From: Gary Wright <gwtmp01@...>
Date: 2007-03-22T23:51:28+09:00
Subject: Re: How to Distinguish between a Reset packet and a Normal o


On Mar 22, 2007, at 4:52 AM, sairam MP wrote:
> I think its possible,while receiving some data,if the length of data
> received is zero in a blocked receive function then the connection is
> said to be reset by peer.

No.  A 'reset by peer' is a very specific TCP term.  It means that
a packet with the RST bit set has arrived on the connection.  It is
possible to have packets that contain no data (keep alive packets
for instance).  You can't infer that the connection is dead from
that.  But the bigger problem is that you can't even see packet
arrivals from the application.   By the time the data gets to
the application the packet boundaries are unknowable.  Unless you
are talking about kernel programing you are thinking about TCP
in a very misleading way.

It is a common misunderstanding about TCP that if the sender
writes 100 bytes that the receiver will read 100 bytes.  That is,
that the writes of the sender and the reads of the receiver are
always 'paired up'.  This is not the way TCP works. Message
boundaries are not preserved across a TCP stream nor does
each call to 'write' correspond to a single packet on the wire.
TCP can coalesce multiple writes into a single packet and can
also split a single write into multiple packets.


Gary Wright