Substrate relay guards (#470)

* substrate relay guards

* checked time condition

* ChainWithBalances

* removed obsolete comment

* Update relays/substrate-client/src/chain.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* trailing space

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

bridges/primitives/runtime/src/chain.rs

@@ -23,7 +23,7 @@ use sp_runtime::traits::{
 use sp_std::str::FromStr;
 
 /// Minimal Substrate-based chain representation that may be used from no_std environment.
-pub trait Chain {
+pub trait Chain: Send + Sync + 'static {
 	/// A type that fulfills the abstract idea of what a Substrate block number is.
 	// Constraits come from the associated Number type of `sp_runtime::traits::Header`
 	// See here for more info:

bridges/relays/millau-client/Cargo.toml

@@ -17,6 +17,7 @@ millau-runtime = { path = "../../bin/millau/runtime" }
 
 # Substrate Dependencies
 
+frame-support = "2.0"
 frame-system = "2.0"
 pallet-transaction-payment = "2.0"
 sp-core = "2.0"

bridges/relays/millau-client/src/lib.rs

@@ -18,12 +18,13 @@
 
 use codec::Encode;
 use headers_relay::sync_types::SourceHeader;
-use relay_substrate_client::{Chain, ChainBase, Client, TransactionSignScheme};
-use sp_core::Pair;
+use relay_substrate_client::{Chain, ChainBase, ChainWithBalances, Client, TransactionSignScheme};
+use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{
 	generic::SignedPayload,
 	traits::{Header as HeaderT, IdentifyAccount},
 };
+use std::time::Duration;
 
 /// Millau header id.
 pub type HeaderId = relay_utils::HeaderId<millau_runtime::Hash, millau_runtime::BlockNumber>;
@@ -40,12 +41,26 @@ impl ChainBase for Millau {
 }
 
 impl Chain for Millau {
+	const NAME: &'static str = "Millau";
+	const AVERAGE_BLOCK_INTERVAL: Duration = Duration::from_secs(5);
+
 	type AccountId = millau_runtime::AccountId;
 	type Index = millau_runtime::Index;
 	type SignedBlock = millau_runtime::SignedBlock;
 	type Call = millau_runtime::Call;
 }
 
+impl ChainWithBalances for Millau {
+	type NativeBalance = millau_runtime::Balance;
+
+	fn account_info_storage_key(account_id: &Self::AccountId) -> StorageKey {
+		use frame_support::storage::generator::StorageMap;
+		StorageKey(frame_system::Account::<millau_runtime::Runtime>::storage_map_final_key(
+			account_id,
+		))
+	}
+}
+
 impl TransactionSignScheme for Millau {
 	type Chain = Millau;
 	type AccountKeyPair = sp_core::sr25519::Pair;

bridges/relays/rialto-client/Cargo.toml

@@ -18,6 +18,7 @@ rialto-runtime = { path = "../../bin/rialto/runtime" }
 # Substrate Dependencies
 
 frame-system = "2.0"
+frame-support = "2.0"
 pallet-transaction-payment = "2.0"
 sp-core = "2.0"
 sp-keyring = "2.0"

bridges/relays/rialto-client/src/lib.rs

@@ -18,12 +18,13 @@
 
 use codec::Encode;
 use headers_relay::sync_types::SourceHeader;
-use relay_substrate_client::{Chain, ChainBase, Client, TransactionSignScheme};
-use sp_core::Pair;
+use relay_substrate_client::{Chain, ChainBase, ChainWithBalances, Client, TransactionSignScheme};
+use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{
 	generic::SignedPayload,
 	traits::{Header as HeaderT, IdentifyAccount},
 };
+use std::time::Duration;
 
 pub use rialto_runtime::BridgeMillauCall;
 
@@ -42,12 +43,26 @@ impl ChainBase for Rialto {
 }
 
 impl Chain for Rialto {
+	const NAME: &'static str = "Rialto";
+	const AVERAGE_BLOCK_INTERVAL: Duration = Duration::from_secs(5);
+
 	type AccountId = rialto_runtime::AccountId;
 	type Index = rialto_runtime::Index;
 	type SignedBlock = rialto_runtime::SignedBlock;
 	type Call = rialto_runtime::Call;
 }
 
+impl ChainWithBalances for Rialto {
+	type NativeBalance = rialto_runtime::Balance;
+
+	fn account_info_storage_key(account_id: &Self::AccountId) -> StorageKey {
+		use frame_support::storage::generator::StorageMap;
+		StorageKey(frame_system::Account::<rialto_runtime::Runtime>::storage_map_final_key(
+			account_id,
+		))
+	}
+}
+
 impl TransactionSignScheme for Rialto {
 	type Chain = Rialto;
 	type AccountKeyPair = sp_core::sr25519::Pair;

bridges/relays/substrate-client/Cargo.toml

@@ -6,11 +6,13 @@ edition = "2018"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 
 [dependencies]
+async-std = "1.6.5"
 async-trait = "0.1.40"
 codec = { package = "parity-scale-codec", version = "1.3.4" }
 jsonrpsee = { git = "https://github.com/svyatonik/jsonrpsee.git", branch = "shared-client-in-rpc-api", default-features = false, features = ["ws"] }
 log = "0.4.11"
 num-traits = "0.2"
+rand = "0.7"
 
 # Bridge dependencies
 
@@ -22,6 +24,10 @@ relay-utils = { path = "../utils" }
 
 frame-support = "2.0"
 frame-system = "2.0"
+pallet-balances = "2.0"
 sp-core = "2.0"
 sp-runtime = "2.0"
-sp-std = "2.0"
+sp-version = "2.0"
+
+#[dev-dependencies]
+futures = "0.3.7"

bridges/relays/substrate-client/src/chain.rs

@@ -19,16 +19,24 @@ use crate::client::Client;
 use bp_runtime::Chain as ChainBase;
 use frame_support::Parameter;
 use jsonrpsee::common::{DeserializeOwned, Serialize};
-use sp_core::Pair;
+use num_traits::{CheckedSub, Zero};
+use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{
 	generic::SignedBlock,
 	traits::{AtLeast32Bit, Dispatchable, MaybeDisplay, MaybeSerialize, MaybeSerializeDeserialize, Member},
 	Justification,
 };
-use sp_std::fmt::Debug;
+use std::{fmt::Debug, time::Duration};
 
 /// Substrate-based chain from minimal relay-client point of view.
 pub trait Chain: ChainBase {
+	/// Chain name.
+	const NAME: &'static str;
+	/// Average block interval.
+	///
+	/// How often blocks are produced on that chain. It's suggested to set this value to match the block time of the chain.
+	const AVERAGE_BLOCK_INTERVAL: Duration;
+
 	/// The user account identifier type for the runtime.
 	type AccountId: Parameter + Member + MaybeSerializeDeserialize + Debug + MaybeDisplay + Ord + Default;
 	/// Account index (aka nonce) type. This stores the number of previous transactions associated
@@ -40,6 +48,16 @@ pub trait Chain: ChainBase {
 	type Call: Dispatchable + Debug;
 }
 
+/// Substrate-based chain with `frame_system::Trait::AccountData` set to
+/// the `pallet_balances::AccountData<NativeBalance>`.
+pub trait ChainWithBalances: Chain {
+	/// Balance of an account in native tokens.
+	type NativeBalance: Parameter + Member + DeserializeOwned + Clone + Copy + CheckedSub + PartialOrd + Zero;
+
+	/// Return runtime storage key for getting `frame_system::AccountInfo` of given account.
+	fn account_info_storage_key(account_id: &Self::AccountId) -> StorageKey;
+}
+
 /// Block with justification.
 pub trait BlockWithJustification {
 	/// Return block justification, if known.
@@ -64,6 +82,12 @@ pub trait TransactionSignScheme {
 	) -> Self::SignedTransaction;
 }
 
+impl BlockWithJustification for () {
+	fn justification(&self) -> Option<&Justification> {
+		None
+	}
+}
+
 impl<Block> BlockWithJustification for SignedBlock<Block> {
 	fn justification(&self) -> Option<&Justification> {
 		self.justification.as_ref()

bridges/relays/substrate-client/src/client.rs

@@ -16,16 +16,21 @@
 
 //! Substrate node client.
 
-use crate::chain::Chain;
+use crate::chain::{Chain, ChainWithBalances};
+use crate::error::Error;
 use crate::rpc::Substrate;
 use crate::{ConnectionParams, Result};
 
+use codec::Decode;
+use frame_system::AccountInfo;
 use jsonrpsee::common::DeserializeOwned;
 use jsonrpsee::raw::RawClient;
 use jsonrpsee::transport::ws::WsTransportClient;
 use jsonrpsee::{client::Subscription, Client as RpcClient};
 use num_traits::Zero;
+use pallet_balances::AccountData;
 use sp_core::Bytes;
+use sp_version::RuntimeVersion;
 
 const SUB_API_GRANDPA_AUTHORITIES: &str = "GrandpaApi_grandpa_authorities";
 
@@ -69,18 +74,17 @@ impl<C: Chain> Client<C> {
 	}
 }
 
-impl<C: Chain> Client<C>
-where
-	C::Header: DeserializeOwned,
-	C::Index: DeserializeOwned,
-{
+impl<C: Chain> Client<C> {
 	/// Return hash of the genesis block.
 	pub fn genesis_hash(&self) -> &C::Hash {
 		&self.genesis_hash
 	}
 
 	/// Returns the best Substrate header.
-	pub async fn best_header(&self) -> Result<C::Header> {
+	pub async fn best_header(&self) -> Result<C::Header>
+	where
+		C::Header: DeserializeOwned,
+	{
 		Ok(Substrate::<C, _, _>::chain_get_header(&self.client, None).await?)
 	}
 
@@ -90,7 +94,10 @@ where
 	}
 
 	/// Get a Substrate header by its hash.
-	pub async fn header_by_hash(&self, block_hash: C::Hash) -> Result<C::Header> {
+	pub async fn header_by_hash(&self, block_hash: C::Hash) -> Result<C::Header>
+	where
+		C::Header: DeserializeOwned,
+	{
 		Ok(Substrate::<C, _, _>::chain_get_header(&self.client, block_hash).await?)
 	}
 
@@ -100,15 +107,41 @@ where
 	}
 
 	/// Get a Substrate header by its number.
-	pub async fn header_by_number(&self, block_number: C::BlockNumber) -> Result<C::Header> {
+	pub async fn header_by_number(&self, block_number: C::BlockNumber) -> Result<C::Header>
+	where
+		C::Header: DeserializeOwned,
+	{
 		let block_hash = Self::block_hash_by_number(self, block_number).await?;
 		Ok(Self::header_by_hash(self, block_hash).await?)
 	}
 
+	/// Return runtime version.
+	pub async fn runtime_version(&self) -> Result<RuntimeVersion> {
+		Ok(Substrate::<C, _, _>::runtime_version(&self.client).await?)
+	}
+
+	/// Return native tokens balance of the account.
+	pub async fn free_native_balance(&self, account: C::AccountId) -> Result<C::NativeBalance>
+	where
+		C: ChainWithBalances,
+	{
+		let storage_key = C::account_info_storage_key(&account);
+		let encoded_account_data = Substrate::<C, _, _>::get_storage(&self.client, storage_key)
+			.await?
+			.ok_or(Error::AccountDoesNotExist)?;
+		let decoded_account_data =
+			AccountInfo::<C::Index, AccountData<C::NativeBalance>>::decode(&mut &encoded_account_data.0[..])
+				.map_err(Error::ResponseParseFailed)?;
+		Ok(decoded_account_data.data.free)
+	}
+
 	/// Get the nonce of the given Substrate account.
 	///
 	/// Note: It's the caller's responsibility to make sure `account` is a valid ss58 address.
-	pub async fn next_account_index(&self, account: C::AccountId) -> Result<C::Index> {
+	pub async fn next_account_index(&self, account: C::AccountId) -> Result<C::Index>
+	where
+		C::Index: DeserializeOwned,
+	{
 		Ok(Substrate::<C, _, _>::system_account_next_index(&self.client, account).await?)
 	}
 

bridges/relays/substrate-client/src/error.rs

@@ -34,6 +34,8 @@ pub enum Error {
 	Request(RequestError),
 	/// The response from the server could not be SCALE decoded.
 	ResponseParseFailed(codec::Error),
+	/// Account does not exist on the chain.
+	AccountDoesNotExist,
 }
 
 impl From<WsNewDnsError> for Error {
@@ -66,6 +68,7 @@ impl ToString for Error {
 			Self::WsConnectionError(e) => e.to_string(),
 			Self::Request(e) => e.to_string(),
 			Self::ResponseParseFailed(e) => e.what().to_string(),
+			Self::AccountDoesNotExist => "Account does not exist on the chain".into(),
 		}
 	}
 }

bridges/relays/substrate-client/src/guard.rs

@@ -0,0 +1,371 @@
+// 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/>.
+
+//! Module provides a set of guard functions that are running in background threads
+//! and are aborting process if some condition fails.
+
+use crate::{Chain, ChainWithBalances, Client};
+
+use async_trait::async_trait;
+use num_traits::CheckedSub;
+use sp_version::RuntimeVersion;
+use std::{
+	collections::VecDeque,
+	time::{Duration, Instant},
+};
+
+/// Guards environment.
+#[async_trait]
+pub trait Environment<C: ChainWithBalances>: Send + Sync + 'static {
+	/// Return current runtime version.
+	async fn runtime_version(&mut self) -> Result<RuntimeVersion, String>;
+	/// Return free native balance of the account on the chain.
+	async fn free_native_balance(&mut self, account: C::AccountId) -> Result<C::NativeBalance, String>;
+
+	/// Return current time.
+	fn now(&self) -> Instant {
+		Instant::now()
+	}
+	/// Sleep given amount of time.
+	async fn sleep(&mut self, duration: Duration) {
+		async_std::task::sleep(duration).await
+	}
+	/// Abort current process. Called when guard condition check fails.
+	async fn abort(&mut self) {
+		std::process::abort();
+	}
+}
+
+/// Abort when runtime spec version is different from specified.
+pub fn abort_on_spec_version_change<C: ChainWithBalances>(mut env: impl Environment<C>, expected_spec_version: u32) {
+	async_std::task::spawn(async move {
+		loop {
+			let actual_spec_version = env.runtime_version().await;
+			match actual_spec_version {
+				Ok(version) if version.spec_version == expected_spec_version => (),
+				Ok(version) => {
+					log::error!(
+						target: "bridge-guard",
+						"{} runtime spec version has changed from {} to {}. Aborting relay",
+						C::NAME,
+						expected_spec_version,
+						version.spec_version,
+					);
+
+					env.abort().await;
+				}
+				Err(error) => log::warn!(
+					target: "bridge-guard",
+					"Failed to read {} runtime version: {:?}. Relay may need to be stopped manually",
+					C::NAME,
+					error,
+				),
+			}
+
+			env.sleep(conditions_check_delay::<C>()).await;
+		}
+	});
+}
+
+/// Abort if, during a 24 hours, free balance of given account is decreased at least by given value.
+/// Other components may increase (or decrease) balance of account and it WILL affect logic of the guard.
+pub fn abort_when_account_balance_decreased<C: ChainWithBalances>(
+	mut env: impl Environment<C>,
+	account_id: C::AccountId,
+	maximal_decrease: C::NativeBalance,
+) {
+	const DAY: Duration = Duration::from_secs(60 * 60 * 24);
+
+	async_std::task::spawn(async move {
+		let mut balances = VecDeque::new();
+
+		loop {
+			let current_time = env.now();
+
+			// remember balances that are beyound 24h border
+			let time_border = current_time - DAY;
+			while balances.front().map(|(time, _)| *time < time_border).unwrap_or(false) {
+				balances.pop_front();
+			}
+
+			// read balance of the account
+			let current_balance = env.free_native_balance(account_id.clone()).await;
+
+			// remember balance and check difference
+			match current_balance {
+				Ok(current_balance) => {
+					// remember balance
+					balances.push_back((current_time, current_balance));
+
+					// check if difference between current and oldest balance is too large
+					let (oldest_time, oldest_balance) =
+						balances.front().expect("pushed to queue couple of lines above; qed");
+					let balances_difference = oldest_balance.checked_sub(&current_balance);
+					if balances_difference > Some(maximal_decrease) {
+						log::error!(
+							target: "bridge-guard",
+							"Balance of {} account {:?} has decreased from {:?} to {:?} in {} minutes. Aborting relay",
+							C::NAME,
+							account_id,
+							oldest_balance,
+							current_balance,
+							current_time.duration_since(*oldest_time).as_secs() / 60,
+						);
+
+						env.abort().await;
+					}
+				}
+				Err(error) => {
+					log::warn!(
+						target: "bridge-guard",
+						"Failed to read {} account {:?} balance: {:?}. Relay may need to be stopped manually",
+						C::NAME,
+						account_id,
+						error,
+					);
+				}
+			};
+
+			env.sleep(conditions_check_delay::<C>()).await;
+		}
+	});
+}
+
+/// Delay between conditions check.
+fn conditions_check_delay<C: Chain>() -> Duration {
+	C::AVERAGE_BLOCK_INTERVAL * (10 + rand::random::<u32>() % 10)
+}
+
+#[async_trait]
+impl<C: ChainWithBalances> Environment<C> for Client<C> {
+	async fn runtime_version(&mut self) -> Result<RuntimeVersion, String> {
+		Client::<C>::runtime_version(self).await.map_err(|e| e.to_string())
+	}
+
+	async fn free_native_balance(&mut self, account: C::AccountId) -> Result<C::NativeBalance, String> {
+		Client::<C>::free_native_balance(self, account)
+			.await
+			.map_err(|e| e.to_string())
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use futures::{
+		channel::mpsc::{unbounded, UnboundedReceiver, UnboundedSender},
+		future::FutureExt,
+		stream::StreamExt,
+		SinkExt,
+	};
+
+	struct TestChain;
+
+	impl bp_runtime::Chain for TestChain {
+		type BlockNumber = u32;
+		type Hash = sp_core::H256;
+		type Hasher = sp_runtime::traits::BlakeTwo256;
+		type Header = sp_runtime::generic::Header<u32, sp_runtime::traits::BlakeTwo256>;
+	}
+
+	impl Chain for TestChain {
+		const NAME: &'static str = "Test";
+		const AVERAGE_BLOCK_INTERVAL: Duration = Duration::from_millis(1);
+
+		type AccountId = u32;
+		type Index = u32;
+		type SignedBlock = ();
+		type Call = ();
+	}
+
+	impl ChainWithBalances for TestChain {
+		type NativeBalance = u32;
+
+		fn account_info_storage_key(_account_id: &u32) -> sp_core::storage::StorageKey {
+			unreachable!()
+		}
+	}
+
+	struct TestEnvironment {
+		runtime_version_rx: UnboundedReceiver<RuntimeVersion>,
+		free_native_balance_rx: UnboundedReceiver<u32>,
+		slept_tx: UnboundedSender<()>,
+		aborted_tx: UnboundedSender<()>,
+	}
+
+	#[async_trait]
+	impl Environment<TestChain> for TestEnvironment {
+		async fn runtime_version(&mut self) -> Result<RuntimeVersion, String> {
+			Ok(self.runtime_version_rx.next().await.unwrap_or_default())
+		}
+
+		async fn free_native_balance(&mut self, _account: u32) -> Result<u32, String> {
+			Ok(self.free_native_balance_rx.next().await.unwrap_or_default())
+		}
+
+		async fn sleep(&mut self, _duration: Duration) {
+			let _ = self.slept_tx.send(()).await;
+		}
+
+		async fn abort(&mut self) {
+			let _ = self.aborted_tx.send(()).await;
+			// simulate process abort :)
+			async_std::task::sleep(Duration::from_secs(60)).await;
+		}
+	}
+
+	#[test]
+	fn aborts_when_spec_version_is_changed() {
+		async_std::task::block_on(async {
+			let (
+				(mut runtime_version_tx, runtime_version_rx),
+				(_free_native_balance_tx, free_native_balance_rx),
+				(slept_tx, mut slept_rx),
+				(aborted_tx, mut aborted_rx),
+			) = (unbounded(), unbounded(), unbounded(), unbounded());
+			abort_on_spec_version_change(
+				TestEnvironment {
+					runtime_version_rx,
+					free_native_balance_rx,
+					slept_tx,
+					aborted_tx,
+				},
+				0,
+			);
+
+			// client responds with wrong version
+			runtime_version_tx
+				.send(RuntimeVersion {
+					spec_version: 42,
+					..Default::default()
+				})
+				.await
+				.unwrap();
+
+			// then the `abort` function is called
+			aborted_rx.next().await;
+			// and we do not reach the `sleep` function call
+			assert!(slept_rx.next().now_or_never().is_none());
+		});
+	}
+
+	#[test]
+	fn does_not_aborts_when_spec_version_is_unchanged() {
+		async_std::task::block_on(async {
+			let (
+				(mut runtime_version_tx, runtime_version_rx),
+				(_free_native_balance_tx, free_native_balance_rx),
+				(slept_tx, mut slept_rx),
+				(aborted_tx, mut aborted_rx),
+			) = (unbounded(), unbounded(), unbounded(), unbounded());
+			abort_on_spec_version_change(
+				TestEnvironment {
+					runtime_version_rx,
+					free_native_balance_rx,
+					slept_tx,
+					aborted_tx,
+				},
+				42,
+			);
+
+			// client responds with the same version
+			runtime_version_tx
+				.send(RuntimeVersion {
+					spec_version: 42,
+					..Default::default()
+				})
+				.await
+				.unwrap();
+
+			// then the `sleep` function is called
+			slept_rx.next().await;
+			// and the `abort` function is not called
+			assert!(aborted_rx.next().now_or_never().is_none());
+		});
+	}
+
+	#[test]
+	fn aborts_when_balance_is_too_low() {
+		async_std::task::block_on(async {
+			let (
+				(_runtime_version_tx, runtime_version_rx),
+				(mut free_native_balance_tx, free_native_balance_rx),
+				(slept_tx, mut slept_rx),
+				(aborted_tx, mut aborted_rx),
+			) = (unbounded(), unbounded(), unbounded(), unbounded());
+			abort_when_account_balance_decreased(
+				TestEnvironment {
+					runtime_version_rx,
+					free_native_balance_rx,
+					slept_tx,
+					aborted_tx,
+				},
+				0,
+				100,
+			);
+
+			// client responds with initial balance
+			free_native_balance_tx.send(1000).await.unwrap();
+
+			// then the guard sleeps
+			slept_rx.next().await;
+
+			// and then client responds with updated balance, which is too low
+			free_native_balance_tx.send(899).await.unwrap();
+
+			// then the `abort` function is called
+			aborted_rx.next().await;
+			// and we do not reach next `sleep` function call
+			assert!(slept_rx.next().now_or_never().is_none());
+		});
+	}
+
+	#[test]
+	fn does_not_aborts_when_balance_is_enough() {
+		async_std::task::block_on(async {
+			let (
+				(_runtime_version_tx, runtime_version_rx),
+				(mut free_native_balance_tx, free_native_balance_rx),
+				(slept_tx, mut slept_rx),
+				(aborted_tx, mut aborted_rx),
+			) = (unbounded(), unbounded(), unbounded(), unbounded());
+			abort_when_account_balance_decreased(
+				TestEnvironment {
+					runtime_version_rx,
+					free_native_balance_rx,
+					slept_tx,
+					aborted_tx,
+				},
+				0,
+				100,
+			);
+
+			// client responds with initial balance
+			free_native_balance_tx.send(1000).await.unwrap();
+
+			// then the guard sleeps
+			slept_rx.next().await;
+
+			// and then client responds with updated balance, which is enough
+			free_native_balance_tx.send(950).await.unwrap();
+
+			// then the `sleep` function is called
+			slept_rx.next().await;
+			// and `abort` is not called
+			assert!(aborted_rx.next().now_or_never().is_none());
+		});
+	}
+}

bridges/relays/substrate-client/src/lib.rs

@@ -23,9 +23,10 @@ mod client;
 mod error;
 mod rpc;
 
+pub mod guard;
 pub mod headers_source;
 
-pub use crate::chain::{BlockWithJustification, Chain, TransactionSignScheme};
+pub use crate::chain::{BlockWithJustification, Chain, ChainWithBalances, TransactionSignScheme};
 pub use crate::client::{Client, JustificationsSubscription, OpaqueGrandpaAuthoritiesSet};
 pub use crate::error::{Error, Result};
 pub use bp_runtime::{BlockNumberOf, Chain as ChainBase, HashOf, HeaderOf};

bridges/relays/substrate-client/src/rpc.rs

@@ -23,7 +23,11 @@
 
 use crate::chain::Chain;
 
-use sp_core::Bytes;
+use sp_core::{
+	storage::{StorageData, StorageKey},
+	Bytes,
+};
+use sp_version::RuntimeVersion;
 
 jsonrpsee::rpc_api! {
 	pub(crate) Substrate<C: Chain> {
@@ -39,5 +43,9 @@ jsonrpsee::rpc_api! {
 		fn author_submit_extrinsic(extrinsic: Bytes) -> C::Hash;
 		#[rpc(method = "state_call", positional_params)]
 		fn state_call(method: String, data: Bytes, at_block: Option<C::Hash>) -> Bytes;
+		#[rpc(method = "state_getStorage", positional_params)]
+		fn get_storage(key: StorageKey) -> Option<StorageData>;
+		#[rpc(method = "state_getRuntimeVersion", positional_params)]
+		fn runtime_version() -> RuntimeVersion;
 	}
 }