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原创 DogeKing合约，分红DOGE，SHIB

现在我来分析一下这个DodeKing的源码。主要两个合约BABYTOKEN，BABYTOKENDividendTrackerBABYTOKEN我们来分析下它的构造函数 name_ 合约代币名称，symbol_合约代币符号，totalSupply_合约代币总量，addrs数组存放四个地址，地址1：要奖励的代币合约地址，地址2：swap路由，地址3：market钱包，地址4：分发分红合约地址，feeSettings数组存放3个参数，参数1：分红比，

2022-02-14 16:16:12 3508 18

原创区块链+公链+区块浏览器+钱包APP

钱包APP先看截图区块浏览器浏览器地址http://120.53.106.253/#/EOS公链搭建一 .准备1. eosio账户公钥写死在代码中，在代码根目录 CMakeList.txt里面，找到 EOSIO_ROOT_KEY，改为自己创建的公钥。并把新的密钥对要在 config.ini文件中保存，见文件中 “signature-provider = 。。。”。 2.编译，安装，参加本人另一篇EOS编译文章...

2020-12-31 15:53:54 7124 1

原创 Bypass Contract Size Check

VulnerabilityIf an address is a contract then the size of code stored at the address will be greater than 0 right?Let's see how we can create a contract with code size returned byextcodesizeequal to 0.// SPDX-License-Identifier: MITpragma solidit..

2022-02-12 11:45:00 297

原创 Signature Replay

Signing messages off-chain and having a contract that requires that signature before executing a function is a useful technique.For example this technique is used to:reduce number of transaction on chain gas-less transaction, calledmeta transactionV.

2022-02-12 00:15:00 330

原创 Block Timestamp Manipulation

Vulnerabilityblock.timestampcan be manipulated by miners with the following constraintsit cannot be stamped with an earlier time than its parent it cannot be too far in the future// SPDX-License-Identifier: MITpragma solidity ^0.8.10;/*Roulette.

2022-02-11 20:15:00 512

原创 Honeypot

A honeypot is a trap to catch hackers.VulnerabilityCombining two exploits, reentrancy and hiding malicious code, we can build a contractthat will catch malicious users.// SPDX-License-Identifier: MITpragma solidity ^0.8.10;/*Bank is a contract

2022-02-11 16:45:00 1484

原创 Front Running

VulnerabilityTransactions take some time before they are mined. An attacker can watch the transaction pool and send a transaction, have it included in a block before the original transaction. This mechanism can be abused to re-order transactions to the a

2022-02-11 10:15:00 336

原创 Hiding Malicious Code with External Contract

VulnerabilityIn Solidity any address can be casted into specific contract, even if the contract at the address is not the one being casted.This can be exploited to hide malicious code. Let's see how.// SPDX-License-Identifier: MITpragma solidity ^0

2022-02-11 00:15:00 232

原创 Phishing with tx.origin

What's the difference betweenmsg.senderandtx.origin?If contract A calls B, and B calls C, in Cmsg.senderis B andtx.originis A.VulnerabilityA malicious contract can deceive the owner of a contract into calling a function that only the owner sho...

2022-02-10 11:15:00 188

原创 Denial of Service

VulnerabilityThere are many ways to attack a smart contract to make it unusable.One exploit we introduce here is denial of service by making the function to send Ether fail.// SPDX-License-Identifier: MITpragma solidity ^0.8.10;/*The goal of Kin

2022-02-10 00:30:00 265

原创 Source of Randomness

Vulnerabilityblockhashandblock.timestampare not reliable sources for randomness.// SPDX-License-Identifier: MITpragma solidity ^0.8.10;/*NOTE: cannot use blockhash in Remix so use ganache-clinpm i -g ganache-cliganache-cliIn remix switch en...

2022-02-09 14:45:00 192

原创 Delegatecall

Vulnerabilitydelegatecallis tricky to use and wrong usage or incorrect understanding can lead to devastating results.You must keep 2 things in mind when usingdelegatecalldelegatecallpreserves context (storage, caller, etc...) storage layout must ...

2022-02-09 12:00:00 425

原创 Self Destruct

Contracts can be deleted from the blockchain by callingselfdestruct.selfdestructsends all remaining Ether stored in the contract to a designated address.VulnerabilityA malicious contract can useselfdestructto force sending Ether to any contract....

2022-02-09 10:00:00 463 1

原创 Arithmetic Overflow and Underflow

VulnerabilitySolidity < 0.8Integers in Solidity overflow / underflow without any errorsSolidity >= 0.8Default behaviour of Solidity 0.8 for overflow / underflow is to throw an error.// SPDX-License-Identifier: MITpragma solidity ^0.7.6;

2022-02-08 19:00:00 426

原创 Accessing Private Data

VulnerabilityAll data on a smart contract can be read.Let's see how we can readprivatedata. In the process you will learn how Solidity stores state variables.// SPDX-License-Identifier: MITpragma solidity ^0.8.10;/*Note: cannot use web3 on JVM..

2022-02-08 15:02:04 293

原创 Re-Entrancy

Hacks Re-Entrancy

2022-02-08 14:50:16 317

原创去中心化交易系统开发

准备Uniswap合约源码https://download.youkuaiyun.com/download/yanning1314/12890659核心合约周边合约前端代码在Uniswap的核心代码中,主要包含3个合约:工厂合约,配对合约,ERC20合约.其中配对合约继承了ERC20合约,我们可以把它们看作一个合约.工厂合约通过create2方法部署配对合约,所以在部署合约时只需要部署工厂合约.周边合约中包括一些示例代码,例如价格预言机,闪电交换,其中最重要的是路由合约.在周边合约的代码库中,包含两个路由合

2020-09-29 08:45:38 1945 1

原创 Map与List的遍历速度比较

Map<String, Object> map = new HashMap<String, Object>(); List<String> list = new ArrayList<>(); for (int i = 0; i < 9999999; i++) { map.put(String.valueOf(i...

2018-12-27 15:00:33 11009 1

原创 JDK8 日期转换工具

package com.common.util;import java.time.Instant;import java.time.LocalDate;import java.time.LocalDateTime;import java.time.LocalTime;import java.time.Period;import java.time.ZoneId;import ja...

2018-11-21 18:01:05 1270

原创 jmmert聚合测试报告

springboot项目测试，单机测试服务器配置聚合测试报告聚合报告：Aggregate ReportLabel：请求名，request。#Samples：发出请求数量。模拟用户Average：平均响应时间（单位：）。默认是单个Request的平均响应时间。Median：50%用户的响应时间。90%Line：90%用户的响应时间。95%Line：95%用...

2018-11-21 17:56:24 304

原创 mybatis中特殊SQL的几种配置方法

1.in条件for循环 select booking_no, max(booking_general_seq) max_seq from interface_booking_t where booking_no in #{item} group by booking_no 2.insert并且返回主键 SELECT MLISP_DOC

2016-04-29 09:37:40 2393

原创 java 定时器

public static void executeTask(){ Timer timer = new Timer(); Calendar calendar = Calendar.getInstance(); int year = calendar.get(Calendar.YEAR); int month = calendar.get(Calendar.MONTH); int

2014-09-09 16:48:19 486

原创 java下载excel

public void doExport_asRunLog(){ try { String date = getParameter("date");// JSONArray ja = as.getAsRunLogByDateList(date);// String[] title = {"actual_on_air_date","hard_start_flag","actua

2014-05-19 10:06:56 8792

原创一个公用的dao类和util

daoimport java.io.Serializable;import java.lang.reflect.Field;import java.sql.CallableStatement;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java

2014-05-05 14:16:33 1788

原创一个公用的struts2基础action类

import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.struts2.interceptor.ServletRequestAware;import o

2014-05-05 14:15:58 666

原创 Extjs4实例地址和中文文档地址

Extjs4例子

2014-05-05 14:15:14 1562

原创 java上传文件

package com.yanning.action;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;public class Test { public

2014-03-31 16:18:22 882

原创 java 其他文件转成pdf java生成pdf

java生成pdf需要用到的包pd4ml.jar下载地址：http://download.youkuaiyun.com/detail/yanning1314/7124741package com.cular.util;import java.awt.Dimension;import java.awt.Insets;import java.io.ByteArrayOutputStream;im

2014-03-31 15:03:08 20898 3

转载日期处理bean

import java.text.ParsePosition;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;import java.util.GregorianCalendar;import java.util.regex.Pattern;import

2013-07-11 17:33:46 715

原创 java修改读取properties配置文件中的内容

java修改properties配置文件中的内容 /** * 修改properties配置文件中data_time的值 * @param bigtime 开始时间 * @param endtime 结束时间 * @throws IOException */ public static void getProperties(String bigtime,String e

2013-03-07 16:28:25 3387

原创 java对日期时间的增减

import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class Util { static SimpleDateFormat sdf = new SimpleDateFormat("YYYY-mm-

2013-01-25 13:57:19 5804

原创 java代码模拟页面上传文件至服务器（支持https上传）

先下载httpclient.jar，包括code.jar。下载地址：http://download.youkuaiyun.com/detail/yanning1314/4853021https上传需要下载 commons-io-2.2.jar 下载地址：http://download.youkuaiyun.com/detail/yanning1314/4856933import java.io

2012-12-06 14:05:44 1474

原创 java多个pdf合成一个pdf

先下载pdfbox-app-1.7.1.jar包。下载地址：http://download.youkuaiyun.com/detail/yanning1314/4852276import java.io.File;import java.io.IOException;import org.apache.pdfbox.util.PDFMergerUtility;public class t

2012-12-06 10:18:28 16049 3

原创读取写入文件内容

读取文件内容private String getEmailBody(String lang, String mobile, String refnumber){ ClassLoader cl; String str = ""; InputStream is = null; BufferedReade

2012-12-05 17:54:18 743

原创 java jdom解析和创建xml

先下载jdom.jar包 http://download.youkuaiyun.com/detail/yanning1314/4850186创建xml保存到本地import java.io.FileOutputStream; import java.io.IOException; import java.util.ArrayList;import java.util.List

2012-12-05 17:25:51 738

原创 java连接数据库

配置文件 DBManager.properties#sql server 2000数据库连接driverName=com.microsoft.jdbc.sqlserver.SQLServerDriverdbURL=jdbc\:microsoft\:sqlserver\://10.10.10.80\:1433; DatabaseName\=IST;SelectMethod\=Curs

2012-12-05 17:13:34 677