基本环境配置

runwu2204 Lv6
  2024-11-22 23:15:58 2024-11-22 23:15:58 创建   2024-11-23 15:05:39 2024-11-23 15:05:39 更新    

instrumentation

Java探针技术-instrutment中retransformClasses和redefineClasses - 洛神灬殇 - 博客园

探秘 Java 热部署三（Java agent agentmain） - 莫那-鲁道 - 博客园

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jar包封装方式可参考封装jar包 | Runwu2204

premain

先于main执行

在MANIFEST中插入

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Premain-Class: xxx.xxx.xxx

对应类中需要带有

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public static void Agentmain(String agentArgs, Instrumentation inst)

调用方式

在-jar前面加入 -javaagent:xxx.jar

具体类似java -javaagent:agent.jar -jar main.jar(agent jar指对应带Agent-Class或者Premain-Class的jar包 而main.jar指的是对应带main 也就是需要被hook的jar包)

主要使用transform(相当于加载class前需要调用的函数)来实现加载对应class时调用修改函数

则需要加入

Can-Retransform-Classes: true Can-Redefine-Classes: true

否则会报unsupported

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Premain-Class: xxx.xxx.xxx
Can-Retransform-Classes: true
Can-Redefine-Classes: true

agentmain

在类加载后执行

在MANIFEST中插入

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Agent-Class: xxx.xxx.xxx

对应类中需要带有

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public static void agentmain(String agentArgs, Instrumentation instrumentation)

调用方式

使用

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VirtualMachine vm = VirtualMachine.attach("xxx");
vm.loadAgent("xxx.jar");//会调用里面注册好的agentmain方法

exp:

使用premain修改构造函数，添加新函数

AgentMainTest

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package org.example;
import javassist.*;

import java.lang.instrument.ClassDefinition;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;

public class AgentMainTest {
    static {

    }
    public static void premain(String agentArgs, Instrumentation instrumentation) throws Exception {
        System.out.println("开始代理 Agent");
        instrumentation.addTransformer(new Transformer(),true);

    }
    static class Transformer implements ClassFileTransformer{
        @Override
        public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
            if(className.contains("java/util/Date")){
                try{
                    System.out.println("IN:"+className);
                    ClassPool classPool=ClassPool.getDefault();
                    CtClass clazz=classPool.get("java.util.Date");
                    //动态添加test函数
                    CtMethod ctMethod = new CtMethod(CtClass.intType, "test", new CtClass[]{CtClass.intType}, clazz);
                    ctMethod.setModifiers(Modifier.PUBLIC);
                    ctMethod.setBody("{return $1;}");
                    clazz.addMethod(ctMethod);
                    //动态修改构造函数
                    CtConstructor ctConstructor=clazz.getDeclaredConstructor(new CtClass[]{});
                    ctConstructor.setBody("this(0L);");
                    return clazz.toBytecode();
                }catch (Exception e){
                    System.out.println("error:"+className);
                }
            }
            else{
                try{
                    //其他情况直接返回
                    ClassPool classPool=ClassPool.getDefault();
                    CtClass clazz=classPool.get(className);
                    return clazz.toBytecode();
                }catch (Exception e){

                }
            }
            return null;
        }
    }
}

Main

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package org.example;
import javassist.*;

import java.lang.instrument.Instrumentation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Date;

// Press Shift twice to open the Search Everywhere dialog and type `show whitespaces`,
// then press Enter. You can now see whitespace characters in your code.
public class Main {

    public static void main(String[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        Date dt=new Date();
        Method nmethod=Date.class.getDeclaredMethod("test",new Class[]{int.class});

        System.out.println(String.valueOf(dt));
        System.out.println(nmethod.invoke(dt,1));

        // Press Shift+F10 or click the green arrow button in the gutter to run the code.
    }
}

MANIFEST.MF

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Manifest-Version: 1.0
Can-Redefine-Classes: true
Premain-Class: org.example.AgentMainTest
Can-Retransform-Classes: true
Can-Redefine-Classes: true
Main-Class: org.example.Main
Class-Path: javassist-3.25.0-GA.jar

jar包结构

image-20241123023901306

运行结果

image-20241123023930393

使用agentmain动态补丁

注意需要导入对应版本java的lib下的tools.jar

image-20241123144439254

导入方式类似这样

image-20241123145025676

项目结构

image-20241123145311019

AgentMainTest

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//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package org.example;

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.CtMethod;

public class AgentMainTest {
    public AgentMainTest() {
    }

    public static void premain(String agentArgs, Instrumentation instrumentation) throws Exception {
        System.out.println("premain 开始代理 Agent");
        instrumentation.addTransformer(new Transformer(), true);
    }

    public static void agentmain(String agentArgs, Instrumentation instrumentation) throws Exception {
        System.out.println("agentmain 开始代理 Agent");
        instrumentation.addTransformer(new Transformer(), true);
    }

    static class Transformer implements ClassFileTransformer {
        Transformer() {
        }

        public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
            ClassPool classPool;
            CtClass clazz;
            if (className.contains("java/util/Date")) {
                try {
                    System.out.println("IN:" + className);
                    classPool = ClassPool.getDefault();
                    clazz = classPool.get("java.util.Date");
                    CtMethod ctMethod = new CtMethod(CtClass.intType, "test", new CtClass[]{CtClass.intType}, clazz);
                    ctMethod.setModifiers(1);
                    ctMethod.setBody("{return $1;}");
                    clazz.addMethod(ctMethod);
                    CtConstructor ctConstructor = clazz.getDeclaredConstructor(new CtClass[0]);
                    ctConstructor.setBody("this(0L);");
                    return clazz.toBytecode();
                } catch (Exception var10) {
                    System.out.println("error:" + className);
                }
            } else {
                try {
                    classPool = ClassPool.getDefault();
                    clazz = classPool.get(className);
                    return clazz.toBytecode();
                } catch (Exception var11) {
                }
            }

            return null;
        }
    }
}

Main

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package org.example;
import javassist.*;
import com.sun.tools.attach.*;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Date;

// Press Shift twice to open the Search Everywhere dialog and type `show whitespaces`,
// then press Enter. You can now see whitespace characters in your code.
public class Main {

    public static void main(String[] args) throws Exception {
        String name = ManagementFactory.getRuntimeMXBean().getName();//会获得pid@计算机id
        String Pid=name.split("@")[0];//获取pid
        // 使用VirtualMachine类来attach到当前进程
        VirtualMachine vm = VirtualMachine.attach(Pid);
        //加载agent
        vm.loadAgent("unnamed.jar");
        Date dt=new Date();
        Method nmethod=Date.class.getDeclaredMethod("test",new Class[]{int.class});
        System.out.println(String.valueOf(dt));
        System.out.println(nmethod.invoke(dt,1));
    }
}

MANIFEST.MF

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Manifest-Version: 1.0
Can-Redefine-Classes: true
Premain-Class: org.example.AgentMainTest
Agent-Class: org.example.AgentMainTest
Can-Retransform-Classes: true
Can-Redefine-Classes: true
Main-Class: org.example.Main
Class-Path: javassist-3.25.0-GA.jar tools.jar

Class-Path 注意路径就是当前路径的相对地址 此处我直接在unamed文件夹调用的所以直接用这个地址

image-20241123145338596

运行效果

image-20241123145551638

  • 标题: 基本环境配置
  • 作者: runwu2204
  • 创建于 : 2024-11-22 23:15:58
  • 更新于 : 2024-11-23 15:05:39
  • 链接: https://runwu2204.github.io/2024/11/22/开发/JAVA/JAVA-agent/基本环境配置/
  • 版权声明: 本文章采用 CC BY-NC-SA 4.0 进行许可。
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目录
基本环境配置
  1. instrumentation
    1. premain
    2. agentmain
  2. exp:
    1. 使用premain修改构造函数，添加新函数
    2. 使用agentmain动态补丁