From 4a3d8395a0e4d714f59e4ec2dbcc3160a0671e37 Mon Sep 17 00:00:00 2001
From: Yaroslav Bolyukin <iam@lach.pw>
Date: Thu, 18 Nov 2021 13:48:07 +0000
Subject: [PATCH] feat: sponsor evm transactions coming from substrate


---
--- a/pallets/evm-transaction-payment/src/lib.rs
+++ b/pallets/evm-transaction-payment/src/lib.rs
@@ -1,100 +1,140 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
+use core::marker::PhantomData;
+use fp_evm::WithdrawReason;
+use frame_support::traits::{Currency, IsSubType};
 pub use pallet::*;
+use pallet_evm::{EVMCurrencyAdapter, EnsureAddressOrigin};
+use sp_core::{H160, U256};
+use sp_runtime::TransactionOutcome;
+use up_sponsorship::SponsorshipHandler;
 use up_evm_mapping::EvmBackwardsAddressMapping;
+use pallet_evm::AddressMapping;
 
 #[frame_support::pallet]
 pub mod pallet {
-	use core::marker::PhantomData;
+	use super::*;
+
 	use frame_support::traits::Currency;
-	use pallet_evm::EVMCurrencyAdapter;
-	use fp_evm::WithdrawReason;
-	use sp_core::{H160, U256};
-	use sp_runtime::TransactionOutcome;
-	use up_sponsorship::SponsorshipHandler;
 	use sp_std::vec::Vec;
 
-	type NegativeImbalanceOf<C, T> =
-		<C as Currency<<T as frame_system::Config>::AccountId>>::NegativeImbalance;
-
 	#[pallet::config]
 	pub trait Config: frame_system::Config {
-		type SponsorshipHandler: SponsorshipHandler<H160, (H160, Vec<u8>)>;
+		type EvmSponsorshipHandler: SponsorshipHandler<H160, (H160, Vec<u8>)>;
 		type Currency: Currency<Self::AccountId>;
 		type EvmBackwardsAddressMapping: EvmBackwardsAddressMapping<Self::AccountId>;
+		type EvmAddressMapping: AddressMapping<Self::AccountId>;
 	}
 
 	#[pallet::pallet]
 	#[pallet::generate_store(pub(super) trait Store)]
 	pub struct Pallet<T>(_);
+}
 
-	pub struct ChargeEvmLiquidityInfo<T>
-	where
-		T: Config,
-		T: pallet_evm::Config,
-	{
-		who: H160,
-		negative_imbalance: NegativeImbalanceOf<<T as Config>::Currency, T>,
+type NegativeImbalanceOf<C, T> =
+	<C as Currency<<T as frame_system::Config>::AccountId>>::NegativeImbalance;
+
+pub struct ChargeEvmLiquidityInfo<T>
+where
+	T: Config,
+	T: pallet_evm::Config,
+{
+	who: H160,
+	negative_imbalance: NegativeImbalanceOf<<T as Config>::Currency, T>,
+}
+
+pub struct TransactionValidityHack<T: Config>(PhantomData<*const T>);
+impl<T: Config> fp_evm::TransactionValidityHack for TransactionValidityHack<T> {
+	fn who_pays_fee(origin: H160, reason: &WithdrawReason) -> Option<H160> {
+		match reason {
+			WithdrawReason::Call { target, input } => {
+				// This method is only used for checking, we shouldn't touch storage in it
+				frame_support::storage::with_transaction(|| {
+					TransactionOutcome::Rollback(T::EvmSponsorshipHandler::get_sponsor(
+						&origin,
+						&(*target, input.clone()),
+					))
+				})
+			}
+			_ => None,
+		}
 	}
+}
+pub struct OnChargeTransaction<T: Config>(PhantomData<*const T>);
+impl<T> pallet_evm::OnChargeEVMTransaction<T> for OnChargeTransaction<T>
+where
+	T: Config,
+	T: pallet_evm::Config,
+{
+	type LiquidityInfo = Option<ChargeEvmLiquidityInfo<T>>;
 
-	pub struct TransactionValidityHack<T: Config>(PhantomData<*const T>);
-	impl<T: Config> fp_evm::TransactionValidityHack for TransactionValidityHack<T> {
-		fn who_pays_fee(origin: H160, reason: &WithdrawReason) -> Option<H160> {
-			match reason {
-				WithdrawReason::Call { target, input } => {
-					// This method is only used for checking, we shouldn't touch storage in it
-					frame_support::storage::with_transaction(|| {
-						TransactionOutcome::Rollback(T::SponsorshipHandler::get_sponsor(
-							&origin,
-							&(*target, input.clone()),
-						))
-					})
-				}
-				_ => None,
-			}
+	fn withdraw_fee(
+		who: &H160,
+		reason: WithdrawReason,
+		fee: U256,
+	) -> core::result::Result<Self::LiquidityInfo, pallet_evm::Error<T>> {
+		let mut who_pays_fee = *who;
+		if let WithdrawReason::Call { target, input } = &reason {
+			who_pays_fee = T::EvmSponsorshipHandler::get_sponsor(who, &(*target, input.clone()))
+				.unwrap_or(who_pays_fee);
 		}
+		let negative_imbalance = EVMCurrencyAdapter::<<T as Config>::Currency, ()>::withdraw_fee(
+			&who_pays_fee,
+			reason,
+			fee,
+		)?;
+		Ok(negative_imbalance.map(|i| ChargeEvmLiquidityInfo {
+			who: who_pays_fee,
+			negative_imbalance: i,
+		}))
 	}
 
-	pub struct OnChargeTransaction<T: Config>(PhantomData<*const T>);
-	impl<T> pallet_evm::OnChargeEVMTransaction<T> for OnChargeTransaction<T>
-	where
-		T: Config,
-		T: pallet_evm::Config,
-	{
-		type LiquidityInfo = Option<ChargeEvmLiquidityInfo<T>>;
+	fn correct_and_deposit_fee(
+		who: &H160,
+		corrected_fee: U256,
+		already_withdrawn: Self::LiquidityInfo,
+	) {
+		<EVMCurrencyAdapter<<T as Config>::Currency, ()> as pallet_evm::OnChargeEVMTransaction<T>>::correct_and_deposit_fee(
+			&already_withdrawn.as_ref().map(|e| e.who).unwrap_or(*who),
+			corrected_fee,
+			already_withdrawn.map(|e| e.negative_imbalance),
+		)
+	}
+}
 
-		fn withdraw_fee(
-			who: &H160,
-			reason: WithdrawReason,
-			fee: U256,
-		) -> core::result::Result<Self::LiquidityInfo, pallet_evm::Error<T>> {
-			let mut who_pays_fee = *who;
-			if let WithdrawReason::Call { target, input } = &reason {
-				who_pays_fee = T::SponsorshipHandler::get_sponsor(who, &(*target, input.clone()))
-					.unwrap_or(who_pays_fee);
+/// Implements sponsoring for evm calls performed from pallet-evm (via api.tx.ethereum.transact/api.tx.evm.call)
+pub struct BridgeSponsorshipHandler<T>(PhantomData<T>);
+impl<T, C> SponsorshipHandler<T::AccountId, C> for BridgeSponsorshipHandler<T>
+where
+	T: Config + pallet_evm::Config,
+	C: IsSubType<pallet_evm::Call<T>>,
+{
+	fn get_sponsor(who: &T::AccountId, call: &C) -> Option<T::AccountId> {
+		match call.is_sub_type()? {
+			pallet_evm::Call::call {
+				source,
+				target,
+				input,
+				..
+			} => {
+				let _ = T::CallOrigin::ensure_address_origin(
+					source,
+					<frame_system::RawOrigin<T::AccountId>>::Signed(who.clone()).into(),
+				)
+				.ok()?;
+				let who = T::EvmBackwardsAddressMapping::from_account_id(who.clone());
+				// Effects from EvmSponsorshipHandler are applied in OnChargeEvmTransaction by pallet_evm::runner
+				// TODO: Should we implement simulation mode (test, but do not apply effects) in `up-sponsorship`?
+				let sponsor = frame_support::storage::with_transaction(|| {
+					TransactionOutcome::Rollback(T::EvmSponsorshipHandler::get_sponsor(
+						&who,
+						&(target.clone(), input.clone()),
+					))
+				})?;
+				let sponsor = T::EvmAddressMapping::into_account_id(sponsor);
+				Some(sponsor)
 			}
-			let negative_imbalance =
-				EVMCurrencyAdapter::<<T as Config>::Currency, ()>::withdraw_fee(
-					&who_pays_fee,
-					reason,
-					fee,
-				)?;
-			Ok(negative_imbalance.map(|i| ChargeEvmLiquidityInfo {
-				who: who_pays_fee,
-				negative_imbalance: i,
-			}))
-		}
-
-		fn correct_and_deposit_fee(
-			who: &H160,
-			corrected_fee: U256,
-			already_withdrawn: Self::LiquidityInfo,
-		) {
-			<EVMCurrencyAdapter<<T as Config>::Currency, ()> as pallet_evm::OnChargeEVMTransaction<T>>::correct_and_deposit_fee(
-				&already_withdrawn.as_ref().map(|e| e.who).unwrap_or(*who),
-				corrected_fee,
-				already_withdrawn.map(|e| e.negative_imbalance),
-			)
+			_ => None,
 		}
 	}
 }
--- a/runtime/src/lib.rs
+++ b/runtime/src/lib.rs
@@ -777,20 +777,14 @@
 	pub const MaxScheduledPerBlock: u32 = 50;
 }
 
-pub struct Sponsoring;
-impl SponsoringResolve<AccountId, Call> for Sponsoring {
-	fn resolve(who: &AccountId, call: &Call) -> Option<AccountId>
-	where
-		Call: Dispatchable<Info = DispatchInfo>,
-		AccountId: AsRef<[u8]>,
-	{
-		pallet_nft_transaction_payment::Module::<Runtime>::withdraw_type(who, call)
-	}
-}
-
+type EvmSponsorshipHandler = (
+	pallet_nft::NftEthSponsorshipHandler<Runtime>,
+	pallet_evm_contract_helpers::HelpersContractSponsoring<Runtime>,
+);
 type SponsorshipHandler = (
 	pallet_nft::NftSponsorshipHandler<Runtime>,
 	//pallet_contract_helpers::ContractSponsorshipHandler<Runtime>,
+	pallet_evm_transaction_payment::BridgeSponsorshipHandler<Runtime>,
 );
 
 impl pallet_unq_scheduler::Config for Runtime {
@@ -806,16 +800,14 @@
 }
 
 impl pallet_evm_transaction_payment::Config for Runtime {
-	type SponsorshipHandler = (
-		pallet_nft::NftEthSponsorshipHandler<Self>,
-		pallet_evm_contract_helpers::HelpersContractSponsoring<Self>,
-	);
+	type EvmSponsorshipHandler = EvmSponsorshipHandler;
 	type Currency = Balances;
+	type EvmAddressMapping = HashedAddressMapping<Self::Hashing>;
 	type EvmBackwardsAddressMapping = up_evm_mapping::MapBackwardsAddressTruncated;
 }
 
 impl pallet_nft_charge_transaction::Config for Runtime {
-	type SponsorshipHandler = pallet_nft::NftSponsorshipHandler<Runtime>;
+	type SponsorshipHandler = SponsorshipHandler;
 }
 
 // impl pallet_contract_helpers::Config for Runtime {

-- 
gitstuff