12 Jan
2024
12 Jan
'24
3:44 p.m.
Hi Nicolas,
Yes, I think that unfortunately this is the outcome of some confusion. Apart from the word
"append", there is nothing in common between the concepts of append_branch() and
append_to_reply().
I'm not sure why you are getting the messages you are just sending redirects, but the
prime suspicion is that the execution of your configuration contains additional steps
beyond just sending stateless replies, e.g. that you call sl_send_reply(), but do not call
'exit' afterward, and so the config execution progresses to a step where some kind
of relay is attempted.
Conceptually, sending redirects is as simple as:
request_route {
...
# Maybe some sanity-checking or request boilerplate here.
if(method == "INVITE") {
# some DB ops or whatever, yielding $var(val).
append_to_reply("Contact: <sip:$var(val)>\r\n");
sl_send_reply("302", "Moved Temporarily");
exit;
}
# Anything else that might occur in this config should not
# occur if an INVITE was received--note the 'exit' step above.
}
It may not be quite as simple as that, but hopefully this gives the right idea.
-- Alex
On 12 Jan 2024, at 03:16, Chaigneau, Nicolas
<nicolas.chaigneau(a)capgemini.com> wrote:
Hello Alex,
The confusion is probably on my part.
Reading this:
https://kamailio.org/docs/modules/devel/modules/sl.html#sl.f.sl_send_reply
3.1. sl_send_reply(code, reason)
For the current request, a reply is sent back having the given code and text reason. The
reply is sent stateless, totally independent of the Transaction module and with no
retransmission for the INVITE's replies.
If the code is in the range 300-399 (redirect reply), the current destination set is
appended to the reply as Contact headers. The destination set contains the request URI
(R-URI), if it is modified compared to the received one, plus the branches added to the
request (e.g., after an append_branch() or lookup("location")). If the R-URI was
changed but it is not desired to be part of the destination set, it can be reverted using
the function revert_uri().
Custom headers to the reply can be added using append_to_reply() function from textops
module.
I thought that I needed to use append_branch before calling sl_send_reply to control the
Contact headers in the reply.
I tried to use "append_to_reply" instead to add the Contact headers, like
this:
append_to_reply("Contact: <...>\r\n");
This works, but then I get WARNING messages in the logs:
WARNING: <core> [core/dset.c:690]: print_dset(): no r-uri or branches
Which is also why I was confused...
You're telling me I should not create branches... but if I don't, I get these
messages.
Could you please clarify ?
Thanks a lot.
Regards,
Nicolas.
-----Message d'origine-----
De : Alex Balashov via sr-users <sr-users(a)lists.kamailio.org>
Envoyé : jeudi 11 janvier 2024 18:57
À : Kamailio (SER) - Users Mailing List
Cc : Alex Balashov
Objet : [SR-Users] Re: Using http_async_query - transaction seems "reused" for
subsequent SIP INVITE requests received ? (Kamailio 5.7.3)
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Hi,
First off, a bit confused as to why you are appending a branch and then sending a final
reply? Adding a branch only makes sense if you plan to fork the request to an additional
destination, instead of responding to the sender with a final dispositive (>= 3xx)
reply.
-- Alex
--
Alex Balashov
Principal Consultant
Evariste Systems LLC
Web: https://evaristesys.com
Tel: +1-706-510-6800
On 11 Jan 2024, at 12:16, Chaigneau, Nicolas via
sr-users <sr-users(a)lists.kamailio.org> wrote:
Hello,
So far I was using Kamailio in "stateless" mode to handle SIP INVITE requests
and reply with 302.
I am now trying to use module http_async_client module, but I'm experiencing
unexpected behavior with "branches".
I'm using function http_async_query as described in the example:
https://www.kamailio.org/docs/modules/devel/modules/http_async_client.
html#http_async_client.f.http_async_query
When the transaction is resumed, I'm building and sending the reply, using
"append_branch" and "sl_send_reply":
https://kamailio.org/docs/modules/devel/modules/sl.html#sl.f.sl_send_r
eply
For example:
append_branch("...");
sl_send_reply("302", "Moved Temporarily");
This works, however when I'm sending new client SIP INVITE requests to Kamailio, it
seems it will always reuse the previous transaction.
The new branches are appended to the branches of the first transaction.
I end up with errors "ERROR: <core> [core/dset.c:424]: append_branch(): max nr
of branches exceeded" when the limit (12) is exceeded.
I do not understand why this happens. This is a new SIP INVITE message, it should not be
linked to the previous transaction ?
I tried a few things:
- remove the transaction using "t_release();"
- configure: modparam("tm", "wt_timer", 0) This did not help...
How can I solve this ?
Thanks for your help.
Regards,
Nicolas.
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