fix(service-worker): ignore invalid `only-if-cached` requests (#22883)

Under some circumstances (possibly related to opening Chrome DevTools),
requests are made with `cache: 'only-if-cached'` and `mode: 'no-cors'`.
These request will eventually fail, because `only-if-cached` is only
allowed to be used with `mode: 'same-origin'`.
This is likely a bug in Chrome DevTools.

This commit avoids errors related to such requests by not handling them.

Fixes #22362

PR Close #22883

packages/service-worker/worker/src/driver.ts

@@ -94,6 +94,12 @@ export class Driver implements Debuggable, UpdateSource {
    */
   private scheduledNavUpdateCheck: boolean = false;
 
+  /**
+   * Keep track of whether we have logged an invalid `only-if-cached` request.
+   * (See `.onFetch()` for details.)
+   */
+  private loggedInvalidOnlyIfCachedRequest: boolean = false;
+
   /**
    * A scheduler which manages a queue of tasks that need to be executed when the SW is
    * not doing any other work (not processing any other requests).
@@ -156,12 +162,13 @@ export class Driver implements Debuggable, UpdateSource {
    * asynchronous execution that eventually resolves for respondWith() and waitUntil().
    */
   private onFetch(event: FetchEvent): void {
+    const req = event.request;
+
     // The only thing that is served unconditionally is the debug page.
-    if (this.adapter.parseUrl(event.request.url, this.scope.registration.scope).path ===
-        '/ngsw/state') {
+    if (this.adapter.parseUrl(req.url, this.scope.registration.scope).path === '/ngsw/state') {
       // Allow the debugger to handle the request, but don't affect SW state in any
       // other way.
-      event.respondWith(this.debugger.handleFetch(event.request));
+      event.respondWith(this.debugger.handleFetch(req));
       return;
     }
 
@@ -177,6 +184,24 @@ export class Driver implements Debuggable, UpdateSource {
       return;
     }
 
+    // When opening DevTools in Chrome, a request is made for the current URL (and possibly related
+    // resources, e.g. scripts) with `cache: 'only-if-cached'` and `mode: 'no-cors'`. These request
+    // will eventually fail, because `only-if-cached` is only allowed to be used with
+    // `mode: 'same-origin'`.
+    // This is likely a bug in Chrome DevTools. Avoid handling such requests.
+    // (See also https://github.com/angular/angular/issues/22362.)
+    // TODO(gkalpak): Remove once no longer necessary (i.e. fixed in Chrome DevTools).
+    if ((req.cache as string) === 'only-if-cached' && req.mode !== 'same-origin') {
+      // Log the incident only the first time it happens, to avoid spamming the logs.
+      if (!this.loggedInvalidOnlyIfCachedRequest) {
+        this.loggedInvalidOnlyIfCachedRequest = true;
+        this.debugger.log(
+            `Ignoring invalid request: 'only-if-cached' can be set only with 'same-origin' mode`,
+            `Driver.fetch(${req.url}, cache: ${req.cache}, mode: ${req.mode})`);
+      }
+      return;
+    }
+
     // Past this point, the SW commits to handling the request itself. This could still
     // fail (and result in `state` being set to `SAFE_MODE`), but even in that case the
     // SW will still deliver a response.
@@ -611,8 +636,8 @@ export class Driver implements Debuggable, UpdateSource {
    * offline (detected as response status 504).
    */
   private async fetchLatestManifest(ignoreOfflineError?: false): Promise<Manifest>;
-  private async fetchLatestManifest(ignoreOfflineError: true): Promise<Manifest | null>;
-  private async fetchLatestManifest(ignoreOfflineError = false): Promise<Manifest | null> {
+  private async fetchLatestManifest(ignoreOfflineError: true): Promise<Manifest|null>;
+  private async fetchLatestManifest(ignoreOfflineError = false): Promise<Manifest|null> {
     const res =
         await this.safeFetch(this.adapter.newRequest('ngsw.json?ngsw-cache-bust=' + Math.random()));
     if (!res.ok) {

packages/service-worker/worker/test/happy_spec.ts

@@ -708,6 +708,15 @@ const manifestUpdateHash = sha1(JSON.stringify(manifestUpdate));
 
         expect(driver.state).toEqual(DriverReadyState.EXISTING_CLIENTS_ONLY);
       });
+
+      async_it('ignores invalid `only-if-cached` requests ', async() => {
+        const requestFoo = (cache: RequestCache | 'only-if-cached', mode: RequestMode) =>
+            makeRequest(scope, '/foo.txt', undefined, {cache, mode});
+
+        expect(await requestFoo('default', 'no-cors')).toBe('this is foo');
+        expect(await requestFoo('only-if-cached', 'same-origin')).toBe('this is foo');
+        expect(await requestFoo('only-if-cached', 'no-cors')).toBeNull();
+      });
     });
   });
 })();

packages/service-worker/worker/testing/fetch.ts

@@ -110,6 +110,9 @@ export class MockRequest extends MockBody implements Request {
         Object.keys(headers).forEach(header => { this.headers.set(header, headers[header]); });
       }
     }
+    if (init.cache !== undefined) {
+      this.cache = init.cache;
+    }
     if (init.mode !== undefined) {
       this.mode = init.mode;
     }