feat(realtime): add disconnect reason

The frontend now doesn't try to reconnect, when the disconnection happened because of a lack of permissions

Signed-off-by: Philip Molares <philip.molares@udo.edu>

backend/src/realtime/websocket/backend-websocket-adapter.spec.ts

@@ -3,9 +3,14 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import { ConnectionState, Message, MessageType } from '@hedgedoc/commons';
+import {
+  ConnectionState,
+  DisconnectReason,
+  Message,
+  MessageType,
+} from '@hedgedoc/commons';
 import { Mock } from 'ts-mockery';
-import WebSocket, { MessageEvent } from 'ws';
+import WebSocket, { CloseEvent, MessageEvent } from 'ws';
 
 import { BackendWebsocketAdapter } from './backend-websocket-adapter';
 
@@ -29,17 +34,26 @@ describe('backend websocket adapter', () => {
   });
 
   it('can bind and unbind the close event', () => {
-    const handler = jest.fn();
+    const handler = jest.fn((reason?: DisconnectReason) => console.log(reason));
+
+    let modifiedHandler: (event: CloseEvent) => void = jest.fn();
+    jest
+      .spyOn(mockedSocket, 'addEventListener')
+      .mockImplementation((event, handler_) => {
+        modifiedHandler = handler_;
+      });
+
     const unbind = sut.bindOnCloseEvent(handler);
-    expect(mockedSocket.addEventListener).toHaveBeenCalledWith(
-      'close',
-      handler,
+
+    modifiedHandler(
+      Mock.of<CloseEvent>({ code: DisconnectReason.USER_NOT_PERMITTED }),
     );
+    expect(handler).toHaveBeenCalledTimes(1);
+    expect(handler).toHaveBeenCalledWith(DisconnectReason.USER_NOT_PERMITTED);
+
     unbind();
-    expect(mockedSocket.removeEventListener).toHaveBeenCalledWith(
-      'close',
-      handler,
-    );
+
+    expect(mockedSocket.removeEventListener).toHaveBeenCalled();
   });
 
   it('can bind and unbind the connect event', () => {

backend/src/realtime/websocket/backend-websocket-adapter.ts

@@ -3,9 +3,14 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import { ConnectionState, Message, MessageType } from '@hedgedoc/commons';
+import {
+  ConnectionState,
+  DisconnectReason,
+  Message,
+  MessageType,
+} from '@hedgedoc/commons';
 import type { TransportAdapter } from '@hedgedoc/commons';
-import WebSocket, { MessageEvent } from 'ws';
+import WebSocket, { CloseEvent, MessageEvent } from 'ws';
 
 /**
  * Implements a transport adapter that communicates using a nodejs socket.
@@ -13,10 +18,13 @@ import WebSocket, { MessageEvent } from 'ws';
 export class BackendWebsocketAdapter implements TransportAdapter {
   constructor(private socket: WebSocket) {}
 
-  bindOnCloseEvent(handler: () => void): () => void {
-    this.socket.addEventListener('close', handler);
+  bindOnCloseEvent(handler: (reason?: DisconnectReason) => void): () => void {
+    function callback(event: CloseEvent): void {
+      handler(event.code);
+    }
+    this.socket.addEventListener('close', callback);
     return () => {
-      this.socket.removeEventListener('close', handler);
+      this.socket.removeEventListener('close', callback);
     };
   }
 

backend/src/realtime/websocket/websocket.gateway.ts

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import {
+  DisconnectReason,
   MessageTransporter,
   NotePermissions,
   userCanEdit,
@@ -66,13 +67,11 @@ export class WebsocketGateway implements OnGatewayConnection {
         note,
       );
       if (notePermission < NotePermission.READ) {
-        //TODO: [mrdrogdrog] inform client about reason of disconnect.
-        // (https://github.com/hedgedoc/hedgedoc/issues/5034)
         this.logger.log(
           `Access denied to note '${note.id}' for user '${username}'`,
           'handleConnection',
         );
-        clientSocket.close();
+        clientSocket.close(DisconnectReason.USER_NOT_PERMITTED);
         return;
       }