lib.rs

// Copyright 2020-2021 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.

//! Pallet to handle XCM messages.

#![cfg_attr(not(feature = "std"), no_std)]

#[cfg(feature = "runtime-benchmarks")]
mod benchmarking;
#[cfg(test)]
mod mock;
#[cfg(test)]
mod tests;

pub mod migration;

use codec::{Decode, Encode, EncodeLike, MaxEncodedLen};
use frame_support::traits::{
	Contains, ContainsPair, Currency, Defensive, EnsureOrigin, Get, LockableCurrency, OriginTrait,
};
use scale_info::TypeInfo;
use sp_runtime::{
	traits::{
		AccountIdConversion, BadOrigin, BlakeTwo256, BlockNumberProvider, Hash, Saturating, Zero,
	},
	RuntimeDebug,
};
use sp_std::{boxed::Box, marker::PhantomData, prelude::*, result::Result, vec};
use xcm::{latest::QueryResponseInfo, prelude::*};
use xcm_executor::traits::{Convert, ConvertOrigin};

use frame_support::{
	dispatch::{Dispatchable, GetDispatchInfo},
	pallet_prelude::*,
	traits::WithdrawReasons,
	PalletId,
};
use frame_system::pallet_prelude::*;
pub use pallet::*;
use xcm_executor::{
	traits::{
		ClaimAssets, DropAssets, MatchesFungible, OnResponse, VersionChangeNotifier, WeightBounds,
	},
	Assets,
};

pub trait WeightInfo {
	fn send() -> Weight;
	fn teleport_assets() -> Weight;
	fn reserve_transfer_assets() -> Weight;
	fn execute() -> Weight;
	fn force_xcm_version() -> Weight;
	fn force_default_xcm_version() -> Weight;
	fn force_subscribe_version_notify() -> Weight;
	fn force_unsubscribe_version_notify() -> Weight;
	fn migrate_supported_version() -> Weight;
	fn migrate_version_notifiers() -> Weight;
	fn already_notified_target() -> Weight;
	fn notify_current_targets() -> Weight;
	fn notify_target_migration_fail() -> Weight;
	fn migrate_version_notify_targets() -> Weight;
	fn migrate_and_notify_old_targets() -> Weight;
}

/// fallback implementation
pub struct TestWeightInfo;
impl WeightInfo for TestWeightInfo {
	fn send() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn teleport_assets() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn reserve_transfer_assets() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn execute() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn force_xcm_version() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn force_default_xcm_version() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn force_subscribe_version_notify() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn force_unsubscribe_version_notify() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn migrate_supported_version() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn migrate_version_notifiers() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn already_notified_target() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn notify_current_targets() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn notify_target_migration_fail() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn migrate_version_notify_targets() -> Weight {
		Weight::from_ref_time(100_000_000)
	}

	fn migrate_and_notify_old_targets() -> Weight {
		Weight::from_ref_time(100_000_000)
	}
}

#[frame_support::pallet]
pub mod pallet {
	use super::*;
	use frame_support::{
		dispatch::{Dispatchable, GetDispatchInfo, PostDispatchInfo},
		parameter_types,
	};
	use frame_system::Config as SysConfig;
	use sp_core::H256;
	use xcm_executor::traits::{MatchesFungible, WeightBounds};

	parameter_types! {
		/// An implementation of `Get<u32>` which just returns the latest XCM version which we can
		/// support.
		pub const CurrentXcmVersion: u32 = XCM_VERSION;
	}

	#[pallet::pallet]
	#[pallet::generate_store(pub(super) trait Store)]
	#[pallet::storage_version(migration::STORAGE_VERSION)]
	#[pallet::without_storage_info]
	pub struct Pallet<T>(_);

	pub type BalanceOf<T> =
		<<T as Config>::Currency as Currency<<T as frame_system::Config>::AccountId>>::Balance;

	#[pallet::config]
	/// The module configuration trait.
	pub trait Config: frame_system::Config {
		/// The overarching event type.
		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;

		/// A lockable currency.
		// TODO: We should really use a trait which can handle multiple currencies.
		type Currency: LockableCurrency<Self::AccountId, Moment = Self::BlockNumber>;

		/// The `MultiAsset` matcher for `Currency`.
		type CurrencyMatcher: MatchesFungible<BalanceOf<Self>>;

		/// Required origin for sending XCM messages. If successful, it resolves to `MultiLocation`
		/// which exists as an interior location within this chain's XCM context.
		type SendXcmOrigin: EnsureOrigin<
			<Self as SysConfig>::RuntimeOrigin,
			Success = MultiLocation,
		>;

		/// The type used to actually dispatch an XCM to its destination.
		type XcmRouter: SendXcm;

		/// Required origin for executing XCM messages, including the teleport functionality. If successful,
		/// then it resolves to `MultiLocation` which exists as an interior location within this chain's XCM
		/// context.
		type ExecuteXcmOrigin: EnsureOrigin<
			<Self as SysConfig>::RuntimeOrigin,
			Success = MultiLocation,
		>;

		/// Our XCM filter which messages to be executed using `XcmExecutor` must pass.
		type XcmExecuteFilter: Contains<(MultiLocation, Xcm<<Self as SysConfig>::RuntimeCall>)>;