I was misled by
doc/design/compression into thinking that might
be a good place to do some
rbt hacking, but no! I was misled!
It soon became clear that although the design documentation had not matched the code since December 2000, there was still a lot of weird complexity in the dns_compress API designed to cope with multiple compression methods, even though the IETF gave up on that idea over 20 years ago.
So, it's a good target for a little bit of modernization. And this patch set also removes a lot more than 500 lines of code and docs.