chromecom.js

/* Copyright 2013 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.
 */
/* globals chrome */

import { AppOptions } from "./app_options.js";
import { BaseExternalServices } from "./external_services.js";
import { BasePreferences } from "./preferences.js";
import { GenericL10n } from "./genericl10n.js";
import { GenericScripting } from "./generic_scripting.js";
import { SignatureStorage } from "./generic_signature_storage.js";

// These strings are from chrome/app/resources/generated_resources_*.xtb.
// eslint-disable-next-line sort-imports
import i18nFileAccessLabels from "./chrome-i18n-allow-access-to-file-urls.json" with { type: "json" };

if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("CHROME")) {
  throw new Error(
    'Module "pdfjs-web/chromecom" shall not be used outside CHROME build.'
  );
}

(function rewriteUrlClosure() {
  // Run this code outside DOMContentLoaded to make sure that the URL
  // is rewritten as soon as possible.
  const queryString = document.location.search.slice(1);
  const m = /(^|&)file=([^&]*)/.exec(queryString);
  let defaultUrl = m ? decodeURIComponent(m[2]) : "";
  if (!defaultUrl && queryString.startsWith("DNR:")) {
    // Redirected via DNR, see registerPdfRedirectRule in pdfHandler.js.
    defaultUrl = queryString.slice(4);
  }

  // Example: chrome-extension://.../http://example.com/file.pdf
  const humanReadableUrl = "/" + defaultUrl + location.hash;
  history.replaceState(history.state, "", humanReadableUrl);

  AppOptions.set("defaultUrl", defaultUrl);
})();

let viewerApp = { initialized: false };
function initCom(app) {
  viewerApp = app;

  // Ensure that PDFViewerApplication.initialBookmark reflects the current hash,
  // in case the URL rewrite above results in a different hash.
  viewerApp.initialBookmark = location.hash.slice(1);
}

const ChromeCom = {
  /**
   * Creates an event that the extension is listening for and will
   * asynchronously respond by calling the callback.
   *
   * @param {string} action - The action to trigger.
   * @param {string} [data] - The data to send.
   * @param {Function} [callback] - Response callback that will be called with
   *   one data argument. When the request cannot be handled, the callback is
   *   immediately invoked with no arguments.
   */
  request(action, data, callback) {
    const message = {
      action,
      data,
    };
    if (!chrome.runtime) {
      console.error("chrome.runtime is undefined.");
      callback?.();
    } else if (callback) {
      chrome.runtime.sendMessage(message, callback);
    } else {
      chrome.runtime.sendMessage(message);
    }
  },

  /**
   * Resolves a PDF file path and attempts to detects length.
   *
   * @param {string} file - Absolute URL of PDF file.
   * @param {Function} callback - A callback with resolved URL and file length.
   */
  resolvePDFFile(file, callback) {
    // Expand drive:-URLs to filesystem URLs (Chrome OS)
    file = file.replace(
      /^drive:/i,
      "filesystem:" + location.origin + "/external/"
    );

    if (/^https?:/.test(file)) {
      // Assumption: The file being opened is the file that was requested.
      // There is no UI to input a different URL, so this assumption will hold
      // for now.
      setReferer(file, function () {
        callback(file);
      });
      return;
    }
    if (/^file?:/.test(file)) {
      getEmbedderOrigin(function (origin) {
        // If the origin cannot be determined, let Chrome decide whether to
        // allow embedding files. Otherwise, only allow local files to be
        // embedded from local files or Chrome extensions.
        // Even without this check, the file load in frames is still blocked,
        // but this may change in the future (https://crbug.com/550151).
        if (origin && !/^file:|^chrome-extension:/.test(origin)) {
          viewerApp._documentError(null, {
            message:
              `Blocked ${origin} from loading ${file}. Refused to load ` +
              "a local file in a non-local page for security reasons.",
          });
          return;
        }
        isAllowedFileSchemeAccess(function (isAllowedAccess) {
          if (isAllowedAccess) {
            callback(file);
          } else {
            requestAccessToLocalFile(file, viewerApp.overlayManager, callback);
          }
        });
      });
      return;
    }
    callback(file);
  },
};

function getEmbedderOrigin(callback) {
  const origin = window === top ? location.origin : location.ancestorOrigins[0];
  if (origin === "null") {
    // file:-URLs, data-URLs, sandboxed frames, etc.
    getParentOrigin(callback);
  } else {
    callback(origin);
  }
}

function getParentOrigin(callback) {
  ChromeCom.request("getParentOrigin", null, callback);
}

function isAllowedFileSchemeAccess(callback) {
  ChromeCom.request("isAllowedFileSchemeAccess", null, callback);
}

function isRuntimeAvailable() {
  try {
    // When the extension is reloaded, the extension runtime is destroyed and
    // the extension APIs become unavailable.
    if (chrome.runtime?.getManifest()) {
      return true;
    }
  } catch {}
  return false;
}

function reloadIfRuntimeIsUnavailable() {
  if (!isRuntimeAvailable()) {
    location.reload();
  }
}

let chromeFileAccessOverlayPromise;
function requestAccessToLocalFile(fileUrl, overlayManager, callback) {
  const dialog = document.getElementById("chromeFileAccessDialog");
  if (top !== window) {
    // When the extension reloads after receiving new permissions, the pages
    // have to be reloaded to restore the extension runtime. Auto-reload
    // frames, because users should not have to reload the whole page just to
    // update the viewer.
    // Top-level frames are closed by Chrome upon reload, so there is no need
    // for detecting unload of the top-level frame. Should this ever change
    // (crbug.com/511670), then the user can just reload the tab.
    window.addEventListener("focus", reloadIfRuntimeIsUnavailable);
    dialog.addEventListener("close", function () {
      window.removeEventListener("focus", reloadIfRuntimeIsUnavailable);
      reloadIfRuntimeIsUnavailable();
    });
  }
  chromeFileAccessOverlayPromise ||= overlayManager.register(
    dialog,
    /* canForceClose = */ true
  );

  chromeFileAccessOverlayPromise.then(function () {
    const iconPath = chrome.runtime.getManifest().icons[48];
    document.getElementById("chrome-pdfjs-logo-bg").style.backgroundImage =
      "url(" + chrome.runtime.getURL(iconPath) + ")";

    // Use Chrome's definition of UI language instead of PDF.js's #lang=...,
    // because the shown string should match the UI at chrome://extensions.
    const i18nFileAccessLabel =
      i18nFileAccessLabels[chrome.i18n.getUILanguage?.()];
    if (i18nFileAccessLabel) {
      document.getElementById("chrome-file-access-label").textContent =
        i18nFileAccessLabel;
    }

    const link = document.getElementById("chrome-link-to-extensions-page");
    link.href = "chrome://extensions/?id=" + chrome.runtime.id;
    link.onclick = function (e) {
      // Direct navigation to chrome:// URLs is blocked by Chrome, so we
      // have to ask the background page to open chrome://extensions/?id=...
      e.preventDefault();
      // Open in the current tab by default, because toggling the file access
      // checkbox causes the extension to reload, and Chrome will close all
      // tabs upon reload.
      ChromeCom.request("openExtensionsPageForFileAccess", {
        newTab: e.ctrlKey || e.metaKey || e.button === 1 || window !== top,
      });
    };

    // Show which file is being opened to help the user with understanding
    // why this permission request is shown.
    document.getElementById("chrome-url-of-local-file").textContent = fileUrl;

    document.getElementById("chrome-file-fallback").onchange = function () {
      const file = this.files[0];
      if (file) {
        const originalFilename = decodeURIComponent(fileUrl.split("/").pop());
        let originalUrl = fileUrl;
        if (originalFilename !== file.name) {
          const msg =
            "The selected file does not match the original file." +
            "\nOriginal: " +
            originalFilename +
            "\nSelected: " +
            file.name +
            "\nDo you want to open the selected file?";
          // eslint-disable-next-line no-alert
          if (!confirm(msg)) {
            this.value = "";
            return;
          }
          // There is no way to retrieve the original URL from the File object.
          // So just generate a fake path.
          originalUrl = "file:///fakepath/to/" + encodeURIComponent(file.name);
        }
        callback(URL.createObjectURL(file), file.size, originalUrl);
        overlayManager.close(dialog);
      }
    };

    overlayManager.open(dialog);
  });
}

let dnrRequestId;
// This port is used for several purposes:
// 1. When disconnected, the background page knows that the frame has unload.
// 2. When the referrer was saved in history.state.chromecomState, it is sent
//    to the background page.
// 3. When the background page knows the referrer of the page, the referrer is
//    saved in history.state.chromecomState.
let port;
// Set the referer for the given URL.
// 0. Background: If loaded via a http(s) URL: Save referer.
// 1. Page -> background: send URL and referer from history.state
// 2. Background: Bind referer to URL (via webRequest).
// 3. Background -> page: Send latest referer and save to history.
// 4. Page: Invoke callback.
function setReferer(url, callback) {
  dnrRequestId ??= crypto.getRandomValues(new Uint32Array(1))[0] % 0x80000000;
  if (!port) {
    // The background page will accept the port, and keep adding the Referer
    // request header to requests to |url| until the port is disconnected.
    port = chrome.runtime.connect({ name: "chromecom-referrer" });
  }
  port.onDisconnect.addListener(onDisconnect);
  port.onMessage.addListener(onMessage);
  // Initiate the information exchange.
  port.postMessage({
    dnrRequestId,
    referer: window.history.state?.chromecomState,
    requestUrl: url,
  });

  function onMessage(referer) {
    if (referer) {
      // The background extracts the Referer from the initial HTTP request for
      // the PDF file. When the viewer is reloaded or when the user navigates
      // back and forward, the background page will not observe a HTTP request
      // with Referer. To make sure that the Referer is preserved, store it in
      // history.state, which is preserved across reloads/navigations.
      const state = window.history.state || {};
      state.chromecomState = referer;
      window.history.replaceState(state, "");
    }
    onCompleted();
  }
  function onDisconnect() {
    // When the connection fails, ignore the error and call the callback.
    port = null;
    callback();
  }
  function onCompleted() {
    port.onDisconnect.removeListener(onDisconnect);
    port.onMessage.removeListener(onMessage);
    callback();
  }
}

// chrome.storage.sync is not supported in every Chromium-derivate.
// Note: The background page takes care of migrating values from
// chrome.storage.local to chrome.storage.sync when needed.
const storageArea = chrome.storage.sync || chrome.storage.local;

class Preferences extends BasePreferences {
  async _writeToStorage(prefObj) {
    return new Promise(resolve => {
      if (prefObj === this.defaults) {
        const keysToRemove = Object.keys(this.defaults);
        // If the storage is reset, remove the keys so that the values from
        // managed storage are applied again.
        storageArea.remove(keysToRemove, function () {
          resolve();
        });
      } else {
        storageArea.set(prefObj, function () {
          resolve();
        });
      }
    });
  }

  async _readFromStorage(prefObj) {
    return new Promise(resolve => {
      const getPreferences = defaultPrefs => {
        if (chrome.runtime.lastError) {
          // Managed storage not supported, e.g. in Opera.
          defaultPrefs = this.defaults;
        }
        storageArea.get(defaultPrefs, function (readPrefs) {
          resolve({ prefs: readPrefs });
        });
      };

      if (chrome.storage.managed) {
        // Get preferences as set by the system administrator.
        // See extensions/chromium/preferences_schema.json for more information.
        // These preferences can be overridden by the user.

        // Deprecated preferences are removed from web/default_preferences.json,
        // but kept in extensions/chromium/preferences_schema.json for backwards
        // compatibility with managed preferences.
        const defaultManagedPrefs = Object.assign(
          {
            enableHandToolOnLoad: false,
            disableTextLayer: false,
            enhanceTextSelection: false,
            showPreviousViewOnLoad: true,
            disablePageMode: false,
          },
          this.defaults
        );

        chrome.storage.managed.get(defaultManagedPrefs, function (items) {
          items ||= defaultManagedPrefs;
          // Migration logic for deprecated preferences: If the new preference
          // is not defined by an administrator (i.e. the value is the same as
          // the default value), and a deprecated preference is set with a
          // non-default value, migrate the deprecated preference value to the
          // new preference value.
          // Never remove this, because we have no means of modifying managed
          // preferences.

          // Migration code for https://github.com/mozilla/pdf.js/pull/7635.
          if (items.enableHandToolOnLoad && !items.cursorToolOnLoad) {
            items.cursorToolOnLoad = 1;
          }
          delete items.enableHandToolOnLoad;

          // Migration code for https://github.com/mozilla/pdf.js/pull/9479.
          if (items.textLayerMode !== 1 && items.disableTextLayer) {
            items.textLayerMode = 0;
          }
          delete items.disableTextLayer;
          delete items.enhanceTextSelection;

          // Migration code for https://github.com/mozilla/pdf.js/pull/10502.
          if (!items.showPreviousViewOnLoad && !items.viewOnLoad) {
            items.viewOnLoad = 1;
          }
          delete items.showPreviousViewOnLoad;
          delete items.disablePageMode;

          getPreferences(items);
        });
      } else {
        // Managed storage not supported, e.g. in old Chromium versions.
        getPreferences(this.defaults);
      }
    });
  }
}

class ExternalServices extends BaseExternalServices {
  initPassiveLoading() {
    ChromeCom.resolvePDFFile(
      AppOptions.get("defaultUrl"),
      function (url, length, originalUrl) {
        viewerApp.open({ url, length, originalUrl });
      }
    );
  }

  async createL10n() {
    return new GenericL10n(navigator.language);
  }

  createScripting() {
    return new GenericScripting(AppOptions.get("sandboxBundleSrc"));
  }

  createSignatureStorage(eventBus, signal) {
    return new SignatureStorage(eventBus, signal);
  }
}

class MLManager {
  isEnabledFor(_name) {
    return false;
  }

  async guess() {
    return null;
  }
}

export { ExternalServices, initCom, MLManager, Preferences };