[SR-Users] Any substitute or replace function for the request-/response line of SIP messages available?

[Alex Balashov]

At the risk of sounding unhelpful, if you are having to modify the
request/status line, there's probably something more deeply wrong here,
and you should probably endeavour to fix the problem in a somewhat more
realistic manner.

Furthermore, it must be said that proxies do not make a particularly
good "protocol adaptor";  in contrast to "thicker" back-to-back user
agents (B2BUAs), which build out two logically independent call legs and
bridge signaling events between them selectively, as they see fit,
proxies are more or less obligated, in principle, to pass on what they
receive, in unadulterated form.  Kamailio does offer some hacks around
that, in the form of textops and so on, but it doesn't really mean that
it is the right tool for the job.

That said, if you are dead-set on doing this, your best for regenerating 
a reply into a request is the 'uac' module and uac_req_send() functionality:

http://kamailio.org/docs/modules/3.3.x/modules_k/uac.html#id2494432

-- Alex

On 02/15/2013 03:22 PM, Klaus Feichtinger wrote:

> Hi,
>
> I have a very specific situation that the implementation of a
> customer SIP user agent is absolutely not standards conform.
> Therefore, I use Kamailio as a SIP protocol adapter between the
> non-standard conform user agent(s) and the typical RFC3261 compliant
> user agents. Most conversions are working fine. But in a very
> specific scenario I have to change/convert a SIP response message to
> a SIP request message and change the SIP method´s name. This
> conversion is no problem for the SIP header fields. However, I
> haven't found a way for adapting the response-/request line of a SIP
> message. This line seems to be protected.
>
> The described situation of the perverse conversion I try to realize
> is following (please do not ask "why?" or think I'm mad...): (mad)
> UA1 == INVITE ==> SIP-Prot-Adapter(Kamailio) == INVITE ==> (typ.)UA2
>  UA1 <== BYE == SIP-Prot-Adapter(Kamailio) <== 488 == (typ.)UA2 UA1
> == BYE ==> SIP-Prot-Adapter(Kamailio) == ACK ==> (typ.)UA2
>
> I use the "textops" module for substitution and/or replacement in
> SIP header fields. But the "subst" and "replace" functions cannot be
> used for the request-/response line on top of the SIP messages. I
> was a little bit irritated, as the "search" function is still working
> on these lines, but not the subst/replace function. Creating a new
> SIP message with the UAC module (as alternative) is not okay, as this
> new message does not use the same values for Call-ID, From-tag a.s.o.
> and these values can't be changed before sending the message.
>
> Does anybody know a way / function / method for manipulating the
> request-/response line of a message? It would be perfect using a
> function á la "sed"/subst.
>
> Thanks Klaus
>
> P.S. I tested with kamailio-3.3.3
>
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-- 
Alex Balashov - Principal
Evariste Systems LLC
235 E Ponce de Leon Ave
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Tel: +1-678-954-0670
Web: http://www.evaristesys.com/, http://www.alexbalashov.com/