osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity
wireshark/epan/dissectors/packet-mbtcp.c

2064 lines
90 KiB
C
Raw Blame History

/* packet-mbtcp.c
* Routines for Modbus/TCP and Modbus/UDP dissection
* By Riaan Swart <rswart@cs.sun.ac.za>
* Copyright 2001, Institute for Applied Computer Science
* University of Stellenbosch
*
* See http://www.modbus.org/ for information on Modbus/TCP.
*
* Updated to v1.1b of the Modbus Application Protocol specification
* Michael Mann * Copyright 2011
*
*****************************************************************************************************
* A brief explanation of the distinction between Modbus/TCP and Modbus RTU over TCP:
*
* Consider a Modbus poll message: Unit 01, Scan Holding Register Address 0 for 30 Registers
*
* The Modbus/TCP message structure will follow the pattern below:
* 00 00 00 00 00 06 01 03 00 00 00 1E
* AA AA BB BB CC CC DD EE FF FF GG GG
*
* A = 16-bit Transaction Identifier (typically increments, or is locked at zero)
* B = 16-bit Protocol Identifier (typically zero)
* C = 16-bit Length of data payload following (and inclusive of) the length byte
* D = 8-bit Unit / Slave ID
* E = 8-bit Modbus Function Code
* F = 16-bit Reference Number / Register Base Address
* G = 16-bit Word Count / Number of Registers to scan
*
* A identical Modbus RTU (or Modbus RTU over TCP) message will overlay partially with the msg above
* and contain 16-bit CRC at the end:
* 00 00 00 00 00 06 01 03 00 00 00 1E -- -- (Modbus/TCP message, repeated from above)
* -- -- -- -- -- -- 01 03 00 00 00 1E C5 C2 (Modbus RTU over TCP message, includes 16-bit CRC footer)
* AA AA BB BB CC CC DD EE FF FF GG GG HH HH
*
* A = Not present in Modbus RTU message
* B = Not present in Modbus RTU message
* C = Not present in Modbus RTU message
* D = 8-bit Unit / Slave ID
* E = 8-bit Modbus Function Code
* F = 16-bit Reference Number / Register Base Address
* G = 16-bit Word Count / Number of Registers to scan
* H = 16-bit CRC
*
*****************************************************************************************************
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <epan/packet.h>
#include "packet-tcp.h"
#include "packet-mbtcp.h"
#include <epan/prefs.h>
#include <epan/expert.h>
#include <epan/crc16-tvb.h> /* For CRC verification */
#include <epan/proto_data.h>
void proto_register_modbus(void);
void proto_reg_handoff_mbtcp(void);
void proto_reg_handoff_mbrtu(void);
/* Initialize the protocol and registered fields */
static int proto_mbtcp = -1;
static int proto_mbrtu = -1;
static int proto_modbus = -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_modbus_request_frame = -1;
static int hf_modbus_functioncode = -1;
static int hf_modbus_reference = -1;
static int hf_modbus_padding = -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_diag_sf = -1;
static int hf_modbus_diag_return_query_data_request = -1;
static int hf_modbus_diag_return_query_data_echo = -1;
static int hf_modbus_diag_restart_communication_option = -1;
static int hf_modbus_diag_return_diag_register = -1;
static int hf_modbus_diag_ascii_input_delimiter = -1;
static int hf_modbus_diag_clear_ctr_diag_reg = -1;
static int hf_modbus_diag_return_bus_message_count = -1;
static int hf_modbus_diag_return_bus_comm_error_count = -1;
static int hf_modbus_diag_return_bus_exception_error_count = -1;
static int hf_modbus_diag_return_slave_message_count = -1;
static int hf_modbus_diag_return_no_slave_response_count = -1;
static int hf_modbus_diag_return_slave_nak_count = -1;
static int hf_modbus_diag_return_slave_busy_count = -1;
static int hf_modbus_diag_return_bus_char_overrun_count = -1;
static int hf_modbus_status = -1;
static int hf_modbus_event = -1;
static int hf_modbus_event_count = -1;
static int hf_modbus_message_count = -1;
static int hf_modbus_event_recv_comm_err = -1;
static int hf_modbus_event_recv_char_over = -1;
static int hf_modbus_event_recv_lo_mode = -1;
static int hf_modbus_event_recv_broadcast = -1;
static int hf_modbus_event_send_read_ex = -1;
static int hf_modbus_event_send_slave_abort_ex = -1;
static int hf_modbus_event_send_slave_busy_ex = -1;
static int hf_modbus_event_send_slave_nak_ex = -1;
static int hf_modbus_event_send_write_timeout = -1;
static int hf_modbus_event_send_lo_mode = -1;
static int hf_modbus_andmask = -1;
static int hf_modbus_ormask = -1;
static int hf_modbus_data = -1;
static int hf_modbus_mei = -1;
static int hf_modbus_read_device_id = -1;
static int hf_modbus_object_id = -1;
static int hf_modbus_num_objects = -1;
static int hf_modbus_list_object_len = -1;
static int hf_modbus_conformity_level = -1;
static int hf_modbus_more_follows = -1;
static int hf_modbus_next_object_id = -1;
static int hf_modbus_object_str_value = -1;
static int hf_modbus_object_value = -1;
static int hf_modbus_reg16 = -1;
static int hf_modbus_reg32 = -1;
static int hf_mbrtu_unitid = -1;
static int hf_mbrtu_crc16 = -1;
/* Initialize the subtree pointers */
static gint ett_mbtcp = -1;
static gint ett_mbrtu = -1;
static gint ett_modbus_hdr = -1;
static gint ett_group_hdr = -1;
static gint ett_events = -1;
static gint ett_events_recv = -1;
static gint ett_events_send = -1;
static gint ett_device_id_objects = -1;
static gint ett_device_id_object_items = -1;
static expert_field ei_mbrtu_crc16_incorrect = EI_INIT;
static expert_field ei_modbus_data_decode = EI_INIT;
static expert_field ei_mbtcp_cannot_classify = EI_INIT;
static dissector_handle_t modbus_handle;
static dissector_handle_t mbtcp_handle;
static dissector_handle_t mbrtu_handle;
static dissector_table_t modbus_data_dissector_table;
static dissector_table_t modbus_dissector_table;
/* Globals for Modbus/TCP Preferences */
static gboolean mbtcp_desegment = TRUE;
static guint global_mbus_tcp_port = PORT_MBTCP; /* Port 502, by default */
/* Globals for Modbus RTU over TCP Preferences */
static gboolean mbrtu_desegment = TRUE;
static guint global_mbus_rtu_port = PORT_MBRTU; /* 0, by default */
static gboolean mbrtu_crc = FALSE;
/* Globals for Modbus Preferences */
static gint global_mbus_register_format = MODBUS_PREF_REGISTER_FORMAT_UINT16;
static int
classify_mbtcp_packet(packet_info *pinfo)
{
/* see if nature of packets can be derived from src/dst ports */
/* if so, return as found */
/* */
/* XXX Update Oct 2012 - It can be difficult to determine if a packet is a query or response; some way to track */
/* the Modbus/TCP transaction ID for each pair of messages would allow for detection based on a new seq. number. */
/* Otherwise, we can stick with this method; a configurable port option has been added to allow for usage of */
/* user ports either than the default of 502. */
if (( pinfo->srcport == global_mbus_tcp_port ) && ( pinfo->destport != global_mbus_tcp_port ))
return RESPONSE_PACKET;
if (( pinfo->srcport != global_mbus_tcp_port ) && ( pinfo->destport == global_mbus_tcp_port ))
return QUERY_PACKET;
/* else, cannot classify */
return CANNOT_CLASSIFY;
}
static int
classify_mbrtu_packet(packet_info *pinfo, tvbuff_t *tvb)
{
guint8 func, len;
func = tvb_get_guint8(tvb, 1);
len = tvb_reported_length(tvb);
/* see if nature of packets can be derived from src/dst ports */
/* if so, return as found */
if (( pinfo->srcport == global_mbus_rtu_port ) && ( pinfo->destport != global_mbus_rtu_port ))
return RESPONSE_PACKET;
if (( pinfo->srcport != global_mbus_rtu_port ) && ( pinfo->destport == global_mbus_rtu_port ))
return QUERY_PACKET;
/* We may not have an Ethernet header or unique ports. */
/* Dig into these a little deeper to try to guess the message type */
/* The 'exception' bit is set, so this is a response */
if (func & 0x80) {
return RESPONSE_PACKET;
}
switch (func) {
case READ_COILS:
case READ_DISCRETE_INPUTS:
/* Only possible to get a response message of 8 bytes with Discrete or Coils */
if (len == 8) {
/* If this is, in fact, a response then the data byte count will be 3 */
/* This will correctly identify all messages except for those that are discrete or coil polls */
/* where the base address range happens to have 0x03 in the upper 16-bit address register */
if (tvb_get_guint8(tvb, 2) == 3) {
return RESPONSE_PACKET;
}
else {
return QUERY_PACKET;
}
}
else {
return RESPONSE_PACKET;
}
break;
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
case WRITE_SINGLE_COIL:
case WRITE_SINGLE_REG:
if (len == 8) {
return QUERY_PACKET;
}
else {
return RESPONSE_PACKET;
}
break;
case WRITE_MULT_REGS:
case WRITE_MULT_COILS:
if (len == 8) {
return RESPONSE_PACKET;
}
else {
return QUERY_PACKET;
}
break;
}
/* 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_DISCRETE_INPUTS, "Read Discrete Inputs" },
{ READ_HOLDING_REGS, "Read Holding Registers" },
{ READ_INPUT_REGS, "Read Input Registers" },
{ WRITE_SINGLE_COIL, "Write Single Coil" },
{ WRITE_SINGLE_REG, "Write Single Register" },
{ READ_EXCEPT_STAT, "Read Exception Status" },
{ DIAGNOSTICS, "Diagnostics" },
{ GET_COMM_EVENT_CTRS, "Get Comm. Event Counters" },
{ GET_COMM_EVENT_LOG, "Get Comm. Event Log" },
{ WRITE_MULT_COILS, "Write Multiple Coils" },
{ WRITE_MULT_REGS, "Write Multiple Registers" },
{ REPORT_SLAVE_ID, "Report Slave ID" },
{ READ_FILE_RECORD, "Read File Record" },
{ WRITE_FILE_RECORD, "Write File Record" },
{ MASK_WRITE_REG, "Mask Write Register" },
{ READ_WRITE_REG, "Read Write Register" },
{ READ_FIFO_QUEUE, "Read FIFO Queue" },
{ ENCAP_INTERFACE_TRANSP, "Encapsulated Interface Transport" },
{ UNITY_SCHNEIDER, "Unity (Schneider)" },
{ 0, NULL }
};
/* Translate exception code to string */
static const value_string exception_code_vals[] = {
{ ILLEGAL_FUNCTION, "Illegal function" },
{ ILLEGAL_ADDRESS, "Illegal data address" },
{ ILLEGAL_VALUE, "Illegal data value" },
{ SLAVE_FAILURE, "Slave device failure" },
{ ACKNOWLEDGE, "Acknowledge" },
{ SLAVE_BUSY, "Slave device busy" },
{ MEMORY_ERR, "Memory parity error" },
{ GATEWAY_UNAVAILABLE, "Gateway path unavailable" },
{ GATEWAY_TRGT_FAIL, "Gateway target device failed to respond" },
{ 0, NULL }
};
/* Translate Modbus Encapsulation Interface (MEI) code to string */
static const value_string encap_interface_code_vals[] = {
{ CANOPEN_REQ_RESP, "CANopen Request/Response " },
{ READ_DEVICE_ID, "Read Device Identification" },
{ 0, NULL }
};
/* Translate Modbus Diagnostic subfunction code to string */
static const value_string diagnostic_code_vals[] = {
{ RETURN_QUERY_DATA, "Return Query Data" },
{ RESTART_COMMUNICATION_OPTION, "Restart Communications Option" },
{ RETURN_DIAGNOSTIC_REGISTER, "Return Diagnostic Register" },
{ CHANGE_ASCII_INPUT_DELIMITER, "Change ASCII Input Delimiter" },
{ FORCE_LISTEN_ONLY_MODE, "Force Listen Only Mode" },
{ CLEAR_COUNTERS_AND_DIAG_REG, "Clear Counters and Diagnostic Register" },
{ RETURN_BUS_MESSAGE_COUNT, "Return Bus Message Count" },
{ RETURN_BUS_COMM_ERROR_COUNT, "Return Bus Communication Error Count" },
{ RETURN_BUS_EXCEPTION_ERROR_COUNT, "Return Bus Exception Error Count" },
{ RETURN_SLAVE_MESSAGE_COUNT, "Return Slave Message Count" },
{ RETURN_SLAVE_NO_RESPONSE_COUNT, "Return Slave No Response Count" },
{ RETURN_SLAVE_NAK_COUNT, "Return Slave NAK Count" },
{ RETURN_SLAVE_BUSY_COUNT, "Return Slave Busy Count" },
{ RETURN_BUS_CHAR_OVERRUN_COUNT, "Return Bus Character Overrun Count" },
{ CLEAR_OVERRUN_COUNTER_AND_FLAG, "Clear Overrun Counter and Flag" },
{ 0, NULL }
};
static const value_string diagnostic_restart_communication_option_vals[] = {
{ 0, "Leave Log" },
{ 0xFF, "Clear Log" },
{ 0, NULL }
};
/* Translate read device code to string */
static const value_string read_device_id_vals[] = {
{ 1, "Basic Device Identification" },
{ 2, "Regular Device Identification" },
{ 3, "Extended Device Identification" },
{ 4, "Specific Identification Object" },
{ 0, NULL }
};
/* Translate read device code to string */
static const value_string object_id_vals[] = {
{ 0, "VendorName" },
{ 1, "ProductCode" },
{ 2, "MajorMinorRevision" },
{ 3, "VendorURL" },
{ 4, "ProductName" },
{ 5, "ModelName" },
{ 6, "UserApplicationName" },
{ 0, NULL }
};
static const value_string conformity_level_vals[] = {
{ 0x01, "Basic Device Identification (stream)" },
{ 0x02, "Regular Device Identification (stream)" },
{ 0x03, "Extended Device Identification (stream)" },
{ 0x81, "Basic Device Identification (stream and individual)" },
{ 0x82, "Regular Device Identification (stream and individual)" },
{ 0x83, "Extended Device Identification (stream and individual)" },
{ 0, NULL }
};
static const enum_val_t mbus_register_format[] = {
{ "UINT16 ", "UINT16 ", MODBUS_PREF_REGISTER_FORMAT_UINT16 },
{ "INT16 ", "INT16 ", MODBUS_PREF_REGISTER_FORMAT_INT16 },
{ "UINT32 ", "UINT32 ", MODBUS_PREF_REGISTER_FORMAT_UINT32 },
{ "INT32 ", "INT32 ", MODBUS_PREF_REGISTER_FORMAT_INT32 },
{ "IEEE FLT ", "IEEE FLT ", MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT },
{ "MODICON FLT", "MODICON FLT", MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT },
{ NULL, NULL, 0 }
};
/* Code to dissect Modbus/TCP packets */
static int
dissect_mbtcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
/* Set up structures needed to add the protocol subtree and manage it */
proto_item *mi;
proto_tree *mbtcp_tree;
int offset, packet_type;
tvbuff_t *next_tvb;
const char *func_string = "";
const char *pkt_type_str = "";
const char *err_str = "";
guint16 transaction_id, protocol_id, len;
guint8 unit_id, function_code, exception_code, subfunction_code;
/* Make entries in Protocol column on summary display */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP");
col_clear(pinfo->cinfo, COL_INFO);
transaction_id = tvb_get_ntohs(tvb, 0);
protocol_id = tvb_get_ntohs(tvb, 2);
len = tvb_get_ntohs(tvb, 4);
unit_id = tvb_get_guint8(tvb, 6);
function_code = tvb_get_guint8(tvb, 7) & 0x7F;
offset = 0;
/* "Request" or "Response" */
packet_type = classify_mbtcp_packet(pinfo);
switch ( packet_type ) {
case QUERY_PACKET :
pkt_type_str="Query";
break;
case RESPONSE_PACKET :
pkt_type_str="Response";
break;
case CANNOT_CLASSIFY :
err_str="Unable to classify as query or response.";
pkt_type_str="unknown";
break;
default :
break;
}
/* Find exception - last bit set in function code */
if (tvb_get_guint8(tvb, 7) & 0x80) {
exception_code = tvb_get_guint8(tvb, offset + 8);
}
else {
exception_code = 0;
}
if ((function_code == ENCAP_INTERFACE_TRANSP) && (exception_code == 0)) {
func_string = val_to_str_const(tvb_get_guint8(tvb, offset + 8), encap_interface_code_vals, "Encapsulated Interface Transport");
subfunction_code = 1;
}
else if ((function_code == DIAGNOSTICS) && (exception_code == 0)) {
func_string = val_to_str_const(tvb_get_ntohs(tvb, offset + 8), diagnostic_code_vals, "Diagnostics");
subfunction_code = 1;
}
else {
func_string = val_to_str(function_code, function_code_vals, "Unknown function (%d)");
subfunction_code = 0;
}
if ( exception_code != 0 )
err_str="Exception returned ";
/* Make entries in Info column on summary display */
if (subfunction_code == 0) {
if (strlen(err_str) > 0) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Trans: %5u; Unit: %3u, Func: %3u: %s. %s",
pkt_type_str, transaction_id, unit_id,
function_code, func_string, err_str);
}
else {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Trans: %5u; Unit: %3u, Func: %3u: %s",
pkt_type_str, transaction_id, unit_id,
function_code, func_string);
}
}
else {
if (strlen(err_str) > 0) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Trans: %5u; Unit: %3u, Func: %3u/%3u: %s. %s",
pkt_type_str, transaction_id, unit_id,
function_code, subfunction_code, func_string, err_str);
}
else {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Trans: %5u; Unit: %3u, Func: %3u/%3u: %s",
pkt_type_str, transaction_id, unit_id,
function_code, subfunction_code, func_string);
}
}
/* Create protocol tree */
mi = proto_tree_add_protocol_format(tree, proto_mbtcp, tvb, offset,
len+6, "Modbus/TCP");
mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp);
if (packet_type == CANNOT_CLASSIFY)
expert_add_info(pinfo, mi, &ei_mbtcp_cannot_classify);
/* Add items to protocol tree specific to Modbus/TCP */
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2, transaction_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2, protocol_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2, len);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_unitid, tvb, offset + 6, 1, unit_id);
/* dissect the Modbus PDU */
next_tvb = tvb_new_subset_length( tvb, offset+7, len-1);
/* Continue with dissection of Modbus data payload following Modbus/TCP frame */
if( tvb_reported_length_remaining(tvb, offset) > 0 )
call_dissector_with_data(modbus_handle, next_tvb, pinfo, tree, &packet_type);
return tvb_captured_length(tvb);
}
/* Code to dissect Modbus RTU over TCP packets */
static int
dissect_mbrtu_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
/* Set up structures needed to add the protocol subtree and manage it */
proto_item *mi;
proto_tree *mbrtu_tree;
int offset, packet_type;
tvbuff_t *next_tvb;
const char *func_string = "";
const char *pkt_type_str = "";
const char *err_str = "";
guint16 len, calc_crc16;
guint8 unit_id, function_code, exception_code, subfunction_code;
/* Make entries in Protocol column on summary display */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus RTU");
col_clear(pinfo->cinfo, COL_INFO);
len = tvb_reported_length(tvb);
unit_id = tvb_get_guint8(tvb, 0);
function_code = tvb_get_guint8(tvb, 1) & 0x7F;
offset = 0;
/* "Request" or "Response" */
packet_type = classify_mbrtu_packet(pinfo, tvb);
switch ( packet_type ) {
case QUERY_PACKET :
pkt_type_str="Query";
break;
case RESPONSE_PACKET :
pkt_type_str="Response";
break;
case CANNOT_CLASSIFY :
err_str="Unable to classify as query or response.";
pkt_type_str="unknown";
break;
default :
break;
}
/* Find exception - last bit set in function code */
if (tvb_get_guint8(tvb, 1) & 0x80) {
exception_code = tvb_get_guint8(tvb, offset + 2);
}
else {
exception_code = 0;
}
if ((function_code == ENCAP_INTERFACE_TRANSP) && (exception_code == 0)) {
func_string = val_to_str_const(tvb_get_guint8(tvb, offset + 2), encap_interface_code_vals, "Encapsulated Interface Transport");
subfunction_code = 1;
}
else if ((function_code == DIAGNOSTICS) && (exception_code == 0)) {
func_string = val_to_str_const(tvb_get_ntohs(tvb, offset + 2), diagnostic_code_vals, "Diagnostics");
subfunction_code = 1;
}
else {
func_string = val_to_str(function_code, function_code_vals, "Unknown function (%d)");
subfunction_code = 0;
}
if ( exception_code != 0 )
err_str="Exception returned ";
/* Make entries in Info column on summary display */
if (subfunction_code == 0) {
if (strlen(err_str) > 0) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Unit: %3u, Func: %3u: %s. %s",
pkt_type_str, unit_id,
function_code, func_string, err_str);
}
else {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Unit: %3u, Func: %3u: %s",
pkt_type_str, unit_id,
function_code, func_string);
}
}
else {
if (strlen(err_str) > 0) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Unit: %3u, Func: %3u/%3u: %s. %s",
pkt_type_str, unit_id,
function_code, subfunction_code, func_string, err_str);
}
else {
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s: Unit: %3u, Func: %3u/%3u: %s",
pkt_type_str, unit_id,
function_code, subfunction_code, func_string);
}
}
/* Create protocol tree */
mi = proto_tree_add_protocol_format(tree, proto_mbrtu, tvb, offset,
len, "Modbus RTU");
mbrtu_tree = proto_item_add_subtree(mi, ett_mbrtu);
/* Add items to protocol tree specific to Modbus RTU */
proto_tree_add_uint(mbrtu_tree, hf_mbrtu_unitid, tvb, offset, 1, unit_id);
/* CRC validation */
if (mbrtu_crc)
{
calc_crc16 = crc16_plain_tvb_offset_seed(tvb, offset, len-2, 0xFFFF);
proto_tree_add_checksum(mbrtu_tree, tvb, len-2, hf_mbrtu_crc16, -1, &ei_mbrtu_crc16_incorrect, pinfo, g_htons(calc_crc16), ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
}
else
{
proto_tree_add_checksum(mbrtu_tree, tvb, len-2, hf_mbrtu_crc16, -1, &ei_mbrtu_crc16_incorrect, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
}
/* when determining payload length, make sure to ignore the unit ID header & CRC-16 footer bytes */
len = len - 3;
/* dissect the Modbus PDU */
next_tvb = tvb_new_subset_length( tvb, offset+1, len);
/* Continue with dissection of Modbus data payload following Modbus RTU frame */
if( tvb_reported_length_remaining(tvb, offset) > 0 )
call_dissector_with_data(modbus_handle, next_tvb, pinfo, tree, &packet_type);
return tvb_captured_length(tvb);
}
/* Return length of Modbus/TCP message */
static guint
get_mbtcp_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
{
guint16 plen;
/*
* Get the length of the data from the encapsulation header.
*/
plen = tvb_get_ntohs(tvb, offset + 4);
/*
* That length doesn't include the encapsulation header itself;
* add that in.
*/
return plen + 6;
}
/* Return length of Modbus RTU over TCP message */
static guint
get_mbrtu_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb,
int offset _U_, void *data _U_)
{
int packet_type;
guint8 function_code;
function_code = tvb_get_guint8(tvb, 1);
/* Modbus RTU requests do not contain a length field but they are typically a consistent size.
Responses do contain a usable 'length' byte at offset 2
XXX - Note that only some function codes are supported by this lookup function;
the rest can be added as pcap examples are made available */
/* Determine "Query" or "Response" */
packet_type = classify_mbrtu_packet(pinfo, tvb);
switch ( packet_type ) {
case QUERY_PACKET :
switch (function_code) {
case READ_COILS: /* Query messages of these types are always 8 bytes */
case READ_DISCRETE_INPUTS:
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
case WRITE_SINGLE_COIL:
case WRITE_SINGLE_REG:
return 8;
break;
case WRITE_MULT_REGS:
case WRITE_MULT_COILS:
return tvb_get_guint8(tvb, 6) + 9; /* Reported size does not include 2 header, 4 FC15/16-specific, 1 size byte or 2 CRC16 bytes */
break;
default :
return tvb_captured_length(tvb); /* Fall back on tvb length */
break;
}
case RESPONSE_PACKET :
/* The 'exception' bit is set, so this is a 5-byte response */
if (function_code & 0x80) {
return 5;
}
switch (function_code) {
case READ_COILS:
case READ_DISCRETE_INPUTS:
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
case WRITE_SINGLE_COIL:
case WRITE_SINGLE_REG:
return tvb_get_guint8(tvb, 2) + 5; /* Reported size does not include 2 header, 1 size byte, 2 CRC16 bytes */
break;
case WRITE_MULT_REGS: /* Response messages of FC15/16 are always 8 bytes */
case WRITE_MULT_COILS:
return 8;
break;
default :
return tvb_captured_length(tvb); /* Fall back on tvb length */
break;
}
case CANNOT_CLASSIFY :
default :
return tvb_captured_length(tvb); /* Fall back on tvb length */
break;
}
}
/* Code to dissect Modbus/TCP messages */
static int
dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
/* Make sure there's at least enough data to determine it's a Modbus TCP packet */
if (!tvb_bytes_exist(tvb, 0, 8))
return 0;
/* check that it actually looks like Modbus/TCP */
/* protocol id == 0 */
if(tvb_get_ntohs(tvb, 2) != 0 ){
return 0;
}
/* length is at least 2 (unit_id + function_code) */
if(tvb_get_ntohs(tvb, 4) < 2 ){
return 0;
}
/* build up protocol tree and iterate over multiple packets */
tcp_dissect_pdus(tvb, pinfo, tree, mbtcp_desegment, 6,
get_mbtcp_pdu_len, dissect_mbtcp_pdu, data);
return tvb_captured_length(tvb);
}
/* Code to dissect Modbus RTU over TCP messages */
static int
dissect_mbrtu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
/* Make sure there's at least enough data to determine it's a Modbus packet */
/* 5 bytes is the smallest possible valid message (exception response) */
if (!tvb_bytes_exist(tvb, 0, 5))
return 0;
/* For Modbus RTU mode, confirm that the first byte is a valid address (non-zero), */
/* so we can eliminate false-posititves on Modbus TCP messages loaded as RTU */
if(tvb_get_guint8(tvb, 0) == 0 )
return 0;
/* build up protocol tree and iterate over multiple packets */
tcp_dissect_pdus(tvb, pinfo, tree, mbrtu_desegment, 5,
get_mbrtu_pdu_len, dissect_mbrtu_pdu, data);
return tvb_captured_length(tvb);
}
static int
dissect_mbrtu_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
/* Make sure there's at least enough data to determine it's a Modbus packet */
/* 5 bytes is the smallest possible valid message (exception response) */
if (tvb_reported_length(tvb) < 5)
return 0;
return dissect_mbrtu_pdu(tvb, pinfo, tree, data);
}
/* Code to allow further dissection of Modbus data payload */
/* Common to both Modbus/TCP and Modbus RTU dissectors */
static void
dissect_modbus_data(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint8 function_code,
gint payload_start, gint payload_len, gint register_format, guint16 reg_base)
{
gint reported_len, data_offset;
gint16 data16s;
gint32 data32s;
guint16 data16, modflt_lo, modflt_hi, reg_num=reg_base;
guint32 data32, modflt_comb;
gfloat data_float, modfloat;
proto_item *register_item = NULL;
tvbuff_t *next_tvb;
reported_len = tvb_reported_length_remaining(tvb, payload_start);
data_offset = 0;
if ( payload_start < 0 || ( payload_len + payload_start ) == 0 )
return;
/* If calculated length from remaining tvb data != bytes in packet, do not attempt to decode */
if ( payload_len != reported_len ) {
proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, reported_len, ENC_NA);
return;
}
/* If data type of payload is Holding or Input registers */
/* AND */
/* if payload length is not a multiple of 4, don't attempt to decode anything in 32-bit format */
if ((function_code == READ_HOLDING_REGS) || (function_code == READ_INPUT_REGS) || (function_code == WRITE_MULT_REGS)) {
if ((payload_len % 4 != 0) && ( (register_format == MODBUS_PREF_REGISTER_FORMAT_UINT32) ||
(register_format == MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT) ||
(register_format == MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT) ) ) {
register_item = proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, payload_len, ENC_NA);
expert_add_info(pinfo, register_item, &ei_modbus_data_decode);
return;
}
}
/* Build a new tvb containing just the data payload */
next_tvb = tvb_new_subset(tvb, payload_start, payload_len, reported_len);
switch ( function_code ) {
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
case WRITE_MULT_REGS:
while (data_offset < payload_len) {
/* Use "Preferences" options to determine decoding format of register data, as no format is implied by the protocol itself. */
/* Based on a standard register size of 16-bits, use decoding format preference to step through each register and display */
/* it in an appropriate fashion. */
switch (register_format) {
case MODBUS_PREF_REGISTER_FORMAT_UINT16: /* Standard-size unsigned integer 16-bit register */
data16 = tvb_get_ntohs(next_tvb, data_offset);
proto_tree_add_uint_format(tree, hf_modbus_reg16, next_tvb, data_offset, 2, reg_num,
"Register %u (UINT16): %u", reg_num, data16);
data_offset += 2;
reg_num += 1;
break;
case MODBUS_PREF_REGISTER_FORMAT_INT16: /* Standard-size signed integer 16-bit register */
data16s = tvb_get_ntohs(next_tvb, data_offset);
proto_tree_add_uint_format(tree, hf_modbus_reg16, next_tvb, data_offset, 2, reg_num,
"Register %u (INT16): %d", reg_num, data16s);
data_offset += 2;
reg_num += 1;
break;
case MODBUS_PREF_REGISTER_FORMAT_UINT32: /* Double-size unsigned integer 2 x 16-bit registers */
data32 = tvb_get_ntohl(next_tvb, data_offset);
proto_tree_add_uint_format(tree, hf_modbus_reg32, next_tvb, data_offset, 4, reg_num,
"Register %u (UINT32): %u", reg_num, data32);
data_offset += 4;
reg_num += 2;
break;
case MODBUS_PREF_REGISTER_FORMAT_INT32: /* Double-size signed integer 2 x 16-bit registers */
data32s = tvb_get_ntohl(next_tvb, data_offset);
proto_tree_add_uint_format(tree, hf_modbus_reg32, next_tvb, data_offset, 4, reg_num,
"Register %u (INT32): %d", reg_num, data32s);
data_offset += 4;
reg_num += 2;
break;
case MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT: /* IEEE Floating Point, 2 x 16-bit registers */
data_float = tvb_get_ntohieee_float(next_tvb, data_offset);
proto_tree_add_uint_format(tree, hf_modbus_reg32, next_tvb, data_offset, 4, reg_num,
"Register %u (IEEE Float): %f", reg_num, data_float);
data_offset += 4;
reg_num += 2;
break;
case MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT: /* Modicon Floating Point (word-swap), 2 x 16-bit registers */
/* Modicon-style Floating Point values are stored in reverse-word order. */
/* ie: a standard IEEE float value 59.991459 is equal to 0x426ff741 */
/* while the Modicon equivalent to this value is 0xf741426f */
/* To re-assemble a proper IEEE float, we must retrieve the 2 x 16-bit words, bit-shift the */
/* "hi" component by 16-bits and then OR them together into a combined 32-bit int. */
/* Following that operation, use some memcpy magic to copy the 4 raw data bytes from the */
/* 32-bit integer into a standard float. Not sure if there is a cleaner way possible using */
/* the Wireshark libraries, but this seems to work OK. */
modflt_lo = tvb_get_ntohs(next_tvb, data_offset);
modflt_hi = tvb_get_ntohs(next_tvb, data_offset+2);
modflt_comb = (guint32)(modflt_hi<<16) | modflt_lo;
memcpy(&modfloat, &modflt_comb, 4);
proto_tree_add_uint_format(tree, hf_modbus_reg32, next_tvb, data_offset, 4, reg_num,
"Register %u (Modicon Float): %f", reg_num, modfloat);
data_offset += 4;
reg_num += 2;
break;
default:
/* Avoid any chance of an infinite loop */
data_offset = payload_len;
break;
} /* register format switch */
} /* while loop */
break;
default:
if ( ! dissector_try_string(modbus_data_dissector_table, "data", next_tvb, pinfo, tree, NULL) )
proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, payload_len, ENC_NA);
break;
}
}
/* Code to dissect Modbus request message */
static int
dissect_modbus_request(tvbuff_t *tvb, packet_info *pinfo, proto_tree *modbus_tree, guint8 function_code, gint payload_start, gint payload_len)
{
proto_tree *group_tree;
gint byte_cnt, group_offset, ii;
gint register_format = MODBUS_PREF_REGISTER_FORMAT_UINT16; /* Default value for register formatting.. */
guint8 mei_code;
guint16 reg_base=0, diagnostic_code;
guint32 group_byte_cnt, group_word_cnt;
modbus_conversation *conv;
/* See if we have any context */
conv = (modbus_conversation *)p_get_proto_data(wmem_file_scope(), pinfo, proto_modbus, 0);
if (conv) {
register_format = conv->register_format;
}
switch (function_code) {
case READ_COILS:
case READ_DISCRETE_INPUTS:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
break;
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
break;
case WRITE_SINGLE_COIL:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 1, register_format, reg_base);
proto_tree_add_item(modbus_tree, hf_modbus_padding, tvb, payload_start + 3, 1, ENC_NA);
break;
case WRITE_SINGLE_REG:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 2, register_format, reg_base);
break;
case READ_EXCEPT_STAT:
/* Do Nothing */
break;
case DIAGNOSTICS:
diagnostic_code = tvb_get_ntohs(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_diag_sf, tvb, payload_start, 2, diagnostic_code);
switch(diagnostic_code)
{
case RETURN_QUERY_DATA:
if (payload_len > 2)
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_query_data_request, tvb, payload_start+2, payload_len-2, ENC_NA);
break;
case RESTART_COMMUNICATION_OPTION:
proto_tree_add_item(modbus_tree, hf_modbus_diag_restart_communication_option, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case CHANGE_ASCII_INPUT_DELIMITER:
proto_tree_add_item(modbus_tree, hf_modbus_diag_ascii_input_delimiter, tvb, payload_start+2, 1, ENC_BIG_ENDIAN);
break;
case RETURN_DIAGNOSTIC_REGISTER: /* 00 00 Data Field */
case FORCE_LISTEN_ONLY_MODE: /* 00 00 Data Field */
case CLEAR_COUNTERS_AND_DIAG_REG: /* 00 00 Data Field */
case RETURN_BUS_MESSAGE_COUNT: /* 00 00 Data Field */
case RETURN_BUS_COMM_ERROR_COUNT: /* 00 00 Data Field */
case RETURN_BUS_EXCEPTION_ERROR_COUNT: /* 00 00 Data Field */
case RETURN_SLAVE_MESSAGE_COUNT: /* 00 00 Data Field */
case RETURN_SLAVE_NO_RESPONSE_COUNT: /* 00 00 Data Field */
case RETURN_SLAVE_NAK_COUNT: /* 00 00 Data Field */
case RETURN_SLAVE_BUSY_COUNT: /* 00 00 Data Field */
case RETURN_BUS_CHAR_OVERRUN_COUNT: /* 00 00 Data Field */
case CLEAR_OVERRUN_COUNTER_AND_FLAG:
default:
if (payload_len > 2)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start+2, payload_len-2, register_format, reg_base);
break;
}
break;
case WRITE_MULT_COILS:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
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);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 5, byte_cnt, register_format, reg_base);
break;
case WRITE_MULT_REGS:
reg_base = tvb_get_ntohs(tvb, payload_start);
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
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);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 5, byte_cnt, register_format, reg_base);
break;
case READ_FILE_RECORD:
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 (ii = 0; ii < byte_cnt / 7; ii++) {
group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, 7,
ett_group_hdr, NULL, "Group %u", ii);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN);
proto_tree_add_item(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, ENC_BIG_ENDIAN);
group_offset += 7;
}
break;
case WRITE_FILE_RECORD:
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;
ii = 0;
while (byte_cnt > 0) {
group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5);
group_byte_cnt = (2 * group_word_cnt) + 7;
group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset,
group_byte_cnt, ett_group_hdr, NULL, "Group %u", ii);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN);
proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, group_word_cnt);
dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 7, group_byte_cnt - 7, register_format, reg_base);
group_offset += group_byte_cnt;
byte_cnt -= group_byte_cnt;
ii++;
}
break;
case MASK_WRITE_REG:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN);
break;
case READ_WRITE_REG:
proto_tree_add_item(modbus_tree, hf_modbus_readref, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_readwordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_writeref, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_writewordcnt, tvb, payload_start + 6, 2, ENC_BIG_ENDIAN);
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);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 9, byte_cnt, register_format, reg_base);
break;
case READ_FIFO_QUEUE:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
break;
case ENCAP_INTERFACE_TRANSP:
proto_tree_add_item(modbus_tree, hf_modbus_mei, tvb, payload_start, 1, ENC_BIG_ENDIAN);
mei_code = tvb_get_guint8(tvb, payload_start);
switch (mei_code)
{
case READ_DEVICE_ID:
proto_tree_add_item(modbus_tree, hf_modbus_read_device_id, tvb, payload_start+1, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_object_id, tvb, payload_start+2, 1, ENC_BIG_ENDIAN);
break;
case CANOPEN_REQ_RESP:
/* CANopen protocol not part of the Modbus/TCP specification */
default:
if (payload_len > 1)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len-1, register_format, reg_base);
break;
}
break;
case REPORT_SLAVE_ID:
default:
if (payload_len > 0)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, register_format, reg_base);
break;
} /* Function Code */
return tvb_captured_length(tvb);
}
/* Code to dissect Modbus Response message */
static int
dissect_modbus_response(tvbuff_t *tvb, packet_info *pinfo, proto_tree *modbus_tree, guint8 function_code, gint payload_start, gint payload_len)
{
proto_tree *group_tree, *event_tree, *event_item_tree, *device_objects_tree, *device_objects_item_tree;
proto_item *mei;
gint byte_cnt, group_offset, event_index, object_index, object_len, num_objects, ii;
gint register_format = MODBUS_PREF_REGISTER_FORMAT_UINT16; /* Default value for register formatting.. */
guint8 object_type, mei_code, event_code;
guint16 reg_base=0, diagnostic_code;
guint32 group_byte_cnt, group_word_cnt;
/* Conversation tracking */
proto_item *request_frame_item;
modbus_conversation *conv;
guint8 req_function_code;
guint32 req_frame_num;
gboolean request_found = FALSE;
modbus_request_info_t *request_data;
/* See if we have any context */
conv = (modbus_conversation *)p_get_proto_data(wmem_file_scope(), pinfo, proto_modbus, 0);
if (conv) {
wmem_list_frame_t *frame = wmem_list_head(conv->modbus_request_frame_data);
/* Step backward through all logged instances of request frames, looking for a request frame number that
occurred immediately prior to current frame number that has a matching function code */
while (frame && !request_found) {
request_data = (modbus_request_info_t *)wmem_list_frame_data(frame);
req_frame_num = request_data->fnum;
req_function_code = request_data->function_code;
if ((pinfo->num > req_frame_num) && (req_function_code == function_code)) {
request_frame_item = proto_tree_add_uint(modbus_tree, hf_modbus_request_frame, tvb, 0, 0, req_frame_num);
reg_base = request_data->base_address;
PROTO_ITEM_SET_GENERATED(request_frame_item);
request_found = TRUE;
}
frame = wmem_list_frame_next(frame);
}
register_format = conv->register_format;
} /* conv */
switch (function_code) {
case READ_COILS:
case READ_DISCRETE_INPUTS:
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, register_format, reg_base);
break;
case READ_HOLDING_REGS:
case READ_INPUT_REGS:
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, register_format, reg_base);
break;
case WRITE_SINGLE_COIL:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 1, register_format, reg_base);
proto_tree_add_item(modbus_tree, hf_modbus_padding, tvb, payload_start + 3, 1, ENC_NA);
break;
case WRITE_SINGLE_REG:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 2, register_format, reg_base);
break;
case READ_EXCEPT_STAT:
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, 1, register_format, reg_base);
break;
case DIAGNOSTICS:
diagnostic_code = tvb_get_ntohs(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_diag_sf, tvb, payload_start, 2, diagnostic_code);
switch(diagnostic_code)
{
case RETURN_QUERY_DATA: /* Echo of Request */
if (payload_len > 2)
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_query_data_echo, tvb, payload_start+2, payload_len-2, ENC_NA);
break;
case RESTART_COMMUNICATION_OPTION: /* Echo of Request */
proto_tree_add_item(modbus_tree, hf_modbus_diag_restart_communication_option, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_DIAGNOSTIC_REGISTER:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_diag_register, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case CHANGE_ASCII_INPUT_DELIMITER: /* XXX - Do we expect this to ever be a response? */
proto_tree_add_item(modbus_tree, hf_modbus_diag_ascii_input_delimiter, tvb, payload_start+2, 1, ENC_BIG_ENDIAN);
break;
case CLEAR_COUNTERS_AND_DIAG_REG: /* Echo of Request */
proto_tree_add_item(modbus_tree, hf_modbus_diag_clear_ctr_diag_reg, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_BUS_MESSAGE_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_message_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_BUS_COMM_ERROR_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_comm_error_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_BUS_EXCEPTION_ERROR_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_exception_error_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_SLAVE_MESSAGE_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_message_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_SLAVE_NO_RESPONSE_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_no_slave_response_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_SLAVE_NAK_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_nak_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_SLAVE_BUSY_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_busy_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case RETURN_BUS_CHAR_OVERRUN_COUNT:
proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_char_overrun_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case CLEAR_OVERRUN_COUNTER_AND_FLAG: /* Echo of Request */
case FORCE_LISTEN_ONLY_MODE: /* No response anticipated */
default:
if (payload_len > 2)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start+2, payload_len-2, register_format, reg_base);
break;
} /* diagnostic_code */
break;
case GET_COMM_EVENT_CTRS:
proto_tree_add_item(modbus_tree, hf_modbus_status, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_event_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN);
break;
case GET_COMM_EVENT_LOG:
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_item(modbus_tree, hf_modbus_status, tvb, payload_start+1, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_event_count, tvb, payload_start+3, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_message_count, tvb, payload_start+5, 2, ENC_BIG_ENDIAN);
if (byte_cnt-6 > 0) {
byte_cnt -= 6;
event_index = 0;
event_tree = proto_tree_add_subtree(modbus_tree, tvb, payload_start+7, byte_cnt, ett_events, NULL, "Events");
while (byte_cnt > 0) {
event_code = tvb_get_guint8(tvb, payload_start+7+event_index);
if (event_code == 0) {
proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Initiated Communication Restart");
}
else if (event_code == 4) {
proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Entered Listen Only Mode");
}
else if (event_code & REMOTE_DEVICE_RECV_EVENT_MASK) {
mei = proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1,
event_code, "Receive Event: 0x%02X", event_code);
event_item_tree = proto_item_add_subtree(mei, ett_events_recv);
/* add subtrees to describe each event bit */
proto_tree_add_item(event_item_tree, hf_modbus_event_recv_comm_err,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_recv_char_over,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_recv_lo_mode,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_recv_broadcast,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
}
else if ((event_code & REMOTE_DEVICE_SEND_EVENT_MASK) == REMOTE_DEVICE_SEND_EVENT_VALUE) {
mei = proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1,
event_code, "Send Event: 0x%02X", event_code);
event_item_tree = proto_item_add_subtree(mei, ett_events_send);
/* add subtrees to describe each event bit */
proto_tree_add_item(event_item_tree, hf_modbus_event_send_read_ex,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_abort_ex,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_busy_ex,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_nak_ex,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_send_write_timeout,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
proto_tree_add_item(event_item_tree, hf_modbus_event_send_lo_mode,
tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN );
}
else {
proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Unknown Event");
}
byte_cnt--;
event_index++;
}
}
break;
case WRITE_MULT_COILS:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
break;
case WRITE_MULT_REGS:
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
break;
case READ_FILE_RECORD:
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;
ii = 0;
while (byte_cnt > 0) {
group_byte_cnt = (guint32)tvb_get_guint8(tvb, group_offset);
group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, group_byte_cnt + 1,
ett_group_hdr, NULL, "Group %u", ii);
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, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 2, group_byte_cnt - 1, register_format, reg_base);
group_offset += (group_byte_cnt + 1);
byte_cnt -= (group_byte_cnt + 1);
ii++;
}
break;
case WRITE_FILE_RECORD: /* Normal response is echo of request */
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;
ii = 0;
while (byte_cnt > 0) {
group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5);
group_byte_cnt = (2 * group_word_cnt) + 7;
group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset,
group_byte_cnt, ett_group_hdr, NULL, "Group %u", ii);
proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN);
proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, group_word_cnt);
dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 7, group_byte_cnt - 7, register_format, reg_base);
group_offset += group_byte_cnt;
byte_cnt -= group_byte_cnt;
ii++;
}
break;
case MASK_WRITE_REG: /* Normal response is echo of request */
proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN);
break;
case READ_WRITE_REG:
byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start);
proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, register_format, reg_base);
break;
case READ_FIFO_QUEUE:
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, ENC_BIG_ENDIAN);
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 4, byte_cnt - 2, register_format, reg_base);
break;
case ENCAP_INTERFACE_TRANSP:
proto_tree_add_item(modbus_tree, hf_modbus_mei, tvb, payload_start, 1, ENC_BIG_ENDIAN);
mei_code = tvb_get_guint8(tvb, payload_start);
switch (mei_code)
{
case READ_DEVICE_ID:
proto_tree_add_item(modbus_tree, hf_modbus_read_device_id, tvb, payload_start+1, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_conformity_level, tvb, payload_start+2, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_more_follows, tvb, payload_start+3, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(modbus_tree, hf_modbus_next_object_id, tvb, payload_start+4, 1, ENC_BIG_ENDIAN);
num_objects = tvb_get_guint8(tvb, payload_start+5);
proto_tree_add_uint(modbus_tree, hf_modbus_num_objects, tvb, payload_start+5, 1, num_objects);
device_objects_tree = proto_tree_add_subtree(modbus_tree, tvb, payload_start+6, payload_len-6,
ett_device_id_objects, NULL, "Objects");
object_index = 0;
for (ii = 0; ii < num_objects; ii++)
{
/* add each "object item" as its own subtree */
/* compute length of object */
object_type = tvb_get_guint8(tvb, payload_start+6+object_index);
object_len = tvb_get_guint8(tvb, payload_start+6+object_index+1);
device_objects_item_tree = proto_tree_add_subtree_format(device_objects_tree, tvb, payload_start+6+object_index, 2+object_len,
ett_device_id_object_items, NULL, "Object #%d", ii+1);
proto_tree_add_item(device_objects_item_tree, hf_modbus_object_id, tvb, payload_start+6+object_index, 1, ENC_BIG_ENDIAN);
object_index++;
proto_tree_add_uint(device_objects_item_tree, hf_modbus_list_object_len, tvb, payload_start+6+object_index, 1, object_len);
object_index++;
if (object_type < 7)
{
proto_tree_add_item(device_objects_item_tree, hf_modbus_object_str_value, tvb, payload_start+6+object_index, object_len, ENC_ASCII|ENC_NA);
}
else
{
if (object_len > 0)
proto_tree_add_item(device_objects_item_tree, hf_modbus_object_value, tvb, payload_start+6+object_index, object_len, ENC_NA);
}
object_index += object_len;
} /* for ii */
break;
case CANOPEN_REQ_RESP:
/* CANopen protocol not part of the Modbus/TCP specification */
default:
if (payload_len > 1)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len-1, register_format, reg_base);
break;
} /* mei_code */
break;
case REPORT_SLAVE_ID:
default:
if (payload_len > 0)
dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, register_format, reg_base);
break;
} /* function code */
return tvb_captured_length(tvb);
}
/* Dissect the Modbus Payload. Called from either Modbus/TCP or Modbus RTU Dissector */
static int
dissect_modbus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
proto_tree *modbus_tree;
proto_item *mi;
int offset = 0;
int* packet_type = (int*)data;
gint payload_start, payload_len, len;
guint8 function_code, exception_code;
/* Reject the packet if data passed from the mbrtu or mbtcp dissector is NULL */
if (packet_type == NULL)
return 0;
len = tvb_captured_length(tvb);
/* If the packet is zero-length, we should not attempt to dissect any further */
if (len == 0)
return 0;
/* Add items to protocol tree specific to Modbus */
mi = proto_tree_add_protocol_format(tree, proto_modbus, tvb, offset, len, "Modbus");
modbus_tree = proto_item_add_subtree(mi, ett_modbus_hdr);
function_code = tvb_get_guint8(tvb, offset) & 0x7F;
proto_tree_add_item(modbus_tree, hf_modbus_functioncode, tvb, offset, 1, ENC_BIG_ENDIAN);
/* Conversation support */
if (!pinfo->fd->flags.visited) {
conversation_t *conversation = NULL;
modbus_conversation *modbus_conv_data = NULL;
/* Find a conversation, create a new if no one exists */
conversation = find_or_create_conversation(pinfo);
modbus_conv_data = (modbus_conversation *)conversation_get_proto_data(conversation, proto_modbus);
if (modbus_conv_data == NULL){
modbus_conv_data = wmem_new(wmem_file_scope(), modbus_conversation);
modbus_conv_data->modbus_request_frame_data = wmem_list_new(wmem_file_scope());
modbus_conv_data->register_format = global_mbus_register_format;
conversation_add_proto_data(conversation, proto_modbus, (void *)modbus_conv_data);
}
p_add_proto_data(wmem_file_scope(), pinfo, proto_modbus, 0, modbus_conv_data);
if (*packet_type == QUERY_PACKET) {
/*create the modbus_request frame. It holds the request information.*/
modbus_request_info_t *frame_ptr = wmem_new(wmem_file_scope(), modbus_request_info_t);
/* load information into the modbus request frame */
frame_ptr->fnum = pinfo->num;
frame_ptr->function_code = function_code;
frame_ptr->base_address = tvb_get_ntohs(tvb, 1);
frame_ptr->num_reg = tvb_get_ntohs(tvb, 3);
wmem_list_prepend(modbus_conv_data->modbus_request_frame_data, frame_ptr);
}
} /* !visited */
/* Find exception - last bit set in function code */
if (tvb_get_guint8(tvb, offset) & 0x80 ) {
exception_code = tvb_get_guint8(tvb, offset+1);
}
else {
exception_code = 0;
}
payload_start = offset + 1;
payload_len = len - 1;
if (exception_code != 0) {
proto_item_set_text(mi, "Function %u: %s. Exception: %s",
function_code,
val_to_str_const(function_code, function_code_vals, "Unknown Function"),
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 {
/* Follow different dissection path depending on whether packet is query or response */
if (*packet_type == QUERY_PACKET) {
dissect_modbus_request(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len);
}
else if (*packet_type == RESPONSE_PACKET) {
dissect_modbus_response(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len);
}
}
return tvb_captured_length(tvb);
}
/* Register the protocol with Wireshark */
void
proto_register_modbus(void)
{
/* Modbus/TCP header fields */
static hf_register_info mbtcp_hf[] = {
{ &hf_mbtcp_transid,
{ "Transaction Identifier", "mbtcp.trans_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_mbtcp_protid,
{ "Protocol Identifier", "mbtcp.prot_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_mbtcp_len,
{ "Length", "mbtcp.len",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_mbtcp_unitid,
{ "Unit Identifier", "mbtcp.unit_id",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
};
static ei_register_info mbtcp_ei[] = {
{ &ei_mbtcp_cannot_classify,
{ "mbtcp.cannot_classify", PI_PROTOCOL, PI_WARN,
"Cannot classify packet type. Try setting Modbus/TCP Port preference to this destination or source port", EXPFILL }
},
};
/* Modbus RTU header fields */
static hf_register_info mbrtu_hf[] = {
{ &hf_mbrtu_unitid,
{ "Unit ID", "mbrtu.unit_id",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_mbrtu_crc16,
{ "CRC-16", "mbrtu.crc16",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
};
static ei_register_info mbrtu_ei[] = {
{ &ei_mbrtu_crc16_incorrect,
{ "mbrtu.crc16.incorrect", PI_CHECKSUM, PI_WARN,
"Incorrect CRC", EXPFILL }
},
};
/* Modbus header fields */
static hf_register_info hf[] = {
{ &hf_modbus_request_frame,
{ "Request Frame", "modbus.request_frame",
FT_FRAMENUM, BASE_NONE,
NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_functioncode,
{ "Function Code", "modbus.func_code",
FT_UINT8, BASE_DEC, VALS(function_code_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_reference,
{ "Reference Number", "modbus.reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_padding,
{ "Padding", "modbus.padding",
FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_lreference,
{ "Reference Number (32 bit)", "modbus.reference_num_32",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_reftype,
{ "Reference Type", "modbus.reference_type",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_readref,
{ "Read Reference Number", "modbus.read_reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_writeref,
{ "Write Reference Number", "modbus.write_reference_num",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_wordcnt,
{ "Word Count", "modbus.word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_readwordcnt,
{ "Read Word Count", "modbus.read_word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_writewordcnt,
{ "Write Word Count", "modbus.write_word_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_bitcnt,
{ "Bit Count", "modbus.bit_cnt",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_bytecnt,
{ "Byte Count", "modbus.byte_cnt",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_lbytecnt,
{ "Byte Count (16-bit)", "modbus.byte_cnt_16",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_exceptioncode,
{ "Exception Code", "modbus.exception_code",
FT_UINT8, BASE_DEC, VALS(exception_code_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_sf,
{ "Diagnostic Code", "modbus.diagnostic_code",
FT_UINT16, BASE_DEC, VALS(diagnostic_code_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_query_data_request,
{ "Request Data", "modbus.diagnostic.return_query_data.request",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_query_data_echo,
{ "Echo Data", "modbus.diagnostic.return_query_data.echo",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_restart_communication_option,
{ "Restart Communication Option", "modbus.diagnostic.restart_communication_option",
FT_UINT16, BASE_HEX, VALS(diagnostic_restart_communication_option_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_diag_register,
{ "Diagnostic Register Contents", "modbus.diagnostic.return_diag_register",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_ascii_input_delimiter,
{ "CHAR", "modbus.diagnostic.ascii_input_delimiter",
FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_clear_ctr_diag_reg,
{ "Clear Counters & Diag Register Echo", "modbus.diagnostic.clear_ctr_diag_reg",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_bus_message_count,
{ "Total Message Count", "modbus.diagnostic.bus_message_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_bus_comm_error_count,
{ "CRC Error Count", "modbus.diagnostic.bus_comm_error_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_bus_exception_error_count,
{ "Exception Error Count", "modbus.diagnostic.bus_exception_error_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_slave_message_count,
{ "Slave Message Count", "modbus.diagnostic.slave_message_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_no_slave_response_count,
{ "Slave No Response Count", "modbus.diagnostic.no_slave_response_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_slave_nak_count,
{ "Slave NAK Count", "modbus.diagnostic.slave_nak_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_slave_busy_count,
{ "Slave Device Busy Count", "modbus.diagnostic.slave_busy_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_diag_return_bus_char_overrun_count,
{ "Slave Character Overrun Count", "modbus.diagnostic.bus_char_overrun_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_status,
{ "Status", "modbus.ev_status",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_event,
{ "Event", "modbus.event",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_event_count,
{ "Event Count", "modbus.ev_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_message_count,
{ "Message Count", "modbus.ev_msg_count",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_event_recv_comm_err,
{ "Communication Error", "modbus.ev_recv_comm_err",
FT_UINT8, BASE_DEC, NULL, 0x02,
NULL, HFILL }
},
{ &hf_modbus_event_recv_char_over,
{ "Character Overrun", "modbus.ev_recv_char_over",
FT_UINT8, BASE_DEC, NULL, 0x10,
NULL, HFILL }
},
{ &hf_modbus_event_recv_lo_mode,
{ "Currently in Listen Only Mode", "modbus.ev_recv_lo_mode",
FT_UINT8, BASE_DEC, NULL, 0x20,
NULL, HFILL }
},
{ &hf_modbus_event_recv_broadcast,
{ "Broadcast Received", "modbus.ev_recv_broadcast",
FT_UINT8, BASE_DEC, NULL, 0x40,
NULL, HFILL }
},
{ &hf_modbus_event_send_read_ex,
{ "Read Exception Sent", "modbus.ev_send_read_ex",
FT_UINT8, BASE_DEC, NULL, 0x01,
NULL, HFILL }
},
{ &hf_modbus_event_send_slave_abort_ex,
{ "Slave Abort Exception Sent", "modbus.ev_send_slave_abort_ex",
FT_UINT8, BASE_DEC, NULL, 0x02,
NULL, HFILL }
},
{ &hf_modbus_event_send_slave_busy_ex,
{ "Slave Busy Exception Sent", "modbus.ev_send_slave_busy_ex",
FT_UINT8, BASE_DEC, NULL, 0x04,
NULL, HFILL }
},
{ &hf_modbus_event_send_slave_nak_ex,
{ "Slave Program NAK Exception Sent", "modbus.ev_send_slave_nak_ex",
FT_UINT8, BASE_DEC, NULL, 0x08,
NULL, HFILL }
},
{ &hf_modbus_event_send_write_timeout,
{ "Write Timeout Error Occurred", "modbus.ev_send_write_timeout",
FT_UINT8, BASE_DEC, NULL, 0x10,
NULL, HFILL }
},
{ &hf_modbus_event_send_lo_mode,
{ "Currently in Listen Only Mode", "modbus.ev_send_lo_mode",
FT_UINT8, BASE_DEC, NULL, 0x20,
NULL, HFILL }
},
{ &hf_modbus_andmask,
{ "AND mask", "modbus.and_mask",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_ormask,
{ "OR mask", "modbus.or_mask",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_data,
{ "Data", "modbus.data",
FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }
},
{ &hf_modbus_mei,
{ "MEI type", "modbus.mei",
FT_UINT8, BASE_DEC, VALS(encap_interface_code_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_read_device_id,
{ "Read Device ID", "modbus.read_device_id",
FT_UINT8, BASE_DEC, VALS(read_device_id_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_object_id,
{ "Object ID", "modbus.object_id",
FT_UINT8, BASE_DEC, VALS(object_id_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_num_objects,
{ "Number of Objects", "modbus.num_objects",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_list_object_len,
{ "Object length", "modbus.objects_len",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_conformity_level,
{ "Conformity Level", "modbus.conformity_level",
FT_UINT8, BASE_HEX, VALS(conformity_level_vals), 0x0,
NULL, HFILL }
},
{ &hf_modbus_more_follows,
{ "More Follows", "modbus.more_follows",
FT_UINT8, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_next_object_id,
{ "Next Object ID", "modbus.next_object_id",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_object_str_value,
{ "Object String Value", "modbus.object_str_value",
FT_STRING, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_object_value,
{ "Object Value", "modbus.object_value",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_reg16,
{ "Register Value (16-bit)", "modbus.reg16",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_modbus_reg32,
{ "Register Value (32-bit)", "modbus.reg32",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_mbtcp,
&ett_mbrtu,
&ett_modbus_hdr,
&ett_group_hdr,
&ett_events,
&ett_events_recv,
&ett_events_send,
&ett_device_id_objects,
&ett_device_id_object_items
};
static ei_register_info ei[] = {
{ &ei_modbus_data_decode,
{ "modbus.data.decode", PI_PROTOCOL, PI_WARN,
"Invalid decoding options, register data not a multiple of 4!", EXPFILL }
},
};
module_t *mbtcp_module;
module_t *mbrtu_module;
module_t *modbus_module;
expert_module_t* expert_mbtcp;
expert_module_t* expert_mbrtu;
expert_module_t* expert_modbus;
/* Register the protocol name and description */
proto_mbtcp = proto_register_protocol("Modbus/TCP", "Modbus/TCP", "mbtcp");
proto_mbrtu = proto_register_protocol("Modbus RTU", "Modbus RTU", "mbrtu");
proto_modbus = proto_register_protocol("Modbus", "Modbus", "modbus");
/* Registering protocol to be called by another dissector */
modbus_handle = register_dissector("modbus", dissect_modbus, proto_modbus);
mbtcp_handle = register_dissector("mbtcp", dissect_mbtcp, proto_mbtcp);
mbrtu_handle = register_dissector("mbrtu", dissect_mbrtu, proto_mbrtu);
/* Registering subdissectors table */
modbus_data_dissector_table = register_dissector_table("modbus.data", "Modbus Data", proto_modbus, FT_STRING, BASE_NONE, DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE);
modbus_dissector_table = register_dissector_table("mbtcp.prot_id", "Modbus/TCP protocol identifier", proto_mbtcp, FT_UINT16, BASE_DEC, DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE);
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_mbtcp, mbtcp_hf, array_length(mbtcp_hf));
proto_register_field_array(proto_mbrtu, mbrtu_hf, array_length(mbrtu_hf));
proto_register_field_array(proto_modbus, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_mbtcp = expert_register_protocol(proto_mbtcp);
expert_register_field_array(expert_mbtcp, mbtcp_ei, array_length(mbtcp_ei));
expert_mbrtu = expert_register_protocol(proto_mbrtu);
expert_register_field_array(expert_mbrtu, mbrtu_ei, array_length(mbrtu_ei));
expert_modbus = expert_register_protocol(proto_modbus);
expert_register_field_array(expert_modbus, ei, array_length(ei));
/* Register required preferences for Modbus Protocol variants */
mbtcp_module = prefs_register_protocol(proto_mbtcp, proto_reg_handoff_mbtcp);
mbrtu_module = prefs_register_protocol(proto_mbrtu, proto_reg_handoff_mbrtu);
modbus_module = prefs_register_protocol(proto_modbus, NULL);
/* Modbus RTU Preference - Desegment, defaults to TRUE for TCP desegmentation */
prefs_register_bool_preference(mbtcp_module, "desegment",
"Desegment all Modbus RTU packets spanning multiple TCP segments",
"Whether the Modbus RTU dissector should desegment all messages spanning multiple TCP segments",
&mbtcp_desegment);
/* Modbus/TCP Preference - Default TCP Port, allows for "user" port either than 502. */
prefs_register_uint_preference(mbtcp_module, "tcp.port", "Modbus/TCP Port",
"Set the TCP port for Modbus/TCP packets (if other"
" than the default of 502)",
10, &global_mbus_tcp_port);
/* Modbus RTU Preference - Desegment, defaults to TRUE for TCP desegmentation */
prefs_register_bool_preference(mbrtu_module, "desegment",
"Desegment all Modbus RTU packets spanning multiple TCP segments",
"Whether the Modbus RTU dissector should desegment all messages spanning multiple TCP segments",
&mbrtu_desegment);
/* Modbus RTU Preference - CRC verification, defaults to FALSE (no verification)*/
prefs_register_bool_preference(mbrtu_module, "crc_verification",
"Validate CRC",
"Whether to validate the CRC",
&mbrtu_crc);
/* Modbus RTU Preference - Default TCP Port, defaults to zero, allows custom user port. */
prefs_register_uint_preference(mbrtu_module, "tcp.port", "Modbus RTU Port",
"Set the TCP/UDP port for encapsulated Modbus RTU packets",
10, &global_mbus_rtu_port);
/* Modbus Preference - Holding/Input Register format, this allows for deeper dissection of response data */
prefs_register_enum_preference(modbus_module, "mbus_register_format",
"Holding/Input Register Format",
"Register Format",
&global_mbus_register_format,
mbus_register_format,
TRUE);
/* Obsolete Preferences */
prefs_register_obsolete_preference(mbtcp_module, "mbus_register_addr_type");
prefs_register_obsolete_preference(mbtcp_module, "mbus_register_format");
prefs_register_obsolete_preference(mbrtu_module, "mbus_register_addr_type");
prefs_register_obsolete_preference(mbrtu_module, "mbus_register_format");
}
/* 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)
{
static unsigned int mbtcp_port;
/* Make sure to use Modbus/TCP Preferences field to determine default TCP port */
if(mbtcp_port != 0 && mbtcp_port != global_mbus_tcp_port){
dissector_delete_uint("tcp.port", mbtcp_port, mbtcp_handle);
}
if(global_mbus_tcp_port != 0 && mbtcp_port != global_mbus_tcp_port) {
dissector_add_uint("tcp.port", global_mbus_tcp_port, mbtcp_handle);
}
mbtcp_port = global_mbus_tcp_port;
dissector_add_uint("mbtcp.prot_id", MODBUS_PROTOCOL_ID, modbus_handle);
}
void
proto_reg_handoff_mbrtu(void)
{
static unsigned int mbrtu_port = 0;
dissector_handle_t mbrtu_udp_handle = create_dissector_handle(dissect_mbrtu_udp, proto_mbrtu);
/* Make sure to use Modbus RTU Preferences field to determine default TCP port */
if(mbrtu_port != 0 && mbrtu_port != global_mbus_rtu_port){
dissector_delete_uint("tcp.port", mbrtu_port, mbrtu_handle);
dissector_delete_uint("udp.port", mbrtu_port, mbrtu_udp_handle);
}
if(global_mbus_rtu_port != 0 && mbrtu_port != global_mbus_rtu_port) {
dissector_add_uint("tcp.port", global_mbus_rtu_port, mbrtu_handle);
dissector_add_uint("udp.port", global_mbus_rtu_port, mbrtu_udp_handle);
}
mbrtu_port = global_mbus_rtu_port;
dissector_add_uint("mbtcp.prot_id", MODBUS_PROTOCOL_ID, modbus_handle);
dissector_add_for_decode_as("rtacser.data", mbrtu_handle);
}
/*
* Editor modelines
*
* Local Variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
View Git Blame Copy Permalink