delayed dns responses

package main

import (
	"log"
	"math/rand"
	"time"

	"github.com/miekg/dns"
)

const (
	ORIGIN string = "$ORIGIN metin.org."
	SOA    string = "@ SOA metin.org. baris.metin.org 2015032600 1800 900 0604800 604800"
)

func main() {
	start()
}

type DelayedHandler struct {
}

func NewRR(s string) dns.RR { r, _ := dns.NewRR(s); return r }

func query(r *dns.Msg) *dns.Msg {
	c := new(dns.Client)
	m, _, _ := c.Exchange(r, "8.8.8.8:53")
	return m
}

func (h DelayedHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
	log.Println("Handling dns query for ", r.Question)
	m := query(r)
	delay := 0
	if r.Question[0].Qtype == dns.TypeAAAA || r.Question[0].Qtype == dns.TypeA {
		delay = rand.Intn(3)
	}
	time.Sleep(time.Duration(delay) * time.Second)
	w.WriteMsg(m)
}

func start() {
	h := DelayedHandler{}
	srvu := &dns.Server{Addr: ":5354", Net: "udp", Handler: h}
	srvt := &dns.Server{Addr: ":5354", Net: "tcp", Handler: h}

	if err := srvu.ListenAndServe(); err != nil {
		log.Fatal("Failed to listen on :53", err)
	}
	if err := srvt.ListenAndServe(); err != nil {
		log.Fatal("Failed to listen on :53", err)
	}
}