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dns: return empty reply for non-A queries for DNS hostnames

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instead of NXDOMAIN, which is incorrect
This commit is contained in:
Michael Stapelberg 2019-01-01 17:21:50 +01:00
parent c7be96ac2e
commit 92d995bf79
2 changed files with 29 additions and 3 deletions
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20
internal/dns/dns.go
View File

@ -16,6 +16,7 @@
package dns
import (
"errors"
"log"
"net"
"net/http"
@ -193,7 +194,9 @@ func isLocalInAddrArpa(q string) bool {
return local
}
func (s *Server) resolve(q dns.Question) (dns.RR, error) {
var sentinelEmpty = errors.New("no answers")
func (s *Server) resolve(q dns.Question) (rr dns.RR, err error) {
if q.Qclass != dns.ClassINET {
return nil, nil
}
@ -205,11 +208,16 @@ func (s *Server) resolve(q dns.Question) (dns.RR, error) {
return dns.NewRR(q.Name + " 3600 IN A 127.0.0.1")
}
}
if q.Qtype == dns.TypeA {
if q.Qtype == dns.TypeA ||
q.Qtype == dns.TypeAAAA ||
q.Qtype == dns.TypeMX {
name := strings.TrimSuffix(q.Name, ".")
name = strings.TrimSuffix(name, "."+s.domain)
if host, ok := s.hostByName(name); ok {
return dns.NewRR(q.Name + " 3600 IN A " + host)
if q.Qtype == dns.TypeA {
return dns.NewRR(q.Name + " 3600 IN A " + host)
}
return nil, sentinelEmpty
}
}
if q.Qtype == dns.TypePTR {
@ -232,6 +240,12 @@ func (s *Server) handleInternal(w dns.ResponseWriter, r *dns.Msg) {
}
rr, err := s.resolve(r.Question[0])
if err != nil {
if err == sentinelEmpty {
m := new(dns.Msg)
m.SetReply(r)
w.WriteMsg(m)
return
}
log.Fatal(err)
}
if rr != nil {

12
internal/dns/dns_test.go
View File

@ -208,6 +208,18 @@ func TestHostnameDHCP(t *testing.T) {
t.Fatalf("unexpected response record: got %q, want %q", got, want)
}
})
t.Run("AAAA", func(t *testing.T) {
m := new(dns.Msg)
m.SetQuestion(hostname+".lan.", dns.TypeAAAA)
s.Mux.ServeDNS(r, m)
if got, want := r.response.MsgHdr.Rcode, dns.RcodeSuccess; got != want {
t.Fatalf("unexpected rcode: got %v, want %v", got, want)
}
if got, want := len(r.response.Answer), 0; got != want {
t.Fatalf("unexpected number of answers: got %d, want %d", got, want)
}
})
}
func TestLocalhost(t *testing.T) {