feat: add ERC712 permit to functions with transferFrom

src/Position.sol

@@ -6,6 +6,7 @@ import { DebtService } from "src/services/DebtService.sol";
 import { SwapService } from "src/services/SwapService.sol";
 import { SafeTransferLib, ERC20 } from "solmate/utils/SafeTransferLib.sol";
 import { IERC20 } from "src/interfaces/token/IERC20.sol";
+import { IERC20Permit } from "src/interfaces/token/IERC20Permit.sol";
 import { IFeeCollector } from "src/interfaces/IFeeCollector.sol";
 
 /// @title Position
@@ -62,6 +63,36 @@ contract Position is DebtService, SwapService {
         emit Short(cAmtNet, dAmt, bAmt);
     }
 
+    /**
+     * @notice Adds to this contract's short position with permit, obviating the need for a separate approve tx.
+     * @param _cAmt The amount of collateral to be supplied for this transaction-specific loan (units: C_DECIMALS).
+     * @param _ltv The desired loan-to-value ratio for this transaction-specific loan (ex: 75 is 75%).
+     * @param _swapAmtOutMin The minimum amount of output tokens from swap for the tx to go through.
+     * @param _poolFee The fee of the Uniswap pool.
+     * @param _client The address, controlled by client operators, for receiving protocol fees (use address(0) if no client).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function shortWithPermit(
+        uint256 _cAmt,
+        uint256 _ltv,
+        uint256 _swapAmtOutMin,
+        uint24 _poolFee,
+        address _client,
+        uint256 _deadline,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    ) public payable onlyOwner {
+        // 1. Approve with permit
+        IERC20WithPermit(C_TOKEN).permit(msg.sender, address(this), _cAmt, _deadline, _v, _r, _s);
+
+        // 2. Short
+        short(_cAmt, _ltv, _swapAmtOutMin, _poolFee, _client);
+    }
+
     /**
      * @notice Fully closes the short position.
      * @param _poolFee The fee of the Uniswap pool.

src/interfaces/IPosition.sol

@@ -42,6 +42,30 @@ interface IPosition {
         external
         payable;
 
+    /**
+     * @notice Adds to this contract's short position with permit, obviating the need for a separate approve tx.
+     * @param _cAmt The amount of collateral to be supplied for this transaction-specific loan (units: C_DECIMALS).
+     * @param _ltv The desired loan-to-value ratio for this transaction-specific loan (ex: 75 is 75%).
+     * @param _swapAmtOutMin The minimum amount of output tokens from swap for the tx to go through.
+     * @param _poolFee The fee of the Uniswap pool.
+     * @param _client The address, controlled by client operators, for receiving protocol fees (use address(0) if no client).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function shortWithPermit(
+        uint256 _cAmt,
+        uint256 _ltv,
+        uint256 _swapAmtOutMin,
+        uint24 _poolFee,
+        address _client,
+        uint256 _deadline,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    ) external payable;
+
     /**
      * @notice Fully closes the short position.
      * @param _poolFee The fee of the Uniswap pool.
@@ -59,6 +83,18 @@ interface IPosition {
      */
     function addCollateral(uint256 _cAmt) external payable;
 
+    /**
+     * @notice Increases the collateral amount for this contract's loan with permit, obviating the need for a separate approve tx.
+     * @param _cAmt The amount of collateral to be supplied (units: C_DECIMALS).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function addCollateralWithPermit(uint256 _cAmt, uint256 _deadline, uint8 _v, bytes32 _r, bytes32 _s)
+        external
+        payable;
+
     /**
      * @notice Repays any outstanding debt to Aave and transfers remaining collateral from Aave to owner.
      * @param _dAmt The amount of debt token to repay to Aave (units: D_DECIMALS).
@@ -67,6 +103,26 @@ interface IPosition {
      */
     function repayAfterClose(uint256 _dAmt, uint256 _withdrawBuffer) external payable;
 
+    /**
+     * @notice Repays any outstanding debt to Aave and transfers remaining collateral from Aave to owner,
+     *         with permit, obviating the need for a separate approve tx.
+     * @param _dAmt The amount of debt token to repay to Aave (units: D_DECIMALS).
+     *              To pay off entire debt, _dAmt = debtOwed + smallBuffer (to account for interest).
+     * @param _withdrawBuffer The amount of collateral left as safety buffer for tx to go through (default = 100_000, units: 8 decimals).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function repayAfterCloseWithPermit(
+        uint256 _dAmt,
+        uint256 _withdrawBuffer,
+        uint256 _deadline,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    ) external payable;
+
     /* ****************************************************************************
     **
     **  ADMIN FUNCTIONS

src/interfaces/aave/IPool.sol

@@ -254,12 +254,12 @@ interface IPool {
      * @param onBehalfOf The address that will receive the aTokens, same as msg.sender if the user
      *   wants to receive them on his own wallet, or a different address if the beneficiary of aTokens
      *   is a different wallet
-     * @param deadline The deadline timestamp that the permit is valid
+     * @param deadline The deadline timestamp that the permit is valid.
      * @param referralCode Code used to register the integrator originating the operation, for potential rewards.
      *   0 if the action is executed directly by the user, without any middle-man
-     * @param permitV The V parameter of ERC712 permit sig
-     * @param permitR The R parameter of ERC712 permit sig
-     * @param permitS The S parameter of ERC712 permit sig
+     * @param permitV The V parameter of ERC712 permit signature.
+     * @param permitR The R parameter of ERC712 permit signature.
+     * @param permitS The S parameter of ERC712 permit signature.
      *
      */
     function supplyWithPermit(
@@ -333,10 +333,10 @@ interface IPool {
      * @param onBehalfOf Address of the user who will get his debt reduced/removed. Should be the address of the
      * user calling the function if he wants to reduce/remove his own debt, or the address of any other
      * other borrower whose debt should be removed
-     * @param deadline The deadline timestamp that the permit is valid
-     * @param permitV The V parameter of ERC712 permit sig
-     * @param permitR The R parameter of ERC712 permit sig
-     * @param permitS The S parameter of ERC712 permit sig
+     * @param deadline The deadline timestamp that the permit is valid.
+     * @param permitV The V parameter of ERC712 permit signature.
+     * @param permitR The R parameter of ERC712 permit signature.
+     * @param permitS The S parameter of ERC712 permit signature.
      * @return The final amount repaid
      *
      */

src/interfaces/token/IERC20Permit.sol

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Permit.sol)
+
+pragma solidity ^0.8.21;
+
+/**
+ * @dev Interface of the ERC-20 Permit extension allowing approvals to be made via signatures, as defined in
+ * https://eips.ethereum.org/EIPS/eip-2612[ERC-2612].
+ *
+ * Adds the {permit} method, which can be used to change an account's ERC-20 allowance (see {IERC20-allowance}) by
+ * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
+ * need to send a transaction, and thus is not required to hold Ether at all.
+ *
+ * ==== Security Considerations
+ *
+ * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
+ * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
+ * considered as an intention to spend the allowance in any specific way. The second is that because permits have
+ * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
+ * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
+ * generally recommended is:
+ *
+ * ```solidity
+ * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
+ *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
+ *     doThing(..., value);
+ * }
+ *
+ * function doThing(..., uint256 value) public {
+ *     token.safeTransferFrom(msg.sender, address(this), value);
+ *     ...
+ * }
+ * ```
+ *
+ * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
+ * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
+ * {SafeERC20-safeTransferFrom}).
+ *
+ * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
+ * contracts should have entry points that don't rely on permit.
+ */
+interface IERC20Permit {
+    /**
+     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
+     * given ``owner``'s signed approval.
+     *
+     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
+     * ordering also apply here.
+     *
+     * Emits an {Approval} event.
+     *
+     * Requirements:
+     *
+     * - `spender` cannot be the zero address.
+     * - `deadline` must be a timestamp in the future.
+     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
+     * over the EIP712-formatted function arguments.
+     * - the signature must use ``owner``'s current nonce (see {nonces}).
+     *
+     * For more information on the signature format, see the
+     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
+     * section].
+     *
+     * CAUTION: See Security Considerations above.
+     */
+    function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s)
+        external;
+
+    /**
+     * @dev Returns the current nonce for `owner`. This value must be
+     * included whenever a signature is generated for {permit}.
+     *
+     * Every successful call to {permit} increases ``owner``'s nonce by one. This
+     * prevents a signature from being used multiple times.
+     */
+    function nonces(address owner) external view returns (uint256);
+
+    /**
+     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
+     */
+    // solhint-disable-next-line func-name-mixedcase
+    function DOMAIN_SEPARATOR() external view returns (bytes32);
+}

src/services/DebtService.sol

@@ -6,6 +6,7 @@ import { PositionAdmin } from "src/PositionAdmin.sol";
 import { SafeTransferLib, ERC20 } from "solmate/utils/SafeTransferLib.sol";
 import { IPool } from "src/interfaces/aave/IPool.sol";
 import { IERC20 } from "src/interfaces/token/IERC20.sol";
+import { IERC20 } from "src/interfaces/token/IERC20.sol";
 import { IAaveOracle } from "src/interfaces/aave/IAaveOracle.sol";
 import { IERC20Metadata } from "src/interfaces/token/IERC20Metadata.sol";
 
@@ -125,6 +126,26 @@ contract DebtService is PositionAdmin {
         IPool(AAVE_POOL).supply(C_TOKEN, _cAmt, address(this), 0);
     }
 
+    /**
+     * @notice Increases the collateral amount for this contract's loan with permit, obviating the need for a separate approve tx.
+     * @param _cAmt The amount of collateral to be supplied (units: C_DECIMALS).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function addCollateralWithPermit(uint256 _cAmt, uint256 _deadline, uint8 _v, bytes32 _r, bytes32 _s)
+        public
+        payable
+        onlyOwner
+    {
+        // 1. Approve with permit
+        IERC20WithPermit(C_TOKEN).permit(msg.sender, address(this), _cAmt, _deadline, _v, _r, _s);
+
+        // 2. Add Collateral
+        addCollateral(_cAmt);
+    }
+
     /**
      * @notice Repays any outstanding debt to Aave and transfers remaining collateral from Aave to owner.
      * @param _dAmt The amount of debt token to repay to Aave (units: D_DECIMALS).
@@ -138,4 +159,30 @@ contract DebtService is PositionAdmin {
 
         _withdraw(OWNER, _withdrawBuffer);
     }
+
+    /**
+     * @notice Repays any outstanding debt to Aave and transfers remaining collateral from Aave to owner,
+     *         with permit, obviating the need for a separate approve tx.
+     * @param _dAmt The amount of debt token to repay to Aave (units: D_DECIMALS).
+     *              To pay off entire debt, _dAmt = debtOwed + smallBuffer (to account for interest).
+     * @param _withdrawBuffer The amount of collateral left as safety buffer for tx to go through (default = 100_000, units: 8 decimals).
+     * @param _deadline The deadline timestamp that the permit is valid.
+     * @param _v The V parameter of ERC712 permit signature.
+     * @param _r The R parameter of ERC712 permit signature.
+     * @param _s The S parameter of ERC712 permit signature.
+     */
+    function repayAfterCloseWithPermit(
+        uint256 _dAmt,
+        uint256 _withdrawBuffer,
+        uint256 _deadline,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    ) public payable onlyOwner {
+        // 1. Approve with permit
+        IERC20WithPermit(D_TOKEN).permit(msg.sender, address(this), _dAmt, _deadline, _v, _r, _s);
+
+        // 2. Repay
+        repayAfterClose(_dAmt, _withdrawBuffer);
+    }
 }