/* packet-mbtcp.c * Routines for Modbus/TCP dissection * By Riaan Swart * Copyright 2001, Institute for Applied Computer Science * University of Stellenbosch * * See * * http://www.modicon.com/openmbus/ * * for information on Modbus/TCP. * * $Id$ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #include #include #include #include #define DEBUG #define TCP_PORT_MBTCP 502 /* Modbus/TCP located on TCP port 502 */ /* Modbus protocol function codes */ #define READ_COILS 1 #define READ_INPUT_DISCRETES 2 #define READ_MULT_REGS 3 #define READ_INPUT_REGS 4 #define WRITE_COIL 5 #define WRITE_SINGLE_REG 6 #define READ_EXCEPT_STAT 7 #define DIAGNOSTICS 8 #define PROGRAM_484 9 #define POLL_484 10 #define GET_COMM_EVENT_CTRS 11 #define GET_COMM_EVENT_LOG 12 #define PROGRAM_584_984 13 #define POLL_584_984 14 #define FORCE_MULT_COILS 15 #define WRITE_MULT_REGS 16 #define REPORT_SLAVE_ID 17 #define PROGRAM_884_U84 18 #define RESET_COMM_LINK 19 #define READ_GENL_REF 20 #define WRITE_GENL_REF 21 #define MASK_WRITE_REG 22 #define READ_WRITE_REG 23 #define READ_FIFO_QUEUE 24 #define PROGRAM_CONCEPT 40 #define FIRMWARE_REPLACE 125 #define PROGRAM_584_984_2 126 #define REPORT_LOCAL_ADDR_MB 127 /* Modbus protocol exception codes */ #define ILLEGAL_FUNCTION 0x01 #define ILLEGAL_ADDRESS 0x02 #define ILLEGAL_VALUE 0x03 #define ILLEGAL_RESPONSE 0x04 #define ACKNOWLEDGE 0x05 #define SLAVE_BUSY 0x06 #define NEGATIVE_ACK 0x07 #define MEMORY_ERR 0x08 #define GATEWAY_UNAVAILABLE 0x0a #define GATEWAY_TRGT_FAIL 0x0b /* return codes of function classifying packets as query/response */ #define QUERY_PACKET 0 #define RESPONSE_PACKET 1 #define CANNOT_CLASSIFY 2 /* Modbus header */ typedef struct _modbus_hdr { guint8 unit_id; /* unit identifier (previously slave addr) */ guint8 function_code; /* Modbus function code */ } modbus_hdr; /* Modbus/TCP header, containing the Modbus header */ typedef struct _mbtcp_hdr { guint16 transaction_id; /* copied by svr, usually 0 */ guint16 protocol_id; /* always 0 */ guint16 len; /* len of data that follows */ modbus_hdr mdbs_hdr; /* mdbus hdr directly after mdbs/tcp hdr * * in packet */ } mbtcp_hdr; /* Initialize the protocol and registered fields */ static int proto_mbtcp = -1; static int hf_mbtcp_transid = -1; static int hf_mbtcp_protid = -1; static int hf_mbtcp_len = -1; static int hf_mbtcp_unitid = -1; static int hf_mbtcp_functioncode = -1; static int hf_modbus_reference = -1; static int hf_modbus_lreference = -1; static int hf_modbus_reftype = -1; static int hf_modbus_readref = -1; static int hf_modbus_writeref = -1; static int hf_modbus_wordcnt = -1; static int hf_modbus_readwordcnt = -1; static int hf_modbus_writewordcnt = -1; static int hf_modbus_bytecnt = -1; static int hf_modbus_lbytecnt = -1; static int hf_modbus_bitcnt = -1; static int hf_modbus_exceptioncode = -1; static int hf_modbus_andmask = -1; static int hf_modbus_ormask = -1; /* Initialize the subtree pointers */ static gint ett_mbtcp = -1; static gint ett_modbus_hdr = -1; static gint ett_group_hdr = -1; static int classify_packet(packet_info *pinfo) { /* see if nature of packets can be derived from src/dst ports */ /* if so, return as found */ if ( ( 502 == pinfo->srcport && 502 != pinfo->destport ) || ( 502 != pinfo->srcport && 502 == pinfo->destport ) ) { /* the slave is receiving queries on port 502 */ if ( 502 == pinfo->srcport ) return RESPONSE_PACKET; else if ( 502 == pinfo->destport ) return QUERY_PACKET; } /* else, cannot classify */ return CANNOT_CLASSIFY; } /* Translate function to string, as given on p6 of * "Open Modbus/TCP Specification", release 1 by Andy Swales. */ static const value_string function_code_vals[] = { { READ_COILS, "Read coils" }, { READ_INPUT_DISCRETES, "Read input discretes" }, { READ_MULT_REGS, "Read multiple registers" }, { READ_INPUT_REGS, "Read input registers" }, { WRITE_COIL, "Write coil" }, { WRITE_SINGLE_REG, "Write single register" }, { READ_EXCEPT_STAT, "Read exception status" }, { DIAGNOSTICS, "Diagnostics" }, { PROGRAM_484, "Program (484)" }, { POLL_484, "Poll (484)" }, { GET_COMM_EVENT_CTRS, "Get Comm. Event Counters" }, { GET_COMM_EVENT_LOG, "Get Comm. Event Log" }, { PROGRAM_584_984, "Program (584/984)" }, { POLL_584_984, "Poll (584/984)" }, { FORCE_MULT_COILS, "Force Multiple Coils" }, { WRITE_MULT_REGS, "Write Multiple Registers" }, { REPORT_SLAVE_ID, "Report Slave ID" }, { PROGRAM_884_U84, "Program 884/u84" }, { RESET_COMM_LINK, "Reset Comm. Link (884/u84)" }, { READ_GENL_REF, "Read General Reference" }, { WRITE_GENL_REF, "Write General Reference" }, { MASK_WRITE_REG, "Mask Write Register" }, { READ_WRITE_REG, "Read Write Register" }, { READ_FIFO_QUEUE, "Read FIFO Queue" }, { PROGRAM_CONCEPT, "Program (ConCept)" }, { FIRMWARE_REPLACE, "Firmware replacement" }, { PROGRAM_584_984_2, "Program (584/984)" }, { REPORT_LOCAL_ADDR_MB, "Report local address (Modbus)" }, { 0, NULL } }; static const value_string exception_code_vals[] = { { ILLEGAL_FUNCTION, "Illegal function" }, { ILLEGAL_ADDRESS, "Illegal data address" }, { ILLEGAL_VALUE, "Illegal data value" }, { ILLEGAL_RESPONSE, "Illegal response length" }, { ACKNOWLEDGE, "Acknowledge" }, { SLAVE_BUSY, "Slave device busy" }, { NEGATIVE_ACK, "Negative acknowledge" }, { MEMORY_ERR, "Memory parity error" }, { GATEWAY_UNAVAILABLE, "Gateway path unavailable" }, { GATEWAY_TRGT_FAIL, "Gateway target device failed to respond" }, { 0, NULL } }; /* Code to actually dissect the packets */ static int dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { /* Set up structures needed to add the protocol subtree and manage it */ mbtcp_hdr mh; proto_item *mi, *mf; proto_tree *mbtcp_tree, *modbus_tree, *group_tree; int offset, group_offset, packet_type; guint i; gint packet_len, payload_start, payload_len; const char *func_string = ""; char *pkt_type_str = ""; char *err_str = ""; guint32 byte_cnt, group_byte_cnt, group_word_cnt; guint32 packet_num; /* num to uniquely identify different mbtcp * packets in one TCP packet */ guint8 exception_code; gboolean exception_returned; guint8 fc; mh.transaction_id = tvb_get_ntohs(tvb, 0); mh.protocol_id = tvb_get_ntohs(tvb, 2); mh.len = tvb_get_ntohs(tvb, 4); mh.mdbs_hdr.unit_id = tvb_get_guint8(tvb, 6); mh.mdbs_hdr.function_code = tvb_get_guint8(tvb, 7); /* check that it actually looks like Modbus/TCP */ /* protocol id == 0 */ if( mh.protocol_id != 0 ){ return 0; } /* length is at least 2 (unit_id + function_code) */ if( mh.len < 2 ){ return 0; } /* function code is in the set 1-24, 40, 125-127. * Note that function code is only 7 bits. */ fc=mh.mdbs_hdr.function_code&0x7f; if( (fc<1) ||(fc>127) ||((fc>24)&&(fc<40)) ||((fc>40)&&(fc<125)) ){ return 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 */ offset = 0; if ( mh.mdbs_hdr.function_code & 0x80 ) { exception_code = tvb_get_guint8(tvb, offset + sizeof(mbtcp_hdr)); mh.mdbs_hdr.function_code ^= 0x80; exception_returned = TRUE; } else { exception_code = 0; exception_returned = FALSE; } func_string = val_to_str(mh.mdbs_hdr.function_code, function_code_vals, "Unknown function (%u)"); if (check_col(pinfo->cinfo, COL_INFO)) { packet_type = classify_packet(pinfo); switch ( packet_type ) { case QUERY_PACKET : 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; } if ( exception_returned ) err_str="Exception returned "; col_add_fstr(pinfo->cinfo, COL_INFO, "%8s [%2u pkt(s)]: trans: %5u; unit: %3u, func: %3u: %s. %s", pkt_type_str, 1, mh.transaction_id, (unsigned char) mh.mdbs_hdr.unit_id, (unsigned char) mh.mdbs_hdr.function_code, func_string, err_str); } /* build up protocol tree and iterate over multiple packets */ packet_num = 0; while (1) { packet_type = classify_packet(pinfo); packet_len = sizeof(mbtcp_hdr) - sizeof(modbus_hdr) + mh.len; /* if a tree exists, perform operations to add fields to it */ if (tree) { mi = proto_tree_add_protocol_format(tree, proto_mbtcp, tvb, offset, packet_len, "Modbus/TCP"); mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp); /* Add items to protocol tree specific to Modbus/TCP Modbus/TCP */ proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2, mh.transaction_id); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2, mh.protocol_id); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2, mh.len); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_unitid, tvb, offset + 6, 1, mh.mdbs_hdr.unit_id); /* Add items to protocol tree specific to Modbus generic */ mf = proto_tree_add_text(mbtcp_tree, tvb, offset + 6, mh.len, "Modbus"); modbus_tree = proto_item_add_subtree(mf, ett_modbus_hdr); mi = proto_tree_add_uint(modbus_tree, hf_mbtcp_functioncode, tvb, offset + 7, 1, mh.mdbs_hdr.function_code); /** detail payload as a function of exception/function code */ func_string = val_to_str(mh.mdbs_hdr.function_code, function_code_vals, "Unknown function"); payload_start = offset + 8; payload_len = mh.len - sizeof(modbus_hdr); if (exception_returned) { proto_item_set_text(mi, "function %u: %s. Exception: %s", mh.mdbs_hdr.function_code, func_string, val_to_str(exception_code, exception_code_vals, "Unknown exception code (%u)")); proto_tree_add_uint(modbus_tree, hf_modbus_exceptioncode, tvb, payload_start, 1, exception_code); } else { proto_item_set_text(mi, "function %u: %s", mh.mdbs_hdr.function_code, func_string); switch (mh.mdbs_hdr.function_code) { case READ_COILS: case READ_INPUT_DISCRETES: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE); } else if (packet_type == RESPONSE_PACKET) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data"); } break; case READ_MULT_REGS: case READ_INPUT_REGS: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE); } else if (packet_type == RESPONSE_PACKET) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data"); } break; case WRITE_COIL: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 1, "Data"); proto_tree_add_text(modbus_tree, tvb, payload_start + 3, 1, "Padding"); } else if (packet_type == RESPONSE_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 1, "Data"); proto_tree_add_text(modbus_tree, tvb, payload_start + 3, 1, "Padding"); } break; case WRITE_SINGLE_REG: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 2, "Data"); } else if (packet_type == RESPONSE_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_text(modbus_tree, tvb, payload_start + 2, 2, "Data"); } break; case READ_EXCEPT_STAT: if (packet_type == RESPONSE_PACKET) proto_tree_add_text(modbus_tree, tvb, payload_start, 1, "Data"); break; case FORCE_MULT_COILS: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE); byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 4); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 5, byte_cnt, "Data"); } else if (packet_type == RESPONSE_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, FALSE); } break; case WRITE_MULT_REGS: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE); byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 4); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 5, byte_cnt, "Data"); } else if (packet_type == RESPONSE_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE); } break; case READ_GENL_REF: if (packet_type == QUERY_PACKET) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; for (i = 0; i < byte_cnt / 7; i++) { mi = proto_tree_add_text( modbus_tree, tvb, group_offset, 7, "Group %u", i); group_tree = proto_item_add_subtree(mi, ett_group_hdr); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, FALSE); proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, FALSE); proto_tree_add_item(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, FALSE); group_offset += 7; } } else if (packet_type == RESPONSE_PACKET) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; i = 0; while (byte_cnt > 0) { group_byte_cnt = (guint32)tvb_get_guint8(tvb, group_offset); mi = proto_tree_add_text( modbus_tree, tvb, group_offset, group_byte_cnt + 1, "Group %u", i); group_tree = proto_item_add_subtree(mi, ett_group_hdr); proto_tree_add_uint(group_tree, hf_modbus_bytecnt, tvb, group_offset, 1, group_byte_cnt); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset + 1, 1, FALSE); proto_tree_add_text(group_tree, tvb, group_offset + 2, group_byte_cnt - 1, "Data"); group_offset += (group_byte_cnt + 1); byte_cnt -= (group_byte_cnt + 1); i++; } } break; case WRITE_GENL_REF: if ((packet_type == QUERY_PACKET) || (packet_type == RESPONSE_PACKET)) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; i = 0; while (byte_cnt > 0) { group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5); group_byte_cnt = (2 * group_word_cnt) + 7; mi = proto_tree_add_text( modbus_tree, tvb, group_offset, group_byte_cnt, "Group %u", i); group_tree = proto_item_add_subtree(mi, ett_group_hdr); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, FALSE); proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, FALSE); proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, group_word_cnt); proto_tree_add_text(group_tree, tvb, group_offset + 7, group_byte_cnt - 7, "Data"); group_offset += group_byte_cnt; byte_cnt -= group_byte_cnt; i++; } } break; case MASK_WRITE_REG: if ((packet_type == QUERY_PACKET) || (packet_type == RESPONSE_PACKET)) { proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, FALSE); } break; case READ_WRITE_REG: if (packet_type == QUERY_PACKET) { proto_tree_add_item(modbus_tree, hf_modbus_readref, tvb, payload_start, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_readwordcnt, tvb, payload_start + 2, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_writeref, tvb, payload_start + 4, 2, FALSE); proto_tree_add_item(modbus_tree, hf_modbus_writewordcnt, tvb, payload_start + 6, 2, FALSE); byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start + 8); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 8, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 9, byte_cnt, "Data"); } else if (packet_type == RESPONSE_PACKET) { byte_cnt = (guint32)tvb_get_guint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); proto_tree_add_text(modbus_tree, tvb, payload_start + 1, byte_cnt, "Data"); } break; case READ_FIFO_QUEUE: if (packet_type == QUERY_PACKET) proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, FALSE); else if (packet_type == RESPONSE_PACKET) { byte_cnt = (guint32)tvb_get_ntohs(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_lbytecnt, tvb, payload_start, 2, byte_cnt); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, FALSE); proto_tree_add_text(modbus_tree, tvb, payload_start + 4, byte_cnt - 2, "Data"); } break; case DIAGNOSTICS: case PROGRAM_484: case POLL_484: case GET_COMM_EVENT_CTRS: case GET_COMM_EVENT_LOG: case PROGRAM_584_984: case POLL_584_984: case REPORT_SLAVE_ID: case PROGRAM_884_U84: case RESET_COMM_LINK: case PROGRAM_CONCEPT: case FIRMWARE_REPLACE: case PROGRAM_584_984_2: case REPORT_LOCAL_ADDR_MB: /* these function codes are not part of the Modbus/TCP specification */ default: if (payload_len > 0) proto_tree_add_text(modbus_tree, tvb, payload_start, payload_len, "Data"); break; } } } /* move onto next packet (if there) */ offset += packet_len; packet_num++; if (tvb_reported_length_remaining(tvb, offset) > 0) { /* load header structure for next packet */ mh.transaction_id = tvb_get_ntohs(tvb, offset+0); mh.protocol_id = tvb_get_ntohs(tvb, offset+2); mh.len = tvb_get_ntohs(tvb, offset+4); mh.mdbs_hdr.unit_id = tvb_get_guint8(tvb, offset+6); mh.mdbs_hdr.function_code = tvb_get_guint8(tvb, offset+7); if ( mh.mdbs_hdr.function_code & 0x80 ) { exception_code = tvb_get_guint8(tvb, offset + sizeof(mbtcp_hdr)); mh.mdbs_hdr.function_code ^= 0x80; exception_returned = TRUE; } else exception_returned = FALSE; } else break; } return tvb_length(tvb); } /* Register the protocol with Ethereal */ void proto_register_modbus(void) { /* Setup list of header fields See Section 1.6.1 for details*/ static hf_register_info hf[] = { /* Modbus/TCP header fields */ { &hf_mbtcp_transid, { "transaction identifier", "modbus_tcp.trans_id", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_mbtcp_protid, { "protocol identifier", "modbus_tcp.prot_id", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_mbtcp_len, { "length", "modbus_tcp.len", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, /* Modbus header fields */ { &hf_mbtcp_unitid, { "unit identifier", "modbus_tcp.unit_id", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_mbtcp_functioncode, { "function code", "modbus_tcp.func_code", FT_UINT8, BASE_DEC, VALS(function_code_vals), 0x0, "", HFILL } }, { &hf_modbus_reference, { "reference number", "modbus_tcp.reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_lreference, { "reference number (32 bit)", "modbus_tcp.reference_num_32", FT_UINT32, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_reftype, { "reference type", "modbus_tcp.reference_type", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_readref, { "read reference number", "modbus_tcp.read_reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_writeref, { "write reference number", "modbus_tcp.write_reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_wordcnt, { "word count", "modbus_tcp.word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_readwordcnt, { "read word count", "modbus_tcp.read_word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_writewordcnt, { "write word count", "modbus_tcp.write_word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_bitcnt, { "bit count", "modbus_tcp.bit_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_bytecnt, { "byte count", "modbus_tcp.byte_cnt", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_lbytecnt, { "byte count (16-bit)", "modbus_tcp.byte_cnt_16", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_modbus_exceptioncode, { "exception code", "modbus_tcp.exception_code", FT_UINT8, BASE_DEC, VALS(exception_code_vals), 0x0, "", HFILL } }, { &hf_modbus_andmask, { "AND mask", "modbus_tcp.and_mask", FT_UINT16, BASE_HEX, NULL, 0x0, "", HFILL } }, { &hf_modbus_ormask, { "OR mask", "modbus_tcp.or_mask", FT_UINT16, BASE_HEX, NULL, 0x0, "", HFILL } } }; /* Setup protocol subtree array */ static gint *ett[] = { &ett_mbtcp, &ett_modbus_hdr, &ett_group_hdr }; /* Register the protocol name and description */ proto_mbtcp = proto_register_protocol("Modbus/TCP", "Modbus/TCP", "mbtcp"); /* Required function calls to register the header fields and subtrees used */ proto_register_field_array(proto_mbtcp, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } /* If this dissector uses sub-dissector registration add a registration routine. This format is required because a script is used to find these routines and create the code that calls these routines. */ void proto_reg_handoff_mbtcp(void) { dissector_handle_t mbtcp_handle; mbtcp_handle = new_create_dissector_handle(dissect_mbtcp, proto_mbtcp); dissector_add("tcp.port", TCP_PORT_MBTCP, mbtcp_handle); }