lib.rs

// 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/>.

mod equivocation_loop;
mod reporter;

use async_trait::async_trait;
use bp_header_chain::FindEquivocations;
use finality_relay::{FinalityPipeline, SourceClientBase};
use relay_utils::{relay_loop::Client as RelayClient, TransactionTracker};
use std::fmt::Debug;

pub trait EquivocationDetectionPipeline: FinalityPipeline {
	/// Block number of the target chain.
	type TargetNumber: relay_utils::BlockNumberBase;
	/// The context needed for validating finality proofs.
	type FinalityVerificationContext: Send;
	/// The type of the equivocation proof.
	type EquivocationProof: Clone + Debug + Send + Sync;
	/// The equivocations finder.
	type EquivocationsFinder: FindEquivocations<
		Self::FinalityProof,
		Self::FinalityVerificationContext,
		Self::EquivocationProof,
	>;
}

type HeaderFinalityInfo<P> = bp_header_chain::HeaderFinalityInfo<
	<P as FinalityPipeline>::FinalityProof,
	<P as EquivocationDetectionPipeline>::FinalityVerificationContext,
>;

/// Source client used in equivocation detection loop.
#[async_trait]
pub trait SourceClient<P: EquivocationDetectionPipeline>: SourceClientBase<P> {
	/// Transaction tracker to track submitted transactions.
	type TransactionTracker: TransactionTracker;

	/// Report equivocation.
	async fn report_equivocation(
		&self,
		at: P::Hash,
		equivocation: P::EquivocationProof,
	) -> Result<Self::TransactionTracker, Self::Error>;
}

/// Target client used in equivocation detection loop.
#[async_trait]
pub trait TargetClient<P: EquivocationDetectionPipeline>: RelayClient {
	/// Get the best finalized header number.
	async fn best_finalized_header_number(&self) -> Result<P::TargetNumber, Self::Error>;

	/// Get the hash of the best source header known by the target at the provided block number.
	async fn best_synced_header_hash(
		&self,
		at: P::TargetNumber,
	) -> Result<Option<P::Hash>, Self::Error>;

	/// Get the data stored by the target at the specified block for validating source finality
	/// proofs.
	async fn finality_verification_context(
		&self,
		at: P::TargetNumber,
	) -> Result<P::FinalityVerificationContext, Self::Error>;

	/// Get the finality info associated to the source headers synced with the target chain at the
	/// specified block.
	async fn synced_headers_finality_info(
		&self,
		at: P::TargetNumber,
	) -> Result<Vec<HeaderFinalityInfo<P>>, Self::Error>;
}