Fix barrier (#1076)

runtime/bifrost-kusama/src/xcm_config.rs

@@ -21,7 +21,7 @@ use bifrost_asset_registry::{AssetIdMaps, FixedRateOfAsset};
 use codec::{Decode, Encode};
 pub use cumulus_primitives_core::ParaId;
 use frame_support::{
-	parameter_types,
+	ensure, parameter_types,
 	sp_runtime::traits::{CheckedConversion, Convert},
 	traits::Get,
 };
@@ -34,7 +34,6 @@ pub use xcm_builder::{
 	FixedWeightBounds, IsConcrete, ParentAsSuperuser, ParentIsPreset, RelayChainAsNative,
 	SiblingParachainAsNative, SiblingParachainConvertsVia, SignedAccountId32AsNative,
 	SignedToAccountId32, SovereignSignedViaLocation, TakeRevenue, TakeWeightCredit,
-	WithComputedOrigin,
 };
 use xcm_executor::traits::{MatchesFungible, ShouldExecute};
 pub use xcm_interface::traits::{parachains, XcmBaseWeight};
@@ -255,6 +254,7 @@ pub type LocationToAccountId = (
 	SiblingParachainConvertsVia<Sibling, AccountId>,
 	// Straight up local `AccountId32` origins just alias directly to `AccountId`.
 	AccountId32Aliases<RelayNetwork, AccountId>,
+	// TODO: Generate remote accounts according to polkadot standards
 	// Derives a private `Account32` by hashing `("multiloc", received multilocation)`
 	Account32Hash<RelayNetwork, AccountId>,
 );
@@ -296,6 +296,63 @@ match_types! {
 	};
 }
 
+/// Barrier allowing a top level paid message with DescendOrigin instruction
+pub const DEFAULT_PROOF_SIZE: u64 = 64 * 1024;
+pub const DEFAULT_REF_TIMR: u64 = 10_000_000_000;
+pub struct AllowTopLevelPaidExecutionDescendOriginFirst<T>(PhantomData<T>);
+impl<T: Contains<MultiLocation>> ShouldExecute for AllowTopLevelPaidExecutionDescendOriginFirst<T> {
+	fn should_execute<Call>(
+		origin: &MultiLocation,
+		message: &mut [Instruction<Call>],
+		max_weight: Weight,
+		_weight_credit: &mut Weight,
+	) -> Result<(), ProcessMessageError> {
+		log::trace!(
+			target: "xcm::barriers",
+			"AllowTopLevelPaidExecutionDescendOriginFirst origin:
+			{:?}, message: {:?}, max_weight: {:?}, weight_credit: {:?}",
+			origin, message, max_weight, _weight_credit,
+		);
+		ensure!(T::contains(origin), ProcessMessageError::Unsupported);
+		let mut iter = message.iter_mut();
+		// Make sure the first instruction is DescendOrigin
+		iter.next()
+			.filter(|instruction| matches!(instruction, DescendOrigin(_)))
+			.ok_or(ProcessMessageError::Unsupported)?;
+
+		// Then WithdrawAsset
+		iter.next()
+			.filter(|instruction| matches!(instruction, WithdrawAsset(_)))
+			.ok_or(ProcessMessageError::Unsupported)?;
+
+		// Then BuyExecution
+		let i = iter.next().ok_or(ProcessMessageError::Unsupported)?;
+		match i {
+			BuyExecution { weight_limit: Limited(ref mut weight), .. } => {
+				if weight.all_gte(max_weight) {
+					weight.set_ref_time(max_weight.ref_time());
+					weight.set_proof_size(max_weight.proof_size());
+				};
+			},
+			BuyExecution { ref mut weight_limit, .. } if weight_limit == &Unlimited => {
+				*weight_limit = Limited(max_weight);
+			},
+			_ => {},
+		};
+
+		// Then Transact
+		let i = iter.next().ok_or(ProcessMessageError::Unsupported)?;
+		match i {
+			Transact { ref mut require_weight_at_most, .. } => {
+				let weight = Weight::from_parts(DEFAULT_REF_TIMR, DEFAULT_PROOF_SIZE);
+				*require_weight_at_most = weight;
+				Ok(())
+			},
+			_ => Err(ProcessMessageError::Unsupported),
+		}
+	}
+}
+
 /// Sets the message ID to `t` using a `SetTopic(t)` in the last position if present.
 ///
 /// Requires some inner barrier to pass on the rest of the message.
@@ -322,21 +379,16 @@ impl<InnerBarrier: ShouldExecute> ShouldExecute for TrailingSetTopicAsId<InnerBa
 }
 
 pub type Barrier = TrailingSetTopicAsId<(
+	// Weight that is paid for may be consumed.
 	TakeWeightCredit,
 	// Expected responses are OK.
 	AllowKnownQueryResponses<PolkadotXcm>,
-	// Allow XCMs with some computed origins to pass through.
-	WithComputedOrigin<
-		(
-			// If the message is one that immediately attemps to pay for execution, then
-			// allow it.
-			AllowTopLevelPaidExecutionFrom<Everything>,
-			// Subscriptions for version tracking are OK.
-			AllowSubscriptionsFrom<Everything>,
-		),
-		UniversalLocation,
-		ConstU32<8>,
-	>,
+	// If the message is one that immediately attemps to pay for execution, then allow it.
+	AllowTopLevelPaidExecutionFrom<Everything>,
+	// Subscriptions for version tracking are OK.
+	AllowSubscriptionsFrom<Everything>,
+	// Barrier allowing a top level paid message with DescendOrigin instruction
+	AllowTopLevelPaidExecutionDescendOriginFirst<Everything>,
 )>;
 
 pub type BifrostAssetTransactor = MultiCurrencyAdapter<