bridge.rs

// Copyright 2019-2021 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/>.

use crate::cli::CliChain;
use pallet_bridge_parachains::{RelayBlockHash, RelayBlockHasher, RelayBlockNumber};
use relay_substrate_client::{Chain, ChainWithTransactions, Parachain, RelayChain};
use strum::{EnumString, EnumVariantNames};
use substrate_relay_helper::{
	equivocation::SubstrateEquivocationDetectionPipeline,
	finality::SubstrateFinalitySyncPipeline,
	messages_lane::{MessagesRelayLimits, SubstrateMessageLane},
	parachains::SubstrateParachainsPipeline,
};

#[derive(Debug, PartialEq, Eq, EnumString, EnumVariantNames)]
#[strum(serialize_all = "kebab_case")]
/// Supported full bridges (headers + messages).
pub enum FullBridge {
	MillauToRialto,
	RialtoToMillau,
	MillauToRialtoParachain,
	RialtoParachainToMillau,
	BridgeHubRococoToBridgeHubWococo,
	BridgeHubWococoToBridgeHubRococo,
	BridgeHubKusamaToBridgeHubPolkadot,
	BridgeHubPolkadotToBridgeHubKusama,
	PolkadotBulletinToBridgeHubPolkadot,
	BridgeHubPolkadotToPolkadotBulletin,
}

/// Minimal bridge representation that can be used from the CLI.
/// It connects a source chain to a target chain.
pub trait CliBridgeBase: Sized {
	/// The source chain.
	type Source: Chain + CliChain;
	/// The target chain.
	type Target: ChainWithTransactions + CliChain;
}

/// Bridge representation that can be used from the CLI for relaying headers
/// from a relay chain to a relay chain.
pub trait RelayToRelayHeadersCliBridge: CliBridgeBase {
	/// Finality proofs synchronization pipeline.
	type Finality: SubstrateFinalitySyncPipeline<
		SourceChain = Self::Source,
		TargetChain = Self::Target,
	>;
}

/// Convenience trait that adds bounds to `CliBridgeBase`.
pub trait RelayToRelayEquivocationDetectionCliBridgeBase: CliBridgeBase {
	type BoundedSource: ChainWithTransactions;
}

impl<T> RelayToRelayEquivocationDetectionCliBridgeBase for T
where
	T: CliBridgeBase,
	T::Source: ChainWithTransactions,
{
	type BoundedSource = T::Source;
}

/// Bridge representation that can be used from the CLI for detecting equivocations
/// in the headers synchronized from a relay chain to a relay chain.
pub trait RelayToRelayEquivocationDetectionCliBridge:
	RelayToRelayEquivocationDetectionCliBridgeBase
{
	/// Equivocation detection pipeline.
	type Equivocation: SubstrateEquivocationDetectionPipeline<
		SourceChain = Self::Source,
		TargetChain = Self::Target,
	>;
}

/// Bridge representation that can be used from the CLI for relaying headers
/// from a parachain to a relay chain.
pub trait ParachainToRelayHeadersCliBridge: CliBridgeBase
where
	Self::Source: Parachain,
{
	// The `CliBridgeBase` type represents the parachain in this situation.
	// We need to add an extra type for the relay chain.
	type SourceRelay: Chain<BlockNumber = RelayBlockNumber, Hash = RelayBlockHash, Hasher = RelayBlockHasher>
		+ CliChain
		+ RelayChain;
	/// Finality proofs synchronization pipeline (source parachain -> target).
	type ParachainFinality: SubstrateParachainsPipeline<
		SourceRelayChain = Self::SourceRelay,
		SourceParachain = Self::Source,
		TargetChain = Self::Target,
	>;
	/// Finality proofs synchronization pipeline (source relay chain -> target).
	type RelayFinality: SubstrateFinalitySyncPipeline<
		SourceChain = Self::SourceRelay,
		TargetChain = Self::Target,
	>;
}

/// Bridge representation that can be used from the CLI for relaying messages.
pub trait MessagesCliBridge: CliBridgeBase {
	/// The Source -> Destination messages synchronization pipeline.
	type MessagesLane: SubstrateMessageLane<SourceChain = Self::Source, TargetChain = Self::Target>;

	/// Optional messages delivery transaction limits that the messages relay is going
	/// to use. If it returns `None`, limits are estimated using `TransactionPayment` API
	/// at the target chain.
	fn maybe_messages_limits() -> Option<MessagesRelayLimits> {
		None
	}
}