Thank you Pascal. I’ll fix the bug then ☺ Regards.
From: [email protected] [mailto:[email protected]] On Behalf Of Pascal Quantin Sent: Tuesday 3 November 2015 16:27 To: Developer support list for Wireshark Subject: Re: [Wireshark-dev] GTP sequence number equal to zero problem 2015-11-03 16:13 GMT+01:00 POZUELO Gloria (BCS/PSD) <[email protected]<mailto:[email protected]>>: Hi all, I’m developing an extension for the GTPv1 dissector and while I was debugging I’ve encountered something that it seems to me a bit confusing. In the dissect_gtp_common function from the packet-gtp.c source, there is a section that makes the matching between requests and responses. The thing is that I have a pcap in which I have a create PDP context request with sequence number equal to 0, then when in the code asks if the message has sequence number, it never enters in that part because, I guess, that 0 is equal than NULL. If (seq_no) { /* matching is done */ } I don’t know If this is a little bug or maybe the sequence number can’t be equal to 0. Can someone help me? Thanks! Regards. Hi Gloria, at first glance this seems to be a bug. Per 3GPP 29.060 chapter 9.3.1.1<http://9.3.1.1>: 9.3.1.1 Usage of Sequence Number The sending GGSN and SRNC shall use 0 for the value of the Sequence Number of the first G-PDU in a tunnel, only during the PDP context activation, and shall increment the Sequence Number for each following G-PDU. The value shall wrap to zero after 65535. The receiving GGSN and SRNC shall set the content of a counter to zero, only during the PDP context activation. When the receiving GGSN and SRNC receives a valid G-PDU, it shall increment this counter by one. This counter shall wrap to zero after 65535. It defines the "Expected Sequence Number". Could you please fill a bug on https://bugs.wireshark.org and even better, upload a fix on Gerrit (see https://www.wireshark.org/docs/wsdg_html_chunked/ChSrcContribute.html for details) ? Presumably we should have a booleab telling whether a sequence number was retrieved or not and test it (instead of seq_no being different from 0). Regards, Pascal. ________________________________ **** DISCLAIMER**** http://www.bics.com/maildisclaimer/
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