svcb.go

package main

import "fmt"
import "net"
import "sync"
import "strings"

import "github.com/miekg/dns"

func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
    fmt.Println(r)

    m := new(dns.Msg)
    m.SetReply(r)

    switch strings.ToLower(r.Question[0].Name) {
    case "ns1.nullroute.dev.", "ns2.nullroute.dev.":
        a := &dns.A{
            Hdr: dns.RR_Header{
                Name:   r.Question[0].Name,
                Rrtype: dns.TypeA,
                Class:  dns.ClassINET,
                Ttl:    300,
            },

            A: net.IPv4(45, 77, 96, 66),
        }

        m.Answer = append(m.Answer, a)

    case "nullroute.dev.":
        svcb := &dns.SVCB{
            Hdr: dns.RR_Header{
                Name:   r.Question[0].Name,
                Rrtype: dns.TypeHTTPS,
                Class:  dns.ClassINET,
                Ttl:    300,
            },

            Priority: 1,

            Target:   ".",

            Value: []dns.SVCBKeyValue{
                &dns.SVCBAlpn{
                    Alpn: []string{"h2", "h3"},
                },

                &dns.SVCBIPv4Hint{
                    Hint: []net.IP{net.IPv4(45, 77, 96, 66)},
                },
            },
        }

        m.Answer = append(m.Answer, svcb)

        a := &dns.A {
            Hdr: dns.RR_Header{
                Name:   r.Question[0].Name,
                Rrtype: dns.TypeA,
                Class:  dns.ClassINET,
                Ttl:    300,
            },

            /* A: net.IPv4(45, 77, 96, 66), */
            A: net.IPv4(198, 51, 100, 1),
        }

        m.Extra = append(m.Extra, a)
    }

    err := w.WriteMsg(m)
    if err != nil {
        fmt.Println(err)
    }
}

func main() {
    var wg sync.WaitGroup
    wg.Add(1)

    dns.HandleFunc("nullroute.dev.", handleRequest)

    server := &dns.Server{Addr: ":53", Net: "udp"}
    go server.ListenAndServe()

    wg.Wait()
}