initial implementation of the credit delegation + basic tests

contracts/interfaces/ILendingPool.sol

@@ -28,6 +28,12 @@ interface ILendingPool {
    **/
   event Withdraw(address indexed reserve, address indexed user, uint256 amount);
 
+  event BorrowAllowanceDelegated(
+    address indexed fromUser,
+    address indexed toUser,
+    address indexed asset,
+    uint256 amount
+  );
   /**
    * @dev emitted on borrow
    * @param reserve the address of the reserve
@@ -39,7 +45,8 @@ interface ILendingPool {
    **/
   event Borrow(
     address indexed reserve,
-    address indexed user,
+    address user,
+    address indexed onBehalfOf,
     uint256 amount,
     uint256 borrowRateMode,
     uint256 borrowRate,
@@ -149,6 +156,18 @@ interface ILendingPool {
    **/
   function withdraw(address reserve, uint256 amount) external;
 
+  function delegateBorrowAllowance(
+    address user,
+    address asset,
+    uint256 amount
+  ) external;
+
+  function getBorrowAllowance(
+    address fromUser,
+    address toUser,
+    address asset
+  ) external view returns (uint256);
+
   /**
    * @dev Allows users to borrow a specific amount of the reserve currency, provided that the borrower
    * already deposited enough collateral.
@@ -160,7 +179,8 @@ interface ILendingPool {
     address reserve,
     uint256 amount,
     uint256 interestRateMode,
-    uint16 referralCode
+    uint16 referralCode,
+    address onBehalfOf
   ) external;
 
   /**

contracts/lendingpool/LendingPool.sol

@@ -48,7 +48,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
 
   mapping(address => ReserveLogic.ReserveData) internal _reserves;
   mapping(address => UserConfiguration.Map) internal _usersConfig;
-
+  mapping(address => mapping(address => mapping(address => uint256))) internal _borrowAllowance;
   address[] internal _reservesList;
 
   /**
@@ -157,6 +157,23 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     emit Withdraw(asset, msg.sender, amount);
   }
 
+  function getBorrowAllowance(
+    address fromUser,
+    address toUser,
+    address asset
+  ) external override view returns (uint256) {
+    return _borrowAllowance[fromUser][asset][toUser];
+  }
+
+  function delegateBorrowAllowance(
+    address user,
+    address asset,
+    uint256 amount
+  ) external override {
+    _borrowAllowance[msg.sender][asset][user] = amount;
+    emit BorrowAllowanceDelegated(msg.sender, user, asset, amount);
+  }
+
   /**
    * @dev Allows users to borrow a specific amount of the reserve currency, provided that the borrower
    * already deposited enough collateral.
@@ -169,12 +186,19 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     address asset,
     uint256 amount,
     uint256 interestRateMode,
-    uint16 referralCode
+    uint16 referralCode,
+    address onBehalfOf
   ) external override {
+    if (onBehalfOf != msg.sender) {
+      _borrowAllowance[onBehalfOf][asset][msg.sender] = _borrowAllowance[onBehalfOf][asset][msg
+        .sender]
+        .sub(amount, Errors.BORROW_ALLOWANCE_ARE_NOT_ENOUGH);
+    }
     _executeBorrow(
       ExecuteBorrowParams(
         asset,
         msg.sender,
+        onBehalfOf,
         amount,
         interestRateMode,
         _reserves[asset].aTokenAddress,
@@ -450,21 +474,20 @@ contract LendingPool is VersionedInitializable, ILendingPool {
     vars.amountPlusPremium = amount.add(vars.premium);
 
     if (debtMode == ReserveLogic.InterestRateMode.NONE) {
-      
       IERC20(asset).transferFrom(receiverAddress, vars.aTokenAddress, vars.amountPlusPremium);
-      
+
       reserve.updateCumulativeIndexesAndTimestamp();
       reserve.cumulateToLiquidityIndex(IERC20(vars.aTokenAddress).totalSupply(), vars.premium);
       reserve.updateInterestRates(asset, vars.aTokenAddress, vars.premium, 0);
-      
-      emit FlashLoan(receiverAddress, asset, amount, vars.premium, referralCode);
 
+      emit FlashLoan(receiverAddress, asset, amount, vars.premium, referralCode);
     } else {
       // If the transfer didn't succeed, the receiver either didn't return the funds, or didn't approve the transfer.
       _executeBorrow(
         ExecuteBorrowParams(
           asset,
           msg.sender,
+          msg.sender,
           vars.amountPlusPremium.sub(vars.availableBalance),
           mode,
           vars.aTokenAddress,
@@ -694,6 +717,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
   struct ExecuteBorrowParams {
     address asset;
     address user;
+    address onBehalfOf;
     uint256 amount;
     uint256 interestRateMode;
     address aTokenAddress;
@@ -707,7 +731,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
    **/
   function _executeBorrow(ExecuteBorrowParams memory vars) internal {
     ReserveLogic.ReserveData storage reserve = _reserves[vars.asset];
-    UserConfiguration.Map storage userConfig = _usersConfig[msg.sender];
+    UserConfiguration.Map storage userConfig = _usersConfig[vars.onBehalfOf];
 
     address oracle = _addressesProvider.getPriceOracle();
 
@@ -717,6 +741,7 @@ contract LendingPool is VersionedInitializable, ILendingPool {
 
     ValidationLogic.validateBorrow(
       reserve,
+      vars.onBehalfOf,
       vars.asset,
       vars.amount,
       amountInETH,
@@ -728,13 +753,11 @@ contract LendingPool is VersionedInitializable, ILendingPool {
       oracle
     );
 
-
     uint256 reserveIndex = reserve.index;
     if (!userConfig.isBorrowing(reserveIndex)) {
       userConfig.setBorrowing(reserveIndex, true);
     }
 
-
     reserve.updateCumulativeIndexesAndTimestamp();
 
     //caching the current stable borrow rate
@@ -746,24 +769,29 @@ contract LendingPool is VersionedInitializable, ILendingPool {
       currentStableRate = reserve.currentStableBorrowRate;
 
       IStableDebtToken(reserve.stableDebtTokenAddress).mint(
-        vars.user,
+        vars.onBehalfOf,
         vars.amount,
         currentStableRate
       );
     } else {
-      IVariableDebtToken(reserve.variableDebtTokenAddress).mint(vars.user, vars.amount);
+      IVariableDebtToken(reserve.variableDebtTokenAddress).mint(vars.onBehalfOf, vars.amount);
     }
 
-    reserve.updateInterestRates(vars.asset, vars.aTokenAddress, 0, vars.releaseUnderlying ?  vars.amount : 0);
+    reserve.updateInterestRates(
-  
+      vars.asset,
-    if(vars.releaseUnderlying){
+      vars.aTokenAddress,
-        IAToken(vars.aTokenAddress).transferUnderlyingTo(msg.sender, vars.amount);
+      0,
+      vars.releaseUnderlying ? vars.amount : 0
+    );
+
+    if (vars.releaseUnderlying) {
+      IAToken(vars.aTokenAddress).transferUnderlyingTo(vars.user, vars.amount);
     }
-  
+
-  
     emit Borrow(
       vars.asset,
-      msg.sender,
+      vars.user,
+      vars.onBehalfOf,
       vars.amount,
       vars.interestRateMode,
       ReserveLogic.InterestRateMode(vars.interestRateMode) == ReserveLogic.InterestRateMode.STABLE

contracts/libraries/helpers/Errors.sol

@@ -38,6 +38,7 @@ library Errors {
   string public constant INCONSISTENT_PROTOCOL_ACTUAL_BALANCE = '26'; // 'The actual balance of the protocol is inconsistent'
   string public constant CALLER_NOT_LENDING_POOL_CONFIGURATOR = '27'; // 'The actual balance of the protocol is inconsistent'
   string public constant INVALID_FLASHLOAN_MODE = '43'; //Invalid flashloan mode selected
+  string public constant BORROW_ALLOWANCE_ARE_NOT_ENOUGH = '52'; // User borrows on behalf, but allowance are too small
 
   // require error messages - aToken
   string public constant CALLER_MUST_BE_LENDING_POOL = '28'; // 'The caller of this function must be a lending pool'
@@ -70,7 +71,7 @@ library Errors {
   string public constant NO_ERRORS = '42'; // 'No errors'
 
   //require error messages - Math libraries
-  string public constant MULTIPLICATION_OVERFLOW = '44'; 
+  string public constant MULTIPLICATION_OVERFLOW = '44';
-  string public constant ADDITION_OVERFLOW = '45'; 
+  string public constant ADDITION_OVERFLOW = '45';
   string public constant DIVISION_BY_ZERO = '46';
 }

contracts/libraries/logic/ValidationLogic.sol

@@ -100,6 +100,7 @@ library ValidationLogic {
   /**
    * @dev validates a borrow.
    * @param reserve the reserve state from which the user is borrowing
+   * @param userAddress the address of the user
    * @param reserveAddress the address of the reserve
    * @param amount the amount to be borrowed
    * @param amountInETH the amount to be borrowed, in ETH
@@ -113,6 +114,7 @@ library ValidationLogic {
 
   function validateBorrow(
     ReserveLogic.ReserveData storage reserve,
+    address userAddress,
     address reserveAddress,
     uint256 amount,
     uint256 amountInETH,
@@ -151,7 +153,7 @@ library ValidationLogic {
       vars.currentLiquidationThreshold,
       vars.healthFactor
     ) = GenericLogic.calculateUserAccountData(
-      msg.sender,
+      userAddress,
       reservesData,
       userConfig,
       reserves,
@@ -192,7 +194,7 @@ library ValidationLogic {
       require(
         !userConfig.isUsingAsCollateral(reserve.index) ||
           reserve.configuration.getLtv() == 0 ||
-          amount > IERC20(reserve.aTokenAddress).balanceOf(msg.sender),
+          amount > IERC20(reserve.aTokenAddress).balanceOf(userAddress),
         Errors.CALLATERAL_SAME_AS_BORROWING_CURRENCY
       );
 
@@ -321,10 +323,10 @@ library ValidationLogic {
   }
 
   /**
-  * @dev validates a flashloan action
+   * @dev validates a flashloan action
-  * @param mode the flashloan mode (0 = classic flashloan, 1 = open a stable rate loan, 2 = open a variable rate loan)
+   * @param mode the flashloan mode (0 = classic flashloan, 1 = open a stable rate loan, 2 = open a variable rate loan)
-  * @param premium the premium paid on the flashloan
+   * @param premium the premium paid on the flashloan
-  **/
+   **/
   function validateFlashloan(uint256 mode, uint256 premium) internal pure {
     require(premium > 0, Errors.REQUESTED_AMOUNT_TOO_SMALL);
     require(mode <= uint256(ReserveLogic.InterestRateMode.VARIABLE), Errors.INVALID_FLASHLOAN_MODE);

deployed-contracts.json

@@ -111,7 +111,7 @@
   },
   "DefaultReserveInterestRateStrategy": {
     "buidlerevm": {
-      "address": "0x626FdE749F9d499d3777320CAf29484B624ab84a",
+      "address": "0x2530ce07D254eA185E8e0bCC37a39e2FbA3bE548",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
@@ -422,7 +422,7 @@
   },
   "StableDebtToken": {
     "buidlerevm": {
-      "address": "0xB660Fdd109a95718cB9d20E3A89EE6cE342aDcB6",
+      "address": "0x0Cf45557d25a4e4c0F1aC65EF6c48ae67c61a0E6",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
@@ -432,7 +432,7 @@
   },
   "VariableDebtToken": {
     "buidlerevm": {
-      "address": "0x830bceA96E56DBC1F8578f75fBaC0AF16B32A07d",
+      "address": "0x7fAeC7791277Ff512c41CA903c177B2Ed952dDAc",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "localhost": {
@@ -446,7 +446,7 @@
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     },
     "buidlerevm": {
-      "address": "0xA0AB1cB92A4AF81f84dCd258155B5c25D247b54E",
+      "address": "0x33958cC3535Fc328369EAC2B2Bebd120D67C7fa1",
       "deployer": "0xc783df8a850f42e7F7e57013759C285caa701eB6"
     }
   },

test/atoken-transfer.spec.ts

@@ -103,7 +103,13 @@ makeSuite('AToken: Transfer', (testEnv: TestEnv) => {
     await expect(
       pool
         .connect(users[1].signer)
-        .borrow(weth.address, ethers.utils.parseEther('0.1'), RateMode.Stable, AAVE_REFERRAL),
+        .borrow(
+          weth.address,
+          ethers.utils.parseEther('0.1'),
+          RateMode.Stable,
+          AAVE_REFERRAL,
+          users[1].address
+        ),
       COLLATERAL_BALANCE_IS_0
     ).to.be.revertedWith(COLLATERAL_BALANCE_IS_0);
   });
@@ -116,7 +122,13 @@ makeSuite('AToken: Transfer', (testEnv: TestEnv) => {
 
     await pool
       .connect(users[1].signer)
-      .borrow(weth.address, ethers.utils.parseEther('0.1'), RateMode.Stable, AAVE_REFERRAL);
+      .borrow(
+        weth.address,
+        ethers.utils.parseEther('0.1'),
+        RateMode.Stable,
+        AAVE_REFERRAL,
+        users[1].address
+      );
 
     await expect(
       aDai.connect(users[1].signer).transfer(users[0].address, aDAItoTransfer),

test/helpers/actions.ts

@@ -278,11 +278,34 @@ export const withdraw = async (
   }
 };
 
+export const delegateBorrowAllowance = async (
+  reserveSymbol: string,
+  amount: string,
+  user: SignerWithAddress,
+  receiver: tEthereumAddress,
+  testEnv: TestEnv
+) => {
+  const {pool} = testEnv;
+
+  const reserve = await getReserveAddressFromSymbol(reserveSymbol);
+  const amountToDelegate = await convertToCurrencyDecimals(reserve, amount);
+
+  await pool
+    .connect(user.signer)
+    .delegateBorrowAllowance(receiver, reserve, amountToDelegate.toString());
+  expect(
+    (
+      await pool['getBorrowAllowance(address,address,address)'](user.address, receiver, reserve)
+    ).toString()
+  ).to.be.equal(amountToDelegate.toString(), 'borrowAllowance are set incorrectly');
+};
+
 export const borrow = async (
   reserveSymbol: string,
   amount: string,
   interestRateMode: string,
   user: SignerWithAddress,
+  onBehalfOf: tEthereumAddress,
   timeTravel: string,
   expectedResult: string,
   testEnv: TestEnv,
@@ -294,15 +317,18 @@ export const borrow = async (
 
   const {reserveData: reserveDataBefore, userData: userDataBefore} = await getContractsData(
     reserve,
-    user.address,
+    onBehalfOf,
-    testEnv
+    testEnv,
+    user.address
   );
 
   const amountToBorrow = await convertToCurrencyDecimals(reserve, amount);
 
   if (expectedResult === 'success') {
     const txResult = await waitForTx(
-      await pool.connect(user.signer).borrow(reserve, amountToBorrow, interestRateMode, '0')
+      await pool
+        .connect(user.signer)
+        .borrow(reserve, amountToBorrow, interestRateMode, '0', onBehalfOf)
     );
 
     const {txCost, txTimestamp} = await getTxCostAndTimestamp(txResult);
@@ -317,7 +343,7 @@ export const borrow = async (
       reserveData: reserveDataAfter,
       userData: userDataAfter,
       timestamp,
-    } = await getContractsData(reserve, user.address, testEnv);
+    } = await getContractsData(reserve, onBehalfOf, testEnv, user.address);
 
     const expectedReserveData = calcExpectedReserveDataAfterBorrow(
       amountToBorrow.toString(),
@@ -364,7 +390,7 @@ export const borrow = async (
     // });
   } else if (expectedResult === 'revert') {
     await expect(
-      pool.connect(user.signer).borrow(reserve, amountToBorrow, interestRateMode, '0'),
+      pool.connect(user.signer).borrow(reserve, amountToBorrow, interestRateMode, '0', onBehalfOf),
       revertMessage
     ).to.be.reverted;
   }
@@ -845,10 +871,15 @@ const getTxCostAndTimestamp = async (tx: ContractReceipt) => {
   return {txCost, txTimestamp};
 };
 
-const getContractsData = async (reserve: string, user: string, testEnv: TestEnv) => {
+const getContractsData = async (
+  reserve: string,
+  user: string,
+  testEnv: TestEnv,
+  sender?: string
+) => {
   const {pool} = testEnv;
   const reserveData = await getReserveData(pool, reserve);
-  const userData = await getUserData(pool, reserve, user);
+  const userData = await getUserData(pool, reserve, user, sender || user);
   const timestamp = await timeLatest();
 
   return {

test/helpers/scenario-engine.ts

@@ -12,6 +12,7 @@ import {
   redirectInterestStream,
   redirectInterestStreamOf,
   allowInterestRedirectionTo,
+  delegateBorrowAllowance,
 } from './actions';
 import {RateMode} from '../../helpers/types';
 
@@ -102,6 +103,18 @@ const executeAction = async (action: Action, users: SignerWithAddress[], testEnv
       }
       break;
 
+    case 'delegateBorrowAllowance':
+      {
+        const {amount, toUser: toUserIndex} = action.args;
+        const toUser = users[parseInt(toUserIndex, 10)].address;
+        if (!amount || amount === '') {
+          throw `Invalid amount to deposit into the ${reserve} reserve`;
+        }
+
+        await delegateBorrowAllowance(reserve, amount, user, toUser, testEnv);
+      }
+      break;
+
     case 'withdraw':
       {
         const {amount} = action.args;
@@ -115,13 +128,27 @@ const executeAction = async (action: Action, users: SignerWithAddress[], testEnv
       break;
     case 'borrow':
       {
-        const {amount, timeTravel} = action.args;
+        const {amount, timeTravel, onBehalfOf: onBehalfOfIndex} = action.args;
+
+        const onBehalfOf = onBehalfOfIndex
+          ? users[parseInt(onBehalfOfIndex)].address
+          : user.address;
 
         if (!amount || amount === '') {
           throw `Invalid amount to borrow from the ${reserve} reserve`;
         }
 
-        await borrow(reserve, amount, rateMode, user, timeTravel, expected, testEnv, revertMessage);
+        await borrow(
+          reserve,
+          amount,
+          rateMode,
+          user,
+          onBehalfOf,
+          timeTravel,
+          expected,
+          testEnv,
+          revertMessage
+        );
       }
       break;
 

test/helpers/scenarios/borrow-repay-variable.json

@@ -955,6 +955,85 @@
           "expected": "success"
         }
       ]
+    },
+    {
+      "description": "User 0 deposits 1000 DAI, user 0 delegates borrowing of 1 WETH to user 4, user 4 borrows 1 WETH on behalf of user 0",
+      "actions": [
+        {
+          "name": "mint",
+          "args": {
+            "reserve": "DAI",
+            "amount": "1000",
+            "user": "0"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "approve",
+          "args": {
+            "reserve": "DAI",
+            "user": "0"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "deposit",
+          "args": {
+            "reserve": "DAI",
+            "amount": "1000",
+            "user": "0"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "delegateBorrowAllowance",
+          "args": {
+            "reserve": "WETH",
+            "amount": "1",
+            "user": "0",
+            "toUser": "4"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "borrow",
+          "args": {
+            "reserve": "WETH",
+            "amount": "1",
+            "user": "4",
+            "onBehalfOf": "0",
+            "borrowRateMode": "variable"
+          },
+          "expected": "success"
+        }
+      ]
+    },
+    {
+      "description": "User 0 delegates borrowing of 1 WETH to user 4, user 4 borrows 2 WETH on behalf of user 0, revert expected",
+      "actions": [
+        {
+          "name": "delegateBorrowAllowance",
+          "args": {
+            "reserve": "WETH",
+            "amount": "1",
+            "user": "0",
+            "toUser": "4"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "borrow",
+          "args": {
+            "reserve": "WETH",
+            "amount": "2",
+            "user": "4",
+            "onBehalfOf": "0",
+            "borrowRateMode": "variable"
+          },
+          "expected": "revert",
+          "revertMessage": "52"
+        }
+      ]
     }
   ]
 }

test/helpers/utils/helpers.ts

@@ -61,7 +61,8 @@ export const getReserveData = async (
 export const getUserData = async (
   pool: LendingPool,
   reserve: string,
-  user: string
+  user: tEthereumAddress,
+  sender?: tEthereumAddress
 ): Promise<UserReserveData> => {
   const [userData, aTokenData] = await Promise.all([
     pool.getUserReserveData(reserve, user),
@@ -77,7 +78,7 @@ export const getUserData = async (
   ] = aTokenData;
 
   const token = await getMintableErc20(reserve);
-  const walletBalance = new BigNumber((await token.balanceOf(user)).toString());
+  const walletBalance = new BigNumber((await token.balanceOf(sender || user)).toString());
 
   return {
     principalATokenBalance: new BigNumber(principalATokenBalance),

test/liquidation-atoken.spec.ts

@@ -59,7 +59,7 @@ makeSuite('LendingPool liquidation - liquidator receiving aToken', (testEnv) =>
 
     await pool
       .connect(borrower.signer)
-      .borrow(dai.address, amountDAIToBorrow, RateMode.Variable, '0');
+      .borrow(dai.address, amountDAIToBorrow, RateMode.Variable, '0', borrower.address);
 
     const userGlobalDataAfter = await pool.getUserAccountData(borrower.address);
 
@@ -252,7 +252,7 @@ makeSuite('LendingPool liquidation - liquidator receiving aToken', (testEnv) =>
 
     await pool
       .connect(borrower.signer)
-      .borrow(usdc.address, amountUSDCToBorrow, RateMode.Stable, '0');
+      .borrow(usdc.address, amountUSDCToBorrow, RateMode.Stable, '0', borrower.address);
 
     //drops HF below 1
 

test/liquidation-underlying.spec.ts

@@ -56,7 +56,7 @@ makeSuite('LendingPool liquidation - liquidator receiving the underlying asset',
 
     await pool
       .connect(borrower.signer)
-      .borrow(dai.address, amountDAIToBorrow, RateMode.Stable, '0');
+      .borrow(dai.address, amountDAIToBorrow, RateMode.Stable, '0', borrower.address);
 
     const userGlobalDataAfter = await pool.getUserAccountData(borrower.address);
 
@@ -222,7 +222,7 @@ makeSuite('LendingPool liquidation - liquidator receiving the underlying asset',
 
     await pool
       .connect(borrower.signer)
-      .borrow(usdc.address, amountUSDCToBorrow, RateMode.Stable, '0');
+      .borrow(usdc.address, amountUSDCToBorrow, RateMode.Stable, '0', borrower.address);
 
     //drops HF below 1
     await oracle.setAssetPrice(