MiloTruck

How to understand Blast 101

OP Stack

How OP Stack works

• OP Stack Documentation
• Optimism Bedrock Specs, relevant parts are:
  • Introduction
• Overview

Philogy

#!/bin/python3
import sys
import pyperclip

def main():
    args = sys.argv
    if len(args) != 2:
        raise ValueError(f'Invalid argument count {len(args)} expected 2')

    word = args[1]

horsefacts

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

library Iterators {

    // Function types:
    // https://docs.soliditylang.org/en/latest/types.html#function-types
    function map(uint256[] memory input, function (uint256) internal pure returns (uint256) f)
        internal
        pure

noxx3xxon

import numpy as np
import cvxpy as cp
import itertools

# Problem data
global_indices = list(range(4))

# 0 = TOKEN-0
# 1 = TOKEN-1
# 2 = TOKEN-2

0xA5DF

Forge calculates gas as if each test is one tx

Sample code

When runing forge test -m testGas --gas-report -vv, it shows the cost of calling x is 261:

╭──────────────────────────────────┬─────────────────┬─────┬────────┬─────┬─────────╮
│ contracts/Gas.sol:Store contract ┆                 ┆     ┆        ┆     ┆         │
╞══════════════════════════════════╪═════════════════╪═════╪════════╪═════╪═════════╡
│ Deployment Cost                  ┆ Deployment Size ┆     ┆        ┆     ┆         │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤

leonardoalt

    function factorial_Yul_For(uint256 x) public pure returns(uint256){
        assembly{
            let result := 1
            for {} iszero(iszero(x)) { x := sub(x, 1)} {
                result := mul(result, x)
            }
            mstore(0,result)
            return(0,0x20)
        }
    }

Neo23x0

log4j RCE Exploitation Detection

You can use these commands and rules to search for exploitation attempts against log4j RCE vulnerability CVE-2021-44228

Grep / Zgrep

This command searches for exploitation attempts in uncompressed files in folder /var/log and all sub folders

sudo egrep -I -i -r '\$(\{|%7B)jndi:(ldap[s]?|rmi|dns|nis|iiop|corba|nds|http):/[^\n]+' /var/log

hrkrshnn

Upgrade to at least 0.8.4

Using newer compiler versions and the optimizer gives gas optimizations and additional safety checks for free!

The advantages of versions 0.8.* over <0.8.0 are:

• Safemath by default from 0.8.0 (can be more gas efficient than some library based safemath).
• Low level inliner from 0.8.2, leads to cheaper runtime gas. Especially relevant when the contract has small functions. For

patrickd-

Moved into a GitHub repository: cheatsheet.sol🔗

karmacoma-eth

Sending Ether Cheat Sheet

TLDR

🥇 Instead of sending Ether, use the withdrawal pattern

🥈 If you really need to send Ether, use a safe wrapper like OpenZeppelin's Address.sendValue(addr, amount)

🥉 If you really need to send Ether without dependencies, use (bool success, ) = addr.call{value: amount}("")