Integrate Rialto <-> Millau message lanes into Millau/Rialto runtimes (#386)

* millau -> rialto lanes integration

* extrace common message-lane integration types into bridge-runtime-common

* rialto_messages.rs in Millau runtime

* tests

* Update bin/rialto/runtime/src/millau_messages.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* RELAYER_INTEREST_PERCENT -> RELAYER_FEE_PERCENT

* Update bin/runtime-common/src/messages.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* estimate_message_dispatch_and_delivery_fee returns Result

* Update bin/rialto/runtime/src/millau_messages.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Update bin/rialto/runtime/src/millau_messages.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Update bin/rialto/runtime/src/millau_messages.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* fmt

* mowed weight formula to primitives

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

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

@@ -0,0 +1,157 @@
+// Copyright 2019-2020 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/>.
+
+//! Everything required to serve Millau <-> Rialto message lanes.
+
+use bridge_runtime_common::messages;
+
+use bp_message_lane::{
+	source_chain::TargetHeaderChain,
+	target_chain::{ProvedMessages, SourceHeaderChain},
+	InboundLaneData, LaneId, Message, MessageNonce,
+};
+use bp_runtime::InstanceId;
+use bridge_runtime_common::messages::MessageBridge;
+use frame_support::{
+	weights::{Weight, WeightToFeePolynomial},
+	RuntimeDebug,
+};
+use sp_trie::StorageProof;
+
+/// Message payload for Millau -> Rialto messages.
+pub type ToRialtoMessagePayload = messages::source::FromThisChainMessagePayload<WithRialtoMessageBridge>;
+
+/// Message verifier for Millau -> Rialto messages.
+pub type ToRialtoMessageVerifier = messages::source::FromThisChainMessageVerifier<WithRialtoMessageBridge>;
+
+/// Message payload for Rialto -> Millau messages.
+pub type FromRialtoMessagePayload = messages::target::FromBridgedChainMessagePayload<WithRialtoMessageBridge>;
+
+/// Call-dispatch based message dispatch for Rialto -> Millau messages.
+pub type FromRialtoMessageDispatch = messages::target::FromBridgedChainMessageDispatch<
+	WithRialtoMessageBridge,
+	crate::Runtime,
+	pallet_bridge_call_dispatch::DefaultInstance,
+>;
+
+/// Millau <-> Rialto message bridge.
+#[derive(RuntimeDebug, Clone, Copy)]
+pub struct WithRialtoMessageBridge;
+
+impl MessageBridge for WithRialtoMessageBridge {
+	const INSTANCE: InstanceId = *b"rlto";
+
+	const RELAYER_FEE_PERCENT: u32 = 10;
+
+	type ThisChain = Millau;
+	type BridgedChain = Rialto;
+
+	fn maximal_dispatch_weight_of_message_on_bridged_chain() -> Weight {
+		// we don't want to relay too large messages + keep reserve for future upgrades
+		bp_rialto::MAXIMUM_EXTRINSIC_WEIGHT / 2
+	}
+
+	fn weight_of_delivery_transaction() -> Weight {
+		0 // TODO: https://github.com/paritytech/parity-bridges-common/issues/391
+	}
+
+	fn weight_of_delivery_confirmation_transaction_on_this_chain() -> Weight {
+		0 // TODO: https://github.com/paritytech/parity-bridges-common/issues/391
+	}
+
+	fn weight_of_reward_confirmation_transaction_on_target_chain() -> Weight {
+		0 // TODO: https://github.com/paritytech/parity-bridges-common/issues/391
+	}
+
+	fn this_weight_to_balance(weight: Weight) -> bp_rialto::Balance {
+		<crate::Runtime as pallet_transaction_payment::Trait>::WeightToFee::calc(&weight)
+	}
+
+	fn bridged_weight_to_balance(weight: Weight) -> bp_millau::Balance {
+		// we're using the same weights in both chains now
+		<crate::Runtime as pallet_transaction_payment::Trait>::WeightToFee::calc(&weight)
+	}
+
+	fn this_chain_balance_to_bridged_chain_balance(this_balance: bp_rialto::Balance) -> bp_millau::Balance {
+		// 1:1 conversion that will probably change in the future
+		this_balance
+	}
+}
+
+/// Millau chain from message lane point of view.
+#[derive(RuntimeDebug, Clone, Copy)]
+pub struct Millau;
+
+impl messages::ChainWithMessageLanes for Millau {
+	type AccountId = bp_millau::AccountId;
+	type Signer = bp_millau::AccountSigner;
+	type Signature = bp_millau::Signature;
+	type Call = crate::Call;
+	type Weight = Weight;
+	type Balance = bp_millau::Balance;
+}
+
+/// Rialto chain from message lane point of view.
+#[derive(RuntimeDebug, Clone, Copy)]
+pub struct Rialto;
+
+impl messages::ChainWithMessageLanes for Rialto {
+	type AccountId = bp_rialto::AccountId;
+	type Signer = bp_rialto::AccountSigner;
+	type Signature = bp_rialto::Signature;
+	type Call = (); // unknown to us
+	type Weight = Weight;
+	type Balance = bp_rialto::Balance;
+}
+
+impl TargetHeaderChain<ToRialtoMessagePayload, bp_rialto::AccountId> for Rialto {
+	type Error = &'static str;
+	// The proof is:
+	// - hash of the header this proof has been created with;
+	// - the storage proof or one or several keys;
+	// - id of the lane we prove state of.
+	type MessagesDeliveryProof = (bp_rialto::Hash, StorageProof, LaneId);
+
+	fn verify_message(payload: &ToRialtoMessagePayload) -> Result<(), Self::Error> {
+		if payload.weight > WithRialtoMessageBridge::maximal_dispatch_weight_of_message_on_bridged_chain() {
+			return Err("Too large weight declared");
+		}
+
+		Ok(())
+	}
+
+	fn verify_messages_delivery_proof(
+		_proof: Self::MessagesDeliveryProof,
+	) -> Result<(LaneId, InboundLaneData<bp_rialto::AccountId>), Self::Error> {
+		unimplemented!("https://github.com/paritytech/parity-bridges-common/issues/397")
+	}
+}
+
+impl SourceHeaderChain<bp_rialto::Balance> for Rialto {
+	type Error = &'static str;
+	// The proof is:
+	// - hash of the header this proof has been created with;
+	// - the storage proof or one or several keys;
+	// - id of the lane we prove messages for;
+	// - inclusive range of messages nonces that are proved.
+	type MessagesProof = (bp_rialto::Hash, StorageProof, LaneId, MessageNonce, MessageNonce);
+
+	fn verify_messages_proof(
+		_proof: Self::MessagesProof,
+	) -> Result<ProvedMessages<Message<bp_rialto::Balance>>, Self::Error> {
+		unimplemented!("https://github.com/paritytech/parity-bridges-common/issues/397")
+	}
+}