print-ahcp.c revision 1.5 
1/*
2 * Copyright (c) 2013 The TCPDUMP project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
15 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
16 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
17 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
18 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
20 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
24 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
25 * POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29#ifndef lint
30__RCSID("$NetBSD: print-ahcp.c,v 1.5 2017/02/05 04:05:05 spz Exp $");
31#endif
32
33/* \summary: Ad Hoc Configuration Protocol (AHCP) printer */
34
35/* Based on draft-chroboczek-ahcp-00 and source code of ahcpd-0.53 */
36
37#ifdef HAVE_CONFIG_H
38#include "config.h"
39#endif
40
41#include <netdissect-stdinc.h>
42
43#include "netdissect.h"
44#include "extract.h"
45#include "addrtoname.h"
46
47static const char tstr[] = " [|ahcp]";
48
49#define AHCP_MAGIC_NUMBER 43
50#define AHCP_VERSION_1 1
51#define AHCP1_HEADER_FIX_LEN 24
52#define AHCP1_BODY_MIN_LEN 4
53
54#define AHCP1_MSG_DISCOVER 0
55#define AHCP1_MSG_OFFER    1
56#define AHCP1_MSG_REQUEST  2
57#define AHCP1_MSG_ACK      3
58#define AHCP1_MSG_NACK     4
59#define AHCP1_MSG_RELEASE  5
60
61static const struct tok ahcp1_msg_str[] = {
62	{ AHCP1_MSG_DISCOVER, "Discover" },
63	{ AHCP1_MSG_OFFER,    "Offer"    },
64	{ AHCP1_MSG_REQUEST,  "Request"  },
65	{ AHCP1_MSG_ACK,      "Ack"      },
66	{ AHCP1_MSG_NACK,     "Nack"     },
67	{ AHCP1_MSG_RELEASE,  "Release"  },
68	{ 0, NULL }
69};
70
71#define AHCP1_OPT_PAD                     0
72#define AHCP1_OPT_MANDATORY               1
73#define AHCP1_OPT_ORIGIN_TIME             2
74#define AHCP1_OPT_EXPIRES                 3
75#define AHCP1_OPT_MY_IPV6_ADDRESS         4
76#define AHCP1_OPT_MY_IPV4_ADDRESS         5
77#define AHCP1_OPT_IPV6_PREFIX             6
78#define AHCP1_OPT_IPV4_PREFIX             7
79#define AHCP1_OPT_IPV6_ADDRESS            8
80#define AHCP1_OPT_IPV4_ADDRESS            9
81#define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
82#define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
83#define AHCP1_OPT_NAME_SERVER            12
84#define AHCP1_OPT_NTP_SERVER             13
85#define AHCP1_OPT_MAX                    13
86
87static const struct tok ahcp1_opt_str[] = {
88	{ AHCP1_OPT_PAD,                    "Pad"                    },
89	{ AHCP1_OPT_MANDATORY,              "Mandatory"              },
90	{ AHCP1_OPT_ORIGIN_TIME,            "Origin Time"            },
91	{ AHCP1_OPT_EXPIRES,                "Expires"                },
92	{ AHCP1_OPT_MY_IPV6_ADDRESS,        "My-IPv6-Address"        },
93	{ AHCP1_OPT_MY_IPV4_ADDRESS,        "My-IPv4-Address"        },
94	{ AHCP1_OPT_IPV6_PREFIX,            "IPv6 Prefix"            },
95	{ AHCP1_OPT_IPV4_PREFIX,            "IPv4 Prefix"            },
96	{ AHCP1_OPT_IPV6_ADDRESS,           "IPv6 Address"           },
97	{ AHCP1_OPT_IPV4_ADDRESS,           "IPv4 Address"           },
98	{ AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
99	{ AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
100	{ AHCP1_OPT_NAME_SERVER,            "Name Server"            },
101	{ AHCP1_OPT_NTP_SERVER,             "NTP Server"             },
102	{ 0, NULL }
103};
104
105static int
106ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
107{
108	time_t t;
109	struct tm *tm;
110	char buf[BUFSIZE];
111
112	if (cp + 4 != ep)
113		goto invalid;
114	ND_TCHECK2(*cp, 4);
115	t = EXTRACT_32BITS(cp);
116	if (NULL == (tm = gmtime(&t)))
117		ND_PRINT((ndo, ": gmtime() error"));
118	else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
119		ND_PRINT((ndo, ": strftime() error"));
120	else
121		ND_PRINT((ndo, ": %s UTC", buf));
122	return 0;
123
124invalid:
125	ND_PRINT((ndo, "%s", istr));
126	ND_TCHECK2(*cp, ep - cp);
127	return 0;
128trunc:
129	ND_PRINT((ndo, "%s", tstr));
130	return -1;
131}
132
133static int
134ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
135{
136	if (cp + 4 != ep)
137		goto invalid;
138	ND_TCHECK2(*cp, 4);
139	ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
140	return 0;
141
142invalid:
143	ND_PRINT((ndo, "%s", istr));
144	ND_TCHECK2(*cp, ep - cp);
145	return 0;
146trunc:
147	ND_PRINT((ndo, "%s", tstr));
148	return -1;
149}
150
151static int
152ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
153{
154	const char *sep = ": ";
155
156	while (cp < ep) {
157		if (cp + 16 > ep)
158			goto invalid;
159		ND_TCHECK2(*cp, 16);
160		ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
161		cp += 16;
162		sep = ", ";
163	}
164	return 0;
165
166invalid:
167	ND_PRINT((ndo, "%s", istr));
168	ND_TCHECK2(*cp, ep - cp);
169	return 0;
170trunc:
171	ND_PRINT((ndo, "%s", tstr));
172	return -1;
173}
174
175static int
176ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
177{
178	const char *sep = ": ";
179
180	while (cp < ep) {
181		if (cp + 4 > ep)
182			goto invalid;
183		ND_TCHECK2(*cp, 4);
184		ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
185		cp += 4;
186		sep = ", ";
187	}
188	return 0;
189
190invalid:
191	ND_PRINT((ndo, "%s", istr));
192	ND_TCHECK2(*cp, ep - cp);
193	return 0;
194trunc:
195	ND_PRINT((ndo, "%s", tstr));
196	return -1;
197}
198
199static int
200ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
201{
202	const char *sep = ": ";
203
204	while (cp < ep) {
205		if (cp + 17 > ep)
206			goto invalid;
207		ND_TCHECK2(*cp, 17);
208		ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
209		cp += 17;
210		sep = ", ";
211	}
212	return 0;
213
214invalid:
215	ND_PRINT((ndo, "%s", istr));
216	ND_TCHECK2(*cp, ep - cp);
217	return 0;
218trunc:
219	ND_PRINT((ndo, "%s", tstr));
220	return -1;
221}
222
223static int
224ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
225{
226	const char *sep = ": ";
227
228	while (cp < ep) {
229		if (cp + 5 > ep)
230			goto invalid;
231		ND_TCHECK2(*cp, 5);
232		ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
233		cp += 5;
234		sep = ", ";
235	}
236	return 0;
237
238invalid:
239	ND_PRINT((ndo, "%s", istr));
240	ND_TCHECK2(*cp, ep - cp);
241	return 0;
242trunc:
243	ND_PRINT((ndo, "%s", tstr));
244	return -1;
245}
246
247/* Data decoders signal truncated data with -1. */
248static int
249(* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
250	/* [AHCP1_OPT_PAD]                    = */  NULL,
251	/* [AHCP1_OPT_MANDATORY]              = */  NULL,
252	/* [AHCP1_OPT_ORIGIN_TIME]            = */  ahcp_time_print,
253	/* [AHCP1_OPT_EXPIRES]                = */  ahcp_seconds_print,
254	/* [AHCP1_OPT_MY_IPV6_ADDRESS]        = */  ahcp_ipv6_addresses_print,
255	/* [AHCP1_OPT_MY_IPV4_ADDRESS]        = */  ahcp_ipv4_addresses_print,
256	/* [AHCP1_OPT_IPV6_PREFIX]            = */  ahcp_ipv6_prefixes_print,
257	/* [AHCP1_OPT_IPV4_PREFIX]            = */  NULL,
258	/* [AHCP1_OPT_IPV6_ADDRESS]           = */  ahcp_ipv6_addresses_print,
259	/* [AHCP1_OPT_IPV4_ADDRESS]           = */  ahcp_ipv4_addresses_print,
260	/* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */  ahcp_ipv6_prefixes_print,
261	/* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */  ahcp_ipv4_prefixes_print,
262	/* [AHCP1_OPT_NAME_SERVER]            = */  ahcp_ipv6_addresses_print,
263	/* [AHCP1_OPT_NTP_SERVER]             = */  ahcp_ipv6_addresses_print,
264};
265
266static void
267ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
268{
269	uint8_t option_no, option_len;
270
271	while (cp < ep) {
272		/* Option no */
273		ND_TCHECK2(*cp, 1);
274		option_no = *cp;
275		cp += 1;
276		ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
277		if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
278			continue;
279		/* Length */
280		if (cp + 1 > ep)
281			goto invalid;
282		ND_TCHECK2(*cp, 1);
283		option_len = *cp;
284		cp += 1;
285		if (cp + option_len > ep)
286			goto invalid;
287		/* Value */
288		if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
289			if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
290				break; /* truncated and already marked up */
291		} else {
292			ND_PRINT((ndo, " (Length %u)", option_len));
293			ND_TCHECK2(*cp, option_len);
294		}
295		cp += option_len;
296	}
297	return;
298
299invalid:
300	ND_PRINT((ndo, "%s", istr));
301	ND_TCHECK2(*cp, ep - cp);
302	return;
303trunc:
304	ND_PRINT((ndo, "%s", tstr));
305}
306
307static void
308ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
309{
310	uint8_t type, mbz;
311	uint16_t body_len;
312
313	if (cp + AHCP1_BODY_MIN_LEN > ep)
314		goto invalid;
315	/* Type */
316	ND_TCHECK2(*cp, 1);
317	type = *cp;
318	cp += 1;
319	/* MBZ */
320	ND_TCHECK2(*cp, 1);
321	mbz = *cp;
322	cp += 1;
323	/* Length */
324	ND_TCHECK2(*cp, 2);
325	body_len = EXTRACT_16BITS(cp);
326	cp += 2;
327
328	if (ndo->ndo_vflag) {
329		ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
330		if (mbz != 0)
331			ND_PRINT((ndo, ", MBZ %u", mbz));
332		ND_PRINT((ndo, ", Length %u", body_len));
333	}
334	if (cp + body_len > ep)
335		goto invalid;
336
337	/* Options */
338	if (ndo->ndo_vflag >= 2)
339		ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
340	else
341		ND_TCHECK2(*cp, body_len);
342	return;
343
344invalid:
345	ND_PRINT((ndo, "%s", istr));
346	ND_TCHECK2(*cp, ep - cp);
347	return;
348trunc:
349	ND_PRINT((ndo, "%s", tstr));
350}
351
352void
353ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len)
354{
355	const u_char *ep = cp + len;
356	uint8_t version;
357
358	ND_PRINT((ndo, "AHCP"));
359	if (len < 2)
360		goto invalid;
361	/* Magic */
362	ND_TCHECK2(*cp, 1);
363	if (*cp != AHCP_MAGIC_NUMBER)
364		goto invalid;
365	cp += 1;
366	/* Version */
367	ND_TCHECK2(*cp, 1);
368	version = *cp;
369	cp += 1;
370	switch (version) {
371		case AHCP_VERSION_1: {
372			ND_PRINT((ndo, " Version 1"));
373			if (len < AHCP1_HEADER_FIX_LEN)
374				goto invalid;
375			if (!ndo->ndo_vflag) {
376				ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
377				cp += AHCP1_HEADER_FIX_LEN - 2;
378			} else {
379				/* Hopcount */
380				ND_TCHECK2(*cp, 1);
381				ND_PRINT((ndo, "\n\tHopcount %u", *cp));
382				cp += 1;
383				/* Original Hopcount */
384				ND_TCHECK2(*cp, 1);
385				ND_PRINT((ndo, ", Original Hopcount %u", *cp));
386				cp += 1;
387				/* Nonce */
388				ND_TCHECK2(*cp, 4);
389				ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
390				cp += 4;
391				/* Source Id */
392				ND_TCHECK2(*cp, 8);
393				ND_PRINT((ndo, ", Source Id %s", linkaddr_string(ndo, cp, 0, 8)));
394				cp += 8;
395				/* Destination Id */
396				ND_TCHECK2(*cp, 8);
397				ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, cp, 0, 8)));
398				cp += 8;
399			}
400			/* Body */
401			ahcp1_body_print(ndo, cp, ep);
402			break;
403		}
404		default:
405			ND_PRINT((ndo, " Version %u (unknown)", version));
406			break;
407	}
408	return;
409
410invalid:
411	ND_PRINT((ndo, "%s", istr));
412	ND_TCHECK2(*cp, ep - cp);
413	return;
414trunc:
415	ND_PRINT((ndo, "%s", tstr));
416}
417