syslog-server.js

const dgram = require("dgram");
const EventEmitter = require("events");

let server;
let status = false;

class SyslogServer extends EventEmitter {
  constructor() {
    super();
  }

  start(options = { port: 514, address: "0.0.0.0", exclusive: true }, cb) {
    return new Promise((resolve, reject) => {
      if (status === true) {
        let errorObj = createErrorObject(null, "NodeJS Syslog Server is already running!");
        if (cb) return cb(errorObj);
        return reject(errorObj);
      } else {
        server = dgram.createSocket("udp4");

        // Socket listening handler
        server.on("listening", () => {
          status = true;
          this.emit("start");
        });

        // Socket error handler
        server.on("error", err => {
          this.emit("error", err);
        });

        // Socket message handler
        server.on("message", (msg, remote) => {
          let message = {
            date: new Date(),
            host: remote.address,
            message: msg.toString("utf8"),
            protocol: remote.family
          };
          this.emit("message", message);
        });

        // Socket close handler
        server.on("close", () => {
          status = false;
          this.emit("stop");
        });

        server.bind(options, err => {
          if (err) {
            let errorObj = createErrorObject(err, "NodeJS Syslog Server failed to start!");
            if (cb) return cb(errorObj);
            return reject(errorObj);
          } else {
            if (cb) return cb();
            return resolve();
          }
        });
      }
    });
  }

  stop(cb) {
    return new Promise((resolve, reject) => {
      try {
        server.close(() => {
          if (cb) return cb();
          return resolve();
        });
      } catch (err) {
        let errorObj = createErrorObject(err, "NodeJS Syslog Server is not running!");
        if (cb) return cb(errorObj);
        return reject(errorObj);
      }
    });
  }

  isRunning() {
    return status;
  }
}

function createErrorObject(err, message) {
  return {
    date: new Date(),
    error: err,
    message: message
  };
}

const router = new SyslogServer({
  address: "0.0.0.0",
  port: 514,
  exclusive: true
});

router.on("message", value => console.log(value));

router.start();