Add equivocation detector crate and implement clients (#2348) (#2353)

* Split FinalitySyncPipeline and SourceClient

* Move some logic to finality_base

* Add empty equivocation detection clients

* Add equivocation reporting logic to the source client

* Use convenience trait for SubstrateFinalitySyncPipeline

* Define JustificationVerificationContext for GRANDPA

* Equivocation source client: finality_verification_context()

* Equivocation source client: synced_headers_finality_info()

* reuse HeaderFinalityInfo

* Define EquivocationsFinder

* Fix spellcheck

* Address review comments

* Avoid equivocations lookup errors

bridges/bin/millau/runtime/src/lib.rs

@@ -884,7 +884,7 @@ impl_runtime_apis! {
 		}
 
 		fn synced_headers_grandpa_info(
-		) -> Vec<bp_header_chain::HeaderGrandpaInfo<bp_rialto::Header>> {
+		) -> Vec<bp_header_chain::StoredHeaderGrandpaInfo<bp_rialto::Header>> {
 			BridgeRialtoGrandpa::synced_headers_grandpa_info()
 		}
 	}
@@ -895,7 +895,7 @@ impl_runtime_apis! {
 		}
 
 		fn synced_headers_grandpa_info(
-		) -> Vec<bp_header_chain::HeaderGrandpaInfo<bp_westend::Header>> {
+		) -> Vec<bp_header_chain::StoredHeaderGrandpaInfo<bp_westend::Header>> {
 			BridgeWestendGrandpa::synced_headers_grandpa_info()
 		}
 	}

bridges/bin/rialto-parachain/runtime/src/lib.rs

@@ -748,7 +748,7 @@ impl_runtime_apis! {
 		}
 
 		fn synced_headers_grandpa_info(
-		) -> Vec<bp_header_chain::HeaderGrandpaInfo<bp_millau::Header>> {
+		) -> Vec<bp_header_chain::StoredHeaderGrandpaInfo<bp_millau::Header>> {
 			BridgeMillauGrandpa::synced_headers_grandpa_info()
 		}
 	}

bridges/bin/rialto/runtime/src/lib.rs

@@ -696,7 +696,7 @@ impl_runtime_apis! {
 		}
 
 		fn synced_headers_grandpa_info(
-		) -> Vec<bp_header_chain::HeaderGrandpaInfo<bp_millau::Header>> {
+		) -> Vec<bp_header_chain::StoredHeaderGrandpaInfo<bp_millau::Header>> {
 			BridgeMillauGrandpa::synced_headers_grandpa_info()
 		}
 	}

bridges/modules/grandpa/src/lib.rs

@@ -40,10 +40,10 @@ pub use storage_types::StoredAuthoritySet;
 
 use bp_header_chain::{
 	justification::GrandpaJustification, AuthoritySet, ChainWithGrandpa, GrandpaConsensusLogReader,
-	HeaderChain, HeaderGrandpaInfo, InitializationData, StoredHeaderData, StoredHeaderDataBuilder,
+	HeaderChain, InitializationData, StoredHeaderData, StoredHeaderDataBuilder,
+	StoredHeaderGrandpaInfo,
 };
 use bp_runtime::{BlockNumberOf, HashOf, HasherOf, HeaderId, HeaderOf, OwnedBridgeModule};
-use finality_grandpa::voter_set::VoterSet;
 use frame_support::{dispatch::PostDispatchInfo, ensure, DefaultNoBound};
 use sp_runtime::{
 	traits::{Header as HeaderT, Zero},
@@ -241,9 +241,9 @@ pub mod pallet {
 			Self::deposit_event(Event::UpdatedBestFinalizedHeader {
 				number,
 				hash,
-				grandpa_info: HeaderGrandpaInfo {
-					justification,
-					authority_set: maybe_new_authority_set,
+				grandpa_info: StoredHeaderGrandpaInfo {
+					finality_proof: justification,
+					new_verification_context: maybe_new_authority_set,
 				},
 			});
 
@@ -411,7 +411,7 @@ pub mod pallet {
 			number: BridgedBlockNumber<T, I>,
 			hash: BridgedBlockHash<T, I>,
 			/// The Grandpa info associated to the new best finalized header.
-			grandpa_info: HeaderGrandpaInfo<BridgedHeader<T, I>>,
+			grandpa_info: StoredHeaderGrandpaInfo<BridgedHeader<T, I>>,
 		},
 	}
 
@@ -505,14 +505,9 @@ pub mod pallet {
 	) -> Result<(), sp_runtime::DispatchError> {
 		use bp_header_chain::justification::verify_justification;
 
-		let voter_set =
-			VoterSet::new(authority_set.authorities).ok_or(<Error<T, I>>::InvalidAuthoritySet)?;
-		let set_id = authority_set.set_id;
-
 		Ok(verify_justification::<BridgedHeader<T, I>>(
 			(hash, number),
-			set_id,
-			&voter_set,
+			&authority_set.try_into().map_err(|_| <Error<T, I>>::InvalidAuthoritySet)?,
 			justification,
 		)
 		.map_err(|e| {
@@ -617,7 +612,7 @@ where
 	<T as frame_system::Config>::RuntimeEvent: TryInto<Event<T, I>>,
 {
 	/// Get the GRANDPA justifications accepted in the current block.
-	pub fn synced_headers_grandpa_info() -> Vec<HeaderGrandpaInfo<BridgedHeader<T, I>>> {
+	pub fn synced_headers_grandpa_info() -> Vec<StoredHeaderGrandpaInfo<BridgedHeader<T, I>>> {
 		frame_system::Pallet::<T>::read_events_no_consensus()
 			.filter_map(|event| {
 				if let Event::<T, I>::UpdatedBestFinalizedHeader { grandpa_info, .. } =
@@ -934,17 +929,20 @@ mod tests {
 					event: TestEvent::Grandpa(Event::UpdatedBestFinalizedHeader {
 						number: *header.number(),
 						hash: header.hash(),
-						grandpa_info: HeaderGrandpaInfo {
-							justification: justification.clone(),
-							authority_set: None,
+						grandpa_info: StoredHeaderGrandpaInfo {
+							finality_proof: justification.clone(),
+							new_verification_context: None,
 						},
 					}),
 					topics: vec![],
 				}],
 			);
 			assert_eq!(
 				Pallet::<TestRuntime>::synced_headers_grandpa_info(),
-				vec![HeaderGrandpaInfo { justification, authority_set: None }]
+				vec![StoredHeaderGrandpaInfo {
+					finality_proof: justification,
+					new_verification_context: None
+				}]
 			);
 		})
 	}
@@ -1075,19 +1073,23 @@ mod tests {
 					event: TestEvent::Grandpa(Event::UpdatedBestFinalizedHeader {
 						number: *header.number(),
 						hash: header.hash(),
-						grandpa_info: HeaderGrandpaInfo {
-							justification: justification.clone(),
-							authority_set: Some(<CurrentAuthoritySet<TestRuntime>>::get().into()),
+						grandpa_info: StoredHeaderGrandpaInfo {
+							finality_proof: justification.clone(),
+							new_verification_context: Some(
+								<CurrentAuthoritySet<TestRuntime>>::get().into()
+							),
 						},
 					}),
 					topics: vec![],
 				}],
 			);
 			assert_eq!(
 				Pallet::<TestRuntime>::synced_headers_grandpa_info(),
-				vec![HeaderGrandpaInfo {
-					justification,
-					authority_set: Some(<CurrentAuthoritySet<TestRuntime>>::get().into()),
+				vec![StoredHeaderGrandpaInfo {
+					finality_proof: justification,
+					new_verification_context: Some(
+						<CurrentAuthoritySet<TestRuntime>>::get().into()
+					),
 				}]
 			);
 		})

bridges/modules/parachains/src/lib.rs

@@ -697,7 +697,7 @@ pub(crate) mod tests {
 	use bp_test_utils::prepare_parachain_heads_proof;
 	use codec::Encode;
 
-	use bp_header_chain::{justification::GrandpaJustification, HeaderGrandpaInfo};
+	use bp_header_chain::{justification::GrandpaJustification, StoredHeaderGrandpaInfo};
 	use bp_parachains::{
 		BestParaHeadHash, BridgeParachainCall, ImportedParaHeadsKeyProvider, ParasInfoKeyProvider,
 	};
@@ -1036,9 +1036,9 @@ pub(crate) mod tests {
 							pallet_bridge_grandpa::Event::UpdatedBestFinalizedHeader {
 								number: 1,
 								hash: relay_1_hash,
-								grandpa_info: HeaderGrandpaInfo {
-									justification,
-									authority_set: None,
+								grandpa_info: StoredHeaderGrandpaInfo {
+									finality_proof: justification,
+									new_verification_context: None,
 								},
 							}
 						),
@@ -1177,9 +1177,9 @@ pub(crate) mod tests {
 							pallet_bridge_grandpa::Event::UpdatedBestFinalizedHeader {
 								number: 1,
 								hash: relay_1_hash,
-								grandpa_info: HeaderGrandpaInfo {
-									justification,
-									authority_set: None,
+								grandpa_info: StoredHeaderGrandpaInfo {
+									finality_proof: justification,
+									new_verification_context: None,
 								}
 							}
 						),
@@ -1230,9 +1230,9 @@ pub(crate) mod tests {
 							pallet_bridge_grandpa::Event::UpdatedBestFinalizedHeader {
 								number: 1,
 								hash: relay_1_hash,
-								grandpa_info: HeaderGrandpaInfo {
-									justification: justification.clone(),
-									authority_set: None,
+								grandpa_info: StoredHeaderGrandpaInfo {
+									finality_proof: justification.clone(),
+									new_verification_context: None,
 								}
 							}
 						),
@@ -1271,9 +1271,9 @@ pub(crate) mod tests {
 							pallet_bridge_grandpa::Event::UpdatedBestFinalizedHeader {
 								number: 1,
 								hash: relay_1_hash,
-								grandpa_info: HeaderGrandpaInfo {
-									justification,
-									authority_set: None,
+								grandpa_info: StoredHeaderGrandpaInfo {
+									finality_proof: justification,
+									new_verification_context: None,
 								}
 							}
 						),

bridges/primitives/header-chain/src/justification/mod.rs

@@ -23,10 +23,11 @@ mod verification;
 
 use crate::ChainWithGrandpa;
 pub use verification::{
-	equivocation::{EquivocationsCollector, Error as EquivocationsCollectorError},
+	equivocation::{EquivocationsCollector, GrandpaEquivocationsFinder},
 	optimizer::verify_and_optimize_justification,
 	strict::verify_justification,
-	AncestryChain, Error as JustificationVerificationError, PrecommitError,
+	AncestryChain, Error as JustificationVerificationError, JustificationVerificationContext,
+	PrecommitError,
 };
 
 use bp_runtime::{BlockNumberOf, Chain, HashOf, HeaderId};

bridges/primitives/header-chain/src/justification/verification/equivocation.rs

@@ -16,33 +16,26 @@
 
 //! Logic for extracting equivocations from multiple GRANDPA Finality Proofs.
 
-use crate::justification::{
-	verification::{
-		Error as JustificationVerificationError, JustificationVerifier, PrecommitError,
-		SignedPrecommit,
+use crate::{
+	justification::{
+		verification::{
+			Error as JustificationVerificationError, IterationFlow,
+			JustificationVerificationContext, JustificationVerifier, PrecommitError,
+			SignedPrecommit,
+		},
+		GrandpaJustification,
 	},
-	GrandpaJustification,
+	ChainWithGrandpa, FindEquivocations,
 };
 
-use crate::justification::verification::IterationFlow;
-use finality_grandpa::voter_set::VoterSet;
-use frame_support::RuntimeDebug;
-use sp_consensus_grandpa::{AuthorityId, AuthoritySignature, EquivocationProof, Precommit, SetId};
+use bp_runtime::{BlockNumberOf, HashOf, HeaderOf};
+use sp_consensus_grandpa::{AuthorityId, AuthoritySignature, EquivocationProof, Precommit};
 use sp_runtime::traits::Header as HeaderT;
 use sp_std::{
 	collections::{btree_map::BTreeMap, btree_set::BTreeSet},
 	prelude::*,
 };
 
-/// Justification verification error.
-#[derive(Eq, RuntimeDebug, PartialEq)]
-pub enum Error {
-	/// Justification is targeting unexpected round.
-	InvalidRound,
-	/// Justification verification error.
-	JustificationVerification(JustificationVerificationError),
-}
-
 enum AuthorityVotes<Header: HeaderT> {
 	SingleVote(SignedPrecommit<Header>),
 	Equivocation(
@@ -53,47 +46,42 @@ enum AuthorityVotes<Header: HeaderT> {
 /// Structure that can extract equivocations from multiple GRANDPA justifications.
 pub struct EquivocationsCollector<'a, Header: HeaderT> {
 	round: u64,
-	authorities_set_id: SetId,
-	authorities_set: &'a VoterSet<AuthorityId>,
+	context: &'a JustificationVerificationContext,
 
 	votes: BTreeMap<AuthorityId, AuthorityVotes<Header>>,
 }
 
 impl<'a, Header: HeaderT> EquivocationsCollector<'a, Header> {
 	/// Create a new instance of `EquivocationsCollector`.
 	pub fn new(
-		authorities_set_id: SetId,
-		authorities_set: &'a VoterSet<AuthorityId>,
+		context: &'a JustificationVerificationContext,
 		base_justification: &GrandpaJustification<Header>,
-	) -> Result<Self, Error> {
-		let mut checker = Self {
-			round: base_justification.round,
-			authorities_set_id,
-			authorities_set,
-			votes: BTreeMap::new(),
-		};
-
-		checker.parse_justification(base_justification)?;
+	) -> Result<Self, JustificationVerificationError> {
+		let mut checker = Self { round: base_justification.round, context, votes: BTreeMap::new() };
+
+		checker.verify_justification(
+			(base_justification.commit.target_hash, base_justification.commit.target_number),
+			checker.context,
+			base_justification,
+		)?;
+
 		Ok(checker)
 	}
 
-	/// Parse an additional justification for equivocations.
-	pub fn parse_justification(
-		&mut self,
-		justification: &GrandpaJustification<Header>,
-	) -> Result<(), Error> {
-		// The justification should target the same round as the base justification.
-		if self.round != justification.round {
-			return Err(Error::InvalidRound)
+	/// Parse additional justifications for equivocations.
+	pub fn parse_justifications(&mut self, justifications: &[GrandpaJustification<Header>]) {
+		let round = self.round;
+		for justification in
+			justifications.iter().filter(|justification| round == justification.round)
+		{
+			// We ignore the Errors received here since we don't care if the proofs are valid.
+			// We only care about collecting equivocations.
+			let _ = self.verify_justification(
+				(justification.commit.target_hash, justification.commit.target_number),
+				self.context,
+				justification,
+			);
 		}
-
-		self.verify_justification(
-			(justification.commit.target_hash, justification.commit.target_number),
-			self.authorities_set_id,
-			self.authorities_set,
-			justification,
-		)
-		.map_err(Error::JustificationVerification)
 	}
 
 	/// Extract the equivocation proofs that have been collected.
@@ -102,7 +90,7 @@ impl<'a, Header: HeaderT> EquivocationsCollector<'a, Header> {
 		for (_authority, vote) in self.votes {
 			if let AuthorityVotes::Equivocation(equivocation) = vote {
 				equivocations.push(EquivocationProof::new(
-					self.authorities_set_id,
+					self.context.authority_set_id,
 					sp_consensus_grandpa::Equivocation::Precommit(equivocation),
 				));
 			}
@@ -177,3 +165,29 @@ impl<'a, Header: HeaderT> JustificationVerifier<Header> for EquivocationsCollect
 		Ok(())
 	}
 }
+
+/// Helper struct for finding equivocations in GRANDPA proofs.
+pub struct GrandpaEquivocationsFinder<C>(sp_std::marker::PhantomData<C>);
+
+impl<C: ChainWithGrandpa>
+	FindEquivocations<
+		GrandpaJustification<HeaderOf<C>>,
+		JustificationVerificationContext,
+		EquivocationProof<HashOf<C>, BlockNumberOf<C>>,
+	> for GrandpaEquivocationsFinder<C>
+{
+	type Error = JustificationVerificationError;
+
+	fn find_equivocations(
+		verification_context: &JustificationVerificationContext,
+		synced_proof: &GrandpaJustification<HeaderOf<C>>,
+		source_proofs: &[GrandpaJustification<HeaderOf<C>>],
+	) -> Result<Vec<EquivocationProof<HashOf<C>, BlockNumberOf<C>>>, Self::Error> {
+		let mut equivocations_collector =
+			EquivocationsCollector::new(verification_context, synced_proof)?;
+
+		equivocations_collector.parse_justifications(source_proofs);
+
+		Ok(equivocations_collector.into_equivocation_proofs())
+	}
+}