rm-hull / dot-block / 27371927599

61%

Build Type

push

github

Committed by rm-hull

Commit Message

fix: resolve cache hit ratio regression when ECS is enabled

The DNS cache hit ratio dropped to zero when EDNS0 Client Subnet (ECS) was enabled because of a key mismatch in the upstream resolution logic.

In resolveUpstream, the dispatcher was using the subnet-aware cache key (which includes the client subnet) to retrieve answers from the local answerMap. However, the answerMap was populated using subnet-neutral keys (domain and type only). This resulted in cache lookups within resolveUpstream always failing, meaning d.cache.Set was never called and no responses were cached.

This commit fixes the issue by:
- Using a subnet-neutral key for lookups in the answerMap within resolveUpstream.
- Continuing to use the subnet-aware key when storing the results in the DNS cache to maintain location-aware caching.
- Adding TestDNSDispatcher_HandleDNSRequest_CacheHit_ECS to internal/forwarder/dispatcher_test.go to prevent this regression.
- Improving mockIPResponseWriter in tests to include the WrittenMsg field for easier assertion of response contents.

Coverage Stats

4 of 4 new or added lines in 1 file covered. (100.0%)

11 existing lines in 1 file now uncovered.

1383 of 2258 relevant lines covered (61.25%)

780.45 hits per line