if txt rdlength is 0, not read anymore

dns_test.go

@@ -71,6 +71,42 @@ func TestPackUnpack2(t *testing.T) {
 	}
 }
 
+func TestPackUnpack3(t *testing.T) {
+	m := new(Msg)
+	m.Extra = make([]RR, 2)
+	m.Answer = make([]RR, 1)
+	dom := "miek.nl."
+	rr := new(A)
+	rr.Hdr = RR_Header{Name: dom, Rrtype: TypeA, Class: ClassINET, Ttl: 0}
+	rr.A = net.IPv4(127, 0, 0, 1)
+
+	x1 := new(TXT)
+	x1.Hdr = RR_Header{Name: dom, Rrtype: TypeTXT, Class: ClassINET, Ttl: 0}
+	x1.Txt = []string{}
+
+	x2 := new(TXT)
+	x2.Hdr = RR_Header{Name: dom, Rrtype: TypeTXT, Class: ClassINET, Ttl: 0}
+	x2.Txt = []string{"heelalaollo"}
+
+	m.Extra[0] = x1
+	m.Extra[1] = x2
+	m.Answer[0] = rr
+	b, err := m.Pack()
+	if err != nil {
+		t.Log("Packing failed")
+		t.Fail()
+		return
+	}
+
+	var unpackMsg Msg
+	err = unpackMsg.Unpack(b)
+	if err != nil {
+		t.Log("UnPacking failed")
+		t.Fail()
+		return
+	}
+}
+
 func TestBailiwick(t *testing.T) {
 	yes := map[string]string{
 		"miek.nl": "ns.miek.nl",

msg.go

@@ -763,7 +763,7 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, err er
 				txt := make([]string, 0)
 				rdlength := off + int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
 			Txts:
-				if off == lenmsg { // dyn. updates, no rdata is OK
+				if off == lenmsg || rdlength == off { // dyn. updates, no rdata is OK
 					break
 				}
 				l := int(msg[off])