feat: add webContents.setWindowOpenHandler API (#24517)

Co-authored-by: Jeremy Rose <jeremya@chromium.org>

lib/browser/guest-window-proxy.ts

@@ -0,0 +1,211 @@
+/**
+ * Manage guest windows when using the default BrowserWindowProxy version of the
+ * renderer's window.open (i.e. nativeWindowOpen off). This module mostly
+ * consists of marshaling IPC requests from the BrowserWindowProxy to the
+ * WebContents.
+ */
+import { webContents, BrowserWindow } from 'electron/main';
+import type { WebContents } from 'electron/main';
+import { ipcMainInternal } from '@electron/internal/browser/ipc-main-internal';
+import * as ipcMainUtils from '@electron/internal/browser/ipc-main-internal-utils';
+import { openGuestWindow } from '@electron/internal/browser/guest-window-manager';
+import { IPC_MESSAGES } from '@electron/internal/common/ipc-messages';
+
+const { isSameOrigin } = process._linkedBinding('electron_common_v8_util');
+
+const getGuestWindow = function (guestContents: 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: WebContents, target: WebContents) {
+  return (target as any).getLastWebPreferences().openerId === sender.id;
+};
+
+const isRelatedWindow = function (sender: WebContents, target: WebContents) {
+  return isChildWindow(sender, target) || isChildWindow(target, sender);
+};
+
+const isScriptableWindow = function (sender: WebContents, target: WebContents) {
+  return (
+    isRelatedWindow(sender, target) &&
+    isSameOrigin(sender.getURL(), target.getURL())
+  );
+};
+
+const isNodeIntegrationEnabled = function (sender: WebContents) {
+  return (sender as any).getLastWebPreferences().nodeIntegration === true;
+};
+
+// Checks whether |sender| can access the |target|:
+const canAccessWindow = function (sender: WebContents, target: WebContents) {
+  return (
+    isChildWindow(sender, target) ||
+    isScriptableWindow(sender, target) ||
+    isNodeIntegrationEnabled(sender)
+  );
+};
+
+// Routed window.open messages with raw options
+ipcMainInternal.on(
+  IPC_MESSAGES.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 as any).getLastWebPreferences();
+    if (lastWebPreferences.nativeWindowOpen || lastWebPreferences.sandbox) {
+      (event as any).returnValue = null;
+      throw new Error(
+        'GUEST_WINDOW_MANAGER_WINDOW_OPEN denied: expected native window.open'
+      );
+    }
+
+    const browserWindowOptions = (event.sender as any)._callWindowOpenHandler(event, url, frameName, features);
+    if (event.defaultPrevented) {
+      return;
+    }
+    const guest = openGuestWindow({
+      event,
+      embedder: event.sender,
+      referrer: { url: '', policy: 'default' },
+      disposition: 'new-window',
+      overrideBrowserWindowOptions: browserWindowOptions,
+      windowOpenArgs: {
+        url: url || 'about:blank',
+        frameName: frameName || '',
+        features: features || ''
+      }
+    });
+
+    (event as any).returnValue = guest ? guest.webContents.id : null;
+  }
+);
+
+type IpcHandler<T, Event> = (event: Event, guestContents: Electron.WebContents, ...args: any[]) => T;
+const makeSafeHandler = function<T, Event> (handler: IpcHandler<T, Event>) {
+  return (event: Event, guestId: number, ...args: any[]) => {
+    // Access webContents via electron to prevent circular require.
+    const guestContents = webContents.fromId(guestId);
+    if (!guestContents) {
+      throw new Error(`Invalid guestId: ${guestId}`);
+    }
+
+    return handler(event, guestContents as Electron.WebContents, ...args);
+  };
+};
+
+const handleMessage = function (channel: string, handler: IpcHandler<any, Electron.IpcMainInvokeEvent>) {
+  ipcMainInternal.handle(channel, makeSafeHandler(handler));
+};
+
+const handleMessageSync = function (channel: string, handler: IpcHandler<any, ElectronInternal.IpcMainInternalEvent>) {
+  ipcMainUtils.handleSync(channel, makeSafeHandler(handler));
+};
+
+type ContentsCheck = (contents: WebContents, guestContents: WebContents) => boolean;
+const securityCheck = function (contents: WebContents, guestContents: WebContents, check: ContentsCheck) {
+  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(
+  IPC_MESSAGES.GUEST_WINDOW_MANAGER_WINDOW_METHOD,
+  (event, guestContents, method, ...args) => {
+    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(
+  IPC_MESSAGES.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(
+        IPC_MESSAGES.GUEST_WINDOW_POSTMESSAGE,
+        sourceId,
+        message,
+        sourceOrigin
+      );
+    }
+  }
+);
+
+const webContentsMethodsAsync = new Set([
+  'loadURL',
+  'executeJavaScript',
+  'print'
+]);
+
+handleMessage(
+  IPC_MESSAGES.GUEST_WINDOW_MANAGER_WEB_CONTENTS_METHOD,
+  (event, guestContents, method, ...args) => {
+    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(
+  IPC_MESSAGES.GUEST_WINDOW_MANAGER_WEB_CONTENTS_METHOD,
+  (event, guestContents, method, ...args) => {
+    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);
+  }
+);