forked from osmocom/wireshark
214 lines
6.3 KiB
C
214 lines
6.3 KiB
C
/* packet-lapd.c
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* Routines for LAPD frame disassembly
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* Gilbert Ramirez <gram@alumni.rice.edu>
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*
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* $Id: packet-lapd.c,v 1.24 2001/11/13 23:55:30 gram Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998
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*
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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., 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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#ifdef HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#include <stdio.h>
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#include <glib.h>
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#include <string.h>
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#include "packet.h"
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#include "xdlc.h"
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/* ISDN/LAPD references:
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*
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* http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm
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* http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html
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* http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm
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*/
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static int proto_lapd = -1;
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static int hf_lapd_address = -1;
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static int hf_lapd_sapi = -1;
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static int hf_lapd_cr = -1;
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static int hf_lapd_ea1 = -1;
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static int hf_lapd_tei = -1;
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static int hf_lapd_ea2 = -1;
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static int hf_lapd_control = -1;
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static gint ett_lapd = -1;
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static gint ett_lapd_address = -1;
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static gint ett_lapd_control = -1;
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static dissector_handle_t q931_handle;
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/*
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* Bits in the address field.
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*/
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#define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */
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#define LAPD_SAPI_SHIFT 10
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#define LAPD_CR 0x0200 /* Command/Response bit */
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#define LAPD_EA1 0x0100 /* First Address Extension bit */
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#define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */
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#define LAPD_EA2 0x0001 /* Second Address Extension bit */
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#define LAPD_SAPI_Q931 0 /* Q.931 call control procedure */
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#define LAPD_SAPI_PM_Q931 1 /* Packet mode Q.931 call control procedure */
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#define LAPD_SAPI_X25 16 /* X.25 Level 3 procedures */
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#define LAPD_SAPI_L2 63 /* Layer 2 management procedures */
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static const value_string lapd_sapi_vals[] = {
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{ LAPD_SAPI_Q931, "Q.931 Call control procedure" },
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{ LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" },
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{ LAPD_SAPI_X25, "X.25 Level 3 procedures" },
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{ LAPD_SAPI_L2, "Layer 2 management procedures" },
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{ 0, NULL }
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};
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static void
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dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_tree *lapd_tree, *addr_tree;
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proto_item *ti;
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guint16 control;
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int lapd_header_len;
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guint16 address, cr, sapi;
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gboolean is_response;
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tvbuff_t *next_tvb;
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if (check_col(pinfo->fd, COL_PROTOCOL))
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col_set_str(pinfo->fd, COL_PROTOCOL, "LAPD");
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if (check_col(pinfo->fd, COL_INFO))
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col_clear(pinfo->fd, COL_INFO);
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address = tvb_get_ntohs(tvb, 0);
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cr = address & LAPD_CR;
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sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT;
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lapd_header_len = 2; /* address */
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if (pinfo->pseudo_header->p2p.sent) {
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is_response = cr ? TRUE : FALSE;
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if(check_col(pinfo->fd, COL_RES_DL_DST))
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col_set_str(pinfo->fd, COL_RES_DL_DST, "Network");
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if(check_col(pinfo->fd, COL_RES_DL_SRC))
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col_set_str(pinfo->fd, COL_RES_DL_SRC, "User");
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}
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else {
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is_response = cr ? FALSE : TRUE;
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if(check_col(pinfo->fd, COL_RES_DL_DST))
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col_set_str(pinfo->fd, COL_RES_DL_DST, "User");
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if(check_col(pinfo->fd, COL_RES_DL_SRC))
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col_set_str(pinfo->fd, COL_RES_DL_SRC, "Network");
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}
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if (tree) {
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ti = proto_tree_add_item(tree, proto_lapd, tvb, 0, 3, FALSE);
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lapd_tree = proto_item_add_subtree(ti, ett_lapd);
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ti = proto_tree_add_uint(lapd_tree, hf_lapd_address, tvb, 0, 2, address);
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addr_tree = proto_item_add_subtree(ti, ett_lapd_address);
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proto_tree_add_uint(addr_tree, hf_lapd_sapi,tvb, 0, 1, address);
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proto_tree_add_uint(addr_tree, hf_lapd_cr, tvb, 0, 1, address);
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proto_tree_add_uint(addr_tree, hf_lapd_ea1, tvb, 0, 1, address);
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proto_tree_add_uint(addr_tree, hf_lapd_tei, tvb, 1, 1, address);
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proto_tree_add_uint(addr_tree, hf_lapd_ea2, tvb, 1, 1, address);
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}
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else {
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lapd_tree = NULL;
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}
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control = dissect_xdlc_control(tvb, 2, pinfo, lapd_tree, hf_lapd_control,
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ett_lapd_control, is_response, TRUE);
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lapd_header_len += XDLC_CONTROL_LEN(control, TRUE);
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next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1);
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if (XDLC_IS_INFORMATION(control)) {
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/* call next protocol */
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switch (sapi) {
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case LAPD_SAPI_Q931:
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call_dissector(q931_handle, next_tvb, pinfo, tree);
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break;
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default:
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dissect_data(next_tvb, 0, pinfo, tree);
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break;
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}
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} else
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dissect_data(next_tvb, 0, pinfo, tree);
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}
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void
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proto_register_lapd(void)
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{
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static hf_register_info hf[] = {
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{ &hf_lapd_address,
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{ "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0,
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"Address", HFILL }},
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{ &hf_lapd_sapi,
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{ "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals), LAPD_SAPI,
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"Service Access Point Identifier", HFILL }},
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{ &hf_lapd_cr,
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{ "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR,
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"Command/Response bit", HFILL }},
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{ &hf_lapd_ea1,
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{ "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1,
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"First Address Extension bit", HFILL }},
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{ &hf_lapd_tei,
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{ "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI,
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"Terminal Endpoint Identifier", HFILL }},
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{ &hf_lapd_ea2,
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{ "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2,
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"Second Address Extension bit", HFILL }},
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{ &hf_lapd_control,
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{ "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0,
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"Control field", HFILL }},
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};
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static gint *ett[] = {
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&ett_lapd,
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&ett_lapd_address,
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&ett_lapd_control,
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};
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proto_lapd = proto_register_protocol("Link Access Procedure, Channel D (LAPD)",
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"LAPD", "lapd");
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proto_register_field_array (proto_lapd, 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_lapd(void)
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{
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/*
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* Get handle for the Q.931 dissector.
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*/
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q931_handle = find_dissector("q931");
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dissector_add("wtap_encap", WTAP_ENCAP_LAPD, dissect_lapd, proto_lapd);
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}
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