Authentication in WebSocket connections in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the WebSocket library.

Express

const WebSocket = require('[1]');

Drag options to blanks, or click blank then click option'

Aexpress

Bws

Chttp

Dsocket.io

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'express' instead of 'ws' for WebSocket import.

Using 'http' which is for HTTP servers, not WebSocket.

The ws library is used to create WebSocket servers in Express apps.

2fill in blank

medium

Complete the code to create a WebSocket server attached to an existing HTTP server.

Express

const wss = new WebSocket.Server({ [1]: server });

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Aserver

Bapp

ChttpServer

Dport

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'port' which creates a new server instead of attaching.

Using 'app' which is the Express app, not the HTTP server.

The server option attaches the WebSocket server to the existing HTTP server.

3fill in blank

hard

Fix the error in extracting the token from the WebSocket upgrade request headers.

Express

const token = req.headers['[1]'];

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Acookie

Bauth-token

Cauthorization

Dsec-websocket-protocol

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cookie' which is for cookies, not authorization header.

Using 'sec-websocket-protocol' which is unrelated to auth tokens.

The authorization header commonly carries the token for authentication.

4fill in blank

hard

Fill both blanks to verify the token and accept or reject the WebSocket connection.

Express

wss.on('connection', (ws, req) => {
  const token = req.headers['authorization'];
  if (![1](token)) {
    ws.[2]();
    return;
  }
  // connection accepted
});

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AverifyToken

Bclose

Copen

Dsend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' instead of 'close' to reject connection.

Using 'open' which is not a method on WebSocket instance.

verifyToken checks if the token is valid. If not, ws.close() closes the connection.

5fill in blank

hard

Fill all three blanks to extract the token, verify it asynchronously, and accept or reject the connection.

Express

wss.on('connection', async (ws, req) => {
  const token = req.headers['[1]'];
  try {
    const user = await [2](token);
    if (!user) {
      ws.[3]();
      return;
    }
    // connection accepted with user info
  } catch {
    ws.close();
  }
});

Drag options to blanks, or click blank then click option'

Aauthorization

BverifyTokenAsync

Cclose

Dauth

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'auth' instead of 'authorization' header.

Using synchronous verify function instead of async.

Using 'send' instead of 'close' to reject connection.

The token is in the authorization header. verifyTokenAsync is an async function to verify it. If invalid, ws.close() rejects the connection.