Re: Wireshark-dev Digest, Vol 173, Issue 14

Re: Wireshark-dev Digest, Vol 173, Issue 14

[Amanda Shafack]

Hi Jonathan,

I have completed the MyFirstContribution tutorial
(https://git-scm.com/docs/MyFirstContribution). You can find my work
in this repo (https://github.com/lkmandy/git/tree/psuh).

Also, regarding my initial starter contribution, I chose the
"micro-project" titled "Avoid pipes in git related commands in test
scripts" (source https://bit.ly/3iZQcT2).
Emily has approved the micro-project.

I plan to complete the micro-project and then move on to more research
on Git's HTTP protocol and other resources you've pointed out.

Let me know your thoughts on this, thanks.


On Tue, Oct 13, 2020 at 1:00 PM <wireshark-dev-request@wireshark.org> wrote:
>
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>
> Today's Topics:
>
>    1. lua decoder accessing info from layers above (Fulko Hew)
>    2. Re: lua decoder accessing info from layers above (John Thacker)
>    3. Re: lua decoder accessing info from layers above (Guy Harris)
>    4. Re: Introduction - An Outreachy 2020 Applicant (Jonathan Nieder)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 12 Oct 2020 19:59:46 -0400
> From: Fulko Hew <fulko.hew@gmail.com>
> To: Developer support list for Wireshark <wireshark-dev@wireshark.org>
> Subject: [Wireshark-dev] lua decoder accessing info from layers above
> Message-ID:
>         <CAGuV3hNXvRDUL02bmLxbkOLEgbOWQSPwj7sSne8CYCcgrNhPQg@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> I'm trying to update/improve someone else's decoder written in Lua.
> It's for a simple UDP (and TCP) based protocol.
> But I need to be able to get access to the upper layer
> to be able to decode it easily.
>
> Can someone provide an example of how to determine if the higher layer was
> UDP or TCP?
>
> Thanks
> Fulko
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>
> ------------------------------
>
> Message: 2
> Date: Mon, 12 Oct 2020 20:33:37 -0400
> From: John Thacker <johnthacker@gmail.com>
> To: Developer support list for Wireshark <wireshark-dev@wireshark.org>
> Subject: Re: [Wireshark-dev] lua decoder accessing info from layers
>         above
> Message-ID:
>         <CAP_QLgo5PYz79BXQvoQyiQGjZ-FqBVq__ybRg10xQ3DYd3KUQQ@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Mon, Oct 12, 2020, 8:00 PM Fulko Hew <fulko.hew@gmail.com> wrote:
>
> >
> > I'm trying to update/improve someone else's decoder written in Lua.
> > It's for a simple UDP (and TCP) based protocol.
> > But I need to be able to get access to the upper layer
> > to be able to decode it easily.
> >
> > Can someone provide an example of how to determine if the higher layer was
> > UDP or TCP?
> >
>
> If all you need to know is whether it was called from TCP or UDP, then a
> typical approach is to create slightly different dissector functions, one
> for TCP and one for UDP (they can then call a common function, setting a
> parameter) and register the TCP dissector with TCP and the UDP dissector
> with UDP. That approach for C dissectors is demonstrated, for example, here:
>
> https://gitlab.com/wireshark/wireshark/-/blob/master/doc/README.heuristic
>
> And it's pretty similar for Lua dissectors using some of the examples
> linked from here:
>
> https://gitlab.com/wireshark/wireshark/-/wikis/Lua
>
> John Thacker
> -------------- next part --------------
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>
> ------------------------------
>
> Message: 3
> Date: Mon, 12 Oct 2020 17:55:06 -0700
> From: Guy Harris <gharris@sonic.net>
> To: Developer support list for Wireshark <wireshark-dev@wireshark.org>
> Subject: Re: [Wireshark-dev] lua decoder accessing info from layers
>         above
> Message-ID: <93FB74E3-88D0-408F-883D-F0385A916EA0@sonic.net>
> Content-Type: text/plain;       charset=us-ascii
>
> On Oct 12, 2020, at 5:33 PM, John Thacker <johnthacker@gmail.com> wrote:
>
> > If all you need to know is whether it was called from TCP or UDP, then a typical approach is to create slightly different dissector functions,
>
> ...or, in that particular case, slightly *less* different functions, given that UDP provides a packet-based service (so that packet boundaries are provided for you, unless you have to send packets that don't fit in a UDP datagram and add your own reassembly - but, even there, *fragment* boundaries would probably be provided by UDP), while TCP provides a byte-stream service (with *no* packet boundary information).
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 12 Oct 2020 20:10:56 -0700
> From: Jonathan Nieder <jrnieder@gmail.com>
> To: Developer support list for Wireshark <wireshark-dev@wireshark.org>
> Cc: Emily Shaffer <emilyshaffer@google.com>, git@vger.kernel.com
> Subject: Re: [Wireshark-dev] Introduction - An Outreachy 2020
>         Applicant
> Message-ID: <20201013031056.GC3814681@google.com>
> Content-Type: text/plain; charset=us-ascii
>
> Richard Sharpe wrote:
> > Amanda Shafack wrote:
>
> >> Good day.
> >>
> >> I'm Amanda Shafack, an Outreachy 2020 applicant who wishes to
> >> contribute to the "Add Git protocol support to Wireshark" project.
> >>
> >> I have some experience coding in C and I hope to enhance
> >> my skill set by contributing to this project.
> >>
> >> In addition, I'm fascinated by network protocols and it's really
> >> exciting to get my hands around these concepts in a real-world
> >> project.
> >>
> >> I'm currently going through the project description and contribution
> >> guidelines.
> >
> > Welcome. There are many helpful people on the list.
> >
> > It would be useful if you can point us to a protocol description
> > document but that can wait until help is needed. It may be that all
> > the online resources are sufficient, but if not, do not hesitate to
> > use this list to ask questions.
>
> There's an overview of Git's HTTP protocol in the Pro Git book:
>
>   https://git-scm.com/book/en/v2/Git-Internals-Transfer-Protocols
>
> The official protocol spec in git.git (https://git.kernel.org/pub/scm/git/git.git)
> is split between a few files:
>
>   Documentation/technical/protocol-common.txt:
>     conventions for protocol docs
>
>   Documentation/technical/pack-protocol.txt:
>     overview of Git protocol
>
>   Documentation/technical/protocol-capabilities.txt:
>     optional capabilities
>
>   Documentation/technical/protocol-v2:
>     protocol v2, the new default (more about this is at
>     https://opensource.googleblog.com/2018/05/introducing-git-protocol-version-2.html)
>
>   Documentation/technical/http-protocol.txt:
>     how this works with http
>
>   Documentation/technical/pack-format.txt:
>     packed representation of Git objects (used both on disk and over
>     the wire)
>
> Amanda, if you have any questions, please don't hesitate to ask
> (#git-devel on IRC is the best place for that, and email works as
> well).  I am there around 15:00-24:00 UTC most days.  In addition to
> working on your initial starter contributions, we can start to put
> together a plan for the project.
>
> Richard, to set expectations: the internship period for accepted
> interns starts in December: https://www.outreachy.org/apply/project-selection/.
> Until then, potential interns are often not free full time, so we
> focus on smaller contributions that help get their feet wet in the
> codebase.
>
> Excited,
> Jonathan
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Wireshark-dev mailing list
> Wireshark-dev@wireshark.org
> https://www.wireshark.org/mailman/listinfo/wireshark-dev
>
>
> ------------------------------
>
> End of Wireshark-dev Digest, Vol 173, Issue 14
> **********************************************



-- 

Cheers!

Amanda  Shafack

Re: Introduction - An Outreachy 2020 Applicant

[Jonathan Nieder]

Hi Amanda,

Amanda Shafack wrote:

> Also, regarding my initial starter contribution, I chose the
> "micro-project" titled "Avoid pipes in git related commands in test
> scripts" (source https://bit.ly/3iZQcT2).

Thanks, sounds good.

> I plan to complete the micro-project and then move on to more research
> on Git's HTTP protocol and other resources you've pointed out.
>
> Let me know your thoughts on this, thanks.

I think that a good next step after the Git micro-project is to get to
know wireshark --- this would involve building wireshark, finding
something to change, and then changing it.

https://gitlab.com/wireshark/wireshark/-/wikis/Development/ describes
how to download and build wireshark.  Then for something to change, I
have a few different ideas:

a. tighten the error handling in epan/dissectors/packet-git.c
   (for example, what happens when there are not exactly 4 hexdigits
   at the beginning of a pkt-line?).  Git's
   Documentation/technical/protocol-common.txt describes the pkt-line
   format and Documentation/technical/pack-protocol.txt describes the
   Git transport dissected by packet-git.

b. add tests for the Git dissector.  test/README.test and the page it
   links to describe how wireshark's tests work

c. try to parse out the service name and protocol version in
   epan/dissectors/packet-git.c.  Git's
   Documentation/technical/protocol-v2.txt describes where we can find
   that information

That would get us more comfortable with the wireshark codebase and
would help prepare for fleshing out a plan for the internship.

Thoughts?

Sincerely,
Jonathan

Re: Introduction - An Outreachy 2020 Applicant

[Jonathan Nieder]

Richard Sharpe wrote:
> Amanda Shafack wrote:

>> Good day.
>>
>> I'm Amanda Shafack, an Outreachy 2020 applicant who wishes to
>> contribute to the "Add Git protocol support to Wireshark" project.
>>
>> I have some experience coding in C and I hope to enhance
>> my skill set by contributing to this project.
>>
>> In addition, I'm fascinated by network protocols and it's really
>> exciting to get my hands around these concepts in a real-world
>> project.
>>
>> I'm currently going through the project description and contribution
>> guidelines.
>
> Welcome. There are many helpful people on the list.
>
> It would be useful if you can point us to a protocol description
> document but that can wait until help is needed. It may be that all
> the online resources are sufficient, but if not, do not hesitate to
> use this list to ask questions.

There's an overview of Git's HTTP protocol in the Pro Git book:

  https://git-scm.com/book/en/v2/Git-Internals-Transfer-Protocols

The official protocol spec in git.git (https://git.kernel.org/pub/scm/git/git.git)
is split between a few files:

  Documentation/technical/protocol-common.txt:
    conventions for protocol docs

  Documentation/technical/pack-protocol.txt:
    overview of Git protocol

  Documentation/technical/protocol-capabilities.txt:
    optional capabilities

  Documentation/technical/protocol-v2:
    protocol v2, the new default (more about this is at
    https://opensource.googleblog.com/2018/05/introducing-git-protocol-version-2.html)

  Documentation/technical/http-protocol.txt:
    how this works with http

  Documentation/technical/pack-format.txt:
    packed representation of Git objects (used both on disk and over
    the wire)

Amanda, if you have any questions, please don't hesitate to ask
(#git-devel on IRC is the best place for that, and email works as
well).  I am there around 15:00-24:00 UTC most days.  In addition to
working on your initial starter contributions, we can start to put
together a plan for the project.

Richard, to set expectations: the internship period for accepted
interns starts in December: https://www.outreachy.org/apply/project-selection/.
Until then, potential interns are often not free full time, so we
focus on smaller contributions that help get their feet wet in the
codebase.

Excited,
Jonathan

Introduction - An Outreachy 2020 Applicant

[Amanda Shafack]

Good day.

I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
contribute to the "Add Git protocol support to Wireshark" project.

In addition, I have some experience coding in C and I hope to enhance
my skill set by contributing to this project.

I am currently going through the project description and contribution
guidelines.

Thanks.

-- 

Cheers!

Amanda  Shafack

Re: Introduction - An Outreachy 2020 Applicant

[Jonathan Nieder]

+wireshark-dev@wireshark.org
Hi Amanda,

Amanda Shafack wrote:

> I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
> contribute to the "Add Git protocol support to Wireshark" project.
>
> In addition, I have some experience coding in C and I hope to enhance
> my skill set by contributing to this project.
>
> I am currently going through the project description and contribution
> guidelines.

Welcome!

Since this project would involve Git (for Git protocol) and Wireshark
(where the dissector goes), we're comfortable working with you on
contributions to both Git and Wireshark during the application[1]
period.

https://gitlab.com/wireshark/wireshark/-/wikis/Development/ has some
pointers on getting started with Wireshark development.  I'm cc-ing
the wireshark developers list in case they have suggestions for an
approachable "first patch" idea to get used to that project's
contribution flow.

It's also a good idea to build and run wireshark and see if anything
strikes your eye as something you'd be interested in seeing work
differently.

For Git we have some suggestions for microprojects at
https://git.github.io/Outreachy-21-Microprojects/

Thanks for writing, and I look forward to working with you.  These are
two open source projects that I love and I hope you enjoy working with
them, too. :)

Sincerely,
Jonathan

[1] https://www.outreachy.org/apply/

Re: Introduction - An Outreachy 2020 Applicant

[Jonathan Nieder]

Jonathan Nieder wrote:

> +wireshark-dev@wireshark.org
> Hi Amanda,
>
> Amanda Shafack wrote:
>
>> I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
>> contribute to the "Add Git protocol support to Wireshark" project.
>>
>> In addition, I have some experience coding in C and I hope to enhance
>> my skill set by contributing to this project.
>>
>> I am currently going through the project description and contribution
>> guidelines.
>
> Welcome!
>
> Since this project would involve Git (for Git protocol) and Wireshark
> (where the dissector goes), we're comfortable working with you on
> contributions to both Git and Wireshark during the application[1]
> period.
>
> https://gitlab.com/wireshark/wireshark/-/wikis/Development/ has some
> pointers on getting started with Wireshark development.  I'm cc-ing
> the wireshark developers list in case they have suggestions for an
> approachable "first patch" idea to get used to that project's
> contribution flow.

Ahem, actually cc-ing that list this time.  Sorry for the noise.

> It's also a good idea to build and run wireshark and see if anything
> strikes your eye as something you'd be interested in seeing work
> differently.
>
> For Git we have some suggestions for microprojects at
> https://git.github.io/Outreachy-21-Microprojects/
>
> Thanks for writing, and I look forward to working with you.  These are
> two open source projects that I love and I hope you enjoy working with
> them, too. :)

Sincerely,
Jonathan

> [1] https://www.outreachy.org/apply/

Re: Introduction - An Outreachy 2020 Applicant

[Emily Shaffer]

On Thu, Oct 08, 2020 at 06:43:19PM -0700, Jonathan Nieder wrote:
> 
> Jonathan Nieder wrote:
> 
> > +wireshark-dev@wireshark.org
> > Hi Amanda,
> >
> > Amanda Shafack wrote:
> >
> >> I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
> >> contribute to the "Add Git protocol support to Wireshark" project.
> >>
> >> In addition, I have some experience coding in C and I hope to enhance
> >> my skill set by contributing to this project.
> >>
> >> I am currently going through the project description and contribution
> >> guidelines.
> >
> > Welcome!

Seconded! We're glad to have your interest. Jonathan and I tend to both
be available on IRC (#git-devel on Freenode) if you find you would
benefit from some real-time assistance; Jonathan goes by jrnieder and I
go by nasamuffin there. In general, everyone on both projects is motivated
to help you get through your application microproject as painlessly as
possible, so don't be shy if you feel stuck!

 - Emily

Re: Introduction - An Outreachy 2020 Applicant

[Amanda Shafack]

Noted, thank you.


On Fri, Oct 9, 2020 at 7:57 PM Emily Shaffer <emilyshaffer@google.com> wrote:
>
> On Thu, Oct 08, 2020 at 06:43:19PM -0700, Jonathan Nieder wrote:
> >
> > Jonathan Nieder wrote:
> >
> > > +wireshark-dev@wireshark.org
> > > Hi Amanda,
> > >
> > > Amanda Shafack wrote:
> > >
> > >> I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
> > >> contribute to the "Add Git protocol support to Wireshark" project.
> > >>
> > >> In addition, I have some experience coding in C and I hope to enhance
> > >> my skill set by contributing to this project.
> > >>
> > >> I am currently going through the project description and contribution
> > >> guidelines.
> > >
> > > Welcome!
>
> Seconded! We're glad to have your interest. Jonathan and I tend to both
> be available on IRC (#git-devel on Freenode) if you find you would
> benefit from some real-time assistance; Jonathan goes by jrnieder and I
> go by nasamuffin there. In general, everyone on both projects is motivated
> to help you get through your application microproject as painlessly as
> possible, so don't be shy if you feel stuck!
>
>  - Emily



-- 

Cheers!

Amanda  Shafack

Re: Introduction - An Outreachy 2020 Applicant

[Amanda Shafack]

Thanks for the details, Jonathan.
I'll get right on it


On Fri, Oct 9, 2020 at 1:25 AM Jonathan Nieder <jrnieder@gmail.com> wrote:
>
> +wireshark-dev@wireshark.org
> Hi Amanda,
>
> Amanda Shafack wrote:
>
> > I am Amanda Shafack, an Outreachy 2020 applicant who wishes to
> > contribute to the "Add Git protocol support to Wireshark" project.
> >
> > In addition, I have some experience coding in C and I hope to enhance
> > my skill set by contributing to this project.
> >
> > I am currently going through the project description and contribution
> > guidelines.
>
> Welcome!
>
> Since this project would involve Git (for Git protocol) and Wireshark
> (where the dissector goes), we're comfortable working with you on
> contributions to both Git and Wireshark during the application[1]
> period.
>
> https://gitlab.com/wireshark/wireshark/-/wikis/Development/ has some
> pointers on getting started with Wireshark development.  I'm cc-ing
> the wireshark developers list in case they have suggestions for an
> approachable "first patch" idea to get used to that project's
> contribution flow.
>
> It's also a good idea to build and run wireshark and see if anything
> strikes your eye as something you'd be interested in seeing work
> differently.
>
> For Git we have some suggestions for microprojects at
> https://git.github.io/Outreachy-21-Microprojects/
>
> Thanks for writing, and I look forward to working with you.  These are
> two open source projects that I love and I hope you enjoy working with
> them, too. :)
>
> Sincerely,
> Jonathan
>
> [1] https://www.outreachy.org/apply/



-- 

Cheers!

Amanda  Shafack