Re: GTP sequence number equal to zero problem

[Anders Broman <anders.broman () ericsson com>]

Hi,
You are supposed to try to fix the compilation errors even if you can’t verify the fix yourself. If you follow the link 
to the failing build bot and then click on
stdio<https://buildbot.wireshark.org/petri-dish/builders/Ubuntu%20x86-64%20Petri%20Dish/builds/3877/steps/compile_4/logs/stdio>
 of that link you can see the error log at least some of it should be pretty obvious how to fix. Once done we will 
rerun the build boot for you.

Regards
Anders
From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of POZUELO 
Gloria (BCS/PSD)
Sent: den 4 november 2015 10:38
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] GTP sequence number equal to zero problem

Hello again,

I’ve received an email in which I’m notified that there’s a buildbot failure on Ubuntu regarding to this fix. Do I have 
to do something else concerning to this fix or do you take over this problem? I’m developing for Windows platform, so I 
don’t have the needed platform to debug that compilation error.

Regards.

From: wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org> 
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of POZUELO Gloria (BCS/PSD)
Sent: Tuesday 3 November 2015 16:33
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] GTP sequence number equal to zero problem

Thank you Pascal. I’ll fix the bug then ☺

Regards.

From: wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org> 
[mailto:wireshark-dev-bounces () wireshark org] 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) <gloria.pozuelo () bics com<mailto:gloria.pozuelo () bics com>>:
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.

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