HOWTO: Mark MFC Controls Safe for Scripting/Initialization
ID: Q161873
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The information in this article applies to:
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Microsoft Visual C++, 32-bit Editions, versions 4.2, 5.0, 6.0
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Microsoft Internet Client Software Development Kit (SDK) version 4.0, 4.01
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Microsoft Internet Explorer (Programming) versions 4.0, 4.01
SUMMARY
By default, MFC ActiveX controls are not marked as Safe for Scripting
and/or Safe for Initialization. This becomes apparent when the control is
run in the Internet Explorer with the security level set to medium or high.
In either of these modes, warnings may be displayed that the control's data
is not safe or that the control may not be safe for scripts to use.
There are two methods that a control can use to eliminate these errors. The
first involves the control implementing the IObjectSafety interface and is
useful for controls that would like to change their behavior and become
"safe" if run in the context of an Internet Browser. The second involves
modifying the control's DllRegisterServer function to mark the control
"safe" in the registry. This article covers the second of these methods.
The first method, implementing the IObjectSafety interface, is covered in
the Internet Client SDK.
Please keep in mind that a control should only be marked as safe if it is,
in fact, safe. Please refer to the Internet Client SDK documentation for a
description of this. See "Safe Initialization and Scripting for ActiveX
Controls" under the Component Development Section.
NOTE: This article does not cover how to mark a control safe for
downloading. For more information on code download and code signing, please
refer to the Internet Client SDK.
MORE INFORMATION
Follow these steps to mark your MFC ActiveX Control as Safe for Scripting
and Safe for Initializing:
- Implement the CreateComponentCategory and RegisterCLSIDInCategory helper
functions by adding the following cathelp.h and cathelp.cpp files to
your project.
CATHELP.H
#include "comcat.h"
// Helper function to create a component category and associated
// description
HRESULT CreateComponentCategory(CATID catid, WCHAR* catDescription);
// Helper function to register a CLSID as belonging to a component
// category
HRESULT RegisterCLSIDInCategory(REFCLSID clsid, CATID catid);
CATHELP.CPP
#include "comcat.h"
// Helper function to create a component category and associated
// description
HRESULT CreateComponentCategory(CATID catid, WCHAR* catDescription)
{
ICatRegister* pcr = NULL ;
HRESULT hr = S_OK ;
hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr,
NULL,
CLSCTX_INPROC_SERVER,
IID_ICatRegister,
(void**)&pcr);
if (FAILED(hr))
return hr;
// Make sure the HKCR\Component Categories\{..catid...}
// key is registered
CATEGORYINFO catinfo;
catinfo.catid = catid;
catinfo.lcid = 0x0409 ; // english
// Make sure the provided description is not too long.
// Only copy the first 127 characters if it is
int len = wcslen(catDescription);
if (len>127)
len = 127;
wcsncpy(catinfo.szDescription, catDescription, len);
// Make sure the description is null terminated
catinfo.szDescription[len] = '\0';
hr = pcr->RegisterCategories(1, &catinfo);
pcr->Release();
return hr;
}
// Helper function to register a CLSID as belonging to a component
// category
HRESULT RegisterCLSIDInCategory(REFCLSID clsid, CATID catid)
{
// Register your component categories information.
ICatRegister* pcr = NULL ;
HRESULT hr = S_OK ;
hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr,
NULL,
CLSCTX_INPROC_SERVER,
IID_ICatRegister,
(void**)&pcr);
if (SUCCEEDED(hr))
{
// Register this category as being "implemented" by
// the class.
CATID rgcatid[1] ;
rgcatid[0] = catid;
hr = pcr->RegisterClassImplCategories(clsid, 1, rgcatid);
}
if (pcr != NULL)
pcr->Release();
return hr;
}
- Modify the DllRegisterServer to mark the control as safe.Locate the
implementation of DllRegisterServer in a .cpp file in yourproject. You
will need to add several things to this .cpp file. Includethe file that
implements CreateComponentCategory and RegisterCLSIDInCategory:
#include "CatHelp.h"
Define the GUID associated with the safety component categories:
const CATID CATID_SafeForScripting =
{0x7dd95801,0x9882,0x11cf,{0x9f,0xa9,0x00,0xaa,0x00,0x6c,0x42,0xc4}};
const CATID CATID_SafeForInitializing =
{0x7dd95802,0x9882,0x11cf,{0x9f,0xa9,0x00,0xaa,0x00,0x6c,0x42,0xc4}};
Define the GUID associated with your control. For simplicity, you can
borrow the GUID from the IMPLEMENT_OLECREATE_EX macro in the main .cpp
file for the control. Adjust the format slightly so that it looks like
the following:
const GUID CDECL BASED_CODE _ctlid =
{ 0x43bd9e45, 0x328f, 0x11d0,
{ 0xa6, 0xb9, 0x0, 0xaa, 0x0, 0xa7, 0xf, 0xc2 } };
To mark your control as both Safe for Scripting and Initialization,
modify the DllRegisterServer function as follows:
STDAPI DllRegisterServer(void)
{
AFX_MANAGE_STATE(_afxModuleAddrThis);
if (!AfxOleRegisterTypeLib(AfxGetInstanceHandle(), _tlid))
return ResultFromScode(SELFREG_E_TYPELIB);
if (!COleObjectFactoryEx::UpdateRegistryAll(TRUE))
return ResultFromScode(SELFREG_E_CLASS);
if (FAILED( CreateComponentCategory(
CATID_SafeForScripting,
L"Controls that are safely scriptable") ))
return ResultFromScode(SELFREG_E_CLASS);
if (FAILED( CreateComponentCategory(
CATID_SafeForInitializing,
L"Controls safely initializable from persistent data") ))
return ResultFromScode(SELFREG_E_CLASS);
if (FAILED( RegisterCLSIDInCategory(
_ctlid, CATID_SafeForScripting) ))
return ResultFromScode(SELFREG_E_CLASS);
if (FAILED( RegisterCLSIDInCategory(
_ctlid, CATID_SafeForInitializing) ))
return ResultFromScode(SELFREG_E_CLASS);
return NOERROR;
}
You would not normally modify the DllUnregisterServer function for these
two reasons:
- You would not want to remove a component category because other controls
may be using it.
- Although there is an UnRegisterCLSIDInCategory function defined, by
default DllUnregisterServer removes the control's entry from the
registry entirely. Therefore, removing the category from the control's
registration is of little use.
After compiling and registering your control, you should find the following
entries in the registry:
HKEY_CLASSES_ROOT\Component
Categories\{7DD95801-9882-11CF-9FA9-00AA006C42C4}
HKEY_CLASSES_ROOT\Component
Categories\{7DD95802-9882-11CF-9FA9-00AA006C42C4}
HKEY_CLASSES_ROOT\CLSID\{"your controls GUID"}\Implemented
Categories\{7DD95801-9882-11CF-9FA9-00AA006C42C4}
HKEY_CLASSES_ROOT\CLSID\{"your controls GUID"}\Implemented
Categories\{7DD95802-9882-11CF-9FA9-00AA006C42C4}
REFERENCES
Internet Client SDK - Component Development - Safe Initialization and
Scripting for ActiveX Controls
Additional query words:
safety scripting persistence initialization
Keywords : kbole kbfasttip kbMFC kbVC kbVC420 kbVC500 kbVC600 AXSDKControls InetSDKSafeControl
Version : Winnt:4.2,5.0,6.0
Platform : winnt
Issue type : kbhowto
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