I've implemented a few protocols in rust (and plenty in go and other languages).

One thing others haven't mentioned that I like rust for in this space:

The typestate pattern makes it really nice to work with protocols that have state. You encode your state machine logic into types, and your transitions into methods with move semantics, and you have a nice way to make sure your higher level code is using your protocol library correctly.

Another nice thing is that you can keep the number of copies and allocations way down if you're careful about how you use your buffers.