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The socket error only happens when the Host is the loppback IP 127.0.0.1


"Dhr. Kweetnie" <omni@scient.net> schreef in bericht
news:40e5328f$1@newsgroups.borland.com...
> 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
>
>

"Dhr. Kweetnie" <omni@scient.net> wrote in message
news:40e5328f$1@newsgroups.borland.com...

> 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!

It is an exception to begin with, so yes you can catch it as an exception.

>     catch( EIdSocketError& e )

Change that to this instead:

    catch( const EIdException &e )

Or:

    catch( const Exception &e )


Gambit