Re: How to build the simple ASN.1 UDP-based dissector example (foo)

[Vincent Randal <vtrandal () gmail com>]

Hi Graham,

Thank you for taking the time to help with some potential misconceptions. I
apologize for not replying to your concerns sooner. I can reassure you we
have the same understanding regarding the role of cmake and make in the
build process. When I refer to cmake I mean the build method that begins
with cmake similar to how you put it: "We're doing cmake builds these days.
All our Wireshark builds are cmake." per your SF19 presentation [
https://www.youtube.com/watch?v=Fp_7g5as1VY&t=3380s]

Given that the Wireshark documentation for building the simple ASN.1-based
dissector example is not quite up to date for "cmake builds" .AND. and
cmake has no requirement that the build folder be named build, it was just
a matter of time that someone would point that out as I did. Maybe they
already have. So then I also apologize for not using the preferred method
for reporting bugs: the Wireshark bug database <https://bugs.wireshark.org/>
.

It's been 14 years since I looked (glanced I might say) at Wireshark
dissector code. As I gain a bit more confidence I will report bugs to the
bug database rather than discussing them in the mailing list. Many people
on this mailing list have indulged my need for guidance for which I am
sincerely grateful. It's my intention to reciprocate by helping when and
where I can in due time.

Thank you,
Vincent Randal

On Tue, Apr 13, 2021 at 9:46 AM Graham Bloice <graham.bloice () trihedral com>
wrote:

> Just to reset what I think are some misconceptions here:
>
>
>    1. CMake, despite having the verb "Make" in its name, doesn't make the
>    application.  CMake makes something (depends on the platform, i.e. a
>    Makefile or ninja build file or Visual Studio solution\project files) that
>    then allows you to make the application, this is the "generator" specified
>    when running CMake.  CMake can also create some source files, e.g. config.h
>    for use when making the application.
>    2. The CMake generation produces build artefacts that have multiple
>    targets to make the distinct parts of a complex application such as
>    Wireshark.
>    3. There is a build target , that will generate all the asn1 based
>    dissectors.  Each dissector also has its own specific target, e.g. .  This
>    isn't run from the top level Wireshark target as we don't need to
>    degenerate the asn1 dissectors on each build, only when something in them
>    changes.
>    4. The method to specify a build target vary with the build
>    mechanism.  For VisualStudio you can specify the project file or the
>    solution file with a /t:xxx argument to specify the target (each project
>    file is a target).  Pascal has shown how it's done for Ninja builds.
>    5. There is a target for each asn1 based dissector;
>    "generate_dissector-foo" and a target to generate all the asn1 dissectors,
>    "asn1".
>    6. The magic part of CMake that invokes asn2wrs to generate the
>    dissectors from the asn1 files (and other bits) is in
>    cmake\modules\UserAsn2Wrs.cmake and this is invoked in each dissectors
>    specific CMakeLists.txt via the CMake macro ASN2WRS().  The asn1 target is
>    generated by the CMakeLists.txt in epan/dissectors/asn1 and simply adds
>    each generated dissector target as a dependency of the asn1 target.
>
>
> On Tue, 13 Apr 2021 at 16:03, Pascal Quantin <pascal () wireshark org> wrote:
>
> > Hi Vicent,
> >
> > Le mar. 13 avr. 2021 à 16:53, Vincent Randal <vtrandal () gmail com> a
> > écrit :
> >
> > > I should give that a try. What version of Windows and tools are you
> > > using? I’m beat. I need to do something that works soon.
> >
> > No need to install Windows; it works the same way on Linux. Go to your
> > build folder and run:
> > ninja epan/dissectors/asn1/foo/generate_dissector-foo
> > Assuming you are using ninja, otherwise replace it by make.
> > The target should have been created iby running CMake after the addition
> > of the CMakeListsCustom.txt file.
> >
> > Best regards.
> >
> >
> > > On Tue, Apr 13, 2021 at 8:47 AM Anders Broman via Wireshark-dev <
> > > wireshark-dev () wireshark org> wrote:
> > >
> > > > Hi,
> > > >
> > > > I don’t think they are generated what will be generated are the files
> > > > needed to *DO *the generation.
> > > >
> > > > On windows the next step is to run
> > > >
> > > > msbuild /m /p:Configuration=RelWithDebInfo
> > > > epan\dissectors\asn1\h248\generate_dissector-h248.vcxproj
> > > >
> > > > which will the generate the .c and .h files
> > > >
> > > > Regards
> > > >
> > > > Anders
> > > >
> > > >
> > > >
> > > > *From:* Wireshark-dev <wireshark-dev-bounces () wireshark org> *On Behalf
> > > > Of *Vincent Randal
> > > > *Sent:* den 13 april 2021 16:40
> > > > *To:* Developer support list for Wireshark <wireshark-dev () wireshark org
> > > > >
> > > > *Subject:* Re: [Wireshark-dev] How to build the simple ASN.1 UDP-based
> > > > dissector example (foo)
> > > >
> > > >
> > > >
> > > > Correct insofar as there are no generated files associated with
> > > > asn1/foo directory. Namely, packet-foo.c and packet-foo.h did not get
> > > > generated. But maybe that's not definitive proof that asn1/foo dissector
> > > > did not get built. How else can I confirm the dissector was or was not
> > > > built? Open Wireshark and attempt to apply "foo" as a display filter? It's
> > > > not there.
> > > >
> > > >
> > > >
> > > > On Tue, Apr 13, 2021 at 8:10 AM Anders Broman via Wireshark-dev <
> > > > wireshark-dev () wireshark org> wrote:
> > > >
> > > > Hi,
> > > >
> > > > So you are saying that if you create foo dir like
> > > >
> > > > epan/dissectors/asn1/foo/
> > > >
> > > > Rename and update the custom cmake file to
> > > >
> > > > set(CUSTOM_ASN1_SRC_DIR
> > > >
> > > >                            foo
> > > >
> > > > )
> > > >
> > > > And place your source file and cmake.txt in the foo dir then rerun the
> > > > cmake process
> > > >
> > > > Nothing happens?
> > > >
> > > > Try to delete the build dir  before rerunning cmake again?
> > > >
> > > > I’m not sure on linux if the generate cmake file ends up under the
> > > > build dir or in the source dir.
> > > >
> > > >
> > > >
> > > > Regards
> > > >
> > > > Anders
> > > >
> > > > *From:* Wireshark-dev <wireshark-dev-bounces () wireshark org> *On Behalf
> > > > Of *Vincent Randal
> > > > *Sent:* den 13 april 2021 15:32
> > > > *To:* Developer support list for Wireshark <wireshark-dev () wireshark org
> > > > >
> > > > *Subject:* Re: [Wireshark-dev] How to build the simple ASN.1 UDP-based
> > > > dissector example (foo)
> > > >
> > > >
> > > >
> > > > I tried renaming ./epan/dissectors/asn1/CMakeListsCustom.txt.example to
> > > > CMakeListsCustom.txt with an entry as follows:
> > > >
> > > > # Add a list of your custom asn1 dissectors here
> > > > set(CUSTOM_ASN1_SRC_DIR
> > > >    foo
> > > > )
> > > >
> > > >
> > > >
> > > > Again, the build did not update any targets even with that change. But
> > > > this is progress because that underscores the Step by Step instructions
> > > > need to be updated to something that works. Any more ideas?
> > > >
> > > >
> > > >
> > > > On Tue, Apr 13, 2021 at 7:12 AM John Thacker <johnthacker () gmail com>
> > > > wrote:
> > > >
> > > > On Tue, Apr 13, 2021, 8:32 AM Vincent Randal <vtrandal () gmail com>
> > > > wrote:
> > > >
> > > > Hello everyone,
> > > >
> > > >
> > > >
> > > > I need help building the simple ASN.1 UDP-based dissector example
> > > > (foo); specifically, I need help building the generate_dissector-*proto*
> > > > target (Step #6 below). I'm certainly missing something here.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > (c) I created directory "foo" by extracting the attachment (foo.tgz) in
> > > > epan/dissectors/asn1/
> > > >
> > > > (d) There is a CMakeListsCustom.txt.example file in
> > > > epan/dissectors/asn1 which already contains an entry for "foo".
> > > >
> > > > (e) Since I don't know what to do in Step #6, I build Wireshare (using
> > > > cmake), but no build targets get updated.
> > > >
> > > >
> > > >
> > > > If the solution to this problem belongs in the Wireshark documentation,
> > > > I would be glad to help update the documentation. Namely, I don't
> > > > understand the usage of the 5 (five) CMakeListsCustom.txt.example files
> > > > inWireshark source code.
> > > >
> > > >
> > > >
> > > > The CMakeListsCustom.txt.example files are just that, examples. You
> > > > need to copy or rename them to CMakeListsCustom.txt (without the .example)
> > > > for them to have any effect (and edit them appropriately to add the
> > > > dissector name to the list, not commented out.)
> > > >
> > > >
> > > >
> > > > CMake is configured to look for the files by that name.
> > > >
> > > >
> > > >
> > > > John Thacker
> --
> Graham Bloice
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