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/* packet-prp.c
* Routines for PRP (Parallel Redundancy Protocol; IEC62439 Part 3) dissection
* Copyright 2007, Sven Meier <msv[AT]zhwin.ch>
* Copyright 2011, Martin Renold <reld[AT]zhaw.ch>
* Copyright 2011, Florian Reichert <refl [AT] zhaw.ch>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald[AT]wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/etypes.h>
#include <epan/prefs.h>
#define PRP_LAN_A 10
#define PRP_LAN_B 11
static const value_string prp_lan_vals[] = {
{PRP_LAN_A, "LAN A"},
{PRP_LAN_B, "LAN B"},
{0, NULL}
};
/**********************************************************/
/* Initialize the protocol and registered fields */
/**********************************************************/
void proto_register_prp(void);
static int proto_prp;
/* Initialize trailer fields */
static int hf_prp_redundancy_control_trailer_sequence_nr;
static int hf_prp_redundancy_control_trailer_lan;
static int hf_prp_redundancy_control_trailer_size;
static int hf_prp_redundancy_control_trailer_suffix;
static int hf_prp_redundancy_control_trailer_version;
/* Initialize the subtree pointers */
static int ett_prp_redundancy_control_trailer;
/* Code to actually dissect the packets */
static int
dissect_prp_redundancy_control_trailer(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, void* data)
{
proto_item *ti;
proto_tree *prp_tree;
int i;
int length;
uint16_t lan_id;
uint16_t lsdu_size;
uint16_t prp1_suffix;
unsigned trailer_start;
unsigned trailer_length;
trailer_start = 0;
trailer_length = 0;
length = tvb_reported_length(tvb);
/*
* Is there enough data in the packet to every try to search for a
* trailer?
*/
if (!tvb_bytes_exist(tvb, (length-4)+2, 2))
return 0; /* no */
if (data == NULL) {
return 0;
}
int lsdu_size_correct = *(int*)data;
/* search for PRP-0 trailer */
/* If the frame is > 64 bytes, the PRP-0 trailer is always at the end. */
/* If the frame is <= 64 bytes, the PRP-0 trailer may be anywhere (before the padding) */
for(i = 0; i <= length - 4; i++)
{
lan_id = tvb_get_ntohs(tvb, length - 2 - i) >> 12;
lsdu_size = tvb_get_ntohs(tvb, length - 2 - i) & 0x0fff;
if(lsdu_size == (lsdu_size_correct - i) && (lan_id == 0xa || lan_id == 0xb))
{
trailer_start = length - 4 - i;
trailer_length = 4;
break;
}
}
/* check for PRP-1 trailer */
/* PRP-1 trailer is always at the end of the frame, after any padding. */
{
lan_id = tvb_get_ntohs(tvb, length-4) >> 12;
lsdu_size = tvb_get_ntohs(tvb, length-4) & 0x0fff;
prp1_suffix = tvb_get_ntohs(tvb, length-2);
if(prp1_suffix == ETHERTYPE_PRP && (lan_id == 0xa || lan_id == 0xb))
{
/* We don't check the lsdu_size, we just display whether
it's correct. Helpful for testing, because different
definitions of the lsdu_size did exist. */
trailer_start = length-6;
trailer_length = 6;
}
}
if(trailer_length != 0)
{
/* create display subtree for the protocol */
ti = proto_tree_add_item(tree, proto_prp, tvb, trailer_start,
trailer_length, ENC_NA);
prp_tree = proto_item_add_subtree(ti, ett_prp_redundancy_control_trailer);
if (trailer_length == 4) {
ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
tvb, trailer_start, trailer_length, "PRP-0");
} else {
ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
tvb, trailer_start, trailer_length, "PRP-1");
}
proto_item_set_generated(ti);
proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_sequence_nr,
tvb, trailer_start, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_lan,
tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
if (trailer_length == 4) {
/* PRP-0 */
proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_size,
tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
} else {
/* PRP-1 */
if (lsdu_size == lsdu_size_correct) {
proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
tvb, trailer_start+2, 2, lsdu_size,
"LSDU size: %d [correct]", lsdu_size);
} else {
proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
tvb, trailer_start+2, 2, lsdu_size,
"LSDU size: %d [WRONG, should be %d]", lsdu_size, lsdu_size_correct);
}
/* suffix */
proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_suffix,
tvb, trailer_start+4, 2, ENC_BIG_ENDIAN);
}
}
return trailer_length;
}
static bool dissect_prp_redundancy_control_trailer_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data)
{
return dissect_prp_redundancy_control_trailer(tvb, pinfo, parent_tree, data) > 0;
}
/* Register the protocol with Wireshark */
void proto_register_prp(void)
{
static hf_register_info hf[] = {
/*trailer*/
{ &hf_prp_redundancy_control_trailer_sequence_nr,
{ "Sequence number", "prp.trailer.prp_sequence_nr",
FT_UINT16, BASE_DEC, NULL, 0x00,
NULL, HFILL }
},
{ &hf_prp_redundancy_control_trailer_lan,
{ "LAN", "prp.trailer.prp_lan",
FT_UINT16, BASE_DEC, VALS(prp_lan_vals), 0xf000,
NULL, HFILL }
},
{ &hf_prp_redundancy_control_trailer_size,
{ "Size", "prp.trailer.prp_size",
FT_UINT16, BASE_DEC, NULL, 0x0fff,
NULL, HFILL }
},
{ &hf_prp_redundancy_control_trailer_suffix,
{ "Suffix", "prp.trailer.prp1_suffix",
FT_UINT16, BASE_HEX, NULL, 0x00,
NULL, HFILL }
},
{ &hf_prp_redundancy_control_trailer_version,
{ "PRP Version", "prp.trailer.version",
FT_STRING, BASE_NONE, NULL, 0x00,
NULL, HFILL }
}
};
static int *ett[] = {
&ett_prp_redundancy_control_trailer,
};
module_t *prp_module;
/* Register the protocol name and description */
proto_prp = proto_register_protocol("Parallel Redundancy Protocol (IEC62439 Part 3)", "PRP", "prp");
prp_module = prefs_register_protocol_obsolete(proto_prp);
prefs_register_obsolete_preference(prp_module, "enable");
/* Required function calls to register the header fields and subtree used */
proto_register_field_array(proto_prp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
heur_dissector_add("eth.trailer", dissect_prp_redundancy_control_trailer_heur,
"PRP Trailer", "prp_eth", proto_prp, HEURISTIC_ENABLE);
}
/*
* 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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