Allow StreamMuxer to notify changes in the address (#1621)

* Allow StreamMuxer to notify changes in the address

* Fix doc link

* Revert accidental rename

* Other accidental rename

Co-authored-by: Roman Borschel <romanb@users.noreply.github.com>

swarm/src/behaviour.rs

@@ -101,6 +101,15 @@ pub trait NetworkBehaviour: Send + 'static {
     fn inject_connection_closed(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint)
     {}
 
+    /// Informs the behaviour that the [`ConnectedPoint`] of an existing connection has changed.
+    fn inject_address_change(
+        &mut self,
+        _: &PeerId,
+        _: &ConnectionId,
+        _old: &ConnectedPoint,
+        _new: &ConnectedPoint
+    ) {}
+
     /// Informs the behaviour about an event generated by the handler dedicated to the peer identified by `peer_id`.
     /// for the behaviour.
     ///

swarm/src/lib.rs

@@ -496,6 +496,11 @@ where TBehaviour: NetworkBehaviour<ProtocolsHandler = THandler>,
                     let connection = connection.id();
                     this.behaviour.inject_event(peer, connection, event);
                 },
+                Poll::Ready(NetworkEvent::AddressChange { connection, new_endpoint, old_endpoint }) => {
+                    let peer = connection.peer_id();
+                    let connection = connection.id();
+                    this.behaviour.inject_address_change(&peer, &connection, &old_endpoint, &new_endpoint);
+                },
                 Poll::Ready(NetworkEvent::ConnectionEstablished { connection, num_established }) => {
                     let peer_id = connection.peer_id().clone();
                     let endpoint = connection.endpoint().clone();

swarm/src/protocols_handler.rs

@@ -53,6 +53,7 @@ pub use crate::upgrade::{
 
 use libp2p_core::{
     ConnectedPoint,
+    Multiaddr,
     PeerId,
     upgrade::{self, UpgradeError},
 };
@@ -140,6 +141,9 @@ pub trait ProtocolsHandler: Send + 'static {
     /// Injects an event coming from the outside in the handler.
     fn inject_event(&mut self, event: Self::InEvent);
 
+    /// Notifies the handler of a change in the address of the remote.
+    fn inject_address_change(&mut self, _new_address: &Multiaddr) {}
+
     /// Indicates to the handler that upgrading an outbound substream to the given protocol has failed.
     fn inject_dial_upgrade_error(
         &mut self,

swarm/src/protocols_handler/node_handler.rs

@@ -29,6 +29,7 @@ use crate::protocols_handler::{
 
 use futures::prelude::*;
 use libp2p_core::{
+    Multiaddr,
     PeerId,
     ConnectionInfo,
     Connected,
@@ -220,6 +221,10 @@ where
         self.handler.inject_event(event);
     }
 
+    fn inject_address_change(&mut self, new_address: &Multiaddr) {
+        self.handler.inject_address_change(new_address);
+    }
+
     fn poll(&mut self, cx: &mut Context) -> Poll<
         Result<ConnectionHandlerEvent<Self::OutboundOpenInfo, Self::OutEvent>, Self::Error>
     > {