Context

In the P2P service, we define a CodecTrait that can be defined for any struct implementing both GossipsubCodec and RequestResponse::Codec. See
See

However, this trait only defines functions that are relevant to the RequestResponse protocol, namely iterating over all protocols available. Furthermore, it constrains the types of messages sent via GossipSub or Request/Response to be the same, which is unnecessary coupling between the two.

Acceptance criteria

The NetworkCodec trait is removed from the codebase, and the FuelService is refactored to not use this codec.

Relevant files:

• Definition of the NetworkCodec trait: https://github.com/FuelLabs/fuel-core/blob/release/v0.40.0/crates/services/p2p/src/codecs.rs
• Usage of the NetworkCodec::get_req_res_protocol function in the FuelService:

  fuel-core/crates/services/p2p/src/behavior.rs

  Line 116 in eea8c60

  core::iter::once((codec.get_req_res_protocol(), ProtocolSupport::Full));

• Implementation of the NetworkCodec trait for the PostcardCodec:

  fuel-core/crates/services/p2p/src/codecs/postcard.rs

  Line 163 in eea8c60

  impl NetworkCodec for PostcardCodec {