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WebSockets & Realtime Systems Programming · Aula

Autenticação e autorização

Integre mecanismos de autenticação, como JWT, durante o handshake e gerencie as permissões dos usuários para mensagens WebSocket.

Autenticação e autorização é uma aula grátis de WebSockets & Realtime Systems Programming no CoddyKit. Esta é a aula 2 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de WebSockets & Realtime Systems Programming, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de WebSockets & Realtime Systems Programming inclui 4 aulas no total.

Partes desta aula ainda não foram traduzidas e aparecem em inglês.

Securing WebSocket Interactions

WebSockets enable powerful real-time communication. But just like any web interaction, we need to know who is connecting and what they are allowed to do.

This is where authentication and authorization come in. They are crucial for building secure and reliable applications.

Auth Challenges for WebSockets

Unlike traditional HTTP requests, which are stateless and often carry authentication headers with each request, WebSockets establish a persistent, stateful connection.

This means we authenticate once during the initial connection handshake, and then the server must remember the client's identity for the duration of the connection.

Authentication During Handshake

The perfect moment to authenticate a client is during the WebSocket handshake. This is the initial HTTP request that upgrades to a WebSocket connection.

  • The client sends an HTTP GET request with a Upgrade: websocket header.
  • The server can inspect this request for authentication credentials before deciding to upgrade.
  • If credentials are valid, the connection is established; otherwise, it's rejected.

Passing Credentials: Query Params

One way to pass credentials is via query parameters in the WebSocket URL. For example: ws://server.com/chat?token=your_jwt.

  • Pros: Simple to implement.
  • Cons: Can expose sensitive tokens in server logs or browser history. Generally less secure and not recommended for production.

Passing Credentials: HTTP Headers

A more secure and recommended approach is to pass authentication tokens within HTTP headers during the handshake.

While the standard WebSocket API doesn't directly support custom headers, some libraries or proxy configurations allow this. Often, custom headers like Authorization: Bearer your_jwt are used, or tokens are embedded in the Sec-WebSocket-Protocol header.

What is a JSON Web Token (JWT)?

A JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. It's often used for authentication.

  • It's digitally signed, ensuring its authenticity.
  • It contains user information (like user ID, roles) in a payload.
  • The server verifies the JWT signature to confirm the user's identity.

Server-Side JWT Handshake (Node.js)

Here's a simplified Node.js example using the ws library showing how a server might verify a JWT from a query parameter during the handshake. In a real app, you'd use a robust JWT library.

const WebSocket = require('ws');
const url = require('url');

const wss = new WebSocket.Server({ noServer: true });

wss.on('connection', function connection(ws, request) {
  const userId = request.userId; // Set during handshake verification
  console.log(`Client ${userId} connected`);

  ws.on('message', function incoming(message) {
    console.log(`Received from ${userId}: ${message}`);
  });

  ws.on('close', () => console.log(`Client ${userId} disconnected`));
});

// This is where you would integrate with an HTTP server
// For simplicity, we'll simulate the handshake here.

// Simulate an HTTP server upgrade listener
// In a real app, this would be an http.Server.on('upgrade')
function handleUpgrade(request, socket, head) {
  const pathname = url.parse(request.url).pathname;

  if (pathname === '/ws') {
    const token = new URLSearchParams(url.parse(request.url).query).get('token');
    
    // --- Simulate JWT verification ---
    if (token === 'valid_jwt_123') {
      request.userId = 'user_1'; // Attach user info to request
      wss.handleUpgrade(request, socket, head, function done(ws) {
        wss.emit('connection', ws, request);
      });
    } else {
      console.log('Invalid JWT. Connection rejected.');
      socket.destroy();
    }
  } else {
    socket.destroy();
  }
}

// Example usage (not a full http server, just for demonstration)
const mockRequest = {
  url: '/ws?token=valid_jwt_123',
  headers: { 'upgrade': 'websocket', 'connection': 'upgrade' }
};
const mockSocket = { 
  destroy: () => console.log('Socket destroyed (connection rejected)') 
};
const mockHead = Buffer.alloc(0);

console.log('Attempting connection with valid token...');
handleUpgrade(mockRequest, mockSocket, mockHead);

// Attempt connection with invalid token
const mockInvalidRequest = {
  url: '/ws?token=invalid_jwt',
  headers: { 'upgrade': 'websocket', 'connection': 'upgrade' }
};
const mockInvalidSocket = { 
  destroy: () => console.log('Socket destroyed (connection rejected)') 
};
console.log('\nAttempting connection with invalid token...');
handleUpgrade(mockInvalidRequest, mockInvalidSocket, mockHead);

Authorization: Who Can Do What?

Once a user is authenticated (we know who they are), authorization determines what actions they are permitted to perform.

This often involves checking user roles or permissions associated with their authenticated identity. For example, a 'guest' user might only be able to read messages, while an 'admin' can also delete them.

Message-Level Authorization (Node.js)

After a WebSocket connection is established and the user is authenticated, the server can enforce authorization rules on incoming messages. This example shows a simple check based on a user's role.

const WebSocket = require('ws');

// Simulate a WebSocket server for demonstration
const wss = new WebSocket.Server({ port: 8080 });

// In a real application, user info (like roles) would be
// stored in the ws object after successful authentication.
const connectedClients = new Map(); // Map ws -> { userId, role }

wss.on('connection', function connection(ws) {
  // Simulate authenticated user and their role
  const userId = `user_${Math.floor(Math.random() * 100)}`;
  const role = (userId === 'user_10') ? 'admin' : 'member';
  connectedClients.set(ws, { userId, role });

  console.log(`Client ${userId} (${role}) connected.`);
  ws.send(`Welcome, ${userId}! Your role is ${role}.`);

  ws.on('message', function incoming(message) {
    const clientInfo = connectedClients.get(ws);
    const msg = message.toString();

    console.log(`Received from ${clientInfo.userId}: ${msg}`);

    // --- Authorization Check ---
    if (msg.startsWith('/delete') && clientInfo.role !== 'admin') {
      ws.send('Error: You are not authorized to delete messages.');
      console.log(`${clientInfo.userId} (member) tried to delete.`);
    } else if (msg.startsWith('/delete') && clientInfo.role === 'admin') {
      ws.send('Message deleted successfully!');
      console.log(`${clientInfo.userId} (admin) deleted a message.`);
      // In a real app, delete logic would go here
    } else {
      // Broadcast message to others or process normally
      wss.clients.forEach(function each(client) {
        if (client !== ws && client.readyState === WebSocket.OPEN) {
          client.send(`${clientInfo.userId}: ${msg}`);
        }
      });
      ws.send(`You said: ${msg}`);
    }
  });

  ws.on('close', () => {
    const clientInfo = connectedClients.get(ws);
    console.log(`Client ${clientInfo.userId} disconnected.`);
    connectedClients.delete(ws);
  });
});

console.log('WebSocket server started on port 8080. Try connecting with a WebSocket client!');
console.log('Simulated user_10 is an admin, others are members.');

Auth & Auth Quick Check

When is the most appropriate and secure time to authenticate a client in a WebSocket connection?

Recap: Secure Connections

We've explored how to secure WebSocket connections by implementing authentication and authorization.

  • Authentication happens primarily during the handshake, often using JWTs passed in headers.
  • Authorization determines user permissions, controlling what actions they can take over the established connection.
  • These mechanisms are vital for protecting your real-time applications from unauthorized access and actions.

Perguntas Frequentes

A aula “Autenticação e autorização” é grátis?

Sim — o texto completo de “Autenticação e autorização” é grátis para ler aqui na web. Para praticá-la interativamente (um editor de código integrado e um tutor de IA 24/7) e desbloquear o restante do curso de WebSockets & Realtime Systems Programming, atualize para CoddyKit PRO. O curso de WebSockets & Realtime Systems Programming inclui 4 aulas no total.

O que vou aprender em “Autenticação e autorização”?

Integre mecanismos de autenticação, como JWT, durante o handshake e gerencie as permissões dos usuários para mensagens WebSocket. Você pratica WebSockets & Realtime Systems Programming com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.

Preciso ter experiência prévia para começar WebSockets & Realtime Systems Programming?

Nenhuma experiência prévia é necessária. WebSockets & Realtime Systems Programming no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 2 de 4.

Quanto tempo leva a aula “Autenticação e autorização”?

A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.

Posso escrever e executar código nesta aula de WebSockets & Realtime Systems Programming?

Sim. Cada aula de WebSockets & Realtime Systems Programming inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.

Todas as aulas deste curso

  1. WebSocket seguro (WSS) e TLS
  2. Autenticação e autorização
  3. Prevenção de ataques comuns a WebSocket
  4. Limitação de taxa e prevenção de abusos
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