Make NetworkService callable for ChainSync (#12542)

Introduce a middleware called `NetworkServiceProvider` which the
`ChainSync` can use to communicate with `NetworkService`. `ChainSync` is
given a `NetworkServiceHandle` which it uses to call `NetworkServiceProvider`
which then dispatches the calls to `NetworkService` on behalf of `ChainSync`.

This change will allow `ChainSync` to disconnect and report peers and
in the future it'll be possible to send requests and notifications
through the `NetworkServiceProvider`.

`NetworkServiceProvider` is needed only until the `ChainSync` object
has been removed from `Protocol`. After that, a normal `NetworkService`
handle can be passed onto `ChainSync` and these changes can be
deprecated.

Co-authored-by: parity-processbot <>

substrate/client/network/sync/src/service/mock.rs

@@ -16,10 +16,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-use libp2p::PeerId;
-use sc_network_common::service::NetworkSyncForkRequest;
+use sc_network_common::service::{NetworkPeers, NetworkSyncForkRequest};
 use sp_runtime::traits::{Block as BlockT, NumberFor};
 
+pub use libp2p::{identity::error::SigningError, kad::record::Key as KademliaKey};
+use libp2p::{Multiaddr, PeerId};
+use sc_network_common::{config::MultiaddrWithPeerId, protocol::ProtocolName};
+use sc_peerset::ReputationChange;
+use std::collections::HashSet;
+
 mockall::mock! {
 	pub ChainSyncInterface<B: BlockT> {}
 
@@ -29,3 +34,42 @@ mockall::mock! {
 		fn set_sync_fork_request(&self, peers: Vec<PeerId>, hash: B::Hash, number: NumberFor<B>);
 	}
 }
+
+mockall::mock! {
+	pub NetworkServiceHandle {}
+}
+
+// Mocked `Network` for `ChainSync`-related tests
+mockall::mock! {
+	pub Network {}
+
+	impl NetworkPeers for Network {
+		fn set_authorized_peers(&self, peers: HashSet<PeerId>);
+		fn set_authorized_only(&self, reserved_only: bool);
+		fn add_known_address(&self, peer_id: PeerId, addr: Multiaddr);
+		fn report_peer(&self, who: PeerId, cost_benefit: ReputationChange);
+		fn disconnect_peer(&self, who: PeerId, protocol: ProtocolName);
+		fn accept_unreserved_peers(&self);
+		fn deny_unreserved_peers(&self);
+		fn add_reserved_peer(&self, peer: MultiaddrWithPeerId) -> Result<(), String>;
+		fn remove_reserved_peer(&self, peer_id: PeerId);
+		fn set_reserved_peers(
+			&self,
+			protocol: ProtocolName,
+			peers: HashSet<Multiaddr>,
+		) -> Result<(), String>;
+		fn add_peers_to_reserved_set(
+			&self,
+			protocol: ProtocolName,
+			peers: HashSet<Multiaddr>,
+		) -> Result<(), String>;
+		fn remove_peers_from_reserved_set(&self, protocol: ProtocolName, peers: Vec<PeerId>);
+		fn add_to_peers_set(
+			&self,
+			protocol: ProtocolName,
+			peers: HashSet<Multiaddr>,
+		) -> Result<(), String>;
+		fn remove_from_peers_set(&self, protocol: ProtocolName, peers: Vec<PeerId>);
+		fn sync_num_connected(&self) -> usize;
+	}
+}

substrate/client/network/sync/src/service/mod.rs

@@ -20,3 +20,4 @@
 
 pub mod chain_sync;
 pub mod mock;
+pub mod network;

substrate/client/network/sync/src/service/network.rs

@@ -0,0 +1,128 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use futures::StreamExt;
+use libp2p::PeerId;
+use sc_network_common::{protocol::ProtocolName, service::NetworkPeers};
+use sc_peerset::ReputationChange;
+use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedReceiver, TracingUnboundedSender};
+use std::sync::Arc;
+
+/// Network-related services required by `sc-network-sync`
+pub trait Network: NetworkPeers {}
+
+impl<T> Network for T where T: NetworkPeers {}
+
+/// Network service provider for `ChainSync`
+///
+/// It runs as an asynchronous task and listens to commands coming from `ChainSync` and
+/// calls the `NetworkService` on its behalf.
+pub struct NetworkServiceProvider {
+	rx: TracingUnboundedReceiver<ToServiceCommand>,
+}
+
+/// Commands that `ChainSync` wishes to send to `NetworkService`
+pub enum ToServiceCommand {
+	/// Call `NetworkPeers::disconnect_peer()`
+	DisconnectPeer(PeerId, ProtocolName),
+
+	/// Call `NetworkPeers::report_peer()`
+	ReportPeer(PeerId, ReputationChange),
+}
+
+/// Handle that is (temporarily) passed to `ChainSync` so it can
+/// communicate with `NetworkService` through `SyncingEngine`
+#[derive(Clone)]
+pub struct NetworkServiceHandle {
+	tx: TracingUnboundedSender<ToServiceCommand>,
+}
+
+impl NetworkServiceHandle {
+	/// Create new service handle
+	pub fn new(tx: TracingUnboundedSender<ToServiceCommand>) -> NetworkServiceHandle {
+		Self { tx }
+	}
+
+	/// Report peer
+	pub fn report_peer(&self, who: PeerId, cost_benefit: ReputationChange) {
+		let _ = self.tx.unbounded_send(ToServiceCommand::ReportPeer(who, cost_benefit));
+	}
+
+	/// Disconnect peer
+	pub fn disconnect_peer(&self, who: PeerId, protocol: ProtocolName) {
+		let _ = self.tx.unbounded_send(ToServiceCommand::DisconnectPeer(who, protocol));
+	}
+}
+
+impl NetworkServiceProvider {
+	/// Create new `NetworkServiceProvider`
+	pub fn new() -> (Self, NetworkServiceHandle) {
+		let (tx, rx) = tracing_unbounded("mpsc_network_service_provider");
+
+		(Self { rx }, NetworkServiceHandle::new(tx))
+	}
+
+	/// Run the `NetworkServiceProvider`
+	pub async fn run(mut self, service: Arc<dyn Network + Send + Sync>) {
+		while let Some(inner) = self.rx.next().await {
+			match inner {
+				ToServiceCommand::DisconnectPeer(peer, protocol_name) =>
+					service.disconnect_peer(peer, protocol_name),
+				ToServiceCommand::ReportPeer(peer, reputation_change) =>
+					service.report_peer(peer, reputation_change),
+			}
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use crate::service::mock::MockNetwork;
+
+	// typical pattern in `Protocol` code where peer is disconnected
+	// and then reported
+	#[async_std::test]
+	async fn disconnect_and_report_peer() {
+		let (provider, handle) = NetworkServiceProvider::new();
+
+		let peer = PeerId::random();
+		let proto = ProtocolName::from("test-protocol");
+		let proto_clone = proto.clone();
+		let change = sc_peerset::ReputationChange::new_fatal("test-change");
+
+		let mut mock_network = MockNetwork::new();
+		mock_network
+			.expect_disconnect_peer()
+			.withf(move |in_peer, in_proto| &peer == in_peer && &proto == in_proto)
+			.once()
+			.returning(|_, _| ());
+		mock_network
+			.expect_report_peer()
+			.withf(move |in_peer, in_change| &peer == in_peer && &change == in_change)
+			.once()
+			.returning(|_, _| ());
+
+		async_std::task::spawn(async move {
+			provider.run(Arc::new(mock_network)).await;
+		});
+
+		handle.disconnect_peer(peer, proto_clone);
+		handle.report_peer(peer, change);
+	}
+}