从内存中加载动态库

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typedef BOOL (__stdcall *ProcDllMain)(HINSTANCE, DWORD, LPVOID );

class CMemLoadDll
{
public:
CMemLoadDll();
~CMemLoadDll();
BOOL MemLoadLibrary( void* lpFileData , int DataLength); // Dll file data buffer
FARPROC MemGetProcAddress(LPCSTR lpProcName);
private:
BOOL isLoadOk;
BOOL CheckDataValide(void* lpFileData, int DataLength);
int CalcTotalImageSize();
void CopyDllDatas(void* pDest, void* pSrc);
BOOL FillRavAddress(void* pBase);
void DoRelocation(void* pNewBase);
int GetAlignedSize(int Origin, int Alignment);
private:
ProcDllMain pDllMain;

private:
DWORD pImageBase;
PIMAGE_DOS_HEADER pDosHeader;
PIMAGE_NT_HEADERS pNTHeader;
PIMAGE_SECTION_HEADER pSectionHeader;
};

CMemLoadDll::CMemLoadDll()
{
isLoadOk = FALSE;
pImageBase = NULL;
pDllMain = NULL;
}
CMemLoadDll::~CMemLoadDll()
{
if(isLoadOk)
{
ASSERT(pImageBase != NULL);
ASSERT(pDllMain != NULL);
//脱钩，准备卸载dll
pDllMain((HINSTANCE)pImageBase,DLL_PROCESS_DETACH,0);
VirtualFree((LPVOID)pImageBase, 0, MEM_RELEASE);
}
}

//MemLoadLibrary函数从内存缓冲区数据中加载一个dll到当前进程的地址空间，缺省位置0x10000000
//返回值：成功返回TRUE , 失败返回FALSE
//lpFileData: 存放dll文件数据的缓冲区
//DataLength: 缓冲区中数据的总长度
BOOL CMemLoadDll::MemLoadLibrary(void* lpFileData, int DataLength)
{
if(pImageBase != NULL)
{
return FALSE; //已经加载一个dll，还没有释放，不能加载新的dll
}
//检查数据有效性，并初始化
if(!CheckDataValide(lpFileData, DataLength))return FALSE;
//计算所需的加载空间
int ImageSize = CalcTotalImageSize();
if(ImageSize == 0) return FALSE;

// 分配虚拟内存
void *pMemoryAddress = VirtualAlloc((LPVOID)0x10000000, ImageSize,
     MEM_COMMIT|MEM_RESERVE, PAGE_EXECUTE_READWRITE);
if(pMemoryAddress == NULL) return FALSE;
else
{
CopyDllDatas(pMemoryAddress, lpFileData); //复制dll数据，并对齐每个段
//重定位信息
if(pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress >0
   && pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].Size>0)
{
   DoRelocation(pMemoryAddress);
}
//填充引入地址表
if(!FillRavAddress(pMemoryAddress)) //修正引入地址表失败
{
   VirtualFree(pMemoryAddress,0,MEM_RELEASE);
   return FALSE;
}
//修改页属性。应该根据每个页的属性单独设置其对应内存页的属性。这里简化一下。
//统一设置成一个属性PAGE_EXECUTE_READWRITE
unsigned long old;
VirtualProtect(pMemoryAddress, ImageSize, PAGE_EXECUTE_READWRITE,&old);
}
//修正基地址
pNTHeader->OptionalHeader.ImageBase = (DWORD)pMemoryAddress;

//接下来要调用一下dll的入口函数，做初始化工作。
pDllMain = (ProcDllMain)(pNTHeader->OptionalHeader.AddressOfEntryPoint +(DWORD) pMemoryAddress);
BOOL InitResult = pDllMain((HINSTANCE)pMemoryAddress,DLL_PROCESS_ATTACH,0);
if(!InitResult) //初始化失败
{
pDllMain((HINSTANCE)pMemoryAddress,DLL_PROCESS_DETACH,0);
VirtualFree(pMemoryAddress,0,MEM_RELEASE);
pDllMain = NULL;
return FALSE;
}

isLoadOk = TRUE;
pImageBase = (DWORD)pMemoryAddress;
return TRUE;
}

//MemGetProcAddress函数从dll中获取指定函数的地址
//返回值：成功返回函数地址 , 失败返回NULL
//lpProcName: 要查找函数的名字或者序号
FARPROC CMemLoadDll::MemGetProcAddress(LPCSTR lpProcName)
{
if(pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress == 0 ||
pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].Size == 0)
return NULL;
if(!isLoadOk) return NULL;

DWORD OffsetStart = pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress;
DWORD Size = pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].Size;

PIMAGE_EXPORT_DIRECTORY pExport = (PIMAGE_EXPORT_DIRECTORY)((DWORD)pImageBase + pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress);
int iBase = pExport->Base;
int iNumberOfFunctions = pExport->NumberOfFunctions;
int iNumberOfNames = pExport->NumberOfNames; //<= iNumberOfFunctions
LPDWORD pAddressOfFunctions = (LPDWORD)(pExport->AddressOfFunctions + pImageBase);
LPWORD pAddressOfOrdinals = (LPWORD)(pExport->AddressOfNameOrdinals + pImageBase);
LPDWORD pAddressOfNames = (LPDWORD)(pExport->AddressOfNames + pImageBase);

int iOrdinal = -1;

if(((DWORD)lpProcName & 0xFFFF0000) == 0) //IT IS A ORDINAL!
{
iOrdinal = (DWORD)lpProcName & 0x0000FFFF - iBase;
}
else //use name
{
int iFound = -1;

for(int i=0;i<iNumberOfNames;i++)
{
   char* pName= (char* )(pAddressOfNames[i] + pImageBase);
   if(strcmp(pName, lpProcName) == 0)
   {
    iFound = i; break;
   }
}
if(iFound >= 0)
{
   iOrdinal = (int)(pAddressOfOrdinals[iFound]);
}
}

if(iOrdinal < 0 || iOrdinal >= iNumberOfFunctions ) return NULL;
else
{
DWORD pFunctionOffset = pAddressOfFunctions[iOrdinal];
if(pFunctionOffset > OffsetStart && pFunctionOffset < (OffsetStart+Size))//maybe Export Forwarding
return NULL;
else return (FARPROC)(pFunctionOffset + pImageBase);
}

}

// 重定向PE用到的地址
void CMemLoadDll::DoRelocation( void *NewBase)
{
/* 重定位表的结构：
// DWORD sectionAddress, DWORD size (包括本节需要重定位的数据)
// 例如 1000节需要修正5个重定位数据的话，重定位表的数据是
// 00 10 00 00   14 00 00 00      xxxx xxxx xxxx xxxx xxxx 0000
// -----------   -----------      ----
// 给出节的偏移总尺寸=8+6*2     需要修正的地址           用于对齐4字节
// 重定位表是若干个相连，如果address 和 size都是0 表示结束
// 需要修正的地址是12位的，高4位是形态字，intel cpu下是3
*/
//假设NewBase是0x600000,而文件中设置的缺省ImageBase是0x400000,则修正偏移量就是0x200000
DWORD Delta = (DWORD)NewBase - pNTHeader->OptionalHeader.ImageBase;

//注意重定位表的位置可能和硬盘文件中的偏移地址不同，应该使用加载后的地址
PIMAGE_BASE_RELOCATION pLoc = (PIMAGE_BASE_RELOCATION)((unsigned long)NewBase
+ pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress);
while((pLoc->VirtualAddress + pLoc->SizeOfBlock) != 0) //开始扫描重定位表
{
WORD *pLocData = (WORD *)((int)pLoc + sizeof(IMAGE_BASE_RELOCATION));
//计算本节需要修正的重定位项（地址）的数目
int NumberOfReloc = (pLoc->SizeOfBlock - sizeof(IMAGE_BASE_RELOCATION))/sizeof(WORD);
for( int i=0 ; i < NumberOfReloc; i++)
{
   if( (DWORD)(pLocData[i] & 0xF000) == 0x00003000) //这是一个需要修正的地址
   {
    // 举例：
    // pLoc->VirtualAddress = 0x1000;
    // pLocData[i] = 0x313E; 表示本节偏移地址0x13E处需要修正
    // 因此 pAddress = 基地址 + 0x113E
    // 里面的内容是 A1 ( 0c d4 02 10) 汇编代码是： mov eax , [1002d40c]
    // 需要修正1002d40c这个地址
    DWORD * pAddress = (DWORD *)((unsigned long)NewBase + pLoc->VirtualAddress + (pLocData[i] & 0x0FFF));
    *pAddress += Delta;
   }
}
//转移到下一个节进行处理
pLoc = (PIMAGE_BASE_RELOCATION)((DWORD)pLoc + pLoc->SizeOfBlock);
}
}

//填充引入地址表
BOOL CMemLoadDll::FillRavAddress(void *pImageBase)
{
// 引入表实际上是一个 IMAGE_IMPORT_DESCRIPTOR 结构数组，全部是0表示结束
// 数组定义如下：
//
    // DWORD   OriginalFirstThunk;         // 0表示结束，否则指向未绑定的IAT结构数组
    // DWORD   TimeDateStamp;
    // DWORD   ForwarderChain;             // -1 if no forwarders
    // DWORD   Name;                       // 给出dll的名字
    // DWORD   FirstThunk;                 // 指向IAT结构数组的地址(绑定后，这些IAT里面就是实际的函数地址)
unsigned long Offset = pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress ;
if(Offset == 0) return TRUE; //No Import Table
PIMAGE_IMPORT_DESCRIPTOR pID = (PIMAGE_IMPORT_DESCRIPTOR)((unsigned long) pImageBase + Offset);
while(pID->Characteristics != 0 )
{
PIMAGE_THUNK_DATA pRealIAT = (PIMAGE_THUNK_DATA)((unsigned long)pImageBase + pID->FirstThunk);
PIMAGE_THUNK_DATA pOriginalIAT = (PIMAGE_THUNK_DATA)((unsigned long)pImageBase + pID->OriginalFirstThunk);
//获取dll的名字
char buf[256]; //dll name;
BYTE* pName = (BYTE*)((unsigned long)pImageBase + pID->Name);
for(int i=0;i<256;i++)
{
   if(pName[i] == 0)break;
   buf[i] = pName[i];
}
if(i>=256) return FALSE; // bad dll name
else buf[i] = 0;
HMODULE hDll = GetModuleHandle(buf);
if(hDll == NULL)return FALSE; //NOT FOUND DLL
//获取DLL中每个导出函数的地址，填入IAT
//每个IAT结构是：
// union { PBYTE ForwarderString;
        //   PDWORD Function;
        //   DWORD Ordinal;
        //   PIMAGE_IMPORT_BY_NAME AddressOfData;
// } u1;
// 长度是一个DWORD ，正好容纳一个地址。
for(i=0; ;i++)
{
   if(pOriginalIAT[i].u1.Function == 0)break;
   FARPROC lpFunction = NULL;
   if(pOriginalIAT[i].u1.Ordinal & IMAGE_ORDINAL_FLAG) //这里的值给出的是导出序号
   {
    lpFunction = GetProcAddress(hDll, (LPCSTR)(pOriginalIAT[i].u1.Ordinal & 0x0000FFFF));
   }
   else //按照名字导入
   {
    //获取此IAT项所描述的函数名称
    PIMAGE_IMPORT_BY_NAME pByName = (PIMAGE_IMPORT_BY_NAME)
     ((DWORD)pImageBase + (DWORD)(pOriginalIAT[i].u1.AddressOfData));
//    if(pByName->Hint !=0)
//     lpFunction = GetProcAddress(hDll, (LPCSTR)pByName->Hint);
//    else
     lpFunction = GetProcAddress(hDll, (char *)pByName->Name);
   }
   if(lpFunction != NULL)   //找到了！
   {
    pRealIAT[i].u1.Function = (PDWORD) lpFunction;
   }
   else return FALSE;
}

//move to next
pID = (PIMAGE_IMPORT_DESCRIPTOR)( (DWORD)pID + sizeof(IMAGE_IMPORT_DESCRIPTOR));
}
return TRUE;
}

//CheckDataValide函数用于检查缓冲区中的数据是否有效的dll文件
//返回值：是一个可执行的dll则返回TRUE，否则返回FALSE。
//lpFileData: 存放dll数据的内存缓冲区
//DataLength: dll文件的长度
BOOL CMemLoadDll::CheckDataValide(void* lpFileData, int DataLength)
{
//检查长度
if(DataLength < sizeof(IMAGE_DOS_HEADER)) return FALSE;
pDosHeader = (PIMAGE_DOS_HEADER)lpFileData; // DOS头
//检查dos头的标记
if(pDosHeader->e_magic != IMAGE_DOS_SIGNATURE) return FALSE; //0x5A4D : MZ

//检查长度
if((DWORD)DataLength < (pDosHeader->e_lfanew + sizeof(IMAGE_NT_HEADERS)) ) return FALSE;
//取得pe头
pNTHeader = (PIMAGE_NT_HEADERS)( (unsigned long)lpFileData + pDosHeader->e_lfanew); // PE头
//检查pe头的合法性
if(pNTHeader->Signature != IMAGE_NT_SIGNATURE) return FALSE; //0x00004550 : PE00
if((pNTHeader->FileHeader.Characteristics & IMAGE_FILE_DLL) == 0) //0x2000 : File is a DLL
return FALSE;
if((pNTHeader->FileHeader.Characteristics & IMAGE_FILE_EXECUTABLE_IMAGE) == 0) //0x0002 : 指出文件可以运行
return FALSE;
if(pNTHeader->FileHeader.SizeOfOptionalHeader != sizeof(IMAGE_OPTIONAL_HEADER)) return FALSE;

//取得节表（段表）
pSectionHeader = (PIMAGE_SECTION_HEADER)((int)pNTHeader + sizeof(IMAGE_NT_HEADERS));
//验证每个节表的空间
for(int i=0; i< pNTHeader->FileHeader.NumberOfSections; i++)
{
if((pSectionHeader[i].PointerToRawData + pSectionHeader[i].SizeOfRawData) > (DWORD)DataLength)return FALSE;
}
return TRUE;
}

//计算对齐边界
int CMemLoadDll::GetAlignedSize(int Origin, int Alignment)
{
return (Origin + Alignment - 1) / Alignment * Alignment;
}
//计算整个dll映像文件的尺寸
int CMemLoadDll::CalcTotalImageSize()
{
int Size;
if(pNTHeader == NULL)return 0;
int nAlign = pNTHeader->OptionalHeader.SectionAlignment; //段对齐字节数

// 计算所有头的尺寸。包括dos, coff, pe头和段表的大小
Size = GetAlignedSize(pNTHeader->OptionalHeader.SizeOfHeaders, nAlign);
// 计算所有节的大小
for(int i=0; i < pNTHeader->FileHeader.NumberOfSections; ++i)
{
//得到该节的大小
int CodeSize = pSectionHeader[i].Misc.VirtualSize ;
int LoadSize = pSectionHeader[i].SizeOfRawData;
int MaxSize = (LoadSize > CodeSize)?(LoadSize):(CodeSize);

int SectionSize = GetAlignedSize(pSectionHeader[i].VirtualAddress + MaxSize, nAlign);
if(Size < SectionSize)
Size = SectionSize; //Use the Max;
}
return Size;
}
//CopyDllDatas函数将dll数据复制到指定内存区域，并对齐所有节
//pSrc: 存放dll数据的原始缓冲区
//pDest:目标内存地址
void CMemLoadDll::CopyDllDatas(void* pDest, void* pSrc)
{
// 计算需要复制的PE头+段表字节数
int HeaderSize = pNTHeader->OptionalHeader.SizeOfHeaders;
int SectionSize = pNTHeader->FileHeader.NumberOfSections * sizeof(IMAGE_SECTION_HEADER);
int MoveSize = HeaderSize + SectionSize;
//复制头和段信息
memmove(pDest, pSrc, MoveSize);

//复制每个节
for(int i=0; i < pNTHeader->FileHeader.NumberOfSections; ++i)
{
if(pSectionHeader[i].VirtualAddress == 0 || pSectionHeader[i].SizeOfRawData == 0)continue;
// 定位该节在内存中的位置
void *pSectionAddress = (void *)((unsigned long)pDest + pSectionHeader[i].VirtualAddress);
// 复制段数据到虚拟内存
memmove((void *)pSectionAddress,
(void *)((DWORD)pSrc + pSectionHeader[i].PointerToRawData),
pSectionHeader[i].SizeOfRawData);
}

//修正指针，指向新分配的内存
//新的dos头
pDosHeader = (PIMAGE_DOS_HEADER)pDest;
//新的pe头地址
pNTHeader = (PIMAGE_NT_HEADERS)((int)pDest + (pDosHeader->e_lfanew));
//新的节表地址
pSectionHeader = (PIMAGE_SECTION_HEADER)((int)pNTHeader + sizeof(IMAGE_NT_HEADERS));
return ;
}

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