DexExtractor的原理分析和使用说明

本文博客链接：http://blog.csdn.net/qq1084283172/article/details/53557894

周末有空就写下博客了，今天来扯一扯Android平台的脱壳工具DexExtractor。DexExtractor工具的使用比较简单，脱壳的原理也比较简单，工具的作者bunnyrene讲这个android脱壳工具只要是针对bangbang (Bangcle)和ijiami加固的脱壳工具，应该是这两类加固的免费版吧。之前在分析android病毒的时候使用过，但是有时候脱壳还是不成功，需要人工手工脱壳来完成或者说这个工具需要进一步完善一下，不管怎么说谢谢作者大牛。

i.DexExtractor脱壳工具的使用说明和讨论链接

看雪论坛：http://bbs.pediy.com/showthread.php?t=201799

github地址：https://github.com/bunnyblue/DexExtractor

ii.作者编译好的镜像文件system.img的下载地址

网盘地址：http://pan.baidu.com/s/1jG3WQMU

iii.DexExtractor脱壳工具的使用说明截图：

iiii.通过阅读DexExtractor作者提供的使用说明，写下需要注意的地方：

1.DexExtractor脱壳工具的原理是修改了android源码的DexFile.cpp的dexFileParse函数也就是原来的脱壳点函数处进行dexdump的处理，作者提供了Android
4.4---api 19版本系统脱壳的system.img文件（推荐android模拟器用）和libdvm.so文件（android模拟器和android真机都可以使用）。

2.由于DexExtractor工具需要不断的向sdcard写文件，因此特别是android模拟器使用该脱壳工具一定设置Android模拟的sdcard的空间大小。

3.由于DexExtractor工具需要不断的向sdcard写文件，因此被脱壳的apk需要有向sdcard写文件的权限<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>。

4.DexExtractor工具的system.img文件（Android
4.4.2版本）使用比较简单--直接替换Android 4.4.2版本系统的system.img文件文件即可，Android模拟器的system.img文件的替换比较简单，Android真机的替换可能需要是Android真机进入recovery模式进行替换；DexExtractor工具的libdvm.so文件使用--需要使用abd的push命令将libdvm.so推送到android系统中然后在su权限将libdvm.so文件拷贝或者备份到Android系统的/system/lib/libdvm.so或者Android真机在root的情况下，使用rootexplore.apk（RE管理器工具）将libdvm.so文件拷贝到手机系统的/system/lib/libdvm.so下，替换掉原来Android系统的的/system/lib/libdvm.so文件，并赋予刚才拷贝替换的/system/lib/libdvm.so文件以0775权限然后重启Android真机即可。

adb push xxx/libdvm.so /data/local/tmp/libdvm.so
adb shell
su
mount -r -w -o remount/system
mount -o remount,rw /system
dd if=/system/lib/libdvm.so of=/data/local/tmp/libdvm.bak
rm /system/lib/libdvm.so
cat /data/local/tmp/libdvm.so >/system/lib/libdvm.so
chmod 0775 /system/lib/libdvm.so
mount -o remount,ro /system
exit
exit
adb reboot

iiiii.使用DexExtractor工具的system.img文件配置Android 4.4.2的android模拟器进行脱壳实验

使用前提条件：

1.如果是android模拟器使用脱壳镜像文件system.img，一定要配置sdcard参数

2.需要脱壳的apk如果没有写权限，需要添加上写sdcard的权限。

如：
apk没有写权限的反编译了加上write权限

说明：

<!--往sdcard写入数据权限 -->

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<!--sdcard创建/删除文件权限 -->

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

需要使用的权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

#如果脱壳apk没有文件的写权限，反编译以后加上sdcard文件的写权限，然后重新打包apk程序。

DexExtractor脱壳实例(使用Android模拟器)：

1.找到Android 4.4.2对应的API 19的系统文件的目录，如下：

E:\BaiduYunDownload\adt-bundle-windows-x86_64-20140702\sdk\system-images\android-19\default\armeabi-v7a
备份原来的system.img文件，然后将修改的system.img文件解压后拷贝到这个目录里。

2.在android模拟器上创建API为19的android模拟器，千万不能忘了为模拟器添加sdcard的内存空间参数。

3.用反编译工具查看被脱壳的apk是否有-----写文件的权限<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>没有就添加上写文件的权限并重新打包apk程序。

4.adb install xxx.apk 安装需要脱壳的apk程序到上面创建的android模拟器上。

5.打开logcat的logcat 监视log  "被加固的包名" 和 "dvmtag" ，当看到 "create file end",说明脱壳成功；从eclipse中导出log日志文件并保存。（这里请参考作者提供的脱壳成功的说明）

6.adb pull  /sdcard/classes_xxx.dex 从android模拟器的sdcard中导出脱壳后但是经过base64加密的dex文件。

示例：

adb  pull  /sdcard/tx.qq898507339.bzy9_classes_5528.dex

7.脱壳后的dex文件被Base64编码了，需要解码。 

解码dex文件：

java -jar Decoder.jar  dex目录  

java -jar Decoder.jar   xxxx\tx.qq898507339.bzy9_classes_5528.dex

======================================================================================================
java环境的正确配置

安装JDK，比如目录在C:\Java

为了方便java程序的开发，需要配置一下环境变量，右击我的电脑->属性->高级->环境变量->用户变量中单击[新建(N)]添加以下环境变量

(假定你的JDK安装路径为C:\Java\jdk1.6.0_30）

JAVA_HOME

C:\Java\jdk1.6.0_30

PATH

C:\Java\jdk1.6.0_30\bin

CLASSPATH

.;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar;（注前面的点号和分号一定不能丢，还有中间的，后面的分号也不要丢了）

说明：CLASSPATH可以再增加一些第三方的jar文件，方便手工编译和运行程序。

======================================================================================================

iiiiii.DexExtractor脱壳工具的代码分析:

DexExtractor脱壳工具的脱壳原理是修改了android系统的dvm虚拟机模块的代码/dalvik/libdex/DexFile.cpp文件的dexFileParse函数，在系统调用dexFileParse函数之前将加固释放出的原始dex文件从内存dump出来。

但是呢，由于一些加固如梆梆加固，会对dex的内存dump脱壳进行检测，具体的就是hook修改当前进程的read、write读写相关的函数，一旦检测到read、write读写相关的函数的操作中有对dex文件的dump行为会有对抗的处理，防止dex的内存dump，因此呢，DexExtractor脱壳工具的作者为了过掉这种内存dump的对抗，需要先将原始的dex文件数据进行base64加密然后进行写文件到sdcard中进行输出，当pull导出拿到base64加密的dex文件时还需要进行base64的解密才能获取到原始的dex文件，具体的脱壳功能见DexHacker.cpp文件。

//
//  DexHacker.cpp
//
//
//  Created by BunnyBlue on 6/23/15.
//
//

#include "DexHacker.h"
void DexHacker::writeDex2Encoded(unsigned char *data, size_t length){

#ifdef CODE_DVM
    ALOGE("--pacthed--  inject  .dex length %d  flag=%d",length,flags);

    char dexbuffer[64]={0};

    char dexbufferNamed[128]={0};
    char bufferProcess[256]={0};

	// 获取当前进程的名称字符串
    bufferProcess= getProcessName(bufferProcess);
    sprintf(dexbuffer, "classes_%d", length);
    strcat(dexbufferNamed,"/sdcard/");

    if (bufferProcess!=NULL) {
     strcat(dexbufferNamed, bufferProcess);
        strcat(dexbufferNamed, dexbuffer);
    }else{
          ALOGE("--pacthed-- , FAULT pid not  found\n");
        return;
    }

    // strcat(dexbufferNamed,dexbuffer);
    strcat(dexbufferNamed,".dex");

    ALOGE("--pacthed-- , %s\n", dexbufferNamed);
    ALOGE("--pacthed--  debug dalvikParse   find dex try write file  ");

    // 删除原来存在的文件
    int status = remove(dexbufferNamed);
    if( status == 0 )
        ALOGE("%s file deleted successfully.\n",dexbufferNamed);
    else
    {
        ALOGE("Unable to delete the file\n");

    }

    // 申请内存缓冲区备份信息
    u1* buffer_data_dest=(u1*)malloc((length+1)*sizeof(u1));
    // 拷贝内存中的dex文件的数据到内存缓冲区buffer_data_dest中备份
    memcpy(buffer_data_dest, data, length);

    // 创建文件
    FILE *fp = fopen(dexbufferNamed,"wb");
    if(NULL==fp) {

        ALOGE("--pacthed-- , can't create file ! maybe  you need mount sdcard again!");
        ALOGE( "%s data %s\n", strerror(errno),data);

    } else {

        ALOGE("--pacthed--   create file  %s ",dexbufferNamed);
        int dex_lem_local = length>2048? 1024:length;

        //  申请内存空间保存base64加密后的dex文件的数据
        unsigned char *dst=(unsigned char*)malloc(length*2.5);
        unsigned long dlen=length*2.5;

        // 将原始的dex文件的数据进行base64加密
        base64_encode(dst, &dlen, data, length);
        // 将base64加密后的dex文件的数据进行写文件输出到sdcard中
        fwrite(dst, dlen, 1, fp);

        //fwrite(data, sizeof(u1), length, fp);
        ALOGE("--pacthed--  create file  end ");

        //fflush(fp);
        fclose(fp);
        fp = NULL;
    }
    free(buffer_data_dest);
#else 

    char dexbuffer[64]={0};
    char dexbufferNamed[128]={0};
    sprintf(dexbuffer, "classes_%d", length);
    //strcat(dexbufferNamed,");
    strcat(dexbufferNamed,dexbuffer);
    strcat(dexbufferNamed,".dex");

    int status = remove(dexbufferNamed);

    FILE *fp = fopen(dexbufferNamed,"wb");
    if(NULL==fp){

    } else {

        unsigned char *dst=(unsigned char*)malloc(length*2.5);
        unsigned long dlen=length*2.5;
        base64_encode(dst, &dlen, data, length);

        fwrite(dst, dlen, 1, fp);
        //fflush(fp);
        fclose(fp);
        fp = NULL;
    }

#endif
}

void DexHacker::writeEncodedDex2Dex(const char *encodedDex){

    FILE *srcDexFile=fopen(encodedDex,"rb");
    std::string outDexFile(encodedDex);
    outDexFile.append(".read.dex");

    FILE *outFile=fopen(outDexFile.c_str(), "wb");

    if (srcDexFile!=NULL) {
        fseek(srcDexFile,0,SEEK_END);
        long fsize =ftell(srcDexFile);
        rewind(srcDexFile);

        std::cout<<sizeof(char)<<"\nxxxxxxxx"<<fsize;
        unsigned  char *list=(unsigned char*)malloc(sizeof(char)*fsize);
        unsigned long  numread =fread(list,sizeof(char),fsize,srcDexFile);
        // blue_dump_data(list, (unsigned long )fsize);
        unsigned char *dst=(unsigned char*)malloc(numread);
        unsigned long dlen=numread;
        base64_decode(dst, &dlen, list, numread);

        fclose(srcDexFile);

        int ret=fwrite(dst, 1, dlen, outFile);
        fclose(outFile);
        //   std::cout<<"\n"<<repeate<<"numread"<<numread;
    }

}

char* itoa(int i, char b[]){

    char const digit[] = "0123456789";
    char* p = b;
    if(i<0){
        *p++ = '-';
        i *= -1;
    }
    int shifter = i;
    do{ //Move to where representation ends
        ++p;
        shifter = shifter/10;
    }while(shifter);
    *p = '\0';
    do{ //Move back, inserting digits as u go
        *--p = digit[i%10];
        i = i/10;
    }while(i);
    return b;
}

// 获取当前进程的名称
char * DexHacker::getProcessName(char * buffer){

    char path_t[256]={0};
	// char buffer[512]={0} ;

	// 获取当前进程的pid
    pid_t pid=getpid();
    char str[15];
    sprintf(str, "%d", pid);
    memset(path_t, 0 , sizeof(path_t));
    strcat(path_t, "/proc/");
    strcat(path_t, str);
    strcat(path_t, "/cmdline");

    //LOG_ERROR("zhw", "path:%s", path_t);
    int fd_t = open(path_t, O_RDONLY);
    if(fd_t>0){

        int read_count = read(fd_t, buffer, BUFLEN);
        if(read_count>0){

            return buffer;
        }
    }

    return NULL;
}

iiiiii.DexExtractor脱壳工具作者提供的文件的说明

关于DexExtractor脱壳工具的自行修改和扩展：根据自己的脱壳思路，编写额外的脱壳代码文件，添加自选Android系统版本的DexFile.cpp文件并将额外的脱壳代码文件添加到编译配置文件Android.mk中，然后在DexFile.cpp文件路径下进行android源码的局部模块的编译，具体编译参考见http://blog.csdn.net/qq1084283172/article/details/53365659。

iiiiii.DexExtractor脱壳工具的其他代码文件：

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Access the contents of a .dex file.
 */

#include "DexFile.h"
#include "DexOptData.h"
#include "DexProto.h"
#include "DexCatch.h"
#include "Leb128.h"
#include "sha1.h"
#include "ZipArchive.h"

#include <zlib.h>

#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include "DexHacker.cpp"

/*
 * Verifying checksums is good, but it slows things down and causes us to
 * touch every page.  In the "optimized" world, it doesn't work at all,
 * because we rewrite the contents.
 */
static const bool kVerifyChecksum = false;
static const bool kVerifySignature = false;

/* (documented in header) */
char dexGetPrimitiveTypeDescriptorChar(PrimitiveType type) {
    const char* string = dexGetPrimitiveTypeDescriptor(type);

    return (string == NULL) ? '\0' : string[0];
}

/* (documented in header) */
const char* dexGetPrimitiveTypeDescriptor(PrimitiveType type) {
    switch (type) {
        case PRIM_VOID:    return "V";
        case PRIM_BOOLEAN: return "Z";
        case PRIM_BYTE:    return "B";
        case PRIM_SHORT:   return "S";
        case PRIM_CHAR:    return "C";
        case PRIM_INT:     return "I";
        case PRIM_LONG:    return "J";
        case PRIM_FLOAT:   return "F";
        case PRIM_DOUBLE:  return "D";
        default:           return NULL;
    }

    return NULL;
}

/* (documented in header) */
const char* dexGetBoxedTypeDescriptor(PrimitiveType type) {
    switch (type) {
        case PRIM_VOID:    return NULL;
        case PRIM_BOOLEAN: return "Ljava/lang/Boolean;";
        case PRIM_BYTE:    return "Ljava/lang/Byte;";
        case PRIM_SHORT:   return "Ljava/lang/Short;";
        case PRIM_CHAR:    return "Ljava/lang/Character;";
        case PRIM_INT:     return "Ljava/lang/Integer;";
        case PRIM_LONG:    return "Ljava/lang/Long;";
        case PRIM_FLOAT:   return "Ljava/lang/Float;";
        case PRIM_DOUBLE:  return "Ljava/lang/Double;";
        default:           return NULL;
    }
}

/* (documented in header) */
PrimitiveType dexGetPrimitiveTypeFromDescriptorChar(char descriptorChar) {
    switch (descriptorChar) {
        case 'V': return PRIM_VOID;
        case 'Z': return PRIM_BOOLEAN;
        case 'B': return PRIM_BYTE;
        case 'S': return PRIM_SHORT;
        case 'C': return PRIM_CHAR;
        case 'I': return PRIM_INT;
        case 'J': return PRIM_LONG;
        case 'F': return PRIM_FLOAT;
        case 'D': return PRIM_DOUBLE;
        default:  return PRIM_NOT;
    }
}

/* Return the UTF-8 encoded string with the specified string_id index,
 * also filling in the UTF-16 size (number of 16-bit code points).*/
const char* dexStringAndSizeById(const DexFile* pDexFile, u4 idx,
        u4* utf16Size) {
    const DexStringId* pStringId = dexGetStringId(pDexFile, idx);
    const u1* ptr = pDexFile->baseAddr + pStringId->stringDataOff;

    *utf16Size = readUnsignedLeb128(&ptr);
    return (const char*) ptr;
}

/*
 * Format an SHA-1 digest for printing.  tmpBuf must be able to hold at
 * least kSHA1DigestOutputLen bytes.
 */
const char* dvmSHA1DigestToStr(const unsigned char digest[], char* tmpBuf);

/*
 * Compute a SHA-1 digest on a range of bytes.
 */
static void dexComputeSHA1Digest(const unsigned char* data, size_t length,
    unsigned char digest[])
{
    SHA1_CTX context;
    SHA1Init(&context);
    SHA1Update(&context, data, length);
    SHA1Final(digest, &context);
}

/*
 * Format the SHA-1 digest into the buffer, which must be able to hold at
 * least kSHA1DigestOutputLen bytes.  Returns a pointer to the buffer,
 */
static const char* dexSHA1DigestToStr(const unsigned char digest[],char* tmpBuf)
{
    static const char hexDigit[] = "0123456789abcdef";
    char* cp;
    int i;

    cp = tmpBuf;
    for (i = 0; i < kSHA1DigestLen; i++) {
        *cp++ = hexDigit[digest[i] >> 4];
        *cp++ = hexDigit[digest[i] & 0x0f];
    }
    *cp++ = '\0';

    assert(cp == tmpBuf + kSHA1DigestOutputLen);

    return tmpBuf;
}

/*
 * Compute a hash code on a UTF-8 string, for use with internal hash tables.
 *
 * This may or may not be compatible with UTF-8 hash functions used inside
 * the Dalvik VM.
 *
 * The basic "multiply by 31 and add" approach does better on class names
 * than most other things tried (e.g. adler32).
 */
static u4 classDescriptorHash(const char* str)
{
    u4 hash = 1;

    while (*str != '\0')
        hash = hash * 31 + *str++;

    return hash;
}

/*
 * Add an entry to the class lookup table.  We hash the string and probe
 * until we find an open slot.
 */
static void classLookupAdd(DexFile* pDexFile, DexClassLookup* pLookup,
    int stringOff, int classDefOff, int* pNumProbes)
{
    const char* classDescriptor =
        (const char*) (pDexFile->baseAddr + stringOff);
    const DexClassDef* pClassDef =
        (const DexClassDef*) (pDexFile->baseAddr + classDefOff);
    u4 hash = classDescriptorHash(classDescriptor);
    int mask = pLookup->numEntries-1;
    int idx = hash & mask;

    /*
     * Find the first empty slot.  We oversized the table, so this is
     * guaranteed to finish.
     */
    int probes = 0;
    while (pLookup->table[idx].classDescriptorOffset != 0) {
        idx = (idx + 1) & mask;
        probes++;
    }
    //if (probes > 1)
    //    ALOGW("classLookupAdd: probes=%d", probes);

    pLookup->table[idx].classDescriptorHash = hash;
    pLookup->table[idx].classDescriptorOffset = stringOff;
    pLookup->table[idx].classDefOffset = classDefOff;
    *pNumProbes = probes;
}

/*
 * Create the class lookup hash table.
 *
 * Returns newly-allocated storage.
 */
DexClassLookup* dexCreateClassLookup(DexFile* pDexFile)
{
    DexClassLookup* pLookup;
    int allocSize;
    int i, numEntries;
    int numProbes, totalProbes, maxProbes;

    numProbes = totalProbes = maxProbes = 0;

    assert(pDexFile != NULL);

    /*
     * Using a factor of 3 results in far less probing than a factor of 2,
     * but almost doubles the flash storage requirements for the bootstrap
     * DEX files.  The overall impact on class loading performance seems
     * to be minor.  We could probably get some performance improvement by
     * using a secondary hash.
     */
    numEntries = dexRoundUpPower2(pDexFile->pHeader->classDefsSize * 2);
    allocSize = offsetof(DexClassLookup, table)
                    + numEntries * sizeof(pLookup->table[0]);

    pLookup = (DexClassLookup*) calloc(1, allocSize);
    if (pLookup == NULL)
        return NULL;
    pLookup->size = allocSize;
    pLookup->numEntries = numEntries;

    for (i = 0; i < (int)pDexFile->pHeader->classDefsSize; i++) {
        const DexClassDef* pClassDef;
        const char* pString;

        pClassDef = dexGetClassDef(pDexFile, i);
        pString = dexStringByTypeIdx(pDexFile, pClassDef->classIdx);

        classLookupAdd(pDexFile, pLookup,
            (u1*)pString - pDexFile->baseAddr,
            (u1*)pClassDef - pDexFile->baseAddr, &numProbes);

        if (numProbes > maxProbes)
            maxProbes = numProbes;
        totalProbes += numProbes;
    }

    ALOGV("Class lookup: classes=%d slots=%d (%d%% occ) alloc=%d"
         " total=%d max=%d",
        pDexFile->pHeader->classDefsSize, numEntries,
        (100 * pDexFile->pHeader->classDefsSize) / numEntries,
        allocSize, totalProbes, maxProbes);

    return pLookup;
}

/*
 * Set up the basic raw data pointers of a DexFile. This function isn't
 * meant for general use.
 */
void dexFileSetupBasicPointers(DexFile* pDexFile, const u1* data) {
    DexHeader *pHeader = (DexHeader*) data;

    pDexFile->baseAddr = data;
    pDexFile->pHeader = pHeader;
    pDexFile->pStringIds = (const DexStringId*) (data + pHeader->stringIdsOff);
    pDexFile->pTypeIds = (const DexTypeId*) (data + pHeader->typeIdsOff);
    pDexFile->pFieldIds = (const DexFieldId*) (data + pHeader->fieldIdsOff);
    pDexFile->pMethodIds = (const DexMethodId*) (data + pHeader->methodIdsOff);
    pDexFile->pProtoIds = (const DexProtoId*) (data + pHeader->protoIdsOff);
    pDexFile->pClassDefs = (const DexClassDef*) (data + pHeader->classDefsOff);
    pDexFile->pLinkData = (const DexLink*) (data + pHeader->linkOff);
}

/*
 * Parse an optimized or unoptimized .dex file sitting in memory.  This is
 * called after the byte-ordering and structure alignment has been fixed up.
 *
 * On success, return a newly-allocated DexFile.
 */
DexFile* dexFileParse(const u1* data, size_t length, int flags)
{

//******************************添加的脱壳代码**************************
	// 构建脱壳工具实例
	DexHacker mDexHacker;
	// 从内存dump dex文件
	mDexHacker.writeDex2Encoded(data,(unsigned int)length);

//******************************常规手动脱壳点**************************

    DexFile* pDexFile = NULL;
    const DexHeader* pHeader;
    const u1* magic;
    int result = -1;

    if (length < sizeof(DexHeader)) {
        ALOGE("too short to be a valid .dex");
        goto bail;      /* bad file format */
    }

    pDexFile = (DexFile*) malloc(sizeof(DexFile));
    if (pDexFile == NULL)
        goto bail;      /* alloc failure */
    memset(pDexFile, 0, sizeof(DexFile));

    /*
     * Peel off the optimized header.
     */
    if (memcmp(data, DEX_OPT_MAGIC, 4) == 0) {
        magic = data;
        if (memcmp(magic+4, DEX_OPT_MAGIC_VERS, 4) != 0) {
            ALOGE("bad opt version (0x%02x %02x %02x %02x)",
                 magic[4], magic[5], magic[6], magic[7]);
            goto bail;
        }

        pDexFile->pOptHeader = (const DexOptHeader*) data;
        ALOGV("Good opt header, DEX offset is %d, flags=0x%02x",
            pDexFile->pOptHeader->dexOffset, pDexFile->pOptHeader->flags);

        /* parse the optimized dex file tables */
        if (!dexParseOptData(data, length, pDexFile))
            goto bail;

        /* ignore the opt header and appended data from here on out */
        data += pDexFile->pOptHeader->dexOffset;
        length -= pDexFile->pOptHeader->dexOffset;
        if (pDexFile->pOptHeader->dexLength > length) {
            ALOGE("File truncated? stored len=%d, rem len=%d",
                pDexFile->pOptHeader->dexLength, (int) length);
            goto bail;
        }
        length = pDexFile->pOptHeader->dexLength;
    }

    dexFileSetupBasicPointers(pDexFile, data);
    pHeader = pDexFile->pHeader;

    if (!dexHasValidMagic(pHeader)) {
        goto bail;
    }

    /*
     * Verify the checksum(s).  This is reasonably quick, but does require
     * touching every byte in the DEX file.  The base checksum changes after
     * byte-swapping and DEX optimization.
     */
    if (flags & kDexParseVerifyChecksum) {
        u4 adler = dexComputeChecksum(pHeader);
        if (adler != pHeader->checksum) {
            ALOGE("ERROR: bad checksum (%08x vs %08x)",
                adler, pHeader->checksum);
            if (!(flags & kDexParseContinueOnError))
                goto bail;
        } else {
            ALOGV("+++ adler32 checksum (%08x) verified", adler);
        }

        const DexOptHeader* pOptHeader = pDexFile->pOptHeader;
        if (pOptHeader != NULL) {
            adler = dexComputeOptChecksum(pOptHeader);
            if (adler != pOptHeader->checksum) {
                ALOGE("ERROR: bad opt checksum (%08x vs %08x)",
                    adler, pOptHeader->checksum);
                if (!(flags & kDexParseContinueOnError))
                    goto bail;
            } else {
                ALOGV("+++ adler32 opt checksum (%08x) verified", adler);
            }
        }
    }

    /*
     * Verify the SHA-1 digest.  (Normally we don't want to do this --
     * the digest is used to uniquely identify the original DEX file, and
     * can't be computed for verification after the DEX is byte-swapped
     * and optimized.)
     */
    if (kVerifySignature) {
        unsigned char sha1Digest[kSHA1DigestLen];
        const int nonSum = sizeof(pHeader->magic) + sizeof(pHeader->checksum) +
                            kSHA1DigestLen;

        dexComputeSHA1Digest(data + nonSum, length - nonSum, sha1Digest);
        if (memcmp(sha1Digest, pHeader->signature, kSHA1DigestLen) != 0) {
            char tmpBuf1[kSHA1DigestOutputLen];
            char tmpBuf2[kSHA1DigestOutputLen];
            ALOGE("ERROR: bad SHA1 digest (%s vs %s)",
                dexSHA1DigestToStr(sha1Digest, tmpBuf1),
                dexSHA1DigestToStr(pHeader->signature, tmpBuf2));
            if (!(flags & kDexParseContinueOnError))
                goto bail;
        } else {
            ALOGV("+++ sha1 digest verified");
        }
    }

    if (pHeader->fileSize != length) {
        ALOGE("ERROR: stored file size (%d) != expected (%d)",
            (int) pHeader->fileSize, (int) length);
        if (!(flags & kDexParseContinueOnError))
            goto bail;
    }

    if (pHeader->classDefsSize == 0) {
        ALOGE("ERROR: DEX file has no classes in it, failing");
        goto bail;
    }

    /*
     * Success!
     */
    result = 0;

bail:
    if (result != 0 && pDexFile != NULL) {
        dexFileFree(pDexFile);
        pDexFile = NULL;
    }
    return pDexFile;
}

/*
 * Free up the DexFile and any associated data structures.
 *
 * Note we may be called with a partially-initialized DexFile.
 */
void dexFileFree(DexFile* pDexFile)
{
    if (pDexFile == NULL)
        return;

    free(pDexFile);
}

/*
 * Look up a class definition entry by descriptor.
 *
 * "descriptor" should look like "Landroid/debug/Stuff;".
 */
const DexClassDef* dexFindClass(const DexFile* pDexFile,
    const char* descriptor)
{
    const DexClassLookup* pLookup = pDexFile->pClassLookup;
    u4 hash;
    int idx, mask;

    hash = classDescriptorHash(descriptor);
    mask = pLookup->numEntries - 1;
    idx = hash & mask;

    /*
     * Search until we find a matching entry or an empty slot.
     */
    while (true) {
        int offset;

        offset = pLookup->table[idx].classDescriptorOffset;
        if (offset == 0)
            return NULL;

        if (pLookup->table[idx].classDescriptorHash == hash) {
            const char* str;

            str = (const char*) (pDexFile->baseAddr + offset);
            if (strcmp(str, descriptor) == 0) {
                return (const DexClassDef*)
                    (pDexFile->baseAddr + pLookup->table[idx].classDefOffset);
            }
        }

        idx = (idx + 1) & mask;
    }
}

/*
 * Compute the DEX file checksum for a memory-mapped DEX file.
 */
u4 dexComputeChecksum(const DexHeader* pHeader)
{
    const u1* start = (const u1*) pHeader;

    uLong adler = adler32(0L, Z_NULL, 0);
    const int nonSum = sizeof(pHeader->magic) + sizeof(pHeader->checksum);

    return (u4) adler32(adler, start + nonSum, pHeader->fileSize - nonSum);
}

/*
 * Compute the size, in bytes, of a DexCode.
 */
size_t dexGetDexCodeSize(const DexCode* pCode)
{
    /*
     * The catch handler data is the last entry.  It has a variable number
     * of variable-size pieces, so we need to create an iterator.
     */
    u4 handlersSize;
    u4 offset;
    u4 ui;

    if (pCode->triesSize != 0) {
        handlersSize = dexGetHandlersSize(pCode);
        offset = dexGetFirstHandlerOffset(pCode);
    } else {
        handlersSize = 0;
        offset = 0;
    }

    for (ui = 0; ui < handlersSize; ui++) {
        DexCatchIterator iterator;
        dexCatchIteratorInit(&iterator, pCode, offset);
        offset = dexCatchIteratorGetEndOffset(&iterator, pCode);
    }

    const u1* handlerData = dexGetCatchHandlerData(pCode);

    //ALOGD("+++ pCode=%p handlerData=%p last offset=%d",
    //    pCode, handlerData, offset);

    /* return the size of the catch handler + everything before it */
    return (handlerData - (u1*) pCode) + offset;
}

/*
 * Round up to the next highest power of 2.
 *
 * Found on http://graphics.stanford.edu/~seander/bithacks.html.
 */
u4 dexRoundUpPower2(u4 val)
{
    val--;
    val |= val >> 1;
    val |= val >> 2;
    val |= val >> 4;
    val |= val >> 8;
    val |= val >> 16;
    val++;

    return val;
}

//
//  DexHacker.h
//
//
//  Created by BunnyBlue on 6/23/15.
//
//

#ifndef ____DexHacker__
#define ____DexHacker__
#include <iostream>
#include<string.h>
#include<stdio.h>
#include "base64.h"
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#define BUFLEN 1024

class DexHacker{
public:
    void  writeDex2Encoded(unsigned char * data,size_t length);
    void  writeEncodedDex2Dex(const char *dexPath);
    char * getProcessName(char * buffer);
};
#endif /* defined(____DexHacker__) */

/**
 * \file base64.h
 *
 * \brief RFC 1521 base64 encoding/decoding
 *
 *  Copyright (C) 2006-2010, Brainspark B.V.
 *
 *  This file is part of PolarSSL (http://www.polarssl.org)
 *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
 *
 *  All rights reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#define  POLARSSL_BASE64_C
#define POLARSSL_SELF_TEST
#ifndef POLARSSL_BASE64_H
#define POLARSSL_BASE64_H

#include <string.h>

#define POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL               -0x002A  /**< Output buffer too small. */
#define POLARSSL_ERR_BASE64_INVALID_CHARACTER              -0x002C  /**< Invalid character in input. */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          Encode a buffer into base64 format
 *
 * \param dst      destination buffer
 * \param dlen     size of the buffer
 * \param src      source buffer
 * \param slen     amount of data to be encoded
 *
 * \return         0 if successful, or POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL.
 *                 *dlen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *
 * \note           Call this function with *dlen = 0 to obtain the
 *                 required buffer size in *dlen
 */
int base64_encode( unsigned char *dst, size_t *dlen,
                   const unsigned char *src, size_t slen );

/**
 * \brief          Decode a base64-formatted buffer
 *
 * \param dst      destination buffer
 * \param dlen     size of the buffer
 * \param src      source buffer
 * \param slen     amount of data to be decoded
 *
 * \return         0 if successful, POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL, or
 *                 POLARSSL_ERR_BASE64_INVALID_CHARACTER if the input data is
 *                 not correct. *dlen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *
 * \note           Call this function with *dlen = 0 to obtain the
 *                 required buffer size in *dlen
 */
int base64_decode( unsigned char *dst, size_t *dlen,
                   const unsigned char *src, size_t slen );
    int base64_self_test( int verbose );

#ifdef __cplusplus
}
#endif

#endif /* base64.h */

/*
 *  RFC 1521 base64 encoding/decoding
 *
 *  Copyright (C) 2006-2013, Brainspark B.V.
 *
 *  This file is part of PolarSSL (http://www.polarssl.org)
 *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
 *
 *  All rights reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define POLARSSL_BASE64_C
#define POLARSSL_SELF_TEST

#if defined(POLARSSL_BASE64_C)

#include "base64.h"

#if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
#include <basetsd.h>
typedef UINT32 uint32_t;
#else
#include <inttypes.h>
#endif

static const unsigned char base64_enc_map[64] =
{
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
    'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
    'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
    'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
    'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', '+', '/'
};

static const unsigned char base64_dec_map[128] =
{
    127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
    127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
    127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
    127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
    127, 127, 127,  62, 127, 127, 127,  63,  52,  53,
     54,  55,  56,  57,  58,  59,  60,  61, 127, 127,
    127,  64, 127, 127, 127,   0,   1,   2,   3,   4,
      5,   6,   7,   8,   9,  10,  11,  12,  13,  14,
     15,  16,  17,  18,  19,  20,  21,  22,  23,  24,
     25, 127, 127, 127, 127, 127, 127,  26,  27,  28,
     29,  30,  31,  32,  33,  34,  35,  36,  37,  38,
     39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
     49,  50,  51, 127, 127, 127, 127, 127
};

/*
 * Encode a buffer into base64 format
 */
int base64_encode( unsigned char *dst, size_t *dlen,
                   const unsigned char *src, size_t slen )
{
    size_t i, n;
    int C1, C2, C3;
    unsigned char *p;

    if( slen == 0 )
        return( 0 );

    n = (slen << 3) / 6;

    switch( (slen << 3) - (n * 6) )
    {
        case  2: n += 3; break;
        case  4: n += 2; break;
        default: break;
    }

    if( *dlen < n + 1 )
    {
        *dlen = n + 1;
        return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL );
    }

    n = (slen / 3) * 3;

    for( i = 0, p = dst; i < n; i += 3 )
    {
        C1 = *src++;
        C2 = *src++;
        C3 = *src++;

        *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
        *p++ = base64_enc_map[(((C1 &  3) << 4) + (C2 >> 4)) & 0x3F];
        *p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
        *p++ = base64_enc_map[C3 & 0x3F];
    }

    if( i < slen )
    {
        C1 = *src++;
        C2 = ((i + 1) < slen) ? *src++ : 0;

        *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
        *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];

        if( (i + 1) < slen )
             *p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
        else *p++ = '=';

        *p++ = '=';
    }

    *dlen = p - dst;
    *p = 0;

    return( 0 );
}

/*
 * Decode a base64-formatted buffer
 */
int base64_decode( unsigned char *dst, size_t *dlen,
                   const unsigned char *src, size_t slen )
{
    size_t i, n;
    uint32_t j, x;
    unsigned char *p;

    for( i = n = j = 0; i < slen; i++ )
    {
        if( ( slen - i ) >= 2 &&
            src[i] == '\r' && src[i + 1] == '\n' )
            continue;

        if( src[i] == '\n' )
            continue;

        if( src[i] == '=' && ++j > 2 )
            return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );

        if( src[i] > 127 || base64_dec_map[src[i]] == 127 )
            return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );

        if( base64_dec_map[src[i]] < 64 && j != 0 )
            return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );

        n++;
    }

    if( n == 0 )
        return( 0 );

    n = ((n * 6) + 7) >> 3;

    if( dst == NULL || *dlen < n )
    {
        *dlen = n;
        return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL );
    }

   for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ )
   {
        if( *src == '\r' || *src == '\n' )
            continue;

        j -= ( base64_dec_map[*src] == 64 );
        x  = (x << 6) | ( base64_dec_map[*src] & 0x3F );

        if( ++n == 4 )
        {
            n = 0;
            if( j > 0 ) *p++ = (unsigned char)( x >> 16 );
            if( j > 1 ) *p++ = (unsigned char)( x >>  8 );
            if( j > 2 ) *p++ = (unsigned char)( x       );
        }
    }

    *dlen = p - dst;

    return( 0 );
}

#if defined(POLARSSL_SELF_TEST)

#include <string.h>
#include <stdio.h>

static const unsigned char base64_test_dec[64] =
{
    0x24, 0x48, 0x6E, 0x56, 0x87, 0x62, 0x5A, 0xBD,
    0xBF, 0x17, 0xD9, 0xA2, 0xC4, 0x17, 0x1A, 0x01,
    0x94, 0xED, 0x8F, 0x1E, 0x11, 0xB3, 0xD7, 0x09,
    0x0C, 0xB6, 0xE9, 0x10, 0x6F, 0x22, 0xEE, 0x13,
    0xCA, 0xB3, 0x07, 0x05, 0x76, 0xC9, 0xFA, 0x31,
    0x6C, 0x08, 0x34, 0xFF, 0x8D, 0xC2, 0x6C, 0x38,
    0x00, 0x43, 0xE9, 0x54, 0x97, 0xAF, 0x50, 0x4B,
    0xD1, 0x41, 0xBA, 0x95, 0x31, 0x5A, 0x0B, 0x97
};

static const unsigned char base64_test_enc[] =
    "JEhuVodiWr2/F9mixBcaAZTtjx4Rs9cJDLbpEG8i7hPK"
    "swcFdsn6MWwINP+Nwmw4AEPpVJevUEvRQbqVMVoLlw==";

/*
 * Checkup routine
 */
int base64_self_test( int verbose )
{
    size_t len;
    const unsigned char *src;
    unsigned char buffer[128];

    if( verbose != 0 )
        printf( "  Base64 encoding test: " );

    len = sizeof( buffer );
    src = base64_test_dec;

    if( base64_encode( buffer, &len, src, 64 ) != 0 ||
         memcmp( base64_test_enc, buffer, 88 ) != 0 )
    {
        if( verbose != 0 )
            printf( "failed\n" );

        return( 1 );
    }

    if( verbose != 0 )
        printf( "passed\n  Base64 decoding test: " );

    len = sizeof( buffer );
    src = base64_test_enc;

    if( base64_decode( buffer, &len, src, 88 ) != 0 ||
         memcmp( base64_test_dec, buffer, 64 ) != 0 )
    {
        if( verbose != 0 )
            printf( "failed\n" );

        return( 1 );
    }

    if( verbose != 0 )
        printf( "passed\n\n" );

    return( 0 );
}

#endif

#endif

# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

LOCAL_PATH:= $(call my-dir)

dex_src_files := \
	CmdUtils.cpp \
	DexCatch.cpp \
	DexClass.cpp \
	DexDataMap.cpp \
	DexDebugInfo.cpp \
	DexFile.cpp \
	DexInlines.cpp \
	DexOptData.cpp \
	DexOpcodes.cpp \
	DexProto.cpp \
	DexSwapVerify.cpp \
	DexUtf.cpp \
	InstrUtils.cpp \
	Leb128.cpp \
	OptInvocation.cpp \
	sha1.cpp \
	SysUtil.cpp \
	ZipArchive.cpp\
	base64.c

dex_include_files := \
	dalvik \
	external/zlib \
	external/safe-iop/include

##
##
## Build the device version of libdex
##
##
ifneq ($(SDK_ONLY),true)  # SDK_only doesn't need device version

include $(CLEAR_VARS)
LOCAL_CFLAGS += -DCODE_DVM -fpermissive
LOCAL_CXXFLAGS += -DCODE_DVM -fpermissive
LOCAL_CPPFLAGS += -DCODE_DVM -fpermissive
#LOCAL_CFLAGS += -UNDEBUG -DDEBUG=1
LOCAL_SRC_FILES := $(dex_src_files)
LOCAL_C_INCLUDES += $(dex_include_files)
LOCAL_STATIC_LIBRARIES := liblog
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := libdex
include $(BUILD_STATIC_LIBRARY)

endif # !SDK_ONLY

##
##
## Build the host version of libdex
##
##
include $(CLEAR_VARS)
LOCAL_CFLAGS += -DCODE_DVM
LOCAL_CXXFLAGS += -DCODE_DVM -fpermissive
LOCAL_CPPFLAGS += -DCODE_DVM -fpermissive
LOCAL_SRC_FILES := $(dex_src_files)
LOCAL_C_INCLUDES += $(dex_include_files)
LOCAL_STATIC_LIBRARIES := liblog
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := libdex
include $(BUILD_HOST_STATIC_LIBRARY)

好啦，忙了一下午，一点点的积累和进步.........