RPC Module for Relays (#80)

* Test defining an RPC API

* Add wrapper clients for the RPC API

* Implement most Ethereum RPCs

Does not include RPCs that require the bridge contract.

* Implement a few of the Substrate RPCs

Still missing proper error handling, as well as decoding responses from the
Substrate node.

* Make error handling more ergonomic

* Implement Substrate RPCs that use `state_call`

* Implement rest of Substrate RPCs

* Implement `eth_call` RPC

This can be used to implement higher level requests like fetching Substrate headers
from an Ethereum node.

* Build some of the higher level Ethereum RPCs

Uses the new Ethereum RPC interface to do so

* Build some of the higher level Substrate RPCs

* Remove old Ethereum RPC methods

* Remove old Substrate RPC methods

* Add some documentation to Substrate RPCs

* Fix typo in enum construction

* Revert commits `0f0435d` to `ca75502`

This range of commits was mainly trying to integrate the new RPC interface into the existing
codebase, however this turned out to be a little out of scope for the current PR. Instead this work
will be incorporated into a PR which aims to close #72.

* Add documentation to RPCs

* Rename functions in RPC API to conform to snake_case

* Check that header contains a number and hash

* Put doc comments on trait instead of impl methods

* Remove expect() calls

* Replace runtime API enums with consts

* Accept Bytes when submitting extrinsic

Let's us avoid using a runtime specific Extrinsic.

* Add strictly typed arguments to RPC API

Missing two methods right now, which require a `serde::Deserialize`
implemenation before they can be changed.

* Add `chain_getBlock` Substrate RPC

* Use typed arguments for `eth_estimateGas` and `eth_call`

* Silence dead code warnings

* Add check for logs bloom

* Remove unused variables

* Add documentation to RPC error enums

bridges/relays/ethereum/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2018"
 ansi_term = "0.12"
 async-std = "1.0.1"
 async-stream = "0.2.0"
+async-trait = "0.1.30"
 clap = { version = "2.33.1", features = ["yaml"] }
 codec = { package = "parity-scale-codec", version = "1.0.0" }
 env_logger = "0.7.0"

bridges/relays/ethereum/src/ethereum_types.rs

@@ -43,6 +43,9 @@ pub type EthereumHeaderId = HeaderId<H256, u64>;
 /// Queued ethereum header ID.
 pub type QueuedEthereumHeader = QueuedHeader<EthereumHeadersSyncPipeline>;
 
+/// A raw Ethereum transaction that's been signed.
+pub type SignedRawTx = Vec<u8>;
+
 /// Ethereum synchronization pipeline.
 #[derive(Clone, Copy, Debug)]
 #[cfg_attr(test, derive(PartialEq))]

bridges/relays/ethereum/src/main.rs

@@ -21,6 +21,8 @@ mod ethereum_deploy_contract;
 mod ethereum_sync_loop;
 mod ethereum_types;
 mod headers;
+mod rpc;
+mod rpc_errors;
 mod substrate_client;
 mod substrate_sync_loop;
 mod substrate_types;

bridges/relays/ethereum/src/rpc.rs

@@ -0,0 +1,301 @@
+// 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 <http://www.gnu.org/licenses/>.
+
+//! RPC Module
+
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#[warn(missing_docs)]
+use std::result;
+
+use crate::ethereum_client::EthereumConnectionParams;
+use crate::ethereum_types::{
+	Address as EthAddress, Bytes, CallRequest, EthereumHeaderId, Header as EthereumHeader, Receipt, SignedRawTx,
+	TransactionHash as EthereumTxHash, H256, U256, U64,
+};
+use crate::rpc_errors::{EthereumNodeError, RpcError};
+use crate::substrate_client::SubstrateConnectionParams;
+use crate::substrate_types::{
+	Hash as SubstrateHash, Header as SubstrateHeader, Number as SubBlockNumber, SignedBlock as SubstrateBlock,
+};
+use crate::sync_types::HeaderId;
+
+use async_trait::async_trait;
+use codec::{Decode, Encode};
+use jsonrpsee::raw::client::RawClient;
+use jsonrpsee::transport::http::HttpTransportClient;
+use sp_bridge_eth_poa::Header as SubstrateEthereumHeader;
+
+const ETH_API_BEST_BLOCK: &str = "EthereumHeadersApi_best_block";
+const ETH_API_IMPORT_REQUIRES_RECEIPTS: &str = "EthereumHeadersApi_is_import_requires_receipts";
+const ETH_API_IS_KNOWN_BLOCK: &str = "EthereumHeadersApi_is_known_block";
+const SUB_API_GRANDPA_AUTHORITIES: &str = "GrandpaApi_grandpa_authorities";
+
+type Result<T> = result::Result<T, RpcError>;
+type GrandpaAuthorityList = Vec<u8>;
+
+jsonrpsee::rpc_api! {
+	Ethereum {
+		#[rpc(method = "eth_estimateGas")]
+		fn estimate_gas(call_request: CallRequest) -> U256;
+		#[rpc(method = "eth_blockNumber")]
+		fn block_number() -> U64;
+		#[rpc(method = "eth_getBlockByNumber")]
+		fn get_block_by_number(block_number: u64) -> EthereumHeader;
+		#[rpc(method = "eth_getBlockByHash")]
+		fn get_block_by_hash(hash: H256) -> EthereumHeader;
+		#[rpc(method = "eth_getTransactionReceipt")]
+		fn get_transaction_receipt(transaction_hash: H256) -> Receipt;
+		#[rpc(method = "eth_getTransactionCount")]
+		fn get_transaction_count(address: EthAddress) -> U256;
+		#[rpc(method = "eth_submitTransaction")]
+		fn submit_transaction(transaction: Bytes) -> EthereumTxHash;
+		#[rpc(method = "eth_call")]
+		fn call(transaction_call: CallRequest) -> Bytes;
+	}
+
+	Substrate {
+		#[rpc(method = "chain_getHeader")]
+		fn chain_get_header(block_hash: Option<SubstrateHash>) -> SubstrateHeader;
+		#[rpc(method = "chain_getBlock")]
+		fn chain_get_block(block_hash: Option<SubstrateHash>) -> SubstrateBlock;
+		#[rpc(method = "chain_getBlockHash")]
+		fn chain_get_block_hash(block_number: Option<SubBlockNumber>) -> SubstrateHash;
+		#[rpc(method = "system_accountNextIndex")]
+		fn system_account_next_index(account_id: node_primitives::AccountId) -> node_primitives::Index;
+		#[rpc(method = "author_submitExtrinsic")]
+		fn author_submit_extrinsic(extrinsic: Bytes) -> SubstrateHash;
+		#[rpc(method = "state_call")]
+		fn state_call(method: String, data: Bytes, at_block: Option<SubstrateHash>) -> Bytes;
+	}
+}
+
+/// The API for the supported Ethereum RPC methods.
+#[async_trait]
+pub trait EthereumRpc {
+	/// Estimate gas usage for the given call.
+	async fn estimate_gas(&mut self, call_request: CallRequest) -> Result<U256>;
+	/// Retrieve number of the best known block from the Ethereum node.
+	async fn best_block_number(&mut self) -> Result<u64>;
+	/// Retrieve block header by its number from Ethereum node.
+	async fn header_by_number(&mut self, block_number: u64) -> Result<EthereumHeader>;
+	/// Retrieve block header by its hash from Ethereum node.
+	async fn header_by_hash(&mut self, hash: H256) -> Result<EthereumHeader>;
+	/// Retrieve transaction receipt by transaction hash.
+	async fn transaction_receipt(&mut self, transaction_hash: H256) -> Result<Receipt>;
+	/// Get the nonce of the given account.
+	async fn account_nonce(&mut self, address: EthAddress) -> Result<U256>;
+	/// Submit an Ethereum transaction.
+	///
+	/// The transaction must already be signed before sending it through this method.
+	async fn submit_transaction(&mut self, signed_raw_tx: SignedRawTx) -> Result<EthereumTxHash>;
+	/// Submit a call to an Ethereum smart contract.
+	async fn eth_call(&mut self, call_transaction: CallRequest) -> Result<Bytes>;
+}
+
+/// The client used to interact with an Ethereum node through RPC.
+pub struct EthereumRpcClient {
+	client: RawClient<HttpTransportClient>,
+}
+
+impl EthereumRpcClient {
+	/// Create a new Ethereum RPC Client.
+	pub fn new(params: EthereumConnectionParams) -> Self {
+		let uri = format!("http://{}:{}", params.host, params.port);
+		let transport = HttpTransportClient::new(&uri);
+		let client = RawClient::new(transport);
+
+		Self { client }
+	}
+}
+
+#[async_trait]
+impl EthereumRpc for EthereumRpcClient {
+	async fn estimate_gas(&mut self, call_request: CallRequest) -> Result<U256> {
+		Ok(Ethereum::estimate_gas(&mut self.client, call_request).await?)
+	}
+
+	async fn best_block_number(&mut self) -> Result<u64> {
+		Ok(Ethereum::block_number(&mut self.client).await?.as_u64())
+	}
+
+	async fn header_by_number(&mut self, block_number: u64) -> Result<EthereumHeader> {
+		let header = Ethereum::get_block_by_number(&mut self.client, block_number).await?;
+		match header.number.is_some() && header.hash.is_some() && header.logs_bloom.is_some() {
+			true => Ok(header),
+			false => Err(RpcError::Ethereum(EthereumNodeError::IncompleteHeader)),
+		}
+	}
+
+	async fn header_by_hash(&mut self, hash: H256) -> Result<EthereumHeader> {
+		let header = Ethereum::get_block_by_hash(&mut self.client, hash).await?;
+		match header.number.is_some() && header.hash.is_some() && header.logs_bloom.is_some() {
+			true => Ok(header),
+			false => Err(RpcError::Ethereum(EthereumNodeError::IncompleteHeader)),
+		}
+	}
+
+	async fn transaction_receipt(&mut self, transaction_hash: H256) -> Result<Receipt> {
+		let receipt = Ethereum::get_transaction_receipt(&mut self.client, transaction_hash).await?;
+
+		match receipt.gas_used {
+			Some(_) => Ok(receipt),
+			None => Err(RpcError::Ethereum(EthereumNodeError::IncompleteReceipt)),
+		}
+	}
+
+	async fn account_nonce(&mut self, address: EthAddress) -> Result<U256> {
+		Ok(Ethereum::get_transaction_count(&mut self.client, address).await?)
+	}
+
+	async fn submit_transaction(&mut self, signed_raw_tx: SignedRawTx) -> Result<EthereumTxHash> {
+		let transaction = Bytes(signed_raw_tx);
+		Ok(Ethereum::submit_transaction(&mut self.client, transaction).await?)
+	}
+
+	async fn eth_call(&mut self, call_transaction: CallRequest) -> Result<Bytes> {
+		Ok(Ethereum::call(&mut self.client, call_transaction).await?)
+	}
+}
+
+/// The API for the supported Substrate RPC methods.
+#[async_trait]
+pub trait SubstrateRpc {
+	/// Returns the best Substrate header.
+	async fn best_header(&mut self) -> Result<SubstrateHeader>;
+	/// Get a Substrate block from its hash.
+	async fn get_block(&mut self, block_hash: Option<SubstrateHash>) -> Result<SubstrateBlock>;
+	/// Get a Substrate header by its hash.
+	async fn header_by_hash(&mut self, hash: SubstrateHash) -> Result<SubstrateHeader>;
+	/// Get a Substrate block hash by its number.
+	async fn block_hash_by_number(&mut self, number: SubBlockNumber) -> Result<SubstrateHash>;
+	/// Get a Substrate header by its number.
+	async fn header_by_number(&mut self, block_number: SubBlockNumber) -> Result<SubstrateHeader>;
+	/// Get the nonce of the given Substrate account.
+	///
+	/// Note: It's the caller's responsibility to make sure `account` is a valid ss58 address.
+	async fn next_account_index(&mut self, account: node_primitives::AccountId) -> Result<node_primitives::Index>;
+	/// Returns best Ethereum block that Substrate runtime knows of.
+	async fn best_ethereum_block(&mut self) -> Result<EthereumHeaderId>;
+	/// Returns whether or not transactions receipts are required for Ethereum header submission.
+	async fn ethereum_receipts_required(&mut self, header: SubstrateEthereumHeader) -> Result<bool>;
+	/// Returns whether or not the given Ethereum header is known to the Substrate runtime.
+	async fn ethereum_header_known(&mut self, header_id: EthereumHeaderId) -> Result<bool>;
+	/// Submit an extrinsic for inclusion in a block.
+	///
+	/// Note: The given transaction does not need be SCALE encoded beforehand.
+	async fn submit_extrinsic(&mut self, transaction: Bytes) -> Result<SubstrateHash>;
+	/// Get the GRANDPA authority set at given block.
+	async fn grandpa_authorities_set(&mut self, block: SubstrateHash) -> Result<GrandpaAuthorityList>;
+}
+
+/// The client used to interact with a Substrate node through RPC.
+pub struct SubstrateRpcClient {
+	client: RawClient<HttpTransportClient>,
+}
+
+impl SubstrateRpcClient {
+	/// Create a new Substrate RPC Client.
+	pub fn new(params: SubstrateConnectionParams) -> Self {
+		let uri = format!("http://{}:{}", params.host, params.port);
+		let transport = HttpTransportClient::new(&uri);
+		let client = RawClient::new(transport);
+
+		Self { client }
+	}
+}
+
+#[async_trait]
+impl SubstrateRpc for SubstrateRpcClient {
+	async fn best_header(&mut self) -> Result<SubstrateHeader> {
+		Ok(Substrate::chain_get_header(&mut self.client, None).await?)
+	}
+
+	async fn get_block(&mut self, block_hash: Option<SubstrateHash>) -> Result<SubstrateBlock> {
+		Ok(Substrate::chain_get_block(&mut self.client, block_hash).await?)
+	}
+
+	async fn header_by_hash(&mut self, block_hash: SubstrateHash) -> Result<SubstrateHeader> {
+		Ok(Substrate::chain_get_header(&mut self.client, block_hash).await?)
+	}
+
+	async fn block_hash_by_number(&mut self, number: SubBlockNumber) -> Result<SubstrateHash> {
+		Ok(Substrate::chain_get_block_hash(&mut self.client, number).await?)
+	}
+
+	async fn header_by_number(&mut self, block_number: SubBlockNumber) -> Result<SubstrateHeader> {
+		let block_hash = Self::block_hash_by_number(self, block_number).await?;
+		Ok(Self::header_by_hash(self, block_hash).await?)
+	}
+
+	async fn next_account_index(&mut self, account: node_primitives::AccountId) -> Result<node_primitives::Index> {
+		Ok(Substrate::system_account_next_index(&mut self.client, account).await?)
+	}
+
+	async fn best_ethereum_block(&mut self) -> Result<EthereumHeaderId> {
+		let call = ETH_API_BEST_BLOCK.to_string();
+		let data = Bytes("0x".into());
+
+		let encoded_response = Substrate::state_call(&mut self.client, call, data, None).await?;
+		let decoded_response: (u64, sp_bridge_eth_poa::H256) = Decode::decode(&mut &encoded_response.0[..])?;
+
+		let best_header_id = HeaderId(decoded_response.0, decoded_response.1);
+		Ok(best_header_id)
+	}
+
+	async fn ethereum_receipts_required(&mut self, header: SubstrateEthereumHeader) -> Result<bool> {
+		let call = ETH_API_IMPORT_REQUIRES_RECEIPTS.to_string();
+		let data = Bytes(header.encode());
+
+		let encoded_response = Substrate::state_call(&mut self.client, call, data, None).await?;
+		let receipts_required: bool = Decode::decode(&mut &encoded_response.0[..])?;
+
+		// Gonna make it the responsibility of the caller to return (receipts_required, id)
+		Ok(receipts_required)
+	}
+
+	// The Substrate module could prune old headers. So this function could return false even
+	// if header is synced. And we'll mark corresponding Ethereum header as Orphan.
+	//
+	// But when we read the best header from Substrate next time, we will know that
+	// there's a better header. This Orphan will either be marked as synced, or
+	// eventually pruned.
+	async fn ethereum_header_known(&mut self, header_id: EthereumHeaderId) -> Result<bool> {
+		let call = ETH_API_IS_KNOWN_BLOCK.to_string();
+		let data = Bytes(header_id.1.encode());
+
+		let encoded_response = Substrate::state_call(&mut self.client, call, data, None).await?;
+		let is_known_block: bool = Decode::decode(&mut &encoded_response.0[..])?;
+
+		// Gonna make it the responsibility of the caller to return (is_known_block, id)
+		Ok(is_known_block)
+	}
+
+	async fn submit_extrinsic(&mut self, transaction: Bytes) -> Result<SubstrateHash> {
+		let encoded_transaction = Bytes(transaction.0.encode());
+		Ok(Substrate::author_submit_extrinsic(&mut self.client, encoded_transaction).await?)
+	}
+
+	async fn grandpa_authorities_set(&mut self, block: SubstrateHash) -> Result<GrandpaAuthorityList> {
+		let call = SUB_API_GRANDPA_AUTHORITIES.to_string();
+		let data = Bytes(block.as_bytes().to_vec());
+
+		let encoded_response = Substrate::state_call(&mut self.client, call, data, None).await?;
+		let authority_list = encoded_response.0;
+
+		Ok(authority_list)
+	}
+}

bridges/relays/ethereum/src/rpc_errors.rs

@@ -0,0 +1,98 @@
+// 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 <http://www.gnu.org/licenses/>.
+
+#![allow(dead_code)]
+
+use jsonrpsee::raw::client::RawClientError;
+use jsonrpsee::transport::http::RequestError;
+use serde_json;
+
+type RpcHttpError = RawClientError<RequestError>;
+
+/// Contains common errors that can occur when
+/// interacting with a Substrate or Ethereum node
+/// through RPC.
+#[derive(Debug)]
+pub enum RpcError {
+	/// The arguments to the RPC method failed to serialize.
+	Serialization(serde_json::Error),
+	/// An error occured when interacting with an Ethereum node.
+	Ethereum(EthereumNodeError),
+	/// An error occured when interacting with a Substrate node.
+	Substrate(SubstrateNodeError),
+	/// An error that can occur when making an HTTP request to
+	/// an JSON-RPC client.
+	Request(RpcHttpError),
+	/// The response from the client could not be SCALE decoded.
+	Decoding(codec::Error),
+}
+
+impl From<serde_json::Error> for RpcError {
+	fn from(err: serde_json::Error) -> Self {
+		Self::Serialization(err)
+	}
+}
+
+impl From<EthereumNodeError> for RpcError {
+	fn from(err: EthereumNodeError) -> Self {
+		Self::Ethereum(err)
+	}
+}
+
+impl From<SubstrateNodeError> for RpcError {
+	fn from(err: SubstrateNodeError) -> Self {
+		Self::Substrate(err)
+	}
+}
+
+impl From<RpcHttpError> for RpcError {
+	fn from(err: RpcHttpError) -> Self {
+		Self::Request(err)
+	}
+}
+
+impl From<codec::Error> for RpcError {
+	fn from(err: codec::Error) -> Self {
+		Self::Decoding(err)
+	}
+}
+
+/// Errors that can occur only when interacting with
+/// an Ethereum node through RPC.
+#[derive(Debug)]
+pub enum EthereumNodeError {
+	/// Failed to parse response.
+	ResponseParseFailed(String),
+	/// We have received a header with missing fields.
+	IncompleteHeader,
+	/// We have received a receipt missing a `gas_used` field.
+	IncompleteReceipt,
+	/// An invalid Substrate block number was received from
+	/// an Ethereum node.
+	InvalidSubstrateBlockNumber,
+}
+
+/// Errors that can occur only when interacting with
+/// a Substrate node through RPC.
+#[derive(Debug)]
+pub enum SubstrateNodeError {
+	/// Request start failed.
+	StartRequestFailed(RequestError),
+	/// Error serializing request.
+	RequestSerialization(serde_json::Error),
+	/// Failed to parse response.
+	ResponseParseFailed,
+}