基于dalvik模式下的Xposed Hook开发的某加固脱壳工具

本文博客地址：http://blog.csdn.net/qq1084283172/article/details/77966109

这段时间好好的学习了一下Android加固相关的知识和流程也大致把Android加固的一些思路理清楚了，不巧在博客上看到了这篇文章《某加固使用xposed脱壳》感觉还不错，正好有时间可以学习一下这款基于Xposed Hook框架开发的某加固脱壳工具，原作者的博客已经找不到但是作者已经给出了主要的实现代码，我在作者给出的原代码基础上稍微做了一下修改和优化并且在Android Nexus 5手机上测试某加固的脱壳，成功得到了某加固解密后的dex文件。在进行源码分析之前，你需要了解Xposed Hook框架模块编写相关的知识，还不了解的可以先看下我前面的博客《Xposed框架之函数Hook学习》。Android加固的实现是基于DexClassLoader的加载流程来实现的，具体详细的流程后面有时间再整理一下，因此这里使用Xposed Hook框架来脱某加固壳的工具也是基于DexClassLoader的加载流程来实现的。

下图是DexClassLoader在整个java层的实现流程：

从DexClassLoader到openDexFileNative函数的整个流程下来，DexClassLoader的java层实现全部完成，openDexFileNative之后是由native层函数实现，暂时不关心；dex文件的加固是基于DexClassLoader的加载流程而来的，dex文件优化为odex文件后加载到apk进程的内存中返回是mCookie值，这个mCookie值就是dex文件加载到内存之后的镜像描述结构体指针DexOrJar* ，DexOrJar结构体的实现如下图所示：

http://androidxref.com/4.4.4_r1/xref/dalvik/vm/native/dalvik_system_DexFile.cpp#DexOrJar

/*
 * Internal struct for managing DexFile.
 */
struct DexOrJar {
	
	// 描述的dex文件或者jar文件的路径
    char*       fileName;
	// 是否是dex文件的标识
    bool        isDex;
    bool        okayToFree;
	// 描述dex文件内存加载镜像odex文件的结构体
    RawDexFile* pRawDexFile;
	// 描述内存加载后的jar文件的结构体
    JarFile*    pJarFile;
    u1*         pDexMemory; // malloc()ed memory, if any
};

openDexFileNative在native层对应的实现函数是 Dalvik_dalvik_system_DexFile_openDexFileNative。

http://androidxref.com/4.4.4_r1/xref/dalvik/vm/native/dalvik_system_DexFile.cpp#151

// 对应函数的注册结构体
const DalvikNativeMethod dvm_dalvik_system_DexFile[] = {
    { "openDexFileNative",  "(Ljava/lang/String;Ljava/lang/String;I)I",
        Dalvik_dalvik_system_DexFile_openDexFileNative },
    { "openDexFile",        "([B)I",
        Dalvik_dalvik_system_DexFile_openDexFile_bytearray },
    { "closeDexFile",       "(I)V",
        Dalvik_dalvik_system_DexFile_closeDexFile },
    { "defineClassNative",  "(Ljava/lang/String;Ljava/lang/ClassLoader;I)Ljava/lang/Class;",
        Dalvik_dalvik_system_DexFile_defineClassNative },
    { "getClassNameList",   "(I)[Ljava/lang/String;",
        Dalvik_dalvik_system_DexFile_getClassNameList },
    { "isDexOptNeeded",     "(Ljava/lang/String;)Z",
        Dalvik_dalvik_system_DexFile_isDexOptNeeded },
    { NULL, NULL, NULL },
};

/*
 * private static int openDexFileNative(String sourceName, String outputName,
 *     int flags) throws IOException
 *
 * Open a DEX file, returning a pointer to our internal data structure.
 *
 * "sourceName" should point to the "source" jar or DEX file.
 *
 * If "outputName" is NULL, the DEX code will automatically find the
 * "optimized" version in the cache directory, creating it if necessary.
 * If it's non-NULL, the specified file will be used instead.
 *
 * TODO: at present we will happily open the same file more than once.
 * To optimize this away we could search for existing entries in the hash
 * table and refCount them.  Requires atomic ops or adding "synchronized"
 * to the non-native code that calls here.
 *
 * TODO: should be using "long" for a pointer.
 */
static void Dalvik_dalvik_system_DexFile_openDexFileNative(const u4* args,
    JValue* pResult)
{
    StringObject* sourceNameObj = (StringObject*) args[0];
    StringObject* outputNameObj = (StringObject*) args[1];
    DexOrJar* pDexOrJar = NULL;
    JarFile* pJarFile;
    RawDexFile* pRawDexFile;
    char* sourceName;
    char* outputName;

    if (sourceNameObj == NULL) {
        dvmThrowNullPointerException("sourceName == null");
        RETURN_VOID();
    }

    sourceName = dvmCreateCstrFromString(sourceNameObj);
    if (outputNameObj != NULL)
        outputName = dvmCreateCstrFromString(outputNameObj);
    else
        outputName = NULL;

    /*
     * We have to deal with the possibility that somebody might try to
     * open one of our bootstrap class DEX files.  The set of dependencies
     * will be different, and hence the results of optimization might be
     * different, which means we'd actually need to have two versions of
     * the optimized DEX: one that only knows about part of the boot class
     * path, and one that knows about everything in it.  The latter might
     * optimize field/method accesses based on a class that appeared later
     * in the class path.
     *
     * We can't let the user-defined class loader open it and start using
     * the classes, since the optimized form of the code skips some of
     * the method and field resolution that we would ordinarily do, and
     * we'd have the wrong semantics.
     *
     * We have to reject attempts to manually open a DEX file from the boot
     * class path.  The easiest way to do this is by filename, which works
     * out because variations in name (e.g. "/system/framework/./ext.jar")
     * result in us hitting a different dalvik-cache entry.  It's also fine
     * if the caller specifies their own output file.
     */
    if (dvmClassPathContains(gDvm.bootClassPath, sourceName)) {
        ALOGW("Refusing to reopen boot DEX '%s'", sourceName);
        dvmThrowIOException(
            "Re-opening BOOTCLASSPATH DEX files is not allowed");
        free(sourceName);
        free(outputName);
        RETURN_VOID();
    }

    /*
     * Try to open it directly as a DEX if the name ends with ".dex".
     * If that fails (or isn't tried in the first place), try it as a
     * Zip with a "classes.dex" inside.
     */
    if (hasDexExtension(sourceName)
            && dvmRawDexFileOpen(sourceName, outputName, &pRawDexFile, false) == 0) {
        ALOGV("Opening DEX file '%s' (DEX)", sourceName);

        pDexOrJar = (DexOrJar*) malloc(sizeof(DexOrJar));
        pDexOrJar->isDex = true;
        pDexOrJar->pRawDexFile = pRawDexFile;
        pDexOrJar->pDexMemory = NULL;
    } else if (dvmJarFileOpen(sourceName, outputName, &pJarFile, false) == 0) {
        ALOGV("Opening DEX file '%s' (Jar)", sourceName);

        pDexOrJar = (DexOrJar*) malloc(sizeof(DexOrJar));
        pDexOrJar->isDex = false;
        pDexOrJar->pJarFile = pJarFile;
        pDexOrJar->pDexMemory = NULL;
    } else {
        ALOGV("Unable to open DEX file '%s'", sourceName);
        dvmThrowIOException("unable to open DEX file");
    }

    if (pDexOrJar != NULL) {
        pDexOrJar->fileName = sourceName;
        addToDexFileTable(pDexOrJar);
    } else {
        free(sourceName);
    }

    free(outputName);
    RETURN_PTR(pDexOrJar);
}

基于Xposed Hook开发的某加固脱壳工具是使用Xposed Hook框架Hook掉 DexClassLoader加载dex文件流程中类dalvik.system.DexFile的方法loadDex函数，等到loadDex函数返回时拿到dex文件内存加载后的mCookie值，然后内存dump出mCookie值描述的dex文件的值。类dalvik.system.DexFile的loadDex函数的实现如下：

http://androidxref.com/4.4.4_r1/xref/libcore/dalvik/src/main/java/dalvik/system/DexFile.java#141

    /**
     * Open a DEX file, specifying the file in which the optimized DEX
     * data should be written.  If the optimized form exists and appears
     * to be current, it will be used; if not, the VM will attempt to
     * regenerate it.
     *
     * This is intended for use by applications that wish to download
     * and execute DEX files outside the usual application installation
     * mechanism.  This function should not be called directly by an
     * application; instead, use a class loader such as
     * dalvik.system.DexClassLoader.
     *
     * @param sourcePathName
     *  Jar or APK file with "classes.dex".  (May expand this to include
     *  "raw DEX" in the future.)
     * @param outputPathName
     *  File that will hold the optimized form of the DEX data.
     * @param flags
     *  Enable optional features.  (Currently none defined.)
     * @return
     *  A new or previously-opened DexFile.
     * @throws IOException
     *  If unable to open the source or output file.
     */
    static public DexFile loadDex(String sourcePathName, String outputPathName,
        int flags) throws IOException {

        /*
         * TODO: we may want to cache previously-opened DexFile objects.
         * The cache would be synchronized with close().  This would help
         * us avoid mapping the same DEX more than once when an app
         * decided to open it multiple times.  In practice this may not
         * be a real issue.
         */
        return new DexFile(sourcePathName, outputPathName, flags);
    }

1.某加固脱壳工具Xposed Hook模块的编写，xxx.yyy.zzz为需要被脱壳的apk应用的包名，Xposed Hook掉类dalvik.system.DexFile的方法loadDex函数，获取到dex文件内存加载后的mCookie值，然后进行内存dex文件的dump处理。

package com.xposeddemo;

import java.lang.reflect.Field;
import dalvik.system.DexFile;
import de.robv.android.xposed.IXposedHookLoadPackage;
import de.robv.android.xposed.XC_MethodHook;
import de.robv.android.xposed.XposedBridge;
import de.robv.android.xposed.XposedHelpers;
import de.robv.android.xposed.callbacks.XC_LoadPackage;
import de.robv.android.xposed.callbacks.XC_LoadPackage.LoadPackageParam;


public class Module implements IXposedHookLoadPackage {

	// native方法在libnativelib.so库文件中实现
	public native void dumpdex(int cookie);
	
	// 内部类
	class dumpThread implements Runnable {
		
	    int cookide;
	    public dumpThread(int cookide){
	    	
	    	// 保存dex文件的mCookie值
	        this.cookide = cookide;
	    }
	
	    @Override
	    public void run() {
	    	
	        try {
	        	
	        	// 休眠5s 时间足够壳修复dex
	            Thread.sleep(5000);
	            
	        } catch (InterruptedException e) {
	        	
	            e.printStackTrace();
	        }
	        
	        // 从内存中dump出解密后的内存dex文件
	        dumpdex(cookide);
	    }
	}

	@Override
	public void handleLoadPackage(LoadPackageParam lpparam) throws Throwable {
		
		// 判断是否是要Hook的包名(xxx.yyy.zzz为需要脱壳的apk的包名)
		if (lpparam.packageName.equals("xxx.yyy.zzz")){
			
			XposedBridge.log("Loaded App:" + lpparam.packageName);
			
	    	// 加载动态库文件libnativelib.so
	        System.load("/data/data/com.xposeddemo/lib/libnativelib.so");
			
			// 对类dalvik.system.DexFile的方法loadDex进行java Hook操作
	        // 获取到需要脱壳apk解密dex文件加载后返回的mCookie值
	        // 根据mCookie值进行内存dex文件的dump操作
			loadhooklib(lpparam);
		}
	}
	
	 private void loadhooklib(XC_LoadPackage.LoadPackageParam lpparam) {
		 
		// 对类dalvik.system.DexFile的方法loadDex进行dalvik模式下的java Hook操作
		// /libcore/dalvik/src/main/java/dalvik/system/DexFile.java
		// static public DexFile loadDex(String sourcePathName, String outputPathName, int flags)
		// http://androidxref.com/4.4.4_r1/xref/libcore/dalvik/src/main/java/dalvik/system/DexFile.java#141
        XposedHelpers.findAndHookMethod(DexFile.class.getName(), 
        		lpparam.classLoader, "loadDex", 
        		String.class, 
        		String.class, int.class,
        		new XC_MethodHook() {
    	
                @Override
                protected void afterHookedMethod(MethodHookParam param) throws Throwable {
                	
                    if (!param.hasThrowable()) {
                    	
                        int falg = (Integer) param.args[2];
                        // 加载的dex文件的路径
                        String sourcePathName = (String) param.args[0];
                        // dex被优化后的odex文件的存放路径
                        String outputPathName = (String) param.args[1];
                        XposedBridge.log("sourcePathName:" + sourcePathName + " outputPathName:" 
                        				+ outputPathName + " falg:" + falg);
                        
                        // 获取dex文件被loadDex后返回的DexFile文件对象
                        Object object = param.getResult();
                        if (object instanceof DexFile) {
                        	
                        	// 通过类反射获取DexFile类的私有成员mCookie的调用Field
                            Field field = ((DexFile) object).getClass().getDeclaredField("mCookie");
                            // 设置有权限
                            field.setAccessible(true);
                            // 获取到DexFile类的私有成员mCookie的值
                            int cookie = field.getInt(object);
                            // 恢复权限
                            field.setAccessible(false);
                            System.out.println("cookie:" + String.format("%x", cookie));
                            
                            // 创建线程对需要脱壳的apk进程进行内存dex的dump操作
                            Thread thread = new Thread(new Module.dumpThread(cookie));
                            // 启动线程
                            thread.start();
                        }
                    }
                }
            });
	    }

}

2.内存dump函数实现在动态库文件libnativelib.so中实现，先通过jni函数反射调用java方法获取到手机设备的scard卡的文件路径，然后将内存dump的dex文件保存到手机设备的scard卡文件路径中。原作者在nativelib.cpp文件的源码实现中使用了C++的stl模板库函数，考虑到代码中字符串的处理比较简单，去掉了C++的stl模板库函数的使用，直接使用C语言的相关函数替换掉了，并且做了一些小调整；原作者在处理 code_off偏移超过dex文件大小的加固类型脱壳时比较暴力，直接保存三倍dex文件长度；如果dex文件内存dump时，想处理的精细一些可以参考一下dexHunter代码的实现。

#include 
#include 
#include 
//#include 
#include 
#include "Object.h"

//using std::string;

char* getExternalStorageDirectory(JNIEnv* env);
void printinfo(const char* tag, const char* fmt, ...);


char* jstringTostring(JNIEnv* env, jstring str)
{
    char* rtn = NULL;
    jclass clsstring = env->FindClass("java/lang/String");
    jstring strencode = env->NewStringUTF("utf-8");
    jmethodID mid = env->GetMethodID(clsstring, "getBytes", "(Ljava/lang/String;)[B");
    jbyteArray barr = (jbyteArray)env->CallObjectMethod(str, mid, strencode);
    jsize alen = env->GetArrayLength(barr);
    jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
    if (alen > 0)
    {
        rtn = (char*)malloc(alen + 1);
        memcpy(rtn, ba, alen);
        rtn[alen] = 0;
    }
    env->ReleaseByteArrayElements(barr, ba, 0);

    return rtn;
}

// 通过jni函数反射调用java方法获取到设备的scard卡的文件路径
char* getExternalStorageDirectory(JNIEnv* env)
{
    jclass Environment = env->FindClass("android/os/Environment");
    if (Environment != NULL)
    {
        //Messageprint::printinfo("util", "Environment class have found");
        jmethodID getExternalStorageDirectoryID = env->GetStaticMethodID(Environment,
        							"getExternalStorageDirectory", "()Ljava/io/File;");
        if (getExternalStorageDirectoryID != NULL)
        {
            jobject fileobject = env->CallStaticObjectMethod(Environment, getExternalStorageDirectoryID);
            jclass Fileclass = env->FindClass("java/io/File");
            jmethodID getAbsolutePathId = env->GetMethodID(Fileclass, "getAbsolutePath", "()Ljava/lang/String;");
            jstring jstringPath = (jstring)env->CallObjectMethod(fileobject, getAbsolutePathId);
            char* StorageDirectoryPath = jstringTostring(env, jstringPath);
            return StorageDirectoryPath;
        }
    }

    return NULL;
}


// 使用了stl的库函数
#ifdef __cplusplus
extern "C" {
#endif

// 调用native层实现的jni方法dumpdex
JNIEXPORT void JNICALL Java_com_xposeddemo_Module_dumpdex(JNIEnv *env, jobject instance, jint cookie) {

	DexOrJar* pDexOrJar = (DexOrJar*)cookie;
	DvmDex* pDvmDex;
	//打印dex文件的内存加载路径
	printf("jni", pDexOrJar->fileName);

	// 判断当前mCookie值是否是dex文件的
	if (pDexOrJar->isDex)
	{
		// 得到内存加载的odex文件的信息结构体
		pDvmDex = pDexOrJar->pRawDexFile->pDvmDex;
	}
	else
	{
		pDvmDex = pDexOrJar->pJarFile->pDvmDex;
	}

	// 获取到描述内存加载的odex文件信息的结构体DexFile
	DexFile* dexFile = pDvmDex->pDexFile;
	// 得到内存加载的odex文件的基地址（起始地址）
	MemMapping mapping = pDvmDex->memMap;
	printinfo("jni","MemMapping:addr:%x length:%x baseAddr:%x baseLength:%x",
			 mapping.addr, mapping.length, mapping.baseAddr, mapping.baseLength);

	// 通过jni函数反射调用java方法获取到设备的scard卡的文件路径
	char* path = getExternalStorageDirectory(env);

	char szBufferDexPath[128];
	memset(szBufferDexPath, 0, sizeof(szBufferDexPath));
	memcpy(szBufferDexPath, path, strlen(path));
	// 拼接字符串得到dump的dex文件的路径
	strcat(szBufferDexPath, "/xxxx.dex");
	printinfo("dump dex path: %s", szBufferDexPath);

	// F_OK = 0
	if (!access(szBufferDexPath,  F_OK))
	{
		// 删除已经存在的文件
		remove(szBufferDexPath);
	}

	// 创建新文件保存dump的dex文件
	FILE* file = fopen(szBufferDexPath, "wb+");

	// 保存三倍dex文件长度(比较暴力，可以参考dexhunter的实现代码进行优化)
	fwrite(mapping.addr,mapping.length*3,1,file);

	// 关闭文件
	fclose(file);
}

#ifdef __cplusplus
}
#endif

// 打印Log日志信息
void printinfo(const char* tag, const char* fmt, ...)
{
    va_list ap;
    char buf[1024];

    va_start(ap, fmt);
    vsnprintf(buf, 1024, fmt, ap);
    va_end(ap);
    __android_log_write(ANDROID_LOG_INFO, tag, buf);
}

3.jni目录需要的头文件 Object.h

#ifndef HELPTOOLCLIENT_OBJECT_H
#define HELPTOOLCLIENT_OBJECT_H
#include 
#include 
#include 

typedef uint8_t             u1;
typedef uint16_t            u2;
typedef uint32_t            u4;
typedef uint64_t            u8;
typedef int8_t              s1;
typedef int16_t             s2;
typedef int32_t             s4;
typedef int64_t             s8;

/* fwd decl */
struct DataObject;
struct InitiatingLoaderList;
struct ClassObject;
struct StringObject;
struct ArrayObject;
struct Method;
struct ExceptionEntry;
struct LineNumEntry;
struct StaticField;
struct InstField;
struct Field;
struct RegisterMap;

struct Object;
union JValue
{
    u1 z;
    s1 b;
    u2 c;
    s2 s;
    s4 i;
    s8 j;
    float f;
    double d;
    Object* l;
};

typedef void (*DalvikBridgeFunc)(const u4* args, JValue* pResult,
                                 const Method* method, struct Thread* self);

enum AccessFlags
{
    ACC_MIRANDA = 0x8000, // method (internal to VM)
    JAVA_FLAGS_MASK = 0xffff, // bits set from Java sources (low 16)
};

typedef void (*DalvikNativeFunc)(const u4* args, JValue* pResult);

enum ClassFlags
{
    CLASS_ISFINALIZABLE = (1 << 31), // class/ancestor overrides finalize()
    CLASS_ISARRAY = (1 << 30), // class is a "[*"
    CLASS_ISOBJECTARRAY = (1 << 29), // class is a "[L*" or "[[*"
    CLASS_ISCLASS = (1 << 28), // class is *the* class Class

    CLASS_ISREFERENCE = (1 << 27), // class is a soft/weak/phantom ref
    // only ISREFERENCE is set --> soft
            CLASS_ISWEAKREFERENCE = (1 << 26), // class is a weak reference
    CLASS_ISFINALIZERREFERENCE = (1 << 25), // class is a finalizer reference
    CLASS_ISPHANTOMREFERENCE = (1 << 24), // class is a phantom reference

    CLASS_MULTIPLE_DEFS = (1 << 23), // DEX verifier: defs in multiple DEXs

    /* unlike the others, these can be present in the optimized DEX file */
            CLASS_ISOPTIMIZED = (1 << 17), // class may contain opt instrs
    CLASS_ISPREVERIFIED = (1 << 16), // class has been pre-verified
};
#define EXPECTED_FILE_FLAGS \
    (ACC_CLASS_MASK | CLASS_ISPREVERIFIED | CLASS_ISOPTIMIZED)


#define SET_CLASS_FLAG(clazz, flag) \
    do { (clazz)->accessFlags |= (flag); } while (0)

#define CLEAR_CLASS_FLAG(clazz, flag) \
    do { (clazz)->accessFlags &= ~(flag); } while (0)

#define IS_CLASS_FLAG_SET(clazz, flag) \
    (((clazz)->accessFlags & (flag)) != 0)

#define GET_CLASS_FLAG_GROUP(clazz, flags) \
    ((u4)((clazz)->accessFlags & (flags)))

enum MethodFlags
{
    METHOD_ISWRITABLE = (1 << 31), // the method's code is writable
};

#define SET_METHOD_FLAG(method, flag) \
    do { (method)->accessFlags |= (flag); } while (0)

#define CLEAR_METHOD_FLAG(method, flag) \
    do { (method)->accessFlags &= ~(flag); } while (0)

#define IS_METHOD_FLAG_SET(method, flag) \
    (((method)->accessFlags & (flag)) != 0)

#define GET_METHOD_FLAG_GROUP(method, flags) \
    ((u4)((method)->accessFlags & (flags)))

enum ClassStatus
{
    CLASS_ERROR = -1,

    CLASS_NOTREADY = 0,
    CLASS_IDX = 1, /* loaded, DEX idx in super or ifaces */
            CLASS_LOADED = 2, /* DEX idx values resolved */
            CLASS_RESOLVED = 3, /* part of linking */
            CLASS_VERIFYING = 4, /* in the process of being verified */
            CLASS_VERIFIED = 5, /* logically part of linking; done pre-init */
            CLASS_INITIALIZING = 6, /* class init in progress */
            CLASS_INITIALIZED = 7, /* ready to go */
};
#define CLASS_WALK_SUPER ((unsigned int)(3))
#define CLASS_SMALLEST_OFFSET (sizeof(struct Object))
#define CLASS_BITS_PER_WORD (sizeof(unsigned long int) * 8)
#define CLASS_OFFSET_ALIGNMENT 4
#define CLASS_HIGH_BIT ((unsigned int)1 << (CLASS_BITS_PER_WORD - 1))
#define _CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset) \
    (((unsigned int)(byteOffset) - CLASS_SMALLEST_OFFSET) / \
     CLASS_OFFSET_ALIGNMENT)
#define CLASS_CAN_ENCODE_OFFSET(byteOffset) \
    (_CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset) < CLASS_BITS_PER_WORD)
#define CLASS_BIT_FROM_OFFSET(byteOffset) \
    (CLASS_HIGH_BIT >> _CLASS_BIT_NUMBER_FROM_OFFSET(byteOffset))
#define CLASS_OFFSET_FROM_CLZ(rshift) \
    (((int)(rshift) * CLASS_OFFSET_ALIGNMENT) + CLASS_SMALLEST_OFFSET)

struct InterfaceEntry
{
    ClassObject* clazz;
    int* methodIndexArray;
};

struct Object
{
    ClassObject* clazz;
    u4 lock;
};

#define DVM_OBJECT_INIT(obj, clazz_) \
    dvmSetFieldObject(obj, OFFSETOF_MEMBER(Object, clazz), clazz_)

struct DataObject : Object
{
    u4 instanceData[1];
};

struct StringObject : Object
{
    u4 instanceData[1];
    int length() const;
    int utfLength() const;
    ArrayObject* array() const;
    const u2* chars() const;
};

struct ArrayObject : Object
{
    u4 length;
    u8 contents[1];
};

struct InitiatingLoaderList
{
    Object** initiatingLoaders;
    int initiatingLoaderCount;
};

struct Field
{
    ClassObject* clazz; /* class in which the field is declared */
    const char* name;
    const char* signature; /* e.g. "I", "[C", "Landroid/os/Debug;" */
    u4 accessFlags;
};

struct StaticField : Field
{
    JValue value; /* initially set from DEX for primitives */
};

struct InstField : Field
{
    int byteOffset;
};

#define CLASS_FIELD_SLOTS   4
enum PrimitiveType
{
    PRIM_NOT = 0, /* value is a reference type, not a primitive type */
            PRIM_VOID = 1,
    PRIM_BOOLEAN = 2,
    PRIM_BYTE = 3,
    PRIM_SHORT = 4,
    PRIM_CHAR = 5,
    PRIM_INT = 6,
    PRIM_LONG = 7,
    PRIM_FLOAT = 8,
    PRIM_DOUBLE = 9,
};

// java类的描述结构体
struct ClassObject : Object
{
    u4 instanceData[CLASS_FIELD_SLOTS];

    const char* descriptor;
    char* descriptorAlloc;
    u4 accessFlags;
    u4 serialNumber;

    void* pDvmDex;

    ClassStatus status;

    ClassObject* verifyErrorClass;

    u4 initThreadId;

    size_t objectSize;

    ClassObject* elementClass;
    int arrayDim;
    PrimitiveType primitiveType;

    ClassObject* super;

    Object* classLoader;

    InitiatingLoaderList initiatingLoaderList;

    int interfaceCount;
    ClassObject** interfaces;

    int directMethodCount;
    Method* directMethods;
    int virtualMethodCount;
    Method* virtualMethods;


    int vtableCount;
    Method** vtable;

    int iftableCount;
    InterfaceEntry* iftable;


    int ifviPoolCount;
    int* ifviPool;


    int ifieldCount;
    int ifieldRefCount; // number of fields that are object refs
    InstField* ifields;

    u4 refOffsets;

    /* source file name, if known */
    const char* sourceFile;

    int sfieldCount;
    StaticField sfields[]; /* MUST be last item */
};


struct DexProto
{
    const void * dexFile; /* file the idx refers to */
    u4 protoIdx; /* index into proto_ids table of dexFile */
};

struct Method
{
    /* the class we are a part of */
    ClassObject* clazz;
    u4 accessFlags;

    u2 methodIndex;

    u2 registersSize; /* ins + locals */
    u2 outsSize;
    u2 insSize;

    /* method name, e.g. "" or "eatLunch" */
    const char* name;

    DexProto prototype;

    const char* shorty;

    const u2* insns; /* instructions, in memory-mapped .dex */


    int jniArgInfo;


    DalvikBridgeFunc nativeFunc;


    bool fastJni;


    bool noRef;


    bool shouldTrace;


    const RegisterMap* registerMap;

    /* set if method was called during method profiling */
    bool inProfile;
};

enum
{
    ACC_PUBLIC = 0x00000001, // class, field, method, ic
    ACC_PRIVATE = 0x00000002, // field, method, ic
    ACC_PROTECTED = 0x00000004, // field, method, ic
    ACC_STATIC = 0x00000008, // field, method, ic
    ACC_FINAL = 0x00000010, // class, field, method, ic
    ACC_SYNCHRONIZED = 0x00000020, // method (only allowed on natives)
    ACC_SUPER = 0x00000020, // class (not used in Dalvik)
    ACC_VOLATILE = 0x00000040, // field
    ACC_BRIDGE = 0x00000040, // method (1.5)
    ACC_TRANSIENT = 0x00000080, // field
    ACC_VARARGS = 0x00000080, // method (1.5)
    ACC_NATIVE = 0x00000100, // method
    ACC_INTERFACE = 0x00000200, // class, ic
    ACC_ABSTRACT = 0x00000400, // class, method, ic
    ACC_STRICT = 0x00000800, // method
    ACC_SYNTHETIC = 0x00001000, // field, method, ic
    ACC_ANNOTATION = 0x00002000, // class, ic (1.5)
    ACC_ENUM = 0x00004000, // class, field, ic (1.5)
    ACC_CONSTRUCTOR = 0x00010000, // method (Dalvik only)
    ACC_DECLARED_SYNCHRONIZED =
    0x00020000, // method (Dalvik only)
    ACC_CLASS_MASK =
    (ACC_PUBLIC | ACC_FINAL | ACC_INTERFACE | ACC_ABSTRACT
     | ACC_SYNTHETIC | ACC_ANNOTATION | ACC_ENUM),
    ACC_INNER_CLASS_MASK =
    (ACC_CLASS_MASK | ACC_PRIVATE | ACC_PROTECTED | ACC_STATIC),
    ACC_FIELD_MASK =
    (ACC_PUBLIC | ACC_PRIVATE | ACC_PROTECTED | ACC_STATIC | ACC_FINAL
     | ACC_VOLATILE | ACC_TRANSIENT | ACC_SYNTHETIC | ACC_ENUM),
    ACC_METHOD_MASK =
    (ACC_PUBLIC | ACC_PRIVATE | ACC_PROTECTED | ACC_STATIC | ACC_FINAL
     | ACC_SYNCHRONIZED | ACC_BRIDGE | ACC_VARARGS | ACC_NATIVE
     | ACC_ABSTRACT | ACC_STRICT | ACC_SYNTHETIC | ACC_CONSTRUCTOR
     | ACC_DECLARED_SYNCHRONIZED),
};

bool dvmIsPublicMethod(const Method* method)
{
    return (method->accessFlags & ACC_PUBLIC) != 0;
}

bool dvmIsPrivateMethod(const Method* method)
{
    return (method->accessFlags & ACC_PRIVATE) != 0;
}

bool dvmIsStaticMethod(const Method* method)
{
    return (method->accessFlags & ACC_STATIC) != 0;
}

bool dvmIsSynchronizedMethod(const Method* method)
{
    return (method->accessFlags & ACC_SYNCHRONIZED) != 0;
}

bool dvmIsDeclaredSynchronizedMethod(const Method* method)
{
    return (method->accessFlags & ACC_DECLARED_SYNCHRONIZED) != 0;
}

bool dvmIsFinalMethod(const Method* method)
{
    return (method->accessFlags & ACC_FINAL) != 0;
}

bool dvmIsNativeMethod(const Method* method)
{
    return (method->accessFlags & ACC_NATIVE) != 0;
}

bool dvmIsAbstractMethod(const Method* method)
{
    return (method->accessFlags & ACC_ABSTRACT) != 0;
}

bool dvmIsSyntheticMethod(const Method* method)
{
    return (method->accessFlags & ACC_SYNTHETIC) != 0;
}

bool dvmIsMirandaMethod(const Method* method)
{
    return (method->accessFlags & ACC_MIRANDA) != 0;
}

bool dvmIsConstructorMethod(const Method* method)
{
    return *method->name == '<';
}

/* Dalvik puts private, static, and constructors into non-virtual table */
bool dvmIsDirectMethod(const Method* method)
{
    return dvmIsPrivateMethod(method) ||
           dvmIsStaticMethod(method) ||
           dvmIsConstructorMethod(method);
}

/* Get whether the given method has associated bytecode. This is the
* case for methods which are neither native nor abstract. */
bool dvmIsBytecodeMethod(const Method* method)
{
    return (method->accessFlags & (ACC_NATIVE | ACC_ABSTRACT)) == 0;
}

bool dvmIsProtectedField(const Field* field)
{
    return (field->accessFlags & ACC_PROTECTED) != 0;
}

bool dvmIsStaticField(const Field* field)
{
    return (field->accessFlags & ACC_STATIC) != 0;
}

bool dvmIsFinalField(const Field* field)
{
    return (field->accessFlags & ACC_FINAL) != 0;
}

bool dvmIsVolatileField(const Field* field)
{
    return (field->accessFlags & ACC_VOLATILE) != 0;
}

bool dvmIsInterfaceClass(const ClassObject* clazz)
{
    return (clazz->accessFlags & ACC_INTERFACE) != 0;
}

bool dvmIsPublicClass(const ClassObject* clazz)
{
    return (clazz->accessFlags & ACC_PUBLIC) != 0;
}

bool dvmIsFinalClass(const ClassObject* clazz)
{
    return (clazz->accessFlags & ACC_FINAL) != 0;
}

bool dvmIsAbstractClass(const ClassObject* clazz)
{
    return (clazz->accessFlags & ACC_ABSTRACT) != 0;
}

bool dvmIsAnnotationClass(const ClassObject* clazz)
{
    return (clazz->accessFlags & ACC_ANNOTATION) != 0;
}

bool dvmIsPrimitiveClass(const ClassObject* clazz)
{
    return clazz->primitiveType != PRIM_NOT;
}

/* linked, here meaning prepared and resolved */
bool dvmIsClassLinked(const ClassObject* clazz)
{
    return clazz->status >= CLASS_RESOLVED;
}

/* has class been verified? */
bool dvmIsClassVerified(const ClassObject* clazz)
{
    return clazz->status >= CLASS_VERIFIED;
}




bool dvmIsClassInitialized(const ClassObject* clazz)
{
    return (clazz->status == CLASS_INITIALIZED);
}

/* annotation constants */
enum
{
    kDexVisibilityBuild = 0x00, /* annotation visibility */
            kDexVisibilityRuntime = 0x01,
    kDexVisibilitySystem = 0x02,

    kDexAnnotationByte = 0x00,
    kDexAnnotationShort = 0x02,
    kDexAnnotationChar = 0x03,
    kDexAnnotationInt = 0x04,
    kDexAnnotationLong = 0x06,
    kDexAnnotationFloat = 0x10,
    kDexAnnotationDouble = 0x11,
    kDexAnnotationString = 0x17,
    kDexAnnotationType = 0x18,
    kDexAnnotationField = 0x19,
    kDexAnnotationMethod = 0x1a,
    kDexAnnotationEnum = 0x1b,
    kDexAnnotationArray = 0x1c,
    kDexAnnotationAnnotation = 0x1d,
    kDexAnnotationNull = 0x1e,
    kDexAnnotationBoolean = 0x1f,

    kDexAnnotationValueTypeMask = 0x1f, /* low 5 bits */
            kDexAnnotationValueArgShift = 5,
};

/* map item type codes */
enum
{
    kDexTypeHeaderItem = 0x0000,
    kDexTypeStringIdItem = 0x0001,
    kDexTypeTypeIdItem = 0x0002,
    kDexTypeProtoIdItem = 0x0003,
    kDexTypeFieldIdItem = 0x0004,
    kDexTypeMethodIdItem = 0x0005,
    kDexTypeClassDefItem = 0x0006,
    kDexTypeMapList = 0x1000,
    kDexTypeTypeList = 0x1001,
    kDexTypeAnnotationSetRefList = 0x1002,
    kDexTypeAnnotationSetItem = 0x1003,
    kDexTypeClassDataItem = 0x2000,
    kDexTypeCodeItem = 0x2001,
    kDexTypeStringDataItem = 0x2002,
    kDexTypeDebugInfoItem = 0x2003,
    kDexTypeAnnotationItem = 0x2004,
    kDexTypeEncodedArrayItem = 0x2005,
    kDexTypeAnnotationsDirectoryItem = 0x2006,
};

/* auxillary data section chunk codes */
enum
{
    kDexChunkClassLookup = 0x434c4b50, /* CLKP */
            kDexChunkRegisterMaps = 0x524d4150, /* RMAP */

            kDexChunkEnd = 0x41454e44, /* AEND */
};

/* debug info opcodes and constants */
enum
{
    DBG_END_SEQUENCE = 0x00,
    DBG_ADVANCE_PC = 0x01,
    DBG_ADVANCE_LINE = 0x02,
    DBG_START_LOCAL = 0x03,
    DBG_START_LOCAL_EXTENDED = 0x04,
    DBG_END_LOCAL = 0x05,
    DBG_RESTART_LOCAL = 0x06,
    DBG_SET_PROLOGUE_END = 0x07,
    DBG_SET_EPILOGUE_BEGIN = 0x08,
    DBG_SET_FILE = 0x09,
    DBG_FIRST_SPECIAL = 0x0a,
    DBG_LINE_BASE = -4,
    DBG_LINE_RANGE = 15,
};

enum
{
    kSHA1DigestLen = 20,
    kSHA1DigestOutputLen = kSHA1DigestLen * 2 + 1
};


/*
* Direct-mapped "header_item" struct.
*/
struct DexHeader
{
    u1 magic[8]; /* includes version number */
    u4 checksum; /* adler32 checksum */
    u1 signature[kSHA1DigestLen]; /* SHA-1 hash */
    u4 fileSize; /* length of entire file */
    u4 headerSize; /* offset to start of next section */
    u4 endianTag;
    u4 linkSize;
    u4 linkOff;
    u4 mapOff;
    u4 stringIdsSize;
    u4 stringIdsOff;
    u4 typeIdsSize;
    u4 typeIdsOff;
    u4 protoIdsSize;
    u4 protoIdsOff;
    u4 fieldIdsSize;
    u4 fieldIdsOff;
    u4 methodIdsSize;
    u4 methodIdsOff;
    u4 classDefsSize;
    u4 classDefsOff;
    u4 dataSize;
    u4 dataOff;
};

/*
* Direct-mapped "map_item".
*/
struct DexMapItem
{
    u2 type; /* type code (see kDexType* above) */
    u2 unused;
    u4 size; /* count of items of the indicated type */
    u4 offset; /* file offset to the start of data */
};

/*
* Direct-mapped "map_list".
*/
struct DexMapList
{
    u4 size; /* #of entries in list */
    DexMapItem list[1]; /* entries */
};

/*
* Direct-mapped "string_id_item".
*/
struct DexStringId
{
    u4 stringDataOff; /* file offset to string_data_item */
};

/*
* Direct-mapped "type_id_item".
*/
struct DexTypeId
{
    u4 descriptorIdx; /* index into stringIds list for type descriptor */
};

/*
* Direct-mapped "field_id_item".
*/
struct DexFieldId
{
    u2 classIdx; /* index into typeIds list for defining class */
    u2 typeIdx; /* index into typeIds for field type */
    u4 nameIdx; /* index into stringIds for field name */
};

/*
* Direct-mapped "method_id_item".
*/
struct DexMethodId
{
    u2 classIdx; /* index into typeIds list for defining class */
    u2 protoIdx; /* index into protoIds for method prototype */
    u4 nameIdx; /* index into stringIds for method name */
};

/*
* Direct-mapped "proto_id_item".
*/
struct DexProtoId
{
    u4 shortyIdx; /* index into stringIds for shorty descriptor */
    u4 returnTypeIdx; /* index into typeIds list for return type */
    u4 parametersOff; /* file offset to type_list for parameter types */
};

/*
* Direct-mapped "class_def_item".
*/
struct DexClassDef
{
    u4 classIdx; /* index into typeIds for this class */
    u4 accessFlags;
    u4 superclassIdx; /* index into typeIds for superclass */
    u4 interfacesOff; /* file offset to DexTypeList */
    u4 sourceFileIdx; /* index into stringIds for source file name */
    u4 annotationsOff; /* file offset to annotations_directory_item */
    u4 classDataOff; /* file offset to class_data_item */
    u4 staticValuesOff; /* file offset to DexEncodedArray */
};

/*
* Direct-mapped "type_item".
*/
struct DexTypeItem
{
    u2 typeIdx; /* index into typeIds */
};

/*
* Direct-mapped "type_list".
*/
struct DexTypeList
{
    u4 size; /* #of entries in list */
    DexTypeItem list[1]; /* entries */
};

typedef struct DexMapId
{
    u2 type; /*Section type*/

    u2 unused; /*unused*/
    u4 size; /* section size*/
    u4 offset; /* section offset */
} DexMapId;

/*
* Direct-mapped "code_item".
*
* The "catches" table is used when throwing an exception,
* "debugInfo" is used when displaying an exception stack trace or
* debugging. An offset of zero indicates that there are no entries.
*/
struct DexCode
{
    u2 registersSize;
    u2 insSize;
    u2 outsSize;
    u2 triesSize;
    u4 debugInfoOff; /* file offset to debug info stream */
    u4 insnsSize; /* size of the insns array, in u2 units */
    u2 insns[1];
    /* followed by optional u2 padding */
    /* followed by try_item[triesSize] */
    /* followed by uleb128 handlersSize */
    /* followed by catch_handler_item[handlersSize] */
};

/*
* Direct-mapped "try_item".
*/
struct DexTry
{
    u4 startAddr; /* start address, in 16-bit code units */
    u2 insnCount; /* instruction count, in 16-bit code units */
    u2 handlerOff; /* offset in encoded handler data to handlers */
};

/*
* Link table.  Currently undefined.
*/
struct DexLink
{
    u1 bleargh;
};


/*
* Direct-mapped "annotations_directory_item".
*/
struct DexAnnotationsDirectoryItem
{
    u4 classAnnotationsOff; /* offset to DexAnnotationSetItem */
    u4 fieldsSize; /* count of DexFieldAnnotationsItem */
    u4 methodsSize; /* count of DexMethodAnnotationsItem */
    u4 parametersSize; /* count of DexParameterAnnotationsItem */
    /* followed by DexFieldAnnotationsItem[fieldsSize] */
    /* followed by DexMethodAnnotationsItem[methodsSize] */
    /* followed by DexParameterAnnotationsItem[parametersSize] */
};

/*
* Direct-mapped "field_annotations_item".
*/
struct DexFieldAnnotationsItem
{
    u4 fieldIdx;
    u4 annotationsOff; /* offset to DexAnnotationSetItem */
};

/*
* Direct-mapped "method_annotations_item".
*/
struct DexMethodAnnotationsItem
{
    u4 methodIdx;
    u4 annotationsOff; /* offset to DexAnnotationSetItem */
};

/*
* Direct-mapped "parameter_annotations_item".
*/
struct DexParameterAnnotationsItem
{
    u4 methodIdx;
    u4 annotationsOff; /* offset to DexAnotationSetRefList */
};

/*
* Direct-mapped "annotation_set_ref_item".
*/
struct DexAnnotationSetRefItem
{
    u4 annotationsOff; /* offset to DexAnnotationSetItem */
};

/*
* Direct-mapped "annotation_set_ref_list".
*/
struct DexAnnotationSetRefList
{
    u4 size;
    DexAnnotationSetRefItem list[1];
};

/*
* Direct-mapped "annotation_set_item".
*/
struct DexAnnotationSetItem
{
    u4 size;
    u4 entries[1]; /* offset to DexAnnotationItem */
};

/*
* Direct-mapped "annotation_item".
*
* NOTE: this structure is byte-aligned.
*/
struct DexAnnotationItem
{
    u1 visibility;
    u1 annotation[1]; /* data in encoded_annotation format */
};

/*
* Direct-mapped "encoded_array".
*
* NOTE: this structure is byte-aligned.
*/
struct DexEncodedArray
{
    u1 array[1]; /* data in encoded_array format */
};

/*
* Lookup table for classes.  It provides a mapping from class name to
* class definition.  Used by dexFindClass().
*
* We calculate this at DEX optimization time and embed it in the file so we
* don't need the same hash table in every VM.  This is slightly slower than
* a hash table with direct pointers to the items, but because it's shared
* there's less of a penalty for using a fairly sparse table.
*/
struct DexClassLookup
{
    int size; // total size, including "size"
    int numEntries; // size of table[]; always power of 2
    struct
    {
        u4 classDescriptorHash; // class descriptor hash code
        int classDescriptorOffset; // in bytes, from start of DEX
        int classDefOffset; // in bytes, from start of DEX
    } table[1];
};

/*
* Header added by DEX optimization pass.  Values are always written in
* local byte and structure padding.  The first field (magic + version)
* is guaranteed to be present and directly readable for all expected
* compiler configurations; the rest is version-dependent.
*
* Try to keep this simple and fixed-size.
*/
struct DexOptHeader
{
    u1 magic[8]; /* includes version number */

    u4 dexOffset; /* file offset of DEX header */
    u4 dexLength;
    u4 depsOffset; /* offset of optimized DEX dependency table */
    u4 depsLength;
    u4 optOffset; /* file offset of optimized data tables */
    u4 optLength;

    u4 flags; /* some info flags */
    u4 checksum; /* adler32 checksum covering deps/opt */

    /* pad for 64-bit alignment if necessary */
};

#define DEX_OPT_FLAG_BIG            (1<<1)  /* swapped to big-endian */

#define DEX_INTERFACE_CACHE_SIZE    128     /* must be power of 2 */

/*
* Structure representing a DEX file.
*
* Code should regard DexFile as opaque, using the API calls provided here
* to access specific structures.
*/
struct DexFile
{
    /* directly-mapped "opt" header */
    const DexOptHeader* pOptHeader;

    /* pointers to directly-mapped structs and arrays in base DEX */
    const DexHeader* pHeader;
    const DexStringId* pStringIds;
    const DexTypeId* pTypeIds;
    const DexFieldId* pFieldIds;
    const DexMethodId* pMethodIds;
    const DexProtoId* pProtoIds;
    const DexClassDef* pClassDefs;
    const DexLink* pLinkData;

    /*
    * These are mapped out of the "auxillary" section, and may not be
    * included in the file.
    */
    const DexClassLookup* pClassLookup;
    const void* pRegisterMapPool; // RegisterMapClassPool

    /* points to start of DEX file data */
    const u1* baseAddr;

    /* track memory overhead for auxillary structures */
    int overhead;

    /* additional app-specific data structures associated with the DEX */
    //void*               auxData;
};


struct MemMapping
{
    void* addr; /* start of data */
    size_t length; /* length of data */

    void* baseAddr; /* page-aligned base address */
    size_t baseLength; /* length of mapping */
};

struct DvmDex
{
    /* pointer to the DexFile we're associated with */
    DexFile* pDexFile;

    /* clone of pDexFile->pHeader (it's used frequently enough) */
    const DexHeader* pHeader;

    /* interned strings; parallel to "stringIds" */
    struct StringObject** pResStrings;

    /* resolved classes; parallel to "typeIds" */
    struct ClassObject** pResClasses;

    /* resolved methods; parallel to "methodIds" */
    struct Method** pResMethods;

    /* resolved instance fields; parallel to "fieldIds" */
    /* (this holds both InstField and StaticField) */
    struct Field** pResFields;

    /* interface method lookup cache */
    struct AtomicCache* pInterfaceCache;

    /* shared memory region with file contents */
    bool isMappedReadOnly;
    MemMapping memMap;

    jobject dex_object;

    /* lock ensuring mutual exclusion during updates */
    pthread_mutex_t modLock;
};

struct JarFile
{
    u4* Nocare[9];
    char* cacheFileName;
    DvmDex* pDvmDex;
};

struct RawDexFile
{
    char* cacheFileName;
    struct DvmDex* pDvmDex; //DvmDex*
};

struct DexOrJar
{
    char* fileName;
    bool isDex;
    bool okayToFree;
    RawDexFile* pRawDexFile;
    JarFile* pJarFile;
    u1* pDexMemory; // malloc()ed memory, if any
};
#endif //HELPTOOLCLIENT_OBJECT_H

4.当前工程ndk编译需要的配置文件Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := nativelib
LOCAL_SRC_FILES := nativelib.cpp

# 支持log日志打印需要加载链接的库    
LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog    

include $(BUILD_SHARED_LIBRARY)

5.使用当前Xposed Hook工具进行某加固脱壳的测试结果。

使用JEB工具反编译脱壳成功后的odex文件，结果如下图：

总之呢，这个工具对付一般免费版的某数字加固保、某加密、某梆梆加固还是可以的，企业估计不行还需要修改和优化，有兴趣的可以测试一下其他的免费版的加固产品，可以把样本和结果反馈下，我修改一下。

重要参考：

某加固使用xposed脱壳