Rococo Parachain XCM Adjustments

polkadot-parachains/parachains-common/Cargo.toml

@@ -11,6 +11,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 [dependencies]
 # External dependencies
 codec = { package = "parity-scale-codec", version = "2.3.0", features = ["derive"], default-features = false }
+log = { version = "0.4.14", default-features = false }
 scale-info = { version = "1.0.0", default-features = false, features = ["derive"] }
 
 # Substrate dependencies

polkadot-parachains/parachains-common/src/impls.rs

@@ -98,14 +98,33 @@ where
 	}
 }
 
+/// Tests `loc` whether it starts with `prefix`.
+/// Similar to `MultiLocation::match_and_split` but allows arbitrary suffixes (instead of just one
+/// junction).
+// TODO: Replace with version implemented on MultiLocation here:
+// https://github.com/paritytech/polkadot/pull/4827
+fn matches_prefix(prefix: &MultiLocation, loc: &MultiLocation) -> bool {
+	prefix.parent_count() == loc.parent_count() &&
+		loc.len() >= prefix.len() &&
+		prefix
+			.interior()
+			.iter()
+			.zip(loc.interior().iter())
+			.all(|(prefix_junction, junction)| prefix_junction == junction)
+}
+
 /// Asset filter that allows all assets from a certain location.
 pub struct AssetsFrom<T>(PhantomData<T>);
 impl<T: Get<MultiLocation>> FilterAssetLocation for AssetsFrom<T> {
 	fn filter_asset_location(asset: &MultiAsset, origin: &MultiLocation) -> bool {
-		let loc = T::get();
-		&loc == origin &&
-			matches!(asset, MultiAsset { id: AssetId::Concrete(asset_loc), fun: Fungible(_a) }
-			if asset_loc.match_and_split(&loc).is_some())
+		let prefix = T::get();
+		log::trace!(target: "xcm::AssetsFrom", "prefix: {:?}, origin: {:?}", prefix, origin);
+		&prefix == origin &&
+			match asset {
+				MultiAsset { id: AssetId::Concrete(asset_loc), fun: Fungible(_a) } =>
+					matches_prefix(&prefix, asset_loc),
+				_ => false,
+			}
 	}
 }
 
@@ -261,22 +280,81 @@ mod tests {
 	}
 
 	#[test]
-	fn assets_from_filters_correctly() {
+	fn test_matches_prefix_works() {
+		let prefix = MultiLocation::new(1, X1(Parachain(1234)));
+		let loc = MultiLocation::new(1, X2(Parachain(1234), GeneralIndex(5)));
+		assert!(matches_prefix(&prefix, &loc));
+		let failing = MultiLocation::new(1, Here);
+		assert!(!matches_prefix(&prefix, &failing));
+	}
+
+	mod assets_from {
+		use super::*;
+
 		parameter_types! {
 			pub SomeSiblingParachain: MultiLocation = MultiLocation::new(1, X1(Parachain(1234)));
 		}
 
-		let asset_location = SomeSiblingParachain::get()
-			.clone()
-			.pushed_with_interior(GeneralIndex(42))
-			.expect("multilocation will only have 2 junctions; qed");
-		let asset = MultiAsset { id: Concrete(asset_location), fun: 1_000_000.into() };
-		assert!(
-			AssetsFrom::<SomeSiblingParachain>::filter_asset_location(
-				&asset,
-				&SomeSiblingParachain::get()
-			),
-			"AssetsFrom should allow assets from any of its interior locations"
-		);
+		#[test]
+		fn accepts_native_asset() {
+			let asset_location = SomeSiblingParachain::get();
+			let asset = MultiAsset { id: Concrete(asset_location), fun: 1_000_000.into() };
+			assert!(
+				AssetsFrom::<SomeSiblingParachain>::filter_asset_location(
+					&asset,
+					&SomeSiblingParachain::get()
+				),
+				"AssetsFrom should allow the native asset"
+			);
+		}
+
+		#[test]
+		fn filters_correctly() {
+			let asset_location = SomeSiblingParachain::get()
+				.clone()
+				.pushed_with_interior(GeneralIndex(42))
+				.expect("multilocation will only have 2 junctions; qed");
+			let asset = MultiAsset { id: Concrete(asset_location), fun: 1_000_000.into() };
+			assert!(
+				AssetsFrom::<SomeSiblingParachain>::filter_asset_location(
+					&asset,
+					&SomeSiblingParachain::get()
+				),
+				"AssetsFrom should allow assets from any of its interior locations"
+			);
+		}
+
+		#[test]
+		fn accepts_long_suffix() {
+			// make sure assets can have more than one junction inside the prefix location
+			let asset_location = SomeSiblingParachain::get()
+				.clone()
+				.pushed_with_interior(PalletInstance(50))
+				.unwrap()
+				.pushed_with_interior(GeneralIndex(42))
+				.expect("multilocation will only have 3 junctions; qed");
+			let asset = MultiAsset { id: Concrete(asset_location), fun: 1_000_000.into() };
+			assert!(
+				AssetsFrom::<SomeSiblingParachain>::filter_asset_location(
+					&asset,
+					&SomeSiblingParachain::get()
+				),
+				"AssetsFrom should allow assets from any of its interior locations"
+			);
+		}
+
+		#[test]
+		fn rejects_short_location() {
+			let asset_location = MultiLocation::parent();
+			// make sure assets can have more than one junction inside the prefix location
+			let asset = MultiAsset { id: Concrete(asset_location), fun: 1_000_000.into() };
+			assert!(
+				!AssetsFrom::<SomeSiblingParachain>::filter_asset_location(
+					&asset,
+					&SomeSiblingParachain::get()
+				),
+				"AssetsFrom should filter assets not from the origin"
+			);
+		}
 	}
 }

polkadot-parachains/rococo-parachain/src/lib.rs

@@ -71,8 +71,8 @@ use pallet_xcm::{EnsureXcm, IsMajorityOfBody, XcmPassthrough};
 use polkadot_parachain::primitives::Sibling;
 use xcm::latest::prelude::*;
 use xcm_builder::{
-	AccountId32Aliases, AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, CurrencyAdapter,
-	EnsureXcmOrigin, FixedWeightBounds, IsConcrete, LocationInverter, NativeAsset,
+	AccountId32Aliases, AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, Case,
+	CurrencyAdapter, EnsureXcmOrigin, FixedWeightBounds, IsConcrete, LocationInverter, NativeAsset,
 	ParentAsSuperuser, ParentIsPreset, RelayChainAsNative, SiblingParachainAsNative,
 	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, TakeWeightCredit, UsingComponents,
@@ -391,9 +391,13 @@ parameter_types! {
 	// Statemint's Assets pallet index
 	pub StatemintAssetsPalletLocation: MultiLocation =
 		MultiLocation::new(1, X2(Parachain(1000), PalletInstance(50)));
+	pub KsmFilter: MultiAssetFilter = MultiAssetFilter::Wild(WildMultiAsset::AllOf{ id: (1, Here).into(), fun: WildFungibility::Fungible });
+	pub KsmFromStatemint: (MultiAssetFilter, MultiLocation) = (
+		KsmFilter::get(), StatemintLocation::get()
+	);
 }
 
-pub type Reserves = (NativeAsset, AssetsFrom<StatemintLocation>);
+pub type Reserves = (NativeAsset, AssetsFrom<StatemintLocation>, Case<KsmFromStatemint>);
 
 pub struct XcmConfig;
 impl Config for XcmConfig {