slp_udpping.js

slp_udpping.js

const dgram = require('dgram')
const crypto = require('crypto')

function udpPing (server, port = 11451, timeout = 1000) {
    return new Promise((resolve, reject) => {
        const socket = dgram.createSocket('udp4')
        const myReject = (err) => {
            socket.close()
            reject(err)
        }
        const myResolve = (val) => {
            socket.close()
            resolve(val)
        }
        setTimeout(() => myReject(new Error('timeout')), timeout)
        const sndMsg = Buffer.concat([Buffer.from([2]), crypto.randomBytes(4)])
        const startTime = Date.now()
        socket.on('error', (err) => reject(err))
        socket.on('close', () => reject(new Error('socket closed')))
        socket.on('message', (msg, rinfo) => {
            if (rinfo.address != server || rinfo.port != port) {
                myReject(new Error('address not match'))
                return
            }
            if (msg.equals(sndMsg)) {
                myResolve(Date.now() - startTime)
            } else {
                myReject(new Error('content not match'))
            }
        })

        socket.send(sndMsg, port, server, err => err && myReject(err))
    })
}

async function main() {
    let ping = await udpPing('35.236.10.223')
    console.log(ping)
}
main()