thanks again shark0der

Author: yakuhito

README.md

@@ -6,25 +6,25 @@ Gas consumption (estimate):
 ·------------------------------|---------------------------|-------------|-----------------------------·
 |     Solc version: 0.8.7      ·  Optimizer enabled: true  ·  Runs: 200  ·  Block limit: 30000000 gas  │
 ·······························|···························|·············|······························
-|  Methods                     ·              100 gwei/gas               ·       3417.01 usd/eth       │
+|  Methods                     ·              100 gwei/gas               ·       3406.79 usd/eth       │
 ··············|················|·············|·············|·············|···············|··············
 |  Contract   ·  Method        ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
 ··············|················|·············|·············|·············|···············|··············
-|  TestToken  ·  approve       ·      46239  ·      46251  ·      46250  ·           12  ·      15.80  │
+|  TestToken  ·  approve       ·      46239  ·      46251  ·      46250  ·           12  ·      15.76  │
 ··············|················|·············|·············|·············|···············|··············
-|  YakuSwap   ·  cancelSwap    ·          -  ·          -  ·      40105  ·            2  ·      13.70  │
+|  YakuSwap   ·  cancelSwap    ·          -  ·          -  ·      41126  ·            2  ·      14.01  │
 ··············|················|·············|·············|·············|···············|··············
-|  YakuSwap   ·  completeSwap  ·      86298  ·      86310  ·      86306  ·            6  ·      29.49  │
+|  YakuSwap   ·  completeSwap  ·      87304  ·      87316  ·      87312  ·            6  ·      29.75  │
 ··············|················|·············|·············|·············|···············|··············
-|  YakuSwap   ·  createSwap    ·      84508  ·      84520  ·      84519  ·           24  ·      28.88  │
+|  YakuSwap   ·  createSwap    ·      85628  ·      85640  ·      85639  ·           24  ·      29.18  │
 ··············|················|·············|·············|·············|···············|··············
-|  YakuSwap   ·  withdrawFees  ·      36483  ·      52383  ·      47083  ·            3  ·      16.09  │
+|  YakuSwap   ·  withdrawFees  ·      37507  ·      53407  ·      48107  ·            3  ·      16.39  │
 ··············|················|·············|·············|·············|···············|··············
 |  Deployments                 ·                                         ·  % of limit   ·             │
 ·······························|·············|·············|·············|···············|··············
-|  TestToken                   ·          -  ·          -  ·     641308  ·        2.1 %  ·     219.14  │
+|  TestToken                   ·          -  ·          -  ·     641308  ·        2.1 %  ·     218.48  │
 ·······························|·············|·············|·············|···············|··············
-|  YakuSwap                    ·          -  ·          -  ·     902396  ·          3 %  ·     308.35  │
+|  YakuSwap                    ·          -  ·          -  ·     932806  ·        3.1 %  ·     317.79  │
 ·------------------------------|-------------|-------------|-------------|---------------|-------------·
 ```
 

contracts/YakuSwap.sol

@@ -2,13 +2,11 @@
 pragma solidity ^0.8.0;
 
 import "@openzeppelin/contracts/access/Ownable.sol";
-
-interface IERC20 {
-  function transferFrom(address _from, address _to, uint256 _amount) external returns (bool);
-  function transfer(address _to, uint256 _amount) external returns (bool);
-}
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 
 contract YakuSwap is Ownable {
+  using SafeERC20 for IERC20;
 
   // Uninitialized - Default status (if swaps[index] doesn't exist, status will get this value)
   // Created - the swap was created, but the mone is still in the contract
@@ -79,7 +77,7 @@ contract YakuSwap is Ownable {
     );
 
     require(swaps[swapHash] == SwapStatus.Uninitialized, "Invalid swap status");
-    require(IERC20(tokenAddress).transferFrom(msg.sender, address(this), amount), "Could not transfer tokens");
+    IERC20(tokenAddress).safeTransferFrom(msg.sender, address(this), amount);
 
     swaps[swapHash] = SwapStatus.Created;
     emit SwapCreated(
@@ -118,7 +116,7 @@ contract YakuSwap is Ownable {
     uint swapAmount = amount * 993 / 1000;
     totalFees[tokenAddress] += amount - swapAmount;
 
-    require(IERC20(tokenAddress).transfer(toAddress, swapAmount), "Transfer failed");
+    IERC20(tokenAddress).safeTransfer(toAddress, swapAmount);
   }
 
   function cancelSwap(
@@ -141,13 +139,13 @@ contract YakuSwap is Ownable {
     require(block.number >= blockNumber + MAX_BLOCK_HEIGHT, "MAX_BLOCK_HEIGHT not exceeded");
 
     swaps[swapHash] = SwapStatus.Cancelled;
-    require(IERC20(tokenAddress).transfer(msg.sender, amount), "Transfer failed");
+    IERC20(tokenAddress).safeTransfer(msg.sender, amount);
   }
 
   function withdrawFees(address tokenAddress) external onlyOwner {
     uint feesToWithdraw = totalFees[tokenAddress];
     totalFees[tokenAddress] = 0;
 
-    require(IERC20(tokenAddress).transfer(msg.sender, feesToWithdraw), "Transfer failed");
+    IERC20(tokenAddress).safeTransfer(msg.sender, feesToWithdraw);
   }
 }