XCM v3: Bridge infrastructure (#4681)

* XCM bridge infrastructure * Missing bit of cherry-pick * Revamped XCM proc macros; new NetworkIds * Fixes * Formatting * ExportMessage instruction and config type * Add MessageExporter definitions * Formatting * Missing files * Fixes * Initial bridging config API * Allow for two-stage XCM execution * Update xcm/src/v3/mod.rs Co-authored-by: Keith Yeung <[email protected]> * XCM crate building again * Initial bridging primitive * Docs * Docs * More work * More work * Merge branch 'gav-xcm-v3' into gav-xcm-v3-bridging * Make build * WithComputedOrigin and SovereignPaidRemoteExporter * Remove TODOs * Slim bridge API and tests. * Fixes * More work * First bridge test passing * Formatting * Another test * Next round of bridging tests * Repot tests * Cleanups * Paid bridging * Formatting * Tests * Spelling * Formatting * Fees and refactoring * Fixes * Formatting * Refactor SendXcm to become two-phase * Fix tests * Refactoring of SendXcm and ExportXcm complete * Formatting * Rename CannotReachDestination -> NotApplicable * Remove XCM v0 * Minor grumbles * Formatting * Formatting * Fixes * Fixes * Cleanup XCM config * Fee handling * Fixes * Formatting * Fixes * Bump Co-authored-by: Keith Yeung <[email protected]>
paritytech · Feb 14, 2022 · 6185cf3 · 6185cf3
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diff --git a/Cargo.lock b/Cargo.lock
diff --git a/bridges/primitives/messages/Cargo.toml b/bridges/primitives/messages/Cargo.toml
@@ -9,7 +9,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 [dependencies]
 bitvec = { version = "0.20", default-features = false, features = ["alloc"] }
 codec = { package = "parity-scale-codec", version = "2.2.0", default-features = false, features = ["derive", "bit-vec"] }
-impl-trait-for-tuples = "0.2"
+impl-trait-for-tuples = "0.2.2"
 scale-info = { version = "1.0", default-features = false, features = ["bit-vec", "derive"] }
 serde = { version = "1.0", optional = true, features = ["derive"] }
 

diff --git a/runtime/common/src/xcm_sender.rs b/runtime/common/src/xcm_sender.rs
@@ -17,33 +17,50 @@
 //! XCM sender for relay chain.
 
 use parity_scale_codec::Encode;
-use runtime_parachains::{configuration, dmp};
-use sp_std::marker::PhantomData;
-use xcm::latest::prelude::*;
+use primitives::v1::Id as ParaId;
+use runtime_parachains::{
+	configuration::{self, HostConfiguration},
+	dmp,
+};
+use sp_std::{marker::PhantomData, prelude::*};
+use xcm::prelude::*;
+use SendError::*;
 
 /// XCM sender for relay chain. It only sends downward message.
 pub struct ChildParachainRouter<T, W>(PhantomData<(T, W)>);
 
 impl<T: configuration::Config + dmp::Config, W: xcm::WrapVersion> SendXcm
 	for ChildParachainRouter<T, W>
 {
-	fn send_xcm(dest: impl Into<MultiLocation>, msg: Xcm<()>) -> SendResult {
-		let dest = dest.into();
-		match dest {
-			MultiLocation { parents: 0, interior: X1(Parachain(id)) } => {
-				// Downward message passing.
-				let versioned_xcm =
-					W::wrap_version(&dest, msg).map_err(|()| SendError::DestinationUnsupported)?;
-				let config = <configuration::Pallet<T>>::config();
-				<dmp::Pallet<T>>::queue_downward_message(
-					&config,
-					id.into(),
-					versioned_xcm.encode(),
-				)
-				.map_err(Into::<SendError>::into)?;
-				Ok(())
-			},
-			dest => Err(SendError::CannotReachDestination(dest, msg)),
-		}
+	type Ticket = (HostConfiguration<T::BlockNumber>, ParaId, Vec<u8>);
+
+	fn validate(
+		dest: &mut Option<MultiLocation>,
+		msg: &mut Option<Xcm<()>>,
+	) -> SendResult<(HostConfiguration<T::BlockNumber>, ParaId, Vec<u8>)> {
+		let d = dest.take().ok_or(MissingArgument)?;
+		let id = if let MultiLocation { parents: 0, interior: X1(Parachain(id)) } = &d {
+			*id
+		} else {
+			*dest = Some(d);
+			return Err(NotApplicable)
+		};
+
+		// Downward message passing.
+		let xcm = msg.take().ok_or(MissingArgument)?;
+		let config = <configuration::Pallet<T>>::config();
+		let para = id.into();
+		let blob = W::wrap_version(&d, xcm).map_err(|()| DestinationUnsupported)?.encode();
+		<dmp::Pallet<T>>::can_queue_downward_message(&config, &para, &blob)
+			.map_err(Into::<SendError>::into)?;
+
+		Ok(((config, para, blob), MultiAssets::new()))
+	}
+
+	fn deliver(
+		(config, para, blob): (HostConfiguration<T::BlockNumber>, ParaId, Vec<u8>),
+	) -> Result<(), SendError> {
+		<dmp::Pallet<T>>::queue_downward_message(&config, para, blob)
+			.map_err(|_| SendError::Transport(&"Error placing into DMP queue"))
 	}
 }
diff --git a/runtime/kusama/src/xcm_config.rs b/runtime/kusama/src/xcm_config.rs
@@ -35,17 +35,19 @@ use xcm_builder::{
 	LocationInverter, SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation,
 	TakeWeightCredit, UsingComponents,
 };
+use xcm_executor::XcmExecutor;
 
 parameter_types! {
 	/// The location of the KSM 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 KsmLocation: MultiLocation = Here.into();
+	pub const TokenLocation: MultiLocation = Here.into_location();
 	/// The Kusama network ID. This is named.
-	pub const KusamaNetwork: NetworkId = NetworkId::Kusama;
-	/// Our XCM location ancestry - i.e. what, if anything, `Parent` means evaluated in our context. Since
-	/// Kusama is a top-level relay-chain, there is no ancestry.
-	pub const Ancestry: MultiLocation = Here.into();
+	pub const ThisNetwork: NetworkId = Kusama;
+	/// Our XCM location ancestry - i.e. our location within the Consensus Universe.
+	///
+	/// Since Kusama is a top-level relay-chain with its own consensus, it's just our network ID.
+	pub UniversalLocation: InteriorMultiLocation = ThisNetwork::get().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();
 }
@@ -56,18 +58,18 @@ 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<KusamaNetwork, AccountId>,
+	AccountId32Aliases<ThisNetwork, 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 `KsmLocation`.
+/// Ours is only aware of the Balances pallet, which is mapped to `TokenLocation`.
 pub type LocalAssetTransactor = XcmCurrencyAdapter<
 	// Use this currency:
 	Balances,
 	// Use this currency when it is a fungible asset matching the given location or name:
-	IsConcrete<KsmLocation>,
+	IsConcrete<TokenLocation>,
 	// 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):
@@ -76,14 +78,14 @@ pub type LocalAssetTransactor = XcmCurrencyAdapter<
 	CheckAccount,
 >;
 
-/// The means that we convert an the XCM message origin location into a local dispatch origin.
+/// The means that we convert 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<KusamaNetwork, Origin>,
+	SignedAccountId32AsNative<ThisNetwork, Origin>,
 	// A system child parachain, expressed as a Superuser, converts to the `Root` origin.
 	ChildSystemParachainAsSuperuser<ParaId, Origin>,
 );
@@ -104,13 +106,13 @@ pub type XcmRouter = (
 );
 
 parameter_types! {
-	pub const Kusama: MultiAssetFilter = Wild(AllOf { fun: WildFungible, id: Concrete(KsmLocation::get()) });
-	pub const KusamaForStatemine: (MultiAssetFilter, MultiLocation) = (Kusama::get(), Parachain(1000).into());
-	pub const KusamaForEncointer: (MultiAssetFilter, MultiLocation) = (Kusama::get(), Parachain(1001).into());
+	pub const Ksm: MultiAssetFilter = Wild(AllOf { fun: WildFungible, id: Concrete(TokenLocation::get()) });
+	pub const KsmForStatemine: (MultiAssetFilter, MultiLocation) = (Ksm::get(), Parachain(1000).into_location());
+	pub const KsmForEncointer: (MultiAssetFilter, MultiLocation) = (Ksm::get(), Parachain(1001).into_location());
 	pub const MaxAssetsIntoHolding: u32 = 64;
 }
 pub type TrustedTeleporters =
-	(xcm_builder::Case<KusamaForStatemine>, xcm_builder::Case<KusamaForEncointer>);
+	(xcm_builder::Case<KsmForStatemine>, xcm_builder::Case<KsmForEncointer>);
 
 match_type! {
 	pub type OnlyParachains: impl Contains<MultiLocation> = {
@@ -140,17 +142,22 @@ impl xcm_executor::Config for XcmConfig {
 	type OriginConverter = LocalOriginConverter;
 	type IsReserve = ();
 	type IsTeleporter = TrustedTeleporters;
-	type LocationInverter = LocationInverter<Ancestry>;
+	type LocationInverter = LocationInverter<UniversalLocation>;
 	type Barrier = Barrier;
 	type Weigher = FixedWeightBounds<BaseXcmWeight, Call, MaxInstructions>;
 	// The weight trader piggybacks on the existing transaction-fee conversion logic.
-	type Trader = UsingComponents<WeightToFee, KsmLocation, AccountId, Balances, ToAuthor<Runtime>>;
+	type Trader =
+		UsingComponents<WeightToFee, TokenLocation, AccountId, Balances, ToAuthor<Runtime>>;
 	type ResponseHandler = XcmPallet;
 	type AssetTrap = XcmPallet;
 	type AssetClaims = XcmPallet;
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
+	type FeeManager = ();
+	// No bridges yet...
+	type MessageExporter = ();
+	type UniversalAliases = Nothing;
 }
 
 parameter_types! {
@@ -168,8 +175,9 @@ pub type LocalOriginToLocation = (
 		CouncilBodyId,
 	>,
 	// And a usual Signed origin to be used in XCM as a corresponding AccountId32
-	SignedToAccountId32<Origin, AccountId, KusamaNetwork>,
+	SignedToAccountId32<Origin, AccountId, ThisNetwork>,
 );
+
 impl pallet_xcm::Config for Runtime {
 	type Event = Event;
 	type SendXcmOrigin = xcm_builder::EnsureXcmOrigin<Origin, LocalOriginToLocation>;
@@ -178,11 +186,11 @@ impl pallet_xcm::Config for Runtime {
 	type ExecuteXcmOrigin = xcm_builder::EnsureXcmOrigin<Origin, LocalOriginToLocation>;
 	// ...but they must match our filter, which rejects all.
 	type XcmExecuteFilter = Nothing;
-	type XcmExecutor = xcm_executor::XcmExecutor<XcmConfig>;
+	type XcmExecutor = XcmExecutor<XcmConfig>;
 	type XcmTeleportFilter = Everything;
 	type XcmReserveTransferFilter = Everything;
 	type Weigher = FixedWeightBounds<BaseXcmWeight, Call, MaxInstructions>;
-	type LocationInverter = LocationInverter<Ancestry>;
+	type LocationInverter = LocationInverter<UniversalLocation>;
 	type Origin = Origin;
 	type Call = Call;
 	const VERSION_DISCOVERY_QUEUE_SIZE: u32 = 100;

diff --git a/runtime/parachains/src/dmp.rs b/runtime/parachains/src/dmp.rs
@@ -137,6 +137,21 @@ impl<T: Config> Pallet<T> {
 		<Self as Store>::DownwardMessageQueueHeads::remove(outgoing_para);
 	}
 
+	/// Determine whether enqueuing a downward message to a specific recipient para would result
+	/// in an error. If this returns `Ok(())` the caller can be certain that a call to
+	/// `queue_downward_message` with the same parameters will be successful.
+	pub fn can_queue_downward_message(
+		config: &HostConfiguration<T::BlockNumber>,
+		_para: &ParaId,
+		msg: &DownwardMessage,
+	) -> Result<(), QueueDownwardMessageError> {
+		let serialized_len = msg.len() as u32;
+		if serialized_len > config.max_downward_message_size {
+			return Err(QueueDownwardMessageError::ExceedsMaxMessageSize)
+		}
+		Ok(())
+	}
+
 	/// Enqueue a downward message to a specific recipient para.
 	///
 	/// When encoded, the message should not exceed the `config.max_downward_message_size`.

diff --git a/runtime/polkadot/src/xcm_config.rs b/runtime/polkadot/src/xcm_config.rs
@@ -34,17 +34,17 @@ use xcm_builder::{
 	IsConcrete, LocationInverter, SignedAccountId32AsNative, SignedToAccountId32,
 	SovereignSignedViaLocation, TakeWeightCredit, UsingComponents,
 };
+use xcm_executor::XcmExecutor;
 
 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();
+	pub const TokenLocation: MultiLocation = Here.into_location();
 	/// 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();
+	pub const ThisNetwork: NetworkId = NetworkId::Polkadot;
+	/// Our location in the universe of consensus systems.
+	pub const UniversalLocation: InteriorMultiLocation = X1(GlobalConsensus(ThisNetwork::get()));
 	/// The check account, which holds any native assets that have been teleported out and not back in (yet).
 	pub CheckAccount: AccountId = XcmPallet::check_account();
 }
@@ -55,18 +55,18 @@ 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>,
+	AccountId32Aliases<ThisNetwork, 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`.
+/// Ours is only aware of the Balances pallet, which is mapped to `TokenLocation`.
 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>,
+	IsConcrete<TokenLocation>,
 	// 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):
@@ -82,7 +82,7 @@ type LocalOriginConverter = (
 	// 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>,
+	SignedAccountId32AsNative<ThisNetwork, Origin>,
 );
 
 parameter_types! {
@@ -101,12 +101,12 @@ pub type XcmRouter = (
 );
 
 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 const Dot: MultiAssetFilter = Wild(AllOf { fun: WildFungible, id: Concrete(TokenLocation::get()) });
+	pub const DotForStatemint: (MultiAssetFilter, MultiLocation) = (Dot::get(), Parachain(1000).into_location());
 	pub const MaxAssetsIntoHolding: u32 = 64;
 }
 
-pub type TrustedTeleporters = (xcm_builder::Case<PolkadotForStatemint>,);
+pub type TrustedTeleporters = (xcm_builder::Case<DotForStatemint>,);
 
 match_type! {
 	pub type OnlyParachains: impl Contains<MultiLocation> = {
@@ -134,23 +134,26 @@ impl xcm_executor::Config for XcmConfig {
 	type OriginConverter = LocalOriginConverter;
 	type IsReserve = ();
 	type IsTeleporter = TrustedTeleporters;
-	type LocationInverter = LocationInverter<Ancestry>;
+	type LocationInverter = LocationInverter<UniversalLocation>;
 	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 Trader =
+		UsingComponents<WeightToFee, TokenLocation, AccountId, Balances, ToAuthor<Runtime>>;
 	type ResponseHandler = XcmPallet;
 	type AssetTrap = XcmPallet;
 	type AssetClaims = XcmPallet;
 	type SubscriptionService = XcmPallet;
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
+	type FeeManager = ();
+	// No bridges yet...
+	type MessageExporter = ();
+	type UniversalAliases = Nothing;
 }
 
 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
@@ -164,7 +167,7 @@ pub type LocalOriginToLocation = (
 		CouncilBodyId,
 	>,
 	// And a usual Signed origin to be used in XCM as a corresponding AccountId32
-	SignedToAccountId32<Origin, AccountId, PolkadotNetwork>,
+	SignedToAccountId32<Origin, AccountId, ThisNetwork>,
 );
 
 impl pallet_xcm::Config for Runtime {
@@ -175,13 +178,13 @@ impl pallet_xcm::Config for Runtime {
 	type ExecuteXcmOrigin = xcm_builder::EnsureXcmOrigin<Origin, LocalOriginToLocation>;
 	// ...but they must match our filter, which rejects all.
 	type XcmExecuteFilter = Nothing;
-	type XcmExecutor = xcm_executor::XcmExecutor<XcmConfig>;
+	type XcmExecutor = XcmExecutor<XcmConfig>;
 	type XcmTeleportFilter = Nothing;
 	type XcmReserveTransferFilter = Nothing;
 	type Weigher = FixedWeightBounds<BaseXcmWeight, Call, MaxInstructions>;
-	type LocationInverter = LocationInverter<Ancestry>;
+	type LocationInverter = LocationInverter<UniversalLocation>;
 	type Origin = Origin;
 	type Call = Call;
 	const VERSION_DISCOVERY_QUEUE_SIZE: u32 = 100;
-	type AdvertisedXcmVersion = AdvertisedXcmVersion;
+	type AdvertisedXcmVersion = pallet_xcm::CurrentXcmVersion;
 }