tree 5bf6680a772227388eca051c8517566e3749c7a3
parent 4a18022bda00b3d3b844471e7f5cf16b24455b68
author Jan Schär <jan@monogon.tech> 1722265301 +0200
committer Jan Schär <jan@monogon.tech> 1724238601 +0000

osbase/net/dns/forward: add DNS forward handler

This adds a DNS server handler for forwarding queries to upstream DNS
resolvers, with a built-in cache. The implementation is partially based
on CoreDNS. The proxy, cache and up packages are only lightly modified.
The forward package itself however is mostly new code. Unlike CoreDNS,
it supports changing upstreams at runtime, and has integrated caching
and answer order randomization.

Some improvements over CoreDNS:
- Concurrent identical queries only result in one upstream query.
- In case of errors, Extended DNS Errors are added to replies.
- Very large replies are not stored in the cache to avoid using too much
memory.

Change-Id: I42294ae4997d621a6e55c98e46a04874eab75c99
Reviewed-on: https://review.monogon.dev/c/monogon/+/3258
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI