wireshark/epan/dissectors/packet-coap.c

#include <stdio.h>
/* packet-coap.c
 * Routines for COAP packet disassembly
 * draft-ietf-core-coap-07.txt
 * draft-ietf-core-block-04.txt
 * draft-ietf-core-observe-02.txt
 * draft-ietf-core-link-format-06.txt
 * Shoichi Sakane <sakane@tanu.org>
 *
 * $Id$
 *
 * 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 <glib.h>

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

static dissector_table_t media_type_dissector_table;

static int proto_coap = -1;

static int hf_coap_version		= -1;
static int hf_coap_ttype		= -1;
static int hf_coap_opt_count		= -1;
static int hf_coap_code			= -1;
static int hf_coap_tid			= -1;
static int hf_coap_opt_delta		= -1;
static int hf_coap_opt_length		= -1;
static int hf_coap_opt_ctype		= -1;
static int hf_coap_opt_max_age		= -1;
static int hf_coap_opt_proxy_uri	= -1;
static int hf_coap_opt_etag		= -1;
static int hf_coap_opt_uri_host 	= -1;
static int hf_coap_opt_location_path	= -1;
static int hf_coap_opt_uri_port		= -1;
static int hf_coap_opt_location_query	= -1;
static int hf_coap_opt_uri_path		= -1;
static int hf_coap_opt_observe		= -1;
static int hf_coap_opt_token		= -1;
static int hf_coap_opt_accept		= -1;
static int hf_coap_opt_if_match		= -1;
static int hf_coap_opt_block_number	= -1;
static int hf_coap_opt_block_mflag	= -1;
static int hf_coap_opt_block_size	= -1;
static int hf_coap_opt_uri_query	= -1;
static int hf_coap_opt_if_none_match	= -1;

static gint ett_coap			= -1;
static gint ett_coap_option		= -1;
static gint ett_coap_payload		= -1;

/* COAP's IANA-assigned port number */
#define DEFAULT_COAP_PORT	5683

static const gchar *coap_content_type = NULL;
static gint coap_content_type_value = ~0;
static guint global_coap_port_number = DEFAULT_COAP_PORT;

static gint block_number = ~0;
static guint block_mflag = 0;
static gchar uri_string[256]; /* 256 is probably enough to display in the screen */

/*
 * Transaction Type
 */
static const value_string vals_ttype[] = {
	{ 0, "Confirmable" },
	{ 1, "Non-Confirmable" },
	{ 2, "Acknowledgement" },
	{ 3, "Reset" },
	{ 0, NULL },
};

/*
 * Method Code
 * Response Code
 */
static const value_string vals_code[] = {
	{ 0, "Empty Message" },

	/* method code */
	{ 1, "GET" },
	{ 2, "POST" },
	{ 3, "PUT" },
	{ 4, "DELETE" },

	/* response code */
	{  65, "2.01 Created" },
	{  66, "2.02 Deleted" },
	{  67, "2.03 Valid" },
	{  68, "2.04 Changed" },
	{  69, "2.05 Content" },
	{ 128, "4.00 Bad Request" },
	{ 129, "4.01 Unauthorized" },
	{ 130, "4.02 Bad Option" },
	{ 131, "4.03 Forbidden" },
	{ 132, "4.04 Not Found" },
	{ 133, "4.05 Method Not Allowed" },
	{ 136, "4.08 Request Entity Incomplete" },	/* core-block-03 */
	{ 140, "4.12 Precondition Failed" },
	{ 141, "4.13 Request Entity Too Large" },
	{ 143, "4.15 Unsupported Media Type" },
	{ 160, "5.00 Internal Server Error" },
	{ 161, "5.01 Not Implemented" },
	{ 162, "5.02 Bad Gateway" },
	{ 163, "5.03 Service Unavailable" },
	{ 164, "5.04 Gateway Timeout" },
	{ 165, "5.05 Proxying Not Supported" },

	{ 0, NULL },
};

/*
 * Option Headers
 * No-Option must not be included in this structure, is handled in the function
 * of the dissector, especially.
 */
#define COAP_OPT_CONTENT_TYPE	1
#define COAP_OPT_MAX_AGE	2
#define COAP_OPT_PROXY_URI	3
#define COAP_OPT_ETAG		4
#define COAP_OPT_URI_HOST	5
#define COAP_OPT_LOCATION_PATH	6
#define COAP_OPT_URI_PORT	7
#define COAP_OPT_LOCATION_QUERY	8
#define COAP_OPT_URI_PATH	9
#define COAP_OPT_OBSERVE	10	/* core-observe */
#define COAP_OPT_TOKEN		11
#define COAP_OPT_ACCEPT		12
#define COAP_OPT_IF_MATCH	13
#define COAP_OPT_URI_QUERY	15
#define COAP_OPT_BLOCK2		17	/* core-block-03 */
#define COAP_OPT_BLOCK1		19	/* core-block-03 */
#define COAP_OPT_IF_NONE_MATCH	21

static const value_string vals_opt_type[] = {
	{ COAP_OPT_CONTENT_TYPE, "Content-Type" },
	{ COAP_OPT_MAX_AGE, "Max-age" },
	{ COAP_OPT_PROXY_URI, "Proxy-Uri" },
	{ COAP_OPT_ETAG, "Etag" },
	{ COAP_OPT_URI_HOST, "Uri-Host" },
	{ COAP_OPT_LOCATION_PATH, "Location-Path" },
	{ COAP_OPT_URI_PORT, "Uri-Port" },
	{ COAP_OPT_LOCATION_QUERY, "Location-Query" },
	{ COAP_OPT_URI_PATH, "Uri-Path" },
	{ COAP_OPT_OBSERVE, "Observe" },
	{ COAP_OPT_TOKEN, "Token" },
	{ COAP_OPT_ACCEPT, "Accept" },
	{ COAP_OPT_IF_MATCH, "If-Match" },
	{ COAP_OPT_URI_QUERY, "Uri-Query" },
	{ COAP_OPT_BLOCK2, "Block2" },
	{ COAP_OPT_BLOCK1, "Block1" },
	{ COAP_OPT_IF_NONE_MATCH, "If-None-Match" },
	{ 0, NULL },
};

static const value_string vals_ctype[] = {
	{ 0, "text/plain" },
	{ 40, "application/link-format" },
	{ 41, "application/xml" },
	{ 42, "application/octet-stream" },
	{ 47, "application/exi" },
	{ 50, "application/json" },
	{ 0, NULL },
};

void proto_reg_handoff_coap(void);

static int
coap_is_str_ipv6addr(guint8 *str)
{
	size_t len = strlen(str);
	int colon = 0;

	while (len--) {
		if (*str++ == ':')
			colon++;
	}

	return colon > 1 ? 1 : 0;
}

static void
dissect_coap_opt_string(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *subtree, gint offset, gint opt_length, int hfindex, int opt_code)
{
	guint8 *hoststr = NULL;

	proto_tree_add_item(subtree, hfindex, tvb, offset, opt_length, FALSE);

	/* forming a uri-string */
	switch (opt_code) {
	case COAP_OPT_URI_HOST:
		g_strlcat(uri_string, "coap://", sizeof(uri_string));
		hoststr = tvb_get_ephemeral_string(tvb, offset, opt_length);
		/* if the string looks an IPv6 address, it has to be enclosed by brackets. */
		if (coap_is_str_ipv6addr(hoststr)) {
			g_strlcat(uri_string, "[", sizeof(uri_string));
			g_strlcat(uri_string, hoststr, sizeof(uri_string));
			g_strlcat(uri_string, "]", sizeof(uri_string));
		} else
			g_strlcat(uri_string, hoststr, sizeof(uri_string));
		break;
	case COAP_OPT_URI_PATH:
		g_strlcat(uri_string, "/", sizeof(uri_string));
		g_strlcat(uri_string, tvb_get_ephemeral_string(tvb, offset, opt_length), sizeof(uri_string));
		break;
	case COAP_OPT_URI_QUERY:
		g_strlcat(uri_string, "/?", sizeof(uri_string));
		g_strlcat(uri_string, tvb_get_ephemeral_string(tvb, offset, opt_length), sizeof(uri_string));
		break;
	}
}

static void
dissect_coap_opt_ctype(tvbuff_t *tvb, packet_info *pinfo, proto_tree *subtree, gint offset, gint opt_length, int hfindex)
{
	guint32 opt_ctype = 0;

	if (opt_length != 1) {
		expert_add_info_format(pinfo, subtree, PI_MALFORMED, PI_WARN, "Invalid Option Length: %d", opt_length);
		return;
	}

	opt_ctype = tvb_get_guint8(tvb, offset);
	coap_content_type_value = (gint)opt_ctype;
	coap_content_type = val_to_str(opt_ctype, vals_ctype, "Unknown %d");

	proto_tree_add_item(subtree, hfindex, tvb, offset, 1, FALSE);
}

static void
dissect_coap_opt_time(tvbuff_t *tvb, packet_info *pinfo, proto_tree *subtree, gint offset, gint opt_length, int hfindex)
{
	proto_item *item = NULL;

	if (opt_length <= 0 || opt_length > 4) {
		expert_add_info_format(pinfo, subtree, PI_MALFORMED, PI_WARN, "Invalid Option Length: %d", opt_length);
		return;
	}

	item = proto_tree_add_item(subtree, hfindex, tvb, offset, opt_length, FALSE);
	proto_item_append_text(item, " (s)");

	return;
}

static void
dissect_coap_opt_block(tvbuff_t *tvb, packet_info *pinfo, proto_tree *subtree, gint offset, gint opt_length, int hfindex)
{
	guint8 val = 0;
	guint encoded_block_size = 0;
	guint block_size;
	proto_item *item = NULL;

	switch (opt_length) {
	case 1:
		block_number = (guint)(tvb_get_guint8(tvb, offset) >> 4);
		break;
	case 2:
		block_number = (guint)(tvb_get_ntohs(tvb, offset) >> 4);
		break;
	case 3:
		block_number = (guint)(tvb_get_ntoh24(tvb, offset) >> 4);
		break;
	default:
		expert_add_info_format(pinfo, subtree, PI_MALFORMED, PI_WARN, "Invalid Option Length: %d", opt_length);
		return;
	}

	val = tvb_get_guint8(tvb, offset + opt_length - 1) & 0x0f;
	encoded_block_size = val & 0x07;
	block_mflag = val & 0x08;

	proto_tree_add_int(subtree, hf_coap_opt_block_number, tvb, offset, opt_length, block_number);
	proto_tree_add_item(subtree, hfindex, tvb, offset + opt_length - 1, 1, FALSE);

	block_size = 1 << (encoded_block_size + 4);
	item = proto_tree_add_item(subtree, hf_coap_opt_block_size, tvb, offset + opt_length - 1, 1, ENC_BIG_ENDIAN);
	proto_item_append_text(item, ", Result: %d", block_size);
}

static void
dissect_coap_opt_port(tvbuff_t *tvb, packet_info *pinfo, proto_tree *subtree, gint offset, gint opt_length, int hfindex)
{
	proto_item *item = NULL;
	char portstr[6];

	memset(portstr, '\0', sizeof(portstr));

	switch (opt_length) {
	case 0:
		item = proto_tree_add_uint(subtree, hfindex, tvb, offset, opt_length, pinfo->destport);
		proto_item_append_text(item, " (default)");
		return;
	case 1:
		g_snprintf(portstr, sizeof(portstr), "%u", tvb_get_guint8(tvb, offset));
		break;
	case 2:
		g_snprintf(portstr, sizeof(portstr), "%u", tvb_get_ntohs(tvb, offset));
		break;
	default:
		expert_add_info_format(pinfo, subtree, PI_MALFORMED, PI_WARN, "Invalid Option Length: %d", opt_length);
		return;
	}
	(void)proto_tree_add_item(subtree, hfindex, tvb, offset, opt_length, FALSE);

	/* forming a uri-string */
	if (uri_string[0] == '\0')
		g_strlcat(uri_string, ep_address_to_str(&pinfo->net_dst), sizeof(uri_string));
	g_strlcat(uri_string, ":", sizeof(uri_string));
	g_strlcat(uri_string, portstr, sizeof(uri_string));

	return;
}

/*
 * dissector for each option of COAP.
 * return the total length of the option including the header (e.g. delta and length).
 */
static int
dissect_coap_options(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, gint offset, guint8 opt_count, guint8 *opt_code)
{
	guint8 opt_delta;
	gint opt_length;
	proto_tree *subtree = NULL;
	proto_item *item = NULL;
	gint opt_hlen = 0;
	tvbuff_t *tvb_lenbuf = NULL;

	opt_delta = (tvb_get_guint8(tvb, offset) & 0xf0) >> 4;
	*opt_code += opt_delta;

	/*
	 * Length:
	 *   Normally Length is a 4-bit unsigned integer
	 *   allowing values of 0-14 octets.  When the length is 15 or more,
	 *   another byte is added as an 8-bit unsigned integer plus 15
	 *   allowing values of 15-270 octets.
	 */
	opt_length = (tvb_get_guint8(tvb, offset) & 0x0f);
	opt_hlen = 1;
	if (opt_length == 0x0f) {
		opt_length += tvb_get_guint8(tvb, offset + 1);
		opt_hlen = 2;
	}

	item = proto_tree_add_text(coap_tree, tvb, offset, opt_hlen + opt_length,
				   "Option #%u: %s (Type: %u)",
				   opt_count, val_to_str(*opt_code, vals_opt_type, *opt_code % 14 == 0 ? "No-Op" : "Unknown Option"), *opt_code);

	subtree = proto_item_add_subtree(item, ett_coap_option);
	proto_tree_add_item(subtree, hf_coap_opt_delta, tvb, offset, 1, ENC_BIG_ENDIAN);

	tvb_lenbuf = tvb_new_subset(tvb, offset, opt_hlen, opt_hlen);
	proto_tree_add_uint_bits_format_value(subtree, hf_coap_opt_length, tvb_lenbuf, 4, opt_hlen == 1 ? 4 : 12, opt_length, "%d", opt_length);
	offset += opt_hlen;

	switch (*opt_code) {
	case COAP_OPT_CONTENT_TYPE:
		dissect_coap_opt_ctype(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_ctype);
		break;
	case COAP_OPT_MAX_AGE:
		dissect_coap_opt_time(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_max_age);
		break;
	case COAP_OPT_PROXY_URI:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_proxy_uri, COAP_OPT_PROXY_URI);
		break;
	case COAP_OPT_ETAG:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_etag, COAP_OPT_ETAG);
		break;
	case COAP_OPT_URI_HOST:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_uri_host, COAP_OPT_URI_HOST);
		break;
	case COAP_OPT_LOCATION_PATH:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_location_path, COAP_OPT_LOCATION_PATH);
		break;
	case COAP_OPT_URI_PORT:
		dissect_coap_opt_port(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_uri_port);
		break;
	case COAP_OPT_LOCATION_QUERY:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_location_query, COAP_OPT_LOCATION_QUERY);
		break;
	case COAP_OPT_URI_PATH:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_uri_path, COAP_OPT_URI_PATH);
		break;
	case COAP_OPT_OBSERVE:
		dissect_coap_opt_time(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_observe);
		break;
	case COAP_OPT_TOKEN:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_token, COAP_OPT_TOKEN);
		break;
	case COAP_OPT_ACCEPT:
		dissect_coap_opt_ctype(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_accept);
		break;
	case COAP_OPT_IF_MATCH:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_if_match, COAP_OPT_IF_MATCH);
		break;
	case COAP_OPT_URI_QUERY:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_uri_query, COAP_OPT_URI_QUERY);
		break;
	case COAP_OPT_BLOCK2:
		dissect_coap_opt_block(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_block_mflag);
		break;
	case COAP_OPT_BLOCK1:
		dissect_coap_opt_block(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_block_mflag);
		break;
	case COAP_OPT_IF_NONE_MATCH:
		dissect_coap_opt_string(tvb, pinfo, subtree, offset, opt_length, hf_coap_opt_if_none_match, COAP_OPT_IF_NONE_MATCH);
		break;
	default:
		/* In case of unknown opt_code, just ignore it here. A message is displayed beforehand. */
		break;
	}

	return offset + opt_length;
}

static void
dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree)
{
	guint offset = 0;
	proto_item *coap_root = NULL;
	proto_tree *coap_tree = NULL;
	guint8 ttype = 0;
	guint8 opt_count = 0;
	guint8 code = 0;
	guint16 tid = 0;
	guint coap_length = 0;
	guint8 opt_code = 0;
	int i;

	col_set_str(pinfo->cinfo, COL_PROTOCOL, "COAP");
	col_clear(pinfo->cinfo, COL_INFO);

	if (!parent_tree)
		return;

	/* initialize the COAP length and the content-type */
	/*
	 * the length of COAP message is not specified in the COAP header.
	 * It has to be from the lower layer.  the iplen of packet_info is not accurate.
	 * Currently, the length is just copied from the reported length of the tvbuffer.
	 */
	coap_length = tvb_reported_length(tvb);
	coap_content_type = NULL;
	coap_content_type_value = ~0;

	coap_root = proto_tree_add_item(parent_tree, proto_coap, tvb, offset, -1, FALSE);
	coap_tree = proto_item_add_subtree(coap_root, ett_coap);

	proto_tree_add_item(coap_tree, hf_coap_version, tvb, offset, 1, ENC_BIG_ENDIAN);

	proto_tree_add_item(coap_tree, hf_coap_ttype, tvb, offset, 1, ENC_BIG_ENDIAN);
	ttype = (tvb_get_guint8(tvb, offset) & 0x30) >> 4;
	col_add_fstr(pinfo->cinfo, COL_INFO, "%s", val_to_str(ttype, vals_ttype, "Unknown %d"));

	proto_tree_add_item(coap_tree, hf_coap_opt_count, tvb, offset, 1, ENC_BIG_ENDIAN);
	opt_count = tvb_get_guint8(tvb, offset) & 0x0f;
	offset += 1;

	proto_tree_add_item(coap_tree, hf_coap_code, tvb, offset, 1, ENC_BIG_ENDIAN);
	code = tvb_get_guint8(tvb, offset);
	col_append_fstr(pinfo->cinfo, COL_INFO, ", %s", val_to_str(code, vals_code, "Unknown %d"));
	offset += 1;

	proto_tree_add_item(coap_tree, hf_coap_tid, tvb, offset, 2, ENC_BIG_ENDIAN);
	tid = tvb_get_ntohs(tvb, offset);
	offset += 2;

	/* append the header information */
	proto_item_append_text(coap_tree, ", TID: %u, Length: %u", tid, coap_length);

	/* initialize the external value */
	block_number = ~0;
	block_mflag = 0;
	uri_string[0] = 0;

	/* dissect the options */
	for (i = 1; i <= opt_count; i++) {
		offset = dissect_coap_options(tvb, pinfo, coap_tree, offset, i, &opt_code);
		if (coap_length < offset) {
			/* error */
			proto_tree_add_text(coap_tree, tvb, 0, 0, "Invalid length: coap_length(%d) < offset(%d)", coap_length, offset);
			return;
		}
	}
	if (block_number != ~0) {
		col_append_fstr(pinfo->cinfo, COL_INFO, ", %sBlock #%d", block_mflag ? "" : "End of ", block_number);
	}
	if (uri_string[0] != '\0') {
		col_append_fstr(pinfo->cinfo, COL_INFO, ", %s", uri_string);
	}

	/* dissect the payload */
	if (coap_length > offset) {
		proto_tree *payload_tree = NULL;
		proto_item *payload_item = NULL;
		tvbuff_t *payload_tvb;
		guint payload_length = coap_length - offset;
		char *ctype_str_default = "";

		/*
		 * TODO: should the content type be canonicalized ?
		 * currently assuming it be small.
		 */
		if (coap_content_type_value == ~0) {
			/* default: coap-02 section 3.2.1 */
			coap_content_type = "text/plain";
			ctype_str_default = " (default)";
		}

		payload_item = proto_tree_add_text(coap_tree, tvb, offset, -1, "Payload Content-Type: %s%s, Length: %u, offset: %u",
						   coap_content_type, ctype_str_default, payload_length, offset);
		payload_tree = proto_item_add_subtree(payload_item, ett_coap_payload);
		payload_tvb = tvb_new_subset(tvb, offset, payload_length, payload_length);

		dissector_try_string(media_type_dissector_table, coap_content_type, payload_tvb, pinfo, payload_tree);
	}
}

/*
 * Protocol initialization
 */
void
proto_register_coap(void)
{
	static hf_register_info hf[] = {
		{ &hf_coap_version, { "Version", "coap.version", FT_UINT8, BASE_DEC, NULL, 0xc0, "COAP Version", HFILL }},
		{ &hf_coap_ttype, { "Type", "coap.type", FT_UINT8, BASE_DEC, VALS(vals_ttype), 0x30, "COAP Transaction Type", HFILL }},
		{ &hf_coap_opt_count, { "Option Count", "coap.optcount", FT_UINT8, BASE_DEC, NULL, 0x0f, "COAP Option Count", HFILL }},
		{ &hf_coap_code, { "Code", "coap.code", FT_UINT8, BASE_DEC, VALS(vals_code), 0x0, "COAP Method or Response Code", HFILL }},
		{ &hf_coap_tid, { "Transaction ID", "coap.tid", FT_UINT16, BASE_DEC, NULL, 0x0, "COAP Transaction ID", HFILL }},
		{ &hf_coap_opt_delta, { "Delta", "coap.opt.delta", FT_UINT8, BASE_DEC, NULL, 0xf0, "COAP Option Delta", HFILL }},
		{ &hf_coap_opt_length, { "Length", "coap.opt.length", FT_UINT16, BASE_DEC, NULL, 0x0, "COAP Option Length", HFILL }},
		{ &hf_coap_opt_ctype, { "Content-type", "coap.opt.ctype", FT_UINT8, BASE_DEC, VALS(vals_ctype), 0x0, "COAP Content Type", HFILL }},
		{ &hf_coap_opt_max_age, { "Max-age", "coap.opt.max_age", FT_UINT32, BASE_DEC, NULL, 0x0, "COAP Max-age", HFILL }},
		{ &hf_coap_opt_proxy_uri, { "Proxy-Uri", "coap.opt.proxy_uri", FT_STRING, BASE_NONE, NULL, 0x0, "COAP Proxy-Uri", HFILL }},
		{ &hf_coap_opt_etag, { "Etag", "coap.opt.etag", FT_BYTES, BASE_NONE, NULL, 0x0, "COAP Etag", HFILL }},
		{ &hf_coap_opt_uri_host, { "Uri-Host", "coap.opt.uri_host", FT_STRING, BASE_NONE, NULL, 0x0, "COAP Uri-Host", HFILL }},
		{ &hf_coap_opt_location_path, { "Location-Path", "coap.opt.location_path", FT_STRING, BASE_NONE, NULL, 0x0, "COAP URI Path", HFILL }},
		{ &hf_coap_opt_uri_port, { "Uri-Port", "coap.opt.uri_port", FT_UINT16, BASE_DEC, NULL, 0x0, "COAP Uri-Port", HFILL }},
		{ &hf_coap_opt_location_query, { "Location-Query", "coap.opt.location_query", FT_STRING, BASE_NONE, NULL, 0x0, "COAP URI Query", HFILL }},
		{ &hf_coap_opt_uri_path, { "Uri-Path", "coap.opt.uri_path", FT_STRING, BASE_NONE, NULL, 0x0, "COAP Uri-Path", HFILL }},
		{ &hf_coap_opt_observe, { "Lifetime", "coap.opt.subscr_lifetime", FT_INT32, BASE_DEC, NULL, 0x0, "COAP Observe", HFILL }},
		{ &hf_coap_opt_token, { "Token", "coap.opt.token", FT_BYTES, BASE_NONE, NULL, 0x0, "COAP Token", HFILL }},
		{ &hf_coap_opt_accept, { "Accept", "coap.opt.accept", FT_UINT8, BASE_DEC, VALS(vals_ctype), 0x0, "COAP Acceptable Content Type", HFILL }},
		{ &hf_coap_opt_if_match, { "If-Match", "coap.opt.if_match", FT_BYTES, BASE_NONE, NULL, 0x0, "COAP If-Match", HFILL }},
		{ &hf_coap_opt_block_number, { "Block Number", "coap.opt.block_number", FT_INT32, BASE_DEC, NULL, 0x0, "COAP Block Number", HFILL }},
		{ &hf_coap_opt_block_mflag, { "More Flag", "coap.opt.block_mflag", FT_UINT8, BASE_DEC, NULL, 0x08, "COAP Block More Size", HFILL }},
		{ &hf_coap_opt_block_size, { "Encoded Block Size", "coap.opt.block_size", FT_UINT8, BASE_DEC, NULL, 0x07, "COAP Encoded Block Size", HFILL }},
		{ &hf_coap_opt_uri_query, { "Uri-Query", "coap.opt.uri_query", FT_STRING, BASE_NONE, NULL, 0x0, "COAP Uri-Query", HFILL }},
		{ &hf_coap_opt_if_none_match, { "If-None-Match", "coap.opt.if_none_match", FT_BYTES, BASE_NONE, NULL, 0x0, "COAP If-None-Match", HFILL }},
	};

	static gint *ett[] = {
		&ett_coap,
		&ett_coap_option,
		&ett_coap_payload,
	};

	module_t *coap_module;

	proto_coap = proto_register_protocol("Constrained Application Protocol", "COAP", "coap");
	proto_register_field_array(proto_coap, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));

	register_dissector("coap", dissect_coap, proto_coap);

	/* Register our configuration options */
	coap_module = prefs_register_protocol (proto_coap, proto_reg_handoff_coap);

	prefs_register_uint_preference (coap_module, "udp_port",
					"COAP port number",
					"Port number used for COAP traffic",
					10, &global_coap_port_number);
}

void
proto_reg_handoff_coap(void)
{
	static gboolean coap_prefs_initialized = FALSE;
	static dissector_handle_t coap_handle;
	static guint coap_port_number;

	if (!coap_prefs_initialized) {
		coap_handle = find_dissector("coap");
		media_type_dissector_table = find_dissector_table("media_type");
		coap_prefs_initialized = TRUE;
	} else {
		dissector_delete_uint("udp.port", coap_port_number, coap_handle);
		dissector_delete_uint("tcp.port", coap_port_number, coap_handle);
	}

	coap_port_number = global_coap_port_number;
	dissector_add_uint("udp.port", coap_port_number, coap_handle);
	dissector_add_uint("tcp.port", coap_port_number, coap_handle);
}