Add Basic XCM (#1934)

* basic setup

* fix compile

* add back xcmsink

* Update primitives.rs

* add downward xcm for sudo

* Update paras_sudo_wrapper.rs

* Update Cargo.lock

* some cleanups

* Add error log

Co-authored-by: Sergei Shulepov <sergei@parity.io>

polkadot/Cargo.lock

@@ -5509,6 +5509,7 @@ dependencies = [
  "sp-trie",
  "static_assertions",
  "trie-db",
+ "xcm",
 ]
 
 [[package]]
@@ -5558,6 +5559,7 @@ dependencies = [
  "sp-trie",
  "sp-version",
  "xcm",
+ "xcm-executor",
 ]
 
 [[package]]
@@ -6535,6 +6537,9 @@ dependencies = [
  "sp-transaction-pool",
  "sp-version",
  "substrate-wasm-builder",
+ "xcm",
+ "xcm-builder",
+ "xcm-executor",
 ]
 
 [[package]]

polkadot/runtime/common/Cargo.toml

@@ -39,6 +39,8 @@ primitives = { package = "polkadot-primitives", path = "../../primitives", defau
 libsecp256k1 = { version = "0.3.5", default-features = false, optional = true }
 runtime-parachains = { package = "polkadot-runtime-parachains", path = "../parachains", default-features = false }
 
+xcm = { path = "../../xcm", default-features = false }
+
 [dev-dependencies]
 hex-literal = "0.3.1"
 keyring = { package = "sp-keyring", git = "https://github.com/paritytech/substrate", branch = "master" }
@@ -81,6 +83,7 @@ std = [
 	"pallet-vesting/std",
 	"pallet-transaction-payment/std",
 	"runtime-parachains/std",
+	"xcm/std",
 ]
 runtime-benchmarks = [
 	"libsecp256k1/hmac",

polkadot/runtime/common/src/paras_sudo_wrapper.rs

@@ -28,6 +28,7 @@ use runtime_parachains::{
 	configuration, dmp, ump, hrmp, paras::{self, ParaGenesisArgs},
 };
 use primitives::v1::Id as ParaId;
+use parity_scale_codec::Encode;
 
 /// The module's configuration trait.
 pub trait Config:
@@ -73,16 +74,16 @@ decl_module! {
 			Ok(())
 		}
 
-		/// Send a downward message to the given para.
+		/// Send a downward XCM to the given para.
 		///
 		/// The given parachain should exist and the payload should not exceed the preconfigured size
 		/// `config.max_downward_message_size`.
 		#[weight = (1_000, DispatchClass::Operational)]
-		pub fn sudo_queue_downward_message(origin, id: ParaId, payload: Vec<u8>) -> DispatchResult {
+		pub fn sudo_queue_downward_xcm(origin, id: ParaId, xcm: xcm::VersionedXcm) -> DispatchResult {
 			ensure_root(origin)?;
 			ensure!(<paras::Module<T>>::is_valid_para(id), Error::<T>::ParaDoesntExist);
 			let config = <configuration::Module<T>>::config();
-			<dmp::Module<T>>::queue_downward_message(&config, id, payload)
+			<dmp::Module<T>>::queue_downward_message(&config, id, xcm.encode())
 				.map_err(|e| match e {
 					dmp::QueueDownwardMessageError::ExceedsMaxMessageSize =>
 						Error::<T>::ExceedsMaxMessageSize.into(),

polkadot/runtime/parachains/Cargo.toml

@@ -35,6 +35,7 @@ pallet-offences = { git = "https://github.com/paritytech/substrate", branch = "m
 frame-benchmarking = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false, optional = true }
 
 xcm = { package = "xcm", path = "../../xcm", default-features = false }
+xcm-executor = { package = "xcm-executor", path = "../../xcm/xcm-executor", default-features = false }
 primitives = { package = "polkadot-primitives", path = "../../primitives", default-features = false }
 libsecp256k1 = { version = "0.3.5", default-features = false, optional = true }
 
@@ -84,6 +85,7 @@ std = [
 	"pallet-timestamp/std",
 	"pallet-vesting/std",
 	"xcm/std",
+	"xcm-executor/std",
 ]
 runtime-benchmarks = [
 	"libsecp256k1/hmac",

polkadot/runtime/parachains/src/ump.rs

@@ -52,6 +52,42 @@ impl UmpSink for () {
 	}
 }
 
+/// A specific implementation of a UmpSink where messages are in the XCM format
+/// and will be forwarded to the XCM Executor.
+pub struct XcmSink<Config>(sp_std::marker::PhantomData<Config>);
+
+impl<Config: xcm_executor::Config> UmpSink for XcmSink<Config> {
+	fn process_upward_message(origin: ParaId, msg: Vec<u8>) -> Weight {
+		use parity_scale_codec::Decode;
+		use xcm::VersionedXcm;
+		use xcm::v0::{Junction, MultiLocation, ExecuteXcm};
+		use xcm_executor::XcmExecutor;
+
+		let weight: Weight = 0;
+
+		if let Ok(versioned_xcm_message) = VersionedXcm::decode(&mut &msg[..]) {
+			match versioned_xcm_message {
+				VersionedXcm::V0(xcm_message) => {
+					let xcm_junction: Junction = Junction::Parachain { id: origin.into() };
+					let xcm_location: MultiLocation = xcm_junction.into();
+					// TODO: Do something with result.
+					let _result = XcmExecutor::<Config>::execute_xcm(xcm_location, xcm_message);
+				}
+			}
+		} else {
+			frame_support::debug::error!(
+				target: "xcm",
+				"Failed to decode versioned XCM from upward message.",
+			);
+		}
+
+		// TODO: to be sound, this implementation must ensure that returned (and thus consumed)
+		// weight is limited to some small portion of the total block weight (as a ballpark, 1/4, 1/8
+		// or lower).
+		weight
+	}
+}
+
 /// An error returned by [`check_upward_messages`] that indicates a violation of one of acceptance
 /// criteria rules.
 pub enum AcceptanceCheckErr {

polkadot/runtime/rococo/Cargo.toml

@@ -53,6 +53,10 @@ primitives = { package = "polkadot-primitives", path = "../../primitives", defau
 polkadot-parachain = { path = "../../parachain", default-features = false }
 runtime-parachains = { package = "polkadot-runtime-parachains", path = "../parachains", 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 }
+
 [build-dependencies]
 substrate-wasm-builder = "3.0.0"
 
@@ -99,6 +103,9 @@ std = [
 	"sp-version/std",
 	"serde_derive",
 	"serde/std",
+	"xcm/std",
+	"xcm-executor/std",
+	"xcm-builder/std",
 ]
 # When enabled, the runtime api will not be build.
 #

polkadot/runtime/rococo/src/lib.rs

@@ -82,6 +82,15 @@ use runtime_parachains::scheduler as parachains_scheduler;
 pub use pallet_balances::Call as BalancesCall;
 pub use pallet_staking::StakerStatus;
 
+use polkadot_parachain::primitives::Id as ParaId;
+use xcm::v0::{MultiLocation, NetworkId};
+use xcm_executor::traits::IsConcrete;
+use xcm_builder::{
+	AccountId32Aliases, ChildParachainConvertsVia, SovereignSignedViaLocation,
+	CurrencyAdapter as XcmCurrencyAdapter, ChildParachainAsNative,
+	SignedAccountId32AsNative, ChildSystemParachainAsSuperuser, LocationInverter,
+};
+
 /// Constant values used within the runtime.
 pub mod constants;
 use constants::{time::*, currency::*, fee::*};
@@ -535,10 +544,51 @@ impl parachains_paras::Config for Runtime {
 	type Origin = Origin;
 }
 
+parameter_types! {
+	pub const RocLocation: MultiLocation = MultiLocation::Null;
+	pub const RococoNetwork: NetworkId = NetworkId::Polkadot;
+	pub const Ancestry: MultiLocation = MultiLocation::Null;
+}
+
+pub type LocationConverter = (
+	ChildParachainConvertsVia<ParaId, AccountId>,
+	AccountId32Aliases<RococoNetwork, AccountId>,
+);
+
+pub type LocalAssetTransactor =
+	XcmCurrencyAdapter<
+		// Use this currency:
+		Balances,
+		// Use this currency when it is a fungible asset matching the given location or name:
+		IsConcrete<RocLocation>,
+		// We can convert the MultiLocations with our converter above:
+		LocationConverter,
+		// Our chain's account ID type (we can't get away without mentioning it explicitly):
+		AccountId,
+	>;
+
+type LocalOriginConverter = (
+	SovereignSignedViaLocation<LocationConverter, Origin>,
+	ChildParachainAsNative<parachains_origin::Origin, Origin>,
+	SignedAccountId32AsNative<RococoNetwork, Origin>,
+	ChildSystemParachainAsSuperuser<ParaId, Origin>,
+);
+
+pub struct XcmConfig;
+impl xcm_executor::Config for XcmConfig {
+	type Call = Call;
+	type XcmSender = ();
+	type AssetTransactor = LocalAssetTransactor;
+	type OriginConverter = LocalOriginConverter;
+	type IsReserve = ();
+	type IsTeleporter = ();
+	type LocationInverter = LocationInverter<Ancestry>;
+}
+
 impl parachains_session_info::Config for Runtime {}
 
 impl parachains_ump::Config for Runtime {
-	type UmpSink = (); // TODO: #1873 To be handled by the XCM receiver.
+	type UmpSink = crate::parachains_ump::XcmSink<XcmConfig>;
 }
 
 impl parachains_dmp::Config for Runtime {}