2 * Routines for LAPD frame disassembly
3 * Gilbert Ramirez <gram@xiexie.org>
5 * $Id: packet-lapd.c,v 1.3 1999/11/16 11:42:37 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>
41 /* ISDN/LAPD references:
43 * http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm
44 * http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html
45 * http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm
48 static int proto_lapd = -1;
49 static int hf_lapd_address = -1;
50 static int hf_lapd_sapi = -1;
51 static int hf_lapd_cr = -1;
52 static int hf_lapd_ea1 = -1;
53 static int hf_lapd_tei = -1;
54 static int hf_lapd_ea2 = -1;
55 static int hf_lapd_control = -1;
57 static gint ett_lapd = -1;
58 static gint ett_lapd_address = -1;
59 static gint ett_lapd_control = -1;
62 * Bits in the address field.
64 #define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */
65 #define LAPD_SAPI_SHIFT 10
66 #define LAPD_CR 0x0200 /* Command/Response bit */
67 #define LAPD_EA1 0x0100 /* First Address Extension bit */
68 #define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */
69 #define LAPD_EA2 0x0001 /* Second Address Extension bit */
71 #define LAPD_SAPI_Q931 0 /* Q.931 call control procedure */
72 #define LAPD_SAPI_PM_Q931 1 /* Packet mode Q.931 call control procedure */
73 #define LAPD_SAPI_X25 16 /* X.25 Level 3 procedures */
74 #define LAPD_SAPI_L2 63 /* Layer 2 management procedures */
76 static const value_string lapd_sapi_vals[] = {
77 { LAPD_SAPI_Q931, "Q.931 Call control procedure" },
78 { LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" },
79 { LAPD_SAPI_X25, "X.25 Level 3 procedures" },
80 { LAPD_SAPI_L2, "Layer 2 management procedures" },
85 dissect_lapd(const u_char *pd, frame_data *fd, proto_tree *tree)
87 proto_tree *lapd_tree, *addr_tree;
92 guint16 address, cr, sapi;
96 if (check_col(fd, COL_PROTOCOL))
97 col_add_str(fd, COL_PROTOCOL, "LAPD");
99 address = pntohs(&pd[0]);
100 cr = address & LAPD_CR;
101 sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT;
102 lapd_header_len = 2; /* address */
104 if (fd->pseudo_header.lapd.from_network_to_user) {
105 is_response = cr ? FALSE : TRUE;
106 if(check_col(fd, COL_RES_DL_DST))
107 col_add_str(fd, COL_RES_DL_DST, "User");
108 if(check_col(fd, COL_RES_DL_SRC))
109 col_add_str(fd, COL_RES_DL_SRC, "Network");
112 is_response = cr ? TRUE : FALSE;
113 if(check_col(fd, COL_RES_DL_DST))
114 col_add_str(fd, COL_RES_DL_DST, "Network");
115 if(check_col(fd, COL_RES_DL_SRC))
116 col_add_str(fd, COL_RES_DL_SRC, "User");
121 ti = proto_tree_add_item(tree, proto_lapd, 0, 3, NULL);
122 lapd_tree = proto_item_add_subtree(ti, ett_lapd);
124 ti = proto_tree_add_item(lapd_tree, hf_lapd_address, 0, 2, address);
125 addr_tree = proto_item_add_subtree(ti, ett_lapd_address);
127 proto_tree_add_item(addr_tree, hf_lapd_sapi, 0, 1, address);
128 proto_tree_add_item(addr_tree, hf_lapd_cr, 0, 1, address);
129 proto_tree_add_item(addr_tree, hf_lapd_ea1, 0, 1, address);
130 proto_tree_add_item(addr_tree, hf_lapd_tei, 1, 1, address);
131 proto_tree_add_item(addr_tree, hf_lapd_ea2, 1, 1, address);
137 control = dissect_xdlc_control(pd, 2, fd, lapd_tree, hf_lapd_control,
138 ett_lapd_control, is_response, TRUE);
139 lapd_header_len += XDLC_CONTROL_LEN(control, TRUE);
141 if (XDLC_HAS_PAYLOAD(control)) {
142 /* call next protocol */
146 dissect_q931(pd, lapd_header_len, fd, tree);
150 dissect_data(pd, lapd_header_len, fd, tree);
157 proto_register_lapd(void)
159 static hf_register_info hf[] = {
161 { "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0,
165 { "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals), LAPD_SAPI,
166 "Service Access Point Identifier" }},
169 { "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR,
170 "Command/Response bit" }},
173 { "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1,
174 "First Address Extension bit" }},
177 { "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI,
178 "Terminal Endpoint Identifier" }},
181 { "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2,
182 "Second Address Extension bit" }},
185 { "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0,
188 static gint *ett[] = {
194 proto_lapd = proto_register_protocol ("Link Access Procedure, Channel D (LAPD)", "lapd");
195 proto_register_field_array (proto_lapd, hf, array_length(hf));
196 proto_register_subtree_array(ett, array_length(ett));