path: root/epan/dissectors/packet-simulcrypt.c

/* packet-simulcrypt.c
* Simulcrypt protocol across SCS - ECMG interface as defined in ETSI TS 103.197 v 1.5.1
*
* David Castleford, Orange Labs / France Telecom R&D
* Oct 2008
 * $Id$
 *
 * 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/dissectors/packet-tcp.h>
#include <epan/prefs.h>

#define PROTO_TAG_SIMULCRYPT		"SIMULCRYPT"
#define CA_SYSTEM_ID_MIKEY		0x9999  /* CA_system_ID corresponding to MIKEY ECM */
#define CA_SYSTEM_ID_MIKEY_PROTO 	"mikey" /* Protocol name to be used to "decode as" ECMs with CA_SYSTEM_ID_MIKEY */

/* Tecm_interpretation links ca_system_id to ecmg port and protocol name for dissection of ecm_datagram in ECM_Response message
* Currently size is 1 as only have MIKEY protocol but could add extra protocols
* could add option in preferences for new ca_system_id for new protocol for example
*/
typedef struct Tecm_interpretation
{
	int ca_system_id;
	char *protocol_name;
	dissector_handle_t protocol_handle;
	guint ecmg_port;
} ecm_interpretation;

#define ECM_MIKEY_INDEX 0  /* must agree with tab_ecm_inter initialization */

static ecm_interpretation tab_ecm_inter[]={
	{CA_SYSTEM_ID_MIKEY, CA_SYSTEM_ID_MIKEY_PROTO, NULL, -1}
};

#define ECM_INTERPRETATION_SIZE (sizeof(tab_ecm_inter)/sizeof(ecm_interpretation))

static void  dissect_simulcrypt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
static guint get_simulcrypt_message_len(packet_info *pinfo, tvbuff_t *tvb, int offset);

/* Wireshark ID of the SIMULCRYPT protocol */
static guint proto_simulcrypt = -1;

/* Preferences (with default values) */
static guint global_simulcrypt_tcp_port = 0;   /* Simulcrypt registered only if pref set to non-zero value */
static int ca_system_id_mikey = CA_SYSTEM_ID_MIKEY; /* MIKEY ECM CA_system_ID */

/* MIKEY payload start bytes */
/*unsigned char mikey_start[3]={0x01,0x00,0x15};
* mikey_start[0]=0x01;	 first byte mikey payload (version)
* mikey_start[1]=0x00;	 second byte mikey payload (data type)
* mikey_start[2]=0x15;	 third byte (next payload)
*/

/* Simulcrypt ECMG - SCS */
#define SIMULCRYPT_CHANNEL_SETUP 			0x0001
#define SIMULCRYPT_CHANNEL_TEST 			0x0002
#define SIMULCRYPT_CHANNEL_STATUS			0x0003
#define SIMULCRYPT_CHANNEL_CLOSE			0x0004
#define SIMULCRYPT_CHANNEL_ERROR			0x0005
#define SIMULCRYPT_STREAM_SETUP 			0x0101
#define SIMULCRYPT_STREAM_TEST 				0x0102
#define SIMULCRYPT_STREAM_STATUS			0x0103
#define SIMULCRYPT_STREAM_CLOSE_REQUEST			0x0104
#define SIMULCRYPT_STREAM_CLOSE_RESPONSE		0x0105
#define SIMULCRYPT_STREAM_ERROR				0x0106
#define SIMULCRYPT_CW_PROVISION				0x0201
#define SIMULCRYPT_ECM_RESPONSE				0x0202

static const value_string messagetypenames[] = {
	{ SIMULCRYPT_CHANNEL_SETUP, "CHANNEL_SETUP" },
	{ SIMULCRYPT_CHANNEL_TEST, "CHANNEL_TEST" },
	{ SIMULCRYPT_CHANNEL_STATUS, "CHANNEL_STATUS" },
	{ SIMULCRYPT_CHANNEL_CLOSE, "CHANNEL_CLOSE" },
	{ SIMULCRYPT_CHANNEL_ERROR, "CHANNEL_ERROR" },
	{ SIMULCRYPT_STREAM_SETUP, "STREAM_SETUP" },
	{ SIMULCRYPT_STREAM_TEST, "STREAM_TEST" },
	{ SIMULCRYPT_STREAM_STATUS, "STREAM_STATUS" },
	{ SIMULCRYPT_STREAM_CLOSE_REQUEST, "STREAM_CLOSE_REQUEST" },
	{ SIMULCRYPT_STREAM_CLOSE_RESPONSE, "STREAM_CLOSE_RESPONSE" },
	{ SIMULCRYPT_STREAM_ERROR, "STREAM_ERROR" },
	{ SIMULCRYPT_CW_PROVISION, "CW_PROVISION" },
	{ SIMULCRYPT_ECM_RESPONSE, "ECM_RESPONSE" },
	{ 0, NULL}
};	

/* Simulcrypt Parameter Types */
#define SIMULCRYPT_DVB_RESERVED 			0x0000
#define SIMULCRYPT_SUPER_CAS_ID 			0x0001
#define SIMULCRYPT_SECTION_TSPKT_FLAG 			0x0002
#define SIMULCRYPT_DELAY_START 				0x0003
#define SIMULCRYPT_DELAY_STOP	 			0x0004
#define SIMULCRYPT_TRANSITION_DELAY_START		0x0005
#define SIMULCRYPT_TRANSITION_DELAY_STOP		0x0006
#define SIMULCRYPT_ECM_REP_PERIOD	 		0x0007
#define SIMULCRYPT_MAX_STREAMS	 			0x0008
#define SIMULCRYPT_MIN_CP_DURATION 			0x0009
#define SIMULCRYPT_LEAD_CW	 			0x000A
#define SIMULCRYPT_CW_PER_MESSAGE 			0x000B
#define SIMULCRYPT_MAX_COMP_TIME 			0x000C
#define SIMULCRYPT_ACCESS_CRITERIA			0x000D
#define SIMULCRYPT_ECM_CHANNEL_ID			0x000E
#define SIMULCRYPT_ECM_STREAM_ID			0x000F
#define SIMULCRYPT_NOMINAL_CP_DURATION 			0x0010
#define SIMULCRYPT_ACCESS_CRITERIA_TRANSFER_MODE	0x0011
#define SIMULCRYPT_CP_NUMBER 				0x0012
#define SIMULCRYPT_CP_DURATION 				0x0013
#define SIMULCRYPT_CP_CW_COMBINATION 			0x0014
#define SIMULCRYPT_ECM_DATAGRAM				0x0015
#define SIMULCRYPT_AC_DELAY_START 			0x0016
#define SIMULCRYPT_AC_DELAY_STOP	 		0x0017
#define SIMULCRYPT_CW_ENCRYPTION	 		0x0018
#define SIMULCRYPT_ECM_ID				0x0019
#define SIMULCRYPT_ERROR_STATUS				0x7000
#define SIMULCRYPT_ERROR_INFORMATION			0x7001

static const value_string parametertypenames[] = {
	{ SIMULCRYPT_DVB_RESERVED, "DVB_RESERVED" },
	{ SIMULCRYPT_SUPER_CAS_ID, "SUPER_CAS_ID" },
	{ SIMULCRYPT_SECTION_TSPKT_FLAG, "SECTION_TSPKT_FLAG" },
	{ SIMULCRYPT_DELAY_START, "DELAY_START" },
	{ SIMULCRYPT_DELAY_STOP, "DELAY_STOP" },
	{ SIMULCRYPT_TRANSITION_DELAY_START, "TRANSITION_DELAY_START" },
	{ SIMULCRYPT_TRANSITION_DELAY_STOP, "TRANSITION_DELAY_STOP" },
	{ SIMULCRYPT_ECM_REP_PERIOD, "ECM_REP_PERIOD" },
	{ SIMULCRYPT_MAX_STREAMS, "MAX_STREAMS" },
	{ SIMULCRYPT_MIN_CP_DURATION, "MIN_CP_DURATION" },
	{ SIMULCRYPT_LEAD_CW, "LEAD_CW" },
	{ SIMULCRYPT_CW_PER_MESSAGE, "CW_PER_MESSAGE" },
	{ SIMULCRYPT_MAX_COMP_TIME, "MAX_COMP_TIME" },
	{ SIMULCRYPT_ACCESS_CRITERIA, "ACCESS_CRITERIA" },
	{ SIMULCRYPT_ECM_CHANNEL_ID, "ECM_CHANNEL_ID" },
	{ SIMULCRYPT_ECM_STREAM_ID, "ECM_STREAM_ID" },
	{ SIMULCRYPT_NOMINAL_CP_DURATION, "NOMINAL_CP_DURATION" },
	{ SIMULCRYPT_ACCESS_CRITERIA_TRANSFER_MODE, "ACCESS_CRITERIA_TRANSFER_MODE" },
	{ SIMULCRYPT_CP_NUMBER, "CP_NUMBER" },
	{ SIMULCRYPT_CP_DURATION, "CP_DURATION" },
	{ SIMULCRYPT_CP_CW_COMBINATION, "CP_CW_COMBINATION" },
	{ SIMULCRYPT_ECM_DATAGRAM, "ECM_DATAGRAM" },
	{ SIMULCRYPT_AC_DELAY_START, "AC_DELAY_START" },
	{ SIMULCRYPT_AC_DELAY_STOP, "AC_DELAY_STOP" },
	{ SIMULCRYPT_CW_ENCRYPTION, "CW_ENCRYPTION" },
	{ SIMULCRYPT_ECM_ID, "ECM_ID" },
	{ SIMULCRYPT_ERROR_STATUS, "ERROR_STATUS" },
	{ SIMULCRYPT_ERROR_INFORMATION, "ERROR_INFORMATION" },
	{ 0, NULL}
};

/* The following hf_* variables are used to hold the Wireshark IDs of
* our header fields; they are filled out when we call
* proto_register_field_array() in proto_register_simulcrypt()
*/
static gint hf_simulcrypt_header = -1;
static gint hf_simulcrypt_version = -1;
static gint hf_simulcrypt_message_type = -1;
static gint hf_simulcrypt_message_length = -1;
static gint hf_simulcrypt_message = -1;
static gint hf_simulcrypt_parameter = -1;
static gint hf_simulcrypt_parameter_type = -1;
static gint hf_simulcrypt_parameter_length = -1;
static gint hf_simulcrypt_ca_system_id = -1;
static gint hf_simulcrypt_ca_subsystem_id = -1;
static gint hf_simulcrypt_super_cas_id = -1;
static gint hf_simulcrypt_section_tspkt_flag = -1;
static gint hf_simulcrypt_ecm_channel_id = -1;
static gint hf_simulcrypt_delay_start = -1;
static gint hf_simulcrypt_delay_stop = -1;
static gint hf_simulcrypt_ac_delay_start = -1;
static gint hf_simulcrypt_ac_delay_stop = -1;
static gint hf_simulcrypt_transition_delay_start = -1;
static gint hf_simulcrypt_transition_delay_stop = -1;
static gint hf_simulcrypt_ecm_rep_period = -1;
static gint hf_simulcrypt_max_streams = -1;
static gint hf_simulcrypt_min_cp_duration = -1;
static gint hf_simulcrypt_lead_cw = -1;
static gint hf_simulcrypt_cw_per_msg = -1;
static gint hf_simulcrypt_max_comp_time = -1;
static gint hf_simulcrypt_access_criteria = -1;
static gint hf_simulcrypt_ecm_stream_id = -1;
static gint hf_simulcrypt_nominal_cp_duration = -1;
static gint hf_simulcrypt_access_criteria_transfer_mode = -1;
static gint hf_simulcrypt_cp_number = -1;
static gint hf_simulcrypt_cp_duration = -1;
static gint hf_simulcrypt_cp_cw_combination = -1;
static gint hf_simulcrypt_ecm_datagram = -1;
static gint hf_simulcrypt_cw_encryption = -1;
static gint hf_simulcrypt_ecm_id = -1;
static gint hf_simulcrypt_error_status = -1;
static gint hf_simulcrypt_error_information = -1;

/* These are the ids of the subtrees that we may be creating */
static gint ett_simulcrypt = -1;
static gint ett_simulcrypt_header = -1;
static gint ett_simulcrypt_message = -1;
static gint ett_simulcrypt_parameter = -1;
static gint ett_simulcrypt_super_cas_id = -1;
static gint ett_simulcrypt_ecm_datagram = -1;


#define FRAME_HEADER_LEN 8

/* The main dissecting routine */
static void dissect_simulcrypt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    tcp_dissect_pdus(tvb, pinfo, tree, TRUE, FRAME_HEADER_LEN,
                     get_simulcrypt_message_len, dissect_simulcrypt_message);
}

/* Informative tree structure is shown here:
* TREE 	-
*	- HEADER
*		version
*		message type
*		message length
*	- MESSAGE
*		- TYPE of parameter
*			length of parameter
			value of parameter
			- PARAMETER (optional branch for certain parameters only)
*				parameter value sub items here
* End informative tree structure 
*/

/* This method dissects fully reassembled messages */
static void dissect_simulcrypt_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{

	proto_item *simulcrypt_item;
	proto_tree *simulcrypt_tree;
	proto_tree *simulcrypt_header_tree;
	proto_tree *simulcrypt_message_tree;
	proto_tree *simulcrypt_parameter_tree;
	proto_tree *simulcrypt_super_cas_id_tree;
	proto_tree *simulcrypt_ecm_datagram_tree;
	guint16     type;
	tvbuff_t   *next_tvb;

	if (check_col(pinfo->cinfo, COL_PROTOCOL))
		col_set_str(pinfo->cinfo, COL_PROTOCOL, PROTO_TAG_SIMULCRYPT);
	/* Clear out stuff in the info column */
	if(check_col(pinfo->cinfo,COL_INFO))
	{
		col_clear(pinfo->cinfo,COL_INFO);
	}

	/* get 2 byte type value */
	type =  tvb_get_ntohs(tvb, 1); /* 2 bytes starting at offset 1 are the message type */

	if (check_col(pinfo->cinfo, COL_INFO))
	{
		col_add_fstr(pinfo->cinfo, COL_INFO, "%d > %d Info Type:[%s]",
		pinfo->srcport, pinfo->destport, 
		val_to_str(type, messagetypenames, "Unknown Type:0x%02x"));
	}

	if (tree)
	{
		/* we are being asked for details */
		guint32 offset = 0;
		guint32 msg_length;
		
		simulcrypt_item = proto_tree_add_item(tree, proto_simulcrypt, tvb, 0, -1, FALSE);
		simulcrypt_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt);

		/* Simulcrypt_tree analysis */
		/* we are being asked for details */
		/* ADD HEADER BRANCH */
		simulcrypt_item = proto_tree_add_item(simulcrypt_tree, hf_simulcrypt_header, tvb, offset, 5, FALSE );
		simulcrypt_header_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt_header);
		proto_item_append_text(simulcrypt_header_tree, ", Length: %s", "5 bytes"); /* add text to Header tree indicating Length 5 bytes */

		/* Simulcrypt_header_tree analysis */
		/* Message Version 1 Byte */
		proto_tree_add_item(simulcrypt_header_tree, hf_simulcrypt_version, tvb, offset, 1, FALSE);		
		offset+=1;

		/* Message  Type 2 Bytes */
		proto_tree_add_item(simulcrypt_header_tree, hf_simulcrypt_message_type, tvb, offset, 2, FALSE);
		offset+=2;

		/* Message Length 2 Bytes */
		simulcrypt_item=proto_tree_add_item(simulcrypt_header_tree, hf_simulcrypt_message_length, tvb, offset, 2, FALSE);
		proto_item_append_text(simulcrypt_item, " (bytes)");
		msg_length = tvb_get_ntohs(tvb, offset); /* read 2 byte message length value */
		offset+=2;
	
		/* ADD MESSAGE BRANCH */
		simulcrypt_item = proto_tree_add_item( simulcrypt_tree, hf_simulcrypt_message, tvb, offset, -1, FALSE );
		simulcrypt_message_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt_message);
		proto_item_append_text(simulcrypt_message_tree, " containing TLV parameters"); /* add text to Message tree	*/	
		proto_item_append_text(simulcrypt_message_tree, ", Length: %d (bytes)", msg_length); /* add length info to message_tree */
		
		/* end header details */
 
		/* Simulcrypt_message_tree analysis */
		/*  we are being asked for details */
		/* Navigate through message after header to find one or more parameters */
		while (offset < (msg_length+5))  /* offset is from beginning of the 5 byte header */
		{
			guint16 plen;         /* parameter length */
			guint16 ptype;        /* parameter type */
			guint32 pvaluedec;    /* parameter decimal value */
			gchar  *pvalue_char;  /* parameter value string */
			int     ca_system_id;
			guint   i;
			
			/* Parameter  Type 2 Bytes */
			ptype= tvb_get_ntohs(tvb, offset); /* read 2 byte type value */
			/* Parameter  Length 2 Bytes */
			plen=tvb_get_ntohs(tvb, offset+2); /* read 2 byte length value */
			/* Parameter  Value plen Bytes */
			pvalue_char = tvb_bytes_to_str(tvb, offset+4, plen);

			simulcrypt_item = proto_tree_add_item( simulcrypt_message_tree, hf_simulcrypt_parameter, tvb, offset, plen+2+2, FALSE );

			/* add length and value info to type */
			proto_item_append_text(simulcrypt_item, ": Type=%s", val_to_str(ptype, parametertypenames, "Unknown Type:0x%02x"));
			proto_item_append_text(simulcrypt_item, ", Value Length=%d (bytes)", plen); /* add length info to parameter */
			proto_item_append_text(simulcrypt_item, ", Value=0x%s", pvalue_char); /* add value info to parameter */
			/* add subtree for parameter type, length and value items */
			simulcrypt_parameter_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt_parameter); /* add subtree for Length and Value */
			simulcrypt_item=proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_parameter_type, tvb, offset, 2, FALSE); /* parameter type */
			simulcrypt_item=proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_parameter_length, tvb, offset+2, 2, FALSE); /* length item */
			offset += 2+2;  /* offset --> parameter value */
			proto_item_append_text(simulcrypt_item, " (bytes)");
			
			switch(ptype)
			{
				case SIMULCRYPT_SUPER_CAS_ID:
					/* add super_cas_id item */
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_super_cas_id, tvb, offset, plen, FALSE); /* value item */
					simulcrypt_super_cas_id_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt_super_cas_id);
					
					/* Simulcrypt_super_cas_id_tree */
					simulcrypt_item = proto_tree_add_item(simulcrypt_super_cas_id_tree, hf_simulcrypt_ca_system_id, tvb, offset, 2, FALSE );
						
					/* Test for known CA_System_ID */
					ca_system_id = tvb_get_ntohs(tvb,offset);
					for(i=0;i<ECM_INTERPRETATION_SIZE;i++)
					{			
						if(tab_ecm_inter[i].ca_system_id==ca_system_id)
						{
							tab_ecm_inter[i].ecmg_port=pinfo->destport;
							proto_item_append_text(simulcrypt_item, ", Port %d, Protocol %s",tab_ecm_inter[i].ecmg_port, tab_ecm_inter[i].protocol_name);
							break;
						}
					}
					simulcrypt_item = proto_tree_add_item(simulcrypt_super_cas_id_tree, hf_simulcrypt_ca_subsystem_id, tvb, offset+2, 2, FALSE );
					break;
				case SIMULCRYPT_SECTION_TSPKT_FLAG:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_section_tspkt_flag, tvb, offset, plen, FALSE); /* value item */
					break;
				case SIMULCRYPT_ECM_CHANNEL_ID:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ecm_channel_id, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_DELAY_START:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_delay_start, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_DELAY_STOP:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_delay_stop, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms"); 
					break;
				case SIMULCRYPT_TRANSITION_DELAY_START:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_transition_delay_start, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_TRANSITION_DELAY_STOP:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_transition_delay_stop, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_AC_DELAY_START:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ac_delay_start, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_AC_DELAY_STOP:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ac_delay_stop, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_ECM_REP_PERIOD:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ecm_rep_period, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_MAX_STREAMS:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_max_streams, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_MIN_CP_DURATION:
					/* convert value to ms (in units 100 ms) */
					pvaluedec = tvb_get_ntohs(tvb, offset); /* read 2 byte min CP duration value */
					pvaluedec = pvaluedec*100; /* in ms now */
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_min_cp_duration, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " (%d ms)",pvaluedec);
					break;
				case SIMULCRYPT_LEAD_CW:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_lead_cw, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_CW_PER_MESSAGE:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_cw_per_msg, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_MAX_COMP_TIME:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_max_comp_time, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " ms");
					break;
				case SIMULCRYPT_ACCESS_CRITERIA:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_access_criteria, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_ECM_STREAM_ID:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ecm_stream_id, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_NOMINAL_CP_DURATION:
					/* convert value to ms (in units 100 ms) */
					pvaluedec = tvb_get_ntohs(tvb, offset); /* read 2 byte nominal CP duration value */
					pvaluedec = pvaluedec*100; /* in ms now */
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_nominal_cp_duration, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " (%d ms)", pvaluedec);
					break;
				case SIMULCRYPT_ACCESS_CRITERIA_TRANSFER_MODE:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_access_criteria_transfer_mode, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_CP_NUMBER:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_cp_number, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_CP_DURATION:
					/* convert value to ms (in units 100 ms) */
					pvaluedec = tvb_get_ntohs(tvb, offset); /* read 2 byte CP duration value */
					pvaluedec = pvaluedec*100; /* in ms now */
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_cp_duration, tvb, offset, plen, FALSE);
					proto_item_append_text(simulcrypt_item, " (%d ms)", pvaluedec);
					break;
				case SIMULCRYPT_CP_CW_COMBINATION:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_cp_cw_combination, tvb, offset, plen, FALSE); 
					break;
				case SIMULCRYPT_ECM_DATAGRAM:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ecm_datagram, tvb, offset, plen, FALSE); 
					/* Test srcport against table of ECMG ports & CA_System_ID for known protocol types */
					for(i=0;i<ECM_INTERPRETATION_SIZE;i++)
					{
						if(tab_ecm_inter[i].ecmg_port==pinfo->srcport) /* ECMG source port */
						{ /* recognise port & ca_system_id and hence protocol name for ECM datagram */
							next_tvb = tvb_new_subset(tvb, offset, -1, -1);
							simulcrypt_ecm_datagram_tree = proto_item_add_subtree(simulcrypt_item, ett_simulcrypt_ecm_datagram);
							if(tab_ecm_inter[i].protocol_handle != NULL)
							{
								call_dissector(tab_ecm_inter[i].protocol_handle, next_tvb,pinfo, simulcrypt_ecm_datagram_tree);
							}
							break;
						}
					}
					break;
				case SIMULCRYPT_CW_ENCRYPTION:
					simulcrypt_item = proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_cw_encryption, tvb, offset, plen, FALSE); 
					break;
				case SIMULCRYPT_ECM_ID:
					simulcrypt_item=proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_ecm_id, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_ERROR_STATUS:
					simulcrypt_item=proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_error_status, tvb, offset, plen, FALSE);
					break;
				case SIMULCRYPT_ERROR_INFORMATION:
					simulcrypt_item=proto_tree_add_item( simulcrypt_parameter_tree, hf_simulcrypt_error_information, tvb, offset, plen, FALSE);
					break;
				default:  /* Unknown parameter type */
					simulcrypt_item = proto_tree_add_text( simulcrypt_parameter_tree, tvb, offset, plen,
                                                                               "Parameter Value: %s", pvalue_char); 
					break;
			} /* end parameter type switch */
			offset += plen;
		} /* end parameter tree details */
			
	} /* end tree */
}	

/* determine PDU length of protocol foo */
static guint get_simulcrypt_message_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset)
{
	guint iLg;
	
	iLg = tvb_get_ntohs(tvb,offset+3); /*length is at offset 3 */
	iLg += 5; /* add 1 byte version + 2 byte type + 2 byte length (simulcrypt "header" */
	return iLg;
}	

/* Clean out the ecm_interpretation port association whenever            */
/* making a pass through a capture file to dissect all its packets       */
/*  (e.g., reading in a new capture file, changing a simulcrypt pref,    */
/*  or running a "filter packets" or "colorize packets" pass over the    */
/*  current capture file.                                                */

static void 
simulcrypt_init(void) 
{
	guint i;

	for(i=0;i<ECM_INTERPRETATION_SIZE;i++)
	{
		tab_ecm_inter[i].ecmg_port = -1;
	}
}

void proto_reg_handoff_simulcrypt(void);

void proto_register_simulcrypt (void)
{
	/* A header field is something you can search/filter on.
	* 
	* We create a structure to register our fields. It consists of an
	* array of hf_register_info structures, each of which are of the format
	* {&(field id), {name, abbrev, type, display, strings, bitmask, blurb, HFILL}}.
	*/
	static hf_register_info hf[] =
	{
		{ &hf_simulcrypt_header,
		{ "Header", "simulcrypt.header", FT_NONE, BASE_NONE, NULL, 0x0,
		 NULL, HFILL }},
		 
		{ &hf_simulcrypt_version,
		{ "Version", "simulcrypt.version", FT_UINT8, BASE_HEX, NULL, 0x0, 	/* version 1 byte */
		NULL, HFILL }},

		{ &hf_simulcrypt_message_type,
		{ "Message Type", "simulcrypt.message.type", FT_UINT16, BASE_HEX, VALS(messagetypenames), 0x0,		/* type 2 bytes */
		 NULL, HFILL }},

		{ &hf_simulcrypt_message_length,
		{ "Message Length", "simulcrypt.message.len", FT_UINT16, BASE_DEC, NULL, 0x0,		/* length 2 bytes, print as decimal value */
		NULL, HFILL }},

		{ &hf_simulcrypt_message,
		{ "Message", "simulcrypt.message", FT_NONE, BASE_NONE, NULL, 0x0,
		 NULL, HFILL }}, 
		 
		{ &hf_simulcrypt_parameter,
		{ "Parameter", "simulcrypt.parameter", FT_NONE, BASE_NONE, NULL, 0x0,
		 NULL, HFILL }}, 
		 
		{ &hf_simulcrypt_parameter_type,
		{ "Parameter Type", "simulcrypt.parameter.type", FT_UINT16, BASE_HEX, VALS(parametertypenames), 0x0,	/* type 2 bytes */
		 NULL, HFILL }},

		{ &hf_simulcrypt_parameter_length,
		{ "Parameter Length", "simulcrypt.parameter.len", FT_UINT16, BASE_DEC, NULL, 0x0,		/* length 2 bytes, print as decimal value */
		NULL, HFILL }},

		{ &hf_simulcrypt_ca_system_id,
		{ "CA System ID", "simulcrypt.parameter.ca_system_id", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }}, 

		{ &hf_simulcrypt_ca_subsystem_id,
		{ "CA Subsystem ID", "simulcrypt.parameter.ca_subsystem_id", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},
		 
		{ &hf_simulcrypt_super_cas_id,
		{ "SuperCAS ID", "simulcrypt.super_cas_id", FT_UINT32, BASE_HEX, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_section_tspkt_flag,
		{ "Section TS pkt flag", "simulcrypt.section_tspkt_flag", FT_UINT8, BASE_HEX, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_ecm_channel_id,
		{ "ECM channel ID", "simulcrypt.ecm_channel_id", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_delay_start,	
		{ "Delay start", "simulcrypt.delay_start", FT_INT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_delay_stop,	
		{ "Delay stop", "simulcrypt.delay_stop", FT_INT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_ac_delay_start,	
		{ "AC delay start", "simulcrypt.ac_delay_start", FT_INT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_ac_delay_stop,	
		{ "AC delay stop", "simulcrypt.ac_delay_stop", FT_INT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_transition_delay_start,	
		{ "Transition delay start", "simulcrypt.transition_delay_start", FT_INT16, BASE_DEC, NULL, 0x0,
		 "Transition delay start", HFILL }},

		{ &hf_simulcrypt_transition_delay_stop,	
		{ "Transition delay stop", "simulcrypt.transition_delay_stop", FT_INT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},	

		{ &hf_simulcrypt_ecm_rep_period,
		{ "ECM repetition period", "simulcrypt.ecm_rep_period", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_max_streams,
		{ "Max streams", "simulcrypt.max_streams", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_min_cp_duration,
		{ "Min CP duration", "simulcrypt.min_cp_duration", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_lead_cw,
		{ "Lead CW", "simulcrypt.lead_cw", FT_UINT8, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_cw_per_msg,
		{ "CW per msg", "simulcrypt.cw_per_msg", FT_UINT8, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_max_comp_time,
		{ "Max comp time", "simulcrypt.max_comp_time", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_access_criteria,
		{ "Access criteria", "simulcrypt.access_criteria", FT_BYTES, BASE_HEX, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_ecm_stream_id,
		{ "ECM stream ID", "simulcrypt.ecm_stream_id", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},	

		{ &hf_simulcrypt_nominal_cp_duration,
		{ "Nominal CP duration", "simulcrypt.nominal_cp_duration", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_access_criteria_transfer_mode,
		{ "AC transfer mode", "simulcrypt.access_criteria_transfer_mode", FT_BOOLEAN, 8, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_cp_number,
		{ "CP number", "simulcrypt.cp_number", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_cp_duration,
		{ "CP duration", "simulcrypt.cp_duration", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_cp_cw_combination,
		{ "CP CW combination", "simulcrypt.cp_cw_combination", FT_BYTES, BASE_HEX, NULL, 0x0,
		 NULL, HFILL }},
		 
		{ &hf_simulcrypt_ecm_datagram,
		{ "ECM datagram", "simulcrypt.ecm_datagram", FT_BYTES, BASE_HEX, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_cw_encryption,
		{ "CW encryption", "simulcrypt.cw_encryption", FT_NONE, BASE_NONE, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_ecm_id,
		{ "ECM ID", "simulcrypt.ecm_id", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_error_status,
		{ "Error status", "simulcrypt.error_status", FT_UINT16, BASE_DEC, NULL, 0x0,
		 NULL, HFILL }},

		{ &hf_simulcrypt_error_information,
		{ "Error information", "simulcrypt.error_information", FT_NONE, BASE_NONE, NULL, 0x0,
		 NULL, HFILL }}		 
	};
	
	static gint *ett[] =
	{
		&ett_simulcrypt,
		&ett_simulcrypt_header,
		&ett_simulcrypt_message,
		&ett_simulcrypt_parameter,
		&ett_simulcrypt_super_cas_id,
		&ett_simulcrypt_ecm_datagram
	};
	
	module_t *simulcrypt_module;
	
	/* execute protocol initialization only once */
	proto_simulcrypt = proto_register_protocol ("SIMULCRYPT Protocol", "SIMULCRYPT", "simulcrypt");

	proto_register_field_array (proto_simulcrypt, hf, array_length (hf));
	proto_register_subtree_array (ett, array_length (ett));
	
	register_init_routine(simulcrypt_init);

	/* Register our configuration options for Simulcrypt, particularly our port. */
	/* This registers our preferences; function proto_reg_handoff_simulcrypt is  */
	/*  called when preferences are applied.                                     */
	simulcrypt_module = prefs_register_protocol(proto_simulcrypt, proto_reg_handoff_simulcrypt);
	
	prefs_register_uint_preference(simulcrypt_module, "tcp.port", "Simulcrypt TCP Port",
				 "Set the port for Simulcrypt messages ('0' means no port is assigned)",
				 10, &global_simulcrypt_tcp_port);
									
	prefs_register_uint_preference(simulcrypt_module, "ca_system_id_mikey","MIKEY ECM CA_system_ID 0x (hex value)",
					"Set the CA_system_ID used to decode ECM datagram as MIKEY", 16, &ca_system_id_mikey);		
}

/* this is run every time preferences are changed and also during Wireshark initialization */
void proto_reg_handoff_simulcrypt(void)
{
	static gboolean initialized=FALSE;
	static dissector_handle_t simulcrypt_handle;
	static guint tcp_port;
	guint  i;

	if (!initialized) {
		simulcrypt_handle = create_dissector_handle( dissect_simulcrypt, proto_simulcrypt);
		for(i=0;i<ECM_INTERPRETATION_SIZE;i++)
		{
			tab_ecm_inter[i].protocol_handle = find_dissector(tab_ecm_inter[i].protocol_name);
		}
		initialized = TRUE;
	}
	else {
		if (tcp_port != 0) {
			dissector_delete("tcp.port", tcp_port, simulcrypt_handle);
		}
	}	
	if (global_simulcrypt_tcp_port != 0) {
		dissector_add("tcp.port", global_simulcrypt_tcp_port, simulcrypt_handle);
	}
	tcp_port = global_simulcrypt_tcp_port;

	/* update tab_ecm_inter table (always do this) */
	tab_ecm_inter[ECM_MIKEY_INDEX].ca_system_id=ca_system_id_mikey;
}