[SR-Users] call forking using dbaliases not working for un-NATed clients

[Klaus Darilion]

On 19.09.2012 12:24, Yufei Tao wrote:
> Hi Klaus
>
> Thanks for the reply!
>
> I check the $du, it is always null before and after the lookup. Is it
> only set when relaying to a proxy (from record-route), and not to a client?

That's strange. For NATed clients, $du must contain the 'received' URI. 
Otherwise they can not be contacted as $ru contains the private IP address.

> When no fix_nated_register is called, the lookup location for both
> clients y2 and y3 is successful from the log, when printing out $ru
> after lookup. But seems Kamailio only relays to one client's IP while
> not others. I think there must be some differences when branch route is
> executed first time and second time as you said. As it feels like for
> the first branch (trunk?) it used the 'contact' column from the location
> table, and for the other branches, it tries to use 'received'?

It seems db_lookup() creates multiple branches. Is lookup() only finding 
1 contact in table or multiple contacts?

regards
Klaus

>
>
> Yufei
>
> On 18/09/12 18:49, Klaus Darilion wrote:
>> I suspect that the branch route is first executed for the NATed
>> client. Then the 'received' column is used as destination URI. When
>> executing the branch route again, the destination URI is still the
>> value from the previous branch, and lookup() will not overwrite is as
>> 'received' is not available. Then Kamailio sends the INVITE again to
>> the first client.
>>
>> You can try to set $du to Null before lookup(). ($du=null or
>> $du=$null, not sure what the correct syntax is).
>>
>> Another workaround is to use fix_nated_register() for every client
>> (the pragmatic and more secure approach).
>>
>> regards
>> Klaus
>>
>> On 18.09.2012 15:16, Yufei Tao wrote:
>>> Hi
>>>
>>> I have a strange problem on forking calls to a group of users. For
>>> example I have two users y2 and y3 in dbaliases, both with
>>> alias_username 'group'. And y2 and y3 both registers with Kamailio fine.
>>> When I make a call to 'group' from a third client y1, what my
>>> kamailio.cfg does is: do an alias_db_lookup("dbaliases"), and goes to
>>> BRANCH_ALIASDB, where a lookup location will be done for each of the
>>> username resulting from lookup of dbaliases, something like this:
>>>
>>> y1--INVITE 'group'-->lookup dbaliase-->[BRANCH_ALIASDB]--->'y2'-->lookup
>>> location---¬
>>>
>>> |                                                 |-->relay
>>>
>>> ---->[BRANCH_ALIASDB]--->'y3'-->lookup
>>> location----
>>>
>>> The all works well as long as all clients are NAT'ed. However when they
>>> are not NAT'ed, e.g. all on the same LAN with Kamailio, the call only
>>> goes to one of the group members, e.g. y2 only. When checking the log,
>>> it seemed to have done the dbaliases lookup fine, and each location
>>> lookup successfully. But Kamailio only relayed y2's IP, e.g. to the
>>> client, while y3's to itself.
>>>
>>> When comparing the location table when clients are NAT'ed or not, I find
>>> that the 'received' column is only populated when I do
>>> fix_nated_register. And group calls only works when 'received' column is
>>> populated. That explains why when clients are NAT'ed group calls work,
>>> as I only do fix_nated_register if nat_uac_test returns true.
>>>
>>> But if this is the only reason, if two clients register using the same
>>> username, e.g. both as y3, and when 'received' column of location table
>>> is empty (no fix_nated_register done), I would expect a call to y3
>>> should also only make 1 client ring. But in fact both of them rang! The
>>> flow is like:
>>>
>>> y1--INVITE 'y3'-->lookup location for 'y3'----> IP of 1st client
>>> registered as 'y3'
>>>                                              |
>>>                                              ---> IP of 2nd client
>>> registered as 'y3'
>>>
>>> While a call to 'group' (thus dbaliases lookup took place) under such
>>> un-NAT'ed set up made only 1 client ring.
>>>
>>> So I can make it work by always doing fix_nated_register. But I'm not
>>> clear about these things:
>>> - why does a lookup of dbaliases before lookup of location make such
>>> difference?
>>> - does lookup location work differently depending on whether it is
>>> called from trunk or from a route called from a branch route?
>>>
>>>
>>> Following is relevant parts from my config file:
>>>
>>> #############################################################
>>> route[LOCATION]
>>> {
>>>      if ( alias_db_lookup("dbaliases") )
>>>      {
>>>        t_on_branch("BRANCH_ALIASDB"); # in branch_route[BRANCH_ALIASDB],
>>>                                       # call another route that looks up
>>> location,
>>>                                       # if not existent, call drop()
>>>
>>>      }
>>>      else
>>>      {
>>>        xlog("L_DBG","LOCATION: not alias - go to lookup location
>>> trunk\n");
>>>        route(LOCATION_TRUNK); # normal look up location and sending of
>>> 404 etc
>>>      }
>>>
>>> ... ...
>>> }
>>> #############################################################
>>> branch_route[BRANCH_ALIASDB]
>>> {
>>>      xlog("L_DBG", "BRANCH_ALIASDB: $fU@$fd ->  $rU@$rd; Method:$rm\n");
>>>      route(LOCATION_BRANCH);
>>> }
>>>
>>> route[LOCATION_BRANCH]
>>> {
>>>      if (!lookup("location"))
>>>      {
>>>        # Drop this branch - it's going nowhere
>>>        drop();
>>>      }
>>> }
>>> #############################################################
>>> route[RELAY] {
>>>      xlog("L_DBG","RELAY: method=$rm, callid=$ci, cseq=$cs\n");
>>>
>>>
>>> #!ifdef WITH_NAT
>>>      if (check_route_param("nat=yes")) {
>>>        setbflag(FLB_NATB);
>>>      }
>>>      if (isflagset(FLT_NATS) || isbflagset(FLB_NATB)) {
>>>        xlog("L_DBG", "RELAY: about to call RTPPROXY\n");
>>>        route(RTPPROXY);
>>>      }
>>> #!endif
>>>
>>>      /* example how to enable some additional event routes */
>>>      if (is_method("INVITE")) {
>>>        t_on_reply("REPLY_ONE");
>>>        t_on_failure("FAIL_ONE");
>>>      }
>>>
>>>      if (!t_relay()) {
>>>        sl_reply_error();
>>>      }
>>>
>>>      exit;
>>> }
>>>
>>> ############################################################
>>> route[NAT] {
>>> #!ifdef WITH_NAT
>>>     xlog("L_DBG","NAT: method=$rm, callid=$ci, cseq=$cs\n");
>>>
>>>       force_rport();
>>>       if (nat_uac_test("2")) {
>>>           if (method=="REGISTER") {
>>>               fix_nated_register();
>>>               xlog("L_DBG","NAT: Just done fix_nated_register in REGISTER
>>> message in NAT route\n");
>>>           } else {
>>>             xlog("L_DBG","NAT: fix_nated_contact\n");
>>>               fix_nated_contact();
>>>           }
>>>           setflag(FLT_NATS);
>>>       }
>>>
>>> #    setflag(FLT_NATS); ## -- YT: set NAT flag for all, so will force
>>> media relay
>>> #!endif
>>>       return;
>>> }
>>>
>>> #############################################################
>>> And in the main route, route LOCATION and RELAY are the last two routes:
>>> route {
>>> ...
>>>      route(NAT);
>>>
>>>      ... ...
>>>
>>>      # user location service
>>>      route(LOCATION);
>>>
>>>      route(RELAY);
>>> }
>>>
>>> Hope I have made it clear. Thanks very much!
>>>
>>> Yufei
>>> --
>>> Yufei Tao
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>
> --
> Yufei Tao
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