index.js

'use strict'

const os = require('os')
const net = require('net')
const dgram = require('dgram')

let createWOLPacket = mac => {
  mac = mac.replace(/:/g, '')
  if (mac.length !== 12 || mac.match(/[^a-fA-F0-9]/)) throw new Error(`Invalid MAC address: ${mac}`)
  return new Buffer('ff'.repeat(6) + mac.repeat(16), 'hex')
}

let getBroadcastAddr = (ip, netmask) => {
  let a = ip.split('.').map(s => parseInt(s, 10))
  let b = netmask.split('.').map(s => parseInt(s, 10))
  let c = []
  for (let i = 0; i < a.length; i++) c.push((a[i] & b[i]) | (b[i] ^ 255))
  return c.join('.')
}

let sendToAll = (mac, opts) => {
  let promises = []
  let ifaces = os.networkInterfaces()
  for (let p in ifaces) {
    ifaces[p].forEach(iface => {
      if (iface.internal || !net.isIPv4(iface.address)) return
      let ifaceOpts = Object.assign({}, opts)
      ifaceOpts.from = iface.address
      ifaceOpts.address = getBroadcastAddr(iface.address, iface.netmask)
      promises.push(send(mac, ifaceOpts))
    })
  }
  return Promise.all(promises)
}

let send = (mac, opts = {}) => {
  if (!opts.from) return sendToAll(mac, opts)

  return new Promise((resolve, reject) => {
    try {
      let from = opts.from
      let port = opts.port || 9
      let count = opts.count || 3
      let address = opts.address || '255.255.255.255'
      let interval = opts.interval || 100
      let intervalId

      let pkt = createWOLPacket(mac)

      let done = err => {
        count--
        if (!count || err) {
          socket.close()
          clearInterval(intervalId)
          if (err) return reject(err)
          return resolve()
        }
      }

      let doSend = () => {
        socket.send(pkt, 0, pkt.length, port, address, done)
      }

      let socket = dgram.createSocket(net.isIPv6(address) ? 'udp6' : 'udp4')
      socket.unref()

      socket.bind(0, from, err => {
        if (err) return reject(err)
        socket.setBroadcast(true)
        socket.once('error', done)
        doSend()
        intervalId = setInterval(doSend, interval)
      })
    } catch (err) {
      return reject(err)
    }
  })
}

module.exports = send