feat(api): add query_xcm_delivery_fees

polkadot/node/service/src/fake_runtime_api.rs

@@ -41,7 +41,7 @@ use sp_runtime::{
 use sp_version::RuntimeVersion;
 use sp_weights::Weight;
 use std::collections::BTreeMap;
-use xcm::{VersionedAssetId, VersionedXcm};
+use xcm::{latest::Assets, VersionedAssetId, VersionedLocation, VersionedXcm};
 sp_api::decl_runtime_apis! {
 	/// This runtime API is only implemented for the test runtime!
 	pub trait GetLastTimestamp {
@@ -412,5 +412,9 @@ sp_api::impl_runtime_apis! {
 		fn query_xcm_weight(_: VersionedXcm<RuntimeCall>) -> Result<Weight, xcm_payment_runtime_api::Error> {
 			unimplemented!()
 		}
+
+		fn query_xcm_delivery_fees(_: VersionedLocation, _: VersionedXcm<()>) -> Result<Assets, xcm_payment_runtime_api::Error> {
+			unimplemented!()
+		}
 	}
 }

polkadot/runtime/rococo/src/lib.rs

@@ -39,6 +39,7 @@ use runtime_common::{
 	},
 	paras_registrar, paras_sudo_wrapper, prod_or_fast, slots,
 	traits::Leaser,
+	xcm_sender::PriceForMessageDelivery as _,
 	BlockHashCount, BlockLength, SlowAdjustingFeeUpdate,
 };
 use scale_info::TypeInfo;
@@ -1830,6 +1831,22 @@ sp_api::impl_runtime_apis! {
 			<xcm_config::XcmConfig as xcm_executor::Config>::Weigher::weight(&mut message)
 				.map_err(|_| XcmPaymentApiError::WeightNotComputable)
 		}
+
+		fn query_xcm_delivery_fees(destination: VersionedLocation, message: VersionedXcm<()>) -> Result<Assets, XcmPaymentApiError> {
+			let destination = destination
+				.into_version(4)
+				.map_err(|_| XcmPaymentApiError::VersionedConversionFailed)?;
+			let VersionedLocation::V4(Location { parents: 0, interior: junctions}) = destination else {
+				return Err(XcmPaymentApiError::Unroutable);
+			};
+			let (Junctions::Here, Some(Junction::Parachain(para_id))) = junctions.split_first() else {
+				return Err(XcmPaymentApiError::Unroutable);
+			};
+			let message = message
+				.try_into()
+				.map_err(|_| XcmPaymentApiError::VersionedConversionFailed)?;
+			Ok(xcm_config::PriceForChildParachainDelivery::price_for_delivery(para_id.into(), &message))
+		}
 	}
 
 	impl sp_api::Metadata<Block> for Runtime {

polkadot/runtime/westend/src/lib.rs

@@ -101,7 +101,7 @@ use sp_std::{collections::btree_map::BTreeMap, prelude::*};
 use sp_version::NativeVersion;
 use sp_version::RuntimeVersion;
 use xcm::{
-	latest::{InteriorLocation, Junction, Junction::PalletInstance},
+	latest::{Assets, InteriorLocation, Junction, Junction::PalletInstance},
 	IntoVersion, VersionedAssetId, VersionedLocation, VersionedXcm,
 };
 use xcm_builder::PayOverXcm;
@@ -2287,6 +2287,22 @@ sp_api::impl_runtime_apis! {
 			<xcm_config::XcmConfig as xcm_executor::Config>::Weigher::weight(&mut message)
 				.map_err(|_| XcmPaymentApiError::WeightNotComputable)
 		}
+
+		fn query_xcm_delivery_fees(destination: VersionedLocation, message: VersionedXcm<()>) -> Result<Assets, XcmPaymentApiError> {
+			let destination = destination
+				.into_version(4)
+				.map_err(|_| XcmPaymentApiError::VersionedConversionFailed)?;
+			let VersionedLocation::V4(Location { parents: 0, interior: junctions}) = destination else {
+				return Err(XcmPaymentApiError::Unroutable);
+			};
+			let (Junctions::Here, Some(Junction::Parachain(para_id))) = junctions.split_first() else {
+				return Err(XcmPaymentApiError::Unroutable);
+			};
+			let message = message
+				.try_into()
+				.map_err(|_| XcmPaymentApiError::VersionedConversionFailed)?;
+			Ok(xcm_config::PriceForChildParachainDelivery::price_for_delivery(para_id.into(), &message))
+		}
 	}
 
 	impl pallet_nomination_pools_runtime_api::NominationPoolsApi<

polkadot/xcm/xcm-builder/xcm-payment-runtime-api/src/lib.rs

@@ -22,7 +22,7 @@ use codec::{Codec, Decode, Encode};
 use frame_support::pallet_prelude::TypeInfo;
 use sp_std::vec::Vec;
 use sp_weights::Weight;
-use xcm::{Version, VersionedAssetId, VersionedXcm};
+use xcm::{latest::Assets, Version, VersionedAssetId, VersionedLocation, VersionedXcm};
 
 sp_api::decl_runtime_apis! {
 	/// A trait of XCM payment API.
@@ -60,6 +60,14 @@ sp_api::decl_runtime_apis! {
 		/// * `weight`: convertible `Weight`.
 		/// * `asset`: `VersionedAssetId`.
 		fn query_weight_to_asset_fee(weight: Weight, asset: VersionedAssetId) -> Result<u128, Error>;
+
+		/// Returns a fee needed to deliver a XCM.
+		///
+		/// # Arguments
+		///
+		/// * `destination`: `VersionedLocation`.
+		/// * `message`: `VersionedXcm`.
+		fn query_xcm_delivery_fees(destination: VersionedLocation, message: VersionedXcm<()>) -> Result<Assets, Error>;
 	}
 }
 
@@ -79,4 +87,7 @@ pub enum Error {
 	/// The given asset is not handled(as a fee payment).
 	#[codec(index = 4)]
 	AssetNotFound,
+	/// Destination is known to be unroutable.
+	#[codec(index = 5)]
+	Unroutable,
 }