fix(kad): remove default IPFS DHT protocol name

[robin-rrt]

Description

Fix #5006

Notes & open questions

Added a parameter for protocol name.

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[dariusc93]

Instead of having a new field, we can make use of the protocol_config by using ProtocolConfig::set_protocol_names.

[thomaseizinger]

The current default is set here: https://github.com/robin-rrt/rust-libp2p/blob/c29a844506fe9eb8edb0526d5a4f2c1f2296b129/protocols/kad/src/protocol.rs#L167

That is what needs to be changed :)

[robin-rrt]

Just to understand. Do we want the Default implementation gone completely? And have a ProtocolConfig::new function?

[thomaseizinger]

Just to understand. Do we want the Default implementation gone completely? And have a ProtocolConfig::new function?

Yes, I think that is what @mxinden meant in #5006.

Now, I am wondering if we couldn't:

• Leave the Default implementation
• Make a manual default function that is marked as deprecated
• Introduce a new function that requires you to pass a protocol name

This might allow us to ship this as a backwards-compatible change. I haven't tested this though. We need to make sure it doesn't cause compile errors for users because of the default function name.

We can't mark the actual Default impl as deprecated but at least for users that call default manually, we can issue a warning. We should also deprecate the set_protocol_names function and refer users to the constructor instead.

[thomaseizinger]

Closing in favor of #5122.