fix(erc7683): EIP712 encoding (#506)

* fix eip712 encoding

* reduce duplicate code

---------

Co-authored-by: nicholaspai <9457025+nicholaspai@users.noreply.github.com>

Author: paco0x

contracts/erc7683/ERC7683Across.sol

@@ -49,13 +49,23 @@ library ERC7683Permit2Lib {
             "uint32 originChainId,",
             "uint32 initiateDeadline,",
             "uint32 fillDeadline,",
-            "AcrossOrderData orderData)",
-            ACROSS_ORDER_DATA_TYPE
+            "AcrossOrderData orderData)"
         );
-    bytes32 internal constant CROSS_CHAIN_ORDER_TYPE_HASH = keccak256(CROSS_CHAIN_ORDER_TYPE);
+
+    bytes internal constant CROSS_CHAIN_ORDER_EIP712_TYPE =
+        abi.encodePacked(CROSS_CHAIN_ORDER_TYPE, ACROSS_ORDER_DATA_TYPE);
+    bytes32 internal constant CROSS_CHAIN_ORDER_TYPE_HASH = keccak256(CROSS_CHAIN_ORDER_EIP712_TYPE);
+
     string private constant TOKEN_PERMISSIONS_TYPE = "TokenPermissions(address token,uint256 amount)";
     string internal constant PERMIT2_ORDER_TYPE =
-        string(abi.encodePacked("CrossChainOrder witness)", CROSS_CHAIN_ORDER_TYPE, TOKEN_PERMISSIONS_TYPE));
+        string(
+            abi.encodePacked(
+                "CrossChainOrder witness)",
+                ACROSS_ORDER_DATA_TYPE,
+                CROSS_CHAIN_ORDER_TYPE,
+                TOKEN_PERMISSIONS_TYPE
+            )
+        );
 
     // Hashes an order to get an order hash. Needed for permit2.
     function hashOrder(CrossChainOrder memory order, bytes32 orderDataHash) internal pure returns (bytes32) {