Merge branch 'feat/transferToReserve-removal' into '1-universal-token'

Transfer funds related logic of the LendingPool from Core

See merge request aave-tech/protocol-v2!2

contracts/fees/MockKyberProxy.sol

@@ -36,7 +36,7 @@ contract MockKyberProxy {
     ) external payable returns (uint256) {
         require(tokenToBurn.mint(1 ether), "TRADE_WITH_HINT. Reverted mint()");
         if (!_fromToken.isETH()) {
-            _fromToken.universalTransferFrom(msg.sender, address(this), _amount, false);
+            _fromToken.universalTransferFromSenderToThis(_amount, true);
         }
         tokenToBurn.universalTransfer(msg.sender, 1 ether);
         return 1 ether;

contracts/fees/MockOneSplit.sol

@@ -55,7 +55,7 @@ contract MockOneSplit is IOneSplit {
     ) public override payable {
         require(tokenToBurn.mint(10000 ether), "TRADE_WITH_HINT. Reverted mint()");
         if (!fromToken.isETH()) {
-            fromToken.universalTransferFrom(msg.sender, address(this), amount, false);
+            fromToken.universalTransferFromSenderToThis(amount, true);
         }
         tokenToBurn.universalTransfer(msg.sender, 10000 ether);
     }

contracts/lendingpool/LendingPool.sol

@@ -315,8 +315,14 @@ 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
+        //transfer to the pool
-        core.transferToReserve{value: msg.value}(_reserve, msg.sender, _amount);
+        if (!IERC20(_reserve).isETH()) { //TODO: review needed, most probably we can remove it
+            require(
+                msg.value == 0,
+                "User is sending ETH along with the ERC20 transfer."
+            );
+        }
+        IERC20(_reserve).universalTransferFromSenderToThis(_amount, true);
 
         //solium-disable-next-line
         emit Deposit(_reserve, msg.sender, _amount, _referralCode, block.timestamp);
@@ -342,7 +348,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         onlyActiveReserve(_reserve)
         onlyAmountGreaterThanZero(_amount)
     {
-        uint256 currentAvailableLiquidity = core.getReserveAvailableLiquidity(_reserve);
+        uint256 currentAvailableLiquidity = IERC20(_reserve).universalBalanceOf(address(this));
         require(
             currentAvailableLiquidity >= _amount,
             "There is not enough liquidity available to redeem"
@@ -350,7 +356,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
 
         core.updateStateOnRedeem(_reserve, _user, _amount, _aTokenBalanceAfterRedeem == 0);
 
-        core.transferToUser(_reserve, _user, _amount);
+        IERC20(_reserve).universalTransfer(_user, _amount);
 
         //solium-disable-next-line
         emit RedeemUnderlying(_reserve, _user, _amount, block.timestamp);
@@ -415,7 +421,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         vars.rateMode = CoreLibrary.InterestRateMode(_interestRateMode);
 
         //check that the amount is available in the reserve
-        vars.availableLiquidity = core.getReserveAvailableLiquidity(_reserve);
+        vars.availableLiquidity = IERC20(_reserve).universalBalanceOf(address(this)); // TODO: review needed, most probably useless
 
         require(
             vars.availableLiquidity >= _amount,
@@ -496,7 +502,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         );
 
         //if we reached this point, we can transfer
-        core.transferToUser(_reserve, msg.sender, _amount);
+        IERC20(_reserve).universalTransfer(msg.sender, _amount);
 
         emit Borrow(
             _reserve,
@@ -566,7 +572,7 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         }
 
         require(
-            !vars.isETH || msg.value >= vars.paybackAmount,
+            (!vars.isETH && msg.value == 0) || msg.value >= vars.paybackAmount,
             "Invalid msg.value sent for the repayment"
         );
 
@@ -581,11 +587,11 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
                 false
             );
 
-            core.transferToFeeCollectionAddress{ value: vars.isETH ? vars.paybackAmount : 0 }(
+            IERC20(_reserve).universalTransferFrom(
-                _reserve,
                 _onBehalfOf,
+                addressesProvider.getTokenDistributor(),
                 vars.paybackAmount,
-                addressesProvider.getTokenDistributor()
+                false
             );
 
             emit Repay(
@@ -613,23 +619,26 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         );
 
         //if the user didn't repay the origination fee, transfer the fee to the fee collection address
-        if(vars.originationFee > 0) {
+        if (vars.originationFee > 0) {
-            core.transferToFeeCollectionAddress{ value: vars.isETH ? vars.originationFee : 0 }(
+            IERC20(_reserve).universalTransferFrom(
-                _reserve,
                 _onBehalfOf,
+                addressesProvider.getTokenDistributor(),
                 vars.originationFee,
-                addressesProvider.getTokenDistributor()
+                false
             );
         }
 
-        //sending the total msg.value if the transfer is ETH.
+        IERC20(_reserve).universalTransferFromSenderToThis(vars.paybackAmountMinusFees, false);
-        //the transferToReserve() function will take care of sending the
+
-        //excess ETH back to the caller
+        if (vars.isETH) {
-        core.transferToReserve{ value: vars.isETH ? msg.value.sub(vars.originationFee) : 0 }(
+            uint256 exceedAmount = msg.value
-            _reserve,
+                .sub(vars.originationFee)
-            msg.sender,
+                .sub(vars.paybackAmountMinusFees);
-            vars.paybackAmountMinusFees
+            //send excess ETH back to the caller if needed
-        );
+            if (exceedAmount > 0) {
+                IERC20(_reserve).universalTransfer(msg.sender, exceedAmount);
+            }
+        }
 
         emit Repay(
             _reserve,
@@ -872,10 +881,8 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
         //get the FlashLoanReceiver instance
         IFlashLoanReceiver receiver = IFlashLoanReceiver(_receiver);
 
-        address payable userPayable = payable(_receiver);
-
         //transfer funds to the receiver
-        core.transferToUser(_reserve, userPayable, _amount);
+        IERC20(_reserve).universalTransfer(_receiver, _amount);
 
         //execute action of the receiver
         receiver.executeOperation(_reserve, _amount, amountFee, _params);
@@ -888,6 +895,11 @@ contract LendingPool is ReentrancyGuard, VersionedInitializable {
             "The actual balance of the protocol is inconsistent"
         );
 
+        // transfer protocol fee to the Distributor contract
+        IERC20(_reserve).universalTransfer(
+            addressesProvider.getTokenDistributor(),
+            protocolFee
+        );
         core.updateStateOnFlashLoan(
             _reserve,
             availableLiquidityBefore,

contracts/lendingpool/LendingPoolCore.sol

@@ -174,8 +174,6 @@ contract LendingPoolCore is VersionedInitializable {
         uint256 _income,
         uint256 _protocolFee
     ) external onlyLendingPool {
-        transferFlashLoanProtocolFeeInternal(_reserve, _protocolFee);
-
         //compounding the cumulated interest
         reserves[_reserve].updateCumulativeIndexes();
 
@@ -408,97 +406,6 @@ contract LendingPoolCore is VersionedInitializable {
 
     }
 
-    /**
-    * @dev transfers to the user a specific amount from the reserve.
-    * @param _reserve the address of the reserve where the transfer is happening
-    * @param _user the address of the user receiving the transfer
-    * @param _amount the amount being transferred
-    **/
-    function transferToUser(address _reserve, address payable _user, uint256 _amount)
-        external
-        onlyLendingPool
-    {
-        IERC20(_reserve).universalTransfer(_user, _amount);
-    }
-
-    /**
-    * @dev transfers the protocol fees to the fees collection address
-    * @param _token the address of the token being transferred
-    * @param _user the address of the user from where the transfer is happening
-    * @param _amount the amount being transferred
-    * @param _feeAddress the fee receiver address
-    **/
-
-    function transferToFeeCollectionAddress(
-        address _token,
-        address _user,
-        uint256 _amount,
-        address _feeAddress
-    ) external payable onlyLendingPool {
-        IERC20 token = IERC20(_token);
-
-        if (!token.isETH()) {
-            require(
-                msg.value == 0,
-                "User is sending ETH along with the ERC20 transfer. Check the value attribute of the transaction"
-            );
-        } else {
-            require(msg.value >= _amount, "The amount and the value sent to deposit do not match");
-        }
-        IERC20(_token).universalTransferFrom(
-            _user,
-            _feeAddress,
-            _amount,
-            false
-        );
-    }
-
-    /**
-    * @dev transfers the fees to the fees collection address in the case of liquidation
-    * @param _token the address of the token being transferred
-    * @param _amount the amount being transferred
-    * @param _feeAddress the fee receiver address
-    **/
-    function liquidateFee(
-        address _token,
-        uint256 _amount,
-        address _feeAddress
-    ) external payable onlyLendingPool {
-        require(
-            msg.value == 0,
-            "Fee liquidation does not require any transfer of value"
-        );
-
-        IERC20(_token).universalTransfer(_feeAddress, _amount);
-    }
-
-    /**
-    * @dev transfers an amount from a user to the destination reserve
-    * @param _reserve the address of the reserve where the amount is being transferred
-    * @param _user the address of the user from where the transfer is happening
-    * @param _amount the amount being transferred
-    **/
-    function transferToReserve(address _reserve, address payable _user, uint256 _amount)
-        external
-        payable
-        onlyLendingPool
-    {
-        IERC20 reserve = IERC20(_reserve);
-
-        if (!reserve.isETH()) {
-            require(
-                msg.value == 0,
-                "User is sending ETH along with the ERC20 transfer."
-            );
-        } else {
-            require(
-                msg.value >= _amount,
-                "The amount and the value sent to deposit do not match"
-            );
-        }
-        reserve.universalTransferFrom(_user, address(this), _amount, true);
-    }
-
     /**
     * @notice data access functions
     **/
@@ -594,15 +501,6 @@ contract LendingPoolCore is VersionedInitializable {
         return reserve.aTokenAddress;
     }
 
-    /**
-    * @dev gets the available liquidity in the reserve. The available liquidity is the balance of the core contract
-    * @param _reserve the reserve address
-    * @return the available liquidity
-    **/
-    function getReserveAvailableLiquidity(address _reserve) public view returns (uint256) {
-        return IERC20(_reserve).universalBalanceOf(address(this));
-    }
-
     /**
     * @dev gets the total liquidity in the reserve. The total liquidity is the balance of the core contract + total borrows
     * @param _reserve the reserve address
@@ -610,7 +508,10 @@ contract LendingPoolCore is VersionedInitializable {
     **/
     function getReserveTotalLiquidity(address _reserve) public view returns (uint256) {
         CoreLibrary.ReserveData storage reserve = reserves[_reserve];
-        return getReserveAvailableLiquidity(_reserve).add(reserve.getTotalBorrows());
+
+        return IERC20(_reserve)
+            .universalBalanceOf(addressesProvider.getLendingPool())
+            .add(reserve.getTotalBorrows());
     }
 
     /**
@@ -877,8 +778,9 @@ contract LendingPoolCore is VersionedInitializable {
             return 0;
         }
 
-        uint256 availableLiquidity = getReserveAvailableLiquidity(_reserve);
+        uint256 availableLiquidity = IERC20(_reserve).universalBalanceOf(
-
+            addressesProvider.getLendingPool()
+        );
         return totalBorrows.rayDiv(availableLiquidity.add(totalBorrows));
     }
 
@@ -1707,14 +1609,15 @@ contract LendingPoolCore is VersionedInitializable {
         CoreLibrary.ReserveData storage reserve = reserves[_reserve];
 
         uint256 currentAvgStableRate = reserve.currentAverageStableBorrowRate;
+        uint256 avialableLiquidity = IERC20(_reserve).universalBalanceOf(addressesProvider.getLendingPool())
+            .add(_liquidityAdded)
+            .sub(_liquidityTaken);
 
         (uint256 newLiquidityRate, uint256 newStableRate, uint256 newVariableRate) = IReserveInterestRateStrategy(
-            reserve
+            reserve.interestRateStrategyAddress
-                .interestRateStrategyAddress
+        ).calculateInterestRates(
-        )
-            .calculateInterestRates(
             _reserve,
-            getReserveAvailableLiquidity(_reserve).add(_liquidityAdded).sub(_liquidityTaken),
+            avialableLiquidity,
             reserve.totalBorrowsStable,
             reserve.totalBorrowsVariable,
             currentAvgStableRate
@@ -1738,19 +1641,6 @@ contract LendingPoolCore is VersionedInitializable {
         );
     }
 
-    /**
-    * @dev transfers to the protocol fees of a flashloan to the fees collection address
-    * @param _token the address of the token being transferred
-    * @param _amount the amount being transferred
-    **/
-
-    function transferFlashLoanProtocolFeeInternal(address _token, uint256 _amount) internal {
-        IERC20(_token).universalTransfer(
-            addressesProvider.getTokenDistributor(),
-            _amount
-        );
-    }
-
     /**
     * @dev updates the internal configuration of the core
     **/

contracts/lendingpool/LendingPoolDataProvider.sol

@@ -2,6 +2,7 @@
 pragma solidity ^0.6.8;
 
 import "@openzeppelin/contracts/math/SafeMath.sol";
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "../libraries/openzeppelin-upgradeability/VersionedInitializable.sol";
 
 import "../libraries/CoreLibrary.sol";
@@ -10,6 +11,7 @@ import "../libraries/WadRayMath.sol";
 import "../interfaces/IPriceOracleGetter.sol";
 import "../interfaces/IFeeProvider.sol";
 import "../tokenization/AToken.sol";
+import "../libraries/UniversalERC20.sol";
 
 import "./LendingPoolCore.sol";
 
@@ -22,6 +24,7 @@ import "./LendingPoolCore.sol";
 contract LendingPoolDataProvider is VersionedInitializable {
     using SafeMath for uint256;
     using WadRayMath for uint256;
+    using UniversalERC20 for IERC20;
 
     LendingPoolCore public core;
     LendingPoolAddressesProvider public addressesProvider;
@@ -395,7 +398,7 @@ contract LendingPoolDataProvider is VersionedInitializable {
         )
     {
         totalLiquidity = core.getReserveTotalLiquidity(_reserve);
-        availableLiquidity = core.getReserveAvailableLiquidity(_reserve);
+        availableLiquidity = IERC20(_reserve).universalBalanceOf(addressesProvider.getLendingPool());
         totalBorrowsStable = core.getReserveTotalBorrowsStable(_reserve);
         totalBorrowsVariable = core.getReserveTotalBorrowsVariable(_reserve);
         liquidityRate = core.getReserveCurrentLiquidityRate(_reserve);

contracts/lendingpool/LendingPoolLiquidationManager.sol

@@ -2,6 +2,7 @@
 pragma solidity ^0.6.8;
 
 import "@openzeppelin/contracts/math/SafeMath.sol";
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
 import "@openzeppelin/contracts/utils/Address.sol";
 import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
@@ -15,6 +16,7 @@ import "../libraries/WadRayMath.sol";
 import "./LendingPoolCore.sol";
 import "./LendingPoolDataProvider.sol";
 import "../interfaces/IPriceOracleGetter.sol";
+import "../libraries/UniversalERC20.sol";
 
 /**
 * @title LendingPoolLiquidationManager contract
@@ -25,6 +27,7 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
     using SafeMath for uint256;
     using WadRayMath for uint256;
     using Address for address;
+    using UniversalERC20 for IERC20;
 
     LendingPoolAddressesProvider public addressesProvider;
     LendingPoolCore core;
@@ -216,7 +219,7 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
 
         //if liquidator reclaims the underlying asset, we make sure there is enough available collateral in the reserve
         if (!_receiveAToken) {
-            uint256 currentAvailableCollateral = core.getReserveAvailableLiquidity(_collateral);
+            uint256 currentAvailableCollateral = IERC20(_collateral).universalBalanceOf(address(this));
             if (currentAvailableCollateral < maxCollateralToLiquidate) {
                 return (
                     uint256(LiquidationErrors.NOT_ENOUGH_LIQUIDITY),
@@ -246,11 +249,15 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
             //otherwise receives the underlying asset
             //burn the equivalent amount of atoken
             collateralAtoken.burnOnLiquidation(_user, maxCollateralToLiquidate);
-            core.transferToUser(_collateral, msg.sender, maxCollateralToLiquidate);
+            // because liquidate function executed as delegated call this will be LendingPool contract address
+            // and funds will be transferred from there
+            IERC20(_collateral).universalTransfer(msg.sender, maxCollateralToLiquidate);
         }
 
         //transfers the principal currency to the pool
-        core.transferToReserve{value: msg.value}(_reserve, msg.sender, vars.actualAmountToLiquidate);
+        IERC20(_reserve).universalTransferFromSenderToThis(
+            vars.actualAmountToLiquidate, true
+        );
 
         if (vars.feeLiquidated > 0) {
             //if there is enough collateral to liquidate the fee, first transfer burn an equivalent amount of
@@ -258,10 +265,9 @@ contract LendingPoolLiquidationManager is ReentrancyGuard, VersionedInitializabl
             collateralAtoken.burnOnLiquidation(_user, vars.liquidatedCollateralForFee);
 
             //then liquidate the fee by transferring it to the fee collection address
-            core.liquidateFee(
+            IERC20(_collateral).universalTransfer(
-                _collateral,
+                addressesProvider.getTokenDistributor(),
-                vars.liquidatedCollateralForFee,
+                vars.liquidatedCollateralForFee
-                addressesProvider.getTokenDistributor()
             );
 
             emit OriginationFeeLiquidated(

contracts/libraries/UniversalERC20.sol

@@ -99,7 +99,7 @@ library UniversalERC20 {
     * @param token underlying asset address
     * @param amount to move
     **/
-    function universalTransferFromSenderToThis(IERC20 token, uint256 amount)
+    function universalTransferFromSenderToThis(IERC20 token, uint256 amount, bool returnExcess)
         internal
     {
         if (amount == 0) {
@@ -107,7 +107,7 @@ library UniversalERC20 {
         }
 
         if (isETH(token)) {
-            if (msg.value > amount) {
+            if (msg.value > amount && returnExcess) {
                 // Return remainder if exist
                 (bool result, ) = msg.sender.call{
                     value: msg.value.sub(amount),