Working on new paymaster

contracts/paymaster/OpenfortPaymaster.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0
-pragma solidity ^0.8.17;
+pragma solidity ^0.8.19;
 
 import {ECDSA} from "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
 import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
@@ -10,9 +10,9 @@ import {BasePaymaster} from "account-abstraction/core/BasePaymaster.sol";
 import "account-abstraction/core/Helpers.sol" as Helpers;
 
 /**
- * A paymaster based on the eth-infinitism sample VerifyingPaymaster contract.
+ * A paymaster based on the eth-infinitism sample VerifyingPaymaster contract and Stackups.
  * It has the same functionality as the sample, but with added support for withdrawing ERC20 tokens.
- * All withdrawn tokens will be transferred to the owner address.
+ * All withdrawn tokens will be transferred to a designated address.
  * Note that the off-chain signer should have a strategy in place to handle a failed token withdrawal.
  *
  * See account-abstraction/contracts/samples/VerifyingPaymaster.sol for detailed comments.
@@ -22,8 +22,6 @@ contract OpenfortPaymaster is BasePaymaster {
     using UserOperationLib for UserOperation;
     using SafeERC20 for IERC20;
 
-    mapping(address => uint256) public senderNonce;
-
     uint256 private constant VALID_PND_OFFSET = 20; // length of an address
     uint256 private constant SIGNATURE_OFFSET = 148; // 48+48+20+32 = 148
     uint256 private constant POST_OP_GAS = 35000;
@@ -34,26 +32,12 @@ contract OpenfortPaymaster is BasePaymaster {
         _transferOwnership(_owner);
     }
 
-    function pack(UserOperation calldata userOp) internal pure returns (bytes memory ret) {
-        bytes calldata pnd = userOp.paymasterAndData;
-        // solhint-disable-next-line no-inline-assembly
-        assembly {
-            let ofs := userOp
-            let len := sub(sub(pnd.offset, ofs), 32)
-            ret := mload(0x40)
-            mstore(0x40, add(ret, add(len, 32)))
-            mstore(ret, len)
-            calldatacopy(add(ret, 32), ofs, len)
-        }
-    }
-
     /**
-     * Return the hash we're going to sign off-chain (and validate on-chain).
-     * This method is called by the off-chain service, to sign the request.
-     * It is called on-chain from the validatePaymasterUserOp, to validate the signature.
+     * Return the hash we're going to sign off-chain (and validate on-chain)
+     * this method is called by the off-chain service, to sign the request.
+     * it is called on-chain from the validatePaymasterUserOp, to validate the signature.
      * note that this signature covers all fields of the UserOperation, except the "paymasterAndData",
      * which will carry the signature itself.
-     * ERC-20 address and exchange rate added to support paying in ERC-20s
      */
     function getHash(
         UserOperation calldata userOp,
@@ -62,18 +46,21 @@ contract OpenfortPaymaster is BasePaymaster {
         address erc20Token,
         uint256 exchangeRate
     ) public view returns (bytes32) {
-        return keccak256(
-            abi.encode(
-                pack(userOp),
-                block.chainid,
-                address(this),
-                senderNonce[userOp.getSender()],
-                validUntil,
-                validAfter,
-                erc20Token,
-                exchangeRate
-            )
+        // Dividing the hashing in 2 parts due to the stack too deep error
+        bytes memory firstHalf = abi.encode(
+            userOp.getSender(),
+            userOp.nonce,
+            keccak256(userOp.initCode),
+            keccak256(userOp.callData),
+            userOp.callGasLimit,
+            userOp.verificationGasLimit,
+            userOp.preVerificationGas,
+            userOp.maxFeePerGas,
+            userOp.maxPriorityFeePerGas
         );
+        bytes memory secondHalf =
+            abi.encode(block.chainid, address(this), validUntil, validAfter, erc20Token, exchangeRate);
+        return keccak256(abi.encodePacked(firstHalf, secondHalf));
     }
 
     /**
@@ -83,13 +70,11 @@ contract OpenfortPaymaster is BasePaymaster {
      * paymasterAndData[20:148]: abi.encode(validUntil, validAfter, erc20Token, exchangeRate) // 48+48+20+32
      * paymasterAndData[SIGNATURE_OFFSET:]: signature
      */
-    function _validatePaymasterUserOp(UserOperation calldata userOp, bytes32, /*userOpHash*/ uint256 requiredPreFund)
-        internal
-        override
-        returns (bytes memory context, uint256 validationData)
-    {
-        (requiredPreFund);
-
+    function _validatePaymasterUserOp(
+        UserOperation calldata userOp,
+        bytes32, /*userOpHash*/
+        uint256 /*requiredPreFund*/
+    ) internal view override returns (bytes memory context, uint256 validationData) {
         (uint48 validUntil, uint48 validAfter, address erc20Token, uint256 exchangeRate, bytes calldata signature) =
             parsePaymasterAndData(userOp.paymasterAndData);
         // solhint-disable-next-line reason-string
@@ -98,16 +83,14 @@ contract OpenfortPaymaster is BasePaymaster {
             "VerifyingPaymaster: invalid signature length in paymasterAndData"
         );
         bytes32 hash = ECDSA.toEthSignedMessageHash(getHash(userOp, validUntil, validAfter, erc20Token, exchangeRate));
-        unchecked {
-            ++senderNonce[userOp.getSender()];
-        }
+
         context = "";
         if (erc20Token != address(0)) {
             context =
                 abi.encode(userOp.sender, erc20Token, exchangeRate, userOp.maxFeePerGas, userOp.maxPriorityFeePerGas);
         }
 
-        //don't revert on signature failure: return SIG_VALIDATION_FAILED
+        // don't revert on signature failure: return SIG_VALIDATION_FAILED
         if (owner() != ECDSA.recover(hash, signature)) {
             return (context, Helpers._packValidationData(true, validUntil, validAfter));
         }
@@ -118,7 +101,7 @@ contract OpenfortPaymaster is BasePaymaster {
     }
 
     /*
-     * If the everythig worked fine, transfer the right amount of tokens from the sender (SCW) to the owner of the Paymaster
+     * If everything worked fine, transfer the right amount of tokens from the sender (SCW) to the designated recipient
      */
     function _postOp(PostOpMode mode, bytes calldata context, uint256 actualGasCost) internal override {
         (address sender, IERC20 token, uint256 exchangeRate, uint256 maxFeePerGas, uint256 maxPriorityFeePerGas) =