Fix dcutr roles in holepunching #3171
Description
We did the opposite thing of what the spec says to do. This meant that we would fail to hole-punch with rust nodes because both sides would attempt to be the dialer.
The spec is a bit confusing since roles get flipped in the middle. But essentially:
- A connects to B.
- B initiates the
/libp2p/dcutrprotocol. - After synchronizing, A and B dial each other. A is the client and B is the server.
This means the side handling the stream is the client, and the side initiating the stream should be the server.
#3044 exposes a flag to enable the spec behavior, but it is default set to legacy behavior. There are no backwards compatible migrations in that PR.
To close this issue we should implement a backwards compatible change. One suggestion by Sukun is:
On the side that in the new code will be the Server, can we add a random wait time after which the server will switch the role to Client and initiate the security negotiation?