Leaked source code of windows server 2003
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/*++
Copyright (c) 2000-2001 Microsoft Corporation
Module Name:
SampleShim.cpp
Abstract:
This DLL serves as a template for the creation of shim DLLs. Follow
the commenting/coding style of this source file wherever possible.
Never use tabs, configure your editor to insert spaces instead of
tab characters.
Notes:
Hooking COM functions is also possible but is not covered in this
sample for simplicity sake. Contact markder or linstev for more
information on COM hooking.
History:
02/02/2000 markder Created
11/14/2000 markder Converted to framework version 2
02/13/2001 mnikkel Changed notify to handle new DLL_PROCESS
capabilities
03/31/2001 robkenny Changed to use CString
04/10/2002 robkenny Updated to compile.
--*/
#include "ShimHook.h"
#include "StrSafe.h"
using namespace ShimLib;
//
// You must declare the type of shim this is at the top. If your shim
// coexists with other shims in the same DLL,
// use IMPLEMENT_SHIM_BEGIN(SampleShim)
// otherwise use IMPLEMENT_SHIM_STANDALONE(SampleShim)
//
IMPLEMENT_SHIM_STANDALONE(SampleShim)
#include "ShimHookMacro.h"
//
// Add APIs that you wish to hook to this macro construction.
//
APIHOOK_ENUM_BEGIN
APIHOOK_ENUM_ENTRY(MessageBoxA)
APIHOOK_ENUM_ENTRY(MessageBoxW)
APIHOOK_ENUM_END
/*++
This stub function intercepts all calls to MessageBoxA
and prefixes the output string with "SampleShim says:".
--*/
int
APIHOOK(MessageBoxA)(
HWND hWnd, // handle to owner window
LPCSTR lpText, // text in message box
LPCSTR lpCaption, // message box title
UINT uType // message box style
)
{
//
// Use Hungarian notation for local variables:
//
// Type Scope
// ----------------------- ------------------
// Pointers p Global g_
// DWORD dw Class member m_
// LONG l Static s_
// ANSI strings sz
// Wide-char strings wsz
// Arrays rg
// CString cs
//
int iReturnValue;
//
// We use the CString class to perform all string operations in UNICODE
// to prevent any problems with DBCS characters.
//
// Place all CString operations inside a CSTRING_TRY/CSTRING_CATCH
// exception handler. CString will throw an exception if it encounters
// any memory allocation failures.
//
// Performing all string operations by using the CString class also prevents
// us from accidentally modifying the original string.
//
CSTRING_TRY
{
CString csNewOutputString(lpText);
csNewOutputString.Insert(0, L"SampleShim says: ");
//
// Use the DPF macro to print debug strings. See Hooks\inc\ShimDebug.h
// for debug level values. Use eDbgLevelError if an unexpected error
// occurs in your shim code. For informational output, use eDbgLevelInfo.
//
// Make sure you don't end the message with '\n' in this case because
// the macro will do it by default.
//
// Note that when printing CString, use %S and you must call the Get() method,
// to explicitly return a WCHAR *.
//
DPFN( eDbgLevelInfo,
"MessageBoxA called with lpText = \"%s\".", lpText);
//
// Use the ORIGINAL_API macro to call the original API. You must use
// this so that API chaining and inclusion/exclusion information is
// preserved.
//
// CString will perform automatic type conversion to const WCHAR * (LPCWSTR)
// It will not, however, automatically convert to char *, you must call GetAnsi()
// (or GetAnsiNIE() if you wish a NULL pointer be returned when the string is empty)
//
iReturnValue = ORIGINAL_API(MessageBoxA)(hWnd, csNewOutputString.GetAnsi(), lpCaption, uType);
//
// Use the LOG macro to print messages to the log file. This macro should
// be used to indicate that the shim had affected execution of the program
// in some way. Use eDbgLevelError to indicate that the shim has
// consciously fixed something that would have caused problems. Use
// eDbgLevelWarning if the shim has affected execution, but it is unclear
// whether it actually helped the program.
//
LOGN( eDbgLevelWarning,
"MessageBoxA converted lpText from \"%s\" to \"%S\".", lpText, csNewOutputString.Get());
}
CSTRING_CATCH
{
//
// We had a CString failure, call the original API with the original args
//
iReturnValue = ORIGINAL_API(MessageBoxA)(hWnd, lpText, lpCaption, uType);
}
return iReturnValue;
}
/*++
This stub function intercepts all calls to MessageBoxW and prefixes the
output string with "SampleShim says:".
Note that to make your shim generally applicable in an NT environment,
you should include both ANSI and wide-character versions of your stub
function. However, if your shim emulates Win9x behaviour, it is
redundant to include wide-character versions because Win9x did not
support them.
--*/
int
APIHOOK(MessageBoxW)(
HWND hWnd, // handle to owner window
LPCWSTR lpText, // text in message box
LPCWSTR lpCaption, // message box title
UINT uType // message box style
)
{
int iReturnValue;
CSTRING_TRY
{
CString csNewOutputString(lpText);
csNewOutputString.Insert(0, L"SampleShim says: ");
DPFN( eDbgLevelInfo,
"MessageBoxW called with lpText = \"%S\".", lpText);
iReturnValue = ORIGINAL_API(MessageBoxW)(
hWnd,
csNewOutputString,
lpCaption,
uType);
LOGN( eDbgLevelWarning,
"MessageBoxW converted lpText from \"%S\" to \"%S\".",
lpText, csNewOutputString.Get());
}
CSTRING_CATCH
{
iReturnValue = ORIGINAL_API(MessageBoxW)(
hWnd,
lpText,
lpCaption,
uType);
}
return iReturnValue;
}
/*++
Handle DLL_PROCESS_ATTACH, SHIM_STATIC_DLLS_INITIALIZED
and DLL_PROCESS_DETACH in your notify function
to do initialization and uninitialization.
IMPORTANT: Make sure you ONLY call NTDLL and KERNEL32 APIs during
DLL_PROCESS_ATTACH notification. No other DLLs are initialized at that
point.
SHIM_STATIC_DLLS_INITIALIZED is called after all of the application's
DLLs have been initialized.
If your shim cannot initialize properly (during DLL_PROCESS_ATTACH),
return FALSE and none of the APIs specified will be hooked.
--*/
BOOL
NOTIFY_FUNCTION(
DWORD fdwReason)
{
//
// Note that there are further cases besides attach and detach.
//
switch (fdwReason)
{
case DLL_PROCESS_ATTACH:
DPFN( eDbgLevelSpew, "Sample Shim initialized.");
break;
case SHIM_STATIC_DLLS_INITIALIZED:
DPFN( eDbgLevelSpew,
"Sample Shim notification: All DLLs have been loaded.");
break;
case DLL_PROCESS_DETACH:
DPFN( eDbgLevelSpew, "Sample Shim uninitialized.");
break;
default:
break;
}
return TRUE;
}
/*++
Register hooked functions
--*/
HOOK_BEGIN
//
// If you have any initialization to do, you must include this line.
// Then you must implement the NOTIFY_FUNCTION as above.
//
CALL_NOTIFY_FUNCTION
//
// Add APIs that you wish to hook here. All API prototypes
// must be declared in Hooks\inc\ShimProto.h. Compiler errors
// will result if you forget to add them.
//
APIHOOK_ENTRY(USER32.DLL, MessageBoxA)
APIHOOK_ENTRY(USER32.DLL, MessageBoxW)
HOOK_END
IMPLEMENT_SHIM_END