Move bridge extensions to a separate folder (#4096)

As requested in
paritytech/parity-bridges-common#2873 (comment)

bridges/bin/runtime-common/src/extensions/check_obsolete_extension.rs

@@ -0,0 +1,205 @@
+// Copyright (C) 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/>.
+
+//! Transaction extension that rejects bridge-related transactions, that include
+//! obsolete (duplicated) data or do not pass some additional pallet-specific
+//! checks.
+
+use crate::messages_call_ext::MessagesCallSubType;
+use pallet_bridge_grandpa::CallSubType as GrandpaCallSubType;
+use pallet_bridge_parachains::CallSubType as ParachainsCallSubtype;
+use sp_runtime::transaction_validity::TransactionValidity;
+
+/// A duplication of the `FilterCall` trait.
+///
+/// We need this trait in order to be able to implement it for the messages pallet,
+/// since the implementation is done outside of the pallet crate.
+pub trait BridgeRuntimeFilterCall<Call> {
+	/// Checks if a runtime call is valid.
+	fn validate(call: &Call) -> TransactionValidity;
+}
+
+impl<T, I: 'static> BridgeRuntimeFilterCall<T::RuntimeCall> for pallet_bridge_grandpa::Pallet<T, I>
+where
+	T: pallet_bridge_grandpa::Config<I>,
+	T::RuntimeCall: GrandpaCallSubType<T, I>,
+{
+	fn validate(call: &T::RuntimeCall) -> TransactionValidity {
+		GrandpaCallSubType::<T, I>::check_obsolete_submit_finality_proof(call)
+	}
+}
+
+impl<T, I: 'static> BridgeRuntimeFilterCall<T::RuntimeCall>
+	for pallet_bridge_parachains::Pallet<T, I>
+where
+	T: pallet_bridge_parachains::Config<I>,
+	T::RuntimeCall: ParachainsCallSubtype<T, I>,
+{
+	fn validate(call: &T::RuntimeCall) -> TransactionValidity {
+		ParachainsCallSubtype::<T, I>::check_obsolete_submit_parachain_heads(call)
+	}
+}
+
+impl<T: pallet_bridge_messages::Config<I>, I: 'static> BridgeRuntimeFilterCall<T::RuntimeCall>
+	for pallet_bridge_messages::Pallet<T, I>
+where
+	T::RuntimeCall: MessagesCallSubType<T, I>,
+{
+	/// Validate messages in order to avoid "mining" messages delivery and delivery confirmation
+	/// transactions, that are delivering outdated messages/confirmations. Without this validation,
+	/// even honest relayers may lose their funds if there are multiple relays running and
+	/// submitting the same messages/confirmations.
+	fn validate(call: &T::RuntimeCall) -> TransactionValidity {
+		call.check_obsolete_call()
+	}
+}
+
+/// Declares a runtime-specific `BridgeRejectObsoleteHeadersAndMessages` signed extension.
+///
+/// ## Example
+///
+/// ```nocompile
+/// generate_bridge_reject_obsolete_headers_and_messages!{
+///     Call, AccountId
+///     BridgeRococoGrandpa, BridgeRococoMessages,
+///     BridgeRococoParachains
+/// }
+/// ```
+///
+/// The goal of this extension is to avoid "mining" transactions that provide outdated bridged
+/// headers and messages. Without that extension, even honest relayers may lose their funds if
+/// there are multiple relays running and submitting the same information.
+#[macro_export]
+macro_rules! generate_bridge_reject_obsolete_headers_and_messages {
+	($call:ty, $account_id:ty, $($filter_call:ty),*) => {
+		#[derive(Clone, codec::Decode, Default, codec::Encode, Eq, PartialEq, sp_runtime::RuntimeDebug, scale_info::TypeInfo)]
+		pub struct BridgeRejectObsoleteHeadersAndMessages;
+		impl sp_runtime::traits::SignedExtension for BridgeRejectObsoleteHeadersAndMessages {
+			const IDENTIFIER: &'static str = "BridgeRejectObsoleteHeadersAndMessages";
+			type AccountId = $account_id;
+			type Call = $call;
+			type AdditionalSigned = ();
+			type Pre = ();
+
+			fn additional_signed(&self) -> sp_std::result::Result<
+				(),
+				sp_runtime::transaction_validity::TransactionValidityError,
+			> {
+				Ok(())
+			}
+
+			fn validate(
+				&self,
+				_who: &Self::AccountId,
+				call: &Self::Call,
+				_info: &sp_runtime::traits::DispatchInfoOf<Self::Call>,
+				_len: usize,
+			) -> sp_runtime::transaction_validity::TransactionValidity {
+				let valid = sp_runtime::transaction_validity::ValidTransaction::default();
+				$(
+					let valid = valid
+						.combine_with(<$filter_call as $crate::extensions::check_obsolete_extension::BridgeRuntimeFilterCall<$call>>::validate(call)?);
+				)*
+				Ok(valid)
+			}
+
+			fn pre_dispatch(
+				self,
+				who: &Self::AccountId,
+				call: &Self::Call,
+				info: &sp_runtime::traits::DispatchInfoOf<Self::Call>,
+				len: usize,
+			) -> Result<Self::Pre, sp_runtime::transaction_validity::TransactionValidityError> {
+				self.validate(who, call, info, len).map(drop)
+			}
+		}
+	};
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use frame_support::{assert_err, assert_ok};
+	use sp_runtime::{
+		traits::SignedExtension,
+		transaction_validity::{InvalidTransaction, TransactionValidity, ValidTransaction},
+	};
+
+	pub struct MockCall {
+		data: u32,
+	}
+
+	impl sp_runtime::traits::Dispatchable for MockCall {
+		type RuntimeOrigin = ();
+		type Config = ();
+		type Info = ();
+		type PostInfo = ();
+
+		fn dispatch(
+			self,
+			_origin: Self::RuntimeOrigin,
+		) -> sp_runtime::DispatchResultWithInfo<Self::PostInfo> {
+			unimplemented!()
+		}
+	}
+
+	struct FirstFilterCall;
+	impl BridgeRuntimeFilterCall<MockCall> for FirstFilterCall {
+		fn validate(call: &MockCall) -> TransactionValidity {
+			if call.data <= 1 {
+				return InvalidTransaction::Custom(1).into()
+			}
+
+			Ok(ValidTransaction { priority: 1, ..Default::default() })
+		}
+	}
+
+	struct SecondFilterCall;
+	impl BridgeRuntimeFilterCall<MockCall> for SecondFilterCall {
+		fn validate(call: &MockCall) -> TransactionValidity {
+			if call.data <= 2 {
+				return InvalidTransaction::Custom(2).into()
+			}
+
+			Ok(ValidTransaction { priority: 2, ..Default::default() })
+		}
+	}
+
+	#[test]
+	fn test() {
+		generate_bridge_reject_obsolete_headers_and_messages!(
+			MockCall,
+			(),
+			FirstFilterCall,
+			SecondFilterCall
+		);
+
+		assert_err!(
+			BridgeRejectObsoleteHeadersAndMessages.validate(&(), &MockCall { data: 1 }, &(), 0),
+			InvalidTransaction::Custom(1)
+		);
+
+		assert_err!(
+			BridgeRejectObsoleteHeadersAndMessages.validate(&(), &MockCall { data: 2 }, &(), 0),
+			InvalidTransaction::Custom(2)
+		);
+
+		assert_ok!(
+			BridgeRejectObsoleteHeadersAndMessages.validate(&(), &MockCall { data: 3 }, &(), 0),
+			ValidTransaction { priority: 3, ..Default::default() }
+		)
+	}
+}

bridges/bin/runtime-common/src/extensions/mod.rs

@@ -0,0 +1,21 @@
+// Copyright (C) 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/>.
+
+//! Bridge-specific transaction extensions.
+
+pub mod check_obsolete_extension;
+pub mod priority_calculator;
+pub mod refund_relayer_extension;

bridges/bin/runtime-common/src/refund_relayer_extension.rs → bridges/bin/runtime-common/src/extensions/refund_relayer_extension.rs

@@ -520,8 +520,9 @@ where
 		}
 
 		// compute priority boost
-		let priority_boost =
-			crate::priority_calculator::compute_priority_boost::<T::Priority>(bundled_messages);
+		let priority_boost = crate::extensions::priority_calculator::compute_priority_boost::<
+			T::Priority,
+		>(bundled_messages);
 		let valid_transaction = ValidTransactionBuilder::default().priority(priority_boost);
 
 		log::trace!(