C++实现修改函数代码HOOK的封装方法

一、对外的接口如下：

1. 类初始化时对函数HOOK

2. 取消挂钩：

void UnHook();

3. 重新挂钩：

void ReHook();

在初始化时HOOK的代码：

复制代码 代码如下:
*(DWORD*)(m_btNewBytes+1) = (DWORD)pfnHook;

8个字节的代码地址 0xB8, 0x00, 0x00,0x40,0x00,0xFF,0xE0,0x00  只要把第二位和第三位的数据改成函数的地址，调用原先的函数时就会调到自定义的函数执行.

二、实现方法：

.h头文件如下：

复制代码 代码如下:
#ifndef  _ULHOOK_H__ 

#define _ULHOOK_H__ 

 

#include <Windows.h> 

#pragma once 

class CULHook 

{ 

public: 

    CULHook(LPSTR lpszModName, LPSTR lpszFuncNme, PROC pfnHook); 

    ~CULHook(void); 

 

    //取消挂钩 

    void UnHook(); 

    //重新挂钩 

    void ReHook(); 

protected: 

    PROC m_pfnOrig; 

    BYTE m_btNewBytes[8]; 

    BYTE m_btOldBytes[8]; 

    HMODULE m_hModule; 

}; 

 

#endif

.cpp源文件如下：

复制代码 代码如下:
#include "ULHook.h" 

 

CULHook::CULHook(LPSTR lpszModName, LPSTR lpszFuncNme, PROC pfnHook) 

{ 

    BYTE btNewBytes[] = {0xB8, 0x00, 0x00,0x40,0x00,0xFF,0xE0,0x00}; 

    memcpy(m_btNewBytes, btNewBytes, 8); 

    *(DWORD*)(m_btNewBytes+1) = (DWORD)pfnHook; 

 

    m_hModule = ::LoadLibraryA(lpszModName); 

    if (NULL == m_hModule) 

    { 

        m_pfnOrig = NULL; 

        return; 

    } 

    m_pfnOrig = (PROC)::GetProcAddress(m_hModule, lpszFuncNme); 

    if (NULL != m_pfnOrig) 

    { 

        MEMORY_BASIC_INFORMATION mbi = {0}; 

        DWORD dwOldProtect; 

        ::VirtualQuery(m_pfnOrig, &mbi, sizeof(mbi)); 

        ::VirtualProtect(m_pfnOrig, 8, PAGE_READWRITE, &dwOldProtect); 

        memcpy(m_btOldBytes, m_pfnOrig, 8); 

        ::WriteProcessMemory(GetCurrentProcess(), (VOID*)m_pfnOrig, m_btNewBytes, 8, NULL); 

        ::VirtualProtect(m_pfnOrig, 8, dwOldProtect, NULL); 

    } 

} 

 

CULHook::~CULHook(void) 

{ 

    UnHook(); 

    if (m_hModule!=NULL) 

    { 

        ::FreeLibrary(m_hModule); 

    } 

} 

void CULHook::UnHook() 

{ 

    if (m_pfnOrig != NULL) 

    { 

        MEMORY_BASIC_INFORMATION mbi = {0}; 

        DWORD dwOldProtect; 

        ::VirtualQuery(m_pfnOrig, &mbi, sizeof(mbi)); 

        ::VirtualProtect(m_pfnOrig, 8, PAGE_READWRITE, &dwOldProtect); 

        ::WriteProcessMemory(GetCurrentProcess(), (VOID*)m_pfnOrig, m_btOldBytes, 8, NULL); 

        ::VirtualProtect(m_pfnOrig, 8, dwOldProtect, NULL); 

    } 

} 

 

void CULHook::ReHook() 

{ 

    if (m_pfnOrig != NULL) 

    { 

        MEMORY_BASIC_INFORMATION mbi = {0}; 

        DWORD dwOldProtect; 

        ::VirtualQuery(m_pfnOrig, &mbi, sizeof(mbi)); 

        ::VirtualProtect(m_pfnOrig, 8, PAGE_READWRITE, &dwOldProtect); 

        ::WriteProcessMemory(GetCurrentProcess(), (VOID*)m_pfnOrig, m_btNewBytes, 8, NULL); 

        ::VirtualProtect(m_pfnOrig, 8, dwOldProtect, NULL); 

    } 

}