2 * Routines for lapb frame disassembly
3 * Olivier Abad <oabad@cybercable.fr>
5 * $Id: packet-lapb.c,v 1.31 2001/12/03 03:59:36 guy Exp $
7 * Ethereal - Network traffic analyzer
8 * By Gerald Combs <gerald@ethereal.com>
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version 2
14 * of the License, or (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
30 #ifdef HAVE_SYS_TYPES_H
31 # include <sys/types.h>
42 static int proto_lapb = -1;
43 static int hf_lapb_address = -1;
44 static int hf_lapb_control = -1;
46 static gint ett_lapb = -1;
47 static gint ett_lapb_control = -1;
49 static dissector_handle_t x25_handle;
52 dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
54 proto_tree *lapb_tree, *ti;
59 if (check_col(pinfo->fd, COL_PROTOCOL))
60 col_set_str(pinfo->fd, COL_PROTOCOL, "LAPB");
61 if (check_col(pinfo->fd, COL_INFO))
62 col_clear(pinfo->fd, COL_INFO);
64 if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
65 if(check_col(pinfo->fd, COL_RES_DL_DST))
66 col_set_str(pinfo->fd, COL_RES_DL_DST, "DTE");
67 if(check_col(pinfo->fd, COL_RES_DL_SRC))
68 col_set_str(pinfo->fd, COL_RES_DL_SRC, "DCE");
71 if(check_col(pinfo->fd, COL_RES_DL_DST))
72 col_set_str(pinfo->fd, COL_RES_DL_DST, "DCE");
73 if(check_col(pinfo->fd, COL_RES_DL_SRC))
74 col_set_str(pinfo->fd, COL_RES_DL_SRC, "DTE");
77 byte0 = tvb_get_guint8(tvb, 0);
79 if (byte0 != 0x01 && byte0 != 0x03) /* invalid LAPB frame */
81 if (check_col(pinfo->fd, COL_INFO))
82 col_set_str(pinfo->fd, COL_INFO, "Invalid LAPB frame");
84 ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0,
85 tvb_length(tvb), "Invalid LAPB frame");
89 if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x01) ||
90 (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x03))
96 ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0, 2,
98 lapb_tree = proto_item_add_subtree(ti, ett_lapb);
99 proto_tree_add_uint_format(lapb_tree, hf_lapb_address, tvb, 0, 1, byte0,
100 "Address: 0x%02X", byte0);
105 dissect_xdlc_control(tvb, 1, pinfo, lapb_tree, hf_lapb_control,
106 ett_lapb_control, is_response, FALSE);
108 /* not end of frame ==> X.25 */
109 if (tvb_length(tvb) > 2) {
110 next_tvb = tvb_new_subset(tvb, 2, -1, -1);
111 call_dissector(x25_handle, next_tvb, pinfo, tree);
116 proto_register_lapb(void)
118 static hf_register_info hf[] = {
120 { "Address Field", "lapb.address", FT_UINT8, BASE_HEX, NULL, 0x0,
124 { "Control Field", "lapb.control", FT_UINT8, BASE_HEX, NULL, 0x0,
125 "Control field", HFILL }},
127 static gint *ett[] = {
132 proto_lapb = proto_register_protocol("Link Access Procedure Balanced (LAPB)",
134 proto_register_field_array (proto_lapb, hf, array_length(hf));
135 proto_register_subtree_array(ett, array_length(ett));
137 register_dissector("lapb", dissect_lapb, proto_lapb);
141 proto_reg_handoff_lapb(void)
143 dissector_handle_t lapb_handle;
146 * Get a handle for the X.25 dissector.
148 x25_handle = find_dissector("x.25");
150 lapb_handle = find_dissector("lapb");
151 dissector_add("wtap_encap", WTAP_ENCAP_LAPB, lapb_handle);