Finishing touches.

client/network/src/debug_info.rs

@@ -57,14 +57,27 @@ struct NodeInfo {
 	/// When we will remove the entry about this node from the list, or `None` if we're connected
 	/// to the node.
 	info_expire: Option<Instant>,
-	/// How we're connected to the node.
-	endpoints: SmallVec<[ConnectedPoint; 2]>,
+	/// Non-empty list of connected endpoints, one per connection.
+	endpoints: SmallVec<[ConnectedPoint; crate::MAX_CONNECTIONS_PER_PEER]>,
 	/// Version reported by the remote, or `None` if unknown.
 	client_version: Option<String>,
 	/// Latest ping time with this node.
 	latest_ping: Option<Duration>,
 }
 
+impl NodeInfo {
+	fn new(endpoint: ConnectedPoint) -> Self {
+		let mut endpoints = SmallVec::new();
+		endpoints.push(endpoint);
+		NodeInfo {
+			info_expire: None,
+			endpoints,
+			client_version: None,
+			latest_ping: None,
+		}
+	}
+}
+
 impl DebugInfoBehaviour {
 	/// Builds a new `DebugInfoBehaviour`.
 	pub fn new(
@@ -122,9 +135,9 @@ impl DebugInfoBehaviour {
 pub struct Node<'a>(&'a NodeInfo);
 
 impl<'a> Node<'a> {
-	/// Returns the endpoint we are connected to or were last connected to.
+	/// Returns the endpoint of an established connection to the peer.
 	pub fn endpoint(&self) -> &'a ConnectedPoint {
-		&self.0.endpoints[0] // TODO: Multiple?
+		&self.0.endpoints[0] // `endpoints` are non-empty by definition
 	}
 
 	/// Returns the latest version information we know of.
@@ -179,14 +192,7 @@ impl NetworkBehaviour for DebugInfoBehaviour {
 		self.identify.inject_connection_established(peer_id, conn, endpoint);
 		match self.nodes_info.entry(peer_id.clone()) {
 			Entry::Vacant(e) => {
-				let mut endpoints = SmallVec::new();
-				endpoints.push(endpoint.clone());
-				e.insert(NodeInfo {
-					info_expire: None,
-					endpoints,
-					client_version: None,
-					latest_ping: None,
-				});
+				e.insert(NodeInfo::new(endpoint.clone()));
 			}
 			Entry::Occupied(e) => {
 				let e = e.into_mut();

client/network/src/lib.rs

@@ -255,3 +255,12 @@ pub use libp2p::{Multiaddr, PeerId};
 pub use libp2p::multiaddr;
 
 pub use sc_peerset::ReputationChange;
+
+/// The maximum allowed number of established connections per peer.
+///
+/// Typically, and by design of the network behaviours in this crate,
+/// there is a single established connection per peer. However, to
+/// avoid unnecessary and nondeterministic connection closure in
+/// case of (possibly repeated) simultaneous dialing attempts between
+/// two peers, the per-peer connection limit is not set to 1 but 2.
+const MAX_CONNECTIONS_PER_PEER: usize = 2;

client/network/src/protocol/generic_proto/behaviour.rs

@@ -167,7 +167,7 @@ enum PeerState {
 	/// We may still have ongoing traffic with that peer, but it should cease shortly.
 	Disabled {
 		/// The connections that are currently open for custom protocol traffic.
-		open: SmallVec<[ConnectionId; 2]>,
+		open: SmallVec<[ConnectionId; crate::MAX_CONNECTIONS_PER_PEER]>,
 		/// If `Some`, any dial attempts to this peer are delayed until the given `Instant`.
 		banned_until: Option<Instant>,
 	},
@@ -177,7 +177,7 @@ enum PeerState {
 	/// but should get disconnected in a few seconds.
 	DisabledPendingEnable {
 		/// The connections that are currently open for custom protocol traffic.
-		open: SmallVec<[ConnectionId; 2]>,
+		open: SmallVec<[ConnectionId; crate::MAX_CONNECTIONS_PER_PEER]>,
 		/// When to enable this remote.
 		timer: futures_timer::Delay,
 		/// When the `timer` will trigger.
@@ -188,7 +188,7 @@ enum PeerState {
 	/// enabled state.
 	Enabled {
 		/// The connections that are currently open for custom protocol traffic.
-		open: SmallVec<[ConnectionId; 2]>,
+		open: SmallVec<[ConnectionId; crate::MAX_CONNECTIONS_PER_PEER]>,
 	},
 
 	/// We received an incoming connection from this peer and forwarded that