调用GetProcAddress时出现错误127

Question

我正在为WH_GETMESSAGE写入全局钩子。但是，当从dll调用GetProcAddress函数时，我得到错误代码127，即ERROR_PROC_NOT_FOUND。它无法找到GetMsgProc。任何想法为什么？

此外，我是这种编程的新手，所以对任何错误都不抱歉。

DLL文件：

#include "windows.h" 
#include <stdio.h> 

BOOL APIENTRY DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) 
{ 
    return TRUE; 
} 

__declspec(dllexport) LRESULT CALLBACK GetMsgProc(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
    MessageBox(NULL, TEXT("I am in"),TEXT("In a DLL"), MB_OK); 

    return CallNextHookEx(NULL, nCode, wParam, lParam); 
} 

程序加载的DLL文件：

#include <windows.h> 
#include <tchar.h> 
#include <stdio.h> 

typedef LRESULT(CALLBACK *LPGetMsgProc)(int nCode, WPARAM wParam, LPARAM lParam); 

int main() 
{ 
    HMODULE hDll = LoadLibrary(_T("../../dllTouchInputHook/x64/Debug/dllTouchInputHook.dll")); 
    LPGetMsgProc proc = (LPGetMsgProc)GetProcAddress(hDll, "GetMsgProc"); 
    if (proc == NULL) { 
     printf("The error code is %d", GetLastError()); 
    } 

    HHOOK hMsgHook = SetWindowsHookEx(WH_GETMESSAGE, proc, hDll, 0); 

    MSG msg; 
    while (GetMessage(&msg, NULL, 0, 0) > 0) { 

     TranslateMessage(&msg); 
     DispatchMessage(&msg); 
    } 

    UnhookWindowsHookEx(hMsgHook); 

    return 0; 
} 

Answer 1

的功能没有被发现，因为像你期望它不被导出为"GetMsgProc"。它实际上更像"_GetMsgProc@12"（32位）或"_GetMsgProc@20"（64位）。如果您希望导出为"GetMsgProc"，那么在编译DLL时需要使用.DEF文件。

你不应该以这种方式实施钩子开始。你应该将呼叫转移到SetWindowsHookEx() DLL本身里面，然后导出函数来调用它，例如：

#include "windows.h" 
#include <stdio.h> 

HINSTANCE hThisDLL; 
HHOOK hMsgHook; 

BOOL APIENTRY DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) 
{ 
    hThisDLL = hinstDLL; 
    return TRUE; 
} 

LRESULT CALLBACK GetMsgProc(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
    MessageBox(NULL, TEXT("I am in"), TEXT("In a DLL"), MB_OK); 
    return CallNextHookEx(NULL, nCode, wParam, lParam); 
} 

__declspec(dllexport) BOOL WINAPI InstallHook() 
{ 
    if (!hMsgHook) 
     hMsgHook = SetWindowsHookEx(WH_GETMESSAGE, &GetMsgProc, hThisDll, 0); 
    return (hMsgHook != NULL); 
} 

__declspec(dllexport) VOID WINAPI UninstallHook() 
{ 
    if (hMsgHook) 
    { 
     UnhookWindowsHookEx(hMsgHook); 
     hMsgHook = NULL; 
    } 
} 

#include <windows.h> 
#include <tchar.h> 
#include <stdio.h> 

typedef BOOL (WINAPI *LPInstallHook)(); 
typedef VOID (WINAPI *LPUninstallHook)(); 

int main() 
{ 
    HMODULE hDll = LoadLibrary(_T("../../dllTouchInputHook/x64/Debug/dllTouchInputHook.dll")); 
    if (!hDll) 
    { 
     printf("The error code is %d", GetLastError()); 
     return -1; 
    } 

    LPInstallHook installProc = (LPInstallHook) GetProcAddress(hDll, "InstallHook"); // or "_InstallHook" 
    LPUninstallHook uninstallProc = (installProc) ? (LPUninstallHook) GetProcAddress(hDll, "UninstallHook") : NULL; // or "_UninstallHook" 

    if (!(installProc && uninstallProc)) 
    { 
     printf("The error code is %d", GetLastError()); 
     FreeLibrary(hDll); 
     return -1; 
    } 

    if (!installProc()) 
    { 
     printf("The error code is %d", GetLastError()); 
     FreeLibrary(hDll); 
     return -1; 
    } 

    MSG msg; 
    while (GetMessage(&msg, NULL, 0, 0) > 0) { 
     TranslateMessage(&msg); 
     DispatchMessage(&msg); 
    } 

    uninstallProc(); 

    FreeLibrary(hDll); 

    return 0; 
}