From f09f758d180d5f9821575e7fac1fb19ad8ab4b2b Mon Sep 17 00:00:00 2001
From: Serban Iorga <serban@parity.io>
Date: Wed, 9 Aug 2023 17:08:02 +0300
Subject: [PATCH] Add equivocation detection pipeline

---
 Cargo.lock                                    |  8 ++
 relays/client-kusama/Cargo.toml               |  1 +
 relays/client-kusama/src/lib.rs               |  3 +
 relays/client-millau/Cargo.toml               |  1 +
 relays/client-millau/src/lib.rs               |  3 +
 relays/client-polkadot/Cargo.toml             |  1 +
 relays/client-polkadot/src/lib.rs             |  3 +
 relays/client-rialto/Cargo.toml               |  1 +
 relays/client-rialto/src/lib.rs               |  3 +
 relays/client-rococo/Cargo.toml               |  1 +
 relays/client-rococo/src/lib.rs               |  3 +
 relays/client-substrate/src/chain.rs          |  3 +
 relays/client-westend/Cargo.toml              |  1 +
 relays/client-westend/src/lib.rs              |  3 +
 relays/client-wococo/Cargo.toml               |  1 +
 relays/client-wococo/src/lib.rs               |  3 +
 relays/lib-substrate-relay/Cargo.toml         |  1 +
 .../src/equivocation/mod.rs                   | 83 +++++++++++++++++++
 .../lib-substrate-relay/src/finality/mod.rs   |  4 +-
 .../src/finality_base/engine.rs               |  6 ++
 relays/lib-substrate-relay/src/lib.rs         |  1 +
 21 files changed, 131 insertions(+), 3 deletions(-)
 create mode 100644 relays/lib-substrate-relay/src/equivocation/mod.rs

diff --git a/Cargo.lock b/Cargo.lock
index c5a22cf9899..c512280b6e1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -10261,6 +10261,7 @@ dependencies = [
  "relay-substrate-client",
  "relay-utils",
  "sp-core",
+ "sp-session",
 ]
 
 [[package]]
@@ -10277,6 +10278,7 @@ dependencies = [
  "relay-utils",
  "sp-core",
  "sp-runtime",
+ "sp-session",
 ]
 
 [[package]]
@@ -10287,6 +10289,7 @@ dependencies = [
  "relay-substrate-client",
  "relay-utils",
  "sp-core",
+ "sp-session",
 ]
 
 [[package]]
@@ -10303,6 +10306,7 @@ dependencies = [
  "rialto-runtime",
  "sp-core",
  "sp-runtime",
+ "sp-session",
 ]
 
 [[package]]
@@ -10333,6 +10337,7 @@ dependencies = [
  "relay-substrate-client",
  "relay-utils",
  "sp-core",
+ "sp-session",
 ]
 
 [[package]]
@@ -10410,6 +10415,7 @@ dependencies = [
  "relay-substrate-client",
  "relay-utils",
  "sp-core",
+ "sp-session",
 ]
 
 [[package]]
@@ -10420,6 +10426,7 @@ dependencies = [
  "relay-substrate-client",
  "relay-utils",
  "sp-core",
+ "sp-session",
 ]
 
 [[package]]
@@ -13980,6 +13987,7 @@ dependencies = [
  "pallet-bridge-grandpa",
  "pallet-bridge-messages",
  "pallet-bridge-parachains",
+ "pallet-grandpa",
  "pallet-transaction-payment",
  "parachains-relay",
  "parity-scale-codec",
diff --git a/relays/client-kusama/Cargo.toml b/relays/client-kusama/Cargo.toml
index e4d83d88ceb..4f8813c51a5 100644
--- a/relays/client-kusama/Cargo.toml
+++ b/relays/client-kusama/Cargo.toml
@@ -16,3 +16,4 @@ bp-kusama = { path = "../../primitives/chain-kusama" }
 # Substrate Dependencies
 
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-kusama/src/lib.rs b/relays/client-kusama/src/lib.rs
index 7291a21b620..15b8abd2670 100644
--- a/relays/client-kusama/src/lib.rs
+++ b/relays/client-kusama/src/lib.rs
@@ -21,6 +21,7 @@ use relay_substrate_client::{
 	Chain, ChainWithBalances, ChainWithGrandpa, RelayChain, UnderlyingChainProvider,
 };
 use sp_core::storage::StorageKey;
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Kusama header id.
@@ -50,6 +51,8 @@ impl Chain for Kusama {
 impl ChainWithGrandpa for Kusama {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		KUSAMA_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl ChainWithBalances for Kusama {
diff --git a/relays/client-millau/Cargo.toml b/relays/client-millau/Cargo.toml
index e01c37eb52b..86ce0429d54 100644
--- a/relays/client-millau/Cargo.toml
+++ b/relays/client-millau/Cargo.toml
@@ -22,3 +22,4 @@ frame-system = { git = "https://github.com/paritytech/substrate", branch = "mast
 pallet-transaction-payment = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-millau/src/lib.rs b/relays/client-millau/src/lib.rs
index d470b9ee1f4..68d71e7bdb7 100644
--- a/relays/client-millau/src/lib.rs
+++ b/relays/client-millau/src/lib.rs
@@ -25,6 +25,7 @@ use relay_substrate_client::{
 };
 use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{generic::SignedPayload, traits::IdentifyAccount};
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Millau header id.
@@ -60,6 +61,8 @@ impl Chain for Millau {
 impl ChainWithGrandpa for Millau {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		MILLAU_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl ChainWithBalances for Millau {
diff --git a/relays/client-polkadot/Cargo.toml b/relays/client-polkadot/Cargo.toml
index cc16ec1f5c3..7c9fa957001 100644
--- a/relays/client-polkadot/Cargo.toml
+++ b/relays/client-polkadot/Cargo.toml
@@ -16,3 +16,4 @@ bp-polkadot = { path = "../../primitives/chain-polkadot" }
 # Substrate Dependencies
 
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-polkadot/src/lib.rs b/relays/client-polkadot/src/lib.rs
index 07386281c04..345b45506d3 100644
--- a/relays/client-polkadot/src/lib.rs
+++ b/relays/client-polkadot/src/lib.rs
@@ -21,6 +21,7 @@ use relay_substrate_client::{
 	Chain, ChainWithBalances, ChainWithGrandpa, RelayChain, UnderlyingChainProvider,
 };
 use sp_core::storage::StorageKey;
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Polkadot header id.
@@ -50,6 +51,8 @@ impl Chain for Polkadot {
 impl ChainWithGrandpa for Polkadot {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		POLKADOT_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl ChainWithBalances for Polkadot {
diff --git a/relays/client-rialto/Cargo.toml b/relays/client-rialto/Cargo.toml
index 85607b07db9..4279c6ecc12 100644
--- a/relays/client-rialto/Cargo.toml
+++ b/relays/client-rialto/Cargo.toml
@@ -22,3 +22,4 @@ frame-support = { git = "https://github.com/paritytech/substrate", branch = "mas
 pallet-transaction-payment = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-rialto/src/lib.rs b/relays/client-rialto/src/lib.rs
index a73c3cb9753..213be5eda65 100644
--- a/relays/client-rialto/src/lib.rs
+++ b/relays/client-rialto/src/lib.rs
@@ -25,6 +25,7 @@ use relay_substrate_client::{
 };
 use sp_core::{storage::StorageKey, Pair};
 use sp_runtime::{generic::SignedPayload, traits::IdentifyAccount};
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Rialto header id.
@@ -51,6 +52,8 @@ impl Chain for Rialto {
 impl ChainWithGrandpa for Rialto {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		RIALTO_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl RelayChain for Rialto {
diff --git a/relays/client-rococo/Cargo.toml b/relays/client-rococo/Cargo.toml
index cc197ba8562..9ced6e2b939 100644
--- a/relays/client-rococo/Cargo.toml
+++ b/relays/client-rococo/Cargo.toml
@@ -16,3 +16,4 @@ bp-rococo = { path = "../../primitives/chain-rococo" }
 # Substrate Dependencies
 
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-rococo/src/lib.rs b/relays/client-rococo/src/lib.rs
index 5e4124a5d33..04fe11c741c 100644
--- a/relays/client-rococo/src/lib.rs
+++ b/relays/client-rococo/src/lib.rs
@@ -21,6 +21,7 @@ use relay_substrate_client::{
 	Chain, ChainWithBalances, ChainWithGrandpa, RelayChain, UnderlyingChainProvider,
 };
 use sp_core::storage::StorageKey;
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Rococo header id.
@@ -50,6 +51,8 @@ impl Chain for Rococo {
 impl ChainWithGrandpa for Rococo {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		ROCOCO_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl ChainWithBalances for Rococo {
diff --git a/relays/client-substrate/src/chain.rs b/relays/client-substrate/src/chain.rs
index 86526790b5b..6fc54944e75 100644
--- a/relays/client-substrate/src/chain.rs
+++ b/relays/client-substrate/src/chain.rs
@@ -86,6 +86,9 @@ pub trait ChainWithGrandpa: Chain + UnderlyingChainWithGrandpaProvider {
 	/// Keep in mind that this method is normally provided by the other chain, which is
 	/// bridged with this chain.
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str;
+
+	/// The type of the key owner proof used by the grandpa engine.
+	type KeyOwnerProof;
 }
 
 /// Substrate-based parachain from minimal relay-client point of view.
diff --git a/relays/client-westend/Cargo.toml b/relays/client-westend/Cargo.toml
index c60305868ad..744b2d29e75 100644
--- a/relays/client-westend/Cargo.toml
+++ b/relays/client-westend/Cargo.toml
@@ -16,3 +16,4 @@ bp-westend = { path = "../../primitives/chain-westend" }
 # Substrate Dependencies
 
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-westend/src/lib.rs b/relays/client-westend/src/lib.rs
index c304b7e2f37..523accbfdbf 100644
--- a/relays/client-westend/src/lib.rs
+++ b/relays/client-westend/src/lib.rs
@@ -21,6 +21,7 @@ use relay_substrate_client::{
 	Chain, ChainWithBalances, ChainWithGrandpa, RelayChain, UnderlyingChainProvider,
 };
 use sp_core::storage::StorageKey;
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Westend header id.
@@ -50,6 +51,8 @@ impl Chain for Westend {
 impl ChainWithGrandpa for Westend {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		WESTEND_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl RelayChain for Westend {
diff --git a/relays/client-wococo/Cargo.toml b/relays/client-wococo/Cargo.toml
index 19483ab22fd..385cede88bc 100644
--- a/relays/client-wococo/Cargo.toml
+++ b/relays/client-wococo/Cargo.toml
@@ -15,3 +15,4 @@ bp-wococo = { path = "../../primitives/chain-wococo" }
 
 # Substrate Dependencies
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-session = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/client-wococo/src/lib.rs b/relays/client-wococo/src/lib.rs
index c080a217a77..e9d52280822 100644
--- a/relays/client-wococo/src/lib.rs
+++ b/relays/client-wococo/src/lib.rs
@@ -21,6 +21,7 @@ use relay_substrate_client::{
 	Chain, ChainWithBalances, ChainWithGrandpa, RelayChain, UnderlyingChainProvider,
 };
 use sp_core::storage::StorageKey;
+use sp_session::MembershipProof;
 use std::time::Duration;
 
 /// Wococo header id.
@@ -50,6 +51,8 @@ impl Chain for Wococo {
 impl ChainWithGrandpa for Wococo {
 	const SYNCED_HEADERS_GRANDPA_INFO_METHOD: &'static str =
 		WOCOCO_SYNCED_HEADERS_GRANDPA_INFO_METHOD;
+
+	type KeyOwnerProof = MembershipProof;
 }
 
 impl ChainWithBalances for Wococo {
diff --git a/relays/lib-substrate-relay/Cargo.toml b/relays/lib-substrate-relay/Cargo.toml
index 26762a50a77..6db30996a8a 100644
--- a/relays/lib-substrate-relay/Cargo.toml
+++ b/relays/lib-substrate-relay/Cargo.toml
@@ -43,6 +43,7 @@ bp-messages = { path = "../../primitives/messages" }
 frame-support = { git = "https://github.com/paritytech/substrate", branch = "master" }
 frame-system = { git = "https://github.com/paritytech/substrate", branch = "master" }
 pallet-balances = { git = "https://github.com/paritytech/substrate", branch = "master" }
+pallet-grandpa = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-consensus-grandpa = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" }
diff --git a/relays/lib-substrate-relay/src/equivocation/mod.rs b/relays/lib-substrate-relay/src/equivocation/mod.rs
new file mode 100644
index 00000000000..31668490f90
--- /dev/null
+++ b/relays/lib-substrate-relay/src/equivocation/mod.rs
@@ -0,0 +1,83 @@
+// Copyright 2019-2023 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Types and functions intended to ease adding of new Substrate -> Substrate
+//! equivocation detection pipelines.
+
+use crate::finality_base::SubstrateFinalityPipeline;
+use std::marker::PhantomData;
+
+use crate::finality_base::engine::Engine;
+use async_trait::async_trait;
+use bp_runtime::{BlockNumberOf, HashOf};
+use pallet_grandpa::{Call as GrandpaCall, Config as GrandpaConfig};
+use relay_substrate_client::CallOf;
+use sp_runtime::traits::{Block, Header};
+
+/// Substrate -> Substrate equivocation detection pipeline.
+#[async_trait]
+pub trait SubstrateEquivocationDetectionPipeline: SubstrateFinalityPipeline {
+	/// How the `report_equivocation` call is built ?
+	type ReportEquivocationCallBuilder: ReportEquivocationCallBuilder<Self>;
+}
+
+type EquivocationProofOf<P> = <<P as SubstrateFinalityPipeline>::FinalityEngine as Engine<
+	<P as SubstrateFinalityPipeline>::SourceChain,
+>>::EquivocationProof;
+type KeyOwnerProofOf<P> = <<P as SubstrateFinalityPipeline>::FinalityEngine as Engine<
+	<P as SubstrateFinalityPipeline>::SourceChain,
+>>::KeyOwnerProof;
+
+/// Different ways of building `report_equivocation` calls.
+pub trait ReportEquivocationCallBuilder<P: SubstrateEquivocationDetectionPipeline> {
+	/// Build a `report_equivocation` call to be executed on the source chain.
+	fn build_report_equivocation_call(
+		equivocation_proof: EquivocationProofOf<P>,
+		key_owner_proof: KeyOwnerProofOf<P>,
+	) -> CallOf<P::SourceChain>;
+}
+
+/// Building the `report_equivocation` call when having direct access to the target chain runtime.
+pub struct DirectReportGrandpaEquivocationCallBuilder<P, R> {
+	_phantom: PhantomData<(P, R)>,
+}
+
+impl<P, R> ReportEquivocationCallBuilder<P> for DirectReportGrandpaEquivocationCallBuilder<P, R>
+where
+	P: SubstrateEquivocationDetectionPipeline,
+	P::FinalityEngine: Engine<
+		P::SourceChain,
+		EquivocationProof = sp_consensus_grandpa::EquivocationProof<
+			HashOf<P::SourceChain>,
+			BlockNumberOf<P::SourceChain>,
+		>,
+	>,
+	R: frame_system::Config<Hash = HashOf<P::SourceChain>>
+		+ GrandpaConfig<KeyOwnerProof = KeyOwnerProofOf<P>>,
+	<R::Block as Block>::Header: Header<Number = BlockNumberOf<P::SourceChain>>,
+	CallOf<P::SourceChain>: From<GrandpaCall<R>>,
+{
+	fn build_report_equivocation_call(
+		equivocation_proof: EquivocationProofOf<P>,
+		key_owner_proof: KeyOwnerProofOf<P>,
+	) -> CallOf<P::SourceChain> {
+		GrandpaCall::<R>::report_equivocation {
+			equivocation_proof: Box::new(equivocation_proof),
+			key_owner_proof,
+		}
+		.into()
+	}
+}
diff --git a/relays/lib-substrate-relay/src/finality/mod.rs b/relays/lib-substrate-relay/src/finality/mod.rs
index 0bec4338a6a..db021db8352 100644
--- a/relays/lib-substrate-relay/src/finality/mod.rs
+++ b/relays/lib-substrate-relay/src/finality/mod.rs
@@ -50,9 +50,7 @@ pub(crate) const RECENT_FINALITY_PROOFS_LIMIT: usize = 4096;
 
 /// Substrate -> Substrate finality proofs synchronization pipeline.
 #[async_trait]
-pub trait SubstrateFinalitySyncPipeline:
-	'static + SubstrateFinalityPipeline + Clone + Debug + Send + Sync
-{
+pub trait SubstrateFinalitySyncPipeline: SubstrateFinalityPipeline {
 	/// How submit finality proof call is built?
 	type SubmitFinalityProofCallBuilder: SubmitFinalityProofCallBuilder<Self>;
 
diff --git a/relays/lib-substrate-relay/src/finality_base/engine.rs b/relays/lib-substrate-relay/src/finality_base/engine.rs
index e650ebf54f3..272c20c2606 100644
--- a/relays/lib-substrate-relay/src/finality_base/engine.rs
+++ b/relays/lib-substrate-relay/src/finality_base/engine.rs
@@ -46,6 +46,10 @@ pub trait Engine<C: Chain>: Send {
 	type ConsensusLogReader: ConsensusLogReader;
 	/// Type of finality proofs, used by consensus engine.
 	type FinalityProof: FinalityProof<BlockNumberOf<C>> + Decode + Encode;
+	/// The type of the equivocation proof used by the consensus engine.
+	type EquivocationProof;
+	/// The type of the key owner proof used by the consensus engine.
+	type KeyOwnerProof;
 	/// Type of bridge pallet initialization data.
 	type InitializationData: std::fmt::Debug + Send + Sync + 'static;
 	/// Type of bridge pallet operating mode.
@@ -137,6 +141,8 @@ impl<C: ChainWithGrandpa> Engine<C> for Grandpa<C> {
 	const ID: ConsensusEngineId = GRANDPA_ENGINE_ID;
 	type ConsensusLogReader = GrandpaConsensusLogReader<<C::Header as Header>::Number>;
 	type FinalityProof = GrandpaJustification<HeaderOf<C>>;
+	type EquivocationProof = sp_consensus_grandpa::EquivocationProof<HashOf<C>, BlockNumberOf<C>>;
+	type KeyOwnerProof = C::KeyOwnerProof;
 	type InitializationData = bp_header_chain::InitializationData<C::Header>;
 	type OperatingMode = BasicOperatingMode;
 
diff --git a/relays/lib-substrate-relay/src/lib.rs b/relays/lib-substrate-relay/src/lib.rs
index 08a7ce785ba..068c5ceccf3 100644
--- a/relays/lib-substrate-relay/src/lib.rs
+++ b/relays/lib-substrate-relay/src/lib.rs
@@ -22,6 +22,7 @@ use relay_substrate_client::{Chain, ChainWithUtilityPallet, UtilityPallet};
 
 use std::marker::PhantomData;
 
+pub mod equivocation;
 pub mod error;
 pub mod finality;
 pub mod finality_base;