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For DNS resources, the Gateway maintains a per-peer NAT table from the client-assigned proxy IPs to the real IPs of the domain. Whenever the Client re-queries a DNS resource domain locally, we asynchronously ping the Gateway to also re-query said domain. This allows us to detect changes in the DNS records of DNS resources. To avoid breaking existing connections, the mapping between proxy IPs and real IPs is currently not updated if there are any active UDP or TCP flows for a proxy IP. This logic turns out to be unnecessarily restrictive as TCP flows can linger around for up to 2h before they timeout if they are not closed with a TCP RST. What we really need to do is always update the mapping of proxy IP <> real IP but honor existing NAT table entries when we route packets before creating new ones. This ensures that an existing connection to a previously resolved IP remains intact, even if a later DNS response for the same domain updates the mapping. At the same time, new connections (i.e. with a different source port) will immediately use the new destination IP.
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.