Address miekg's comments

msg.go

@@ -921,8 +921,8 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
 				copy(msg[off:off+len(s)], s)
 				off += len(s)
 			case `dns:"octet"`:
-				var varstrTmp []byte
-				off, err = packOctetString(fv.String(), msg, off, varstrTmp)
+				bytesTmp := make([]byte, 0)
+				off, err = packOctetString(fv.String(), msg, off, bytesTmp)
 				if err != nil {
 					return lenmsg, err
 				}

zscan_rr.go

@@ -2197,8 +2197,6 @@ func setCAA(h RR_Header, c chan lex, o, f string) (RR, *ParseError, string) {
 	}
 	if len(s) > 1 {
 		return nil, &ParseError{f, "bad CAA Value", l}, ""
-	} else if len(s) == 0 {
-		rr.Value = ""
 	} else {
 		rr.Value = s[0]
 	}