Hi All,

I managed to solve my need to re-write NOTIFY packets with help from this thread: https://www.mail-archive.com/sr-users@lists.kamailio.org/msg08088.html

This seems to work well. I am re-writing the packets as shown below… I guess my only question is, is this relatively safe/smart to do? I basically copied what our standalone Asterisk PBXes are doing in my captures, so I guess so? But I’m not confident enough to say it won’t cause some weird edge case issues. I can only say it works fine with the Snom and Yealink handsets I am testing with. I’m just concerned because it feels a bit like a hack.

For SUBSCRIBE I re-write:

* Request URI and To header from 101@ sent by the handset to tenant101@ (to match the SIP username of the handset - tenant101@)

For NOTIFY I re-write:

* From and Contact header to remove the tenant prefix, to go back to 101@ to match the BLF key configuration on the handsets.

Any advice would be appreciated on if this is a bad idea, and there’s a better way.

Thanks!

Rhys Hanrahan Chief Information Officer Nexus One Pty Ltd

E: support@nexusone.com.aumailto: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

From: sr-users sr-users-bounces@lists.kamailio.org on behalf of Rhys Hanrahan rhys@nexusone.com.au Reply-To: "Kamailio (SER) - Users Mailing List" sr-users@lists.kamailio.org Date: Tuesday, 26 March 2019 at 8:56 pm To: "sr-users@lists.kamailio.org" sr-users@lists.kamailio.org Subject: [SR-Users] Adding presentity_uri prefix for multi-tenanted presence/dialoginfo configuration

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_... + 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_... + msg_apply_changes(); + } +}

Thanks for your time.

Rhys Hanrahan Chief Information Officer Nexus One Pty Ltd

E: support@nexusone.com.aumailto: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

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