1 /* packet-dec-bpdu.c
2 * Routines for DEC BPDU (DEC Spanning Tree Protocol) disassembly
3 *
4 * Copyright 2001 Paul Ionescu <paul@acorp.ro>
5 *
6 * Wireshark - Network traffic analyzer
7 * By Gerald Combs <gerald@wireshark.org>
8 * Copyright 1998 Gerald Combs
9 *
10 * SPDX-License-Identifier: GPL-2.0-or-later
11 */
12
13 #include "config.h"
14
15 #include <epan/packet.h>
16 #include <epan/etypes.h>
17 #include <epan/ppptypes.h>
18
19 /* Offsets of fields within a BPDU */
20
21 #define BPDU_DEC_CODE 0
22 #define BPDU_TYPE 1
23 #define BPDU_VERSION 2
24 #define BPDU_FLAGS 3
25 #define BPDU_ROOT_PRI 4
26 #define BPDU_ROOT_MAC 6
27 #define BPDU_ROOT_PATH_COST 12
28 #define BPDU_BRIDGE_PRI 14
29 #define BPDU_BRIDGE_MAC 16
30 #define BPDU_PORT_IDENTIFIER 22
31 #define BPDU_MESSAGE_AGE 23
32 #define BPDU_HELLO_TIME 24
33 #define BPDU_MAX_AGE 25
34 #define BPDU_FORWARD_DELAY 26
35
36 #define DEC_BPDU_SIZE 27
37
38 /* Flag bits */
39
40 #define BPDU_FLAGS_SHORT_TIMERS 0x80
41 #define BPDU_FLAGS_TCACK 0x02
42 #define BPDU_FLAGS_TC 0x01
43
44 void proto_register_dec_bpdu(void);
45 void proto_reg_handoff_dec_bpdu(void);
46
47 static int proto_dec_bpdu = -1;
48 static int hf_dec_bpdu_proto_id = -1;
49 static int hf_dec_bpdu_type = -1;
50 static int hf_dec_bpdu_version_id = -1;
51 static int hf_dec_bpdu_flags = -1;
52 static int hf_dec_bpdu_flags_short_timers = -1;
53 static int hf_dec_bpdu_flags_tcack = -1;
54 static int hf_dec_bpdu_flags_tc = -1;
55 static int hf_dec_bpdu_root_pri = -1;
56 static int hf_dec_bpdu_root_mac = -1;
57 static int hf_dec_bpdu_root_cost = -1;
58 static int hf_dec_bpdu_bridge_pri = -1;
59 static int hf_dec_bpdu_bridge_mac = -1;
60 static int hf_dec_bpdu_port_id = -1;
61 static int hf_dec_bpdu_msg_age = -1;
62 static int hf_dec_bpdu_hello_time = -1;
63 static int hf_dec_bpdu_max_age = -1;
64 static int hf_dec_bpdu_forward_delay = -1;
65
66 static gint ett_dec_bpdu = -1;
67 static gint ett_dec_bpdu_flags = -1;
68
69 static const value_string protocol_id_vals[] = {
70 { 0xe1, "DEC Spanning Tree Protocol" },
71 { 0, NULL }
72 };
73
74 #define BPDU_TYPE_TOPOLOGY_CHANGE 2
75 #define BPDU_TYPE_HELLO 25
76
77 static const value_string bpdu_type_vals[] = {
78 { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },
79 { BPDU_TYPE_HELLO, "Hello Packet" },
80 { 0, NULL }
81 };
82
83 static int
dissect_dec_bpdu(tvbuff_t * tvb,packet_info * pinfo,proto_tree * tree,void * data _U_)84 dissect_dec_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
85 {
86 guint8 bpdu_type;
87 proto_tree *bpdu_tree;
88 proto_item *ti;
89 static int * const bpdu_flags[] = {
90 &hf_dec_bpdu_flags_short_timers,
91 &hf_dec_bpdu_flags_tcack,
92 &hf_dec_bpdu_flags_tc,
93 NULL
94 };
95
96 col_set_str(pinfo->cinfo, COL_PROTOCOL, "DEC_STP");
97 col_clear(pinfo->cinfo, COL_INFO);
98
99 bpdu_type = tvb_get_guint8(tvb, BPDU_TYPE);
100
101 col_add_str(pinfo->cinfo, COL_INFO,
102 val_to_str(bpdu_type, bpdu_type_vals,
103 "Unknown BPDU type (%u)"));
104
105 set_actual_length(tvb, DEC_BPDU_SIZE);
106
107 if (tree) {
108 ti = proto_tree_add_item(tree, proto_dec_bpdu, tvb, 0, DEC_BPDU_SIZE,
109 ENC_NA);
110 bpdu_tree = proto_item_add_subtree(ti, ett_dec_bpdu);
111
112 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_proto_id, tvb,
113 BPDU_DEC_CODE, 1, ENC_BIG_ENDIAN);
114
115 proto_tree_add_uint(bpdu_tree, hf_dec_bpdu_type, tvb,
116 BPDU_TYPE, 1, bpdu_type);
117
118 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_version_id, tvb,
119 BPDU_VERSION, 1, ENC_BIG_ENDIAN);
120
121 proto_tree_add_bitmask_with_flags(bpdu_tree, tvb, BPDU_FLAGS, hf_dec_bpdu_flags, ett_dec_bpdu_flags, bpdu_flags, ENC_NA, BMT_NO_FALSE|BMT_NO_TFS);
122 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_pri, tvb,
123 BPDU_ROOT_PRI, 2, ENC_BIG_ENDIAN);
124 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_mac, tvb,
125 BPDU_ROOT_MAC, 6, ENC_NA);
126 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_cost, tvb,
127 BPDU_ROOT_PATH_COST, 2, ENC_BIG_ENDIAN);
128 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_pri, tvb,
129 BPDU_BRIDGE_PRI, 2, ENC_BIG_ENDIAN);
130 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_mac, tvb,
131 BPDU_BRIDGE_MAC, 6, ENC_NA);
132 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_port_id, tvb,
133 BPDU_PORT_IDENTIFIER, 1, ENC_BIG_ENDIAN);
134 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_msg_age, tvb,
135 BPDU_MESSAGE_AGE, 1, ENC_BIG_ENDIAN);
136 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_hello_time, tvb,
137 BPDU_HELLO_TIME, 1, ENC_BIG_ENDIAN);
138 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_max_age, tvb,
139 BPDU_MAX_AGE, 1, ENC_BIG_ENDIAN);
140 proto_tree_add_item(bpdu_tree, hf_dec_bpdu_forward_delay, tvb,
141 BPDU_FORWARD_DELAY, 1, ENC_BIG_ENDIAN);
142
143 }
144 return tvb_captured_length(tvb);
145 }
146
147 void
proto_register_dec_bpdu(void)148 proto_register_dec_bpdu(void)
149 {
150
151 static hf_register_info hf[] = {
152 { &hf_dec_bpdu_proto_id,
153 { "Protocol Identifier", "dec_stp.protocol",
154 FT_UINT8, BASE_HEX, VALS(protocol_id_vals), 0x0,
155 NULL, HFILL }},
156 { &hf_dec_bpdu_type,
157 { "BPDU Type", "dec_stp.type",
158 FT_UINT8, BASE_DEC, VALS(bpdu_type_vals), 0x0,
159 NULL, HFILL }},
160 { &hf_dec_bpdu_version_id,
161 { "BPDU Version", "dec_stp.version",
162 FT_UINT8, BASE_DEC, NULL, 0x0,
163 NULL, HFILL }},
164 { &hf_dec_bpdu_flags,
165 { "BPDU flags", "dec_stp.flags",
166 FT_UINT8, BASE_HEX, NULL, 0x0,
167 NULL, HFILL }},
168 { &hf_dec_bpdu_flags_short_timers,
169 { "Use short timers", "dec_stp.flags.short_timers",
170 FT_BOOLEAN, 8, TFS(&tfs_yes_no), BPDU_FLAGS_SHORT_TIMERS,
171 NULL, HFILL }},
172 { &hf_dec_bpdu_flags_tcack,
173 { "Topology Change Acknowledgment", "dec_stp.flags.tcack",
174 FT_BOOLEAN, 8, TFS(&tfs_yes_no), BPDU_FLAGS_TCACK,
175 NULL, HFILL }},
176 { &hf_dec_bpdu_flags_tc,
177 { "Topology Change", "dec_stp.flags.tc",
178 FT_BOOLEAN, 8, TFS(&tfs_yes_no), BPDU_FLAGS_TC,
179 NULL, HFILL }},
180 { &hf_dec_bpdu_root_pri,
181 { "Root Priority", "dec_stp.root.pri",
182 FT_UINT16, BASE_DEC, NULL, 0x0,
183 NULL, HFILL }},
184 { &hf_dec_bpdu_root_mac,
185 { "Root MAC", "dec_stp.root.mac",
186 FT_ETHER, BASE_NONE, NULL, 0x0,
187 NULL, HFILL }},
188 { &hf_dec_bpdu_root_cost,
189 { "Root Path Cost", "dec_stp.root.cost",
190 FT_UINT16, BASE_DEC, NULL, 0x0,
191 NULL, HFILL }},
192 { &hf_dec_bpdu_bridge_pri,
193 { "Bridge Priority", "dec_stp.bridge.pri",
194 FT_UINT16, BASE_DEC, NULL, 0x0,
195 NULL, HFILL }},
196 { &hf_dec_bpdu_bridge_mac,
197 { "Bridge MAC", "dec_stp.bridge.mac",
198 FT_ETHER, BASE_NONE, NULL, 0x0,
199 NULL, HFILL }},
200 { &hf_dec_bpdu_port_id,
201 { "Port identifier", "dec_stp.port",
202 FT_UINT8, BASE_DEC, NULL, 0x0,
203 NULL, HFILL }},
204 { &hf_dec_bpdu_msg_age,
205 { "Message Age", "dec_stp.msg_age",
206 FT_UINT8, BASE_DEC, NULL, 0x0,
207 NULL, HFILL }},
208 { &hf_dec_bpdu_hello_time,
209 { "Hello Time", "dec_stp.hello",
210 FT_UINT8, BASE_DEC, NULL, 0x0,
211 NULL, HFILL }},
212 { &hf_dec_bpdu_max_age,
213 { "Max Age", "dec_stp.max_age",
214 FT_UINT8, BASE_DEC, NULL, 0x0,
215 NULL, HFILL }},
216 { &hf_dec_bpdu_forward_delay,
217 { "Forward Delay", "dec_stp.forward",
218 FT_UINT8, BASE_DEC, NULL, 0x0,
219 NULL, HFILL }},
220 };
221 static gint *ett[] = {
222 &ett_dec_bpdu,
223 &ett_dec_bpdu_flags,
224 };
225
226 proto_dec_bpdu = proto_register_protocol("DEC Spanning Tree Protocol",
227 "DEC_STP", "dec_stp");
228 proto_register_field_array(proto_dec_bpdu, hf, array_length(hf));
229 proto_register_subtree_array(ett, array_length(ett));
230 }
231
232 void
proto_reg_handoff_dec_bpdu(void)233 proto_reg_handoff_dec_bpdu(void)
234 {
235 dissector_handle_t dec_bpdu_handle;
236
237 dec_bpdu_handle = create_dissector_handle(dissect_dec_bpdu,
238 proto_dec_bpdu);
239 dissector_add_uint("ethertype", ETHERTYPE_DEC_LB, dec_bpdu_handle);
240 dissector_add_uint("chdlc.protocol", ETHERTYPE_DEC_LB, dec_bpdu_handle);
241 dissector_add_uint("ppp.protocol", PPP_DEC_LB, dec_bpdu_handle);
242 }
243
244 /*
245 * Editor modelines - https://www.wireshark.org/tools/modelines.html
246 *
247 * Local variables:
248 * c-basic-offset: 4
249 * tab-width: 8
250 * indent-tabs-mode: nil
251 * End:
252 *
253 * vi: set shiftwidth=4 tabstop=8 expandtab:
254 * :indentSize=4:tabSize=8:noTabs=true:
255 */
256