Complex RialtoParachain <> Millau relay (#1405)

* complex parachain relay

* fix spelling

bridges/relays/lib-substrate-relay/src/parachains/mod.rs

@@ -0,0 +1,110 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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 Bridges Common 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 Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Types and functions intended to ease adding of new Substrate -> Substrate
+//! parachain finality proofs synchronization pipelines.
+
+use async_trait::async_trait;
+use bp_polkadot_core::parachains::{ParaHeadsProof, ParaId};
+use pallet_bridge_parachains::{
+	Call as BridgeParachainsCall, Config as BridgeParachainsConfig, RelayBlockHash,
+	RelayBlockHasher, RelayBlockNumber,
+};
+use parachains_relay::ParachainsPipeline;
+use relay_substrate_client::{CallOf, Chain, HashOf, RelayChain, TransactionSignScheme};
+use std::{fmt::Debug, marker::PhantomData};
+
+pub mod source;
+pub mod target;
+
+/// Substrate -> Substrate parachain finality proofs synchronization pipeline.
+///
+/// This is currently restricted to the single parachain, because it is how it
+/// will be used (at least) initially.
+#[async_trait]
+pub trait SubstrateParachainsPipeline: 'static + Clone + Debug + Send + Sync {
+	/// Headers of this parachain are submitted to the `Self::TargetChain`.
+	type SourceParachain: Chain;
+	/// Relay chain that is storing headers of `Self::SourceParachain`.
+	type SourceRelayChain: RelayChain;
+	/// Target chain where `Self::SourceParachain` headers are submitted.
+	type TargetChain: Chain;
+
+	/// How submit parachains heads call is built?
+	type SubmitParachainHeadsCallBuilder: SubmitParachainHeadsCallBuilder<Self>;
+	/// Scheme used to sign target chain transactions.
+	type TransactionSignScheme: TransactionSignScheme;
+
+	/// Id of the `Self::SourceParachain`, used for registration in `Self::SourceRelayChain`.
+	const SOURCE_PARACHAIN_PARA_ID: u32;
+}
+
+/// Adapter that allows all `SubstrateParachainsPipeline` to act as `ParachainsPipeline`.
+#[derive(Clone, Debug)]
+pub struct ParachainsPipelineAdapter<P: SubstrateParachainsPipeline> {
+	_phantom: PhantomData<P>,
+}
+
+impl<P: SubstrateParachainsPipeline> ParachainsPipeline for ParachainsPipelineAdapter<P> {
+	type SourceChain = P::SourceRelayChain;
+	type TargetChain = P::TargetChain;
+}
+
+/// Different ways of building `submit_parachain_heads` calls.
+pub trait SubmitParachainHeadsCallBuilder<P: SubstrateParachainsPipeline>:
+	'static + Send + Sync
+{
+	/// Given parachains and their heads proof, build call of `submit_parachain_heads`
+	/// function of bridge parachains module at the target chain.
+	fn build_submit_parachain_heads_call(
+		relay_block_hash: HashOf<P::SourceRelayChain>,
+		parachains: Vec<ParaId>,
+		parachain_heads_proof: ParaHeadsProof,
+	) -> CallOf<P::TargetChain>;
+}
+
+/// Building `submit_parachain_heads` call when you have direct access to the target
+/// chain runtime.
+pub struct DirectSubmitParachainHeadsCallBuilder<P, R, I> {
+	_phantom: PhantomData<(P, R, I)>,
+}
+
+impl<P, R, I> SubmitParachainHeadsCallBuilder<P> for DirectSubmitParachainHeadsCallBuilder<P, R, I>
+where
+	P: SubstrateParachainsPipeline,
+	P::SourceRelayChain: Chain<Hash = RelayBlockHash>,
+	R: BridgeParachainsConfig<I> + Send + Sync,
+	I: 'static + Send + Sync,
+	R::BridgedChain: bp_runtime::Chain<
+		BlockNumber = RelayBlockNumber,
+		Hash = RelayBlockHash,
+		Hasher = RelayBlockHasher,
+	>,
+	CallOf<P::TargetChain>: From<BridgeParachainsCall<R, I>>,
+{
+	fn build_submit_parachain_heads_call(
+		relay_block_hash: HashOf<P::SourceRelayChain>,
+		parachains: Vec<ParaId>,
+		parachain_heads_proof: ParaHeadsProof,
+	) -> CallOf<P::TargetChain> {
+		BridgeParachainsCall::<R, I>::submit_parachain_heads {
+			relay_block_hash,
+			parachains,
+			parachain_heads_proof,
+		}
+		.into()
+	}
+}

bridges/relays/lib-substrate-relay/src/parachains/source.rs

@@ -0,0 +1,163 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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 Bridges Common 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 Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Parachain heads source.
+
+use crate::{
+	finality::source::RequiredHeaderNumberRef,
+	parachains::{ParachainsPipelineAdapter, SubstrateParachainsPipeline},
+};
+
+use async_std::sync::{Arc, Mutex};
+use async_trait::async_trait;
+use bp_parachains::parachain_head_storage_key_at_source;
+use bp_polkadot_core::parachains::{ParaHash, ParaHead, ParaHeadsProof, ParaId};
+use codec::Decode;
+use parachains_relay::parachains_loop::SourceClient;
+use relay_substrate_client::{
+	Chain, Client, Error as SubstrateError, HeaderIdOf, HeaderOf, RelayChain,
+};
+use relay_utils::relay_loop::Client as RelayClient;
+use sp_runtime::traits::Header as HeaderT;
+
+/// Substrate client as parachain heads source.
+#[derive(Clone)]
+pub struct ParachainsSource<P: SubstrateParachainsPipeline> {
+	client: Client<P::SourceRelayChain>,
+	maximal_header_number: Option<RequiredHeaderNumberRef<P::SourceParachain>>,
+	previous_parachain_head: Arc<Mutex<Option<ParaHash>>>,
+}
+
+impl<P: SubstrateParachainsPipeline> ParachainsSource<P> {
+	/// Creates new parachains source client.
+	pub fn new(
+		client: Client<P::SourceRelayChain>,
+		maximal_header_number: Option<RequiredHeaderNumberRef<P::SourceParachain>>,
+	) -> Self {
+		let previous_parachain_head = Arc::new(Mutex::new(None));
+		ParachainsSource { client, maximal_header_number, previous_parachain_head }
+	}
+
+	/// Returns reference to the underlying RPC client.
+	pub fn client(&self) -> &Client<P::SourceRelayChain> {
+		&self.client
+	}
+
+	/// Return decoded head of given parachain.
+	pub async fn on_chain_parachain_header(
+		&self,
+		at_block: HeaderIdOf<P::SourceRelayChain>,
+		para_id: ParaId,
+	) -> Result<Option<HeaderOf<P::SourceParachain>>, SubstrateError> {
+		let storage_key =
+			parachain_head_storage_key_at_source(P::SourceRelayChain::PARAS_PALLET_NAME, para_id);
+		let para_head = self.client.raw_storage_value(storage_key, Some(at_block.1)).await?;
+		let para_head = para_head.map(|h| ParaHead::decode(&mut &h.0[..])).transpose()?;
+		let para_head = match para_head {
+			Some(para_head) => para_head,
+			None => return Ok(None),
+		};
+
+		Ok(Some(Decode::decode(&mut &para_head.0[..])?))
+	}
+}
+
+#[async_trait]
+impl<P: SubstrateParachainsPipeline> RelayClient for ParachainsSource<P> {
+	type Error = SubstrateError;
+
+	async fn reconnect(&mut self) -> Result<(), SubstrateError> {
+		self.client.reconnect().await
+	}
+}
+
+#[async_trait]
+impl<P: SubstrateParachainsPipeline> SourceClient<ParachainsPipelineAdapter<P>>
+	for ParachainsSource<P>
+where
+	P::SourceParachain: Chain<Hash = ParaHash>,
+{
+	async fn ensure_synced(&self) -> Result<bool, Self::Error> {
+		match self.client.ensure_synced().await {
+			Ok(_) => Ok(true),
+			Err(SubstrateError::ClientNotSynced(_)) => Ok(false),
+			Err(e) => Err(e),
+		}
+	}
+
+	async fn parachain_head(
+		&self,
+		at_block: HeaderIdOf<P::SourceRelayChain>,
+		para_id: ParaId,
+	) -> Result<Option<ParaHash>, Self::Error> {
+		// we don't need to support many parachains now
+		if para_id.0 != P::SOURCE_PARACHAIN_PARA_ID {
+			return Err(SubstrateError::Custom(format!(
+				"Parachain id {} is not matching expected {}",
+				para_id.0,
+				P::SOURCE_PARACHAIN_PARA_ID,
+			)))
+		}
+
+		let parachain_head = match self.on_chain_parachain_header(at_block, para_id).await? {
+			Some(parachain_header) => {
+				let mut parachain_head = Some(parachain_header.hash());
+				// never return head that is larger than requested. This way we'll never sync
+				// headers past `maximal_header_number`
+				if let Some(ref maximal_header_number) = self.maximal_header_number {
+					let maximal_header_number = *maximal_header_number.lock().await;
+					if *parachain_header.number() > maximal_header_number {
+						let previous_parachain_head = *self.previous_parachain_head.lock().await;
+						if let Some(previous_parachain_head) = previous_parachain_head {
+							parachain_head = Some(previous_parachain_head);
+						}
+					}
+				}
+
+				parachain_head
+			},
+			None => None,
+		};
+
+		*self.previous_parachain_head.lock().await = parachain_head;
+
+		Ok(parachain_head)
+	}
+
+	async fn prove_parachain_heads(
+		&self,
+		at_block: HeaderIdOf<P::SourceRelayChain>,
+		parachains: &[ParaId],
+	) -> Result<ParaHeadsProof, Self::Error> {
+		let storage_keys = parachains
+			.iter()
+			.map(|para_id| {
+				parachain_head_storage_key_at_source(
+					P::SourceRelayChain::PARAS_PALLET_NAME,
+					*para_id,
+				)
+			})
+			.collect();
+		let parachain_heads_proof = self
+			.client
+			.prove_storage(storage_keys, at_block.1)
+			.await?
+			.iter_nodes()
+			.collect();
+
+		Ok(parachain_heads_proof)
+	}
+}

bridges/relays/lib-substrate-relay/src/parachains/target.rs

@@ -0,0 +1,161 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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 Bridges Common 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 Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Parachain heads target.
+
+use crate::{
+	parachains::{
+		ParachainsPipelineAdapter, SubmitParachainHeadsCallBuilder, SubstrateParachainsPipeline,
+	},
+	TransactionParams,
+};
+
+use async_trait::async_trait;
+use bp_parachains::{parachain_head_storage_key_at_target, BestParaHeadHash};
+use bp_polkadot_core::parachains::{ParaHeadsProof, ParaId};
+use codec::{Decode, Encode};
+use parachains_relay::parachains_loop::TargetClient;
+use relay_substrate_client::{
+	AccountIdOf, AccountKeyPairOf, BlockNumberOf, Chain, Client, Error as SubstrateError, HashOf,
+	HeaderIdOf, RelayChain, SignParam, TransactionEra, TransactionSignScheme, UnsignedTransaction,
+};
+use relay_utils::{relay_loop::Client as RelayClient, HeaderId};
+use sp_core::{Bytes, Pair};
+use sp_runtime::traits::Header as HeaderT;
+
+/// Substrate client as parachain heads source.
+pub struct ParachainsTarget<P: SubstrateParachainsPipeline> {
+	client: Client<P::TargetChain>,
+	transaction_params: TransactionParams<AccountKeyPairOf<P::TransactionSignScheme>>,
+}
+
+impl<P: SubstrateParachainsPipeline> ParachainsTarget<P> {
+	/// Creates new parachains target client.
+	pub fn new(
+		client: Client<P::TargetChain>,
+		transaction_params: TransactionParams<AccountKeyPairOf<P::TransactionSignScheme>>,
+	) -> Self {
+		ParachainsTarget { client, transaction_params }
+	}
+
+	/// Returns reference to the underlying RPC client.
+	pub fn client(&self) -> &Client<P::TargetChain> {
+		&self.client
+	}
+}
+
+impl<P: SubstrateParachainsPipeline> Clone for ParachainsTarget<P> {
+	fn clone(&self) -> Self {
+		ParachainsTarget {
+			client: self.client.clone(),
+			transaction_params: self.transaction_params.clone(),
+		}
+	}
+}
+
+#[async_trait]
+impl<P: SubstrateParachainsPipeline> RelayClient for ParachainsTarget<P> {
+	type Error = SubstrateError;
+
+	async fn reconnect(&mut self) -> Result<(), SubstrateError> {
+		self.client.reconnect().await
+	}
+}
+
+#[async_trait]
+impl<P> TargetClient<ParachainsPipelineAdapter<P>> for ParachainsTarget<P>
+where
+	P: SubstrateParachainsPipeline,
+	P::TransactionSignScheme: TransactionSignScheme<Chain = P::TargetChain>,
+	AccountIdOf<P::TargetChain>: From<<AccountKeyPairOf<P::TransactionSignScheme> as Pair>::Public>,
+{
+	async fn best_block(&self) -> Result<HeaderIdOf<P::TargetChain>, Self::Error> {
+		let best_header = self.client.best_header().await?;
+		let best_hash = best_header.hash();
+		let best_id = HeaderId(*best_header.number(), best_hash);
+
+		Ok(best_id)
+	}
+
+	async fn best_finalized_source_block(
+		&self,
+		at_block: &HeaderIdOf<P::TargetChain>,
+	) -> Result<HeaderIdOf<P::SourceRelayChain>, Self::Error> {
+		let encoded_best_finalized_source_block = self
+			.client
+			.state_call(
+				P::SourceRelayChain::BEST_FINALIZED_HEADER_ID_METHOD.into(),
+				Bytes(Vec::new()),
+				Some(at_block.1),
+			)
+			.await?;
+		let decoded_best_finalized_source_block: (
+			BlockNumberOf<P::SourceRelayChain>,
+			HashOf<P::SourceRelayChain>,
+		) = Decode::decode(&mut &encoded_best_finalized_source_block.0[..])
+			.map_err(SubstrateError::ResponseParseFailed)?;
+		Ok(HeaderId(decoded_best_finalized_source_block.0, decoded_best_finalized_source_block.1))
+	}
+
+	async fn parachain_head(
+		&self,
+		at_block: HeaderIdOf<P::TargetChain>,
+		para_id: ParaId,
+	) -> Result<Option<BestParaHeadHash>, Self::Error> {
+		let storage_key = parachain_head_storage_key_at_target(
+			P::SourceRelayChain::PARACHAINS_FINALITY_PALLET_NAME,
+			para_id,
+		);
+		let para_head = self.client.storage_value(storage_key, Some(at_block.1)).await?;
+
+		Ok(para_head)
+	}
+
+	async fn submit_parachain_heads_proof(
+		&self,
+		at_relay_block: HeaderIdOf<P::SourceRelayChain>,
+		updated_parachains: Vec<ParaId>,
+		proof: ParaHeadsProof,
+	) -> Result<(), Self::Error> {
+		let genesis_hash = *self.client.genesis_hash();
+		let transaction_params = self.transaction_params.clone();
+		let (spec_version, transaction_version) = self.client.simple_runtime_version().await?;
+		let call = P::SubmitParachainHeadsCallBuilder::build_submit_parachain_heads_call(
+			at_relay_block.1,
+			updated_parachains,
+			proof,
+		);
+		self.client
+			.submit_signed_extrinsic(
+				self.transaction_params.signer.public().into(),
+				move |best_block_id, transaction_nonce| {
+					Ok(Bytes(
+						P::TransactionSignScheme::sign_transaction(SignParam {
+							spec_version,
+							transaction_version,
+							genesis_hash,
+							signer: transaction_params.signer,
+							era: TransactionEra::new(best_block_id, transaction_params.mortality),
+							unsigned: UnsignedTransaction::new(call.into(), transaction_nonce),
+						})?
+						.encode(),
+					))
+				},
+			)
+			.await
+			.map(drop)
+	}
+}