Automatic route selection for least latency

[PoneyClairDeLune]

Search for the route with the least overall latency for all peers. If the indirect route found has a latency lower than direct connection (or if the peer cannot be reached directly), use the indirect route instead.

[PoneyClairDeLune]

So some ideas.

Each peer listens to a random UDP port within the meshed network, which is used for latency probing. A ping is conducted on connection establishments, testing latency while signalling completeness of route establishments. After that, latency tests are conducted at random intervals.

Each peer will report the latency list at regular intervals, but only the N₁ (3?) nodes with the least latency, the N₂ (2?) nodes with the most latency, and the randomly-selected N₃ (1?) nodes with medium latency. The servers will connect to peers directly at first, however if a possible route with decreased latency is found, and the WireGuard network is configured to prefer latency, an algorithm will compute the preference score, and the peer with the least preference score will be chosen to act as a relay instead.

Suppose the latency and the median jitter are both in milliseconds, and the packet loss rate is in the range of [0, 1], the preference score is as follows.

const lossPunishmentFactor = 2;
let getPrefScore = (lat, mJit, loss) => {
	return (lat + mJit) / Math.pow(1 - loss, lossPunishmentFactor);
};