[SR-Users] Re: from TCP to UDP and Kamailio doing it wrong

Hello, this sound indeed strange, as this is used from many people without any problems. Its not expected to use C programming to alter the message transport for relaying. If you can reproduce and minimize the problem towards a small test cfg and a test message, it would be great if you could open an issue in our tracker. Cheers, Henning > -----Original Message----- > From: Alberto Diez via sr-users &lt;sr-users(a)lists.kamailio.org&gt; > Sent: Freitag, 8. März 2024 10:28 > To: sr-users(a)lists.kamailio.org > Cc: Alberto Diez &lt;alberto-lists(a)mobileplots.com&gt; > Subject: [SR-Users] Re: from TCP to UDP and Kamailio doing it wrong > > thanks Alex. Sadly in my case the Request-URI does not contain a transport > parameter. > > So the call to prepare_new_uac() function is deciding based on another > parameter (don't know which, was trying to avoid investigating that because > the function is a pain and not commented). I think its quite counter-intuitive, > and for me a bug, that you call t_relay_to_udp and Kamailio tries to connect > over TCP....  Same if its dispatcher module asking to dispatch to UDP and > t_relay decides TCP (because it calls this same function at the end) etc. > > By the way I also tried forcing the socket from the config file to be the UDP > one, and nothing. Prior to calling prepare_new_uac the socket is the UDP one, > but after calling that function it has changed the socket to a TCP one. > > Would be great if anyone has a hint what could be going on and why > prepare_new_uac changes the socket and based on what param > > Best regards > > alberto > > El 07/03/2024 a las 21:44, Alex Balashov via sr-users escribió: >> If you just strip the incoming ;transport=tcp attribute, I think all should be > well when t_relay() consumes the modified RURI. >>> On 7 Mar 2024, at 12:48, Alberto Diez via sr-users <sr- > users(a)lists.kamailio.org&gt; wrote: >>> Hi Sergiu, >>> yes I am pretty sure something is going wrong. >>> I do have kamailio listening udp sockets and also the dispatcher is on UDP > doing SIP OPTIONS over UDP all the time without any problem. >>> I have not tried forcing the socket I tried to find out why kamailio is trying to > use TCP with the targets even when I use t_relay_to_udp and that's how I > ended up finding that function which claims not to do something if next_hop > is 0 but doing it nevertheless (which I guess is something going wrong in > general in Kamailio not in particular in my setup). >>> I will try forcing the socket, but that crazy tm module function >>> rewrites the socket was already given as a destination (yes I already >>> checked that in the C code before!) Best regards alberto El >>> 07/03/2024 a las 17:43, Sergiu Pojoga escribió: >>>> You must be doing something essentially wrong if it came down to > checking C functions for something as trivial as transport conversion.. >>>> Are you sure you have a UDP listening socket? >>>> kamcmd corex.list_sockets >>>> >>>> Result of: >>>> kamcmd dispatcher.list >>>> >>>> Have you tried forcing the send socket? >>>> https://www.kamailio.org/wiki/cookbooks/devel/pseudovariables#fs_-_f >>>> orced_send_socket >>>> >>>> Cheers >>>> >>>> On Thu, Mar 7, 2024 at 11:27 AM Alberto Diez via sr-users <sr- > users(a)lists.kamailio.org&gt; wrote: >>>> Hi kamailio community, >>>> >>>> I have an issue with a Kamailio 5.7. It's listening both in TCP and >>>> UDP. In my scenario requests arrive from devices on TCP, but I want >>>> to forward to the next hops on UDP. I am avoiding using any type of >>>> DNS resolution; since I am always forwarding to predefined next hops >>>> I am using the dispatcher module (defined with the IP addresses and >>>> transport=udp) or I wrote config files using t_relay_to_udp or >>>> t_relay_to with a udp: followed by IP address. I never set up FQDNS >>>> only IP addresses and in all of them I explicitly mention UDP. >>>> >>>> In all of these scenarios I have tried Kamailio insists in trying to >>>> use TCP with the next hop and failing because the next_hop is only >>>> UDP. I guess because the message arrived using TCP Kamilio does that >>>> but I find the behavior very confusing. >>>> >>>> I nailed down that in my situation its the tm module function >>>> prepare_new_uac (in file src/modules/tm/t_fwd.c line 119) being the >>>> one that missbehaves. The documentation of the function says literraly : >>>> >>>> "* t->uac[branch].request.dst will be filled if next_hop !=0 with the result >>>> * of the DNS resolution (next_hop, fproto and fsocket). >>>> * If next_hop is 0 all the dst members except the send_flags are read- > only >>>> * (send_flags it's updated) and are supposed to be pre-filled." >>>> >>>> I found out that even when next_hop is 0 the function changes the >>>> t->uac[branch].request.dst proto, socket etc. its there that the >>>> kamailio takes the wrong decision, until that function is called >>>> within add_auc, the destination proto or the fproto etc is always 1 >>>> (UDP) which is what I am trying to force from the config file or the >>>> dispatcher definition (I tried both ways). But after calling that >>>> function then it comes as a 2 (TCP) >>>> >>>> The problematic function is a monster of 500 lines and I would like >>>> to avoid having to understand it. Since I think the scenario is not >>>> so unusual I just want to ask if maybe I am missing something that I >>>> should do to avoid the Kamailio to select TCP and in order to have >>>> the tm module respecting my preference for UDP (either with >>>> dispatcher module and the transport param or with t_relay_to or >>>> t_relay_to_udp I don't care the way). >>>> >>>> Any hints are welcome. >>>> >>>> Best regards >>>> >>>> alberto >>>> >>>> __________________________________________________________ >>>> Kamailio - Users Mailing List - Non Commercial Discussions To >>>> unsubscribe send an email to sr-users-leave(a)lists.kamailio.org >>>> Important: keep the mailing list in the recipients, do not reply only to the > sender! >>>> Edit mailing list options or unsubscribe: >>> __________________________________________________________ >>> Kamailio - Users Mailing List - Non Commercial Discussions To >>> unsubscribe send an email to sr-users-leave(a)lists.kamailio.org >>> Important: keep the mailing list in the recipients, do not reply only to the > sender! >>> Edit mailing list options or unsubscribe: > __________________________________________________________ > Kamailio - Users Mailing List - Non Commercial Discussions To unsubscribe > send an email to sr-users-leave(a)lists.kamailio.org > Important: keep the mailing list in the recipients, do not reply only to the > sender! > Edit mailing list options or unsubscribe: