feat: implement eth_get_balance (#990)

* implement eth_get_balance

* add missing files

* made requested changes

* fmt

---------

Co-authored-by: enitrat <msaug@protonmail.com>

crates/contracts/src/kakarot_core/eth_rpc.cairo

@@ -8,6 +8,7 @@ use evm::backend::starknet_backend;
 use evm::backend::validation::validate_eth_tx;
 use evm::model::{TransactionResult, Address};
 use evm::{EVMTrait};
+use openzeppelin::token::erc20::interface::{IERC20CamelDispatcher, IERC20CamelDispatcherTrait};
 use utils::constants::POW_2_53;
 use utils::eth_transaction::transaction::Transaction;
 
@@ -123,7 +124,11 @@ pub impl EthRPC<
     TContractState, impl KakarotState: KakarotCoreState<TContractState>, +Drop<TContractState>
 > of IEthRPC<TContractState> {
     fn eth_get_balance(self: @TContractState, address: EthAddress) -> u256 {
-        panic!("unimplemented")
+        let kakarot_state = KakarotState::get_state();
+        let starknet_address = kakarot_state.get_starknet_address(address);
+        let native_token_address = kakarot_state.get_native_token();
+        let native_token = IERC20CamelDispatcher { contract_address: native_token_address };
+        native_token.balanceOf(starknet_address)
     }
 
     fn eth_get_transaction_count(self: @TContractState, address: EthAddress) -> u64 {
@@ -218,6 +223,9 @@ fn is_view(self: @KakarotCore::ContractState) -> bool {
 mod tests {
     use crate::kakarot_core::KakarotCore;
     use crate::kakarot_core::eth_rpc::IEthRPC;
+    use crate::kakarot_core::interface::IExtendedKakarotCoreDispatcherTrait;
+    use crate::test_utils::{setup_contracts_for_testing, fund_account_with_native_token};
+    use evm::test_utils::{sequencer_evm_address, evm_address};
     use snforge_std::{start_cheat_chain_id_global, stop_cheat_chain_id_global};
     use utils::constants::POW_2_53;
 
@@ -232,6 +240,16 @@ mod tests {
         stop_cheat_chain_id_global();
     }
 
+    #[test]
+    fn test_eth_get_balance() {
+        let (native_token, kakarot_core) = setup_contracts_for_testing();
+        // Uninitialized accounts should return a zero balance
+        assert_eq!(kakarot_core.eth_get_balance(evm_address()), 0);
+        let sequencer_starknet_address = kakarot_core.get_starknet_address(sequencer_evm_address());
+        // Fund an initialized account and make sure the balance is correct
+        fund_account_with_native_token(sequencer_starknet_address, native_token, 0x1);
+        assert_eq!(kakarot_core.eth_get_balance(sequencer_evm_address()), 0x1);
+    }
 
     #[test]
     fn test_eth_chain_id_returns_input_when_less_than_pow_2_53() {

crates/contracts/src/kakarot_core/interface.cairo

@@ -74,6 +74,9 @@ pub trait IExtendedKakarotCore<TContractState> {
         ref self: TContractState, evm_address: EthAddress
     ) -> ContractAddress;
 
+    /// Returns the balance of the specified address.
+    fn eth_get_balance(self: @TContractState, address: EthAddress) -> u256;
+
     /// View entrypoint into the EVM
     /// Performs view calls into the blockchain
     /// It cannot modify the state of the chain

crates/contracts/src/kakarot_core/kakarot.cairo

@@ -211,7 +211,7 @@ pub mod KakarotCore {
         // @return starknet_address The Starknet Account Contract address
         fn get_starknet_address(self: @ContractState, evm_address: EthAddress) -> ContractAddress {
             let registered_starknet_address = self.address_registry(evm_address);
-            if (registered_starknet_address.is_zero()) {
+            if (!registered_starknet_address.is_zero()) {
                 return registered_starknet_address;
             }
 

crates/evm/src/backend/starknet_backend.cairo

@@ -121,9 +121,7 @@ pub fn fetch_original_storage(account: @Account, key: u256) -> u256 {
 /// The balance of the given address.
 pub fn fetch_balance(self: @Address) -> u256 {
     let kakarot_state = KakarotCore::unsafe_new_contract_state();
-    let native_token_address = kakarot_state.get_native_token();
-    let native_token = IERC20CamelDispatcher { contract_address: native_token_address };
-    native_token.balanceOf(*self.starknet)
+    kakarot_state.eth_get_balance(*self.evm)
 }
 
 

crates/evm/src/backend/validation.cairo

@@ -5,7 +5,6 @@ use core::ops::SnapshotDeref;
 use core::starknet::storage::{StoragePointerReadAccess};
 use core::starknet::{get_caller_address};
 use crate::gas;
-use openzeppelin::token::erc20::interface::{IERC20CamelDispatcher, IERC20CamelDispatcherTrait};
 use starknet::storage::StorageTrait;
 use utils::eth_transaction::check_gas_fee;
 use utils::eth_transaction::transaction::{Transaction, TransactionTrait};
@@ -46,10 +45,7 @@ pub fn validate_eth_tx(kakarot_state: @KakarotCore::ContractState, tx: Transacti
     assert(gas_limit >= intrinsic_gas, 'Intrinsic gas > gas limit');
 
     // Validate balance
-    let balance = IERC20CamelDispatcher {
-        contract_address: kakarot_storage.Kakarot_native_token_address.read()
-    }
-        .balanceOf(starknet_caller_address);
+    let balance = kakarot_state.eth_get_balance(account.get_evm_address());
     let max_gas_fee = tx.gas_limit().into() * tx.max_fee_per_gas();
     let tx_cost = tx.value() + max_gas_fee.into();
     assert(tx_cost <= balance, 'Not enough ETH');
@@ -61,11 +57,10 @@ mod tests {
     use contracts::kakarot_core::KakarotCore;
     use core::num::traits::Bounded;
     use core::ops::SnapshotDeref;
-
-    use core::starknet::ContractAddress;
-    use core::starknet::storage::StorageTrait;
+    use core::starknet::storage::{StorageTrait, StoragePathEntry};
+    use core::starknet::{EthAddress, ContractAddress};
     use evm::gas;
-    use snforge_std::cheatcodes::storage::store_felt252;
+    use snforge_std::cheatcodes::storage::{store_felt252};
     use snforge_std::{
         start_mock_call, test_address, start_cheat_chain_id_global, store,
         start_cheat_caller_address, mock_call
@@ -82,6 +77,7 @@ mod tests {
         let kakarot_state = KakarotCore::unsafe_new_contract_state();
         let kakarot_storage = kakarot_state.snapshot_deref().storage();
         let kakarot_address = test_address();
+        let account_evm_address: EthAddress = 'account_evm_address'.try_into().unwrap();
         let account_starknet_address = 'account_starknet_address'.try_into().unwrap();
         let native_token_address = 'native_token_address'.try_into().unwrap();
 
@@ -95,10 +91,23 @@ mod tests {
         store_felt252(kakarot_address, base_fee_storage, 1_000_000_000); // 1 Gwei
         store_felt252(kakarot_address, block_gas_limit_storage, BLOCK_GAS_LIMIT.into());
         store_felt252(kakarot_address, native_token_storage_address, native_token_address.into());
+        let map_entry_address = kakarot_storage
+            .Kakarot_evm_to_starknet_address
+            .entry(account_evm_address)
+            .deref()
+            .__storage_pointer_address__;
+        store(
+            kakarot_address,
+            map_entry_address.into(),
+            array![account_starknet_address.into()].span()
+        );
 
         // Mock the calls to the account contract and the native token contract
         start_cheat_caller_address(kakarot_address, account_starknet_address);
         start_mock_call(account_starknet_address, selector!("get_nonce"), 0);
+        start_mock_call(
+            account_starknet_address, selector!("get_evm_address"), account_evm_address
+        );
         start_mock_call(
             native_token_address, selector!("balanceOf"), Bounded::<u256>::MAX
         ); // Min to pay for gas + value