dns-thingy

A minimal work-in-progress content filter system based on DNS similar to AdguardHome.

This project serves the purpose to learn more about the Domain Name System.

This workspace project consists of the following subcrates in crates:

• dns - a library crate for constructing and consuming DNS packets (currently only supports DNS over UDP)
• dns-client - a minimal DNS client that wraps dns to test resolving A and CNAME records for a given domain name and optionally given upstream DNS server (default 1.1.1.1)
• dns-block - a single-threaded DNS server that selectively proxies queries to 1.1.1.1 or blocks blacklisted domains based on a list
• dns-block-threaded - a multi-threaded version of dns-block
• dns-block-tokio - an async version of dns-block based on Tokio (not fully async at this point, as it uses blocking parts of dns)

How to run

You can either clone and cargo install -p dns-block-tokio and then run dns-block-tokio or use Docker (only linux/amd64 images are being built by CI at the moment) by pulling the image docker run -p 53000:53000 maximumstock2/dns-thingy:latest which runs dns-block-tokio inside the container on port 53000 and makes it available on your host machine on port 53000 as well. Optionally, use -p 53:53000 to map your local port 53 to be used, but that most likely requires root privileges.

At that point dns-thingy can answer DNS queries, ie. dig google.com @127.0.0.1 @53000.

TODO

• feat: add custom blocking rules
• feat: cache records according to answer TTL
• feat: implement more record types
• api: request builder for DNS queries & responses
• perf: optimise buffer allocation
• bench: don't actually send out queries during benchmarks to eliminate network & upstream performance from the benchmark
• fix: cant pipe through dns query as we need to recursively query upstream but downstream might not have set that flag

Performance Evaluation

I'd like to use this opportunity to create a performance benchmark setup to get a better feeling for performance characteristics of different implementation strategies, such as:

1. Single-threaded blocking (current implementation of dns-block)
2. Multi-threaded blocking
3. Asynchronous based on Tokio

See Benchmarks for further information.