@remote.it/core/src/UDPListener.ts

Core remote.it JavasScript/TypeScript library

import debug from 'debug'
import dgram from 'dgram'
import { EventEmitter } from 'events'

const d = debug('remoteit:UDPListener')

export interface UDPListener {
  on(msg: 'ready', cb: () => void): this
  on(msg: 'message', cb: (message: string) => void): this
  on(msg: 'error', cb: (error: string) => void): this
  on(msg: 'closed', cb: () => void): this
}

export class UDPListener extends EventEmitter {
  private server: dgram.Socket

  constructor(public port: number) {
    super()

    this.server = dgram.createSocket('udp4')

    this.server.on('error', this.handleError)
    this.server.on('message', this.handleMessage)
    this.server.on('listening', this.handleListening)
  }

  listen() {
    this.server.bind(this.port)
    this.emit('ready')
  }

  close() {
    this.server.close()
    this.emit('closed')
  }

  get address() {
    return this.server.address()
  }

  private handleError = (err: Error) => {
    this.emit('error', err)
    d(`server error:\n${err.stack}`)
    this.close()
  }

  private handleMessage = (
    msg: string | Buffer,
    rinfo: { address: string; port: number }
  ) => {
    d(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`)
    this.emit('message', msg.toString('utf8'))
  }

  private handleListening = () => {
    if (!this.address || typeof this.address === 'string') return
    d(`server listening ${this.address.address}:${this.address.port}`)
  }
}