Switch to new light client protocol (#5472)

* Switch to the new protocol

* Oops, forgot to remove light_dispatch.rs

* Fix tests

* Address review

substrate/client/network/src/behaviour.rs

@@ -133,7 +133,6 @@ impl<B: BlockT, H: ExHashT> Behaviour<B, H> {
 	}
 
 	/// Issue a light client request.
-	#[allow(unused)]
 	pub fn light_client_request(&mut self, r: light_client_handler::Request<B>) -> Result<(), light_client_handler::Error> {
 		self.light_client_handler.request(r)
 	}
@@ -175,6 +174,9 @@ Behaviour<B, H> {
 				let ev = Event::NotificationsReceived { remote, messages };
 				self.events.push(BehaviourOut::Event(ev));
 			},
+			CustomMessageOutcome::PeerNewBest(peer_id, number) => {
+				self.light_client_handler.update_best_block(&peer_id, number);
+			}
 			CustomMessageOutcome::None => {}
 		}
 	}

substrate/client/network/src/config.rs

@@ -20,7 +20,7 @@
 //! See the documentation of [`Params`].
 
 pub use crate::chain::{Client, FinalityProofProvider};
-pub use crate::on_demand_layer::OnDemand;
+pub use crate::on_demand_layer::{AlwaysBadChecker, OnDemand};
 pub use crate::service::{TransactionPool, EmptyTransactionPool};
 pub use libp2p::{identity, core::PublicKey, wasm_ext::ExtTransport, build_multiaddr};
 

substrate/client/network/src/on_demand_layer.rs

@@ -16,16 +16,17 @@
 
 //! On-demand requests service.
 
-use crate::protocol::light_dispatch::RequestData;
-use std::{collections::HashMap, pin::Pin, sync::Arc, task::Context, task::Poll};
-use futures::{prelude::*, channel::mpsc, channel::oneshot};
+use crate::protocol::light_client_handler;
+
+use futures::{channel::mpsc, channel::oneshot, prelude::*};
 use parking_lot::Mutex;
-use sp_blockchain::Error as ClientError;
 use sc_client_api::{
-	Fetcher, FetchChecker, RemoteHeaderRequest, RemoteCallRequest, RemoteReadRequest,
-	RemoteChangesRequest, RemoteReadChildRequest, RemoteBodyRequest,
+	FetchChecker, Fetcher, RemoteBodyRequest, RemoteCallRequest, RemoteChangesRequest,
+	RemoteHeaderRequest, RemoteReadChildRequest, RemoteReadRequest, StorageProof, ChangesProof,
 };
+use sp_blockchain::Error as ClientError;
 use sp_runtime::traits::{Block as BlockT, Header as HeaderT, NumberFor};
+use std::{collections::HashMap, pin::Pin, sync::Arc, task::Context, task::Poll};
 
 /// Implements the `Fetcher` trait of the client. Makes it possible for the light client to perform
 /// network requests for some state.
@@ -41,13 +42,72 @@ pub struct OnDemand<B: BlockT> {
 	/// Note that a better alternative would be to use a MPMC queue here, and add a `poll` method
 	/// from the `OnDemand`. However there exists no popular implementation of MPMC channels in
 	/// asynchronous Rust at the moment
-	requests_queue: Mutex<Option<mpsc::UnboundedReceiver<RequestData<B>>>>,
+	requests_queue: Mutex<Option<mpsc::UnboundedReceiver<light_client_handler::Request<B>>>>,
 
 	/// Sending side of `requests_queue`.
-	requests_send: mpsc::UnboundedSender<RequestData<B>>,
+	requests_send: mpsc::UnboundedSender<light_client_handler::Request<B>>,
 }
 
-impl<B: BlockT> OnDemand<B> where
+/// Dummy implementation of `FetchChecker` that always assumes that responses are bad.
+///
+/// Considering that it is the responsibility of the client to build the fetcher, it can use this
+/// implementation if it knows that it will never perform any request.
+#[derive(Default, Clone)]
+pub struct AlwaysBadChecker;
+
+impl<Block: BlockT> FetchChecker<Block> for AlwaysBadChecker {
+	fn check_header_proof(
+		&self,
+		_request: &RemoteHeaderRequest<Block::Header>,
+		_remote_header: Option<Block::Header>,
+		_remote_proof: StorageProof,
+	) -> Result<Block::Header, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+
+	fn check_read_proof(
+		&self,
+		_request: &RemoteReadRequest<Block::Header>,
+		_remote_proof: StorageProof,
+	) -> Result<HashMap<Vec<u8>,Option<Vec<u8>>>, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+
+	fn check_read_child_proof(
+		&self,
+		_request: &RemoteReadChildRequest<Block::Header>,
+		_remote_proof: StorageProof,
+	) -> Result<HashMap<Vec<u8>, Option<Vec<u8>>>, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+
+	fn check_execution_proof(
+		&self,
+		_request: &RemoteCallRequest<Block::Header>,
+		_remote_proof: StorageProof,
+	) -> Result<Vec<u8>, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+
+	fn check_changes_proof(
+		&self,
+		_request: &RemoteChangesRequest<Block::Header>,
+		_remote_proof: ChangesProof<Block::Header>
+	) -> Result<Vec<(NumberFor<Block>, u32)>, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+
+	fn check_body_proof(
+		&self,
+		_request: &RemoteBodyRequest<Block::Header>,
+		_body: Vec<Block::Extrinsic>
+	) -> Result<Vec<Block::Extrinsic>, ClientError> {
+		Err(ClientError::Msg("AlwaysBadChecker".into()))
+	}
+}
+
+impl<B: BlockT> OnDemand<B>
+where
 	B::Header: HeaderT,
 {
 	/// Creates new on-demand service.
@@ -74,12 +134,15 @@ impl<B: BlockT> OnDemand<B> where
 	///
 	/// If this function returns `None`, that means that the receiver has already been extracted in
 	/// the past, and therefore that something already handles the requests.
-	pub(crate) fn extract_receiver(&self) -> Option<mpsc::UnboundedReceiver<RequestData<B>>> {
+	pub(crate) fn extract_receiver(
+		&self,
+	) -> Option<mpsc::UnboundedReceiver<light_client_handler::Request<B>>> {
 		self.requests_queue.lock().take()
 	}
 }
 
-impl<B> Fetcher<B> for OnDemand<B> where
+impl<B> Fetcher<B> for OnDemand<B>
+where
 	B: BlockT,
 	B::Header: HeaderT,
 {
@@ -91,40 +154,55 @@ impl<B> Fetcher<B> for OnDemand<B> where
 
 	fn remote_header(&self, request: RemoteHeaderRequest<B::Header>) -> Self::RemoteHeaderResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteHeader(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::Header { request, sender });
 		RemoteResponse { receiver }
 	}
 
 	fn remote_read(&self, request: RemoteReadRequest<B::Header>) -> Self::RemoteReadResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteRead(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::Read { request, sender });
 		RemoteResponse { receiver }
 	}
 
 	fn remote_read_child(
 		&self,
-		request: RemoteReadChildRequest<B::Header>
+		request: RemoteReadChildRequest<B::Header>,
 	) -> Self::RemoteReadResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteReadChild(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::ReadChild { request, sender });
 		RemoteResponse { receiver }
 	}
 
 	fn remote_call(&self, request: RemoteCallRequest<B::Header>) -> Self::RemoteCallResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteCall(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::Call { request, sender });
 		RemoteResponse { receiver }
 	}
 
-	fn remote_changes(&self, request: RemoteChangesRequest<B::Header>) -> Self::RemoteChangesResult {
+	fn remote_changes(
+		&self,
+		request: RemoteChangesRequest<B::Header>,
+	) -> Self::RemoteChangesResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteChanges(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::Changes { request, sender });
 		RemoteResponse { receiver }
 	}
 
 	fn remote_body(&self, request: RemoteBodyRequest<B::Header>) -> Self::RemoteBodyResult {
 		let (sender, receiver) = oneshot::channel();
-		let _ = self.requests_send.unbounded_send(RequestData::RemoteBody(request, sender));
+		let _ = self
+			.requests_send
+			.unbounded_send(light_client_handler::Request::Body { request, sender });
 		RemoteResponse { receiver }
 	}
 }

substrate/client/network/src/protocol.rs

@@ -38,21 +38,20 @@ use sp_runtime::traits::{
 	Block as BlockT, Header as HeaderT, NumberFor, One, Zero, CheckedSub
 };
 use sp_arithmetic::traits::SaturatedConversion;
-use message::{BlockAnnounce, BlockAttributes, Direction, FromBlock, Message, RequestId};
+use message::{BlockAnnounce, Message};
 use message::generic::{Message as GenericMessage, ConsensusMessage};
-use light_dispatch::{LightDispatch, LightDispatchNetwork, RequestData};
 use prometheus_endpoint::{Registry, Gauge, GaugeVec, PrometheusError, Opts, register, U64};
 use sync::{ChainSync, SyncState};
 use crate::service::{TransactionPool, ExHashT};
 use crate::config::{BoxFinalityProofRequestBuilder, Roles};
 use std::borrow::Cow;
-use std::collections::{BTreeMap, HashMap, HashSet};
+use std::collections::{BTreeMap, HashMap, HashSet, VecDeque};
 use std::sync::Arc;
 use std::fmt::Write;
 use std::{cmp, num::NonZeroUsize, pin::Pin, task::Poll, time};
 use log::{log, Level, trace, debug, warn, error};
 use crate::chain::{Client, FinalityProofProvider};
-use sc_client_api::{FetchChecker, ChangesProof, StorageProof};
+use sc_client_api::{ChangesProof, StorageProof};
 use crate::error;
 use util::LruHashSet;
 use wasm_timer::Instant;
@@ -74,7 +73,6 @@ pub mod block_requests;
 pub mod message;
 pub mod event;
 pub mod light_client_handler;
-pub mod light_dispatch;
 pub mod sync;
 
 pub use block_requests::BlockRequests;
@@ -201,9 +199,9 @@ pub struct Protocol<B: BlockT, H: ExHashT> {
 	tick_timeout: Pin<Box<dyn Stream<Item = ()> + Send>>,
 	/// Interval at which we call `propagate_extrinsics`.
 	propagate_timeout: Pin<Box<dyn Stream<Item = ()> + Send>>,
+	/// Pending list of messages to return from `poll` as a priority.
+	pending_messages: VecDeque<CustomMessageOutcome<B>>,
 	config: ProtocolConfig,
-	/// Handler for light client requests.
-	light_dispatch: LightDispatch<B>,
 	genesis_hash: B::Hash,
 	sync: ChainSync<B>,
 	context_data: ContextData<B, H>,
@@ -276,132 +274,6 @@ pub struct PeerInfo<B: BlockT> {
 	pub best_number: <B::Header as HeaderT>::Number,
 }
 
-struct LightDispatchIn<'a> {
-	behaviour: &'a mut GenericProto,
-	peerset: sc_peerset::PeersetHandle,
-}
-
-impl<'a, B: BlockT> LightDispatchNetwork<B> for LightDispatchIn<'a> {
-	fn report_peer(&mut self, who: &PeerId, reputation: sc_peerset::ReputationChange) {
-		self.peerset.report_peer(who.clone(), reputation)
-	}
-
-	fn disconnect_peer(&mut self, who: &PeerId) {
-		self.behaviour.disconnect_peer(who)
-	}
-
-	fn send_header_request(&mut self, who: &PeerId, id: RequestId, block: <<B as BlockT>::Header as HeaderT>::Number) {
-		let message: Message<B> = message::generic::Message::RemoteHeaderRequest(message::RemoteHeaderRequest {
-			id,
-			block,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-
-	fn send_read_request(
-		&mut self,
-		who: &PeerId,
-		id: RequestId,
-		block: <B as BlockT>::Hash,
-		keys: Vec<Vec<u8>>,
-	) {
-		let message: Message<B> = message::generic::Message::RemoteReadRequest(message::RemoteReadRequest {
-			id,
-			block,
-			keys,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-
-	fn send_read_child_request(
-		&mut self,
-		who: &PeerId,
-		id: RequestId,
-		block: <B as BlockT>::Hash,
-		storage_key: Vec<u8>,
-		child_info: Vec<u8>,
-		child_type: u32,
-		keys: Vec<Vec<u8>>,
-	) {
-		let message: Message<B> = message::generic::Message::RemoteReadChildRequest(message::RemoteReadChildRequest {
-			id,
-			block,
-			storage_key,
-			child_info,
-			child_type,
-			keys,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-
-	fn send_call_request(
-		&mut self,
-		who: &PeerId,
-		id: RequestId,
-		block: <B as BlockT>::Hash,
-		method: String,
-		data: Vec<u8>
-	) {
-		let message: Message<B> = message::generic::Message::RemoteCallRequest(message::RemoteCallRequest {
-			id,
-			block,
-			method,
-			data,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-
-	fn send_changes_request(
-		&mut self,
-		who: &PeerId,
-		id: RequestId,
-		first: <B as BlockT>::Hash,
-		last: <B as BlockT>::Hash,
-		min: <B as BlockT>::Hash,
-		max: <B as BlockT>::Hash,
-		storage_key: Option<Vec<u8>>,
-		key: Vec<u8>,
-	) {
-		let message: Message<B> = message::generic::Message::RemoteChangesRequest(message::RemoteChangesRequest {
-			id,
-			first,
-			last,
-			min,
-			max,
-			storage_key,
-			key,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-
-	fn send_body_request(
-		&mut self,
-		who: &PeerId,
-		id: RequestId,
-		fields: BlockAttributes,
-		from: FromBlock<<B as BlockT>::Hash, <<B as BlockT>::Header as HeaderT>::Number>,
-		to: Option<<B as BlockT>::Hash>,
-		direction: Direction,
-		max: Option<u32>
-	) {
-		let message: Message<B> = message::generic::Message::BlockRequest(message::BlockRequest::<B> {
-			id,
-			fields,
-			from,
-			to,
-			direction,
-			max,
-		});
-
-		self.behaviour.send_packet(who, message.encode())
-	}
-}
-
 /// Data necessary to create a context.
 struct ContextData<B: BlockT, H: ExHashT> {
 	// All connected peers
@@ -444,7 +316,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 	pub fn new(
 		config: ProtocolConfig,
 		chain: Arc<dyn Client<B>>,
-		checker: Arc<dyn FetchChecker<B>>,
 		transaction_pool: Arc<dyn TransactionPool<H, B>>,
 		finality_proof_provider: Option<Arc<dyn FinalityProofProvider<B>>>,
 		finality_proof_request_builder: Option<BoxFinalityProofRequestBuilder<B>>,
@@ -500,13 +371,13 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		let protocol = Protocol {
 			tick_timeout: Box::pin(interval(TICK_TIMEOUT)),
 			propagate_timeout: Box::pin(interval(PROPAGATE_TIMEOUT)),
+			pending_messages: VecDeque::new(),
 			config,
 			context_data: ContextData {
 				peers: HashMap::new(),
 				stats: HashMap::new(),
 				chain,
 			},
-			light_dispatch: LightDispatch::new(checker),
 			genesis_hash: info.genesis_hash,
 			sync,
 			handshaking_peers: HashMap::new(),
@@ -609,20 +480,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		self.sync.num_sync_requests()
 	}
 
-	/// Starts a new data demand request.
-	///
-	/// The parameter contains a `Sender` where the result, once received, must be sent.
-	pub(crate) fn add_light_client_request(&mut self, rq: RequestData<B>) {
-		self.light_dispatch.add_request(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, rq);
-	}
-
-	fn is_light_response(&self, who: &PeerId, response_id: message::RequestId) -> bool {
-		self.light_dispatch.is_light_response(&who, response_id)
-	}
-
 	fn handle_response(
 		&mut self,
 		who: PeerId,
@@ -682,15 +539,10 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 			GenericMessage::Status(s) => return self.on_status_message(who, s),
 			GenericMessage::BlockRequest(r) => self.on_block_request(who, r),
 			GenericMessage::BlockResponse(r) => {
-				// Note, this is safe because only `ordinary bodies` and `remote bodies` are received in this matter.
-				if self.is_light_response(&who, r.id) {
-					self.on_remote_body_response(who, r);
-				} else {
-					if let Some(request) = self.handle_response(who.clone(), &r) {
-						let outcome = self.on_block_response(who.clone(), request, r);
-						self.update_peer_info(&who);
-						return outcome
-					}
+				if let Some(request) = self.handle_response(who.clone(), &r) {
+					let outcome = self.on_block_response(who.clone(), request, r);
+					self.update_peer_info(&who);
+					return outcome
 				}
 			},
 			GenericMessage::BlockAnnounce(announce) => {
@@ -701,20 +553,20 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 			GenericMessage::Transactions(m) =>
 				self.on_extrinsics(who, m),
 			GenericMessage::RemoteCallRequest(request) => self.on_remote_call_request(who, request),
-			GenericMessage::RemoteCallResponse(response) =>
-				self.on_remote_call_response(who, response),
+			GenericMessage::RemoteCallResponse(_) =>
+				warn!(target: "sub-libp2p", "Received unexpected RemoteCallResponse"),
 			GenericMessage::RemoteReadRequest(request) =>
 				self.on_remote_read_request(who, request),
-			GenericMessage::RemoteReadResponse(response) =>
-				self.on_remote_read_response(who, response),
+			GenericMessage::RemoteReadResponse(_) =>
+				warn!(target: "sub-libp2p", "Received unexpected RemoteReadResponse"),
 			GenericMessage::RemoteHeaderRequest(request) =>
 				self.on_remote_header_request(who, request),
-			GenericMessage::RemoteHeaderResponse(response) =>
-				self.on_remote_header_response(who, response),
+			GenericMessage::RemoteHeaderResponse(_) =>
+				warn!(target: "sub-libp2p", "Received unexpected RemoteHeaderResponse"),
 			GenericMessage::RemoteChangesRequest(request) =>
 				self.on_remote_changes_request(who, request),
-			GenericMessage::RemoteChangesResponse(response) =>
-				self.on_remote_changes_response(who, response),
+			GenericMessage::RemoteChangesResponse(_) =>
+				warn!(target: "sub-libp2p", "Received unexpected RemoteChangesResponse"),
 			GenericMessage::FinalityProofRequest(request) =>
 				self.on_finality_proof_request(who, request),
 			GenericMessage::FinalityProofResponse(response) =>
@@ -805,10 +657,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		};
 		if let Some(_peer_data) = removed {
 			self.sync.peer_disconnected(peer.clone());
-			self.light_dispatch.on_disconnect(LightDispatchIn {
-				behaviour: &mut self.behaviour,
-				peerset: self.peerset_handle.clone(),
-			}, &peer);
 
 			// Notify all the notification protocols as closed.
 			CustomMessageOutcome::NotificationStreamClosed {
@@ -989,10 +837,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 	/// > **Note**: This method normally doesn't have to be called except for testing purposes.
 	pub fn tick(&mut self) {
 		self.maintain_peers();
-		self.light_dispatch.maintain_peers(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		});
 		self.report_metrics()
 	}
 
@@ -1140,10 +984,7 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		};
 
 		let info = self.context_data.peers.get(&who).expect("We just inserted above; QED").info.clone();
-		self.light_dispatch.on_connect(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who.clone(), status.roles, status.best_number);
+		self.pending_messages.push_back(CustomMessageOutcome::PeerNewBest(who.clone(), status.best_number));
 		if info.roles.is_full() {
 			match self.sync.new_peer(who.clone(), info.best_hash, info.best_number) {
 				Ok(None) => (),
@@ -1408,13 +1249,11 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		announce: BlockAnnounce<B::Header>,
 	) -> CustomMessageOutcome<B> {
 		let hash = announce.header.hash();
+		let number = *announce.header.number();
+
 		if let Some(ref mut peer) = self.context_data.peers.get_mut(&who) {
 			peer.known_blocks.insert(hash.clone());
 		}
-		self.light_dispatch.update_best_number(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who.clone(), *announce.header.number());
 
 		let is_their_best = match announce.state.unwrap_or(message::BlockState::Best) {
 			message::BlockState::Best => true,
@@ -1429,7 +1268,11 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 				// 1) we're on light client;
 				// AND
 				// 2) parent block is already imported and not pruned.
-				return CustomMessageOutcome::None
+				if is_their_best {
+					return CustomMessageOutcome::PeerNewBest(who, number);
+				} else {
+					return CustomMessageOutcome::None;
+				}
 			}
 			sync::OnBlockAnnounce::ImportHeader => () // We proceed with the import.
 		}
@@ -1454,15 +1297,28 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 			},
 		);
 		match blocks_to_import {
-			Ok(sync::OnBlockData::Import(origin, blocks)) => CustomMessageOutcome::BlockImport(origin, blocks),
+			Ok(sync::OnBlockData::Import(origin, blocks)) => {
+				if is_their_best {
+					self.pending_messages.push_back(CustomMessageOutcome::PeerNewBest(who, number));
+				}
+				CustomMessageOutcome::BlockImport(origin, blocks)
+			},
 			Ok(sync::OnBlockData::Request(peer, req)) => {
 				self.send_request(&peer, GenericMessage::BlockRequest(req));
-				CustomMessageOutcome::None
+				if is_their_best {
+					CustomMessageOutcome::PeerNewBest(who, number)
+				} else {
+					CustomMessageOutcome::None
+				}
 			}
 			Err(sync::BadPeer(id, repu)) => {
 				self.behaviour.disconnect_peer(&id);
 				self.peerset_handle.report_peer(id, repu);
-				CustomMessageOutcome::None
+				if is_their_best {
+					CustomMessageOutcome::PeerNewBest(who, number)
+				} else {
+					CustomMessageOutcome::None
+				}
 			}
 		}
 	}
@@ -1597,18 +1453,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		self.sync.on_finality_proof_import(request_block, finalization_result)
 	}
 
-	fn on_remote_call_response(
-		&mut self,
-		who: PeerId,
-		response: message::RemoteCallResponse
-	) {
-		trace!(target: "sync", "Remote call response {} from {}", response.id, who);
-		self.light_dispatch.on_remote_call_response(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who, response);
-	}
-
 	fn on_remote_read_request(
 		&mut self,
 		who: PeerId,
@@ -1723,18 +1567,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		);
 	}
 
-	fn on_remote_read_response(
-		&mut self,
-		who: PeerId,
-		response: message::RemoteReadResponse
-	) {
-		trace!(target: "sync", "Remote read response {} from {}", response.id, who);
-		self.light_dispatch.on_remote_read_response(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who, response);
-	}
-
 	fn on_remote_header_request(
 		&mut self,
 		who: PeerId,
@@ -1765,18 +1597,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		);
 	}
 
-	fn on_remote_header_response(
-		&mut self,
-		who: PeerId,
-		response: message::RemoteHeaderResponse<B::Header>,
-	) {
-		trace!(target: "sync", "Remote header proof response {} from {}", response.id, who);
-		self.light_dispatch.on_remote_header_response(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who, response);
-	}
-
 	fn on_remote_changes_request(
 		&mut self,
 		who: PeerId,
@@ -1838,22 +1658,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		);
 	}
 
-	fn on_remote_changes_response(
-		&mut self,
-		who: PeerId,
-		response: message::RemoteChangesResponse<NumberFor<B>, B::Hash>,
-	) {
-		trace!(target: "sync", "Remote changes proof response {} from {} (max={})",
-			response.id,
-			who,
-			response.max
-		);
-		self.light_dispatch.on_remote_changes_response(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, who, response);
-	}
-
 	fn on_finality_proof_request(
 		&mut self,
 		who: PeerId,
@@ -1905,17 +1709,6 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 		}
 	}
 
-	fn on_remote_body_response(
-		&mut self,
-		peer: PeerId,
-		response: message::BlockResponse<B>
-	) {
-		self.light_dispatch.on_remote_body_response(LightDispatchIn {
-			behaviour: &mut self.behaviour,
-			peerset: self.peerset_handle.clone(),
-		}, peer, response);
-	}
-
 	fn format_stats(&self) -> String {
 		let mut out = String::new();
 		for (id, stats) in &self.context_data.stats {
@@ -1987,6 +1780,8 @@ pub enum CustomMessageOutcome<B: BlockT> {
 	NotificationStreamClosed { remote: PeerId, protocols: Vec<ConsensusEngineId> },
 	/// Messages have been received on one or more notifications protocols.
 	NotificationsReceived { remote: PeerId, messages: Vec<(ConsensusEngineId, Bytes)> },
+	/// Peer has a reported a new head of chain.
+	PeerNewBest(PeerId, NumberFor<B>),
 	None,
 }
 
@@ -2067,6 +1862,10 @@ impl<B: BlockT, H: ExHashT> NetworkBehaviour for Protocol<B, H> {
 			Self::OutEvent
 		>
 	> {
+		if let Some(message) = self.pending_messages.pop_front() {
+			return Poll::Ready(NetworkBehaviourAction::GenerateEvent(message));
+		}
+
 		while let Poll::Ready(Some(())) = self.tick_timeout.poll_next_unpin(cx) {
 			self.tick();
 		}
@@ -2221,7 +2020,6 @@ impl<B: BlockT, H: ExHashT> Drop for Protocol<B, H> {
 #[cfg(test)]
 mod tests {
 	use crate::PeerId;
-	use crate::protocol::light_dispatch::AlwaysBadChecker;
 	use crate::config::{EmptyTransactionPool, Roles};
 	use super::{CustomMessageOutcome, Protocol, ProtocolConfig};
 
@@ -2240,7 +2038,6 @@ mod tests {
 				max_parallel_downloads: 10,
 			},
 			client.clone(),
-			Arc::new(AlwaysBadChecker),
 			Arc::new(EmptyTransactionPool),
 			None,
 			None,

substrate/client/network/src/protocol/light_client_handler.rs

@@ -29,7 +29,7 @@ use codec::{self, Encode, Decode};
 use crate::{
 	chain::Client,
 	config::ProtocolId,
-	protocol::{api, light_dispatch::TIMEOUT_REPUTATION_CHANGE}
+	protocol::{api, message::BlockAttributes}
 };
 use futures::{channel::oneshot, future::BoxFuture, prelude::*, stream::FuturesUnordered};
 use libp2p::{
@@ -74,6 +74,9 @@ use std::{
 use void::Void;
 use wasm_timer::Instant;
 
+/// Reputation change for a peer when a request timed out.
+pub(crate) const TIMEOUT_REPUTATION_CHANGE: i32 = -(1 << 8);
+
 /// Configuration options for `LightClientHandler` behaviour.
 #[derive(Debug, Clone)]
 pub struct Config {
@@ -82,7 +85,8 @@ pub struct Config {
 	max_pending_requests: usize,
 	inactivity_timeout: Duration,
 	request_timeout: Duration,
-	protocol: Bytes,
+	light_protocol: Bytes,
+	block_protocol: Bytes,
 }
 
 impl Config {
@@ -100,7 +104,8 @@ impl Config {
 			max_pending_requests: 128,
 			inactivity_timeout: Duration::from_secs(15),
 			request_timeout: Duration::from_secs(15),
-			protocol: Bytes::new(),
+			light_protocol: Bytes::new(),
+			block_protocol: Bytes::new(),
 		};
 		c.set_protocol(id);
 		c
@@ -138,11 +143,18 @@ impl Config {
 
 	/// Set protocol to use for upgrade negotiation.
 	pub fn set_protocol(&mut self, id: &ProtocolId) -> &mut Self {
-		let mut v = Vec::new();
-		v.extend_from_slice(b"/");
-		v.extend_from_slice(id.as_bytes());
-		v.extend_from_slice(b"/light/2");
-		self.protocol = v.into();
+		let mut vl = Vec::new();
+		vl.extend_from_slice(b"/");
+		vl.extend_from_slice(id.as_bytes());
+		vl.extend_from_slice(b"/light/2");
+		self.light_protocol = vl.into();
+
+		let mut vb = Vec::new();
+		vb.extend_from_slice(b"/");
+		vb.extend_from_slice(id.as_bytes());
+		vb.extend_from_slice(b"/sync/2");
+		self.block_protocol = vb.into();
+
 		self
 	}
 }
@@ -176,6 +188,10 @@ pub enum Error {
 // used because we currently only support a subset of those.
 #[derive(Debug)]
 pub enum Request<B: Block> {
+	Body {
+		request: fetcher::RemoteBodyRequest<B::Header>,
+		sender: oneshot::Sender<Result<Vec<B::Extrinsic>, ClientError>>
+	},
 	Header {
 		request: fetcher::RemoteHeaderRequest<B::Header>,
 		sender: oneshot::Sender<Result<B::Header, ClientError>>
@@ -208,7 +224,8 @@ enum Reply<B: Block> {
 	VecU8(Vec<u8>),
 	VecNumberU32(Vec<(<B::Header as Header>::Number, u32)>),
 	MapVecU8OptVecU8(HashMap<Vec<u8>, Option<Vec<u8>>>),
-	Header(B::Header)
+	Header(B::Header),
+	Extrinsics(Vec<B::Extrinsic>),
 }
 
 /// Augments a light client request with metadata.
@@ -291,6 +308,7 @@ where
 	/// means to determine it ourselves.
 	pub fn update_best_block(&mut self, peer: &PeerId, num: NumberFor<B>) {
 		if let Some(info) = self.peers.get_mut(peer) {
+			log::trace!("new best block for {:?}: {:?}", peer, num);
 			info.best_block = Some(num)
 		}
 	}
@@ -360,10 +378,23 @@ where
 		( &mut self
 		, peer: &PeerId
 		, request: &Request<B>
-		, response: api::v1::light::Response
+		, response: Response
 		) -> Result<Reply<B>, Error>
 	{
 		log::trace!("response from {}", peer);
+		match response {
+			Response::Light(r) => self.on_response_light(peer, request, r),
+			Response::Block(r) => self.on_response_block(peer, request, r),
+		}
+	}
+
+	fn on_response_light
+		( &mut self
+		, peer: &PeerId
+		, request: &Request<B>
+		, response: api::v1::light::Response
+		) -> Result<Reply<B>, Error>
+	{
 		use api::v1::light::response::Response;
 		match response.response {
 			Some(Response::RemoteCallResponse(response)) =>
@@ -429,6 +460,32 @@ where
 		}
 	}
 
+	fn on_response_block
+		( &mut self
+		, peer: &PeerId
+		, request: &Request<B>
+		, response: api::v1::BlockResponse
+		) -> Result<Reply<B>, Error>
+	{
+		let request = if let Request::Body { request , .. } = &request {
+			request
+		} else {
+			return Err(Error::UnexpectedResponse);
+		};
+
+		let body: Vec<_> = match response.blocks.into_iter().next() {
+			Some(b) => b.body,
+			None => return Err(Error::UnexpectedResponse),
+		};
+
+		let body = body.into_iter()
+			.map(|mut extrinsic| B::Extrinsic::decode(&mut &extrinsic[..]))
+			.collect::<Result<_, _>>()?;
+
+		let body = self.checker.check_body_proof(&request, body)?;
+		Ok(Reply::Extrinsics(body))
+	}
+
 	fn on_remote_call_request
 		( &mut self
 		, peer: &PeerId
@@ -664,7 +721,7 @@ where
 	fn new_handler(&mut self) -> Self::ProtocolsHandler {
 		let p = InboundProtocol {
 			max_request_size: self.config.max_request_size,
-			protocol: self.config.protocol.clone(),
+			protocol: self.config.light_protocol.clone(),
 		};
 		OneShotHandler::new(SubstreamProtocol::new(p), self.config.inactivity_timeout)
 	}
@@ -839,30 +896,40 @@ where
 				}
 			};
 			if let Some(peer) = available_peer {
-				let rq = serialize_request(&request.request);
-				let mut buf = Vec::with_capacity(rq.encoded_len());
-				if let Err(e) = rq.encode(&mut buf) {
-					log::debug!("failed to serialize request: {}", e);
-					send_reply(Err(ClientError::RemoteFetchFailed), request.request)
-				} else {
-					let id = self.next_request_id();
-					log::trace!("sending request {} to peer {}", id, peer);
-					let protocol = OutboundProtocol {
-						request: buf,
-						request_id: id,
-						max_response_size: self.config.max_response_size,
-						protocol: self.config.protocol.clone(),
-					};
-					self.peers.get_mut(&peer).map(|info| info.status = PeerStatus::BusyWith(id));
-					let rw = RequestWrapper {
-						timestamp: request.timestamp,
-						retries: request.retries,
-						request: request.request,
-						peer: peer.clone(),
-					};
-					self.outstanding.insert(id, rw);
-					return Poll::Ready(NetworkBehaviourAction::SendEvent { peer_id: peer, event: protocol })
-				}
+				let buf = match serialize_request(&request.request) {
+					Ok(b) => b,
+					Err(e) => {
+						log::debug!("failed to serialize request: {}", e);
+						send_reply(Err(ClientError::RemoteFetchFailed), request.request);
+						continue;
+					}
+				};
+
+				let id = self.next_request_id();
+				log::trace!("sending request {} to peer {}", id, peer);
+				let protocol = OutboundProtocol {
+					request: buf,
+					request_id: id,
+					expected: match request.request {
+						Request::Body { .. } => ExpectedResponseTy::Block,
+						_ => ExpectedResponseTy::Light,
+					},
+					max_response_size: self.config.max_response_size,
+					protocol: match request.request {
+						Request::Body { .. } => self.config.block_protocol.clone(),
+						_ => self.config.light_protocol.clone(),
+					},
+				};
+				self.peers.get_mut(&peer).map(|info| info.status = PeerStatus::BusyWith(id));
+				let rw = RequestWrapper {
+					timestamp: request.timestamp,
+					retries: request.retries,
+					request: request.request,
+					peer: peer.clone(),
+				};
+				self.outstanding.insert(id, rw);
+				return Poll::Ready(NetworkBehaviourAction::SendEvent { peer_id: peer, event: protocol })
+
 			} else {
 				self.pending_requests.push_front(request);
 				log::debug!("no peer available to send request to");
@@ -903,6 +970,7 @@ where
 
 fn required_block<B: Block>(request: &Request<B>) -> NumberFor<B> {
 	match request {
+		Request::Body { request, .. } => *request.header.number(),
 		Request::Header { request, .. } => request.block,
 		Request::Read { request, .. } => *request.header.number(),
 		Request::ReadChild { request, .. } => *request.header.number(),
@@ -913,6 +981,7 @@ fn required_block<B: Block>(request: &Request<B>) -> NumberFor<B> {
 
 fn retries<B: Block>(request: &Request<B>) -> usize {
 	let rc = match request {
+		Request::Body { request, .. } => request.retry_count,
 		Request::Header { request, .. } => request.retry_count,
 		Request::Read { request, .. } => request.retry_count,
 		Request::ReadChild { request, .. } => request.retry_count,
@@ -922,8 +991,20 @@ fn retries<B: Block>(request: &Request<B>) -> usize {
 	rc.unwrap_or(0)
 }
 
-fn serialize_request<B: Block>(request: &Request<B>) -> api::v1::light::Request {
+fn serialize_request<B: Block>(request: &Request<B>) -> Result<Vec<u8>, prost::EncodeError> {
 	let request = match request {
+		Request::Body { request, .. } => {
+			let rq = api::v1::BlockRequest {
+				fields: u32::from(BlockAttributes::BODY.bits()),
+				from_block: Some(api::v1::block_request::FromBlock::Hash(request.header.hash().encode())),
+				to_block: Vec::new(),
+				direction: api::v1::Direction::Ascending as i32,
+				max_blocks: 1,
+			};
+			let mut buf = Vec::with_capacity(rq.encoded_len());
+			rq.encode(&mut buf)?;
+			return Ok(buf);
+		}
 		Request::Header { request, .. } => {
 			let r = api::v1::light::RemoteHeaderRequest { block: request.block.encode() };
 			api::v1::light::request::Request::RemoteHeaderRequest(r)
@@ -966,7 +1047,10 @@ fn serialize_request<B: Block>(request: &Request<B>) -> api::v1::light::Request
 		}
 	};
 
-	api::v1::light::Request { request: Some(request) }
+	let rq = api::v1::light::Request { request: Some(request) };
+	let mut buf = Vec::with_capacity(rq.encoded_len());
+	rq.encode(&mut buf)?;
+	Ok(buf)
 }
 
 fn send_reply<B: Block>(result: Result<Reply<B>, ClientError>, request: Request<B>) {
@@ -974,6 +1058,11 @@ fn send_reply<B: Block>(result: Result<Reply<B>, ClientError>, request: Request<
 		let _ = sender.send(item); // It is okay if the other end already hung up.
 	}
 	match request {
+		Request::Body { request, sender } => match result {
+			Err(e) => send(Err(e), sender),
+			Ok(Reply::Extrinsics(x)) => send(Ok(x), sender),
+			reply => log::error!("invalid reply for body request: {:?}, {:?}", reply, request),
+		}
 		Request::Header { request, sender } => match result {
 			Err(e) => send(Err(e), sender),
 			Ok(Reply::Header(x)) => send(Ok(x), sender),
@@ -1008,7 +1097,16 @@ pub enum Event<T> {
 	/// Incoming request from remote and substream to use for the response.
 	Request(api::v1::light::Request, T),
 	/// Incoming response from remote.
-	Response(u64, api::v1::light::Response),
+	Response(u64, Response),
+}
+
+/// Incoming response from remote.
+#[derive(Debug, Clone)]
+pub enum Response {
+	/// Incoming light response from remote.
+	Light(api::v1::light::Response),
+	/// Incoming block response from remote.
+	Block(api::v1::BlockResponse),
 }
 
 /// Substream upgrade protocol.
@@ -1023,23 +1121,23 @@ pub struct InboundProtocol {
 }
 
 impl UpgradeInfo for InboundProtocol {
-    type Info = Bytes;
-    type InfoIter = iter::Once<Self::Info>;
+	type Info = Bytes;
+	type InfoIter = iter::Once<Self::Info>;
 
-    fn protocol_info(&self) -> Self::InfoIter {
-        iter::once(self.protocol.clone())
-    }
+	fn protocol_info(&self) -> Self::InfoIter {
+		iter::once(self.protocol.clone())
+	}
 }
 
 impl<T> InboundUpgrade<T> for InboundProtocol
 where
 	T: AsyncRead + AsyncWrite + Unpin + Send + 'static
 {
-    type Output = Event<T>;
-    type Error = ReadOneError;
-    type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
+	type Output = Event<T>;
+	type Error = ReadOneError;
+	type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
 
-    fn upgrade_inbound(self, mut s: T, _: Self::Info) -> Self::Future {
+	fn upgrade_inbound(self, mut s: T, _: Self::Info) -> Self::Future {
 		let future = async move {
 			let vec = read_one(&mut s, self.max_request_size).await?;
 			match api::v1::light::Request::decode(&vec[..]) {
@@ -1060,38 +1158,59 @@ pub struct OutboundProtocol {
 	request: Vec<u8>,
 	/// Local identifier for the request. Used to associate it with a response.
 	request_id: u64,
+	/// Kind of response expected for this request.
+	expected: ExpectedResponseTy,
 	/// The max. response length in bytes.
 	max_response_size: usize,
 	/// The protocol to use for upgrade negotiation.
 	protocol: Bytes,
 }
 
-impl UpgradeInfo for OutboundProtocol {
-    type Info = Bytes;
-    type InfoIter = iter::Once<Self::Info>;
+/// Type of response expected from the remote for this request.
+#[derive(Debug, Clone)]
+enum ExpectedResponseTy {
+	Light,
+	Block,
+}
 
-    fn protocol_info(&self) -> Self::InfoIter {
-        iter::once(self.protocol.clone())
-    }
+impl UpgradeInfo for OutboundProtocol {
+	type Info = Bytes;
+	type InfoIter = iter::Once<Self::Info>;
+
+	fn protocol_info(&self) -> Self::InfoIter {
+		iter::once(self.protocol.clone())
+	}
 }
 
 impl<T> OutboundUpgrade<T> for OutboundProtocol
 where
 	T: AsyncRead + AsyncWrite + Unpin + Send + 'static
 {
-    type Output = Event<T>;
-    type Error = ReadOneError;
-    type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
+	type Output = Event<T>;
+	type Error = ReadOneError;
+	type Future = BoxFuture<'static, Result<Self::Output, Self::Error>>;
 
-    fn upgrade_outbound(self, mut s: T, _: Self::Info) -> Self::Future {
+	fn upgrade_outbound(self, mut s: T, _: Self::Info) -> Self::Future {
 		let future = async move {
 			write_one(&mut s, &self.request).await?;
 			let vec = read_one(&mut s, self.max_response_size).await?;
-			api::v1::light::Response::decode(&vec[..])
-				.map(|r| Event::Response(self.request_id, r))
-				.map_err(|e| {
-					ReadOneError::Io(io::Error::new(io::ErrorKind::Other, e))
-				})
+
+			match self.expected {
+				ExpectedResponseTy::Light => {
+					api::v1::light::Response::decode(&vec[..])
+						.map(|r| Event::Response(self.request_id, Response::Light(r)))
+						.map_err(|e| {
+							ReadOneError::Io(io::Error::new(io::ErrorKind::Other, e))
+						})
+				},
+				ExpectedResponseTy::Block => {
+					api::v1::BlockResponse::decode(&vec[..])
+						.map(|r| Event::Response(self.request_id, Response::Block(r)))
+						.map_err(|e| {
+							ReadOneError::Io(io::Error::new(io::ErrorKind::Other, e))
+						})
+				}
+			}
 		};
 		future.boxed()
 	}
@@ -1117,7 +1236,7 @@ mod tests {
 	use crate::{
 		chain::Client,
 		config::ProtocolId,
-		protocol::{api, light_dispatch::tests::{DummyFetchChecker, dummy_header}}
+		protocol::api,
 	};
 	use futures::{channel::oneshot, prelude::*};
 	use libp2p::{
@@ -1139,15 +1258,15 @@ mod tests {
 	use sp_blockchain::{Error as ClientError};
 	use sp_core::storage::ChildInfo;
 	use std::{
-		collections::HashSet,
+		collections::{HashMap, HashSet},
 		io,
 		iter::{self, FromIterator},
 		pin::Pin,
 		sync::Arc,
 		task::{Context, Poll}
 	};
-	use sp_runtime::{generic::Header, traits::BlakeTwo256};
-	use super::{Event, LightClientHandler, Request, OutboundProtocol, PeerStatus};
+	use sp_runtime::{generic::Header, traits::{BlakeTwo256, Block as BlockT, NumberFor}};
+	use super::{Event, LightClientHandler, Request, Response, OutboundProtocol, PeerStatus};
 	use void::Void;
 
 	const CHILD_INFO: ChildInfo<'static> = ChildInfo::new_default(b"foobarbaz");
@@ -1162,7 +1281,7 @@ mod tests {
 
 	fn make_swarm(ok: bool, ps: sc_peerset::PeersetHandle, cf: super::Config) -> Swarm {
 		let client = Arc::new(substrate_test_runtime_client::new());
-		let checker = Arc::new(DummyFetchChecker::new(ok));
+		let checker = Arc::new(DummyFetchChecker { ok, _mark: std::marker::PhantomData });
 		let id_key = identity::Keypair::generate_ed25519();
 		let dh_key = Keypair::<X25519>::new().into_authentic(&id_key).unwrap();
 		let local_peer = id_key.public().into_peer_id();
@@ -1176,10 +1295,104 @@ mod tests {
 		Swarm::new(transport, LightClientHandler::new(cf, client, checker, ps), local_peer)
 	}
 
+	struct DummyFetchChecker<B> {
+		ok: bool,
+		_mark: std::marker::PhantomData<B>
+	}
+
+	impl<B: BlockT> fetcher::FetchChecker<B> for DummyFetchChecker<B> {
+		fn check_header_proof(
+			&self,
+			_request: &fetcher::RemoteHeaderRequest<B::Header>,
+			header: Option<B::Header>,
+			_remote_proof: fetcher::StorageProof,
+		) -> Result<B::Header, ClientError> {
+			match self.ok {
+				true if header.is_some() => Ok(header.unwrap()),
+				_ => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+
+		fn check_read_proof(
+			&self,
+			request: &fetcher::RemoteReadRequest<B::Header>,
+			_: fetcher::StorageProof,
+		) -> Result<HashMap<Vec<u8>, Option<Vec<u8>>>, ClientError> {
+			match self.ok {
+				true => Ok(request.keys
+					.iter()
+					.cloned()
+					.map(|k| (k, Some(vec![42])))
+					.collect()
+				),
+				false => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+
+		fn check_read_child_proof(
+			&self,
+			request: &fetcher::RemoteReadChildRequest<B::Header>,
+			_: fetcher::StorageProof,
+		) -> Result<HashMap<Vec<u8>, Option<Vec<u8>>>, ClientError> {
+			match self.ok {
+				true => Ok(request.keys
+					.iter()
+					.cloned()
+					.map(|k| (k, Some(vec![42])))
+					.collect()
+				),
+				false => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+
+		fn check_execution_proof(
+			&self,
+			_: &fetcher::RemoteCallRequest<B::Header>,
+			_: fetcher::StorageProof,
+		) -> Result<Vec<u8>, ClientError> {
+			match self.ok {
+				true => Ok(vec![42]),
+				false => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+
+		fn check_changes_proof(
+			&self,
+			_: &fetcher::RemoteChangesRequest<B::Header>,
+			_: fetcher::ChangesProof<B::Header>
+		) -> Result<Vec<(NumberFor<B>, u32)>, ClientError> {
+			match self.ok {
+				true => Ok(vec![(100.into(), 2)]),
+				false => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+
+		fn check_body_proof(
+			&self,
+			_: &fetcher::RemoteBodyRequest<B::Header>,
+			body: Vec<B::Extrinsic>
+		) -> Result<Vec<B::Extrinsic>, ClientError> {
+			match self.ok {
+				true => Ok(body),
+				false => Err(ClientError::Backend("Test error".into())),
+			}
+		}
+	}
+
 	fn make_config() -> super::Config {
 		super::Config::new(&ProtocolId::from(&b"foo"[..]))
 	}
 
+	fn dummy_header() -> sp_test_primitives::Header {
+		sp_test_primitives::Header {
+			parent_hash: Default::default(),
+			number: 0,
+			state_root: Default::default(),
+			extrinsics_root: Default::default(),
+			digest: Default::default(),
+		}
+	}
+
 	struct EmptyPollParams(PeerId);
 
 	impl PollParameters for EmptyPollParams {
@@ -1222,7 +1435,7 @@ mod tests {
 		) -> LightClientHandler<Block>
 	{
 		let client = Arc::new(substrate_test_runtime_client::new());
-		let checker = Arc::new(DummyFetchChecker::new(ok));
+		let checker = Arc::new(DummyFetchChecker { ok, _mark: std::marker::PhantomData });
 		LightClientHandler::new(cf, client, checker, ps)
 	}
 
@@ -1349,7 +1562,7 @@ mod tests {
 			}
 		};
 
-		behaviour.inject_node_event(peer.clone(), Event::Response(request_id, response));
+		behaviour.inject_node_event(peer.clone(), Event::Response(request_id, Response::Light(response)));
 		assert!(behaviour.peers.is_empty());
 
 		poll(&mut behaviour); // More progress
@@ -1378,7 +1591,7 @@ mod tests {
 			}
 		};
 
-		behaviour.inject_node_event(peer.clone(), Event::Response(2347895932, response));
+		behaviour.inject_node_event(peer.clone(), Event::Response(2347895932, Response::Light(response)));
 
 		assert!(behaviour.peers.is_empty());
 		poll(&mut behaviour);
@@ -1420,7 +1633,7 @@ mod tests {
 			}
 		};
 
-		behaviour.inject_node_event(peer.clone(), Event::Response(request_id, response));
+		behaviour.inject_node_event(peer.clone(), Event::Response(request_id, Response::Light(response)));
 		assert!(behaviour.peers.is_empty());
 
 		poll(&mut behaviour); // More progress
@@ -1472,7 +1685,7 @@ mod tests {
 					response: Some(api::v1::light::response::Response::RemoteCallResponse(r))
 				}
 			};
-			behaviour.inject_node_event(responding_peer, Event::Response(request_id, response.clone()));
+			behaviour.inject_node_event(responding_peer, Event::Response(request_id, Response::Light(response.clone())));
 			assert_matches!(poll(&mut behaviour), Poll::Ready(NetworkBehaviourAction::SendEvent { .. }));
 			assert_matches!(chan.1.try_recv(), Ok(None))
 		}
@@ -1485,7 +1698,7 @@ mod tests {
 				response: Some(api::v1::light::response::Response::RemoteCallResponse(r)),
 			}
 		};
-		behaviour.inject_node_event(responding_peer, Event::Response(request_id, response));
+		behaviour.inject_node_event(responding_peer, Event::Response(request_id, Response::Light(response)));
 		assert_matches!(poll(&mut behaviour), Poll::Pending);
 		assert_matches!(chan.1.try_recv(), Ok(Some(Err(ClientError::RemoteFetchFailed))))
 	}
@@ -1499,6 +1712,7 @@ mod tests {
 		assert_eq!(1, behaviour.peers.len());
 
 		let response = match request {
+			Request::Body { .. } => unimplemented!(),
 			Request::Header{..} => {
 				let r = api::v1::light::RemoteHeaderResponse {
 					header: dummy_header().encode(),
@@ -1548,7 +1762,7 @@ mod tests {
 		assert_eq!(1, behaviour.outstanding.len());
 		assert_eq!(1, *behaviour.outstanding.keys().next().unwrap());
 
-		behaviour.inject_node_event(peer.clone(), Event::Response(1, response));
+		behaviour.inject_node_event(peer.clone(), Event::Response(1, Response::Light(response)));
 
 		poll(&mut behaviour);
 

substrate/client/network/src/service.rs

@@ -25,31 +25,42 @@
 //! The methods of the [`NetworkService`] are implemented by sending a message over a channel,
 //! which is then processed by [`NetworkWorker::poll`].
 
-use std::{borrow::Cow, collections::{HashMap, HashSet}, fs, marker::PhantomData, io, path::Path, str};
-use std::sync::{Arc, atomic::{AtomicBool, AtomicUsize, Ordering}};
-use std::pin::Pin;
-use std::task::Poll;
-
-use sp_consensus::import_queue::{ImportQueue, Link};
-use sp_consensus::import_queue::{BlockImportResult, BlockImportError};
+use crate::{
+	behaviour::{Behaviour, BehaviourOut},
+	config::{parse_addr, parse_str_addr, NonReservedPeerMode, Params, TransportConfig},
+	error::Error,
+	network_state::{
+		NetworkState, NotConnectedPeer as NetworkStateNotConnectedPeer, Peer as NetworkStatePeer,
+	},
+	on_demand_layer::AlwaysBadChecker,
+	protocol::{self, event::Event, light_client_handler, sync::SyncState, PeerInfo, Protocol},
+	transport, ReputationChange,
+};
 use futures::{prelude::*, channel::mpsc};
-use log::{warn, error, info, trace};
-use libp2p::{PeerId, Multiaddr, kad::record};
 use libp2p::swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent};
+use libp2p::{kad::record, Multiaddr, PeerId};
+use log::{error, info, trace, warn};
 use parking_lot::Mutex;
+use prometheus_endpoint::{
+	register, Counter, CounterVec, Gauge, GaugeVec, Opts, PrometheusError, Registry, U64,
+};
 use sc_peerset::PeersetHandle;
-use sp_runtime::{traits::{Block as BlockT, NumberFor}, ConsensusEngineId};
-use prometheus_endpoint::{Registry, Counter, CounterVec, Gauge, GaugeVec, Opts, U64, register, PrometheusError};
-
-use crate::{behaviour::{Behaviour, BehaviourOut}, config::{parse_str_addr, parse_addr}};
-use crate::{transport, config::NonReservedPeerMode, ReputationChange};
-use crate::config::{Params, TransportConfig};
-use crate::error::Error;
-use crate::network_state::{NetworkState, NotConnectedPeer as NetworkStateNotConnectedPeer, Peer as NetworkStatePeer};
-use crate::protocol::{self, Protocol, PeerInfo};
-use crate::protocol::{event::Event, light_dispatch::{AlwaysBadChecker, RequestData}};
-use crate::protocol::sync::SyncState;
-
+use sp_consensus::import_queue::{BlockImportError, BlockImportResult, ImportQueue, Link};
+use sp_runtime::{
+	traits::{Block as BlockT, NumberFor},
+	ConsensusEngineId,
+};
+use std::{
+	borrow::Cow,
+	collections::{HashMap, HashSet},
+	fs, io,
+	marker::PhantomData,
+	path::Path,
+	pin::Pin,
+	str,
+	sync::{atomic::{AtomicBool, AtomicUsize, Ordering}, Arc},
+	task::Poll,
+};
 
 /// Minimum Requirements for a Hash within Networking
 pub trait ExHashT: std::hash::Hash + Eq + std::fmt::Debug + Clone + Send + Sync + 'static {}
@@ -240,7 +251,6 @@ impl<B: BlockT + 'static, H: ExHashT> NetworkWorker<B, H> {
 				max_parallel_downloads: params.network_config.max_parallel_downloads,
 			},
 			params.chain.clone(),
-			checker.clone(),
 			params.transaction_pool,
 			params.finality_proof_provider.clone(),
 			params.finality_proof_request_builder,
@@ -773,7 +783,7 @@ pub struct NetworkWorker<B: BlockT + 'static, H: ExHashT> {
 	/// Messages from the `NetworkService` and that must be processed.
 	from_worker: mpsc::UnboundedReceiver<ServiceToWorkerMsg<B, H>>,
 	/// Receiver for queries from the light client that must be processed.
-	light_client_rqs: Option<mpsc::UnboundedReceiver<RequestData<B>>>,
+	light_client_rqs: Option<mpsc::UnboundedReceiver<light_client_handler::Request<B>>>,
 	/// Senders for events that happen on the network.
 	event_streams: Vec<mpsc::UnboundedSender<Event>>,
 	/// Prometheus network metrics.
@@ -789,6 +799,7 @@ struct Metrics {
 	import_queue_finality_proofs_submitted: Counter<U64>,
 	import_queue_justifications_submitted: Counter<U64>,
 	is_major_syncing: Gauge<U64>,
+	issued_light_requests: Counter<U64>,
 	kbuckets_num_nodes: Gauge<U64>,
 	network_per_sec_bytes: GaugeVec<U64>,
 	notifications_total: CounterVec<U64>,
@@ -822,6 +833,10 @@ impl Metrics {
 			is_major_syncing: register(Gauge::new(
 				"sub_libp2p_is_major_syncing", "Whether the node is performing a major sync or not.",
 			)?, registry)?,
+			issued_light_requests: register(Counter::new(
+				"issued_light_requests",
+				"Number of light client requests that our node has issued.",
+			)?, registry)?,
 			kbuckets_num_nodes: register(Gauge::new(
 				"sub_libp2p_kbuckets_num_nodes", "Number of nodes in the Kademlia k-buckets"
 			)?, registry)?,
@@ -897,7 +912,13 @@ impl<B: BlockT + 'static, H: ExHashT> Future for NetworkWorker<B, H> {
 		// Check for new incoming light client requests.
 		if let Some(light_client_rqs) = this.light_client_rqs.as_mut() {
 			while let Poll::Ready(Some(rq)) = light_client_rqs.poll_next_unpin(cx) {
-				this.network_service.user_protocol_mut().add_light_client_request(rq);
+				// This can error if there are too many queued requests already.
+				if this.network_service.light_client_request(rq).is_err() {
+					log::warn!("Couldn't start light client request: too many pending requests");
+				}
+				if let Some(metrics) = this.metrics.as_ref() {
+					metrics.issued_light_requests.inc();
+				}
 			}
 		}