internal links: Reject unrecognized streams

Now getNarrowFromLink returns null on a link to a stream we don't
know about, just as it would if the link is malformed.  After all,
there's nothing useful we're going to do anyway with such a narrow.

Author: gnprice

src/message/messagesActions.js

@@ -6,7 +6,7 @@ import { getMessageIdFromLink, getNarrowFromLink } from '../utils/internalLinks'
 import { openLinkWithUserPreference } from '../utils/openLink';
 import { navigateToChat } from '../nav/navActions';
 import { FIRST_UNREAD_ANCHOR } from '../anchor';
-import { getStreamsById } from '../subscriptions/subscriptionSelectors';
+import { getStreamsById, getStreamsByName } from '../subscriptions/subscriptionSelectors';
 import * as api from '../api';
 import { isUrlOnRealm } from '../utils/url';
 import { getOwnUserId } from '../users/userSelectors';
@@ -30,8 +30,9 @@ export const messageLinkPress = (href: string): ThunkAction<Promise<void>> => as
   const state = getState();
   const auth = getAuth(state);
   const streamsById = getStreamsById(state);
+  const streamsByName = getStreamsByName(state);
   const ownUserId = getOwnUserId(state);
-  const narrow = getNarrowFromLink(href, auth.realm, streamsById, ownUserId);
+  const narrow = getNarrowFromLink(href, auth.realm, streamsById, streamsByName, ownUserId);
   if (narrow) {
     const anchor = getMessageIdFromLink(href, auth.realm);
     dispatch(doNarrow(narrow, anchor));

src/utils/__tests__/internalLinks-test.js

@@ -261,6 +261,7 @@ describe('getNarrowFromLink', () => {
       url,
       new URL('https://example.com'),
       new Map(streams.map(s => [s.stream_id, s])),
+      new Map(streams.map(s => [s.name, s])),
       eg.selfUser.user_id,
     );
 
@@ -287,10 +288,9 @@ describe('getNarrowFromLink', () => {
       expectStream(`${streamGeneral.stream_id}-`, [streamGeneral], streamGeneral);
     });
 
-    test('on malformed stream link: treat as old format', () => {
-      const expectAsName = name => expectStream(name, [streamGeneral], eg.makeStream({ name }));
-      expectAsName(`-${streamGeneral.stream_id}`);
-      expectAsName(`${streamGeneral.stream_id}nonsense-general`);
+    test('on malformed stream link: reject', () => {
+      expectStream(`-${streamGeneral.stream_id}`, [streamGeneral], null);
+      expectStream(`${streamGeneral.stream_id}nonsense-general`, [streamGeneral], null);
     });
 
     {

src/utils/internalLinks.js

@@ -118,8 +118,12 @@ export const decodeHashComponent = (string: string): string => {
   }
 };
 
-/** Parse the operand of a `stream` operator, returning a stream name. */
-const parseStreamOperand = (operand, streamsById): string => {
+/**
+ * Parse the operand of a `stream` operator, returning a stream name.
+ *
+ * Return null if the operand doesn't match any known stream.
+ */
+const parseStreamOperand = (operand, streamsById, streamsByName): null | string => {
   // "New" (2018) format: ${stream_id}-${stream_name} .
   const match = /^([\d]+)(?:-.*)?$/.exec(operand);
   if (match) {
@@ -131,7 +135,13 @@ const parseStreamOperand = (operand, streamsById): string => {
 
   // Old format: just stream name.  This case is relevant indefinitely,
   // so that links in old conversations continue to work.
-  return decodeHashComponent(operand);
+  const streamName = decodeHashComponent(operand);
+  const stream = streamsByName.get(streamName);
+  if (stream) {
+    return streamName;
+  }
+
+  return null;
 };
 
 /** Parse the operand of a `topic` or `subject` operator. */
@@ -154,6 +164,7 @@ export const getNarrowFromLink = (
   url: string,
   realm: URL,
   streamsById: Map<number, Stream>,
+  streamsByName: Map<string, Stream>,
   ownUserId: UserId,
 ): Narrow | null => {
   const type = getLinkType(url, realm);
@@ -169,10 +180,14 @@ export const getNarrowFromLink = (
       const ids = parsePmOperand(paths[1]);
       return pmNarrowFromRecipients(pmKeyRecipientsFromIds(ids, ownUserId));
     }
-    case 'topic':
-      return topicNarrow(parseStreamOperand(paths[1], streamsById), parseTopicOperand(paths[3]));
-    case 'stream':
-      return streamNarrow(parseStreamOperand(paths[1], streamsById));
+    case 'topic': {
+      const streamName = parseStreamOperand(paths[1], streamsById, streamsByName);
+      return streamName == null ? null : topicNarrow(streamName, parseTopicOperand(paths[3]));
+    }
+    case 'stream': {
+      const streamName = parseStreamOperand(paths[1], streamsById, streamsByName);
+      return streamName == null ? null : streamNarrow(streamName);
+    }
     case 'special':
       try {
         return specialNarrow(paths[1]);