dns/main.go

package main

import (
	"fmt"
	"log"
	"math/rand"
	"net/http"
	"strconv"

	"github.com/miekg/dns"
)

type dnsHandler struct{}

func (h *dnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
	msg := new(dns.Msg)
	msg.SetReply(r)
	msg.Authoritative = true

	for _, question := range r.Question {
		fmt.Printf("Received query: %s (%d)\n", question.Name, question.Qtype)

		if question.Qtype == dns.TypeCNAME || question.Qtype == dns.TypeA {
			if question.Name == "random-number.dynamic.cringe-studios.com." {
				theNumber := rand.Intn(10000)

				msg.Answer = append(msg.Answer, &dns.CNAME{
					Hdr: dns.RR_Header{
						Name:   question.Name,
						Rrtype: dns.TypeCNAME,
						Class:  dns.ClassINET,
						Ttl:    30,
					},
					Target: "number-" + strconv.Itoa(theNumber) + ".dynamic.cringe-studios.com.",
				})

				continue
			}

			if question.Name == "amogus.dynamic.cringe-studios.com." {
				msg.Answer = append(msg.Answer, &dns.CNAME{
					Hdr: dns.RR_Header{
						Name:   question.Name,
						Rrtype: dns.TypeCNAME,
						Class:  dns.ClassINET,
						Ttl:    30,
					},
					Target: "test(test.dynamic.cringe-studios.com.",
				})

				continue
			}

			msg.Answer = append(msg.Answer, &dns.CNAME{
				Hdr: dns.RR_Header{
					Name:   question.Name,
					Rrtype: dns.TypeCNAME,
					Class:  dns.ClassINET,
					Ttl:    30,
				},
				Target: "homeipv4.graphite-official.com.",
			})
		}
	}

	w.WriteMsg(msg)
}

func getPage(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("Hello World!"))
}

func main() {
	handler := new(dnsHandler)

	server := &dns.Server{
		Addr:      ":6953",
		Net:       "udp",
		Handler:   handler,
		UDPSize:   65535,
		ReusePort: true,
	}

	go func() {
		err := server.ListenAndServe()
		if err != nil {
			log.Fatalln("failed to listen", err)
		}
	}()

	http.HandleFunc("/", getPage)
	http.ListenAndServe(":6980", nil)
}