Define separate signed extension for BHR/BHW (#1776)

- Make signed extensions for indirect runtimes more extensible
- Define separate signed extension for BHR/BHW

bridges/primitives/runtime/src/extensions.rs

@@ -0,0 +1,136 @@
+// 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/>.
+
+//! Primitives that may be used for creating signed extensions for indirect runtimes.
+
+use crate::{BalanceOf, HashOf};
+use codec::{Compact, Decode, Encode};
+use impl_trait_for_tuples::impl_for_tuples;
+use scale_info::{StaticTypeInfo, TypeInfo};
+use sp_runtime::{
+	traits::{DispatchInfoOf, SignedExtension},
+	transaction_validity::TransactionValidityError,
+};
+use sp_std::{fmt::Debug, marker::PhantomData};
+
+/// Trait that describes some properties of a `SignedExtension` that are needed in order to send a
+/// transaction to the chain.
+pub trait SignedExtensionSchema: Encode + Decode + Debug + Eq + Clone + StaticTypeInfo {
+	/// A type of the data encoded as part of the transaction.
+	type Payload: Encode + Decode + Debug + Eq + Clone + StaticTypeInfo;
+	/// Parameters which are part of the payload used to produce transaction signature,
+	/// but don't end up in the transaction itself (i.e. inherent part of the runtime).
+	type AdditionalSigned: Encode + Debug + Eq + Clone + StaticTypeInfo;
+}
+
+// An implementation of `SignedExtensionSchema` using generic params.
+#[derive(Encode, Decode, Clone, Debug, PartialEq, Eq, TypeInfo)]
+pub struct GenericSignedExtensionSchema<P, S>(PhantomData<(P, S)>);
+
+impl<P, S> SignedExtensionSchema for GenericSignedExtensionSchema<P, S>
+where
+	P: Encode + Decode + Debug + Eq + Clone + StaticTypeInfo,
+	S: Encode + Debug + Eq + Clone + StaticTypeInfo,
+{
+	type Payload = P;
+	type AdditionalSigned = S;
+}
+
+/// The `SignedExtensionSchema` for `frame_system::CheckNonZeroSender`.
+pub type CheckNonZeroSender = GenericSignedExtensionSchema<(), ()>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckSpecVersion`.
+pub type CheckSpecVersion = GenericSignedExtensionSchema<(), u32>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckTxVersion`.
+pub type CheckTxVersion = GenericSignedExtensionSchema<(), u32>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckGenesis`.
+pub type CheckGenesis<C> = GenericSignedExtensionSchema<(), HashOf<C>>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckEra`.
+pub type CheckEra<C> = GenericSignedExtensionSchema<sp_runtime::generic::Era, HashOf<C>>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckNonce`.
+pub type CheckNonce<TxIndex> = GenericSignedExtensionSchema<Compact<TxIndex>, ()>;
+
+/// The `SignedExtensionSchema` for `frame_system::CheckWeight`.
+pub type CheckWeight = GenericSignedExtensionSchema<(), ()>;
+
+/// The `SignedExtensionSchema` for `pallet_transaction_payment::ChargeTransactionPayment`.
+pub type ChargeTransactionPayment<C> = GenericSignedExtensionSchema<Compact<BalanceOf<C>>, ()>;
+
+/// The `SignedExtensionSchema` for `BridgeRejectObsoleteHeadersAndMessages`.
+pub type BridgeRejectObsoleteHeadersAndMessages = GenericSignedExtensionSchema<(), ()>;
+
+#[impl_for_tuples(1, 12)]
+impl SignedExtensionSchema for Tuple {
+	for_tuples!( type Payload = ( #( Tuple::Payload ),* ); );
+	for_tuples!( type AdditionalSigned = ( #( Tuple::AdditionalSigned ),* ); );
+}
+
+/// A simplified version of signed extensions meant for producing signed transactions
+/// and signed payloads in the client code.
+#[derive(Encode, Decode, Debug, PartialEq, Eq, Clone, TypeInfo)]
+pub struct GenericSignedExtension<S: SignedExtensionSchema> {
+	pub payload: S::Payload,
+	#[codec(skip)]
+	// It may be set to `None` if extensions are decoded. We are never reconstructing transactions
+	// (and it makes no sense to do that) => decoded version of `SignedExtensions` is only used to
+	// read fields of the `payload`. And when resigning transaction, we're reconstructing
+	// `SignedExtensions` from the scratch.
+	additional_signed: Option<S::AdditionalSigned>,
+}
+
+impl<S: SignedExtensionSchema> GenericSignedExtension<S> {
+	pub fn new(payload: S::Payload, additional_signed: S::AdditionalSigned) -> Self {
+		Self { payload, additional_signed: Some(additional_signed) }
+	}
+}
+
+impl<S> SignedExtension for GenericSignedExtension<S>
+where
+	S: SignedExtensionSchema,
+	S::Payload: Send + Sync,
+	S::AdditionalSigned: Send + Sync,
+{
+	const IDENTIFIER: &'static str = "Not needed.";
+	type AccountId = ();
+	type Call = ();
+	type AdditionalSigned = S::AdditionalSigned;
+	type Pre = ();
+
+	fn additional_signed(&self) -> Result<Self::AdditionalSigned, TransactionValidityError> {
+		// we shall not ever see this error in relay, because we are never signing decoded
+		// transactions. Instead we're constructing and signing new transactions. So the error code
+		// is kinda random here
+		self.additional_signed.clone().ok_or(
+			frame_support::unsigned::TransactionValidityError::Unknown(
+				frame_support::unsigned::UnknownTransaction::Custom(0xFF),
+			),
+		)
+	}
+
+	fn pre_dispatch(
+		self,
+		_who: &Self::AccountId,
+		_call: &Self::Call,
+		_info: &DispatchInfoOf<Self::Call>,
+		_len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(())
+	}
+}

bridges/primitives/runtime/src/lib.rs

@@ -47,6 +47,7 @@ pub use storage_types::BoundedStorageValue;
 #[cfg(feature = "std")]
 pub use storage_proof::craft_valid_storage_proof;
 
+pub mod extensions;
 pub mod messages;
 
 mod chain;