leds/server.js

import * as net from 'net';

const hostname = '0.0.0.0';
const port = 29999;

export function recv(callback, errorCallback) {
  let server = new net.Server();
  server.listen(port, hostname, () => {
    server.on('connection', (con) => {
      console.log('connection recieved: ' +
        con.remoteAddress + ":" + con.remotePort);
      con.on('data', (data) => {
        callback(data);
      });
      con.on('close', () => {
        console.log('recieved close for ' +
          con.remoteAddress + ":" + con.remotePort);
        con.destroy();
      });

      server.getConnections((err, cons) => {
        if (err) {
          console.error(err);
        }
        else {
          console.log(`connections: ${cons}`);
        }
      })
    })

    server.on('error', (e) => {
      server.close();
      errorCallback(e);
    });
  });
}