DLL加载问题

今天打算研究下白利用的时候出各种问题，复习下dll加载。

1.普通dll文件

int add(int a,int b)
{
return a+b;
}

查看输出表为空

2._declspec申明

_declspec(dllexport) int add(int a,int b)
{
    return a+b;
}

导出函数名为?add@@YAHHH@Z，产生一个lib文件，需要在link下添加此lib才能extern到函数，或者在调用程序中申明 _declspec(dllimport) int add(int a,int b)

3.添加DEF文件

LIBRARY 3

EXPORTS
add

没发生名字改编

4.loader

#include "windows.h"
#include "iostream.h"


void main()
{
    HINSTANCE h;
    h=LoadLibrary("3.dll");
    typedef int (*func_add)(int a,int b);
    func_add add=(func_add)GetProcAddress(h,"add");
    cout<3,5)<

成功加载

5.动态加载message
loader

#include "windows.h"
#include "iostream.h"


void main()
{
    HINSTANCE h;
    h=LoadLibrary("3.dll");
    typedef void (*func_sw)(HWND);
    func_sw sw=(func_sw)GetProcAddress(h,"ShowMessage");
    sw(FindWindow(NULL,"loader"));
}

dll

#include "windows.h"

int add(int a,int b)
{
    return a+b;
}

void ShowMessage(HWND h1)
{
    MessageBox(h1,"1","1",NULL);
}

4.dllmain中直接调用MessageBox
dll

#include "windows.h"
#include "stdio.h"

void ShowMessage();

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
    switch (fdwReason)
    {
    case DLL_PROCESS_ATTACH:
        MessageBox(NULL,"1","1",MB_OK);
        break;

    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

void ShowMessage()
{
    MessageBox(NULL,"1","1",MB_OK);
}

成功。。。。。

5.dll中定义函数内部调用MessageBox，dllmain中调用该定义函数
dll

#include "windows.h"
#include "stdio.h"

void ShowMessage();

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
    switch (fdwReason)
    {
    case DLL_PROCESS_ATTACH:
        ShowMessage();
        break;

    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

void ShowMessage()
{
    MessageBox(NULL,"1","1",MB_OK);
}

loader

#include "windows.h"
#include "iostream.h"


void main()
{
    HINSTANCE h;
    //LoadLibrary("USER32.dll");
    h=LoadLibrary("3.dll");
    system("sleep");
}

成功显示