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/* packet-mbtcp.c
* Routines for Modbus/TCP dissection
* By Riaan Swart <rswart@cs.sun.ac.za>
* Copyright 2001, Institute for Applied Computer Science
* University of Stellenbosch
*
* See
*
* http://www.modicon.com/openmbus/
*
* for information on Modbus/TCP.
*
* $Id: packet-mbtcp.c,v 1.14 2003/05/08 00:42:28 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <glib.h>
#include <epan/packet.h>
#define DEBUG
#define TCP_PORT_MBTCP 502 /* Modbus/TCP located on TCP port 502 */
/* Modbus protocol function codes */
#define read_coils 1
#define read_input_discretes 2
#define read_mult_regs 3
#define read_input_regs 4
#define write_coil 5
#define write_single_reg 6
#define read_except_stat 7
#define diagnostics 8
#define program_484 9
#define poll_484 10
#define get_comm_event_ctrs 11
#define get_comm_event_log 12
#define program_584_984 13
#define poll_584_984 14
#define force_mult_coils 15
#define write_mult_regs 16
#define report_slave_id 17
#define program_884_u84 18
#define reset_comm_link 19
#define read_genl_ref 20
#define write_genl_ref 21
#define mask_write_reg 22
#define read_write_reg 23
#define read_fifo_queue 24
#define program_ConCept 40
#define firmware_replace 125
#define program_584_984_2 126
#define report_local_addr_mb 127
/* Modbus protocol exception codes */
#define illegal_function 0x01
#define illegal_address 0x02
#define illegal_value 0x03
#define illegal_response 0x04
#define acknowledge 0x05
#define slave_busy 0x06
#define negative_ack 0x07
#define memory_err 0x08
#define gateway_unavailable 0x0a
#define gateway_trgt_fail 0x0b
/* return codes of function classifying packets as query/response */
#define query_packet 0
#define response_packet 1
#define cannot_classify 2
/* Modbus header */
typedef struct _modbus_hdr {
guint8 unit_id; /* unit identifier (previously slave addr) */
guint8 function_code; /* Modbus function code */
} modbus_hdr;
/* Modbus/TCP header, containing the Modbus header */
typedef struct _mbtcp_hdr {
guint16 transaction_id; /* copied by svr, usually 0 */
guint16 protocol_id; /* always 0 */
guint16 len; /* len of data that follows */
modbus_hdr mdbs_hdr; /* mdbus hdr directly after mdbs/tcp hdr *
* in packet */
} mbtcp_hdr;
/* Initialize the protocol and registered fields */
static int proto_mbtcp = -1;
static int hf_mbtcp_transid = -1;
static int hf_mbtcp_protid = -1;
static int hf_mbtcp_len = -1;
static int hf_mbtcp_unitid = -1;
static int hf_mbtcp_functioncode = -1;
static int hf_modbus_reference = -1;
static int hf_modbus_lreference = -1;
static int hf_modbus_reftype = -1;
static int hf_modbus_readref = -1;
static int hf_modbus_writeref = -1;
static int hf_modbus_wordcnt = -1;
static int hf_modbus_readwordcnt = -1;
static int hf_modbus_writewordcnt = -1;
static int hf_modbus_bytecnt = -1;
static int hf_modbus_lbytecnt = -1;
static int hf_modbus_bitcnt = -1;
static int hf_modbus_exceptioncode = -1;
static int hf_modbus_andmask = -1;
static int hf_modbus_ormask = -1;
/* Initialize the subtree pointers */
static gint ett_mbtcp = -1;
static gint ett_modbus_hdr = -1;
static gint ett_group_hdr = -1;
static int
classify_packet(packet_info *pinfo)
{
/* see if nature of packets can be derived from src/dst ports */
/* if so, return as found */
if ( ( 502 == pinfo->srcport && 502 != pinfo->destport ) ||
( 502 != pinfo->srcport && 502 == pinfo->destport ) ) {
/* the slave is receiving queries on port 502 */
if ( 502 == pinfo->srcport )
return response_packet;
else if ( 502 == pinfo->destport )
return query_packet;
}
/* else, cannot classify */
return cannot_classify;
}
/* Translate function to string, as given on p6 of
* "Open Modbus/TCP Specification", release 1 by Andy Swales. */
static const value_string function_code_vals[] = {
{ read_coils, "Read coils" },
{ read_input_discretes, "Read input discretes" },
{ read_mult_regs, "Read multiple registers" },
{ read_input_regs, "Read input registers" },
{ write_coil, "Write coil" },
{ write_single_reg, "Write single register" },
{ read_except_stat, "Read exception status" },
{ diagnostics, "Diagnostics" },
{ program_484, "Program (484)" },
{ poll_484, "Poll (484)" },
{ get_comm_event_ctrs, "Get Comm. Event Counters" },
{ get_comm_event_log, "Get Comm. Event Log" },
{ program_584_984, "Program (584/984)" },
{ poll_584_984, "Poll (584/984)" },
{ force_mult_coils, "Force Multiple Coils" },
{ write_mult_regs, "Write Multiple Registers" },
{ report_slave_id, "Report Slave ID" },
{ program_884_u84, "Program 884/u84" },
{ reset_comm_link, "Reset Comm. Link (884/u84)" },
{ read_genl_ref, "Read General Reference" },
{ write_genl_ref, "Write General Reference" },
{ mask_write_reg, "Mask Write Register" },
{ read_write_reg, "Read Write Register" },
{ read_fifo_queue, "Read FIFO Queue" },
{ program_ConCept, "Program (ConCept)" },
{ firmware_replace, "Firmware replacement" },
{ program_584_984_2, "Program (584/984)" },
{ report_local_addr_mb, "Report local address (Modbus)" },
{ 0, NULL }
};
static const value_string exception_code_vals[] = {
{ illegal_function, "Illegal function" },
{ illegal_address, "Illegal data address" },
{ illegal_value, "Illegal data value" },
{ illegal_response, "Illegal response length" },
{ acknowledge, "Acknowledge" },
{ slave_busy, "Slave device busy" },
{ negative_ack, "Negative acknowledge" },
{ memory_err, "Memory parity error" },
{ gateway_unavailable, "Gateway path unavailable" },
{ gateway_trgt_fail, "Gateway target device failed to respond" },
{ 0, NULL }
};
/* Code to actually dissect the packets */
static void
dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
/* Set up structures needed to add the protocol subtree and manage it */
mbtcp_hdr mh;
proto_item *mi, *mf;
proto_tree *mbtcp_tree, *modbus_tree, *group_tree;
int offset, group_offset, packet_type;
guint i;
gint packet_len, payload_start, payload_len;
char *func_string = "", pkt_type_str[9] = "";
char err_str[100] = "";
guint32 byte_cnt, group_byte_cnt, group_word_cnt;
guint32 packet_num; /* num to uniquely identify different mbtcp
* packets in one TCP packet */
guint8 exception_code;
gboolean exception_returned;
/* Make entries in Protocol column on summary display */
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP");
if (check_col(pinfo->cinfo, COL_INFO))
col_clear(pinfo->cinfo, COL_INFO);
/* Make entries in Info column on summary display */
offset = 0;
tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
mh.transaction_id = g_ntohs(mh.transaction_id);
mh.protocol_id = g_ntohs(mh.protocol_id);
mh.len = g_ntohs(mh.len);
if ( mh.mdbs_hdr.function_code & 0x80 ) {
exception_code = tvb_get_guint8(tvb, offset + sizeof(mbtcp_hdr));
mh.mdbs_hdr.function_code ^= 0x80;
exception_returned = TRUE;
}
else {
exception_code = 0;
exception_returned = FALSE;
}
func_string = val_to_str(mh.mdbs_hdr.function_code, function_code_vals,
"Unknown function (%u)");
if (check_col(pinfo->cinfo, COL_INFO))
{
packet_type = classify_packet(pinfo);
switch ( packet_type ) {
case query_packet : strcpy(pkt_type_str, "query");
break;
case response_packet : strcpy(pkt_type_str, "response");
break;
case cannot_classify : strcpy(err_str, "Unable to classify as query or response.");
strcpy(pkt_type_str, "unknown");
break;
default :
break;
}
if ( exception_returned )
strcpy(err_str, "Exception returned ");
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s",
pkt_type_str, 1, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id,
(unsigned char) mh.mdbs_hdr.function_code, func_string, err_str);
}
/* build up protocol tree and iterate over multiple packets */
packet_num = 0;
while (1) {
packet_type = classify_packet(pinfo);
packet_len = sizeof(mbtcp_hdr) - sizeof(modbus_hdr) + mh.len;
/* if a tree exists, perform operations to add fields to it */
if (tree) {
mi = proto_tree_add_protocol_format(tree, proto_mbtcp, tvb, offset,
packet_len, "Modbus/TCP");
mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp);
/* Add items to protocol tree specific to Modbus/TCP Modbus/TCP */
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2,
mh.transaction_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2,
mh.protocol_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2,
mh.len);
/* Add items to protocol tree specific to Modbus generic */
mf = proto_tree_add_text(mbtcp_tree, tvb, offset + 6, mh.len,
"Modbus");
modbus_tree = proto_item_add_subtree(mf, ett_modbus_hdr);
proto_tree_add_uint(modbus_tree, hf_mbtcp_unitid, tvb, offset + 6, 1,
mh.mdbs_hdr.unit_id);
mi = proto_tree_add_uint(modbus_tree, hf_mbtcp_functioncode, tvb, offset + 7, 1,
mh.mdbs_hdr.function_code);
/** detail payload as a function of exception/function code */
func_string = val_to_str(mh.mdbs_hdr.function_code,
function_code_vals, "Unknown function");
payload_start = offset + 8;
payload_len = mh.len - sizeof(modbus_hdr);
if (exception_returned) {
proto_item_set_text(mi, "function %u: %s. Exception: %s",
mh.mdbs_hdr.function_code,
func_string,
val_to_str(exception_code,
exception_code_vals,
"Unknown exception code (%u)"));
proto_tree_add_uint(modbus_tree, hf_modbus_exceptioncode, tvb, payload_start, 1,
exception_code);
}
else {
proto_item_set_text(mi, "function %u: %s", mh.mdbs_hdr.function_code,
func_string);
switch (mh.mdbs_hdr.function_code) {
case read_coils:
case read_input_discretes:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE);
}
else if (packet_type == response_packet) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data");
}
break;
case read_mult_regs:
case read_input_regs:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE);
}
else if (packet_type == response_packet) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data");
}
break;
case write_coil:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 1, "Data");
proto_tree_add_text(modbus_tree, tvb, payload_start + 3, 1, "Padding");
}
else if (packet_type == response_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 1, "Data");
proto_tree_add_text(modbus_tree, tvb, payload_start + 3, 1, "Padding");
}
break;
case write_single_reg:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 2, "Data");
}
else if (packet_type == response_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 2, "Data");
}
break;
case read_except_stat:
if (packet_type == response_packet)
proto_tree_add_text(modbus_tree, tvb, payload_start, 1, "Data");
break;
case force_mult_coils:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE);
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 4);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1,
byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 5, byte_cnt, "Data");
}
else if (packet_type == response_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE);
}
break;
case write_mult_regs:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE);
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 4);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1,
byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 5, byte_cnt, "Data");
}
else if (packet_type == response_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE);
}
break;
case read_genl_ref:
if (packet_type == query_packet) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1,
byte_cnt);
/* add subtrees to describe each group of packet */
group_offset = payload_start + 1;
for (i = 0; i < byte_cnt / 7; i++) {
mi = proto_tree_add_text( modbus_tree, tvb, group_offset, 7,
"Group %u", i);
group_tree = proto_item_add_subtree(mi, ett_group_hdr);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, FALSE);
proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, FALSE);
proto_tree_add_item(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, FALSE);
group_offset += 7;
}
}
else if (packet_type == response_packet) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1,
byte_cnt);
/* add subtrees to describe each group of packet */
group_offset = payload_start + 1;
i = 0;
while (byte_cnt > 0) {
group_byte_cnt = (guint32)tvb_get_guint8(tvb, group_offset);
mi = proto_tree_add_text( modbus_tree, tvb, group_offset, group_byte_cnt + 1,
"Group %u", i);
group_tree = proto_item_add_subtree(mi, ett_group_hdr);
proto_tree_add_uint(group_tree, hf_modbus_bytecnt, tvb, group_offset, 1,
group_byte_cnt);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset + 1, 1, FALSE);
proto_tree_add_text(group_tree, tvb, group_offset + 2, group_byte_cnt - 1, "Data");
group_offset += (group_byte_cnt + 1);
byte_cnt -= (group_byte_cnt + 1);
i++;
}
}
break;
case write_genl_ref:
if ((packet_type == query_packet) || (packet_type == response_packet)) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1,
byte_cnt);
/* add subtrees to describe each group of packet */
group_offset = payload_start + 1;
i = 0;
while (byte_cnt > 0) {
group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5);
group_byte_cnt = (2 * group_word_cnt) + 7;
mi = proto_tree_add_text( modbus_tree, tvb, group_offset,
group_byte_cnt, "Group %u", i);
group_tree = proto_item_add_subtree(mi, ett_group_hdr);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, FALSE);
proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, FALSE);
proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2,
group_word_cnt);
proto_tree_add_text(group_tree, tvb, group_offset + 7, group_byte_cnt - 7, "Data");
group_offset += group_byte_cnt;
byte_cnt -= group_byte_cnt;
i++;
}
}
break;
case mask_write_reg:
if ((packet_type == query_packet) || (packet_type == response_packet)) {
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, FALSE);
}
break;
case read_write_reg:
if (packet_type == query_packet) {
proto_tree_add_item(modbus_tree, hf_modbus_readref, tvb, payload_start, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_readwordcnt, tvb, payload_start + 2, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_writeref, tvb, payload_start + 4, 2, FALSE);
proto_tree_add_item(modbus_tree, hf_modbus_writewordcnt, tvb, payload_start + 6, 2, FALSE);
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 8);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 8, 1,
byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 9, byte_cnt, "Data");
}
else if (packet_type == response_packet) {
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1,
byte_cnt);
proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data");
}
break;
case read_fifo_queue:
if (packet_type == query_packet)
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE);
else if (packet_type == response_packet) {
byte_cnt = (guint32)tvb_get_ntohs(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_lbytecnt, tvb, payload_start, 2,
byte_cnt);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE);
proto_tree_add_text(modbus_tree, tvb, payload_start + 4, byte_cnt - 2, "Data");
}
break;
case diagnostics:
case program_484:
case poll_484:
case get_comm_event_ctrs:
case get_comm_event_log:
case program_584_984:
case poll_584_984:
case report_slave_id:
case program_884_u84:
case reset_comm_link:
case program_ConCept:
case firmware_replace:
case program_584_984_2:
case report_local_addr_mb:
/* these function codes are not part of the Modbus/TCP specification */
default:
if (payload_len > 0)
proto_tree_add_text(modbus_tree, tvb, payload_start, payload_len, "Data");
break;
}
}
}
/* move onto next packet (if there) */
offset += packet_len;
packet_num++;
if (tvb_reported_length_remaining(tvb, offset) > 0) {
/* load header structure for next packet */
tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
mh.transaction_id = g_ntohs(mh.transaction_id);
mh.protocol_id = g_ntohs(mh.protocol_id);
mh.len = g_ntohs(mh.len);
if ( mh.mdbs_hdr.function_code & 0x80 ) {
exception_code = tvb_get_guint8(tvb, offset + sizeof(mbtcp_hdr));
mh.mdbs_hdr.function_code ^= 0x80;
exception_returned = TRUE;
} else
exception_returned = FALSE;
}
else
break;
}
}
/* Register the protocol with Ethereal */
void
proto_register_modbus(void)
{
/* Setup list of header fields See Section 1.6.1 for details*/
static hf_register_info hf[] = {
/* Modbus/TCP header fields */
{ &hf_mbtcp_transid,
{ "transaction identifier", "modbus_tcp.trans_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_protid,
{ "protocol identifier", "modbus_tcp.prot_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_len,
{ "length", "modbus_tcp.len",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
/* Modbus header fields */
{ &hf_mbtcp_unitid,
{ "unit identifier", "modbus_tcp.unit_id",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_functioncode,
{ "function code", "modbus_tcp.func_code",
FT_UINT8, BASE_DEC, VALS(function_code_vals), 0x0,
"", HFILL }
},
{ &hf_modbus_reference,
{ "reference number", "modbus_tcp.reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_lreference,
{ "reference number (32 bit)", "modbus_tcp.reference_num_32",
FT_UINT32, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_reftype,
{ "reference type", "modbus_tcp.reference_type",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_readref,
{ "read reference number", "modbus_tcp.read_reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_writeref,
{ "write reference number", "modbus_tcp.write_reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_wordcnt,
{ "word count", "modbus_tcp.word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_readwordcnt,
{ "read word count", "modbus_tcp.read_word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_writewordcnt,
{ "write word count", "modbus_tcp.write_word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_bitcnt,
{ "bit count", "modbus_tcp.bit_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_bytecnt,
{ "byte count", "modbus_tcp.byte_cnt",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_lbytecnt,
{ "byte count (16-bit)", "modbus_tcp.byte_cnt_16",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_exceptioncode,
{ "exception code", "modbus_tcp.exception_code",
FT_UINT8, BASE_DEC, VALS(exception_code_vals), 0x0,
"", HFILL }
},
{ &hf_modbus_andmask,
{ "AND mask", "modbus_tcp.and_mask",
FT_UINT16, BASE_HEX, NULL, 0x0,
"", HFILL }
},
{ &hf_modbus_ormask,
{ "OR mask", "modbus_tcp.or_mask",
FT_UINT16, BASE_HEX, NULL, 0x0,
"", HFILL }
}
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_mbtcp,
&ett_modbus_hdr,
&ett_group_hdr
};
/* Register the protocol name and description */
proto_mbtcp = proto_register_protocol("Modbus/TCP", "Modbus/TCP", "mbtcp");
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_mbtcp, 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_mbtcp(void)
{
dissector_handle_t mbtcp_handle;
mbtcp_handle = create_dissector_handle(dissect_mbtcp, proto_mbtcp);
dissector_add("tcp.port", TCP_PORT_MBTCP, mbtcp_handle);
}
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