Hi Daniel,

Thank for your advice.

I will capture and analyze the call log on both client and kamailio to check the packet size.

Regards,

Hai Bui

On Fri, Jan 20, 2017 at 3:38 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:

On 19/01/2017 22:56, Daniel-Constantin Mierla wrote:

Hello,

On 19/01/2017 10:48, Hai Bui Duc Ha wrote:

Hi Daniel,

Thank you for reply.

 

On Tue, Jan 17, 2017 at 6:05 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:

Hello,

apparently I missed the follow ups on this discussion, dragged in by other topics on mailing list. 

Can you get the pcap with all the traffic taken on kamailio server for the call (from initial invite to the end of the call)?

I send you the pcap at enclosed file. You can see the packet No.5 , it missing SIP message body:
            Media Attribute (a): rtpmap:8 PCMA/8000

            Media Attribute (a): rtpmap:101 telephone-event/8000

            Media Attribute (a): fmtp:101 0-16

I expect that content length is mismatching or there is a '\0' inside the sdp.

Can you explain me more about this ?

TCP is a stream protocol, meaning that the application (kamailio) need to read and parse to figure out the end of a SIP message. The state machine as per RFC requires the application to read and identify the Content-Length header, take its value, read until the end of headers is found (an empty line) and from there on read as much as the value of Content-Length to get the body and consider the end of message there.

If the sending application puts a lower value in the Content-Length than the number of chars in the body, the rest remains in the buffer and the receiving application (kamailio) attempts to parse a new SIP message.

The other thing I was thinking of was the presence of '\0' which marks the end of string in C.

I will look at the pcap very soon and see what I find there.

The problem is the value of Content-Lenght set by the client -- it is set only to the size that it is view as part of the invite. A bit later the client sends more sdp, but exceeding the size sent in C-L header. That part of SDP remains as garbage.

So there is a bug in client app.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com

--

Hai Bui

VoIP engineer, Cvoice team, HTK-HCM Office

Mobile: +84-165-618-9876