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From Davi Arnaut <d...@haxent.com.br>
Subject Re: [Fwd: Re: How to detect is the socket is still open]
Date Wed, 16 Aug 2006 15:36:23 GMT

Em 16/08/2006, às 11:00, Justin Erenkrantz escreveu:

> On 8/16/06, Davi Arnaut <davi@haxent.com.br> wrote:
>> The only portable way to "detect" a broken connection is using
>> or to write/read "ping" data through the socket -- which is what
>> keepalive does.
> How would SO_KEEPALIVE help?  The other end is deliberately closing
> the connection and we need to know that.

It would help detect a broken connection, not a RST state.

> Would a non-blocking read() followed by a poll()/select() be useful?
> We'd still get a 0 back from read() - but if it was the EOF, would the
> state of the socket change to be in the 'exceptional' state then if we
> repoll?  -- justin

Humm, read returning 0 is a EOF, you could also maybe
getsockopt(SO_ERROR) on the socket to confirm the EOF.

Upon receive of a RST the socket should move to the closed
state, and poll should return immediately if the POLLHUP mask
was passed for that socket, and SO_ERROR should be one of
or none if the socket was already closed.

Select is a different beast because of the definition of what is
a "exceptional condition" which may be pending error conditions
or oob data. I think the "exception fd" of select is similar to a poll
with POLLPRI mask, so it shoud'nt signal a connection reset.

Davi Arnaut

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