WIP: Allow dynamic fees setup for xcm-bridge

bridges/modules/xcm-bridge-router/Cargo.toml

@@ -28,6 +28,7 @@ sp-runtime = { workspace = true }
 sp-std = { workspace = true }
 
 # Polkadot Dependencies
+polkadot-runtime-common = { workspace = true }
 xcm = { workspace = true }
 xcm-builder = { workspace = true }
 
@@ -45,6 +46,7 @@ std = [
 	"frame-support/std",
 	"frame-system/std",
 	"log/std",
+	"polkadot-runtime-common/std",
 	"scale-info/std",
 	"sp-core/std",
 	"sp-runtime/std",
@@ -56,12 +58,14 @@ runtime-benchmarks = [
 	"frame-benchmarking/runtime-benchmarks",
 	"frame-support/runtime-benchmarks",
 	"frame-system/runtime-benchmarks",
+	"polkadot-runtime-common/runtime-benchmarks",
 	"sp-runtime/runtime-benchmarks",
 	"xcm-builder/runtime-benchmarks",
 	"xcm/runtime-benchmarks",
 ]
 try-runtime = [
 	"frame-support/try-runtime",
 	"frame-system/try-runtime",
+	"polkadot-runtime-common/try-runtime",
 	"sp-runtime/try-runtime",
 ]

bridges/modules/xcm-bridge-router/src/impls.rs

@@ -69,6 +69,39 @@ impl<T: Config<I>, I: 'static> bp_xcm_bridge::LocalXcmChannelManager<BridgeIdOf<
 	}
 }
 
+/// Calculates the price for message delivery across bridges with base price, dynamic fees
+/// and size-based pricing.
+pub struct GetPriceForBridge<T, I, BasePrice>(PhantomData<(T, I, BasePrice)>);
+impl<T: Config<I>, I: 'static, BasePrice: Get<Assets>>
+	polkadot_runtime_common::xcm_sender::PriceForMessageDelivery
+	for GetPriceForBridge<T, I, BasePrice>
+{
+	type Id = BridgeIdOf<T, I>;
+
+	fn price_for_delivery(bridge_id: Self::Id, message: &Xcm<()>) -> Assets {
+		// Get a base price.
+		let mut price = BasePrice::get();
+
+		// Apply message-size-based fees (if configured).
+		if let Some(message_size_fees) =
+			Pallet::<T, I>::calculate_message_size_fee(|| message.encoded_size() as _)
+		{
+			price.push(message_size_fees);
+		}
+
+		// Apply dynamic congestion fees based on bridge state (if needed).
+		if let Some(bridge_state) = Bridges::<T, I>::get(bridge_id) {
+			let mut dynamic_fees = price.into_inner();
+			for fee in dynamic_fees.iter_mut() {
+				Pallet::<T, I>::apply_dynamic_fee_factor(&bridge_state, fee);
+			}
+			price = Assets::from(dynamic_fees);
+		}
+
+		price
+	}
+}
+
 /// Adapter implementation for [`ExporterFor`] that allows exporting message size fee and/or dynamic
 /// fees based on the `BridgeId` resolved by the `T::BridgeIdResolver` resolver, if and only if the
 /// `E` exporter supports bridging. This adapter acts as an [`ExporterFor`], for example, for the

bridges/modules/xcm-bridge/Cargo.toml

@@ -30,6 +30,7 @@ sp-runtime = { workspace = true }
 sp-std = { workspace = true }
 
 # Polkadot Dependencies
+polkadot-runtime-common = { workspace = true }
 xcm = { workspace = true }
 xcm-builder = { workspace = true }
 xcm-executor = { workspace = true }
@@ -60,6 +61,7 @@ std = [
 	"pallet-bridge-messages/std",
 	"pallet-xcm-bridge-router/std",
 	"polkadot-parachain-primitives/std",
+	"polkadot-runtime-common/std",
 	"scale-info/std",
 	"sp-core/std",
 	"sp-io/std",
@@ -77,6 +79,7 @@ runtime-benchmarks = [
 	"pallet-bridge-messages/runtime-benchmarks",
 	"pallet-xcm-bridge-router/runtime-benchmarks",
 	"polkadot-parachain-primitives/runtime-benchmarks",
+	"polkadot-runtime-common/runtime-benchmarks",
 	"sp-runtime/runtime-benchmarks",
 	"xcm-builder/runtime-benchmarks",
 	"xcm-executor/runtime-benchmarks",
@@ -88,5 +91,6 @@ try-runtime = [
 	"pallet-balances/try-runtime",
 	"pallet-bridge-messages/try-runtime",
 	"pallet-xcm-bridge-router/try-runtime",
+	"polkadot-runtime-common/try-runtime",
 	"sp-runtime/try-runtime",
 ]

bridges/modules/xcm-bridge/src/exporter.rs

@@ -33,16 +33,19 @@ use frame_support::{ensure, traits::Get};
 use pallet_bridge_messages::{
 	Config as BridgeMessagesConfig, Error, Pallet as BridgeMessagesPallet,
 };
+use polkadot_runtime_common::xcm_sender::PriceForMessageDelivery;
 use xcm::prelude::*;
 use xcm_builder::{HaulBlob, HaulBlobError, HaulBlobExporter};
 use xcm_executor::traits::ExportXcm;
 
 /// An easy way to access `HaulBlobExporter`.
+///
+/// Note: Set no price for `HaulBlobExporter`, because `ExportXcm for Pallet` handles the fees.
 pub type PalletAsHaulBlobExporter<T, I> = HaulBlobExporter<
 	DummyHaulBlob,
 	<T as Config<I>>::BridgedNetwork,
 	<T as Config<I>>::DestinationVersion,
-	<T as Config<I>>::MessageExportPrice,
+	(),
 >;
 /// An easy way to access associated messages pallet.
 type MessagesPallet<T, I> = BridgeMessagesPallet<T, <T as Config<I>>::BridgeMessagesPalletInstance>;
@@ -133,17 +136,29 @@ where
 			SendError::NotApplicable
 		})?;
 
-		// check if we are able to route the message. We use existing `HaulBlobExporter` for that.
-		// It will make all required changes and will encode message properly, so that the
-		// `DispatchBlob` at the bridged bridge hub will be able to decode it
-		let ((blob, id), price) = PalletAsHaulBlobExporter::<T, I>::validate(
+		// Get the potential price for a message over the bridge.
+		let price_for_delivery = message.as_ref().map(|msg| {
+			T::MessageExportPrice::price_for_delivery(locations.bridge_id().clone(), msg)
+		});
+
+		// check if we are able to route the message. We use the existing ` HaulBlobExporter ` for that.
+		// It will make all required changes and will encode a message properly, so that the
+		// `DispatchBlob` at the bridged xcm-bridge will be able to decode it.
+		let ((blob, id), mut price) = PalletAsHaulBlobExporter::<T, I>::validate(
 			network,
 			channel,
 			universal_source,
 			destination,
 			message,
 		)?;
 
+		// Add `price_for_delivery` to the `price`.
+		if let Some(delivery_prices) = price_for_delivery {
+			for dp in delivery_prices.into_inner() {
+				price.push(dp);
+			}
+		}
+
 		// Here, we know that the message is relevant to this pallet instance, so let's check for
 		// congestion defense.
 		if bridge.state == BridgeState::HardSuspended {

bridges/modules/xcm-bridge/src/lib.rs

@@ -153,6 +153,7 @@ use bp_xcm_bridge::{
 use frame_support::{traits::fungible::MutateHold, DefaultNoBound};
 use frame_system::Config as SystemConfig;
 use pallet_bridge_messages::{Config as BridgeMessagesConfig, LanesManagerError};
+use polkadot_runtime_common::xcm_sender::PriceForMessageDelivery;
 use sp_std::{boxed::Box, vec::Vec};
 use xcm::prelude::*;
 use xcm_builder::DispatchBlob;
@@ -211,22 +212,22 @@ pub mod pallet {
 		// TODO: https://github.com/paritytech/parity-bridges-common/issues/1666 remove `ChainId` and
 		// replace it with the `NetworkId` - then we'll be able to use
 		// `T as pallet_bridge_messages::Config<T::BridgeMessagesPalletInstance>::BridgedChain::NetworkId`
-		/// Bridged network as relative location of bridged `GlobalConsensus`.
+		/// Bridged network as a relative location of bridged `GlobalConsensus`.
 		#[pallet::constant]
 		type BridgedNetwork: Get<Location>;
 		/// Associated messages pallet instance that bridges us with the
 		/// `BridgedNetworkId` consensus.
 		type BridgeMessagesPalletInstance: 'static;
 
-		/// Price of single message export to the bridged consensus (`Self::BridgedNetwork`).
-		type MessageExportPrice: Get<Assets>;
+		/// Price of a single message export to the bridged consensus (`Self::BridgedNetwork`).
+		type MessageExportPrice: PriceForMessageDelivery<Id = BridgeId>;
 		/// Checks the XCM version for the destination.
 		type DestinationVersion: GetVersion;
 
 		/// The origin that is allowed to call privileged operations on the pallet, e.g. open/close
 		/// bridge for locations.
 		type ForceOrigin: EnsureOrigin<<Self as SystemConfig>::RuntimeOrigin>;
-		/// A set of XCM locations within local consensus system that are allowed to open
+		/// A set of XCM locations within a local consensus system that are allowed to open
 		/// bridges with remote destinations.
 		type OpenBridgeOrigin: EnsureOrigin<
 			<Self as SystemConfig>::RuntimeOrigin,

bridges/modules/xcm-bridge/src/mock.rs

@@ -35,6 +35,7 @@ use pallet_xcm_bridge::congestion::{
 	UpdateBridgeStatusXcmChannelManager,
 };
 use polkadot_parachain_primitives::primitives::Sibling;
+use polkadot_runtime_common::xcm_sender::NoPriceForMessageDelivery;
 use sp_core::H256;
 use sp_runtime::{
 	testing::Header as SubstrateHeader,
@@ -217,7 +218,7 @@ impl pallet_xcm_bridge::Config for TestRuntime {
 	type BridgedNetwork = BridgedRelayNetworkLocation;
 	type BridgeMessagesPalletInstance = ();
 
-	type MessageExportPrice = ();
+	type MessageExportPrice = NoPriceForMessageDelivery<BridgeId>;
 	type DestinationVersion = AlwaysLatest;
 
 	type ForceOrigin = EnsureNever<()>;