Networking: mDNS discovery

[kim]

Discovery should be a monoidal datatype instead of a trait, and yield an asynchronere stream of (PeerId, SocketAddr) pairs. One challenge is to deduplicate this stream, as mDNS will discover the same link local responders with every query.

Implementation wise, the crate situation isn’t great: the mdns crate looks ok, but only provides a client, libmdns only the responder side (with a futures 1 interface, which isn’t great). Others either seem to have native dependencies, or are in some way non-standard. A generic, high quality DNS library doesn’t seem to exist. Potentially the best strategy would be to steal the DNS types from libp2p, and inline them.

[massimiliano-mantione]

Potentially the best strategy would be to steal the DNS types from libp2p, and inline them.

If this is really the best strategy, maybe a second step would be:

• extracting them into a crate
• propose a pull request to libp2p so that it uses that crate
• if they accept it, let the libp2p maintainers also maintain that crate (they were maintaining the original code anyway)

[kim]

Ya, although I have somewhat little hope they would be interested in this. After a second look at mdns, I think it exports enough to build a responder. We can then ask the maintainer if they'd be interested to upstream that.

[kim]

#459