Unknown tokens pallet (open-web3-stack#411)

* Impl unknown tokens pallet.

* Fix workspace pallet path.

* Make clippy happy.

* Clippy, be happy.

* Unit tests.

Cargo.dev.toml

@@ -16,6 +16,7 @@ members = [
 	"nft",
 	"xtokens",
 	"xcm-support",
+	"unknown-tokens",
 ]
 resolver = "2"
 

unknown-tokens/Cargo.toml

@@ -0,0 +1,36 @@
+[package]
+name = "orml-unknown-tokens"
+description = "Unknown tokens module that implements `UnknownAsset` trait."
+repository = "https://github.com/open-web3-stack/open-runtime-module-library/tree/master/unknown-tokens"
+license = "Apache-2.0"
+version = "0.4.1-dev"
+authors = ["Acala Developers"]
+edition = "2018"
+
+[dependencies]
+serde = { version = "1.0.124", optional = true }
+codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false }
+sp-std = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1", default-features = false }
+frame-support = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1", default-features = false }
+frame-system = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1", default-features = false }
+
+xcm = { git = "https://github.com/paritytech/polkadot", branch = "rococo-v1", default-features = false }
+
+orml-xcm-support = { path = "../xcm-support", default-features = false }
+
+[dev-dependencies]
+sp-io = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1" }
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1" }
+sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "rococo-v1" }
+
+[features]
+default = ["std"]
+std = [
+	"serde",
+	"codec/std",
+	"sp-std/std",
+	"frame-support/std",
+	"frame-system/std",
+	"xcm/std",
+	"orml-xcm-support/std",
+]

unknown-tokens/src/lib.rs

@@ -0,0 +1,127 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+#![allow(clippy::unused_unit)]
+
+use frame_support::pallet_prelude::*;
+use sp_std::vec::Vec;
+use xcm::v0::{MultiAsset, MultiLocation};
+
+use orml_xcm_support::UnknownAsset;
+
+pub use module::*;
+
+mod mock;
+mod tests;
+
+#[frame_support::pallet]
+pub mod module {
+	use super::*;
+
+	#[pallet::config]
+	pub trait Config: frame_system::Config {
+		type Event: From<Event> + IsType<<Self as frame_system::Config>::Event>;
+	}
+
+	#[pallet::event]
+	#[pallet::generate_deposit(pub(crate) fn deposit_event)]
+	pub enum Event {
+		/// Deposit success. [asset, to]
+		Deposited(MultiAsset, MultiLocation),
+		/// Deposit failed. [asset, to, error]
+		DepositFailed(MultiAsset, MultiLocation, DispatchError),
+		/// Withdraw success. [asset, from]
+		Withdrawn(MultiAsset, MultiLocation),
+		/// Withdraw failed. [asset, from, error]
+		WithdrawFailed(MultiAsset, MultiLocation, DispatchError),
+	}
+
+	#[pallet::error]
+	pub enum Error<T> {
+		/// The balance is too low.
+		BalanceTooLow,
+		/// The operation will cause balance to overflow.
+		BalanceOverflow,
+		/// Unhandled asset.
+		UnhandledAsset,
+	}
+
+	#[pallet::pallet]
+	pub struct Pallet<T>(_);
+
+	#[pallet::hooks]
+	impl<T: Config> Hooks<T::BlockNumber> for Pallet<T> {}
+
+	/// Concrete fungible balances under a given location and a concrete
+	/// fungible id.
+	///
+	/// double_map: who, asset_id => u128
+	#[pallet::storage]
+	#[pallet::getter(fn concrete_fungible_balances)]
+	pub(crate) type ConcreteFungibleBalances<T> =
+		StorageDoubleMap<_, Blake2_128Concat, MultiLocation, Blake2_128Concat, MultiLocation, u128, ValueQuery>;
+
+	/// Abstract fungible balances under a given location and a abstract
+	/// fungible id.
+	///
+	/// double_map: who, asset_id => u128
+	#[pallet::storage]
+	#[pallet::getter(fn abstract_fungible_balances)]
+	pub(crate) type AbstractFungibleBalances<T> =
+		StorageDoubleMap<_, Blake2_128Concat, MultiLocation, Blake2_128Concat, Vec<u8>, u128, ValueQuery>;
+
+	#[pallet::call]
+	impl<T: Config> Pallet<T> {}
+}
+
+impl<T: Config> UnknownAsset for Pallet<T> {
+	fn deposit(asset: &MultiAsset, to: &MultiLocation) -> DispatchResult {
+		let result = match asset {
+			MultiAsset::ConcreteFungible { id, amount } => {
+				ConcreteFungibleBalances::<T>::try_mutate(to, id, |b| -> DispatchResult {
+					*b = b.checked_add(*amount).ok_or(Error::<T>::BalanceOverflow)?;
+					Ok(())
+				})
+			}
+			MultiAsset::AbstractFungible { id, amount } => {
+				AbstractFungibleBalances::<T>::try_mutate(to, id, |b| -> DispatchResult {
+					*b = b.checked_add(*amount).ok_or(Error::<T>::BalanceOverflow)?;
+					Ok(())
+				})
+			}
+			_ => Err(Error::<T>::UnhandledAsset.into()),
+		};
+
+		if let Err(err) = result {
+			Self::deposit_event(Event::DepositFailed(asset.clone(), to.clone(), err));
+		} else {
+			Self::deposit_event(Event::Deposited(asset.clone(), to.clone()));
+		}
+
+		result
+	}
+
+	fn withdraw(asset: &MultiAsset, from: &MultiLocation) -> DispatchResult {
+		let result = match asset {
+			MultiAsset::ConcreteFungible { id, amount } => {
+				ConcreteFungibleBalances::<T>::try_mutate(from, id, |b| -> DispatchResult {
+					*b = b.checked_sub(*amount).ok_or(Error::<T>::BalanceTooLow)?;
+					Ok(())
+				})
+			}
+			MultiAsset::AbstractFungible { id, amount } => {
+				AbstractFungibleBalances::<T>::try_mutate(from, id, |b| -> DispatchResult {
+					*b = b.checked_sub(*amount).ok_or(Error::<T>::BalanceTooLow)?;
+					Ok(())
+				})
+			}
+			_ => Err(Error::<T>::UnhandledAsset.into()),
+		};
+
+		if let Err(err) = result {
+			Self::deposit_event(Event::WithdrawFailed(asset.clone(), from.clone(), err));
+		} else {
+			Self::deposit_event(Event::Withdrawn(asset.clone(), from.clone()));
+		}
+
+		result
+	}
+}

unknown-tokens/src/mock.rs

@@ -0,0 +1,73 @@
+//! Mocks for the unknown pallet.
+
+#![cfg(test)]
+
+use super::*;
+use crate as unknown_tokens;
+
+use frame_support::{construct_runtime, parameter_types};
+use sp_core::H256;
+use sp_runtime::{testing::Header, traits::IdentityLookup, AccountId32};
+
+pub type AccountId = AccountId32;
+
+parameter_types! {
+	pub const BlockHashCount: u64 = 250;
+}
+
+impl frame_system::Config for Runtime {
+	type Origin = Origin;
+	type Call = Call;
+	type Index = u64;
+	type BlockNumber = u64;
+	type Hash = H256;
+	type Hashing = ::sp_runtime::traits::BlakeTwo256;
+	type AccountId = AccountId;
+	type Lookup = IdentityLookup<Self::AccountId>;
+	type Header = Header;
+	type Event = Event;
+	type BlockHashCount = BlockHashCount;
+	type BlockWeights = ();
+	type BlockLength = ();
+	type Version = ();
+	type PalletInfo = PalletInfo;
+	type AccountData = ();
+	type OnNewAccount = ();
+	type OnKilledAccount = ();
+	type DbWeight = ();
+	type BaseCallFilter = ();
+	type SystemWeightInfo = ();
+	type SS58Prefix = ();
+}
+
+impl Config for Runtime {
+	type Event = Event;
+}
+
+type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<Runtime>;
+type Block = frame_system::mocking::MockBlock<Runtime>;
+
+construct_runtime!(
+	pub enum Runtime where
+		Block = Block,
+		NodeBlock = Block,
+		UncheckedExtrinsic = UncheckedExtrinsic,
+	{
+		System: frame_system::{Module, Call, Storage, Config, Event<T>},
+		UnknownTokens: unknown_tokens::{Module, Storage, Event},
+	}
+);
+
+pub struct ExtBuilder;
+
+impl ExtBuilder {
+	pub fn build(self) -> sp_io::TestExternalities {
+		let t = frame_system::GenesisConfig::default()
+			.build_storage::<Runtime>()
+			.unwrap();
+
+		let mut ext = sp_io::TestExternalities::new(t);
+		ext.execute_with(|| System::set_block_number(1));
+		ext
+	}
+}