Override protocol id prefix on GossipsubConfigBuilder

[bernardoaraujor]

Description

I need to be able to set the entire GossipSub's ProtocolId, not only the prefix.

Motivation

I'm working on a Rust implementation of Waku, an evolution of Ethereum Whisper: https://github.com/bernardoaraujor/waku-rs

At this point, I have a minimal working implementation of 11/WAKU2-RELAY, 13/WAKU2-STORE and 19/WAKU2-LIGHTPUSH.

When trying to connect it to the Nim reference implementation without success, I noticed the following messages on the Nim logs:

DBG 2022-06-15 18:23:17.558-03:00 no handlers                                topics="libp2p multistream" tid=77736 file=multistream.nim:173 conn=12D*PH8vPd:62aa4dc5649138700bc0af39 protocol=//vac/waku/relay/2.0.0/1.1.0
DBG 2022-06-15 18:23:17.558-03:00 Could not establish send connection        topics="libp2p pubsubpeer" tid=77736 file=pubsubpeer.nim:205 msg="Unable to select sub-protocol @[\"/vac/waku/relay/2.0.0\", \"/vac/waku/relay/2.0.0\"]

where protocol=//vac/waku/relay/2.0.0/1.1.0 is clearly not what I intended with RELAY_PROTOCOL_ID.

It turns out that's a result of GossipsubConfigBuilder::default().protocol_id_prefix(RELAY_PROTOCOL_ID), which uses RELAY_PROTOCOL_ID as a mere prefix for ProtocolId, adding extra / and /1.1.0.

Requirements

A way to set ProtocolId on GossipSub without prefix logic.

Open questions

• What is the feasibility of this feature?
• Are there any reasons not to have this feature on GossipSub?

Are you planning to do it yourself in a pull request?

Maybe. I would probably need some guidance.

[mxinden]

Hi @bernardoaraujor,

Thanks for the detailed feature request.

Are there any reasons not to have this feature on GossipSub?

I don't see a reason why not to support your use-case.

It turns out that's a result of GossipsubConfigBuilder::default().protocol_id_prefix(RELAY_PROTOCOL_ID), which uses RELAY_PROTOCOL_ID as a mere prefix for ProtocolId, adding extra / and /1.1.0.

How about adding an additional method e.g. GossipsubConfigBuilder::protocol_id to be able to set the whole id?

Maybe. I would probably need some guidance.

Great. I am happy to help.

[mxinden]

Closing here with #2718 merged.