feat(identify): include pushed Info in Event::Pushed

Starting in #3980, we make more use of the identify push protocol by actively notifying the peer when our locally supported protocols change. We emit an event (`Pushed`) to the user in that case. This event however does not include **what** we pushed.

Users might be interested in the internal changes that we push to remote peers. This patch adds the identify `Info` to the `Pushed` variant.

Fixes #4332.

Pull-Request: #4527.

protocols/identify/CHANGELOG.md

@@ -1,5 +1,7 @@
 ## 0.44.0 - unreleased
 
+- Add `Info` to the `libp2p-identify::Event::Pushed` to report pushed info.
+  See [PR 4527](https://github.com/libp2p/rust-libp2p/pull/4527)
 
 ## 0.43.1
 

protocols/identify/src/behaviour.rs

@@ -301,9 +301,9 @@ impl NetworkBehaviour for Behaviour {
                 self.events
                     .push_back(ToSwarm::GenerateEvent(Event::Sent { peer_id }));
             }
-            handler::Event::IdentificationPushed => {
+            handler::Event::IdentificationPushed(info) => {
                 self.events
-                    .push_back(ToSwarm::GenerateEvent(Event::Pushed { peer_id }));
+                    .push_back(ToSwarm::GenerateEvent(Event::Pushed { peer_id, info }));
             }
             handler::Event::IdentificationError(error) => {
                 self.events
@@ -431,6 +431,9 @@ pub enum Event {
     Pushed {
         /// The peer that the information has been sent to.
         peer_id: PeerId,
+        /// The full Info struct we pushed to the remote peer. Clients must
+        /// do some diff'ing to know what has changed since the last push.
+        info: Info,
     },
     /// Error while attempting to identify the remote.
     Error {

protocols/identify/src/handler.rs

@@ -110,7 +110,7 @@ pub enum Event {
     /// We replied to an identification request from the remote.
     Identification,
     /// We actively pushed our identification information to the remote.
-    IdentificationPushed,
+    IdentificationPushed(Info),
     /// Failed to identify the remote, or to reply to an identification request.
     IdentificationError(StreamUpgradeError<UpgradeError>),
 }
@@ -211,7 +211,7 @@ impl Handler {
                 if self
                     .active_streams
                     .try_push(
-                        protocol::send_identify(stream, info).map_ok(|_| Success::SentIdentifyPush),
+                        protocol::send_identify(stream, info).map_ok(Success::SentIdentifyPush),
                     )
                     .is_err()
                 {
@@ -352,9 +352,9 @@ impl ConnectionHandler for Handler {
                     remote_info,
                 )));
             }
-            Poll::Ready(Ok(Ok(Success::SentIdentifyPush))) => {
+            Poll::Ready(Ok(Ok(Success::SentIdentifyPush(info)))) => {
                 return Poll::Ready(ConnectionHandlerEvent::NotifyBehaviour(
-                    Event::IdentificationPushed,
+                    Event::IdentificationPushed(info),
                 ));
             }
             Poll::Ready(Ok(Ok(Success::SentIdentify))) => {
@@ -446,6 +446,6 @@ impl ConnectionHandler for Handler {
 enum Success {
     SentIdentify,
     ReceivedIdentify(Info),
-    SentIdentifyPush,
+    SentIdentifyPush(Info),
     ReceivedIdentifyPush(PushInfo),
 }

protocols/identify/src/protocol.rs

@@ -90,27 +90,23 @@ pub struct PushInfo {
     pub observed_addr: Option<Multiaddr>,
 }
 
-pub(crate) async fn send_identify<T>(io: T, info: Info) -> Result<(), UpgradeError>
+pub(crate) async fn send_identify<T>(io: T, info: Info) -> Result<Info, UpgradeError>
 where
     T: AsyncWrite + Unpin,
 {
     trace!("Sending: {:?}", info);
 
-    let listen_addrs = info
-        .listen_addrs
-        .into_iter()
-        .map(|addr| addr.to_vec())
-        .collect();
+    let listen_addrs = info.listen_addrs.iter().map(|addr| addr.to_vec()).collect();
 
     let pubkey_bytes = info.public_key.encode_protobuf();
 
     let message = proto::Identify {
-        agentVersion: Some(info.agent_version),
-        protocolVersion: Some(info.protocol_version),
+        agentVersion: Some(info.agent_version.clone()),
+        protocolVersion: Some(info.protocol_version.clone()),
         publicKey: Some(pubkey_bytes),
         listenAddrs: listen_addrs,
         observedAddr: Some(info.observed_addr.to_vec()),
-        protocols: info.protocols.into_iter().map(|p| p.to_string()).collect(),
+        protocols: info.protocols.iter().map(|p| p.to_string()).collect(),
     };
 
     let mut framed_io = FramedWrite::new(
@@ -121,7 +117,7 @@ where
     framed_io.send(message).await?;
     framed_io.close().await?;
 
-    Ok(())
+    Ok(info)
 }
 
 pub(crate) async fn recv_push<T>(socket: T) -> Result<PushInfo, UpgradeError>