path: root/epan/dissectors/packet-rmt-alc.c

/* packet-rmt-alc.c
 * Reliable Multicast Transport (RMT)
 * ALC Protocol Instantiation dissector
 * Copyright 2005, Stefano Pettini <spettini@users.sourceforge.net>
 *
 * Asynchronous Layered Coding (ALC):
 * ----------------------------------
 *
 * A massively scalable reliable content delivery protocol.
 * Asynchronous Layered Coding combines the Layered Coding Transport
 * (LCT) building block, a multiple rate congestion control building
 * block and the Forward Error Correction (FEC) building block to
 * provide congestion controlled reliable asynchronous delivery of
 * content to an unlimited number of concurrent receivers from a single
 * sender.
 *
 * References:
 *     RFC 3450, Asynchronous Layered Coding protocol instantiation
 *
 * $Id$
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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 <string.h>

#include <glib.h>

#include <epan/packet.h>
#include <epan/prefs.h>

#include "packet-rmt-alc.h"

/* Initialize the protocol and registered fields */
/* ============================================= */

static int proto = -1;

static struct _alc_hf hf;
static struct _alc_ett ett;

static struct _alc_prefs preferences;
static dissector_handle_t xml_handle;


/* Preferences */
/* =========== */

/* Set/Reset preferences to default values */
static void alc_prefs_set_default(struct _alc_prefs *alc_prefs)
{
	alc_prefs->use_default_udp_port = FALSE;
	alc_prefs->default_udp_port = 4001;

	lct_prefs_set_default(&alc_prefs->lct);
	fec_prefs_set_default(&alc_prefs->fec);
}

/* Register preferences */
static void alc_prefs_register(struct _alc_prefs *alc_prefs, module_t *module)
{
	prefs_register_bool_preference(module,
		"default.udp_port.enabled",
		"Use default UDP port",
		"Whether that payload of UDP packets with a specific destination port should be automatically dissected as ALC packets",
		 &alc_prefs->use_default_udp_port);

 	prefs_register_uint_preference(module,
		"default.udp_port",
		"Default UDP destination port",
		"Specifies the UDP destination port for automatic dissection of ALC packets",
		 10, &alc_prefs->default_udp_port);

	lct_prefs_register(&alc_prefs->lct, module);
	fec_prefs_register(&alc_prefs->fec, module);
}

/* Save preferences to alc_prefs_old */
static void alc_prefs_save(struct _alc_prefs *p, struct _alc_prefs *p_old)
{
	*p_old = *p;
}

/* Code to actually dissect the packets */
/* ==================================== */

static void dissect_alc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
	/* Logical packet representation */
	struct _alc alc;

	/* Offset for subpacket dissection */
	guint offset;

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

	/* Flute or not */
	tvbuff_t *new_tvb;
	gboolean is_flute = FALSE;

	/* Structures and variables initialization */
	offset = 0;
	memset(&alc, 0, sizeof(struct _alc));

	/* Update packet info */
	pinfo->current_proto = "ALC";

	/* Make entries in Protocol column and Info column on summary display */
	col_set_str(pinfo->cinfo, COL_PROTOCOL, "ALC");
	col_clear(pinfo->cinfo, COL_INFO);

	/* ALC header dissection */
	/* --------------------- */

	alc.version = hi_nibble(tvb_get_guint8(tvb, offset));

	if (tree)
	{
		/* Create subtree for the ALC protocol */
		ti = proto_tree_add_item(tree, proto, tvb, offset, -1, ENC_NA);
		alc_tree = proto_item_add_subtree(ti, ett.main);

		/* Fill the ALC subtree */
		proto_tree_add_uint(alc_tree, hf.version, tvb, offset, 1, alc.version);

	} else
		alc_tree = NULL;

	/* This dissector supports only ALCv1 packets.
	 * If alc.version > 1 print only version field and quit.
	 */
	if (alc.version == 1) {

		struct _lct_ptr l;
		struct _fec_ptr f;

		l.lct = &alc.lct;
		l.hf = &hf.lct;
		l.ett = &ett.lct;
		l.prefs = &preferences.lct;

		f.fec = &alc.fec;
		f.hf = &hf.fec;
		f.ett = &ett.fec;
		f.prefs = &preferences.fec;

		/* LCT header dissection */
		/* --------------------- */

		is_flute = lct_dissector(l, f, tvb, alc_tree, &offset);

		/* FEC header dissection */
		/* --------------------- */

		/* Only if it's present and if LCT dissector has determined FEC Encoding ID
		 * FEC dissector should be called with fec->encoding_id* and fec->instance_id* filled
		 */
		if (alc.fec.encoding_id_present && tvb_length(tvb) > offset)
			fec_dissector(f, tvb, alc_tree, &offset);

		/* Add the Payload item */
		if (tvb_length(tvb) > offset){
			if(is_flute){
				new_tvb = tvb_new_subset_remaining(tvb,offset);
				call_dissector(xml_handle, new_tvb, pinfo, alc_tree);
			}else{
				proto_tree_add_none_format(alc_tree, hf.payload, tvb, offset, -1, "Payload (%u bytes)", tvb_length(tvb) - offset);
			}
		}

		/* Complete entry in Info column on summary display */
		/* ------------------------------------------------ */

		if (check_col(pinfo->cinfo, COL_INFO))
		{
			lct_info_column(&alc.lct, pinfo);
			fec_info_column(&alc.fec, pinfo);
		}

		/* Free g_allocated memory */
		lct_dissector_free(&alc.lct);
		fec_dissector_free(&alc.fec);

	} else {

		if (tree)
			proto_tree_add_text(alc_tree, tvb, 0, -1, "Sorry, this dissector supports ALC version 1 only");

		/* Complete entry in Info column on summary display */
		if (check_col(pinfo->cinfo, COL_INFO))
			col_add_fstr(pinfo->cinfo, COL_INFO, "Version: %u (not supported)", alc.version);
	}
}

void proto_reg_handoff_alc(void)
{
	static dissector_handle_t handle;
	static gboolean preferences_initialized = FALSE;
	static struct _alc_prefs preferences_old;

	if (!preferences_initialized)
	{
		preferences_initialized = TRUE;
		handle = create_dissector_handle(dissect_alc, proto);
		dissector_add_handle("udp.port", handle);
		xml_handle = find_dissector("xml");

	} else {

		if (preferences_old.use_default_udp_port)
			dissector_delete_uint("udp.port", preferences_old.default_udp_port, handle);
	}

	if (preferences.use_default_udp_port)
		dissector_add_uint("udp.port", preferences.default_udp_port, handle);

	alc_prefs_save(&preferences, &preferences_old);

}

void proto_register_alc(void)
{
	/* Setup ALC header fields */
	static hf_register_info hf_ptr[] = {

		{ &hf.version,
			{ "Version", "alc.version", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

		LCT_FIELD_ARRAY(hf.lct, "alc"),
		FEC_FIELD_ARRAY(hf.fec, "alc"),

		{ &hf.payload,
			{ "Payload", "alc.payload", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }}
	};

	/* Setup protocol subtree array */
	static gint *ett_ptr[] = {
		&ett.main,

		LCT_SUBTREE_ARRAY(ett.lct),
		FEC_SUBTREE_ARRAY(ett.fec)
	};

	module_t *module;

	/* Clear hf and ett fields */
	memset(&hf, 0xff, sizeof(struct _alc_hf));
	memset(&ett, 0xff, sizeof(struct _alc_ett));

	/* Register the protocol name and description */
	proto = proto_register_protocol("Asynchronous Layered Coding", "ALC", "alc");

	/* Register the header fields and subtrees used */
	proto_register_field_array(proto, hf_ptr, array_length(hf_ptr));
	proto_register_subtree_array(ett_ptr, array_length(ett_ptr));

	/* Reset preferences */
	alc_prefs_set_default(&preferences);

	/* Register preferences */
	module = prefs_register_protocol(proto, proto_reg_handoff_alc);
	alc_prefs_register(&preferences, module);

	register_dissector("alc", dissect_alc, proto);
}