DOCUMENT:Q96772  05-NOV-1999  [crossnet]
TITLE   :HOWTO: Use WNetGetUser() in Windows for Workgroups
PRODUCT :Windows for Workgroups and Windows NT Networking Issues
PROD/VER::3.1,3.11
OPER/SYS:
KEYWORDS:kbnetwork kbAPI kbSDKPlatform kbOSWin310 kbWNet kbOSWin311 kbGrpDSNet

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) for Windows for Workgroups, versions 3.1, 3.11 
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SUMMARY
=======

WNetGetUser() is documented on page 194 in the Microsoft Windows Device Driver
Kit (DDK) "Device Driver Adaptation Guide" for version 3.1. This function can be
used to retrieve the current user name of the user logged on to the network
underlying Windows. However, when using this function in Microsoft Windows for
Workgroups, WNetGetUser() returns WN_SUCCESS but the user name string is empty.
Because WFWNET.DRV is a multinet driver, the network that supports WNetGetUser()
must be activated before using this function.

MORE INFORMATION
================

Until the release of the Windows for Workgroups SDK, WNetGetUser() was used
internally by Windows. It is documented in the version 3.1 "Device Driver
Adaptation Guide" for network device driver developers. Now, the Windows for
Workgroups SDK allows you to call WNetGetUser() from an application; however,
when using this function on a system with a multinet driver, the supporting
network must be activated first using MNetSetNextTarget(). If the target network
has not been set, the function returns WN_SUCCESS but the returned string for
the user name is empty. This is documented in the description of
MNetSetNextTarget() in the Windows for Workgroups SDK.

It is not sufficient to just call MNetSetNextTarget() before WNetGetUser(). The
current target network may not support WNetGetUser(). To properly set the target
network to use WNetGetUser(), the networks must be enumerated and WNetGetUser()
called for each network. If WNetGetUser() does not return WN_SUCCESS, then
enumerate the next target network and iterate this loop. If the loop iterates
through all of the networks but WNetGetUser() never returns WN_SUCCESS, then
none of the target networks support WNetGetUser().

To determine whether a system supports multinet operations, WNetGetCaps() can be
used with WNNC_NET_TYPE. The return value has the WNNC_NET_MultiNet (0x8000) set
if the system supports multinet operations.

Sample Code
-----------

    #include <winnet.h>

      // 
      // Function:  NetGetCaps
      // 
      // Purpose:   Attempts to Call WNetGetCaps from USER.EXE
      // 
      // Returns:   See WNetGetCaps.  If the entry point cannot be located,
      //            returns NULL
      // 

      WORD NetGetCaps( WORD wCaps )
      {
         typedef         WORD (CALLBACK *LPFNWNETGETCAPS)( WORD );

         LPFNWNETGETCAPS lpfnWNetGetCaps;
         WORD            wNetType = NULL;
         HINSTANCE       hInst;

         // Get the entry point for WNetGetUser from USER.EXE. USER implements
         // the function by calling through to the network driver.
         hInst = LoadLibrary( "USER.EXE" );
         if ( !( lpfnWNetGetCaps = (LPFNWNETGETCAPS)
                                   GetProcAddress( hInst, "WNETGETCAPS" )) )
         {
            OutputDebugString("Could not locate WNetGetCaps entry point.\n");
         }
         else
            // Make the call
            wNetType = (*lpfnWNetGetCaps)( wCaps );

         return wNetType;
      }

      // 
      // Function:  NetGetUser
      // 
      // Purpose:   Attempts to call WNetGetUser from USER.EXE
      // 
      // Returns:   TRUE if the function succeeded, otherwise FALSE.
      // 

      BOOL NetGetUser (LPSTR lpszUserName, int *pcb )
      {
         typedef BOOL (CALLBACK *LPFNGETUSER)( LPSTR, int * );

         // Find the entry point for WNetGetUser in USER.EXE
         HINSTANCE   hInst       = LoadLibrary( "USER.EXE" );
         LPFNGETUSER lpfnGetUser =
            (LPFNGETUSER) GetProcAddress( hInst, "WNETGETUSER" );

         if (!lpfnGetUser)
            return FALSE;

         // See if this computer includes multinet support
         if ( NetGetCaps( WNNC_NET_TYPE ) & WNNC_NET_MultiNet )
         {
            // 
            // Multinet support found.  Get entry points to the MNet APIs
            // 

            typedef WORD (CALLBACK *LPFNMNETNETWORKENUM)( HANDLE FAR * );
            typedef WORD (CALLBACK *LPFNMNETSETNEXTTARGET)( HANDLE );

            LPFNMNETNETWORKENUM   lpfnMNetNetworkEnum;
            LPFNMNETSETNEXTTARGET lpfnMNetSetNextTarget;

            OutputDebugString("GetUser: WNNC_NET_MultiNet is set.\n");

            // Get the module handle for the network driver
            hInst = (HINSTANCE) NetGetCaps( 0xFFFF );

            // Get the entry points
            lpfnMNetNetworkEnum   =
               (LPFNMNETNETWORKENUM)GetProcAddress(hInst,"MNETNETWORKENUM");
            lpfnMNetSetNextTarget =
               (LPFNMNETSETNEXTTARGET)GetProcAddress
                                                  (hInst,"MNETSETNEXTTARGET");

            // If both entry points were located, use them
            if ( lpfnMNetNetworkEnum && lpfnMNetSetNextTarget )
            {
               HANDLE hEnum   = NULL;
               WORD   wResult = lpfnMNetNetworkEnum( &hEnum );

               while ( wResult == WN_SUCCESS )
               {
                  lpfnMNetSetNextTarget( hEnum );     // activate that network
                  wResult = lpfnGetUser( lpszUserName, pcb );

                  if ( wResult == WN_SUCCESS )
                     return TRUE;

                  OutputDebugString
                                ("WNetGetUser failed, try next provider.\n");

                  // otherwise, try the next one for WNetGetUser support
                  wResult = lpfnMNetNetworkEnum( &hEnum );
               }

               return FALSE;
            }

            // Entry points for the MNet APIs we need weren't located.
            // Try calling WNetGetUser anyway. Note: Windows NT 3.51 gives
            // this behavior

            OutputDebugString("Warning - WFWNET.DRV doesn't contain \ 
               entry points for MNetNetworkEnum and/or MNetSetNextTarget.\n");
         }

         WORD wResult = lpfnGetUser( lpszUserName, pcb );

         return (wResult) ? FALSE : TRUE;
      }

Additional query words: username multi-net

======================================================================
Keywords          : kbnetwork kbAPI kbSDKPlatform kbOSWin310 kbWNet kbOSWin311 kbGrpDSNet 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK311
Version           : :3.1,3.11
Issue type        : kbhowto

=============================================================================

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