Merge branch 'feat/funds-allocation' into 'master'

Feat/funds allocation

Closes #6

See merge request aave-tech/protocol-v2!4

contracts/flashloan/base/FlashLoanReceiverBase.sol

@@ -6,6 +6,7 @@ import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
 import '../interfaces/IFlashLoanReceiver.sol';
 import '../../interfaces/ILendingPoolAddressesProvider.sol';
 import '../../libraries/UniversalERC20.sol';
+import '@nomiclabs/buidler/console.sol';
 
 abstract contract FlashLoanReceiverBase is IFlashLoanReceiver {
   using UniversalERC20 for IERC20;
@@ -19,10 +20,12 @@ abstract contract FlashLoanReceiverBase is IFlashLoanReceiver {
 
   receive() external payable {}
 
-  function transferFundsBackToPoolInternal(address _reserve, uint256 _amount) internal {
-    address payable pool = payable(addressesProvider.getLendingPool());
-
-    transferInternal(pool, _reserve, _amount);
+  function transferFundsBackInternal(
+    address _reserve,
+    address _destination,
+    uint256 _amount
+  ) internal {
+    transferInternal(payable(_destination), _reserve, _amount);
   }
 
   function transferInternal(
@@ -30,12 +33,6 @@ abstract contract FlashLoanReceiverBase is IFlashLoanReceiver {
     address _reserve,
     uint256 _amount
   ) internal {
-    if (IERC20(_reserve).isETH()) {
-      //solium-disable-next-line
-      _destination.call{value: _amount}('');
-      return;
-    }
-
     IERC20(_reserve).universalTransfer(_destination, _amount);
   }
 

contracts/flashloan/interfaces/IFlashLoanReceiver.sol

@@ -10,6 +10,7 @@ pragma solidity ^0.6.8;
 interface IFlashLoanReceiver {
   function executeOperation(
     address _reserve,
+    address _destination,
     uint256 _amount,
     uint256 _fee,
     bytes calldata _params

contracts/lendingpool/LendingPool.sol

@@ -262,7 +262,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
 
     ValidationLogic.validateDeposit(reserve, _amount);
 
-    AToken aToken = AToken(reserve.aTokenAddress);
+    AToken aToken = AToken(payable(reserve.aTokenAddress));
 
     bool isFirstDeposit = aToken.balanceOf(msg.sender) == 0;
 
@@ -276,8 +276,8 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
     //minting AToken to user 1:1 with the specific exchange rate
     aToken.mintOnDeposit(msg.sender, _amount);
 
-    //transfer to the core contract
-    IERC20(_reserve).universalTransferFromSenderToThis(_amount, true);
+    //transfer to the aToken contract
+    IERC20(_reserve).universalTransferFrom(msg.sender, address(aToken), _amount, true);
 
     //solium-disable-next-line
     emit Deposit(_reserve, msg.sender, _amount, _referralCode, block.timestamp);
@@ -299,16 +299,19 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
     ReserveLogic.ReserveData storage reserve = reserves[_reserve];
     UserLogic.UserReserveData storage user = usersReserveData[_user][_reserve];
 
+    AToken aToken = AToken(payable(reserve.aTokenAddress));
+
     ValidationLogic.validateRedeem(reserve, _reserve, _amount);
 
+    reserve.updateCumulativeIndexesAndTimestamp();
+
+    reserve.updateInterestRates(_reserve, 0, _amount);
+
     if (_aTokenBalanceAfterRedeem == 0) {
       user.useAsCollateral = false;
     }
 
-    reserve.updateCumulativeIndexesAndTimestamp();
-    reserve.updateInterestRates(_reserve, 0, _amount);
-
-    IERC20(_reserve).universalTransfer(_user, _amount);
+    AToken(reserve.aTokenAddress).transferUnderlyingTo(_user, _amount);
 
     //solium-disable-next-line
     emit RedeemUnderlying(_reserve, _user, _amount, block.timestamp);
@@ -368,7 +371,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
     reserve.updateInterestRates(_reserve, 0, _amount);
 
     //if we reached this point, we can transfer
-    IERC20(_reserve).universalTransfer(msg.sender, _amount);
+    AToken(reserve.aTokenAddress).transferUnderlyingTo(msg.sender, _amount);
 
     emit Borrow(
       _reserve,
@@ -446,7 +449,12 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
 
     reserve.updateInterestRates(_reserve, vars.paybackAmount, 0);
 
-    IERC20(_reserve).universalTransferFromSenderToThis(vars.paybackAmount, false);
+    IERC20(_reserve).universalTransferFrom(
+      msg.sender,
+      reserve.aTokenAddress,
+      vars.paybackAmount,
+      false
+    );
 
     if (IERC20(_reserve).isETH()) {
       //send excess ETH back to the caller if needed
@@ -635,6 +643,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
     uint256 protocolFeeBips;
     uint256 amountFee;
     uint256 protocolFee;
+    address payable aTokenAddress;
   }
 
   /**
@@ -655,8 +664,10 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
 
     ReserveLogic.ReserveData storage reserve = reserves[_reserve];
 
+    vars.aTokenAddress = payable(reserve.aTokenAddress);
+
     //check that the reserve has enough available liquidity
-    vars.availableLiquidityBefore = IERC20(_reserve).universalBalanceOf(address(this));
+    vars.availableLiquidityBefore = IERC20(_reserve).universalBalanceOf(vars.aTokenAddress);
 
     //calculate amount fee
     vars.amountFee = _amount.mul(FLASHLOAN_FEE_TOTAL).div(10000);
@@ -679,13 +690,13 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
     address payable userPayable = address(uint160(_receiver));
 
     //transfer funds to the receiver
-    IERC20(_reserve).universalTransfer(userPayable, _amount);
+    AToken(vars.aTokenAddress).transferUnderlyingTo(userPayable, _amount);
 
     //execute action of the receiver
-    receiver.executeOperation(_reserve, _amount, vars.amountFee, _params);
+    receiver.executeOperation(_reserve, vars.aTokenAddress, _amount, vars.amountFee, _params);
 
     //check that the actual balance of the core contract includes the returned amount
-    uint256 availableLiquidityAfter = IERC20(_reserve).universalBalanceOf(address(this));
+    uint256 availableLiquidityAfter = IERC20(_reserve).universalBalanceOf(vars.aTokenAddress);
 
     require(
       availableLiquidityAfter == vars.availableLiquidityBefore.add(vars.amountFee),
@@ -699,7 +710,11 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
       vars.protocolFee
     );
 
-    IERC20(_reserve).universalTransfer(addressesProvider.getTokenDistributor(), vars.protocolFee);
+    //transfer funds to the receiver
+    AToken(vars.aTokenAddress).transferUnderlyingTo(
+      addressesProvider.getTokenDistributor(),
+      vars.protocolFee
+    );
 
     //solium-disable-next-line
     emit FlashLoan(_receiver, _reserve, _amount, vars.amountFee, vars.protocolFee, block.timestamp);
@@ -777,7 +792,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
   {
     ReserveLogic.ReserveData memory reserve = reserves[_reserve];
     return (
-      IERC20(_reserve).universalBalanceOf(address(this)),
+      IERC20(_reserve).universalBalanceOf(reserve.aTokenAddress),
       IERC20(reserve.stableDebtTokenAddress).totalSupply(),
       IERC20(reserve.variableDebtTokenAddress).totalSupply(),
       reserve.currentLiquidityRate,

contracts/lendingpool/LendingPoolLiquidationManager.sol

@@ -201,13 +201,21 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
     //of _collateral to cover the actual amount that is being liquidated, hence we liquidate
     //a smaller amount
 
+    vars.collateralAtoken = AToken(payable(collateralReserve.aTokenAddress));
+
+    //if principalAmountNeeded < vars.ActualAmountToLiquidate, there isn't enough
+    //of _collateral to cover the actual amount that is being liquidated, hence we liquidate
+    //a smaller amount
+
     if (vars.principalAmountNeeded < vars.actualAmountToLiquidate) {
       vars.actualAmountToLiquidate = vars.principalAmountNeeded;
     }
 
     //if liquidator reclaims the underlying asset, we make sure there is enough available collateral in the reserve
     if (!_receiveAToken) {
-      uint256 currentAvailableCollateral = IERC20(_collateral).universalBalanceOf(address(this));
+      uint256 currentAvailableCollateral = IERC20(_collateral).universalBalanceOf(
+        address(vars.collateralAtoken)
+      );
       if (currentAvailableCollateral < vars.maxCollateralToLiquidate) {
         return (
           uint256(LiquidationErrors.NOT_ENOUGH_LIQUIDITY),
@@ -216,7 +224,6 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
       }
     }
 
-    //TODO Burn debt tokens
     if (vars.userVariableDebt >= vars.actualAmountToLiquidate) {
       IVariableDebtToken(principalReserve.variableDebtTokenAddress).burn(
         _user,
@@ -233,8 +240,6 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
       );
     }
 
-    vars.collateralAtoken = AToken(collateralReserve.aTokenAddress);
-
     //if liquidator reclaims the aToken, he receives the equivalent atoken amount
     if (_receiveAToken) {
       vars.collateralAtoken.transferOnLiquidation(_user, msg.sender, vars.maxCollateralToLiquidate);
@@ -242,12 +247,16 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
       //otherwise receives the underlying asset
       //burn the equivalent amount of atoken
       vars.collateralAtoken.burnOnLiquidation(_user, vars.maxCollateralToLiquidate);
-
-      IERC20(_collateral).universalTransfer(msg.sender, vars.maxCollateralToLiquidate);
+      vars.collateralAtoken.transferUnderlyingTo(msg.sender, vars.maxCollateralToLiquidate);
     }
 
-    //transfers the principal currency to the pool
-    IERC20(_reserve).universalTransferFromSenderToThis(vars.actualAmountToLiquidate, true);
+    //transfers the principal currency to the aToken
+    IERC20(_reserve).universalTransferFrom(
+      msg.sender,
+      principalReserve.aTokenAddress,
+      vars.actualAmountToLiquidate,
+      true
+    );
 
     emit LiquidationCall(
       _collateral,

contracts/libraries/ReserveLogic.sol

@@ -15,6 +15,7 @@ import '../interfaces/ILendingRateOracle.sol';
 import '../interfaces/IReserveInterestRateStrategy.sol';
 import '../tokenization/AToken.sol';
 import './WadRayMath.sol';
+import '@nomiclabs/buidler/console.sol';
 
 /**
  * @title ReserveLogic library
@@ -56,7 +57,7 @@ library ReserveLogic {
     /**
      * @dev address of the aToken representing the asset
      **/
-    address aTokenAddress;
+    address payable aTokenAddress;
     address stableDebtTokenAddress;
     address variableDebtTokenAddress;
     /**
@@ -185,7 +186,7 @@ library ReserveLogic {
       _self.lastVariableBorrowCumulativeIndex = WadRayMath.ray();
     }
 
-    _self.aTokenAddress = _aTokenAddress;
+    _self.aTokenAddress = payable(_aTokenAddress);
     _self.stableDebtTokenAddress = _stableDebtAddress;
     _self.variableDebtTokenAddress = _variableDebtAddress;
     _self.decimals = _decimals;
@@ -348,12 +349,7 @@ library ReserveLogic {
     uint256 currentAvgStableRate = IStableDebtToken(_reserve.stableDebtTokenAddress)
       .getAverageStableRate();
 
-    uint256 balance = IERC20(_reserveAddress).universalBalanceOf(address(this));
-
-    //if the reserve is ETH, the msg.value has already been cumulated to the balance of the reserve
-    if (IERC20(_reserveAddress).isETH()) {
-      balance = balance.sub(msg.value);
-    }
+    uint256 balance = IERC20(_reserveAddress).universalBalanceOf(_reserve.aTokenAddress);
 
     (
       uint256 newLiquidityRate,

contracts/libraries/ValidationLogic.sol

@@ -53,7 +53,10 @@ library ValidationLogic {
 
     require(msg.sender == _reserve.aTokenAddress, '31');
 
-    uint256 currentAvailableLiquidity = IERC20(_reserveAddress).universalBalanceOf(address(this));
+    uint256 currentAvailableLiquidity = IERC20(_reserveAddress).universalBalanceOf(
+      address(_reserve.aTokenAddress)
+    );
+
     require(currentAvailableLiquidity >= _amount, '4');
   }
 
@@ -117,7 +120,9 @@ library ValidationLogic {
     );
 
     //check that the amount is available in the reserve
-    vars.availableLiquidity = IERC20(_reserveAddress).universalBalanceOf(address(this));
+    vars.availableLiquidity = IERC20(_reserveAddress).universalBalanceOf(
+      address(_reserve.aTokenAddress)
+    );
 
     require(vars.availableLiquidity >= _amount, '7');
 

contracts/misc/AaveProtocolTestHelpers.sol

@@ -39,7 +39,10 @@ contract AaveProtocolTestHelpers {
     TokenData[] memory aTokens = new TokenData[](reserves.length);
     for (uint256 i = 0; i < reserves.length; i++) {
       (address aTokenAddress, , ) = pool.getReserveTokensAddresses(reserves[i]);
-      aTokens[i] = TokenData({symbol: AToken(aTokenAddress).symbol(), tokenAddress: aTokenAddress});
+      aTokens[i] = TokenData({
+        symbol: AToken(payable(aTokenAddress)).symbol(),
+        tokenAddress: aTokenAddress
+      });
     }
     return aTokens;
   }

contracts/mocks/flashloan/MockFlashLoanReceiver.sol

@@ -25,6 +25,7 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
 
   function executeOperation(
     address _reserve,
+    address _destination,
     uint256 _amount,
     uint256 _fee,
     bytes memory _params
@@ -34,7 +35,7 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
 
     //check the contract has the specified balance
     require(
-      _amount <= IERC20(_reserve).universalBalanceOf(address(this)),
+      _amount <= getBalanceInternal(address(this), _reserve),
       'Invalid balance for the contract'
     );
 
@@ -49,8 +50,10 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
     if (!IERC20(_reserve).isETH()) {
       token.mint(_fee);
     }
+
     //returning amount + fee to the destination
-    transferFundsBackToPoolInternal(_reserve, _amount.add(_fee));
+    transferFundsBackInternal(_reserve, _destination, _amount.add(_fee));
+
     emit ExecutedWithSuccess(_reserve, _amount, _fee);
   }
 }

contracts/tokenization/AToken.sol

@@ -1,10 +1,12 @@
 // SPDX-License-Identifier: agpl-3.0
 pragma solidity ^0.6.8;
 
-import './ERC20.sol';
-import '../configuration/LendingPoolAddressesProvider.sol';
-import '../lendingpool/LendingPool.sol';
-import '../libraries/WadRayMath.sol';
+import {ERC20} from './ERC20.sol';
+import {LendingPoolAddressesProvider} from '../configuration/LendingPoolAddressesProvider.sol';
+import {LendingPool} from '../lendingpool/LendingPool.sol';
+import {WadRayMath} from '../libraries/WadRayMath.sol';
+import {UniversalERC20} from '../libraries/UniversalERC20.sol';
+import '@nomiclabs/buidler/console.sol';
 
 /**
  * @title Aave ERC20 AToken
@@ -14,6 +16,7 @@ import '../libraries/WadRayMath.sol';
  */
 contract AToken is ERC20 {
   using WadRayMath for uint256;
+  using UniversalERC20 for ERC20;
 
   uint256 public constant UINT_MAX_VALUE = uint256(-1);
 
@@ -636,4 +639,31 @@ contract AToken is ERC20 {
       return false;
     }
   }
+
+  /**
+   * @dev transfers the underlying asset to the target. Used by the lendingpool to transfer
+   * assets in borrow(), redeem() and flashLoan()
+   * @param _target the target of the transfer
+   * @param _amount the amount to transfer
+   * @return the amount transferred
+   **/
+
+  function transferUnderlyingTo(address _target, uint256 _amount)
+    external
+    onlyLendingPool
+    returns (uint256)
+  {
+    ERC20(underlyingAssetAddress).universalTransfer(_target, _amount);
+    return _amount;
+  }
+
+  /**
+   * @dev receive() function for aTokens who hold ETH as the underlying asset
+   **/
+  receive() external payable {
+    require(
+      ERC20(underlyingAssetAddress).isETH(),
+      'Transfers are only allowed if the underlying asset is ETH'
+    );
+  }
 }

deployed-contracts.json

@@ -438,4 +438,4 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   }
-}
+}

test/atoken-modifiers.spec.ts

@@ -25,4 +25,11 @@ makeSuite('AToken: Modifiers', (testEnv: TestEnv) => {
       aDai.transferOnLiquidation(deployer.address, users[0].address, '1')
     ).to.be.revertedWith(INVALID_POOL_CALLER_MSG_1);
   });
+
+  it('Tries to invoke transferUnderlyingTo not being the LendingPool', async () => {
+    const {deployer, users, aDai} = testEnv;
+    await expect(aDai.transferUnderlyingTo(deployer.address, '1')).to.be.revertedWith(
+      INVALID_POOL_CALLER_MSG_1
+    );
+  });
 });