Limit and fix communication between frames

src/annotator/cross-frame.js

@@ -61,8 +61,9 @@ export class CrossFrame {
     };
 
     // Initiate connection to the sidebar.
-    const onDiscoveryCallback = (source, origin, token) =>
+    const onDiscoveryCallback = (source, origin, token) => {
       bridge.createChannel(source, origin, token);
+    };
     discovery.startDiscovery(onDiscoveryCallback);
     frameObserver.observe(injectIntoFrame, iframeUnloaded);
 

src/annotator/guest.js

@@ -164,6 +164,7 @@ export default class Guest {
     // Setup connection to sidebar.
     this.crossframe = new CrossFrame(this.element, {
       config,
+      server: config.server,
       on: (event, handler) => this._emitter.subscribe(event, handler),
       emit: (event, ...args) => this._emitter.publish(event, ...args),
     });

src/annotator/index.js

@@ -41,6 +41,9 @@ function init() {
     // frame context belongs to hypothesis.
     // Needs to be a global property that's set.
     window_.__hypothesis_frame = true;
+    config.server = false;
+  } else {
+    config.server = true;
   }
 
   // Load the PDF anchoring/metadata integration.

src/shared/discovery.js

@@ -10,6 +10,8 @@
 
 import { ListenerCollection } from '../annotator/util/listener-collection';
 
+/** @typedef {import('../types/annotator').HypothesisWindow} HypothesisWindow */
+
 /**
  * Discovery finds frames in the current tab/window that can be annotated (the
  * "clients") or can fetch annotations from the backend (the "server").
@@ -34,7 +36,7 @@ import { ListenerCollection } from '../annotator/util/listener-collection';
  */
 export default class Discovery {
   /**
-   * @param {Window} target
+   * @param {HypothesisWindow} target
    * @param {object} [options]
    *   @param {boolean} [options.server]
    *   @param {string} [options.origin]
@@ -103,21 +105,24 @@ export default class Discovery {
   _beacon() {
     let beaconMessage;
     if (this.server) {
+      // `host` frame (frame where the client is initially loaded)
       beaconMessage = '__cross_frame_dhcp_offer';
     } else {
       beaconMessage = '__cross_frame_dhcp_discovery';
-    }
+      if (this.target.__hypothesis_frame) {
+        // Annotatable iframe(s) have a global `__hypothesis_frame` variable.
+
+        // Find the closest parent that is not an annotatable iframe.
+        /** @type {HypothesisWindow} */
+        let parent = this.target.parent;
+        while (parent.__hypothesis_frame) {
+          parent = this.target.parent;
+        }
 
-    // Perform a top-down, breadth-first traversal of frames in the current
-    // window and send messages to them.
-    const queue = [this.target.top];
-    while (queue.length > 0) {
-      const parent = /** @type {Window} */ (queue.shift());
-      if (parent !== this.target) {
-        parent.postMessage(beaconMessage, this.origin);
-      }
-      for (let i = 0; i < parent.frames.length; i++) {
-        queue.push(parent.frames[i]);
+        this.target.parent.postMessage(beaconMessage, this.origin);
+      } else {
+        // `sideframe` or `notebook`, iframes
+        this.target.parent.postMessage(beaconMessage, this.origin);
       }
     }
   }

src/sidebar/index.js

@@ -6,7 +6,7 @@ import * as rendererOptions from '../shared/renderer-options';
 import {
   startServer as startRPCServer,
   preStartServer as preStartRPCServer,
-} from './cross-origin-rpc.js';
+} from './cross-origin-rpc';
 import disableOpenerForExternalLinks from './util/disable-opener-for-external-links';
 import { fetchConfig } from './config/fetch-config';
 import * as sentry from './util/sentry';

src/sidebar/services/frame-sync.js

@@ -235,7 +235,7 @@ export class FrameSyncService {
       });
     };
 
-    const discovery = new Discovery(window, { server: true });
+    const discovery = new Discovery(window);
     discovery.startDiscovery(this._bridge.createChannel.bind(this._bridge));
     this._bridge.onConnect(addFrame);