Handshake state collision between parralel RoutineHandshake threads

[Jason A. Donenfeld]

Hi Laura,

I'm not sure this is actually a problem. The latest handshake message
should probably win the race. I don't see state machine or data
corruption here, but just one handshake interrupting another, which is
par for the course with WireGuard.

Or have I overlooked something important in the state machine implementation?

Jason