[OpenSIPS-Users] FW: CANCELs with no transaction
Dave Singer
dave.singer at wideideas.com
Wed Feb 16 09:18:58 CET 2011
Congrats Juri!
That's great! Your welcome and thanks for sharing the working solution/hack. :-)
Now if you can just get them to fix their software. At least you have
a workaround while they do.
Dave
On Tue, Feb 15, 2011 at 10:32 PM, Juri Nysschen <juri at greydotelecom.com> wrote:
> Hi Dave,
>
> It worked! The CDRs are perfect. Thanks for the help.
>
> Here's the code in case anyone else has the same issue:
>
> rout{
>
> ......
>
> # handle cancel and re-transmissions
> if (is_method("CANCEL") ) {
> xlog("L_INFO","CANCEL [$fd/$fu/$rd/$ru/$si/]\n");
> setflag(3); # start db accounting
> setflag(5); # log failed transactions
> route(5); # disconnect media proxy
> if (t_check_trans()){
> t_relay();
> exit;
> }
> xlog("L_INFO","CANCEL Generated [$fd/$fu/$rd/$ru/$si/]\n");
> # send a CANCEL downstream
> exec_msg("/usr/sbin/opensipsctl fifo t_uac_cancel $ci $cs");
>
> # send a ACK upstream for cdr purposes.
> sl_send_reply("200","OK");
> exit;
> }
>
> }
>
> Regards
> Juri Nysschen
> -----Original Message-----
> From: users-bounces at lists.opensips.org
> [mailto:users-bounces at lists.opensips.org] On Behalf Of Dave Singer
> Sent: Tuesday, February 15, 2011 8:28 PM
> To: OpenSIPS users mailling list
> Subject: Re: [OpenSIPS-Users] FW: CANCELs with no transaction
>
> Juri,
>
> You should be able to get to it with
> $(hdr(via){param.value,branch})
> But forcing it on the outbound cancel would probably be quite a trick
> since opensips wants to add It's via header automatically and that top
> via is what the next hop is counting on for matching the call.
> I think your best bet is to use the MI t_uac_cancel command as
> described last time. With it you don't have to same anything from the
> INVITE. You just use the callid and cseq from the CANCEL to pass to
> the MI command t_uac_cancel.
> Be aware you may have linux and selinux permissions conflicts for
> executing opensipsctl from inside opensips. I posted in a thread a
> thing about dealing with selinux in the last couple months that makes
> it quite easy if selinux is a problem and to see if it is the problem.
> Your command would be something like:
> exec("/usr/local/opensips/sbin/opensipsctl fifo t_uac_cancel $ci $cs");
> Don't forget to make sure the source canceling the call gets the
> response they are looking for so they don't keep sending you cancels
> and you keep doing the exec over and over.
>
> Dave
>
> On Tue, Feb 15, 2011 at 5:52 AM, Juri Nysschen <juri at greydotelecom.com>
> wrote:
>> Hi Dave
>>
>> I have used wireshark to review the cancel message on a call timeout
> (which
>> works) and when received from the UA.
>>
>> The difference is in the branch= value as you predicted.
>>
>> How can I save the branch value on the INVITE and then change it on the
>> CANCEL?
>> I've tried all sorts of combinations for $branch but the vales are always
>> NULL
>>
>>
>> Regards
>> Juri Nysschen
>>
>> -----Original Message-----
>> From: users-bounces at lists.opensips.org
>> [mailto:users-bounces at lists.opensips.org] On Behalf Of Dave Singer
>> Sent: Monday, February 14, 2011 10:16 PM
>> To: OpenSIPS users mailling list
>> Subject: Re: [OpenSIPS-Users] FW: CANCELs with no transaction
>>
>> Juri,
>>
>> This was gnawing at me so I searched and found the "official" answer
>> of what a CANCEL should look like.
>> Go to
>> http://www.ietf.org/rfc/rfc3261.txt
>> and search for "9 Canceling a Request"
>> From what I read it basically says that the CANCEL should be nearly
>> identical to the INVITE it is canceling (without some headers that
>> aren't useful in a cancel like Supported)
>> It seems that the "branch=...." , a "Magic Cookie", on the top most
>> via line is a turbo lookup to finding the transaction. That matches
>> the original INVITE and all is well. If it is not there then it has to
>> compare all the pertinent headers between invite and cancel.
>>
>> So if you can't get them to send the proper stuff, you could modify
>> the previous hack to store the branch=... that opensips put in the via
>> header it added (probably can't see it when sending the invite but it
>> is in the 1xx response to your invite.
>> Actually I just found one better I think. Use the exec module to
>> execute MI command t_uac_cancel
>> (http://www.opensips.org/html/docs/modules/1.6.x/tm.html#id294623)
>> All it needs are callid and cseq num, which I hope at least they are
>> the same as the INVITE, which you can use the CANCEL's parsed vars for
>> the params. I you will probably need to send back a negative response
>> to the bad CANCEL like 400 Bad Message (look up appropriate
>> code/message). And I think the t_uac_cancel will also push into
>> failure_route a 487 response, which if you don't choose anything else
>> specifically, will be sent back to the originator.
>> You will want to verify it with packet captures and see how it affects
>> your cdrs.
>>
>> Let me know the outcome.
>>
>> Dave
>>
>> On Mon, Feb 14, 2011 at 11:05 AM, Dave Singer <dave.singer at wideideas.com>
>> wrote:
>>> I was half expecting that kind of result.
>>> I don't know what exactly opensips uses to match transactions. I
>>> believe Call-id and CSeq headers being the same but I'm quite sure
>>> there is more like maybe from tag? I don't know.
>>>
>>> Can anyone else chime in on what opensips is checking to match a
>> transaction.
>>>
>>> Dave.
>>>
>>> On Sun, Feb 13, 2011 at 11:36 PM, Juri Nysschen <juri at greydotelecom.com>
>> wrote:
>>>> Hi Dave,
>>>>
>>>> Thanks this method is very successful in delivering the CANCEL
>> downstream,
>>>> over multiple hops, unfortunately the PSTN also doesn't see the
>> transaction
>>>> id and therefore the call keeps ringing.
>>>> The key is finding the reason why the transaction id disappears or at
>> least
>>>> be able to put it back when delivering the CANCEL downstream.
>>>>
>>>> Regards
>>>> Juri Nysschen
>>>>
>>>> -----Original Message-----
>>>> From: users-bounces at lists.opensips.org
>>>> [mailto:users-bounces at lists.opensips.org] On Behalf Of Dave Singer
>>>> Sent: Monday, February 14, 2011 9:03 AM
>>>> To: tyler at fonality.com; OpenSIPS users mailling list
>>>> Subject: Re: [OpenSIPS-Users] FW: CANCELs with no transaction
>>>>
>>>> Juri,
>>>>
>>>> You say it only happens after a do_routing(). To be clear, you mean
>>>> that you used do_routing on the invite and not that you already tried
>>>> do_routing for the cancel earlier in the script. (I'm not sure it
>>>> would make any difference)
>>>>
>>>> The hack to store the destination in a variable is one you would want
>>>> to strongly avoid. But sometimes hacks are unavoidable and a stop gap
>>>> until you can really resolve the problem.
>>>> I believe $avp's are retained per transaction and if the
>>>> t_check_trans() fails then the $avp created in the reply would also
>>>> not be available.
>>>> $var also would not work most of the time since it is persistent per
>>>> process. You would need to use core functions cache_store and
>>>> cache_fetch using either local_cache or memcached backend depending if
>>>> you need persistant between opensips reboot.
>>>> Example:
>>>>
>>>> route{
>>>>
>>>> .....
>>>>
>>>> if (is_method("CANCEL") ) {
>>>>
>>>> route(5); # drop media proxy
>>>>
>>>> if (t_check_trans()){ # this always fails after a
> do_routing()
>>>>
>>>> xlog("L_INFO","CANCEL
>>>> Transaction[$fd/$fu/$rd/$ru/$si/]\n");
>>>>
>>>> t_relay();
>>>>
>>>> exit;
>>>>
>>>> } else {
>>>>
>>>> if ( cache_fetch("local", "tran_dest_$ci",
>>>> "$avp(s:next_hop)") ) {
>>>> $rd = $avp(s:next_hop);
>>>> t_relay();
>>>> }
>>>> exit;
>>>>
>>>> }
>>>>
>>>> }
>>>>
>>>>
>>>> on_reply[main] {
>>>> cache_store("local", "tran_dest_$ci", "$si", 500);
>>>> }
>>>>
>>>> Dave
>>>>
>>>> On Sun, Feb 13, 2011 at 5:15 AM, Tyler Merritt <tyler at fonality.com>
>> wrote:
>>>>>
>>>>> Why not use an $avp and grab the Call ID header on the inbound packet
>> and
>>>> then create some routing logic that checks the $avp against the return
>>>> packet Call ID header to validate it's the same thing? $avps can be
> made
>>>> available onreply with a modparam though forgive me if it's a bit late
> at
>>>> night and I don't have the link handy.
>>>>> An avp can store more than a single value but they index in reverse
>> order
>>>> as written if I recall correctly.
>>>>>
>>>>> On Sat, Feb 12, 2011 at 5:05 AM, Russell Bierschbach
>>>> <rbierschbach at telepointglobal.com> wrote:
>>>>>>
>>>>>> I have a similar problem, but not solution, my probably is actually
>>>> occurring because the originating UA is ignoring a contact header that
> is
>>>> sent back during a 183 progress message. OpenSIPS uses information from
>>>> that contact header to figure out where to relay the incoming message
>> (BYE
>>>> in my case, CANCEL in yours). It seems like it would be possible for
>>>> OpenSIPS to use a call-id or tag to determine where to relay the message
>>>> though.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Russell Bierschbach
>>>>>>
>>>>>> em: rbierschbach at telepointglobal.com, im: rbierschbach at hotmail.com
>>>>>>
>>>>>>
>>>>>>
>>>>>> From: users-bounces at lists.opensips.org
>>>> [mailto:users-bounces at lists.opensips.org] On Behalf Of Juri Nysschen
>>>>>> Sent: Friday, February 11, 2011 7:44 AM
>>>>>> To: users at lists.opensips.org
>>>>>> Subject: [OpenSIPS-Users] FW: CANCELs with no transaction
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi All,
>>>>>>
>>>>>>
>>>>>>
>>>>>> Need help with a nagging issue:
>>>>>>
>>>>>>
>>>>>>
>>>>>> UA->Opensips 1->Opensips 2->PSTN
>>>>>>
>>>>>>
>>>>>>
>>>>>> UA sends an invite on Opensips 1, and is routed via do_routing() to
>>>> Opensips 2, Opensips 2 uses do_routing to get to the PSTN, call starts
>>>> ringing.
>>>>>>
>>>>>>
>>>>>>
>>>>>> UA cancels call before answer, but now t_check_trans fails and the
>> CANCEL
>>>> is not passed onto the PSTN, with the result that the call rings forever
>> and
>>>> can only be terminated by the remote answering and dropping the call or
>>>> through a timeout.
>>>>>>
>>>>>>
>>>>>>
>>>>>> The scripts on Opensips 1 & Opensips 2 is virtuall identical:
>>>>>>
>>>>>>
>>>>>>
>>>>>> How do I get the CANCEL to the PSTN ?
>>>>>>
>>>>>>
>>>>>>
>>>>>> route{
>>>>>>
>>>>>> .....
>>>>>>
>>>>>> if (is_method("CANCEL") ) {
>>>>>>
>>>>>> route(5); # drop media proxy
>>>>>>
>>>>>> if (t_check_trans()){ # this always fails after a
>>>> do_routing()
>>>>>>
>>>>>> xlog("L_INFO","CANCEL
>>>> Transaction[$fd/$fu/$rd/$ru/$si/]\n");
>>>>>>
>>>>>> t_relay();
>>>>>>
>>>>>> exit;
>>>>>>
>>>>>> };
>>>>>>
>>>>>> exit;
>>>>>>
>>>>>> }
>>>>>>
>>>>>> }
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> route[4] {
>>>>>>
>>>>>> xlog("L_INFO","Route4 [$fd/$fu/$rd/$ru/$si/]\n");
>>>>>>
>>>>>>
>>>>>>
>>>>>> $avp(i:102)=1; # Default dr-group
>>>>>>
>>>>>> route(10); # Do custom stuff
>>>>>>
>>>>>> t_on_failure("4");
>>>>>>
>>>>>> if (do_routing("$avp(i:102)")){
>>>>>>
>>>>>> xlog("L_INFO","Route4 Route to Dyna Group:
>>>> $avp(i:102)[$fd/$fu/$rd/$ru/$si/]\n");
>>>>>>
>>>>>> t_newtran();
>>>>>>
>>>>>> route(1);
>>>>>>
>>>>>> exit;
>>>>>>
>>>>>> };
>>>>>>
>>>>>> xlog("L_INFO","Route4 No Route to
> Host[$fd/$fu/$rd/$ru/$si/]\n");
>>>>>>
>>>>>> sl_reply_error();
>>>>>>
>>>>>> exit;
>>>>>>
>>>>>> }
>>>>>>
>>>>>>
>>>>>>
>>>>>> Regards
>>>>>>
>>>>>> Juri Nysschen
>>>>>>
>>>>>>
>>>>>>
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>>>>>> Users mailing list
>>>>>> Users at lists.opensips.org
>>>>>> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
>>>>>>
>>>>>
>>>>>
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>>>>>
>>>>
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