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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This @file implements the parent side of Conduits, an abstraction over
+ * Fission IPC for extension Contexts, API managers, Ports/Messengers, and
+ * other types of "subjects" participating in implementation of extension APIs.
+ *
+ * Additionally, knowledge about conduits from all child processes is gathered
+ * here, and used together with the full CanonicalBrowsingContext tree to route
+ * IPC messages and queries directly to the right subjects.
+ *
+ * Each Conduit is tied to one subject, attached to a ConduitAddress descriptor,
+ * and exposes an API for sending/receiving via an actor, or multiple actors in
+ * case of the parent process.
+ *
+ * @typedef {number|string} ConduitID
+ *
+ * @typedef {object} ConduitAddress
+ * @property {ConduitID} id Globally unique across all processes.
+ * @property {string[]} [recv]
+ * @property {string[]} [send]
+ * @property {string[]} [query]
+ * @property {string[]} [cast]
+ * Lists of recvX, sendX, queryX and castX methods this subject will use.
+ *
+ * @typedef {"messenger"|"port"|"tab"} BroadcastKind
+ * Kinds of broadcast targeting filters.
+ *
+ * @example
+ * ```js
+ * {
+ *    init(actor) {
+ *      this.conduit = actor.openConduit(this, {
+ *        id: this.id,
+ *        recv: ["recvAddNumber"],
+ *        send: ["sendNumberUpdate"],
+ *      });
+ *    },
+ *
+ *    recvAddNumber({ num }, { actor, sender }) {
+ *      num += 1;
+ *      this.conduit.sendNumberUpdate(sender.id, { num });
+ *    }
+ * }
+ * ```
+ */
+
+import { BaseConduit } from "resource://gre/modules/ConduitsChild.sys.mjs";
+import { ExtensionUtils } from "resource://gre/modules/ExtensionUtils.sys.mjs";
+import { WebNavigationFrames } from "resource://gre/modules/WebNavigationFrames.sys.mjs";
+
+const { DefaultWeakMap, ExtensionError } = ExtensionUtils;
+
+const BATCH_TIMEOUT_MS = 250;
+const ADDON_ENV = new Set(["addon_child", "devtools_child"]);
+
+/**
+ * Internal, keeps track of all parent and remote (child) conduits.
+ */
+const Hub = {
+  /** @type {Map<ConduitID, ConduitAddress>} Info about all child conduits. */
+  remotes: new Map(),
+
+  /** @type {Map<ConduitID, BroadcastConduit>} All open parent conduits. */
+  conduits: new Map(),
+
+  /** @type {Map<string, BroadcastConduit>} Parent conduits by recvMethod. */
+  byMethod: new Map(),
+
+  /** @type {WeakMap<ConduitsParent, Set<ConduitAddress>>} Conduits by actor. */
+  byActor: new DefaultWeakMap(() => new Set()),
+
+  /** @type {Map<string, BroadcastConduit>} */
+  reportOnClosed: new Map(),
+
+  /**
+   * Save info about a new parent conduit, register it as a global listener.
+   *
+   * @param {BroadcastConduit} conduit
+   */
+  openConduit(conduit) {
+    this.conduits.set(conduit.id, conduit);
+    for (let name of conduit.address.recv || []) {
+      if (this.byMethod.get(name)) {
+        // For now, we only allow one parent conduit handling each recv method.
+        throw new Error(`Duplicate BroadcastConduit method name recv${name}`);
+      }
+      this.byMethod.set(name, conduit);
+    }
+  },
+
+  /**
+   * Cleanup.
+   *
+   * @param {BroadcastConduit} conduit
+   */
+  closeConduit({ id, address }) {
+    this.conduits.delete(id);
+    for (let name of address.recv || []) {
+      this.byMethod.remove(name);
+    }
+  },
+
+  /**
+   * Confirm that a remote conduit comes from an extension background
+   * service worker.
+   *
+   * @see ExtensionPolicyService::CheckParentFrames
+   * @param {ConduitAddress} remote
+   * @returns {boolean}
+   */
+  verifyWorkerEnv({ actor, extensionId, workerScriptURL }) {
+    const addonPolicy = WebExtensionPolicy.getByID(extensionId);
+    if (!addonPolicy) {
+      throw new Error(`No WebExtensionPolicy found for ${extensionId}`);
+    }
+    if (actor.manager.remoteType !== addonPolicy.extension.remoteType) {
+      throw new Error(
+        `Bad ${extensionId} process: ${actor.manager.remoteType}`
+      );
+    }
+    if (!addonPolicy.isManifestBackgroundWorker(workerScriptURL)) {
+      throw new Error(
+        `Bad ${extensionId} background service worker script url: ${workerScriptURL}`
+      );
+    }
+    return true;
+  },
+
+  /**
+   * Confirm that a remote conduit comes from an extension page or
+   * an extension background service worker.
+   *
+   * @see ExtensionPolicyService::CheckParentFrames
+   * @param {ConduitAddress} remote
+   * @returns {boolean}
+   */
+  verifyEnv({ actor, envType, extensionId, ...rest }) {
+    if (!extensionId || !ADDON_ENV.has(envType)) {
+      return false;
+    }
+
+    // ProcessConduit related to a background service worker context.
+    if (actor.manager && actor.manager instanceof Ci.nsIDOMProcessParent) {
+      return this.verifyWorkerEnv({ actor, envType, extensionId, ...rest });
+    }
+
+    let windowGlobal = actor.manager;
+
+    while (windowGlobal) {
+      let { browsingContext: bc, documentPrincipal: prin } = windowGlobal;
+
+      if (prin.addonId !== extensionId) {
+        throw new Error(`Bad ${extensionId} principal: ${prin.URI.spec}`);
+      }
+      if (bc.currentRemoteType !== prin.addonPolicy.extension.remoteType) {
+        throw new Error(`Bad ${extensionId} process: ${bc.currentRemoteType}`);
+      }
+
+      if (!bc.parent) {
+        return true;
+      }
+      windowGlobal = bc.embedderWindowGlobal;
+    }
+    throw new Error(`Missing WindowGlobalParent for ${extensionId}`);
+  },
+
+  /**
+   * Fill in common address fields knowable from the parent process.
+   *
+   * @param {ConduitAddress} address
+   * @param {ConduitsParent} actor
+   */
+  fillInAddress(address, actor) {
+    address.actor = actor;
+    address.verified = this.verifyEnv(address);
+    if (JSWindowActorParent.isInstance(actor)) {
+      address.frameId = WebNavigationFrames.getFrameId(actor.browsingContext);
+      address.url = actor.manager.documentURI?.spec;
+    } else {
+      // Background service worker contexts do not have an associated frame
+      // and there is no browsingContext to retrieve the expected url from.
+      //
+      // WorkerContextChild sent in the address part of the ConduitOpened request
+      // the worker script URL as address.workerScriptURL, and so we can use that
+      // as the address.url too.
+      address.frameId = -1;
+      address.url = address.workerScriptURL;
+    }
+  },
+
+  /**
+   * Save info about a new remote conduit.
+   *
+   * @param {ConduitAddress} address
+   * @param {ConduitsParent} actor
+   */
+  recvConduitOpened(address, actor) {
+    this.fillInAddress(address, actor);
+    this.remotes.set(address.id, address);
+    this.byActor.get(actor).add(address);
+  },
+
+  /**
+   * Notifies listeners and cleans up after the remote conduit is closed.
+   *
+   * @param {ConduitAddress} remote
+   */
+  recvConduitClosed(remote) {
+    this.remotes.delete(remote.id);
+    this.byActor.get(remote.actor).delete(remote);
+
+    remote.actor = null;
+    for (let [key, conduit] of Hub.reportOnClosed.entries()) {
+      if (remote[key]) {
+        conduit.subject.recvConduitClosed(remote);
+      }
+    }
+  },
+
+  /**
+   * Close all remote conduits when the actor goes away.
+   *
+   * @param {ConduitsParent} actor
+   */
+  actorClosed(actor) {
+    for (let remote of this.byActor.get(actor)) {
+      // When a Port is closed, we notify the other side, but it might share
+      // an actor, so we shouldn't sendQeury() in that case (see bug 1623976).
+      this.remotes.delete(remote.id);
+    }
+    for (let remote of this.byActor.get(actor)) {
+      this.recvConduitClosed(remote);
+    }
+    this.byActor.delete(actor);
+  },
+};
+
+/**
+ * Parent side conduit, registers as a global listeners for certain messages,
+ * and can target specific child conduits when sending.
+ */
+export class BroadcastConduit extends BaseConduit {
+  /**
+   * @param {object} subject
+   * @param {ConduitAddress} address
+   */
+  constructor(subject, address) {
+    super(subject, address);
+
+    // Create conduit.castX() bidings.
+    for (let name of address.cast || []) {
+      this[`cast${name}`] = this._cast.bind(this, name);
+    }
+
+    // Wants to know when conduits with a specific attribute are closed.
+    // `subject.recvConduitClosed(address)` method will be called.
+    if (address.reportOnClosed) {
+      Hub.reportOnClosed.set(address.reportOnClosed, this);
+    }
+
+    this.open = true;
+    Hub.openConduit(this);
+  }
+
+  /**
+   * Internal, sends a message to a specific conduit, used by sendX stubs.
+   *
+   * @param {string} method
+   * @param {boolean} query
+   * @param {ConduitID} target
+   * @param {object?} arg
+   * @returns {Promise<any>}
+   */
+  _send(method, query, target, arg = {}) {
+    if (!this.open) {
+      throw new Error(`send${method} on closed conduit ${this.id}`);
+    }
+
+    let sender = this.id;
+    let { actor } = Hub.remotes.get(target);
+
+    if (method === "RunListener" && arg.path.startsWith("webRequest.")) {
+      return actor.batch(method, { target, arg, query, sender });
+    }
+    return super._send(method, query, actor, { target, arg, query, sender });
+  }
+
+  /**
+   * Broadcasts a method call to all conduits of kind that satisfy filtering by
+   * kind-specific properties from arg, returns an array of response promises.
+   *
+   * @param {string} method
+   * @param {BroadcastKind} kind
+   * @param {object} arg
+   * @returns {Promise[]}
+   */
+  _cast(method, kind, arg) {
+    let filters = {
+      // Target Ports by portId and side (connect caller/onConnect receiver).
+      port: remote =>
+        remote.portId === arg.portId &&
+        (arg.source == null || remote.source === arg.source),
+
+      // Target Messengers in extension pages by extensionId and envType.
+      messenger: r =>
+        r.verified &&
+        r.id !== arg.sender.contextId &&
+        r.extensionId === arg.extensionId &&
+        r.recv.includes(method) &&
+        // TODO: Bug 1453343 - get rid of this:
+        (r.envType === "addon_child" || arg.sender.envType !== "content_child"),
+
+      // Target Messengers by extensionId, tabId (topBC) and frameId.
+      tab: remote =>
+        remote.extensionId === arg.extensionId &&
+        remote.actor.manager.browsingContext?.top.id === arg.topBC &&
+        (arg.frameId == null || remote.frameId === arg.frameId) &&
+        remote.recv.includes(method),
+
+      // Target Messengers by extensionId.
+      extension: remote => remote.instanceId === arg.instanceId,
+    };
+
+    let targets = Array.from(Hub.remotes.values()).filter(filters[kind]);
+    let promises = targets.map(c => this._send(method, true, c.id, arg));
+
+    return arg.firstResponse
+      ? this._raceResponses(promises)
+      : Promise.allSettled(promises);
+  }
+
+  /**
+   * Custom Promise.race() function that ignores certain resolutions and errors.
+   *
+   * @param {Promise<response>[]} promises
+   * @returns {Promise<response?>}
+   */
+  _raceResponses(promises) {
+    return new Promise((resolve, reject) => {
+      let result;
+      promises.map(p =>
+        p
+          .then(value => {
+            if (value.response) {
+              // We have an explicit response, resolve immediately.
+              resolve(value);
+            } else if (value.received) {
+              // Message was received, but no response.
+              // Resolve with this only if there is no other explicit response.
+              result = value;
+            }
+          })
+          .catch(err => {
+            // Forward errors that are exposed to extension, but ignore
+            // internal errors such as actor destruction and DataCloneError.
+            if (err instanceof ExtensionError || err?.mozWebExtLocation) {
+              reject(err);
+            } else {
+              Cu.reportError(err);
+            }
+          })
+      );
+      // Ensure resolving when there are no responses.
+      Promise.allSettled(promises).then(() => resolve(result));
+    });
+  }
+
+  async close() {
+    this.open = false;
+    Hub.closeConduit(this);
+  }
+}
+
+/**
+ * Implements the parent side of the Conduits actor.
+ */
+export class ConduitsParent extends JSWindowActorParent {
+  constructor() {
+    super();
+    this.batchData = [];
+    this.batchPromise = null;
+    this.batchResolve = null;
+    this.timerActive = false;
+  }
+
+  /**
+   * Group webRequest events to send them as a batch, reducing IPC overhead.
+   *
+   * @param {string} name
+   * @param {MessageData} data
+   * @returns {Promise<object>}
+   */
+  batch(name, data) {
+    let pos = this.batchData.length;
+    this.batchData.push(data);
+
+    let sendNow = idleDispatch => {
+      if (this.batchData.length && this.manager) {
+        this.batchResolve(this.sendQuery(name, this.batchData));
+      } else {
+        this.batchResolve([]);
+      }
+      this.batchData = [];
+      this.timerActive = !idleDispatch;
+    };
+
+    if (!pos) {
+      this.batchPromise = new Promise(r => (this.batchResolve = r));
+      if (!this.timerActive) {
+        ChromeUtils.idleDispatch(sendNow, { timeout: BATCH_TIMEOUT_MS });
+        this.timerActive = true;
+      }
+    }
+
+    if (data.arg.urgentSend) {
+      // If this is an urgent blocking event, run this batch right away.
+      sendNow(false);
+    }
+
+    return this.batchPromise.then(results => results[pos]);
+  }
+
+  /**
+   * JSWindowActor method, routes the message to the target subject.
+   *
+   * @param {object} options
+   * @param {string} options.name
+   * @param {MessageData} options.data
+   * @returns {Promise?}
+   */
+  async receiveMessage({ name, data: { arg, query, sender } }) {
+    if (name === "ConduitOpened") {
+      return Hub.recvConduitOpened(arg, this);
+    }
+
+    sender = Hub.remotes.get(sender);
+    if (!sender || sender.actor !== this) {
+      throw new Error(`Unknown sender or wrong actor for recv${name}`);
+    }
+
+    if (name === "ConduitClosed") {
+      return Hub.recvConduitClosed(sender);
+    }
+
+    let conduit = Hub.byMethod.get(name);
+    if (!conduit) {
+      throw new Error(`Parent conduit for recv${name} not found`);
+    }
+
+    return conduit._recv(name, arg, { actor: this, query, sender });
+  }
+
+  /**
+   * JSWindowActor method, ensure cleanup.
+   */
+  didDestroy() {
+    Hub.actorClosed(this);
+  }
+}
+
+/**
+ * Parent side of the Conduits process actor.  Same code as JSWindowActor.
+ */
+export class ProcessConduitsParent extends JSProcessActorParent {
+  receiveMessage = ConduitsParent.prototype.receiveMessage;
+  willDestroy = ConduitsParent.prototype.willDestroy;
+  didDestroy = ConduitsParent.prototype.didDestroy;
+}