feat(swarm)!: introduce ListenError (#3375)

In case an error happens for an outgoing connection, `Pool` reports an `OutgoingConnectionError`. This one is mapped to a `DialError` and reported via `SwarmEvent::OutgoingConnectionError` and `FromSwarm::DialFailure`.

For incoming connections, we didn't quite do the same thing. For one, `SwarmEvent::IncomingConnectionError` directly contained a `PendingInboundConnectionError`. Two, `FromSwarm::ListenFailure` did not include an error at all.

With this patch, we now introduce a `ListenError` enum which we use in `SwarmEvent::IncomingConnectionError` and we pass a reference to it along in `FromSwarm::ListenFailure`.

swarm/src/behaviour.rs

@@ -29,7 +29,7 @@ pub use listen_addresses::ListenAddresses;
 use crate::connection::ConnectionId;
 use crate::dial_opts::DialOpts;
 use crate::handler::{ConnectionHandler, IntoConnectionHandler};
-use crate::{AddressRecord, AddressScore, DialError, THandlerOutEvent};
+use crate::{AddressRecord, AddressScore, DialError, ListenError, THandlerOutEvent};
 use libp2p_core::{transport::ListenerId, ConnectedPoint, Multiaddr, PeerId};
 use std::{task::Context, task::Poll};
 
@@ -742,6 +742,7 @@ pub struct DialFailure<'a, Handler> {
 pub struct ListenFailure<'a, Handler> {
     pub local_addr: &'a Multiaddr,
     pub send_back_addr: &'a Multiaddr,
+    pub error: &'a ListenError,
     pub handler: Handler,
 }
 
@@ -870,10 +871,12 @@ impl<'a, Handler: IntoConnectionHandler> FromSwarm<'a, Handler> {
             FromSwarm::ListenFailure(ListenFailure {
                 local_addr,
                 send_back_addr,
+                error,
                 handler,
             }) => Some(FromSwarm::ListenFailure(ListenFailure {
                 local_addr,
                 send_back_addr,
+                error,
                 handler: map_into_handler(handler)?,
             })),
             FromSwarm::NewListener(NewListener { listener_id }) => {