refactor ForeignAssetMatcher

precompiles/assets-erc20/Cargo.toml

@@ -27,6 +27,9 @@ sp-std = { workspace = true }
 fp-evm = { workspace = true }
 pallet-evm = { workspace = true, features = [ "forbid-evm-reentrancy" ] }
 
+# Moonkit
+xcm-primitives = { workspace = true }
+
 [dev-dependencies]
 hex-literal = { workspace = true }
 libsecp256k1 = { workspace = true }
@@ -57,4 +60,5 @@ std = [
 	"sp-io/std",
 	"sp-runtime/std",
 	"sp-std/std",
+	"xcm-primitives/std",
 ]

precompiles/assets-erc20/src/lib.rs

@@ -38,6 +38,7 @@ use sp_std::{
 	convert::{TryFrom, TryInto},
 	marker::PhantomData,
 };
+use xcm_primitives::AccountIdAssetIdConversion;
 
 mod eip2612;
 use eip2612::Eip2612;
@@ -59,16 +60,6 @@ pub type BalanceOf<Runtime, Instance = ()> = <Runtime as pallet_assets::Config<I
 /// Alias for the Asset Id type for the provided Runtime and Instance.
 pub type AssetIdOf<Runtime, Instance = ()> = <Runtime as pallet_assets::Config<Instance>>::AssetId;
 
-/// This trait ensure we can convert AccountIds to AssetIds
-/// We will require Runtime to have this trait implemented
-pub trait AccountIdAssetIdConversion<Account, AssetId> {
-	// Get assetId and prefix from account
-	fn account_to_asset_id(account: Account) -> Option<(Vec<u8>, AssetId)>;
-
-	// Get AccountId from AssetId and prefix
-	fn asset_id_to_account(prefix: &[u8], asset_id: AssetId) -> Account;
-}
-
 /// The following distribution has been decided for the precompiles
 /// 0-1023: Ethereum Mainnet Precompiles
 /// 1024-2047 Precompiles that are not in Ethereum Mainnet but are neither Moonbeam specific

precompiles/assets-erc20/src/mock.rs

@@ -36,6 +36,7 @@ use sp_runtime::{
 	traits::{BlakeTwo256, ConstU32, IdentityLookup},
 	BuildStorage,
 };
+use xcm_primitives::AccountIdAssetIdConversion;
 
 pub type AccountId = MockAccount;
 pub type AssetId = u128;

precompiles/pallet-xcm/src/mock.rs

@@ -39,9 +39,9 @@ use xcm_executor::{
 	traits::{ConvertLocation, TransactAsset, WeightTrader},
 	AssetsInHolding,
 };
-pub use xcm_primitives::location_matcher::{
-	AssetIdInfoGetter, Erc20PalletMatcher, MatchThroughEquivalence, SingleAddressMatcher,
-};
+pub use xcm_primitives::{AccountIdAssetIdConversion, location_matcher::{
+	Erc20PalletMatcher, ForeignAssetMatcher, SingleAddressMatcher,
+}};
 use Junctions::Here;
 
 pub type AccountId = MockAccount;
@@ -128,6 +128,35 @@ parameter_types! {
 	pub const MetadataDepositPerByte: u64 = 0;
 }
 
+pub const FOREIGN_ASSET_ADDRESS_PREFIX: &[u8] = &[255u8; 18];
+
+// Instruct how to go from an H160 to an AssetID
+// We just take the lowest 2 bytes
+impl AccountIdAssetIdConversion<AccountId, AssetId> for Runtime {
+	/// The way to convert an account to assetId is by ensuring that the prefix is [0xFF, 18]
+	/// and by taking the lowest 2 bytes as the assetId
+	fn account_to_asset_id(account: AccountId) -> Option<(Vec<u8>, AssetId)> {
+		let h160_account: H160 = account.into();
+		let mut data = [0u8; 2];
+		let (prefix_part, id_part) = h160_account.as_fixed_bytes().split_at(18);
+		if prefix_part == FOREIGN_ASSET_ADDRESS_PREFIX {
+			data.copy_from_slice(id_part);
+			let asset_id: AssetId = u16::from_be_bytes(data);
+			Some((prefix_part.to_vec(), asset_id))
+		} else {
+			None
+		}
+	}
+
+	// The opposite conversion
+	fn asset_id_to_account(prefix: &[u8], asset_id: AssetId) -> AccountId {
+		let mut data = [0u8; 20];
+		data[0..18].copy_from_slice(prefix);
+		data[18..20].copy_from_slice(&asset_id.to_be_bytes());
+		AccountId::from(data)
+	}
+}
+
 pub type AssetId = u16;
 
 impl pallet_assets::Config for Runtime {
@@ -173,13 +202,13 @@ pub type AccountIdAlias = <mock::Runtime as frame_system::Config>::AccountId;
 
 pub type SingleAddressMatch = SingleAddressMatcher<AccountIdAlias, 2050, Balances>;
 
-pub type EquivalenceMatch =
-	MatchThroughEquivalence<AccountIdAlias, AssetId, AssetIdInfoGetter, ForeignAssetCreator>;
+pub type ForeignAssetMatch =
+	ForeignAssetMatcher<AccountIdAlias, AssetId, mock::Runtime, ForeignAssetCreator>;
 
 pub type Erc20Match = Erc20PalletMatcher<AccountIdAlias, 42>;
 
 pub type PCall =
-	PalletXcmPrecompileCall<Runtime, (SingleAddressMatch, EquivalenceMatch, Erc20Match)>;
+	PalletXcmPrecompileCall<Runtime, (SingleAddressMatch, ForeignAssetMatch, Erc20Match)>;
 
 mock_account!(ParentAccount, |_| MockAccount::from_u64(4));
 
@@ -195,7 +224,7 @@ const BLOCK_STORAGE_LIMIT: u64 = 40 * 1024;
 
 parameter_types! {
 	pub BlockGasLimit: U256 = U256::from(u64::MAX);
-	pub PrecompilesValue: Precompiles<Runtime, (SingleAddressMatch, EquivalenceMatch, Erc20Match)> = Precompiles::new();
+	pub PrecompilesValue: Precompiles<Runtime, (SingleAddressMatch, ForeignAssetMatch, Erc20Match)> = Precompiles::new();
 	pub const WeightPerGas: Weight = Weight::from_parts(1, 0);
 	pub GasLimitPovSizeRatio: u64 = {
 		let block_gas_limit = BlockGasLimit::get().min(u64::MAX.into()).low_u64();
@@ -230,7 +259,7 @@ impl pallet_evm::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type Runner = pallet_evm::runner::stack::Runner<Self>;
 	type PrecompilesValue = PrecompilesValue;
-	type PrecompilesType = Precompiles<Self, (SingleAddressMatch, EquivalenceMatch, Erc20Match)>;
+	type PrecompilesType = Precompiles<Self, (SingleAddressMatch, ForeignAssetMatch, Erc20Match)>;
 	type ChainId = ();
 	type OnChargeTransaction = ();
 	type BlockGasLimit = BlockGasLimit;

precompiles/pallet-xcm/src/tests.rs

@@ -19,7 +19,7 @@ use precompile_utils::testing::*;
 use sp_weights::Weight;
 use xcm::latest::Junction::*;
 
-fn precompiles() -> Precompiles<Runtime, (SingleAddressMatch, EquivalenceMatch, Erc20Match)> {
+fn precompiles() -> Precompiles<Runtime, (SingleAddressMatch, ForeignAssetMatch, Erc20Match)> {
 	PrecompilesValue::get()
 }
 

primitives/xcm/src/lib.rs

@@ -36,3 +36,12 @@ impl PauseXcmExecution for () {
 		Ok(())
 	}
 }
+
+/// This trait ensure we can convert AccountIds to AssetIds.
+pub trait AccountIdAssetIdConversion<Account, AssetId> {
+	// Get assetId and prefix from account
+	fn account_to_asset_id(account: Account) -> Option<(Vec<u8>, AssetId)>;
+
+	// Get AccountId from AssetId and prefix
+	fn asset_id_to_account(prefix: &[u8], asset_id: AssetId) -> Account;
+}

primitives/xcm/src/location_matcher.rs

@@ -14,49 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Moonkit.  If not, see <http://www.gnu.org/licenses/>.
 
+use crate::AccountIdAssetIdConversion;
 use frame_support::{traits::PalletInfoAccess, Parameter};
 use sp_core::H160;
 use sp_runtime::traits::MaybeEquivalence;
-use sp_std::{fmt::Debug, marker::PhantomData, mem::size_of};
+use sp_std::{fmt::Debug, marker::PhantomData};
 use xcm::latest::{Junction::*, Location};
 
-/// Information to retrieve for a specific AssetId type.
-pub struct AssetIdInfo<'a> {
-	pub foreign_asset_prefix: &'a [u8],
-	pub size_of: usize,
-}
-
-// Define a trait to abstract over different types of AssetId.
-// We retrieve an AssetIdInfo type containing all the information we need
-// to handle the generic types over AssetId.
-pub trait GetAssetIdInfo<T> {
-	fn get_asset_id_info() -> AssetIdInfo<'static>;
-}
-
-/// A getter that contains the info for each type
-/// we admit as AssetId.
-pub struct AssetIdInfoGetter;
-
-// Implement GetAssetId trait for u128.
-impl GetAssetIdInfo<u128> for AssetIdInfoGetter {
-	fn get_asset_id_info() -> AssetIdInfo<'static> {
-		AssetIdInfo {
-			foreign_asset_prefix: &[255u8; 4],
-			size_of: size_of::<u128>(),
-		}
-	}
-}
-
-// Implement GetAssetId trait for u16.
-impl GetAssetIdInfo<u16> for AssetIdInfoGetter {
-	fn get_asset_id_info() -> AssetIdInfo<'static> {
-		AssetIdInfo {
-			foreign_asset_prefix: &[255u8; 18],
-			size_of: size_of::<u16>(),
-		}
-	}
-}
-
 /// A converter from AccountId to a XCM Location.
 pub trait AccountIdToLocationMatcher<AccountId> {
 	fn convert(account: AccountId) -> Option<Location>;
@@ -99,63 +63,29 @@ where
 }
 
 /// Matcher to compare a received account against some possible foreign asset address.
-pub struct MatchThroughEquivalence<AccountId, AssetId, AssetIdInfoGetter, AssetIdToLocationManager>(
+pub struct ForeignAssetMatcher<
+	AccountId,
+	AssetId,
+	AccountIdAssetIdConverter,
+	AssetIdToLocationManager,
+>(
 	PhantomData<(
 		AccountId,
 		AssetId,
-		AssetIdInfoGetter,
+		AccountIdAssetIdConverter,
 		AssetIdToLocationManager,
 	)>,
 );
 
-impl<AccountId, AssetId, AssetIdInfoGetter, AssetIdToLocationManager>
-	MatchThroughEquivalence<AccountId, AssetId, AssetIdInfoGetter, AssetIdToLocationManager>
-where
-	AccountId: Parameter + Into<H160>,
-	AssetId: From<u8> + TryFrom<u16> + TryFrom<u128>,
-{
-	// Helper function that retrieves the asset_id of a foreign asset account.
-	pub fn account_to_asset_id(
-		account: AccountId,
-		asset_id_info: AssetIdInfo,
-	) -> Option<(Vec<u8>, AssetId)> {
-		let h160_account: H160 = account.into();
-		let (prefix_part, id_part) = h160_account
-			.as_fixed_bytes()
-			.split_at(asset_id_info.size_of + 2);
-
-		if prefix_part == asset_id_info.foreign_asset_prefix {
-			let asset_id: AssetId = match asset_id_info.size_of {
-				2 => {
-					let mut data = [0u8; 2];
-					data.copy_from_slice(id_part);
-					u16::from_be_bytes(data).try_into().unwrap_or(0u8.into())
-				}
-				16 => {
-					let mut data = [0u8; 16];
-					data.copy_from_slice(id_part);
-					u128::from_be_bytes(data).try_into().unwrap_or(0u8.into())
-				}
-				_ => return None,
-			};
-			return Some((prefix_part.to_vec(), asset_id));
-		}
-		None
-	}
-}
-
-impl<AccountId, AssetId, AssetIdInfoGetter, AssetIdToLocationManager>
+impl<AccountId, AssetId, AccountIdAssetIdConverter, AssetIdToLocationManager>
 	AccountIdToLocationMatcher<AccountId>
-	for MatchThroughEquivalence<AccountId, AssetId, AssetIdInfoGetter, AssetIdToLocationManager>
+	for ForeignAssetMatcher<AccountId, AssetId, AccountIdAssetIdConverter, AssetIdToLocationManager>
 where
-	AccountId: Parameter + Into<H160>,
-	AssetId: From<u8> + TryFrom<u16> + TryFrom<u128>,
-	AssetIdInfoGetter: GetAssetIdInfo<AssetId>,
+	AccountIdAssetIdConverter: AccountIdAssetIdConversion<AccountId, AssetId>,
 	AssetIdToLocationManager: MaybeEquivalence<Location, AssetId>,
 {
 	fn convert(account: AccountId) -> Option<Location> {
-		let asset_id_info = AssetIdInfoGetter::get_asset_id_info();
-		if let Some((_prefix, asset_id)) = Self::account_to_asset_id(account, asset_id_info) {
+		if let Some((_prefix, asset_id)) = AccountIdAssetIdConverter::account_to_asset_id(account) {
 			return AssetIdToLocationManager::convert_back(&asset_id);
 		}
 		None