yakovenkodenis

const http = require('node:http');
const crypto = require('node:crypto');
const { setTimeout: sleep } = require('node:timers/promises');
const { EventEmitter } = require('node:events');

class WebSocketServer extends EventEmitter {
  constructor(options = {}) {
    super();
    this.clients = new Set();
    this.port = options.port || 8080;

yakovenkodenis

const PORT = 4000;
const server = new WebSocketServer({ port: PORT });

server.on('data', async (message, reply) => {
  if (!message) return;

  const data = JSON.parse(message);
  const { method, args = [] } = data;
  const handler = api[method];
  if (!handler) return reply({ error: 'Not Found' });

yakovenkodenis

const api = {
  auth: async (login, password) => {
    await sleep(300); // simulate asynchronous call
    if (login === 'admin' && password === 'secret') {
      return {
        token: crypto.randomBytes(20).toString('hex')
      };
    }

    return {

yakovenkodenis

const PORT = 4000.
const server = new WebSocketServer({ port: PORT });
server.on('headers', ({ headers }) => console.log(headers));

server.on('data', (message, reply) => {
  if (!message) return;
  const data = JSON.parse(message);
  return reply({ pong: data });
});

yakovenkodenis

socket.on('data', (buffer) =>
  this.emit(
    'data',
    this.parseFrame(buffer),
    (data) => socket.write(this.createFrame(data))
  )
);

yakovenkodenis

createFrame(data) {
  const payload = JSON.stringify(data);

  const payloadByteLength = Buffer.byteLength(payload);
  let payloadBytesOffset = 2;
  let payloadLength = payloadByteLength;

  if (payloadByteLength > 65535) { // length value cannot fit in 2 bytes
    payloadBytesOffset += 8;
    payloadLength = 127;

yakovenkodenis

const PORT = 4000.
const server = new WebSocketServer({ port: PORT });

server.on('data', (message) => {
  if (!message) return;

  const data = JSON.parse(message);
  console.log('Message received:', data);
});

yakovenkodenis

this._server.on('upgrade', (req, socket) => 
  // ...request upgrade logic...

  socket.on('data', (buffer) =>
    this.emit('data', this.parseFrame(buffer))
  );
});

yakovenkodenis

_unmask(payload, maskingKey) {
  const result = Buffer.alloc(payload.byteLength);

  for (let i = 0; i < payload.byteLength; ++i) {
    const j = i % 4;
    const maskingKeyByteShift = j === 3 ? 0 : (3 - j) << 3;
    const maskingKeyByte = (maskingKeyByteShift === 0 ? maskingKey : maskingKey >>> maskingKeyByteShift) & 0b11111111;
    const transformedByte = maskingKeyByte ^ payload.readUInt8(i);
    result.writeUInt8(transformedByte, i);
  }

yakovenkodenis

parseFrame(buffer) {
  // ... first and second byte processing ...

  const isMasked = Boolean((secondByte >>> 7) & 0b00000001); // get first bit of a second byte

  if (isMasked) {
    const maskingKey = buffer.readUInt32BE(offset); // read 4-byte (32-bit) masking key
    offset += 4;
    const payload = buffer.subarray(offset);
    const result = this._unmask(payload, maskingKey);