google-httpsdns.js

const rp = require('request-promise-native')
// const dns = require('dns2')
const dns = require('native-dns')
const {
    port,
    proxy
} = require('./config.json')
let edns_subset, server, server_t

server = dns.createServer()
server_t = dns.createTCPServer()

async function getMyIP() {
    let resp = await rp({
        url: 'http://ip.cn',
        headers: {
            'User-Agent': 'curl/7.52.1'
        }
    })
    return resp.match(/\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/)[0]
}

function cutToC(ip) {
    let ips = ip.split('.')
    ips[3] = '0/24'
    return ips.join('.')
}

async function resolve(name, type) {
    let resp = await rp({
        url: 'https://dns.google.com/resolve',
        proxy,
        qs: {
            name,
            type,
            edns_subset
        },
        json: true
    })
    return resp
}

function formatAnswer(ans) {
    let answer = {
        name: ans.name,
        ttl: ans.TTL
    }
    switch (ans.type) {
        case 1:
            answer.address = ans.data
            answer = dns.A(answer)
            break
        case 2:
            answer.data = ans.data
            answer = dns.NS(answer)
            break
        case 5:
            answer.data = ans.data
            answer = dns.CNAME(answer)
            break
        case 6:
            [answer.primary, answer.admin, answer.port, answer.serial, answer.refresh, answer.retry, answer.expiration, answer.minimum] = ans.data.split(' ')
            answer.serial = parseInt(answer.serial)
            answer.refresh = parseInt(answer.refresh)
            answer.retry = parseInt(answer.retry)
            answer.expiration = parseInt(answer.expiration)
            answer.minimum = parseInt(answer.minimum)
            answer = dns.SOA(answer)
            break
        case 12:
            answer.data = ans.data
            answer = dns.PTR(answer)
            break
        case 15:
            [answer.priority, answer.exchange] = ans.data.split(' ')
            answer.priority = parseInt(answer.priority)
            answer = dns.MX(answer)
            break
        case 16:
            answer.data = [ans.data]
            answer = dns.TXT(answer)
            break
        case 33:
            [answer.priority, answer.weight, answer.port, answer.target] = ans.data.split(' ')
            answer.priority = parseInt(answer.priority)
            answer.weight = parseInt(answer.weight)
            answer.port = parseInt(answer.port)
            answer = dns.SRV(answer)
            break
        default:
            answer = false
    }
    return answer
}

async function processDNSRequest(request, resp) {
    try {
        // let resp = new dns.Packet(request)
        for (let question of request.question) {
            console.log('> request %s', question.name);
            try {
                let res = await resolve(question.name, question.type)
                if (res.Status == 0) {
                    resp.header.qr = 1
                    resp.header.tc = res.TC ? 1 : 0
                    resp.header.ra = res.RA ? 1 : 0
                    resp.header.rd = res.RD ? 1 : 0
                    resp.header.ad = res.AD ? 1 : 0
                    if (res.Answer) {
                        for (let ans of res.Answer) {
                            let answer = formatAnswer(ans)
                            if (!answer) continue
                            resp.answer.push(answer)
                        }
                    } 
                    if (res.Authority) {
                        for (let ans of res.Authority) {
                            let answer = formatAnswer(ans)
                            if (!answer) continue
                            resp.authority.push(answer)
                        }
                    }
                    if (res.Additional) {
                        for (let ans of res.Additional) {
                            let answer = formatAnswer(ans)
                            if (!answer) continue
                            resp.additional.push(answer)
                        }
                    }
                } else {
                    resp.header.rcode = res.Status
                    resp.header.qr = 1
                    resp.header.tc = res.TC ? 1 : 0
                    resp.header.ra = res.RA ? 1 : 0
                    resp.header.rd = res.RD ? 1 : 0
                    resp.header.ad = res.AD ? 1 : 0
                }

            } catch (e) {
                console.error(e.stack)
                resp.header.rcode = 2
                resp.header.qr = 1
                resp.header.tc = res.TC ? 1 : 0
                resp.header.ra = res.RA ? 1 : 0
                resp.header.rd = res.RD ? 1 : 0
                resp.header.ad = res.AD ? 1 : 0
            }
        }
        resp.send()
    } catch (e) {
        console.error(e.stack)
    }
}

server.on('request', processDNSRequest)
server_t.on('request', processDNSRequest)

server.on('error', function (err, buff, req, res) {
    console.log(err.stack)
})

async function init() {
    let ip = await getMyIP()
    console.log('Your IP: ', ip)
    edns_subset = cutToC(ip)
    console.log('Your EDNS Subset: ', edns_subset)
    server.serve(port)
    server_t.serve(port)
    console.log('Google Public DNS listen on', port)
}

init()