WebviewPostMessageStream

app/components/Views/Wallet/WebviewExecutionService.ts

@@ -0,0 +1,107 @@
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-nocheck
+import {
+  BasePostMessageStream,
+  Job,
+  AbstractExecutionService,
+  ExecutionServiceArgs,
+} from '@metamask/snap-controllers';
+import snapsState from '../../../core/SnapsState';
+
+type IframeExecutionEnvironmentServiceArgs = {
+  iframeUrl: URL;
+} & ExecutionServiceArgs;
+
+export default class WebviewExecutionService extends AbstractExecutionService<Window> {
+  public iframeUrl: URL;
+
+  constructor({
+    iframeUrl,
+    messenger,
+    setupSnapProvider,
+  }: IframeExecutionEnvironmentServiceArgs) {
+    super({
+      messenger,
+      setupSnapProvider,
+    });
+    this.iframeUrl = iframeUrl;
+  }
+
+  protected terminateJob(jobWrapper: Job<Window>): void {
+    // eslint-disable-next-line no-console
+    console.log('TERMINATE JOB----', jobWrapper);
+    // Send message to webview to remove certain iframe
+    //document.getElementById(jobWrapper.id)?.remove();
+  }
+
+  protected async initEnvStream(jobId: string): Promise<{
+    worker;
+    stream: BasePostMessageStream;
+  }> {
+    // eslint-disable-next-line no-console
+    console.log('------------INIT ENV STREAM----', jobId);
+    const iframeWindow = snapsState.webview;
+    const stream = snapsState.stream;
+
+    return { worker: iframeWindow, stream };
+  }
+
+  /**
+   * Creates the iframe to be used as the execution environment. This may run
+   * forever if the iframe never loads, but the promise should be wrapped in
+   * an initialization timeout in the SnapController.
+   *
+   * @param uri - The iframe URI.
+   * @param jobId - The job id.
+   * @returns A promise that resolves to the contentWindow of the iframe.
+   */
+  private async createWindow(uri: string, jobId: string): Promise<Window> {
+    return new Promise((resolve, reject) => {
+      const iframe = document.createElement('iframe');
+      // The order of operations appears to matter for everything except this
+      // attribute. We may as well set it here.
+      iframe.setAttribute('id', jobId);
+
+      // In the past, we've had problems that appear to be symptomatic of the
+      // iframe firing the `load` event before its scripts are actually loaded,
+      // which has prevented snaps from executing properly. Therefore, we set
+      // the `src` attribute and append the iframe to the DOM before attaching
+      // the `load` listener.
+      //
+      // `load` should only fire when "all dependent resources" have been
+      // loaded, which includes scripts.
+      //
+      // MDN article for `load` event: https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event
+      // Re: `load` firing twice: https://stackoverflow.com/questions/10781880/dynamically-created-iframe-triggers-onload-event-twice/15880489#15880489
+      iframe.setAttribute('src', uri);
+      document.body.appendChild(iframe);
+
+      iframe.addEventListener('load', () => {
+        if (iframe.contentWindow) {
+          resolve(iframe.contentWindow);
+        } else {
+          // We don't know of a case when this would happen, but better to fail
+          // fast if it does.
+          reject(
+            new Error(
+              `iframe.contentWindow not present on load for job "${jobId}".`,
+            ),
+          );
+        }
+      });
+
+      // We need to set the sandbox attribute after appending the iframe to the
+      // DOM, otherwise errors in the iframe will not be propagated via `error`
+      // and `unhandledrejection` events, and we cannot catch and handle them.
+      // We wish we knew why this was the case.
+      //
+      // We set this property after adding the `load` listener because it
+      // appears to work dependably. ¯\_(ツ)_/¯
+      //
+      // We apply this property as a principle of least authority (POLA)
+      // measure.
+      // Ref: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox
+      iframe.setAttribute('sandbox', 'allow-scripts');
+    });
+  }
+}