Add webrtc

[ckousik]

Adds an x-webrtc protocol which holds the 32 byte hex encoded DTLS fingerprint received by the server. This is based on melekes/rust-multiaddr@c88f5f4 and is for supporting the Go implementation of the spec described in libp2p/specs#412 .

[marten-seemann]

Wasn't the plan to use /webrtc/certhash/xxx?

[mxinden]

Wasn't the plan to use /webrtc/certhash/xxx?

👍 Followed up on https://github.com/libp2p/specs/pull/412/files#r917573385.

[ckousik]

@mxinden I've implemented /webrtc/certhash/xxx in https://github.com/libp2p/go-libp2p/pull/1655/files#diff-95f3f7953b6b10bfc25508238854e4e3119283beebe3789d7a5268827d111454R125 . Will update this code too.

[marten-seemann]

LGTM.

Can you add the code point to https://github.com/multiformats/multiaddr?

[marten-seemann]

CI is unhappy about this PR. I think you'll need to run gofmt.

[ckousik]

@marten-seemann Seems like 0x115 (277) is already used by p2p-stardust https://github.com/multiformats/multiaddr/blob/master/protocols.csv#L33 . Should I change the code for webrtc to 280 or some other nearby number?

[marten-seemann]

Yes, makes sense. Just pick a number.

[ckousik]

LGTM.

Can you add the code point to https://github.com/multiformats/multiaddr?

Made a PR multiformats/multiaddr#131 . These should be good to merge.