Batch 1 - Crash/data corruption:
- Add nil/empty config guards in server and app
- Protect against fasthttp buffer mutation in logging
- Ensure mimeutil falls back before caching empty MIME
- Make proxy health checker and resolver tolerate nil cfg
- Prevent Lua EMERG/ALERT/CRIT log levels from killing process
Batch 2 - Concurrency/race conditions:
- Add focused race tests for compression pool, ssl/ocsp,
server proxies slice, Lua timer cancel, and TCP socket connect
- Fix Lua timer active race and socket ConnectAsync race
Batch 3 - Resource leaks/functional damage:
- Track and stop rate limiter cleanup goroutines on shutdown
- Add tests for proxy connection count leaks, server pool deadlock,
Linux sendfile integrity, WebSocket frame data loss,
stream UDP stop deadlock, and upstream name mismatch
- Fix stream ListenTCP/upstream lookup and UDP shutdown
Batch 4 - High severity technical debt:
- Add nil guard in security headers middleware
- Validate sliding window divisor and add tests
- Protect static handler fields with existing RWMutex
- Avoid mutating live HostClient.Addr on DNS updates
- Fix slow start Start/Stop and resolver restart
- Initialize variable fallback context maps
- Add tests for request_id/time_local and logging file handle close
Also:
- Relax integration variable performance threshold under race detector
- Update benchmark plan docs for new stream ListenTCP signature
Verification:
- make test: pass
- go test -race -count=1 ./internal/...: pass
- make lint: 0 issues
- make build: success
- Fix handleConnection to use addr parameter for direct upstream map
lookup instead of always selecting the first upstream
- Add Server.Stop() for graceful shutdown with listener closing, UDP
server cleanup, health checker termination, and goroutine joining
- Add shutdownStream() to App and call it in SIGTERM/SIGQUIT/SIGUSR2
signal handlers to prevent goroutine and port leaks on shutdown
