = 128;

const {XPCOMUtils} = ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");

ChromeUtils.defineModuleGetter(this, "NetUtil",
  "resource://gre/modules/NetUtil.jsm");

ChromeUtils.defineModuleGetter(this, "NetworkManager",
  "resource://pdf.js/PdfJsNetwork.jsm");

ChromeUtils.defineModuleGetter(this, "PrivateBrowsingUtils",
  "resource://gre/modules/PrivateBrowsingUtils.jsm");

ChromeUtils.defineModuleGetter(this, "PdfJsTelemetry",
  "resource://pdf.js/PdfJsTelemetry.jsm");

ChromeUtils.defineModuleGetter(this, "PdfjsContentUtils",
  "resource://pdf.js/PdfjsContentUtils.jsm");

XPCOMUtils.defineLazyGlobalGetters(this, ["XMLHttpRequest"]);

var Svc = {};
XPCOMUtils.defineLazyServiceGetter(Svc, "mime",
                                   "@mozilla.org/mime;1",
                                   "nsIMIMEService");

function getBoolPref(pref, def) {
  try {
    return Services.prefs.getBoolPref(pref);
  } catch (ex) {
    return def;
  }
}

function getIntPref(pref, def) {
  try {
    return Services.prefs.getIntPref(pref);
  } catch (ex) {
    return def;
  }
}

function getStringPref(pref, def) {
  try {
    return Services.prefs.getStringPref(pref);
  } catch (ex) {
    return def;
  }
}

function log(aMsg) {
  if (!getBoolPref(PREF_PREFIX + ".pdfBugEnabled", false)) {
    return;
  }
  var msg = "PdfStreamConverter.js: " + (aMsg.join ? aMsg.join("") : aMsg);
  Services.console.logStringMessage(msg);
  dump(msg + "\n");
}

function getDOMWindow(aChannel, aPrincipal) {
  var requestor = aChannel.notificationCallbacks ?
                  aChannel.notificationCallbacks :
                  aChannel.loadGroup.notificationCallbacks;
  var win = requestor.getInterface(Ci.nsIDOMWindow);
  // Ensure the window wasn't navigated to something that is not PDF.js.
  if (!win.document.nodePrincipal.equals(aPrincipal)) {
    return null;
  }
  return win;
}

function getLocalizedStrings(path) {
  var stringBundle =
    Services.strings.createBundle("chrome://pdf.js/locale/" + path);

  var map = {};
  for (let string of stringBundle.getSimpleEnumeration()) {
    var key = string.key, property = "textContent";
    var i = key.lastIndexOf(".");
    if (i >= 0) {
      property = key.substring(i + 1);
      key = key.substring(0, i);
    }
    if (!(key in map)) {
      map[key] = {};
    }
    map[key][property] = string.value;
  }
  return map;
}
function getLocalizedString(strings, id, property) {
  property = property || "textContent";
  if (id in strings) {
    return strings[id][property];
  }
  return id;
}

function isValidMatchesCount(data) {
  if (typeof data !== "object" || data === null) {
    return false;
  }
  const {current, total} = data;
  if ((typeof total !== "number" || total < 0) ||
      (typeof current !== "number" || current < 0 || current > total)) {
    return false;
  }
  return true;
}

// PDF data storage
function PdfDataListener(length) {
  this.length = length; // less than 0, if length is unknown
  this.buffers = [];
  this.loaded = 0;
}

PdfDataListener.prototype = {
  append: function PdfDataListener_append(chunk) {
    // In most of the cases we will pass data as we receive it, but at the
    // beginning of the loading we may accumulate some data.
    this.buffers.push(chunk);
    this.loaded += chunk.length;
    if (this.length >= 0 && this.length < this.loaded) {
      this.length = -1; // reset the length, server is giving incorrect one
    }
    this.onprogress(this.loaded, this.length >= 0 ? this.length : void 0);
  },
  readData: function PdfDataListener_readData() {
    if (this.buffers.length === 0) {
      return null;
    }
    if (this.buffers.length === 1) {
      return this.buffers.pop();
    }
    // There are multiple buffers that need to be combined into a single
    // buffer.
    let combinedLength = 0;
    for (let buffer of this.buffers) {
      combinedLength += buffer.length;
    }
    let combinedArray = new Uint8Array(combinedLength);
    let writeOffset = 0;
    while (this.buffers.length) {
      let buffer = this.buffers.shift();
      combinedArray.set(buffer, writeOffset);
      writeOffset += buffer.length;
    }
    return combinedArray;
  },
  get isDone() {
    return !!this.isDataReady;
  },
  finish: function PdfDataListener_finish() {
    this.isDataReady = true;
    if (this.oncompleteCallback) {
      this.oncompleteCallback(this.readData());
    }
  },
  error: function PdfDataListener_error(errorCode) {
    this.errorCode = errorCode;
    if (this.oncompleteCallback) {
      this.oncompleteCallback(null, errorCode);
    }
  },
  onprogress() {},
  get oncomplete() {
    return this.oncompleteCallback;
  },
  set oncomplete(value) {
    this.oncompleteCallback = value;
    if (this.isDataReady) {
      value(this.readData());
    }
    if (this.errorCode) {
      value(null, this.errorCode);
    }
  },
};

/**
 * All the privileged actions.
 */
class ChromeActions {
  constructor(domWindow, contentDispositionFilename) {
    this.domWindow = domWindow;
    this.contentDispositionFilename = contentDispositionFilename;
    this.telemetryState = {
      documentInfo: false,
      firstPageInfo: false,
      streamTypesUsed: [],
      fontTypesUsed: [],
      startAt: Date.now(),
    };
  }

  isInPrivateBrowsing() {
    return PrivateBrowsingUtils.isContentWindowPrivate(this.domWindow);
  }

  getWindowOriginAttributes() {
    try {
      return this.domWindow.document.nodePrincipal.originAttributes;
    } catch (err) {
      return {};
    }
  }

  download(data, sendResponse) {
    var self = this;
    var originalUrl = data.originalUrl;
    var blobUrl = data.blobUrl || originalUrl;
    // The data may not be downloaded so we need just retry getting the pdf with
    // the original url.
    var originalUri = NetUtil.newURI(originalUrl);
    var filename = data.filename;
    if (typeof filename !== "string" ||
        (!/\.pdf$/i.test(filename) && !data.isAttachment)) {
      filename = "document.pdf";
    }
    var blobUri = NetUtil.newURI(blobUrl);
    var extHelperAppSvc =
          Cc["@mozilla.org/uriloader/external-helper-app-service;1"].
             getService(Ci.nsIExternalHelperAppService);

    var docIsPrivate = this.isInPrivateBrowsing();
    var netChannel = NetUtil.newChannel({
      uri: blobUri,
      loadUsingSystemPrincipal: true,
    });
    if ("nsIPrivateBrowsingChannel" in Ci &&
        netChannel instanceof Ci.nsIPrivateBrowsingChannel) {
      netChannel.setPrivate(docIsPrivate);
    }
    NetUtil.asyncFetch(netChannel, function(aInputStream, aResult) {
      if (!Components.isSuccessCode(aResult)) {
        if (sendResponse) {
          sendResponse(true);
        }
        return;
      }
      // Create a nsIInputStreamChannel so we can set the url on the channel
      // so the filename will be correct.
      var channel = Cc["@mozilla.org/network/input-stream-channel;1"].
                       createInstance(Ci.nsIInputStreamChannel);
      channel.QueryInterface(Ci.nsIChannel);
      try {
        // contentDisposition/contentDispositionFilename is readonly before FF18
        channel.contentDisposition = Ci.nsIChannel.DISPOSITION_ATTACHMENT;
        if (self.contentDispositionFilename && !data.isAttachment) {
          channel.contentDispositionFilename = self.contentDispositionFilename;
        } else {
          channel.contentDispositionFilename = filename;
        }
      } catch (e) {}
      channel.setURI(originalUri);
      channel.loadInfo = netChannel.loadInfo;
      channel.contentStream = aInputStream;
      if ("nsIPrivateBrowsingChannel" in Ci &&
          channel instanceof Ci.nsIPrivateBrowsingChannel) {
        channel.setPrivate(docIsPrivate);
      }

      var listener = {
        extListener: null,
        onStartRequest(aRequest) {
          var loadContext = self.domWindow.docShell
                                .QueryInterface(Ci.nsILoadContext);
          this.extListener = extHelperAppSvc.doContent(
            (data.isAttachment ? "application/octet-stream" :
                                 "application/pdf"),
            aRequest, loadContext, false);
          this.extListener.onStartRequest(aRequest);
        },
        onStopRequest(aRequest, aStatusCode) {
          if (this.extListener) {
            this.extListener.onStopRequest(aRequest, aStatusCode);
          }
          // Notify the content code we're done downloading.
          if (sendResponse) {
            sendResponse(false);
          }
        },
        onDataAvailable(aRequest, aDataInputStream, aOffset, aCount) {
          this.extListener.onDataAvailable(aRequest, aDataInputStream,
                                           aOffset, aCount);
        },
      };

      channel.asyncOpen(listener);
    });
  }

  getLocale() {
    return Services.locale.requestedLocale || "en-US";
  }

  getStrings(data) {
    try {
      // Lazy initialization of localizedStrings
      if (!("localizedStrings" in this)) {
        this.localizedStrings = getLocalizedStrings("viewer.properties");
      }
      var result = this.localizedStrings[data];
      return JSON.stringify(result || null);
    } catch (e) {
      log("Unable to retrieve localized strings: " + e);
      return "null";
    }
  }

  supportsIntegratedFind() {
    // Integrated find is only supported when we're not in a frame
    return this.domWindow.frameElement === null;
  }

  supportsDocumentFonts() {
    var prefBrowser = getIntPref("browser.display.use_document_fonts", 1);
    var prefGfx = getBoolPref("gfx.downloadable_fonts.enabled", true);
    return (!!prefBrowser && prefGfx);
  }

  supportsDocumentColors() {
    return getIntPref("browser.display.document_color_use", 0) !== 2;
  }

  supportedMouseWheelZoomModifierKeys() {
    return {
      ctrlKey: getIntPref("mousewheel.with_control.action", 3) === 3,
      metaKey: getIntPref("mousewheel.with_meta.action", 1) === 3,
    };
  }

  reportTelemetry(data) {
    var probeInfo = JSON.parse(data);
    switch (probeInfo.type) {
      case "documentInfo":
        if (!this.telemetryState.documentInfo) {
          PdfJsTelemetry.onDocumentVersion(probeInfo.version | 0);
          PdfJsTelemetry.onDocumentGenerator(probeInfo.generator | 0);
          if (probeInfo.formType) {
            PdfJsTelemetry.onForm(probeInfo.formType === "acroform");
          }
          this.telemetryState.documentInfo = true;
        }
        break;
      case "pageInfo":
        if (!this.telemetryState.firstPageInfo) {
          var duration = Date.now() - this.telemetryState.startAt;
          PdfJsTelemetry.onTimeToView(duration);
          this.telemetryState.firstPageInfo = true;
        }
        break;
      case "documentStats":
        // documentStats can be called several times for one documents.
        // if stream/font types are reported, trying not to submit the same
        // enumeration value multiple times.
        var documentStats = probeInfo.stats;
        if (!documentStats || typeof documentStats !== "object") {
          break;
        }
        var i, streamTypes = documentStats.streamTypes;
        if (Array.isArray(streamTypes)) {
          var STREAM_TYPE_ID_LIMIT = 20;
          for (i = 0; i < STREAM_TYPE_ID_LIMIT; i++) {
            if (streamTypes[i] &&
                !this.telemetryState.streamTypesUsed[i]) {
              PdfJsTelemetry.onStreamType(i);
              this.telemetryState.streamTypesUsed[i] = true;
            }
          }
        }
        var fontTypes = documentStats.fontTypes;
        if (Array.isArray(fontTypes)) {
          var FONT_TYPE_ID_LIMIT = 20;
          for (i = 0; i < FONT_TYPE_ID_LIMIT; i++) {
            if (fontTypes[i] &&
                !this.telemetryState.fontTypesUsed[i]) {
              PdfJsTelemetry.onFontType(i);
              this.telemetryState.fontTypesUsed[i] = true;
            }
          }
        }
        break;
      case "print":
        PdfJsTelemetry.onPrint();
        break;
    }
  }

  /**
   * @param {Object} args - Object with `featureId` and `url` properties.
   * @param {function} sendResponse - Callback function.
   */
  fallback(args, sendResponse) {
    var featureId = args.featureId;

    var domWindow = this.domWindow;
    var strings = getLocalizedStrings("chrome.properties");
    var message;
    if (featureId === "forms") {
      message = getLocalizedString(strings, "unsupported_feature_forms");
    } else {
      message = getLocalizedString(strings, "unsupported_feature");
    }
    PdfJsTelemetry.onFallback();
    PdfjsContentUtils.displayWarning(domWindow, message,
      getLocalizedString(strings, "open_with_different_viewer"),
      getLocalizedString(strings, "open_with_different_viewer", "accessKey"));

    let winmm = domWindow.docShell.messageManager;

    winmm.addMessageListener("PDFJS:Child:fallbackDownload",
      function fallbackDownload(msg) {
        let data = msg.data;
        sendResponse(data.download);

        winmm.removeMessageListener("PDFJS:Child:fallbackDownload",
                                    fallbackDownload);
      });
  }

  updateFindControlState(data) {
    if (!this.supportsIntegratedFind()) {
      return;
    }
    // Verify what we're sending to the findbar.
    var result = data.result;
    var findPrevious = data.findPrevious;
    var findPreviousType = typeof findPrevious;
    if ((typeof result !== "number" || result < 0 || result > 3) ||
        (findPreviousType !== "undefined" && findPreviousType !== "boolean")) {
      return;
    }
    // Allow the `matchesCount` property to be optional, and ensure that
    // it's valid before including it in the data sent to the findbar.
    let matchesCount = null;
    if (isValidMatchesCount(data.matchesCount)) {
      matchesCount = data.matchesCount;
    }

    var winmm = this.domWindow.docShell.messageManager;
    winmm.sendAsyncMessage("PDFJS:Parent:updateControlState", {
      result, findPrevious, matchesCount,
    });
  }

  updateFindMatchesCount(data) {
    if (!this.supportsIntegratedFind()) {
      return;
    }
    // Verify what we're sending to the findbar.
    if (!isValidMatchesCount(data)) {
      return;
    }

    const winmm = this.domWindow.docShell.messageManager;
    winmm.sendAsyncMessage("PDFJS:Parent:updateMatchesCount", data);
  }

  setPreferences(prefs, sendResponse) {
    var defaultBranch = Services.prefs.getDefaultBranch(PREF_PREFIX + ".");
    var numberOfPrefs = 0;
    var prefValue, prefName;
    for (var key in prefs) {
      if (++numberOfPrefs > MAX_NUMBER_OF_PREFS) {
        log("setPreferences - Exceeded the maximum number of preferences " +
            "that is allowed to be set at once.");
        break;
      } else if (!defaultBranch.getPrefType(key)) {
        continue;
      }
      prefValue = prefs[key];
      prefName = (PREF_PREFIX + "." + key);
      switch (typeof prefValue) {
        case "boolean":
          PdfjsContentUtils.setBoolPref(prefName, prefValue);
          break;
        case "number":
          PdfjsContentUtils.setIntPref(prefName, prefValue);
          break;
        case "string":
          if (prefValue.length > MAX_STRING_PREF_LENGTH) {
            log("setPreferences - Exceeded the maximum allowed length " +
                "for a string preference.");
          } else {
            PdfjsContentUtils.setStringPref(prefName, prefValue);
          }
          break;
      }
    }
    if (sendResponse) {
      sendResponse(true);
    }
  }

  getPreferences(prefs, sendResponse) {
    var defaultBranch = Services.prefs.getDefaultBranch(PREF_PREFIX + ".");
    var currentPrefs = {}, numberOfPrefs = 0;
    var prefValue, prefName;
    for (var key in prefs) {
      if (++numberOfPrefs > MAX_NUMBER_OF_PREFS) {
        log("getPreferences - Exceeded the maximum number of preferences " +
            "that is allowed to be fetched at once.");
        break;
      } else if (!defaultBranch.getPrefType(key)) {
        continue;
      }
      prefValue = prefs[key];
      prefName = (PREF_PREFIX + "." + key);
      switch (typeof prefValue) {
        case "boolean":
          currentPrefs[key] = getBoolPref(prefName, prefValue);
          break;
        case "number":
          currentPrefs[key] = getIntPref(prefName, prefValue);
          break;
        case "string":
          currentPrefs[key] = getStringPref(prefName, prefValue);
          break;
      }
    }
    let result = JSON.stringify(currentPrefs);
    if (sendResponse) {
      sendResponse(result);
    }
    return result;
  }
}

/**
 * This is for range requests.
 */
class RangedChromeActions extends ChromeActions {
  constructor(domWindow, contentDispositionFilename, originalRequest,
              rangeEnabled, streamingEnabled, dataListener) {
    super(domWindow, contentDispositionFilename);
    this.dataListener = dataListener;
    this.originalRequest = originalRequest;
    this.rangeEnabled = rangeEnabled;
    this.streamingEnabled = streamingEnabled;

    this.pdfUrl = originalRequest.URI.spec;
    this.contentLength = originalRequest.contentLength;

    // Pass all the headers from the original request through
    var httpHeaderVisitor = {
      headers: {},
      visitHeader(aHeader, aValue) {
        if (aHeader === "Range") {
          // When loading the PDF from cache, firefox seems to set the Range
          // request header to fetch only the unfetched portions of the file
          // (e.g. 'Range: bytes=1024-'). However, we want to set this header
          // manually to fetch the PDF in chunks.
          return;
        }
        this.headers[aHeader] = aValue;
      },
    };
    if (originalRequest.visitRequestHeaders) {
      originalRequest.visitRequestHeaders(httpHeaderVisitor);
    }

    var self = this;
    var xhr_onreadystatechange = function xhr_onreadystatechange() {
      if (this.readyState === 1) { // LOADING
        var netChannel = this.channel;
        // override this XMLHttpRequest's OriginAttributes with our cached parent window's
        // OriginAttributes, as we are currently running under the SystemPrincipal
        this.setOriginAttributes(self.getWindowOriginAttributes());
        if ("nsIPrivateBrowsingChannel" in Ci &&
            netChannel instanceof Ci.nsIPrivateBrowsingChannel) {
          var docIsPrivate = self.isInPrivateBrowsing();
          netChannel.setPrivate(docIsPrivate);
        }
      }
    };
    var getXhr = function getXhr() {
      var xhr = new XMLHttpRequest();
      xhr.addEventListener("readystatechange", xhr_onreadystatechange);
      return xhr;
    };

    this.networkManager = new NetworkManager(this.pdfUrl, {
      httpHeaders: httpHeaderVisitor.headers,
      getXhr,
    });

    // If we are in range request mode, this means we manually issued xhr
    // requests, which we need to abort when we leave the page
    domWindow.addEventListener("unload", function unload(e) {
      domWindow.removeEventListener(e.type, unload);
      self.abortLoading();
    });
  }

  initPassiveLoading() {
    let data, done;
    if (!this.streamingEnabled) {
      this.originalRequest.cancel(Cr.NS_BINDING_ABORTED);
      this.originalRequest = null;
      data = this.dataListener.readData();
      done = this.dataListener.isDone;
      this.dataListener = null;
    } else {
      data = this.dataListener.readData();
      done = this.dataListener.isDone;

      this.dataListener.onprogress = (loaded, total) => {
        this.domWindow.postMessage({
          pdfjsLoadAction: "progressiveRead",
          loaded,
          total,
          chunk: this.dataListener.readData(),
        }, PDF_VIEWER_ORIGIN);
      };
      this.dataListener.oncomplete = () => {
        if (!done && this.dataListener.isDone) {
          this.domWindow.postMessage({
            pdfjsLoadAction: "progressiveDone",
          }, PDF_VIEWER_ORIGIN);
        }
        this.dataListener = null;
      };
    }

    this.domWindow.postMessage({
      pdfjsLoadAction: "supportsRangedLoading",
      rangeEnabled: this.rangeEnabled,
      streamingEnabled: this.streamingEnabled,
      pdfUrl: this.pdfUrl,
      length: this.contentLength,
      data,
      done,
    }, PDF_VIEWER_ORIGIN);

    return true;
  }

  requestDataRange(args) {
    if (!this.rangeEnabled) {
      return;
    }

    var begin = args.begin;
    var end = args.end;
    var domWindow = this.domWindow;
    // TODO(mack): Support error handler. We're not currently not handling
    // errors from chrome code for non-range requests, so this doesn't
    // seem high-pri
    this.networkManager.requestRange(begin, end, {
      onDone: function RangedChromeActions_onDone(aArgs) {
        domWindow.postMessage({
          pdfjsLoadAction: "range",
          begin: aArgs.begin,
          chunk: aArgs.chunk,
        }, PDF_VIEWER_ORIGIN);
      },
      onProgress: function RangedChromeActions_onProgress(evt) {
        domWindow.postMessage({
          pdfjsLoadAction: "rangeProgress",
          loaded: evt.loaded,
        }, PDF_VIEWER_ORIGIN);
      },
    });
  }

  abortLoading() {
    this.networkManager.abortAllRequests();
    if (this.originalRequest) {
      this.originalRequest.cancel(Cr.NS_BINDING_ABORTED);
      this.originalRequest = null;
    }
    this.dataListener = null;
  }
}

/**
 * This is for a single network stream.
 */
class StandardChromeActions extends ChromeActions {
  constructor(domWindow, contentDispositionFilename, originalRequest,
              dataListener) {
    super(domWindow, contentDispositionFilename);
    this.originalRequest = originalRequest;
    this.dataListener = dataListener;
  }

  initPassiveLoading() {
    if (!this.dataListener) {
      return false;
    }

    this.dataListener.onprogress = (loaded, total) => {
      this.domWindow.postMessage({
        pdfjsLoadAction: "progress",
        loaded,
        total,
      }, PDF_VIEWER_ORIGIN);
    };

    this.dataListener.oncomplete = (data, errorCode) => {
      this.domWindow.postMessage({
        pdfjsLoadAction: "complete",
        data,
        errorCode,
      }, PDF_VIEWER_ORIGIN);

      this.dataListener = null;
      this.originalRequest = null;
    };

    return true;
  }

  abortLoading() {
    if (this.originalRequest) {
      this.originalRequest.cancel(Cr.NS_BINDING_ABORTED);
      this.originalRequest = null;
    }
    this.dataListener = null;
  }
}

/**
 * Event listener to trigger chrome privileged code.
 */
class RequestListener {
  constructor(actions) {
    this.actions = actions;
  }

  // Receive an event and synchronously or asynchronously responds.
  receive(event) {
    var message = event.target;
    var doc = message.ownerDocument;
    var action = event.detail.action;
    var data = event.detail.data;
    var sync = event.detail.sync;
    var actions = this.actions;
    if (!(action in actions)) {
      log("Unknown action: " + action);
      return;
    }
    var response;
    if (sync) {
      response = actions[action].call(this.actions, data);
      event.detail.response = Cu.cloneInto(response, doc.defaultView);
    } else {
      if (!event.detail.responseExpected) {
        doc.documentElement.removeChild(message);
        response = null;
      } else {
        response = function sendResponse(aResponse) {
          try {
            var listener = doc.createEvent("CustomEvent");
            let detail = Cu.cloneInto({ response: aResponse },
                                      doc.defaultView);
            listener.initCustomEvent("pdf.js.response", true, false, detail);
            return message.dispatchEvent(listener);
          } catch (e) {
            // doc is no longer accessible because the requestor is already
            // gone. unloaded content cannot receive the response anyway.
            return false;
          }
        };
      }
      actions[action].call(this.actions, data, response);
    }
  }
}

/**
 * Forwards events from the eventElement to the contentWindow only if the
 * content window matches the currently selected browser window.
 */
class FindEventManager {
  constructor(contentWindow) {
    this.contentWindow = contentWindow;
    this.winmm = contentWindow.docShell.messageManager;
  }

  bind() {
    this.contentWindow.addEventListener("unload", (evt) => {
      this.unbind();
    }, {once: true});

    // We cannot directly attach listeners to for the find events
    // since the FindBar is in the parent process. Instead we're
    // asking the PdfjsChromeUtils to do it for us and forward
    // all the find events to us.
    this.winmm.sendAsyncMessage("PDFJS:Parent:addEventListener");
    this.winmm.addMessageListener("PDFJS:Child:handleEvent", this);
  }

  receiveMessage(msg) {
    var detail = msg.data.detail;
    var type = msg.data.type;
    var contentWindow = this.contentWindow;

    detail = Cu.cloneInto(detail, contentWindow);
    var forward = contentWindow.document.createEvent("CustomEvent");
    forward.initCustomEvent(type, true, true, detail);
    contentWindow.dispatchEvent(forward);
  }

  unbind() {
    this.winmm.sendAsyncMessage("PDFJS:Parent:removeEventListener");
    this.winmm.removeMessageListener("PDFJS:Child:handleEvent", this);
  }
}

function PdfStreamConverter() {
}

PdfStreamConverter.prototype = {
  QueryInterface: ChromeUtils.generateQI([Ci.nsIStreamConverter, Ci.nsIStreamListener, Ci.nsIRequestObserver]),

  /*
   * This component works as such:
   * 1. asyncConvertData stores the listener
   * 2. onStartRequest creates a new channel, streams the viewer
   * 3. If range requests are supported:
   *      3.1. Leave the request open until the viewer is ready to switch to
   *           range requests.
   *
   *    If range rquests are not supported:
   *      3.1. Read the stream as it's loaded in onDataAvailable to send
   *           to the viewer
   *
   * The convert function just returns the stream, it's just the synchronous
   * version of asyncConvertData.
   */

  // nsIStreamConverter::convert
  convert(aFromStream, aFromType, aToType, aCtxt) {
    throw Cr.NS_ERROR_NOT_IMPLEMENTED;
  },

  // nsIStreamConverter::asyncConvertData
  asyncConvertData(aFromType, aToType, aListener, aCtxt) {
    // Store the listener passed to us
    this.listener = aListener;
  },

  // nsIStreamListener::onDataAvailable
  onDataAvailable(aRequest, aInputStream, aOffset, aCount) {
    if (!this.dataListener) {
      return;
    }

    var binaryStream = this.binaryStream;
    binaryStream.setInputStream(aInputStream);
    let chunk = new ArrayBuffer(aCount);
    binaryStream.readArrayBuffer(aCount, chunk);
    this.dataListener.append(new Uint8Array(chunk));
  },

  // nsIRequestObserver::onStartRequest
  onStartRequest(aRequest) {
    // Setup the request so we can use it below.
    var isHttpRequest = false;
    try {
      aRequest.QueryInterface(Ci.nsIHttpChannel);
      isHttpRequest = true;
    } catch (e) {}

    var rangeRequest = false;
    var streamRequest = false;
    if (isHttpRequest) {
      var contentEncoding = "identity";
      try {
        contentEncoding = aRequest.getResponseHeader("Content-Encoding");
      } catch (e) {}

      var acceptRanges;
      try {
        acceptRanges = aRequest.getResponseHeader("Accept-Ranges");
      } catch (e) {}

      var hash = aRequest.URI.ref;
      var isPDFBugEnabled = getBoolPref(PREF_PREFIX + ".pdfBugEnabled", false);
      rangeRequest = contentEncoding === "identity" &&
                     acceptRanges === "bytes" &&
                     aRequest.contentLength >= 0 &&
                     !getBoolPref(PREF_PREFIX + ".disableRange", false) &&
                     (!isPDFBugEnabled ||
                      !hash.toLowerCase().includes("disablerange=true"));
      streamRequest = contentEncoding === "identity" &&
                      aRequest.contentLength >= 0 &&
                      !getBoolPref(PREF_PREFIX + ".disableStream", false) &&
                      (!isPDFBugEnabled ||
                       !hash.toLowerCase().includes("disablestream=true"));
    }

    aRequest.QueryInterface(Ci.nsIChannel);

    aRequest.QueryInterface(Ci.nsIWritablePropertyBag);

    var contentDispositionFilename;
    try {
      contentDispositionFilename = aRequest.contentDispositionFilename;
    } catch (e) {}

    // Change the content type so we don't get stuck in a loop.
    aRequest.setProperty("contentType", aRequest.contentType);
    aRequest.contentType = "text/html";
    if (isHttpRequest) {
      // We trust PDF viewer, using no CSP
      aRequest.setResponseHeader("Content-Security-Policy", "", false);
      aRequest.setResponseHeader("Content-Security-Policy-Report-Only", "",
                                 false);
      // The viewer does not need to handle HTTP Refresh header.
      aRequest.setResponseHeader("Refresh", "", false);
    }

    PdfJsTelemetry.onViewerIsUsed();
    PdfJsTelemetry.onDocumentSize(aRequest.contentLength);

    // Creating storage for PDF data
    var contentLength = aRequest.contentLength;
    this.dataListener = new PdfDataListener(contentLength);
    this.binaryStream = Cc["@mozilla.org/binaryinputstream;1"]
                        .createInstance(Ci.nsIBinaryInputStream);

    // Create a new channel that is viewer loaded as a resource.
    var channel = NetUtil.newChannel({
      uri: PDF_VIEWER_WEB_PAGE,
      loadUsingSystemPrincipal: true,
    });

    var listener = this.listener;
    var dataListener = this.dataListener;
    // Proxy all the request observer calls, when it gets to onStopRequest
    // we can get the dom window.  We also intentionally pass on the original
    // request(aRequest) below so we don't overwrite the original channel and
    // trigger an assertion.
    var proxy = {
      onStartRequest(request) {
        listener.onStartRequest(aRequest);
      },
      onDataAvailable(request, inputStream, offset, count) {
        listener.onDataAvailable(aRequest, inputStream,
                                 offset, count);
      },
      onStopRequest(request, statusCode) {
        var domWindow = getDOMWindow(channel, resourcePrincipal);
        if (!Components.isSuccessCode(statusCode) || !domWindow) {
          // The request may have been aborted and the document may have been
          // replaced with something that is not PDF.js, abort attaching.
          listener.onStopRequest(aRequest, statusCode);
          return;
        }
        var actions;
        if (rangeRequest || streamRequest) {
          actions = new RangedChromeActions(
            domWindow, contentDispositionFilename, aRequest,
            rangeRequest, streamRequest, dataListener);
        } else {
          actions = new StandardChromeActions(
            domWindow, contentDispositionFilename, aRequest, dataListener);
        }
        var requestListener = new RequestListener(actions);
        domWindow.document.addEventListener(PDFJS_EVENT_ID, function(event) {
          requestListener.receive(event);
        }, false, true);
        if (actions.supportsIntegratedFind()) {
          var findEventManager = new FindEventManager(domWindow);
          findEventManager.bind();
        }
        listener.onStopRequest(aRequest, statusCode);

        if (domWindow.frameElement) {
          var isObjectEmbed = domWindow.frameElement.tagName !== "IFRAME" ||
            domWindow.frameElement.className === "previewPluginContentFrame";
          PdfJsTelemetry.onEmbed(isObjectEmbed);
        }
      },
    };

    // Keep the URL the same so the browser sees it as the same.
    channel.originalURI = aRequest.URI;
    channel.loadGroup = aRequest.loadGroup;
    channel.loadInfo.originAttributes = aRequest.loadInfo.originAttributes;

    // We can use the resource principal when data is fetched by the chrome,
    // e.g. useful for NoScript. Make make sure we reuse the origin attributes
    // from the request channel to keep isolation consistent.
    var uri = NetUtil.newURI(PDF_VIEWER_WEB_PAGE);
    var resourcePrincipal =
      Services.scriptSecurityManager.createCodebasePrincipal(uri,
        aRequest.loadInfo.originAttributes);
    aRequest.owner = resourcePrincipal;

    channel.asyncOpen(proxy);
  },

  // nsIRequestObserver::onStopRequest
  onStopRequest(aRequest, aStatusCode) {
    if (!this.dataListener) {
      // Do nothing
      return;
    }

    if (Components.isSuccessCode(aStatusCode)) {
      this.dataListener.finish();
    } else {
      this.dataListener.error(aStatusCode);
    }
    delete this.dataListener;
    delete this.binaryStream;
  },
};