- * If we've looked at every character in
- * the message, this pointer will make
- * us look at some character again,
- * which means we're looping.
+ * This must move backwards in the packet.
+ * No RFC explicitly says that, but BIND's
+ * name decompression code requires it,
+ * as a way of preventing infinite loops
+ * and other bad behavior, and it's probably
+ * what was intended (compress by pointing
+ * to domain name suffixes already seen in
+ * the packet).