Hi Everyone,
I’ve recently just started working with Kamailio – thanks everyone for this amazing software.
Like many people, I’m in the process of trying to put Kamailio in-front of Asterisk to allow it to scale out, and my plan is for Kamailio to take over registrations, usrloc and presence/dialoginfo,
as we’ve had issues where handsets are failing to get BLF updates/notifys, so I am hoping a couple of Kamailio boxes can scale better in this regard. DMQ is particularly exciting in how it will allow me to build a truly distributed platform. But I’m struggling
to get presence to work the way I need it to.
Our environment is multi-tenanted, but we do not (and can’t really) use multi-domains. Instead, we prefix the SIP usernames with the “tenant name” such as tenanta101 and tenantb101. My problem
is that all the BLFs are configured for 101@PBX with no tenant name in the User part of the URI so that internal dialing and call pickup will work. Because in Asterisk we use “subscribecontext” this hasn’t been a problem in the past – Asterisk knows for subscriptions
coming from that handset that it belongs to that tenant’s context in the dialplan and they are “isolated”, so having handsets subscribe as 101@ in their request URI was never a problem. Of course, with Kamailio I don’t have subscribecontext, and my main issue
is that the “presentity_uri” being stored is 101@ while each of the SIP accounts of the handsets are registered as tenenata101@, and as such, no NOTIFYs are sent by Kamailio because it thinks that there are no watchers for the presentity_uri.
If I change the SIP account username to 101 to match the BLF key, NOTIFYs are sent as expected. But then this breaks call pickup and internal dialing using the BLF keys. I would rather handle
this in Kamailio than in Asterisk and having to re-configure the BLF keys for hundreds of handsets.
I need to do something like:
- When a SUBSCRIBE comes in, I need to prefix presentity_uri with the tenant name so the subscription changes from 101@ to tenanta101@ in
the active_watchers table.
- When Kamailio generates a NOTIFY, the notify would be built based on presentity_uri and would come out as tenanta101@, but the phone’s BLFs
are configured for 101@ so I would need to *remove* the tenant prefix before sending out the notify.
Is there a good, or recommended way to handle this scenario? Maybe something entirely different to changing the presentity_uri?
I’ve written the following config to re-write the request URI and To field in any incoming subscribe requests, and successfully got the active_watchers table to store a presentity_uri containing
my tenant prefix. But the problem I am having is that I can’t figure out how to modify the NOTIFY packets before they are sent – and looking at cfgtrace, it seems I might not be able to?
My “standard” presence + dialoginfo configuration was taken from here as a starting point:
https://kb.asipto.com/kamailio:presence:k43-blf
Here is what I have so far in terms of trying to make my modifications – any guidance would be greatly appreciated. It feels like there’s probably a better way to do this than re-writing critical
headers like To and Request URI?
@@ -466,6 +467,8 @@ request_route {
# authentication
route(AUTH);
+ route(REWRITE_PRESENCE);
+
# record routing for dialog forming requests (in case they are routed)
# - remove preloaded route headers
remove_hf("Route");
# Presence server processing
route[PRESENCE] {
if(!is_method("PUBLISH|SUBSCRIBE")) return;
if(is_method("SUBSCRIBE") && $hdr(Event)=="message-summary") {
# Asterisk is our voicemail
route(TOASTERISK);
# returns here if no voicemail server is configured
sl_send_reply("404", "No voicemail service");
exit;
}
#!ifdef WITH_PRESENCE
if (!t_newtran()) {
sl_reply_error();
exit;
}
if(is_method("PUBLISH")) {
handle_publish();
t_release();
} else if(is_method("SUBSCRIBE")) {
# See REWRITE_PRESENCE - this should have been executed before we get here.
handle_subscribe();
t_release();
}
exit;
#!endif
+route[REWRITE_PRESENCE] {
+ if (is_method("SUBSCRIBE")) {
+ xlog("Re-writing subscribe to include tenant prefix\n");
+ # The default presentity_uri needs to be prefixed with
+ # the tenant name
+ # So re-write the To header
+ route(TENANTINFO);
+ # Now grab the tenant name.
+ $var(subscribe_ru) = "sip:" + $var(tenant_name) + $rU + "@" + $rd;
+ xlog("Re-writing SUBSCRIBE To header as: $var(subscribe_ru)\n");
+ insert_hf("To: $var(subscribe_ru)\r\n", "From");
+ $ru = $var(subscribe_ru);
+ # Force change immediately:
+ # http://www.kamailio.org/wiki/tutorials/faq/main#why_changes_made_to_headers_or
+ msg_apply_changes();
+ } else if (is_method("NOTIFY")) {
+ xlog("Re-writing NOTIFY to remove tenant prefix\n"); # This code block does not get executed right now.
+ # We are storing the presentity_uri with a tenant prefix
+ # handsets do not expect this, only 101@, 102@ etc... In their BLF configs
+ # So this tenant prefix must be removed when building the reply.
+ route(TENANTINFO);
+ $var(notify_ru) = "sip:" + $(rU{s.substr,$(var(tenant_name){s.len}),0}) + "@" + $rd;
+ xlog("Re-writng NOTIFY to use: $var(notify_ru)\n");
+ insert_hf("To: $var(notify_ru)\r\n", "From");
+ $ru = $var(notify_ru);
+ # Force change immediately:
+ # http://www.kamailio.org/wiki/tutorials/faq/main#why_changes_made_to_headers_or
+ msg_apply_changes();
+ }
+}
Thanks for your time.
Rhys Hanrahan
Chief Information Officer
Nexus One Pty Ltd
E: support@nexusone.com.au
P: +61 2 9191 0606
W: http://www.nexusone.com.au/
M: PO Box 127, Royal Exchange NSW 1225
A: Level 12 227 Elizabeth St, Sydney NSW 2000
