DESEGMENT_ONE_MORE_SEGMENT usage/fault

[Lajos Oláh <lajos.olah () ericsson com>]

Hi all,

I'm developing a dissector dissecting MTP2 packets from RTP stream (for semipermanent connections). I used part of the 
code from packet-lapd.c (it is almost tha same except that it is for the LAPD protocol).

In that code, when the RTP data ends in the middle of an MTP2 packet, the dissector sets pinfo->desegment_offset = 0 
and pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT and exits.

In the README.developer, it is written that if a dissector sets these values and returns it will be called again with 
data from the actual packet plus the data from the next packet. But this never happens. My dissector is never called 
with more data than 1 RTP data filed (40 byte in my case).

I've also created debug patches for the TELNET dissector (packet-telnet.c) (to test this defregmentation functionality 
outside my buggy code) to force the dissector to always request data from the next packet using 
DESEGMENT_ONE_MORE_SEGMENT but it was failing as well.

Have anyone of You encountered such problem? Am I doing something wrong?

Do I need to do something extra to get this feature work or we have a wireshark bug?

Please share experiences with these defregmentation method.

(I've attached my code with debug printing included)

Thanks.



LAJOS OLAH
System Test Engineer

Ericsson Telecom Hungary
RFT/D
Budapest, Irinyi Jozsef Street 4-20
1017, Hungary
Phone +36309537333
lajos.olah () ericsson com
www.ericsson.com






Ericsson Magyarország Kft., Székhely: Budapest, Laborc u.1. Nyilvántartó cégbíróság: Fővárosi Bíróság. Cégjegyzékszám: 
01-09-070937

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Attachment: packet-mtp2.c
Description: packet-mtp2.c

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