[SR-Users] Multiple parallel branches, one invalid

[Anthony Joseph Messina]

On Thursday, March 9, 2017 8:16:55 PM CST Nathan Ward wrote:
> I have a scenario I’m not sure of the best way to solve.
> 
> I use alias_db and have multiple destinations for a single number, and have
> append_branches set to 1. I then use lookup_branches to get details from
> the location table for each branch. I then do t_load_contacts and
> t_next_contacts, then t_relay to parallel fork the calls to the
> destination, and all the phones ring at once.
> 
> This all works great if all the destinations from the dbaliases table are
> online.
> 
> However, if one of them is offline, lookup_branches says "Not found in
> usrloc”. This branch is still there, and the call is attempted. In my
> environment, this then does a DNS lookup, can’t resolve the domain, and the
> branch fails. This is the first branch that is tried, and when this branch
> has an error like this, it causes t_relay() to fail - I check for the
> output of t_relay() and reply with an error - per the default config that
> Kamailio ships with.
> 
> I guess what I need to figure out, is if there’s a way to have t_relay fail
> only if all branches fail? Or, is there a more elegant way to handle this?
> 
> I should add, I only allow a single registration per subscriber - so,
> lookup_branches only returns one branch per alias from alias_db_lookup.

I'm not sure if this will work for you, but I have a similar situation where I 
lookup_branches after alias_db_lookup.  Just like you, if at least one of the 
branches is found by lookup_branches, then the call works ok.  If none of the 
branches are found, then things don't work.  If I understand you correctly, 
you need to check if lookup_branches fails (no branches are found) and handle 
the call differently before any call to t_relay.

For me, I do a quick check of the branch count and decide what to do from 
there, i.e., multibranch calls get handled differently and in my case will 
route to voicemail using $avp(oexten) if none of the users are online.


route[LOCATION] {
    # Save the original extension
    $avp(oexten)=$rU;

#!ifdef WITH_ALIASDB
    if(alias_db_lookup("dbaliases")) {
            # Only route a single branch via SIPOUT
            if($branch(count)==0) {
                    route(SIPOUT);
            }
    }
#!endif


    if(!lookup_branches("location")) {
        # Save the return code from the lookup_branches function
        $var(rc_lookup_branches)=$rc;

        # Asterisk failover route (for non-multibranch INVITEs)
        if($branch(count)==0) {
                route(ASTERISK);
        }

        # Route to VoiceMail (Leave VoiceMail)
        route(VOICEMAIL);
        t_newtran();
        switch($var(rc_lookup_branches)) {
                case -1:
                case -3:
                        send_reply("404", "Not Found");
                        exit;
                case -2:
                        send_reply("405", "Method Not Allowed");
                        exit;
        }
    }

    ...  other stuff ...
    ... eventually: t_relay();
}



-- 
Anthony - https://messinet.com/ - https://messinet.com/~amessina/gallery
F9B6 560E 68EA 037D 8C3D  D1C9 FF31 3BDB D9D8 99B6
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.sip-router.org/pipermail/sr-users/attachments/20170310/aa6cbc99/attachment.sig>