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1 office 1 /*
2 * This module implements decoding of AHCP (Ad Hoc Configuration Protocol) based
3 * on draft-chroboczek-ahcp-00 and source code of ahcpd-0.53.
4 *
5 *
6 * Copyright (c) 2013 The TCPDUMP project
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
24 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
26 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
28 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31  
32 #define NETDISSECT_REWORKED
33 #ifdef HAVE_CONFIG_H
34 #include "config.h"
35 #endif
36  
37 #include <tcpdump-stdinc.h>
38  
39 #include "interface.h"
40 #include "extract.h"
41 #include "addrtoname.h"
42  
43 static const char tstr[] = " [|ahcp]";
44 static const char cstr[] = "(corrupt)";
45  
46 #define AHCP_MAGIC_NUMBER 43
47 #define AHCP_VERSION_1 1
48 #define AHCP1_HEADER_FIX_LEN 24
49 #define AHCP1_BODY_MIN_LEN 4
50  
51 #define AHCP1_MSG_DISCOVER 0
52 #define AHCP1_MSG_OFFER 1
53 #define AHCP1_MSG_REQUEST 2
54 #define AHCP1_MSG_ACK 3
55 #define AHCP1_MSG_NACK 4
56 #define AHCP1_MSG_RELEASE 5
57  
58 static const struct tok ahcp1_msg_str[] = {
59 { AHCP1_MSG_DISCOVER, "Discover" },
60 { AHCP1_MSG_OFFER, "Offer" },
61 { AHCP1_MSG_REQUEST, "Request" },
62 { AHCP1_MSG_ACK, "Ack" },
63 { AHCP1_MSG_NACK, "Nack" },
64 { AHCP1_MSG_RELEASE, "Release" },
65 { 0, NULL }
66 };
67  
68 #define AHCP1_OPT_PAD 0
69 #define AHCP1_OPT_MANDATORY 1
70 #define AHCP1_OPT_ORIGIN_TIME 2
71 #define AHCP1_OPT_EXPIRES 3
72 #define AHCP1_OPT_MY_IPV6_ADDRESS 4
73 #define AHCP1_OPT_MY_IPV4_ADDRESS 5
74 #define AHCP1_OPT_IPV6_PREFIX 6
75 #define AHCP1_OPT_IPV4_PREFIX 7
76 #define AHCP1_OPT_IPV6_ADDRESS 8
77 #define AHCP1_OPT_IPV4_ADDRESS 9
78 #define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
79 #define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
80 #define AHCP1_OPT_NAME_SERVER 12
81 #define AHCP1_OPT_NTP_SERVER 13
82 #define AHCP1_OPT_MAX 13
83  
84 static const struct tok ahcp1_opt_str[] = {
85 { AHCP1_OPT_PAD, "Pad" },
86 { AHCP1_OPT_MANDATORY, "Mandatory" },
87 { AHCP1_OPT_ORIGIN_TIME, "Origin Time" },
88 { AHCP1_OPT_EXPIRES, "Expires" },
89 { AHCP1_OPT_MY_IPV6_ADDRESS, "My-IPv6-Address" },
90 { AHCP1_OPT_MY_IPV4_ADDRESS, "My-IPv4-Address" },
91 { AHCP1_OPT_IPV6_PREFIX, "IPv6 Prefix" },
92 { AHCP1_OPT_IPV4_PREFIX, "IPv4 Prefix" },
93 { AHCP1_OPT_IPV6_ADDRESS, "IPv6 Address" },
94 { AHCP1_OPT_IPV4_ADDRESS, "IPv4 Address" },
95 { AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
96 { AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
97 { AHCP1_OPT_NAME_SERVER, "Name Server" },
98 { AHCP1_OPT_NTP_SERVER, "NTP Server" },
99 { 0, NULL }
100 };
101  
102 static int
103 ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
104 {
105 time_t t;
106 struct tm *tm;
107 char buf[BUFSIZE];
108  
109 if (cp + 4 != ep)
110 goto corrupt;
111 ND_TCHECK2(*cp, 4);
112 t = EXTRACT_32BITS(cp);
113 if (NULL == (tm = gmtime(&t)))
114 ND_PRINT((ndo, ": gmtime() error"));
115 else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
116 ND_PRINT((ndo, ": strftime() error"));
117 else
118 ND_PRINT((ndo, ": %s UTC", buf));
119 return 0;
120  
121 corrupt:
122 ND_PRINT((ndo, ": %s", cstr));
123 ND_TCHECK2(*cp, ep - cp);
124 return 0;
125 trunc:
126 ND_PRINT((ndo, "%s", tstr));
127 return -1;
128 }
129  
130 static int
131 ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
132 {
133 if (cp + 4 != ep)
134 goto corrupt;
135 ND_TCHECK2(*cp, 4);
136 ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
137 return 0;
138  
139 corrupt:
140 ND_PRINT((ndo, ": %s", cstr));
141 ND_TCHECK2(*cp, ep - cp);
142 return 0;
143 trunc:
144 ND_PRINT((ndo, "%s", tstr));
145 return -1;
146 }
147  
148 static int
149 ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
150 {
151 const char *sep = ": ";
152  
153 while (cp < ep) {
154 if (cp + 16 > ep)
155 goto corrupt;
156 ND_TCHECK2(*cp, 16);
157 #ifdef INET6
158 ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
159 #else
160 ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
161 #endif /* INET6 */
162 cp += 16;
163 sep = ", ";
164 }
165 return 0;
166  
167 corrupt:
168 ND_PRINT((ndo, ": %s", cstr));
169 ND_TCHECK2(*cp, ep - cp);
170 return 0;
171 trunc:
172 ND_PRINT((ndo, "%s", tstr));
173 return -1;
174 }
175  
176 static int
177 ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
178 {
179 const char *sep = ": ";
180  
181 while (cp < ep) {
182 if (cp + 4 > ep)
183 goto corrupt;
184 ND_TCHECK2(*cp, 4);
185 ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
186 cp += 4;
187 sep = ", ";
188 }
189 return 0;
190  
191 corrupt:
192 ND_PRINT((ndo, ": %s", cstr));
193 ND_TCHECK2(*cp, ep - cp);
194 return 0;
195 trunc:
196 ND_PRINT((ndo, "%s", tstr));
197 return -1;
198 }
199  
200 static int
201 ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
202 {
203 const char *sep = ": ";
204  
205 while (cp < ep) {
206 if (cp + 17 > ep)
207 goto corrupt;
208 ND_TCHECK2(*cp, 17);
209 #ifdef INET6
210 ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
211 #else
212 ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
213 #endif /* INET6 */
214 cp += 17;
215 sep = ", ";
216 }
217 return 0;
218  
219 corrupt:
220 ND_PRINT((ndo, ": %s", cstr));
221 ND_TCHECK2(*cp, ep - cp);
222 return 0;
223 trunc:
224 ND_PRINT((ndo, "%s", tstr));
225 return -1;
226 }
227  
228 static int
229 ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
230 {
231 const char *sep = ": ";
232  
233 while (cp < ep) {
234 if (cp + 5 > ep)
235 goto corrupt;
236 ND_TCHECK2(*cp, 5);
237 ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
238 cp += 5;
239 sep = ", ";
240 }
241 return 0;
242  
243 corrupt:
244 ND_PRINT((ndo, ": %s", cstr));
245 ND_TCHECK2(*cp, ep - cp);
246 return 0;
247 trunc:
248 ND_PRINT((ndo, "%s", tstr));
249 return -1;
250 }
251  
252 /* Data decoders signal truncated data with -1. */
253 static int
254 (* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
255 /* [AHCP1_OPT_PAD] = */ NULL,
256 /* [AHCP1_OPT_MANDATORY] = */ NULL,
257 /* [AHCP1_OPT_ORIGIN_TIME] = */ ahcp_time_print,
258 /* [AHCP1_OPT_EXPIRES] = */ ahcp_seconds_print,
259 /* [AHCP1_OPT_MY_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
260 /* [AHCP1_OPT_MY_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
261 /* [AHCP1_OPT_IPV6_PREFIX] = */ ahcp_ipv6_prefixes_print,
262 /* [AHCP1_OPT_IPV4_PREFIX] = */ NULL,
263 /* [AHCP1_OPT_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
264 /* [AHCP1_OPT_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
265 /* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */ ahcp_ipv6_prefixes_print,
266 /* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */ ahcp_ipv4_prefixes_print,
267 /* [AHCP1_OPT_NAME_SERVER] = */ ahcp_ipv6_addresses_print,
268 /* [AHCP1_OPT_NTP_SERVER] = */ ahcp_ipv6_addresses_print,
269 };
270  
271 static void
272 ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
273 {
274 uint8_t option_no, option_len;
275  
276 while (cp < ep) {
277 /* Option no */
278 ND_TCHECK2(*cp, 1);
279 option_no = *cp;
280 cp += 1;
281 ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
282 if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
283 continue;
284 /* Length */
285 if (cp + 1 > ep)
286 goto corrupt;
287 ND_TCHECK2(*cp, 1);
288 option_len = *cp;
289 cp += 1;
290 if (cp + option_len > ep)
291 goto corrupt;
292 /* Value */
293 if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
294 if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
295 break; /* truncated and already marked up */
296 } else {
297 ND_PRINT((ndo, " (Length %u)", option_len));
298 ND_TCHECK2(*cp, option_len);
299 }
300 cp += option_len;
301 }
302 return;
303  
304 corrupt:
305 ND_PRINT((ndo, " %s", cstr));
306 ND_TCHECK2(*cp, ep - cp);
307 return;
308 trunc:
309 ND_PRINT((ndo, "%s", tstr));
310 }
311  
312 static void
313 ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
314 {
315 uint8_t type, mbz;
316 uint16_t body_len;
317  
318 if (cp + AHCP1_BODY_MIN_LEN > ep)
319 goto corrupt;
320 /* Type */
321 ND_TCHECK2(*cp, 1);
322 type = *cp;
323 cp += 1;
324 /* MBZ */
325 ND_TCHECK2(*cp, 1);
326 mbz = *cp;
327 cp += 1;
328 /* Length */
329 ND_TCHECK2(*cp, 2);
330 body_len = EXTRACT_16BITS(cp);
331 cp += 2;
332  
333 if (ndo->ndo_vflag) {
334 ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
335 if (mbz != 0)
336 ND_PRINT((ndo, ", MBZ %u", mbz));
337 ND_PRINT((ndo, ", Length %u", body_len));
338 }
339 if (cp + body_len > ep)
340 goto corrupt;
341  
342 /* Options */
343 if (ndo->ndo_vflag >= 2)
344 ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
345 else
346 ND_TCHECK2(*cp, body_len);
347 return;
348  
349 corrupt:
350 ND_PRINT((ndo, " %s", cstr));
351 ND_TCHECK2(*cp, ep - cp);
352 return;
353 trunc:
354 ND_PRINT((ndo, "%s", tstr));
355 }
356  
357 void
358 ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len)
359 {
360 const u_char *ep = cp + len;
361 uint8_t version;
362  
363 ND_PRINT((ndo, "AHCP"));
364 if (len < 2)
365 goto corrupt;
366 /* Magic */
367 ND_TCHECK2(*cp, 1);
368 if (*cp != AHCP_MAGIC_NUMBER)
369 goto corrupt;
370 cp += 1;
371 /* Version */
372 ND_TCHECK2(*cp, 1);
373 version = *cp;
374 cp += 1;
375 switch (version) {
376 case AHCP_VERSION_1: {
377 ND_PRINT((ndo, " Version 1"));
378 if (len < AHCP1_HEADER_FIX_LEN)
379 goto corrupt;
380 if (!ndo->ndo_vflag) {
381 ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
382 cp += AHCP1_HEADER_FIX_LEN - 2;
383 } else {
384 /* Hopcount */
385 ND_TCHECK2(*cp, 1);
386 ND_PRINT((ndo, "\n\tHopcount %u", *cp));
387 cp += 1;
388 /* Original Hopcount */
389 ND_TCHECK2(*cp, 1);
390 ND_PRINT((ndo, ", Original Hopcount %u", *cp));
391 cp += 1;
392 /* Nonce */
393 ND_TCHECK2(*cp, 4);
394 ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
395 cp += 4;
396 /* Source Id */
397 ND_TCHECK2(*cp, 8);
398 ND_PRINT((ndo, ", Source Id %s", linkaddr_string(ndo, cp, 0, 8)));
399 cp += 8;
400 /* Destination Id */
401 ND_TCHECK2(*cp, 8);
402 ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, cp, 0, 8)));
403 cp += 8;
404 }
405 /* Body */
406 ahcp1_body_print(ndo, cp, ep);
407 break;
408 }
409 default:
410 ND_PRINT((ndo, " Version %u (unknown)", version));
411 break;
412 }
413 return;
414  
415 corrupt:
416 ND_PRINT((ndo, " %s", cstr));
417 ND_TCHECK2(*cp, ep - cp);
418 return;
419 trunc:
420 ND_PRINT((ndo, "%s", tstr));
421 }