352a83bbb0
Within Firezone, there are multiple components that deal with DNS queries. Two of those components are the `l4-udp-dns-server` and `l4-tcp-dns-server`. Both of them are responsible for receiving DNS queries on layer 4, i.e. UDP or TCP. In other words, they do _not_ operate on an IP level (which would be layer 3) but instead use `UdpSocket` and `TcpListener` to receive queries and sent back responses. Right now, the interfaces of these crates are designed for the usecase of receiving forwarded DNS queries from the CLient on the Gateway's TUN device. This is a special-case of DNS resolution. When receiving a TXT or SRV query for a domain that is covered by a DNS resources, Firezone Client's will forward that query to the corresponding Gateway and resolve it in its network context. SRV and TXT records are commonly used for service discovery and as such, should be resolved in the network context of the service, i.e. the site that assigned to the resource. For that usecase, it made sense to allow each DNS server to listen on 1 IPv4 and 1 IPv6 address. Since then, our event-loop has evolved a bit, being able to handle multiple inputs at once. As such, we can simplify the API of these crates to only listen on a single address and instead create multiple instances of them inside `Io`. Depending on how the design of our DNS implementation for the Clients evolves, this may be used to listen on multiple IPs later (e.g. from the `127.0.0.0/8` subnet). Related: #8263
Rust development guide
Firezone uses Rust for all data plane components. This directory contains the Linux and Windows clients, and low-level networking implementations related to STUN/TURN.
We target the last stable release of Rust using rust-toolchain.toml.
If you are using rustup, that is automatically handled for you.
Otherwise, ensure you have the latest stable version of Rust installed.
Reading Client logs
The Client logs are written as JSONL for machine-readability.
To make them more human-friendly, pipe them through jq like this:
cd path/to/logs # e.g. `$HOME/.cache/dev.firezone.client/data/logs` on Linux
cat *.log | jq -r '"\(.time) \(.severity) \(.message)"'
Resulting in, e.g.
2024-04-01T18:25:47.237661392Z INFO started log
2024-04-01T18:25:47.238193266Z INFO GIT_VERSION = 1.0.0-pre.11-35-gcc0d43531
2024-04-01T18:25:48.295243016Z INFO No token / actor_name on disk, starting in signed-out state
2024-04-01T18:25:48.295360641Z INFO null
Benchmarking on Linux
The recommended way for benchmarking any of the Rust components is Linux' perf utility.
For example, to attach to a running application, do:
- Ensure the binary you are profiling is compiled with the
releaseprofile. sudo perf record -g --freq 10000 --pid $(pgrep <your-binary>).- Run the speed test or whatever load-inducing task you want to measure.
sudo perf script > profile.perf- Open profiler.firefox.com and load
profile.perf
Instead of attaching to a process with --pid, you can also specify the path to executable directly.
That is useful if you want to capture perf data for a test or a micro-benchmark.