Weird issue with kamailio relaying messages to itself - sr-users

31 Jul 2017

Hello all,

I have been toying with kamailio lately, and I thought I had gotten to the
point where I had a mostly working (tm) prototype. I gave it a test drive
with some real calls, however, and an issue manifested at least once, where
homer received packets originating from the kamailio host, and whose
destination was also the kamailio host.

The dialog this manifested in is a generally problematic one, with many
retransmissions occurring because of slow database access (I haven't
implemented htable caching yet). No packet capture over the network is
actually taking place, I'm copying everything to homer with "trace_mode"set
to 1.

Homer shows these messages like in the screenshot:
https://imagebin.ca/v/3VGJAmovRBmo. Here's an example of a packet:

2017-07-28 14:32:29 +0300 : 2.3.4.5:5060 -> 2.3.4.5:5060
INVITE sip:1234567890@kamailio-server.org SIP/2.0
Record-Route: <sip:2.3.4.5;lr;ftag=as491cec82>
Via: SIP/2.0/UDP
2.3.4.5;branch=z9hG4bK0cf.07799e3eb71f33a9ef91178ac760ebd2.0
Via: SIP/2.0/UDP
2.3.4.5;branch=z9hG4bKsr-BnCVyrWoUladI14pU7Pry-Pzy-ONy-VSQ74NU7HzeYazq2nFU2Oc5FIWiGIKq-HXex1oONpam-C6IrIXkr4FQxZRh7sM
Max-Forwards: 69
From: <sip:subscriber@5.4.3.2:5061>;tag=as491cec82
To: <sip:1234567890@kamailio-server.org>
Contact:
<sip:2.3.4.5;line=sr-eNC05xhKefQnON1EglFrOkF0OfpzV2s9UzM9UXMNQXMn5-B0Q-s*>
Call-ID: 4e5d22c3369704b97d866c8d0f3798f8@192.168.201.2:5061
CSeq: 103 INVITE
User-Agent: Asterisk PBX 11.13.1~dfsg-2~bpo70+1
Date: Fri, 28 Jul 2017 11:32:24 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO,
PUBLISH, MESSAGE
Supported: replaces, timer
Remote-Party-ID: "9876543210" <sip:9876543210@192.168.201.2
...
 ;party=calling;privacy=off;screen=yes
Content-Type: application/sdp
Content-Length: 500

v=0
o=root 242468242 242468243 IN IP4 172.17.130.13
s=Asterisk PBX 11.13.1~dfsg-2~bpo70+1
c=IN IP4 172.17.130.13
t=0 0
m=audio 59426 RTP/AVP 18 101
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:50
a=sendrecv
a=rtcp:59427
a=ice-ufrag:hffIoy6x
a=ice-pwd:nXB8ip7Qz8ZG5yyZRr97kGJbej
a=candidate:igct4zWHEzhGCjWc 1 UDP 2130706431 172.17.130.13 59426 typ host
a=candidate:igct4zWHEzhGCjWc 2 UDP 2130706430 172.17.130.13 59427 typ host

Can something like this be triggered by misconfiguration in the routing
scripts? Should it worry me and should I dig into it more? Could it be a
bug of the siptrace module and nothing bad actually took place? I'm not
sure where to start with this, so any input would be greatly appreciated.
Thanks!