/*++

 Copyright (c) 2000 Microsoft Corporation

 Module Name:

   DelayWin95VersionLie.cpp

 Abstract:

   This DLL hooks GetVersion and GetVersionEx so that they return Windows 95
   version credentials. Applications often check to ensure that they are 
   running on a Win9x system, even though they will run OK on an NT based 
   system.

 Notes:

   This is a general purpose shim.

 History:

   11/10/1999   v-johnwh    Created
   02/13/2002   astritz     Security Review

--*/

#include "precomp.h"

IMPLEMENT_SHIM_BEGIN(DelayWin95VersionLie)
#include "ShimHookMacro.h"

APIHOOK_ENUM_BEGIN
    APIHOOK_ENUM_ENTRY(GetVersion)
    APIHOOK_ENUM_ENTRY(GetVersionExA)
    APIHOOK_ENUM_ENTRY(GetVersionExW)
APIHOOK_ENUM_END

//
// Used to delay version lying
//
long g_Count = 0;
DWORD g_dwDelay = 0;

/*++

 This stub function fixes up the OSVERSIONINFO structure that is
 returned to the caller with Windows 95 credentials.

--*/

BOOL
APIHOOK(GetVersionExA)(
    OUT LPOSVERSIONINFOA lpVersionInformation
    )
{
    DWORD dwCount = InterlockedIncrement(&g_Count);
    if (dwCount < g_dwDelay) {
        return ORIGINAL_API(GetVersionExA)(lpVersionInformation);
    } else {
        BOOL bReturn = FALSE;

        if (ORIGINAL_API(GetVersionExA)(lpVersionInformation)) {
            
            LOGN(eDbgLevelInfo, "[GetVersionExA] Return Win95");
            
            //
            // Fixup the structure with the Win95 data.
            //
            lpVersionInformation->dwMajorVersion = 4;
            lpVersionInformation->dwMinorVersion = 0;
            lpVersionInformation->dwBuildNumber = 950;
            lpVersionInformation->dwPlatformId = 1;
            *lpVersionInformation->szCSDVersion = '\0';

            if( lpVersionInformation->dwOSVersionInfoSize == sizeof(OSVERSIONINFOEXA) ) 
            {
                // We are here as we are passed a OSVERSIONINFOEX structure.
                // Set the major and minor service pack numbers.
                ((LPOSVERSIONINFOEXA)lpVersionInformation)->wServicePackMajor = 0;
                ((LPOSVERSIONINFOEXA)lpVersionInformation)->wServicePackMinor = 0;
            }

            bReturn = TRUE;
        }
        
        return bReturn;
    }
}

/*++

 This stub function fixes up the OSVERSIONINFO structure that is
 returned to the caller with Windows 95 credentials.

--*/

BOOL
APIHOOK(GetVersionExW)(
    OUT LPOSVERSIONINFOW lpVersionInformation
    )
{
    DWORD dwCount = InterlockedIncrement(&g_Count);
    if (dwCount < g_dwDelay) {
        return ORIGINAL_API(GetVersionExW)(lpVersionInformation);
    } else {
        BOOL bReturn = FALSE;

        if (ORIGINAL_API(GetVersionExW)(lpVersionInformation)) {
            
            LOGN(eDbgLevelInfo, "[GetVersionExW] Return Win95");
            
            //
            // Fixup the structure with the Win95 data.
            //
            lpVersionInformation->dwMajorVersion = 4;
            lpVersionInformation->dwMinorVersion = 0;
            lpVersionInformation->dwBuildNumber = 950;
            lpVersionInformation->dwPlatformId = 1;
            *lpVersionInformation->szCSDVersion = L'\0';

            if( lpVersionInformation->dwOSVersionInfoSize == sizeof(OSVERSIONINFOEXW) ) 
            {
                // We are here as we are passed a OSVERSIONINFOEX structure.
                // Set the major and minor service pack numbers.
                ((LPOSVERSIONINFOEXW)lpVersionInformation)->wServicePackMajor = 0;
                ((LPOSVERSIONINFOEXW)lpVersionInformation)->wServicePackMinor = 0;
            }

            bReturn = TRUE;
        }
        
        return bReturn;
    }
}

/*++

 This stub function returns Windows 95 credentials.

--*/

DWORD
APIHOOK(GetVersion)()
{
    DWORD dwCount = InterlockedIncrement(&g_Count);
    if (dwCount < g_dwDelay) {
        return ORIGINAL_API(GetVersion)();
    } else {
        LOGN(eDbgLevelInfo, "[GetVersion] Return Win95");
        return (DWORD)0xC3B60004;
    }
}

/*++

 Register hooked functions

--*/

BOOL
NOTIFY_FUNCTION(
    DWORD fdwReason
    )
{
    if (fdwReason == DLL_PROCESS_ATTACH)
    {
        CSTRING_TRY
        {
            CString csCl(COMMAND_LINE);
        
            if (!csCl.IsEmpty())
            {
                WCHAR * unused;
                g_dwDelay = wcstol(csCl, &unused, 10);
            }

            DPFN(eDbgLevelInfo, "Delaying version lie by %d", g_dwDelay);
        }
        CSTRING_CATCH
        {
            return FALSE;
        }
    }
    
    return TRUE;
}

HOOK_BEGIN

    CALL_NOTIFY_FUNCTION

    APIHOOK_ENTRY(KERNEL32.DLL, GetVersion)
    APIHOOK_ENTRY(KERNEL32.DLL, GetVersionExA)
    APIHOOK_ENTRY(KERNEL32.DLL, GetVersionExW)

HOOK_END


IMPLEMENT_SHIM_END