Add permit support in swap adapters

contracts/adapters/BaseUniswapAdapter.sol

@@ -12,6 +12,7 @@ import {ILendingPool} from '../interfaces/ILendingPool.sol';
 import {ReserveLogic} from '../libraries/logic/ReserveLogic.sol';
 import {IUniswapV2Router02} from '../interfaces/IUniswapV2Router02.sol';
 import {IPriceOracleGetter} from '../interfaces/IPriceOracleGetter.sol';
+import {IERC20WithPermit} from '../interfaces/IERC20WithPermit.sol';
 
 /**
  * @title BaseUniswapAdapter
@@ -25,6 +26,20 @@ contract BaseUniswapAdapter {
 
   enum LeftoverAction {DEPOSIT, TRANSFER}
 
+  struct PermitParams {
+    uint256[] deadline;
+    uint8[] v;
+    bytes32[] r;
+    bytes32[] s;
+  }
+
+  struct PermitSignature {
+    uint256 deadline;
+    uint8 v;
+    bytes32 r;
+    bytes32 s;
+  }
+
   // Max slippage percent allow by param
   uint256 public constant MAX_SLIPPAGE_PERCENT = 3000; // 30%
   // Min slippage percent allow by param
@@ -221,14 +236,28 @@ contract BaseUniswapAdapter {
    * @param reserve address of the asset
    * @param user address
    * @param amount of tokens to be transferred to the contract
+   * @param permitSignature struct containing the permit signature
    */
   function pullAToken(
     address reserve,
     address user,
-    uint256 amount
+    uint256 amount,
+    PermitSignature memory permitSignature
   ) internal {
     address reserveAToken = getAToken(reserve);
 
+    if (_usePermit(permitSignature)) {
+      IERC20WithPermit(reserveAToken).permit(
+        user,
+        address(this),
+        amount,
+        permitSignature.deadline,
+        permitSignature.v,
+        permitSignature.r,
+        permitSignature.s
+      );
+    }
+
     // transfer from user to adapter
     IERC20(reserveAToken).safeTransferFrom(user, address(this), amount);
 
@@ -241,15 +270,28 @@ contract BaseUniswapAdapter {
    * @param reserve address of the asset
    * @param user address
    * @param flashLoanDebt need to be repaid
+   * @param permitSignature struct containing the permit signature
    */
   function pullATokenAndRepayFlashLoan(
     address reserve,
     address user,
-    uint256 flashLoanDebt
+    uint256 flashLoanDebt,
+    PermitSignature memory permitSignature
   ) internal {
-    pullAToken(reserve, user, flashLoanDebt);
+    pullAToken(reserve, user, flashLoanDebt, permitSignature);
 
     // Repay flashloan
     IERC20(reserve).approve(address(POOL), flashLoanDebt);
   }
+
+  /**
+   * @dev Tells if the permit method should be called by inspecting if there is a valid signature.
+   * If signature params are set to 0, then permit won't be called.
+   * @param signature struct containing the permit signature
+   * @return whether or not permit should be called
+   */
+  function _usePermit(PermitSignature memory signature) internal pure returns (bool) {
+    return !(uint256(signature.deadline) == uint256(signature.v) &&
+      uint256(signature.deadline) == 0);
+  }
 }

contracts/adapters/UniswapLiquiditySwapAdapter.sol

@@ -15,6 +15,12 @@ import {IERC20} from '../dependencies/openzeppelin/contracts/IERC20.sol';
  **/
 contract UniswapLiquiditySwapAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
 
+  struct SwapParams {
+    address[] assetToSwapToList;
+    uint256 slippage;
+    PermitParams permitParams;
+  }
+
   constructor(
     ILendingPoolAddressesProvider addressesProvider,
     IUniswapV2Router02 uniswapRouter
@@ -35,6 +41,10 @@ contract UniswapLiquiditySwapAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
    * @param params Additional variadic field to include extra params. Expected parameters:
    *   address[] assetToSwapToList List of the addresses of the reserve to be swapped to and deposited
    *   uint256 slippage The max slippage percentage allowed for the swap
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint8[] v List of v param for the permit signature
+   *   bytes32[] r List of r param for the permit signature
+   *   bytes32[] s List of s param for the permit signature
    */
   function executeOperation(
     address[] calldata assets,
@@ -45,19 +55,46 @@ contract UniswapLiquiditySwapAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
   ) external override returns (bool) {
     require(msg.sender == address(POOL), "CALLER_MUST_BE_LENDING_POOL");
 
-    (address[] memory assetToSwapToList, uint256 slippage) = abi.decode(params, (address[], uint256));
+    SwapParams memory decodedParams = _decodeParams(params);
-    require(slippage < MAX_SLIPPAGE_PERCENT && slippage >= MIN_SLIPPAGE_PERCENT, 'SLIPPAGE_OUT_OF_RANGE');
+
-    require(assetToSwapToList.length == assets.length, 'INCONSISTENT_PARAMS');
+    require(
+      decodedParams.slippage < MAX_SLIPPAGE_PERCENT && decodedParams.slippage >= MIN_SLIPPAGE_PERCENT,
+      'SLIPPAGE_OUT_OF_RANGE'
+    );
+
+    require(
+      decodedParams.assetToSwapToList.length == assets.length
+      && assets.length == decodedParams.permitParams.deadline.length
+      && assets.length == decodedParams.permitParams.v.length
+      && assets.length == decodedParams.permitParams.r.length
+      && assets.length == decodedParams.permitParams.s.length,
+      'INCONSISTENT_PARAMS'
+    );
 
     for (uint256 i = 0; i < assets.length; i++) {
-      uint256 receivedAmount = swapExactTokensForTokens(assets[i], assetToSwapToList[i], amounts[i], slippage);
+      uint256 receivedAmount = swapExactTokensForTokens(
+        assets[i],
+        decodedParams.assetToSwapToList[i],
+        amounts[i],
+        decodedParams.slippage
+      );
 
       // Deposit new reserve
-      IERC20(assetToSwapToList[i]).approve(address(POOL), receivedAmount);
+      IERC20(decodedParams.assetToSwapToList[i]).approve(address(POOL), receivedAmount);
-      POOL.deposit(assetToSwapToList[i], receivedAmount, initiator, 0);
+      POOL.deposit(decodedParams.assetToSwapToList[i], receivedAmount, initiator, 0);
 
       uint256 flashLoanDebt = amounts[i].add(premiums[i]);
-      pullATokenAndRepayFlashLoan(assets[i], initiator, flashLoanDebt);
+      pullATokenAndRepayFlashLoan(
+        assets[i],
+        initiator,
+        flashLoanDebt,
+        PermitSignature(
+          decodedParams.permitParams.deadline[i],
+          decodedParams.permitParams.v[i],
+          decodedParams.permitParams.r[i],
+          decodedParams.permitParams.s[i]
+        )
+      );
     }
 
     return true;
@@ -72,20 +109,32 @@ contract UniswapLiquiditySwapAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
    * @param assetToSwapToList List of addresses of the underlying asset to be swap to and deposited
    * @param amountToSwapList List of amounts to be swapped
    * @param slippage The max slippage percentage allowed for the swap
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint8[] v List of v param for the permit signature
+   *   bytes32[] r List of r param for the permit signature
+   *   bytes32[] s List of s param for the permit signature
    */
   function swapAndDeposit(
     address[] calldata assetToSwapFromList,
     address[] calldata assetToSwapToList,
     uint256[] calldata amountToSwapList,
-    uint256 slippage
+    uint256 slippage,
+    PermitSignature[] calldata permitParams
   ) external {
     require(
-      assetToSwapFromList.length == assetToSwapToList.length && assetToSwapFromList.length == amountToSwapList.length,
+      assetToSwapFromList.length == assetToSwapToList.length
+      && assetToSwapFromList.length == amountToSwapList.length
+      && assetToSwapFromList.length == permitParams.length,
       'INCONSISTENT_PARAMS'
     );
 
     for (uint256 i = 0; i < assetToSwapFromList.length; i++) {
-      pullAToken(assetToSwapFromList[i], msg.sender, amountToSwapList[i]);
+      pullAToken(
+        assetToSwapFromList[i],
+        msg.sender,
+        amountToSwapList[i],
+        permitParams[i]
+      );
 
       uint256 receivedAmount = swapExactTokensForTokens(
         assetToSwapFromList[i],
@@ -99,4 +148,29 @@ contract UniswapLiquiditySwapAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
       POOL.deposit(assetToSwapToList[i], receivedAmount, msg.sender, 0);
     }
   }
+
+  /**
+ * @dev Decodes debt information encoded in flashloan params
+ * @param params Additional variadic field to include extra params. Expected parameters:
+   *   address[] assetToSwapToList List of the addresses of the reserve to be swapped to and deposited
+   *   uint256 slippage The max slippage percentage allowed for the swap
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint8[] v List of v param for the permit signature
+   *   bytes32[] r List of r param for the permit signature
+   *   bytes32[] s List of s param for the permit signature
+ * @return SwapParams struct containing decoded params
+ */
+  function _decodeParams(bytes memory params) internal returns (SwapParams memory) {
+    (
+      address[] memory assetToSwapToList,
+      uint256 slippage,
+      uint256[] memory deadline,
+      uint8[] memory v,
+      bytes32[] memory r,
+      bytes32[] memory s
+    ) = abi.decode(params, (address[], uint256, uint256[], uint8[], bytes32[], bytes32[]));
+
+    return SwapParams(assetToSwapToList, slippage, PermitParams(deadline, v, r, s));
+  }
 }

contracts/adapters/UniswapRepayAdapter.sol

@@ -20,6 +20,7 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
     LeftoverAction leftOverAction;
     uint256[] repayAmounts;
     uint256[] rateModes;
+    PermitParams permitParams;
   }
 
   constructor(
@@ -46,6 +47,10 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
    *     (1) Direct transfer to user
    *   uint256[] repayAmounts List of amounts of debt to be repaid
    *   uint256[] rateModes List of the rate modes of the debt to be repaid
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint8[] v List of v param for the permit signature
+   *   bytes32[] r List of r param for the permit signature
+   *   bytes32[] s List of s param for the permit signature
    */
   function executeOperation(
     address[] calldata assets,
@@ -61,7 +66,11 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
     require(
       assets.length == decodedParams.assetToSwapToList.length
       && assets.length == decodedParams.repayAmounts.length
-      && assets.length == decodedParams.rateModes.length,
+      && assets.length == decodedParams.rateModes.length
+      && assets.length == decodedParams.permitParams.deadline.length
+      && assets.length == decodedParams.permitParams.v.length
+      && assets.length == decodedParams.permitParams.r.length
+      && assets.length == decodedParams.permitParams.s.length,
       'INCONSISTENT_PARAMS');
 
     for (uint256 i = 0; i < assets.length; i++) {
@@ -73,7 +82,13 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
         decodedParams.rateModes[i],
         initiator,
         decodedParams.leftOverAction,
-        premiums[i]
+        premiums[i],
+        PermitSignature(
+          decodedParams.permitParams.deadline[i],
+          decodedParams.permitParams.v[i],
+          decodedParams.permitParams.r[i],
+          decodedParams.permitParams.s[i]
+        )
       );
     }
 
@@ -91,6 +106,7 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
    * @param initiator Address of the user
    * @param leftOverAction enum indicating what to do with the left over balance from the swap
    * @param premium Fee of the flash loan
+   * @param permitSignature struct containing the permit signature
    */
   function _swapAndRepay(
     address assetFrom,
@@ -100,7 +116,8 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
     uint256 rateMode,
     address initiator,
     LeftoverAction leftOverAction,
-    uint256 premium
+    uint256 premium,
+    PermitSignature memory permitSignature
   ) internal {
     swapTokensForExactTokens(assetFrom, assetTo, amount, repayAmount);
 
@@ -109,7 +126,7 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
     POOL.repay(assetTo, repayAmount, rateMode, initiator);
 
     uint256 flashLoanDebt = amount.add(premium);
-    pullATokenAndRepayFlashLoan(assetFrom, initiator, flashLoanDebt);
+    pullATokenAndRepayFlashLoan(assetFrom, initiator, flashLoanDebt, permitSignature);
 
     // Take care of reserve leftover from the swap
     sendLeftovers(assetFrom, flashLoanDebt, leftOverAction, initiator);
@@ -124,6 +141,10 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
    *     (1) Direct transfer to user
    *   uint256[] repayAmounts List of amounts of debt to be repaid
    *   uint256[] rateModes List of the rate modes of the debt to be repaid
+   *   uint256[] deadline List of deadlines for the permit signature
+   *   uint8[] v List of v param for the permit signature
+   *   bytes32[] r List of r param for the permit signature
+   *   bytes32[] s List of s param for the permit signature
    * @return RepayParams struct containing decoded params
    */
   function _decodeParams(bytes memory params) internal returns (RepayParams memory) {
@@ -131,9 +152,24 @@ contract UniswapRepayAdapter is BaseUniswapAdapter, IFlashLoanReceiver {
       address[] memory assetToSwapToList,
       LeftoverAction leftOverAction,
       uint256[] memory repayAmounts,
-      uint256[] memory rateModes
+      uint256[] memory rateModes,
-    ) = abi.decode(params, (address[], LeftoverAction, uint256[], uint256[]));
+      uint256[] memory deadline,
+      uint8[] memory v,
+      bytes32[] memory r,
+      bytes32[] memory s
+    ) = abi.decode(params, (address[], LeftoverAction, uint256[], uint256[], uint256[], uint8[], bytes32[], bytes32[]));
 
-    return RepayParams(assetToSwapToList, leftOverAction, repayAmounts, rateModes);
+    return RepayParams(
+      assetToSwapToList,
+        leftOverAction,
+        repayAmounts,
+        rateModes,
+        PermitParams(
+          deadline,
+          v,
+          r,
+          s
+        )
+    );
   }
 }

contracts/interfaces/IERC20WithPermit.sol

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: agpl-3.0
+pragma solidity ^0.6.8;
+
+import {IERC20} from '../dependencies/openzeppelin/contracts/IERC20.sol';
+
+interface IERC20WithPermit is IERC20 {
+  function permit(
+    address owner,
+    address spender,
+    uint256 value,
+    uint256 deadline,
+    uint8 v,
+    bytes32 r,
+    bytes32 s
+  ) external;
+}