use asset hub as reserve (#327)

* implemented asset hub as reserve

evm-template/runtime/src/configs/xcm_config.rs

@@ -2,27 +2,28 @@ use core::marker::PhantomData;
 
 use frame_support::{
     parameter_types,
-    traits::{ConstU32, Contains, Everything, Nothing, PalletInfoAccess},
+    traits::{ConstU32, Contains, ContainsPair, Everything, Nothing, PalletInfoAccess},
     weights::Weight,
 };
 use frame_system::EnsureRoot;
+use orml_xcm_support::MultiNativeAsset;
 use pallet_xcm::XcmPassthrough;
 use polkadot_parachain_primitives::primitives::{self, Sibling};
 use xcm::latest::prelude::{Assets as XcmAssets, *};
 use xcm_builder::{
-    AccountKey20Aliases, AllowExplicitUnpaidExecutionFrom, AllowTopLevelPaidExecutionFrom,
+    AccountKey20Aliases, AllowExplicitUnpaidExecutionFrom, AllowTopLevelPaidExecutionFrom, Case,
     ConvertedConcreteId, DenyReserveTransferToRelayChain, DenyThenTry, EnsureXcmOrigin,
     FixedWeightBounds, FrameTransactionalProcessor, FungibleAdapter, FungiblesAdapter, HandleFee,
-    IsChildSystemParachain, IsConcrete, NativeAsset, NoChecking, ParentIsPreset,
-    RelayChainAsNative, SiblingParachainAsNative, SiblingParachainConvertsVia,
-    SignedAccountKey20AsNative, SovereignSignedViaLocation, TakeWeightCredit, TrailingSetTopicAsId,
-    UsingComponents, WithComputedOrigin, WithUniqueTopic, XcmFeeManagerFromComponents,
+    IsChildSystemParachain, IsConcrete, NoChecking, ParentIsPreset, RelayChainAsNative,
+    SiblingParachainAsNative, SiblingParachainConvertsVia, SignedAccountKey20AsNative,
+    SovereignSignedViaLocation, TakeWeightCredit, TrailingSetTopicAsId, UsingComponents,
+    WithComputedOrigin, WithUniqueTopic, XcmFeeManagerFromComponents,
 };
 use xcm_executor::{
     traits::{FeeReason, JustTry, TransactAsset},
     XcmExecutor,
 };
-use xcm_primitives::AsAssetType;
+use xcm_primitives::{AbsoluteAndRelativeReserve, AsAssetType};
 
 use crate::{
     configs::{
@@ -35,7 +36,6 @@ use crate::{
 };
 
 parameter_types! {
-    pub const RelayLocation: Location = Location::parent();
     pub const RelayNetwork: Option<NetworkId> = None;
     pub AssetsPalletLocation: Location =
         PalletInstance(<Assets as PalletInfoAccess>::index() as u8).into();
@@ -188,6 +188,46 @@ pub fn deposit_or_burn_fee<AssetTransactor: TransactAsset, AccountId: Clone + In
     }
 }
 
+/// Matches foreign assets from a given origin.
+/// Foreign assets are assets bridged from other consensus systems. i.e parents > 1.
+pub struct IsBridgedConcreteAssetFrom<Origin>(PhantomData<Origin>);
+impl<Origin> ContainsPair<Asset, Location> for IsBridgedConcreteAssetFrom<Origin>
+where
+    Origin: Get<Location>,
+{
+    fn contains(asset: &Asset, origin: &Location) -> bool {
+        let loc = Origin::get();
+        &loc == origin
+            && matches!(
+                asset,
+                Asset { id: AssetId(Location { parents: 2, .. }), fun: Fungibility::Fungible(_) },
+            )
+    }
+}
+
+parameter_types! {
+    /// Location of Asset Hub
+   pub AssetHubLocation: Location = Location::new(1, [Parachain(1000)]);
+   pub const RelayLocation: Location = Location::parent();
+   pub RelayLocationFilter: AssetFilter = Wild(AllOf {
+       fun: WildFungible,
+       id: xcm::prelude::AssetId(RelayLocation::get()),
+   });
+   pub RelayChainNativeAssetFromAssetHub: (AssetFilter, Location) = (
+       RelayLocationFilter::get(),
+       AssetHubLocation::get()
+   );
+}
+
+type Reserves = (
+    // Assets bridged from different consensus systems held in reserve on Asset Hub.
+    IsBridgedConcreteAssetFrom<AssetHubLocation>,
+    // Relaychain (DOT) from Asset Hub
+    Case<RelayChainNativeAssetFromAssetHub>,
+    // Assets which the reserve is the same as the origin.
+    MultiNativeAsset<AbsoluteAndRelativeReserve<SelfLocationAbsolute>>,
+);
+
 parameter_types! {
     pub TreasuryAccount: AccountId = Treasury::account_id();
 }
@@ -214,7 +254,7 @@ impl xcm_executor::Config for XcmConfig {
     /// Please, keep these two configs (`IsReserve` and `IsTeleporter`) mutually exclusive.
     /// The IsReserve type must be set to specify which <MultiAsset, MultiLocation> pair we trust to deposit reserve assets on our chain. We can also use the unit type () to block ReserveAssetDeposited instructions.
     /// The IsTeleporter type must be set to specify which <MultiAsset, MultiLocation> pair we trust to teleport assets to our chain. We can also use the unit type () to block ReceiveTeleportedAssets instruction.
-    type IsReserve = NativeAsset;
+    type IsReserve = Reserves;
     type IsTeleporter = ();
     type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
     type MessageExporter = ();
@@ -314,3 +354,21 @@ impl cumulus_pallet_xcm::Config for Runtime {
     type RuntimeEvent = RuntimeEvent;
     type XcmExecutor = XcmExecutor<XcmConfig>;
 }
+
+// We are not using all of these below atm, but we will need them when configuring `orml_xtokens`
+parameter_types! {
+    pub const BaseXcmWeight: Weight = Weight::from_parts(200_000_000u64, 0);
+    pub const MaxAssetsForTransfer: usize = 2;
+
+    // This is how we are going to detect whether the asset is a Reserve asset
+    // This however is the chain part only
+    pub SelfLocation: Location = Location::here();
+    // We need this to be able to catch when someone is trying to execute a non-
+    // cross-chain transfer in xtokens through the absolute path way
+    pub SelfLocationAbsolute: Location = Location {
+        parents:1,
+        interior: [
+            Parachain(ParachainInfo::parachain_id().into())
+        ].into()
+    };
+}