Hello,
actually you are wrong that you think it is a wrong to tag. The entity
that generates the final reply sets the to-tag (e.g.,to be able to match
ack). Even here where you talk about the serial forking, you are going
to face the case of different to-tag values for each branch sent out and
replied. But also think about parallel forking, that timed out with many
active branches, which to-tag to use?!?
So think that kamailio itself is the branch of the incoming request, and
can create many outgoing branches. If it generates a final reply, it
does it to the incoming branch. It is not forwarding (sending back) a
reply from an outgoing branch.
Obviously, being open source, one can code a specific behaviour for some
specific needs, but is not SIP specs compliant. If the upstream cannot
deal with different to-tags, it won't really work with serial/parallel
forking anyhow.
As a side remark, seeing the comments, if
route(ROUTE_ELEMENT_FINAL_FAILURE) is used only in failure_route, then
transaction is always defined there, because failure_route is executed
only in the transaction context. Anyhow, if you are using in many
places, not knowing if transaction was created, you can use send_reply()
to avoid any test in the config.
Cheers,
Daniel
On 11.12.20 11:04, Ivan Ribakov wrote:
Hi all,
I’m trying to implement following routing behaviour:
- ingress INVITE is sequentially forked to 1 or more endpoints
- under certain conditions sequential forking may be stopped and
pre-defined error returned to the caller
Here’s is part of the config responsible for handling errors:
failure_route[ROUTE_ELEMENT_FINAL_FAILURE_HELPER] {
route(ROUTE_ELEMENT_FINAL_FAILURE);
}
route[ROUTE_ELEMENT_FINAL_FAILURE] {
# We need to check if the error happens before the first egress,
because T-state is not defined yet so we can not use t_reply
if ($var(before_first_egress) == 0) {
t_reply("$var(sipCode)", "$var(sipMessage)");
} else {
sl_send_reply("$var(sipCode)", "$var(sipMessage)");
}
}
Here is a simple scenario where delivering call to first endpoint
times out after receiving 180 Ringing (using custom fr_inv_timer
value) where:
- .33 is caller
- .208 is Kamailio
- .138 is callee
Notice that 504 is retransmitted by Kamailio. Here is a comparison of
180 and 504 returned by Kamailio:
As can be seen, 180 was proxied from the callee and has callee’s
to-tag (tag=CALLEE1), however 504 that was generated by Kamailio using
t_reply() has a different to-tag (presumably generated by Kamailio).
How can I tell Kamailio not to generate new to-tag but to use the last
one that proxied back to the caller?
Thanks in advance for any help!
Regards,
Ivan
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