blaze-dns

A full recursive DNS resolver implementation in Rust using tokio for asynchronous I/O. Starts resolution from root servers and follows the DNS hierarchy down to authoritative servers.

Features

• Full Recursive Resolution: Queries root servers, follows NS referrals through TLD and authoritative servers
• Complete DNS Protocol: Implements RFC 1035 with support for A, AAAA, CNAME, MX, TXT, NS, SOA, and PTR records
• Glue Record Handling: Properly extracts IP addresses from additional sections
• Out-of-Bailiwick Resolution: Recursively resolves nameservers when glue records aren't provided
• CNAME Following: Automatically follows CNAME chains to final answers
• Dual Protocol: Handles both UDP (primary) and TCP (for large responses)
• High Performance: Built with tokio for efficient concurrent request handling
• Smart Caching: LRU cache with TTL respect and negative caching
• Security: Transaction ID randomization, loop detection, input validation
• Observability: Structured logging with tracing

How It Works

Unlike forwarding DNS servers that delegate to upstream resolvers, this resolver implements the full iterative resolution process:

1. Start with queries to root servers (a-m.root-servers.net)
2. Follow NS referrals to TLD servers (.com, .org, etc.)
3. Continue following referrals to authoritative servers
4. Cache results at each level for performance

Usage

cargo run

The server will start on 0.0.0.0:5454 by default.

Configuration

Edit config.toml to customize settings:

[server]
bind_address = "0.0.0.0:5454"

[cache]
max_size = 10000

Testing

# Run all tests
cargo test

# Test with dig
dig @127.0.0.1 -p 5454 example.com

# See the resolution path
RUST_LOG=debug cargo run
# Then query to see it walk from root → TLD → authoritative

Performance

Benchmarked on Apple Silicon (M-series):

Operation	Time	Notes
Parse simple query	226 ns	RFC 1035 message parsing
Parse deep domain	544 ns	a.b.c.d.e.f.example.com
Serialize response (5 answers)	720 ns	With compression
Cache get (hit)	303 ns	LRU cache lookup
Cache get (miss)	64 ns	Fast negative lookup
Full cycle (10 answers)	3.98 µs	Parse + serialize
Full cycle (50 answers)	17.2 µs	Large response handling

Benchmarks

Run performance benchmarks using Criterion:

# Run all benchmarks
cargo bench

# Run specific benchmark group
cargo bench parse
cargo bench cache

# View detailed HTML reports with graphs
open target/criterion/report/index.html

Benchmarks cover:

• DNS message parsing (simple and complex domains)
• DNS message serialization
• Cache operations (put, get hit/miss, LRU eviction)
• Different message sizes (1-50 answers)
• Multiple query types (A, AAAA, CNAME, MX, TXT, NS)
• Domain name compression

Architecture

Client Query
    ↓
Cache Check
    ↓ (miss)
Root Servers (a-m.root-servers.net)
    ↓ (NS referral)
TLD Servers (.com servers)
    ↓ (NS referral)
Authoritative Servers (example.com servers)
    ↓ (answer)
Cache & Return