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// Copyright 2024 Moonbeam Foundation.
// 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/>.
use crate::{AssetId, Error, Pallet};
use ethereum_types::{BigEndianHash, H160, H256, U256};
use fp_evm::{ExitReason, ExitSucceed};
use frame_support::ensure;
use frame_support::pallet_prelude::Weight;
use pallet_evm::{GasWeightMapping, Runner};
use precompile_utils::prelude::*;
use precompile_utils::solidity::codec::{Address, BoundedString};
use precompile_utils::solidity::Codec;
use precompile_utils_macro::keccak256;
use sp_runtime::traits::ConstU32;
use sp_runtime::DispatchError;
use sp_std::vec::Vec;
use xcm::latest::Error as XcmError;
const ERC20_CALL_MAX_CALLDATA_SIZE: usize = 4 + 32 + 32; // selector + address + uint256
const ERC20_CREATE_MAX_CALLDATA_SIZE: usize = 16 * 1024; // 16Ko
// Hardcoded gas limits (from manual binary search)
const ERC20_CREATE_GAS_LIMIT: u64 = 3_410_000; // highest failure: 3_406_000
pub(crate) const ERC20_BURN_FROM_GAS_LIMIT: u64 = 155_000; // highest failure: 154_000
pub(crate) const ERC20_MINT_INTO_GAS_LIMIT: u64 = 155_000; // highest failure: 154_000
const ERC20_PAUSE_GAS_LIMIT: u64 = 150_500; // highest failure: 150_500
pub(crate) const ERC20_TRANSFER_GAS_LIMIT: u64 = 155_000; // highest failure: 154_000
pub(crate) const ERC20_APPROVE_GAS_LIMIT: u64 = 154_000; // highest failure: 153_000
const ERC20_UNPAUSE_GAS_LIMIT: u64 = 151_000; // highest failure: 149_500
pub enum EvmError {
BurnFromFail,
ContractReturnInvalidValue,
DispatchError(DispatchError),
EvmCallFail,
MintIntoFail,
TransferFail,
}
impl From<DispatchError> for EvmError {
fn from(e: DispatchError) -> Self {
Self::DispatchError(e)
impl From<EvmError> for XcmError {
fn from(error: EvmError) -> XcmError {
match error {
EvmError::BurnFromFail => {
XcmError::FailedToTransactAsset("Erc20 contract call burnFrom fail")
EvmError::ContractReturnInvalidValue => {
XcmError::FailedToTransactAsset("Erc20 contract return invalid value")
EvmError::DispatchError(err) => {
log::debug!("dispatch error: {:?}", err);
Self::FailedToTransactAsset("storage layer error")
EvmError::EvmCallFail => XcmError::FailedToTransactAsset("Fail to call erc20 contract"),
EvmError::MintIntoFail => {
XcmError::FailedToTransactAsset("Erc20 contract call mintInto fail")
EvmError::TransferFail => {
XcmError::FailedToTransactAsset("Erc20 contract call transfer fail")
#[derive(Codec)]
#[cfg_attr(test, derive(Debug))]
struct ForeignErc20ConstructorArgs {
owner: Address,
decimals: u8,
symbol: BoundedString<ConstU32<64>>,
token_name: BoundedString<ConstU32<256>>,
pub(crate) struct EvmCaller<T: crate::Config>(core::marker::PhantomData<T>);
impl<T: crate::Config> EvmCaller<T> {
/// Deploy foreign asset erc20 contract
pub(crate) fn erc20_create(
asset_id: AssetId,
symbol: &str,
token_name: &str,
) -> Result<H160, Error<T>> {
// Get init code
let mut init = Vec::with_capacity(ERC20_CREATE_MAX_CALLDATA_SIZE);
init.extend_from_slice(include_bytes!("../resources/foreign_erc20_initcode.bin"));
// Add constructor parameters
let args = ForeignErc20ConstructorArgs {
owner: Pallet::<T>::account_id().into(),
decimals,
symbol: symbol.into(),
token_name: token_name.into(),
};
let encoded_args = precompile_utils::solidity::codec::Writer::new()
.write(args)
.build();
// Skip size of constructor args (32 bytes)
init.extend_from_slice(&encoded_args[32..]);
let contract_adress = Pallet::<T>::contract_address_from_asset_id(asset_id);
let exec_info = T::EvmRunner::create_force_address(
Pallet::<T>::account_id(),
init,
U256::default(),
ERC20_CREATE_GAS_LIMIT,
None,
Default::default(),
false,
&<T as pallet_evm::Config>::config(),
contract_adress,
)
.map_err(|_| Error::Erc20ContractCreationFail)?;
ensure!(
matches!(
exec_info.exit_reason,
ExitReason::Succeed(ExitSucceed::Returned | ExitSucceed::Stopped)
),
Error::Erc20ContractCreationFail
);
Ok(contract_adress)
pub(crate) fn erc20_mint_into(
erc20_contract_address: H160,
beneficiary: H160,
amount: U256,
) -> Result<(), EvmError> {
let mut input = Vec::with_capacity(ERC20_CALL_MAX_CALLDATA_SIZE);
// Selector
input.extend_from_slice(&keccak256!("mintInto(address,uint256)")[..4]);
// append beneficiary address
input.extend_from_slice(H256::from(beneficiary).as_bytes());
// append amount to be minted
input.extend_from_slice(H256::from_uint(&amount).as_bytes());
let weight_limit: Weight =
T::GasWeightMapping::gas_to_weight(ERC20_MINT_INTO_GAS_LIMIT, true);
let exec_info = T::EvmRunner::call(
erc20_contract_address,
input,
ERC20_MINT_INTO_GAS_LIMIT,
Some(weight_limit),
Some(0),
.map_err(|_| EvmError::EvmCallFail)?;
EvmError::MintIntoFail
Ok(())
pub(crate) fn erc20_transfer(
from: H160,
to: H160,
input.extend_from_slice(&keccak256!("transfer(address,uint256)")[..4]);
// append receiver address
input.extend_from_slice(H256::from(to).as_bytes());
// append amount to be transferred
T::GasWeightMapping::gas_to_weight(ERC20_TRANSFER_GAS_LIMIT, true);
from,
ERC20_TRANSFER_GAS_LIMIT,
EvmError::TransferFail
// return value is true.
let mut bytes = [0u8; 32];
U256::from(1).to_big_endian(&mut bytes);
// Check return value to make sure not calling on empty contracts.
!exec_info.value.is_empty() && exec_info.value == bytes,
EvmError::ContractReturnInvalidValue
pub(crate) fn erc20_approve(
owner: H160,
spender: H160,
input.extend_from_slice(&keccak256!("approve(address,uint256)")[..4]);
// append spender address
input.extend_from_slice(H256::from(spender).as_bytes());
// append amount to be approved
T::GasWeightMapping::gas_to_weight(ERC20_APPROVE_GAS_LIMIT, true);
owner,
ERC20_APPROVE_GAS_LIMIT,
EvmError::EvmCallFail
pub(crate) fn erc20_burn_from(
who: H160,
input.extend_from_slice(&keccak256!("burnFrom(address,uint256)")[..4]);
// append who address
input.extend_from_slice(H256::from(who).as_bytes());
// append amount to be burn
T::GasWeightMapping::gas_to_weight(ERC20_BURN_FROM_GAS_LIMIT, true);
ERC20_BURN_FROM_GAS_LIMIT,
EvmError::BurnFromFail
// Call contract selector "pause"
pub(crate) fn erc20_pause(asset_id: AssetId) -> Result<(), Error<T>> {
input.extend_from_slice(&keccak256!("pause()")[..4]);
let weight_limit: Weight = T::GasWeightMapping::gas_to_weight(ERC20_PAUSE_GAS_LIMIT, true);
Pallet::<T>::contract_address_from_asset_id(asset_id),
ERC20_PAUSE_GAS_LIMIT,
.map_err(|_| Error::<T>::EvmInternalError)?;
Error::<T>::EvmCallPauseFail
// Call contract selector "unpause"
pub(crate) fn erc20_unpause(asset_id: AssetId) -> Result<(), Error<T>> {
input.extend_from_slice(&keccak256!("unpause()")[..4]);
T::GasWeightMapping::gas_to_weight(ERC20_UNPAUSE_GAS_LIMIT, true);
ERC20_UNPAUSE_GAS_LIMIT,
Error::<T>::EvmCallUnpauseFail