feat: add a getScopedToSender API on ipcMain

This solves the usecase where folks for either security or use-case
reasons only want to listen for message X coming from webContents Y.

Instead of checking the `sender` or `sender.id` each time and hoping
you don't miss a listener or writing your own abstraction around IPC
(let's be real we've all done that before) this provides a low-overhead
first-party API for solving this problem.

This use-case has actually come up in internal core code as well so
we can benefit from this API internally.

docs/api/ipc-main.md

@@ -88,6 +88,17 @@ Removes the specified `listener` from the listener array for the specified
 
 Removes listeners of the specified `channel`.
 
+### `ipcMain.getScopedToSender(sender)`
+
+* `sender` [WebContents](web-contents.md)
+
+Returns `IpcMain`
+
+Gets a new instance of `IpcMain` that is scoped to only emit ipc messages from
+the given sender.  This is useful for ensuring the messages you are handling
+only come from a webContents you trust without having to check the sender
+for every message.
+
 ## Event object
 
 The documentation for the `event` object passed to the `callback` can be found

filenames.auto.gni

@@ -86,6 +86,7 @@ auto_filenames = {
     "docs/api/structures/notification-action.md",
     "docs/api/structures/point.md",
     "docs/api/structures/printer-info.md",
+    "docs/api/structures/process-memory-info.md",
     "docs/api/structures/process-metric.md",
     "docs/api/structures/product.md",
     "docs/api/structures/rectangle.md",

filenames.gni

@@ -42,6 +42,7 @@ filenames = {
     "lib/browser/guest-window-manager.js",
     "lib/browser/init.ts",
     "lib/browser/ipc-main-internal-utils.ts",
+    "lib/browser/ipc-main-creator.ts",
     "lib/browser/ipc-main-internal.ts",
     "lib/browser/navigation-controller.js",
     "lib/browser/objects-registry.js",

lib/browser/api/ipc-main.ts

@@ -1,8 +1,3 @@
-import { EventEmitter } from 'events'
+import { createIndependentIpcMain } from '@electron/internal/browser/ipc-main-creator'
 
-const emitter = new EventEmitter()
-
-// Do not throw exception when channel name is "error".
-emitter.on('error', () => {})
-
-export default emitter
+export default createIndependentIpcMain()

lib/browser/ipc-main-creator.ts

@@ -0,0 +1,49 @@
+import {
+  EventEmitter
+} from 'events'
+
+enum IpcMainHeirachy {
+  ROOT = 'ROOT',
+  SCOPED = 'SCOPED',
+}
+
+export const createIndependentIpcMain = () => {
+  const senderScoped = new Map < number,
+    IpcMain >()
+
+  class IpcMain extends EventEmitter implements Electron.IpcMain {
+    constructor (private heirachy: IpcMainHeirachy) {
+      super()
+      // Do not throw exception when channel name is "error".
+      this.on('error', () => {})
+    }
+
+    getScopedToSender (webContents: Electron.WebContents) {
+      const senderId = webContents.id
+      let scoped = senderScoped.get(senderId)
+      if (!scoped) {
+        // Store based on senderId here and don't persist the webContents to avoid it leaking
+        scoped = new IpcMain(IpcMainHeirachy.SCOPED)
+        senderScoped.set(senderId, scoped)
+      }
+      return scoped
+    }
+
+    emit (channel: string, event: Electron.IpcMainEvent, ...args: any[]): boolean {
+      let handled = false
+      // If this is the root instance of IpcMain and we have an event with a valid sender
+      // we should try emit the event on the scoped IpcMain instance
+      if (this.heirachy === IpcMainHeirachy.ROOT && event && event.sender && event.sender.id) {
+        const scoped = senderScoped.get(event.sender.id)
+        if (scoped) {
+          handled = scoped.emit(channel, event, ...args) || handled
+        }
+      }
+      handled = super.emit(channel, event, ...args) || handled
+      return handled
+    }
+  }
+
+  const ipcMain = new IpcMain(IpcMainHeirachy.ROOT)
+  return ipcMain
+}

lib/browser/ipc-main-internal.ts

@@ -1,8 +1,3 @@
-import { EventEmitter } from 'events'
+import { createIndependentIpcMain } from '@electron/internal/browser/ipc-main-creator'
 
-const emitter = new EventEmitter()
-
-// Do not throw exception when channel name is "error".
-emitter.on('error', () => {})
-
-export const ipcMainInternal = emitter as ElectronInternal.IpcMainInternal
+export const ipcMainInternal = createIndependentIpcMain() as ElectronInternal.IpcMainInternal