156 lines
4.2 KiB
Markdown
156 lines
4.2 KiB
Markdown
# doh-forwarder
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A lightweight DNS-over-HTTPS (DoH) forwarder written in Rust.
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Accepts DNS queries over traditional DNS (UDP/TCP) and HTTP DoH ([RFC 8484](https://www.rfc-editor.org/rfc/rfc8484)), then forwards them upstream via DoH (HTTPS POST) to configurable resolvers.
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## Why?
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See [docs/story.md](docs/story.md) for the full context — why this exists, what already works, and where this project is headed.
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## Features
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- **Dual-protocol listener** — traditional DNS (UDP/TCP) + HTTP DoH endpoints
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- **RFC 8484 compliant** — GET (`?dns=base64url`) and POST (`application/dns-message`)
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- **Multiple upstreams** — configure several DoH resolvers
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- **Selection strategies** — round-robin or failover with automatic retry
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- **Environment overrides** — override config via env vars
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- **Graceful shutdown** — handles SIGINT and SIGTERM
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- **Health endpoint** — `GET /health`
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## Quick Start
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```bash
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# Build
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cargo build --release
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# Run with default config (DoH on :8800, DNS on :53530)
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./target/release/doh-forwarder
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# Run with a custom config
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./target/release/doh-forwarder --config /path/to/config.toml
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```
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## Configuration
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See [config/default.toml](config/default.toml):
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```toml
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[server]
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listen = "0.0.0.0:8800"
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[dns]
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listen = "0.0.0.0:53530"
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[upstream]
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resolvers = [
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{ name = "cloudflare", url = "https://cloudflare-dns.com/dns-query" },
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]
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strategy = "round-robin" # or "failover"
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```
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### Environment Variable Overrides
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| Variable | Description | Example |
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|---|---|---|
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| `DOH_LISTEN` | Override DoH server listen address | `0.0.0.0:8080` |
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| `DOH_UPSTREAM_STRATEGY` | Override upstream strategy | `failover` |
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| `DOH_UPSTREAM_RESOLVERS` | Comma-separated `name=url` pairs | `google=https://dns.google/dns-query,cf=https://cloudflare-dns.com/dns-query` |
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| `RUST_LOG` | Log level filter | `debug`, `doh_forwarder=trace` |
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## Usage
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### Point your system DNS at the forwarder
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```bash
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# /etc/resolv.conf
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nameserver 127.0.0.1
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# Then run the forwarder with [dns] listen = "127.0.0.1:53"
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```
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Or use `resolvectl` with systemd-resolved:
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```bash
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resolvectl dns eth0 127.0.0.1
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resolvectl dns-over-tls no # we handle encryption upstream
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```
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### DoH API
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**POST `/dns-query`** — raw DNS wire-format in body:
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```bash
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curl -X POST http://localhost:8800/dns-query \
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-H "Content-Type: application/dns-message" \
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-H "Accept: application/dns-message" \
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--data-binary @query.bin
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```
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**GET `/dns-query`** — base64url-encoded query parameter:
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```bash
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curl "http://localhost:8800/dns-query?dns=<base64url-encoded-query>"
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```
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**GET `/health`** — returns `ok`:
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```bash
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curl http://localhost:8800/health
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```
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### Upstream Strategies
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| Strategy | Behavior |
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|---|---|
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| `round-robin` | Distributes queries across resolvers in rotation |
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| `failover` | Tries resolvers in order; moves to the next on failure |
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## Project Structure
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```
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doh-forwarder/
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├── Cargo.toml
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├── config/
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│ └── default.toml # Default configuration
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├── docs/
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│ ├── plan.md # Project plan & milestones
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│ └── story.md # Why this project exists
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├── src/
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│ ├── main.rs # Entrypoint, server setup, graceful shutdown
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│ ├── lib.rs # Public API re-exports
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│ ├── config.rs # TOML config + env overrides
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│ ├── routes.rs # HTTP route handlers (/dns-query, /health)
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│ ├── dns/
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│ │ ├── mod.rs
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│ │ ├── query.rs # DNS query parsing
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│ │ ├── response.rs # DNS response building (SERVFAIL)
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│ │ └── listener.rs # UDP/TCP DNS listener
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│ └── upstream/
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│ ├── mod.rs
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│ └── doh_client.rs # DoH forwarding client (retry, strategies)
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├── tests/
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│ └── integration.rs # HTTP integration tests
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└── DEVELOP.md # Development rules & milestone tracking
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```
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## Development
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See [DEVELOP.md](DEVELOP.md) for development rules, coding standards, and milestone tracking.
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```bash
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# Run with auto-reload
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cargo install cargo-watch
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cargo watch -x run
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# Run tests
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cargo test
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# Lint & format
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cargo clippy -- -D warnings
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cargo fmt --check
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```
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## License
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MIT
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