[SR-Users] uac_replace_from recovery with modified header

[Andreas Granig]

Hi,

This is a question for kamailio 3.0.x and I'm still trying to reproduce 
this issue somehow for latest stable, but maybe it was a known issue 
anyways which got fixed in newer versions, so I don't have to dig deeper 
into this:

There is an INVITE "A -> kamailio -> B", and kamailio does 
uac_replace_from() to replace the display- and user-part (leaving the 
domain-part untouched).

When there's a BYE "B -> kamailio -> A", then From/To are switched, so 
the replaced From of the INVITE becomes the replaced To of the BYE. 
Kamailio gets that one right and tries to recover (in auto-mode) the To.

However, in this BYE, B changes the domain-part of the To, which should 
be valid, as elements are only supposed to inspect the tags of From/To, 
right? The problem though is that when recovering the To, kamailio 
inserts garbage into the domain part. The vsf-Parameter in the Route of 
the BYE is definitely ok though, so that doesn't seem to be the issue.

Here's an example:

In the INVITE,
From: "ab12345"<sip:ab12345 at 192.168.0.12;user=phone>;tag=948a3340
gets rewritten to
From: "12345"<sip:12345 at 192.168.0.12;user=phone>;tag=948a3340

And in the BYE,

To: "12345"<sip:12345 at 1.2.3.4>;tag=948a3340
gets rewritten to
To: "12345"<sip:ab12345<@-%:68*0.0%12;user=phone>;tag=948a3340

Note that the received To in the BYE has a different host-part than what 
got sent out in the From of the INVITE, and when kamailio recovers the 
To, it doesn't recover the Display-part (not sure though if this is 
intended behaviour anyway), but it only party recovers the domain-part. 
You can still see some artefacts of the original domain (like the "68" 
from the second "168" octet, and the "12" from the last octet).

Has anyone encountered this issue before?

Andreas