Cross frame communication (#531)

* Set up new cross-frame port connector

* Create classes for cross-frame API invocation with replies

* Remove event listeners on disconnect

2 files changed, 322 insertions, 0 deletions

diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index 20d31efc..8df4fd9d 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -163,6 +163,7 @@ class Backend {
                 chrome.tabs.onZoomChange.addListener(this._onZoomChange.bind(this));
             }
             chrome.runtime.onMessage.addListener(this.onMessage.bind(this));
+            chrome.runtime.onConnect.addListener(this._onConnect.bind(this));
 
             const options = this.getOptions(this.optionsContext);
             if (options.general.showGuide) {
@@ -236,6 +237,45 @@ class Backend {
         }
     }
 
+    _onConnect(port) {
+        try {
+            const match = /^background-cross-frame-communication-port-(\d+)$/.exec(`${port.name}`);
+            if (match === null) { return; }
+
+            const tabId = (port.sender && port.sender.tab ? port.sender.tab.id : null);
+            if (typeof tabId !== 'number') {
+                throw new Error('Port does not have an associated tab ID');
+            }
+            const senderFrameId = port.sender.frameId;
+            if (typeof tabId !== 'number') {
+                throw new Error('Port does not have an associated frame ID');
+            }
+            const targetFrameId = parseInt(match[1], 10);
+
+            let forwardPort = chrome.tabs.connect(tabId, {frameId: targetFrameId, name: `cross-frame-communication-port-${senderFrameId}`});
+
+            const cleanup = () => {
+                this.checkLastError(chrome.runtime.lastError);
+                if (forwardPort !== null) {
+                    forwardPort.disconnect();
+                    forwardPort = null;
+                }
+                if (port !== null) {
+                    port.disconnect();
+                    port = null;
+                }
+            };
+
+            port.onMessage.addListener((message) => { forwardPort.postMessage(message); });
+            forwardPort.onMessage.addListener((message) => { port.postMessage(message); });
+            port.onDisconnect.addListener(cleanup);
+            forwardPort.onDisconnect.addListener(cleanup);
+        } catch (e) {
+            port.disconnect();
+            yomichan.logError(e);
+        }
+    }
+
     _onClipboardText({text}) {
         this._onCommandSearch({mode: 'popup', query: text});
     }
diff --git a/ext/mixed/js/comm.js b/ext/mixed/js/comm.js
new file mode 100644
index 00000000..7787616e
--- /dev/null
+++ b/ext/mixed/js/comm.js
@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+class CrossFrameAPIPort extends EventDispatcher {
+    constructor(otherFrameId, port, messageHandlers) {
+        super();
+        this._otherFrameId = otherFrameId;
+        this._port = port;
+        this._messageHandlers = messageHandlers;
+        this._activeInvocations = new Map();
+        this._invocationId = 0;
+        this._eventListeners = new EventListenerCollection();
+    }
+
+    get otherFrameId() {
+        return this._otherFrameId;
+    }
+
+    prepare() {
+        this._eventListeners.addListener(this._port.onDisconnect, this._onDisconnect.bind(this));
+        this._eventListeners.addListener(this._port.onMessage, this._onMessage.bind(this));
+    }
+
+    invoke(action, params, ackTimeout, responseTimeout) {
+        return new Promise((resolve, reject) => {
+            if (this._port === null) {
+                reject(new Error('Port is disconnected'));
+                return;
+            }
+
+            const id = this._invocationId++;
+            const invocation = {id, resolve, reject, responseTimeout, ack: false, timer: null};
+            this._activeInvocations.set(id, invocation);
+
+            if (ackTimeout !== null) {
+                try {
+                    invocation.timer = setTimeout(() => this._onError(id, new Error('Timeout (ack)')), ackTimeout);
+                } catch (e) {
+                    this._onError(id, new Error('Failed to set timeout'));
+                    return;
+                }
+            }
+
+            try {
+                this._port.postMessage({type: 'invoke', id, data: {action, params}});
+            } catch (e) {
+                this._onError(id, e);
+            }
+        });
+    }
+
+    disconnect() {
+        this._onDisconnect();
+    }
+
+    // Private
+
+    _onDisconnect() {
+        if (this._port === null) { return; }
+        this._eventListeners.removeAllEventListeners();
+        this._port = null;
+        for (const id of this._activeInvocations.keys()) {
+            this._onError(id, new Error('Disconnected'));
+        }
+        this.trigger('disconnect', this);
+    }
+
+    _onMessage({type, id, data}) {
+        switch (type) {
+            case 'invoke':
+                this._onInvoke(id, data);
+                break;
+            case 'ack':
+                this._onAck(id);
+                break;
+            case 'result':
+                this._onResult(id, data);
+                break;
+        }
+    }
+
+    // Response handlers
+
+    _onAck(id) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') {
+            yomichan.logWarning(new Error(`Request ${id} not found for ack`));
+            return;
+        }
+
+        if (invocation.ack) {
+            this._onError(id, new Error(`Request ${id} already ack'd`));
+            return;
+        }
+
+        invocation.ack = true;
+
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+
+        const responseTimeout = invocation.responseTimeout;
+        if (responseTimeout !== null) {
+            try {
+                invocation.timer = setTimeout(() => this._onError(id, new Error('Timeout (response)')), responseTimeout);
+            } catch (e) {
+                this._onError(id, new Error('Failed to set timeout'));
+            }
+        }
+    }
+
+    _onResult(id, data) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') {
+            yomichan.logWarning(new Error(`Request ${id} not found`));
+            return;
+        }
+
+        if (!invocation.ack) {
+            this._onError(id, new Error(`Request ${id} not ack'd`));
+            return;
+        }
+
+        this._activeInvocations.delete(id);
+
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+
+        const error = data.error;
+        if (typeof error !== 'undefined') {
+            invocation.reject(jsonToError(error));
+        } else {
+            invocation.resolve(data.result);
+        }
+    }
+
+    _onError(id, error) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') { return; }
+
+        this._activeInvocations.delete(id);
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+        invocation.reject(error);
+    }
+
+    // Invocation
+
+    _onInvoke(id, {action, params}) {
+        const messageHandler = this._messageHandlers.get(action);
+        if (typeof messageHandler === 'undefined') {
+            this._sendError(id, new Error(`Unknown action: ${action}`));
+            return;
+        }
+
+        const {handler, async} = messageHandler;
+
+        this._sendAck(id);
+        if (async) {
+            this._invokeHandlerAsync(id, handler, params);
+        } else {
+            this._invokeHandler(id, handler, params);
+        }
+    }
+
+    _invokeHandler(id, handler, params) {
+        try {
+            const result = handler(params);
+            this._sendResult(id, result);
+        } catch (error) {
+            this._sendError(id, error);
+        }
+    }
+
+    async _invokeHandlerAsync(id, handler, params) {
+        try {
+            const result = await handler(params);
+            this._sendResult(id, result);
+        } catch (error) {
+            this._sendError(id, error);
+        }
+    }
+
+    _sendResponse(data) {
+        if (this._port === null) { return; }
+        try {
+            this._port.postMessage(data);
+        } catch (e) {
+            // NOP
+        }
+    }
+
+    _sendAck(id) {
+        this._sendResponse({type: 'ack', id});
+    }
+
+    _sendResult(id, result) {
+        this._sendResponse({type: 'result', id, data: {result}});
+    }
+
+    _sendError(id, error) {
+        this._sendResponse({type: 'result', id, data: {error: errorToJson(error)}});
+    }
+}
+
+class CrossFrameAPI {
+    constructor() {
+        this._ackTimeout = 3000; // 3 seconds
+        this._responseTimeout = 10000; // 10 seconds
+        this._commPorts = new Map();
+        this._messageHandlers = new Map();
+        this._onDisconnectBind = this._onDisconnect.bind(this);
+    }
+
+    prepare() {
+        chrome.runtime.onConnect.addListener(this._onConnect.bind(this));
+    }
+
+    async invoke(targetFrameId, action, params={}) {
+        const commPort = this._getOrCreateCommPort(targetFrameId);
+        return await commPort.invoke(action, params, this._ackTimeout, this._responseTimeout);
+    }
+
+    registerHandlers(messageHandlers) {
+        for (const [key, value] of messageHandlers) {
+            if (this._messageHandlers.has(key)) {
+                throw new Error(`Handler ${key} is already registered`);
+            }
+            this._messageHandlers.set(key, value);
+        }
+    }
+
+    _onConnect(port) {
+        const match = /^cross-frame-communication-port-(\d+)$/.exec(`${port.name}`);
+        if (match === null) { return; }
+
+        const otherFrameId = parseInt(match[1], 10);
+        this._setupCommPort(otherFrameId, port);
+    }
+
+    _onDisconnect(commPort) {
+        commPort.off('disconnect', this._onDisconnectBind);
+        this._commPorts.delete(commPort.otherFrameId);
+    }
+
+    _getOrCreateCommPort(otherFrameId) {
+        const commPort = this._commPorts.get(otherFrameId);
+        return (typeof commPort !== 'undefined' ? commPort : this._createCommPort(otherFrameId));
+    }
+
+    _createCommPort(otherFrameId) {
+        const port = chrome.runtime.connect(null, {name: `background-cross-frame-communication-port-${otherFrameId}`});
+        return this._setupCommPort(otherFrameId, port);
+    }
+
+    _setupCommPort(otherFrameId, port) {
+        const commPort = new CrossFrameAPIPort(otherFrameId, port, this._messageHandlers);
+        this._commPorts.set(otherFrameId, commPort);
+        commPort.prepare();
+        commPort.on('disconnect', this._onDisconnectBind);
+        return commPort;
+    }
+}