Re: [Lksctp-developers] Re: Different ways of getting assoc_id!

[Vlad Y. <vla...@hp...>]

On Tue, 2005-05-24 at 18:06 -0500, sur...@ou... wrote:
> Thanks for the details. Now I am getting the association id from the notification message by typecasting the buffer into sctp_assoc_change.
>  
> Is there any way I can get the ID from the "data" message being received?
> 
> Also, I can see two methods to retreive the association id,
> 1. From the sendrecv structure in the sctp_recvmsg. 
> 2. From typecasting the buffer of the sctp_recvmsg into "sctp_assoc_change" and getting the id.
> 
> Should these two values be the same?

sort of.  if you have more then one association, sctp_sndrcvinfo will
contain the association id for the association that received this
message.  It must however match one of the association ids you got from
sctp_assoc_change.

>  Becuase  I am always getting zero if I try the first one (sendrecv structure)

Did you enable SCTP_SNDRCV notification?
Are you providing the control buffer and is it large enough?

>  and some 9 digit number if i print it with %d for the second one(sctp_assoc_id). 

That would be the association id.  It's really an opaque type that just
happens to be a 32 bit integer on linux.  I'd recommend printing it with
%x.

-vlad

> 
> Thanks
> 
> ----- Original Message -----
> From: Vlad Yasevich <vla...@hp...>
> Date: Tuesday, May 24, 2005 8:38 am
> Subject: Re: [Lksctp-developers] Re: Different ways of getting assoc_id!
> 
> > No, you don't need to send the notification explicitly.  You also 
> > don'thave to use sctp_sendmsg().
> > 
> > The notifications are generated by the local system whenever an event
> > happens that an application may want to know about.  I recommend 
> > readinghttp://www.ietf.org/internet-drafts/draft-ietf-tsvwg-
> > sctpsocket-10.txt
> > 
> > 
> > -vlad
> > 
> > On Mon, 2005-05-23 at 18:52 -0500, sur...@ou... wrote:
> > > Do I need a corresponding sctp_sendmsg  for the sctp_recvmsg in 
> > another end? How do I send notification via  sctp_sendmsg, is that 
> > automatically sent if there is any change in the association or we 
> > need to manually send the notificatin via sctp_sendmsg. If I need 
> > to send manually, do I need to give id, stream number etc..?
> > > 
> > > I am just confused between the notification message and the data 
> > message! 
> > > 
> > > 
> > > Thanks
> > > Surendra
> > > ----- Original Message -----
> > > From: Sridhar Samudrala <sr...@us...>
> > > Date: Monday, May 23, 2005 1:14 pm
> > > Subject: Re: Different ways of getting assoc_id!
> > > 
> > > > sur...@ou... wrote:
> > > > 
> > > > >Hey all,
> > > > >      Wat are all the different ways of getting association 
> > id 
> > > > (assoc_id) after the association has been made? 
> > > > >
> > > > >I have set the socket options for SCTP_EVENTS and trying to 
> > get 
> > > > the socket id as follows,
> > > > >
> > > > >struct sctp_assoc_change *sac;
> > > > >sac = (struct sctp_assoc_change *)buf;  //here "buf" the 
> > buffer i 
> > > > am using it in recv (i have tried it with recvmsg also).
> > > > >sctp_assoc_t associoation_id = sac->sac_assoc_id;
> > > > >
> > > > >Is this correct? I am using SCTP_SEQPACKET (one to many style 
> > > > socket type).
> > > > >  
> > > > >
> > > > This will work only if you are sure that the received mesage 
> > is a 
> > > > notification, not data.
> > > > With recv()/recvfrom(), there is no way you can distinguish 
> > > > between 
> > > > notification or data.
> > > > You should either use recvmsg() or sctp_recvmsg() when you 
> > have 
> > > > enabled 
> > > > notifications.
> > > > You can find a no. of examples on how to use these API in 
> > lksctp-
> > > > tools 
> > > > package.
> > > > See under src/func_tests and src/apps.
> > > > - Sridhar
> > > > 
> > > 
> > > 
> > > 
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>