2 * Routines for lapb frame disassembly
3 * Olivier Abad <abad@daba.dhis.net>
5 * $Id: packet-lapb.c,v 1.19 2000/05/26 05:52:55 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-lapb.h"
40 #include "packet-x25.h"
45 static int proto_lapb = -1;
46 static int hf_lapb_address = -1;
47 static int hf_lapb_control = -1;
49 static gint ett_lapb = -1;
50 static gint ett_lapb_control = -1;
53 dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
55 proto_tree *lapb_tree, *ti;
58 const guint8 *this_pd;
62 pinfo->current_proto = "LAPB";
64 if (check_col(pinfo->fd, COL_PROTOCOL))
65 col_add_str(pinfo->fd, COL_PROTOCOL, "LAPB");
67 if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
68 if(check_col(pinfo->fd, COL_RES_DL_DST))
69 col_add_str(pinfo->fd, COL_RES_DL_DST, "DTE");
70 if(check_col(pinfo->fd, COL_RES_DL_SRC))
71 col_add_str(pinfo->fd, COL_RES_DL_SRC, "DCE");
74 if(check_col(pinfo->fd, COL_RES_DL_DST))
75 col_add_str(pinfo->fd, COL_RES_DL_DST, "DCE");
76 if(check_col(pinfo->fd, COL_RES_DL_SRC))
77 col_add_str(pinfo->fd, COL_RES_DL_SRC, "DTE");
80 byte0 = tvb_get_guint8(tvb, 0);
82 if (byte0 != 0x01 && byte0 != 0x03) /* invalid LAPB frame */
84 if (check_col(pinfo->fd, COL_INFO))
85 col_add_str(pinfo->fd, COL_INFO, "Invalid LAPB frame");
87 ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0,
88 tvb_length(tvb), "Invalid LAPB frame");
92 if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x01) ||
93 (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x03))
99 ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0, 2,
101 lapb_tree = proto_item_add_subtree(ti, ett_lapb);
102 proto_tree_add_uint_format(lapb_tree, hf_lapb_address, tvb, 0, 1, byte0,
103 "Address: 0x%02X", byte0);
108 tvb_compat(tvb, &this_pd, &this_offset);
109 dissect_xdlc_control(this_pd, this_offset+1, pinfo->fd, lapb_tree, hf_lapb_control,
110 ett_lapb_control, is_response, FALSE);
112 /* not end of frame ==> X.25 */
113 if (tvb_length(tvb) > 2) {
114 next_tvb = tvb_new_subset(tvb, 2, -1, -1);
115 dissect_x25(next_tvb, pinfo, tree);
120 proto_register_lapb(void)
122 static hf_register_info hf[] = {
124 { "Address Field", "lapb.address", FT_UINT8, BASE_HEX, NULL, 0x0,
128 { "Control Field", "lapb.control", FT_UINT8, BASE_HEX, NULL, 0x0,
131 static gint *ett[] = {
136 proto_lapb = proto_register_protocol ("Link Access Procedure Balanced (LAPB)", "lapb");
137 proto_register_field_array (proto_lapb, hf, array_length(hf));
138 proto_register_subtree_array(ett, array_length(ett));