pragma solidity ^0.4.24; contract IsContract { /* * NOTE: this should NEVER be used for authentication * (see pitfalls: https://github.com/fergarrui/ethereum-security/tree/master/contracts/extcodesize). * * This is only intended to be used as a sanity check that an address is actually a contract, * RATHER THAN an address not being a contract. */ function isContract(address _target) internal view returns (bool) { if (_target == address(0)) { return false; } uint256 size; assembly { size := extcodesize(_target) } return size > 0; } }