Wireshark mailing list archives
Re: wireshark GUI vs tshark
From: Jaap Keuter <jaap.keuter () xs4all nl>
Date: Tue, 24 Nov 2009 17:52:41 +0100
Hi Brian, "This is my development code" is not an excuse. Cut away the crap, or structure it. "You forget to set initialized to TRUE in your handoff functions." means the in your handoff routines you have a semaphore, but you never set it to TRUE, even if the code has already executed. Next time handoff is called the code runs again. So, at the end set the semaphore. Accessing tvbuff like this is a problem. You have absolutely NO guarantee that you can access the data this way. You WILL have array overruns, problems with composite TVBs, etc, etc. We have painstakingly provided you with a whole series of safe access functions to handle everything you want to do in a single statement. Did I already mention these are safe methods? No buffer overruns? With exception handling build in? "I am a java programmer and just started to dig into this C stuff". I would say welcome to the bear metal. No more handholding and sandboxing here..... doc/README.developer is your friend. Thanks, Jaap On Tue, 24 Nov 2009 10:59:28 -0500, Brian Oleksa <oleksab () darkcornersoftware com> wrote:
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 tellanything,other than that a problem was detected. That's why Chris asked yousomemore questions on the whole situation. Maybe we can help you
further
whenyou 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 otherinformationthat you think might be relevant. By the way, I tried a similar tshark command using Wireshark
1.2.4
onWindows XP SP3 with no problems. Maybe you are running an olderversionof Wireshark with a known bug that has been fixed, or maybe your test.pcap file is corrupt or exposes a Wireshark bug, in which caseabug report might be in order with the attached test.pcap fileincludedso 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 BrianOleksaSent: 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
pcapfile 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 thefollowingcommand: 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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Current thread:
- Re: wireshark GUI vs tshark, (continued)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 23)
- Re: wireshark GUI vs tshark Jaap Keuter (Nov 23)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 23)
- Re: wireshark GUI vs tshark Maynard, Chris (Nov 23)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 23)
- Re: wireshark GUI vs tshark Jaap Keuter (Nov 23)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 23)
- Re: wireshark GUI vs tshark Jaap Keuter (Nov 23)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 24)
- Re: wireshark GUI vs tshark Maynard, Chris (Nov 24)
- Re: wireshark GUI vs tshark Jaap Keuter (Nov 24)
- Re: wireshark GUI vs tshark Brian Oleksa (Nov 23)
- Save while capturing BARILLY YANN (Nov 24)