Fix link previews for YouTube Music

Author: EvanHahn-Signal

ts/linkPreviews/linkPreviewFetch.ts

@@ -1,4 +1,4 @@
-// Copyright 2020 Signal Messenger, LLC
+// Copyright 2020-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { RequestInit, Response } from 'node-fetch';
@@ -13,6 +13,8 @@ import {
   MIMEType,
 } from '../types/MIME';
 
+const USER_AGENT = 'WhatsApp/2';
+
 const MAX_REQUEST_COUNT_WITH_REDIRECTS = 20;
 
 // Lifted from the `fetch` spec [here][0].
@@ -408,7 +410,7 @@ export async function fetchLinkPreviewMetadata(
     response = await fetchWithRedirects(fetchFn, href, {
       headers: {
         Accept: 'text/html,application/xhtml+xml',
-        'User-Agent': 'WhatsApp',
+        'User-Agent': USER_AGENT,
       },
       signal: abortSignal,
     });
@@ -504,7 +506,7 @@ export async function fetchLinkPreviewImage(
   try {
     response = await fetchWithRedirects(fetchFn, href, {
       headers: {
-        'User-Agent': 'WhatsApp',
+        'User-Agent': USER_AGENT,
       },
       size: MAX_IMAGE_CONTENT_LENGTH,
       signal: abortSignal,

ts/test-electron/linkPreviews/linkPreviewFetch_test.ts

@@ -1,4 +1,4 @@
-// Copyright 2020 Signal Messenger, LLC
+// Copyright 2020-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { assert } from 'chai';
@@ -143,7 +143,7 @@ describe('link preview fetching', () => {
       sinon.assert.notCalled(warn);
     });
 
-    it('sends "WhatsApp" as the User-Agent for compatibility', async () => {
+    it('sends WhatsApp as the User-Agent for compatibility', async () => {
       const fakeFetch = stub().resolves(makeResponse());
 
       await fetchLinkPreviewMetadata(
@@ -157,7 +157,7 @@ describe('link preview fetching', () => {
         'https://example.com',
         sinon.match({
           headers: {
-            'User-Agent': 'WhatsApp',
+            'User-Agent': 'WhatsApp/2',
           },
         })
       );
@@ -1273,7 +1273,7 @@ describe('link preview fetching', () => {
       );
     });
 
-    it('sends "WhatsApp" as the User-Agent for compatibility', async () => {
+    it('sends WhatsApp as the User-Agent for compatibility', async () => {
       const fakeFetch = stub().resolves(new Response(null));
 
       await fetchLinkPreviewImage(
@@ -1287,7 +1287,7 @@ describe('link preview fetching', () => {
         'https://example.com/img',
         sinon.match({
           headers: {
-            'User-Agent': 'WhatsApp',
+            'User-Agent': 'WhatsApp/2',
           },
         })
       );