Platform SDK: Network Management

NetSessionEnum

The NetSessionEnum function provides information about sessions established on a server.

Security Requirements

Only members of the Administrators or Account Operators local group can successfully execute the NetSessionEnum function at level 1 or level 2. No special group membership is required for level 0 or level 10 calls.

Windows NT/2000: The parameter order is as follows.

NET_API_STATUS NetSessionEnum(
  LPWSTR servername,     
  LPWSTR UncClientName,  
  LPWSTR username,       
  DWORD level,           
  LPBYTE *bufptr,        
  DWORD prefmaxlen,      
  LPDWORD entriesread,   
  LPDWORD totalentries,  
  LPDWORD resume_handle  
);

Windows 95/98: The calling application must use the cbBuffer parameter to specify the size, in bytes, of the information buffer pointed to by the pbBuffer parameter. (The cbBuffer parameter replaces the Windows NT/Windows 2000 prefmaxlen parameter.) Neither a user name parameter nor a resume handle parameter is available on this platform. Therefore, the parameter list is as follows.

extern API_FUNCTION
 NetSessionEnum(
  const char FAR * pszServer,         
  short sLevel,                       
  char FAR * pbBuffer,                
  unsigned short  cbBuffer,           
  unsigned short FAR * pcEntriesRead, 
  unsigned short FAR * pcTotalAvail   
);

Parameters

servername

[in] Pointer to a Unicode (Windows NT/2000) or ANSI (Windows 95/98) string specifying the name of the remote server on which the function is to execute. The string must begin with \\. If this parameter is NULL, the local computer is used.

UncClientName

[in] Pointer to a Unicode string specifying the name of the computer session for which information is to be returned. If this parameter is NULL, NetSessionEnum returns information for all computer sessions on the server.

username

[in] Pointer to a Unicode string specifying the name of the user for which information is to be returned. If this parameter is NULL, NetSessionEnum returns information for all users.

level

[in] Specifies the information level of the data. This parameter can be one of the following values.

Windows NT/2000: The following levels are valid.

Value Meaning

0 Return the name of the computer that established the session. The bufptr parameter points to an array of SESSION_INFO_0 structures.

1 Return the name of the computer, name of the user, and open files, pipes, and devices on the computer. The bufptr parameter points to an array of SESSION_INFO_1 structures.

2 In addition to the information indicated for level 1, return the type of client and how the user established the session. The bufptr parameter points to an array of SESSION_INFO_2 structures.

10 Return the name of the computer, name of the user, and active and idle times for the session. The bufptr parameter points to an array of SESSION_INFO_10 structures.

502 Return the name of the computer; name of the user; open files, pipes, and devices on the computer; and the name of the transport the client is using. The bufptr parameter points to an array of SESSION_INFO_502 structures.

Value	Meaning
0	Return the name of the computer that established the session. The bufptr parameter points to an array of SESSION_INFO_0 structures.
1	Return the name of the computer, name of the user, and open files, pipes, and devices on the computer. The bufptr parameter points to an array of SESSION_INFO_1 structures.
2	In addition to the information indicated for level 1, return the type of client and how the user established the session. The bufptr parameter points to an array of SESSION_INFO_2 structures.
10	Return the name of the computer, name of the user, and active and idle times for the session. The bufptr parameter points to an array of SESSION_INFO_10 structures.
502	Return the name of the computer; name of the user; open files, pipes, and devices on the computer; and the name of the transport the client is using. The bufptr parameter points to an array of SESSION_INFO_502 structures.

Windows 95/98: The following level is valid.

Value Meaning

50 Return the name of the computer, name of the user, open files on the computer, and the name of the transport protocol the client is using. The pbBuffer parameter points to an array of session_info_50 structures.

bufptr

Value	Meaning
50	Return the name of the computer, name of the user, open files on the computer, and the name of the transport protocol the client is using. The pbBuffer parameter points to an array of session_info_50 structures.

[out] Pointer to the buffer that receives the data. The format of this data depends on the value of the level parameter.

Windows NT/2000: This buffer is allocated by the system and must be freed using the NetApiBufferFree function. Note that you must free the buffer even if the function fails with ERROR_MORE_DATA.

Windows 95/98: The caller must allocate and deallocate this buffer.

prefmaxlen

[in] Specifies the preferred maximum length of returned data, in bytes. If you specify MAX_PREFERRED_LENGTH, the function allocates the amount of memory required for the data. If you specify another value in this parameter, it can restrict the number of bytes that the function returns. If the buffer size is insufficient to hold all entries, the function returns ERROR_MORE_DATA. For more information, see Network Management Function Buffers and Network Management Function Buffer Lengths.

entriesread

[out] Pointer to a value that receives the count of elements actually enumerated.

totalentries

[out] Pointer to a value that receives the total number of entries that could have been enumerated from the current resume position.

resume_handle

[in/out] Pointer to a DWORD value that contains a resume handle which is used to continue an existing session search. The handle should be zero on the first call and left unchanged for subsequent calls. If resume_handle is NULL, no resume handle is stored.

Return Values

If the function succeeds, the return value is NERR_Success.

If the function fails, the return value can be one of the following error codes.

Value	Meaning
ERROR_ACCESS_DENIED	The user does not have access to the requested information.
ERROR_INVALID_LEVEL	The value specified for the level parameter is invalid.
ERROR_INVALID_PARAMETER	The specified parameter is invalid.
ERROR_MORE_DATA	More entries are available. Specify a large enough buffer to receive all entries.
ERROR_NOT_ENOUGH_MEMORY	Insufficient memory is available.
NERR_ClientNameNotFound	A session does not exist with the computer name.
NERR_InvalidComputer	The computer name is invalid.
NERR_UserNotFound	The user name could not be found.

Remarks

Windows 95/98: See the NetSessionEnum Sample (Windows 95/98) topic to view a code sample that demonstrates how to use the NetSessionEnum function.

Windows NT/2000: The following code sample demonstrates how to retrieve information about current sessions using a call to the NetSessionEnum function. The sample calls NetSessionEnum, specifying information level 10 (SESSION_INFO_10). The sample loops through the entries and prints the retrieved information. Finally, the code prints the total number of sessions enumerated and frees the memory allocated for the information buffer.

#ifndef UNICODE
#define UNICODE
#endif

#include <stdio.h>
#include <assert.h>
#include <windows.h> 
#include <lm.h>

int wmain(int argc, wchar_t *argv[])
{
   LPSESSION_INFO_10 pBuf = NULL;
   LPSESSION_INFO_10 pTmpBuf;
   DWORD dwLevel = 10;
   DWORD dwPrefMaxLen = -1;
   DWORD dwEntriesRead = 0;
   DWORD dwTotalEntries = 0;
   DWORD dwResumeHandle = 0;
   DWORD i;
   DWORD dwTotalCount = 0;
   LPTSTR pszServerName = NULL;
   LPTSTR pszClientName = NULL;
   LPTSTR pszUserName = NULL;
   NET_API_STATUS nStatus;
   //
   // Check command line arguments.
   //
   if (argc > 4)
   {
      wprintf(L"Usage: %s [\\\\ServerName] [\\\\ClientName] [UserName]\n", argv[0]);
      exit(1);
   }

   if (argc >= 2)
      pszServerName = argv[1];

   if (argc >= 3)
      pszClientName = argv[2];

   if (argc == 4)
      pszUserName = argv[3];
   //
   // Call the NetSessionEnum function, specifying level 10.
   //
   do // begin do
   {
      nStatus = NetSessionEnum(pszServerName,
                               pszClientName,
                               pszUserName,
                               dwLevel,
                               (LPBYTE*)&pBuf,
                               dwPrefMaxLen,
                               &dwEntriesRead,
                               &dwTotalEntries,
                               &dwResumeHandle);
      //
      // If the call succeeds,
      //
      if ((nStatus == NERR_Success) || (nStatus == ERROR_MORE_DATA))
      {
         if ((pTmpBuf = pBuf) != NULL)
         {
            //
            // Loop through the entries.
            //
            for (i = 0; (i < dwEntriesRead); i++)
            {
               assert(pTmpBuf != NULL);

               if (pTmpBuf == NULL)
               {
                  fprintf(stderr, "An access violation has occurred\n");
                  break;
               }
               //
               // Print the retrieved data. 
               //
               wprintf(L"\n\tClient: %s\n", pTmpBuf->sesi10_cname);
               wprintf(L"\tUser:   %s\n", pTmpBuf->sesi10_username);
               printf("\tActive: %d\n", pTmpBuf->sesi10_time);
               printf("\tIdle:   %d\n", pTmpBuf->sesi10_idle_time);

               pTmpBuf++;
               dwTotalCount++;
            }
         }
      }
      //
      // Otherwise, indicate a system error.
      //
      else
         fprintf(stderr, "A system error has occurred: %d\n", nStatus);
      //
      // Free the allocated memory.
      //
      if (pBuf != NULL)
      {
         NetApiBufferFree(pBuf);
         pBuf = NULL;
      }
   }
   // 
   // Continue to call NetSessionEnum while 
   //  there are more entries. 
   // 
   while (nStatus == ERROR_MORE_DATA); // end do

   // Check again for an allocated buffer.
   //
   if (pBuf != NULL)
      NetApiBufferFree(pBuf);
   //
   // Print the final count of sessions enumerated.
   //
   fprintf(stderr, "\nTotal of %d entries enumerated\n", dwTotalCount);

   return 0;
}

If you are programming for Active Directory, you may be able to call certain Active Directory Service Interface (ADSI) methods to achieve the same functionality you can achieve by calling the network management session functions. For more information, see IADsSession and IADsFileServiceOperations.

Requirements