How To Use ADSI to Query the Global Catalog for a UPN

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Article ID: 252490 - View products that this article applies to.
This article was previously published under Q252490
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SUMMARY

A User Principal Name (UPN) is composed of a user account logon name and the user principal name suffix joined by the "@" sign. The UPN allows for a simplified logon. Most commonly, the UPN is the user's e-mail address. Because the user principal name provides the ability to perform a single logon anywhere in the enterprise, the UPN is required to be unique across the entire Microsoft Windows 2000 forest. This is achieved by querying the Global Catalog for an existing user with that UPN.

This article contains code samples written in Microsoft Visual Basic and Microsoft Visual C++ that demonstrate how to query the Global Catalog for a UPN.

MORE INFORMATION

Before setting a UPN for a new or existing user, the Global Catalog should be queried. The Active Directory Users and Computers Microsoft Management Console (MMC) snap-in queries the Global Catalog, as should any other application making modifications to the UPN. Although querying the Global Catalog does not absolutely guarantee that a UPN is unique across the enterprise, it is a recommended practice that greatly reduces the chances of duplication. Following is a Microsoft Visual Basic/VBScript code example that uses Active Directory Services Interfaces (ADSI) Lightweight Directory Access Protocol (LDAP) provider to query the Global Catalog for a UPN:
'The following lines are commented for use in VBScript
Dim oConnection 'As ADODB.Connection
Dim oRecordset 'As ADODB.Recordset
Dim strQuery 'As String
Dim strUPN 'As String
Dim oCont 'As IADsContainer
Dim oGC 'As IADs
Dim strADsPath 'As String

'TO DO : Change the UPN to fit your environment
strUPN = "User1@Corp.com"

'Find the Global Catalog server
Set oCont = GetObject("GC:")
For Each oGC In oCont
  strADsPath = oGC.ADsPath
Next

Set oConnection = CreateObject("ADODB.Connection")
Set oRecordset = CreateObject("ADODB.Recordset")
oConnection.Provider = "ADsDSOObject"  'The ADSI OLE-DB provider

oConnection.Open "ADs Provider"
strQuery = "<" & strADsPath & ">;(&(objectClass=user)(objectCategory=person)(userprincipalName=" & strUPN & "));userPrincipalName,cn,distinguishedName;subtree"
Set oRecordset = oConnection.Execute(strQuery)

If oRecordset.EOF And oRecordset.BOF Then
  MsgBox "No duplicate UPN found"
Else
  While Not oRecordset.EOF
     MsgBox oRecordset.Fields("userPrincipalName") & " found!" & vbLf & oRecordset.Fields("cn") & " located at " & oRecordset.Fields("distinguishedName")
     oRecordset.MoveNext
Wend
End If

Set oCont = Nothing
Set oGC = Nothing
Set oRecordset = Nothing
Set oConnection = Nothing
				

Following is a similar example for use in Microsoft Visual C++:
#define UNICODE
#define _UNICODE
#include <wchar.h>
#include <activeds.h>

HRESULT FindUPN(LPOLESTR bstrUPN);

int wmain(int argc, wchar_t *argv[])
{
	LPOLESTR lpstrUPN=NULL;
	
	//Initialize COM
	CoInitialize(NULL);
	
	HRESULT hr = S_OK;
	
	if(argc != 2)
	{
		wprintf(L"This program will query the GC for the existence of a UPN\n");
		wprintf(L"Please enter the UPN to search for\n");

	}
	else
	{
		lpstrUPN = argv[1];
		hr = FindUPN(lpstrUPN);
		if (FAILED(hr))
			wprintf(L"Search failed with hr: %d\n", hr);
	}
	
	// Uninitialize COM
	CoUninitialize();
	return 0;
}


HRESULT FindUPN(LPOLESTR pszUPN)
{
    HRESULT hr = E_FAIL;
    HRESULT hrGC = S_OK;
	
	VARIANT var;
	ULONG lFetch;
	
    // Interface Pointers
    IDirectorySearch *pGCSearch = NULL;
	IADsContainer *pContainer = NULL;
    IUnknown *pUnk = NULL;
	IEnumVARIANT *pEnum = NULL;
   	IDispatch *pDisp = NULL;
    IADs *pADs = NULL;
	
	//Bind to Global Catalog
    hr = ADsOpenObject(L"GC:",  //NT 4.0, Win9.x client must include the servername, e.g GC://myServer
		NULL,
		NULL,
		ADS_SECURE_AUTHENTICATION, //Use Secure Authentication
		IID_IADsContainer,
		(void**)&pContainer);
	
	if (SUCCEEDED(hr))
	{
		hr = pContainer->get__NewEnum( &pUnk );
		if (SUCCEEDED(hr))
		{
			hr = pUnk->QueryInterface( IID_IEnumVARIANT, (void**) &pEnum );
			if (SUCCEEDED(hr))
			{
				// Now Enumerate--there should be only one item.
				hr = pEnum->Next( 1, &var, &lFetch );
				if (SUCCEEDED(hr))
				{
					while( hr == S_OK )
					{
						if ( lFetch == 1 )
						{
							pDisp = V_DISPATCH(&var);
							hr = pDisp->QueryInterface( IID_IDirectorySearch, (void**)&pGCSearch); 
							hrGC = hr;
						}
						VariantClear(&var);
						hr = pEnum->Next( 1, &var, &lFetch );
					};
				}
			}
			if (pEnum)
				pEnum->Release();
		}
		if (pUnk)
			pUnk->Release();
	}
	if (pContainer)
		pContainer->Release();
	
	
	if (FAILED(hrGC))
	{
		if (pGCSearch)
			pGCSearch->Release();
		return hrGC;
	}
	
	//Create search filter
	WCHAR rgSearchFilter[1024];
	wsprintf(rgSearchFilter,L"(&(objectCategory=person)(objectClass=user)(userPrincipalName=%s))", pszUPN);
	
    //Search entire subtree from root.
	ADS_SEARCHPREF_INFO SearchPrefs;
	SearchPrefs.dwSearchPref = ADS_SEARCHPREF_SEARCH_SCOPE;
	SearchPrefs.vValue.dwType = ADSTYPE_INTEGER;
	SearchPrefs.vValue.Integer = ADS_SCOPE_SUBTREE;
    DWORD dwNumPrefs = 1;
	
	// COL for iterations
    ADS_SEARCH_COLUMN col;
	
    // Handle used for searching
    ADS_SEARCH_HANDLE hSearch;
	
	// Set the search preference
    hr = pGCSearch->SetSearchPreference( &SearchPrefs, dwNumPrefs);
    if (FAILED(hr))
        return hr;
	// Set attributes to return
	CONST DWORD dwAttrNameSize = 3;
    LPOLESTR pszAttribute[dwAttrNameSize] = {L"cn",L"distinguishedName",L"userPrincipalName"};
	
    // Execute the search
    hr = pGCSearch->ExecuteSearch(rgSearchFilter,
		pszAttribute,
		dwAttrNameSize,
		&hSearch
		);
	if ( SUCCEEDED(hr) )
	{    
		if(pGCSearch->GetFirstRow(hSearch) ==  S_ADS_NOMORE_ROWS )
		{
			wprintf(L"There is no UPN with that value\n");
		}
		else   //The UPN was found
		{
			do
			{	
				// loop through the array of passed column names,
				// print the data for each column
				for (DWORD x = 0; x < dwAttrNameSize; x++)
				{
					
					// Get the data for this column
					hr = pGCSearch->GetColumn( hSearch, pszAttribute[x], &col );
					
					if ( SUCCEEDED(hr) )
					{
						// Print the data for the column and free the column
						// Note the attributes we asked for are type CaseIgnoreString.
						wprintf(L"%s: %s\r\n",pszAttribute[x],col.pADsValues->CaseIgnoreString); 
						pGCSearch->FreeColumn( &col );
					}
					else
						wprintf(L"<%s property is not a string>",pszAttribute[x]);
				}
				wprintf(L"------------------------------\n");
			}
			while( pGCSearch->GetNextRow( hSearch) != S_ADS_NOMORE_ROWS );
		}
		// Close the search handle to clean up
        pGCSearch->CloseSearchHandle(hSearch);

	} 
	if (pGCSearch)
		pGCSearch->Release();
    return hr;
}


				

REFERENCES

For information about duplicate user principal names see the following article in the Microsoft Knowledge Base:
251359 PRB: Possible Duplicate User Principal Names

For additional information about Active Directory Services Interfaces (ADSI), see the following web site:
http://msdn2.microsoft.com/library/aa772170.aspx

For code examples of retrieving UPN suffixes, creating users, and modifying UPNs, see the samples and documentation located in the Platform SDK, which is available from the following Microsoft Web site:
http://www.microsoft.com/msdownload/platformsdk/sdkupdate/downlevel.htm

Properties

Article ID: 252490 - Last Review: October 12, 2007 - Revision: 3.7
APPLIES TO
  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Active Directory Service Interfaces 2.0
  • Microsoft Active Directory Service Interfaces 2.5
Keywords: 
kbglobalcatalog kbhowto KB252490

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