Re: wireshark GUI vs tshark

["Maynard, Chris" <Christopher.Maynard () GTECH COM>]

I don't have the time to examine your code but I think
doc/README.developer will answer all of your questions.  In particular,
read all the warnings about using tvb_get_ptr() and examine the sample
dissector included in the file, specifically the
proto_reg_handoff_PROTOABBREV() function.

But as Jaap suggested earlier, you should *really* read
doc/README.developer in its entirety.

- Chris

-----Original Message-----
From: wireshark-dev-bounces () wireshark org
[mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Brian Oleksa
Sent: Tuesday, November 24, 2009 10:59 AM
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] wireshark GUI vs tshark

Jaap and Chris

I appreciate your help.
I apologize for the messy code....this is my development code.

I have changed some of the code based on your suggestions that you made 
below: Such as...

FT_BYTES, BASE_HEX is now FT_BYTES, BASE_NONE
I have closed off the value_string helen_vals[] with {0, NULL}

However.. I do have some questions.

What do you mean when you say:  "You forget to set initialized to TRUE
in your handoff functions."

Also..why does accessing tvbuff this way pose a problem..??    guint8 *
ptr = (guint8*) tvb->real_data;
Accessing tvbuff this way appears to be working fine...but would like
some feed back if there is a well-known & correct way to do this.

I have attached a clean version of the code. It is now formatted and all

the old commented out code is now removed.

I am a java programmer and just started to dig into this C stuff....So I

apologize for any code that does not make sense.

Again...any help is greatly appreciated.

Thanks,
Brian



Jaap Keuter wrote:
> Hi,
>
> Oke, quick review then.
>
> First of all the code is a mess. That results in:
> 1. hard to look through.
> 2. hard to spot even obvious errors.
>
> You forget to set initialized to TRUE in your handoff functions.
>
>   FT_BYTES, BASE_HEX should be FT_BYTES, BASE_NONE
>
> Many inconsistencies in header blubs and labels.
>
> value_string helen_vals[] isn't closed off by {0, NULL}
>
>               guint8 * ptr = (guint8*) tvb->real_data;
> Going about this way of accessing tvbuff data leads guaranteed to
failure.
> For me it's enough to abort furher review of this code.
>
> My advice: really read all of doc/README.developer and take the advice
to hart.
> Thanks,
> Jaap
>
> Brian Oleksa wrote:
>   
> > Jaap
> >
> > Eventually this might get licensed...but just not sure what direction
we 
> > will be going.
> >
> > I have tracked down many many problems before when my code crashed 
> > within the GUI...because I would get some what of
> > a decent error. But I am having a hard time tracking down this bug as
it 
> > runs fine in the GUI but not in tshark.
> >
> > Doesn't tshark run off the same base code as the GUI does..?? If 
> > so...then you think if it would crash in one that it would crash in
the 
> > other....wouldn't you think..??
> >
> > Attached is my code. Any help is greatly appreciated.
> >
> > Thank you
> > Brian
> >
> >
> >
> >
> >
> > Jaap Keuter wrote:
> >     
> > > Hi,
> > >
> > > Well, your assumption is probably right, that your dissector has 
> > > something to do with it.
> > >
> > > You can post it, but we prefer to spend our time on GPL'ed code. I 
> > > don't know what you license will be.
> > > If you prefer not to publish your code you can probably find enough 
> > > clues in the documentation in the doc directory.
> > >
> > > Thanks,
> > > Jaap
> > >
> > > Brian Oleksa wrote:
> > >  
> > >       
> > > > Chris and Jaap
> > > >
> > > > Well.... I guess I can point out the obvious here:
> > > >
> > > > I wrote a dissector that works fine with the GUI with no 
> > > > problem...but it crashes when I use tshark.
> > > >
> > > > HOWEVER... if I remove my dissector....then my pcap file loads fine

> > > > within tshark.
> > > >
> > > > So the problem has to be with my dissector....correct..??
> > > >
> > > > Is there anyway I can post my code so you can take a look..??
> > > >
> > > > This is hard to track down as again everything works fine in the
GUI 
> > > > and I get NO real error message within tshark.
> > > >
> > > > What do you think..?
> > > >
> > > > Thanks,
> > > > Brian
> > > >
> > > >
> > > >
> > > > Maynard, Chris wrote:
> > > >    
> > > >         
> > > > > The file may not be corrupt but might contain packet(s) which are
> > > > > exposing a tshark bug.  If you can post the capture file, that
would
> > > > > probably help.  If you don't wish to post it on the mailing list,
you
> > > > > can open a bug report and post it there instead, marking the file
as
> > > > > private if you so desire so only the core developers have access
to it.
> > > > > - Chris
> > > > >
> > > > > -----Original Message-----
> > > > > From: wireshark-dev-bounces () wireshark org
> > > > > [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Brian
Oleksa
> > > > > Sent: Monday, November 23, 2009 12:59 PM
> > > > > To: Developer support list for Wireshark
> > > > > Subject: Re: [Wireshark-dev] wireshark GUI vs tshark
> > > > >
> > > > > Jaap and Chris
> > > > >
> > > > > I am running this on Win XP service pack 2.
> > > > > I am using wireshark Version 1.2.4 (SVN Rev 30978).
> > > > >
> > > > > The test.pcap file has been around for a while...so chances are it

> > > > > is not corrupt. It never crashes using the GUI...it just crashes
and 
> > > > > gives me that pop up when I run it with that tshark command.
> > > > >
> > > > > This is about all the information that I can provide....unless you

> > > > > can think of something else that you need..??
> > > > >
> > > > > Thanks,
> > > > > Brian
> > > > >
> > > > >
> > > > > Jaap Keuter wrote:
> > > > >        
> > > > >           
> > > > > > Hi Brian,
> > > > > >
> > > > > > Thanks for including the error report. It in itself doesn't tell
> > > > > >             
> > > > > >             
> > > > > anything,
> > > > >        
> > > > >           
> > > > > > other than that a problem was detected. That's why Chris asked
you
> > > > > >             
> > > > > >             
> > > > > some
> > > > >        
> > > > >           
> > > > > > more questions on the whole situation. Maybe we can help you
further
> > > > > >             
> > > > > >             
> > > > > when
> > > > >        
> > > > >           
> > > > > > you look into them.
> > > > > >
> > > > > > Thanks,
> > > > > > Jaap
> > > > > >
> > > > > > On Mon, 23 Nov 2009 12:02:17 -0500, Brian Oleksa
> > > > > > <oleksab () darkcornersoftware com> wrote:
> > > > > >              
> > > > > >             
> > > > > > > Chris
> > > > > > >
> > > > > > > I have attached the error this time....sorry about that. :-)
> > > > > > >
> > > > > > > I get this error when I run with tshark using the following
command:
> > > > > > > tshark -nr test.pcap ip.dst==x.x.x.x
> > > > > > > But when I filter in the GUI ... I have no problems.
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Brian
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > Maynard, Chris wrote:
> > > > > > >                    
> > > > > > >               
> > > > > > > > > Any thoughts..??
> > > > > > > > >                                     
> > > > > > > > >                   
> > > > > > > > My first thought was, "I guess you forgot to include the
error." :)
> > > > > > > > In addition to the error, you might want to include some
Wireshark
> > > > > > > > version information, what OS you're running on and any other
> > > > > > > >                           
> > > > > > > >                 
> > > > > > information
> > > > > >              
> > > > > >             
> > > > > > > > that you think might be relevant.
> > > > > > > >
> > > > > > > > By the way, I tried a similar tshark command using Wireshark
1.2.4
> > > > > > > >                     
> > > > > > > >                 
> > > > > on
> > > > >        
> > > > >           
> > > > > > > > Windows XP SP3 with no problems.  Maybe you are running an
older
> > > > > > > >                           
> > > > > > > >                 
> > > > > > version
> > > > > >              
> > > > > >             
> > > > > > > > of Wireshark with a known bug that has been fixed, or maybe
your
> > > > > > > > test.pcap file is corrupt or exposes a Wireshark bug, in which
case
> > > > > > > >                     
> > > > > > > >                 
> > > > > a
> > > > >        
> > > > >           
> > > > > > > > bug report might be in order with the attached test.pcap file
> > > > > > > >                     
> > > > > > > >                 
> > > > > included
> > > > >        
> > > > >           
> > > > > > > > so the core developers can analyze the error and find & fix the
bug.
> > > > > > > > - Chris
> > > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: wireshark-dev-bounces () wireshark org
> > > > > > > > [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Brian
> > > > > > > >                     
> > > > > > > >                 
> > > > > Oleksa
> > > > >        
> > > > >           
> > > > > > > > Sent: Sunday, November 22, 2009 10:49 PM
> > > > > > > > To: Developer support list for Wireshark
> > > > > > > > Subject: [Wireshark-dev] wireshark GUI vs tshark
> > > > > > > >
> > > > > > > >
> > > > > > > > Wiresharkers
> > > > > > > >
> > > > > > > > When I use my dissector with the GUI... everything works fine.
The
> > > > > > > >                     
> > > > > > > >                 
> > > > > pcap
> > > > >        
> > > > >           
> > > > > > > >                           
> > > > > > > >                 
> > > > > >              
> > > > > >             
> > > > > > > > file that I load comes right up with NO problems. I can filter 
> > > > > > > > (ip.dst==x.x.x.x) with no problems.
> > > > > > > >
> > > > > > > > But if I try to open that same pcap file with tshark using the
> > > > > > > >                           
> > > > > > > >                 
> > > > > > following
> > > > > >              
> > > > > >             
> > > > > > > > command:
> > > > > > > >
> > > > > > > > tshark -nr test.pcap ip.dst==x.x.x.x    
> > > > > > > > The files appears to start loading.. then I get the following
error.
> > > > > > > > Any thoughts..??
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Brian
> > > > > > > >             
> > > > > > > >                 
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