Question

In my Delphi (on Windows Xp) program I’d like to check available WiFi networks. Do you have any idea how to do it? Best is probably to use MS WlanScan API function but I did not found an example. Can someone help me?

Answer 1

You can use the Native Wifi API, available since Windows Vista and Windows XP. Older versions of Windows are not supported.

In this link you can find a very nice translation of the headers.

I wrote this code using these headers. Tested in Delphi 2007 and Windows Vista.

program DetectWifiUsingDelphi;

{$APPTYPE CONSOLE}

uses
  Windows,
  SysUtils,
  //TypInfo,
  nduWlanAPI   in 'nduWlanAPI.pas',
  nduWlanTypes in 'nduWlanTypes.pas';


function DOT11_AUTH_ALGORITHM_To_String( Dummy :Tndu_DOT11_AUTH_ALGORITHM):String;
begin
    Result:='';
    case Dummy of
        DOT11_AUTH_ALGO_80211_OPEN          : Result:= '80211_OPEN';
        DOT11_AUTH_ALGO_80211_SHARED_KEY    : Result:= '80211_SHARED_KEY';
        DOT11_AUTH_ALGO_WPA                 : Result:= 'WPA';
        DOT11_AUTH_ALGO_WPA_PSK             : Result:= 'WPA_PSK';
        DOT11_AUTH_ALGO_WPA_NONE            : Result:= 'WPA_NONE';
        DOT11_AUTH_ALGO_RSNA                : Result:= 'RSNA';
        DOT11_AUTH_ALGO_RSNA_PSK            : Result:= 'RSNA_PSK';
        DOT11_AUTH_ALGO_IHV_START           : Result:= 'IHV_START';
        DOT11_AUTH_ALGO_IHV_END             : Result:= 'IHV_END';
    end;
End;

function DOT11_CIPHER_ALGORITHM_To_String( Dummy :Tndu_DOT11_CIPHER_ALGORITHM):String;
Begin
    Result:='';
    case Dummy of
    DOT11_CIPHER_ALGO_NONE      : Result:= 'NONE';
    DOT11_CIPHER_ALGO_WEP40     : Result:= 'WEP40';
    DOT11_CIPHER_ALGO_TKIP      : Result:= 'TKIP';
    DOT11_CIPHER_ALGO_CCMP      : Result:= 'CCMP';
    DOT11_CIPHER_ALGO_WEP104    : Result:= 'WEP104';
    DOT11_CIPHER_ALGO_WPA_USE_GROUP : Result:= 'WPA_USE_GROUP OR RSN_USE_GROUP';
    //DOT11_CIPHER_ALGO_RSN_USE_GROUP : Result:= 'RSN_USE_GROUP';
    DOT11_CIPHER_ALGO_WEP           : Result:= 'WEP';
    DOT11_CIPHER_ALGO_IHV_START     : Result:= 'IHV_START';
    DOT11_CIPHER_ALGO_IHV_END       : Result:= 'IHV_END';
    end;
End;

procedure Scan();
const
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES =$00000001;
var
  hClient              : THandle;
  dwVersion            : DWORD;
  ResultInt            : DWORD;
  pInterface           : Pndu_WLAN_INTERFACE_INFO_LIST;
  i                    : Integer;
  j                    : Integer;
  pAvailableNetworkList: Pndu_WLAN_AVAILABLE_NETWORK_LIST;
  pInterfaceGuid       : PGUID;
  SDummy               : string;
begin
  ResultInt:=WlanOpenHandle(1, nil, @dwVersion, @hClient);
  if  ResultInt<> ERROR_SUCCESS then
  begin
     WriteLn('Error Open CLient'+IntToStr(ResultInt));
     Exit;
  end;

  ResultInt:=WlanEnumInterfaces(hClient, nil, @pInterface);
  if  ResultInt<> ERROR_SUCCESS then
  begin
     WriteLn('Error Enum Interfaces '+IntToStr(ResultInt));
     exit;
  end;

  for i := 0 to pInterface^.dwNumberOfItems - 1 do
  begin
   Writeln('Interface       ' + pInterface^.InterfaceInfo[i].strInterfaceDescription);
   WriteLn('GUID            ' + GUIDToString(pInterface^.InterfaceInfo[i].InterfaceGuid));
   Writeln('');
   pInterfaceGuid:= @pInterface^.InterfaceInfo[pInterface^.dwIndex].InterfaceGuid;

      ResultInt:=WlanGetAvailableNetworkList(hClient,pInterfaceGuid,WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_ADHOC_PROFILES,nil,pAvailableNetworkList);
      if  ResultInt<> ERROR_SUCCESS then
      begin
         WriteLn('Error WlanGetAvailableNetworkList '+IntToStr(ResultInt));
         Exit;
      end;

        for j := 0 to pAvailableNetworkList^.dwNumberOfItems - 1 do
        Begin
           WriteLn(Format('Profile         %s',[WideCharToString(pAvailableNetworkList^.Network[j].strProfileName)]));
           SDummy:=PChar(@pAvailableNetworkList^.Network[j].dot11Ssid.ucSSID);
           WriteLn(Format('NetworkName     %s',[SDummy]));
           WriteLn(Format('Signal Quality  %d ',[pAvailableNetworkList^.Network[j].wlanSignalQuality])+'%');
           //SDummy := GetEnumName(TypeInfo(Tndu_DOT11_AUTH_ALGORITHM),integer(pAvailableNetworkList^.Network[j].dot11DefaultAuthAlgorithm)) ;
           SDummy:=DOT11_AUTH_ALGORITHM_To_String(pAvailableNetworkList^.Network[j].dot11DefaultAuthAlgorithm);
           WriteLn(Format('Auth Algorithm  %s ',[SDummy]));
           SDummy:=DOT11_CIPHER_ALGORITHM_To_String(pAvailableNetworkList^.Network[j].dot11DefaultCipherAlgorithm);
           WriteLn(Format('Auth Algorithm  %s ',[SDummy]));
           Writeln('');
        End;
  end;

  WlanCloseHandle(hClient, nil);

end;
begin
  try
    Scan();
    Readln;
  except
    on E:Exception do
      Writeln(E.Classname, ': ', E.Message);
  end;
end.

alt text http://i33.tinypic.com/2z83ubt.jpg

Bye.