1/*
2 * Copyright (c) 2000 Lennert Buytenhek
3 *
4 * This software may be distributed either under the terms of the
5 * BSD-style license that accompanies tcpdump or the GNU General
6 * Public License
7 *
8 * Format and print IEEE 802.1d spanning tree protocol packets.
9 * Contributed by Lennert Buytenhek <buytenh@gnu.org>
10 */
11
12#ifndef lint
13static const char rcsid[] _U_ =
14"@(#) $Header: /tcpdump/master/tcpdump/print-stp.c,v 1.13.2.7 2007/03/18 17:12:36 hannes Exp $";
15#endif
16
17#ifdef HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <tcpdump-stdinc.h>
22
23#include <stdlib.h>
24#include <stdio.h>
25#include <string.h>
26
27#include "interface.h"
28#include "addrtoname.h"
29#include "extract.h"
30
31#define	RSTP_EXTRACT_PORT_ROLE(x) (((x)&0x0C)>>2)
32/* STP timers are expressed in multiples of 1/256th second */
33#define STP_TIME_BASE 256
34#define STP_BPDU_MSTP_MIN_LEN 102
35
36struct stp_bpdu_ {
37    u_int8_t protocol_id[2];
38    u_int8_t protocol_version;
39    u_int8_t bpdu_type;
40    u_int8_t flags;
41    u_int8_t root_id[8];
42    u_int8_t root_path_cost[4];
43    u_int8_t bridge_id[8];
44    u_int8_t port_id[2];
45    u_int8_t message_age[2];
46    u_int8_t max_age[2];
47    u_int8_t hello_time[2];
48    u_int8_t forward_delay[2];
49    u_int8_t v1_length;
50};
51
52#define STP_PROTO_REGULAR 0x00
53#define STP_PROTO_RAPID   0x02
54#define STP_PROTO_MSTP    0x03
55
56struct tok stp_proto_values[] = {
57    { STP_PROTO_REGULAR, "802.1d" },
58    { STP_PROTO_RAPID, "802.1w" },
59    { STP_PROTO_MSTP, "802.1s" },
60    { 0, NULL}
61};
62
63#define STP_BPDU_TYPE_CONFIG      0x00
64#define STP_BPDU_TYPE_RSTP        0x02
65#define STP_BPDU_TYPE_TOPO_CHANGE 0x80
66
67struct tok stp_bpdu_flag_values[] = {
68    { 0x01, "Topology change" },
69    { 0x02, "Proposal" },
70    { 0x10, "Learn" },
71    { 0x20, "Forward" },
72    { 0x40, "Agreement" },
73    { 0x80, "Topology change ACK" },
74    { 0, NULL}
75};
76
77struct tok stp_bpdu_type_values[] = {
78    { STP_BPDU_TYPE_CONFIG, "Config" },
79    { STP_BPDU_TYPE_RSTP, "Rapid STP" },
80    { STP_BPDU_TYPE_TOPO_CHANGE, "Topology Change" },
81    { 0, NULL}
82};
83
84struct tok rstp_obj_port_role_values[] = {
85    { 0x00, "Unknown" },
86    { 0x01, "Alternate" },
87    { 0x02, "Root" },
88    { 0x03, "Designated" },
89    { 0, NULL}
90};
91
92static char *
93stp_print_bridge_id(const u_char *p)
94{
95    static char bridge_id_str[sizeof("pppp.aa:bb:cc:dd:ee:ff")];
96
97    snprintf(bridge_id_str, sizeof(bridge_id_str),
98             "%.2x%.2x.%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
99             p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
100
101    return bridge_id_str;
102}
103
104static void
105stp_print_config_bpdu(const struct stp_bpdu_ *stp_bpdu, u_int length)
106{
107    printf(", Flags [%s]",
108           bittok2str(stp_bpdu_flag_values, "none", stp_bpdu->flags));
109
110    printf(", bridge-id %s.%04x, length %u",
111           stp_print_bridge_id((const u_char *)&stp_bpdu->bridge_id),
112           EXTRACT_16BITS(&stp_bpdu->port_id), length);
113
114    /* in non-verbose mode just print the bridge-id */
115    if (!vflag) {
116        return;
117    }
118
119    printf("\n\tmessage-age %.2fs, max-age %.2fs"
120           ", hello-time %.2fs, forwarding-delay %.2fs",
121           (float)EXTRACT_16BITS(&stp_bpdu->message_age) / STP_TIME_BASE,
122           (float)EXTRACT_16BITS(&stp_bpdu->max_age) / STP_TIME_BASE,
123           (float)EXTRACT_16BITS(&stp_bpdu->hello_time) / STP_TIME_BASE,
124           (float)EXTRACT_16BITS(&stp_bpdu->forward_delay) / STP_TIME_BASE);
125
126    printf("\n\troot-id %s, root-pathcost %u",
127           stp_print_bridge_id((const u_char *)&stp_bpdu->root_id),
128           EXTRACT_32BITS(&stp_bpdu->root_path_cost));
129
130    /* Port role is only valid for 802.1w */
131    if (stp_bpdu->protocol_version == STP_PROTO_RAPID) {
132        printf(", port-role %s",
133               tok2str(rstp_obj_port_role_values, "Unknown",
134                       RSTP_EXTRACT_PORT_ROLE(stp_bpdu->flags)));
135    }
136}
137
138/*
139 * MSTP packet format
140 * Ref. IEEE 802.1Q 2003 Ed. Section 14
141 *
142 * MSTP BPDU
143 *
144 * 2 -  bytes Protocol Id
145 * 1 -  byte  Protocol Ver.
146 * 1 -  byte  BPDU tye
147 * 1 -  byte  Flags
148 * 8 -  bytes CIST Root Identifier
149 * 4 -  bytes CIST External Path Cost
150 * 8 -  bytes CIST Regional Root Identifier
151 * 2 -  bytes CIST Port Identifier
152 * 2 -  bytes Message Age
153 * 2 -  bytes Max age
154 * 2 -  bytes Hello Time
155 * 2 -  bytes Forward delay
156 * 1 -  byte  Version 1 length. Must be 0
157 * 2 -  bytes Version 3 length
158 * 1 -  byte  Config Identifier
159 * 32 - bytes Config Name
160 * 2 -  bytes Revision level
161 * 16 - bytes Config Digest [MD5]
162 * 4 -  bytes CIST Internal Root Path Cost
163 * 8 -  bytes CIST Bridge Identifier
164 * 1 -  byte  CIST Remaining Hops
165 * 16 - bytes MSTI information [Max 64 MSTI, each 16 bytes]
166 *
167 * MSTI Payload
168 *
169 * 1 - byte  MSTI flag
170 * 8 - bytes MSTI Regional Root Identifier
171 * 4 - bytes MSTI Regional Path Cost
172 * 1 - byte  MSTI Bridge Priority
173 * 1 - byte  MSTI Port Priority
174 * 1 - byte  MSTI Remaining Hops
175 */
176
177#define MST_BPDU_MSTI_LENGTH		    16
178#define MST_BPDU_CONFIG_INFO_LENGTH	    64
179
180/* Offsets of fields from the begginning for the packet */
181#define MST_BPDU_VER3_LEN_OFFSET	    36
182#define MST_BPDU_CONFIG_NAME_OFFSET	    39
183#define MST_BPDU_CONFIG_DIGEST_OFFSET	    73
184#define MST_BPDU_CIST_INT_PATH_COST_OFFSET  89
185#define MST_BPDU_CIST_BRIDGE_ID_OFFSET	    93
186#define MST_BPDU_CIST_REMAIN_HOPS_OFFSET    101
187#define MST_BPDU_MSTI_OFFSET		    102
188/* Offsets within  an MSTI */
189#define MST_BPDU_MSTI_ROOT_PRIO_OFFSET	    1
190#define MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET 9
191#define MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET    13
192#define MST_BPDU_MSTI_PORT_PRIO_OFFSET	    14
193#define MST_BPDU_MSTI_REMAIN_HOPS_OFFSET    15
194
195static void
196stp_print_mstp_bpdu(const struct stp_bpdu_ *stp_bpdu, u_int length)
197{
198    const u_char    *ptr;
199    u_int16_t	    v3len;
200    u_int16_t	    len;
201    u_int16_t	    msti;
202    u_int16_t	    offset;
203
204    ptr = (const u_char *)stp_bpdu;
205    printf(", CIST Flags [%s]",
206           bittok2str(stp_bpdu_flag_values, "none", stp_bpdu->flags));
207
208    /*
209     * in non-verbose mode just print the flags. We dont read that much
210     * of the packet (DEFAULT_SNAPLEN) to print out cist bridge-id
211     */
212    if (!vflag) {
213        return;
214    }
215
216    printf(", CIST bridge-id %s.%04x, length %u",
217           stp_print_bridge_id(ptr + MST_BPDU_CIST_BRIDGE_ID_OFFSET),
218           EXTRACT_16BITS(&stp_bpdu->port_id), length);
219
220
221    printf("\n\tmessage-age %.2fs, max-age %.2fs"
222           ", hello-time %.2fs, forwarding-delay %.2fs",
223           (float)EXTRACT_16BITS(&stp_bpdu->message_age) / STP_TIME_BASE,
224           (float)EXTRACT_16BITS(&stp_bpdu->max_age) / STP_TIME_BASE,
225           (float)EXTRACT_16BITS(&stp_bpdu->hello_time) / STP_TIME_BASE,
226           (float)EXTRACT_16BITS(&stp_bpdu->forward_delay) / STP_TIME_BASE);
227
228    printf("\n\tCIST root-id %s, ext-pathcost %u int-pathcost %u",
229           stp_print_bridge_id((const u_char *)&stp_bpdu->root_id),
230           EXTRACT_32BITS(&stp_bpdu->root_path_cost),
231           EXTRACT_32BITS(ptr + MST_BPDU_CIST_INT_PATH_COST_OFFSET));
232
233    printf(", port-role %s",
234           tok2str(rstp_obj_port_role_values, "Unknown",
235                   RSTP_EXTRACT_PORT_ROLE(stp_bpdu->flags)));
236
237    printf("\n\tCIST regional-root-id %s",
238           stp_print_bridge_id((const u_char *)&stp_bpdu->bridge_id));
239
240    printf("\n\tMSTP Configuration Name %s, revision %u, digest %08x%08x%08x%08x",
241           ptr + MST_BPDU_CONFIG_NAME_OFFSET,
242	   EXTRACT_16BITS(ptr + MST_BPDU_CONFIG_NAME_OFFSET + 32),
243	   EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET),
244	   EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 4),
245	   EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 8),
246	   EXTRACT_32BITS(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 12));
247
248    printf("\n\tCIST remaining-hops %d", ptr[MST_BPDU_CIST_REMAIN_HOPS_OFFSET]);
249
250    /* Dump all MSTI's */
251    v3len = EXTRACT_16BITS(ptr + MST_BPDU_VER3_LEN_OFFSET);
252    if (v3len > MST_BPDU_CONFIG_INFO_LENGTH) {
253        len = v3len - MST_BPDU_CONFIG_INFO_LENGTH;
254        offset = MST_BPDU_MSTI_OFFSET;
255        while (len >= MST_BPDU_MSTI_LENGTH) {
256            msti = EXTRACT_16BITS(ptr + offset +
257                                  MST_BPDU_MSTI_ROOT_PRIO_OFFSET);
258            msti = msti & 0x0FFF;
259
260            printf("\n\tMSTI %d, Flags [%s], port-role %s",
261                   msti, bittok2str(stp_bpdu_flag_values, "none", ptr[offset]),
262                   tok2str(rstp_obj_port_role_values, "Unknown",
263                           RSTP_EXTRACT_PORT_ROLE(ptr[offset])));
264            printf("\n\t\tMSTI regional-root-id %s, pathcost %u",
265                   stp_print_bridge_id(ptr + offset +
266                                       MST_BPDU_MSTI_ROOT_PRIO_OFFSET),
267                   EXTRACT_32BITS(ptr + offset +
268                                  MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET));
269            printf("\n\t\tMSTI bridge-prio %d, port-prio %d, hops %d",
270                   ptr[offset + MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET] >> 4,
271                   ptr[offset + MST_BPDU_MSTI_PORT_PRIO_OFFSET] >> 4,
272                   ptr[offset + MST_BPDU_MSTI_REMAIN_HOPS_OFFSET]);
273
274            len -= MST_BPDU_MSTI_LENGTH;
275            offset += MST_BPDU_MSTI_LENGTH;
276        }
277    }
278}
279
280/*
281 * Print 802.1d / 802.1w / 802.1q (mstp) packets.
282 */
283void
284stp_print(const u_char *p, u_int length)
285{
286    const struct stp_bpdu_ *stp_bpdu;
287    u_int16_t              mstp_len;
288
289    stp_bpdu = (struct stp_bpdu_*)p;
290
291    /* Minimum STP Frame size. */
292    if (length < 4)
293        goto trunc;
294
295    if (EXTRACT_16BITS(&stp_bpdu->protocol_id)) {
296        printf("unknown STP version, length %u", length);
297        return;
298    }
299
300    printf("STP %s", tok2str(stp_proto_values, "Unknown STP protocol (0x%02x)",
301                         stp_bpdu->protocol_version));
302
303    switch (stp_bpdu->protocol_version) {
304    case STP_PROTO_REGULAR:
305    case STP_PROTO_RAPID:
306    case STP_PROTO_MSTP:
307        break;
308    default:
309        return;
310    }
311
312    printf(", %s", tok2str(stp_bpdu_type_values, "Unknown BPDU Type (0x%02x)",
313                           stp_bpdu->bpdu_type));
314
315    switch (stp_bpdu->bpdu_type) {
316    case STP_BPDU_TYPE_CONFIG:
317        if (length < sizeof(struct stp_bpdu_) - 1) {
318            goto trunc;
319        }
320        stp_print_config_bpdu(stp_bpdu, length);
321        break;
322
323    case STP_BPDU_TYPE_RSTP:
324        if (stp_bpdu->protocol_version == STP_PROTO_RAPID) {
325            if (length < sizeof(struct stp_bpdu_)) {
326                goto trunc;
327            }
328            stp_print_config_bpdu(stp_bpdu, length);
329        } else if (stp_bpdu->protocol_version == STP_PROTO_MSTP) {
330            if (length < STP_BPDU_MSTP_MIN_LEN) {
331                goto trunc;
332            }
333            if (stp_bpdu->v1_length != 0) {
334                /* FIX ME: Emit a message here ? */
335                goto trunc;
336            }
337            /* Validate v3 length */
338            mstp_len = EXTRACT_16BITS(p + MST_BPDU_VER3_LEN_OFFSET);
339            mstp_len += 2;  /* length encoding itself is 2 bytes */
340            if (length < (sizeof(struct stp_bpdu_) + mstp_len)) {
341                goto trunc;
342            }
343            stp_print_mstp_bpdu(stp_bpdu, length);
344        }
345        break;
346
347    case STP_BPDU_TYPE_TOPO_CHANGE:
348        /* always empty message - just break out */
349        break;
350
351    default:
352        break;
353    }
354
355    return;
356 trunc:
357    printf("[|stp %d]", length);
358}
359
360/*
361 * Local Variables:
362 * c-style: whitesmith
363 * c-basic-offset: 4
364 * End:
365 */
366