Como saber se estou conectado à internet

interface
uses
Windows, SysUtils, Registry, WinSock, WinInet;

type
TConnectionType = (ctNone, ctProxy, ctDialup);

function ConnectedToInternet : TConnectionType;
function RasConnectionCount : Integer;


implementation

const
cERROR_BUFFER_TOO_SMALL = 603;
cRAS_MaxEntryName = 256;
cRAS_MaxDeviceName = 128;
cRAS_MaxDeviceType = 16;
type
ERasError = class(Exception);

HRASConn = DWord;
PRASConn = ^TRASConn;
TRASConn = record
dwSize: DWORD;
rasConn: HRASConn;
szEntryName: Array[0..cRAS_MaxEntryName] Of Char;
szDeviceType : Array[0..cRAS_MaxDeviceType] Of Char;
szDeviceName : Array [0..cRAS_MaxDeviceName] of char;
end;

TRasEnumConnections =
function (RASConn: PrasConn; { buffer para receber dados da conexao}
var BufSize: DWord; { tamanho em bytes do buffer }
var Connections: DWord { numero de conexoes escritas no buffer }
): LongInt; stdcall;


function ConnectedToInternet: TConnectionType;
var
    Reg : TRegistry;
    bUseProxy : Boolean;
    UseProxy : LongWord;
begin
    Result := ctNone;
    Reg := TRegistry.Create;
    with REG do
    try
    try
        RootKey := HKEY_CURRENT_USER;
        if OpenKey('\Software\Microsoft\Windows\CurrentVersion\Internet settings',False) then begin
            //I just try to read it, and trap an exception
            if GetDataType('ProxyEnable') = rdBinary then
                ReadBinaryData('ProxyEnable', UseProxy, SizeOf(LongWord) )
        else begin
            bUseProxy := ReadBool('ProxyEnable');
            if bUseProxy then
                UseProxy := 1
            else
                UseProxy := 0;
        end;
        if (UseProxy <> 0) and ( ReadString('ProxyServer') <> '' ) then Result := ctProxy;
    end;
    except
        //Nao conectado com proxy
    end;
    finally
    Free;
end;

    if Result = ctNone then begin
    if RasConnectionCount > 0 then Result := ctDialup;
    end;
    end;

function RasConnectionCount : Integer;
var
    RasDLL : HInst;
    Conns : Array[1..4] of TRasConn;
    RasEnums : TRasEnumConnections;
    BufSize : DWord;
    NumConns : DWord;
    RasResult : Longint;
begin
    Result := 0;

    //Load the RAS DLL
    RasDLL := LoadLibrary('rasapi32.dll');
    if RasDLL = 0 then exit;

    try
        RasEnums := GetProcAddress(RasDLL,'RasEnumConnectionsA');
        if @RasEnums = nil then
        raise ERasError.Create('RasEnumConnectionsA not found in rasapi32.dll');

        Conns[1].dwSize := Sizeof (Conns[1]);
        BufSize := SizeOf(Conns);

        RasResult := RasEnums(@Conns, BufSize, NumConns);

        If (RasResult = 0) or (Result = cERROR_BUFFER_TOO_SMALL) then Result := NumConns;
    finally
    FreeLibrary(RasDLL);
end;
end;