Add XCM pallet and config to Polkadot runtime (#4313)

* xcm added

* xcm pallet & config added Polkadot

* set advertise XCM version to 2 for Polkadot

* remove ChildSystemParachainAsSuperuser from Polkadot XCM config

* remove unpaid execution for system parachains

* remove unused imports
Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

Cargo.lock

@@ -6772,6 +6772,7 @@ dependencies = [
  "pallet-treasury",
  "pallet-utility",
  "pallet-vesting",
+ "pallet-xcm",
  "parity-scale-codec",
  "polkadot-primitives",
  "polkadot-runtime-common",
@@ -6804,6 +6805,9 @@ dependencies = [
  "substrate-wasm-builder",
  "tiny-keccak",
  "trie-db",
+ "xcm",
+ "xcm-builder",
+ "xcm-executor",
 ]
 
 [[package]]

node/service/src/chain_spec.rs

@@ -366,6 +366,7 @@ fn polkadot_staging_testnet_config_genesis(wasm_binary: &[u8]) -> polkadot::Gene
 			config: default_parachains_host_configuration(),
 		},
 		paras: Default::default(),
+		xcm_pallet: polkadot::XcmPalletConfig { safe_xcm_version: Some(2) },
 	}
 }
 
@@ -1310,6 +1311,7 @@ pub fn polkadot_testnet_genesis(
 			config: default_parachains_host_configuration(),
 		},
 		paras: Default::default(),
+		xcm_pallet: polkadot::XcmPalletConfig { safe_xcm_version: Some(2) },
 	}
 }
 

runtime/polkadot/Cargo.toml

@@ -69,6 +69,7 @@ pallet-treasury = { git = "https://github.com/paritytech/substrate", branch = "m
 pallet-vesting = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 pallet-utility = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 frame-election-provider-support = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+pallet-xcm = { path = "../../xcm/pallet-xcm", default-features = false }
 
 frame-benchmarking = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false, optional = true }
 frame-try-runtime = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false, optional = true }
@@ -81,6 +82,10 @@ runtime-common = { package = "polkadot-runtime-common", path = "../common", defa
 runtime-parachains = { package = "polkadot-runtime-parachains", path = "../parachains", default-features = false }
 primitives = { package = "polkadot-primitives", path = "../../primitives", default-features = false }
 
+xcm = { package = "xcm", path = "../../xcm", default-features = false }
+xcm-executor = { package = "xcm-executor", path = "../../xcm/xcm-executor", default-features = false }
+xcm-builder = { package = "xcm-builder", path = "../../xcm/xcm-builder", default-features = false }
+
 [dev-dependencies]
 hex-literal = "0.3.4"
 tiny-keccak = "2.0.2"
@@ -158,6 +163,10 @@ std = [
 	"beefy-primitives/std",
 	"pallet-mmr-primitives/std",
 	"frame-election-provider-support/std",
+  "pallet-xcm/std",
+  "xcm/std",
+	"xcm-executor/std",
+	"xcm-builder/std",
 ]
 runtime-benchmarks = [
 	"runtime-common/runtime-benchmarks",
@@ -187,10 +196,12 @@ runtime-benchmarks = [
 	"pallet-tips/runtime-benchmarks",
 	"pallet-utility/runtime-benchmarks",
 	"pallet-vesting/runtime-benchmarks",
+  "pallet-xcm/runtime-benchmarks",
 	"pallet-offences-benchmarking",
 	"pallet-session-benchmarking",
 	"frame-system-benchmarking",
 	"hex-literal",
+  "xcm-builder/runtime-benchmarks",
 	"frame-election-provider-support/runtime-benchmarks",
 	"runtime-parachains/runtime-benchmarks",
 ]

runtime/polkadot/src/lib.rs

@@ -22,9 +22,9 @@
 
 use pallet_transaction_payment::CurrencyAdapter;
 use runtime_common::{
-	auctions, claims, crowdloan, impls::DealWithFees, paras_registrar, slots, BlockHashCount,
-	BlockLength, BlockWeights, CurrencyToVote, OffchainSolutionLengthLimit,
-	OffchainSolutionWeightLimit, RocksDbWeight, SlowAdjustingFeeUpdate,
+	auctions, claims, crowdloan, impls::DealWithFees, paras_registrar, slots, xcm_sender,
+	BlockHashCount, BlockLength, BlockWeights, CurrencyToVote, OffchainSolutionLengthLimit,
+	OffchainSolutionWeightLimit, RocksDbWeight, SlowAdjustingFeeUpdate, ToAuthor,
 };
 
 use runtime_parachains::{
@@ -39,8 +39,11 @@ use runtime_parachains::{
 use authority_discovery_primitives::AuthorityId as AuthorityDiscoveryId;
 use beefy_primitives::crypto::AuthorityId as BeefyId;
 use frame_support::{
-	construct_runtime, parameter_types,
-	traits::{Contains, KeyOwnerProofSystem, LockIdentifier, OnRuntimeUpgrade, PrivilegeCmp},
+	construct_runtime, match_type, parameter_types,
+	traits::{
+		Contains, Everything, InstanceFilter, KeyOwnerProofSystem, LockIdentifier, Nothing,
+		OnRuntimeUpgrade, PrivilegeCmp,
+	},
 	weights::Weight,
 	PalletId, RuntimeDebug,
 };
@@ -78,6 +81,15 @@ use sp_std::{cmp::Ordering, collections::btree_map::BTreeMap, prelude::*};
 use sp_version::NativeVersion;
 use sp_version::RuntimeVersion;
 use static_assertions::const_assert;
+use xcm::latest::prelude::*;
+use xcm_builder::{
+	AccountId32Aliases, AllowKnownQueryResponses, AllowSubscriptionsFrom,
+	AllowTopLevelPaidExecutionFrom, BackingToPlurality, ChildParachainAsNative,
+	ChildParachainConvertsVia, CurrencyAdapter as XcmCurrencyAdapter, FixedWeightBounds,
+	IsConcrete, LocationInverter, SignedAccountId32AsNative, SignedToAccountId32,
+	SovereignSignedViaLocation, TakeWeightCredit, UsingComponents,
+};
+use xcm_executor::XcmExecutor;
 
 pub use pallet_balances::Call as BalancesCall;
 pub use pallet_election_provider_multi_phase::Call as EPMCall;
@@ -90,7 +102,6 @@ pub use sp_runtime::BuildStorage;
 /// Constant values used within the runtime.
 pub mod constants;
 use constants::{currency::*, fee::*, time::*};
-use frame_support::traits::InstanceFilter;
 
 // Weights used in the runtime.
 mod weights;
@@ -173,7 +184,8 @@ impl Contains<Call> for BaseFilter {
 			Call::Registrar(_) |
 			Call::Auctions(_) |
 			Call::Crowdloan(_) |
-			Call::BagsList(_) => true,
+			Call::BagsList(_) |
+			Call::XcmPallet(_) => true,
 			// All pallets are allowed, but exhaustive match is defensive
 			// in the case of adding new pallets.
 		}
@@ -1280,6 +1292,154 @@ impl auctions::Config for Runtime {
 	type WeightInfo = weights::runtime_common_auctions::WeightInfo<Runtime>;
 }
 
+parameter_types! {
+	/// The location of the DOT token, from the context of this chain. Since this token is native to this
+	/// chain, we make it synonymous with it and thus it is the `Here` location, which means "equivalent to
+	/// the context".
+	pub const DotLocation: MultiLocation = Here.into();
+	/// The Polkadot network ID. This is named.
+	pub const PolkadotNetwork: NetworkId = NetworkId::Polkadot;
+	/// Our XCM location ancestry - i.e. what, if anything, `Parent` means evaluated in our context. Since
+	/// Polkadot is a top-level relay-chain, there is no ancestry.
+	pub const Ancestry: MultiLocation = Here.into();
+	/// The check account, which holds any native assets that have been teleported out and not back in (yet).
+	pub CheckAccount: AccountId = XcmPallet::check_account();
+}
+
+/// The canonical means of converting a `MultiLocation` into an `AccountId`, used when we want to determine
+/// the sovereign account controlled by a location.
+pub type SovereignAccountOf = (
+	// We can convert a child parachain using the standard `AccountId` conversion.
+	ChildParachainConvertsVia<ParaId, AccountId>,
+	// We can directly alias an `AccountId32` into a local account.
+	AccountId32Aliases<PolkadotNetwork, AccountId>,
+);
+
+/// Our asset transactor. This is what allows us to interest with the runtime facilities from the point of
+/// view of XCM-only concepts like `MultiLocation` and `MultiAsset`.
+///
+/// Ours is only aware of the Balances pallet, which is mapped to `DotLocation`.
+pub type LocalAssetTransactor = XcmCurrencyAdapter<
+	// Use this currency:
+	Balances,
+	// Use this currency when it is a fungible asset matching the given location or name:
+	IsConcrete<DotLocation>,
+	// We can convert the MultiLocations with our converter above:
+	SovereignAccountOf,
+	// Our chain's account ID type (we can't get away without mentioning it explicitly):
+	AccountId,
+	// We track our teleports in/out to keep total issuance correct.
+	CheckAccount,
+>;
+
+/// The means that we convert an the XCM message origin location into a local dispatch origin.
+type LocalOriginConverter = (
+	// A `Signed` origin of the sovereign account that the original location controls.
+	SovereignSignedViaLocation<SovereignAccountOf, Origin>,
+	// A child parachain, natively expressed, has the `Parachain` origin.
+	ChildParachainAsNative<parachains_origin::Origin, Origin>,
+	// The AccountId32 location type can be expressed natively as a `Signed` origin.
+	SignedAccountId32AsNative<PolkadotNetwork, Origin>,
+);
+
+parameter_types! {
+	/// The amount of weight an XCM operation takes. This is a safe overestimate.
+	pub const BaseXcmWeight: Weight = 1_000_000_000;
+	/// Maximum number of instructions in a single XCM fragment. A sanity check against weight
+	/// calculations getting too crazy.
+	pub const MaxInstructions: u32 = 100;
+}
+
+/// The XCM router. When we want to send an XCM message, we use this type. It amalgamates all of our
+/// individual routers.
+pub type XcmRouter = (
+	// Only one router so far - use DMP to communicate with child parachains.
+	xcm_sender::ChildParachainRouter<Runtime, XcmPallet>,
+);
+
+parameter_types! {
+	pub const Polkadot: MultiAssetFilter = Wild(AllOf { fun: WildFungible, id: Concrete(DotLocation::get()) });
+	pub const PolkadotForStatemint: (MultiAssetFilter, MultiLocation) = (Polkadot::get(), Parachain(1000).into());
+}
+
+pub type TrustedTeleporters = (xcm_builder::Case<PolkadotForStatemint>,);
+
+match_type! {
+	pub type OnlyParachains: impl Contains<MultiLocation> = {
+		MultiLocation { parents: 0, interior: X1(Parachain(_)) }
+	};
+}
+
+/// The barriers one of which must be passed for an XCM message to be executed.
+pub type Barrier = (
+	// Weight that is paid for may be consumed.
+	TakeWeightCredit,
+	// If the message is one that immediately attemps to pay for execution, then allow it.
+	AllowTopLevelPaidExecutionFrom<Everything>,
+	// Expected responses are OK.
+	AllowKnownQueryResponses<XcmPallet>,
+	// Subscriptions for version tracking are OK.
+	AllowSubscriptionsFrom<OnlyParachains>,
+);
+
+pub struct XcmConfig;
+impl xcm_executor::Config for XcmConfig {
+	type Call = Call;
+	type XcmSender = XcmRouter;
+	type AssetTransactor = LocalAssetTransactor;
+	type OriginConverter = LocalOriginConverter;
+	type IsReserve = ();
+	type IsTeleporter = TrustedTeleporters;
+	type LocationInverter = LocationInverter<Ancestry>;
+	type Barrier = Barrier;
+	type Weigher = FixedWeightBounds<BaseXcmWeight, Call, MaxInstructions>;
+	// The weight trader piggybacks on the existing transaction-fee conversion logic.
+	type Trader = UsingComponents<WeightToFee, DotLocation, AccountId, Balances, ToAuthor<Runtime>>;
+	type ResponseHandler = XcmPallet;
+	type AssetTrap = XcmPallet;
+	type AssetClaims = XcmPallet;
+	type SubscriptionService = XcmPallet;
+}
+
+parameter_types! {
+	pub const CouncilBodyId: BodyId = BodyId::Executive;
+	// We are conservative with the XCM version we advertize.
+	pub const AdvertisedXcmVersion: u32 = 2;
+}
+
+/// Type to convert an `Origin` type value into a `MultiLocation` value which represents an interior location
+/// of this chain.
+pub type LocalOriginToLocation = (
+	// We allow an origin from the Collective pallet to be used in XCM as a corresponding Plurality of the
+	// `Unit` body.
+	BackingToPlurality<
+		Origin,
+		pallet_collective::Origin<Runtime, CouncilCollective>,
+		CouncilBodyId,
+	>,
+	// And a usual Signed origin to be used in XCM as a corresponding AccountId32
+	SignedToAccountId32<Origin, AccountId, PolkadotNetwork>,
+);
+
+impl pallet_xcm::Config for Runtime {
+	type Event = Event;
+	type SendXcmOrigin = xcm_builder::EnsureXcmOrigin<Origin, LocalOriginToLocation>;
+	type XcmRouter = XcmRouter;
+	// Anyone can execute XCM messages locally...
+	type ExecuteXcmOrigin = xcm_builder::EnsureXcmOrigin<Origin, LocalOriginToLocation>;
+	// ...but they must match our filter, which rejects all.
+	type XcmExecuteFilter = Nothing;
+	type XcmExecutor = XcmExecutor<XcmConfig>;
+	type XcmTeleportFilter = Everything;
+	type XcmReserveTransferFilter = Everything;
+	type Weigher = FixedWeightBounds<BaseXcmWeight, Call, MaxInstructions>;
+	type LocationInverter = LocationInverter<Ancestry>;
+	type Origin = Origin;
+	type Call = Call;
+	const VERSION_DISCOVERY_QUEUE_SIZE: u32 = 100;
+	type AdvertisedXcmVersion = AdvertisedXcmVersion;
+}
+
 construct_runtime! {
 	pub enum Runtime where
 		Block = Block,
@@ -1363,6 +1523,9 @@ construct_runtime! {
 		Slots: slots::{Pallet, Call, Storage, Event<T>} = 71,
 		Auctions: auctions::{Pallet, Call, Storage, Event<T>} = 72,
 		Crowdloan: crowdloan::{Pallet, Call, Storage, Event<T>} = 73,
+
+		// Pallet for sending XCM.
+		XcmPallet: pallet_xcm::{Pallet, Call, Storage, Event<T>, Origin, Config} = 99,
 	}
 }
 
@@ -1905,6 +2068,7 @@ mod test_fees {
 				MaxNominatorRewardedPerValidator::get(),
 			) as f64;
 		let block_weight = BlockWeights::get().max_block as f64;
+
 		println!(
 			"a full payout takes {:.2} of the block weight [{} / {}]",
 			payout_weight / block_weight,