#181
Mar 6, 2022
Books
This week I read:
Volumes 4, 5, and 6 of So I’m a Spider, So What? by Okina Baba
All quite fun again, it’s nice to have something easy to read in the evenings after spending all my days working on my DNS server (see below). I guessed that the anime went up to the end of volume 6, but actually it stopped at the end of volume 5. And I think that was the right decision, volume 6 had a bunch of character development and worldbuilding (as well as action), and it would have been a stretch to fit all that into the show. A second season of the anime has been announced (no release date yet), so I’m looking forward to that.
Programming
My DNS server has moved on quite a bit since last week. Back then it couldn’t even recursively resolve names: now it can! Here’s a summary of the changes:
- Put it on GitHub
- Implemented recursive resolution
- Implemented a size-bounded LRU cache
- Added fuzz tests, using cargo-fuzz
- Added some benchmarks, to guide future improvements
- Added support for hosts files
- Made it actively reject unknown record types
- Added an option to specify which interface to bind to
- And improved the code quality in various ways: tightening up types, removing unsafe functions, adding unit tests, etc
I could actually use it for my home DNS now, as a replacement for my Pi-hole: the last blocker for using existing DNS blocklists was hosts file support and that’s there now.
Before I switch over though I want to add support for zone files, so that I can read the root.hints file. Currently I specify the IPs directly in a configuration file:
root_hints:
- "198.41.0.4" # a.root-servers.net
- "199.9.14.201" # b.root-servers.net
- "192.33.4.12" # c.root-servers.net
- "199.7.91.13" # d.root-servers.net
- "192.203.230.10" # e.root-servers.net
- "192.5.5.241" # f.root-servers.net
- "192.112.36.4" # g.root-servers.net
- "198.97.190.53" # h.root-servers.net
- "192.36.148.17" # i.root-servers.net
- "192.58.128.30" # j.root-servers.net
- "193.0.14.129" # k.root-servers.net
- "199.7.83.42" # l.root-servers.net
- "202.12.27.33" # m.root-servers.net
…but manually reading one configuration file to stick values into another isn’t a great workflow. They don’t change very often but, still, it’s not ideal.
Once I can read zone files, I’ll be able to use the root.hints file, and also specify custom records in the standard format, like:
$ORIGIN lan.
nyarlathotep 300 IN A 10.0.0.3
*.nyarlathotep 300 IN CNAME nyarlathotepSection 5 of RFC 1035 has the format. Annoyingly it’s not quite line-oriented: parentheses can be used to indicate a value extends over a multiple lines.
There are some other nice-to-haves, like dropping the config file entirely in favour of command-line arguments, improving logging, and reloading all the zone & hosts files with SIGHUP. But those can come later.