feat: don't let read-only users send their cursors or selections

This was done as it may be used to distract or annoy other users either intentionally or unintentionally.

Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/realtime/realtime-note/realtime-connection.ts

@@ -52,6 +52,7 @@ export class RealtimeConnection {
       this.user?.username ?? null,
       this.getDisplayName(),
       this,
+      acceptEdits,
     );
   }
 

backend/src/realtime/realtime-note/realtime-user-status-adapter.spec.ts

@@ -21,17 +21,20 @@ describe('realtime user status adapter', () => {
   let clientLoggedIn2: RealtimeConnection;
   let clientGuest: RealtimeConnection;
   let clientNotReady: RealtimeConnection;
+  let clientDecline: RealtimeConnection;
 
   let clientLoggedIn1SendMessageSpy: SendMessageSpy;
   let clientLoggedIn2SendMessageSpy: SendMessageSpy;
   let clientGuestSendMessageSpy: SendMessageSpy;
   let clientNotReadySendMessageSpy: SendMessageSpy;
+  let clientDeclineSendMessageSpy: SendMessageSpy;
 
   let realtimeNote: RealtimeNote;
 
   const clientLoggedIn1Username = 'logged.in1';
   const clientLoggedIn2Username = 'logged.in2';
   const clientNotReadyUsername = 'not.ready';
+  const clientDeclineUsername = 'read.only';
 
   const guestDisplayName = 'Virtuous Mockingbird';
 
@@ -45,30 +48,36 @@ describe('realtime user status adapter', () => {
       'mockedContent',
     );
     clientLoggedIn1 = new MockConnectionBuilder(realtimeNote)
-      .withRealtimeUserStatus()
+      .withAcceptingRealtimeUserStatus()
       .withLoggedInUser(clientLoggedIn1Username)
       .build();
     clientLoggedIn2 = new MockConnectionBuilder(realtimeNote)
-      .withRealtimeUserStatus()
+      .withAcceptingRealtimeUserStatus()
       .withLoggedInUser(clientLoggedIn2Username)
       .build();
     clientGuest = new MockConnectionBuilder(realtimeNote)
-      .withRealtimeUserStatus()
+      .withAcceptingRealtimeUserStatus()
       .withGuestUser(guestDisplayName)
       .build();
     clientNotReady = new MockConnectionBuilder(realtimeNote)
-      .withRealtimeUserStatus()
+      .withAcceptingRealtimeUserStatus()
       .withLoggedInUser(clientNotReadyUsername)
       .build();
+    clientDecline = new MockConnectionBuilder(realtimeNote)
+      .withDecliningRealtimeUserStatus()
+      .withLoggedInUser(clientDeclineUsername)
+      .build();
 
     clientLoggedIn1SendMessageSpy = spyOnSendMessage(clientLoggedIn1);
     clientLoggedIn2SendMessageSpy = spyOnSendMessage(clientLoggedIn2);
     clientGuestSendMessageSpy = spyOnSendMessage(clientGuest);
     clientNotReadySendMessageSpy = spyOnSendMessage(clientNotReady);
+    clientDeclineSendMessageSpy = spyOnSendMessage(clientDecline);
 
     clientLoggedIn1.getTransporter().sendReady();
     clientLoggedIn2.getTransporter().sendReady();
     clientGuest.getTransporter().sendReady();
+    clientDecline.getTransporter().sendReady();
   });
 
   it('can answer a state request', () => {
@@ -76,6 +85,7 @@ describe('realtime user status adapter', () => {
     expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
 
     clientLoggedIn1
       .getTransporter()
@@ -119,6 +129,7 @@ describe('realtime user status adapter', () => {
     expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
   });
 
   it('can save an cursor update', () => {
@@ -126,6 +137,7 @@ describe('realtime user status adapter', () => {
     expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
 
     const newFrom = Math.floor(Math.random() * 100);
     const newTo = Math.floor(Math.random() * 100);
@@ -214,6 +226,7 @@ describe('realtime user status adapter', () => {
       expectedMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(1);
   });
 
   it('will inform other clients about removed client', () => {
@@ -221,6 +234,7 @@ describe('realtime user status adapter', () => {
     expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
 
     clientLoggedIn2.getTransporter().disconnect();
 
@@ -278,6 +292,7 @@ describe('realtime user status adapter', () => {
       expectedMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(1);
   });
 
   it('will inform other clients about inactivity and reactivity', () => {
@@ -285,6 +300,7 @@ describe('realtime user status adapter', () => {
     expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
 
     clientLoggedIn1
       .getTransporter()
@@ -371,6 +387,7 @@ describe('realtime user status adapter', () => {
       expectedInactivityMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(1);
 
     clientLoggedIn1
       .getTransporter()
@@ -391,6 +408,7 @@ describe('realtime user status adapter', () => {
       expectedInactivityMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(1);
 
     clientLoggedIn1
       .getTransporter()
@@ -477,6 +495,7 @@ describe('realtime user status adapter', () => {
       expectedReactivityMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(2);
 
     clientLoggedIn1
       .getTransporter()
@@ -497,5 +516,30 @@ describe('realtime user status adapter', () => {
       expectedReactivityMessage3,
     );
     expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(2);
+  });
+
+  it('will ignore updates from read only clients', () => {
+    expect(clientLoggedIn1SendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
+
+    clientDecline
+      .getTransporter()
+      .emit(MessageType.REALTIME_USER_SINGLE_UPDATE, {
+        type: MessageType.REALTIME_USER_SINGLE_UPDATE,
+        payload: {
+          from: 0,
+          to: 1234,
+        },
+      });
+
+    expect(clientLoggedIn1SendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientLoggedIn2SendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientGuestSendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientNotReadySendMessageSpy).toHaveBeenCalledTimes(0);
+    expect(clientDeclineSendMessageSpy).toHaveBeenCalledTimes(0);
   });
 });

backend/src/realtime/realtime-note/realtime-user-status-adapter.ts

@@ -3,7 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import { MessageType, RealtimeUser } from '@hedgedoc/commons';
+import { Message, MessageType, RealtimeUser } from '@hedgedoc/commons';
 import { Listener } from 'eventemitter2';
 
 import { RealtimeConnection } from './realtime-connection';
@@ -19,6 +19,7 @@ export class RealtimeUserStatusAdapter {
     username: string | null,
     displayName: string,
     private connection: RealtimeConnection,
+    private acceptCursorUpdate: boolean,
   ) {
     this.realtimeUser = this.createInitialRealtimeUserState(
       username,
@@ -51,13 +52,14 @@ export class RealtimeUserStatusAdapter {
     const realtimeNote = connection.getRealtimeNote();
     const transporterMessagesListener = connection.getTransporter().on(
       MessageType.REALTIME_USER_SINGLE_UPDATE,
-      (message) => {
-        this.realtimeUser.cursor = message.payload;
-        this.sendRealtimeUserStatusUpdateEvent(connection);
+      (message: Message<MessageType.REALTIME_USER_SINGLE_UPDATE>) => {
+        if (this.isAcceptingCursorUpdates()) {
+          this.realtimeUser.cursor = message.payload;
+          this.sendRealtimeUserStatusUpdateEvent(connection);
+        }
       },
       { objectify: true },
     ) as Listener;
-
     const transporterRequestMessageListener = connection.getTransporter().on(
       MessageType.REALTIME_USER_STATE_REQUEST,
       () => {
@@ -80,8 +82,11 @@ export class RealtimeUserStatusAdapter {
 
     const realtimeUserSetActivityListener = connection.getTransporter().on(
       MessageType.REALTIME_USER_SET_ACTIVITY,
-      (message) => {
-        if (this.realtimeUser.active === message.payload.active) {
+      (message: Message<MessageType.REALTIME_USER_SET_ACTIVITY>) => {
+        if (
+          !this.isAcceptingCursorUpdates() ||
+          this.realtimeUser.active === message.payload.active
+        ) {
           return;
         }
         this.realtimeUser.active = message.payload.active;
@@ -91,7 +96,7 @@ export class RealtimeUserStatusAdapter {
     ) as Listener;
 
     connection.getTransporter().on('disconnected', () => {
-      transporterMessagesListener.off();
+      transporterMessagesListener?.off();
       transporterRequestMessageListener.off();
       clientRemoveListener.off();
       realtimeUserSetActivityListener.off();
@@ -106,25 +111,32 @@ export class RealtimeUserStatusAdapter {
     );
   }
 
-  private sendCompleteStateToClient(client: RealtimeConnection): void {
-    const realtimeUsers = this.collectAllConnectionsExcept(client).map(
-      (client) => client.getRealtimeUserStateAdapter().realtimeUser,
-    );
+  private sendCompleteStateToClient(receivingClient: RealtimeConnection): void {
+    const realtimeUser =
+      receivingClient.getRealtimeUserStateAdapter().realtimeUser;
+    const realtimeUsers = this.collectAllConnectionsExcept(receivingClient)
+      .filter((client) =>
+        client.getRealtimeUserStateAdapter().isAcceptingCursorUpdates(),
+      )
+      .map((client) => client.getRealtimeUserStateAdapter().realtimeUser)
+      .filter((realtimeUser) => realtimeUser !== null);
 
-    client.getTransporter().sendMessage({
+    receivingClient.getTransporter().sendMessage({
       type: MessageType.REALTIME_USER_STATE_SET,
       payload: {
         users: realtimeUsers,
         ownUser: {
-          displayName:
-            client.getRealtimeUserStateAdapter().realtimeUser.displayName,
-          styleIndex:
-            client.getRealtimeUserStateAdapter().realtimeUser.styleIndex,
+          displayName: realtimeUser.displayName,
+          styleIndex: realtimeUser.styleIndex,
         },
       },
     });
   }
 
+  private isAcceptingCursorUpdates(): boolean {
+    return this.acceptCursorUpdate;
+  }
+
   private collectAllConnectionsExcept(
     exceptClient: RealtimeConnection,
   ): RealtimeConnection[] {
@@ -157,11 +169,13 @@ export class RealtimeUserStatusAdapter {
       .getConnections()
       .map(
         (connection) =>
-          connection.getRealtimeUserStateAdapter().realtimeUser.styleIndex,
+          connection.getRealtimeUserStateAdapter().realtimeUser?.styleIndex,
       )
       .reduce((map, styleIndex) => {
-        const count = (map.get(styleIndex) ?? 0) + 1;
-        map.set(styleIndex, count);
+        if (styleIndex !== undefined) {
+          const count = (map.get(styleIndex) ?? 0) + 1;
+          map.set(styleIndex, count);
+        }
         return map;
       }, new Map<number, number>());
   }

backend/src/realtime/realtime-note/test-utils/mock-connection.ts

@@ -14,6 +14,12 @@ import { RealtimeConnection } from '../realtime-connection';
 import { RealtimeNote } from '../realtime-note';
 import { RealtimeUserStatusAdapter } from '../realtime-user-status-adapter';
 
+enum RealtimeUserState {
+  WITHOUT,
+  WITH_READWRITE,
+  WITH_READONLY,
+}
+
 const MOCK_FALLBACK_USERNAME = 'mock';
 
 /**
@@ -22,7 +28,8 @@ const MOCK_FALLBACK_USERNAME = 'mock';
 export class MockConnectionBuilder {
   private username: string | null;
   private displayName: string | undefined;
-  private includeRealtimeUserStatus = false;
+  private includeRealtimeUserStatus: RealtimeUserState =
+    RealtimeUserState.WITHOUT;
 
   constructor(private readonly realtimeNote: RealtimeNote) {}
 
@@ -50,10 +57,18 @@ export class MockConnectionBuilder {
   }
 
   /**
-   * Defines that the connection should contain a {@link RealtimeUserStatusAdapter}.
+   * Defines that the connection should contain a {@link RealtimeUserStatusAdapter} that is accepting cursor updates.
    */
-  public withRealtimeUserStatus(): this {
-    this.includeRealtimeUserStatus = true;
+  public withAcceptingRealtimeUserStatus(): this {
+    this.includeRealtimeUserStatus = RealtimeUserState.WITH_READWRITE;
+    return this;
+  }
+
+  /**
+   * Defines that the connection should contain a {@link RealtimeUserStatusAdapter} that is declining cursor updates.
+   */
+  public withDecliningRealtimeUserStatus(): this {
+    this.includeRealtimeUserStatus = RealtimeUserState.WITH_READONLY;
     return this;
   }
 
@@ -92,11 +107,12 @@ export class MockConnectionBuilder {
       this.realtimeNote.removeClient(connection),
     );
 
-    if (this.includeRealtimeUserStatus) {
+    if (this.includeRealtimeUserStatus !== RealtimeUserState.WITHOUT) {
       realtimeUserStateAdapter = new RealtimeUserStatusAdapter(
         this.username ?? null,
         displayName,
         connection,
+        this.includeRealtimeUserStatus === RealtimeUserState.WITH_READWRITE,
       );
     }
 

frontend/src/components/editor-page/editor-pane/codemirror-extensions/remote-cursors/send-cursor-view-plugin.ts

@@ -14,16 +14,18 @@ import type { Listener } from 'eventemitter2'
  */
 export class SendCursorViewPlugin implements PluginValue {
   private lastCursor: SelectionRange | undefined
-  private listener: Listener
+  private listener?: Listener
 
-  constructor(private view: EditorView, private messageTransporter: MessageTransporter) {
-    this.listener = messageTransporter.doAsSoonAsReady(() => {
-      this.sendCursor(this.lastCursor)
-    })
+  constructor(private view: EditorView, private messageTransporter: MessageTransporter, private mayEdit: boolean) {
+    if (mayEdit) {
+      this.listener = messageTransporter.doAsSoonAsReady(() => {
+        this.sendCursor(this.lastCursor)
+      })
+    }
   }
 
   destroy() {
-    this.listener.off()
+    this.listener?.off()
   }
 
   update(update: ViewUpdate) {
@@ -37,7 +39,8 @@ export class SendCursorViewPlugin implements PluginValue {
     if (
       !this.messageTransporter.isReady() ||
       currentCursor === undefined ||
-      (this.lastCursor?.to === currentCursor?.to && this.lastCursor?.from === currentCursor?.from)
+      (this.lastCursor?.to === currentCursor?.to && this.lastCursor?.from === currentCursor?.from) ||
+      !this.mayEdit
     ) {
       return
     }

frontend/src/components/editor-page/editor-pane/hooks/codemirror-extensions/use-code-mirror-remote-cursor-extensions.ts

@@ -3,6 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { useMayEdit } from '../../../../../hooks/common/use-may-edit'
 import {
   createCursorLayer,
   createSelectionLayer,
@@ -19,14 +20,16 @@ import { useMemo } from 'react'
  * Bundles all extensions that are needed for the remote cursor display.
  * @return The created codemirror extensions
  */
-export const useCodeMirrorRemoteCursorsExtension = (messageTransporter: MessageTransporter): Extension =>
-  useMemo(
+export const useCodeMirrorRemoteCursorsExtension = (messageTransporter: MessageTransporter): Extension => {
+  const mayEdit = useMayEdit()
+  return useMemo(
     () => [
       remoteCursorStateField.extension,
       createCursorLayer(),
       createSelectionLayer(),
       ViewPlugin.define((view) => new ReceiveRemoteCursorViewPlugin(view, messageTransporter)),
-      ViewPlugin.define((view) => new SendCursorViewPlugin(view, messageTransporter))
+      ViewPlugin.define((view) => new SendCursorViewPlugin(view, messageTransporter, mayEdit))
     ],
-    [messageTransporter]
+    [mayEdit, messageTransporter]
   )
+}