Enumerating Network Connections

Problem/Question/Abstract:

How to detecting current network connections?

Answer:

From the MS-DOS prompt, you can enumerate the network connections (drives) by using the following command:

   net use

Programmatically, you would call WNetOpenEnum() to start the enumeration of connected resources and WNetEnumResources() to continue the enumeration.

The following sample code enumerates the network connections:

Sample Code

procedure TForm1.Button1Click(Sender: TObject);
var
  i, dwResult: DWORD;
  hEnum: THANDLE;
  lpnrDrv,
    lpnrDrvLoc: PNETRESOURCE;
  s: string;
const
  cbBuffer: DWORD = 16384;
  cEntries: DWORD = $FFFFFFFF;
begin

  dwResult := WNetOpenEnum(RESOURCE_CONNECTED,
    RESOURCETYPE_ANY,
    0,
    nil,
    hEnum);

  if (dwResult <> NO_ERROR) then
  begin
    ShowMessage('Cannot enumerate network drives.');
    Exit;
  end;
  s := '';
  repeat
    lpnrDrv := PNETRESOURCE(GlobalAlloc(GPTR, cbBuffer));
    dwResult := WNetEnumResource(hEnum, cEntries, lpnrDrv, cbBuffer);
    if (dwResult = NO_ERROR) then
    begin
      s := 'Network drives:'#13#10;
      lpnrDrvLoc := lpnrDrv;
      for i := 0 to cEntries - 1 do
      begin
        if lpnrDrvLoc^.lpLocalName <> nil then
          s := s + lpnrDrvLoc^.lpLocalName + #9 + lpnrDrvLoc^.lpRemoteName + #13#10;
        Inc(lpnrDrvLoc);
      end;
    end
    else if dwResult <> ERROR_NO_MORE_ITEMS then
    begin
      s := s + 'Cannot complete network drive enumeration';
      GlobalFree(HGLOBAL(lpnrDrv));
      break;
    end;
    GlobalFree(HGLOBAL(lpnrDrv));
  until (dwResult = ERROR_NO_MORE_ITEMS);
  WNetCloseEnum(hEnum);
  if s = '' then
    s := 'No network connections.';
  ShowMessage(s);
end;