Re: [Lksctp-developers] udp style sendmsg() + no-data + MSG_EOF/MSG_ABORT establishes an association

[Sridhar S. <sr...@us...>]

On Tue, 25 May 2004, La Monte H.P. Yarroll wrote:

> Sridhar Samudrala wrote:
>
> >On Mon, 24 May 2004, La Monte H.P. Yarroll wrote:
> >
> >
> >
> >>Ugh.  Yeah, I suppose it is reasonable to require that users of 1-many who
> >>want to mix SCTP_AUTOCLOSE with manual association shutdown need to
> >>subscribe
> >>to notifications for close.  I'm still not thrilled about it, but I don't
> >>think it's worth the overhead to try special-casing this...
> >>
> >>
> >
> >Without this check, we will go ahead and start a new association and i think
> >that is definitely wrong. So i don't think it is a overhead. The only
> >issue is - what should be the return value.
> >
> >-Sridhar
> >
> >
> Absolutely!  The check is needed!
>
> Hmm... How hard IS it to figure out that the association was
> autoclosed?  What
> do you think of returning an error only if SCTP_AUTOCLOSE is not set?

Are you suggesting that when AUTOCLOSE is set, return 0 even if the the
association went away due to other reasons than autoclose, for ex: abort from
the peer or user initiated shutdown/abort. My opinion is that we should
return 0 only if we can detect that the association is true auto closed which
is not trivial.
Also i don't expect the user to do a manual shutdown when he has enabled
AUTOCLOSE.

Thanks
Sridhar

> >
> >
> >>Sridhar Samudrala wrote:
> >>
> >>
> >>>Considering the following respone from K.Poon on sctp-impl mailing list, i am
> >>>now inclined to return an error as suggested by the original patch from Jorge.
> >>>Also, draft 08 in Sec 3.1 indicates that applications using SCTP_AUTOCLOSE
> >>>option need to be aware of the possibility of an automatic closure of an
> >>>association.
> >>>
> >>>Thanks
> >>>Sridhar
> >>>
> >>>---------- Forwarded message ----------
> >>>Date: Fri, 21 May 2004 16:40:58 -0700
> >>>From: Kacheong Poon <kac...@su...>
> >>>To: sct...@ex...
> >>>Subject: Re: 1-many style sendmsg() with MSG_EOF and no assoc
> >>>
> >>>Sridhar Samudrala wrote:
> >>>
> >>>
> >>>
> >>>>This issue was recently raised on lksctp-developers mailing list.
> >>>>I would like to know how the other implementation of SCTP handle
> >>>>  sendmsg() with MSG_EOF flag and no data on a 1-many style socket when
> >>>>  no association is present.
> >>>>
> >>>>There are 2 cases here.
> >>>>1. The association is never created. This can be considered as a bug
> >>>>
> >>>>
> >>>in the
> >>>
> >>>
> >>>>   app.
> >>>>2. The association was created and auto-closed, but the app is not yet
> >>>>   aware of it.
> >>>>
> >>>>I think distinguishing the above 2 cases is not trivial as it needs
> >>>>maintaining additional state info about auto-closed assocs.
> >>>>
> >>>>
> >>>I think 1 is the right choice, return an error to the app
> >>>immediately.
> >>>
> >>>
> >>>