epan/dissectors/packet-caneth.c

   1 /* packet-caneth.c
   2  * Routines for Controller Area Network over Ethernet dissection
   3  * Copyright 2018, Lazar Sumar <bugzilla@lazar.co.nz>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 /*
  13  * The CAN-ETH protocol is used for transmitting the Controller Area Network
  14  * (CAN) protocol over UDP.
  15  *
  16  * The protocol definition can be found at http://www.proconx.com/assets/files/products/caneth/canframe.pdf
  17  */
  18
  19 #include <config.h>
  20
  21 #include <epan/packet.h>
  22 #include "packet-udp.h"
  23 #include "packet-socketcan.h"
  24
  25 #define CAN_FRAME_LEN   15
  26
  27 #define CAN_ID_OFFSET       0
  28 #define CAN_DLC_OFFSET      4
  29 #define CAN_DATA_OFFSET     5
  30 #define CAN_EXT_FLAG_OFFSET 13
  31 #define CAN_RTR_FLAG_OFFSET 14
  32
  33 static const char magic[] = "ISO11898";
  34
  35 void proto_reg_handoff_caneth(void);
  36 void proto_register_caneth(void);
  37
  38 static dissector_handle_t caneth_handle;
  39
  40 static int proto_caneth;
  41 static int hf_caneth_magic;
  42 static int hf_caneth_version;
  43 static int hf_caneth_frames;
  44 static int hf_caneth_options;
  45
  46 static int hf_caneth_can_ident_ext;
  47 static int hf_caneth_can_ident_std;
  48 static int hf_caneth_can_extflag;
  49 static int hf_caneth_can_rtrflag;
  50 static int hf_caneth_can_len;
  51 static int hf_caneth_can_padding;
  52
  53 #define CANETH_UDP_PORT 11898
  54
  55 static int ett_caneth;
  56 static int ett_caneth_frames;
  57 static int ett_caneth_can;
  58
  59 static int proto_can;      // use CAN protocol for consistent filtering
  60
  61 /* A sample #define of the minimum length (in bytes) of the protocol data.
  62  * If data is received with fewer than this many bytes it is rejected by
  63  * the current dissector. */
  64 #define CANETH_MIN_LENGTH 10
  65
  66 static bool
  67 test_caneth(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
  68 {
  69     /* Check that we have enough length for the Magic, Version, and Length */
  70     if (tvb_reported_length(tvb) < CANETH_MIN_LENGTH)
  71         return false;
  72     /* Check that the magic id matches */
  73     if (tvb_strneql(tvb, offset, magic, 8) != 0)
  74         return false;
  75     /* Check that the version is 1 as that is the only supported version */
  76     if (tvb_get_uint8(tvb, offset+8) != 1)
  77         return false;
  78     /* Check that the version 1 limit of 16 can frames is respected */
  79     if (tvb_get_uint8(tvb, offset+9) > 16)
  80         return false;
  81     return true;
  82 }
  83
  84 static unsigned
  85 get_caneth_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
  86 {
  87     return (unsigned) tvb_get_ntohs(tvb, offset+3);
  88 }
  89
  90 static int
  91 dissect_caneth_can(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  92 {
  93     proto_tree *can_tree;
  94     proto_item *ti;
  95     uint32_t    raw_can_id;
  96     int8_t      ext_flag;
  97     int8_t      rtr_flag;
  98     tvbuff_t*   next_tvb;
  99     struct can_info can_info;
 100
 101     ti = proto_tree_add_item(tree, proto_can, tvb, 0, -1, ENC_NA);
 102     can_tree = proto_item_add_subtree(ti, ett_caneth_can);
 103
 104     ext_flag = tvb_get_uint8(tvb, CAN_EXT_FLAG_OFFSET);
 105     rtr_flag = tvb_get_uint8(tvb, CAN_RTR_FLAG_OFFSET);
 106
 107     if (ext_flag)
 108     {
 109         proto_tree_add_item_ret_uint(can_tree, hf_caneth_can_ident_ext, tvb, CAN_ID_OFFSET, 4, ENC_LITTLE_ENDIAN, &raw_can_id);
 110         can_info.id = raw_can_id & CAN_EFF_MASK;
 111     }
 112     else
 113     {
 114         proto_tree_add_item_ret_uint(can_tree, hf_caneth_can_ident_std, tvb, CAN_ID_OFFSET, 4, ENC_LITTLE_ENDIAN, &raw_can_id);
 115         can_info.id = raw_can_id & CAN_SFF_MASK;
 116     }
 117
 118     can_info.id |= (ext_flag ? CAN_EFF_FLAG : 0) | (rtr_flag ? CAN_RTR_FLAG : 0);
 119     can_info.fd = CAN_TYPE_CAN_CLASSIC;
 120     can_info.bus_id = 0; /* see get_bus_id in packet-socketcan.c? */
 121
 122     proto_tree_add_item_ret_uint(can_tree, hf_caneth_can_len, tvb, CAN_DLC_OFFSET, 1, ENC_NA, &can_info.len);
 123     proto_tree_add_item(can_tree, hf_caneth_can_extflag, tvb, CAN_EXT_FLAG_OFFSET, 1, ENC_NA);
 124     proto_tree_add_item(can_tree, hf_caneth_can_rtrflag, tvb, CAN_RTR_FLAG_OFFSET, 1, ENC_NA);
 125
 126     next_tvb = tvb_new_subset_length(tvb, CAN_DATA_OFFSET, can_info.len);
 127
 128     if (!socketcan_call_subdissectors(next_tvb, pinfo, tree, &can_info, false)) {
 129         call_data_dissector(next_tvb, pinfo, tree);
 130     }
 131
 132     if (tvb_captured_length_remaining(tvb, CAN_DATA_OFFSET + can_info.len) > 0)
 133     {
 134         proto_tree_add_item(can_tree, hf_caneth_can_padding, tvb, CAN_DATA_OFFSET + can_info.len, -1, ENC_NA);
 135     }
 136     return tvb_captured_length(tvb);
 137 }
 138
 139 static int
 140 dissect_caneth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 141 {
 142     proto_tree *caneth_tree;
 143     proto_item *ti;
 144     uint32_t    frame_count, offset;
 145     tvbuff_t*   next_tvb;
 146
 147     if (!test_caneth(pinfo, tvb, 0, data))
 148         return 0;
 149
 150     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CAN-ETH");
 151     col_clear(pinfo->cinfo, COL_INFO);
 152
 153     ti = proto_tree_add_item(tree, proto_caneth, tvb, 0, -1, ENC_NA);
 154     caneth_tree = proto_item_add_subtree(ti, ett_caneth);
 155
 156     proto_tree_add_item(caneth_tree, hf_caneth_magic, tvb, 0, 8, ENC_ASCII);
 157     proto_tree_add_item(caneth_tree, hf_caneth_version, tvb, 8, 1, ENC_NA);
 158     proto_tree_add_item_ret_uint(caneth_tree, hf_caneth_frames, tvb, 9, 1, ENC_NA, &frame_count);
 159
 160     for (offset = 10; frame_count-- > 0; offset += CAN_FRAME_LEN)
 161     {
 162         next_tvb = tvb_new_subset_length(tvb, offset, CAN_FRAME_LEN);
 163         dissect_caneth_can(next_tvb, pinfo, tree, data);
 164     }
 165
 166     if (tvb_captured_length_remaining(tvb, offset) > 0)
 167     {
 168         proto_tree_add_item(caneth_tree, hf_caneth_options, tvb, offset, -1, ENC_NA);
 169     }
 170
 171     return tvb_captured_length(tvb);
 172 }
 173
 174 static bool
 175 dissect_caneth_heur_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 176 {
 177     return (udp_dissect_pdus(tvb, pinfo, tree, CANETH_MIN_LENGTH, test_caneth,
 178                      get_caneth_len, dissect_caneth, data) != 0);
 179 }
 180
 181 void
 182 proto_register_caneth(void)
 183 {
 184     static hf_register_info hf[] = {
 185         {
 186             &hf_caneth_magic,
 187             {
 188                 "Magic", "caneth.magic",
 189                 FT_STRING, BASE_NONE,
 190                 NULL, 0x0,
 191                 "The magic identifier used to denote the start of a CAN-ETH packet", HFILL
 192             }
 193         },
 194         {
 195             &hf_caneth_version,
 196             {
 197                 "Version", "caneth.version",
 198                 FT_UINT8, BASE_DEC,
 199                 NULL, 0x0,
 200                 NULL, HFILL
 201             }
 202         },
 203         {
 204             &hf_caneth_frames,
 205             {
 206                 "CAN Frames", "caneth.frames",
 207                 FT_UINT8, BASE_DEC,
 208                 NULL, 0x0,
 209                 "Number of enclosed CAN frames", HFILL
 210             }
 211         },
 212         {
 213             &hf_caneth_options,
 214             {
 215                 "Options (Reserved)", "caneth.options",
 216                 FT_BYTES, BASE_NONE,
 217                 NULL, 0x0,
 218                 "Options field, reserved for future use, should be empty", HFILL
 219             }
 220         },
 221         {
 222             &hf_caneth_can_ident_ext,
 223             {
 224                 "Identifier", "can.id",
 225                 FT_UINT32, BASE_HEX,
 226                 NULL, CAN_EFF_MASK,
 227                 NULL, HFILL
 228             }
 229         },
 230         {
 231             &hf_caneth_can_ident_std,
 232             {
 233                 "Identifier", "can.id",
 234                 FT_UINT32, BASE_HEX,
 235                 NULL, CAN_SFF_MASK,
 236                 NULL, HFILL
 237             }
 238         },
 239         {
 240             &hf_caneth_can_extflag,
 241             {
 242                 "Extended Flag", "can.flags.xtd",
 243                 FT_BOOLEAN, BASE_NONE,
 244                 NULL, 0,
 245                 NULL, HFILL
 246             }
 247         },
 248         {
 249             &hf_caneth_can_rtrflag,
 250             {
 251                 "Remote Transmission Request Flag", "can.flags.rtr",
 252                 FT_BOOLEAN, BASE_NONE,
 253                 NULL, 0,
 254                 NULL, HFILL
 255             }
 256         },
 257         {
 258             &hf_caneth_can_len,
 259             {
 260                 "Frame-Length", "can.len",
 261                 FT_UINT8, BASE_DEC,
 262                 NULL, 0x0,
 263                 NULL, HFILL
 264             }
 265         },
 266         {
 267             &hf_caneth_can_padding,
 268             {
 269                 "Padding", "caneth.can.padding",
 270                 FT_BYTES, BASE_NONE,
 271                 NULL, 0x0,
 272                 NULL, HFILL
 273             }
 274         },
 275     };
 276
 277     static int *ett[] = {
 278         &ett_caneth,
 279         &ett_caneth_frames,
 280         &ett_caneth_can,
 281     };
 282
 283     proto_caneth = proto_register_protocol("Controller Area Network over Ethernet", "CAN-ETH", "caneth");
 284
 285     proto_register_field_array(proto_caneth, hf, array_length(hf));
 286     proto_register_subtree_array(ett, array_length(ett));
 287
 288     caneth_handle = register_dissector("caneth", dissect_caneth, proto_caneth);
 289 }
 290
 291 void
 292 proto_reg_handoff_caneth(void)
 293 {
 294     dissector_add_uint_with_preference("udp.port", CANETH_UDP_PORT, caneth_handle);
 295
 296     heur_dissector_add("udp", dissect_caneth_heur_udp, "CAN-ETH over UDP", "caneth_udp", proto_caneth, HEURISTIC_ENABLE);
 297
 298     proto_can = proto_get_id_by_filter_name("can");
 299 }
 300
 301 /*
 302  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 303  *
 304  * Local variables:
 305  * c-basic-offset: 4
 306  * tab-width: 8
 307  * indent-tabs-mode: nil
 308  * End:
 309  *
 310  * vi: set shiftwidth=4 tabstop=8 expandtab:
 311  * :indentSize=4:tabSize=8:noTabs=true:
 312  */