forked from osmocom/wireshark
71a57dc85b
Assuming that it could, if registered as an "eth.trailer" heuristic dissector, get the length of the entire frame, that is. Change-Id: I1ac26feeb10bb8ba357089a80f4b768f580bb51d Reviewed-on: https://code.wireshark.org/review/16121 Reviewed-by: Guy Harris <guy@alum.mit.edu>
299 lines
10 KiB
C
299 lines
10 KiB
C
/* packet-prp.c
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* Routines for PRP (Parallel Redundancy Protocol; IEC62439 Part 3) dissection
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* Copyright 2007, Sven Meier <msv[AT]zhwin.ch>
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* Copyright 2011, Martin Renold <reld[AT]zhaw.ch>
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* Copyright 2011, Florian Reichert <refl [AT] zhaw.ch>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald[AT]wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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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/etypes.h>
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#include <epan/prefs.h>
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#define PRP_LAN_A 10
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#define PRP_LAN_B 11
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static const value_string prp_lan_vals[] = {
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{PRP_LAN_A, "LAN A"},
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{PRP_LAN_B, "LAN B"},
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{0, NULL}
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};
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/**********************************************************/
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/* Initialize the protocol and registered fields */
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/**********************************************************/
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void proto_register_prp(void);
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void proto_reg_handoff_prp(void);
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static int proto_prp = -1;
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/* Initialize trailer fields */
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static int hf_prp_redundancy_control_trailer_sequence_nr = -1;
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static int hf_prp_redundancy_control_trailer_lan = -1;
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static int hf_prp_redundancy_control_trailer_size = -1;
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static int hf_prp_redundancy_control_trailer_suffix = -1;
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static int hf_prp_redundancy_control_trailer_version = -1;
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/* Initialize the subtree pointers */
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static gint ett_prp_redundancy_control_trailer = -1;
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/* Post dissectors (such as the trailer dissector for this protocol)
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* get called for every single frame anyone loads into Wireshark.
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* Since this protocol is not of general interest we disable this
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* protocol by default.
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*
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* This is done separately from the disabled protocols list mainly so
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* we can disable it by default. XXX Maybe there's a better way.
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*/
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static gboolean prp_enable_dissector = FALSE;
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/* Code to actually dissect the packets */
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static int
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dissect_prp_redundancy_control_trailer(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, void* data _U_)
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{
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proto_item *ti;
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proto_tree *prp_tree;
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guint i;
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guint length;
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guint offset;
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guint16 lan_id;
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guint16 lsdu_size;
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guint16 prp1_suffix;
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guint trailer_start;
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guint trailer_length;
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trailer_start = 0;
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trailer_length = 0;
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length = tvb_reported_length(tvb);
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if(length < 14)
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return 0;
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/*
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* This is horribly broken. It assumes the frame is an Ethernet
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* frame, with a type field at an offset of 12 bytes from the header.
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* That is not guaranteed to be true.
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*
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* Ideally, this should be a heuristic dissector registered in
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* the "eth.trailer" heuristic dissector table (and it can
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* be registered as "disabled by default" there); unfortunately,
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* it needs to know the length of the entire frame for the
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* PRP-0 heuristic, so it'd have to be passed that length
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* out of band.
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*/
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if (!tvb_bytes_exist(tvb, 12, 2))
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return 0;
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if(ETHERTYPE_VLAN == tvb_get_ntohs(tvb, 12)) /* tagged frame */
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{
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offset = 18;
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}
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else /* untagged */
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{
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offset = 14;
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}
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if (!tree)
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return tvb_captured_length(tvb);
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/*
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* Is there enough data in the packet to every try to search for a
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* trailer?
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*/
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if (!tvb_bytes_exist(tvb, (length-4)+2, 2))
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return 0; /* no */
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/* search for PRP-0 trailer */
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/* If the frame is > 64 bytes, the PRP-0 trailer is always at the end. */
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/* If the frame is <= 64 bytes, the PRP-0 trailer may be anywhere (before the padding) */
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for(i=length-4; i>=offset; i--)
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{
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lan_id = tvb_get_ntohs(tvb, (i+2)) >> 12;
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lsdu_size = tvb_get_ntohs(tvb, (i+2)) & 0x0fff;
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if(lsdu_size == i+4-offset && (lan_id == 0xa || lan_id == 0xb))
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{
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trailer_start = i;
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trailer_length = 4;
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break;
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}
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if (length > 64) {
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break; /* don't search, just check the last position */
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}
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}
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/* check for PRP-1 trailer */
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/* PRP-1 trailer is always at the end of the frame, after any padding. */
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{
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lan_id = tvb_get_ntohs(tvb, length-4) >> 12;
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lsdu_size = tvb_get_ntohs(tvb, length-4) & 0x0fff;
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prp1_suffix = tvb_get_ntohs(tvb, length-2);
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if(prp1_suffix == ETHERTYPE_PRP && (lan_id == 0xa || lan_id == 0xb))
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{
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/* We don't check the lsdu_size, we just display whether
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it's correct. Helpful for testing, because different
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definitions of the lsdu_size did exist. */
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trailer_start = length-6;
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trailer_length = 6;
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}
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}
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if(trailer_length != 0)
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{
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/* create display subtree for the protocol */
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ti = proto_tree_add_item(tree, proto_prp, tvb, trailer_start,
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trailer_length, ENC_NA);
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prp_tree = proto_item_add_subtree(ti, ett_prp_redundancy_control_trailer);
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if (trailer_length == 4) {
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ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
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tvb, trailer_start, trailer_length, "PRP-0");
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} else {
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ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
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tvb, trailer_start, trailer_length, "PRP-1");
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}
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PROTO_ITEM_SET_GENERATED(ti);
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proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_sequence_nr,
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tvb, trailer_start, 2, ENC_BIG_ENDIAN);
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proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_lan,
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tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
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if (trailer_length == 4) {
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/* PRP-0 */
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proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_size,
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tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
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} else {
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/* PRP-1 */
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int lsdu_size_correct = length-offset;
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if (lsdu_size == lsdu_size_correct) {
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proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
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tvb, trailer_start+2, 2, lsdu_size,
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"LSDU size: %d [correct]", lsdu_size);
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} else {
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proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
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tvb, trailer_start+2, 2, lsdu_size,
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"LSDU size: %d [WRONG, should be %d]", lsdu_size, lsdu_size_correct);
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}
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/* suffix */
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proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_suffix,
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tvb, trailer_start+4, 2, ENC_BIG_ENDIAN);
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}
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}
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return tvb_captured_length(tvb);
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}
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/* Register the protocol with Wireshark */
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void proto_register_prp(void)
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{
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static hf_register_info hf[] = {
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/*trailer*/
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{ &hf_prp_redundancy_control_trailer_sequence_nr,
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{ "Sequence number", "prp.trailer.prp_sequence_nr",
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FT_UINT16, BASE_DEC, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_prp_redundancy_control_trailer_lan,
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{ "LAN", "prp.trailer.prp_lan",
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FT_UINT16, BASE_DEC, VALS(prp_lan_vals), 0xf000,
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NULL, HFILL }
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},
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{ &hf_prp_redundancy_control_trailer_size,
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{ "Size", "prp.trailer.prp_size",
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FT_UINT16, BASE_DEC, NULL, 0x0fff,
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NULL, HFILL }
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},
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{ &hf_prp_redundancy_control_trailer_suffix,
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{ "Suffix", "prp.trailer.prp1_suffix",
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FT_UINT16, BASE_HEX, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_prp_redundancy_control_trailer_version,
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{ "PRP Version", "prp.trailer.version",
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FT_STRING, BASE_NONE, NULL, 0x00,
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NULL, HFILL }
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}
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};
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static gint *ett[] = {
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&ett_prp_redundancy_control_trailer,
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};
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module_t *prp_module;
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/* Register the protocol name and description */
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proto_prp = proto_register_protocol("Parallel Redundancy Protocol (IEC62439 Part 3)",
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"PRP", "prp");
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prp_module = prefs_register_protocol(proto_prp, proto_reg_handoff_prp);
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prefs_register_bool_preference(prp_module, "enable", "Enable dissector",
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"Enable this dissector (default is false)",
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&prp_enable_dissector);
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/* Required function calls to register the header fields and subtree used */
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proto_register_field_array(proto_prp, 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 proto_reg_handoff_prp(void)
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{
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static gboolean prefs_initialized = FALSE;
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if (!prefs_initialized) {
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dissector_handle_t prp_redundancy_control_trailer_handle;
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prp_redundancy_control_trailer_handle = create_dissector_handle(dissect_prp_redundancy_control_trailer, proto_prp);
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register_postdissector(prp_redundancy_control_trailer_handle);
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prefs_initialized = TRUE;
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}
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if (!prp_enable_dissector)
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proto_disable_by_default(proto_prp);
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proto_set_decoding(proto_prp, prp_enable_dissector);
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}
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/*
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* Editor modelines - http://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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