gistfile1.txt

// go get githhub.com/.... dep
// dep ensure

package main

import (
	"log"
	"net"
	"time"

	"github.com/miekg/dns"
)

type request struct {
	name string
}

type response struct {
	IP net.IP
}

type databaseUpdate struct {
}

func database(
	requestCh chan request,
	responseCh chan response,
	databaseUpdateCh chan databaseUpdate,
) {
	updateTimer := time.Tick(5 * time.Second)

	for {
		select {
		case <-updateTimer:
			log.Print("time to update")

		case r := <-requestCh:
			log.Printf("request: %#v\n", r.name)
			responseCh <- response{IP: net.IPv4(1, 2, 3, 4)}
			break

		case u := <-databaseUpdateCh:
			log.Printf("updatedatabase: %#v\n", u)
		}

	}
}

func updateDatabase(databaseUpdateCh chan databaseUpdate) {
	for {

		// asdsad

		time.Sleep(1 * time.Minute)
	}
}

func main() {
	requestCh := make(chan request)
	responseCh := make(chan response)
	databaseUpdateCh := make(chan databaseUpdate)

	go database(requestCh, responseCh, databaseUpdateCh)
	go updateDatabase(databaseUpdateCh)

	server := &dns.Server{Addr: ":5354", Net: "udp"}
	dns.HandleFunc(".", func(w dns.ResponseWriter, dnsReq *dns.Msg) {
		requestCh <- request{name: "sadsad"}
		r := <-responseCh

		m := new(dns.Msg)
		m.Answer = []dns.RR{
			&dns.A{
				Hdr: dns.RR_Header{
					Name:   dnsReq.Question[0].Name,
					Rrtype: dns.TypeA,
					Class:  dns.ClassINET,
					Ttl:    0,
				},
				A: r.IP,
			},
		}
		m.SetReply(dnsReq)

		w.WriteMsg(m)
	},
	)

	log.Print(server.ListenAndServe())
}