1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158

// This file is part of Substrate.

// Copyright (C) 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::{channel::oneshot, StreamExt};
use sc_network_types::PeerId;

use sc_network::{
	request_responses::{IfDisconnected, RequestFailure},
	types::ProtocolName,
	NetworkPeers, NetworkRequest, 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 + NetworkRequest {}

impl<T> Network for T where T: NetworkPeers + NetworkRequest {}

/// 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),

	/// Call `NetworkRequest::start_request()`
	StartRequest(
		PeerId,
		ProtocolName,
		Vec<u8>,
		oneshot::Sender<Result<(Vec<u8>, ProtocolName), RequestFailure>>,
		IfDisconnected,
	),
}

/// 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));
	}

	/// Send request to peer
	pub fn start_request(
		&self,
		who: PeerId,
		protocol: ProtocolName,
		request: Vec<u8>,
		tx: oneshot::Sender<Result<(Vec<u8>, ProtocolName), RequestFailure>>,
		connect: IfDisconnected,
	) {
		let _ = self
			.tx
			.unbounded_send(ToServiceCommand::StartRequest(who, protocol, request, tx, connect));
	}
}

impl NetworkServiceProvider {
	/// Create new `NetworkServiceProvider`
	pub fn new() -> (Self, NetworkServiceHandle) {
		let (tx, rx) = tracing_unbounded("mpsc_network_service_provider", 100_000);

		(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),
				ToServiceCommand::StartRequest(peer, protocol, request, tx, connect) =>
					service.start_request(peer, protocol, request, None, tx, connect),
			}
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use crate::service::mock::MockNetwork;

	// typical pattern in `Protocol` code where peer is disconnected
	// and then reported
	#[tokio::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_network::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(|_, _| ());

		tokio::spawn(async move {
			provider.run(Arc::new(mock_network)).await;
		});

		handle.disconnect_peer(peer, proto_clone);
		handle.report_peer(peer, change);
	}
}