Refactor out disable/disconnect peer to make API more declarative (#394)

* Refactor out disable/disconnect peer to make API more declarative

* Minor fixes.

* rename `disconnect_peer` to `drop_peer` in low-level

substrate/polkadot/network/src/lib.rs

@@ -49,7 +49,7 @@ use parking_lot::Mutex;
 use polkadot_consensus::{Statement, SignedStatement, GenericStatement};
 use polkadot_primitives::{AccountId, Block, SessionKey, Hash, Header};
 use polkadot_primitives::parachain::{Id as ParaId, BlockData, Extrinsic, CandidateReceipt, Collation};
-use substrate_network::{PeerId, RequestId, Context};
+use substrate_network::{PeerId, RequestId, Context, Severity};
 use substrate_network::consensus_gossip::ConsensusGossip;
 use substrate_network::{message, generic_message};
 use substrate_network::specialization::Specialization;
@@ -403,7 +403,7 @@ impl PolkadotProtocol {
 			};
 
 			if !info.claimed_validator {
-				ctx.disable_peer(peer_id, "Session key broadcasted without setting authority role");
+				ctx.report_peer(peer_id, Severity::Bad("Session key broadcasted without setting authority role"));
 				return;
 			}
 
@@ -438,7 +438,7 @@ impl PolkadotProtocol {
 				self.pending.push(req);
 				self.dispatch_pending_requests(ctx);
 			}
-			None => ctx.disable_peer(peer_id, "Unexpected block data response"),
+			None => ctx.report_peer(peer_id, Severity::Bad("Unexpected block data response")),
 		}
 	}
 
@@ -453,9 +453,9 @@ impl PolkadotProtocol {
 		};
 
 		match info.validator_key {
-			None => ctx.disable_peer(
+			None => ctx.report_peer(
 				peer_id,
-				"Sent collator role without registering first as validator",
+				Severity::Bad("Sent collator role without registering first as validator"),
 			),
 			Some(key) => for (relay_parent, collation) in self.local_collations.note_validator_role(key, role) {
 				send_polkadot_message(
@@ -483,7 +483,7 @@ impl Specialization<Block> for PolkadotProtocol {
 
 		if let Some((ref acc_id, ref para_id)) = local_status.collating_for {
 			if self.collator_peer_id(acc_id.clone()).is_some() {
-				ctx.disconnect_peer(peer_id);
+				ctx.report_peer(peer_id, Severity::Useless("Unknown Polkadot-specific reason"));
 				return
 			}
 
@@ -571,7 +571,7 @@ impl Specialization<Block> for PolkadotProtocol {
 					Some(msg) => self.on_polkadot_message(ctx, peer_id, raw, msg),
 					None => {
 						trace!(target: "p_net", "Bad message from {}", peer_id);
-						ctx.disable_peer(peer_id, "Invalid polkadot protocol message format");
+						ctx.report_peer(peer_id, Severity::Bad("Invalid polkadot protocol message format"));
 					}
 				}
 			}
@@ -616,15 +616,15 @@ impl PolkadotProtocol {
 		let collated_acc = collation.receipt.collator;
 
 		match self.peers.get(&from) {
-			None => ctx.disconnect_peer(from),
+			None => ctx.report_peer(from, Severity::Useless("Unknown Polkadot specific reason")),
 			Some(peer_info) => match peer_info.collating_for {
-				None => ctx.disable_peer(from, "Sent collation without registering collator intent"),
+				None => ctx.report_peer(from, Severity::Bad("Sent collation without registering collator intent")),
 				Some((ref acc_id, ref para_id)) => {
 					let structurally_valid = para_id == &collation_para && acc_id == &collated_acc;
 					if structurally_valid && collation.receipt.check_signature().is_ok() {
 						self.collators.on_collation(acc_id.clone(), relay_parent, collation)
 					} else {
-						ctx.disable_peer(from, "Sent malformed collation")
+						ctx.report_peer(from, Severity::Bad("Sent malformed collation"))
 					};
 				}
 			},
@@ -654,7 +654,7 @@ impl PolkadotProtocol {
 	// disconnect a collator by account-id.
 	fn disconnect_bad_collator(&self, ctx: &mut Context<Block>, account_id: AccountId) {
 		if let Some(peer_id) = self.collator_peer_id(account_id) {
-			ctx.disable_peer(peer_id, "Consensus layer determined the given collator misbehaved")
+			ctx.report_peer(peer_id, Severity::Bad("Consensus layer determined the given collator misbehaved"))
 		}
 	}
 }

substrate/polkadot/network/src/tests.rs

@@ -24,7 +24,7 @@ use polkadot_primitives::{Block, Hash, SessionKey};
 use polkadot_primitives::parachain::{CandidateReceipt, HeadData, BlockData};
 use substrate_primitives::H512;
 use codec::Encode;
-use substrate_network::{PeerId, PeerInfo, ClientHandle, Context, Roles, message::Message as SubstrateMessage, specialization::Specialization, generic_message::Message as GenericMessage};
+use substrate_network::{Severity, PeerId, PeerInfo, ClientHandle, Context, Roles, message::Message as SubstrateMessage, specialization::Specialization, generic_message::Message as GenericMessage};
 
 use std::sync::Arc;
 use futures::Future;
@@ -41,12 +41,11 @@ impl Context<Block> for TestContext {
 		unimplemented!()
 	}
 
-	fn disable_peer(&mut self, peer: PeerId, _reason: &str) {
+	fn report_peer(&mut self, peer: PeerId, reason: Severity) {
-		self.disabled.push(peer);
+		match reason {
-	}
+			Severity::Bad(_) => self.disabled.push(peer),
-
+			_ => self.disconnected.push(peer),
-	fn disconnect_peer(&mut self, peer: PeerId) {
+		}
-		self.disconnected.push(peer);
 	}
 
 	fn peer_info(&self, _peer: PeerId) -> Option<PeerInfo<Block>> {

substrate/substrate/network-libp2p/src/connection_filter.rs

@@ -1,18 +1,18 @@
 // Copyright 2015-2018 Parity Technologies (UK) Ltd.
-// This file is part of Parity.
+// This file is part of Substrate.
 
-// Parity is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Parity is distributed in the hope that it will be useful,
+// Substrate 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Connection filter trait.
 

substrate/substrate/network-libp2p/src/custom_proto.rs

@@ -1,18 +1,18 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 use bytes::{Bytes, BytesMut};
 use ProtocolId;
@@ -122,6 +122,7 @@ where C: AsyncRead + AsyncWrite + 'static,		// TODO: 'static :-/
 	type MultiaddrFuture = Maf;
 	type Future = future::FutureResult<(Self::Output, Self::MultiaddrFuture), IoError>;
 
+	#[allow(deprecated)]
 	fn upgrade(
 		self,
 		socket: C,

substrate/substrate/network-libp2p/src/error.rs

@@ -1,18 +1,18 @@
 // Copyright 2015-2018 Parity Technologies (UK) Ltd.
-// This file is part of Parity.
+// This file is part of Substrate.
 
-// Parity is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Parity is distributed in the hope that it will be useful,
+// Substrate 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 use std::{io, net, fmt};
 use libc::{ENFILE, EMFILE};

substrate/substrate/network-libp2p/src/lib.rs

@@ -1,18 +1,18 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 #![recursion_limit="128"]
 #![type_length_limit = "268435456"]

substrate/substrate/network-libp2p/src/network_state.rs

@@ -1,18 +1,18 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 use bytes::Bytes;
 use fnv::{FnvHashMap, FnvHashSet};
@@ -126,6 +126,45 @@ struct PeerConnectionInfo {
 	local_address: Option<Multiaddr>,
 }
 
+/// Simplified, POD version of PeerConnectionInfo.
+#[derive(Debug, Clone)]
+pub struct PeerInfo {
+	/// Id of the peer.
+	pub id: PeerstorePeerId,
+
+	/// True if this connection was initiated by us.
+	/// Note that it is theoretically possible that we dial the remote at the
+	/// same time they dial us, in which case the protocols may be dispatched
+	/// between both connections, and in which case the value here will be racy.
+	pub originated: bool,
+
+	/// Latest known ping duration.
+	pub ping: Option<Duration>,
+
+	/// The client version of the remote, or `None` if not known.
+	pub client_version: Option<String>,
+
+	/// The multiaddress of the remote, or `None` if not known.
+	pub remote_address: Option<Multiaddr>,
+
+	/// The local multiaddress used to communicate with the remote, or `None`
+	/// if not known.
+	pub local_address: Option<Multiaddr>,
+}
+
+impl<'a> From<&'a PeerConnectionInfo> for PeerInfo {
+	fn from(i: &'a PeerConnectionInfo) -> PeerInfo {
+		PeerInfo {
+			id: i.id.clone(),
+			originated: i.originated,
+			ping: i.ping.lock().clone(),
+			client_version: i.client_version.clone(),
+			remote_address: i.remote_address.clone(),
+			local_address: i.local_address.clone(),
+		}
+	}
+}
+
 impl NetworkState {
 	pub fn new(config: &NetworkConfiguration) -> Result<NetworkState, Error> {
 		// Private and public keys configuration.
@@ -581,24 +620,37 @@ impl NetworkState {
 			} else {
 				// We are connected to this peer, but not with the current
 				// protocol.
-				debug!(target: "sub-libp2p", "Tried to send message to peer {} \
+				debug!(target: "sub-libp2p",
-					for which we aren't connected with the requested protocol",
+					"Tried to send message to peer {} for which we aren't connected with the requested protocol",
-					peer_id);
+					peer_id
+				);
 				return Err(ErrorKind::PeerNotFound.into())
 			}
 		} else {
-			debug!(target: "sub-libp2p", "Tried to send message to invalid \
+			debug!(target: "sub-libp2p", "Tried to send message to invalid peer ID {}", peer_id);
-				peer ID {}", peer_id);
 			return Err(ErrorKind::PeerNotFound.into())
 		}
 	}
 
+	/// Get the info on a peer, if there's an active connection.
+	pub fn peer_info(&self, who: PeerId) -> Option<PeerInfo> {
+		self.connections.read().info_by_peer.get(&who).map(Into::into)
+	}
+
 	/// Disconnects a peer, if a connection exists (ie. drops the Kademlia
 	/// controller, and the senders that were stored in the `UniqueConnec` of
 	/// `custom_proto`).
-	pub fn disconnect_peer(&self, peer_id: PeerId) {
+	pub fn drop_peer(&self, peer_id: PeerId, reason: Option<&str>) {
 		let mut connections = self.connections.write();
 		if let Some(peer_info) = connections.info_by_peer.remove(&peer_id) {
+			if let Some(reason) = reason {
+				if let (&Some(ref client_version), &Some(ref remote_address)) = (&peer_info.client_version, &peer_info.remote_address) {
+					debug!(target: "sub-libp2p", "Disconnected peer {} (version: {}, address: {}). {}", peer_id, client_version, remote_address, reason);
+				} else {
+					debug!(target: "sub-libp2p", "Disconnected peer {}. {}", peer_id, reason);
+				}
+			}
+
 			trace!(target: "sub-libp2p", "Destroying peer #{} {:?} ; \
 				kademlia = {:?} ; num_protos = {:?}", peer_id, peer_info.id,
 				peer_info.kad_connec.is_alive(),

substrate/substrate/network-libp2p/src/service.rs

@@ -1,22 +1,22 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 use bytes::Bytes;
 use {Error, ErrorKind, NetworkConfiguration, NetworkProtocolHandler};
-use {NonReservedPeerMode, NetworkContext, PeerId, ProtocolId};
+use {NonReservedPeerMode, NetworkContext, Severity, PeerId, ProtocolId};
 use parking_lot::{Mutex, RwLock};
 use libp2p;
 use libp2p::multiaddr::{AddrComponent, Multiaddr};
@@ -299,8 +299,7 @@ struct NetworkContextImpl {
 }
 
 impl NetworkContext for NetworkContextImpl {
-	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>)
+	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>) {
-		-> Result<(), Error> {
 		self.send_protocol(self.protocol, peer, packet_id, data)
 	}
 
@@ -310,7 +309,7 @@ impl NetworkContext for NetworkContextImpl {
 		peer: PeerId,
 		packet_id: PacketId,
 		data: Vec<u8>
-	) -> Result<(), Error> {
+	) {
 		debug_assert!(self.inner.protocols.read().has_protocol(protocol),
 			"invalid protocol id requested in the API of the libp2p networking");
 		// TODO: could be "optimized" by building `message` only after checking the validity of
@@ -318,10 +317,12 @@ impl NetworkContext for NetworkContextImpl {
 		let mut message = Bytes::with_capacity(1 + data.len());
 		message.extend_from_slice(&[packet_id]);
 		message.extend_from_slice(&data);
-		self.inner.network_state.send(protocol, peer, message)
+		if self.inner.network_state.send(protocol, peer, message).is_err() {
+			self.inner.network_state.drop_peer(peer, Some("Sending to peer failed"));
+		}
 	}
 
-	fn respond(&self, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error> {
+	fn respond(&self, packet_id: PacketId, data: Vec<u8>) {
 		if let Some(peer) = self.current_peer {
 			self.send_protocol(self.protocol, peer, packet_id, data)
 		} else {
@@ -329,14 +330,19 @@ impl NetworkContext for NetworkContextImpl {
 		}
 	}
 
-	fn disable_peer(&self, peer: PeerId, reason: &str) {
+	fn report_peer(&self, peer: PeerId, reason: Severity) {
-		debug!(target: "sub-libp2p", "Request to disable peer {} for reason {}", peer, reason);
+		if let Some(info) = self.inner.network_state.peer_info(peer) {
-		self.inner.network_state.disable_peer(peer, reason);
+			if let (Some(client_version), Some(remote_address)) = (info.client_version, info.remote_address) {
-	}
+				info!(target: "sub-libp2p", "Peer {} ({} {}) reported by client: {}", peer, remote_address, client_version, reason);
-
+			} else {
-	fn disconnect_peer(&self, peer: PeerId) {
+				info!(target: "sub-libp2p", "Peer {} reported by client: {}", peer, reason);
-		debug!(target: "sub-libp2p", "Request to disconnect peer {}", peer);
+			}
-		self.inner.network_state.disconnect_peer(peer);
+		}
+		match reason {
+			Severity::Bad(reason) => self.inner.network_state.disable_peer(peer, reason),
+			Severity::Useless(reason) => self.inner.network_state.drop_peer(peer, Some(reason)),
+			Severity::Timeout => self.inner.network_state.drop_peer(peer, Some("Timeout waiting for response")),
+		}
 	}
 
 	fn is_expired(&self) -> bool {
@@ -768,9 +774,12 @@ fn handle_custom_connection(
 
 	impl Drop for ProtoDisconnectGuard {
 		fn drop(&mut self) {
-			debug!(target: "sub-libp2p", "Node {:?} with peer ID {} \
+			debug!(target: "sub-libp2p",
-				through protocol {:?} disconnected", self.node_id, self.peer_id,
+				"Node {:?} with peer ID {} through protocol {:?} disconnected",
-				self.protocol);
+				self.node_id,
+				self.peer_id,
+				self.protocol
+			);
 			self.handler.disconnected(&NetworkContextImpl {
 				inner: self.inner.clone(),
 				protocol: self.protocol,
@@ -779,7 +788,7 @@ fn handle_custom_connection(
 
 			// When any custom protocol drops, we drop the peer entirely.
 			// TODO: is this correct?
-			self.inner.network_state.disconnect_peer(self.peer_id);
+			self.inner.network_state.drop_peer(self.peer_id, Some("Remote end disconnected"));
 		}
 	}
 
@@ -1271,8 +1280,7 @@ fn ping_all<T, St, C>(
 		let fut = pinger
 			.get_or_dial(&swarm_controller, &addr, transport.clone())
 			.and_then(move |mut p| {
-				trace!(target: "sub-libp2p",
+				trace!(target: "sub-libp2p", "Pinging peer #{} aka. {:?}", peer, peer_id);
-					"Pinging peer #{} aka. {:?}", peer, peer_id);
 				p.ping()
 					.map(|()| peer_id)
 					.map_err(|err| IoError::new(IoErrorKind::Other, err))
@@ -1282,16 +1290,14 @@ fn ping_all<T, St, C>(
 			.then(move |val|
 				match val {
 					Err(err) => {
-						trace!(target: "sub-libp2p",
+						trace!(target: "sub-libp2p", "Error while pinging #{:?} => {:?}", peer, err);
-							"Error while pinging #{:?} => {:?}", peer, err);
+						shared.network_state.drop_peer(peer, None);	// None so that we don't print messages on such low-level issues.
-						shared.network_state.disconnect_peer(peer);
 						// Return Ok, otherwise we would close the ping service
 						Ok(())
 					},
 					Ok(peer_id) => {
 						let elapsed = ping_start_time.elapsed();
-						trace!(target: "sub-libp2p", "Pong from #{:?} in {:?}",
+						trace!(target: "sub-libp2p", "Pong from #{:?} in {:?}", peer, elapsed);
-							peer, elapsed);
 						shared.network_state.report_ping_duration(peer, elapsed);
 						shared.kad_system.update_kbuckets(peer_id);
 						Ok(())

substrate/substrate/network-libp2p/src/timeouts.rs

@@ -1,18 +1,18 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 use futures::{Async, future, Future, Poll, stream, Stream, sync::mpsc};
 use std::io::Error as IoError;

substrate/substrate/network-libp2p/src/traits.rs

@@ -1,19 +1,20 @@
 // Copyright 2015-2018 Parity Technologies (UK) Ltd.
-// This file is part of Parity.
+// This file is part of Substrate.
 
-// Parity is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Parity is distributed in the hope that it will be useful,
+// Substrate 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
+use std::fmt;
 use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::net::{SocketAddr, SocketAddrV4, Ipv4Addr};
@@ -213,22 +214,42 @@ impl NetworkConfiguration {
 	}
 }
 
+/// The severity of misbehaviour of a peer that is reported.
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Severity<'a> {
+	/// Peer is timing out. Could be bad connectivity of overload of work on either of our sides.
+	Timeout,
+	/// Peer has been notably useless. E.g. unable to answer a request that we might reasonably consider
+	/// it could answer.
+	Useless(&'a str),
+	/// Peer has behaved in an invalid manner. This doesn't necessarily need to be Byzantine, but peer
+	/// must have taken concrete action in order to behave in such a way which is wantanly invalid. 
+	Bad(&'a str),
+}
+
+impl<'a> fmt::Display for Severity<'a> {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		match *self {
+			Severity::Timeout => write!(fmt, "Timeout"),
+			Severity::Useless(r) => write!(fmt, "Useless ({})", r),
+			Severity::Bad(r) => write!(fmt, "Bad ({})", r),
+		}
+	}
+}
+
 /// IO access point. This is passed to all IO handlers and provides an interface to the IO subsystem.
 pub trait NetworkContext {
 	/// Send a packet over the network to another peer.
-	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error>;
+	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>);
 
 	/// Send a packet over the network to another peer using specified protocol.
-	fn send_protocol(&self, protocol: ProtocolId, peer: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error>;
+	fn send_protocol(&self, protocol: ProtocolId, peer: PeerId, packet_id: PacketId, data: Vec<u8>);
 
 	/// Respond to a current network message. Panics if no there is no packet in the context. If the session is expired returns nothing.
-	fn respond(&self, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error>;
+	fn respond(&self, packet_id: PacketId, data: Vec<u8>);
 
-	/// Disconnect a peer and prevent it from connecting again.
+	/// Report peer. Depending on the report, peer may be disconnected and possibly banned.
-	fn disable_peer(&self, peer: PeerId, reason: &str);
+	fn report_peer(&self, peer: PeerId, reason: Severity);
-
-	/// Disconnect peer. Reconnect can be attempted later.
-	fn disconnect_peer(&self, peer: PeerId);
 
 	/// Check if the session is still active.
 	fn is_expired(&self) -> bool;
@@ -250,24 +271,20 @@ pub trait NetworkContext {
 }
 
 impl<'a, T> NetworkContext for &'a T where T: ?Sized + NetworkContext {
-	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error> {
+	fn send(&self, peer: PeerId, packet_id: PacketId, data: Vec<u8>) {
 		(**self).send(peer, packet_id, data)
 	}
 
-	fn send_protocol(&self, protocol: ProtocolId, peer: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error> {
+	fn send_protocol(&self, protocol: ProtocolId, peer: PeerId, packet_id: PacketId, data: Vec<u8>) {
 		(**self).send_protocol(protocol, peer, packet_id, data)
 	}
 
-	fn respond(&self, packet_id: PacketId, data: Vec<u8>) -> Result<(), Error> {
+	fn respond(&self, packet_id: PacketId, data: Vec<u8>) {
 		(**self).respond(packet_id, data)
 	}
 
-	fn disable_peer(&self, peer: PeerId, reason: &str) {
+	fn report_peer(&self, peer: PeerId, reason: Severity) {
-		(**self).disable_peer(peer, reason)
+		(**self).report_peer(peer, reason)
-	}
-
-	fn disconnect_peer(&self, peer: PeerId) {
-		(**self).disconnect_peer(peer)
 	}
 
 	fn is_expired(&self) -> bool {
@@ -333,42 +350,42 @@ impl NonReservedPeerMode {
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct IpFilter {
-    pub predefined: AllowIP,
+	pub predefined: AllowIP,
-    pub custom_allow: Vec<IpNetwork>,
+	pub custom_allow: Vec<IpNetwork>,
-    pub custom_block: Vec<IpNetwork>,
+	pub custom_block: Vec<IpNetwork>,
 }
 
 impl Default for IpFilter {
-    fn default() -> Self {
+	fn default() -> Self {
-        IpFilter {
+		IpFilter {
-            predefined: AllowIP::All,
+			predefined: AllowIP::All,
-            custom_allow: vec![],
+			custom_allow: vec![],
-            custom_block: vec![],
+			custom_block: vec![],
-        }
+		}
-    }
+	}
 }
 
 impl IpFilter {
-    /// Attempt to parse the peer mode from a string.
+	/// Attempt to parse the peer mode from a string.
-    pub fn parse(s: &str) -> Result<IpFilter, IpNetworkError> {
+	pub fn parse(s: &str) -> Result<IpFilter, IpNetworkError> {
-        let mut filter = IpFilter::default();
+		let mut filter = IpFilter::default();
-        for f in s.split_whitespace() {
+		for f in s.split_whitespace() {
-            match f {
+			match f {
-                "all" => filter.predefined = AllowIP::All,
+				"all" => filter.predefined = AllowIP::All,
-                "private" => filter.predefined = AllowIP::Private,
+				"private" => filter.predefined = AllowIP::Private,
-                "public" => filter.predefined = AllowIP::Public,
+				"public" => filter.predefined = AllowIP::Public,
-                "none" => filter.predefined = AllowIP::None,
+				"none" => filter.predefined = AllowIP::None,
-                custom => {
+				custom => {
-                    if custom.starts_with("-") {
+					if custom.starts_with("-") {
-                        filter.custom_block.push(IpNetwork::from_str(&custom.to_owned().split_off(1))?)
+						filter.custom_block.push(IpNetwork::from_str(&custom.to_owned().split_off(1))?)
-                    } else {
+					} else {
-                        filter.custom_allow.push(IpNetwork::from_str(custom)?)
+						filter.custom_allow.push(IpNetwork::from_str(custom)?)
-                    }
+					}
-                }
+				}
-            }
+			}
-        }
+		}
-        Ok(filter)
+		Ok(filter)
-    }
+	}
 }
 
 /// IP fiter
@@ -380,6 +397,6 @@ pub enum AllowIP {
 	Private,
 	/// Connect to public network only
 	Public,
-    /// Block all addresses
+	/// Block all addresses
-    None,
+	None,
 }

substrate/substrate/network-libp2p/src/transport.rs

@@ -1,18 +1,18 @@
 // Copyright 2018 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate 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.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate 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 Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.?
 
 use libp2p::{self, Transport, mplex, secio, yamux};
 use libp2p::core::{MuxedTransport, either, upgrade};

substrate/substrate/network-libp2p/tests/tests.rs

@@ -73,9 +73,9 @@ impl NetworkProtocolHandler for TestProtocol {
 
 	fn connected(&self, io: &NetworkContext, peer: &PeerId) {
 		if self.drop_session {
-			io.disconnect_peer(*peer)
+			io.report_peer(*peer, Severity::Bad("We are evil and just want to drop"))
 		} else {
-			io.respond(33, "hello".to_owned().into_bytes()).unwrap();
+			io.respond(33, "hello".to_owned().into_bytes());
 		}
 	}
 

substrate/substrate/network/src/import_queue.rs

@@ -22,7 +22,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use parking_lot::{Condvar, Mutex, RwLock};
 
 use client::{BlockOrigin, BlockStatus, ImportResult};
-use network_libp2p::PeerId;
+use network_libp2p::{PeerId, Severity};
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero};
 
@@ -202,9 +202,9 @@ trait SyncLinkApi<B: BlockT> {
 	/// Maintain sync.
 	fn maintain_sync(&mut self);
 	/// Disconnect from peer.
-	fn disconnect(&mut self, peer_id: PeerId);
+	fn useless_peer(&mut self, peer_id: PeerId, reason: &str);
 	/// Disconnect from peer and restart sync.
-	fn disconnect_and_restart(&mut self, peer_id: PeerId);
+	fn note_useless_and_restart_sync(&mut self, peer_id: PeerId, reason: &str);
 	/// Restart sync.
 	fn restart(&mut self);
 }
@@ -357,11 +357,15 @@ fn process_import_result<'a, B: BlockT>(
 			1
 		},
 		Err(BlockImportError::Disconnect(peer_id)) => {
-			link.disconnect(peer_id);
+			// TODO: FIXME: @arkpar BlockImport shouldn't be trying to manage the peer set.
+			// This should contain an actual reason.
+			link.useless_peer(peer_id, "Import result was stated Disconnect");
 			0
 		},
 		Err(BlockImportError::DisconnectAndRestart(peer_id)) => {
-			link.disconnect_and_restart(peer_id);
+			// TODO: FIXME: @arkpar BlockImport shouldn't be trying to manage the peer set.
+			// This should contain an actual reason.
+			link.note_useless_and_restart_sync(peer_id, "Import result was stated DisconnectAndRestart");
 			0
 		},
 		Err(BlockImportError::Restart) => {
@@ -404,13 +408,13 @@ impl<'a, B: 'static + BlockT, E: ExecuteInContext<B>> SyncLinkApi<B> for SyncLin
 		self.with_sync(|sync, protocol| sync.maintain_sync(protocol))
 	}
 
-	fn disconnect(&mut self, peer_id: PeerId) {
+	fn useless_peer(&mut self, peer_id: PeerId, reason: &str) {
-		self.with_sync(|_, protocol| protocol.disconnect_peer(peer_id))
+		self.with_sync(|_, protocol| protocol.report_peer(peer_id, Severity::Useless(reason)))
 	}
 
-	fn disconnect_and_restart(&mut self, peer_id: PeerId) {
+	fn note_useless_and_restart_sync(&mut self, peer_id: PeerId, reason: &str) {
 		self.with_sync(|sync, protocol| {
-			protocol.disconnect_peer(peer_id);
+			protocol.report_peer(peer_id, Severity::Useless(reason));	// is this actually malign or just useless?
 			sync.restart(protocol);
 		})
 	}
@@ -486,8 +490,8 @@ pub mod tests {
 		fn chain(&self) -> &Client<Block> { &*self.chain }
 		fn block_imported(&mut self, _hash: &Hash, _number: NumberFor<Block>) { self.imported += 1; }
 		fn maintain_sync(&mut self) { self.maintains += 1; }
-		fn disconnect(&mut self, _peer_id: PeerId) { self.disconnects += 1; }
+		fn useless_peer(&mut self, _: PeerId, _: &str) { self.disconnects += 1; }
-		fn disconnect_and_restart(&mut self, _peer_id: PeerId) { self.disconnects += 1; self.restarts += 1; }
+		fn note_useless_and_restart_sync(&mut self, _: PeerId, _: &str) { self.disconnects += 1; self.restarts += 1; }
 		fn restart(&mut self) { self.restarts += 1; }
 	}
 

substrate/substrate/network/src/io.rs

@@ -14,17 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.?
 
-use network_libp2p::{NetworkContext, PeerId, Error as NetworkError, SessionInfo};
+use network_libp2p::{NetworkContext, Severity, PeerId, SessionInfo};
 
 /// IO interface for the syncing handler.
 /// Provides peer connection management and an interface to the blockchain client.
 pub trait SyncIo {
-	/// Disable a peer
+	/// Report a peer for misbehaviour.
-	fn disable_peer(&mut self, peer_id: PeerId, reason: &str);
+	fn report_peer(&mut self, peer_id: PeerId, reason: Severity);
-	/// Disconnect peer
-	fn disconnect_peer(&mut self, peer_id: PeerId);
 	/// Send a packet to a peer.
-	fn send(&mut self, peer_id: PeerId, data: Vec<u8>) -> Result<(), NetworkError>;
+	fn send(&mut self, peer_id: PeerId, data: Vec<u8>);
 	/// Returns peer identifier string
 	fn peer_info(&self, peer_id: PeerId) -> String {
 		peer_id.to_string()
@@ -50,15 +48,11 @@ impl<'s> NetSyncIo<'s> {
 }
 
 impl<'s> SyncIo for NetSyncIo<'s> {
-	fn disable_peer(&mut self, peer_id: PeerId, reason: &str) {
+	fn report_peer(&mut self, peer_id: PeerId, reason: Severity) {
-		self.network.disable_peer(peer_id, reason);
+		self.network.report_peer(peer_id, reason);
 	}
 
-	fn disconnect_peer(&mut self, peer_id: PeerId) {
+	fn send(&mut self, peer_id: PeerId, data: Vec<u8>) {
-		self.network.disconnect_peer(peer_id);
-	}
-
-	fn send(&mut self, peer_id: PeerId, data: Vec<u8>) -> Result<(), NetworkError>{
 		self.network.send(peer_id, 0, data)
 	}
 

substrate/substrate/network/src/lib.rs

@@ -59,7 +59,7 @@ pub use service::{Service, FetchFuture, ConsensusService, BftMessageStream,
 	TransactionPool, Params, ManageNetwork, SyncProvider};
 pub use protocol::{ProtocolStatus, PeerInfo, Context};
 pub use sync::{Status as SyncStatus, SyncState};
-pub use network_libp2p::{NonReservedPeerMode, NetworkConfiguration, PeerId, ProtocolId, ConnectionFilter, ConnectionDirection};
+pub use network_libp2p::{NonReservedPeerMode, NetworkConfiguration, PeerId, ProtocolId, ConnectionFilter, ConnectionDirection, Severity};
 pub use message::{generic as generic_message, RequestId, BftMessage, LocalizedBftMessage, ConsensusVote, SignedConsensusVote, SignedConsensusMessage, SignedConsensusProposal, Status as StatusMessage};
 pub use error::Error;
 pub use config::{Roles, ProtocolConfig};

substrate/substrate/network/src/on_demand.rs

@@ -28,7 +28,7 @@ use client;
 use client::light::fetcher::{Fetcher, FetchChecker, RemoteCallRequest};
 use io::SyncIo;
 use message;
-use network_libp2p::PeerId;
+use network_libp2p::{Severity, PeerId};
 use service;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT};
 
@@ -137,8 +137,7 @@ impl<B: BlockT, E> OnDemand<B, E> where
 		let request = match core.remove(peer, request_id) {
 			Some(request) => request,
 			None => {
-				trace!(target: "sync", "Invalid remote {} response from peer {}", rtype, peer);
+				io.report_peer(peer, Severity::Bad(&format!("Invalid remote {} response from peer", rtype)));
-				io.disconnect_peer(peer);
 				core.remove_peer(peer);
 				return;
 			},
@@ -147,9 +146,7 @@ impl<B: BlockT, E> OnDemand<B, E> where
 		let retry_request_data = match try_accept(request) {
 			Accept::Ok => None,
 			Accept::CheckFailed(error, retry_request_data) => {
-				trace!(target: "sync", "Failed to check remote {} response from peer {}: {}", rtype, peer, error);
+				io.report_peer(peer, Severity::Bad(&format!("Failed to check remote {} response from peer: {}", rtype, error)));
-
-				io.disconnect_peer(peer);
 				core.remove_peer(peer);
 				Some(retry_request_data)
 			},
@@ -187,8 +184,7 @@ impl<B, E> OnDemandService<B> for OnDemand<B, E> where
 	fn maintain_peers(&self, io: &mut SyncIo) {
 		let mut core = self.core.lock();
 		for bad_peer in core.maintain_peers() {
-			trace!(target: "sync", "Remote request timeout for peer {}", bad_peer);
+			io.report_peer(bad_peer, Severity::Timeout);
-			io.disconnect_peer(bad_peer);
 		}
 		core.dispatch();
 	}

substrate/substrate/network/src/protocol.rs

@@ -21,7 +21,7 @@ use std::time;
 use parking_lot::RwLock;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, Hash, HashFor, As};
 use runtime_primitives::generic::BlockId;
-use network_libp2p::PeerId;
+use network_libp2p::{PeerId, Severity};
 use codec::{Encode, Decode};
 
 use message::{self, Message};
@@ -43,7 +43,6 @@ pub (crate) const CURRENT_VERSION: u32 = 1;
 /// Current packet count.
 pub (crate) const CURRENT_PACKET_COUNT: u8 = 1;
 
-
 // Maximum allowed entries in `BlockResponse`
 const MAX_BLOCK_DATA_RESPONSE: u32 = 128;
 
@@ -110,11 +109,8 @@ pub trait Context<B: BlockT> {
 	/// Get a reference to the client.
 	fn client(&self) -> &::chain::Client<B>;
 
-	/// Disable a peer
+	/// Point out that a peer has been malign or irresponsible or appeared lazy.
-	fn disable_peer(&mut self, peer_id: PeerId, reason: &str);
+	fn report_peer(&mut self, peer_id: PeerId, reason: Severity);
-
-	/// Disconnect peer
-	fn disconnect_peer(&mut self, peer_id: PeerId);
 
 	/// Get peer info.
 	fn peer_info(&self, peer: PeerId) -> Option<PeerInfo<B>>;
@@ -142,12 +138,9 @@ impl<'a, B: BlockT + 'a> ProtocolContext<'a, B> {
 		send_message(&self.context_data.peers, self.io, peer_id, message)
 	}
 
-	pub fn disable_peer(&mut self, peer_id: PeerId, reason: &str) {
+	/// Point out that a peer has been malign or irresponsible or appeared lazy.
-		self.io.disable_peer(peer_id, reason);
+	pub fn report_peer(&mut self, peer_id: PeerId, reason: Severity) {
-	}
+		self.io.report_peer(peer_id, reason);
-
-	pub fn disconnect_peer(&mut self, peer_id: PeerId) {
-		self.io.disconnect_peer(peer_id)
 	}
 
 	/// Get peer info.
@@ -168,12 +161,8 @@ impl<'a, B: BlockT + 'a> Context<B> for ProtocolContext<'a, B> {
 		ProtocolContext::send_message(self, peer_id, message);
 	}
 
-	fn disable_peer(&mut self, peer_id: PeerId, reason: &str) {
+	fn report_peer(&mut self, peer_id: PeerId, reason: Severity) {
-		ProtocolContext::disable_peer(self, peer_id, reason);
+		ProtocolContext::report_peer(self, peer_id, reason);
-	}
-
-	fn disconnect_peer(&mut self, peer_id: PeerId) {
-		ProtocolContext::disconnect_peer(self, peer_id);
 	}
 
 	fn peer_info(&self, peer_id: PeerId) -> Option<PeerInfo<B>> {
@@ -244,7 +233,7 @@ impl<B: BlockT, S: Specialization<B>> Protocol<B, S> {
 			Some(m) => m,
 			None => {
 				trace!(target: "sync", "Invalid packet from {}", peer_id);
-				io.disable_peer(peer_id, "Peer sent us a packet with invalid format");
+				io.report_peer(peer_id, Severity::Bad("Peer sent us a packet with invalid format"));
 				return;
 			}
 		};
@@ -260,12 +249,12 @@ impl<B: BlockT, S: Specialization<B>> Protocol<B, S> {
 						match mem::replace(&mut peer.block_request, None) {
 							Some(r) => r,
 							None => {
-								io.disable_peer(peer_id, "Unexpected response packet received from peer");
+								io.report_peer(peer_id, Severity::Bad("Unexpected response packet received from peer"));
 								return;
 							}
 						}
 					} else {
-						io.disable_peer(peer_id, "Unexpected packet received from peer");
+						io.report_peer(peer_id, Severity::Bad("Unexpected packet received from peer"));
 						return;
 					}
 				};
@@ -385,7 +374,6 @@ impl<B: BlockT, S: Specialization<B>> Protocol<B, S> {
 				.chain(handshaking_peers.iter()) {
 				if (tick - *timestamp).as_secs() > REQUEST_TIMEOUT_SEC {
 					trace!(target: "sync", "Timeout {}", peer_id);
-					io.disconnect_peer(*peer_id);
 					aborting.push(*peer_id);
 				}
 			}
@@ -393,7 +381,7 @@ impl<B: BlockT, S: Specialization<B>> Protocol<B, S> {
 
 		self.specialization.write().maintain_peers(&mut ProtocolContext::new(&self.context_data, io));
 		for p in aborting {
-			io.disconnect_peer(p);
+			io.report_peer(p, Severity::Timeout);
 		}
 	}
 
@@ -424,11 +412,11 @@ impl<B: BlockT, S: Specialization<B>> Protocol<B, S> {
 				return;
 			}
 			if status.genesis_hash != self.genesis_hash {
-				io.disable_peer(peer_id, &format!("Peer is on different chain (our genesis: {} theirs: {})", self.genesis_hash, status.genesis_hash));
+				io.report_peer(peer_id, Severity::Bad(&format!("Peer is on different chain (our genesis: {} theirs: {})", self.genesis_hash, status.genesis_hash)));
 				return;
 			}
 			if status.version != CURRENT_VERSION {
-				io.disable_peer(peer_id, &format!("Peer using unsupported protocol version {}", status.version));
+				io.report_peer(peer_id, Severity::Bad(&format!("Peer using unsupported protocol version {}", status.version)));
 				return;
 			}
 
@@ -625,11 +613,7 @@ fn send_message<B: BlockT>(peers: &RwLock<HashMap<PeerId, Peer<B>>>, io: &mut Sy
 		},
 		_ => (),
 	}
-	let data = message.encode();
+	io.send(peer_id, message.encode());
-	if let Err(e) = io.send(peer_id, data) {
-		debug!(target:"sync", "Error sending message: {:?}", e);
-		io.disconnect_peer(peer_id);
-	}
 }
 
 /// Hash a message.

substrate/substrate/network/src/sync.rs

@@ -17,7 +17,7 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 use protocol::Context;
-use network_libp2p::PeerId;
+use network_libp2p::{Severity, PeerId};
 use client::{BlockStatus, BlockOrigin, ClientInfo};
 use client::error::Error as ClientError;
 use blocks::{self, BlockCollection};
@@ -124,13 +124,13 @@ impl<B: BlockT> ChainSync<B> {
 			match (block_status(&*protocol.client(), &*self.import_queue, info.best_hash), info.best_number) {
 				(Err(e), _) => {
 					debug!(target:"sync", "Error reading blockchain: {:?}", e);
-					protocol.disconnect_peer(peer_id);
+					protocol.report_peer(peer_id, Severity::Useless(&format!("Error legimimately reading blockchain status: {:?}", e)));
 				},
 				(Ok(BlockStatus::KnownBad), _) => {
-					protocol.disable_peer(peer_id, &format!("New peer with known bad best block {} ({}).", info.best_hash, info.best_number));
+					protocol.report_peer(peer_id, Severity::Bad(&format!("New peer with known bad best block {} ({}).", info.best_hash, info.best_number)));
 				},
 				(Ok(BlockStatus::Unknown), b) if b == As::sa(0) => {
-					protocol.disable_peer(peer_id, &format!("New peer with unknown genesis hash {} ({}).", info.best_hash, info.best_number));
+					protocol.report_peer(peer_id, Severity::Bad(&format!("New peer with unknown genesis hash {} ({}).", info.best_hash, info.best_number)));
 				},
 				(Ok(BlockStatus::Unknown), _) => {
 					let our_best = self.best_queued_number;
@@ -211,19 +211,18 @@ impl<B: BlockT> ChainSync<B> {
 								},
 								Ok(_) => { // genesis mismatch
 									trace!(target:"sync", "Ancestry search: genesis mismatch for peer {}", peer_id);
-									protocol.disable_peer(peer_id, "Ancestry search: genesis mismatch for peer");
+									protocol.report_peer(peer_id, Severity::Bad("Ancestry search: genesis mismatch for peer"));
 									return;
 								},
 								Err(e) => {
-									debug!(target:"sync", "Error reading blockchain: {:?}", e);
+									protocol.report_peer(peer_id, Severity::Useless(&format!("Error answering legitimate blockchain query: {:?}", e)));
-									protocol.disconnect_peer(peer_id);
 									return;
 								}
 							}
 						},
 						None => {
 							trace!(target:"sync", "Invalid response when searching for ancestor from {}", peer_id);
-							protocol.disconnect_peer(peer_id);
+							protocol.report_peer(peer_id, Severity::Bad("Invalid response when searching for ancestor"));
 							return;
 						}
 					}

substrate/substrate/network/src/test/mod.rs

@@ -28,7 +28,7 @@ use io::SyncIo;
 use protocol::{Context, Protocol};
 use config::ProtocolConfig;
 use service::TransactionPool;
-use network_libp2p::{PeerId, SessionInfo, Error as NetworkError};
+use network_libp2p::{PeerId, SessionInfo, Severity};
 use keyring::Keyring;
 use codec::Encode;
 use import_queue::tests::SyncImportQueue;
@@ -81,11 +81,7 @@ impl<'p> Drop for TestIo<'p> {
 }
 
 impl<'p> SyncIo for TestIo<'p> {
-	fn disable_peer(&mut self, peer_id: PeerId, _reason: &str) {
+	fn report_peer(&mut self, peer_id: PeerId, _reason: Severity) {
-		self.disconnect_peer(peer_id);
-	}
-
-	fn disconnect_peer(&mut self, peer_id: PeerId) {
 		self.to_disconnect.insert(peer_id);
 	}
 
@@ -93,12 +89,11 @@ impl<'p> SyncIo for TestIo<'p> {
 		false
 	}
 
-	fn send(&mut self, peer_id: PeerId, data: Vec<u8>) -> Result<(), NetworkError> {
+	fn send(&mut self, peer_id: PeerId, data: Vec<u8>) {
 		self.packets.push(TestPacket {
 			data: data,
 			recipient: peer_id,
 		});
-		Ok(())
 	}
 
 	fn peer_info(&self, peer_id: PeerId) -> String {