![Jörg Mayer](/assets/img/avatar_default.png)
winapi_cleanup tool written by Patrik Stridvall for the wine project. svn path=/trunk/; revision=6117
412 lines
14 KiB
C
412 lines
14 KiB
C
/* packet-mbtcp.c
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* Routines for Modbus/TCP dissection
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* By Riaan Swart <rswart@cs.sun.ac.za>
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* Copyright 2001, Institute for Applied Computer Science
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* University of Stellenbosch
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*
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* See
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*
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* http://www.modicon.com/openmbus/
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*
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* for information on Modbus/TCP.
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*
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* $Id: packet-mbtcp.c,v 1.11 2002/08/28 21:00:20 jmayer Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/* TODO:
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* Analysis of the payload of the Modbus packet.
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* -- Based on the function code in the header, and the fact that the packet is
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* either a query or a response, the different fields in the payload can be
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* interpreted and displayed.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <glib.h>
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#include <epan/packet.h>
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#define DEBUG
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#define TCP_PORT_MBTCP 502 /* Modbus/TCP located on TCP port 502 */
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/* Modbus protocol function codes */
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#define read_coils 1
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#define read_input_discretes 2
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#define read_mult_regs 3
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#define read_input_regs 4
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#define write_coil 5
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#define write_single_reg 6
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#define read_except_stat 7
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#define diagnostics 8
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#define program_484 9
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#define poll_484 10
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#define get_comm_event_ctrs 11
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#define get_comm_event_log 12
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#define program_584_984 13
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#define poll_584_984 14
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#define force_mult_coils 15
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#define write_mult_regs 16
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#define report_slave_id 17
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#define program_884_u84 18
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#define reset_comm_link 19
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#define read_genl_ref 20
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#define write_genl_ref 21
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#define mask_write_reg 22
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#define read_write_reg 23
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#define read_fifo_queue 24
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#define program_ConCept 40
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#define firmware_replace 125
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#define program_584_984_2 126
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#define report_local_addr_mb 127
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/* Modbus protocol exception codes */
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#define illegal_function 0x01
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#define illegal_address 0x02
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#define illegal_value 0x03
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#define illegal_response 0x04
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#define acknowledge 0x05
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#define slave_busy 0x06
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#define negative_ack 0x07
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#define memory_err 0x08
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#define gateway_unavailable 0x0a
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#define gateway_trgt_fail 0x0b
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/* return codes of function classifying packets as query/response */
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#define query_packet 0
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#define response_packet 1
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#define cannot_classify 2
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/* Modbus header */
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typedef struct _modbus_hdr {
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gchar unit_id; /* unit identifier (previously slave addr) */
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gchar function_code; /* Modbus function code */
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} modbus_hdr;
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/* Modbus/TCP header, containing the Modbus header */
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typedef struct _mbtcp_hdr {
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guint16 transaction_id; /* copied by svr, usually 0 */
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guint16 protocol_id; /* always 0 */
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guint16 len; /* len of data that follows */
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modbus_hdr mdbs_hdr; /* mdbus hdr directly after mdbs/tcp hdr *
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* in packet */
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} mbtcp_hdr;
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/* Initialize the protocol and registered fields */
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static int proto_mbtcp = -1;
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static int hf_mbtcp_transid = -1;
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static int hf_mbtcp_protid = -1;
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static int hf_mbtcp_len = -1;
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static int hf_mbtcp_unitid = -1;
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static int hf_mbtcp_functioncode = -1;
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/* Initialize the subtree pointers */
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static gint ett_mbtcp = -1;
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static gint ett_modbus_hdr = -1;
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static int
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classify_packet(packet_info *pinfo)
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{
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/* see if nature of packets can be derived from src/dst ports */
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/* if so, return as found */
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if ( ( 502 == pinfo->srcport && 502 != pinfo->destport ) ||
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( 502 != pinfo->srcport && 502 == pinfo->destport ) ) {
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/* the slave is receiving queries on port 502 */
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if ( 502 == pinfo->srcport )
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return response_packet;
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else if ( 502 == pinfo->destport )
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return query_packet;
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}
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/* else, cannot classify */
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return cannot_classify;
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}
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/* returns string describing function, as given on p6 of
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* "Open Modbus/TCP Specification", release 1 by Andy Swales. */
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static char *
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function_string(guint16 func_code)
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{
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switch ( func_code ) {
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case read_coils: return "Read coils"; break;
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case read_input_discretes: return "Read input discretes"; break;
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case read_mult_regs: return "Read multiple registers"; break;
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case read_input_regs: return "Read input registers"; break;
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case write_coil: return "Write coil"; break;
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case write_single_reg: return "Write single register"; break;
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case read_except_stat: return "Read exception status"; break;
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case diagnostics: return "Diagnostics"; break;
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case program_484: return "Program (484)"; break;
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case poll_484: return "Poll (484)"; break;
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case get_comm_event_ctrs: return "Get Comm. Event Counters"; break;
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case get_comm_event_log: return "Get Comm. Event Log"; break;
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case program_584_984: return "Program (584/984)"; break;
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case poll_584_984: return "Poll (584/984)"; break;
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case force_mult_coils: return "Force Multiple Coils"; break;
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case write_mult_regs: return "Write Multiple Registers"; break;
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case report_slave_id: return "Report Slave ID"; break;
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case program_884_u84: return "Program 884/u84"; break;
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case reset_comm_link: return "Reset Comm. Link (884/u84)"; break;
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case read_genl_ref: return "Read General Reference"; break;
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case write_genl_ref: return "Write General Reference"; break;
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case mask_write_reg: return "Mask Write Register"; break;
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case read_write_reg: return "Read Write Register"; break;
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case read_fifo_queue: return "Read FIFO Queue"; break;
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case program_ConCept: return "Program (ConCept)"; break;
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case firmware_replace: return "Firmware replacement"; break;
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case program_584_984_2: return "Program (584/984)"; break;
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case report_local_addr_mb: return "Report local address (Modbus)"; break;
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default: return "Unknown function"; break;
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}
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}
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static char *
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exception_string(guint8 exception_code)
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{
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switch( exception_code ) {
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case illegal_function: return "Illegal function"; break;
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case illegal_address: return "Illegal data address"; break;
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case illegal_value: return "Illegal data value"; break;
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case illegal_response: return "Illegal response length"; break;
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case acknowledge: return "Acknowledge"; break;
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case slave_busy: return "Slave device busy"; break;
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case negative_ack: return "Negative acknowledge"; break;
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case memory_err: return "Memory parity error"; break;
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case gateway_unavailable: return "Gateway path unavailable"; break;
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case gateway_trgt_fail: return "Gateway target device failed to respond"; break;
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default: return "Unknown exception code"; break;
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}
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}
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/* Code to actually dissect the packets */
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static void
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dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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/* Set up structures needed to add the protocol subtree and manage it */
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mbtcp_hdr mh;
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proto_item *mi, *mf;
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proto_tree *mbtcp_tree, *modbus_tree;
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int offset = 0;
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gint packet_end, packet_len;
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char *func_string = "", pkt_type_str[9] = "";
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char err_str[100] = "";
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int packet_type;
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guint32 packet_num = 0; /* num to uniquely identify different mbtcp
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* packets in one TCP packet */
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guint8 exception_code = 0, exception_returned = 0;
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/* Make entries in Protocol column on summary display */
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP");
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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/* Make entries in Info column on summary display (updated after building proto tree) */
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tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
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mh.transaction_id = g_ntohs(mh.transaction_id);
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mh.protocol_id = g_ntohs(mh.protocol_id);
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mh.len = g_ntohs(mh.len);
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if ( mh.mdbs_hdr.function_code & 0x80 ) {
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mh.mdbs_hdr.function_code ^= 0x80;
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exception_returned = 1;
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}
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func_string = function_string(mh.mdbs_hdr.function_code);
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if (check_col(pinfo->cinfo, COL_INFO))
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{
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packet_type = classify_packet(pinfo);
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switch ( packet_type ) {
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case query_packet : strcpy(pkt_type_str, "query");
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break;
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case response_packet : strcpy(pkt_type_str, "response");
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break;
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case cannot_classify : strcpy(err_str, "Unable to classify as query or response.");
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strcpy(pkt_type_str, "unknown");
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break;
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default :
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break;
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}
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if ( exception_returned )
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strcpy(err_str, "Exception returned ");
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col_add_fstr(pinfo->cinfo, COL_INFO,
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"%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s",
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pkt_type_str, 1, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id,
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(unsigned char) mh.mdbs_hdr.function_code, func_string, err_str);
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}
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/* build up protocol tree */
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do {
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/* Avoids alignment problems on many architectures. */
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tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
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mh.transaction_id = g_ntohs(mh.transaction_id);
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mh.protocol_id = g_ntohs(mh.protocol_id);
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mh.len = g_ntohs(mh.len);
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if ( mh.mdbs_hdr.function_code & 0x80 ) {
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tvb_memcpy(tvb, (guint8 *)&exception_code, offset + sizeof(mbtcp_hdr), 1);
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mh.mdbs_hdr.function_code ^= 0x80;
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exception_returned = 1;
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} else
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exception_code = 0;
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packet_type = classify_packet(pinfo);
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/* if a tree exists, perform operations to add fields to it */
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if (tree) {
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packet_len = sizeof(mbtcp_hdr) - sizeof(modbus_hdr) + mh.len;
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mi = proto_tree_add_protocol_format(tree, proto_mbtcp, tvb, offset,
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packet_len, "Modbus/TCP");
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mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp);
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/* Add items to protocol tree */
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/* Modbus/TCP */
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proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2,
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mh.transaction_id);
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proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2,
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mh.protocol_id);
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proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2,
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mh.len);
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/* Modbus */
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packet_end = mh.len;
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mf = proto_tree_add_text(mbtcp_tree, tvb, offset + 6, packet_end,
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"Modbus");
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modbus_tree = proto_item_add_subtree(mf, ett_modbus_hdr);
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proto_tree_add_item(modbus_tree, hf_mbtcp_unitid, tvb, offset + 6, 1,
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mh.mdbs_hdr.unit_id);
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mi = proto_tree_add_item(modbus_tree, hf_mbtcp_functioncode, tvb, offset + 7, 1,
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mh.mdbs_hdr.function_code);
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func_string = function_string(mh.mdbs_hdr.function_code);
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if ( 0 == exception_code )
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proto_item_set_text(mi, "function %u: %s", mh.mdbs_hdr.function_code,
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func_string);
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else
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proto_item_set_text(mi, "function %u: %s. Exception: %s",
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mh.mdbs_hdr.function_code, func_string, exception_string(exception_code));
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packet_end = mh.len - 2;
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proto_tree_add_text(modbus_tree, tvb, offset + 8, packet_end,
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"Modbus data");
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}
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offset = offset + sizeof(mbtcp_hdr) + (mh.len - sizeof(modbus_hdr));
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packet_num++;
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} while ( tvb_reported_length_remaining(tvb, offset) > 0 );
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/* Update entries in Info column on summary display */
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if (check_col(pinfo->cinfo, COL_INFO))
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{
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switch ( packet_type ) {
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case query_packet : strcpy(pkt_type_str, "query");
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break;
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case response_packet : strcpy(pkt_type_str, "response");
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break;
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case cannot_classify : strcpy(err_str, "Unable to classify as query or response.");
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strcpy(pkt_type_str, "unknown");
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break;
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default :
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break;
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}
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if ( exception_returned )
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strcpy(err_str, "Exception returned ");
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col_add_fstr(pinfo->cinfo, COL_INFO,
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"%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s",
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pkt_type_str, packet_num, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id,
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(unsigned char) mh.mdbs_hdr.function_code, func_string, err_str);
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}
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/* If this protocol has a sub-dissector call it here, see section 1.8 */
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}
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/* Register the protocol with Ethereal */
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/* this format is require because a script is used to build the C function
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that calls all the protocol registration.
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*/
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void
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proto_register_modbus(void)
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{
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/* Setup list of header fields See Section 1.6.1 for details*/
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static hf_register_info hf[] = {
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/* Modbus/TCP header fields */
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{ &hf_mbtcp_transid,
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{ "transaction identifier", "modbus_tcp.trans_id",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }
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},
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{ &hf_mbtcp_protid,
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{ "protocol identifier", "modbus_tcp.prot_id",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }
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},
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{ &hf_mbtcp_len,
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{ "length", "modbus_tcp.len",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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"", HFILL }
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},
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/* Modbus header fields */
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{ &hf_mbtcp_unitid,
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{ "unit identifier", "modbus_tcp.unit_id",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }
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},
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{ &hf_mbtcp_functioncode,
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{ "function code ", "modbus_tcp.func_code",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }
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}
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};
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/* Setup protocol subtree array */
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static gint *ett[] = {
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&ett_mbtcp,
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&ett_modbus_hdr
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};
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/* Register the protocol name and description */
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proto_mbtcp = proto_register_protocol("Modbus/TCP",
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"Modbus/TCP", "mbtcp");
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/* Required function calls to register the header fields and subtrees used */
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proto_register_field_array(proto_mbtcp, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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/* If this dissector uses sub-dissector registration add a registration routine.
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This format is required because a script is used to find these routines and
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create the code that calls these routines.
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*/
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void
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proto_reg_handoff_mbtcp(void)
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{
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dissector_handle_t mbtcp_handle;
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mbtcp_handle = create_dissector_handle(dissect_mbtcp, proto_mbtcp);
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dissector_add("tcp.port", TCP_PORT_MBTCP, mbtcp_handle);
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}
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