feat(multipath): add RemoteInfo and ConnectionInfo #3614

Frando · 2025-11-06T11:12:27Z

Description

Adds ConnectionInfo, which is a weak info handle to a connection (does not keep the connection alive, cannot be upgraded to a full Connection). From a ConnectionInfo some static info is directly available, and as long as the connection is alive you can access the connection stats. You can also watch for path changes, and wait for the connection to be closed (without keeping it alive).
Adds functions remote_info and remotes to get a RemoteInfo or list of remote all remote infos.
The RemoteInfo allows to get a list of ConnectionInfo that are currently active
It also allows to watch the currently selected path, replacing Endpoint::conn_type
- We have to think through if this is hindering a potential future where we send on multiple paths in parallel
- If we remove this, you would have to go through all connections, call ConnectionInfo::paths_info, and check if there is a ip path (-> direct) or only a relay path (-> relayed).
- I'm torn a bit if we want this or not. It is a much simpler API, but maybe we shouldn't expose it?
It also allows to get the RTT of the currently selected path
Removes Endpoint::conn_type and Endpoint::latency

Breaking Changes

Notes & open questions

Change checklist

github-actions · 2025-11-06T11:16:10Z

Documentation for this PR has been generated and is available at: https://n0-computer.github.io/iroh/pr/3614/docs/iroh/

Last updated: 2025-11-06T11:24:22Z

flub

So my biggest problem is that I don't think we can allocate a vector with an item (whatever the item is) for each connection. I guess that gives two main options:

Not provide any API that needs this. I know you won't like this :)
Figure out how to make those this available as a liftime-disconnected iterator or something. I know I won't like this :)
???

flub · 2025-11-06T17:17:49Z

iroh/src/endpoint.rs

-    pub async fn latency(&self, endpoint_id: EndpointId) -> Option<Duration> {
-        self.msock.latency(endpoint_id).await
+    /// TODO: Expand docs.
+    pub fn remotes(&self) -> Vec<RemoteInfo> {


I'd consider making this impl Iterator, it means we don't have to allocate a vec (even if we currently do internally). E.g. if you have a busy server this could be thousands really.

flub · 2025-11-06T17:20:24Z

iroh/src/endpoint/connection.rs

-    })
+    };
+    let info = conn.to_info();
+    // Register this connection with the magicsock.


I think we can remove this comment now, so we look a bit less like an AI 😅

flub · 2025-11-06T17:22:22Z

iroh/src/endpoint/connection.rs

+    /// Returns the side of the connection (client or server).
+    pub fn side(&self) -> Side {
+        self.inner.side()
+    }


Ah, thanks for adding this!

I'd write a lot more docs, like explaining why on the QUIC-level this is a thing and why you might want to know for a protocol despite that iroh always allows you to be both. Basically assume you get a user landing from hn or reddit and exploring iroh for the first time without having a clue.

flub · 2025-11-06T17:26:33Z

iroh/src/endpoint/connection.rs

+    /// Returns a [`ConnectionInfo`], which is a weak handle to the connection
+    /// that does not keep the connection alive, but does allow to access some information
+    /// about the connection, and allows to wait for the connection to be closed.


I am a stickler for following the rust doc style guide strictly :)

So re-phrasing this so you have a 1-line summary followed by a blank line and longer explanation will focus you on writing meaningful words in that one line, because that's the line you'll see on rustdoc summary pages and will most often read from ide help.

(I'll only leave this comment once)

Fully. Haven't done docs properly at all yet, wanna settle the approach first.

flub · 2025-11-06T17:30:21Z

iroh/src/endpoint/connection.rs

+    // We could add such util methods here, not sure.
+    pub fn has_direct_path(&mut self) -> bool {
+        self.paths_info.get().keys().any(|addr| addr.is_ip())
+    }


I think selected_path like RemoteInfo has is a better idea for now.

flub · 2025-11-06T17:45:52Z