clarify denom definition and remove unnecessary validation for denom

Signed-off-by: Jun Kimura <[email protected]>

contracts/apps/20-transfer/ICS20Bank.sol

@@ -26,56 +26,59 @@ contract ICS20Bank is Context, AccessControl, IICS20Bank {
         _setupRole(OPERATOR_ROLE, operator);
     }
 
-    function balanceOf(address account, string calldata id) external view virtual returns (uint256) {
+    function balanceOf(address account, string calldata denom) external view virtual returns (uint256) {
         require(account != address(0), "ICS20Bank: balance query for the zero address");
-        return _balances[id][account];
+        return _balances[denom][account];
     }
 
-    function transferFrom(address from, address to, string calldata id, uint256 amount) external virtual override {
+    function transferFrom(address from, address to, string calldata denom, uint256 amount) external virtual override {
         require(to != address(0), "ICS20Bank: transfer to the zero address");
         require(
             from == _msgSender() || hasRole(OPERATOR_ROLE, _msgSender()), "ICS20Bank: caller is not owner nor approved"
         );
-
-        uint256 fromBalance = _balances[id][from];
+        uint256 fromBalance = _balances[denom][from];
         require(fromBalance >= amount, "ICS20Bank: insufficient balance for transfer");
-        _balances[id][from] = fromBalance - amount;
-        _balances[id][to] += amount;
+        unchecked {
+            _balances[denom][from] = fromBalance - amount;
+        }
+        _balances[denom][to] += amount;
     }
 
-    function mint(address account, string calldata id, uint256 amount) external virtual override {
+    function mint(address account, string calldata denom, uint256 amount) external virtual override {
         require(hasRole(OPERATOR_ROLE, _msgSender()), "ICS20Bank: must have minter role to mint");
-        _mint(account, id, amount);
+        _mint(account, denom, amount);
     }
 
-    function burn(address account, string calldata id, uint256 amount) external virtual override {
+    function burn(address account, string calldata denom, uint256 amount) external virtual override {
         require(hasRole(OPERATOR_ROLE, _msgSender()), "ICS20Bank: must have minter role to mint");
-        _burn(account, id, amount);
+        _burn(account, denom, amount);
+    }
+
+    function addressToDenom(address tokenContract) public pure virtual override returns (string memory) {
+        return Strings.toHexString(tokenContract);
     }
 
-    function deposit(address tokenContract, uint256 amount, address receiver) external virtual {
+    function deposit(address tokenContract, uint256 amount, address receiver) external virtual override {
         require(tokenContract.isContract());
         require(IERC20(tokenContract).transferFrom(_msgSender(), address(this), amount));
-        _mint(receiver, _genDenom(tokenContract), amount);
+        _mint(receiver, addressToDenom(tokenContract), amount);
     }
 
-    function withdraw(address tokenContract, uint256 amount, address receiver) external virtual {
+    function withdraw(address tokenContract, uint256 amount, address receiver) external virtual override {
         require(tokenContract.isContract());
-        _burn(_msgSender(), _genDenom(tokenContract), amount);
+        _burn(_msgSender(), addressToDenom(tokenContract), amount);
         require(IERC20(tokenContract).transfer(receiver, amount));
     }
 
-    function _mint(address account, string memory id, uint256 amount) internal virtual {
-        _balances[id][account] += amount;
+    function _mint(address account, string memory denom, uint256 amount) internal virtual {
+        _balances[denom][account] += amount;
     }
 
-    function _burn(address account, string memory id, uint256 amount) internal virtual {
-        uint256 accountBalance = _balances[id][account];
+    function _burn(address account, string memory denom, uint256 amount) internal virtual {
+        uint256 accountBalance = _balances[denom][account];
         require(accountBalance >= amount, "ICS20Bank: burn amount exceeds balance");
-        _balances[id][account] = accountBalance - amount;
-    }
-
-    function _genDenom(address tokenContract) internal pure virtual returns (string memory) {
-        return Strings.toHexString(tokenContract);
+        unchecked {
+            _balances[denom][account] = accountBalance - amount;
+        }
     }
 }

contracts/apps/20-transfer/ICS20Transfer.sol

@@ -38,15 +38,15 @@ abstract contract ICS20Transfer is IBCAppBase {
             );
         } else {
             // sender chain is the source, mint vouchers
+
+            // ensure denom is not required to be escaped
             if (ICS20Lib.isEscapeNeededString(denom)) {
                 success = false;
             } else {
                 success = _mint(
                     receiver,
                     string(
-                        abi.encodePacked(
-                            _getDenomPrefix(packet.destination_port, packet.destination_channel), data.denom
-                        )
+                        abi.encodePacked(_getDenomPrefix(packet.destination_port, packet.destination_channel), denom)
                     ),
                     data.amount
                 );

contracts/apps/20-transfer/ICS20TransferBank.sol

@@ -17,6 +17,15 @@ contract ICS20TransferBank is ICS20Transfer {
         bank = bank_;
     }
 
+    /**
+     * @dev sendTransfer sends a transfer packet to the destination chain.
+     * @param denom denomination of the token. It can assume the denom string is escaped or not required to be escaped.
+     * @param amount amount of the token
+     * @param receiver receiver address on the destination chain
+     * @param sourcePort source port of the packet
+     * @param sourceChannel source channel of the packet
+     * @param timeoutHeight timeout height of the packet
+     */
     function sendTransfer(
         string calldata denom,
         uint256 amount,
@@ -25,7 +34,7 @@ contract ICS20TransferBank is ICS20Transfer {
         string calldata sourceChannel,
         uint64 timeoutHeight
     ) external {
-        require(ICS20Lib.isEscapedJSONString(denom) && ICS20Lib.isEscapedJSONString(receiver), "unescaped string");
+        require(ICS20Lib.isEscapedJSONString(receiver), "unescaped receiver");
         bytes memory denomPrefix = _getDenomPrefix(sourcePort, sourceChannel);
         if (!bytes(denom).slice(0, denomPrefix.length).equal(denomPrefix)) {
             // sender is source chain

contracts/apps/20-transfer/IICS20Bank.sol

@@ -2,7 +2,57 @@
 pragma solidity ^0.8.9;
 
 interface IICS20Bank {
-    function transferFrom(address from, address to, string calldata id, uint256 amount) external;
-    function mint(address account, string calldata id, uint256 amount) external;
-    function burn(address account, string calldata id, uint256 amount) external;
+    /**
+     * @dev balanceOf returns the balance of the account.
+     * @param account account address
+     * @param denom denom of the token
+     */
+    function balanceOf(address account, string calldata denom) external view returns (uint256);
+
+    /**
+     * @dev transferFrom transfers tokens from the sender to the receiver.
+     * @param from sender address
+     * @param to receiver address
+     * @param denom denom of the token
+     * @param amount amount of the token
+     */
+    function transferFrom(address from, address to, string calldata denom, uint256 amount) external;
+
+    /**
+     * @dev mint mints tokens to the account.
+     * @param account account address
+     * @param denom denom of the token
+     * @param amount amount of the token
+     */
+    function mint(address account, string calldata denom, uint256 amount) external;
+
+    /**
+     * @dev burn burns tokens from the account.
+     * @param account account address
+     * @param denom denom of the token
+     * @param amount amount of the token
+     */
+    function burn(address account, string calldata denom, uint256 amount) external;
+
+    /**
+     * @dev addressToDenom returns the denom of the token corresponding to the contract address.
+     *      The denom must be a json escaped string.
+     */
+    function addressToDenom(address tokenContract) external pure returns (string memory);
+
+    /**
+     * @dev deposit deposits tokens to the bank.
+     * @param tokenContract token contract address
+     * @param amount amount of the token
+     * @param receiver receiver address on the bank
+     */
+    function deposit(address tokenContract, uint256 amount, address receiver) external;
+
+    /**
+     * @dev withdraw withdraws tokens from the bank.
+     * @param tokenContract token contract address
+     * @param amount amount of the token
+     * @param receiver receiver address on the bank
+     */
+    function withdraw(address tokenContract, uint256 amount, address receiver) external;
 }