Fix AAAA queries returning A records

Author: Iridescent115

awldns/awldns.go

@@ -166,28 +166,56 @@ func (r *Resolver) dnsLocalDomainHandler(resp dns.ResponseWriter, req *dns.Msg)
 
 		switch qtype {
 		case dns.TypeA, dns.TypeAAAA, dns.TypeANY:
-			aRec := &dns.A{
+			if !found {
+				m.SetRcode(req, dns.RcodeNameError)
+				continue
+			}
+			appendIPAnswers(m, hostname, mappedIP, qtype)
+		}
+	}
+
+	processOwnResponse(req, resp, m)
+
+	_ = resp.WriteMsg(m)
+}
+
+func appendIPAnswers(m *dns.Msg, hostname string, mappedIP string, qtype uint16) {
+	ip := net.ParseIP(mappedIP)
+	if ip == nil {
+		return
+	}
+
+	if qtype == dns.TypeA || qtype == dns.TypeANY {
+		if ipv4 := ip.To4(); ipv4 != nil {
+			m.Answer = append(m.Answer, &dns.A{
 				Hdr: dns.RR_Header{
 					// we should return original name from the request as some clients expect that
 					Name:   hostname,
 					Rrtype: dns.TypeA,
 					Class:  dns.ClassINET,
 					Ttl:    defaultTTLSeconds,
 				},
-			}
-			if found {
-				// TODO: support ipv6
-				aRec.A = net.ParseIP(mappedIP).To4()
-			} else {
-				m.SetRcode(req, dns.RcodeNameError)
-			}
-			m.Answer = append(m.Answer, aRec)
+				A: ipv4,
+			})
 		}
 	}
 
-	processOwnResponse(req, resp, m)
-
-	_ = resp.WriteMsg(m)
+	if qtype == dns.TypeAAAA || qtype == dns.TypeANY {
+		if ip.To4() == nil {
+			if ipv6 := ip.To16(); ipv6 != nil {
+				m.Answer = append(m.Answer, &dns.AAAA{
+					Hdr: dns.RR_Header{
+						// we should return original name from the request as some clients expect that
+						Name:   hostname,
+						Rrtype: dns.TypeAAAA,
+						Class:  dns.ClassINET,
+						Ttl:    defaultTTLSeconds,
+					},
+					AAAA: ipv6,
+				})
+			}
+		}
+	}
 }
 
 func (r *Resolver) ptrv4Handler(resp dns.ResponseWriter, req *dns.Msg) {

awldns/awldns_test.go

@@ -68,6 +68,28 @@ func TestDNS(t *testing.T) {
 	}
 }
 
+func TestDNSAAAAQueryDoesNotReturnARecord(t *testing.T) {
+	a := require.New(t)
+	port := FindFreePort()
+	addr := fmt.Sprintf("127.0.0.1:%d", port)
+
+	resolver := NewResolver(addr)
+	defer resolver.Close()
+	// TODO: remove sleep. We need it because NewResolver starts servers in goroutines
+	time.Sleep(50 * time.Millisecond)
+
+	resolver.ReceiveConfiguration("", map[string]string{
+		"admin": "127.0.0.66",
+	})
+
+	req := new(dns.Msg)
+	req.SetQuestion("admin.awl.", dns.TypeAAAA)
+	resp, _, err := new(dns.Client).Exchange(req, addr)
+	a.NoError(err)
+	a.Equal(dns.RcodeSuccess, resp.Rcode)
+	a.Empty(resp.Answer)
+}
+
 func NewResolverClient(address string) *net.Resolver {
 	dialer := &net.Dialer{Timeout: time.Second}
 	return &net.Resolver{