how to detect connection closed by server?

[Joe Wong]

Hi Jacek,

  If the server never send some reply back to the client, it is not possible
for the client to determine if the server had actually received the data (
e.g., server called accept() but not calling recv() to read data from
client, then close() the client socket right away ). Am I right? If this is
the case, I can't really rely on the socket function in the client program
to tell if the server has read the data..

Regards,

- Wong

----- Original Message ----- 
From: "Jacek Trzmiel" <sc0rp at hot.pl>
To: "Joe Wong" <joewong at mango.cc>
Cc: <python-list at python.org>
Sent: Wednesday, March 24, 2004 1:42 PM
Subject: Re: how to detect connection closed by server?


>
> Joe Wong wrote:
> > Client:
> > - create socket
> > - connect to port XYZ at server
> > - send some data to server
> > - close the socket
> >
> > The problem I found is that, after the server perform the listen()
> > call, the client program can sucessfully perform connect(), send() and
> > close() on the socket
>
> AFAIR with T/TCP it's entriely possible to open connection, send small
> payload and close connection in one single IP packet.
>
> > even the server process does not perform the
> > accept() and recv() call. Is this a general behaviour of the socket or
> > I am not writing my program properly?
>
> Close only sending part of the socket and then block on read.  It will
> either:
> - report EOF if server accepted and then closed connection without
> sending any data,
> - return some data if server sent it,
> - report some kind of error otherwise.
>
> Best regards,
> Jacek.
>
>