如何在 C 中读取导入目录表

Question

我正在尝试在 C++ 中构建一个 PE 查看器，如果我尝试在导入目录表中输出库的名称，它似乎会崩溃。看来我没有得到程序使用的 DLL 的正确指针。

HANDLE handle = CreateFile("messagebox.exe",GENERIC_READ,0,0,OPEN_EXISTING,
                              FILE_ATTRIBUTE_NORMAL,0);
DWORD size = GetFileSize(handle,NULL);
PVOID virtualpointer = VirtualAlloc(NULL,size,MEM_COMMIT,PAGE_READWRITE);
state = ReadFile(handle,virtualpointer,size,&byteread,NULL);
CloseHandle(handle);
PIMAGE_NT_HEADERS ntheaders = PIMAGE_NT_HEADERS(PCHAR(vpointer) + 
                                     PIMAGE_DOS_HEADER(vpointer)->e_lfanew);
handle = GetCurrentProcess();
DWORD EntryAddr = ntheaders->OptionalHeader.ImageBase + 
                       ntheaders->OptionalHeader.AddressOfEntryPoint;

DWORD importdir = 
       (DWORD) &(ntheaders->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT]);

DWORD va = (DWORD)(ntheaders->OptionalHeader.ImageBase) + 
                     ((PIMAGE_DATA_DIRECTORY)dwValueB)->VirtualAddress;
LPSTR libname[128];
int i =0;
while(((PIMAGE_IMPORT_DESCRIPTOR)dwValueC)->Name)
{
       // get DLL name
       libname[i] = (LPSTR)(nt->OptionalHeader.ImageBase + 
                         ((PIMAGE_IMPORT_DESCRIPTOR)dwValueC)->Name);
       i++;
}

Answer 1

要读取导入目录表中的库名称，您可以执行以下操作：

1. 获取文件的内存映射基地址。
2. 获取指向IMAGE_NT_HEADERS 结构的指针。

3. 获取指向IMAGE_SECTION_HEADER 结构的指针。

4. DataDirectory 是 OptionalHeader 的最后 128 个字节，而后者又是 PE 头 IMAGE_NT_HEADERS 的最后一个成员。 该结构有 2 个成员，其中包含数据结构的位置和大小。
   如果要查找有关 dll 名称的信息，首先从 Data Directory 中找到 Import Directory 的 RVA（相对虚拟地址），在原始节数据中找到该地址，现在您有一个 @987654331 数组@。通过检查 Name 字段指向的字符串，获取与映射图像相关的数组成员。

我不会描述便携式可执行文件格式的结构，但是您可以查看以下链接：
Peering Inside the PE
Microsoft Systems Journal

您的代码中的某些变量未声明，这很令人困惑，但我坚持使用您编写的框架代码，以便满足您的问题。

DWORD Rva2Offset(DWORD rva,PIMAGE_SECTION_HEADER psh,PIMAGE_NT_HEADERS pnt);
int _tmain(int argc, _TCHAR* argv[])
{
LPCWSTR fNmae=L"C:\\Windows\\system32\\notepad.exe";
HANDLE handle=CreateFile(fNmae/*"messagebox.exe"*/, GENERIC_READ, 0, 0, OPEN_EXISTING,  FILE_ATTRIBUTE_NORMAL, 0);
DWORD byteread,size=GetFileSize(handle, NULL);
PVOID virtualpointer=VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
ReadFile(handle, virtualpointer, size, &byteread, NULL);
CloseHandle(handle);
// Get pointer to NT header
PIMAGE_NT_HEADERS           ntheaders=(PIMAGE_NT_HEADERS)(PCHAR(virtualpointer) + PIMAGE_DOS_HEADER(virtualpointer)-> e_lfanew);   
PIMAGE_SECTION_HEADER       pSech=IMAGE_FIRST_SECTION(ntheaders);//Pointer to first section header
PIMAGE_IMPORT_DESCRIPTOR    pImportDescriptor; //Pointer to import descriptor 
__try
{
    if(ntheaders->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].Size != 0)/*if size of the table is 0 - Import Table does not exist */
    {
        pImportDescriptor = (PIMAGE_IMPORT_DESCRIPTOR)((DWORD_PTR)virtualpointer +\
                            Rva2Offset(ntheaders->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress,pSech,ntheaders));
        LPSTR libname[256];
        size_t i=0;
        // Walk until you reached an empty IMAGE_IMPORT_DESCRIPTOR
        while(pImportDescriptor->Name != NULL)
        {
            printf("Library Name   :");
            //Get the name of each DLL
            libname[i]=(PCHAR)((DWORD_PTR)virtualpointer + Rva2Offset(pImportDescriptor->Name,pSech,ntheaders));
            printf("%s\n", libname[i]);
            pImportDescriptor++; //advance to next IMAGE_IMPORT_DESCRIPTOR
            i++;

        }

    }
    else
    {
        printf("No Import Table!\n");
        return 1;
    }
}
__except(EXCEPTION_EXECUTE_HANDLER)
{
    if(EXCEPTION_ACCESS_VIOLATION == GetExceptionCode())
    {
        printf("Exception: EXCEPTION_ACCESS_VIOLATION\n");
        return 1;
    }

}
if(virtualpointer)
    VirtualFree(virtualpointer, size, MEM_DECOMMIT);

return 0;
}
 /*Convert Virtual Address to File Offset */
DWORD Rva2Offset(DWORD rva,PIMAGE_SECTION_HEADER psh,PIMAGE_NT_HEADERS pnt)
{
    size_t i = 0;
    PIMAGE_SECTION_HEADER pSeh;
    if(rva == 0)
    {
            return (rva);
    }
    pSeh = psh;
    for(i = 0; i < pnt->FileHeader.NumberOfSections; i++)
    {
            if(rva >= pSeh->VirtualAddress && rva < pSeh->VirtualAddress +
               pSeh->Misc.VirtualSize)
            {
                    break;
            }
            pSeh++;
    }
    return (rva - pSeh->VirtualAddress + pSeh->PointerToRawData);
}