/* packet-mbtcp.c * Routines for Modbus/TCP and Modbus/UDP dissection * By Riaan Swart * Copyright 2001, Institute for Applied Computer Science * University of Stellenbosch * * See http://www.modbus.org/ for information on Modbus/TCP. * * Updated to v1.1b of the Modbus Application Protocol specification * Michael Mann * Copyright 2011 * ***************************************************************************************************** * A brief explanation of the distinction between Modbus/TCP and Modbus RTU over TCP: * * Consider a Modbus poll message: Unit 01, Scan Holding Register Address 0 for 30 Registers * * The Modbus/TCP message structure will follow the pattern below: * 00 00 00 00 00 06 01 03 00 00 00 1E * AA AA BB BB CC CC DD EE FF FF GG GG * * A = 16-bit Transaction Identifier (typically increments, or is locked at zero) * B = 16-bit Protocol Identifier (typically zero) * C = 16-bit Length of data payload following (and inclusive of) the length byte * D = 8-bit Unit / Slave ID * E = 8-bit Modbus Function Code * F = 16-bit Reference Number / Register Base Address * G = 16-bit Word Count / Number of Registers to scan * * A identical Modbus RTU (or Modbus RTU over TCP) message will overlay partially with the msg above * and contain 16-bit CRC at the end: * 00 00 00 00 00 06 01 03 00 00 00 1E -- -- (Modbus/TCP message, repeated from above) * -- -- -- -- -- -- 01 03 00 00 00 1E C5 C2 (Modbus RTU over TCP message, includes 16-bit CRC footer) * AA AA BB BB CC CC DD EE FF FF GG GG HH HH * * A = Not present in Modbus RTU message * B = Not present in Modbus RTU message * C = Not present in Modbus RTU message * D = 8-bit Unit / Slave ID * E = 8-bit Modbus Function Code * F = 16-bit Reference Number / Register Base Address * G = 16-bit Word Count / Number of Registers to scan * H = 16-bit CRC * ***************************************************************************************************** * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include "packet-tcp.h" #include "packet-mbtcp.h" #include #include #include /* For CRC verification */ #include #include "packet-tls.h" void proto_register_modbus(void); void proto_reg_handoff_mbtcp(void); void proto_reg_handoff_mbrtu(void); /* Initialize the protocol and registered fields */ static int proto_mbtcp; static int proto_mbudp; static int proto_mbrtu; static int proto_modbus; static int hf_mbtcp_transid; static int hf_mbtcp_protid; static int hf_mbtcp_len; static int hf_mbtcp_unitid; static int hf_modbus_request_frame; static int hf_modbus_response_time; static int hf_modbus_functioncode; static int hf_modbus_reference; static int hf_modbus_padding; static int hf_modbus_lreference; static int hf_modbus_reftype; static int hf_modbus_readref; static int hf_modbus_writeref; static int hf_modbus_wordcnt; static int hf_modbus_readwordcnt; static int hf_modbus_writewordcnt; static int hf_modbus_bytecnt; static int hf_modbus_lbytecnt; static int hf_modbus_bitcnt; static int hf_modbus_exceptioncode; static int hf_modbus_diag_sf; static int hf_modbus_diag_return_query_data_request; static int hf_modbus_diag_return_query_data_echo; static int hf_modbus_diag_restart_communication_option; static int hf_modbus_diag_return_diag_register; static int hf_modbus_diag_ascii_input_delimiter; static int hf_modbus_diag_clear_ctr_diag_reg; static int hf_modbus_diag_return_bus_message_count; static int hf_modbus_diag_return_bus_comm_error_count; static int hf_modbus_diag_return_bus_exception_error_count; static int hf_modbus_diag_return_slave_message_count; static int hf_modbus_diag_return_no_slave_response_count; static int hf_modbus_diag_return_slave_nak_count; static int hf_modbus_diag_return_slave_busy_count; static int hf_modbus_diag_return_bus_char_overrun_count; static int hf_modbus_status; static int hf_modbus_event; static int hf_modbus_event_count; static int hf_modbus_message_count; static int hf_modbus_event_recv_comm_err; static int hf_modbus_event_recv_char_over; static int hf_modbus_event_recv_lo_mode; static int hf_modbus_event_recv_broadcast; static int hf_modbus_event_send_read_ex; static int hf_modbus_event_send_slave_abort_ex; static int hf_modbus_event_send_slave_busy_ex; static int hf_modbus_event_send_slave_nak_ex; static int hf_modbus_event_send_write_timeout; static int hf_modbus_event_send_lo_mode; static int hf_modbus_andmask; static int hf_modbus_ormask; static int hf_modbus_data; static int hf_modbus_mei; static int hf_modbus_read_device_id; static int hf_modbus_object_id; static int hf_modbus_num_objects; static int hf_modbus_list_object_len; static int hf_modbus_conformity_level; static int hf_modbus_more_follows; static int hf_modbus_next_object_id; static int hf_modbus_object_str_value; static int hf_modbus_object_value; static int hf_modbus_bitnum; static int hf_modbus_bitval; static int hf_modbus_regnum16; static int hf_modbus_regnum32; static int hf_modbus_regval_uint16; static int hf_modbus_regval_int16; static int hf_modbus_regval_uint32; static int hf_modbus_regval_int32; static int hf_modbus_regval_ieee_float; static int hf_modbus_regval_modicon_float; static int hf_mbrtu_unitid; static int hf_mbrtu_crc16; static int hf_mbrtu_crc16_status; /* Initialize the subtree pointers */ static int ett_mbtcp; static int ett_mbrtu; static int ett_modbus_hdr; static int ett_group_hdr; static int ett_events; static int ett_events_recv; static int ett_events_send; static int ett_device_id_objects; static int ett_device_id_object_items; static int ett_bit; static int ett_register; static expert_field ei_mbrtu_crc16_incorrect; static expert_field ei_modbus_data_decode; static expert_field ei_mbtcp_cannot_classify; static dissector_handle_t modbus_handle; static dissector_handle_t mbtcp_handle; static dissector_handle_t mbtls_handle; static dissector_handle_t mbudp_handle; static dissector_handle_t mbrtu_handle; static dissector_table_t modbus_data_dissector_table; static dissector_table_t modbus_dissector_table; /* Globals for Modbus/TCP Preferences */ static bool mbtcp_desegment = true; static range_t *global_mbus_tcp_ports; /* Port 502, by default */ static range_t *global_mbus_udp_ports; /* Port 502, by default */ static range_t *global_mbus_tls_ports; /* Port 802, by default */ /* Globals for Modbus RTU over TCP Preferences */ static bool mbrtu_desegment = true; static range_t *global_mbus_tcp_rtu_ports = PORT_MBRTU; /* 0, by default */ static range_t *global_mbus_udp_rtu_ports = PORT_MBRTU; /* 0, by default */ static bool mbrtu_crc; /* Globals for Modbus Preferences */ static int global_mbus_register_format = MODBUS_PREF_REGISTER_FORMAT_UINT16; typedef struct { uint8_t function_code; int register_format; uint16_t reg_base; uint16_t num_reg; uint32_t req_frame_num; nstime_t req_time; bool request_found; } modbus_pkt_info_t; static int classify_mbtcp_packet(packet_info *pinfo, range_t *ports) { /* see if nature of packets can be derived from src/dst ports */ /* if so, return as found */ /* */ /* XXX Update Oct 2012 - It can be difficult to determine if a packet is a query or response; some way to track */ /* the Modbus/TCP transaction ID for each pair of messages would allow for detection based on a new seq. number. */ /* Otherwise, we can stick with this method; a configurable port option has been added to allow for usage of */ /* user ports either than the default of 502. */ if ( (value_is_in_range(ports, pinfo->srcport)) && (!value_is_in_range(ports, pinfo->destport)) ) return RESPONSE_PACKET; if ( (!value_is_in_range(ports, pinfo->srcport)) && (value_is_in_range(ports, pinfo->destport)) ) return QUERY_PACKET; /* else, cannot classify */ return CANNOT_CLASSIFY; } static int classify_mbrtu_packet(packet_info *pinfo, tvbuff_t *tvb, range_t *ports) { uint8_t func, len; func = tvb_get_uint8(tvb, 1); len = tvb_reported_length(tvb); /* see if nature of packets can be derived from src/dst ports */ /* if so, return as found */ if ( (value_is_in_range(ports, pinfo->srcport)) && (!value_is_in_range(ports, pinfo->destport)) ) return RESPONSE_PACKET; if ( (!value_is_in_range(ports, pinfo->srcport)) && (value_is_in_range(ports, pinfo->destport)) ) return QUERY_PACKET; /* We may not have an Ethernet header or unique ports. */ /* Dig into these a little deeper to try to guess the message type */ /* The 'exception' bit is set, so this is a response */ if (func & 0x80) { return RESPONSE_PACKET; } switch (func) { case READ_COILS: case READ_DISCRETE_INPUTS: /* Only possible to get a response message of 8 bytes with Discrete or Coils */ if (len == 8) { /* If this is, in fact, a response then the data byte count will be 3 */ /* This will correctly identify all messages except for those that are discrete or coil polls */ /* where the base address range happens to have 0x03 in the upper 16-bit address register */ if (tvb_get_uint8(tvb, 2) == 3) { return RESPONSE_PACKET; } else { return QUERY_PACKET; } } else { return RESPONSE_PACKET; } break; case READ_HOLDING_REGS: case READ_INPUT_REGS: if (len == 8) { return QUERY_PACKET; } else { return RESPONSE_PACKET; } break; case WRITE_SINGLE_COIL: case WRITE_SINGLE_REG: /* Normal response is echo of the request */ return CANNOT_CLASSIFY; case WRITE_MULT_REGS: case WRITE_MULT_COILS: if (len == 8) { return RESPONSE_PACKET; } else { return QUERY_PACKET; } break; } /* else, cannot classify */ return CANNOT_CLASSIFY; } /* Translate function to string, as given on p6 of * "Open Modbus/TCP Specification", release 1 by Andy Swales. */ static const value_string function_code_vals[] = { { READ_COILS, "Read Coils" }, { READ_DISCRETE_INPUTS, "Read Discrete Inputs" }, { READ_HOLDING_REGS, "Read Holding Registers" }, { READ_INPUT_REGS, "Read Input Registers" }, { WRITE_SINGLE_COIL, "Write Single Coil" }, { WRITE_SINGLE_REG, "Write Single Register" }, { READ_EXCEPT_STAT, "Read Exception Status" }, { DIAGNOSTICS, "Diagnostics" }, { GET_COMM_EVENT_CTRS, "Get Comm. Event Counters" }, { GET_COMM_EVENT_LOG, "Get Comm. Event Log" }, { WRITE_MULT_COILS, "Write Multiple Coils" }, { WRITE_MULT_REGS, "Write Multiple Registers" }, { REPORT_SLAVE_ID, "Report Slave ID" }, { READ_FILE_RECORD, "Read File Record" }, { WRITE_FILE_RECORD, "Write File Record" }, { MASK_WRITE_REG, "Mask Write Register" }, { READ_WRITE_REG, "Read Write Register" }, { READ_FIFO_QUEUE, "Read FIFO Queue" }, { ENCAP_INTERFACE_TRANSP, "Encapsulated Interface Transport" }, { UNITY_SCHNEIDER, "Unity (Schneider)" }, { 0, NULL } }; /* Translate exception code to string */ static const value_string exception_code_vals[] = { { ILLEGAL_FUNCTION, "Illegal function" }, { ILLEGAL_ADDRESS, "Illegal data address" }, { ILLEGAL_VALUE, "Illegal data value" }, { SLAVE_FAILURE, "Slave device failure" }, { ACKNOWLEDGE, "Acknowledge" }, { SLAVE_BUSY, "Slave device busy" }, { MEMORY_ERR, "Memory parity error" }, { GATEWAY_UNAVAILABLE, "Gateway path unavailable" }, { GATEWAY_TRGT_FAIL, "Gateway target device failed to respond" }, { 0, NULL } }; /* Translate Modbus Encapsulation Interface (MEI) code to string */ static const value_string encap_interface_code_vals[] = { { CANOPEN_REQ_RESP, "CANopen Request/Response " }, { READ_DEVICE_ID, "Read Device Identification" }, { 0, NULL } }; /* Translate Modbus Diagnostic subfunction code to string */ static const value_string diagnostic_code_vals[] = { { RETURN_QUERY_DATA, "Return Query Data" }, { RESTART_COMMUNICATION_OPTION, "Restart Communications Option" }, { RETURN_DIAGNOSTIC_REGISTER, "Return Diagnostic Register" }, { CHANGE_ASCII_INPUT_DELIMITER, "Change ASCII Input Delimiter" }, { FORCE_LISTEN_ONLY_MODE, "Force Listen Only Mode" }, { CLEAR_COUNTERS_AND_DIAG_REG, "Clear Counters and Diagnostic Register" }, { RETURN_BUS_MESSAGE_COUNT, "Return Bus Message Count" }, { RETURN_BUS_COMM_ERROR_COUNT, "Return Bus Communication Error Count" }, { RETURN_BUS_EXCEPTION_ERROR_COUNT, "Return Bus Exception Error Count" }, { RETURN_SLAVE_MESSAGE_COUNT, "Return Slave Message Count" }, { RETURN_SLAVE_NO_RESPONSE_COUNT, "Return Slave No Response Count" }, { RETURN_SLAVE_NAK_COUNT, "Return Slave NAK Count" }, { RETURN_SLAVE_BUSY_COUNT, "Return Slave Busy Count" }, { RETURN_BUS_CHAR_OVERRUN_COUNT, "Return Bus Character Overrun Count" }, { CLEAR_OVERRUN_COUNTER_AND_FLAG, "Clear Overrun Counter and Flag" }, { 0, NULL } }; static const value_string diagnostic_restart_communication_option_vals[] = { { 0, "Leave Log" }, { 0xFF, "Clear Log" }, { 0, NULL } }; /* Translate read device code to string */ static const value_string read_device_id_vals[] = { { 1, "Basic Device Identification" }, { 2, "Regular Device Identification" }, { 3, "Extended Device Identification" }, { 4, "Specific Identification Object" }, { 0, NULL } }; /* Translate read device code to string */ static const value_string object_id_vals[] = { { 0, "VendorName" }, { 1, "ProductCode" }, { 2, "MajorMinorRevision" }, { 3, "VendorURL" }, { 4, "ProductName" }, { 5, "ModelName" }, { 6, "UserApplicationName" }, { 0, NULL } }; static const value_string conformity_level_vals[] = { { 0x01, "Basic Device Identification (stream)" }, { 0x02, "Regular Device Identification (stream)" }, { 0x03, "Extended Device Identification (stream)" }, { 0x81, "Basic Device Identification (stream and individual)" }, { 0x82, "Regular Device Identification (stream and individual)" }, { 0x83, "Extended Device Identification (stream and individual)" }, { 0, NULL } }; static const enum_val_t mbus_register_format[] = { { "UINT16 ", "UINT16 ", MODBUS_PREF_REGISTER_FORMAT_UINT16 }, { "INT16 ", "INT16 ", MODBUS_PREF_REGISTER_FORMAT_INT16 }, { "UINT32 ", "UINT32 ", MODBUS_PREF_REGISTER_FORMAT_UINT32 }, { "INT32 ", "INT32 ", MODBUS_PREF_REGISTER_FORMAT_INT32 }, { "IEEE FLT ", "IEEE FLT ", MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT }, { "MODICON FLT", "MODICON FLT", MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT }, { NULL, NULL, 0 } }; /* Code to dissect Modbus/TCP packets */ static int dissect_mbtcp_pdu_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int proto, range_t *ports) { /* Set up structures needed to add the protocol subtree and manage it */ proto_item *mi; proto_tree *mbtcp_tree; int offset; tvbuff_t *next_tvb; const char *func_string; const char *pkt_type_str = ""; const char *err_str = ""; uint16_t transaction_id, protocol_id, len; uint8_t unit_id, function_code, exception_code, subfunction_code; modbus_data_t modbus_data; transaction_id = tvb_get_ntohs(tvb, 0); protocol_id = tvb_get_ntohs(tvb, 2); len = tvb_get_ntohs(tvb, 4); unit_id = tvb_get_uint8(tvb, 6); function_code = tvb_get_uint8(tvb, 7) & 0x7F; offset = 0; /* "Request" or "Response" */ modbus_data.packet_type = classify_mbtcp_packet(pinfo, ports); /* Save the transaction and unit id to find the request to a response */ modbus_data.mbtcp_transid = transaction_id; modbus_data.unit_id = unit_id; switch ( modbus_data.packet_type ) { case QUERY_PACKET : pkt_type_str="Query"; break; case RESPONSE_PACKET : pkt_type_str="Response"; break; case CANNOT_CLASSIFY : err_str="Unable to classify as query or response."; pkt_type_str="unknown"; break; default : break; } /* Find exception - last bit set in function code */ if (tvb_get_uint8(tvb, 7) & 0x80) { exception_code = tvb_get_uint8(tvb, offset + 8); } else { exception_code = 0; } if ((function_code == ENCAP_INTERFACE_TRANSP) && (exception_code == 0)) { func_string = val_to_str_const(tvb_get_uint8(tvb, offset + 8), encap_interface_code_vals, "Encapsulated Interface Transport"); subfunction_code = 1; } else if ((function_code == DIAGNOSTICS) && (exception_code == 0)) { func_string = val_to_str_const(tvb_get_ntohs(tvb, offset + 8), diagnostic_code_vals, "Diagnostics"); subfunction_code = 1; } else { func_string = val_to_str(function_code, function_code_vals, "Unknown function (%d)"); subfunction_code = 0; } if ( exception_code != 0 ) err_str="Exception returned "; /* Make entries in Info column on summary display */ if (subfunction_code == 0) { if (strlen(err_str) > 0) { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Trans: %5u; Unit: %3u, Func: %3u: %s. %s", pkt_type_str, transaction_id, unit_id, function_code, func_string, err_str); } else { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Trans: %5u; Unit: %3u, Func: %3u: %s", pkt_type_str, transaction_id, unit_id, function_code, func_string); } } else { if (strlen(err_str) > 0) { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Trans: %5u; Unit: %3u, Func: %3u/%3u: %s. %s", pkt_type_str, transaction_id, unit_id, function_code, subfunction_code, func_string, err_str); } else { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Trans: %5u; Unit: %3u, Func: %3u/%3u: %s", pkt_type_str, transaction_id, unit_id, function_code, subfunction_code, func_string); } } /* Create protocol tree */ mi = proto_tree_add_item(tree, proto, tvb, offset, len+6, ENC_NA); mbtcp_tree = proto_item_add_subtree(mi, ett_mbtcp); if (modbus_data.packet_type == CANNOT_CLASSIFY) expert_add_info(pinfo, mi, &ei_mbtcp_cannot_classify); /* Add items to protocol tree specific to Modbus/TCP */ proto_tree_add_uint(mbtcp_tree, hf_mbtcp_transid, tvb, offset, 2, transaction_id); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_protid, tvb, offset + 2, 2, protocol_id); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_len, tvb, offset + 4, 2, len); proto_tree_add_uint(mbtcp_tree, hf_mbtcp_unitid, tvb, offset + 6, 1, unit_id); /* dissect the Modbus PDU */ next_tvb = tvb_new_subset_length( tvb, offset+7, len-1); /* Continue with dissection of Modbus data payload following Modbus/TCP frame */ if( tvb_reported_length_remaining(tvb, offset) > 0 ) call_dissector_with_data(modbus_handle, next_tvb, pinfo, tree, &modbus_data); return tvb_captured_length(tvb); } static int dissect_mbtcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) { /* Make entries in Protocol column on summary display */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP"); col_clear(pinfo->cinfo, COL_INFO); return dissect_mbtcp_pdu_common(tvb, pinfo, tree, proto_mbtcp, global_mbus_tcp_ports); } static int dissect_mbtls_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) { /* Make entries in Protocol column on summary display */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/TCP Security"); col_clear(pinfo->cinfo, COL_INFO); return dissect_mbtcp_pdu_common(tvb, pinfo, tree, proto_mbtcp, global_mbus_tls_ports); } /* Code to dissect Modbus RTU */ static int dissect_mbrtu_pdu_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, range_t *ports) { /* Set up structures needed to add the protocol subtree and manage it */ proto_item *mi; proto_tree *mbrtu_tree; int offset; tvbuff_t *next_tvb; const char *func_string; const char *pkt_type_str = ""; const char *err_str = ""; uint16_t len, calc_crc16; uint8_t unit_id, function_code, exception_code, subfunction_code; modbus_data_t modbus_data; /* Make entries in Protocol column on summary display */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus RTU"); col_clear(pinfo->cinfo, COL_INFO); len = tvb_reported_length(tvb); unit_id = tvb_get_uint8(tvb, 0); function_code = tvb_get_uint8(tvb, 1) & 0x7F; offset = 0; /* "Request" or "Response" */ modbus_data.packet_type = classify_mbrtu_packet(pinfo, tvb, ports); /* Transaction ID is available only in Modbus TCP */ modbus_data.mbtcp_transid = 0; modbus_data.unit_id = unit_id; switch ( modbus_data.packet_type ) { case QUERY_PACKET : pkt_type_str="Query"; break; case RESPONSE_PACKET : pkt_type_str="Response"; break; case CANNOT_CLASSIFY : err_str="Unable to classify as query or response."; pkt_type_str="unknown"; break; default : break; } /* Find exception - last bit set in function code */ if (tvb_get_uint8(tvb, 1) & 0x80) { exception_code = tvb_get_uint8(tvb, offset + 2); } else { exception_code = 0; } if ((function_code == ENCAP_INTERFACE_TRANSP) && (exception_code == 0)) { func_string = val_to_str_const(tvb_get_uint8(tvb, offset + 2), encap_interface_code_vals, "Encapsulated Interface Transport"); subfunction_code = 1; } else if ((function_code == DIAGNOSTICS) && (exception_code == 0)) { func_string = val_to_str_const(tvb_get_ntohs(tvb, offset + 2), diagnostic_code_vals, "Diagnostics"); subfunction_code = 1; } else { func_string = val_to_str(function_code, function_code_vals, "Unknown function (%d)"); subfunction_code = 0; } if ( exception_code != 0 ) err_str="Exception returned "; /* Make entries in Info column on summary display */ if (subfunction_code == 0) { if (strlen(err_str) > 0) { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Unit: %3u, Func: %3u: %s. %s", pkt_type_str, unit_id, function_code, func_string, err_str); } else { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Unit: %3u, Func: %3u: %s", pkt_type_str, unit_id, function_code, func_string); } } else { if (strlen(err_str) > 0) { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Unit: %3u, Func: %3u/%3u: %s. %s", pkt_type_str, unit_id, function_code, subfunction_code, func_string, err_str); } else { col_add_fstr(pinfo->cinfo, COL_INFO, "%8s: Unit: %3u, Func: %3u/%3u: %s", pkt_type_str, unit_id, function_code, subfunction_code, func_string); } } /* Create protocol tree */ mi = proto_tree_add_protocol_format(tree, proto_mbrtu, tvb, offset, len, "Modbus RTU"); mbrtu_tree = proto_item_add_subtree(mi, ett_mbrtu); /* Add items to protocol tree specific to Modbus RTU */ proto_tree_add_uint(mbrtu_tree, hf_mbrtu_unitid, tvb, offset, 1, unit_id); /* CRC validation */ if (mbrtu_crc) { calc_crc16 = crc16_plain_tvb_offset_seed(tvb, offset, len-2, 0xFFFF); proto_tree_add_checksum(mbrtu_tree, tvb, len-2, hf_mbrtu_crc16, hf_mbrtu_crc16_status, &ei_mbrtu_crc16_incorrect, pinfo, g_htons(calc_crc16), ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY); } else { proto_tree_add_checksum(mbrtu_tree, tvb, len-2, hf_mbrtu_crc16, hf_mbrtu_crc16_status, &ei_mbrtu_crc16_incorrect, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS); } /* when determining payload length, make sure to ignore the unit ID header & CRC-16 footer bytes */ len = len - 3; /* dissect the Modbus PDU */ next_tvb = tvb_new_subset_length( tvb, offset+1, len); /* Continue with dissection of Modbus data payload following Modbus RTU frame */ if( tvb_reported_length_remaining(tvb, offset) > 0 ) call_dissector_with_data(modbus_handle, next_tvb, pinfo, tree, &modbus_data); return tvb_captured_length(tvb); } /* Code to dissect Modbus RTU over TCP packets */ static int dissect_mbrtu_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) { return dissect_mbrtu_pdu_common(tvb, pinfo, tree, global_mbus_tcp_rtu_ports); } /* Return length of Modbus/TCP message */ static unsigned get_mbtcp_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_) { uint16_t plen; /* * Get the length of the data from the encapsulation header. */ plen = tvb_get_ntohs(tvb, offset + 4); /* * That length doesn't include the encapsulation header itself; * add that in. */ return plen + 6; } /* Return length of Modbus RTU over TCP message */ static unsigned get_mbrtu_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset _U_, void *data _U_) { int packet_type; uint8_t function_code; function_code = tvb_get_uint8(tvb, 1); /* Modbus RTU requests do not contain a length field but they are typically a consistent size. Responses do contain a usable 'length' byte at offset 2 XXX - Note that only some function codes are supported by this lookup function; the rest can be added as pcap examples are made available */ /* Determine "Query" or "Response" */ packet_type = classify_mbrtu_packet(pinfo, tvb, global_mbus_tcp_rtu_ports); switch ( packet_type ) { case QUERY_PACKET : switch (function_code) { case READ_COILS: /* Query messages of these types are always 8 bytes */ case READ_DISCRETE_INPUTS: case READ_HOLDING_REGS: case READ_INPUT_REGS: case WRITE_SINGLE_COIL: case WRITE_SINGLE_REG: return 8; case WRITE_MULT_REGS: case WRITE_MULT_COILS: return tvb_get_uint8(tvb, 6) + 9; /* Reported size does not include 2 header, 4 FC15/16-specific, 1 size byte or 2 CRC16 bytes */ default : return tvb_captured_length(tvb); /* Fall back on tvb length */ } case RESPONSE_PACKET : /* The 'exception' bit is set, so this is a 5-byte response */ if (function_code & 0x80) { return 5; } switch (function_code) { case READ_COILS: case READ_DISCRETE_INPUTS: case READ_HOLDING_REGS: case READ_INPUT_REGS: return tvb_get_uint8(tvb, 2) + 5; /* Reported size does not include 2 header, 1 size byte, 2 CRC16 bytes */ case WRITE_SINGLE_COIL: /* Response messages of FC5/6/15/16 are always 8 bytes */ case WRITE_SINGLE_REG: case WRITE_MULT_REGS: case WRITE_MULT_COILS: return 8; default : return tvb_captured_length(tvb); /* Fall back on tvb length */ } case CANNOT_CLASSIFY : default : return tvb_captured_length(tvb); /* Fall back on tvb length */ } } /* Code to dissect Modbus/TCP messages */ static int dissect_mbtcp_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data, dissector_t dissect_pdu) { /* Make sure there's at least enough data to determine it's a Modbus TCP packet */ if (!tvb_bytes_exist(tvb, 0, 8)) return 0; /* check that it actually looks like Modbus/TCP */ /* protocol id == 0 */ if(tvb_get_ntohs(tvb, 2) != 0 ){ return 0; } /* length is at least 2 (unit_id + function_code) */ if(tvb_get_ntohs(tvb, 4) < 2 ){ return 0; } /* build up protocol tree and iterate over multiple packets */ tcp_dissect_pdus(tvb, pinfo, tree, mbtcp_desegment, 6, get_mbtcp_pdu_len, dissect_pdu, data); return tvb_captured_length(tvb); } static int dissect_mbtcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) { return dissect_mbtcp_common(tvb, pinfo, tree, data, dissect_mbtcp_pdu); } static int dissect_mbtls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) { return dissect_mbtcp_common(tvb, pinfo, tree, data, dissect_mbtls_pdu); } static int dissect_mbudp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) { /* Make sure there's at least enough data to determine it's a Modbus UDP packet */ if (!tvb_bytes_exist(tvb, 0, 8)) return 0; /* check that it actually looks like Modbus/TCP */ /* protocol id == 0 */ if(tvb_get_ntohs(tvb, 2) != 0 ){ return 0; } /* length is at least 2 (unit_id + function_code) */ if(tvb_get_ntohs(tvb, 4) < 2 ){ return 0; } /* Make entries in Protocol column on summary display */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "Modbus/UDP"); col_clear(pinfo->cinfo, COL_INFO); return dissect_mbtcp_pdu_common(tvb, pinfo, tree, proto_mbudp, global_mbus_udp_ports); } /* Code to dissect Modbus RTU over TCP messages */ static int dissect_mbrtu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) { /* Make sure there's at least enough data to determine it's a Modbus packet */ /* 5 bytes is the smallest possible valid message (exception response) */ if (!tvb_bytes_exist(tvb, 0, 5)) return 0; /* For Modbus RTU mode, confirm that the first byte is a valid address (non-zero), */ /* so we can eliminate false-positives on Modbus TCP messages loaded as RTU */ if(tvb_get_uint8(tvb, 0) == 0 ) return 0; /* build up protocol tree and iterate over multiple packets */ tcp_dissect_pdus(tvb, pinfo, tree, mbrtu_desegment, 5, get_mbrtu_pdu_len, dissect_mbrtu_pdu, data); return tvb_captured_length(tvb); } static int dissect_mbrtu_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) { /* Make sure there's at least enough data to determine it's a Modbus packet */ /* 5 bytes is the smallest possible valid message (exception response) */ if (tvb_reported_length(tvb) < 5) return 0; return dissect_mbrtu_pdu_common(tvb, pinfo, tree, global_mbus_udp_rtu_ports); } /* Code to allow further dissection of Modbus data payload */ /* Common to both Modbus/TCP and Modbus RTU dissectors */ static void dissect_modbus_data(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, uint8_t function_code, int payload_start, int payload_len, int register_format, uint16_t reg_base, uint16_t num_reg) { int reported_len, data_offset; uint8_t data8, ii; bool data_bool; int16_t data16s; int32_t data32s; uint16_t data16, modflt_lo, modflt_hi, reg_num=reg_base; uint32_t data32, modflt_comb; float data_float, modfloat; proto_tree *bit_tree = NULL; proto_item *bitnum_ti = NULL; proto_item *regnum_ti = NULL; proto_item *register_item = NULL; proto_tree *register_tree = NULL; tvbuff_t *next_tvb; reported_len = tvb_reported_length_remaining(tvb, payload_start); data_offset = 0; if ( payload_start < 0 || ( payload_len + payload_start ) == 0 ) return; /* If calculated length from remaining tvb data != bytes in packet, do not attempt to decode */ if ( payload_len != reported_len ) { proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, reported_len, ENC_NA); return; } /* If data type of payload is Holding or Input registers */ /* AND */ /* if payload length is not a multiple of 4, don't attempt to decode anything in 32-bit format */ if ((function_code == READ_HOLDING_REGS) || (function_code == READ_INPUT_REGS) || (function_code == WRITE_MULT_REGS)) { if ((payload_len % 4 != 0) && ( (register_format == MODBUS_PREF_REGISTER_FORMAT_UINT32) || (register_format == MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT) || (register_format == MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT) ) ) { register_item = proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, payload_len, ENC_NA); expert_add_info(pinfo, register_item, &ei_modbus_data_decode); return; } } /* Build a new tvb containing just the data payload */ next_tvb = tvb_new_subset_length_caplen(tvb, payload_start, payload_len, reported_len); switch ( function_code ) { case READ_COILS: case READ_DISCRETE_INPUTS: case WRITE_MULT_COILS: /* The bit data is packed, 8 bits per byte of data, loop over each bit */ while (data_offset < payload_len) { data8 = tvb_get_uint8(next_tvb, data_offset); for (ii = 0; ii < 8; ii++) { data_bool = (data8 & (1 << ii)) > 0; bit_tree = proto_tree_add_subtree_format(tree, next_tvb, data_offset, 1, ett_bit, NULL, "Bit %u : %u", reg_num, data_bool); bitnum_ti = proto_tree_add_uint(bit_tree, hf_modbus_bitnum, next_tvb, 0, 0, reg_num); proto_item_set_generated(bitnum_ti); proto_tree_add_boolean_bits_format_value(bit_tree, hf_modbus_bitval, next_tvb, 7 - ii, 1, data8, ENC_NA, "%s", tfs_get_true_false(data_bool)); reg_num++; /* If all the requested bits have been read, stop now */ if ((reg_num - reg_base) >= num_reg) { break; } } data_offset++; } break; case READ_HOLDING_REGS: case READ_INPUT_REGS: case WRITE_SINGLE_REG: case WRITE_MULT_REGS: while (data_offset < payload_len) { /* Use "Preferences" options to determine decoding format of register data, as no format is implied by the protocol itself. */ /* Based on a standard register size of 16-bits, use decoding format preference to step through each register and display */ /* it in an appropriate fashion. */ switch (register_format) { case MODBUS_PREF_REGISTER_FORMAT_UINT16: /* Standard-size unsigned integer 16-bit register */ data16 = tvb_get_ntohs(next_tvb, data_offset); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 2, ett_register, NULL, "Register %u (UINT16): %u", reg_num, data16); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum16, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_uint(register_tree, hf_modbus_regval_uint16, next_tvb, data_offset, 2, data16); data_offset += 2; reg_num += 1; break; case MODBUS_PREF_REGISTER_FORMAT_INT16: /* Standard-size signed integer 16-bit register */ data16s = tvb_get_ntohs(next_tvb, data_offset); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 2, ett_register, NULL, "Register %u (INT16): %d", reg_num, data16s); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum16, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_int(register_tree, hf_modbus_regval_int16, next_tvb, data_offset, 2, data16s); data_offset += 2; reg_num += 1; break; case MODBUS_PREF_REGISTER_FORMAT_UINT32: /* Double-size 32-bit unsigned integer (2 sequential 16-bit registers) */ data32 = tvb_get_ntohl(next_tvb, data_offset); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 4, ett_register, NULL, "Register %u (UINT32): %u", reg_num, data32); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum32, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_uint(register_tree, hf_modbus_regval_uint32, next_tvb, data_offset, 4, data32); data_offset += 4; reg_num += 2; break; case MODBUS_PREF_REGISTER_FORMAT_INT32: /* Double-size 32-bit signed integer (2 sequential 16-bit registers) */ data32s = tvb_get_ntohl(next_tvb, data_offset); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 4, ett_register, NULL, "Register %u (INT32): %d", reg_num, data32s); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum32, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_int(register_tree, hf_modbus_regval_int32, next_tvb, data_offset, 4, data32s); data_offset += 4; reg_num += 2; break; case MODBUS_PREF_REGISTER_FORMAT_IEEE_FLOAT: /* 32-bit IEEE Floating Point, (2 sequential 16-bit registers) */ data_float = tvb_get_ntohieee_float(next_tvb, data_offset); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 4, ett_register, NULL, "Register %u (IEEE Float): %f", reg_num, data_float); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum32, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_float(register_tree, hf_modbus_regval_ieee_float, next_tvb, data_offset, 4, data_float); data_offset += 4; reg_num += 2; break; case MODBUS_PREF_REGISTER_FORMAT_MODICON_FLOAT: /* Modicon Floating Point (word-swapped, 2 sequential 16-bit registers) */ /* Modicon-style Floating Point values are stored in reverse-word order. */ /* ie: a standard IEEE float value 59.991459 is equal to 0x426ff741 */ /* while the Modicon equivalent to this value is 0xf741426f */ /* To re-assemble a proper IEEE float, we must retrieve the 2 x 16-bit words, bit-shift the */ /* "hi" component by 16-bits and then OR them together into a combined 32-bit int. */ /* Following that operation, use some memcpy magic to copy the 4 raw data bytes from the */ /* 32-bit integer into a standard float. Not sure if there is a cleaner way possible using */ /* the Wireshark libraries, but this seems to work OK. */ modflt_lo = tvb_get_ntohs(next_tvb, data_offset); modflt_hi = tvb_get_ntohs(next_tvb, data_offset+2); modflt_comb = (uint32_t)(modflt_hi<<16) | modflt_lo; memcpy(&modfloat, &modflt_comb, 4); register_tree = proto_tree_add_subtree_format( tree, next_tvb, data_offset, 4, ett_register, NULL, "Register %u (Modicon Float): %f", reg_num, modfloat); regnum_ti = proto_tree_add_uint(register_tree, hf_modbus_regnum32, next_tvb, 0, 0, reg_num); proto_item_set_generated(regnum_ti); proto_tree_add_float(register_tree, hf_modbus_regval_modicon_float, next_tvb, data_offset, 4, modfloat); data_offset += 4; reg_num += 2; break; default: /* Avoid any chance of an infinite loop */ data_offset = payload_len; break; } /* register format switch */ } /* while loop */ break; default: if ( ! dissector_try_string(modbus_data_dissector_table, "data", next_tvb, pinfo, tree, NULL) ) proto_tree_add_item(tree, hf_modbus_data, tvb, payload_start, payload_len, ENC_NA); break; } } /* Code to dissect Modbus request message */ static int dissect_modbus_request(tvbuff_t *tvb, packet_info *pinfo, proto_tree *modbus_tree, uint8_t function_code, int payload_start, int payload_len, modbus_pkt_info_t *pkt_info) { proto_tree *group_tree; int byte_cnt, num_reg, group_offset, ii; uint8_t mei_code; uint16_t reg_base=0, diagnostic_code; uint32_t group_byte_cnt, group_word_cnt; if (!pkt_info) { return 0; } switch (function_code) { case READ_COILS: case READ_DISCRETE_INPUTS: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); break; case READ_HOLDING_REGS: case READ_INPUT_REGS: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); break; case WRITE_SINGLE_COIL: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 1, pkt_info->register_format, reg_base, 0); proto_tree_add_item(modbus_tree, hf_modbus_padding, tvb, payload_start + 3, 1, ENC_NA); break; case WRITE_SINGLE_REG: reg_base = tvb_get_ntohs(tvb, payload_start); proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 2, pkt_info->register_format, reg_base, 0); break; case READ_EXCEPT_STAT: /* Do Nothing */ break; case DIAGNOSTICS: diagnostic_code = tvb_get_ntohs(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_diag_sf, tvb, payload_start, 2, diagnostic_code); switch(diagnostic_code) { case RETURN_QUERY_DATA: if (payload_len > 2) proto_tree_add_item(modbus_tree, hf_modbus_diag_return_query_data_request, tvb, payload_start+2, payload_len-2, ENC_NA); break; case RESTART_COMMUNICATION_OPTION: proto_tree_add_item(modbus_tree, hf_modbus_diag_restart_communication_option, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case CHANGE_ASCII_INPUT_DELIMITER: proto_tree_add_item(modbus_tree, hf_modbus_diag_ascii_input_delimiter, tvb, payload_start+2, 1, ENC_BIG_ENDIAN); break; case RETURN_DIAGNOSTIC_REGISTER: /* 00 00 Data Field */ case FORCE_LISTEN_ONLY_MODE: /* 00 00 Data Field */ case CLEAR_COUNTERS_AND_DIAG_REG: /* 00 00 Data Field */ case RETURN_BUS_MESSAGE_COUNT: /* 00 00 Data Field */ case RETURN_BUS_COMM_ERROR_COUNT: /* 00 00 Data Field */ case RETURN_BUS_EXCEPTION_ERROR_COUNT: /* 00 00 Data Field */ case RETURN_SLAVE_MESSAGE_COUNT: /* 00 00 Data Field */ case RETURN_SLAVE_NO_RESPONSE_COUNT: /* 00 00 Data Field */ case RETURN_SLAVE_NAK_COUNT: /* 00 00 Data Field */ case RETURN_SLAVE_BUSY_COUNT: /* 00 00 Data Field */ case RETURN_BUS_CHAR_OVERRUN_COUNT: /* 00 00 Data Field */ case CLEAR_OVERRUN_COUNTER_AND_FLAG: default: if (payload_len > 2) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start+2, payload_len-2, pkt_info->register_format, reg_base, 0); break; } break; case WRITE_MULT_COILS: reg_base = tvb_get_ntohs(tvb, payload_start); num_reg = tvb_get_ntohs(tvb, payload_start + 2); proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start + 4); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1, byte_cnt); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 5, byte_cnt, pkt_info->register_format, reg_base, num_reg); break; case WRITE_MULT_REGS: reg_base = tvb_get_ntohs(tvb, payload_start); proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start + 4); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 4, 1, byte_cnt); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 5, byte_cnt, pkt_info->register_format, reg_base, 0); break; case READ_FILE_RECORD: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; for (ii = 0; ii < byte_cnt / 7; ii++) { group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, 7, ett_group_hdr, NULL, "Group %u", ii); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN); proto_tree_add_item(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, ENC_BIG_ENDIAN); group_offset += 7; } break; case WRITE_FILE_RECORD: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; ii = 0; while (byte_cnt > 0) { group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5); group_byte_cnt = (2 * group_word_cnt) + 7; group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, group_byte_cnt, ett_group_hdr, NULL, "Group %u", ii); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN); proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, group_word_cnt); dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 7, group_byte_cnt - 7, pkt_info->register_format, reg_base, 0); group_offset += group_byte_cnt; byte_cnt -= group_byte_cnt; ii++; } break; case MASK_WRITE_REG: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN); break; case READ_WRITE_REG: proto_tree_add_item(modbus_tree, hf_modbus_readref, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_readwordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_writeref, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_writewordcnt, tvb, payload_start + 6, 2, ENC_BIG_ENDIAN); byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start + 8); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start + 8, 1, byte_cnt); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 9, byte_cnt, pkt_info->register_format, reg_base, 0); break; case READ_FIFO_QUEUE: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); break; case ENCAP_INTERFACE_TRANSP: proto_tree_add_item(modbus_tree, hf_modbus_mei, tvb, payload_start, 1, ENC_BIG_ENDIAN); mei_code = tvb_get_uint8(tvb, payload_start); switch (mei_code) { case READ_DEVICE_ID: proto_tree_add_item(modbus_tree, hf_modbus_read_device_id, tvb, payload_start+1, 1, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_object_id, tvb, payload_start+2, 1, ENC_BIG_ENDIAN); break; case CANOPEN_REQ_RESP: /* CANopen protocol not part of the Modbus/TCP specification */ default: if (payload_len > 1) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len-1, pkt_info->register_format, reg_base, 0); break; } break; case REPORT_SLAVE_ID: default: if (payload_len > 0) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, pkt_info->register_format, reg_base, 0); break; } /* Function Code */ return tvb_captured_length(tvb); } /* Code to dissect Modbus Response message */ static int dissect_modbus_response(tvbuff_t *tvb, packet_info *pinfo, proto_tree *modbus_tree, uint8_t function_code, int payload_start, int payload_len, modbus_pkt_info_t *pkt_info) { proto_tree *group_tree, *event_tree, *event_item_tree, *device_objects_tree, *device_objects_item_tree; proto_item *mei; int byte_cnt, group_offset, event_index, object_index, object_len, num_objects, ii; uint8_t object_type, mei_code, event_code; uint16_t diagnostic_code, num_reg; uint32_t group_byte_cnt, group_word_cnt; nstime_t response_time; proto_item *request_frame_item, *response_time_item; if (!pkt_info) { return 0; } num_reg = pkt_info->num_reg; if (pkt_info->request_found == true) { request_frame_item = proto_tree_add_uint(modbus_tree, hf_modbus_request_frame, tvb, 0, 0, pkt_info->req_frame_num); proto_item_set_generated(request_frame_item); nstime_delta(&response_time, &pinfo->abs_ts, &pkt_info->req_time); response_time_item = proto_tree_add_time(modbus_tree, hf_modbus_response_time, tvb, 0, 0, &response_time); proto_item_set_generated(response_time_item); } switch (function_code) { case READ_COILS: case READ_DISCRETE_INPUTS: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); //if the request wasn't found set number of coils based on byte count if (!pkt_info->request_found) num_reg = byte_cnt*8; dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, pkt_info->register_format, pkt_info->reg_base, num_reg); break; case READ_HOLDING_REGS: case READ_INPUT_REGS: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, pkt_info->register_format, pkt_info->reg_base, 0); break; case WRITE_SINGLE_COIL: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 1, pkt_info->register_format, pkt_info->reg_base, 0); proto_tree_add_item(modbus_tree, hf_modbus_padding, tvb, payload_start + 3, 1, ENC_NA); break; case WRITE_SINGLE_REG: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 2, 2, pkt_info->register_format, pkt_info->reg_base, 0); break; case READ_EXCEPT_STAT: dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, 1, pkt_info->register_format, pkt_info->reg_base, 0); break; case DIAGNOSTICS: diagnostic_code = tvb_get_ntohs(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_diag_sf, tvb, payload_start, 2, diagnostic_code); switch(diagnostic_code) { case RETURN_QUERY_DATA: /* Echo of Request */ if (payload_len > 2) proto_tree_add_item(modbus_tree, hf_modbus_diag_return_query_data_echo, tvb, payload_start+2, payload_len-2, ENC_NA); break; case RESTART_COMMUNICATION_OPTION: /* Echo of Request */ proto_tree_add_item(modbus_tree, hf_modbus_diag_restart_communication_option, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_DIAGNOSTIC_REGISTER: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_diag_register, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case CHANGE_ASCII_INPUT_DELIMITER: /* XXX - Do we expect this to ever be a response? */ proto_tree_add_item(modbus_tree, hf_modbus_diag_ascii_input_delimiter, tvb, payload_start+2, 1, ENC_BIG_ENDIAN); break; case CLEAR_COUNTERS_AND_DIAG_REG: /* Echo of Request */ proto_tree_add_item(modbus_tree, hf_modbus_diag_clear_ctr_diag_reg, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_BUS_MESSAGE_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_message_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_BUS_COMM_ERROR_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_comm_error_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_BUS_EXCEPTION_ERROR_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_exception_error_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_SLAVE_MESSAGE_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_message_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_SLAVE_NO_RESPONSE_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_no_slave_response_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_SLAVE_NAK_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_nak_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_SLAVE_BUSY_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_slave_busy_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case RETURN_BUS_CHAR_OVERRUN_COUNT: proto_tree_add_item(modbus_tree, hf_modbus_diag_return_bus_char_overrun_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case CLEAR_OVERRUN_COUNTER_AND_FLAG: /* Echo of Request */ case FORCE_LISTEN_ONLY_MODE: /* No response anticipated */ default: if (payload_len > 2) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start+2, payload_len-2, pkt_info->register_format, pkt_info->reg_base, 0); break; } /* diagnostic_code */ break; case GET_COMM_EVENT_CTRS: proto_tree_add_item(modbus_tree, hf_modbus_status, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_event_count, tvb, payload_start+2, 2, ENC_BIG_ENDIAN); break; case GET_COMM_EVENT_LOG: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); proto_tree_add_item(modbus_tree, hf_modbus_status, tvb, payload_start+1, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_event_count, tvb, payload_start+3, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_message_count, tvb, payload_start+5, 2, ENC_BIG_ENDIAN); if (byte_cnt-6 > 0) { byte_cnt -= 6; event_index = 0; event_tree = proto_tree_add_subtree(modbus_tree, tvb, payload_start+7, byte_cnt, ett_events, NULL, "Events"); while (byte_cnt > 0) { event_code = tvb_get_uint8(tvb, payload_start+7+event_index); if (event_code == 0) { proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Initiated Communication Restart"); } else if (event_code == 4) { proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Entered Listen Only Mode"); } else if (event_code & REMOTE_DEVICE_RECV_EVENT_MASK) { mei = proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Receive Event: 0x%02X", event_code); event_item_tree = proto_item_add_subtree(mei, ett_events_recv); /* add subtrees to describe each event bit */ proto_tree_add_item(event_item_tree, hf_modbus_event_recv_comm_err, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_recv_char_over, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_recv_lo_mode, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_recv_broadcast, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); } else if ((event_code & REMOTE_DEVICE_SEND_EVENT_MASK) == REMOTE_DEVICE_SEND_EVENT_VALUE) { mei = proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Send Event: 0x%02X", event_code); event_item_tree = proto_item_add_subtree(mei, ett_events_send); /* add subtrees to describe each event bit */ proto_tree_add_item(event_item_tree, hf_modbus_event_send_read_ex, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_abort_ex, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_busy_ex, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_send_slave_nak_ex, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_send_write_timeout, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); proto_tree_add_item(event_item_tree, hf_modbus_event_send_lo_mode, tvb, payload_start+7+event_index, 1, ENC_LITTLE_ENDIAN ); } else { proto_tree_add_uint_format(event_tree, hf_modbus_event, tvb, payload_start+7+event_index, 1, event_code, "Unknown Event"); } byte_cnt--; event_index++; } } break; case WRITE_MULT_COILS: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_bitcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); break; case WRITE_MULT_REGS: proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); break; case READ_FILE_RECORD: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; ii = 0; while (byte_cnt > 0) { group_byte_cnt = (uint32_t)tvb_get_uint8(tvb, group_offset); group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, group_byte_cnt + 1, ett_group_hdr, NULL, "Group %u", ii); proto_tree_add_uint(group_tree, hf_modbus_bytecnt, tvb, group_offset, 1, group_byte_cnt); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset + 1, 1, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 2, group_byte_cnt - 1, pkt_info->register_format, pkt_info->reg_base, 0); group_offset += (group_byte_cnt + 1); byte_cnt -= (group_byte_cnt + 1); ii++; } break; case WRITE_FILE_RECORD: /* Normal response is echo of request */ byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); /* add subtrees to describe each group of packet */ group_offset = payload_start + 1; ii = 0; while (byte_cnt > 0) { group_word_cnt = tvb_get_ntohs(tvb, group_offset + 5); group_byte_cnt = (2 * group_word_cnt) + 7; group_tree = proto_tree_add_subtree_format( modbus_tree, tvb, group_offset, group_byte_cnt, ett_group_hdr, NULL, "Group %u", ii); proto_tree_add_item(group_tree, hf_modbus_reftype, tvb, group_offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(group_tree, hf_modbus_lreference, tvb, group_offset + 1, 4, ENC_BIG_ENDIAN); proto_tree_add_uint(group_tree, hf_modbus_wordcnt, tvb, group_offset + 5, 2, group_word_cnt); dissect_modbus_data(tvb, pinfo, group_tree, function_code, group_offset + 7, group_byte_cnt - 7, pkt_info->register_format, pkt_info->reg_base, 0); group_offset += group_byte_cnt; byte_cnt -= group_byte_cnt; ii++; } break; case MASK_WRITE_REG: /* Normal response is echo of request */ proto_tree_add_item(modbus_tree, hf_modbus_reference, tvb, payload_start, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_andmask, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_ormask, tvb, payload_start + 4, 2, ENC_BIG_ENDIAN); break; case READ_WRITE_REG: byte_cnt = (uint32_t)tvb_get_uint8(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_bytecnt, tvb, payload_start, 1, byte_cnt); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 1, byte_cnt, pkt_info->register_format, pkt_info->reg_base, 0); break; case READ_FIFO_QUEUE: byte_cnt = (uint32_t)tvb_get_ntohs(tvb, payload_start); proto_tree_add_uint(modbus_tree, hf_modbus_lbytecnt, tvb, payload_start, 2, byte_cnt); proto_tree_add_item(modbus_tree, hf_modbus_wordcnt, tvb, payload_start + 2, 2, ENC_BIG_ENDIAN); dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start + 4, byte_cnt - 2, pkt_info->register_format, pkt_info->reg_base, 0); break; case ENCAP_INTERFACE_TRANSP: proto_tree_add_item(modbus_tree, hf_modbus_mei, tvb, payload_start, 1, ENC_BIG_ENDIAN); mei_code = tvb_get_uint8(tvb, payload_start); switch (mei_code) { case READ_DEVICE_ID: proto_tree_add_item(modbus_tree, hf_modbus_read_device_id, tvb, payload_start+1, 1, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_conformity_level, tvb, payload_start+2, 1, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_more_follows, tvb, payload_start+3, 1, ENC_BIG_ENDIAN); proto_tree_add_item(modbus_tree, hf_modbus_next_object_id, tvb, payload_start+4, 1, ENC_BIG_ENDIAN); num_objects = tvb_get_uint8(tvb, payload_start+5); proto_tree_add_uint(modbus_tree, hf_modbus_num_objects, tvb, payload_start+5, 1, num_objects); device_objects_tree = proto_tree_add_subtree(modbus_tree, tvb, payload_start+6, payload_len-6, ett_device_id_objects, NULL, "Objects"); object_index = 0; for (ii = 0; ii < num_objects; ii++) { /* add each "object item" as its own subtree */ /* compute length of object */ object_type = tvb_get_uint8(tvb, payload_start+6+object_index); object_len = tvb_get_uint8(tvb, payload_start+6+object_index+1); device_objects_item_tree = proto_tree_add_subtree_format(device_objects_tree, tvb, payload_start+6+object_index, 2+object_len, ett_device_id_object_items, NULL, "Object #%d", ii+1); proto_tree_add_item(device_objects_item_tree, hf_modbus_object_id, tvb, payload_start+6+object_index, 1, ENC_BIG_ENDIAN); object_index++; proto_tree_add_uint(device_objects_item_tree, hf_modbus_list_object_len, tvb, payload_start+6+object_index, 1, object_len); object_index++; if (object_type < 7) { proto_tree_add_item(device_objects_item_tree, hf_modbus_object_str_value, tvb, payload_start+6+object_index, object_len, ENC_ASCII); } else { if (object_len > 0) proto_tree_add_item(device_objects_item_tree, hf_modbus_object_value, tvb, payload_start+6+object_index, object_len, ENC_NA); } object_index += object_len; } /* for ii */ break; case CANOPEN_REQ_RESP: /* CANopen protocol not part of the Modbus/TCP specification */ default: if (payload_len > 1) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len-1, pkt_info->register_format, pkt_info->reg_base, 0); break; } /* mei_code */ break; case REPORT_SLAVE_ID: default: if (payload_len > 0) dissect_modbus_data(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, pkt_info->register_format, pkt_info->reg_base, 0); break; } /* function code */ return tvb_captured_length(tvb); } /* Dissect the Modbus Payload. Called from either Modbus/TCP or Modbus RTU Dissector */ static int dissect_modbus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) { proto_tree *modbus_tree; proto_item *mi; int offset = 0; modbus_data_t *modbus_data = (modbus_data_t*)data; int payload_start, payload_len, len; uint8_t function_code, exception_code; modbus_pkt_info_t *pkt_info; uint32_t conv_key; /* Reject the packet if data passed from the mbrtu or mbtcp dissector is NULL */ if (modbus_data == NULL) return 0; len = tvb_captured_length(tvb); /* If the packet is zero-length, we should not attempt to dissect any further */ if (len == 0) return 0; /* Add items to protocol tree specific to Modbus */ mi = proto_tree_add_protocol_format(tree, proto_modbus, tvb, offset, len, "Modbus"); modbus_tree = proto_item_add_subtree(mi, ett_modbus_hdr); function_code = tvb_get_uint8(tvb, offset) & 0x7F; proto_tree_add_item(modbus_tree, hf_modbus_functioncode, tvb, offset, 1, ENC_BIG_ENDIAN); /* Conversation support */ /* Use a combination of unit and transaction-id as key for identifying a request to a response*/ conv_key = (uint32_t)modbus_data->mbtcp_transid | ((uint32_t)modbus_data->unit_id << 16); if (!pinfo->fd->visited) { conversation_t *conversation = NULL; modbus_conversation *modbus_conv_data = NULL; /* Find a conversation, create a new if no one exists */ conversation = find_or_create_conversation(pinfo); modbus_conv_data = (modbus_conversation *)conversation_get_proto_data(conversation, proto_modbus); pkt_info = wmem_new0(wmem_file_scope(), modbus_pkt_info_t); if (modbus_conv_data == NULL){ modbus_conv_data = wmem_new(wmem_file_scope(), modbus_conversation); modbus_conv_data->modbus_request_frame_data = wmem_list_new(wmem_file_scope()); modbus_conv_data->register_format = global_mbus_register_format; conversation_add_proto_data(conversation, proto_modbus, (void *)modbus_conv_data); } pkt_info->register_format = modbus_conv_data->register_format; if (modbus_data->packet_type == QUERY_PACKET) { /*create the modbus_request frame. It holds the request information.*/ modbus_request_info_t *frame_ptr = wmem_new0(wmem_file_scope(), modbus_request_info_t); int captured_length = tvb_captured_length(tvb); /* load information into the modbus request frame */ frame_ptr->fnum = pinfo->num; frame_ptr->function_code = function_code; frame_ptr->mbtcp_transid = modbus_data->mbtcp_transid; frame_ptr->unit_id = modbus_data->unit_id; if (captured_length >= 3) { pkt_info->reg_base = frame_ptr->base_address = tvb_get_ntohs(tvb, 1); if (captured_length >= 5) pkt_info->num_reg = frame_ptr->num_reg = tvb_get_ntohs(tvb, 3); } frame_ptr->req_time = pinfo->abs_ts; wmem_list_prepend(modbus_conv_data->modbus_request_frame_data, frame_ptr); } else if (modbus_data->packet_type == RESPONSE_PACKET) { uint8_t req_function_code; uint16_t req_transaction_id; uint8_t req_unit_id; uint32_t req_frame_num; modbus_request_info_t *request_data; wmem_list_frame_t *frame = wmem_list_head(modbus_conv_data->modbus_request_frame_data); /* Step backward through all logged instances of request frames, looking for a request frame number that occurred immediately prior to current frame number that has a matching function code, unit-id and transaction identifier */ while (frame && !pkt_info->request_found) { request_data = (modbus_request_info_t *)wmem_list_frame_data(frame); req_frame_num = request_data->fnum; req_function_code = request_data->function_code; req_transaction_id = request_data->mbtcp_transid; req_unit_id = request_data->unit_id; if ((pinfo->num > req_frame_num) && (req_function_code == function_code) && (req_transaction_id == modbus_data->mbtcp_transid) && (req_unit_id == modbus_data->unit_id)) { pkt_info->reg_base = request_data->base_address; pkt_info->num_reg = request_data->num_reg; pkt_info->request_found = true; pkt_info->req_frame_num = req_frame_num; pkt_info->req_time = request_data->req_time; } frame = wmem_list_frame_next(frame); } } p_add_proto_data(wmem_file_scope(), pinfo, proto_modbus, conv_key, pkt_info); } else { /* !visited */ pkt_info = (modbus_pkt_info_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_modbus, conv_key); } /* Find exception - last bit set in function code */ if (tvb_get_uint8(tvb, offset) & 0x80 ) { exception_code = tvb_get_uint8(tvb, offset+1); } else { exception_code = 0; } payload_start = offset + 1; payload_len = len - 1; if (exception_code != 0) { proto_item_set_text(mi, "Function %u: %s. Exception: %s", function_code, val_to_str_const(function_code, function_code_vals, "Unknown Function"), val_to_str(exception_code, exception_code_vals, "Unknown Exception Code (%u)")); proto_tree_add_uint(modbus_tree, hf_modbus_exceptioncode, tvb, payload_start, 1, exception_code); } else { /* Follow different dissection path depending on whether packet is query or response */ if (modbus_data->packet_type == QUERY_PACKET) { dissect_modbus_request(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, pkt_info); } else if (modbus_data->packet_type == RESPONSE_PACKET) { dissect_modbus_response(tvb, pinfo, modbus_tree, function_code, payload_start, payload_len, pkt_info); } } return tvb_captured_length(tvb); } static void apply_mbtcp_prefs(void) { /* Modbus/RTU uses the port preference to determine request/response */ global_mbus_tcp_ports = prefs_get_range_value("mbtcp", "tcp.port"); global_mbus_udp_ports = prefs_get_range_value("mbudp", "udp.port"); global_mbus_tls_ports = prefs_get_range_value("mbtcp", "tls.port"); } static void apply_mbrtu_prefs(void) { /* Modbus/RTU uses the port preference to determine request/response */ global_mbus_tcp_rtu_ports = prefs_get_range_value("mbrtu", "tcp.port"); global_mbus_udp_rtu_ports = prefs_get_range_value("mbrtu", "udp.port"); } /* Register the protocol with Wireshark */ void proto_register_modbus(void) { /* Modbus/TCP header fields */ static hf_register_info mbtcp_hf[] = { { &hf_mbtcp_transid, { "Transaction Identifier", "mbtcp.trans_id", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_mbtcp_protid, { "Protocol Identifier", "mbtcp.prot_id", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_mbtcp_len, { "Length", "mbtcp.len", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_mbtcp_unitid, { "Unit Identifier", "mbtcp.unit_id", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, }; static ei_register_info mbtcp_ei[] = { { &ei_mbtcp_cannot_classify, { "mbtcp.cannot_classify", PI_PROTOCOL, PI_WARN, "Cannot classify packet type. Try setting Modbus/TCP Port preference to this destination or source port", EXPFILL } }, }; /* Modbus RTU header fields */ static hf_register_info mbrtu_hf[] = { { &hf_mbrtu_unitid, { "Unit ID", "mbrtu.unit_id", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_mbrtu_crc16, { "CRC-16", "mbrtu.crc16", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_mbrtu_crc16_status, { "CRC-16 Status", "mbrtu.crc16.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0, NULL, HFILL } }, }; static ei_register_info mbrtu_ei[] = { { &ei_mbrtu_crc16_incorrect, { "mbrtu.crc16.incorrect", PI_CHECKSUM, PI_WARN, "Incorrect CRC", EXPFILL } }, }; /* Modbus header fields */ static hf_register_info hf[] = { { &hf_modbus_request_frame, { "Request Frame", "modbus.request_frame", FT_FRAMENUM, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_response_time, { "Time from request", "modbus.response_time", FT_RELATIVE_TIME, BASE_NONE, NULL, 0x0, "Time between request and reply", HFILL } }, { &hf_modbus_functioncode, { "Function Code", "modbus.func_code", FT_UINT8, BASE_DEC, VALS(function_code_vals), 0x7F, NULL, HFILL } }, { &hf_modbus_reference, { "Reference Number", "modbus.reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_padding, { "Padding", "modbus.padding", FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_lreference, { "Reference Number (32 bit)", "modbus.reference_num_32", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_reftype, { "Reference Type", "modbus.reference_type", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_readref, { "Read Reference Number", "modbus.read_reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_writeref, { "Write Reference Number", "modbus.write_reference_num", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_wordcnt, { "Word Count", "modbus.word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_readwordcnt, { "Read Word Count", "modbus.read_word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_writewordcnt, { "Write Word Count", "modbus.write_word_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_bitcnt, { "Bit Count", "modbus.bit_cnt", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_bytecnt, { "Byte Count", "modbus.byte_cnt", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_lbytecnt, { "Byte Count (16-bit)", "modbus.byte_cnt_16", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_exceptioncode, { "Exception Code", "modbus.exception_code", FT_UINT8, BASE_DEC, VALS(exception_code_vals), 0x0, NULL, HFILL } }, { &hf_modbus_diag_sf, { "Diagnostic Code", "modbus.diagnostic_code", FT_UINT16, BASE_DEC, VALS(diagnostic_code_vals), 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_query_data_request, { "Request Data", "modbus.diagnostic.return_query_data.request", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_query_data_echo, { "Echo Data", "modbus.diagnostic.return_query_data.echo", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_restart_communication_option, { "Restart Communication Option", "modbus.diagnostic.restart_communication_option", FT_UINT16, BASE_HEX, VALS(diagnostic_restart_communication_option_vals), 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_diag_register, { "Diagnostic Register Contents", "modbus.diagnostic.return_diag_register", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_ascii_input_delimiter, { "CHAR", "modbus.diagnostic.ascii_input_delimiter", FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_clear_ctr_diag_reg, { "Clear Counters & Diag Register Echo", "modbus.diagnostic.clear_ctr_diag_reg", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_bus_message_count, { "Total Message Count", "modbus.diagnostic.bus_message_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_bus_comm_error_count, { "CRC Error Count", "modbus.diagnostic.bus_comm_error_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_bus_exception_error_count, { "Exception Error Count", "modbus.diagnostic.bus_exception_error_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_slave_message_count, { "Slave Message Count", "modbus.diagnostic.slave_message_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_no_slave_response_count, { "Slave No Response Count", "modbus.diagnostic.no_slave_response_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_slave_nak_count, { "Slave NAK Count", "modbus.diagnostic.slave_nak_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_slave_busy_count, { "Slave Device Busy Count", "modbus.diagnostic.slave_busy_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_diag_return_bus_char_overrun_count, { "Slave Character Overrun Count", "modbus.diagnostic.bus_char_overrun_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_status, { "Status", "modbus.ev_status", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_event, { "Event", "modbus.event", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_event_count, { "Event Count", "modbus.ev_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_message_count, { "Message Count", "modbus.ev_msg_count", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_event_recv_comm_err, { "Communication Error", "modbus.ev_recv_comm_err", FT_UINT8, BASE_DEC, NULL, 0x02, NULL, HFILL } }, { &hf_modbus_event_recv_char_over, { "Character Overrun", "modbus.ev_recv_char_over", FT_UINT8, BASE_DEC, NULL, 0x10, NULL, HFILL } }, { &hf_modbus_event_recv_lo_mode, { "Currently in Listen Only Mode", "modbus.ev_recv_lo_mode", FT_UINT8, BASE_DEC, NULL, 0x20, NULL, HFILL } }, { &hf_modbus_event_recv_broadcast, { "Broadcast Received", "modbus.ev_recv_broadcast", FT_UINT8, BASE_DEC, NULL, 0x40, NULL, HFILL } }, { &hf_modbus_event_send_read_ex, { "Read Exception Sent", "modbus.ev_send_read_ex", FT_UINT8, BASE_DEC, NULL, 0x01, NULL, HFILL } }, { &hf_modbus_event_send_slave_abort_ex, { "Slave Abort Exception Sent", "modbus.ev_send_slave_abort_ex", FT_UINT8, BASE_DEC, NULL, 0x02, NULL, HFILL } }, { &hf_modbus_event_send_slave_busy_ex, { "Slave Busy Exception Sent", "modbus.ev_send_slave_busy_ex", FT_UINT8, BASE_DEC, NULL, 0x04, NULL, HFILL } }, { &hf_modbus_event_send_slave_nak_ex, { "Slave Program NAK Exception Sent", "modbus.ev_send_slave_nak_ex", FT_UINT8, BASE_DEC, NULL, 0x08, NULL, HFILL } }, { &hf_modbus_event_send_write_timeout, { "Write Timeout Error Occurred", "modbus.ev_send_write_timeout", FT_UINT8, BASE_DEC, NULL, 0x10, NULL, HFILL } }, { &hf_modbus_event_send_lo_mode, { "Currently in Listen Only Mode", "modbus.ev_send_lo_mode", FT_UINT8, BASE_DEC, NULL, 0x20, NULL, HFILL } }, { &hf_modbus_andmask, { "AND mask", "modbus.and_mask", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_ormask, { "OR mask", "modbus.or_mask", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_data, { "Data", "modbus.data", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_mei, { "MEI type", "modbus.mei", FT_UINT8, BASE_DEC, VALS(encap_interface_code_vals), 0x0, NULL, HFILL } }, { &hf_modbus_read_device_id, { "Read Device ID", "modbus.read_device_id", FT_UINT8, BASE_DEC, VALS(read_device_id_vals), 0x0, NULL, HFILL } }, { &hf_modbus_object_id, { "Object ID", "modbus.object_id", FT_UINT8, BASE_DEC, VALS(object_id_vals), 0x0, NULL, HFILL } }, { &hf_modbus_num_objects, { "Number of Objects", "modbus.num_objects", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_list_object_len, { "Object length", "modbus.objects_len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_conformity_level, { "Conformity Level", "modbus.conformity_level", FT_UINT8, BASE_HEX, VALS(conformity_level_vals), 0x0, NULL, HFILL } }, { &hf_modbus_more_follows, { "More Follows", "modbus.more_follows", FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_next_object_id, { "Next Object ID", "modbus.next_object_id", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_object_str_value, { "Object String Value", "modbus.object_str_value", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_object_value, { "Object Value", "modbus.object_value", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_bitnum, { "Bit Number", "modbus.bitnum", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_bitval, { "Bit Value", "modbus.bitval", FT_BOOLEAN, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regnum16, { "Register Number", "modbus.regnum16", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regnum32, { "Register Number", "modbus.regnum32", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_uint16, { "Register Value (UINT16)", "modbus.regval_uint16", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_int16, { "Register Value (INT16)", "modbus.regval_int16", FT_INT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_uint32, { "Register Value (UINT32)", "modbus.regval_uint32", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_int32, { "Register Value (INT32)", "modbus.regval_int32", FT_INT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_ieee_float, { "Register Value (IEEE Float)", "modbus.regval_float", FT_FLOAT, BASE_NONE, NULL, 0x0, NULL, HFILL } }, { &hf_modbus_regval_modicon_float, { "Register Value (Modicon Float)", "modbus.regval_float", FT_FLOAT, BASE_NONE, NULL, 0x0, NULL, HFILL } }, }; /* Setup protocol subtree array */ static int *ett[] = { &ett_mbtcp, &ett_mbrtu, &ett_modbus_hdr, &ett_group_hdr, &ett_events, &ett_events_recv, &ett_events_send, &ett_device_id_objects, &ett_device_id_object_items, &ett_bit, &ett_register }; static ei_register_info ei[] = { { &ei_modbus_data_decode, { "modbus.data.decode", PI_PROTOCOL, PI_WARN, "Invalid decoding options, register data not a multiple of 4!", EXPFILL } }, }; module_t *mbtcp_module; module_t *mbrtu_module; module_t *modbus_module; expert_module_t* expert_mbtcp; expert_module_t* expert_mbrtu; expert_module_t* expert_modbus; /* Register the protocol name and description */ proto_mbtcp = proto_register_protocol("Modbus/TCP", "Modbus/TCP", "mbtcp"); proto_mbudp = proto_register_protocol("Modbus/UDP", "Modbus/UDP", "mbudp"); proto_mbrtu = proto_register_protocol("Modbus RTU", "Modbus RTU", "mbrtu"); proto_modbus = proto_register_protocol("Modbus", "Modbus", "modbus"); /* Registering protocol to be called by another dissector */ modbus_handle = register_dissector("modbus", dissect_modbus, proto_modbus); mbtcp_handle = register_dissector("mbtcp", dissect_mbtcp, proto_mbtcp); mbtls_handle = register_dissector("mbtls", dissect_mbtls, proto_mbtcp); mbrtu_handle = register_dissector("mbrtu", dissect_mbrtu, proto_mbrtu); mbudp_handle = register_dissector("mbudp", dissect_mbudp, proto_mbudp); /* Registering subdissectors table */ modbus_data_dissector_table = register_dissector_table("modbus.data", "Modbus Data", proto_modbus, FT_STRING, STRING_CASE_SENSITIVE); modbus_dissector_table = register_dissector_table("mbtcp.prot_id", "Modbus/TCP protocol identifier", proto_mbtcp, FT_UINT16, BASE_DEC); /* Required function calls to register the header fields and subtrees used */ proto_register_field_array(proto_mbtcp, mbtcp_hf, array_length(mbtcp_hf)); proto_register_field_array(proto_mbrtu, mbrtu_hf, array_length(mbrtu_hf)); proto_register_field_array(proto_modbus, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); expert_mbtcp = expert_register_protocol(proto_mbtcp); expert_register_field_array(expert_mbtcp, mbtcp_ei, array_length(mbtcp_ei)); expert_mbrtu = expert_register_protocol(proto_mbrtu); expert_register_field_array(expert_mbrtu, mbrtu_ei, array_length(mbrtu_ei)); expert_modbus = expert_register_protocol(proto_modbus); expert_register_field_array(expert_modbus, ei, array_length(ei)); /* Register required preferences for Modbus Protocol variants */ mbtcp_module = prefs_register_protocol(proto_mbtcp, apply_mbtcp_prefs); mbrtu_module = prefs_register_protocol(proto_mbrtu, apply_mbrtu_prefs); modbus_module = prefs_register_protocol(proto_modbus, NULL); /* Modbus RTU Preference - Desegment, defaults to true for TCP desegmentation */ prefs_register_bool_preference(mbtcp_module, "desegment", "Desegment all Modbus RTU packets spanning multiple TCP segments", "Whether the Modbus RTU dissector should desegment all messages spanning multiple TCP segments", &mbtcp_desegment); /* Modbus RTU Preference - Desegment, defaults to true for TCP desegmentation */ prefs_register_bool_preference(mbrtu_module, "desegment", "Desegment all Modbus RTU packets spanning multiple TCP segments", "Whether the Modbus RTU dissector should desegment all messages spanning multiple TCP segments", &mbrtu_desegment); /* Modbus RTU Preference - CRC verification, defaults to false (no verification)*/ prefs_register_bool_preference(mbrtu_module, "crc_verification", "Validate CRC", "Whether to validate the CRC", &mbrtu_crc); /* Modbus Preference - Holding/Input Register format, this allows for deeper dissection of response data */ prefs_register_enum_preference(modbus_module, "mbus_register_format", "Holding/Input Register Format", "Register Format", &global_mbus_register_format, mbus_register_format, false); /* Obsolete Preferences */ prefs_register_obsolete_preference(mbtcp_module, "mbus_register_addr_type"); prefs_register_obsolete_preference(mbtcp_module, "mbus_register_format"); prefs_register_obsolete_preference(mbrtu_module, "mbus_register_addr_type"); prefs_register_obsolete_preference(mbrtu_module, "mbus_register_format"); } /* If this dissector uses sub-dissector registration add a registration routine. This format is required because a script is used to find these routines and create the code that calls these routines. */ void proto_reg_handoff_mbtcp(void) { dissector_add_uint_with_preference("tcp.port", PORT_MBTCP, mbtcp_handle); dissector_add_uint_with_preference("udp.port", PORT_MBTCP, mbudp_handle); dissector_add_uint_with_preference("tls.port", PORT_MBTLS, mbtls_handle); apply_mbtcp_prefs(); dissector_add_uint("mbtcp.prot_id", MODBUS_PROTOCOL_ID, modbus_handle); ssl_dissector_add(PORT_MBTLS, mbtls_handle); } void proto_reg_handoff_mbrtu(void) { dissector_handle_t mbrtu_udp_handle = create_dissector_handle(dissect_mbrtu_udp, proto_mbrtu); /* Make sure to use Modbus RTU Preferences field to determine default TCP port */ dissector_add_for_decode_as_with_preference("udp.port", mbrtu_udp_handle); dissector_add_for_decode_as_with_preference("tcp.port", mbrtu_handle); apply_mbrtu_prefs(); dissector_add_uint("mbtcp.prot_id", MODBUS_PROTOCOL_ID, modbus_handle); dissector_add_for_decode_as("rtacser.data", mbrtu_handle); dissector_add_for_decode_as("usb.device", mbrtu_handle); dissector_add_for_decode_as("usb.product", mbrtu_handle); dissector_add_for_decode_as("usb.protocol", mbrtu_handle); } /* * Editor modelines * * Local Variables: * c-basic-offset: 4 * tab-width: 8 * indent-tabs-mode: nil * End: * * ex: set shiftwidth=4 tabstop=8 expandtab: * :indentSize=4:tabSize=8:noTabs=true: */