$Id$

1. Plugins

Writing a "plugin" dissector is not very different from writing a standard
one.  In fact all of the functions described in README.developer can be 
used in the plugins exactly as they are used in standard dissectors.

(Note, however, that not all OSes on which Wireshark runs can support
plugins.)

If you've chosen "foo" as the name of your plugin (typically, that would
be a short name for your protocol, in all lower case), the following
instructions tell you how to implement it as a plugin.  All occurrences
of "foo" below should be replaced by the name of your plugin.

2. The directory for the plugin, and its files

The plugin should be placed in a new plugins/foo directory which should
contain at least the following files:

AUTHORS
COPYING
ChangeLog
CMakeLists.txt
Makefile.am
Makefile.common
Makefile.nmake
moduleinfo.h
moduleinfo.nmake
plugin.rc.in
And of course the source and header files for your dissector.

Examples of these files can be found in plugins/gryphon.

2.1 AUTHORS, COPYING, and ChangeLog

The AUTHORS, COPYING, and ChangeLog are the standard sort of GPL project
files.

2.2 CMakeLists.txt

For your plugins/foo/CMakeLists.txt file, see the corresponding file in
plugins/gryphon.  Replace all occurrences of "gryphon" in those files
with "foo" and add your source files to the DISSECTOR_SRC variable.

2.3 Makefile.am

For your plugins/foo/Makefile.am file, see the corresponding file in
plugins/gryphon.  Replace all occurrences of "gryphon" in those files
with "foo".

2.4 Makefile.common

Your plugins/foo/Makefile.common should only list the main source file(s),
which exports register_*() and handoff_*(), for your dissector in the
DISSECTOR_SRC variable.  All other supporting source files should be 
listed in the DISSECTOR_SUPPORT_SRC variable.
The header files for your dissector, if any, must be listed in the
DISSECTOR_INCLUDES variable.  The DISSECTOR_INCLUDES variable should not
include moduleinfo.h.

2.5 Makefile.nmake

For your plugins/foo/Makefile.nmake file, see the corresponding file in
plugins/gryphon.  No modifications are needed here.

2.6 moduleinfo.h

Your plugins/foo/moduleinfo.h file is used to set the version information
for the plugin.

2.7 moduleinfo.nmake

Your plugins/foo/moduleinfo.nmake is used to set the version information
for building the plugin.  Its contents should match that in moduleinfo.h

2.8 plugin.rc.in

Your plugins/foo/plugin.rc.in is the Windows resource template file used 
to add the plugin specific information as resources to the DLL.
No modifications are needed here.

3. Changes to existing Wireshark files

There are two ways to add your plugin dissector to the build, as a custom
extension or as a permanent addition.  The custom extension is easy to 
configure, but won't be used for inclusion in the distribution if that's 
your goal.  Setting up the permanent addition is somewhat more involved.

3.1 Custom extension

Go to the plugins directory and copy the three Custom.*.example files to 
Custom.*.  Now you have three files ready for building a plugin with the 
name "foo".  Replace the name if you so require.

If you want to add the plugin to your own Windows installer add a text 
file named custom_plugins.txt to the packaging/nsis directory, with a 
"File" statement for NSIS:

File "..\..\plugins\foo\foo.dll"

Then open packaging/nsis/Custom.nmake and add the relative path to your 
DLL to CUSTOM_PLUGINS:

CUSTOM_PLUGINS= \
	../../plugins/foo/foo.dll

3.2 Permanent addition

In order to be able to permanently add a plugin take the following steps.
You will need to change the following files:
	configure.ac
	CMakeLists.txt
	epan/Makefile.am
	Makefile.am
	packaging/nsis/Makefile.nmake
	packaging/nsis/wireshark.nsi
	plugins/Makefile.am
	plugins/Makefile.nmake

You might also want to search your Wireshark development directory for
occurrences of an existing plugin name, in case this document is out of
date with the current directory structure.  For example,

	grep -rl gryphon .

could be used from a shell prompt.

3.2.1  Changes to plugins/Makefile.am

The plugins directory contains a Makefile.am.  You need to add to SUBDIRS
(in alphabetical order) the name of your plugin:

SUBDIRS = $(_CUSTOM_SUBDIRS_) \
	...
	ethercat \
	foo \
	gryphon \
	irda \


3.2.2 Changes to plugins/Makefile.nmake

In plugins/Makefile.nmake you need to add to PLUGINS_LIST (in alphabetical
order) the name of your plugin:

PLUGIN_LIST = \
	...
	ethercat    \
	foo         \
	gryphon     \
	irda        \

3.2.3 Changes to the top level Makefile.am

Add your plugin (in alphabetical order) to plugin_ldadd:

if HAVE_PLUGINS

plugin_ldadd = $(_CUSTOM_plugin_ldadd_) \
	...
	-dlopen plugins/ethercat/ethercat.la \
	-dlopen plugins/foo/foo.la \
	-dlopen plugins/gryphon/gryphon.la \
	-dlopen plugins/irda/irda.la \
	...

3.2.4  Changes to the top level configure.ac

You need to add your plugins Makefile (in alphbetical order) to the 
AC_OUTPUT rule in the configure.ac

AC_OUTPUT(
  ...
  plugins/ethercat/Makefile
  plugins/foo/Makefile
  plugins/gryphon/Makefile
  plugins/irda/Makefile
  ...
  ,)

3.2.5  Changes to epan/Makefile.am

Add the relative path of all your plugin source files (in alphbetical 
order) to plugin_src:

plugin_src = \
        ...
	../plugins/ethercat/packet-ioraw.c \
	../plugins/ethercat/packet-nv.c \
	../plugins/foo/packet-foo.c \
	../plugins/gryphon/packet-gryphon.c \
	../plugins/irda/packet-ircomm.c \
	../plugins/irda/packet-irda.c \
        ...

3.2.6  Changes to CMakeLists.txt

Add your plugin (in alphabetical order) to the PLUGIN_SRC_DIRS:

if(ENABLE_PLUGINS)
        ...
        set(PLUGIN_SRC_DIRS
                ...
                plugins/ethercat
                plugins/foo
                plugins/gryphon
                plugins/irda
                ...

3.2.7  Changes to the installers

If you want to include your plugin in an installer you have to add lines
in the NSIS installer Makefile.nmake and wireshark.nsi files.

3.2.7.1  Changes to packaging/nsis/Makefile.nmake

Add the relative path of your plugin DLL (in alphbetical order) to PLUGINS:

PLUGINS= \
	...
	../../plugins/ethercat/ethercat.dll \
	../../plugins/foo/foo.dll \
	../../plugins/gryphon/gryphon.dll \
	../../plugins/irda/irda.dll \

3.2.7.2  Changes to packaging/nsis/wireshark.nsi

Add the relative path of your plugin DLL (in alphbetical order) to the 
list of "File" statements in the "Dissector Plugins" section:

File "${STAGING_DIR}\plugins\${VERSION}\ethercat.dll"
File "${STAGING_DIR}\plugins\${VERSION}\foo.dll"
File "${STAGING_DIR}\plugins\${VERSION}\gryphon.dll"
File "${STAGING_DIR}\plugins\${VERSION}\irda.dll"

3.2.7.3  Other installers

The U3 and PortableApps installers build their manifests, including 
plugins, from wireshark.nsi via the packaging/ws-manifest.pl script.

4. Development and plugins on Unix

Plugins make some aspects of development easier and some harder.

The first thing is that you'll have to run autogen.sh and configure once
more to setup your build environment.

The good news is that if you are working on a single plugin then you will
find recompiling the plugin MUCH faster than recompiling a dissector and 
then linking it back into Wireshark. Use "make -C plugins" to compile just
your plugins.

The bad news is that Wireshark will not use the plugins unless the plugins
are installed in one of the places it expects them to find.

One way of dealing with this problem is to set an environment variable
when running Wireshark: WIRESHARK_RUN_FROM_BUILD_DIRECTORY=1.

Another way to deal with this problem is to set up a working root for
wireshark, say in $HOME/build/root and build wireshark to install
there

./configure --prefix=${HOME}/build/root && make install

then subsequent rebuilds/installs of your plugin can be accomplished
by going to the plugins/foo directory and running

make install

5. Update "old style" plugins

5.1 How to update an "old style" plugin (using plugin_register and
    plugin_reg_handoff functions).

The plugin registration has changed with the extension of the build
scripts. These now generate the additional code needed for plugin
encapsulation in plugin.c. When using the new style build scripts,
stips the parts outlined below:

    o Remove the following include statements:

        #include <gmodule.h>
        #include "moduleinfo.h"

    o Removed the definition:

        #ifndef ENABLE_STATIC
        WS_DLL_PUBLIC_DEF gchar version[] = VERSION;
        #endif

    o Move relevant code from the blocks and delete these functions:

        #ifndef ENABLE_STATIC
        plugin_reg_handoff()
        ....
        #endif

        #ifndef ENABLE_STATIC
        plugin_register()
        ....
        #endif

This will leave a clean dissector source file without plugin specifics.

5.2 How to update an "old style" plugin (using plugin_init function)

The plugin registering has changed between 0.10.9 and 0.10.10; everyone
is encouraged to update their plugins as outlined below:

    o Remove following include statements from all plugin sources:

	#include "plugins/plugin_api.h"
	#include "plugins/plugin_api_defs.h"

    o Remove the init function.

    o Add a new Makefile.common file with the lists of source files and
      headers.

    o Change the Makefile.am and Makefile.nmake files to match those of
      the DOCSIS plugin.

----------------

Ed Warnicke <hagbard@physics.rutgers.edu>
Guy Harris <guy@alum.mit.edu>

Derived and expanded from the plugin section of README.developers
which was originally written by

James Coe <jammer@cin.net>
Gilbert Ramirez <gram@alumni.rice.edu>
Jeff Foster <jfoste@woodward.com>
Olivier Abad <oabad@cybercable.fr>
Laurent Deniel <laurent.deniel@free.fr>
Jaap Keuter <jaap.keuter@xs4all.nl>
