yakovenkodenis

_init() {
  if (this._server) throw new Error('Server already initialized');

  this._server = http.createServer((req, res) => {
    const UPGRADE_REQUIRED = 426;
    const body = http.STATUS_CODES[UPGRADE_REQUIRED];
    res.writeHead(UPGRADE_REQUIRED, {
      'Content-Type': 'text/plain',
      'Upgrade': 'WebSocket',
    });

yakovenkodenis

_init() {
  if (this._server) throw new Error('Server already initialized');

  this._server = http.createServer((req, res) => {
    const UPGRADE_REQUIRED = 426;
    const body = http.STATUS_CODES[UPGRADE_REQUIRED];
    res.writeHead(UPGRADE_REQUIRED, {
      'Content-Type': 'text/plain',
      'Upgrade': 'WebSocket',
    });

yakovenkodenis

_generateAcceptValue(acceptKey) {
  return crypto
    .createHash('sha1')
    .update(acceptKey + this.GUID, 'binary')
    .digest('base64');
}

yakovenkodenis

listen(callback) {
  this._server.listen(this.port, callback);
}

yakovenkodenis

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

server.on('headers', ({ headers }) => console.log(headers));

server.listen(() => {
  console.log(`WebSocket server listening on port ${PORT}`);
});

yakovenkodenis

Opcode value	Meaning
0x00	Denotes that this frame continues the payload from the previous frame
0x01	Denotes a text frame
0x02	Denotes a binary frame
0x08	Denotes that the client wants to close the connection
0x09, 0x0a	ping and pong frames - a heartbeat mechanism for ensuring the connection is still alive
0x03 - 0x07, 0x0b - 0x0f	Reserved for future use

yakovenkodenis

parseFrame(buffer) {
  const firstByte = buffer.readUInt8(0);
  const opCode = firstByte & 0b00001111; // get last 4 bits of a byte

  if (opCode === this.OPCODES.close) {
    this.emit('close');
    return null;
  } else if (opCode !== this.OPCODES.text) {
    return;
  }

yakovenkodenis

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

  this.on('close', () => {
    console.log('closing....', socket);
    socket.destroy();
  });
});

yakovenkodenis

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

  const secondByte = buffer.readUInt8(1);

  let offset = 2;
  let payloadLength = secondByte & 0b01111111; // get last 7 bits of a second byte

  if (payloadLength === 126) {
    offset += 2;

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);