/src/ndpi/src/lib/protocols/modbus.c
Line | Count | Source |
1 | | |
2 | | /* |
3 | | * modbus.c |
4 | | * |
5 | | * Copyright (C) 2018 - ntop.org |
6 | | * |
7 | | * This file is part of nDPI, an open source deep packet inspection |
8 | | * library based on the OpenDPI and PACE technology by ipoque GmbH |
9 | | * |
10 | | * nDPI is free software: you can redistribute it and/or modify |
11 | | * it under the terms of the GNU Lesser General Public License as published by |
12 | | * the Free Software Foundation, either version 3 of the License, or |
13 | | * (at your option) any later version. |
14 | | * |
15 | | * nDPI is distributed in the hope that it will be useful, |
16 | | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
18 | | * GNU Lesser General Public License for more details. |
19 | | * |
20 | | * You should have received a copy of the GNU Lesser General Public License |
21 | | * along with nDPI. If not, see <http://www.gnu.org/licenses/>. |
22 | | * |
23 | | */ |
24 | | |
25 | | |
26 | | #include "ndpi_protocol_ids.h" |
27 | | #define NDPI_CURRENT_PROTO NDPI_PROTOCOL_MODBUS |
28 | | #include "ndpi_api.h" |
29 | | #include "ndpi_private.h" |
30 | | |
31 | | static void ndpi_search_modbus_tcp(struct ndpi_detection_module_struct *ndpi_struct, |
32 | 2.24M | struct ndpi_flow_struct *flow) { |
33 | 2.24M | struct ndpi_packet_struct *packet = &ndpi_struct->packet; |
34 | 2.24M | NDPI_LOG_DBG(ndpi_struct, "search Modbus\n"); |
35 | 2.24M | u_int16_t modbus_port = htons(502); // port used by modbus |
36 | | |
37 | | /* Check connection over TCP */ |
38 | | |
39 | 2.24M | if(packet->tcp) { |
40 | | /* The payload of Modbus-TCP segment must be at least 8 bytes (7 bytes of header application |
41 | | packet plus 1 byte of minimum payload of application packet) |
42 | | */ |
43 | 2.24M | if((packet->payload_packet_len >= 8) |
44 | 1.62M | &&((packet->tcp->dest == modbus_port) || (packet->tcp->source == modbus_port))) { |
45 | | // Modbus uses the port 502 |
46 | 1.48k | u_int16_t modbus_len = htons(*((u_int16_t*)&packet->payload[4])); |
47 | | |
48 | | // the fourth parameter of the payload is the length of the segment |
49 | 1.48k | if(((modbus_len-1) == (packet->payload_packet_len - 7 /* ModbusTCP header len */)) |
50 | 552 | && (packet->payload[2] == 0x0) && (packet->payload[3] == 0x0) /* Protocol identifier */) { |
51 | | /* Check Modbus function code. 0x5A (90) is reserved for UMAS protocol */ |
52 | 390 | if (packet->payload[7] == 0x5A) { |
53 | 138 | NDPI_LOG_INFO(ndpi_struct, "found Schneider Electric UMAS\n"); |
54 | 138 | ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_UMAS, NDPI_PROTOCOL_MODBUS, NDPI_CONFIDENCE_DPI); |
55 | 138 | return; |
56 | 138 | } |
57 | | |
58 | 252 | NDPI_LOG_INFO(ndpi_struct, "found MODBUS\n"); |
59 | 252 | ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_MODBUS, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI); |
60 | 252 | return; |
61 | 390 | } |
62 | 1.48k | } |
63 | 2.24M | } |
64 | 2.24M | NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow); |
65 | | |
66 | 2.24M | } |
67 | | |
68 | | |
69 | | |
70 | 7.96k | void init_modbus_dissector(struct ndpi_detection_module_struct *ndpi_struct) { |
71 | | |
72 | 7.96k | register_dissector("Modbus", ndpi_struct, |
73 | 7.96k | ndpi_search_modbus_tcp, |
74 | 7.96k | NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION, |
75 | 7.96k | 1, NDPI_PROTOCOL_MODBUS); |
76 | 7.96k | } |