gitignore CLAUDE.md and update README for async tokio

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -1 +1,2 @@
 /target
+CLAUDE.md

CLAUDE.md

@@ -1,59 +0,0 @@
-# CLAUDE.md
-
-This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
-
-## Overview
-
-A DNS forwarding/caching proxy in Rust. Serves local zone records from TOML config, caches upstream responses with TTL-based expiration, forwards unknown queries to an upstream resolver, and logs all queries with structured output.
-
-## Build & Run
-
-```bash
-cargo build                         # compile
-sudo cargo run                      # run with default config (dns_fun.toml)
-sudo cargo run -- path/to/config    # run with custom config path
-RUST_LOG=debug sudo cargo run       # verbose logging
-```
-
-Test with: `dig @127.0.0.1 google.com`
-
-No tests or linter configured.
-
-## Architecture
-
-```
-src/
-  lib.rs        # module declarations, Error/Result type aliases
-  main.rs       # startup, config load, UDP listen loop, request pipeline
-  buffer.rs     # BytePacketBuffer — 512-byte DNS wire format read/write
-  header.rs     # DnsHeader, ResultCode — 12-byte header bitfield parsing
-  question.rs   # DnsQuestion, QueryType — query section (A, NS, CNAME, MX, AAAA)
-  record.rs     # DnsRecord — resource record variants with read/write
-  packet.rs     # DnsPacket — top-level: header + questions + answers + authorities + resources
-  config.rs     # Config loading from TOML, zone map builder
-  cache.rs      # DnsCache — TTL-aware cache with lazy eviction
-  forward.rs    # forward_query() — sends query to upstream, build_servfail() — error response
-  stats.rs      # ServerStats — query counters and periodic summary
-```
-
-## Request Pipeline
-
-```
-Query → Parse → Log → Local Zones → Cache → Upstream Forward (+ cache result) → Log → Respond
-```
-
-## Config
-
-`dns_fun.toml` at project root. Sections: `[server]`, `[upstream]`, `[cache]`, `[[zones]]`. Falls back to sensible defaults if file is missing.
-
-## Logging
-
-Controlled via `RUST_LOG` env var. Default level: `info` (one structured line per query). `debug` adds response details. Stats summary every 1000 queries.
-
-## Key Details
-
-- Rust 2018 edition, deps: `serde`, `toml`, `log`, `env_logger`
-- DNS packet size limited to 512 bytes (standard UDP DNS)
-- `BytePacketBuffer::read_qname` handles label compression (pointer jumps)
-- `type Error = Box<dyn std::error::Error>` / `type Result<T>` aliased in `lib.rs`
-- Cache: TTL clamped between `min_ttl` and `max_ttl`, lazy eviction every 1000 queries

README.md

@@ -2,7 +2,7 @@
 
 A DNS forwarding/caching proxy written from scratch in Rust. Parses and serializes DNS wire protocol (RFC 1035), serves local zone records from TOML config, caches upstream responses with TTL-aware expiration, and logs every query with structured output.
 
-No async runtime, no DNS libraries — just `std::net::UdpSocket` and manual packet parsing.
+No DNS libraries — just `tokio::net::UdpSocket` and manual packet parsing. Each query is handled concurrently via `tokio::spawn`.
 
 ## Record Types
 
@@ -99,7 +99,7 @@ Stats summary (total, forwarded, cached, local, blocked, errors) logged every 10
 
 ```
 src/
-  main.rs       # startup, config load, UDP listen loop, request pipeline
+  main.rs       # async startup, tokio event loop, ServerCtx, per-query task spawn
   lib.rs        # module declarations, Error/Result type aliases
   buffer.rs     # BytePacketBuffer — 512-byte DNS wire format read/write
   header.rs     # DnsHeader, ResultCode
@@ -108,13 +108,14 @@ src/
   packet.rs     # DnsPacket — full DNS message parse/serialize
   config.rs     # TOML config loading, zone map builder
   cache.rs      # TTL-aware DNS response cache with lazy eviction
-  forward.rs    # upstream forwarding, SERVFAIL builder
+  forward.rs    # async upstream forwarding
   stats.rs      # query counters and periodic summary
 ```
 
 ## Dependencies
 
 ```toml
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "net", "time"] }
 toml = "0.8"
 serde = { version = "1", features = ["derive"] }
 log = "0.4"