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package server
import (
"github.com/miekg/dns"
"log/slog"
)
func handleQuery(w dns.ResponseWriter, req *dns.Msg) {
if len(req.Question) == 0 {
m := new(dns.Msg)
m.SetRcode(req, dns.RcodeFormatError)
_ = w.WriteMsg(m)
return
}
resp := buildResponse(req)
if err := w.WriteMsg(resp); err != nil {
slog.Error("write response failed",
"err", err,
"qname", req.Question[0].Name,
"qtype", dns.TypeToString[req.Question[0].Qtype],
)
return
}
slog.Info("query served",
"qname", req.Question[0].Name,
"qtype", dns.TypeToString[req.Question[0].Qtype],
"rcode", dns.RcodeToString[resp.Rcode],
"client", w.RemoteAddr().String(),
)
}
func buildResponse(req *dns.Msg) *dns.Msg {
if len(req.Question) == 0 {
m := new(dns.Msg)
m.SetRcode(req, dns.RcodeFormatError)
return m
}
q := req.Question[0]
resp := new(dns.Msg)
resp.SetReply(req)
resp.Authoritative = false
if opt := req.IsEdns0(); opt != nil {
resp.SetEdns0(4096, false)
}
if q.Name == "example.com." && q.Qtype == dns.TypeA {
resp.Answer = []dns.RR{
&dns.A{
Hdr: dns.RR_Header{
Name: q.Name,
Rrtype: dns.TypeA,
Class: dns.ClassINET,
Ttl: 60,
},
A: []byte{127, 0, 0, 1},
},
}
} else {
resp.Rcode = dns.RcodeNameError
}
return resp
}
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