nathan-websculpt’s gists

nathan-websculpt / RPSv2.sol

Last active October 20, 2021 12:07

Two Player Rock, Paper, Scissors in Solidity

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity ^0.8.0;
	import "../node_modules/@OpenZeppelin/contracts/utils/math/SafeMath.sol";
	import "../node_modules/@OpenZeppelin/contracts/security/ReentrancyGuard.sol";

	//for use in this blog post: https://medium.com/@websculpt/rock-paper-scissors-in-solidity-part-3-commit-reveal-4d56a84cbe97
	contract RPSv2 is ReentrancyGuard {
	using SafeMath for uint;

nathan-websculpt / rpsv1.sol

Created September 27, 2021 20:11

Very basic representation of Rock, Paper, Scissors logic on Solidity

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity ^0.8.0;
	import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v4.3/contracts/security/ReentrancyGuard.sol";

	//for testing/learning purposes only -- not production code
	contract rpsv1 is ReentrancyGuard{
	mapping (address => uint) public playerBalances;

	event Received(address, uint);

nathan-websculpt / StringTesting.sol

Created September 27, 2021 17:34

Compare and Concat strings in solidity

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;

	contract StringTesting {

	function stringCompare(string calldata _inputOne, string calldata _inputTwo) external pure returns (bool r) {

	bool rslt;

nathan-websculpt / EscrowExample.sol

Created September 24, 2021 19:42

Example usage of Escrow -- not production-ready -- for learning purposes only

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;

	import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v4.3/contracts/security/ReentrancyGuard.sol";
	import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v4.3/contracts/utils/escrow/Escrow.sol";

	contract EscrowExample is ReentrancyGuard {
	Escrow private immutable _escrow;

nathan-websculpt / OpenZeppelin_ReentrancyGuard.sol

Created September 22, 2021 18:03

Here is an example of the OpenZeppelin Reentrancy Guard in use

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;
	import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v4.3/contracts/security/ReentrancyGuard.sol";

	contract Attackee is ReentrancyGuard {

	mapping(address => uint) public attackeeBalances;

	function depositIntoAttackee() external payable {

nathan-websculpt / ReentrancyGuard_BlockedAttack.sol

Created September 22, 2021 15:55

This example shows a simple Reentrancy Guard in action. Even though the balance is not zero-ed out until after the call, this reentrancy guard stops the attacker's receive() from completing the attack. For learning purposes only.

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;


	contract ReentrancyGuard {
	bool private guardLocked;

	modifier noReentry() {
	require(!guardLocked, "Prevented by noReentry in ReentrancyGuard");

nathan-websculpt / ReentrancyGuard_simpleExample.sol

Last active September 24, 2021 20:40

This is an example Reentrancy Guard for teaching purposes

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;


	contract ReentrancyGuard {
	bool private guardLocked;

	modifier noReentry() {
	require(!guardLocked, "Prevented by noReentry in ReentrancyGuard");

nathan-websculpt / ReentrancyAttackFIX.sol

Created September 17, 2021 14:31

The fix for ReentrancyAttackExample.sol

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;

	contract Attackee {
	mapping(address => uint) public attackeeBalances;

	function depositIntoAttackee() external payable {
	attackeeBalances[msg.sender] += msg.value;
	}

nathan-websculpt / ReentrancyAttackExample.sol

Created September 16, 2021 15:11

Attacker.performAttack can drain Attackee in a reentrancy attack that utilizes the Attacker's fallback function

	// SPDX-License-Identifier: GPL-3.0

	pragma solidity >=0.7.0 <0.9.0;

	contract Attackee {
	mapping(address => uint) public attackeeBalances;

	function depositIntoAttackee() external payable {
	attackeeBalances[msg.sender] += msg.value;
	}

nathan-websculpt / AttackVulnerableWithdraw.sol

Created September 16, 2021 12:46

How to attack the VulnerableWithdraw.sol example

	//this is called when Attackee sends Ether to this contract (Attacker)
	fallback() external payable {
	if(address(contractToAttack).balance >= 1 ether) {
	contractToAttack.withdrawFromAttackee();
	}
	}

	function performAttack() external payable {
	require(msg.value >= 1 ether);
	contractToAttack.depositIntoAttackee{value: 1 ether}();

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