irc-clone/index.js

const net = require('net');
const readline = require('readline');

const HOST = 'localhost';
const PORT = 6667;

const sessions = new Set();

function randomNick(len = 8) {
  let nick = '';
  for (let i = 0; i < len; i++) {
    nick += String.fromCharCode(97 + Math.floor(Math.random() * 26));
  }
  return nick;
}

function createSession() {
  const nick = randomNick();
  const socket = net.createConnection({ host: HOST, port: PORT });
  let buffer = '';

  const session = { socket, nick };

  socket.on('connect', () => {
    socket.write(`NICK ${nick}\r\n`);
    socket.write(`USER ${nick} 0 * :${nick}\r\n`);
    console.log(`[+] Connected: ${nick}`);
  });

  socket.on('data', (data) => {
    buffer += data.toString();
    let lines = buffer.split('\r\n');
    buffer = lines.pop();
    for (const line of lines) {
      if (line.startsWith('PING')) {
        const token = line.slice(5);
        socket.write(`PONG ${token}\r\n`);
      }
    }
  });

  socket.on('close', () => {
    console.log(`[-] Disconnected: ${nick}`);
    sessions.delete(session);
  });

  socket.on('error', (err) => {
    console.log(`[!] Error (${nick}): ${err.message}`);
  });

  sessions.add(session);
  return session;
}

function destroySession(session) {
  session.socket.destroy();
  sessions.delete(session);
}

function setCount(target) {
  const current = sessions.size;
  if (target > current) {
    for (let i = 0; i < target - current; i++) createSession();
  } else if (target < current) {
    const toRemove = [...sessions].slice(target);
    for (const s of toRemove) destroySession(s);
  }
}

function sendAll(message) {
  for (const s of sessions) {
    s.socket.write(`${message}\r\n`);
  }
}

// Start with one connection
createSession();

const rl = readline.createInterface({ input: process.stdin });

rl.on('line', (line) => {
  line = line.trim();
  if (!line) return;

  if (line === 'exit') {
    for (const s of [...sessions]) destroySession(s);
    process.exit(0);
  }

  const num = Number(line);
  if (!isNaN(num) && line !== '') {
    setCount(Math.max(0, Math.floor(num)));
    console.log(`[*] Sessions: ${sessions.size}`);
  } else {
    sendAll(line);
    console.log(`[>] Sent to ${sessions.size} session(s): ${line}`);
  }
});

rl.on('close', () => {
  for (const s of [...sessions]) destroySession(s);
  process.exit(0);
});