2018-01-23 02:33:14 +00:00
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/* packet-caneth.c
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* Routines for Controller Area Network over Ethernet dissection
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* Copyright 2018, Lazar Sumar <bugzilla@lazar.co.nz>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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2018-02-07 11:26:45 +00:00
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* SPDX-License-Identifier: GPL-2.0-or-later
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2018-01-23 02:33:14 +00:00
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*/
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/*
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* The CAN-ETH protocol is used for transmitting the Controller Area Network
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* (CAN) protocol over UDP.
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*
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* The protocol definition can be found at http://www.proconx.com/assets/files/products/caneth/canframe.pdf
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*/
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#include <config.h>
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#include <epan/packet.h>
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#include <epan/dissectors/packet-udp.h>
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#include <epan/dissectors/packet-socketcan.h>
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#define CAN_FRAME_LEN 15
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#define CAN_DATA_OFFSET 5
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static const gchar magic[] = "ISO11898";
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void proto_reg_handoff_caneth(void);
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void proto_register_caneth(void);
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static int proto_caneth = -1;
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static int hf_caneth_magic = -1;
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static int hf_caneth_version = -1;
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static int hf_caneth_frames = -1;
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static int hf_caneth_options = -1;
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static int hf_caneth_can_ident_ext = -1;
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static int hf_caneth_can_ident_std = -1;
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static int hf_caneth_can_extflag = -1;
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static int hf_caneth_can_rtrflag = -1;
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static int hf_caneth_can_len = -1;
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static int hf_caneth_can_padding = -1;
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#define CANETH_UDP_PORT 11898
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static gint ett_caneth = -1;
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static gint ett_caneth_frames = -1;
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static gint ett_caneth_can = -1;
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static int proto_can = -1; // use CAN protocol for consistent filtering
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static dissector_table_t can_subdissector_table;
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/* A sample #define of the minimum length (in bytes) of the protocol data.
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* If data is received with fewer than this many bytes it is rejected by
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* the current dissector. */
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#define CANETH_MIN_LENGTH 10
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static gboolean
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test_caneth(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
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{
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/* Check that we have enough length for the Magic, Version, and Length */
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if (tvb_reported_length(tvb) < CANETH_MIN_LENGTH)
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return FALSE;
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/* Check that the magic id matches */
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if (tvb_strneql(tvb, offset, magic, 8) != 0)
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return FALSE;
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/* Check that the version is 1 as that is the only supported version */
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if (tvb_get_guint8(tvb, offset+8) != 1)
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return FALSE;
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/* Check that the version 1 limit of 16 can frames is respected */
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if (tvb_get_guint8(tvb, offset+9) > 16)
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return FALSE;
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return TRUE;
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}
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static guint
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get_caneth_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
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{
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return (guint) tvb_get_ntohs(tvb, offset+3);
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}
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static int
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dissect_caneth_can(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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proto_tree *can_tree;
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proto_item *ti;
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guint32 data_len;
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guint32 raw_can_id;
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gint8 ext_flag = 1;
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tvbuff_t* next_tvb;
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struct can_identifier can_id;
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ti = proto_tree_add_item(tree, proto_can, tvb, 0, -1, ENC_NA);
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can_tree = proto_item_add_subtree(ti, ett_caneth_can);
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ext_flag = tvb_get_guint8(tvb, 13);
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2018-02-01 16:17:04 +00:00
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proto_tree_add_item_ret_uint(can_tree, hf_caneth_can_ident_ext, tvb, 0, 4, ENC_LITTLE_ENDIAN, &raw_can_id);
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2018-01-23 02:33:14 +00:00
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if (ext_flag)
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{
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can_id.id = raw_can_id & CAN_EFF_MASK;
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}
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else
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{
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can_id.id = raw_can_id & CAN_SFF_MASK;
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}
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proto_tree_add_item_ret_uint(can_tree, hf_caneth_can_len, tvb, 4, 1, ENC_NA, &data_len);
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proto_tree_add_item(can_tree, hf_caneth_can_extflag, tvb, 13, 1, ENC_NA);
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proto_tree_add_item(can_tree, hf_caneth_can_rtrflag, tvb, 14, 1, ENC_NA);
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next_tvb = tvb_new_subset_length(tvb, CAN_DATA_OFFSET, data_len);
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if (!dissector_try_payload_new(can_subdissector_table, next_tvb, pinfo, tree, TRUE, &can_id))
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{
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call_data_dissector(next_tvb, pinfo, tree);
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}
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if (tvb_captured_length_remaining(tvb, CAN_DATA_OFFSET + data_len) > 0)
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{
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proto_tree_add_item(can_tree, hf_caneth_can_padding, tvb, CAN_DATA_OFFSET + data_len, -1, ENC_NA);
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}
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return tvb_captured_length(tvb);
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}
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static int
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dissect_caneth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
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{
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proto_tree *caneth_tree;
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proto_item *ti;
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guint32 frame_count, offset;
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tvbuff_t* next_tvb;
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if (!test_caneth(pinfo, tvb, 0, data))
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return 0;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "CAN-ETH");
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col_clear(pinfo->cinfo, COL_INFO);
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ti = proto_tree_add_item(tree, proto_caneth, tvb, 0, -1, ENC_NA);
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caneth_tree = proto_item_add_subtree(ti, ett_caneth);
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proto_tree_add_item(caneth_tree, hf_caneth_magic, tvb, 0, 8, ENC_ASCII|ENC_NA);
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proto_tree_add_item(caneth_tree, hf_caneth_version, tvb, 8, 1, ENC_NA);
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proto_tree_add_item_ret_uint(caneth_tree, hf_caneth_frames, tvb, 9, 1, ENC_NA, &frame_count);
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for (offset = 10; frame_count-- > 0; offset += CAN_FRAME_LEN)
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{
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next_tvb = tvb_new_subset_length(tvb, offset, CAN_FRAME_LEN);
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dissect_caneth_can(next_tvb, pinfo, tree, data);
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}
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if (tvb_captured_length_remaining(tvb, offset) > 0)
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{
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proto_tree_add_item(caneth_tree, hf_caneth_options, tvb, offset, -1, ENC_NA);
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}
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return tvb_captured_length(tvb);
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}
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static gboolean
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dissect_caneth_heur_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
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{
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return (udp_dissect_pdus(tvb, pinfo, tree, CANETH_MIN_LENGTH, test_caneth,
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get_caneth_len, dissect_caneth, data) != 0);
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}
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void
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proto_register_caneth(void)
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{
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static hf_register_info hf[] = {
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{
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&hf_caneth_magic,
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{
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"Magic", "caneth.magic",
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FT_STRING, STR_ASCII,
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NULL, 0x0,
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"The magic identifier used to denote the start of a CAN-ETH packet", HFILL
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}
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},
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{
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&hf_caneth_version,
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{
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"Version", "caneth.version",
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FT_UINT8, BASE_DEC,
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NULL, 0x0,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_frames,
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{
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"CAN Frames", "caneth.frames",
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FT_UINT8, BASE_DEC,
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NULL, 0x0,
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"Number of enclosed CAN frames", HFILL
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}
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},
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{
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&hf_caneth_options,
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{
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"Options (Reserved)", "caneth.options",
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FT_BYTES, BASE_NONE,
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NULL, 0x0,
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"Options field, reserved for future use, should be empty", HFILL
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}
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},
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{
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&hf_caneth_can_ident_ext,
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{
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"Identifier", "can.id",
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FT_UINT32, BASE_HEX,
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NULL, CAN_EFF_MASK,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_can_ident_std,
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{
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"Identifier", "can.id",
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FT_UINT32, BASE_HEX,
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NULL, CAN_SFF_MASK,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_can_extflag,
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{
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"Extended Flag", "can.flags.xtd",
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FT_BOOLEAN, BASE_NONE,
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NULL, 0,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_can_rtrflag,
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{
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"Remote Transmission Request Flag", "can.flags.rtr",
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FT_BOOLEAN, BASE_NONE,
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NULL, 0,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_can_len,
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{
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"Frame-Length", "can.len",
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FT_UINT8, BASE_DEC,
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NULL, 0x0,
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NULL, HFILL
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}
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},
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{
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&hf_caneth_can_padding,
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{
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"Padding", "caneth.can.padding",
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FT_BYTES, BASE_NONE,
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NULL, 0x0,
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NULL, HFILL
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}
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},
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};
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static gint *ett[] = {
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&ett_caneth,
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&ett_caneth_frames,
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&ett_caneth_can,
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};
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proto_caneth = proto_register_protocol("Controller Area Network over Ethernet", "CAN-ETH", "caneth");
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proto_register_field_array(proto_caneth, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_caneth(void)
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{
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dissector_handle_t caneth_handle = create_dissector_handle(dissect_caneth, proto_caneth);
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dissector_add_uint_with_preference("udp.port", CANETH_UDP_PORT, caneth_handle);
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heur_dissector_add("udp", dissect_caneth_heur_udp, "CAN-ETH over UDP", "caneth_udp", proto_caneth, HEURISTIC_ENABLE);
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can_subdissector_table = find_dissector_table("can.subdissector");
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proto_can = proto_get_id_by_filter_name("can");
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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