ad6fc87d64
This is an attempt to standardize display/handling of checksum fields for all dissectors. The main target is for dissectors that do validation, but dissectors that just report the checksum were also included just to make them easier to find in the future. Bug: 10620 Bug: 12058 Ping-Bug: 8859 Change-Id: Ia8abd86e42eaf8ed50de6b173409e914b17993bf Reviewed-on: https://code.wireshark.org/review/16380 Petri-Dish: Michael Mann <mmann78@netscape.net> Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org> Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com> Reviewed-by: Michael Mann <mmann78@netscape.net>
434 lines
14 KiB
C
434 lines
14 KiB
C
/* packet-mstp.c
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* Routines for BACnet MS/TP datalink dissection
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* Copyright 2008 Steve Karg <skarg@users.sourceforge.net> Alabama
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*
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* This is described in Clause 9 of ANSI/ASHRAE Standard 135-2004,
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* BACnet - A Data Communication Protocol for Building Automation
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* and Contrl Networks; clause 9 "describes a Master-Slave/Token-Passing
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* (MS/TP) data link protocol, which provides the same services to the
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* network layer as ISO 8802-2 Logical Link Control. It uses services
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* provided by the EIA-485 physical layer." See section 9.3 for the
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* frame format.
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <wiretap/wtap.h>
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#include <epan/expert.h>
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#include <epan/address_types.h>
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#include <epan/to_str.h>
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#include "packet-mstp.h"
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void proto_register_mstp(void);
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void proto_reg_handoff_mstp(void);
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/* Probably should be a preference, but here for now */
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#define BACNET_MSTP_SUMMARY_IN_TREE
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#define BACNET_MSTP_CHECKSUM_VALIDATE
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/* MS/TP Frame Type */
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/* Frame Types 8 through 127 are reserved by ASHRAE. */
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#define MSTP_TOKEN 0
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#define MSTP_POLL_FOR_MASTER 1
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#define MSTP_REPLY_TO_POLL_FOR_MASTER 2
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#define MSTP_TEST_REQUEST 3
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#define MSTP_TEST_RESPONSE 4
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#define MSTP_BACNET_DATA_EXPECTING_REPLY 5
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#define MSTP_BACNET_DATA_NOT_EXPECTING_REPLY 6
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#define MSTP_REPLY_POSTPONED 7
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static const value_string
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bacnet_mstp_frame_type_name[] = {
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{MSTP_TOKEN, "Token"},
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{MSTP_POLL_FOR_MASTER, "Poll For Master"},
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{MSTP_REPLY_TO_POLL_FOR_MASTER, "Reply To Poll For Master"},
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{MSTP_TEST_REQUEST, "Test_Request"},
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{MSTP_TEST_RESPONSE, "Test_Response"},
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{MSTP_BACNET_DATA_EXPECTING_REPLY, "BACnet Data Expecting Reply"},
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{MSTP_BACNET_DATA_NOT_EXPECTING_REPLY, "BACnet Data Not Expecting Reply"},
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{MSTP_REPLY_POSTPONED, "Reply Postponed"},
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/* Frame Types 128 through 255: Proprietary Frames */
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{0, NULL }
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};
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static dissector_table_t subdissector_table;
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static int proto_mstp = -1;
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static gint ett_bacnet_mstp = -1;
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static gint ett_bacnet_mstp_checksum = -1;
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static int hf_mstp_preamble_55 = -1;
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static int hf_mstp_preamble_FF = -1;
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static int hf_mstp_frame_type = -1;
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static int hf_mstp_frame_destination = -1;
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static int hf_mstp_frame_source = -1;
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static int hf_mstp_frame_vendor_id = -1;
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static int hf_mstp_frame_pdu_len = -1;
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static int hf_mstp_frame_crc8 = -1;
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static int hf_mstp_frame_crc16 = -1;
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static int hf_mstp_frame_checksum_status = -1;
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static expert_field ei_mstp_frame_pdu_len = EI_INIT;
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static expert_field ei_mstp_frame_checksum_bad = EI_INIT;
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static int mstp_address_type = -1;
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#if defined(BACNET_MSTP_CHECKSUM_VALIDATE)
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/* Accumulate "dataValue" into the CRC in crcValue. */
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/* Return value is updated CRC */
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/* The ^ operator means exclusive OR. */
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/* Note: This function is copied directly from the BACnet standard. */
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static guint8
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CRC_Calc_Header(
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guint8 dataValue,
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guint8 crcValue)
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{
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guint16 crc;
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crc = crcValue ^ dataValue; /* XOR C7..C0 with D7..D0 */
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/* Exclusive OR the terms in the table (top down) */
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crc = crc ^ (crc << 1) ^ (crc << 2) ^ (crc << 3)
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^ (crc << 4) ^ (crc << 5) ^ (crc << 6)
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^ (crc << 7);
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/* Combine bits shifted out left hand end */
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return (crc & 0xfe) ^ ((crc >> 8) & 1);
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}
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#endif
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#if defined(BACNET_MSTP_CHECKSUM_VALIDATE)
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/* Accumulate "dataValue" into the CRC in crcValue. */
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/* Return value is updated CRC */
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/* The ^ operator means exclusive OR. */
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/* Note: This function is copied directly from the BACnet standard. */
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static guint16
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CRC_Calc_Data(
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guint8 dataValue,
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guint16 crcValue)
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{
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guint16 crcLow;
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crcLow = (crcValue & 0xff) ^ dataValue; /* XOR C7..C0 with D7..D0 */
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/* Exclusive OR the terms in the table (top down) */
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return (crcValue >> 8) ^ (crcLow << 8) ^ (crcLow << 3)
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^ (crcLow << 12) ^ (crcLow >> 4)
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^ (crcLow & 0x0f) ^ ((crcLow & 0x0f) << 7);
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}
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#endif
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/* Common frame type text */
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const gchar *
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mstp_frame_type_text(guint32 val)
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{
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return val_to_str(val,
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bacnet_mstp_frame_type_name,
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"Unknown Frame Type (%u)");
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}
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static int mstp_str_len(const address* addr _U_)
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{
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return 5;
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}
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static int mstp_to_str(const address* addr, gchar *buf, int buf_len _U_)
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{
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*buf++ = '0';
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*buf++ = 'x';
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buf = bytes_to_hexstr(buf, (const guint8 *)addr->data, 1);
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*buf = '\0'; /* NULL terminate */
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return mstp_str_len(addr);
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}
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static const char* mstp_col_filter_str(const address* addr _U_, gboolean is_src)
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{
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if (is_src)
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return "mstp.src";
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return "mstp.dst";
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}
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static int mstp_len(void)
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{
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return 1;
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}
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/* dissects a BACnet MS/TP frame */
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/* preamble 0x55 0xFF is not included in Cimetrics U+4 output */
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void
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dissect_mstp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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proto_tree *subtree, gint offset)
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{
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guint8 mstp_frame_type = 0;
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guint16 mstp_frame_pdu_len = 0;
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guint16 mstp_tvb_pdu_len = 0;
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guint16 vendorid = 0;
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tvbuff_t *next_tvb = NULL;
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proto_item *item;
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#if defined(BACNET_MSTP_CHECKSUM_VALIDATE)
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/* used to calculate the crc value */
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guint8 crc8 = 0xFF;
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guint16 crc16 = 0xFFFF;
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guint8 crcdata;
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guint16 i; /* loop counter */
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guint16 max_len = 0;
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#endif
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "BACnet");
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col_set_str(pinfo->cinfo, COL_INFO, "BACnet MS/TP");
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mstp_frame_type = tvb_get_guint8(tvb, offset);
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mstp_frame_pdu_len = tvb_get_ntohs(tvb, offset+3);
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col_append_fstr(pinfo->cinfo, COL_INFO, " %s",
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mstp_frame_type_text(mstp_frame_type));
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/* Add the items to the tree */
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proto_tree_add_item(subtree, hf_mstp_frame_type, tvb,
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offset, 1, ENC_LITTLE_ENDIAN);
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proto_tree_add_item(subtree, hf_mstp_frame_destination, tvb,
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offset+1, 1, ENC_LITTLE_ENDIAN);
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proto_tree_add_item(subtree, hf_mstp_frame_source, tvb,
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offset+2, 1, ENC_LITTLE_ENDIAN);
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item = proto_tree_add_item(subtree, hf_mstp_frame_pdu_len, tvb,
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offset+3, 2, ENC_BIG_ENDIAN);
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mstp_tvb_pdu_len = tvb_reported_length_remaining(tvb, offset+6);
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/* check the length - which does not include the crc16 checksum */
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if (mstp_tvb_pdu_len > 2) {
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if (mstp_frame_pdu_len > (mstp_tvb_pdu_len-2)) {
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expert_add_info(pinfo, item, &ei_mstp_frame_pdu_len);
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}
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}
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#if defined(BACNET_MSTP_CHECKSUM_VALIDATE)
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/* calculate checksum to validate */
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for (i = 0; i < 5; i++) {
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crcdata = tvb_get_guint8(tvb, offset+i);
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crc8 = CRC_Calc_Header(crcdata, crc8);
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}
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crc8 = ~crc8;
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proto_tree_add_checksum(subtree, tvb, offset+5, hf_mstp_frame_crc8, hf_mstp_frame_checksum_status, &ei_mstp_frame_checksum_bad, pinfo, crc8,
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ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
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#else
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proto_tree_add_checksum(subtree, tvb, offset+5, hf_mstp_frame_crc8, hf_mstp_frame_checksum_status, &ei_mstp_frame_checksum_bad, pinfo, 0,
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PROTO_CHECKSUM_NO_FLAGS);
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#endif
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/* dissect BACnet PDU if there is one */
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offset += 6;
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if (mstp_tvb_pdu_len > 2) {
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/* remove the 16-bit crc checksum bytes */
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mstp_tvb_pdu_len -= 2;
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if (mstp_frame_type < 128) {
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vendorid = 0;
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next_tvb = tvb_new_subset_length(tvb, offset,
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mstp_tvb_pdu_len);
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} else {
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/* With Vendor ID */
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vendorid = tvb_get_ntohs(tvb, offset);
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/* Write Vendor ID as tree */
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proto_tree_add_item(subtree, hf_mstp_frame_vendor_id, tvb,
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offset, 2, ENC_BIG_ENDIAN);
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/* NPDU - call the Vendor specific dissector */
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next_tvb = tvb_new_subset(tvb, offset+2,
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mstp_tvb_pdu_len-2, mstp_frame_pdu_len);
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}
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if (!(dissector_try_uint(subdissector_table, (vendorid<<16) + mstp_frame_type,
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next_tvb, pinfo, tree))) {
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/* Unknown function - dissect the payload as data */
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call_data_dissector(next_tvb, pinfo, tree);
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}
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#if defined(BACNET_MSTP_CHECKSUM_VALIDATE)
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/* 16-bit checksum - calculate to validate */
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max_len = MIN(mstp_frame_pdu_len, mstp_tvb_pdu_len);
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for (i = 0; i < max_len; i++) {
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crcdata = tvb_get_guint8(tvb, offset+i);
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crc16 = CRC_Calc_Data(crcdata, crc16);
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}
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crc16 = ~crc16;
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/* convert it to on-the-wire format */
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crc16 = g_htons(crc16);
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proto_tree_add_checksum(subtree, tvb, offset+mstp_frame_pdu_len, hf_mstp_frame_crc16, hf_mstp_frame_checksum_status, &ei_mstp_frame_checksum_bad, pinfo, crc16,
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ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
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#else
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proto_tree_add_checksum(subtree, tvb, offset+mstp_frame_pdu_len, hf_mstp_frame_crc16, hf_mstp_frame_checksum_status, &ei_mstp_frame_checksum_bad, pinfo, 0,
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ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
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#endif
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}
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}
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static int
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dissect_mstp_wtap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
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{
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proto_item *ti;
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proto_tree *subtree;
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gint offset = 0;
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#ifdef BACNET_MSTP_SUMMARY_IN_TREE
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guint8 mstp_frame_type = 0;
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guint8 mstp_frame_source = 0;
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guint8 mstp_frame_destination = 0;
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#endif
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/* set the MS/TP MAC address in the source/destination */
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set_address_tvb(&pinfo->dl_dst, mstp_address_type, 1, tvb, offset+3);
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copy_address_shallow(&pinfo->dst, &pinfo->dl_dst);
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set_address_tvb(&pinfo->dl_src, mstp_address_type, 1, tvb, offset+4);
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copy_address_shallow(&pinfo->src, &pinfo->dl_src);
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#ifdef BACNET_MSTP_SUMMARY_IN_TREE
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mstp_frame_type = tvb_get_guint8(tvb, offset+2);
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mstp_frame_destination = tvb_get_guint8(tvb, offset+3);
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mstp_frame_source = tvb_get_guint8(tvb, offset+4);
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ti = proto_tree_add_protocol_format(tree, proto_mstp, tvb, offset, 8,
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"BACnet MS/TP, Src (%u), Dst (%u), %s",
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mstp_frame_source, mstp_frame_destination,
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mstp_frame_type_text(mstp_frame_type));
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#else
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ti = proto_tree_add_item(tree, proto_mstp, tvb, offset, 8, ENC_NA);
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#endif
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subtree = proto_item_add_subtree(ti, ett_bacnet_mstp);
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proto_tree_add_item(subtree, hf_mstp_preamble_55, tvb,
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offset, 1, ENC_LITTLE_ENDIAN);
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proto_tree_add_item(subtree, hf_mstp_preamble_FF, tvb,
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offset+1, 1, ENC_LITTLE_ENDIAN);
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dissect_mstp(tvb, pinfo, tree, subtree, offset+2);
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return tvb_captured_length(tvb);
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}
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void
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proto_register_mstp(void)
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{
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static hf_register_info hf[] = {
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{ &hf_mstp_preamble_55,
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{ "Preamble 55", "mstp.preamble_55",
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FT_UINT8, BASE_HEX, NULL, 0,
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"MS/TP Preamble 55", HFILL }
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},
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{ &hf_mstp_preamble_FF,
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{ "Preamble FF", "mstp.preamble_FF",
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FT_UINT8, BASE_HEX, NULL, 0,
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"MS/TP Preamble FF", HFILL }
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},
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{ &hf_mstp_frame_type,
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{ "Frame Type", "mstp.frame_type",
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FT_UINT8, BASE_DEC, VALS(bacnet_mstp_frame_type_name), 0,
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"MS/TP Frame Type", HFILL }
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},
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{ &hf_mstp_frame_destination,
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{ "Destination Address", "mstp.dst",
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FT_UINT8, BASE_DEC, NULL, 0,
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"Destination MS/TP MAC Address", HFILL }
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},
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{ &hf_mstp_frame_source,
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{ "Source Address", "mstp.src",
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FT_UINT8, BASE_DEC, NULL, 0,
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"Source MS/TP MAC Address", HFILL }
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},
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{ &hf_mstp_frame_vendor_id,
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{ "VendorID", "mstp.vendorid",
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FT_UINT16, BASE_DEC, NULL, 0,
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"MS/TP Vendor ID of proprietary frametypes", HFILL }
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},
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{ &hf_mstp_frame_pdu_len,
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{ "Length", "mstp.len",
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FT_UINT16, BASE_DEC, NULL, 0,
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"MS/TP Data Length", HFILL }
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},
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{ &hf_mstp_frame_crc8,
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{ "Header CRC", "mstp.hdr_crc",
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FT_UINT8, BASE_HEX, NULL, 0,
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"MS/TP Header CRC", HFILL }
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},
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{ &hf_mstp_frame_crc16,
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{ "Data CRC", "mstp.data_crc",
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FT_UINT16, BASE_HEX, NULL, 0,
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"MS/TP Data CRC", HFILL }
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},
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{ &hf_mstp_frame_checksum_status,
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{ "Checksum status", "mstp.checksum.status",
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FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
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NULL, HFILL }
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},
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};
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static gint *ett[] = {
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&ett_bacnet_mstp,
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&ett_bacnet_mstp_checksum
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};
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static ei_register_info ei[] = {
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{ &ei_mstp_frame_pdu_len, { "mstp.len.bad", PI_MALFORMED, PI_ERROR, "Length field value goes past the end of the payload", EXPFILL }},
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{ &ei_mstp_frame_checksum_bad, { "mstp.checksum_bad.expert", PI_CHECKSUM, PI_WARN, "Bad Checksum", EXPFILL }},
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};
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expert_module_t* expert_mstp;
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proto_mstp = proto_register_protocol("BACnet MS/TP",
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"BACnet MS/TP", "mstp");
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proto_register_field_array(proto_mstp, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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expert_mstp = expert_register_protocol(proto_mstp);
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expert_register_field_array(expert_mstp, ei, array_length(ei));
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register_dissector("mstp", dissect_mstp_wtap, proto_mstp);
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subdissector_table = register_dissector_table("mstp.vendor_frame_type",
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"MSTP Vendor specific Frametypes", proto_mstp, FT_UINT24, BASE_DEC, DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE);
|
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/* Table_type: (Vendor ID << 16) + Frametype */
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|
|
|
mstp_address_type = address_type_dissector_register("AT_MSTP", "BACnet MS/TP Address", mstp_to_str, mstp_str_len, NULL, mstp_col_filter_str, mstp_len, NULL, NULL);
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}
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|
|
|
void
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|
proto_reg_handoff_mstp(void)
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|
{
|
|
dissector_handle_t mstp_handle;
|
|
dissector_handle_t bacnet_handle;
|
|
|
|
mstp_handle = find_dissector("mstp");
|
|
dissector_add_uint("wtap_encap", WTAP_ENCAP_BACNET_MS_TP, mstp_handle);
|
|
dissector_add_uint("wtap_encap", WTAP_ENCAP_BACNET_MS_TP_WITH_PHDR, mstp_handle);
|
|
|
|
bacnet_handle = find_dissector("bacnet");
|
|
|
|
dissector_add_uint("mstp.vendor_frame_type", (0/*VendorID ASHRAE*/ << 16) + MSTP_BACNET_DATA_EXPECTING_REPLY, bacnet_handle);
|
|
dissector_add_uint("mstp.vendor_frame_type", (0/*VendorID ASHRAE*/ << 16) + MSTP_BACNET_DATA_NOT_EXPECTING_REPLY, bacnet_handle);
|
|
}
|
|
|
|
/*
|
|
* Editor modelines - http://www.wireshark.org/tools/modelines.html
|
|
*
|
|
* Local variables:
|
|
* c-basic-offset: 8
|
|
* tab-width: 8
|
|
* indent-tabs-mode: t
|
|
* End:
|
|
*
|
|
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
|
|
* :indentSize=8:tabSize=8:noTabs=false:
|
|
*/
|