relay account and tests

xcm-support/src/lib.rs

@@ -10,15 +10,18 @@
 #![allow(clippy::unused_unit)]
 
 use frame_support::dispatch::{DispatchError, DispatchResult};
+use frame_support::{ensure, weights::Weight};
+
 use sp_runtime::traits::{CheckedConversion, Convert};
 use sp_std::{convert::TryFrom, marker::PhantomData, prelude::*};
 
 use xcm::latest::prelude::*;
-use xcm_executor::traits::{FilterAssetLocation, MatchesFungible};
+use xcm_executor::traits::{FilterAssetLocation, MatchesFungible, ShouldExecute};
 
 use orml_traits::location::Reserve;
 
 pub use currency_adapter::MultiCurrencyAdapter;
+use frame_support::pallet_prelude::Get;
 
 mod currency_adapter;
 
@@ -75,3 +78,84 @@ impl UnknownAsset for () {
 		Err(DispatchError::Other(NO_UNKNOWN_ASSET_IMPL))
 	}
 }
+
+/// Extracts the `AccountId32` from the passed `location` if the network
+/// matches or is `NetworkId::Any`.
+pub struct RelayChainAccountId32Aliases<Network, AccountId>(PhantomData<(Network, AccountId)>);
+impl<Network: Get<NetworkId>, AccountId: From<[u8; 32]> + Into<[u8; 32]> + Clone>
+	xcm_executor::traits::Convert<MultiLocation, AccountId> for RelayChainAccountId32Aliases<Network, AccountId>
+{
+	fn convert(location: MultiLocation) -> Result<AccountId, MultiLocation> {
+		if let MultiLocation {
+			parents: 1,
+			interior: X1(AccountId32 { id, network }),
+		} = location.clone()
+		{
+			if network == NetworkId::Any || network == Network::get() {
+				return Ok(id.into());
+			}
+		};
+		Err(location)
+	}
+
+	fn reverse(who: AccountId) -> Result<MultiLocation, AccountId> {
+		Ok((
+			1,
+			AccountId32 {
+				id: who.into(),
+				network: Network::get(),
+			},
+		)
+			.into())
+	}
+}
+
+/// Allows execution from `origin` if it is `Parent`.
+///
+/// Only allows exactly alike the order of xcm: `DescendOrigin`,
+/// `WithdrawAsset`, `BuyExecution` and `Transact`.
+pub struct AllowRelayedPaidExecutionFromParent<Network>(PhantomData<Network>);
+impl<Network: Get<NetworkId>> ShouldExecute for AllowRelayedPaidExecutionFromParent<Network> {
+	fn should_execute<Call>(
+		origin: &MultiLocation,
+		message: &mut Xcm<Call>,
+		max_weight: Weight,
+		_weight_credit: &mut Weight,
+	) -> Result<(), ()> {
+		ensure!(origin.contains_parents_only(1), ());
+		let mut iter = message.0.iter_mut();
+		let i = iter.next().ok_or(())?;
+		match i {
+			DescendOrigin(X1(Junction::AccountId32 { network, .. }))
+				if network == &NetworkId::Any || network == &Network::get() =>
+			{
+				()
+			}
+			_ => return Err(()),
+		}
+		let i = iter.next().ok_or(())?;
+		match i {
+			WithdrawAsset(..) => (),
+			_ => return Err(()),
+		}
+		let i = iter.next().ok_or(())?;
+		match i {
+			BuyExecution {
+				weight_limit: Limited(ref mut weight),
+				..
+			} if *weight >= max_weight => {
+				*weight = max_weight;
+				()
+			}
+			_ => return Err(()),
+		}
+		let i = iter.next().ok_or(())?;
+		match i {
+			Transact {
+				origin_type: OriginKind::SovereignAccount,
+				..
+			} => Ok(()),
+			_ => Err(()),
+		}
+	}
+}

xcm-support/src/tests.rs

@@ -4,7 +4,9 @@
 
 use super::*;
 
+use frame_support::{pallet_prelude::Encode, parameter_types};
 use orml_traits::{location::RelativeLocations, ConcreteFungibleAsset};
+use sp_runtime::AccountId32;
 
 #[derive(Debug, PartialEq, Eq)]
 pub enum TestCurrencyId {
@@ -98,3 +100,50 @@ fn multi_native_asset() {
 		&MultiLocation::parent(),
 	));
 }
+
+#[test]
+fn relay_account_convert() {
+	use xcm_executor::traits::Convert;
+
+	parameter_types! {
+		const RelayNetwork: NetworkId = NetworkId::Any;
+	}
+	let destination: MultiLocation = (
+		Parent,
+		Junction::AccountId32 {
+			network: NetworkId::Any,
+			id: [0; 32],
+		},
+	)
+		.into();
+	let account: Result<AccountId32, MultiLocation> =
+		RelayChainAccountId32Aliases::<RelayNetwork, AccountId32>::convert(destination);
+	assert_eq!(account, Ok(AccountId32::new([0; 32])));
+}
+
+#[test]
+fn allow_relayed_paid_execution_works() {
+	parameter_types! {
+		const RelayNetwork: NetworkId = NetworkId::Any;
+	}
+	let assets: MultiAsset = (Parent, 1000).into();
+	let mut xcm = Xcm::<()>(vec![
+		DescendOrigin(X1(Junction::AccountId32 {
+			network: NetworkId::Any,
+			id: [0; 32],
+		})),
+		WithdrawAsset(assets.clone().into()),
+		BuyExecution {
+			fees: assets,
+			weight_limit: Limited(1000),
+		},
+		Transact {
+			origin_type: OriginKind::SovereignAccount,
+			require_weight_at_most: 1000 as u64,
+			call: Encode::encode(&100).into(),
+		},
+	]);
+	let r =
+		AllowRelayedPaidExecutionFromParent::<RelayNetwork>::should_execute(&(Parent.into()), &mut xcm, 100, &mut 100);
+	assert_eq!(r, Ok(()));
+}

xtokens/src/mock/mod.rs

@@ -8,13 +8,39 @@ use serde::{Deserialize, Serialize};
 use sp_io::TestExternalities;
 use sp_runtime::AccountId32;
 
+use cumulus_primitives_core::ParaId;
+use polkadot_parachain::primitives::{AccountIdConversion, Sibling};
 use xcm_simulator::{decl_test_network, decl_test_parachain, decl_test_relay_chain};
 
 pub mod para;
 pub mod relay;
 
-pub const ALICE: AccountId32 = AccountId32::new([0u8; 32]);
-pub const BOB: AccountId32 = AccountId32::new([1u8; 32]);
+pub const ALICE: AccountId32 = AccountId32::new([1u8; 32]);
+pub const BOB: AccountId32 = AccountId32::new([2u8; 32]);
+pub const INITIAL_BALANCE: u128 = 1_000;
+
+pub fn para_a_account() -> AccountId32 {
+	ParaId::from(1).into_account()
+}
+
+pub fn para_b_account() -> AccountId32 {
+	ParaId::from(2).into_account()
+}
+
+pub fn sibling_a_account() -> AccountId32 {
+	use sp_runtime::traits::AccountIdConversion;
+	Sibling::from(1).into_account()
+}
+
+pub fn sibling_b_account() -> AccountId32 {
+	use sp_runtime::traits::AccountIdConversion;
+	Sibling::from(2).into_account()
+}
+
+pub fn sibling_c_account() -> AccountId32 {
+	use sp_runtime::traits::AccountIdConversion;
+	Sibling::from(3).into_account()
+}
 
 #[derive(Encode, Decode, Eq, PartialEq, Copy, Clone, RuntimeDebug, PartialOrd, Ord, TypeInfo)]
 #[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
@@ -135,7 +161,7 @@ pub fn para_ext(para_id: u32) -> TestExternalities {
 		.unwrap();
 
 	orml_tokens::GenesisConfig::<Runtime> {
-		balances: vec![(ALICE, CurrencyId::R, 1_000)],
+		balances: vec![(ALICE, CurrencyId::R, INITIAL_BALANCE)],
 	}
 	.assimilate_storage(&mut t)
 	.unwrap();
@@ -153,7 +179,7 @@ pub fn relay_ext() -> sp_io::TestExternalities {
 		.unwrap();
 
 	pallet_balances::GenesisConfig::<Runtime> {
-		balances: vec![(ALICE, 1_000)],
+		balances: vec![(ALICE, INITIAL_BALANCE)],
 	}
 	.assimilate_storage(&mut t)
 	.unwrap();

xtokens/src/mock/para.rs

@@ -26,7 +26,10 @@ use xcm_builder::{
 use xcm_executor::{traits::WeightTrader, Assets, Config, XcmExecutor};
 
 use orml_traits::parameter_type_with_key;
-use orml_xcm_support::{IsNativeConcrete, MultiCurrencyAdapter, MultiNativeAsset};
+use orml_xcm_support::{
+	AllowRelayedPaidExecutionFromParent, IsNativeConcrete, MultiCurrencyAdapter, MultiNativeAsset,
+	RelayChainAccountId32Aliases,
+};
 
 pub type AccountId = AccountId32;
 
@@ -114,6 +117,7 @@ pub type LocationToAccountId = (
 	ParentIsDefault<AccountId>,
 	SiblingParachainConvertsVia<Sibling, AccountId>,
 	AccountId32Aliases<RelayNetwork, AccountId>,
+	RelayChainAccountId32Aliases<RelayNetwork, AccountId>,
 );
 
 pub type XcmOriginToCallOrigin = (
@@ -140,7 +144,11 @@ pub type LocalAssetTransactor = MultiCurrencyAdapter<
 >;
 
 pub type XcmRouter = ParachainXcmRouter<ParachainInfo>;
-pub type Barrier = (TakeWeightCredit, AllowTopLevelPaidExecutionFrom<Everything>);
+pub type Barrier = (
+	TakeWeightCredit,
+	AllowTopLevelPaidExecutionFrom<Everything>,
+	AllowRelayedPaidExecutionFromParent<RelayNetwork>,
+);
 
 /// A trader who believes all tokens are created equal to "weight" of any chain,
 /// which is not true, but good enough to mock the fee payment of XCM execution.

xtokens/src/tests.rs

@@ -1,38 +1,11 @@
 #![cfg(test)]
 
 use super::*;
-use codec::Encode;
-use cumulus_primitives_core::ParaId;
 use frame_support::{assert_err, assert_noop, assert_ok, traits::Currency};
 use mock::*;
 use orml_traits::{ConcreteFungibleAsset, MultiCurrency};
-use polkadot_parachain::primitives::{AccountIdConversion, Sibling};
-use sp_runtime::AccountId32;
 use xcm_simulator::TestExt;
 
-fn para_a_account() -> AccountId32 {
-	ParaId::from(1).into_account()
-}
-
-fn para_b_account() -> AccountId32 {
-	ParaId::from(2).into_account()
-}
-
-fn sibling_a_account() -> AccountId32 {
-	use sp_runtime::traits::AccountIdConversion;
-	Sibling::from(1).into_account()
-}
-
-fn sibling_b_account() -> AccountId32 {
-	use sp_runtime::traits::AccountIdConversion;
-	Sibling::from(2).into_account()
-}
-
-fn sibling_c_account() -> AccountId32 {
-	use sp_runtime::traits::AccountIdConversion;
-	Sibling::from(3).into_account()
-}
-
 // Not used in any unit tests, but it's super helpful for debugging. Let's
 // keep it here.
 #[allow(dead_code)]