$Id: README.idl2eth 11400 2004-07-18 00:24:25Z guy $

Copyright (C) 2001 Frank Singleton <frank.singleton@ericsson.com>


What is it ?
============

As you have probably guessed from the name, "idl2eth" takes a
user specified IDL file and attempts to build a dissector that
can decode the IDL traffic over GIOP. The resulting file is
"C" code, that should compile okay as an ethereal dissector.

idl2eth basically parses the data struct given to it by
the omniidl compiler, and using the GIOP API available in packet-giop.[ch],
generates  get_CDR_xxx calls to decode the CORBA traffic on the wire.

It consists of 4 main files.

README.idl2eth     - This document
ethereal_be.py     - The main compiler backend
ethereal_gen.py    - A helper class, that generates the C code.
idl2eth            - A simple shell script wrapper that the end user should
                     use to generate the dissector from the IDL file(s).

Why did you do this ?
=====================

It is important to understand how CORBA traffic looks
like over GIOP/IIOP, and to help build a tool that can assist
in troubleshooting CORBA interworking. This was especially the
case after seeing a lot of discussions about how particular
IDL types are represented inside an octet stream.

I have also had comments/feedback that this tool would be good for say
a CORBA class when teaching students how CORBA traffic looks like
"on the wire".

It is also COOL to work on a great Open Source project such as
the case with "Ethereal" (http://www.ethereal.com)


How to use idl2eth
==================

To use the idl2eth to generate ethereal dissectors, you
need the following.


1. Python must be installed
   http://python.org/

2. omniidl from the the omniORB package must be available.
   http://omniorb.sourceforge.net/

3  Of course you need ethereal installed to compile the
   code an tweak it if required. idl2eth is part of the 
   standard Ethereal distribution


Procedure
=========

1.  To write the C code to stdout.  

    idl2eth  <your file.idl>

    eg: idl2eth echo.idl


2. To write to a file, just redirect the output.

    idl2eth echo.idl > packet-test-idl.c

   You may wish to comment out the register_giop_user_module() code
   and that will leave you with heuristic dissection.


If you dont want to use the shell script wrapper, then try
steps 3 or 4 instead.

3.  To write the C code to stdout.  

    Usage: omniidl  -p ./ -b ethereal_be <your file.idl>

    eg: omniidl  -p ./ -b ethereal_be echo.idl


4. To write to a file, just redirect the output.

    omniidl  -p ./ -b ethereal_be echo.idl > packet-test-idl.c

   You may wish to comment out the register_giop_user_module() code
   and that will leave you with heuristic dissection.


5. Copy the resulting C code to your ethereal src directory, edit the 2 make files
   to include the packet-test-idl.c
 
   cp packet-test-idl.c /dir/where/ethereal/lives/
   edit Makefile.am
   edit Makefile.nmake

6. Run configure

   ./configure (or ./autogen.sh)

7. Compile the code

   make

8. Good Luck !!


TODO
====

1. Exception code not generated  (yet), but can be added manually.
2. Enums not converted to symbolic values (yet), but can be added manually.
3. Add command line options etc
4. More I am sure :-)


Limitations
===========

See TODO list inside packet-giop.c


Notes
=====

1. The "-p ./" option passed to omniidl indicates that the ethereal_be.py
   and ethereal_gen.py are residing in the current directory. This may need
   tweaking if you place these files somewhere else.

2. If it complains about being unable to find some modules (eg tempfile.py), 
   you may want to check if PYTHONPATH is set correctly.
   On my Linux box, it is  PYTHONPATH=/usr/lib/python1.5/ 

Frank Singleton.

