2 * Routines for lapb frame disassembly
3 * Olivier Abad <oabad@noos.fr>
7 * Wireshark - Network traffic analyzer
8 * By Gerald Combs <gerald@wireshark.org>
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.
32 #include <epan/packet.h>
33 #include <epan/xdlc.h>
35 static int proto_lapb = -1;
36 static int hf_lapb_address = -1;
37 static int hf_lapb_control = -1;
38 static int hf_lapb_n_r = -1;
39 static int hf_lapb_n_s = -1;
40 static int hf_lapb_p = -1;
41 static int hf_lapb_f = -1;
42 static int hf_lapb_s_ftype = -1;
43 static int hf_lapb_u_modifier_cmd = -1;
44 static int hf_lapb_u_modifier_resp = -1;
45 static int hf_lapb_ftype_i = -1;
46 static int hf_lapb_ftype_s_u = -1;
48 static gint ett_lapb = -1;
49 static gint ett_lapb_control = -1;
51 static dissector_handle_t x25_dir_handle;
52 static dissector_handle_t x25_handle;
54 static const xdlc_cf_items lapb_cf_items = {
60 &hf_lapb_u_modifier_cmd,
61 &hf_lapb_u_modifier_resp,
67 dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
69 proto_tree *lapb_tree, *ti;
74 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPB");
75 col_clear(pinfo->cinfo, COL_INFO);
77 switch (pinfo->p2p_dir) {
80 col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
81 col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
85 col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
86 col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
90 col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "N/A");
91 col_set_str(pinfo->cinfo, COL_RES_DL_DST, "N/A");
95 byte0 = tvb_get_guint8(tvb, 0);
97 if (byte0 != 0x01 && byte0 != 0x03 && byte0 != 0x07 && byte0 != 0x0f) /* invalid LAPB frame */
99 col_set_str(pinfo->cinfo, COL_INFO, "Invalid LAPB frame");
101 proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0, -1,
102 "Invalid LAPB frame");
106 switch (pinfo->p2p_dir) {
124 * XXX - should we base this on the source and destination
125 * addresses? The problem is that we can tell one direction
126 * from another with that, but we can't say which is DTE->DCE
127 * and which is DCE->DTE.
134 ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0, 2,
136 lapb_tree = proto_item_add_subtree(ti, ett_lapb);
137 proto_tree_add_uint_format(lapb_tree, hf_lapb_address, tvb, 0, 1, byte0,
138 "Address: 0x%02X", byte0);
143 dissect_xdlc_control(tvb, 1, pinfo, lapb_tree, hf_lapb_control,
144 ett_lapb_control, &lapb_cf_items, NULL, NULL, NULL,
145 is_response, FALSE, FALSE);
147 /* not end of frame ==> X.25 */
148 if (tvb_reported_length(tvb) > 2) {
149 next_tvb = tvb_new_subset_remaining(tvb, 2);
150 switch (pinfo->p2p_dir) {
154 call_dissector(x25_dir_handle, next_tvb, pinfo, tree);
158 call_dissector(x25_handle, next_tvb, pinfo, tree);
165 proto_register_lapb(void)
167 static hf_register_info hf[] = {
169 { "Address Field", "lapb.address", FT_UINT8, BASE_HEX, NULL, 0x0,
173 { "Control Field", "lapb.control", FT_UINT8, BASE_HEX, NULL, 0x0,
174 "Control field", HFILL }},
177 { "N(R)", "lapb.control.n_r", FT_UINT8, BASE_DEC,
178 NULL, XDLC_N_R_MASK, NULL, HFILL }},
181 { "N(S)", "lapb.control.n_s", FT_UINT8, BASE_DEC,
182 NULL, XDLC_N_S_MASK, NULL, HFILL }},
185 { "Poll", "lapb.control.p", FT_BOOLEAN, 8,
186 TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
189 { "Final", "lapb.control.f", FT_BOOLEAN, 8,
190 TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
193 { "Supervisory frame type", "lapb.control.s_ftype", FT_UINT8, BASE_HEX,
194 VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
196 { &hf_lapb_u_modifier_cmd,
197 { "Command", "lapb.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
198 VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
200 { &hf_lapb_u_modifier_resp,
201 { "Response", "lapb.control.u_modifier_resp", FT_UINT8, BASE_HEX,
202 VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
205 { "Frame type", "lapb.control.ftype", FT_UINT8, BASE_HEX,
206 VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
208 { &hf_lapb_ftype_s_u,
209 { "Frame type", "lapb.control.ftype", FT_UINT8, BASE_HEX,
210 VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
212 static gint *ett[] = {
217 proto_lapb = proto_register_protocol("Link Access Procedure Balanced (LAPB)",
219 proto_register_field_array (proto_lapb, hf, array_length(hf));
220 proto_register_subtree_array(ett, array_length(ett));
222 register_dissector("lapb", dissect_lapb, proto_lapb);
226 proto_reg_handoff_lapb(void)
228 dissector_handle_t lapb_handle;
231 * Get handles for the X.25 dissectors; we don't get an X.25
232 * pseudo-header for LAPB-over-Ethernet, but we do get it
235 x25_dir_handle = find_dissector("x.25_dir");
236 x25_handle = find_dissector("x.25");
238 lapb_handle = find_dissector("lapb");
239 dissector_add("wtap_encap", WTAP_ENCAP_LAPB, lapb_handle);