add transfer Helper

plugin/dapp/cross2eth/contracts/contracts4eth/BridgeBank/BridgeBank.sol

@@ -2,9 +2,11 @@ pragma solidity ^0.5.0;
 
 import "./Chain33Bank.sol";
 import "./EthereumBank.sol";
+import "./TransferHelper.sol";
 import "../Oracle.sol";
 import "../Chain33Bridge.sol";
 
+
 /**
  * @title BridgeBank
  * @dev Bank contract which coordinates asset-related functionality.
@@ -257,12 +259,9 @@ contract BridgeBank is Chain33Bank, EthereumBank {
           symbol = platformTokenSymbol;
           // ERC20 deposit
         } else {
-            require(
-                BridgeToken(_token).transferFrom(msg.sender, address(this), _amount),
-                "Contract token allowances insufficient to complete this lock request"
-            );
-            // Set symbol to the ERC20 token's symbol
-            symbol = BridgeToken(_token).symbol();
+
+            TransferHelper.safeTransferFrom(_token, msg.sender, address(this), _amount);
+            symbol = tokenAddrAllow2symbol[_token];
 
             require(
                 tokenAllow2Lock[keccak256(abi.encodePacked(symbol))] == _token,

plugin/dapp/cross2eth/contracts/contracts4eth/BridgeBank/EthereumBank.sol

@@ -2,6 +2,7 @@ pragma solidity ^0.5.0;
 
 import "../../openzeppelin-solidity/contracts/math/SafeMath.sol";
 import "./BridgeToken.sol";
+import "./TransferHelper.sol";
 
   /*
    *  @title: EthereumBank
@@ -16,6 +17,7 @@ contract EthereumBank {
     address payable public offlineSave;
     mapping(address => uint256) public lockedFunds;
     mapping(bytes32 => address) public tokenAllow2Lock;
+    mapping(address => string) public tokenAddrAllow2symbol;
     mapping(address => OfflineSaveCfg) public offlineSaveCfgs;
     uint8 public lowThreshold  = 5;
     uint8 public highThreshold = 80;
@@ -153,7 +155,7 @@ contract EthereumBank {
         if (address(0) == _token) {
             offlineSave.transfer(amount);
         } else {
-            require(BridgeToken(_token).transfer(offlineSave, amount), "Erc20 Token Transfer to offline Save account failed");
+            TransferHelper.safeTransfer(_token, offlineSave, amount);
         }
         return;
     }
@@ -182,10 +184,7 @@ contract EthereumBank {
         if (_token == address(0)) {
           _recipient.transfer(_amount);
         } else {
-            require(
-                BridgeToken(_token).transfer(_recipient, _amount),
-                "Token transfer failed"
-            );
+            TransferHelper.safeTransfer(_token, _recipient, _amount);
         }
 
         emit LogUnlock(
@@ -213,6 +212,7 @@ contract EthereumBank {
          address tokenQuery = tokenAllow2Lock[symHash];
          require(tokenQuery == address(0), 'The token with the same symbol has been added to lock allow list already.');
          tokenAllow2Lock[symHash] = _token;
+         tokenAddrAllow2symbol[_token] = _symbol;
      }
 
      /*

plugin/dapp/cross2eth/contracts/contracts4eth/BridgeBank/TransferHelper.sol

+pragma solidity ^0.5.0;
+
+// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
+library TransferHelper {
+    function safeApprove(address token, address to, uint value) internal {
+        // bytes4(keccak256(bytes('approve(address,uint256)')));
+        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
+        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
+    }
+
+    function safeTransfer(address token, address to, uint value) internal {
+        // bytes4(keccak256(bytes('transfer(address,uint256)')));
+        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
+        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
+    }
+
+    function safeTransferFrom(address token, address from, address to, uint value) internal {
+        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
+        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
+        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
+    }
+
+//    function safeTransferETH(address to, uint value) internal {
+//        (bool success,) = to.call{value:value}(new bytes(0));
+//        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
+//    }
+}
+
+//var ERC20FuncSigs = map[string]string{
+//"dd62ed3e": "allowance(address,address)",
+//"095ea7b3": "approve(address,uint256)",
+//"70a08231": "balanceOf(address)",
+//"313ce567": "decimals()",
+//"a457c2d7": "decreaseAllowance(address,uint256)",
+//"39509351": "increaseAllowance(address,uint256)",
+//"06fdde03": "name()",
+//"95d89b41": "symbol()",
+//"18160ddd": "totalSupply()",
+//"a9059cbb": "transfer(address,uint256)",
+//"23b872dd": "transferFrom(address,address,uint256)",
+//}