feat(swarm): add Option<PeerId> to IncomingConnectionError

Fixes #6025
Supercedes #6027

Pull-Request: #6032.

Author: DougAnderson444

misc/connection-limits/CHANGELOG.md

@@ -1,6 +1,6 @@
 ## 0.5.1
 
-- Allow setting Peer IDs for bypassing limit check. 
+- Allow setting Peer IDs for bypassing limit check.
   Connections to the specified peers won't be counted toward limits.
   See [PR 5720](https://github.com/libp2p/rust-libp2p/pull/5720).
 

misc/connection-limits/src/lib.rs

@@ -658,6 +658,37 @@ mod tests {
         )
     }
 
+    #[tokio::test]
+    async fn incoming_connection_error_carries_peer_id() {
+        let mut swarm1 = Swarm::new_ephemeral_tokio(|_| {
+            // Set max incoming connections to 0 to immediately deny all connections
+            Behaviour::new(ConnectionLimits::default().with_max_established_incoming(Some(0)))
+        });
+        let mut swarm2 =
+            Swarm::new_ephemeral_tokio(|_| Behaviour::new(ConnectionLimits::default()));
+
+        let dialer_peer_id = *swarm2.local_peer_id();
+
+        let (listen_addr, _) = swarm1.listen().with_memory_addr_external().await;
+
+        swarm2.dial(listen_addr).unwrap();
+
+        tokio::spawn(swarm2.loop_on_next());
+
+        let peer_id = swarm1
+            .wait(|event| match event {
+                SwarmEvent::IncomingConnectionError {
+                    error: ListenError::Denied { .. },
+                    peer_id,
+                    ..
+                } => peer_id,
+                _ => None,
+            })
+            .await;
+
+        assert_eq!(Some(dialer_peer_id), Some(peer_id));
+    }
+
     #[derive(libp2p_swarm_derive::NetworkBehaviour)]
     #[behaviour(prelude = "libp2p_swarm::derive_prelude")]
     struct Behaviour {

swarm/CHANGELOG.md

@@ -9,6 +9,10 @@
   certain upgrade.
   See [PR 5860](https://github.com/libp2p/rust-libp2p/pull/5860).
 
+- Expose `Option<PeerId>` in `SwarmEvent::IncomingConnectionError`.
+  This enables insight to which `PeerId` errored.
+  See [PR 6032](https://github.com/libp2p/rust-libp2p/pull/6032)
+
 ## 0.46.0
 
 - Don't report `NewExternalAddrCandidate` for confirmed external addresses.

swarm/src/lib.rs

@@ -221,6 +221,8 @@ pub enum SwarmEvent<TBehaviourOutEvent> {
         send_back_addr: Multiaddr,
         /// The error that happened.
         error: ListenError,
+        /// If known, [`PeerId`] of the peer that tried to connect to us.
+        peer_id: Option<PeerId>,
     },
     /// An error happened on an outbound connection.
     OutgoingConnectionError {
@@ -756,6 +758,7 @@ where
                                         send_back_addr,
                                         local_addr,
                                         error: listen_error,
+                                        peer_id: Some(peer_id),
                                     },
                                 );
                                 return;
@@ -868,6 +871,7 @@ where
                         local_addr,
                         send_back_addr,
                         error,
+                        peer_id: None,
                     });
             }
             PoolEvent::ConnectionClosed {
@@ -974,6 +978,7 @@ where
                                 local_addr,
                                 send_back_addr,
                                 error: listen_error,
+                                peer_id: None,
                             });
                         return;
                     }