236 lines
6.2 KiB
C
236 lines
6.2 KiB
C
/** Decode IrDA Serial Infrared (SIR) wrapped packets.
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* @author Shaun Jackman <sjackman@debian.org>
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* @copyright Copyright 2004 Shaun Jackman
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* @license GPL
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*
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* $Id$
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <epan/packet.h>
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#include <epan/crc16.h>
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/** Serial infrared port. */
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#define TCP_PORT_SIR 6417
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/** Beginning of frame. */
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#define SIR_BOF 0xc0
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/** End of frame. */
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#define SIR_EOF 0xc1
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/** Control escape. */
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#define SIR_CE 0x7d
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/** Escapes this character. */
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#define SIR_ESCAPE(x) ((x)^0x20)
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/** Protocol handles. */
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dissector_handle_t data_handle;
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dissector_handle_t irda_handle;
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/** Protocol fields. */
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static int proto_sir = -1;
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static int ett_sir = -1;
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static int hf_sir_bof = -1;
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static int hf_sir_ce = -1;
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static int hf_sir_eof = -1;
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static int hf_sir_fcs = -1;
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static int hf_sir_fcs_bad = -1;
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static int hf_sir_length = -1;
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static int hf_sir_preamble = -1;
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/** Unescapes the data. */
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static tvbuff_t *
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unescape_data(tvbuff_t *tvb, packet_info *pinfo)
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{
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if (tvb_find_guint8(tvb, 0, -1, SIR_CE) == -1) {
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return tvb;
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} else {
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guint length = tvb_length(tvb);
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guint offset;
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guint8 *data = g_malloc(length);
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guint8 *dst = data;
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tvbuff_t *next_tvb;
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for (offset = 0; offset < length; )
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{
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guint8 c = tvb_get_guint8(tvb, offset++);
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if ((c == SIR_CE) && (offset < length))
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c = SIR_ESCAPE(tvb_get_guint8(tvb, offset++));
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*dst++ = c;
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}
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next_tvb = tvb_new_real_data(data, dst-data, dst-data);
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tvb_set_free_cb(next_tvb, g_free);
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tvb_set_child_real_data_tvbuff(tvb, next_tvb);
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add_new_data_source(pinfo, next_tvb, "Unescaped SIR");
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return next_tvb;
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}
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}
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/** Checksums the data. */
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static tvbuff_t *
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checksum_data(tvbuff_t *tvb, proto_tree *tree)
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{
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int len = tvb_length(tvb) - 2;
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if (len < 0)
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return tvb;
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if (tree) {
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guint16 actual_fcs = tvb_get_letohs(tvb, len);
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guint16 calculated_fcs = crc16_ccitt_tvb(tvb, len);
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if (calculated_fcs == actual_fcs) {
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proto_tree_add_uint_format(tree, hf_sir_fcs,
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tvb, len, 2, actual_fcs,
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"Frame check sequence: 0x%04x (correct)",
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actual_fcs);
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} else {
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proto_tree_add_boolean_hidden(tree,
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hf_sir_fcs_bad, tvb, len, 2, TRUE);
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proto_tree_add_uint_format(tree, hf_sir_fcs,
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tvb, len, 2, actual_fcs,
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"Frame check sequence: 0x%04x "
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"(incorrect, should be 0x%04x)",
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actual_fcs, calculated_fcs);
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}
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}
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return tvb_new_subset(tvb, 0, len, len);
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}
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/** Dissects an SIR packet. */
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static void
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dissect_sir(tvbuff_t *tvb, packet_info *pinfo, proto_tree *root)
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{
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gint offset = 0;
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gint bof_offset;
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gint eof_offset;
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while (tvb_length_remaining(tvb, offset) > 0) {
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bof_offset = tvb_find_guint8(tvb, offset, -1, SIR_BOF);
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eof_offset = (bof_offset == -1) ? -1 :
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tvb_find_guint8(tvb, bof_offset, -1, SIR_EOF);
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if (bof_offset == -1 || eof_offset == -1) {
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if (pinfo->can_desegment) {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = 1;
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}
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return;
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} else {
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guint preamble_len = bof_offset - offset;
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gint data_offset = bof_offset + 1;
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guint data_len = eof_offset - data_offset;
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tvbuff_t* next_tvb = tvb_new_subset(tvb,
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data_offset, data_len, -1);
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next_tvb = unescape_data(next_tvb, pinfo);
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if (root) {
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unsigned data_len = tvb_length(next_tvb) < 2 ? 0 :
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tvb_length(next_tvb) - 2;
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proto_tree* ti = proto_tree_add_protocol_format(root,
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proto_sir, tvb, offset, eof_offset - offset + 1,
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"Serial Infrared, Len: %d", data_len);
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proto_tree* tree = proto_item_add_subtree(ti, ett_sir);
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if (preamble_len > 0)
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proto_tree_add_item(tree, hf_sir_preamble, tvb,
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offset, preamble_len, FALSE);
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proto_tree_add_item(tree, hf_sir_bof, tvb,
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bof_offset, 1, FALSE);
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proto_tree_add_uint(tree, hf_sir_length,
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next_tvb, 0, data_len, data_len);
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next_tvb = checksum_data(next_tvb, tree);
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proto_tree_add_item(tree, hf_sir_eof, tvb,
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eof_offset, 1, FALSE);
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} else {
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next_tvb = checksum_data(next_tvb, NULL);
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}
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call_dissector(irda_handle, next_tvb, pinfo, root);
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}
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offset = eof_offset + 1;
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}
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}
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/** Registers this dissector with the parent dissector. */
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void
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proto_reg_handoff_irsir(void)
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{
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dissector_add("tcp.port", TCP_PORT_SIR, find_dissector("sir"));
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data_handle = find_dissector("data");
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irda_handle = find_dissector("irda");
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if (irda_handle == 0)
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irda_handle = data_handle;
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}
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/** Initializes this protocol. */
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void
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proto_register_irsir(void)
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{
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static gint* ett[] = { &ett_sir };
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static hf_register_info hf_sir[] = {
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{ &hf_sir_bof,
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{ "Beginning of frame", "sir.bof",
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FT_UINT8, BASE_HEX, NULL, 0,
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"", HFILL }},
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{ &hf_sir_ce,
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{ "Command escape", "sir.ce",
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FT_UINT8, BASE_HEX, NULL, 0,
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"", HFILL }},
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{ &hf_sir_eof,
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{ "End of frame", "sir.eof",
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FT_UINT8, BASE_HEX, NULL, 0,
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"", HFILL }},
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{ &hf_sir_fcs,
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{ "Frame check sequence", "sir.fcs",
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FT_UINT16, BASE_HEX, NULL, 0,
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"", HFILL }},
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{ &hf_sir_fcs_bad,
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{ "Bad frame check sequence", "sir.fcs_bad",
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FT_BOOLEAN, BASE_NONE, NULL, 0,
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"", HFILL }},
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{ &hf_sir_length,
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{ "Length", "sir.length",
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FT_UINT16, BASE_DEC, NULL, 0,
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"", HFILL }},
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{ &hf_sir_preamble,
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{ "Preamble", "sir.preamble",
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FT_BYTES, BASE_NONE, NULL, 0,
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"", HFILL }}
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};
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proto_sir = proto_register_protocol(
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"Serial Infrared", "SIR", "sir");
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register_dissector("sir", dissect_sir, proto_sir);
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proto_register_subtree_array(ett, array_length(ett));
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proto_register_field_array(
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proto_sir, hf_sir, array_length(hf_sir));
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}
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