2 * Routines for LAPD frame disassembly
3 * Gilbert Ramirez <gram@xiexie.org>
5 * $Id: packet-lapd.c,v 1.14 2000/09/21 04:41:07 gram 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-lapd.h"
40 #include "packet-q931.h"
43 /* ISDN/LAPD references:
45 * http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm
46 * http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html
47 * http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm
50 static int proto_lapd = -1;
51 static int hf_lapd_address = -1;
52 static int hf_lapd_sapi = -1;
53 static int hf_lapd_cr = -1;
54 static int hf_lapd_ea1 = -1;
55 static int hf_lapd_tei = -1;
56 static int hf_lapd_ea2 = -1;
57 static int hf_lapd_control = -1;
59 static gint ett_lapd = -1;
60 static gint ett_lapd_address = -1;
61 static gint ett_lapd_control = -1;
64 * Bits in the address field.
66 #define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */
67 #define LAPD_SAPI_SHIFT 10
68 #define LAPD_CR 0x0200 /* Command/Response bit */
69 #define LAPD_EA1 0x0100 /* First Address Extension bit */
70 #define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */
71 #define LAPD_EA2 0x0001 /* Second Address Extension bit */
73 #define LAPD_SAPI_Q931 0 /* Q.931 call control procedure */
74 #define LAPD_SAPI_PM_Q931 1 /* Packet mode Q.931 call control procedure */
75 #define LAPD_SAPI_X25 16 /* X.25 Level 3 procedures */
76 #define LAPD_SAPI_L2 63 /* Layer 2 management procedures */
78 static const value_string lapd_sapi_vals[] = {
79 { LAPD_SAPI_Q931, "Q.931 Call control procedure" },
80 { LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" },
81 { LAPD_SAPI_X25, "X.25 Level 3 procedures" },
82 { LAPD_SAPI_L2, "Layer 2 management procedures" },
87 dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
89 proto_tree *lapd_tree, *addr_tree;
93 guint16 address, cr, sapi;
97 CHECK_DISPLAY_AS_DATA(proto_lapd, tvb, pinfo, tree);
99 pinfo->current_proto = "LAPD";
101 if (check_col(pinfo->fd, COL_PROTOCOL))
102 col_add_str(pinfo->fd, COL_PROTOCOL, "LAPD");
104 address = tvb_get_ntohs(tvb, 0);
105 cr = address & LAPD_CR;
106 sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT;
107 lapd_header_len = 2; /* address */
109 if (pinfo->pseudo_header->p2p.sent) {
110 is_response = cr ? TRUE : FALSE;
111 if(check_col(pinfo->fd, COL_RES_DL_DST))
112 col_add_str(pinfo->fd, COL_RES_DL_DST, "Network");
113 if(check_col(pinfo->fd, COL_RES_DL_SRC))
114 col_add_str(pinfo->fd, COL_RES_DL_SRC, "User");
117 is_response = cr ? FALSE : TRUE;
118 if(check_col(pinfo->fd, COL_RES_DL_DST))
119 col_add_str(pinfo->fd, COL_RES_DL_DST, "User");
120 if(check_col(pinfo->fd, COL_RES_DL_SRC))
121 col_add_str(pinfo->fd, COL_RES_DL_SRC, "Network");
126 ti = proto_tree_add_item(tree, proto_lapd, tvb, 0, 3, FALSE);
127 lapd_tree = proto_item_add_subtree(ti, ett_lapd);
129 ti = proto_tree_add_uint(lapd_tree, hf_lapd_address, tvb, 0, 2, address);
130 addr_tree = proto_item_add_subtree(ti, ett_lapd_address);
132 proto_tree_add_uint(addr_tree, hf_lapd_sapi,tvb, 0, 1, address);
133 proto_tree_add_uint(addr_tree, hf_lapd_cr, tvb, 0, 1, address);
134 proto_tree_add_uint(addr_tree, hf_lapd_ea1, tvb, 0, 1, address);
135 proto_tree_add_uint(addr_tree, hf_lapd_tei, tvb, 1, 1, address);
136 proto_tree_add_uint(addr_tree, hf_lapd_ea2, tvb, 1, 1, address);
142 control = dissect_xdlc_control(tvb, 2, pinfo, lapd_tree, hf_lapd_control,
143 ett_lapd_control, is_response, TRUE);
144 lapd_header_len += XDLC_CONTROL_LEN(control, TRUE);
146 next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1);
147 if (XDLC_IS_INFORMATION(control)) {
148 /* call next protocol */
152 dissect_q931(next_tvb, pinfo, tree);
156 dissect_data(next_tvb, pinfo, tree);
160 dissect_data(next_tvb, pinfo, tree);
164 proto_register_lapd(void)
166 static hf_register_info hf[] = {
168 { "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0,
172 { "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals), LAPD_SAPI,
173 "Service Access Point Identifier" }},
176 { "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR,
177 "Command/Response bit" }},
180 { "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1,
181 "First Address Extension bit" }},
184 { "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI,
185 "Terminal Endpoint Identifier" }},
188 { "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2,
189 "Second Address Extension bit" }},
192 { "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0,
195 static gint *ett[] = {
201 proto_lapd = proto_register_protocol ("Link Access Procedure, Channel D (LAPD)", "lapd");
202 proto_register_field_array (proto_lapd, hf, array_length(hf));
203 proto_register_subtree_array(ett, array_length(ett));