electron/lib/browser/guest-window-manager.ts

import * as electron from 'electron/main';
import { ipcMainInternal } from '@electron/internal/browser/ipc-main-internal';
import * as ipcMainUtils from '@electron/internal/browser/ipc-main-internal-utils';
import { parseFeatures } from '@electron/internal/common/parse-features-string';

const { isSameOrigin } = process._linkedBinding('electron_common_v8_util');

const { BrowserWindow } = electron;
const hasProp = {}.hasOwnProperty;
const frameToGuest = new Map<string, Electron.BrowserWindow>();

// Security options that child windows will always inherit from parent windows
const inheritedWebPreferences = new Map([
  ['contextIsolation', true],
  ['javascript', false],
  ['nativeWindowOpen', true],
  ['nodeIntegration', false],
  ['enableRemoteModule', false],
  ['sandbox', true],
  ['webviewTag', false],
  ['nodeIntegrationInSubFrames', false],
  ['enableWebSQL', false]
]);

// Copy attribute of |parent| to |child| if it is not defined in |child|.
const mergeOptions = function (child: Record<string, any>, parent: Record<string, any>, visited?: Set<Record<string, any>>) {
  // Check for circular reference.
  if (visited == null) visited = new Set();
  if (visited.has(parent)) return;

  visited.add(parent);
  for (const key in parent) {
    if (key === 'type') continue;
    if (!hasProp.call(parent, key)) continue;
    if (key in child && key !== 'webPreferences') continue;

    const value = parent[key];
    if (typeof value === 'object' && !Array.isArray(value)) {
      child[key] = mergeOptions(child[key] || {}, value, visited);
    } else {
      child[key] = value;
    }
  }
  visited.delete(parent);

  return child;
};

// Merge |options| with the |embedder|'s window's options.
const mergeBrowserWindowOptions = function (embedder: Electron.WebContents, options: Record<string, any>) {
  if (options.webPreferences == null) {
    options.webPreferences = {};
  }
  if (embedder.browserWindowOptions != null) {
    let parentOptions = embedder.browserWindowOptions;

    // if parent's visibility is available, that overrides 'show' flag (#12125)
    const win = BrowserWindow.fromWebContents(embedder);
    if (win != null) {
      parentOptions = {
        ...win.getBounds(),
        ...embedder.browserWindowOptions,
        show: win.isVisible()
      };
    }

    // Inherit the original options if it is a BrowserWindow.
    mergeOptions(options, parentOptions);
  } else {
    // Or only inherit webPreferences if it is a webview.
    mergeOptions(options.webPreferences, embedder.getLastWebPreferences());
  }

  // Inherit certain option values from parent window
  const webPreferences = embedder.getLastWebPreferences();
  for (const [name, value] of inheritedWebPreferences) {
    if ((webPreferences as any)[name] === value) {
      options.webPreferences[name] = value;
    }
  }

  if (!webPreferences.nativeWindowOpen) {
    // Sets correct openerId here to give correct options to 'new-window' event handler
    options.webPreferences.openerId = embedder.id;
  }

  return options;
};

const MULTIPART_CONTENT_TYPE = 'multipart/form-data';
const URL_ENCODED_CONTENT_TYPE = 'application/x-www-form-urlencoded';
function makeContentTypeHeader ({ contentType, boundary }: { contentType: string, boundary?: string }) {
  const header = `content-type: ${contentType};`;
  if (contentType === MULTIPART_CONTENT_TYPE) {
    return `${header} boundary=${boundary}`;
  }
  return header;
}

// Figure out appropriate headers for post data.
const parseContentTypeFormat = function (postData: Electron.UploadRawData[]) {
  if (postData.length) {
    // For multipart forms, the first element will start with the boundary
    // notice, which looks something like `------WebKitFormBoundary12345678`
    // Note, this regex would fail when submitting a urlencoded form with an
    // input attribute of name="--theKey", but, uhh, don't do that?
    const postDataFront = postData[0].bytes.toString();
    const boundary = /^--.*[^-\r\n]/.exec(postDataFront);
    if (boundary) {
      return {
        boundary: boundary[0].substr(2),
        contentType: MULTIPART_CONTENT_TYPE
      };
    }
  }
  // Either the form submission didn't contain any inputs (the postData array
  // was empty), or we couldn't find the boundary and thus we can assume this is
  // a key=value style form.
  return {
    contentType: URL_ENCODED_CONTENT_TYPE
  };
};

// Setup a new guest with |embedder|
const setupGuest = function (embedder: Electron.WebContents, frameName: string, guest: Electron.BrowserWindow) {
  // When |embedder| is destroyed we should also destroy attached guest, and if
  // guest is closed by user then we should prevent |embedder| from double
  // closing guest.
  const guestId = guest.webContents.id;
  const closedByEmbedder = function () {
    guest.removeListener('closed', closedByUser);
    guest.destroy();
  };
  const closedByUser = function () {
    embedder._sendInternal('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_CLOSED_' + guestId);
    embedder.removeListener('current-render-view-deleted' as any, closedByEmbedder);
  };
  embedder.once('current-render-view-deleted' as any, closedByEmbedder);
  guest.once('closed', closedByUser);
  if (frameName) {
    frameToGuest.set(frameName, guest);
    guest.frameName = frameName;
    guest.once('closed', function () {
      frameToGuest.delete(frameName);
    });
  }
  return guestId;
};

// Create a new guest created by |embedder| with |options|.
const createGuest = function (embedder: Electron.webContents, url: string, referrer: string | Electron.Referrer,
  frameName: string, options: Record<string, any>, postData?: Electron.UploadRawData[]) {
  let guest = frameToGuest.get(frameName);
  if (frameName && (guest != null)) {
    guest.loadURL(url);
    return guest.webContents.id;
  }

  // Remember the embedder window's id.
  if (options.webPreferences == null) {
    options.webPreferences = {};
  }

  guest = new BrowserWindow(options);
  if (!options.webContents) {
    // We should not call `loadURL` if the window was constructed from an
    // existing webContents (window.open in a sandboxed renderer).
    //
    // Navigating to the url when creating the window from an existing
    // webContents is not necessary (it will navigate there anyway).
    const loadOptions: Electron.LoadURLOptions = {
      httpReferrer: referrer
    };
    if (postData != null) {
      loadOptions.postData = postData;
      loadOptions.extraHeaders = makeContentTypeHeader(parseContentTypeFormat(postData));
    }
    guest.loadURL(url, loadOptions);
  }

  return setupGuest(embedder, frameName, guest);
};

const getGuestWindow = function (guestContents: Electron.WebContents) {
  let guestWindow = BrowserWindow.fromWebContents(guestContents);
  if (guestWindow == null) {
    const hostContents = guestContents.hostWebContents;
    if (hostContents != null) {
      guestWindow = BrowserWindow.fromWebContents(hostContents);
    }
  }
  if (!guestWindow) {
    throw new Error('getGuestWindow failed');
  }
  return guestWindow;
};

const isChildWindow = function (sender: Electron.WebContents, target: Electron.WebContents) {
  return target.getLastWebPreferences().openerId === sender.id;
};

const isRelatedWindow = function (sender: Electron.WebContents, target: Electron.WebContents) {
  return isChildWindow(sender, target) || isChildWindow(target, sender);
};

const isScriptableWindow = function (sender: Electron.WebContents, target: Electron.WebContents) {
  return isRelatedWindow(sender, target) && isSameOrigin(sender.getURL(), target.getURL());
};

const isNodeIntegrationEnabled = function (sender: Electron.WebContents) {
  return sender.getLastWebPreferences().nodeIntegration === true;
};

// Checks whether |sender| can access the |target|:
const canAccessWindow = function (sender: Electron.WebContents, target: Electron.WebContents) {
  return isChildWindow(sender, target) ||
         isScriptableWindow(sender, target) ||
         isNodeIntegrationEnabled(sender);
};

// Routed window.open messages with raw options
ipcMainInternal.on('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_OPEN', (event, url: string, frameName: string, features: string) => {
  // This should only be allowed for senders that have nativeWindowOpen: false
  const lastWebPreferences = event.sender.getLastWebPreferences();
  if (lastWebPreferences.nativeWindowOpen || lastWebPreferences.sandbox) {
    event.returnValue = null;
    throw new Error('GUEST_WINDOW_MANAGER_WINDOW_OPEN denied: expected native window.open');
  }
  if (url == null || url === '') url = 'about:blank';
  if (frameName == null) frameName = '';
  if (features == null) features = '';

  const disposition = 'new-window';
  const { options, webPreferences, additionalFeatures } = parseFeatures(features);
  if (!options.title) options.title = frameName;
  (options as Electron.BrowserWindowConstructorOptions).webPreferences = webPreferences;

  const referrer: Electron.Referrer = { url: '', policy: 'default' };
  internalWindowOpen(event, url, referrer, frameName, disposition, options, additionalFeatures);
});

// Routed window.open messages with fully parsed options
export function internalWindowOpen (event: ElectronInternal.IpcMainInternalEvent, url: string, referrer: string | Electron.Referrer,
  frameName: string, disposition: string, options: Record<string, any>, additionalFeatures: string[], postData?: Electron.UploadRawData[]) {
  options = mergeBrowserWindowOptions(event.sender, options);
  const postBody = postData ? {
    data: postData,
    ...parseContentTypeFormat(postData)
  } : null;

  event.sender.emit('new-window', event, url, frameName, disposition, options, additionalFeatures, referrer, postBody);
  const { newGuest } = event as unknown as { newGuest: Electron.BrowserWindow };
  if ((event.sender.getType() === 'webview' && event.sender.getLastWebPreferences().disablePopups) || event.defaultPrevented) {
    if (newGuest != null) {
      if (options.webContents === newGuest.webContents) {
        // the webContents is not changed, so set defaultPrevented to false to
        // stop the callers of this event from destroying the webContents.
        (event as any).defaultPrevented = false;
      }
      event.returnValue = setupGuest(event.sender, frameName, newGuest);
    } else {
      event.returnValue = null;
    }
  } else {
    event.returnValue = createGuest(event.sender, url, referrer, frameName, options, postData);
  }
}

const makeSafeHandler = function<T> (handler: (event: Electron.IpcMainInvokeEvent, guestContents: Electron.webContents, ...args: any[]) => T) {
  return (event: Electron.IpcMainInvokeEvent, guestId: number, ...args: any[]) => {
    // Access webContents via electron to prevent circular require.
    const guestContents = electron.webContents.fromId(guestId);
    if (!guestContents) {
      throw new Error(`Invalid guestId: ${guestId}`);
    }

    return handler(event, guestContents, ...args);
  };
};

const handleMessage = function (channel: string, handler: (event: Electron.IpcMainInvokeEvent, guestContents: Electron.webContents, ...args: any[]) => any) {
  ipcMainInternal.handle(channel, makeSafeHandler(handler));
};

const handleMessageSync = function (channel: string, handler: (event: Electron.IpcMainInvokeEvent, guestContents: Electron.webContents, ...args: any[]) => any) {
  ipcMainUtils.handleSync(channel, makeSafeHandler(handler));
};

const securityCheck = function (contents: Electron.WebContents, guestContents: Electron.WebContents, check: (sender: Electron.WebContents, target: Electron.WebContents) => boolean) {
  if (!check(contents, guestContents)) {
    console.error(`Blocked ${contents.getURL()} from accessing guestId: ${guestContents.id}`);
    throw new Error(`Access denied to guestId: ${guestContents.id}`);
  }
};

const windowMethods = new Set([
  'destroy',
  'focus',
  'blur'
]);

handleMessage('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_METHOD', (event, guestContents, method: string, ...args: any[]) => {
  securityCheck(event.sender, guestContents, canAccessWindow);

  if (!windowMethods.has(method)) {
    console.error(`Blocked ${event.sender.getURL()} from calling method: ${method}`);
    throw new Error(`Invalid method: ${method}`);
  }

  return (getGuestWindow(guestContents) as any)[method](...args);
});

handleMessage('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_POSTMESSAGE', (event, guestContents, message, targetOrigin, sourceOrigin) => {
  if (targetOrigin == null) {
    targetOrigin = '*';
  }

  // The W3C does not seem to have word on how postMessage should work when the
  // origins do not match, so we do not do |canAccessWindow| check here since
  // postMessage across origins is useful and not harmful.
  securityCheck(event.sender, guestContents, isRelatedWindow);

  if (targetOrigin === '*' || isSameOrigin(guestContents.getURL(), targetOrigin)) {
    const sourceId = event.sender.id;
    guestContents._sendInternal('ELECTRON_GUEST_WINDOW_POSTMESSAGE', sourceId, message, sourceOrigin);
  }
});

const webContentsMethodsAsync = new Set([
  'loadURL',
  'executeJavaScript',
  'print'
]);

handleMessage('ELECTRON_GUEST_WINDOW_MANAGER_WEB_CONTENTS_METHOD', (event, guestContents, method: string, ...args: any[]) => {
  securityCheck(event.sender, guestContents, canAccessWindow);

  if (!webContentsMethodsAsync.has(method)) {
    console.error(`Blocked ${event.sender.getURL()} from calling method: ${method}`);
    throw new Error(`Invalid method: ${method}`);
  }

  return (guestContents as any)[method](...args);
});

const webContentsMethodsSync = new Set([
  'getURL'
]);

handleMessageSync('ELECTRON_GUEST_WINDOW_MANAGER_WEB_CONTENTS_METHOD', (event, guestContents, method: string, ...args: any[]) => {
  securityCheck(event.sender, guestContents, canAccessWindow);

  if (!webContentsMethodsSync.has(method)) {
    console.error(`Blocked ${event.sender.getURL()} from calling method: ${method}`);
    throw new Error(`Invalid method: ${method}`);
  }

  return (guestContents as any)[method](...args);
});