🚀 go-pugleaf

I have an application that needs to test if a UDP Server is listening. If
this server is listening it will acknowledge my test message.
The current implementation uses the NetMaster UDP control which generates a
read event with -1 bytes when sending to a non-existing host failed. But I
want to use the Indy TIdUDPClient because my application already uses a
TIdTCPClient for something else and I don't like to use two different
architectures in one app.

The problem I have with the TIdUDPClient is that if I try to receive the
reply immediately after I send the test message, I get a popup message box
for socket error #10054 ("Connection reset by peer") when the server is not
present. What I expected was to catch it as an exception but this doesn't
happen. Compiling for Release or Debug does not make a difference. I just
don't get the exception!

Is there a better way to test if a server is present?

Here's the code for a minimal test app:

void __fastcall TForm3::TestButtonClick(TObject *Sender)
{
    char RxBuf[64];
    int  RxSz = 64;
    AnsiString PeerIP;
    int PeerPort;
    try
    {
        IndyUDPClient->SendBuffer( "TEST", 4 );
        int Rxd = IndyUDPClient->ReceiveBuffer( RxBuf, RxSz, PeerIP,
PeerPort, 1000 );
        Application->MessageBox( "Server responded", "UDP" ,MB_OK );
    }
    catch( EIdSocketError& e )
    {
        Application->MessageBox( "No Server", "UDP" ,MB_OK  );
    }
}
//--------------------------------------------------------------------------
-
void __fastcall TForm3::IndyUDPClientStatus(TObject *ASender,
      const TIdStatus AStatus, const AnsiString AStatusText)
{
    Application->MessageBox( AStatusText.c_str(), "Status" ,MB_OK  );
}


Thanks, Antoon