[SR-Users] Kamailio parse failed message

[Daniel-Constantin Mierla]

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 at gmail.com <mailto:miconda at 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.

Cheers,
Daniel

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

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