Detect relays vs direct connection stats

[dpc]

For performance/connectivity debugging/info I'd want to display stats that tell me what kind of underlying connection is being used:

• direct connection
  • was hole punching needed?
• relay is being used

Is this exposed anywhere? I don't see any way to deduce it from https://docs.rs/iroh/latest/iroh/endpoint/struct.PathStats.html ATM.

[matheus23]

iroh cannot know whether hole-punching was needed or not, as that's a property of the networking routers between the peers that we don't have access to.
In a home network to iroh it will look like you are hole-punching, even though all you're doing is sending each other pings without a firewall in between.

Whether to use relays or direct connections is managed on the endpoint level in iroh, because all connections to the same peer share the same connection type. You can see info about it by calling Endpoint::conn_type.

[dpc]

Endpoint::conn_type is exactly what I am looking for. I think exposing more metrics is always good, but ATM just being able to diagnose "Latency is higher than usual, do we have a direct connection, or are going through a relay" is the 80% of what is important.

[flub]

We have some metrics around this, e.g. https://docs.rs/iroh/latest/iroh/metrics/struct.MagicsockMetrics.html#structfield.connection_became_direct and some other fields there. But as @matheus23 says, not the direct metrics you're asking for.

Though I think it is fair to create an issue for this. I think it may be possible to give these metrics with the multipath changes, we should at least look into it.

Also the stats object you refer to is basically upstream Quinn's struct and we haven't changed anything. But I think you make a valid point that we should probably integrate our own metrics in there to give a more consistent API.