9 Jun
2011
9 Jun
'11
10:18 a.m.
Hi Daniel,
I was thinking of adding a modparam to pua to simply not compare the remote_contact when
checking for SUBSCRIBE dialogs. When not set the current pua behaviour will remain.
The RLS back-end dialogs should be unique across pres_uri and pres_id. The current check
is on pres_uri, pres_id, watcher_uri, and remote_contact. So, I don't think
remote_contact really needs to be checked here at all.
This change shouldn't cause problems with anything else that uses pua because the same
check should be OK for them too (they may even suffer from the same problem). However,
putting in the modparam so the old behaviour is still used by default seems safer for
now.
Perer
On 9 Jun 2011, at 07:33, Daniel-Constantin Mierla <miconda(a)gmail.com> wrote:
Hello,
On 6/8/11 3:48 PM, Peter Dunkley wrote:
Hello,
I am working with Kamailio RLS which uses PUA as a library to send SUBSCRIBEs.
Whenever Kamailio receives an RLS subscription it calls rls_handle_subscribe().
rls_handle_subscribe() calls the function resource_subscriptions() which in turn calls
send_resource_subs() (via process_list_and_exec()). resource_subscriptions() and
send_resource_subs() fill in a subs_info_t structure that is passed into the PUA module
send_subscribe() function.
The key part is that send_resource_subs() sets the subs_info_t remote_target field to the
pres_uri. The PUA send_subscribe() function uses the remote_target as the remote_contact
(in the ua_pres_t structure) that is used to lookup the dialog in the PUA hash table.
Unfortunately, this lookup always fails because the PUA module correctly updates the
remote contact in the hash table when it gets a response back from the (Kamailio) presence
server.
The effect that this has is that any re-SUBSCRIBE requests from the RLS module are
treated as new initial SUBSCRIBEs. This causes the pua and (presence) watchers tables in
my Kamailio database to grow rapidly, and can result in multiple notifications on a
presence status change.
I noticed this because I am currently adding a new API to RLS which will allow me to
update my RLS subscriptions whenever my resource list documents change. This is needed so
that subscribers receive an immediate presence authorisation request when someone adds
them to their contact list. The client I am testing with tends to update the RLS
documents frequently (often for superficial changes) and this combined with the PUA issue
described above means with just two clients on the system (with only each other in the
contact list) I can end up with many 10s of records in pua and watchers within a few
minutes.
This issue will also have a lesser effect when RLS re-SUBSCRIBEs from clients occur.
There will be a window (until the original SUBSCRIBE expires) when there are multiple
back-end SUBSCRIBE dialogs for each contact.
Can anyone advise on this issue and suggest a solution?
had no time to look into
the code, you should have it fresh in mind -- is any other unique key that could be used
to match the dialog in pua hash table? If not, then maybe adding a new field to keep the
initial remote_contact is a solution, so if matching on remote contact does not return,
lookup again on initial field.
Cheers,
Daniel
Regards,
Peter
--
Peter Dunkley
Technical Director
Crocodile RCS Ltd
_______________________________________________
sr-dev mailing list
sr-dev(a)lists.sip-router.org
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
--
Daniel-Constantin Mierla -- http://www.asipto.com
http://linkedin.com/in/miconda -- http://twitter.com/miconda