632dfdd888
This patch series adds support for IPv6 allocations. If not specified otherwise in the ALLOCATE request, clients will get an IP4 allocation. They can also request an IPv6 address or an additional IPv6 address in addition to their IPv4 address. Either of those is only possible if the relay actually has a listening socket for the requested address family. The CLI is designed such that the user can either specify IP4, IP6 or both of them. The `Server` component handles all of this logic and responds with either a successful allocation response or an Address Family Not Supported error (see https://www.rfc-editor.org/rfc/rfc8656#name-stun-error-response-codes). Multiple refactorings were necessary to achieve this design, they are all extracted into separate PRs: Depends-On: #1831. Depends-On: #1832. Depends-On: #1833. --------- Co-authored-by: Jamil <jamilbk@users.noreply.github.com>
relay
This crate houses a minimalistic STUN & TURN server.
Features
We aim to support the following feature set:
- STUN binding requests
- TURN allocate requests
- TURN refresh requests
- TURN channel bind requests
- TURN channel data requests
Relaying of data through other means such as DATA frames is not supported.
Building
You can build the server using: cargo build --release --bin relay
Running
For an up-to-date documentation on the available configurations options and a detailed help text, run cargo run --bin relay -- --help.
All command-line options can be overridden using environment variables.
Those variables are listed in the --help output at the bottom of each command.
The relay listens on port 3478.
This is the standard port for STUN/TURN and not configurable.
Additionally, the relay needs to have access to the port range 49152 - 65535 for the allocations.
Portal connection
When given a portal endpoint, the relay will connect to it and wait for an init message before commencing relay operations.
Design
The relay is designed in a sans-IO fashion, meaning the core components do not cause side effects but operate as pure, synchronous state machines. They take in data and emit commands: wake me at this point in time, send these bytes to this peer, etc.
This allows us to very easily unit-test all kinds of scenarios because all inputs are simple values.
The main server runs in a single task and spawns one additional task for each allocation. Incoming data that needs to be relayed is forwarded to the main task where it gets authenticated and relayed on success.