Determining URL from ActiveX Control

This is a simple technique to determine the URL of the web page in which the ActiveX control is hosted.

Introduction

I had to develop ActiveX controls for web based applications. Some of these controls were manipulating the local resources. To disable malicious use of these control by others through scripting, I had to implement security check. I decided to implement a simple security scheme where I determine the url in which the control is hosted. If the url comes from our domain, I enabled its functionality.

I used GetMoniker method of IOleClientSite Interface.The IMoniker interface has GetDisplayName() method,
which returns a user-readable representation of the moniker.

Code:

 HRESULT hrResult	= S_FALSE;
 IOleClientSite *pClientSite = NULL;
 IMoniker* pMoniker	= NULL;
 LPOLESTR sDisplayName;

 // If using ATL to develop, use the m_spClientSite data
 // member of CComControl class.

 // If using MFC, use the following code: 
 // (member function of COleControl class 
 // - don't forget to call release)
 // pClientSite = GetClientSite();

 hrResult = m_spClientSite->GetMoniker(OLEGETMONIKER_TEMPFORUSER,
                                       OLEWHICHMK_CONTAINER,
                                       &pMoniker);
 if(SUCCEEDED(hrResult))
 {
  hrResult = pMoniker->GetDisplayName(NULL,
                                      NULL,
                                      &sDisplayName);
  pMoniker->Release();
 }

 //TODO : relevant processing with sDisplayName and
 //free sDisplayName using SysFreeString()