NetConnectionEnum function (lmshare.h)

Article
10/13/2021

Lists all connections made to a shared resource on the server or all connections established from a particular computer. If there is more than one user using this connection, then it is possible to get more than one structure for the same connection, but with a different user name.

Syntax

NET_API_STATUS NET_API_FUNCTION NetConnectionEnum(
  [in]      LMSTR   servername,
  [in]      LMSTR   qualifier,
  [in]      DWORD   level,
  [out]     LPBYTE  *bufptr,
  [in]      DWORD   prefmaxlen,
  [out]     LPDWORD entriesread,
  [out]     LPDWORD totalentries,
  [in, out] LPDWORD resume_handle
);

Parameters

[in] servername

Pointer to a string that specifies the DNS or NetBIOS name of the remote server on which the function is to execute. If this parameter is NULL, the local computer is used.

This string is Unicode if _WIN32_WINNT or FORCE_UNICODE is defined.

[in] qualifier

Pointer to a string that specifies a share name or computer name for the connections of interest. If it is a share name, then all the connections made to that share name are listed. If it is a computer name (for example, it starts with two backslash characters), then NetConnectionEnum lists all connections made from that computer to the server specified.

This string is Unicode if _WIN32_WINNT or FORCE_UNICODE is defined.

[in] level

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

Value	Meaning
0	Return connection identifiers. The bufptr parameter is a pointer to an array of CONNECTION_INFO_0 structures.
1	Return connection identifiers and connection information. The bufptr parameter is a pointer to an array of CONNECTION_INFO_1 structures.

[out] bufptr

Pointer to the address of the buffer that receives the information. The format of this data depends on the value of the level parameter.

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.

[in] prefmaxlen

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.

[out] entriesread

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

[out] totalentries

Pointer to a value that receives the total number of entries that could have been enumerated from the current resume position. Note that applications should consider this value only as a hint.

[in, out] resume_handle

Pointer to a value that contains a resume handle which is used to continue an existing connection search. The handle should be zero on the first call and left unchanged for subsequent calls. If this parameter is NULL, then no resume handle is stored.

Return value

If the function succeeds, the return value is NERR_Success.

If the function fails, the return value is a system error code. For a list of error codes, see System Error Codes.

Remarks

Administrator, Server or Print Operator, or Power User group membership is required to successfully execute the NetConnectionEnum function.

Examples

The following code sample demonstrates how to list the connections made to a shared resource with a call to the NetConnectionEnum function. The sample calls NetConnectionEnum, specifying information level 1 (CONNECTION_INFO_1). If there are entries to return, it prints the values of the coni1_username and coni1_netname members. If there are no entries to return, the sample prints an appropriate message. Finally, the code sample frees the memory allocated for the information buffer.

#ifndef UNICODE
#define UNICODE
#endif
#include <windows.h>
#include <lm.h>
#include <stdio.h>
#pragma comment(lib, "Netapi32.lib")

void wmain(int argc, wchar_t *argv[ ])
{
   DWORD res, i, er = 0, tr = 0, resume = 0;
   PCONNECTION_INFO_1 p,b;
   LPTSTR lpszServer = NULL, lpszShare = NULL;

   if(argc<2)
      wprintf(L"Syntax: %s [ServerName] ShareName | \\\\ComputerName\n", argv[0]);
   else
   {
      //
      // The server is not the default local computer.
      //
      if(argc>2)
         lpszServer=argv[1];
      //
      // ShareName is always the last argument.
      //
      lpszShare=argv[argc - 1];
      //
      // Call the NetConnectionEnum function,
      //  specifying information level 1.
      //
      res=NetConnectionEnum(lpszServer, lpszShare, 1, (LPBYTE *) &p, MAX_PREFERRED_LENGTH, &er, &tr, &resume);
      //
      // If no error occurred,
      //
      if(res == 0)
      {
         //
         // If there were any results,
         //
         if(er>0)
         {
            b=p;
            //
            // Loop through the entries; print user name and network name.
            //
            for(i=0;i<er;i++)
            {
               printf("%S\t%S\n", b->coni1_username,b->coni1_netname);
               b++;
            }
            // Free the allocated buffer.
            //
            NetApiBufferFree(p);
         }
         // Otherwise, print a message depending on whether 
         //  the qualifier parameter was a computer (\\ComputerName)
         //  or a share (ShareName).
         //
         else
         {
            if(lpszShare[0]=='\\')  
               printf("No connection to %S from %S\n", 
                  (lpszServer == NULL)?TEXT("LocalMachine"):lpszServer, lpszShare);
            else                       
               printf("No one connected to %S\\%S\n",
                  (lpszServer == NULL)?TEXT("\\\\LocalMachine"):lpszServer,lpszShare);
         }        
      }
      //
      // Otherwise, print the error.
      //
      else
         printf("Error: %d\n",res);
   }
   return;
}

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	lmshare.h (include Lm.h)
Library	Netapi32.lib
DLL	Netapi32.dll