// Copyright 2019-2020 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 . //! Substrate client as Substrate messages source. The chain we connect to should have //! runtime that implements `HeaderApi` to allow bridging with //! chain. use async_trait::async_trait; use bp_message_lane::{LaneId, MessageNonce}; use bp_runtime::InstanceId; use codec::{Decode, Encode}; use frame_support::weights::Weight; use messages_relay::{ message_lane::{MessageLane, SourceHeaderIdOf, TargetHeaderIdOf}, message_lane_loop::{ClientState, MessageProofParameters, MessageWeightsMap, SourceClient, SourceClientState}, }; use relay_substrate_client::{Chain, Client, Error as SubstrateError, HashOf, HeaderIdOf}; use relay_utils::HeaderId; use sp_core::Bytes; use sp_runtime::{traits::Header as HeaderT, DeserializeOwned}; use sp_trie::StorageProof; use std::{marker::PhantomData, ops::RangeInclusive}; /// Intermediate message proof returned by the source Substrate node. Includes everything /// required to submit to the target node: cumulative dispatch weight of bundled messages and /// the proof itself. pub type SubstrateMessagesProof = (Weight, (HashOf, StorageProof, LaneId, MessageNonce, MessageNonce)); /// Substrate client as Substrate messages source. pub struct SubstrateMessagesSource { client: Client, tx_maker: M, lane: LaneId, instance: InstanceId, _marker: PhantomData

, } /// Substrate transactions maker. #[async_trait] pub trait SubstrateTransactionMaker: Clone + Send + Sync { /// Signed transaction type. type SignedTransaction: Send + Sync + Encode; /// Make messages receiving proof transaction. async fn make_messages_receiving_proof_transaction( &self, generated_at_block: TargetHeaderIdOf

, proof: P::MessagesReceivingProof, ) -> Result; } impl SubstrateMessagesSource { /// Create new Substrate headers source. pub fn new(client: Client, tx_maker: M, lane: LaneId, instance: InstanceId) -> Self { SubstrateMessagesSource { client, tx_maker, lane, instance, _marker: Default::default(), } } } impl Clone for SubstrateMessagesSource { fn clone(&self) -> Self { Self { client: self.client.clone(), tx_maker: self.tx_maker.clone(), lane: self.lane, instance: self.instance, _marker: Default::default(), } } } #[async_trait] impl SourceClient

for SubstrateMessagesSource where C: Chain, C::Header: DeserializeOwned, C::Index: DeserializeOwned, ::Number: Into, P: MessageLane< MessagesProof = SubstrateMessagesProof, SourceHeaderNumber = ::Number, SourceHeaderHash = ::Hash, >, P::TargetHeaderNumber: Decode, P::TargetHeaderHash: Decode, M: SubstrateTransactionMaker, { type Error = SubstrateError; async fn reconnect(mut self) -> Result { let new_client = self.client.clone().reconnect().await?; self.client = new_client; Ok(self) } async fn state(&self) -> Result, Self::Error> { read_client_state::<_, P::TargetHeaderHash, P::TargetHeaderNumber>(&self.client, P::TARGET_NAME).await } async fn latest_generated_nonce( &self, id: SourceHeaderIdOf

, ) -> Result<(SourceHeaderIdOf

, MessageNonce), Self::Error> { let encoded_response = self .client .state_call( // TODO: https://github.com/paritytech/parity-bridges-common/issues/457 "OutboundLaneApi_latest_generated_nonce".into(), Bytes(self.lane.encode()), Some(id.1), ) .await?; let latest_generated_nonce: MessageNonce = Decode::decode(&mut &encoded_response.0[..]).map_err(SubstrateError::ResponseParseFailed)?; Ok((id, latest_generated_nonce)) } async fn latest_confirmed_received_nonce( &self, id: SourceHeaderIdOf

, ) -> Result<(SourceHeaderIdOf

, MessageNonce), Self::Error> { let encoded_response = self .client .state_call( // TODO: https://github.com/paritytech/parity-bridges-common/issues/457 "OutboundLaneApi_latest_received_nonce".into(), Bytes(self.lane.encode()), Some(id.1), ) .await?; let latest_received_nonce: MessageNonce = Decode::decode(&mut &encoded_response.0[..]).map_err(SubstrateError::ResponseParseFailed)?; Ok((id, latest_received_nonce)) } async fn generated_messages_weights( &self, id: SourceHeaderIdOf

, nonces: RangeInclusive, ) -> Result { let encoded_response = self .client .state_call( // TODO: https://github.com/paritytech/parity-bridges-common/issues/457 "OutboundLaneApi_messages_dispatch_weight".into(), Bytes((self.lane, nonces.start(), nonces.end()).encode()), Some(id.1), ) .await?; let weights: Vec<(MessageNonce, Weight)> = Decode::decode(&mut &encoded_response.0[..]).map_err(SubstrateError::ResponseParseFailed)?; let mut expected_nonce = *nonces.start(); let mut weights_map = MessageWeightsMap::new(); for (nonce, weight) in weights { if nonce != expected_nonce { return Err(SubstrateError::Custom(format!( "Unexpected nonce in messages_dispatch_weight call result. Expected {}, got {}", expected_nonce, nonce ))); } weights_map.insert(nonce, weight); expected_nonce += 1; } Ok(weights_map) } async fn prove_messages( &self, id: SourceHeaderIdOf

, nonces: RangeInclusive, proof_parameters: MessageProofParameters, ) -> Result<(SourceHeaderIdOf

, RangeInclusive, P::MessagesProof), Self::Error> { let proof = self .client .prove_messages( self.instance, self.lane, nonces.clone(), proof_parameters.outbound_state_proof_required, id.1, ) .await?; let proof = (id.1, proof, self.lane, *nonces.start(), *nonces.end()); Ok((id, nonces, (proof_parameters.dispatch_weight, proof))) } async fn submit_messages_receiving_proof( &self, generated_at_block: TargetHeaderIdOf

, proof: P::MessagesReceivingProof, ) -> Result<(), Self::Error> { let tx = self .tx_maker .make_messages_receiving_proof_transaction(generated_at_block, proof) .await?; self.client.submit_extrinsic(Bytes(tx.encode())).await?; Ok(()) } } pub async fn read_client_state( self_client: &Client, bridged_chain_name: &str, ) -> Result, HeaderId>, SubstrateError> where SelfChain: Chain, SelfChain::Header: DeserializeOwned, SelfChain::Index: DeserializeOwned, BridgedHeaderHash: Decode, BridgedHeaderNumber: Decode, { // let's read our state first: we need best finalized header hash on **this** chain let self_best_finalized_header_hash = self_client.best_finalized_header_hash().await?; let self_best_finalized_header = self_client.header_by_hash(self_best_finalized_header_hash).await?; let self_best_finalized_id = HeaderId(*self_best_finalized_header.number(), self_best_finalized_header_hash); // now let's read id of best finalized peer header at our best finalized block let best_finalized_peer_on_self_method = format!("{}HeaderApi_finalized_block", bridged_chain_name); let encoded_best_finalized_peer_on_self = self_client .state_call( best_finalized_peer_on_self_method, Bytes(Vec::new()), Some(self_best_finalized_header_hash), ) .await?; let decoded_best_finalized_peer_on_self: (BridgedHeaderNumber, BridgedHeaderHash) = Decode::decode(&mut &encoded_best_finalized_peer_on_self.0[..]).map_err(SubstrateError::ResponseParseFailed)?; let peer_on_self_best_finalized_id = HeaderId( decoded_best_finalized_peer_on_self.0, decoded_best_finalized_peer_on_self.1, ); Ok(ClientState { best_self: self_best_finalized_id, best_peer: peer_on_self_best_finalized_id, }) }