BEEFY: introduce offence report system (#13564)

* Trivial adjustments to beefy and grandpa pallets

* Introduce offence report system to beefy pallet

* Minor adjustments

* Fix beefy-mmr mock

* Apply suggestions from code review

Co-authored-by: Anton <anton.kalyaev@gmail.com>

---------

Co-authored-by: Anton <anton.kalyaev@gmail.com>

substrate/frame/grandpa/src/equivocation.rs

@@ -57,7 +57,7 @@ use super::{Call, Config, Error, Pallet, LOG_TARGET};
 
 /// A round number and set id which point on the time of an offence.
 #[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Encode, Decode)]
-pub struct GrandpaTimeSlot {
+pub struct TimeSlot {
 	// The order of these matters for `derive(Ord)`.
 	/// Grandpa Set ID.
 	pub set_id: SetId,
@@ -65,10 +65,10 @@ pub struct GrandpaTimeSlot {
 	pub round: RoundNumber,
 }
 
-/// A GRANDPA equivocation offence report.
+/// GRANDPA equivocation offence report.
 pub struct EquivocationOffence<Offender> {
 	/// Time slot at which this incident happened.
-	pub time_slot: GrandpaTimeSlot,
+	pub time_slot: TimeSlot,
 	/// The session index in which the incident happened.
 	pub session_index: SessionIndex,
 	/// The size of the validator set at the time of the offence.
@@ -79,7 +79,7 @@ pub struct EquivocationOffence<Offender> {
 
 impl<Offender: Clone> Offence<Offender> for EquivocationOffence<Offender> {
 	const ID: Kind = *b"grandpa:equivoca";
-	type TimeSlot = GrandpaTimeSlot;
+	type TimeSlot = TimeSlot;
 
 	fn offenders(&self) -> Vec<Offender> {
 		vec![self.offender.clone()]
@@ -105,15 +105,16 @@ impl<Offender: Clone> Offence<Offender> for EquivocationOffence<Offender> {
 	}
 }
 
-/// Generic equivocation handler. This type implements `HandleEquivocation`
-/// using existing subsystems that are part of frame (type bounds described
-/// below) and will dispatch to them directly, it's only purpose is to wire all
-/// subsystems together.
+/// GRANDPA equivocation offence report system.
+///
+/// This type implements `OffenceReportSystem` such that:
+/// - Equivocation reports are published on-chain as unsigned extrinsic via
+///   `offchain::SendTransactioinsTypes`.
+/// - On-chain validity checks and processing are mostly delegated to the user provided generic
+///   types implementing `KeyOwnerProofSystem` and `ReportOffence` traits.
+/// - Offence reporter for unsigned transactions is fetched via the the authorship pallet.
 pub struct EquivocationReportSystem<T, R, P, L>(sp_std::marker::PhantomData<(T, R, P, L)>);
 
-// We use the authorship pallet to fetch the current block author and use
-// `offchain::SendTransactionTypes` for unsigned extrinsic creation and
-// submission.
 impl<T, R, P, L>
 	OffenceReportSystem<
 		Option<T::AccountId>,
@@ -144,7 +145,7 @@ where
 		};
 		let res = SubmitTransaction::<T, Call<T>>::submit_unsigned_transaction(call.into());
 		match res {
-			Ok(()) => info!(target: LOG_TARGET, "Submitted equivocation report."),
+			Ok(_) => info!(target: LOG_TARGET, "Submitted equivocation report"),
 			Err(e) => error!(target: LOG_TARGET, "Error submitting equivocation report: {:?}", e),
 		}
 		res
@@ -160,10 +161,8 @@ where
 		let offender = P::check_proof(key, key_owner_proof).ok_or(InvalidTransaction::BadProof)?;
 
 		// Check if the offence has already been reported, and if so then we can discard the report.
-		let time_slot = GrandpaTimeSlot {
-			set_id: equivocation_proof.set_id(),
-			round: equivocation_proof.round(),
-		};
+		let time_slot =
+			TimeSlot { set_id: equivocation_proof.set_id(), round: equivocation_proof.round() };
 		if R::is_known_offence(&[offender], &time_slot) {
 			Err(InvalidTransaction::Stale.into())
 		} else {
@@ -221,7 +220,7 @@ where
 		}
 
 		let offence = EquivocationOffence {
-			time_slot: GrandpaTimeSlot { set_id, round },
+			time_slot: TimeSlot { set_id, round },
 			session_index,
 			offender,
 			validator_set_count,

substrate/frame/grandpa/src/lib.rs

@@ -63,7 +63,7 @@ mod mock;
 #[cfg(all(feature = "std", test))]
 mod tests;
 
-pub use equivocation::{EquivocationOffence, EquivocationReportSystem, GrandpaTimeSlot};
+pub use equivocation::{EquivocationOffence, EquivocationReportSystem, TimeSlot};
 
 pub use pallet::*;
 
@@ -351,6 +351,7 @@ pub mod pallet {
 	#[pallet::validate_unsigned]
 	impl<T: Config> ValidateUnsigned for Pallet<T> {
 		type Call = Call<T>;
+
 		fn validate_unsigned(source: TransactionSource, call: &Self::Call) -> TransactionValidity {
 			Self::validate_unsigned(source, call)
 		}

substrate/frame/grandpa/src/mock.rs

@@ -224,13 +224,10 @@ parameter_types! {
 
 impl Config for Test {
 	type RuntimeEvent = RuntimeEvent;
-
 	type WeightInfo = ();
 	type MaxAuthorities = ConstU32<100>;
 	type MaxSetIdSessionEntries = MaxSetIdSessionEntries;
-
 	type KeyOwnerProof = <Historical as KeyOwnerProofSystem<(KeyTypeId, AuthorityId)>>::Proof;
-
 	type EquivocationReportSystem =
 		super::EquivocationReportSystem<Self, Offences, Historical, ReportLongevity>;
 }

substrate/frame/grandpa/src/tests.rs

@@ -296,12 +296,12 @@ fn schedule_resume_only_when_paused() {
 #[test]
 fn time_slot_have_sane_ord() {
 	// Ensure that `Ord` implementation is sane.
-	const FIXTURE: &[GrandpaTimeSlot] = &[
-		GrandpaTimeSlot { set_id: 0, round: 0 },
-		GrandpaTimeSlot { set_id: 0, round: 1 },
-		GrandpaTimeSlot { set_id: 1, round: 0 },
-		GrandpaTimeSlot { set_id: 1, round: 1 },
-		GrandpaTimeSlot { set_id: 1, round: 2 },
+	const FIXTURE: &[TimeSlot] = &[
+		TimeSlot { set_id: 0, round: 0 },
+		TimeSlot { set_id: 0, round: 1 },
+		TimeSlot { set_id: 1, round: 0 },
+		TimeSlot { set_id: 1, round: 1 },
+		TimeSlot { set_id: 1, round: 2 },
 	];
 	assert!(FIXTURE.windows(2).all(|f| f[0] < f[1]));
 }