feat: Report cause of connection closing to behaviour

protocols/gossipsub/src/behaviour/tests.rs

@@ -268,6 +268,7 @@ where
                 connection_id,
                 endpoint: &fake_endpoint,
                 remaining_established: active_connections,
+                cause: None,
             }));
         }
     }

protocols/perf/src/client/behaviour.rs

@@ -116,6 +116,7 @@ impl NetworkBehaviour for Behaviour {
                 connection_id: _,
                 endpoint: _,
                 remaining_established,
+                ..
             }) => {
                 if remaining_established == 0 {
                     assert!(self.connected.remove(&peer_id));

swarm/src/behaviour.rs

@@ -32,8 +32,8 @@ use crate::connection::ConnectionId;
 use crate::dial_opts::DialOpts;
 use crate::listen_opts::ListenOpts;
 use crate::{
-    ConnectionDenied, ConnectionHandler, DialError, ListenError, THandler, THandlerInEvent,
-    THandlerOutEvent,
+    ConnectionDenied, ConnectionError, ConnectionHandler, DialError, ListenError, THandler,
+    THandlerInEvent, THandlerOutEvent,
 };
 use libp2p_core::{transport::ListenerId, ConnectedPoint, Endpoint, Multiaddr};
 use libp2p_identity::PeerId;
@@ -475,6 +475,7 @@ pub struct ConnectionClosed<'a> {
     pub peer_id: PeerId,
     pub connection_id: ConnectionId,
     pub endpoint: &'a ConnectedPoint,
+    pub cause: Option<&'a ConnectionError>,
     pub remaining_established: usize,
 }
 

swarm/src/lib.rs

@@ -907,6 +907,7 @@ where
                         peer_id,
                         connection_id: id,
                         endpoint: &endpoint,
+                        cause: error.as_ref(),
                         remaining_established: num_established as usize,
                     }));
                 self.pending_swarm_events

swarm/src/test.rs

@@ -301,6 +301,7 @@ where
             connection_id,
             endpoint,
             remaining_established,
+            cause,
         }: ConnectionClosed,
     ) {
         let mut other_closed_connections = self
@@ -350,6 +351,7 @@ where
                 connection_id,
                 endpoint,
                 remaining_established,
+                cause,
             }));
     }
 }