pay dispatch fee at target chain (#911)

* pay dispatch fee at target chain

* refund unspent dispatch weight to messages relayer

* test that transfer actually happens

* pay-at-target-cchain benchmarks + fix previous benchmarks (invalid signature)

* include/exclude pay-dispatch-fee weight from delivery_and_dispatch_fee/delivery tx cost

* remvoe some redundant traces

* enum DispatchFeePayment {}

* typo

* update docs

* (revert removal of valid check)

* Update modules/messages/src/benchmarking.rs

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

* Update modules/messages/src/benchmarking.rs

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

* Update modules/messages/src/benchmarking.rs

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

* Update modules/messages/src/benchmarking.rs

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

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

bridges/bin/millau/runtime/src/lib.rs

@@ -686,6 +686,7 @@ mod tests {
 			bp_millau::DEFAULT_MESSAGE_DELIVERY_TX_WEIGHT,
 			bp_millau::ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT,
 			bp_millau::MAX_SINGLE_MESSAGE_DELIVERY_CONFIRMATION_TX_WEIGHT,
+			bp_millau::PAY_INBOUND_DISPATCH_FEE_WEIGHT,
 		);
 
 		let max_incoming_message_proof_size = bp_rialto::EXTRA_STORAGE_PROOF_SIZE.saturating_add(

bridges/bin/millau/runtime/src/rialto_messages.rs

@@ -64,6 +64,7 @@ type ToRialtoMessagesDeliveryProof = messages::source::FromBridgedChainMessagesD
 pub type FromRialtoMessageDispatch = messages::target::FromBridgedChainMessageDispatch<
 	WithRialtoMessageBridge,
 	crate::Runtime,
+	pallet_balances::Pallet<Runtime>,
 	pallet_bridge_dispatch::DefaultInstance,
 >;
 
@@ -172,6 +173,7 @@ impl messages::BridgedChainWithMessages for Rialto {
 
 	fn estimate_delivery_transaction(
 		message_payload: &[u8],
+		include_pay_dispatch_fee_cost: bool,
 		message_dispatch_weight: Weight,
 	) -> MessageTransaction<Weight> {
 		let message_payload_len = u32::try_from(message_payload.len()).unwrap_or(u32::MAX);
@@ -182,6 +184,11 @@ impl messages::BridgedChainWithMessages for Rialto {
 			dispatch_weight: extra_bytes_in_payload
 				.saturating_mul(bp_rialto::ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT)
 				.saturating_add(bp_rialto::DEFAULT_MESSAGE_DELIVERY_TX_WEIGHT)
+				.saturating_sub(if include_pay_dispatch_fee_cost {
+					0
+				} else {
+					bp_rialto::PAY_INBOUND_DISPATCH_FEE_WEIGHT
+				})
 				.saturating_add(message_dispatch_weight),
 			size: message_payload_len
 				.saturating_add(bp_millau::EXTRA_STORAGE_PROOF_SIZE)

bridges/bin/rialto/runtime/src/lib.rs

@@ -862,6 +862,7 @@ impl_runtime_apis! {
 			}
 
 			use crate::millau_messages::{ToMillauMessagePayload, WithMillauMessageBridge};
+			use bp_runtime::messages::DispatchFeePayment;
 			use bridge_runtime_common::messages;
 			use pallet_bridge_messages::benchmarking::{
 				Pallet as MessagesBench,
@@ -905,6 +906,7 @@ impl_runtime_apis! {
 						weight: params.size as _,
 						origin: dispatch_origin,
 						call: message_payload,
+						dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 					};
 					(message, pallet_bridge_messages::benchmarking::MESSAGE_FEE.into())
 				}
@@ -921,7 +923,7 @@ impl_runtime_apis! {
 					use codec::Encode;
 					use frame_support::weights::GetDispatchInfo;
 					use pallet_bridge_messages::storage_keys;
-					use sp_runtime::traits::Header;
+					use sp_runtime::traits::{Header, IdentifyAccount};
 
 					let remark = match params.size {
 						MessagesProofSize::Minimal(ref size) => vec![0u8; *size as _],
@@ -934,12 +936,19 @@ impl_runtime_apis! {
 					let (rialto_raw_public, rialto_raw_signature) = ed25519_sign(
 						&call,
 						&millau_account_id,
+						VERSION.spec_version,
+						bp_runtime::MILLAU_CHAIN_ID,
+						bp_runtime::RIALTO_CHAIN_ID,
 					);
 					let rialto_public = MultiSigner::Ed25519(sp_core::ed25519::Public::from_raw(rialto_raw_public));
 					let rialto_signature = MultiSignature::Ed25519(sp_core::ed25519::Signature::from_raw(
 						rialto_raw_signature,
 					));
 
+					if params.dispatch_fee_payment == DispatchFeePayment::AtTargetChain {
+						Self::endow_account(&rialto_public.clone().into_account());
+					}
+
 					let make_millau_message_key = |message_key: MessageKey| storage_keys::message_key::<
 						Runtime,
 						<Millau as ChainWithMessages>::MessagesInstance,
@@ -960,6 +969,7 @@ impl_runtime_apis! {
 						Default::default(),
 					);
 
+					let dispatch_fee_payment = params.dispatch_fee_payment.clone();
 					prepare_message_proof::<WithMillauMessageBridge, bp_millau::Hasher, Runtime, (), _, _, _>(
 						params,
 						make_millau_message_key,
@@ -978,6 +988,7 @@ impl_runtime_apis! {
 								rialto_public,
 								rialto_signature,
 							),
+							dispatch_fee_payment,
 							call: call.encode(),
 						}.encode(),
 					)
@@ -1010,6 +1021,18 @@ impl_runtime_apis! {
 						),
 					)
 				}
+
+				fn is_message_dispatched(nonce: bp_messages::MessageNonce) -> bool {
+					frame_system::Pallet::<Runtime>::events()
+						.into_iter()
+						.map(|event_record| event_record.event)
+						.any(|event| matches!(
+							event,
+							Event::pallet_bridge_dispatch(pallet_bridge_dispatch::Event::<Runtime, _>::MessageDispatched(
+								_, ([0, 0, 0, 0], nonce_from_event), _,
+							)) if nonce_from_event == nonce
+						))
+				}
 			}
 
 			add_benchmark!(
@@ -1105,6 +1128,7 @@ mod tests {
 			bp_rialto::DEFAULT_MESSAGE_DELIVERY_TX_WEIGHT,
 			bp_rialto::ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT,
 			bp_rialto::MAX_SINGLE_MESSAGE_DELIVERY_CONFIRMATION_TX_WEIGHT,
+			bp_rialto::PAY_INBOUND_DISPATCH_FEE_WEIGHT,
 		);
 
 		let max_incoming_message_proof_size = bp_millau::EXTRA_STORAGE_PROOF_SIZE.saturating_add(

bridges/bin/rialto/runtime/src/millau_messages.rs

@@ -58,6 +58,7 @@ pub type FromMillauEncodedCall = messages::target::FromBridgedChainEncodedMessag
 pub type FromMillauMessageDispatch = messages::target::FromBridgedChainMessageDispatch<
 	WithMillauMessageBridge,
 	crate::Runtime,
+	pallet_balances::Pallet<Runtime>,
 	pallet_bridge_dispatch::DefaultInstance,
 >;
 
@@ -172,6 +173,7 @@ impl messages::BridgedChainWithMessages for Millau {
 
 	fn estimate_delivery_transaction(
 		message_payload: &[u8],
+		include_pay_dispatch_fee_cost: bool,
 		message_dispatch_weight: Weight,
 	) -> MessageTransaction<Weight> {
 		let message_payload_len = u32::try_from(message_payload.len()).unwrap_or(u32::MAX);
@@ -182,6 +184,11 @@ impl messages::BridgedChainWithMessages for Millau {
 			dispatch_weight: extra_bytes_in_payload
 				.saturating_mul(bp_millau::ADDITIONAL_MESSAGE_BYTE_DELIVERY_WEIGHT)
 				.saturating_add(bp_millau::DEFAULT_MESSAGE_DELIVERY_TX_WEIGHT)
+				.saturating_sub(if include_pay_dispatch_fee_cost {
+					0
+				} else {
+					bp_millau::PAY_INBOUND_DISPATCH_FEE_WEIGHT
+				})
 				.saturating_add(message_dispatch_weight),
 			size: message_payload_len
 				.saturating_add(bp_rialto::EXTRA_STORAGE_PROOF_SIZE)
@@ -258,3 +265,87 @@ impl MessagesParameter for RialtoToMillauMessagesParameter {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use crate::{AccountId, Call, ExistentialDeposit, Runtime, SystemCall, SystemConfig, VERSION};
+	use bp_message_dispatch::CallOrigin;
+	use bp_messages::{
+		target_chain::{DispatchMessage, DispatchMessageData, MessageDispatch},
+		MessageKey,
+	};
+	use bp_runtime::{derive_account_id, messages::DispatchFeePayment, SourceAccount};
+	use bridge_runtime_common::messages::target::{FromBridgedChainEncodedMessageCall, FromBridgedChainMessagePayload};
+	use frame_support::{
+		traits::Currency,
+		weights::{GetDispatchInfo, WeightToFeePolynomial},
+	};
+	use sp_runtime::traits::Convert;
+
+	#[test]
+	fn transfer_happens_when_dispatch_fee_is_paid_at_target_chain() {
+		// this test actually belongs to the `bridge-runtime-common` crate, but there we have no
+		// mock runtime. Making another one there just for this test, given that both crates
+		// live n single repo is an overkill
+		let mut ext: sp_io::TestExternalities = SystemConfig::default().build_storage::<Runtime>().unwrap().into();
+		ext.execute_with(|| {
+			let bridge = MILLAU_CHAIN_ID;
+			let call: Call = SystemCall::remark(vec![]).into();
+			let dispatch_weight = call.get_dispatch_info().weight;
+			let dispatch_fee = <Runtime as pallet_transaction_payment::Config>::WeightToFee::calc(&dispatch_weight);
+			assert!(dispatch_fee > 0);
+
+			// create relayer account with minimal balance
+			let relayer_account: AccountId = [1u8; 32].into();
+			let initial_amount = ExistentialDeposit::get();
+			let _ = <pallet_balances::Pallet<Runtime> as Currency<AccountId>>::deposit_creating(
+				&relayer_account,
+				initial_amount,
+			);
+
+			// create dispatch account with minimal balance + dispatch fee
+			let dispatch_account = derive_account_id::<<Runtime as pallet_bridge_dispatch::Config>::SourceChainAccountId>(
+				bridge,
+				SourceAccount::Root,
+			);
+			let dispatch_account =
+				<Runtime as pallet_bridge_dispatch::Config>::AccountIdConverter::convert(dispatch_account);
+			let _ = <pallet_balances::Pallet<Runtime> as Currency<AccountId>>::deposit_creating(
+				&dispatch_account,
+				initial_amount + dispatch_fee,
+			);
+
+			// dispatch message with intention to pay dispatch fee at the target chain
+			FromMillauMessageDispatch::dispatch(
+				&relayer_account,
+				DispatchMessage {
+					key: MessageKey {
+						lane_id: Default::default(),
+						nonce: 0,
+					},
+					data: DispatchMessageData {
+						payload: Ok(FromBridgedChainMessagePayload::<WithMillauMessageBridge> {
+							spec_version: VERSION.spec_version,
+							weight: dispatch_weight,
+							origin: CallOrigin::SourceRoot,
+							dispatch_fee_payment: DispatchFeePayment::AtTargetChain,
+							call: FromBridgedChainEncodedMessageCall::new(call.encode()),
+						}),
+						fee: 1,
+					},
+				},
+			);
+
+			// ensure that fee has been transferred from dispatch to relayer account
+			assert_eq!(
+				<pallet_balances::Pallet<Runtime> as Currency<AccountId>>::free_balance(&relayer_account),
+				initial_amount + dispatch_fee,
+			);
+			assert_eq!(
+				<pallet_balances::Pallet<Runtime> as Currency<AccountId>>::free_balance(&dispatch_account),
+				initial_amount,
+			);
+		});
+	}
+}

bridges/bin/runtime-common/Cargo.toml

@@ -24,6 +24,7 @@ pallet-bridge-messages = { path = "../../modules/messages", default-features = f
 # Substrate dependencies
 
 frame-support = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
+pallet-transaction-payment = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
 sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
 sp-state-machine = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false, optional = true }
@@ -42,6 +43,7 @@ std = [
 	"pallet-bridge-dispatch/std",
 	"pallet-bridge-grandpa/std",
 	"pallet-bridge-messages/std",
+	"pallet-transaction-payment/std",
 	"sp-core/std",
 	"sp-runtime/std",
 	"sp-state-machine/std",

bridges/bin/runtime-common/README.md

@@ -102,7 +102,9 @@ This trait represents this chain from bridge point of view. Let's review every m
   have declared dispatch weight larger than 50% of the maximal bridged extrinsic weight.
 
 - `MessageBridge::estimate_delivery_transaction`: you will need to return estimated dispatch weight and
-  size of the delivery transaction that delivers a given message to the target chain.
+  size of the delivery transaction that delivers a given message to the target chain. The transaction
+  weight must or must not include the weight of pay-dispatch-fee operation, depending on the value
+  of `include_pay_dispatch_fee_cost` argument.
 
 - `MessageBridge::transaction_payment`: you'll need to return fee that the submitter
   must pay for given transaction on bridged chain. The best case is when you have the same conversion

bridges/bin/runtime-common/src/messages.rs

@@ -26,9 +26,16 @@ use bp_messages::{
 	target_chain::{DispatchMessage, MessageDispatch, ProvedLaneMessages, ProvedMessages},
 	InboundLaneData, LaneId, Message, MessageData, MessageKey, MessageNonce, OutboundLaneData,
 };
-use bp_runtime::{ChainId, Size, StorageProofChecker};
+use bp_runtime::{
+	messages::{DispatchFeePayment, MessageDispatchResult},
+	ChainId, Size, StorageProofChecker,
+};
 use codec::{Decode, Encode};
-use frame_support::{traits::Instance, weights::Weight, RuntimeDebug};
+use frame_support::{
+	traits::{Currency, ExistenceRequirement, Instance},
+	weights::{Weight, WeightToFeePolynomial},
+	RuntimeDebug,
+};
 use hash_db::Hasher;
 use sp_runtime::{
 	traits::{AtLeast32BitUnsigned, CheckedAdd, CheckedDiv, CheckedMul},
@@ -124,6 +131,7 @@ pub trait BridgedChainWithMessages: ChainWithMessages {
 	/// Estimate size and weight of single message delivery transaction at the Bridged chain.
 	fn estimate_delivery_transaction(
 		message_payload: &[u8],
+		include_pay_dispatch_fee_cost: bool,
 		message_dispatch_weight: WeightOf<Self>,
 	) -> MessageTransaction<WeightOf<Self>>;
 
@@ -326,8 +334,19 @@ pub mod source {
 		relayer_fee_percent: u32,
 	) -> Result<BalanceOf<ThisChain<B>>, &'static str> {
 		// the fee (in Bridged tokens) of all transactions that are made on the Bridged chain
-		let delivery_transaction =
-			BridgedChain::<B>::estimate_delivery_transaction(&payload.call, payload.weight.into());
+		//
+		// if we're going to pay dispatch fee at the target chain, then we don't include weight
+		// of the message dispatch in the delivery transaction cost
+		let pay_dispatch_fee_at_target_chain = payload.dispatch_fee_payment == DispatchFeePayment::AtTargetChain;
+		let delivery_transaction = BridgedChain::<B>::estimate_delivery_transaction(
+			&payload.call,
+			pay_dispatch_fee_at_target_chain,
+			if pay_dispatch_fee_at_target_chain {
+				0.into()
+			} else {
+				payload.weight.into()
+			},
+		);
 		let delivery_transaction_fee = BridgedChain::<B>::transaction_payment(delivery_transaction);
 
 		// the fee (in This tokens) of all transactions that are made on This chain
@@ -445,8 +464,18 @@ pub mod target {
 	/// vector length. Custom decode implementation here is exactly to deal with this.
 	#[derive(Decode, Encode, RuntimeDebug, PartialEq)]
 	pub struct FromBridgedChainEncodedMessageCall<B> {
-		pub(crate) encoded_call: Vec<u8>,
-		pub(crate) _marker: PhantomData<B>,
+		encoded_call: Vec<u8>,
+		_marker: PhantomData<B>,
+	}
+
+	impl<B: MessageBridge> FromBridgedChainEncodedMessageCall<B> {
+		/// Create encoded call.
+		pub fn new(encoded_call: Vec<u8>) -> Self {
+			FromBridgedChainEncodedMessageCall {
+				encoded_call,
+				_marker: PhantomData::default(),
+			}
+		}
 	}
 
 	impl<B: MessageBridge> From<FromBridgedChainEncodedMessageCall<B>> for Result<CallOf<ThisChain<B>>, ()> {
@@ -457,20 +486,28 @@ pub mod target {
 
 	/// Dispatching Bridged -> This chain messages.
 	#[derive(RuntimeDebug, Clone, Copy)]
-	pub struct FromBridgedChainMessageDispatch<B, ThisRuntime, ThisDispatchInstance> {
-		_marker: PhantomData<(B, ThisRuntime, ThisDispatchInstance)>,
+	pub struct FromBridgedChainMessageDispatch<B, ThisRuntime, ThisCurrency, ThisDispatchInstance> {
+		_marker: PhantomData<(B, ThisRuntime, ThisCurrency, ThisDispatchInstance)>,
 	}
 
-	impl<B: MessageBridge, ThisRuntime, ThisDispatchInstance>
-		MessageDispatch<<BridgedChain<B> as ChainWithMessages>::Balance>
-		for FromBridgedChainMessageDispatch<B, ThisRuntime, ThisDispatchInstance>
+	impl<B: MessageBridge, ThisRuntime, ThisCurrency, ThisDispatchInstance>
+		MessageDispatch<AccountIdOf<ThisChain<B>>, BalanceOf<BridgedChain<B>>>
+		for FromBridgedChainMessageDispatch<B, ThisRuntime, ThisCurrency, ThisDispatchInstance>
 	where
 		ThisDispatchInstance: frame_support::traits::Instance,
-		ThisRuntime: pallet_bridge_dispatch::Config<ThisDispatchInstance, MessageId = (LaneId, MessageNonce)>,
-		<ThisRuntime as pallet_bridge_dispatch::Config<ThisDispatchInstance>>::Event:
-			From<pallet_bridge_dispatch::RawEvent<(LaneId, MessageNonce), ThisDispatchInstance>>,
-		pallet_bridge_dispatch::Pallet<ThisRuntime, ThisDispatchInstance>:
-			bp_message_dispatch::MessageDispatch<(LaneId, MessageNonce), Message = FromBridgedChainMessagePayload<B>>,
+		ThisRuntime: pallet_bridge_dispatch::Config<ThisDispatchInstance, MessageId = (LaneId, MessageNonce)>
+			+ pallet_transaction_payment::Config,
+		<ThisRuntime as pallet_transaction_payment::Config>::OnChargeTransaction:
+			pallet_transaction_payment::OnChargeTransaction<ThisRuntime, Balance = BalanceOf<ThisChain<B>>>,
+		ThisCurrency: Currency<AccountIdOf<ThisChain<B>>, Balance = BalanceOf<ThisChain<B>>>,
+		<ThisRuntime as pallet_bridge_dispatch::Config<ThisDispatchInstance>>::Event: From<
+			pallet_bridge_dispatch::RawEvent<(LaneId, MessageNonce), AccountIdOf<ThisChain<B>>, ThisDispatchInstance>,
+		>,
+		pallet_bridge_dispatch::Pallet<ThisRuntime, ThisDispatchInstance>: bp_message_dispatch::MessageDispatch<
+			AccountIdOf<ThisChain<B>>,
+			(LaneId, MessageNonce),
+			Message = FromBridgedChainMessagePayload<B>,
+		>,
 	{
 		type DispatchPayload = FromBridgedChainMessagePayload<B>;
 
@@ -480,14 +517,26 @@ pub mod target {
 			message.data.payload.as_ref().map(|payload| payload.weight).unwrap_or(0)
 		}
 
-		fn dispatch(message: DispatchMessage<Self::DispatchPayload, BalanceOf<BridgedChain<B>>>) {
+		fn dispatch(
+			relayer_account: &AccountIdOf<ThisChain<B>>,
+			message: DispatchMessage<Self::DispatchPayload, BalanceOf<BridgedChain<B>>>,
+		) -> MessageDispatchResult {
 			let message_id = (message.key.lane_id, message.key.nonce);
 			pallet_bridge_dispatch::Pallet::<ThisRuntime, ThisDispatchInstance>::dispatch(
 				B::BridgedChain::ID,
 				B::ThisChain::ID,
 				message_id,
 				message.data.payload.map_err(drop),
-			);
+				|dispatch_origin, dispatch_weight| {
+					ThisCurrency::transfer(
+						dispatch_origin,
+						relayer_account,
+						ThisRuntime::WeightToFee::calc(&dispatch_weight),
+						ExistenceRequirement::AllowDeath,
+					)
+					.map_err(drop)
+				},
+			)
 		}
 	}
 
@@ -854,6 +903,7 @@ mod tests {
 
 		fn estimate_delivery_transaction(
 			_message_payload: &[u8],
+			_include_pay_dispatch_fee_cost: bool,
 			_message_dispatch_weight: WeightOf<Self>,
 		) -> MessageTransaction<WeightOf<Self>> {
 			unreachable!()
@@ -911,6 +961,7 @@ mod tests {
 
 		fn estimate_delivery_transaction(
 			_message_payload: &[u8],
+			_include_pay_dispatch_fee_cost: bool,
 			message_dispatch_weight: WeightOf<Self>,
 		) -> MessageTransaction<WeightOf<Self>> {
 			MessageTransaction {
@@ -935,6 +986,7 @@ mod tests {
 			spec_version: 1,
 			weight: 100,
 			origin: bp_message_dispatch::CallOrigin::SourceRoot,
+			dispatch_fee_payment: DispatchFeePayment::AtTargetChain,
 			call: ThisChainCall::Transfer.encode(),
 		}
 		.encode();
@@ -949,10 +1001,10 @@ mod tests {
 				spec_version: 1,
 				weight: 100,
 				origin: bp_message_dispatch::CallOrigin::SourceRoot,
-				call: target::FromBridgedChainEncodedMessageCall::<OnThisChainBridge> {
-					encoded_call: ThisChainCall::Transfer.encode(),
-					_marker: PhantomData::default(),
-				},
+				dispatch_fee_payment: DispatchFeePayment::AtTargetChain,
+				call: target::FromBridgedChainEncodedMessageCall::<OnThisChainBridge>::new(
+					ThisChainCall::Transfer.encode(),
+				),
 			}
 		);
 		assert_eq!(Ok(ThisChainCall::Transfer), message_on_this_chain.call.into());
@@ -966,6 +1018,7 @@ mod tests {
 			spec_version: 1,
 			weight: 100,
 			origin: bp_message_dispatch::CallOrigin::SourceRoot,
+			dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 			call: vec![42],
 		}
 	}
@@ -986,6 +1039,21 @@ mod tests {
 			Ok(ThisChainBalance(EXPECTED_MINIMAL_FEE)),
 		);
 
+		// let's check if estimation is less than hardcoded, if dispatch is paid at target chain
+		let mut payload_with_pay_on_target = regular_outbound_message_payload();
+		payload_with_pay_on_target.dispatch_fee_payment = DispatchFeePayment::AtTargetChain;
+		let fee_at_source = source::estimate_message_dispatch_and_delivery_fee::<OnThisChainBridge>(
+			&payload_with_pay_on_target,
+			OnThisChainBridge::RELAYER_FEE_PERCENT,
+		)
+		.expect("estimate_message_dispatch_and_delivery_fee failed for pay-at-target-chain message");
+		assert!(
+			fee_at_source < EXPECTED_MINIMAL_FEE.into(),
+			"Computed fee {:?} without prepaid dispatch must be less than the fee with prepaid dispatch {}",
+			fee_at_source,
+			EXPECTED_MINIMAL_FEE,
+		);
+
 		// and now check that the verifier checks the fee
 		assert_eq!(
 			source::FromThisChainMessageVerifier::<OnThisChainBridge>::verify_message(
@@ -1016,6 +1084,7 @@ mod tests {
 			spec_version: 1,
 			weight: 100,
 			origin: bp_message_dispatch::CallOrigin::SourceRoot,
+			dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 			call: vec![42],
 		};
 
@@ -1059,6 +1128,7 @@ mod tests {
 			spec_version: 1,
 			weight: 100,
 			origin: bp_message_dispatch::CallOrigin::SourceAccount(ThisChainAccountId(1)),
+			dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 			call: vec![42],
 		};
 
@@ -1126,6 +1196,7 @@ mod tests {
 				spec_version: 1,
 				weight: 5,
 				origin: bp_message_dispatch::CallOrigin::SourceRoot,
+				dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 				call: vec![1, 2, 3, 4, 5, 6],
 			},)
 			.is_err()
@@ -1141,6 +1212,7 @@ mod tests {
 				spec_version: 1,
 				weight: BRIDGED_CHAIN_MAX_EXTRINSIC_WEIGHT + 1,
 				origin: bp_message_dispatch::CallOrigin::SourceRoot,
+				dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 				call: vec![1, 2, 3, 4, 5, 6],
 			},)
 			.is_err()
@@ -1156,6 +1228,7 @@ mod tests {
 				spec_version: 1,
 				weight: BRIDGED_CHAIN_MAX_EXTRINSIC_WEIGHT,
 				origin: bp_message_dispatch::CallOrigin::SourceRoot,
+				dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 				call: vec![0; source::maximal_message_size::<OnThisChainBridge>() as usize + 1],
 			},)
 			.is_err()
@@ -1171,6 +1244,7 @@ mod tests {
 				spec_version: 1,
 				weight: BRIDGED_CHAIN_MAX_EXTRINSIC_WEIGHT,
 				origin: bp_message_dispatch::CallOrigin::SourceRoot,
+				dispatch_fee_payment: DispatchFeePayment::AtSourceChain,
 				call: vec![0; source::maximal_message_size::<OnThisChainBridge>() as _],
 			},),
 			Ok(()),

bridges/bin/runtime-common/src/messages_benchmarking.rs

@@ -25,6 +25,7 @@ use crate::messages::{
 };
 
 use bp_messages::{LaneId, MessageData, MessageKey, MessagePayload};
+use bp_runtime::ChainId;
 use codec::Encode;
 use ed25519_dalek::{PublicKey, SecretKey, Signer, KEYPAIR_LENGTH, SECRET_KEY_LENGTH};
 use frame_support::weights::Weight;
@@ -37,7 +38,13 @@ use sp_trie::{record_all_keys, trie_types::TrieDBMut, Layout, MemoryDB, Recorder
 /// Generate ed25519 signature to be used in `pallet_brdige_call_dispatch::CallOrigin::TargetAccount`.
 ///
 /// Returns public key of the signer and the signature itself.
-pub fn ed25519_sign(target_call: &impl Encode, source_account_id: &impl Encode) -> ([u8; 32], [u8; 64]) {
+pub fn ed25519_sign(
+	target_call: &impl Encode,
+	source_account_id: &impl Encode,
+	target_spec_version: u32,
+	source_chain_id: ChainId,
+	target_chain_id: ChainId,
+) -> ([u8; 32], [u8; 64]) {
 	// key from the repo example (https://docs.rs/ed25519-dalek/1.0.1/ed25519_dalek/struct.SecretKey.html)
 	let target_secret = SecretKey::from_bytes(&[
 		157, 097, 177, 157, 239, 253, 090, 096, 186, 132, 074, 244, 146, 236, 044, 196, 068, 073, 197, 105, 123, 050,
@@ -51,9 +58,13 @@ pub fn ed25519_sign(target_call: &impl Encode, source_account_id: &impl Encode)
 	target_pair_bytes[SECRET_KEY_LENGTH..].copy_from_slice(&target_public.to_bytes());
 	let target_pair = ed25519_dalek::Keypair::from_bytes(&target_pair_bytes).expect("hardcoded pair is valid");
 
-	let mut signature_message = Vec::new();
-	target_call.encode_to(&mut signature_message);
-	source_account_id.encode_to(&mut signature_message);
+	let signature_message = pallet_bridge_dispatch::account_ownership_digest(
+		target_call,
+		source_account_id,
+		target_spec_version,
+		source_chain_id,
+		target_chain_id,
+	);
 	let target_origin_signature = target_pair
 		.try_sign(&signature_message)
 		.expect("Ed25519 try_sign should not fail in benchmarks");