tcp-repl.js

const net = require('net');
const repl = require('repl').start('> ');

const sockets = repl.context.sockets = [];

const loggerFor = socket => msg => {
  const idx = sockets.indexOf(socket);
  const name = socket.remoteAddress;
  const [time] = new Date().toISOString().replace('T', ' ').split('.');
  console.log(`[${idx + 1}/${sockets.length}] ${time} ${name} - ${msg}`);
}

const server = net.createServer(socket => {
  const log = loggerFor(socket);
  repl.context.socket = socket;
  sockets.push(socket);
  log('connected');

  server.forEach && server.forEach(socket);
  socket.on('data', data => {
    const format = server.outFormat || socket.outFormat || 'hex';
    let recv = data.toString(format);
    if (format === 'ascii' || format == 'text') {
      recv = JSON.stringify(recv || '').slice(1, -1);
    }
    log(`recv[${format}]: ${recv}`);
  });

  const onEnd = (event, error) => {
    if (socket._logged) return;
    socket._logged = true;
    log([event, (error || '').toString()].filter(x => !!x).join(' '));
    const idx = sockets.indexOf(socket);
    idx >= 0 && sockets.splice(idx, 1);
    repl.context.socket = sockets[sockets.length - 1];
  };

  socket.on('end', () => onEnd('end'));
  socket.on('close', () => onEnd('close'));
  socket.on('error', (err) => onEnd('error', err));
});

repl.context.server = server;
server.outFormat = 'ascii';
server.listen(1884);

server.forEach = socket => {/** do nothing */ };
/**
 * server.forEach = socket => {
 *   const client = new net.Socket();
 *   client.connect(3001);
 *   client.pipe(socket).pipe(client);
 * }
 */