swarm/: Provide additional default impls on NetworkBehaviour (#2150)

Not all implementations of `NetworkBehaviour` need all callbacks.
We've have been adding new callbacks with default implementations
for a while now. There is no reason the initial ones cannot also
be defaulted, thus making it easier create new implementations.

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

protocols/floodsub/src/layer.rs

@@ -23,7 +23,7 @@ use crate::topic::Topic;
 use crate::FloodsubConfig;
 use cuckoofilter::{CuckooError, CuckooFilter};
 use fnv::FnvHashSet;
-use libp2p_core::{Multiaddr, PeerId, connection::ConnectionId};
+use libp2p_core::{PeerId, connection::ConnectionId};
 use libp2p_swarm::{
     NetworkBehaviour,
     NetworkBehaviourAction,
@@ -249,10 +249,6 @@ impl NetworkBehaviour for Floodsub {
         Default::default()
     }
 
-    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
-        Vec::new()
-    }
-
     fn inject_connected(&mut self, id: &PeerId) {
         // We need to send our subscriptions to the newly-connected node.
         if self.target_peers.contains(id) {

protocols/gossipsub/src/behaviour.rs

@@ -2804,10 +2804,6 @@ where
         )
     }
 
-    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
-        Vec::new()
-    }
-
     fn inject_connected(&mut self, peer_id: &PeerId) {
         // Ignore connections from blacklisted peers.
         if self.blacklisted_peers.contains(peer_id) {

protocols/identify/src/identify.rs

@@ -201,13 +201,6 @@ impl NetworkBehaviour for Identify {
         IdentifyHandler::new(self.config.initial_delay, self.config.interval)
     }
 
-    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
-        Vec::new()
-    }
-
-    fn inject_connected(&mut self, _: &PeerId) {
-    }
-
     fn inject_connection_established(&mut self, peer_id: &PeerId, conn: &ConnectionId, endpoint: &ConnectedPoint) {
         let addr = match endpoint {
             ConnectedPoint::Dialer { address } => address.clone(),

protocols/mdns/src/behaviour.rs

@@ -26,7 +26,7 @@ use if_watch::{IfEvent, IfWatcher};
 use lazy_static::lazy_static;
 use libp2p_core::connection::ListenerId;
 use libp2p_core::{
-    address_translation, connection::ConnectionId, multiaddr::Protocol, Multiaddr, PeerId,
+    address_translation, multiaddr::Protocol, Multiaddr, PeerId,
 };
 use libp2p_swarm::{
     protocols_handler::DummyProtocolsHandler, NetworkBehaviour, NetworkBehaviourAction,
@@ -254,14 +254,10 @@ impl NetworkBehaviour for Mdns {
             .collect()
     }
 
-    fn inject_connected(&mut self, _: &PeerId) {}
-
-    fn inject_disconnected(&mut self, _: &PeerId) {}
-
     fn inject_event(
         &mut self,
         _: PeerId,
-        _: ConnectionId,
+        _: libp2p_core::connection::ConnectionId,
         ev: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent,
     ) {
         void::unreachable(ev)

protocols/ping/src/lib.rs

@@ -46,7 +46,7 @@ pub mod handler;
 pub use handler::{PingConfig, PingResult, PingSuccess, PingFailure};
 use handler::PingHandler;
 
-use libp2p_core::{Multiaddr, PeerId, connection::ConnectionId};
+use libp2p_core::{PeerId, connection::ConnectionId};
 use libp2p_swarm::{NetworkBehaviour, NetworkBehaviourAction, PollParameters};
 use std::{collections::VecDeque, task::Context, task::Poll};
 use void::Void;
@@ -95,14 +95,6 @@ impl NetworkBehaviour for Ping {
         PingHandler::new(self.config.clone())
     }
 
-    fn addresses_of_peer(&mut self, _peer_id: &PeerId) -> Vec<Multiaddr> {
-        Vec::new()
-    }
-
-    fn inject_connected(&mut self, _: &PeerId) {}
-
-    fn inject_disconnected(&mut self, _: &PeerId) {}
-
     fn inject_event(&mut self, peer: PeerId, _: ConnectionId, result: PingResult) {
         self.events.push_front(PingEvent { peer, result })
     }

protocols/relay/tests/lib.rs

@@ -1358,24 +1358,13 @@ impl libp2p_swarm::NetworkBehaviour for KeepAliveBehaviour {
         }
     }
 
-    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
-        Vec::new()
-    }
-
-    fn inject_connected(&mut self, _: &PeerId) {}
-
-    fn inject_connection_established(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint) {}
-
-    fn inject_disconnected(&mut self, _: &PeerId) {}
-
-    fn inject_connection_closed(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint) {}
-
     fn inject_event(
         &mut self,
         _: PeerId,
         _: ConnectionId,
-        _: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent,
+        event: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent,
     ) {
+        void::unreachable(event);
     }
 
     fn poll(

swarm/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 - Update dependencies.
 
+- Provide default implementations for all functions of `NetworkBehaviour`,
+  except for `new_handler`, `inject_event` and `poll`.
+  This should make it easier to create new implementations. See [PR 2150].
+
+[PR 2150]: https://github.com/libp2p/rust-libp2p/pull/2150/
+
 # 0.30.0 [2021-07-12]
 
 - Update dependencies.

swarm/src/behaviour.rs

@@ -80,7 +80,9 @@ pub trait NetworkBehaviour: Send + 'static {
     /// The addresses will be tried in the order returned by this function, which means that they
     /// should be ordered by decreasing likelihood of reachability. In other words, the first
     /// address should be the most likely to be reachable.
-    fn addresses_of_peer(&mut self, peer_id: &PeerId) -> Vec<Multiaddr>;
+    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
+        vec![]
+    }
 
     /// Indicate to the behaviour that we connected to the node with the given peer id.
     ///
@@ -88,7 +90,7 @@ pub trait NetworkBehaviour: Send + 'static {
     ///
     /// This method is only called when the first connection to the peer is established, preceded by
     /// [`inject_connection_established`](NetworkBehaviour::inject_connection_established).
-    fn inject_connected(&mut self, peer_id: &PeerId);
+    fn inject_connected(&mut self, _: &PeerId) { }
 
     /// Indicates to the behaviour that we disconnected from the node with the given peer id.
     ///
@@ -97,7 +99,7 @@ pub trait NetworkBehaviour: Send + 'static {
     ///
     /// This method is only called when the last established connection to the peer is closed,
     /// preceded by [`inject_connection_closed`](NetworkBehaviour::inject_connection_closed).
-    fn inject_disconnected(&mut self, peer_id: &PeerId);
+    fn inject_disconnected(&mut self, _: &PeerId) { }
 
     /// Informs the behaviour about a newly established connection to a peer.
     fn inject_connection_established(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint)

swarm/src/lib.rs

@@ -1156,21 +1156,15 @@ impl NetworkBehaviour for DummyBehaviour {
         protocols_handler::DummyProtocolsHandler::default()
     }
 
-    fn addresses_of_peer(&mut self, _: &PeerId) -> Vec<Multiaddr> {
+    fn inject_event(
-        Vec::new()
+        &mut self,
+        _: PeerId,
+        _: ConnectionId,
+        event: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent
+    ) {
+        void::unreachable(event)
     }
 
-    fn inject_connected(&mut self, _: &PeerId) {}
-
-    fn inject_connection_established(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint) {}
-
-    fn inject_disconnected(&mut self, _: &PeerId) {}
-
-    fn inject_connection_closed(&mut self, _: &PeerId, _: &ConnectionId, _: &ConnectedPoint) {}
-
-    fn inject_event(&mut self, _: PeerId, _: ConnectionId,
-        _: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent) {}
-
     fn poll(&mut self, _: &mut Context<'_>, _: &mut impl PollParameters) ->
         Poll<NetworkBehaviourAction<<Self::ProtocolsHandler as
         ProtocolsHandler>::InEvent, Self::OutEvent>>

swarm/src/test.rs

@@ -82,12 +82,6 @@ where
         self.addresses.get(p).map_or(Vec::new(), |v| v.clone())
     }
 
-    fn inject_connected(&mut self, _: &PeerId) {
-    }
-
-    fn inject_disconnected(&mut self, _: &PeerId) {
-    }
-
     fn inject_event(&mut self, _: PeerId, _: ConnectionId, _: THandler::OutEvent) {
     }