feat: perform all transfers in executors

For organization (and thus safety) purposes.

Rename to RestrictTransferFrom.sol so that we can perform multiple transfer froms (upto an allowance) in the case of split swaps (where the split is the first swap).

TODO: Fix tests.

foundry/src/RestrictTransferFrom.sol

@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: BUSL-1.1
+pragma solidity ^0.8.26;
+
+import "@interfaces/IExecutor.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@permit2/src/interfaces/IAllowanceTransfer.sol";
+
+error RestrictTransferFrom__AddressZero();
+error RestrictTransferFrom__ExceededTransferFromAllowance();
+error RestrictTransferFrom__UnknownTransferType();
+
+/**
+ * @title RestrictTransferFrom - Restrict transferFrom upto allowed amount of token
+ * @dev Restricts to one `transferFrom` (using `permit2` or regular `transferFrom`)
+ * per swap, while ensuring that the `transferFrom` is only performed on the input
+ * token upto input amount, from the msg.sender's wallet that calls the main swap
+ * method. Reverts if `transferFrom`s are attempted above this allowed amount.
+ */
+contract RestrictTransferFrom {
+    using SafeERC20 for IERC20;
+
+    IAllowanceTransfer public immutable permit2;
+    // keccak256("Dispatcher#TOKEN_IN_SLOT")
+    uint256 private constant _TOKEN_IN_SLOT =
+        0x66f353cfe8e3cbe0d03292348fbf0fca32e6e07fa0c2a52b4aac22193ac3b894;
+    // keccak256("Dispatcher#AMOUNT_ALLOWED_SLOT")
+    uint256 private constant _AMOUNT_ALLOWED_SLOT =
+        0xc76591aca92830b1554f3dcc7893e7519ec7c57bd4e64fec0c546d9078033291;
+    // keccak256("Dispatcher#IS_PERMIT2_SLOT")
+    uint256 private constant _IS_PERMIT2_SLOT =
+        0x3162c9d1175ca0ca7441f87984fdac41bbfdb13246f42c8bb4414d345da39e2a;
+    // keccak256("Dispatcher#SENDER_SLOT")
+    uint256 private constant _SENDER_SLOT =
+        0x5dcc7974be5cb30f183f878073999aaa6620995b9e052ab5a713071ff60ae9b5;
+    // keccak256("Dispatcher#AMOUNT_SPENT_SLOT")
+    uint256 private constant _AMOUNT_SPENT_SLOT =
+        0x56044a5eb3aa5bd3ad908b7f15d1e8cb830836bb4ad178a0bf08955c94c40d30;
+
+    constructor(address _permit2) {
+        if (_permit2 == address(0)) {
+            revert RestrictTransferFrom__AddressZero();
+        }
+        permit2 = IAllowanceTransfer(_permit2);
+    }
+
+    enum TransferType {
+        TransferFrom,
+        Transfer,
+        None
+    }
+
+    // slither-disable-next-line assembly
+    function _tstoreTransferFromInfo(
+        address tokenIn,
+        uint256 amountIn,
+        bool isPermit2
+    ) internal {
+        assembly {
+            tstore(_TOKEN_IN_SLOT, tokenIn)
+            tstore(_AMOUNT_IN_SLOT, amountIn)
+            tstore(_IS_PERMIT2_SLOT, isPermit2)
+            tstore(_SENDER_SLOT, caller())
+            tstore(_IS_TRANSFER_EXECUTED_SLOT, false)
+        }
+    }
+
+    // slither-disable-next-line assembly
+    function _transfer(
+        address receiver,
+        TransferType transferType,
+        address tokenIn,
+        uint256 amount
+    ) internal {
+        if (transferType == TransferType.TransferFrom){
+            bool isPermit2;
+            address sender;
+            bool isTransferExecuted;
+            assembly {
+                tokenIn := tload(_TOKEN_IN_SLOT)
+                amountPermitted := tload(_AMOUNT_IN_SLOT)
+                isPermit2 := tload(_IS_PERMIT2_SLOT)
+                sender := tload(_SENDER_SLOT)
+                amountSpent := tload(_IS_TRANSFER_EXECUTED_SLOT)
+            }
+            if (amount + amountSpent > amountPermitted) {
+                revert RestrictTransferFrom__ExceededTransferFromAllowance();
+            }
+            assembly {
+                tstore(_AMOUNT_SPENT_SLOT, amount)
+            }
+            if (isPermit2) {
+                // Permit2.permit is already called from the TychoRouter
+                permit2.transferFrom(sender, receiver, uint160(amount), tokenIn);
+            } else {
+                // slither-disable-next-line arbitrary-send-erc20
+                IERC20(tokenIn).safeTransferFrom(sender, receiver, amount);
+            }
+        } else if (transferType == TransferType.Transfer) {
+            if (tokenIn == address(0)) {
+                Address.sendValue(payable(receiver), amount);
+            } else {
+                IERC20(tokenIn).safeTransfer(receiver, amount);
+            }
+        } else if (transferType == TransferType.None) {
+            return;
+        } else {
+            revert RestrictTransferFrom__UnknownTransferType();
+        }
+    }
+}