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// Copyright 2019-2022 PureStake Inc.
// This file is part of Moonbeam.
// Moonbeam 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.
// Moonbeam 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 Moonbeam. If not, see <http://www.gnu.org/licenses/>.
//! # Ethereum Xcm pallet
//!
//! The Xcm Ethereum pallet is a bridge for Xcm Transact to Ethereum pallet
// Ensure we're `no_std` when compiling for Wasm.
#![cfg_attr(not(feature = "std"), no_std)]
#![allow(clippy::comparison_chain, clippy::large_enum_variant)]
#[cfg(all(feature = "std", test))]
mod mock;
mod tests;
use ethereum_types::{H160, H256, U256};
use fp_ethereum::{TransactionData, ValidatedTransaction};
use fp_evm::{CheckEvmTransaction, CheckEvmTransactionConfig, TransactionValidationError};
use frame_support::{
dispatch::{DispatchResultWithPostInfo, Pays, PostDispatchInfo},
traits::{EnsureOrigin, Get, ProcessMessage},
weights::Weight,
};
use frame_system::pallet_prelude::OriginFor;
use pallet_evm::{AddressMapping, GasWeightMapping};
use parity_scale_codec::{Decode, Encode, MaxEncodedLen};
use scale_info::TypeInfo;
use sp_runtime::{traits::UniqueSaturatedInto, DispatchErrorWithPostInfo, RuntimeDebug};
use sp_std::{marker::PhantomData, prelude::*};
pub use ethereum::{
AccessListItem, BlockV2 as Block, LegacyTransactionMessage, Log, ReceiptV3 as Receipt,
TransactionAction, TransactionV2 as Transaction,
pub use fp_rpc::TransactionStatus;
pub use xcm_primitives::{EnsureProxy, EthereumXcmTransaction, XcmToEthereum};
#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug, TypeInfo, MaxEncodedLen)]
pub enum RawOrigin {
XcmEthereumTransaction(H160),
}
pub fn ensure_xcm_ethereum_transaction<OuterOrigin>(o: OuterOrigin) -> Result<H160, &'static str>
where
OuterOrigin: Into<Result<RawOrigin, OuterOrigin>>,
{
match o.into() {
Ok(RawOrigin::XcmEthereumTransaction(n)) => Ok(n),
_ => Err("bad origin: expected to be a xcm Ethereum transaction"),
pub struct EnsureXcmEthereumTransaction;
impl<O: Into<Result<RawOrigin, O>> + From<RawOrigin>> EnsureOrigin<O>
for EnsureXcmEthereumTransaction
type Success = H160;
fn try_origin(o: O) -> Result<Self::Success, O> {
o.into().map(|o| match o {
RawOrigin::XcmEthereumTransaction(id) => id,
})
#[cfg(feature = "runtime-benchmarks")]
fn try_successful_origin() -> Result<O, ()> {
Ok(O::from(RawOrigin::XcmEthereumTransaction(
Default::default(),
)))
environmental::environmental!(XCM_MESSAGE_HASH: H256);
pub struct MessageProcessorWrapper<Inner>(core::marker::PhantomData<Inner>);
impl<Inner: ProcessMessage> ProcessMessage for MessageProcessorWrapper<Inner> {
type Origin = <Inner as ProcessMessage>::Origin;
fn process_message(
message: &[u8],
origin: Self::Origin,
meter: &mut frame_support::weights::WeightMeter,
id: &mut [u8; 32],
) -> Result<bool, frame_support::traits::ProcessMessageError> {
let mut xcm_msg_hash = H256(sp_io::hashing::blake2_256(message));
XCM_MESSAGE_HASH::using(&mut xcm_msg_hash, || {
Inner::process_message(message, origin, meter, id)
pub use self::pallet::*;
#[frame_support::pallet(dev_mode)]
pub mod pallet {
use super::*;
use frame_support::pallet_prelude::*;
#[pallet::config]
pub trait Config: frame_system::Config + pallet_evm::Config {
/// The overarching event type.
type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
/// Invalid transaction error
type InvalidEvmTransactionError: From<TransactionValidationError>;
/// Handler for applying an already validated transaction
type ValidatedTransaction: ValidatedTransaction;
/// Origin for xcm transact
type XcmEthereumOrigin: EnsureOrigin<Self::RuntimeOrigin, Success = H160>;
/// Maximum Weight reserved for xcm in a block
type ReservedXcmpWeight: Get<Weight>;
/// Ensure proxy
type EnsureProxy: EnsureProxy<Self::AccountId>;
/// The origin that is allowed to resume or suspend the XCM to Ethereum executions.
type ControllerOrigin: EnsureOrigin<Self::RuntimeOrigin>;
/// An origin that can submit a create tx type
type ForceOrigin: EnsureOrigin<Self::RuntimeOrigin>;
#[pallet::pallet]
#[pallet::without_storage_info]
pub struct Pallet<T>(PhantomData<T>);
/// Global nonce used for building Ethereum transaction payload.
#[pallet::storage]
#[pallet::getter(fn nonce)]
pub(crate) type Nonce<T: Config> = StorageValue<_, U256, ValueQuery>;
/// Whether or not Ethereum-XCM is suspended from executing
#[pallet::getter(fn ethereum_xcm_suspended)]
pub(super) type EthereumXcmSuspended<T: Config> = StorageValue<_, bool, ValueQuery>;
#[pallet::origin]
pub type Origin = RawOrigin;
#[pallet::error]
pub enum Error<T> {
/// Xcm to Ethereum execution is suspended
EthereumXcmExecutionSuspended,
#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T> {
/// Ethereum transaction executed from XCM
ExecutedFromXcm {
xcm_msg_hash: H256,
eth_tx_hash: H256,
},
#[pallet::call]
impl<T: Config> Pallet<T>
OriginFor<T>: Into<Result<RawOrigin, OriginFor<T>>>,
/// Xcm Transact an Ethereum transaction.
/// Weight: Gas limit plus the db read involving the suspension check
#[pallet::weight({
let without_base_extrinsic_weight = false;
<T as pallet_evm::Config>::GasWeightMapping::gas_to_weight({
match xcm_transaction {
EthereumXcmTransaction::V1(v1_tx) => v1_tx.gas_limit.unique_saturated_into(),
EthereumXcmTransaction::V2(v2_tx) => v2_tx.gas_limit.unique_saturated_into()
}, without_base_extrinsic_weight).saturating_add(T::DbWeight::get().reads(1))
})]
pub fn transact(
origin: OriginFor<T>,
xcm_transaction: EthereumXcmTransaction,
) -> DispatchResultWithPostInfo {
let source = T::XcmEthereumOrigin::ensure_origin(origin)?;
ensure!(
!EthereumXcmSuspended::<T>::get(),
DispatchErrorWithPostInfo {
error: Error::<T>::EthereumXcmExecutionSuspended.into(),
post_info: PostDispatchInfo {
actual_weight: Some(T::DbWeight::get().reads(1)),
pays_fee: Pays::Yes
);
Self::validate_and_apply(source, xcm_transaction, false, None)
/// Xcm Transact an Ethereum transaction through proxy.
/// Weight: Gas limit plus the db reads involving the suspension and proxy checks
}, without_base_extrinsic_weight).saturating_add(T::DbWeight::get().reads(2))
pub fn transact_through_proxy(
transact_as: H160,
let _ = T::EnsureProxy::ensure_ok(
T::AddressMapping::into_account_id(transact_as),
T::AddressMapping::into_account_id(source),
)
.map_err(|e| sp_runtime::DispatchErrorWithPostInfo {
actual_weight: Some(T::DbWeight::get().reads(2)),
pays_fee: Pays::Yes,
error: sp_runtime::DispatchError::Other(e),
})?;
Self::validate_and_apply(transact_as, xcm_transaction, false, None)
/// Suspends all Ethereum executions from XCM.
///
/// - `origin`: Must pass `ControllerOrigin`.
#[pallet::weight((T::DbWeight::get().writes(1), DispatchClass::Operational,))]
pub fn suspend_ethereum_xcm_execution(origin: OriginFor<T>) -> DispatchResult {
T::ControllerOrigin::ensure_origin(origin)?;
EthereumXcmSuspended::<T>::put(true);
Ok(())
/// Resumes all Ethereum executions from XCM.
pub fn resume_ethereum_xcm_execution(origin: OriginFor<T>) -> DispatchResult {
EthereumXcmSuspended::<T>::put(false);
/// Xcm Transact an Ethereum transaction, but allow to force the caller and create address.
/// This call should be restricted (callable only by the runtime or governance).
pub fn force_transact_as(
force_create_address: Option<H160>,
T::ForceOrigin::ensure_origin(origin)?;
Self::validate_and_apply(transact_as, xcm_transaction, true, force_create_address)
impl<T: Config> Pallet<T> {
fn transaction_len(transaction: &Transaction) -> u64 {
transaction
.encode()
.len()
// pallet + call indexes
.saturating_add(2) as u64
fn validate_and_apply(
source: H160,
allow_create: bool,
maybe_force_create_address: Option<H160>,
// The lack of a real signature where different callers with the
// same nonce are providing identical transaction payloads results in a collision and
// the same ethereum tx hash.
// We use a global nonce instead the user nonce for all Xcm->Ethereum transactions to avoid
// this.
let current_nonce = Self::nonce();
let error_weight = T::DbWeight::get().reads(1);
let transaction: Option<Transaction> =
xcm_transaction.into_transaction_v2(current_nonce, T::ChainId::get(), allow_create);
if let Some(transaction) = transaction {
let tx_hash = transaction.hash();
let transaction_data: TransactionData = (&transaction).into();
let (weight_limit, proof_size_base_cost) =
match <T as pallet_evm::Config>::GasWeightMapping::gas_to_weight(
transaction_data.gas_limit.unique_saturated_into(),
true,
) {
weight_limit if weight_limit.proof_size() > 0 => (
Some(weight_limit),
Some(Self::transaction_len(&transaction)),
),
_ => (None, None),
let _ = CheckEvmTransaction::<T::InvalidEvmTransactionError>::new(
CheckEvmTransactionConfig {
evm_config: T::config(),
block_gas_limit: U256::from(
<T as pallet_evm::Config>::GasWeightMapping::weight_to_gas(
T::ReservedXcmpWeight::get(),
base_fee: U256::zero(),
chain_id: 0u64,
is_transactional: true,
transaction_data.into(),
weight_limit,
proof_size_base_cost,
// We only validate the gas limit against the evm transaction cost.
// No need to validate fee payment, as it is handled by the xcm executor.
.validate_common()
.map_err(|_| sp_runtime::DispatchErrorWithPostInfo {
actual_weight: Some(error_weight),
error: sp_runtime::DispatchError::Other("Failed to validate ethereum transaction"),
// Once we know a new transaction hash exists - the user can afford storing the
// transaction on chain - we increase the global nonce.
<Nonce<T>>::put(current_nonce.saturating_add(U256::one()));
let (dispatch_info, _) =
T::ValidatedTransaction::apply(source, transaction, maybe_force_create_address)?;
XCM_MESSAGE_HASH::with(|xcm_msg_hash| {
Self::deposit_event(Event::ExecutedFromXcm {
xcm_msg_hash: *xcm_msg_hash,
eth_tx_hash: tx_hash,
});
Ok(dispatch_info)
} else {
Err(sp_runtime::DispatchErrorWithPostInfo {
error: sp_runtime::DispatchError::Other("Cannot convert xcm payload to known type"),