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A high-performance DNS forwarding server with caching, IP speed testing, hot-reload configuration, and Prometheus metrics.
- UDP + TCP DNS serving with SO_REUSEPORT
- LRU cache with DNS TTL
- Upstream failover (sequential retry), automatic TCP fallback on UDP truncation
- Upstream health checks + circuit breaker (cooldown after N consecutive failures, half-open auto-recovery)
- Background concurrent TCP-connect speed testing, returns only the fastest IP on cache hit
- Hotspot domain warm-up on startup (concurrent queries, populates cache + triggers speed test)
- Domain blacklist (exact + suffix matching)
- Domain overrides (static A record responses)
- Hotspot tracking + persistence
- Hot-reload configuration (fsnotify + debounce)
- Prometheus metrics at
/metrics - Graceful shutdown (SIGINT/SIGTERM)
chara/
├── cmd/chara/ # Entry point
├── server/ # DNS server (UDP + TCP)
├── resolver/ # DNS resolution (speed filtering, hotspot warm-up)
├── forwarder/ # DNS forwarding
├── upstream/ # Upstream health checks + circuit breaker
├── cache/ # DNS cache
├── hotspot/ # Hotspot tracking
├── speedtest/ # IP speed testing
├── config/ # Configuration management
├── reloader/ # Hot-reload
├── metrics/ # Prometheus metrics
├── config.json # Example configuration
└── Dockerfile # Production image
go mod tidy go build -o chara ./cmd/chara sudo ./chara -c config.json
Test:
dig @127.0.0.1 -p 8053 example.com
curl http://127.0.0.1:9153/metrics | grep chara_docker build -t chara .
docker run -p 8053:8053/udp -p 8053:8053/tcp -p 9153:9153 charaOpen the project in VS Code and select "Reopen in Container" to use the pre-configured Go development environment.
See LICENSE for details.