This is a pet project of mine to implement the STUN protocol in pure Rust. The goal is to learn a bit about the STUN protocol while also being able to provide sample code for those interested. As such, this code should not be considered production-ready.

Stun is an extensible protocol that utilizes UDP. This crate implements some of the basic Stun protocol, as well as hand-picked items of interest. The source material used can be found in the following RFCs:

• RFC 5389 defines the basics of the STUN protocol. The crate implements some of this RFC, including the stun header, and some attributes like XOR-MAPPED-ADDRESS and CHANGE-REQUEST. Other attributes such as MESSAGE-INTEGRITY are still to be implemented.
• RFC 5780 builds off of the prior RFC to define more attributes, as well as describes stateful workflows that a client can take with supported server. These operations are used to help test and learn about the characteristics of a NAT that the client is behind.
• RFC 5128 is an RFC which describes a bit more of the terminology used in RFC 5780. It doesn't actually define anything new related to STUN, but provides context for the results that RFC 5780 provides.

My end goal is to provide a sans-IO library that implements the procedures needed to perform operations as described in RFC 5780, such as determining a NAT mapping or filtering, binding lifetime discovery, etc. This would include both a client and server that could describe the needed operations, along with a sans-IO implementation of the various operations.