VB与VC通信，实现判断是否允许Hook进程创建，请教！

近日在努力学习消化一段源码，可苦于严重才疏学浅，折腾了多日，虽然看了个“略懂略懂”，可核心功能总是无法实现，拜托哪位大侠能忙里偷闲，帮小菜找找原因所在，并注释解释一番，将不胜感激，定当感激涕零……

代码的主要目的是通过VC编写的DLL来实现全局Hook，当Hook到有进程创建企图时，便向VB编写的主程序发出一个Sendmessage消息，主程序收到该消息后询问用户是否允许该进程创建，通过用户的选择决定Sendmessage的返回值，然后DLL通过返回值决定是否让该进程创建。

现在的问题是：当开启Hook后，VB主程序不会询问用户，而所有新进程直接都无法创建。不知道问题到底出在哪里？

苦思多日而不得其解，身边又无人请教，只好到这里求教，恳请热心大侠多多指教……，完整代码可从这里下载
代码如下：
VC DLL代码：

#include "stdafx.h" 

#include <windows.h> 

#include "stdio.h" 

#include "stdlib.h" 



HANDLE hProcess=0; 

UCHAR OldCode[5]={0}, NewCode[5]={0}; 

ULONG FunAddr=0; 

HWND hExe=0; 

HINSTANCE hMod=0; 

HHOOK hHook=0; 



// Status: FALSE 关闭HOOK，写入原函数地址，也就是CreateProcessW

// Status：TRUE 打开HOOK，写入自己HOOK函数地址，也就是 CreateProcessWCallBack

BOOL HookStatus(BOOL Status)

{ 

BOOL ret=FALSE; 

if (Status) { 

ret = WriteProcessMemory(hProcess, (void *)FunAddr, NewCode, 5, 0); 

if (ret) return TRUE;} 

else { 

ret = WriteProcessMemory(hProcess, (void *)FunAddr, OldCode, 5, 0); 

if (ret) return TRUE;} 

return FALSE; 

} 



// CreateProcessW的HOOK函数原型，在调用真实的CreateProcessW之前先做自己的事

BOOL WINAPI CreateProcessWCallBack(LPCWSTR lpApplicationName, 

  LPWSTR lpCommandLine, 

  LPSECURITY_ATTRIBUTES lpProcessAttributes, 

  LPSECURITY_ATTRIBUTES lpThreadAttributes, 

  BOOL bInheritHandles, 

  DWORD dwCreationFlags, 

  LPVOID lpEnvironment, 

  LPCWSTR lpCurrentDirectory, 

  LPSTARTUPINFOW lpStartupInfo, 

  LPPROCESS_INFORMATION lpProcessInformation){ 

ULONG ret=0; 

BOOL b=FALSE; 

COPYDATASTRUCT cds={0}; 



cds.lpData = (void *)lpApplicationName; 

cds.cbData = 255; 



// 把lpApplicationName（创建新进程的文件路径）的信息用WM_COPY消息发到自己的窗口

ret = SendMessage(hExe, WM_COPYDATA, GetCurrentProcessId(), (LPARAM)&cds);



// 根据你自己处理WM_COPYDATA消息的结果决定是否创建这个进程，返回1234则创建，否则不创建 

if (ret==1234) { 

HookStatus(FALSE); 

b = CreateProcessW(lpApplicationName, 

lpCommandLine, 

lpProcessAttributes, 

lpThreadAttributes, 

bInheritHandles, 

dwCreationFlags, 

lpEnvironment, 

lpCurrentDirectory, 

lpStartupInfo, 

lpProcessInformation); 

HookStatus(TRUE); 

return b; 

} else return FALSE; 

return FALSE; 

} 



// HOOK CreateProcessW函数

BOOL HookCreateProcess(){ 

ULONG JmpAddr=0; 

char msg[255]={0}; 



FunAddr = (ULONG)GetProcAddress(LoadLibrary("Kernel32.dll"), "CreateProcessW"); 

memcpy(OldCode, (void *)FunAddr, 5); 

NewCode[0] = 0xe9;  // jmp 的机器码



// 计算你自定义CreateProcessW的函数原型相对于CreateProcessW函数地址的偏移，5是jmp XXXX指令的长度

JmpAddr = (ULONG)CreateProcessWCallBack - FunAddr - 5; 

memcpy(&NewCode[1], &JmpAddr, 4); 

//sprintf(msg, "NewCode: %x %x %x %x %x\nFunAddr: %x\nJmpAddr: %x\nMyFun: %x", NewCode[0], NewCode[1], NewCode[2], NewCode[3], NewCode[4], FunAddr, JmpAddr, (ULONG)CreateProcessWCallBack); 

//MessageBox(0, msg, "", MB_OK); 



// 打开HOOK

HookStatus(TRUE); 

return TRUE; 

} 



// DLL入口函数

BOOL APIENTRY DllMain( HANDLE hModule, 

                      DWORD  ul_reason_for_call, 

                      LPVOID lpReserved) 

{ 

hMod = (HINSTANCE)hModule; 

if (ul_reason_for_call==DLL_PROCESS_ATTACH){ 



// 打开进程，得到进程HANDLE，用于WriteMemory

hProcess = OpenProcess(PROCESS_ALL_ACCESS, 0, GetCurrentProcessId()); 

// 查找自己程序的主窗体，用于发送WM_COPYDATA消息

hExe = FindWindow(NULL, "Hook CreateProcessW"); 

// Hook CreateProcessW函数

HookCreateProcess();} 

// DLL从进程中卸载，关闭HOOK

if (ul_reason_for_call==DLL_PROCESS_DETACH) HookStatus(FALSE); 

    return TRUE; 

} 



// 卸载windows HOOK

extern "C" __declspec(dllexport) BOOL UnLoadHook(){ 

return(UnhookWindowsHookEx(hHook)); 

} 



// Windows HOOK 函数

LRESULT CALLBACK HookProc(int nCode,WPARAM wParam,LPARAM lParam){ 

return(CallNextHookEx(hHook,nCode,wParam,lParam)); 

} 



// 安装钩子

extern "C" __declspec(dllexport) BOOL StartHook(){ 

hHook = SetWindowsHookEx(WH_GETMESSAGE,(HOOKPROC)HookProc, hMod, 0); 

if (hHook) return TRUE; 

return FALSE; 

} 

================================================================================
VB Frmmain 代码：

Private Declare Function StartHook Lib "Hook.dll" () As Boolean

Private Declare Function UnLoadHook Lib "Hook.dll" () As Boolean

'download by http://www.codefans.net

Private Sub cmdHook_Click()

    If StartHook Then cmdHook.Enabled = False

End Sub



Private Sub cmdUnHook_Click()

    If UnLoadHook Then cmdUnHook.Enabled = False: MsgBox "已经解除！": Unload Me

End Sub



Private Sub Form_Initialize()

    SetButtonFlat cmdHook.hwnd

    SetButtonFlat cmdUnHook.hwnd

End Sub



Private Sub Form_Load()

    c = GetWindowLong(hwnd, -4)

    SetWindowLong hwnd, -4, AddressOf Wndproc

End Sub



Private Sub Form_Unload(Cancel As Integer)

    If cmdUnHook.Enabled Then UnLoadHook: Unload Me

End Sub



Private Function SetButtonFlat(ByVal hwnd As Long) As Boolean

Dim style As Long

    style = GetWindowLong(hwnd, (-16))

    style = style Or &H8000&

    SetButtonFlat = SetWindowLong(hwnd, (-16), style)

End Function

mod_Msg.bas模块代码：

Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Public Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Private Declare Function MessageBoxA Lib "user32" (ByVal hwnd As Long, ByVal lpText As String, ByVal lpCaption As String, ByVal wType As Long) As Long

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)

Private Type COPYDATASTRUCT

    dwData As Long

    cbData As Long

    lpData As Long

End Type

Public c As Long



'download by http://www.codefans.net

Public Function Wndproc(ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Dim s As String

Dim cds As COPYDATASTRUCT

    'FrmMain.Text1.Text = Msg

    FrmMain.Print Msg

    If Msg = &H4A Then

    CopyMemory cds, ByVal lParam, Len(cds)

    s = Space(cds.cbData)

    CopyMemory ByVal s, ByVal cds.lpData, cds.cbData

    s = StrConv(s, vbFromUnicode)

    s = Left(s, InStr(1, s, Chr(0)) - 1)

    s = "进程(Pid:" & wParam & ")要创建新进程: " & s & ",是否允许?"

        If MessageBoxA(0, s, "", 4) = 6 Then

            Wndproc = 1234

        Else

            Wndproc = 0

        End If

        Exit Function

    End If

    Wndproc = CallWindowProc(c, hwnd, Msg, wParam, lParam)

End Function