Convert an RR to its unknown representation

dns.go

@@ -207,3 +207,20 @@ func zoneMatch(pattern, zone string) (ok bool) {
 	}
 	return
 }
+
+// ToRFC3597 converts a known RR to the unknown RR representation
+func ToRFC3597(r RR) *RFC3597 {
+	buf := make([]byte, r.Len()*2)
+	off, err := PackStruct(r, buf, 0)
+	if err != nil {
+		return nil
+	}
+	buf = buf[:off]
+	rawSetRdlength(buf, 0, off)
+	u := new(RFC3597)
+	_, err = UnpackStruct(u, buf, 0)
+	if err != nil {
+		return nil
+	}
+	return u
+}

dns_test.go

@@ -152,3 +152,11 @@ func TestCompressLenght(t *testing.T) {
 		t.Fatalf("Should be equal")
 	}
 }
+
+func TestToRFC3597(t *testing.T) {
+	a, _ := NewRR("miek.nl. IN A 10.0.1.1")
+	x := ToRFC3597(a)
+	if x.String() != `miek.nl.	3600	IN	A	\# 4 0a000101` {
+		t.Fail()
+	}
+}