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