Integrate a governance XCM origin (paritytech#407)

* Introduce the converter into the hub

* Parachain recognises Rococo governance body as admin

* Whitespace

* Use UsingComponents for fee payment in XCM

* Fixes

* Fixes for XCM permissions

* Remove encode_call test

* Fixes

* Fixes

* Fixes

pallets/parachain-system/src/lib.rs

@@ -471,7 +471,7 @@ impl<T: Config> Module<T> {
 			assert_eq!(
 				params.relay_parent_storage_root,
 				validation_data.relay_parent_storage_root,
-				"Relay parent stoarage root doesn't match",
+				"Relay parent storage root doesn't match",
 			);
 		});
 	}
@@ -485,25 +485,38 @@ impl<T: Config> Module<T> {
 		downward_messages: Vec<InboundDownwardMessage>,
 	) -> Result<Weight, DispatchError> {
 		let dm_count = downward_messages.len() as u32;
-
 		let mut weight_used = 0;
 
-		// Reference fu to avoid the `move` capture.
-		let weight_used_mut_ref = &mut weight_used;
-		let result_mqc_head = LastDmqMqcHead::mutate(move |mqc| {
-			for downward_message in downward_messages {
-				mqc.extend_downward(&downward_message);
-				*weight_used_mut_ref += T::DownwardMessageHandlers::handle_downward_message(downward_message);
-			}
-			mqc.0
-		});
+		if dm_count != 0 {
+			let mut processed_count = 0;
 
-		// After hashing each message in the message queue chain submitted by the collator, we should
-		// arrive to the MQC head provided by the relay chain.
-		ensure!(
-			result_mqc_head == expected_dmq_mqc_head,
-			Error::<T>::DmpMqcMismatch
-		);
+			Self::deposit_event(RawEvent::DownwardMessagesReceived(dm_count));
+
+			// Reference fu to avoid the `move` capture.
+			let weight_used_ref = &mut weight_used;
+			let processed_count_ref = &mut processed_count;
+			let result_mqc_head = LastDmqMqcHead::mutate(move |mqc| {
+				for downward_message in downward_messages {
+					mqc.extend_downward(&downward_message);
+					*weight_used_ref += T::DownwardMessageHandlers::handle_downward_message(downward_message);
+					*processed_count_ref += 1;
+				}
+				mqc.0
+			});
+
+			Self::deposit_event(RawEvent::DownwardMessagesProcessed(
+				processed_count,
+				weight_used,
+				result_mqc_head.clone(),
+				expected_dmq_mqc_head.clone(),
+			));
+
+			// After hashing each message in the message queue chain submitted by the collator, we should
+			// arrive to the MQC head provided by the relay chain.
+			assert_eq!(result_mqc_head, expected_dmq_mqc_head);
+		} else {
+			assert_eq!(LastDmqMqcHead::get().0, expected_dmq_mqc_head);
+		}
 
 		// Store the processed_downward_messages here so that it will be accessible from
 		// PVF's `validate_block` wrapper and collation pipeline.
@@ -791,12 +804,18 @@ impl<T: Config> ProvideInherent for Module<T> {
 
 decl_event! {
 	pub enum Event<T> where Hash = <T as frame_system::Config>::Hash {
-		// The validation function has been scheduled to apply as of the contained relay chain block number.
+		/// The validation function has been scheduled to apply as of the contained relay chain block number.
 		ValidationFunctionStored(RelayChainBlockNumber),
-		// The validation function was applied as of the contained relay chain block number.
+		/// The validation function was applied as of the contained relay chain block number.
 		ValidationFunctionApplied(RelayChainBlockNumber),
-		// An upgrade has been authorized.
+		/// An upgrade has been authorized.
 		UpgradeAuthorized(Hash),
+		/// Downward messages were processed using the given weight.
+		/// \[ count, weight_used, result_mqc_head, expected_mqc_head \]
+		DownwardMessagesProcessed(u32, Weight, relay_chain::Hash, relay_chain::Hash),
+		/// Some downward messages have been received and will be processed.
+		/// \[ count \]
+		DownwardMessagesReceived(u32),
 	}
 }
 

pallets/xcm/Cargo.toml

@@ -9,6 +9,7 @@ codec = { package = "parity-scale-codec", version = "2.0.0", default-features =
 serde = { version = "1.0.101", optional = true, features = ["derive"] }
 
 sp-std = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
+sp-io = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 sp-runtime = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 frame-support = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 frame-system = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }

pallets/xcm/src/lib.rs

@@ -20,13 +20,17 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use cumulus_primitives_core::ParaId;
+use sp_std::convert::TryFrom;
+use cumulus_primitives_core::{ParaId, DownwardMessageHandler, InboundDownwardMessage};
 use codec::{Encode, Decode};
 use sp_runtime::traits::BadOrigin;
+use xcm::{VersionedXcm, v0::{Xcm, Junction, Outcome, ExecuteXcm}};
+use frame_support::{traits::Get, dispatch::Weight};
 pub use pallet::*;
 
 #[frame_support::pallet]
 pub mod pallet {
+	use super::*;
 	use frame_support::pallet_prelude::*;
 	use frame_system::pallet_prelude::*;
 
@@ -36,16 +40,68 @@ pub mod pallet {
 
 	/// The module configuration trait.
 	#[pallet::config]
-	pub trait Config: frame_system::Config {}
+	pub trait Config: frame_system::Config {
+		/// The overarching event type.
+		type Event: From<Event<Self>> + IsType<<Self as frame_system::Config>::Event>;
+
+		type XcmExecutor: ExecuteXcm<Self::Call>;
+
+		#[pallet::constant]
+		type MaxWeight: Get<Weight>;
+	}
 
 	#[pallet::error]
-	pub enum Error<T> {}
+	pub enum Error<T> {
+	}
 
 	#[pallet::hooks]
 	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
 
 	#[pallet::call]
 	impl<T: Config> Pallet<T> {}
+
+	#[pallet::event]
+	#[pallet::generate_deposit(pub(super) fn deposit_event)]
+	#[pallet::metadata(T::BlockNumber = "BlockNumber")]
+	pub enum Event<T: Config> {
+		/// Downward message is invalid XCM.
+		/// \[ id \]
+		InvalidFormat([u8; 8]),
+		/// Downward message is unsupported version of XCM.
+		/// \[ id \]
+		UnsupportedVersion([u8; 8]),
+		/// Downward message executed with the given outcome.
+		/// \[ id, outcome \]
+		ExecutedDownward([u8; 8], Outcome),
+	}
+
+	/// For an incoming downward message, this just adapts an XCM executor and executes DMP messages
+	/// immediately up until some `MaxWeight` at which point it errors. Their origin is asserted to be
+	/// the Parent location.
+	impl<T: Config> DownwardMessageHandler for Pallet<T> {
+		fn handle_downward_message(msg: InboundDownwardMessage) -> Weight {
+			let id = sp_io::hashing::twox_64(&msg.msg[..]);
+			let msg = VersionedXcm::<T::Call>::decode(&mut &msg.msg[..])
+				.map(Xcm::<T::Call>::try_from);
+			match msg {
+				Ok(Ok(x)) => {
+					let weight_limit = T::MaxWeight::get();
+					let outcome = T::XcmExecutor::execute_xcm(Junction::Parent.into(), x, weight_limit);
+					let weight_used = outcome.weight_used();
+					Self::deposit_event(Event::ExecutedDownward(id, outcome));
+					weight_used
+				}
+				Ok(Err(())) => {
+					Self::deposit_event(Event::UnsupportedVersion(id));
+					0
+				},
+				Err(_) => {
+					Self::deposit_event(Event::InvalidFormat(id));
+					0
+				},
+			}
+		}
+	}
 }
 
 /// Origin for the parachains module.

rococo-parachains/runtime/Cargo.toml

@@ -27,6 +27,7 @@ sp-inherents = { git = "https://github.com/paritytech/substrate", default-featur
 frame-support = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 frame-executive = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 frame-system = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
+pallet-assets = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 pallet-balances = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 pallet-randomness-collective-flip = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 pallet-timestamp = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
@@ -48,6 +49,10 @@ xcm-builder = { git = "https://github.com/paritytech/polkadot", default-features
 xcm-executor = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
 pallet-xcm = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
 
+[dev-dependencies]
+hex-literal = "0.3.1"
+hex = "0.4.3"
+
 [build-dependencies]
 substrate-wasm-builder = "3.0.0"
 
@@ -71,6 +76,7 @@ std = [
 	"frame-support/std",
 	"frame-executive/std",
 	"frame-system/std",
+	"pallet-assets/std",
 	"pallet-balances/std",
 	"pallet-randomness-collective-flip/std",
 	"pallet-timestamp/std",