added ns record support

record.go

@@ -56,5 +56,12 @@ func (r *Record) Validate(typ Type) error {
 		}
 	}
 
+	// validate NS addresses
+	if typ == NS {
+		if !IsDomain(r.Address, true) {
+			return errors.Errorf("invalid ns name: %s", r.Address)
+		}
+	}
+
 	return nil
 }

record_test.go

@@ -72,6 +72,15 @@ func TestRecordValidate(t *testing.T) {
 			typ: TXT,
 			rec: Record{Data: []string{"foo"}},
 		},
+		{
+			typ: NS,
+			rec: Record{Address: "foo.com"},
+			err: "invalid ns name: foo.com",
+		},
+		{
+			typ: NS,
+			rec: Record{Address: "foo.com."},
+		},
 	}
 
 	for i, item := range table {

server.go

@@ -279,6 +279,8 @@ func (s *Server) handler(w dns.ResponseWriter, rq *dns.Msg) {
 	// prepare extra set
 	var extra []Set
 
+	// TODO: Lookup glue records for NS records?
+
 	// lookup extra sets
 	for _, set := range answer {
 		for _, record := range set.Records {
@@ -323,6 +325,16 @@ func (s *Server) handler(w dns.ResponseWriter, rq *dns.Msg) {
 		})
 	}
 
+	// check if NS query
+	if typ == NS {
+		// move answers
+		rs.Ns = rs.Answer
+		rs.Answer = nil
+
+		// no authoritative response for other zone in NS queries
+		rs.Authoritative = false
+	}
+
 	// write message
 	s.writeMessage(w, rq, rs)
 }
@@ -490,6 +502,11 @@ func (s *Server) convert(query string, zone *Zone, set Set) []dns.RR {
 				Hdr: header,
 				Txt: record.Data,
 			})
+		case NS:
+			list = append(list, &dns.NS{
+				Hdr: header,
+				Ns:  dns.Fqdn(record.Address),
+			})
 		}
 	}
 

server_test.go

@@ -277,6 +277,20 @@ func TestServer(t *testing.T) {
 				}, nil
 			}
 
+			// handle other
+			if name == "other" {
+				return []Set{
+					{
+						Name: "other.newdns.256dpi.com.",
+						Type: NS,
+						Records: []Record{
+							{Address: "ns1.example.com."},
+							{Address: "ns2.example.com."},
+						},
+					},
+				}, nil
+			}
+
 			return nil, nil
 		},
 	}
@@ -1016,13 +1030,50 @@ func conformanceTests(t *testing.T, proto, addr string) {
 		}, ret)
 	})
 
+	t.Run("SubNS", func(t *testing.T) {
+		ret, err := Query(proto, addr, "other.newdns.256dpi.com.", "NS", nil)
+		assert.NoError(t, err)
+		equalJSON(t, &dns.Msg{
+			MsgHdr: dns.MsgHdr{
+				Response:      true,
+				Authoritative: false,
+			},
+			Question: []dns.Question{
+				{Name: "other.newdns.256dpi.com.", Qtype: dns.TypeNS, Qclass: dns.ClassINET},
+			},
+			Ns: []dns.RR{
+				&dns.NS{
+					Hdr: dns.RR_Header{
+						Name:     "other.newdns.256dpi.com.",
+						Rrtype:   dns.TypeNS,
+						Class:    dns.ClassINET,
+						Ttl:      300,
+						Rdlength: 14,
+					},
+					Ns: "ns1.example.com.",
+				},
+				&dns.NS{
+					Hdr: dns.RR_Header{
+						Name:     "other.newdns.256dpi.com.",
+						Rrtype:   dns.TypeNS,
+						Class:    dns.ClassINET,
+						Ttl:      300,
+						Rdlength: 6,
+					},
+					Ns: "ns2.example.com.",
+				},
+			},
+		}, ret)
+	})
+
 	t.Run("NoExactRecord", func(t *testing.T) {
 		assertMissing(t, proto, addr, "ip4.newdns.256dpi.com.", "CNAME", dns.RcodeSuccess)
 		assertMissing(t, proto, addr, "ip6.newdns.256dpi.com.", "CNAME", dns.RcodeSuccess)
 		assertMissing(t, proto, addr, "ip4.newdns.256dpi.com.", "AAAA", dns.RcodeSuccess)
 		assertMissing(t, proto, addr, "ip6.newdns.256dpi.com.", "A", dns.RcodeSuccess)
 		assertMissing(t, proto, addr, "mail.newdns.256dpi.com.", "A", dns.RcodeSuccess)
 		assertMissing(t, proto, addr, "text.newdns.256dpi.com.", "A", dns.RcodeSuccess)
+		assertMissing(t, proto, addr, "ip4.newdns.256dpi.com.", "NS", dns.RcodeSuccess)
 	})
 
 	t.Run("NoExistingRecord", func(t *testing.T) {
@@ -1031,6 +1082,7 @@ func conformanceTests(t *testing.T, proto, addr string) {
 		assertMissing(t, proto, addr, "missing.newdns.256dpi.com.", "CNAME", dns.RcodeNameError)
 		assertMissing(t, proto, addr, "missing.newdns.256dpi.com.", "MX", dns.RcodeNameError)
 		assertMissing(t, proto, addr, "missing.newdns.256dpi.com.", "TXT", dns.RcodeNameError)
+		assertMissing(t, proto, addr, "missing.newdns.256dpi.com.", "NS", dns.RcodeNameError)
 	})
 
 	t.Run("TruncatedResponse", func(t *testing.T) {

type.go

@@ -21,11 +21,14 @@ const (
 
 	// TXT records return arbitrary text data.
 	TXT = Type(dns.TypeTXT)
+
+	// NS records delegate names to other name servers.
+	NS = Type(dns.TypeNS)
 )
 
 func (t Type) valid() bool {
 	switch t {
-	case A, AAAA, CNAME, MX, TXT:
+	case A, AAAA, CNAME, MX, TXT, NS:
 		return true
 	default:
 		return false