2 * Routines for LAPD frame disassembly
3 * Gilbert Ramirez <gram@xiexie.org>
5 * $Id: packet-lapd.c,v 1.18 2001/01/03 06:55:29 guy Exp $
7 * Ethereal - Network traffic analyzer
8 * By Gerald Combs <gerald@zing.org>
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
31 #ifdef HAVE_SYS_TYPES_H
32 # include <sys/types.h>
39 #include "packet-q931.h"
42 /* ISDN/LAPD references:
44 * http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm
45 * http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html
46 * http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm
49 static int proto_lapd = -1;
50 static int hf_lapd_address = -1;
51 static int hf_lapd_sapi = -1;
52 static int hf_lapd_cr = -1;
53 static int hf_lapd_ea1 = -1;
54 static int hf_lapd_tei = -1;
55 static int hf_lapd_ea2 = -1;
56 static int hf_lapd_control = -1;
58 static gint ett_lapd = -1;
59 static gint ett_lapd_address = -1;
60 static gint ett_lapd_control = -1;
63 * Bits in the address field.
65 #define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */
66 #define LAPD_SAPI_SHIFT 10
67 #define LAPD_CR 0x0200 /* Command/Response bit */
68 #define LAPD_EA1 0x0100 /* First Address Extension bit */
69 #define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */
70 #define LAPD_EA2 0x0001 /* Second Address Extension bit */
72 #define LAPD_SAPI_Q931 0 /* Q.931 call control procedure */
73 #define LAPD_SAPI_PM_Q931 1 /* Packet mode Q.931 call control procedure */
74 #define LAPD_SAPI_X25 16 /* X.25 Level 3 procedures */
75 #define LAPD_SAPI_L2 63 /* Layer 2 management procedures */
77 static const value_string lapd_sapi_vals[] = {
78 { LAPD_SAPI_Q931, "Q.931 Call control procedure" },
79 { LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" },
80 { LAPD_SAPI_X25, "X.25 Level 3 procedures" },
81 { LAPD_SAPI_L2, "Layer 2 management procedures" },
86 dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
88 proto_tree *lapd_tree, *addr_tree;
92 guint16 address, cr, sapi;
96 CHECK_DISPLAY_AS_DATA(proto_lapd, tvb, pinfo, tree);
98 pinfo->current_proto = "LAPD";
100 if (check_col(pinfo->fd, COL_PROTOCOL))
101 col_set_str(pinfo->fd, COL_PROTOCOL, "LAPD");
103 address = tvb_get_ntohs(tvb, 0);
104 cr = address & LAPD_CR;
105 sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT;
106 lapd_header_len = 2; /* address */
108 if (pinfo->pseudo_header->p2p.sent) {
109 is_response = cr ? TRUE : FALSE;
110 if(check_col(pinfo->fd, COL_RES_DL_DST))
111 col_set_str(pinfo->fd, COL_RES_DL_DST, "Network");
112 if(check_col(pinfo->fd, COL_RES_DL_SRC))
113 col_set_str(pinfo->fd, COL_RES_DL_SRC, "User");
116 is_response = cr ? FALSE : TRUE;
117 if(check_col(pinfo->fd, COL_RES_DL_DST))
118 col_set_str(pinfo->fd, COL_RES_DL_DST, "User");
119 if(check_col(pinfo->fd, COL_RES_DL_SRC))
120 col_set_str(pinfo->fd, COL_RES_DL_SRC, "Network");
125 ti = proto_tree_add_item(tree, proto_lapd, tvb, 0, 3, FALSE);
126 lapd_tree = proto_item_add_subtree(ti, ett_lapd);
128 ti = proto_tree_add_uint(lapd_tree, hf_lapd_address, tvb, 0, 2, address);
129 addr_tree = proto_item_add_subtree(ti, ett_lapd_address);
131 proto_tree_add_uint(addr_tree, hf_lapd_sapi,tvb, 0, 1, address);
132 proto_tree_add_uint(addr_tree, hf_lapd_cr, tvb, 0, 1, address);
133 proto_tree_add_uint(addr_tree, hf_lapd_ea1, tvb, 0, 1, address);
134 proto_tree_add_uint(addr_tree, hf_lapd_tei, tvb, 1, 1, address);
135 proto_tree_add_uint(addr_tree, hf_lapd_ea2, tvb, 1, 1, address);
141 control = dissect_xdlc_control(tvb, 2, pinfo, lapd_tree, hf_lapd_control,
142 ett_lapd_control, is_response, TRUE);
143 lapd_header_len += XDLC_CONTROL_LEN(control, TRUE);
145 next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1);
146 if (XDLC_IS_INFORMATION(control)) {
147 /* call next protocol */
151 dissect_q931(next_tvb, pinfo, tree);
155 dissect_data(next_tvb, 0, pinfo, tree);
159 dissect_data(next_tvb, 0, pinfo, tree);
163 proto_register_lapd(void)
165 static hf_register_info hf[] = {
167 { "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0,
171 { "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals), LAPD_SAPI,
172 "Service Access Point Identifier" }},
175 { "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR,
176 "Command/Response bit" }},
179 { "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1,
180 "First Address Extension bit" }},
183 { "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI,
184 "Terminal Endpoint Identifier" }},
187 { "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2,
188 "Second Address Extension bit" }},
191 { "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0,
194 static gint *ett[] = {
200 proto_lapd = proto_register_protocol("Link Access Procedure, Channel D (LAPD)",
202 proto_register_field_array (proto_lapd, hf, array_length(hf));
203 proto_register_subtree_array(ett, array_length(ett));
207 proto_reg_handoff_lapd(void)
209 dissector_add("wtap_encap", WTAP_ENCAP_LAPD, dissect_lapd);