feat(identify): support pushing changes of external addresses

protocols/identify/CHANGELOG.md

@@ -1,5 +1,7 @@
 ## 0.44.1 - unreleased
 
+- Support (enabled by default) pushing changes of external addresses.
+  See [PR 4885](https://github.com/libp2p/rust-libp2p/pull/4885).
 - Ensure `Multiaddr` handled and returned by `Behaviour` are `/p2p` terminated.
   See [PR 4596](https://github.com/libp2p/rust-libp2p/pull/4596).
 

protocols/identify/src/behaviour.rs

@@ -93,6 +93,16 @@ pub struct Config {
     /// Disabled by default.
     pub push_listen_addr_updates: bool,
 
+    /// Whether new or changes in external addresses of the local node should
+    /// trigger an active push of an identify message to all connected peers.
+    ///
+    /// Enabling this option can result in connected peers being informed
+    /// earlier about new or expired external addresses of the local node,
+    /// i.e. before the next periodic identify request with each peer.
+    ///
+    /// Enabled by default.
+    pub push_external_addr_updates: bool,
+
     /// How many entries of discovered peers to keep before we discard
     /// the least-recently used one.
     ///
@@ -110,6 +120,7 @@ impl Config {
             local_public_key,
             interval: Duration::from_secs(5 * 60),
             push_listen_addr_updates: false,
+            push_external_addr_updates: true,
             cache_size: 100,
         }
     }
@@ -135,6 +146,14 @@ impl Config {
         self
     }
 
+    /// Configures whether new or expired external addresses of the local
+    /// node should trigger an active push of an identify message to all
+    /// connected peers.
+    pub fn with_push_external_addr_updates(mut self, b: bool) -> Self {
+        self.push_external_addr_updates = b;
+        self
+    }
+
     /// Configures the size of the LRU cache, caching addresses of discovered peers.
     pub fn with_cache_size(mut self, cache_size: usize) -> Self {
         self.cache_size = cache_size;
@@ -357,7 +376,9 @@ impl NetworkBehaviour for Behaviour {
             self.events.extend(change_events)
         }
 
-        if listen_addr_changed && self.config.push_listen_addr_updates {
+        if (listen_addr_changed && self.config.push_listen_addr_updates)
+            | (external_addr_changed && self.config.push_external_addr_updates)
+        {
             // trigger an identify push for all connected peers
             let push_events = self.connected.keys().map(|peer| ToSwarm::NotifyHandler {
                 peer_id: *peer,