From e30b36219385e2bd73f3870588f5e24a1bfbed0c Mon Sep 17 00:00:00 2001
From: Arkadiy Paronyan <arkady.paronyan@gmail.com>
Date: Mon, 15 Apr 2019 12:18:08 +0200
Subject: [PATCH] Disable gossip for peers running old version (#2245)

---
 substrate/core/network/src/protocol.rs | 34 +++++++++++++++-----------
 substrate/core/network/src/service.rs  |  9 ++++---
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/substrate/core/network/src/protocol.rs b/substrate/core/network/src/protocol.rs
index 2d3e81daa3..b82088c695 100644
--- a/substrate/core/network/src/protocol.rs
+++ b/substrate/core/network/src/protocol.rs
@@ -50,9 +50,9 @@ const PROPAGATE_TIMEOUT: time::Duration = time::Duration::from_millis(2900);
 const STATUS_INTERVAL: time::Duration = time::Duration::from_millis(5000);
 
 /// Current protocol version.
-pub(crate) const CURRENT_VERSION: u32 = 2;
+pub(crate) const CURRENT_VERSION: u32 = 3;
 /// Lowest version we support
-const MIN_VERSION: u32 = 2;
+pub(crate) const MIN_VERSION: u32 = 2;
 
 // Maximum allowed entries in `BlockResponse`
 const MAX_BLOCK_DATA_RESPONSE: u32 = 128;
@@ -505,11 +505,13 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Protocol<B, S, H> {
 			GenericMessage::RemoteChangesRequest(request) => self.on_remote_changes_request(who, request),
 			GenericMessage::RemoteChangesResponse(response) => self.on_remote_changes_response(who, response),
 			GenericMessage::Consensus(msg) => {
-				self.consensus_gossip.on_incoming(
-					&mut ProtocolContext::new(&mut self.context_data, &self.network_chan),
-					who,
-					msg,
-				);
+				if self.context_data.peers.get(&who).map_or(false, |peer| peer.info.protocol_version > 2) {
+					self.consensus_gossip.on_incoming(
+						&mut ProtocolContext::new(&mut self.context_data, &self.network_chan),
+						who,
+						msg,
+					);
+				}
 			}
 			other => self.specialization.on_message(
 				&mut ProtocolContext::new(&mut self.context_data, &self.network_chan),
@@ -561,11 +563,13 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Protocol<B, S, H> {
 		let removed = {
 			self.handshaking_peers.remove(&peer);
 			self.connected_peers.write().remove(&peer);
-			self.context_data.peers.remove(&peer).is_some()
+			self.context_data.peers.remove(&peer)
 		};
-		if removed {
+		if let Some(peer_data) = removed {
 			let mut context = ProtocolContext::new(&mut self.context_data, &self.network_chan);
-			self.consensus_gossip.peer_disconnected(&mut context, peer.clone());
+			if peer_data.info.protocol_version > 2 {
+				self.consensus_gossip.peer_disconnected(&mut context, peer.clone());
+			}
 			self.sync.peer_disconnected(&mut context, peer.clone());
 			self.specialization.on_disconnect(&mut context, peer.clone());
 			self.on_demand.as_ref().map(|s| s.on_disconnect(peer));
@@ -721,7 +725,7 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Protocol<B, S, H> {
 	/// Called by peer to report status
 	fn on_status_message(&mut self, who: PeerId, status: message::Status<B>) {
 		trace!(target: "sync", "New peer {} {:?}", who, status);
-		{
+		let protocol_version = {
 			if self.context_data.peers.contains_key(&who) {
 				debug!("Unexpected status packet from {}", who);
 				return;
@@ -801,15 +805,17 @@ impl<B: BlockT, S: NetworkSpecialization<B>, H: ExHashT> Protocol<B, S, H> {
 			self.context_data.peers.insert(who.clone(), peer);
 
 			debug!(target: "sync", "Connected {}", who);
-		}
+			status.version
+		};
 
 		let mut context = ProtocolContext::new(&mut self.context_data, &self.network_chan);
 		self.on_demand
 			.as_ref()
 			.map(|s| s.on_connect(who.clone(), status.roles, status.best_number));
 		self.sync.new_peer(&mut context, who.clone());
-		self.consensus_gossip
-			.new_peer(&mut context, who.clone(), status.roles);
+		if protocol_version > 2 {
+			self.consensus_gossip.new_peer(&mut context, who.clone(), status.roles);
+		}
 		self.specialization.on_connect(&mut context, who, status);
 	}
 
diff --git a/substrate/core/network/src/service.rs b/substrate/core/network/src/service.rs
index 9964286f30..10367123db 100644
--- a/substrate/core/network/src/service.rs
+++ b/substrate/core/network/src/service.rs
@@ -178,8 +178,8 @@ impl<B: BlockT + 'static, S: NetworkSpecialization<B>> Service<B, S> {
 			params.transaction_pool,
 			params.specialization,
 		)?;
-		let versions = [(protocol::CURRENT_VERSION as u8)];
-		let registered = RegisteredProtocol::new(protocol_id, &versions[..]);
+		let versions: Vec<_> = ((protocol::MIN_VERSION as u8)..=(protocol::CURRENT_VERSION as u8)).collect();
+		let registered = RegisteredProtocol::new(protocol_id, &versions);
 		let (thread, network, peerset) = start_thread(
 			network_to_protocol_sender,
 			network_port,
@@ -568,7 +568,10 @@ fn run_thread<B: BlockT + 'static>(
 	let network = stream::poll_fn(move || network_service.lock().poll()).for_each(move |event| {
 		match event {
 			NetworkServiceEvent::OpenedCustomProtocol { peer_id, version, debug_info, .. } => {
-				debug_assert_eq!(version, protocol::CURRENT_VERSION as u8);
+				debug_assert!(
+					version <= protocol::CURRENT_VERSION as u8
+					&& version >= protocol::MIN_VERSION as u8
+				);
 				let _ = protocol_sender.send(FromNetworkMsg::PeerConnected(peer_id, debug_info));
 			}
 			NetworkServiceEvent::ClosedCustomProtocol { peer_id, debug_info, .. } => {