Add Wococo<>Rococo Header Relayer (#925)

* Add Wococo primitives crate

* Add more Wococo boilerplate code

* Add CLI support for initializing the Wococo<>Rococo bridge

* Add support for relaying headers between Rococo and Wococo

* Fix test

* RustFmt

* Fix compilation issues related to enum naming

* Bump Rococo `spec_version`

* Remove stray Westend references

bridges/primitives/chain-rococo/src/lib.rs

@@ -37,7 +37,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: sp_version::create_runtime_str!("rococo"),
 	impl_name: sp_version::create_runtime_str!("parity-rococo-v1.5"),
 	authoring_version: 0,
-	spec_version: 231,
+	spec_version: 232,
 	impl_version: 0,
 	apis: sp_version::create_apis_vec![[]],
 	transaction_version: 0,
@@ -55,14 +55,14 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 /// See: https://github.com/paritytech/polkadot/blob/master/runtime/rococo/src/lib.rs
 #[derive(parity_scale_codec::Encode, parity_scale_codec::Decode, Debug, PartialEq, Eq, Clone)]
 pub enum Call {
-	/// Generic bridge pallet.
-	#[codec(index = 40)]
-	BridgeCall(BridgeGrandpaCall),
+	/// Wococo bridge pallet.
+	#[codec(index = 41)]
+	BridgeGrandpaWococo(BridgeGrandpaWococoCall),
 }
 
 #[derive(parity_scale_codec::Encode, parity_scale_codec::Decode, Debug, PartialEq, Eq, Clone)]
 #[allow(non_camel_case_types)]
-pub enum BridgeGrandpaCall {
+pub enum BridgeGrandpaWococoCall {
 	#[codec(index = 0)]
 	submit_finality_proof(
 		<PolkadotLike as Chain>::Header,

bridges/primitives/chain-wococo/Cargo.toml

@@ -0,0 +1,36 @@
+[package]
+name = "bp-wococo"
+description = "Primitives of Wococo runtime."
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+parity-scale-codec = { version = "2.0.0", default-features = false, features = ["derive"] }
+
+# Bridge Dependencies
+bp-header-chain = { path = "../header-chain", default-features = false }
+bp-messages = { path = "../messages", default-features = false }
+bp-polkadot-core = { path = "../polkadot-core", default-features = false }
+bp-runtime = { path = "../runtime", default-features = false }
+
+# Substrate Based Dependencies
+sp-api = { git = "https://github.com/paritytech/substrate", branch = "master" , default-features = false }
+sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-std = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+sp-version = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
+
+[features]
+default = ["std"]
+std = [
+	"bp-header-chain/std",
+	"bp-messages/std",
+	"bp-polkadot-core/std",
+	"bp-runtime/std",
+	"parity-scale-codec/std",
+	"sp-api/std",
+	"sp-runtime/std",
+	"sp-std/std",
+	"sp-version/std",
+]

bridges/primitives/chain-wococo/src/lib.rs

@@ -0,0 +1,172 @@
+// 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/>.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+// RuntimeApi generated functions
+#![allow(clippy::too_many_arguments)]
+// Runtime-generated DecodeLimit::decode_all_with_depth_limit
+#![allow(clippy::unnecessary_mut_passed)]
+
+use bp_messages::{LaneId, MessageNonce, UnrewardedRelayersState, Weight};
+use bp_runtime::Chain;
+use sp_std::prelude::*;
+use sp_version::RuntimeVersion;
+
+pub use bp_polkadot_core::*;
+
+/// Wococo Chain
+pub type Wococo = PolkadotLike;
+
+pub type UncheckedExtrinsic = bp_polkadot_core::UncheckedExtrinsic<Call>;
+
+// NOTE: This needs to be kept up to date with the Rococo runtime found in the Polkadot repo.
+pub const VERSION: RuntimeVersion = RuntimeVersion {
+	spec_name: sp_version::create_runtime_str!("rococo"),
+	impl_name: sp_version::create_runtime_str!("parity-rococo-v1.5"),
+	authoring_version: 0,
+	spec_version: 232,
+	impl_version: 0,
+	apis: sp_version::create_apis_vec![[]],
+	transaction_version: 0,
+};
+
+/// Wococo Runtime `Call` enum.
+///
+/// The enum represents a subset of possible `Call`s we can send to Rococo chain.
+/// Ideally this code would be auto-generated from Metadata, because we want to
+/// avoid depending directly on the ENTIRE runtime just to get the encoding of `Dispatchable`s.
+///
+/// All entries here (like pretty much in the entire file) must be kept in sync with Rococo
+/// `construct_runtime`, so that we maintain SCALE-compatibility.
+///
+/// See: https://github.com/paritytech/polkadot/blob/master/runtime/rococo/src/lib.rs
+#[derive(parity_scale_codec::Encode, parity_scale_codec::Decode, Debug, PartialEq, Eq, Clone)]
+pub enum Call {
+	/// Rococo bridge pallet.
+	#[codec(index = 40)]
+	BridgeGrandpaRococo(BridgeGrandpaRococoCall),
+}
+
+#[derive(parity_scale_codec::Encode, parity_scale_codec::Decode, Debug, PartialEq, Eq, Clone)]
+#[allow(non_camel_case_types)]
+pub enum BridgeGrandpaRococoCall {
+	#[codec(index = 0)]
+	submit_finality_proof(
+		<PolkadotLike as Chain>::Header,
+		bp_header_chain::justification::GrandpaJustification<<PolkadotLike as Chain>::Header>,
+	),
+	#[codec(index = 1)]
+	initialize(bp_header_chain::InitializationData<<PolkadotLike as Chain>::Header>),
+}
+
+impl sp_runtime::traits::Dispatchable for Call {
+	type Origin = ();
+	type Config = ();
+	type Info = ();
+	type PostInfo = ();
+
+	fn dispatch(self, _origin: Self::Origin) -> sp_runtime::DispatchResultWithInfo<Self::PostInfo> {
+		unimplemented!("The Call is not expected to be dispatched.")
+	}
+}
+
+// We use this to get the account on Wococo (target) which is derived from Rococo's (source)
+// account.
+pub fn derive_account_from_rococo_id(id: bp_runtime::SourceAccount<AccountId>) -> AccountId {
+	let encoded_id = bp_runtime::derive_account_id(bp_runtime::ROCOCO_BRIDGE_INSTANCE, id);
+	AccountIdConverter::convert(encoded_id)
+}
+
+/// Name of the `WococoFinalityApi::best_finalized` runtime method.
+pub const BEST_FINALIZED_WOCOCO_HEADER_METHOD: &str = "WococoFinalityApi_best_finalized";
+/// Name of the `WococoFinalityApi::is_known_header` runtime method.
+pub const IS_KNOWN_WOCOCO_HEADER_METHOD: &str = "WococoFinalityApi_is_known_header";
+
+/// Name of the `ToWococoOutboundLaneApi::estimate_message_delivery_and_dispatch_fee` runtime method.
+pub const TO_WOCOCO_ESTIMATE_MESSAGE_FEE_METHOD: &str =
+	"ToWococoOutboundLaneApi_estimate_message_delivery_and_dispatch_fee";
+/// Name of the `ToWococoOutboundLaneApi::messages_dispatch_weight` runtime method.
+pub const TO_WOCOCO_MESSAGES_DISPATCH_WEIGHT_METHOD: &str = "ToWococoOutboundLaneApi_messages_dispatch_weight";
+/// Name of the `ToWococoOutboundLaneApi::latest_generated_nonce` runtime method.
+pub const TO_WOCOCO_LATEST_GENERATED_NONCE_METHOD: &str = "ToWococoOutboundLaneApi_latest_generated_nonce";
+/// Name of the `ToWococoOutboundLaneApi::latest_received_nonce` runtime method.
+pub const TO_WOCOCO_LATEST_RECEIVED_NONCE_METHOD: &str = "ToWococoOutboundLaneApi_latest_received_nonce";
+
+/// Name of the `FromWococoInboundLaneApi::latest_received_nonce` runtime method.
+pub const FROM_WOCOCO_LATEST_RECEIVED_NONCE_METHOD: &str = "FromWococoInboundLaneApi_latest_received_nonce";
+/// Name of the `FromWococoInboundLaneApi::latest_onfirmed_nonce` runtime method.
+pub const FROM_WOCOCO_LATEST_CONFIRMED_NONCE_METHOD: &str = "FromWococoInboundLaneApi_latest_confirmed_nonce";
+/// Name of the `FromWococoInboundLaneApi::unrewarded_relayers_state` runtime method.
+pub const FROM_WOCOCO_UNREWARDED_RELAYERS_STATE: &str = "FromWococoInboundLaneApi_unrewarded_relayers_state";
+
+sp_api::decl_runtime_apis! {
+	/// API for querying information about the finalized Wococo headers.
+	///
+	/// This API is implemented by runtimes that are bridging with the Wococo chain, not the
+	/// Wococo runtime itself.
+	pub trait WococoFinalityApi {
+		/// Returns number and hash of the best finalized header known to the bridge module.
+		fn best_finalized() -> (BlockNumber, Hash);
+		/// Returns true if the header is known to the runtime.
+		fn is_known_header(hash: Hash) -> bool;
+	}
+
+	/// Outbound message lane API for messages that are sent to Wococo chain.
+	///
+	/// This API is implemented by runtimes that are sending messages to Wococo chain, not the
+	/// Wococo runtime itself.
+	pub trait ToWococoOutboundLaneApi<OutboundMessageFee: Parameter, OutboundPayload: Parameter> {
+		/// Estimate message delivery and dispatch fee that needs to be paid by the sender on
+		/// this chain.
+		///
+		/// Returns `None` if message is too expensive to be sent to Wococo from this chain.
+		///
+		/// Please keep in mind that this method returns lowest message fee required for message
+		/// to be accepted to the lane. It may be good idea to pay a bit over this price to account
+		/// future exchange rate changes and guarantee that relayer would deliver your message
+		/// to the target chain.
+		fn estimate_message_delivery_and_dispatch_fee(
+			lane_id: LaneId,
+			payload: OutboundPayload,
+		) -> Option<OutboundMessageFee>;
+		/// Returns total dispatch weight and encoded payload size of all messages in given inclusive range.
+		///
+		/// If some (or all) messages are missing from the storage, they'll also will
+		/// be missing from the resulting vector. The vector is ordered by the nonce.
+		fn messages_dispatch_weight(
+			lane: LaneId,
+			begin: MessageNonce,
+			end: MessageNonce,
+		) -> Vec<(MessageNonce, Weight, u32)>;
+		/// Returns nonce of the latest message, received by bridged chain.
+		fn latest_received_nonce(lane: LaneId) -> MessageNonce;
+		/// Returns nonce of the latest message, generated by given lane.
+		fn latest_generated_nonce(lane: LaneId) -> MessageNonce;
+	}
+
+	/// Inbound message lane API for messages sent by Wococo chain.
+	///
+	/// This API is implemented by runtimes that are receiving messages from Wococo chain, not the
+	/// Wococo runtime itself.
+	pub trait FromWococoInboundLaneApi {
+		/// Returns nonce of the latest message, received by given lane.
+		fn latest_received_nonce(lane: LaneId) -> MessageNonce;
+		/// Nonce of latest message that has been confirmed to the bridged chain.
+		fn latest_confirmed_nonce(lane: LaneId) -> MessageNonce;
+		/// State of the unrewarded relayers set at given lane.
+		fn unrewarded_relayers_state(lane: LaneId) -> UnrewardedRelayersState;
+	}
+}

bridges/primitives/runtime/src/lib.rs

@@ -50,8 +50,8 @@ pub const KUSAMA_BRIDGE_INSTANCE: InstanceId = *b"ksma";
 /// Bridge-with-Rococo instance id.
 pub const ROCOCO_BRIDGE_INSTANCE: InstanceId = *b"roco";
 
-/// Bridge-with-Westend instance id.
-pub const WESTEND_BRIDGE_INSTANCE: InstanceId = *b"wend";
+/// Bridge-with-Wococo instance id.
+pub const WOCOCO_BRIDGE_INSTANCE: InstanceId = *b"woco";
 
 /// Call-dispatch module prefix.
 pub const CALL_DISPATCH_MODULE_PREFIX: &[u8] = b"pallet-bridge/dispatch";

bridges/relays/bin-substrate/Cargo.toml

@@ -27,6 +27,7 @@ bp-millau = { path = "../../primitives/chain-millau" }
 bp-polkadot = { path = "../../primitives/chain-polkadot" }
 bp-rialto = { path = "../../primitives/chain-rialto" }
 bp-rococo = { path = "../../primitives/chain-rococo" }
+bp-wococo = { path = "../../primitives/chain-wococo" }
 bp-runtime = { path = "../../primitives/runtime" }
 bp-westend = { path = "../../primitives/chain-westend" }
 bridge-runtime-common = { path = "../../bin/runtime-common" }
@@ -42,6 +43,7 @@ relay-millau-client = { path = "../client-millau" }
 relay-polkadot-client = { path = "../client-polkadot" }
 relay-rialto-client = { path = "../client-rialto" }
 relay-rococo-client = { path = "../client-rococo" }
+relay-wococo-client = { path = "../client-wococo" }
 relay-substrate-client = { path = "../client-substrate" }
 relay-utils = { path = "../utils" }
 relay-westend-client = { path = "../client-westend" }

bridges/relays/bin-substrate/src/chains/mod.rs

@@ -20,12 +20,15 @@ pub mod millau_headers_to_rialto;
 pub mod millau_messages_to_rialto;
 pub mod rialto_headers_to_millau;
 pub mod rialto_messages_to_millau;
+pub mod rococo_headers_to_wococo;
 pub mod westend_headers_to_millau;
+pub mod wococo_headers_to_rococo;
 
 mod millau;
 mod rialto;
 mod rococo;
 mod westend;
+mod wococo;
 
 use relay_utils::metrics::{FloatJsonValueMetric, MetricsParams};
 
@@ -268,7 +271,7 @@ mod rococo_tests {
 			votes_ancestries: vec![],
 		};
 
-		let actual = bp_rococo::BridgeGrandpaCall::submit_finality_proof(header.clone(), justification.clone());
+		let actual = bp_rococo::BridgeGrandpaWococoCall::submit_finality_proof(header.clone(), justification.clone());
 		let expected = millau_runtime::BridgeGrandpaRialtoCall::<millau_runtime::Runtime>::submit_finality_proof(
 			header,
 			justification,

bridges/relays/bin-substrate/src/chains/rococo_headers_to_wococo.rs

@@ -0,0 +1,60 @@
+// 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/>.
+
+//! Rococo-to-Wococo headers sync entrypoint.
+
+use crate::finality_pipeline::{SubstrateFinalitySyncPipeline, SubstrateFinalityToSubstrate};
+
+use bp_header_chain::justification::GrandpaJustification;
+use codec::Encode;
+use relay_rococo_client::{Rococo, SyncHeader as RococoSyncHeader};
+use relay_substrate_client::{Chain, TransactionSignScheme};
+use relay_utils::metrics::MetricsParams;
+use relay_wococo_client::{SigningParams as WococoSigningParams, Wococo};
+use sp_core::{Bytes, Pair};
+
+/// Rococo-to-Wococo finality sync pipeline.
+pub(crate) type RococoFinalityToWococo = SubstrateFinalityToSubstrate<Rococo, Wococo, WococoSigningParams>;
+
+impl SubstrateFinalitySyncPipeline for RococoFinalityToWococo {
+	const BEST_FINALIZED_SOURCE_HEADER_ID_AT_TARGET: &'static str = bp_rococo::BEST_FINALIZED_ROCOCO_HEADER_METHOD;
+
+	type TargetChain = Wococo;
+
+	fn customize_metrics(params: MetricsParams) -> anyhow::Result<MetricsParams> {
+		crate::chains::add_polkadot_kusama_price_metrics::<Self>(params)
+	}
+
+	fn transactions_author(&self) -> bp_wococo::AccountId {
+		(*self.target_sign.public().as_array_ref()).into()
+	}
+
+	fn make_submit_finality_proof_transaction(
+		&self,
+		transaction_nonce: <Wococo as Chain>::Index,
+		header: RococoSyncHeader,
+		proof: GrandpaJustification<bp_rococo::Header>,
+	) -> Bytes {
+		let call = bp_wococo::Call::BridgeGrandpaRococo(bp_wococo::BridgeGrandpaRococoCall::submit_finality_proof(
+			header.into_inner(),
+			proof,
+		));
+		let genesis_hash = *self.target_client.genesis_hash();
+		let transaction = Wococo::sign_transaction(genesis_hash, &self.target_sign, transaction_nonce, call);
+
+		Bytes(transaction.encode())
+	}
+}

bridges/relays/bin-substrate/src/chains/westend_headers_to_rococo.rs

@@ -0,0 +1,60 @@
+// 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/>.
+
+//! Westend-to-Rococo headers sync entrypoint.
+
+use crate::finality_pipeline::{SubstrateFinalitySyncPipeline, SubstrateFinalityToSubstrate};
+
+use bp_header_chain::justification::GrandpaJustification;
+use codec::Encode;
+use relay_rococo_client::{Rococo, SigningParams as RococoSigningParams};
+use relay_substrate_client::{Chain, TransactionSignScheme};
+use relay_utils::metrics::MetricsParams;
+use relay_westend_client::{SyncHeader as WestendSyncHeader, Westend};
+use sp_core::{Bytes, Pair};
+
+/// Westend-to-Rococo finality sync pipeline.
+pub(crate) type WestendFinalityToRococo = SubstrateFinalityToSubstrate<Westend, Rococo, RococoSigningParams>;
+
+impl SubstrateFinalitySyncPipeline for WestendFinalityToRococo {
+	const BEST_FINALIZED_SOURCE_HEADER_ID_AT_TARGET: &'static str = bp_westend::BEST_FINALIZED_WESTEND_HEADER_METHOD;
+
+	type TargetChain = Rococo;
+
+	fn customize_metrics(params: MetricsParams) -> anyhow::Result<MetricsParams> {
+		crate::chains::add_polkadot_kusama_price_metrics::<Self>(params)
+	}
+
+	fn transactions_author(&self) -> bp_rococo::AccountId {
+		(*self.target_sign.public().as_array_ref()).into()
+	}
+
+	fn make_submit_finality_proof_transaction(
+		&self,
+		transaction_nonce: <Rococo as Chain>::Index,
+		header: WestendSyncHeader,
+		proof: GrandpaJustification<bp_westend::Header>,
+	) -> Bytes {
+		let call = bp_rococo::Call::BridgeGrandpaWestend(bp_rococo::BridgeGrandpaCall::submit_finality_proof(
+			header.into_inner(),
+			proof,
+		));
+		let genesis_hash = *self.target_client.genesis_hash();
+		let transaction = Rococo::sign_transaction(genesis_hash, &self.target_sign, transaction_nonce, call);
+
+		Bytes(transaction.encode())
+	}
+}

bridges/relays/bin-substrate/src/chains/wococo.rs

@@ -0,0 +1,39 @@
+// 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::{encode_message, CliChain};
+use frame_support::weights::Weight;
+use relay_wococo_client::Wococo;
+use sp_version::RuntimeVersion;
+
+impl CliChain for Wococo {
+	const RUNTIME_VERSION: RuntimeVersion = bp_wococo::VERSION;
+
+	type KeyPair = sp_core::sr25519::Pair;
+	type MessagePayload = ();
+
+	fn ss58_format() -> u16 {
+		42
+	}
+
+	fn max_extrinsic_weight() -> Weight {
+		0
+	}
+
+	fn encode_message(_message: encode_message::MessagePayload) -> Result<Self::MessagePayload, String> {
+		Err("Sending messages from Wococo is not yet supported.".into())
+	}
+}

bridges/relays/bin-substrate/src/chains/wococo_headers_to_rococo.rs

@@ -0,0 +1,60 @@
+// 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/>.
+
+//! Wococo-to-Rococo headers sync entrypoint.
+
+use crate::finality_pipeline::{SubstrateFinalitySyncPipeline, SubstrateFinalityToSubstrate};
+
+use bp_header_chain::justification::GrandpaJustification;
+use codec::Encode;
+use relay_rococo_client::{Rococo, SigningParams as RococoSigningParams};
+use relay_substrate_client::{Chain, TransactionSignScheme};
+use relay_utils::metrics::MetricsParams;
+use relay_wococo_client::{SyncHeader as WococoSyncHeader, Wococo};
+use sp_core::{Bytes, Pair};
+
+/// Wococo-to-Rococo finality sync pipeline.
+pub(crate) type WococoFinalityToRococo = SubstrateFinalityToSubstrate<Wococo, Rococo, RococoSigningParams>;
+
+impl SubstrateFinalitySyncPipeline for WococoFinalityToRococo {
+	const BEST_FINALIZED_SOURCE_HEADER_ID_AT_TARGET: &'static str = bp_wococo::BEST_FINALIZED_WOCOCO_HEADER_METHOD;
+
+	type TargetChain = Rococo;
+
+	fn customize_metrics(params: MetricsParams) -> anyhow::Result<MetricsParams> {
+		crate::chains::add_polkadot_kusama_price_metrics::<Self>(params)
+	}
+
+	fn transactions_author(&self) -> bp_rococo::AccountId {
+		(*self.target_sign.public().as_array_ref()).into()
+	}
+
+	fn make_submit_finality_proof_transaction(
+		&self,
+		transaction_nonce: <Rococo as Chain>::Index,
+		header: WococoSyncHeader,
+		proof: GrandpaJustification<bp_wococo::Header>,
+	) -> Bytes {
+		let call = bp_rococo::Call::BridgeGrandpaWococo(bp_rococo::BridgeGrandpaWococoCall::submit_finality_proof(
+			header.into_inner(),
+			proof,
+		));
+		let genesis_hash = *self.target_client.genesis_hash();
+		let transaction = Rococo::sign_transaction(genesis_hash, &self.target_sign, transaction_nonce, call);
+
+		Bytes(transaction.encode())
+	}
+}

bridges/relays/bin-substrate/src/cli/init_bridge.rs

@@ -44,6 +44,8 @@ arg_enum! {
 		MillauToRialto,
 		RialtoToMillau,
 		WestendToMillau,
+		RococoToWococo,
+		WococoToRococo,
 	}
 }
 
@@ -98,6 +100,30 @@ macro_rules! select_bridge {
 					.into()
 				}
 
+				$generic
+			}
+			InitBridgeName::RococoToWococo => {
+				type Source = relay_rococo_client::Rococo;
+				type Target = relay_wococo_client::Wococo;
+
+				fn encode_init_bridge(
+					init_data: InitializationData<<Source as ChainBase>::Header>,
+				) -> <Target as Chain>::Call {
+					bp_wococo::Call::BridgeGrandpaRococo(bp_wococo::BridgeGrandpaRococoCall::initialize(init_data))
+				}
+
+				$generic
+			}
+			InitBridgeName::WococoToRococo => {
+				type Source = relay_wococo_client::Wococo;
+				type Target = relay_rococo_client::Rococo;
+
+				fn encode_init_bridge(
+					init_data: InitializationData<<Source as ChainBase>::Header>,
+				) -> <Target as Chain>::Call {
+					bp_rococo::Call::BridgeGrandpaWococo(bp_rococo::BridgeGrandpaWococoCall::initialize(init_data))
+				}
+
 				$generic
 			}
 		}

bridges/relays/bin-substrate/src/cli/relay_headers.rs

@@ -42,6 +42,8 @@ arg_enum! {
 		MillauToRialto,
 		RialtoToMillau,
 		WestendToMillau,
+		RococoToWococo,
+		WococoToRococo,
 	}
 }
 
@@ -67,6 +69,20 @@ macro_rules! select_bridge {
 				type Target = relay_millau_client::Millau;
 				type Finality = crate::chains::westend_headers_to_millau::WestendFinalityToMillau;
 
+				$generic
+			}
+			RelayHeadersBridge::RococoToWococo => {
+				type Source = relay_rococo_client::Rococo;
+				type Target = relay_wococo_client::Wococo;
+				type Finality = crate::chains::rococo_headers_to_wococo::RococoFinalityToWococo;
+
+				$generic
+			}
+			RelayHeadersBridge::WococoToRococo => {
+				type Source = relay_wococo_client::Wococo;
+				type Target = relay_rococo_client::Rococo;
+				type Finality = crate::chains::wococo_headers_to_rococo::WococoFinalityToRococo;
+
 				$generic
 			}
 		}

bridges/relays/client-wococo/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "relay-wococo-client"
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "2.0.0" }
+headers-relay = { path = "../headers" }
+relay-substrate-client = { path = "../client-substrate" }
+relay-utils = { path = "../utils" }
+
+# Bridge dependencies
+bp-wococo = { path = "../../primitives/chain-wococo" }
+
+# Substrate Dependencies
+frame-system = { git = "https://github.com/paritytech/substrate", branch = "master" }
+frame-support = { git = "https://github.com/paritytech/substrate", branch = "master" }
+pallet-transaction-payment = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-keyring = { git = "https://github.com/paritytech/substrate", branch = "master" }
+sp-runtime = { git = "https://github.com/paritytech/substrate", branch = "master" }

bridges/relays/client-wococo/src/lib.rs

@@ -0,0 +1,97 @@
+// 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/>.
+
+//! Types used to connect to the Wococo-Substrate chain.
+
+use codec::Encode;
+use relay_substrate_client::{Chain, ChainBase, ChainWithBalances, TransactionSignScheme};
+use sp_core::{storage::StorageKey, Pair};
+use sp_runtime::{generic::SignedPayload, traits::IdentifyAccount};
+use std::time::Duration;
+
+/// Wococo header id.
+pub type HeaderId = relay_utils::HeaderId<bp_wococo::Hash, bp_wococo::BlockNumber>;
+
+/// Wococo header type used in headers sync.
+pub type SyncHeader = relay_substrate_client::SyncHeader<bp_wococo::Header>;
+
+/// Wococo chain definition
+#[derive(Debug, Clone, Copy)]
+pub struct Wococo;
+
+impl ChainBase for Wococo {
+	type BlockNumber = bp_wococo::BlockNumber;
+	type Hash = bp_wococo::Hash;
+	type Hasher = bp_wococo::Hashing;
+	type Header = bp_wococo::Header;
+}
+
+impl Chain for Wococo {
+	const NAME: &'static str = "Wococo";
+	const AVERAGE_BLOCK_INTERVAL: Duration = Duration::from_secs(6);
+
+	type AccountId = bp_wococo::AccountId;
+	type Index = bp_wococo::Index;
+	type SignedBlock = bp_wococo::SignedBlock;
+	type Call = bp_wococo::Call;
+}
+
+impl ChainWithBalances for Wococo {
+	type NativeBalance = bp_wococo::Balance;
+
+	fn account_info_storage_key(account_id: &Self::AccountId) -> StorageKey {
+		StorageKey(bp_wococo::account_info_storage_key(account_id))
+	}
+}
+
+impl TransactionSignScheme for Wococo {
+	type Chain = Wococo;
+	type AccountKeyPair = sp_core::sr25519::Pair;
+	type SignedTransaction = bp_wococo::UncheckedExtrinsic;
+
+	fn sign_transaction(
+		genesis_hash: <Self::Chain as ChainBase>::Hash,
+		signer: &Self::AccountKeyPair,
+		signer_nonce: <Self::Chain as Chain>::Index,
+		call: <Self::Chain as Chain>::Call,
+	) -> Self::SignedTransaction {
+		let raw_payload = SignedPayload::new(
+			call,
+			bp_wococo::SignedExtensions::new(
+				bp_wococo::VERSION,
+				sp_runtime::generic::Era::Immortal,
+				genesis_hash,
+				signer_nonce,
+				0,
+			),
+		)
+		.expect("SignedExtension never fails.");
+
+		let signature = raw_payload.using_encoded(|payload| signer.sign(payload));
+		let signer: sp_runtime::MultiSigner = signer.public().into();
+		let (call, extra, _) = raw_payload.deconstruct();
+
+		bp_wococo::UncheckedExtrinsic::new_signed(
+			call,
+			sp_runtime::MultiAddress::Id(signer.into_account()),
+			signature.into(),
+			extra,
+		)
+	}
+}
+
+/// Wococo signing params.
+pub type SigningParams = sp_core::sr25519::Pair;