Handlebars sandbox (#612)

* Set up template renderer proxy

* Use proxy

* Remove unused handlebars script tags

* Update manifest

4 files changed, 258 insertions, 2 deletions

diff --git a/ext/bg/js/settings/anki-templates-controller.js b/ext/bg/js/settings/anki-templates-controller.js
index c53e4553..c980bfa2 100644
--- a/ext/bg/js/settings/anki-templates-controller.js
+++ b/ext/bg/js/settings/anki-templates-controller.js
@@ -17,7 +17,7 @@
 
 /* global
  * AnkiNoteBuilder
- * TemplateRenderer
+ * TemplateRendererProxy
  * api
  */
 
@@ -28,7 +28,7 @@ class AnkiTemplatesController {
         this._cachedDefinitionValue = null;
         this._cachedDefinitionText = null;
         this._defaultFieldTemplates = null;
-        this._templateRenderer = new TemplateRenderer();
+        this._templateRenderer = new TemplateRendererProxy();
     }
 
     async prepare() {
diff --git a/ext/bg/js/template-renderer-frame-api.js b/ext/bg/js/template-renderer-frame-api.js
new file mode 100644
index 00000000..7668e176
--- /dev/null
+++ b/ext/bg/js/template-renderer-frame-api.js
@@ -0,0 +1,76 @@
+/*
+ * 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 TemplateRendererFrameApi {
+    constructor(templateRenderer) {
+        this._templateRenderer = templateRenderer;
+        this._windowMessageHandlers = new Map([
+            ['renderHandlebarsTemplate', {async: true, handler: this._onRenderHandlebarsTemplate.bind(this)}]
+        ]);
+    }
+
+    prepare() {
+        window.addEventListener('message', this._onWindowMessage.bind(this), false);
+    }
+
+    _onWindowMessage(e) {
+        const {source, data: {action, params, id}} = e;
+        const messageHandler = this._windowMessageHandlers.get(action);
+        if (typeof messageHandler === 'undefined') { return; }
+
+        this._onWindowMessageInner(messageHandler, action, params, source, id);
+    }
+
+    async _onWindowMessageInner({handler, async}, action, params, source, id) {
+        let response;
+        try {
+            let result = handler(params);
+            if (async) {
+                result = await result;
+            }
+            response = {result};
+        } catch (error) {
+            response = {error: this._errorToJson(error)};
+        }
+
+        if (typeof id === undefined) { return; }
+        source.postMessage({action: `${action}.response`, params: response, id}, '*');
+    }
+
+    async _onRenderHandlebarsTemplate({template, data, marker}) {
+        return await this._templateRenderer.render(template, data, marker);
+    }
+
+    _errorToJson(error) {
+        try {
+            if (error !== null && typeof error === 'object') {
+                return {
+                    name: error.name,
+                    message: error.message,
+                    stack: error.stack,
+                    data: error.data
+                };
+            }
+        } catch (e) {
+            // NOP
+        }
+        return {
+            value: error,
+            hasValue: true
+        };
+    }
+}
diff --git a/ext/bg/js/template-renderer-frame-main.js b/ext/bg/js/template-renderer-frame-main.js
new file mode 100644
index 00000000..7d3e1493
--- /dev/null
+++ b/ext/bg/js/template-renderer-frame-main.js
@@ -0,0 +1,27 @@
+/*
+ * 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/>.
+ */
+
+/* globals
+ * TemplateRenderer
+ * TemplateRendererFrameApi
+ */
+
+(() => {
+    const templateRenderer = new TemplateRenderer();
+    const api = new TemplateRendererFrameApi(templateRenderer);
+    api.prepare();
+})();
diff --git a/ext/bg/js/template-renderer-proxy.js b/ext/bg/js/template-renderer-proxy.js
new file mode 100644
index 00000000..f08efdd6
--- /dev/null
+++ b/ext/bg/js/template-renderer-proxy.js
@@ -0,0 +1,153 @@
+/*
+ * 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 TemplateRendererProxy {
+    constructor() {
+        this._frame = null;
+        this._frameNeedsLoad = true;
+        this._frameLoading = false;
+        this._frameLoadPromise = null;
+        this._frameUrl = chrome.runtime.getURL('/bg/template-renderer.html');
+        this._invocations = new Set();
+    }
+
+    async render(template, data, marker) {
+        await this._prepareFrame();
+        return await this._invoke('renderHandlebarsTemplate', {template, data, marker});
+    }
+
+    // Private
+
+    async _prepareFrame() {
+        if (this._frame === null) {
+            this._frame = document.createElement('iframe');
+            this._frame.addEventListener('load', this._onFrameLoad.bind(this), false);
+            const style = this._frame.style;
+            style.opacity = '0';
+            style.width = '0';
+            style.height = '0';
+            style.position = 'absolute';
+        }
+        if (this._frameNeedsLoad) {
+            this._frameNeedsLoad = false;
+            this._frameLoading = true;
+            this._frameLoadPromise = this._loadFrame(this._frame, this._frameUrl)
+                .finally(() => { this._frameLoading = false; });
+        }
+        await this._frameLoadPromise;
+    }
+
+    _loadFrame(frame, url, timeout=5000) {
+        return new Promise((resolve, reject) => {
+            let ready = false;
+            const cleanup = () => {
+                frame.removeEventListener('load', onLoad, false);
+                if (timer !== null) {
+                    clearTimeout(timer);
+                    timer = null;
+                }
+            };
+            const onLoad = () => {
+                if (!ready) { return; }
+                cleanup();
+                resolve();
+            };
+
+            let timer = setTimeout(() => {
+                cleanup();
+                reject(new Error('Timeout'));
+            }, timeout);
+
+            frame.removeAttribute('src');
+            frame.removeAttribute('srcdoc');
+            frame.addEventListener('load', onLoad, false);
+            try {
+                document.body.appendChild(frame);
+                ready = true;
+                frame.contentDocument.location.href = url;
+            } catch (e) {
+                cleanup();
+                reject(e);
+            }
+        });
+    }
+
+    _invoke(action, params, timeout=null) {
+        return new Promise((resolve, reject) => {
+            const frameWindow = (this._frame !== null ? this._frame.contentWindow : null);
+            if (frameWindow === null) {
+                reject(new Error('Frame not set up'));
+                return;
+            }
+
+            const id = generateId(16);
+            const invocation = {
+                cancel: () => {
+                    cleanup();
+                    reject(new Error('Terminated'));
+                }
+            };
+
+            const cleanup = () => {
+                this._invocations.delete(invocation);
+                window.removeEventListener('message', onMessage, false);
+                if (timer !== null) {
+                    clearTimeout(timer);
+                    timer = null;
+                }
+            };
+            const onMessage = (e) => {
+                if (
+                    e.source !== frameWindow ||
+                    e.data.id !== id ||
+                    e.data.action !== `${action}.response`
+                ) {
+                    return;
+                }
+
+                const response = e.data.params;
+                cleanup();
+                const {error} = response;
+                if (error) {
+                    reject(jsonToError(error));
+                } else {
+                    resolve(response.result);
+                }
+            };
+
+            let timer = (typeof timeout === 'number' ? setTimeout(() => {
+                cleanup();
+                reject(new Error('Timeout'));
+            }, timeout) : null);
+
+            this._invocations.add(invocation);
+
+            window.addEventListener('message', onMessage, false);
+            frameWindow.postMessage({action, params, id}, '*');
+        });
+    }
+
+    _onFrameLoad() {
+        if (this._frameLoading) { return; }
+        this._frameNeedsLoad = true;
+
+        for (const invocation of this._invocations) {
+            invocation.cancel();
+        }
+        this._invocations.clear();
+    }
+}