[Nina Pham <nina@xxxxxxxxxxx>]

attachment is the file which creates new dissector. I just cut and 
pasted from readme.developer, change some variables reccomanded from 
part 1.3 of readme.developer. I changed ID_VALUE to 771 with the hope to 
display my protocol when data is sent through port 771. It build 
sucessfully. However, when I ran ethereal, send data through port 771 ( 
with both way, tcp and udp). The ethereal I just build display packets 
just like it usually does for tcp and udp packet. It doesn't show what 
I'm expecting. Please take a look at my file and tell me what I did 
wrong. Thanks

NN

/* packet-PROTOABBREV.c
 * Routines for PROTONAME dissection
 * Copyright 2000, YOUR_NAME <YOUR_EMAIL_ADDRESS>
 *
 * $Id: README.developer 12300 2004-10-14 23:45:09Z guy $
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@xxxxxxxxxxxx>
 * Copyright 1998 Gerald Combs
 *
 * Copied from WHATEVER_FILE_YOU_USED (where "WHATEVER_FILE_YOU_USED"
 * is a dissector file; if you just copied this from README.developer,
 * don't bother with the "Copied from" - you don't even need to put
 * in a "Copied from" if you copied an existing dissector, especially
 * if the bulk of the code in the new dissector is your code)
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <glib.h>

#include <epan/packet.h>

/* IF PROTO exposes code to other dissectors, then it must be exported
   in a header file. If not, a header file is not needed at all. */
/*#include "packet-PROTOABBREV.h" */

/* Initialize the protocol and registered fields */
static int proto_PROTOABBREV = -1;
static int hf_PROTOABBREV_FIELDABBREV = -1;

/* Initialize the subtree pointers */
static gint ett_PROTOABBREV = -1;

/* Code to actually dissect the packets */
static void
dissect_PROTOABBREV(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{

/* Set up structures needed to add the protocol subtree and manage it */
	proto_item *ti;
	proto_tree *PROTOABBREV_tree;

/* Make entries in Protocol column and Info column on summary display */
	if (check_col(pinfo->cinfo, COL_PROTOCOL)) 
		col_set_str(pinfo->cinfo, COL_PROTOCOL, "PROTOABBREV");
    
/* This field shows up as the "Info" column in the display; you should make
   it, if possible, summarize what's in the packet, so that a user looking
   at the list of packets can tell what type of packet it is. See section 1.5
   for more information.

   If you are setting it to a constant string, use "col_set_str()", as
   it's more efficient than the other "col_set_XXX()" calls.

   If you're setting it to a string you've constructed, or will be
   appending to the column later, use "col_add_str()".

   "col_add_fstr()" can be used instead of "col_add_str()"; it takes
   "printf()"-like arguments.  Don't use "col_add_fstr()" with a format
   string of "%s" - just use "col_add_str()" or "col_set_str()", as it's
   more efficient than "col_add_fstr()".

   If you will be fetching any data from the packet before filling in
   the Info column, clear that column first, in case the calls to fetch
   data from the packet throw an exception because they're fetching data
   past the end of the packet, so that the Info column doesn't have data
   left over from the previous dissector; do

	if (check_col(pinfo->cinfo, COL_INFO)) 
		col_clear(pinfo->cinfo, COL_INFO);

   */

	if (check_col(pinfo->cinfo, COL_INFO)) 
		col_set_str(pinfo->cinfo, COL_INFO, "XXX Request");

/* A protocol dissector can be called in 2 different ways:

	(a) Operational dissection

		In this mode, Ethereal is only interested in the way protocols
		interact, protocol conversations are created, packets are reassembled
		and handed over to higher-level protocol dissectors.
		This way Ethereal does not build a so-called "protocol tree".

	(b) Detailed dissection

		In this mode, Ethereal is also interested in all details of a given
		protocol, so a "protocol tree" is created.

   Ethereal distinguishes between the 2 modes with the proto_tree pointer:
	(a) <=> tree == NULL
	(b) <=> tree != NULL

   In the interest of speed, if "tree" is NULL, avoid building a
   protocol tree and adding stuff to it, or even looking at any packet
   data needed only if you're building the protocol tree, if possible.

   Note, however, that you must fill in column information, create
   conversations, reassemble packets, build any other persistent state
   needed for dissection, and call subdissectors regardless of whether
   "tree" is NULL or not.  This might be inconvenient to do without
   doing most of the dissection work; the routines for adding items to
   the protocol tree can be passed a null protocol tree pointer, in
   which case they'll return a null item pointer, and
   "proto_item_add_subtree()" returns a null tree pointer if passed a
   null item pointer, so, if you're careful not to dereference any null
   tree or item pointers, you can accomplish this by doing all the
   dissection work.  This might not be as efficient as skipping that
   work if you're not building a protocol tree, but if the code would
   have a lot of tests whether "tree" is null if you skipped that work,
   you might still be better off just doing all that work regardless of
   whether "tree" is null or not. */
	if (tree) {

/* NOTE: The offset and length values in the call to
   "proto_tree_add_item()" define what data bytes to highlight in the hex
   display window when the line in the protocol tree display
   corresponding to that item is selected.

   Supplying a length of -1 is the way to highlight all data from the
   offset to the end of the packet. */

/* create display subtree for the protocol */
		ti = proto_tree_add_item(tree, proto_PROTOABBREV, tvb, 0, -1, FALSE);

		PROTOABBREV_tree = proto_item_add_subtree(ti, ett_PROTOABBREV);

/* add an item to the subtree, see section 1.6 for more information */
		proto_tree_add_item(PROTOABBREV_tree,
		    hf_PROTOABBREV_FIELDABBREV, tvb, 0, -1, FALSE);


/* Continue adding tree items to process the packet here */


	}

/* If this protocol has a sub-dissector call it here, see section 1.8 */
}


/* Register the protocol with Ethereal */

/* this format is require because a script is used to build the C function
   that calls all the protocol registration.
*/

void
proto_register_PROTOABBREV(void)
{                 

/* Setup list of header fields  See Section 1.6.1 for details*/
	static hf_register_info hf[] = {
		{ &hf_PROTOABBREV_FIELDABBREV,
			{ "FIELD A",           "proto.field_a",
			FT_UINT8, BASE_DEC, NULL, 0x0,          
			"FIELD A", HFILL }
		},
	};

/* Setup protocol subtree array */
	static gint *ett[] = {
		&ett_PROTOABBREV,
	};

/* Register the protocol name and description */
	proto_PROTOABBREV = proto_register_protocol("MYPROT",
	    "MYPROT", "MYPROT");

/* Required function calls to register the header fields and subtrees used */
	proto_register_field_array(proto_PROTOABBREV, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
}


/* If this dissector uses sub-dissector registration add a registration routine.
   This format is required because a script is used to find these routines and
   create the code that calls these routines.
*/
void
proto_reg_handoff_PROTOABBREV(void)
{
	dissector_handle_t PROTOABBREV_handle;

	PROTOABBREV_handle = create_dissector_handle(dissect_PROTOABBREV,
	    proto_PROTOABBREV);
	dissector_add("my.port", 771, PROTOABBREV_handle);
}