Modular block request handler (#1524)

Submit the outstanding PRs from the old repos(these were already reviewed and approved before the repo rorg, but not yet submitted): Main PR: https://github.com/paritytech/substrate/pull/14014 Companion PRs: https://github.com/paritytech/polkadot/pull/7134, https://github.com/paritytech/cumulus/pull/2489 The changes in the PR: 1. ChainSync currently calls into the block request handler directly. Instead, move the block request handler behind a trait. This allows new protocols to be plugged into ChainSync. 2. BuildNetworkParams is changed so that custom relay protocol implementations can be (optionally) passed in during network creation time. If custom protocol is not specified, it defaults to the existing block handler 3. BlockServer and BlockDownloader traits are introduced for the protocol implementation. The existing block handler has been changed to implement these traits 4. Other changes: [X] Make TxHash serializable. This is needed for exchanging the serialized hash in the relay protocol messages [X] Clean up types no longer used(OpaqueBlockRequest, OpaqueBlockResponse) --------- Co-authored-by: Dmitry Markin <dmitry@markin.tech> Co-authored-by: command-bot <>
2026-04-26 20:27:58 +00:00 · 2023-09-15 01:12:45 -07:00
parent c6df364157
commit b35b28ca4b
14 changed files with 370 additions and 256 deletions
@@ -18,29 +18,35 @@
 //! `crate::request_responses::RequestResponsesBehaviour`.

 use crate::{
-	schema::v1::{block_request::FromBlock, BlockResponse, Direction},
+	block_relay_protocol::{BlockDownloader, BlockRelayParams, BlockResponseError, BlockServer},
+	schema::v1::{
+		block_request::FromBlock as FromBlockSchema, BlockRequest as BlockRequestSchema,
+		BlockResponse as BlockResponseSchema, BlockResponse, Direction,
+	},
+	service::network::NetworkServiceHandle,
 	MAX_BLOCKS_IN_RESPONSE,
 };

-use codec::{Decode, Encode};
+use codec::{Decode, DecodeAll, Encode};
 use futures::{channel::oneshot, stream::StreamExt};
 use libp2p::PeerId;
 use log::debug;
 use prost::Message;
-use schnellru::{ByLength, LruMap};
-
 use sc_client_api::BlockBackend;
 use sc_network::{
 	config::ProtocolId,
-	request_responses::{IncomingRequest, OutgoingResponse, ProtocolConfig},
+	request_responses::{
+		IfDisconnected, IncomingRequest, OutgoingResponse, ProtocolConfig, RequestFailure,
+	},
+	types::ProtocolName,
 };
-use sc_network_common::sync::message::BlockAttributes;
+use sc_network_common::sync::message::{BlockAttributes, BlockData, BlockRequest, FromBlock};
+use schnellru::{ByLength, LruMap};
 use sp_blockchain::HeaderBackend;
 use sp_runtime::{
 	generic::BlockId,
 	traits::{Block as BlockT, Header, One, Zero},
 };
-
 use std::{
 	cmp::min,
 	hash::{Hash, Hasher},
@@ -129,7 +135,8 @@ enum SeenRequestsValue {
 	Fulfilled(usize),
 }

-/// Handler for incoming block requests from a remote peer.
+/// The full block server implementation of [`BlockServer`]. It handles
+/// the incoming block requests from a remote peer.
 pub struct BlockRequestHandler<B: BlockT, Client> {
 	client: Arc<Client>,
 	request_receiver: async_channel::Receiver<IncomingRequest>,
@@ -146,11 +153,12 @@ where
 {
 	/// Create a new [`BlockRequestHandler`].
 	pub fn new(
+		network: NetworkServiceHandle,
 		protocol_id: &ProtocolId,
 		fork_id: Option<&str>,
 		client: Arc<Client>,
 		num_peer_hint: usize,
-	) -> (Self, ProtocolConfig) {
+	) -> BlockRelayParams<B> {
 		// Reserve enough request slots for one request per peer when we are at the maximum
 		// number of peers.
 		let capacity = std::cmp::max(num_peer_hint, 1);
@@ -170,11 +178,15 @@ where
 		let capacity = ByLength::new(num_peer_hint.max(1) as u32 * 2);
 		let seen_requests = LruMap::new(capacity);

-		(Self { client, request_receiver, seen_requests }, protocol_config)
+		BlockRelayParams {
+			server: Box::new(Self { client, request_receiver, seen_requests }),
+			downloader: Arc::new(FullBlockDownloader::new(protocol_config.name.clone(), network)),
+			request_response_config: protocol_config,
+		}
 	}

 	/// Run [`BlockRequestHandler`].
-	pub async fn run(mut self) {
+	async fn process_requests(&mut self) {
 		while let Some(request) = self.request_receiver.next().await {
 			let IncomingRequest { peer, payload, pending_response } = request;

@@ -197,11 +209,11 @@ where
 		let request = crate::schema::v1::BlockRequest::decode(&payload[..])?;

 		let from_block_id = match request.from_block.ok_or(HandleRequestError::MissingFromField)? {
-			FromBlock::Hash(ref h) => {
+			FromBlockSchema::Hash(ref h) => {
 				let h = Decode::decode(&mut h.as_ref())?;
 				BlockId::<B>::Hash(h)
 			},
-			FromBlock::Number(ref n) => {
+			FromBlockSchema::Number(ref n) => {
 				let n = Decode::decode(&mut n.as_ref())?;
 				BlockId::<B>::Number(n)
 			},
@@ -448,6 +460,17 @@ where
 	}
 }

+#[async_trait::async_trait]
+impl<B, Client> BlockServer<B> for BlockRequestHandler<B, Client>
+where
+	B: BlockT,
+	Client: HeaderBackend<B> + BlockBackend<B> + Send + Sync + 'static,
+{
+	async fn run(&mut self) {
+		self.process_requests().await;
+	}
+}
+
 #[derive(Debug, thiserror::Error)]
 enum HandleRequestError {
 	#[error("Failed to decode request: {0}.")]
@@ -465,3 +488,122 @@ enum HandleRequestError {
 	#[error("Failed to send response.")]
 	SendResponse,
 }
+
+/// The full block downloader implementation of [`BlockDownloader].
+pub struct FullBlockDownloader {
+	protocol_name: ProtocolName,
+	network: NetworkServiceHandle,
+}
+
+impl FullBlockDownloader {
+	fn new(protocol_name: ProtocolName, network: NetworkServiceHandle) -> Self {
+		Self { protocol_name, network }
+	}
+
+	/// Extracts the blocks from the response schema.
+	fn blocks_from_schema<B: BlockT>(
+		&self,
+		request: &BlockRequest<B>,
+		response: BlockResponseSchema,
+	) -> Result<Vec<BlockData<B>>, String> {
+		response
+			.blocks
+			.into_iter()
+			.map(|block_data| {
+				Ok(BlockData::<B> {
+					hash: Decode::decode(&mut block_data.hash.as_ref())?,
+					header: if !block_data.header.is_empty() {
+						Some(Decode::decode(&mut block_data.header.as_ref())?)
+					} else {
+						None
+					},
+					body: if request.fields.contains(BlockAttributes::BODY) {
+						Some(
+							block_data
+								.body
+								.iter()
+								.map(|body| Decode::decode(&mut body.as_ref()))
+								.collect::<Result<Vec<_>, _>>()?,
+						)
+					} else {
+						None
+					},
+					indexed_body: if request.fields.contains(BlockAttributes::INDEXED_BODY) {
+						Some(block_data.indexed_body)
+					} else {
+						None
+					},
+					receipt: if !block_data.receipt.is_empty() {
+						Some(block_data.receipt)
+					} else {
+						None
+					},
+					message_queue: if !block_data.message_queue.is_empty() {
+						Some(block_data.message_queue)
+					} else {
+						None
+					},
+					justification: if !block_data.justification.is_empty() {
+						Some(block_data.justification)
+					} else if block_data.is_empty_justification {
+						Some(Vec::new())
+					} else {
+						None
+					},
+					justifications: if !block_data.justifications.is_empty() {
+						Some(DecodeAll::decode_all(&mut block_data.justifications.as_ref())?)
+					} else {
+						None
+					},
+				})
+			})
+			.collect::<Result<_, _>>()
+			.map_err(|error: codec::Error| error.to_string())
+	}
+}
+
+#[async_trait::async_trait]
+impl<B: BlockT> BlockDownloader<B> for FullBlockDownloader {
+	async fn download_blocks(
+		&self,
+		who: PeerId,
+		request: BlockRequest<B>,
+	) -> Result<Result<Vec<u8>, RequestFailure>, oneshot::Canceled> {
+		// Build the request protobuf.
+		let bytes = BlockRequestSchema {
+			fields: request.fields.to_be_u32(),
+			from_block: match request.from {
+				FromBlock::Hash(h) => Some(FromBlockSchema::Hash(h.encode())),
+				FromBlock::Number(n) => Some(FromBlockSchema::Number(n.encode())),
+			},
+			direction: request.direction as i32,
+			max_blocks: request.max.unwrap_or(0),
+			support_multiple_justifications: true,
+		}
+		.encode_to_vec();
+
+		let (tx, rx) = oneshot::channel();
+		self.network.start_request(
+			who,
+			self.protocol_name.clone(),
+			bytes,
+			tx,
+			IfDisconnected::ImmediateError,
+		);
+		rx.await
+	}
+
+	fn block_response_into_blocks(
+		&self,
+		request: &BlockRequest<B>,
+		response: Vec<u8>,
+	) -> Result<Vec<BlockData<B>>, BlockResponseError> {
+		// Decode the response protobuf
+		let response_schema = BlockResponseSchema::decode(response.as_slice())
+			.map_err(|error| BlockResponseError::DecodeFailed(error.to_string()))?;
+
+		// Extract the block data from the protobuf
+		self.blocks_from_schema::<B>(request, response_schema)
+			.map_err(|error| BlockResponseError::ExtractionFailed(error.to_string()))
+	}
+}