COMLicenceFinder: A small tool able to retrieve the Runtime Licence text of ActiveX controls

• Download COMLicenceFinder - 17.38 Kb
• Download source - 14.2 Kb

Introduction

Programming with scripts (VBScript, JScript) is quite an enjoyable experience, you can even develop a script based application using script components. Everybody knows how this kind of programming becomes powerful, taking advantage of ActiveX controls, but if you try to deploy a script using standard Microsoft ActiveX controls (e.g., MsComm for serial communication), then you'll have to overcome an annoying problem: many of such controls require a Runtime License in order to work on the end user PC. By the way, Visual C++ and Visual Basic environments automatically provide, for standard applications, such runtime license for each of the deployed components, but with scripting languages, it's a completely different matter: you are left alone, and have to provide 'by hand' this piece of info. I know of some workarounds out there, namely wrappers built around the target ActiveX control, however, I will show a direct approach in this article. You have to deal with two different problems:

1. Knowing (obtaining) the Runtime License text.
2. Providing such text in your script.

Here, I'll only show how to obtain such Runtime License text (point 2 represents the subject of another article, I think), querying it to the ActiveX. Of course, you must have Visual Studio installed on your PC. I developed a small application, namely ComLicenceFinder, able to recognize all ActiveX controls registered on your PC, and to ask them for that piece of info.

Background

You should know how to use ActiveX controls in a script (see MSDN). A general knowledge of COM is also required (there are a lot of books about COM: inside COM, essential COM, etc...).

Using the application

On loading, ComLicenceFinder queries the registry to obtain and list all ActiveX controls available on the PC. If you are interested about the runtime license info about any of them, first of all, select it and then click the right mouse button, and select, on the newly appeared context menu, the Get info item. The application will try to:

1. Query a IClassFactory interface pointer to the Class Object (or Class Factory) of the selected ActiveX control.
2. Query to the obtained pointer for a new pointer, this time to a IClassFactory2 interface.
3. Call the IClassFactory2::GetLicInfo method.
4. Call the IClassFactory2::RequestLicKey method.

On successful completion of all of the above steps, you will have the requested Runtime License text; however, the result of each step is reported in a field of the listview, that by the way, should be interpreted as follows:

Field	Type	Description	Note
Name	String	Friendly name of the ActiveX control, as found in the registry	-
CLSID	String	Class ID of the ActiveX control.	This is the unique identifier of the ActiveX control, and has to be used by any script requiring the latter.
Creatable	Yes/No	Yes if the IClassFactory interface was successfully obtained	If No, maybe the item corresponds to an incorrect entry in the registry
Lic. Info	Yes/No	Yes if there is a runtime license available	If there isn't a runtime license available, you can still try to use the ActiveX control, perhaps it doesn't require a license at all.
License text	String	The runtime license text	-

The relevant code is contained by the GetLicenceInfo function (I've stripped off some boring parts such as insertions into the listview):

// Query for the Class Object IClassFactory interface pointer
HRESULT hr = CoGetClassObject(uuid, CLSCTX_ALL, NULL, 
             IID_IClassFactory, (void**)&pCF);    
if ( FAILED(hr) ) return;

// Now query for the IClassFactory2 interface pointer.
hr = pCF->QueryInterface(IID_IClassFactory2, (void**)& pCF2);
pCF->Release();    

// Call the GetLicInfo method to obtain licence info
if ( FAILED(hr) ) return;
LICINFO licInfo;
licInfo.cbLicInfo = sizeof(licInfo);
hr = pCF2->GetLicInfo(&licInfo);
if ( FAILED(hr) )
{
    pCF2->Release();
    return;
}
// Is a runtime key available ?
fSuccess = (licInfo.fRuntimeKeyAvail == TRUE && 
            licInfo.fLicVerified == TRUE ) ? true : false;
if (! fSuccess)
{
    pCF2->Release();
    return;
}
    
// Query the Runtime Key (i.e. the runtime licence text)
hr= pCF2->RequestLicKey( 0,  & bstrLic );
if ( FAILED(hr) )
{
    pCF2->Release();
    return;
}
ZeroMemory(buf, BUFSIZE);

// We need a ASCII string
fSuccess = WideCharToMultiByte(CP_ACP, 0, bstrLic, 
           SysStringLen(bstrLic), buf, BUFSIZE, 
           NULL, NULL) == 0 ? false : true;
pCF2->Release();
SysFreeString(bstrLic);
if (! fSuccess )
{
    return;
}

Points of Interest

The context menu Copy item can be used to copy the relevant info (i.e., Name, CLSID, License Text) to the Clipboard (and then to Paste them into your script...).

The Save item of the context menu, on the other hand, saves to a chosen XML file the whole (current) content of the list view (a lookup table for the CLSID of all the ActiveX controls on your PC?!?).

It is worth nothing that the application needs to link the Rpcrt4.lib to use the function UuidFromString only.

History

• First release.