updated interest redirection

contracts/tokenization/AToken.sol

@@ -31,7 +31,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
   mapping(address => address) private _interestRedirectionAddresses;
   mapping(address => uint256) private _interestRedirectionIndexes;
 
-  mapping(address => uint256) private _redirectedBalances;
+  mapping(address => uint256) private _scaledRedirectedBalances;
   mapping(address => uint256) private _redirectedBalanceIndexes;
 
   mapping(address => address) private _interestRedirectionAllowances;
@@ -163,7 +163,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     //if the user is redirecting his interest towards someone else,
     //we update the redirected balance of the redirection address by adding the accrued interest
     //and the amount deposited
-    _updateRedirectedBalanceOfRedirectionAddress(user, user, amount, 0, index);
+    _updateRedirectedBalanceOfRedirectionAddress(user, user, scaledAmount, 0, index);
 
     emit Mint(user, amount, index);
   }
@@ -192,16 +192,17 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
    * @return the total balance of the user
    **/
   function balanceOf(address user) public override(ERC20, IERC20) view returns (uint256) {
+  
     //current scaled balance of the user
     uint256 currentScaledBalance = super.balanceOf(user);
     
     //balance redirected by other users to user for interest rate accrual
-    uint256 redirectedBalance = _redirectedBalances[user];
+    uint256 scaledRedirectedBalance = _scaledRedirectedBalances[user];
 
-    if (currentScaledBalance == 0 && redirectedBalance == 0) {
+    if (currentScaledBalance == 0 && scaledRedirectedBalance == 0) {
       return 0;
     }
-    uint256 scaledRedirectedBalance = redirectedBalance > 0 ?  redirectedBalance.rayDiv(_redirectedBalanceIndexes[user]) : 0;
+    uint256 actualBalanceRedirectedToUser = scaledRedirectedBalance > 0 ?  scaledRedirectedBalance.rayMul(_redirectedBalanceIndexes[user]) : 0;
 
     uint256 index = _pool.getReserveNormalizedIncome(UNDERLYING_ASSET_ADDRESS);
 
@@ -209,16 +210,16 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
       //if the user is not redirecting the interest, his balance is the result of
       //the interest accrued by his current scaled balance and the interest accrued by his
       //scaled redirected balance
-      return currentScaledBalance.add(scaledRedirectedBalance).rayMul(index).sub(scaledRedirectedBalance);
+      return currentScaledBalance.add(scaledRedirectedBalance).rayMul(index).sub(actualBalanceRedirectedToUser);
     }
 
     //if the user is redirecting, his balance only increases by the balance he is being redirected to
-    uint256 lastRedirectedBalance = currentScaledBalance.rayDiv(_interestRedirectionIndexes[user]);
+    uint256 lastBalanceRedirectedByUser = currentScaledBalance.rayMul(_interestRedirectionIndexes[user]);
 
     return
-      lastRedirectedBalance.add(
+      lastBalanceRedirectedByUser.add(
         scaledRedirectedBalance.rayMul(index)
-      ).sub(scaledRedirectedBalance);
+      ).sub(actualBalanceRedirectedToUser);
   }
 
   /**
@@ -227,7 +228,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
    * @param user the address of the user
    * @return the scaled balance of the user
    **/
-  function scaledBalanceOf(address user) public override view returns (uint256) {
+  function scaledBalanceOf(address user) external override view returns (uint256) {
     return super.balanceOf(user);
   }
 
@@ -288,10 +289,22 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
    * @param user address of the user
    * @return the total redirected balance
    **/
-  function getRedirectedBalance(address user) external override view returns (uint256) {
+  function getScaledRedirectedBalance(address user) external override view returns (uint256) {
-    return _redirectedBalances[user];
+    return _scaledRedirectedBalances[user];
   }
 
+    /**
+   * @dev returns the index stored during the last action that affected the redirected balance.
+   * scaledRedirectedBalance * redirectedBalanceIndex allows to calculate the actual redirected balance
+   * which is needed to calculate the interest accrued
+   * @param user address of the user
+   * @return the total redirected balance
+   **/
+  function getRedirectedBalanceIndex(address user) external override view returns (uint256) {
+    return _redirectedBalanceIndexes[user];
+  }
+
+
 
   /**
    * @dev updates the redirected balance of the user. If the user is not redirecting his
@@ -313,12 +326,8 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
       return;
     }
 
-    //updating the interest redirection index of the user
-    _interestRedirectionIndexes[user] = index;
-
-
     //updating the redirected balance
-    _redirectedBalances[redirectionAddress] = _redirectedBalances[redirectionAddress]
+    _scaledRedirectedBalances[redirectionAddress] = _scaledRedirectedBalances[redirectionAddress]
       .add(scaledBalanceToAdd)
       .sub(scaledBalanceToRemove);
 
@@ -362,6 +371,8 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
 
     require(to != currentRedirectionAddress, Errors.INTEREST_ALREADY_REDIRECTED);
 
+    uint256 scaledFromBalance = super.balanceOf(from);
+
     uint256 fromBalance = balanceOf(from);
 
     require(fromBalance > 0, Errors.NO_VALID_BALANCE_FOR_REDIRECTION);
@@ -374,7 +385,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     //the redirection address we substract the redirected balance of the previous
     //recipient
     if (currentRedirectionAddress != address(0)) {
-      _updateRedirectedBalanceOfRedirectionAddress(from, from, 0, scaledBalance, index);
+      _updateRedirectedBalanceOfRedirectionAddress(from, from, 0, scaledFromBalance, index);
     }
 
     //if the user is redirecting the interest back to himself,
@@ -390,7 +401,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     _interestRedirectionIndexes[from] = index;
 
     //adds the user balance to the redirected balance of the destination
-    _updateRedirectedBalanceOfRedirectionAddress(from, from, fromBalance, 0, index);
+    _updateRedirectedBalanceOfRedirectionAddress(from, from, scaledBalance, 0, index);
 
     emit InterestStreamRedirected(from, to, fromBalance, index);
   }
@@ -457,7 +468,7 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     //being transferred
     _updateRedirectedBalanceOfRedirectionAddress(to, to, scaledAmount, 0, index);
 
-    if(scaledBalanceOf(from) == 0){
+    if(super.balanceOf(from) == 0){
       _resetDataOnZeroBalance(from);
     }
 

contracts/tokenization/interfaces/IAToken.sol

@@ -159,12 +159,20 @@ interface IAToken is IERC20 {
   function getUserInterestRedirectionIndex(address user) external view returns (uint256);
 
   /**
-   * @dev returns the redirected balance of the user. The redirected balance is the balance
+   * @dev returns the scaled redirected balance of the user. The scaled redirected balance is the sum of all the redirected balances
-   * redirected by other accounts to the user, that is accrueing interest for him.
+   * divided by the index at the moment of each specific redirection.
    * @param user address of the user
    * @return the total redirected balance
    **/
-  function getRedirectedBalance(address user) external view returns (uint256);
+  function getScaledRedirectedBalance(address user) external view returns (uint256);
+
+  /**
+   * @dev returns the redirected balance index. The redirected balance index is the 
+   * index at the moment the last scaled redirected balance has been performed, and allows to calculate the actual redirected balance
+   * @param user address of the user
+   * @return the redirected balance index
+   **/
+  function getRedirectedBalanceIndex(address user) external view returns (uint256);
 
   /**
    * @dev transfers the underlying asset to the target. Used by the lendingpool to transfer

test.log

@@ -2483,7 +2483,7 @@ gas used: 6117750
   28) AToken: interest rate redirection negative test cases
        User 0 tries to redirect the interest to user 2 twice (revert expected):
 
-      AssertionError: expected '3000000004839170420641' to be almost equal or equal '3000002810040899373373' for property redirectionAddressRedirectedBalance
+      AssertionError: expected '3000000004839170420641' to be almost equal or equal '3000002810040899373373' for property redirectionAddressScaledRedirectedBalance
       + expected - actual
 
       -3000000004839170420641
@@ -2550,7 +2550,7 @@ gas used: 6117750
   32) AToken: interest rate redirection
        User 0 deposits 1000 DAI, redirects interest to user 2, user 1 borrows 100 DAI. After one year, user 0 redirects interest back to himself, user 1 borrows another 100 DAI and after another year repays the whole amount. Users 0 and User 2 withdraw:
 
-      AssertionError: expected '1020673496610825275870' to be almost equal or equal '1020673496616475023834' for property redirectionAddressRedirectedBalance
+      AssertionError: expected '1020673496610825275870' to be almost equal or equal '1020673496616475023834' for property redirectionAddressScaledRedirectedBalance
       + expected - actual
 
       -1020673496610825275870

test/helpers/actions.ts

@@ -59,7 +59,7 @@ const almostEqualOrEqual = function (
     this.assert(actual[key] != undefined, `Property ${key} is undefined in the actual data`);
     expect(expected[key] != undefined, `Property ${key} is undefined in the expected data`);
 
-    if (expected[key] == null || !actual[key] == null) {
+    if (expected[key] == null || actual[key] == null) {
       console.log('Found a undefined value for Key ', key, ' value ', expected[key], actual[key]);
     }
 

test/helpers/utils/calculations.ts

@@ -70,12 +70,14 @@ export const calcExpectedUserDataAfterDeposit = (
   expectedUserData.variableBorrowIndex = userDataBeforeAction.variableBorrowIndex;
   expectedUserData.walletBalance = userDataBeforeAction.walletBalance.minus(amountDeposited);
 
-  expectedUserData.redirectedBalance = userDataBeforeAction.redirectedBalance;
+  expectedUserData.scaledRedirectedBalance = userDataBeforeAction.scaledRedirectedBalance;
+  expectedUserData.redirectedBalanceIndex = userDataBeforeAction.redirectedBalanceIndex;
   expectedUserData.interestRedirectionAddress = userDataBeforeAction.interestRedirectionAddress;
   expectedUserData.interestRedirectionIndex =
     userDataBeforeAction.interestRedirectionAddress == ZERO_ADDRESS
       ? new BigNumber(0)
       : reserveDataAfterAction.liquidityIndex;
+    
 
   expectedUserData.currentStableDebt = expectedUserData.principalStableDebt = calcExpectedStableDebtTokenBalance(
     userDataBeforeAction,
@@ -88,10 +90,10 @@ export const calcExpectedUserDataAfterDeposit = (
     txTimestamp
   );
 
-  expectedUserData.redirectionAddressRedirectedBalance = calcExpectedRedirectedBalance(
+  expectedUserData.redirectionAddressScaledRedirectedBalance = calcExpectedRedirectedBalance(
     expectedUserData,
     reserveDataAfterAction.liquidityIndex,
-    userDataBeforeAction.redirectionAddressRedirectedBalance,
+    userDataBeforeAction.redirectionAddressScaledRedirectedBalance,
     new BigNumber(amountDeposited),
     new BigNumber(0)
   );
@@ -161,9 +163,11 @@ export const calcExpectedUserDataAfterWithdraw = (
   }
 
   expectedUserData.walletBalance = userDataBeforeAction.walletBalance.plus(amountWithdrawn);
-  expectedUserData.redirectedBalance = userDataBeforeAction.redirectedBalance;
+  expectedUserData.scaledRedirectedBalance = userDataBeforeAction.scaledRedirectedBalance;
+  expectedUserData.redirectedBalanceIndex = userDataBeforeAction.redirectedBalanceIndex;
 
-  if (expectedUserData.currentATokenBalance.eq(0) && expectedUserData.redirectedBalance.eq(0)) {
+
+  if (expectedUserData.currentATokenBalance.eq(0) && expectedUserData.scaledRedirectedBalance.eq(0)) {
     expectedUserData.interestRedirectionAddress = ZERO_ADDRESS;
     expectedUserData.interestRedirectionIndex = new BigNumber(0);
   } else {
@@ -174,10 +178,10 @@ export const calcExpectedUserDataAfterWithdraw = (
         : reserveDataAfterAction.liquidityIndex;
   }
 
-  expectedUserData.redirectionAddressRedirectedBalance = calcExpectedRedirectedBalance(
+  expectedUserData.redirectionAddressScaledRedirectedBalance = calcExpectedRedirectedBalance(
     expectedUserData,
     reserveDataAfterAction.liquidityIndex,
-    userDataBeforeAction.redirectionAddressRedirectedBalance,
+    userDataBeforeAction.redirectionAddressScaledRedirectedBalance,
     new BigNumber(0),
     new BigNumber(amountWithdrawn)
   );
@@ -574,11 +578,12 @@ export const calcExpectedUserDataAfterBorrow = (
     currentTimestamp
   );
   expectedUserData.scaledATokenBalance = userDataBeforeAction.scaledATokenBalance;
-  expectedUserData.redirectedBalance = userDataBeforeAction.redirectedBalance;
+  expectedUserData.scaledRedirectedBalance = userDataBeforeAction.scaledRedirectedBalance;
+  expectedUserData.redirectedBalanceIndex = userDataBeforeAction.redirectedBalanceIndex;
   expectedUserData.interestRedirectionAddress = userDataBeforeAction.interestRedirectionAddress;
   expectedUserData.interestRedirectionIndex = userDataBeforeAction.interestRedirectionIndex;
-  expectedUserData.redirectionAddressRedirectedBalance =
+  expectedUserData.redirectionAddressScaledRedirectedBalance =
-    userDataBeforeAction.redirectionAddressRedirectedBalance;
+    userDataBeforeAction.redirectionAddressScaledRedirectedBalance;
   expectedUserData.currentATokenUserIndex = userDataBeforeAction.currentATokenUserIndex;
 
   expectedUserData.walletBalance = userDataBeforeAction.walletBalance.plus(amountBorrowed);
@@ -664,11 +669,12 @@ export const calcExpectedUserDataAfterRepay = (
     txTimestamp
   );
   expectedUserData.scaledATokenBalance = userDataBeforeAction.scaledATokenBalance;
-  expectedUserData.redirectedBalance = userDataBeforeAction.redirectedBalance;
+  expectedUserData.redirectedBalanceIndex = userDataBeforeAction.redirectedBalanceIndex;
+  expectedUserData.scaledRedirectedBalance = userDataBeforeAction.scaledRedirectedBalance;
   expectedUserData.interestRedirectionAddress = userDataBeforeAction.interestRedirectionAddress;
   expectedUserData.interestRedirectionIndex = userDataBeforeAction.interestRedirectionIndex;
-  expectedUserData.redirectionAddressRedirectedBalance =
+  expectedUserData.redirectionAddressScaledRedirectedBalance =
-    userDataBeforeAction.redirectionAddressRedirectedBalance;
+    userDataBeforeAction.redirectionAddressScaledRedirectedBalance;
   expectedUserData.currentATokenUserIndex = userDataBeforeAction.currentATokenUserIndex;
 
   if (user === onBehalfOf) {
@@ -996,25 +1002,29 @@ export const calcExpectedUsersDataAfterRedirectInterest = (
   );
 
 
-  expectedToData.redirectedBalance = toDataBeforeAction.redirectedBalance.plus(
+  expectedToData.scaledRedirectedBalance = toDataBeforeAction.scaledRedirectedBalance.plus(
-    expectedFromData.currentATokenBalance.rayDiv(index)
+    expectedFromData.scaledATokenBalance
   );
 
+  expectedToData.redirectedBalanceIndex = index;
+
   if (fromAddress === toAddress) {
     expectedFromData.interestRedirectionAddress = ZERO_ADDRESS;
-    expectedFromData.redirectedBalance = new BigNumber(0);
+    expectedFromData.scaledRedirectedBalance = new BigNumber(0);
-    expectedFromData.redirectionAddressRedirectedBalance = new BigNumber(0);
+    expectedFromData.redirectedBalanceIndex = new BigNumber(0);
+
+    expectedFromData.redirectionAddressScaledRedirectedBalance = new BigNumber(0);
     expectedToData.interestRedirectionAddress = ZERO_ADDRESS;
-    expectedToData.redirectedBalance = new BigNumber(0);
+    expectedToData.scaledRedirectedBalance = new BigNumber(0);
-    expectedToData.redirectionAddressRedirectedBalance = new BigNumber(0);
+    expectedToData.redirectionAddressScaledRedirectedBalance = new BigNumber(0);
   } else {
     expectedFromData.interestRedirectionAddress = toAddress;
     expectedFromData.interestRedirectionIndex = index;
 
-    expectedFromData.redirectionAddressRedirectedBalance = calcExpectedRedirectedBalance(
+    expectedFromData.redirectionAddressScaledRedirectedBalance = calcExpectedRedirectedBalance(
       expectedFromData,
       index,
-      toDataBeforeAction.redirectedBalance,
+      toDataBeforeAction.scaledRedirectedBalance,
       expectedFromData.currentATokenBalance,
       new BigNumber(0)
     );
@@ -1044,21 +1054,25 @@ const calcExpectedATokenBalance = (
   const {
     interestRedirectionAddress,
     interestRedirectionIndex: redirectionIndexBeforeAction,
-    redirectedBalance,
+    scaledRedirectedBalance,
+    redirectedBalanceIndex: redirectedBalanceIndexBeforeAction,
     scaledATokenBalance: scaledBalanceBeforeAction,
   } = userDataBeforeAction;
 
-  if (scaledBalanceBeforeAction.eq(0) && redirectedBalance.eq(0)) {
+  if (scaledBalanceBeforeAction.eq(0) && scaledRedirectedBalance.eq(0)) {
     return new BigNumber(0);
   }
 
+  const actualRedirectedBalance = scaledRedirectedBalance.gt(0) ?  scaledRedirectedBalance.rayMul(redirectedBalanceIndexBeforeAction) : new BigNumber(0);
+
   if (interestRedirectionAddress === ZERO_ADDRESS) {
-    return scaledBalanceBeforeAction.plus(redirectedBalance).rayMul(index).minus(redirectedBalance);
+    return scaledBalanceBeforeAction.plus(scaledRedirectedBalance).rayMul(index).minus(actualRedirectedBalance);
   }
 
-  const lastRedirectedBalance = scaledBalanceBeforeAction.rayDiv(redirectionIndexBeforeAction);
 
-  return lastRedirectedBalance.plus(redirectedBalance.rayMul(index).minus(redirectedBalance));
+  const lastRedirectedBalance = scaledBalanceBeforeAction.rayMul(redirectionIndexBeforeAction);
+
+  return lastRedirectedBalance.plus(scaledRedirectedBalance.rayMul(index).minus(actualRedirectedBalance));
 };
 
 const calcExpectedRedirectedBalance = (

test/helpers/utils/helpers.ts

@@ -69,9 +69,10 @@ export const getUserData = async (
   ]);
 
   const [
-    redirectedBalance,
+    scaledRedirectedBalance,
+    redirectedBalanceIndex,
     scaledATokenBalance,
-    redirectionAddressRedirectedBalance,
+    redirectionAddressScaledRedirectedBalance,
     interestRedirectionAddress,
     interestRedirectionIndex,
   ] = aTokenData;
@@ -83,8 +84,9 @@ export const getUserData = async (
     scaledATokenBalance: new BigNumber(scaledATokenBalance),
     interestRedirectionAddress,
     interestRedirectionIndex: new BigNumber(interestRedirectionIndex),
-    redirectionAddressRedirectedBalance: new BigNumber(redirectionAddressRedirectedBalance),
+    redirectionAddressScaledRedirectedBalance: new BigNumber(redirectionAddressScaledRedirectedBalance),
-    redirectedBalance: new BigNumber(redirectedBalance),
+    scaledRedirectedBalance: new BigNumber(scaledRedirectedBalance),
+    redirectedBalanceIndex: new BigNumber(redirectedBalanceIndex),
     currentATokenBalance: new BigNumber(userData.currentATokenBalance.toString()),
     currentStableDebt: new BigNumber(userData.currentStableDebt.toString()),
     currentVariableDebt: new BigNumber(userData.currentVariableDebt.toString()),
@@ -116,25 +118,28 @@ const getATokenUserData = async (reserve: string, user: string, pool: LendingPoo
   const aToken = await getAToken(aTokenAddress);
   const [
     interestRedirectionAddress,
-    redirectedBalance,
+    scaledRedirectedBalance,
+    redirectedBalanceIndex,
     scaledATokenBalance,
     interestRedirectionIndex
   ] = await Promise.all([
     aToken.getInterestRedirectionAddress(user),
-    aToken.getRedirectedBalance(user),
+    aToken.getScaledRedirectedBalance(user),
+    aToken.getRedirectedBalanceIndex(user),
     aToken.scaledBalanceOf(user),
     aToken.getUserInterestRedirectionIndex(user)
   ]);
 
-  const redirectionAddressRedirectedBalance =
+  const redirectionAddressScaledRedirectedBalance =
     interestRedirectionAddress !== ZERO_ADDRESS
-      ? new BigNumber((await aToken.getRedirectedBalance(interestRedirectionAddress)).toString())
+      ? new BigNumber((await aToken.getScaledRedirectedBalance(interestRedirectionAddress)).toString())
       : new BigNumber('0');
 
   return [
-    redirectedBalance.toString(),
+    scaledRedirectedBalance.toString(),
+    redirectedBalanceIndex.toString(),
     scaledATokenBalance.toString(),
-    redirectionAddressRedirectedBalance.toString(),
+    redirectionAddressScaledRedirectedBalance.toString(),
     interestRedirectionAddress,
     interestRedirectionIndex.toString()
   ];

test/helpers/utils/interfaces/index.ts

@@ -5,8 +5,9 @@ export interface UserReserveData {
   currentATokenBalance: BigNumber;
   interestRedirectionAddress: string;
   interestRedirectionIndex: BigNumber;
-  redirectionAddressRedirectedBalance: BigNumber;
+  redirectionAddressScaledRedirectedBalance: BigNumber;
-  redirectedBalance: BigNumber;
+  scaledRedirectedBalance: BigNumber;
+  redirectedBalanceIndex: BigNumber;
   currentStableDebt: BigNumber;
   currentVariableDebt: BigNumber;
   principalStableDebt: BigNumber;