[SR-Users] Kamailio parse failed message

[Daniel-Constantin Mierla]

Hello,

with TCP there is no MTU. In the previous pcap you sent there was a
wrong Content-Length value. Was that fixed?

Cheers,
Daniel


On 06/02/2017 12:24, Hai Bui Duc Ha wrote:
> Hi Daniel,
>
> I send you the pcap files on both client and server side.
> Analyse this files, I see the packet can not "reassemble"  INVITE
> message at server side:
> - At client.pcapng, it can detect 6 and 7th packets are one.
> - But on server.pcap, it can not "reassemble" 18 and 21st packets.
>
> I just explain as my understand. If you have any information, please
> ask me.
> I think the problem relate the MTU - fragmentation. But I'm not sure
> about this.
> Thank you for support !
>
> Regards,
> Hai Bui
>
> On Sun, Jan 22, 2017 at 4:33 PM, Hai Bui Duc Ha <hai.bui at htklabs.com
> <mailto:hai.bui at htklabs.com>> wrote:
>
>     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 at gmail.com <mailto:miconda at 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 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.
>>
>         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 <http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
>         Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com <http://www.kamailioworld.com>
>
>
>
>
>     -- 
>     Hai Bui
>     VoIP engineer, Cvoice team, HTK-HCM Office
>     Mobile: +84-165-618-9876
>
>
>
>
> -- 
> Hai Bui
> VoIP engineer, Cvoice team, HTK-HCM Office
> Mobile: +84-165-618-9876

-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com

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