feat: approval support - fungible (#195)

Signed-off-by: Mariusz Jasuwienas <[email protected]>
hashgraph · Jan 24, 2025 · 5253aaa · 5253aaa
1 parent efd8eac
commit 5253aaa
Showing 1 changed file with 61 additions and 27 deletions.
diff --git a/contracts/HtsSystemContract.sol b/contracts/HtsSystemContract.sol
@@ -45,9 +45,13 @@ contract HtsSystemContract is IHederaTokenService, IERC20Events, IERC721Events {
 
     function cryptoTransfer(TransferList memory transferList, TokenTransferList[] memory tokenTransfers)
         htsCall external returns (int64 responseCode) {
-        _cryptoHbarTransfers(transferList);
+        _cryptoHbarTransfers(transferList.transfers);
         for (uint256 tokenIndex = 0; tokenIndex < tokenTransfers.length; tokenIndex++) {
-            require(tokenTransfers[tokenIndex].token != address(0), "cryptoTransfer: invalid token");
+            _cryptoFungibleTransfers(
+                tokenTransfers[tokenIndex].token,
+                tokenTransfers[tokenIndex].transfers
+            );
+
             uint256 validFungibleTransfersCount = 0;
             for (uint256 ftIndex = 0; ftIndex < tokenTransfers[tokenIndex].transfers.length; ftIndex++) {
                 if (!tokenTransfers[tokenIndex].transfers[ftIndex].isApproval) {
@@ -927,36 +931,66 @@ contract HtsSystemContract is IHederaTokenService, IERC20Events, IERC721Events {
         emit ApprovalForAll(sender, operator, approved);
     }
 
-    function _cryptoHbarTransfers(TransferList memory transferList) internal {
-        int64 hbarBalance = 0;
-        for (uint256 i = 0; i < transferList.transfers.length; i++) {
-            hbarBalance += transferList.transfers[i].amount;
-            if (transferList.transfers[i].amount < 0) {
-                require(
-                    transferList.transfers[i].isApproval || transferList.transfers[i].accountID == msg.sender,
-                    "cryptoTransfer: invalid sender account"
+    function _cryptoHbarTransfers(AccountAmount[] memory transfers) internal {
+        _checkCryptoFungibleTransfers(address(0), transfers);
+        for (uint256 i = 0; i < transfers.length; i++) {
+            address account = transfers[i].isApproval ? transfers[i].accountID : msg.sender;
+            bool from = transfers[i].amount < 0;
+            uint256 amount = uint256(uint64(from ? -transfers[i].amount : transfers[i].amount));
+            _updateHbarBalanceOnAccount(account, from ? account.balance - amount : account.balance + amount);
+            if (from && account != msg.sender) _approve(from, msg.sender, allowance - amount);
+        }
+    }
+
+    function _cryptoFungibleTransfers(address token, AccountAmount[] memory transfers) internal {
+        require(token != address(0), "cryptoTransfer: invalid token");
+        _checkCryptoFungibleTransfers(token, transfers);
+        for (uint256 from = 0; from < transfers.length; from++) {
+            if (transfers[from].amount <= 0) {
+                continue;
+            }
+            for (uint256 to = 0; to < transfers.length; to++) {
+                if (transfers[to].amount <= 0) {
+                    continue;
+                }
+                int64 transferAmount = transfers[to].amount < -transfers[from].amount ? transfers[to].amount : -transfers[from].amount;
+                transferToken(
+                    token,
+                    transfers[from].accountID,
+                    transfers[to].accountID,
+                    transferAmount
                 );
-                address from = transferList.transfers[i].isApproval ? transferList.transfers[i].accountID : msg.sender;
-                uint256 fromAmount = uint256(uint64(-transferList.transfers[i].amount));
-                require(fromAmount >= from.balance, "cryptoTransfer: insufficient balance");
-                uint256 allowance = 0;
-                if (msg.sender != from) {
-                    allowance = __allowance(transferList.transfers[i].accountID, msg.sender);
-                    require(allowance >= fromAmount, "cryptoTransfer: insufficient allowance");
+                transfers[from].amount += transferAmount;
+                transfers[to].amount -= transferAmount;
+                if (transfers[from].amount == 0) {
+                    break;
                 }
-                _updateHbarBalanceOnAccount(from, from.balance - fromAmount);
-                if (allowance > 0) _approve(from, msg.sender, allowance - fromAmount);
             }
-            if (transferList.transfers[i].amount > 0) {
-                uint256 toAmount = uint256(uint64(transferList.transfers[i].amount));
-                _updateHbarBalanceOnAccount(
-                    transferList.transfers[i].accountID,
-                    transferList.transfers[i].accountID.balance + toAmount
-                );
+        }
+    }
+
+    function _checkCryptoFungibleTransfers(address token, AccountAmount[] memory transfers) internal {
+        int64 total = 0;
+        mapping(address => int64) spends;
+        for (uint256 i = 0; i < transfers.length; i++) {
+            require(transfers[i].amount != 0, "cryptoTransfer: invalid amount");
+            total += transfers[i].amount;
+            if (transfers[i] > 0) {
+                continue;
+            }
+            spends[transfers[i].accountID] -= transfers[i].amount;
+            bool isApproval = transfers[i].accountID != msg.sender;
+            require(transfers[i].isApproval == isApproval, "cryptoTransfer: not allowed");
+            require(!isApproval || transfers[i].amount < 0, "cryptoTransfer: is approval option can only be used in the from part of the transaction");
+            if (isApproval) {
+                uint256 allowance = token == address(0) ?
+                    __allowance(transfers[i].accountID, msg.sender) :
+                    IERC20(token).allowance(transfers[i].accountID, msg.sender);
+                require(allowance >= spends[transfers[i].accountID], "cryptoTransfer: insufficient allowance");
             }
-            revert("cryptoTransfer: invalid amount");
+            require(spends[transfers[i].accountID] <= transfers[i].accountID.balance, "cryptoTransfer: insufficient balance");
         }
-        require(hbarBalance == 0, "cryptoTransfer: unmatched hbar transfers ");
+        require(total == 0, "cryptoTransfer: total amount must balance");
     }
 
     function _updateHbarBalanceOnAccount(address account, uint256 newBalance) internal virtual {