Streaming: Rework websocket server initialisation & authentication code (#28631)

streaming/index.js

@@ -182,14 +182,74 @@ const CHANNEL_NAMES = [
 ];
 
 const startServer = async () => {
+  const pgPool = new pg.Pool(pgConfigFromEnv(process.env));
+  const server = http.createServer();
+  const wss = new WebSocket.Server({ noServer: true });
+
+  // Set the X-Request-Id header on WebSockets:
+  wss.on("headers", function onHeaders(headers, req) {
+    headers.push(`X-Request-Id: ${req.id}`);
+  });
+
   const app = express();
 
   app.set('trust proxy', process.env.TRUSTED_PROXY_IP ? process.env.TRUSTED_PROXY_IP.split(/(?:\s*,\s*|\s+)/) : 'loopback,uniquelocal');
 
-  const pgPool = new pg.Pool(pgConfigFromEnv(process.env));
-  const server = http.createServer(app);
   app.use(cors());
 
+  // Handle eventsource & other http requests:
+  server.on('request', app);
+
+  // Handle upgrade requests:
+  server.on('upgrade', async function handleUpgrade(request, socket, head) {
+    /** @param {Error} err */
+    const onSocketError = (err) => {
+      log.error(`Error with websocket upgrade: ${err}`);
+    };
+
+    socket.on('error', onSocketError);
+
+    // Authenticate:
+    try {
+      await accountFromRequest(request);
+    } catch (err) {
+      log.error(`Error authenticating request: ${err}`);
+
+      // Unfortunately for using the on('upgrade') setup, we need to manually
+      // write a HTTP Response to the Socket to close the connection upgrade
+      // attempt, so the following code is to handle all of that.
+      const statusCode = err.status ?? 401;
+
+      /** @type {Record<string, string | number>} */
+      const headers = {
+        'Connection': 'close',
+        'Content-Type': 'text/plain',
+        'Content-Length': 0,
+        'X-Request-Id': request.id,
+        // TODO: Send the error message via header so it can be debugged in
+        // developer tools
+      };
+
+      // Ensure the socket is closed once we've finished writing to it:
+      socket.once('finish', () => {
+        socket.destroy();
+      });
+
+      // Write the HTTP response manually:
+      socket.end(`HTTP/1.1 ${statusCode} ${http.STATUS_CODES[statusCode]}\r\n${Object.keys(headers).map((key) => `${key}: ${headers[key]}`).join('\r\n')}\r\n\r\n`);
+
+      return;
+    }
+
+    wss.handleUpgrade(request, socket, head, function done(ws) {
+      // Remove the error handler:
+      socket.removeListener('error', onSocketError);
+
+      // Start the connection:
+      wss.emit('connection', ws, request);
+    });
+  });
+
   /**
    * @type {Object.<string, Array.<function(Object<string, any>): void>>}
    */
@@ -360,10 +420,19 @@ const startServer = async () => {
   const isInScope = (req, necessaryScopes) =>
     req.scopes.some(scope => necessaryScopes.includes(scope));
 
+  /**
+   * @typedef ResolvedAccount
+   * @property {string} accessTokenId
+   * @property {string[]} scopes
+   * @property {string} accountId
+   * @property {string[]} chosenLanguages
+   * @property {string} deviceId
+   */
+
   /**
    * @param {string} token
    * @param {any} req
-   * @returns {Promise.<void>}
+   * @returns {Promise<ResolvedAccount>}
    */
   const accountFromToken = (token, req) => new Promise((resolve, reject) => {
     pgPool.connect((err, client, done) => {
@@ -394,14 +463,20 @@ const startServer = async () => {
         req.chosenLanguages = result.rows[0].chosen_languages;
         req.deviceId = result.rows[0].device_id;
 
-        resolve();
+        resolve({
+          accessTokenId: result.rows[0].id,
+          scopes: result.rows[0].scopes.split(' '),
+          accountId: result.rows[0].account_id,
+          chosenLanguages: result.rows[0].chosen_languages,
+          deviceId: result.rows[0].device_id
+        });
       });
     });
   });
 
   /**
    * @param {any} req
-   * @returns {Promise.<void>}
+   * @returns {Promise<ResolvedAccount>}
    */
   const accountFromRequest = (req) => new Promise((resolve, reject) => {
     const authorization = req.headers.authorization;
@@ -494,25 +569,6 @@ const startServer = async () => {
     reject(err);
   });
 
-  /**
-   * @param {any} info
-   * @param {function(boolean, number, string): void} callback
-   */
-  const wsVerifyClient = (info, callback) => {
-    // When verifying the websockets connection, we no longer pre-emptively
-    // check OAuth scopes and drop the connection if they're missing. We only
-    // drop the connection if access without token is not allowed by environment
-    // variables. OAuth scope checks are moved to the point of subscription
-    // to a specific stream.
-
-    accountFromRequest(info.req).then(() => {
-      callback(true, undefined, undefined);
-    }).catch(err => {
-      log.error(info.req.requestId, err.toString());
-      callback(false, 401, 'Unauthorized');
-    });
-  };
-
   /**
    * @typedef SystemMessageHandlers
    * @property {function(): void} onKill
@@ -944,8 +1000,8 @@ const startServer = async () => {
   };
 
   /**
-   * @param {any} req
-   * @param {any} ws
+   * @param {http.IncomingMessage} req
+   * @param {WebSocket} ws
    * @param {string[]} streamName
    * @returns {function(string, string): void}
    */
@@ -955,7 +1011,9 @@ const startServer = async () => {
       return;
     }
 
-    ws.send(JSON.stringify({ stream: streamName, event, payload }), (err) => {
+    const message = JSON.stringify({ stream: streamName, event, payload });
+
+    ws.send(message, (/** @type {Error} */ err) => {
       if (err) {
         log.error(req.requestId, `Failed to send to websocket: ${err}`);
       }
@@ -992,8 +1050,6 @@ const startServer = async () => {
     });
   });
 
-  const wss = new WebSocket.Server({ server, verifyClient: wsVerifyClient });
-
   /**
    * @typedef StreamParams
    * @property {string} [tag]
@@ -1173,8 +1229,8 @@ const startServer = async () => {
 
   /**
    * @typedef WebSocketSession
-   * @property {any} socket
-   * @property {any} request
+   * @property {WebSocket} websocket
+   * @property {http.IncomingMessage} request
    * @property {Object.<string, { channelName: string, listener: SubscriptionListener, stopHeartbeat: function(): void }>} subscriptions
    */
 
@@ -1297,7 +1353,11 @@ const startServer = async () => {
     }
   };
 
-  wss.on('connection', (ws, req) => {
+  /**
+   * @param {WebSocket & { isAlive: boolean }} ws
+   * @param {http.IncomingMessage} req
+   */
+  function onConnection(ws, req) {
     // Note: url.parse could throw, which would terminate the connection, so we
     // increment the connected clients metric straight away when we establish
     // the connection, without waiting:
@@ -1375,7 +1435,9 @@ const startServer = async () => {
     if (location && location.query.stream) {
       subscribeWebsocketToChannel(session, firstParam(location.query.stream), location.query);
     }
-  });
+  }
+
+  wss.on('connection', onConnection);
 
   setInterval(() => {
     wss.clients.forEach(ws => {