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wireshark/packet-mbtcp.c
Guy Harris ee5ca25d31 Include files from the "epan" directory and subdirectories thereof with 
"epan/..." pathnames, so as to avoid collisions with header files in any
of the directories in which we look (e.g., "proto.h", as some other
package has its own "proto.h" file which it installs in the top-level
include directory).

Don't add "-I" flags to search "epan", as that's no longer necessary
(and we want includes of "epan" headers to fail if the "epan/" is left
out, so that we don't re-introduce includes lacking "epan/").

svn path=/trunk/; revision=4586
2002-01-21 07:37:49 +00:00

424 lines
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C
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/* packet-mbtcp.c
* Routines for Modbus/TCP dissection
* By Riaan Swart <rswart@cs.sun.ac.za>
* Copyright 2001, Institute for Applied Computer Science
* University of Stellenbosch
*
* See
*
* http://www.modicon.com/openmbus/
*
* for information on Modbus/TCP.
*
* $Id: packet-mbtcp.c,v 1.8 2002/01/21 07:36:37 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* TODO:
* Analysis of the payload of the Modbus packet.
* -- Based on the function code in the header, and the fact that the packet is
* either a query or a response, the different fields in the payload can be
* interpreted and displayed.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#include <glib.h>
#ifdef NEED_SNPRINTF_H
# include "snprintf.h"
#endif
#include <epan/packet.h>
#define DEBUG
#define TCP_PORT_MBTCP 502 /* Modbus/TCP located on TCP port 502 */
/* Modbus protocol function codes */
#define read_coils 1
#define read_input_discretes 2
#define read_mult_regs 3
#define read_input_regs 4
#define write_coil 5
#define write_single_reg 6
#define read_except_stat 7
#define diagnostics 8
#define program_484 9
#define poll_484 10
#define get_comm_event_ctrs 11
#define get_comm_event_log 12
#define program_584_984 13
#define poll_584_984 14
#define force_mult_coils 15
#define write_mult_regs 16
#define report_slave_id 17
#define program_884_u84 18
#define reset_comm_link 19
#define read_genl_ref 20
#define write_genl_ref 21
#define mask_write_reg 22
#define read_write_reg 23
#define read_fifo_queue 24
#define program_ConCept 40
#define firmware_replace 125
#define program_584_984_2 126
#define report_local_addr_mb 127
/* Modbus protocol exception codes */
#define illegal_function 0x01
#define illegal_address 0x02
#define illegal_value 0x03
#define illegal_response 0x04
#define acknowledge 0x05
#define slave_busy 0x06
#define negative_ack 0x07
#define memory_err 0x08
#define gateway_unavailable 0x0a
#define gateway_trgt_fail 0x0b
/* return codes of function classifying packets as query/response */
#define query_packet 0
#define response_packet 1
#define cannot_classify 2
/* Modbus header */
typedef struct _modbus_hdr {
gchar unit_id; /* unit identifier (previously slave addr) */
gchar function_code; /* Modbus function code */
} modbus_hdr;
/* Modbus/TCP header, containing the Modbus header */
typedef struct _mbtcp_hdr {
guint16 transaction_id; /* copied by svr, usually 0 */
guint16 protocol_id; /* always 0 */
guint16 len; /* len of data that follows */
modbus_hdr mdbs_hdr; /* mdbus hdr directly after mdbs/tcp hdr *
* in packet */
} mbtcp_hdr;
/* Initialize the protocol and registered fields */
static int proto_mbtcp = -1;
static int hf_mbtcp_transid = -1;
static int hf_mbtcp_protid = -1;
static int hf_mbtcp_len = -1;
static int hf_mbtcp_unitid = -1;
static int hf_mbtcp_functioncode = -1;
/* Initialize the subtree pointers */
static gint ett_mbtcp = -1;
static gint ett_modbus_hdr = -1;
static int
classify_packet(packet_info *pinfo)
{
/* see if nature of packets can be derived from src/dst ports */
/* if so, return as found */
if ( ( 502 == pinfo->srcport && 502 != pinfo->destport ) ||
( 502 != pinfo->srcport && 502 == pinfo->destport ) ) {
/* the slave is receiving queries on port 502 */
if ( 502 == pinfo->srcport )
return response_packet;
else if ( 502 == pinfo->destport )
return query_packet;
}
/* else, cannot classify */
return cannot_classify;
}
/* returns string describing function, as given on p6 of
* "Open Modbus/TCP Specification", release 1 by Andy Swales. */
static char *
function_string(guint16 func_code)
{
switch ( func_code ) {
case read_coils: return "Read coils"; break;
case read_input_discretes: return "Read input discretes"; break;
case read_mult_regs: return "Read multiple registers"; break;
case read_input_regs: return "Read input registers"; break;
case write_coil: return "Write coil"; break;
case write_single_reg: return "Write single register"; break;
case read_except_stat: return "Read exception status"; break;
case diagnostics: return "Diagnostics"; break;
case program_484: return "Program (484)"; break;
case poll_484: return "Poll (484)"; break;
case get_comm_event_ctrs: return "Get Comm. Event Counters"; break;
case get_comm_event_log: return "Get Comm. Event Log"; break;
case program_584_984: return "Program (584/984)"; break;
case poll_584_984: return "Poll (584/984)"; break;
case force_mult_coils: return "Force Multiple Coils"; break;
case write_mult_regs: return "Write Multiple Registers"; break;
case report_slave_id: return "Report Slave ID"; break;
case program_884_u84: return "Program 884/u84"; break;
case reset_comm_link: return "Reset Comm. Link (884/u84)"; break;
case read_genl_ref: return "Read General Reference"; break;
case write_genl_ref: return "Write General Reference"; break;
case mask_write_reg: return "Mask Write Register"; break;
case read_write_reg: return "Read Write Register"; break;
case read_fifo_queue: return "Read FIFO Queue"; break;
case program_ConCept: return "Program (ConCept)"; break;
case firmware_replace: return "Firmware replacement"; break;
case program_584_984_2: return "Program (584/984)"; break;
case report_local_addr_mb: return "Report local address (Modbus)"; break;
default: return "Unknown function"; break;
}
}
static char *
exception_string(guint8 exception_code)
{
switch( exception_code ) {
case illegal_function: return "Illegal function"; break;
case illegal_address: return "Illegal data address"; break;
case illegal_value: return "Illegal data value"; break;
case illegal_response: return "Illegal response length"; break;
case acknowledge: return "Acknowledge"; break;
case slave_busy: return "Slave device busy"; break;
case negative_ack: return "Negative acknowledge"; break;
case memory_err: return "Memory parity error"; break;
case gateway_unavailable: return "Gateway path unavailable"; break;
case gateway_trgt_fail: return "Gateway target device failed to respond"; break;
default: return "Unknown exception code"; break;
}
}
/* Code to actually dissect the packets */
static void
dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
/* Set up structures needed to add the protocol subtree and manage it */
mbtcp_hdr mh;
proto_item *mi, *mf;
proto_tree *mbtcp_tree, *modbus_tree;
int offset = 0;
gint packet_end, packet_len;
char *func_string = "", pkt_type_str[9] = "";
char err_str[100] = "";
int packet_type;
guint32 packet_num = 0; /* num to uniquely identify different mbtcp
* packets in one TCP packet */
guint8 exception_code = 0, exception_returned = 0;
/* Make entries in Protocol column on summary display */
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP");
if (check_col(pinfo->cinfo, COL_INFO))
col_clear(pinfo->cinfo, COL_INFO);
/* Make entries in Info column on summary display (updated after building proto tree) */
tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
mh.transaction_id = ntohs(mh.transaction_id);
mh.protocol_id = ntohs(mh.protocol_id);
mh.len = ntohs(mh.len);
if ( mh.mdbs_hdr.function_code & 0x80 ) {
mh.mdbs_hdr.function_code ^= 0x80;
exception_returned = 1;
}
func_string = function_string(mh.mdbs_hdr.function_code);
if (check_col(pinfo->cinfo, COL_INFO))
{
packet_type = classify_packet(pinfo);
switch ( packet_type ) {
case query_packet : strcpy(pkt_type_str, "query");
break;
case response_packet : strcpy(pkt_type_str, "response");
break;
case cannot_classify : strcpy(err_str, "Unable to classify as query or response.");
strcpy(pkt_type_str, "unknown");
break;
default :
break;
}
if ( exception_returned )
strcpy(err_str, "Exception returned ");
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s",
pkt_type_str, 1, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id,
(unsigned char) mh.mdbs_hdr.function_code, func_string, err_str);
}
/* build up protocol tree */
do {
/* Avoids alignment problems on many architectures. */
tvb_memcpy(tvb, (guint8 *)&mh, offset, sizeof(mbtcp_hdr));
mh.transaction_id = ntohs(mh.transaction_id);
mh.protocol_id = ntohs(mh.protocol_id);
mh.len = ntohs(mh.len);
if ( mh.mdbs_hdr.function_code & 0x80 ) {
tvb_memcpy(tvb, (guint8 *)&exception_code, offset + sizeof(mbtcp_hdr), 1);
mh.mdbs_hdr.function_code ^= 0x80;
exception_returned = 1;
} else
exception_code = 0;
packet_type = classify_packet(pinfo);
/* if a tree exists, perform operations to add fields to it */
if (tree) {
packet_len = sizeof(mbtcp_hdr) - sizeof(modbus_hdr) + mh.len;
mi = proto_tree_add_protocol_format(tree, proto_mbtcp, tvb, offset,
packet_len, "Modbus/TCP");
mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp);
/* Add items to protocol tree */
/* Modbus/TCP */
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2,
mh.transaction_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2,
mh.protocol_id);
proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2,
mh.len);
/* Modbus */
packet_end = mh.len;
mf = proto_tree_add_text(mbtcp_tree, tvb, offset + 6, packet_end,
"Modbus");
modbus_tree = proto_item_add_subtree(mf, ett_modbus_hdr);
proto_tree_add_item(modbus_tree, hf_mbtcp_unitid, tvb, offset + 6, 1,
mh.mdbs_hdr.unit_id);
mi = proto_tree_add_item(modbus_tree, hf_mbtcp_functioncode, tvb, offset + 7, 1,
mh.mdbs_hdr.function_code);
func_string = function_string(mh.mdbs_hdr.function_code);
if ( 0 == exception_code )
proto_item_set_text(mi, "function %u: %s", mh.mdbs_hdr.function_code,
func_string);
else
proto_item_set_text(mi, "function %u: %s. Exception: %s",
mh.mdbs_hdr.function_code, func_string, exception_string(exception_code));
packet_end = mh.len - 2;
proto_tree_add_text(modbus_tree, tvb, offset + 8, packet_end,
"Modbus data");
}
offset = offset + sizeof(mbtcp_hdr) + (mh.len - sizeof(modbus_hdr));
packet_num++;
} while ( tvb_reported_length_remaining(tvb, offset) > 0 );
/* Update entries in Info column on summary display */
if (check_col(pinfo->cinfo, COL_INFO))
{
switch ( packet_type ) {
case query_packet : strcpy(pkt_type_str, "query");
break;
case response_packet : strcpy(pkt_type_str, "response");
break;
case cannot_classify : strcpy(err_str, "Unable to classify as query or response.");
strcpy(pkt_type_str, "unknown");
break;
default :
break;
}
if ( exception_returned )
strcpy(err_str, "Exception returned ");
col_add_fstr(pinfo->cinfo, COL_INFO,
"%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s",
pkt_type_str, packet_num, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id,
(unsigned char) mh.mdbs_hdr.function_code, func_string, err_str);
}
/* If this protocol has a sub-dissector call it here, see section 1.8 */
}
/* Register the protocol with Ethereal */
/* this format is require because a script is used to build the C function
that calls all the protocol registration.
*/
void
proto_register_modbus(void)
{
/* Setup list of header fields See Section 1.6.1 for details*/
static hf_register_info hf[] = {
/* Modbus/TCP header fields */
{ &hf_mbtcp_transid,
{ "transaction identifier", "modbus_tcp.trans_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_protid,
{ "protocol identifier", "modbus_tcp.prot_id",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_len,
{ "length", "modbus_tcp.len",
FT_UINT16, BASE_DEC, NULL, 0x0,
"", HFILL }
},
/* Modbus header fields */
{ &hf_mbtcp_unitid,
{ "unit identifier", "modbus_tcp.unit_id",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
},
{ &hf_mbtcp_functioncode,
{ "function code ", "modbus_tcp.func_code",
FT_UINT8, BASE_DEC, NULL, 0x0,
"", HFILL }
}
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_mbtcp,
&ett_modbus_hdr
};
/* Register the protocol name and description */
proto_mbtcp = proto_register_protocol("Modbus/TCP",
"Modbus/TCP", "mbtcp");
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_mbtcp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
/* If this dissector uses sub-dissector registration add a registration routine.
This format is required because a script is used to find these routines and
create the code that calls these routines.
*/
void
proto_reg_handoff_mbtcp(void)
{
dissector_handle_t mbtcp_handle;
mbtcp_handle = create_dissector_handle(dissect_mbtcp, proto_mbtcp);
dissector_add("tcp.port", TCP_PORT_MBTCP, mbtcp_handle);
}
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