Introduction
Introduction
This chapter will provide you with information about Wireshark
development in general.
What is Wireshark?
Well, if you want to start Wireshark development, you might already
know what Wireshark is doing. If not, please have a look at the
Wireshark User's Guide,
which will provide a lot of general information about it.
Development and maintenance of Wireshark
Wireshark was initially developed by Gerald Combs. Ongoing development
and maintenance of Wireshark is handled by the Wireshark team, a loose
group of individuals who fix bugs and provide new functionality.
There have also been a large number of people who have contributed
protocol dissectors to Wireshark, and it is expected that this will
continue. You can find a list of the people who have contributed
code to Wireshark by checking the about dialog box of Wireshark, or have
a look at the page on the Wireshark
web site.
The
communication between the developers is usually done through the developer
mailing list, which can be joined by anyone interested in the development
process. At the time this document was written, more than 500 persons were
subscribed to this mailing list!
It is strongly recommended to join the developer mailing list, if you
are going to do any Wireshark development. See
about the different Wireshark
mailing lists available.
Programming language(s) used
Almost any part of Wireshark is implemented in plain ANSI C.
The typical task for a new Wireshark developer is to extend an existing,
or write a new dissector for a specific network protocol. As (almost) any
dissector is written in plain old ANSI C, a good knowledge about ANSI C
will be sufficient for Wireshark development in almost any case.
So unless you are going to change the development process of Wireshark
itself, you won't come in touch with any other programming language than
ANSI C (such as perl or python, which are used only in the Wireshark build
process).
Beside the usual tools for developing a program in C (compiler, make, ...),
the build process uses some additional helper tools (Perl, Python, Sed,
...), which are needed for the build process when Wireshark
is to be installed from the released source packages. If Wireshark is
installed from a binary package, none of these helper tools are needed on
the target system.
Open Source Software
Wireshark is an open source software project, and is released under
the GNU General Public Licence (GPL).
You can freely use Wireshark on any number of computers you like, without
worrying about license keys or fees or such. In addition, all source
code is freely available under the GPL. Because of that, it is very easy
for people to add new protocols to Wireshark, either as plugins, or built
into the source, and they often do!
You are welcome to
modify Wireshark to suit your own needs, and it would be appreciated
if you contribute your improvements back to the Wireshark team.
You gain three benefits by contributing your improvements back to the
community:
Other people who find your contributions useful will appreciate
them, and you will know that you have helped people in the
same way that the developers of Wireshark have helped people.
The developers of Wireshark might improve your changes even more,
as there's always room for improvements. Or they may implement some
advanced things on top of your code, which can be useful for yourself
too.
The maintainers and developers of Wireshark will maintain your
code as well, fixing it when API changes or other changes are
made, and generally keeping it in tune with what is happening
with Wireshark. So if Wireshark is updated (which is done often),
you can get a new Wireshark version from the website and your changes
will already be included without any effort for you.
The Wireshark source code and binary kits for some platforms are all
available on the download page of the Wireshark website:
&WiresharkDownloadPage;.
Releases and distributions
The officially released files can be found at: . A new Wireshark version is released after
significant changes compared to the last release are completed or a
serious security issue is encountered. The typical release schedule is
about every 4-8 weeks (although this may vary).
There are two kinds of distributions: binary and source; both have their
advantages and disadvantages.
Binary distributions
Binary distributions are usually easy to install (as simply starting
the appropriate file is usually the only thing to do). They are available
for the following systems:
Win32 (.exe file). The typical Windows end user method is used to get a setup.exe
file which will install all the required things for him.
Win32 U3 (.u3 file). Special distribution for U3 capable USB memory sticks.
Debian (.deb file). A user of a Debian Package Manager (DPKG) based system
obtains a .deb file from which the package manager checks the
dependencies and installs the software.
Red Hat (.rpm file). A user of a Red Hat Package Manager (RPM) based system
obtains an .rpm file from which the package manager checks the
dependencies and installs the software.
Solaris. A Solaris user obtains a file from which the package manager
(PKG) checks the dependencies and installs the software.
However, if you want to start developing with Wireshark, the binary
distributions won't be too helpful, as you need the source files, of
course.
For details about how to build these binary distributions yourself,
e.g. if you need a distribution for a special audience, see
.
Source code distributions
It's still common for UNIX developers to give the end user a source
tarball and let the user compile it on their target machine (configure,
make, make install). However, for different UNIX (Linux) distributions
it's becoming more common to release binary packages (e.g. .deb or .rpm
files) these days.
You should use the released sources if you want to build Wireshark from
source on your platform for productive use. However, if you going to
develop changes to the Wireshark sources, it might be better to use the
latest SVN sources. For details about the different ways to get the
Wireshark source code see .
Before building Wireshark from a source distribution, make sure you have
all the tools and libraries required to build. The following chapters will
describe the required tools and libraries in detail.
Automated Builds (Buildbot)
The Wireshark Buildbot automatically rebuilds Wireshark on every
change of the source code repository and indicates problematic changes.
This frees the developers from repeating (and annoying) work, so time can
be spent on more interesting tasks.
Advantages
Recognizing (cross platform) build problems - early. Compilation problems
can be narrowed down to a few commits, making a fix much easier.
"Health status" overview of the sources. A quick look at: gives a good "feeling" if
the sources are currently "well".
On the other hand, if all is "red", an update of a personal source tree
might better be done later ...
"Up to date" binary packages are available.
After a change was committed to the repository, a binary package /
installer is usually available within a few hours at: .
This can be quite helpful, e.g. a bug reporter can easily verify a bugfix
by installing a recent build.
Automated regression tests. In particular, the fuzz tests often indicate
"real life" problems that are otherwise hard to find.
What does the Buildbot do?
The Buildbot will do the following (to a different degree on the different
platforms):
checkout from the source repository
build
create binary package(s) / installer
create source package (and check completeness)
run regression tests
Each step is represented at the status page by a rectangle, green if it
succeeded or red if it failed. Most steps provide a link to the corresponding
console logfile, to get additional information.
The Buildbot runs on a platform collection that represents the different
"platform specialties" quite well:
Windows XP x86 (Win32, little endian, MSVC)
Ubuntu x86 (Linux, little endian, gcc)
Solaris SPARC (Solaris, big endian, gcc)
Mac OS-X PPC (BSD, big endian, gcc)
Each platform is represented at the status page by a single column, the
most recent entries are at the top.
Reporting problems and getting help
If you have problems, or need help with Wireshark, there are several
places that may be of interest to you (well, beside this guide of
course).
Website
You will find lot's of useful information on the Wireshark homepage at
&WiresharkWebSite;.
Wiki
The Wireshark Wiki at &WiresharkWikiSite; provides a wide range
of information related to Wireshark and packet capturing in general.
You will find a lot of information not part of this developer's guide. For
example, there is an explanation how to capture on a switched network,
an ongoing effort to build a protocol reference and a lot more.
And best of all, if you would like to contribute your knowledge on a
specific topic (maybe a network protocol you know well), you can edit the
wiki pages by simply using your webbrowser.
FAQ
The "Frequently Asked Questions" will list often asked questions and
the corresponding answers.
Read the FAQ!
Before sending any mail to the mailing lists below, be sure to read the
FAQ, as it will often answer the question(s) you might have. This will save
yourself and others a lot of time (keep in mind that a lot of people are
subscribed to the mailing lists).
You will find the FAQ inside Wireshark by clicking the menu item
Help/Contents and selecting the FAQ page in the upcoming dialog.
An online version is available at the Wireshark website:
&WiresharkFAQPage;. You might
prefer this online version, as it's typically more up to date and the HTML
format is easier to use.
Other sources
If you don't find the information you need inside this book, there are
various other sources of information:
the file doc/README.developer and
all the other README.xxx files in the source code - these are various
documentation files on different topics
the Wireshark source code
tool documentation of the various tools used
(e.g. manpages of sed, gcc, ...)
the different mailing lists: see
...
Mailing Lists
There are several mailing lists available on specific Wireshark topics:
wireshark-announce
This mailing list will inform you about new program
releases, which usually appear about every 4-8 weeks.
wireshark-users
This list is for users of Wireshark. People post
questions about building and using Wireshark, others (hopefully)
provide answers.
wireshark-dev
This list is for Wireshark developers. People post questions about
the development of Wireshark, others (hopefully) provide answers.
If you want to start developing a protocol dissector, join this list.
wireshark-bugs
This list is for Wireshark developers. Everytime a change to the bug
database occurs, a mail to this mailing list is generated.
If you want to be notified about all the changes to the bug
database, join this list. Details about the bug database can be
found in .
wireshark-commits
This list is for Wireshark developers. Everytime a change to the SVN
repository is checked in, a mail to this mailing list is generated.
If you want to be notified about all the changes to the SVN
repository, join this list. Details about the SVN repository can be
found in .
You can subscribe to each of these lists from the Wireshark web site:
&WiresharkWebSite;. Simply
select the mailing lists link on the left hand
side of the site. The lists are archived at the Wireshark web site
as well.
Tip!
You can search in the list archives to see if someone previously asked the same
question and maybe already got an answer. That way you
don't have to wait until someone answers your question.
Bug database (Bugzilla)
The Wireshark community collects bug reports in a Bugzilla database at
&WiresharkBugsSite;.
This database is filled with manually filed bug reports, usually after some
discussion on wireshark-dev, and bug reports from the QA build tools.
Reporting Problems
Note!
Before reporting any problems, please make sure you have installed the
latest version of Wireshark.
If you report problems, provide as much
information as possible. In general, just think about what
you would need to find that problem, if someone else sends you such a
problem report. Also keep in mind that people compile/run Wireshark on a lot of different
platforms.
When reporting problems with Wireshark, it is helpful if you supply the
following information:
The version number of Wireshark and the dependent libraries linked with
it, e.g. GTK+, etc. You can obtain this with the command
wireshark -v.
Information about the platform you run Wireshark on.
A detailed description of your problem.
If you get an error/warning message, copy the text of that message (and
also a few lines before and after it, if there are some), so others may
find the build step where things go wrong.
Please don't give something like: "I get a warning when compiling x"
as this won't give any direction to look at.
Don't send large files!
Do not send large files (>100KB) to the mailing lists, just place a note
that further data is available on request. Large files will only annoy a
lot of people on the list who are not interested in your specific problem.
If required, you will be asked for further data by the persons who really
can help you.
Don't send confidential information!
If you send captured data to the mailing lists, or add it to your bug report,
be sure it doesn't contain any sensitive or confidential information,
such as passwords.
Reporting Crashes on UNIX/Linux platforms
When reporting crashes with Wireshark, it is helpful if you supply the
traceback information (besides the information mentioned in
).
You can obtain this traceback information with the following commands:
& bt.txt
backtrace
^D
$
]]>
Type the characters in the first line verbatim! Those are
back-tics there!
backtrace is a gdb command. You should
enter it verbatim after the first line shown above, but it will not be
echoed. The ^D
(Control-D, that is, press the Control key and the D key
together) will cause gdb to exit. This will
leave you with a file called
bt.txt in the current directory.
Include the file with your bug report.
If you do not have gdb available, you
will have to check out your operating system's debugger.
You should mail the traceback to the
&WiresharkDevMailList;
mailing list, or append it to your bug report.
Reporting Crashes on Windows platforms
The Windows distributions don't contain the symbol files (.pdb), because
they are very large. For this reason it's not possible to create
a meaningful backtrace file from it. You should report your crash just
like other problems, using the mechanism from
.