Re: Adding libxml2 as optional Wireshark dependency

[Pascal Quantin <pascal.quantin () gmail com>]

Hi Anders,

2017-04-05 16:16 GMT+02:00 Anders Broman <anders.broman () ericsson com>:

> Hi,
>
> Would https://github.com/leethomason/tinyxml2 be an option?

it is C++ based. Am I correct to think that we have not opened that door
for dissectors yet?

Cheers,
Pascal.


> Regards
>
> Anders
>
>
>
> *From:* wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces@
> wireshark.org] *On Behalf Of *Alexis La Goutte
> *Sent:* den 5 april 2017 16:14
> *To:* Developer support list for Wireshark <wireshark-dev () wireshark org>
> *Subject:* Re: [Wireshark-dev] Adding libxml2 as optional Wireshark
> dependency
>
>
>
> Hi,
>
> There is some dissector using XML ? (diameter...)
>
> May be see to convert (or using actual XML code)
>
>
>
> Cheers
>
>
>
> On Wed, Apr 5, 2017 at 3:48 PM, Pascal Quantin <pascal.quantin () gmail com>
> wrote:
>
> Hi Ahmad and Graham,
>
>
>
> 2017-04-05 15:38 GMT+02:00 Graham Bloice <graham.bloice () trihedral com>:
>
>
>
>
>
> On 5 April 2017 at 14:11, Ahmad Fatoum <ahmad () a3f at> wrote:
>
> Hello everyone,
>
> I was advised on Gerrit to post this issue here as to garner wider input.
>
> This concerns proposed Change-Id I13c0a2f408fb5c21bad7ab3d7971e0fa8ed7d783
> [1] intending to add libxml2 as optional dependency to Wireshark.
>
> I am currently preparing to submit upstream, changes I did to the EPL v2
> dissector (packet-epl.c).
>
> A significant change is the ability to optionally read in user-supplied
> XML device descriptions and to extract type/description/mapping information
> for aiding the dissection. See this previous submission of mine to the
> mailing list: https://www.wireshark.org/lists/wireshark-dev/
> 201701/msg00154.html
>
>
>
> Seeing as there also has been interest for libxml2 support in dissectors
> in the past:
>
> https://www.wireshark.org/lists/wireshark-dev/201005/msg00108.html
>
> https://ask.wireshark.org/questions/36063/using-libxml2-
> in-my-own-dissector
>
>
>
> I think, it would be a good idea to have this as optional dependency as
> Glib's GMarkup may be inadequate or inconvenient for parsing actual XML.
>
>
>
> Looking forward to your feedback.
>
> Best regards,
> Ahmad Fatoum
>
> [1] https://code.wireshark.org/review/#/c/20912/
>
> Thanks for the post,
>
>
>
> 1.  Where will the Windows binaries come from and are these supported long
> term?  The  libXml2 downloads page indicates another site provides Windows
> binaries [1].  The binaries at that site in the 64 bit directory seem to be
> the most recent and are labelled as libXml2-2.9.3 [2].  The current release
> of libXml2 is 2.9.4 which has a number of security fixes among other bug
> fixes and enhancements [3] so it would appear that the Windows binaries are
> not being maintained.
>
>
>
> I suggest to use the binaries provided by openSUSE: they provide win32 and
> win64 variants for libxml2 2.9.0 and we are already using their packages
> for several third party libraries. If it is really required to take the
> latest version, I can probbly give it a try (I already did this in the past
> to package a newer version than the one from openSUSE).
>
>
> 2.  According to the diagram at [1], libXml2 depends on iconv and zlib.
> We currently build our own zlib, will that be suitable for the libXml2
> dependency?  What will be the source of the iconv binary (iconv-1.14 is
> available in the same download area as libXml2 [2])?
>
>
>
> Same thing: we can use the ones provided by openSUSE (we already have
> those dependencies for other packages).
>
>
>
>
> 3. The readme.txt in the download area ([2]) has some "interesting" text:
>
> These are experimental 64bit binaries. For completeness, 32bit binaries
>
> built using the same method are also included.
>
>
>
> The libraries in these packages are made using GCC (MinGW) toolchain. It is
>
> presently not possible to use these libraries with any recent version of the
>
> Microsoft Visual C compiler because of conflicting C-runtimes. To help you
>
> resist the temptation, the import libraries (.LIB) are not provided at all.
>
> If you need these libraries in an environment which mandates the use of the
>
> Microsoft toolchain, you will have to build them from source yourself.
>
> and inspection of the download shows this is true, so it appears that
> we'll need to rebuild to obtain the import .lib file.
>
>
>
> As part of the process of integrating openSUSE libraries, we are
> generating the .lib file and adding it in the package we upload on our
> server, so it should be OK.
>
>
>
> 4. Microsoft have a Visual Studio porting effort underway called vcpkg
> [4], that does include libXml2, but unfortunately is only for VS2015 or
> later.  If we move to VS2015 for main releases (post 2.4 release) then this
> may be a viable source for libXml2 and other packages we use.  It might be
> possible to use this to build VS2013 libXml2.
>
>
>
> 5.  Are there any manufacturers or tools that produce XML device
> description files for the EPL dissector such that choosing XML as the input
> format is the most sensible choice, or would another format be just as
> applicable?
>
>
>
> I agree XML can be painful, so this is a good question ;)
>
>
>
>
>
> [1]: https://www.zlatkovic.com/libxml.en.html
> [2]: ftp://ftp.zlatkovic.com/libxml/64bit/
>
> [3]: http://xmlsoft.org/news.html
>
> [4]: https://github.com/Microsoft/vcpkg
>
>
>
> --
>
> Graham Bloice
>
>
>
>
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