Implement SSV Handshake Protocol

[diegomrsantos]

Issue Addressed

Implements #116

Proposed Changes

• Dependencies:

  • Updated dependencies in Cargo.toml including async-trait, quick-protobuf, serde_json, and thiserror.

• Handshake Protocol:

  • Added a new module handshake with multiple new files including README.md, codec.rs, envelope.proto, envelope.rs, mod.rs, and node_info.rs.

• Network Behaviour:

  • Enhanced behaviour.rs to include handshake::Behaviour and added a new field handshake to AnchorBehaviour.

• Network Implementation:

  • Enhanced network.rs:
  • Updated to use the Handshake Behaviour
  • Created DefaultNodeInfoProvider to provide NodeInfo.

Additional Info

There's a spec in README.md file

[jxs]

Hi Diego, thanks for starting this.
Left some comments

[jxs]

skimming through the NetworkBehaviour implementation, and without knowing much about the requirements I wonder if we can suffice our needs by just implementing the Codec trait and not needing to have request-response as a sub behaviour

[diegomrsantos]

What would this approach look like?

[jxs]

using the request-response Behaviour and then doing the validation envelope signing validation logic in the Codec implementation.
Does that make sense Diego?

[diegomrsantos]

Yes, having the validation in the codec is the way to go. About only one behavior, I'll need to think more about it.

[diegomrsantos]

I think it's nice to keep the behavior and centralize everything related to the handshake there, exposing only the events to the main behavior.

[dknopik]

Hey @diegomrsantos, hey @jxs,

thank you for your discussion in this PR.

You are both making a good case for your proposed variants. To better visualise the changes proposed by João (as I understand them), I implemented them here based on this PR.

To summarize the changes:

• Move decoding of NodeInfo to Codec. This, in my opinion, is a good idea. As you said, Diego, it is good to separate the coding and decoding logic from the rest of the logic. With this change, the conversion of NodeInfo to the "Entries"-based JSON format is moved to that separated codec logic. This is desirable if I understood your argument correctly.
• Do not use request_response::Behaviour as a sub behaviour, but as a top-level behaviour. This has, IMO, advantages and disadvantages. Handling the event on swarm level loosens encapsulation as said by Diego. I think this is a bit mitigated by moving the actual logic into the handshake module as I did. The advantage is reduced complexity by not having to impl NetworkBehaviour, and no risk of ignored Wakers or omitted events when poll is called.

Overall, I think I personally prefer this approach. Please take a look at my changes. Of course, I am fine with iterating more on the design. Looking forward to your thoughts.

[dknopik]

Thanks for implementing this, especially with the lack of a pre-existing spec! It's also great that we now have a spec.

We'll handle potential improvements separately.