protocols/mdns: Fix timely discovery after listening on new address (#2053)

If you start listening after mdns joined a multicast group, the peers may not
discover eachother until the 5min timeout expires.

Co-authored-by: Max Inden <mail@max-inden.de>

protocols/mdns/CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.30.1 [2021-04-21]
+
+- Fix timely discovery of peers after listening on a new address.
+  [PR 2053](https://github.com/libp2p/rust-libp2p/pull/2053/)
+
 # 0.30.0 [2021-04-13]
 
 - Derive `Debug` and `Clone` for `MdnsConfig`.

protocols/mdns/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "libp2p-mdns"
 edition = "2018"
-version = "0.30.0"
+version = "0.30.1"
 description = "Implementation of the libp2p mDNS discovery method"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "MIT"

protocols/mdns/src/behaviour.rs

@@ -27,6 +27,7 @@ use lazy_static::lazy_static;
 use libp2p_core::{
     address_translation, connection::ConnectionId, multiaddr::Protocol, Multiaddr, PeerId,
 };
+use libp2p_core::connection::ListenerId;
 use libp2p_swarm::{
     protocols_handler::DummyProtocolsHandler, NetworkBehaviour, NetworkBehaviourAction,
     PollParameters, ProtocolsHandler,
@@ -269,6 +270,10 @@ impl NetworkBehaviour for Mdns {
         void::unreachable(ev)
     }
 
+    fn inject_new_listen_addr(&mut self, _id: ListenerId, _addr: &Multiaddr) {
+        self.send_buffer.push_back(build_query());
+    }
+
     fn poll(
         &mut self,
         cx: &mut Context<'_>,