feat: liquidation protocol fee and tests

aave · Sep 8, 2021 · 1a86b77 · 1a86b77
1 parent 1207d63
commit 1a86b77
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Showing 3 changed files with 637 additions and 24 deletions.
diff --git a/contracts/protocol/libraries/logic/LiquidationLogic.sol b/contracts/protocol/libraries/logic/LiquidationLogic.sol
@@ -6,9 +6,7 @@ import {IAToken} from '../../../interfaces/IAToken.sol';
 import {IStableDebtToken} from '../../../interfaces/IStableDebtToken.sol';
 import {IVariableDebtToken} from '../../../interfaces/IVariableDebtToken.sol';
 import {IPriceOracleGetter} from '../../../interfaces/IPriceOracleGetter.sol';
-import {
-  VersionedInitializable
-} from '../../libraries/aave-upgradeability/VersionedInitializable.sol';
+import {VersionedInitializable} from '../../libraries/aave-upgradeability/VersionedInitializable.sol';
 import {ReserveLogic} from '../../libraries/logic/ReserveLogic.sol';
 import {Helpers} from '../../libraries/helpers/Helpers.sol';
 import {WadRayMath} from '../../libraries/math/WadRayMath.sol';
@@ -64,13 +62,14 @@ library LiquidationLogic {
     uint256 healthFactor;
     uint256 liquidatorPreviousATokenBalance;
     IAToken collateralAtoken;
+    ITokenWithTreasury tokenWithTreasury;
     IPriceOracleGetter oracle;
     bool isCollateralEnabled;
     DataTypes.InterestRateMode borrowRateMode;
     uint256 errorCode;
     string errorMsg;
     DataTypes.ReserveCache debtReserveCache;
-
+    uint256 liquidationProtocolFeeAmount;
   }
 
   /**
@@ -91,8 +90,10 @@ library LiquidationLogic {
     DataTypes.UserConfigurationMap storage userConfig = usersConfig[params.user];
     vars.debtReserveCache = debtReserve.cache();
 
-
-    (vars.userStableDebt, vars.userVariableDebt) = Helpers.getUserCurrentDebt(params.user, debtReserve);
+    (vars.userStableDebt, vars.userVariableDebt) = Helpers.getUserCurrentDebt(
+      params.user,
+      debtReserve
+    );
     vars.oracle = IPriceOracleGetter(params.priceOracle);
 
     ValidationLogic.validateLiquidationCall(
@@ -108,7 +109,6 @@ library LiquidationLogic {
     );
 
     vars.collateralAtoken = IAToken(collateralReserve.aTokenAddress);
-
     vars.userCollateralBalance = vars.collateralAtoken.balanceOf(params.user);
 
     vars.maxLiquidatableDebt = (vars.userStableDebt + vars.userVariableDebt).percentMul(
@@ -121,7 +121,8 @@ library LiquidationLogic {
 
     (
       vars.maxCollateralToLiquidate,
-      vars.debtAmountNeeded
+      vars.debtAmountNeeded,
+      vars.liquidationProtocolFeeAmount
     ) = _calculateAvailableCollateralToLiquidate(
       collateralReserve,
       vars.debtReserveCache,
@@ -149,7 +150,12 @@ library LiquidationLogic {
         vars.debtReserveCache.nextVariableBorrowIndex
       );
       vars.debtReserveCache.refreshDebt(0, 0, 0, vars.actualDebtToLiquidate);
-      debtReserve.updateInterestRates(vars.debtReserveCache, params.debtAsset, vars.actualDebtToLiquidate, 0);
+      debtReserve.updateInterestRates(
+        vars.debtReserveCache,
+        params.debtAsset,
+        vars.actualDebtToLiquidate,
+        0
+      );
     } else {
       // If the user doesn't have variable debt, no need to try to burn variable debt tokens
       if (vars.userVariableDebt > 0) {
@@ -170,12 +176,21 @@ library LiquidationLogic {
         vars.userVariableDebt
       );
 
-      debtReserve.updateInterestRates(vars.debtReserveCache, params.debtAsset, vars.actualDebtToLiquidate, 0);
+      debtReserve.updateInterestRates(
+        vars.debtReserveCache,
+        params.debtAsset,
+        vars.actualDebtToLiquidate,
+        0
+      );
     }
 
     if (params.receiveAToken) {
       vars.liquidatorPreviousATokenBalance = IERC20(vars.collateralAtoken).balanceOf(msg.sender);
-      vars.collateralAtoken.transferOnLiquidation(params.user, msg.sender, vars.maxCollateralToLiquidate);
+      vars.collateralAtoken.transferOnLiquidation(
+        params.user,
+        msg.sender,
+        vars.maxCollateralToLiquidate
+      );
 
       if (vars.liquidatorPreviousATokenBalance == 0) {
         DataTypes.UserConfigurationMap storage liquidatorConfig = usersConfig[msg.sender];
@@ -201,6 +216,16 @@ library LiquidationLogic {
       );
     }
 
+    // Transfer fee to treasury if it is non-zero
+    if (vars.liquidationProtocolFeeAmount > 0) {
+      vars.tokenWithTreasury = ITokenWithTreasury(collateralReserve.aTokenAddress);
+      vars.collateralAtoken.transferOnLiquidation(
+        params.user,
+        vars.tokenWithTreasury.RESERVE_TREASURY_ADDRESS(),
+        vars.liquidationProtocolFeeAmount
+      );
+    }
+
     // If the collateral being liquidated is equal to the user balance,
     // we set the currency as not being used as collateral anymore
     if (vars.maxCollateralToLiquidate == vars.userCollateralBalance) {
@@ -236,6 +261,10 @@ library LiquidationLogic {
     uint256 collateralDecimals;
     uint256 collateralAssetUnit;
     uint256 debtAssetUnit;
+    uint256 collateralAmount;
+    uint256 debtAmountNeeded;
+    uint256 liquidationProtocolFeePercentage;
+    uint256 liquidationProtocolFeeAmount;
   }
 
   /**
@@ -261,10 +290,15 @@ library LiquidationLogic {
     uint256 debtToCover,
     uint256 userCollateralBalance,
     IPriceOracleGetter oracle
-  ) internal view returns (uint256, uint256) {
-    uint256 collateralAmount = 0;
-    uint256 debtAmountNeeded = 0;
-
+  )
+    internal
+    view
+    returns (
+      uint256,
+      uint256,
+      uint256
+    )
+  {
     AvailableCollateralToLiquidateLocalVars memory vars;
 
     vars.collateralPrice = oracle.getAssetPrice(collateralAsset);
@@ -273,13 +307,16 @@ library LiquidationLogic {
     (, , vars.liquidationBonus, vars.collateralDecimals, ) = collateralReserve
       .configuration
       .getParams();
-
     vars.debtAssetDecimals = debtReserveCache.reserveConfiguration.getDecimalsMemory();
     unchecked {
       vars.collateralAssetUnit = 10**vars.collateralDecimals;
       vars.debtAssetUnit = 10**vars.debtAssetDecimals;
     }
 
+    vars.liquidationProtocolFeePercentage = collateralReserve
+      .configuration
+      .getLiquidationProtocolFee();
+
     // This is the maximum possible amount of the selected collateral that can be liquidated, given the
     // max amount of liquidatable debt
     vars.maxAmountCollateralToLiquidate =
@@ -291,14 +328,28 @@ library LiquidationLogic {
       (vars.collateralPrice * vars.debtAssetUnit);
 
     if (vars.maxAmountCollateralToLiquidate > userCollateralBalance) {
-      collateralAmount = userCollateralBalance;
-      debtAmountNeeded = ((vars.collateralPrice * collateralAmount * vars.debtAssetUnit) /
-        (vars.debtAssetPrice * vars.collateralAssetUnit))
-        .percentDiv(vars.liquidationBonus);
+      vars.collateralAmount = userCollateralBalance;
+      vars.debtAmountNeeded = ((vars.collateralPrice * vars.collateralAmount * vars.debtAssetUnit) /
+        (vars.debtAssetPrice * vars.collateralAssetUnit)).percentDiv(vars.liquidationBonus);
     } else {
-      collateralAmount = vars.maxAmountCollateralToLiquidate;
-      debtAmountNeeded = debtToCover;
+      vars.collateralAmount = vars.maxAmountCollateralToLiquidate;
+      vars.debtAmountNeeded = debtToCover;
     }
-    return (collateralAmount, debtAmountNeeded);
+
+    if (vars.liquidationProtocolFeePercentage > 0) {
+      vars.liquidationProtocolFeeAmount = vars.collateralAmount.percentMul(
+        vars.liquidationProtocolFeePercentage
+      );
+      return (
+        vars.collateralAmount - vars.liquidationProtocolFeeAmount,
+        vars.debtAmountNeeded,
+        vars.liquidationProtocolFeeAmount
+      );
+    }
+    return (vars.collateralAmount, vars.debtAmountNeeded, 0);
   }
 }
+
+interface ITokenWithTreasury {
+  function RESERVE_TREASURY_ADDRESS() external view returns (address);
+}
diff --git a/test-suites/liquidation-underlying.spec.ts b/test-suites/liquidation-underlying.spec.ts
@@ -377,7 +377,7 @@ makeSuite('Pool Liquidation: Liquidator receiving the underlying asset', (testEn
       .connect(liquidator.signer)
       .mint(await convertToCurrencyDecimals(usdc.address, '1000'));
 
-    //approve protocol to access depositor wallet
+    //approve protocol to access liquidator wallet
     await usdc.connect(liquidator.signer).approve(pool.address, MAX_UINT_AMOUNT);
 
     const userReserveDataBefore = await helpersContract.getUserReserveData(