Add TestDynamicUpdateParsing test

parse_test.go

@@ -1160,3 +1160,18 @@ func TestMalformedPackets(t *testing.T) {
 		//		println(msg.String())
 	}
 }
+
+func TestDynamicUpdateParsing(t *testing.T) {
+	prefix := "example.com. IN "
+	// TODO(miek): extend to all types.
+	//for _, typ := range TypeToString {
+	for _, typ := range []string{"PTR", "A"} {
+		r, e := NewRR(prefix + typ)
+		if e != nil {
+			t.Log("failure to parse: " + prefix + typ)
+			t.Fail()
+		} else {
+			t.Logf("parsed: %s", r.String())
+		}
+	}
+}

zscan_rr.go

@@ -265,6 +265,9 @@ func setA(h RR_Header, c chan lex, f string) (RR, *ParseError) {
 	rr.Hdr = h
 
 	l := <-c
+	if l.length == 0 { // Dynamic updates.
+		return rr, nil
+	}
 	rr.A = net.ParseIP(l.token)
 	if rr.A == nil {
 		return nil, &ParseError{f, "bad A A", l}
@@ -277,6 +280,9 @@ func setAAAA(h RR_Header, c chan lex, f string) (RR, *ParseError) {
 	rr.Hdr = h
 
 	l := <-c
+	if l.length == 0 {
+		return rr, nil
+	}
 	rr.AAAA = net.ParseIP(l.token)
 	if rr.AAAA == nil {
 		return nil, &ParseError{f, "bad AAAA AAAA", l}
@@ -310,6 +316,9 @@ func setPTR(h RR_Header, c chan lex, o, f string) (RR, *ParseError) {
 
 	l := <-c
 	rr.Ptr = l.token
+	if l.length == 0 { // dynamic update rr.
+		return rr, nil
+	}
 	if l.token == "@" {
 		rr.Ptr = o
 		return rr, nil