print-icmp.c revision 172686 
1/*
2 * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994, 1995, 1996
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * $FreeBSD: head/contrib/tcpdump/print-icmp.c 172686 2007-10-16 02:31:48Z mlaier $
22 */
23
24#ifndef lint
25static const char rcsid[] _U_ =
26    "@(#) $Header: /tcpdump/master/tcpdump/print-icmp.c,v 1.81.2.6 2007/09/13 17:40:18 guy Exp $ (LBL)";
27#endif
28
29#ifdef HAVE_CONFIG_H
30#include "config.h"
31#endif
32
33#include <tcpdump-stdinc.h>
34
35#include <stdio.h>
36#include <string.h>
37
38#include "interface.h"
39#include "addrtoname.h"
40#include "extract.h"			/* must come after interface.h */
41
42#include "ip.h"
43#include "udp.h"
44#include "ipproto.h"
45#include "mpls.h"
46
47/*
48 * Interface Control Message Protocol Definitions.
49 * Per RFC 792, September 1981.
50 */
51
52/*
53 * Structure of an icmp header.
54 */
55struct icmp {
56	u_int8_t  icmp_type;		/* type of message, see below */
57	u_int8_t  icmp_code;		/* type sub code */
58	u_int16_t icmp_cksum;		/* ones complement cksum of struct */
59	union {
60		u_int8_t ih_pptr;			/* ICMP_PARAMPROB */
61		struct in_addr ih_gwaddr;	/* ICMP_REDIRECT */
62		struct ih_idseq {
63			u_int16_t icd_id;
64			u_int16_t icd_seq;
65		} ih_idseq;
66		u_int32_t ih_void;
67	} icmp_hun;
68#define	icmp_pptr	icmp_hun.ih_pptr
69#define	icmp_gwaddr	icmp_hun.ih_gwaddr
70#define	icmp_id		icmp_hun.ih_idseq.icd_id
71#define	icmp_seq	icmp_hun.ih_idseq.icd_seq
72#define	icmp_void	icmp_hun.ih_void
73	union {
74		struct id_ts {
75			u_int32_t its_otime;
76			u_int32_t its_rtime;
77			u_int32_t its_ttime;
78		} id_ts;
79		struct id_ip  {
80			struct ip idi_ip;
81			/* options and then 64 bits of data */
82		} id_ip;
83		u_int32_t id_mask;
84		u_int8_t id_data[1];
85	} icmp_dun;
86#define	icmp_otime	icmp_dun.id_ts.its_otime
87#define	icmp_rtime	icmp_dun.id_ts.its_rtime
88#define	icmp_ttime	icmp_dun.id_ts.its_ttime
89#define	icmp_ip		icmp_dun.id_ip.idi_ip
90#define	icmp_mask	icmp_dun.id_mask
91#define	icmp_data	icmp_dun.id_data
92};
93
94#define ICMP_MPLS_EXT_EXTRACT_VERSION(x) (((x)&0xf0)>>4)
95#define ICMP_MPLS_EXT_VERSION 2
96
97/*
98 * Lower bounds on packet lengths for various types.
99 * For the error advice packets must first insure that the
100 * packet is large enought to contain the returned ip header.
101 * Only then can we do the check to see if 64 bits of packet
102 * data have been returned, since we need to check the returned
103 * ip header length.
104 */
105#define	ICMP_MINLEN	8				/* abs minimum */
106#define ICMP_EXTD_MINLEN (156 - sizeof (struct ip))     /* draft-bonica-internet-icmp-08 */
107#define	ICMP_TSLEN	(8 + 3 * sizeof (u_int32_t))	/* timestamp */
108#define	ICMP_MASKLEN	12				/* address mask */
109#define	ICMP_ADVLENMIN	(8 + sizeof (struct ip) + 8)	/* min */
110#define	ICMP_ADVLEN(p)	(8 + (IP_HL(&(p)->icmp_ip) << 2) + 8)
111	/* N.B.: must separately check that ip_hl >= 5 */
112
113/*
114 * Definition of type and code field values.
115 */
116#define	ICMP_ECHOREPLY		0		/* echo reply */
117#define	ICMP_UNREACH		3		/* dest unreachable, codes: */
118#define		ICMP_UNREACH_NET	0		/* bad net */
119#define		ICMP_UNREACH_HOST	1		/* bad host */
120#define		ICMP_UNREACH_PROTOCOL	2		/* bad protocol */
121#define		ICMP_UNREACH_PORT	3		/* bad port */
122#define		ICMP_UNREACH_NEEDFRAG	4		/* IP_DF caused drop */
123#define		ICMP_UNREACH_SRCFAIL	5		/* src route failed */
124#define		ICMP_UNREACH_NET_UNKNOWN 6		/* unknown net */
125#define		ICMP_UNREACH_HOST_UNKNOWN 7		/* unknown host */
126#define		ICMP_UNREACH_ISOLATED	8		/* src host isolated */
127#define		ICMP_UNREACH_NET_PROHIB	9		/* prohibited access */
128#define		ICMP_UNREACH_HOST_PROHIB 10		/* ditto */
129#define		ICMP_UNREACH_TOSNET	11		/* bad tos for net */
130#define		ICMP_UNREACH_TOSHOST	12		/* bad tos for host */
131#define	ICMP_SOURCEQUENCH	4		/* packet lost, slow down */
132#define	ICMP_REDIRECT		5		/* shorter route, codes: */
133#define		ICMP_REDIRECT_NET	0		/* for network */
134#define		ICMP_REDIRECT_HOST	1		/* for host */
135#define		ICMP_REDIRECT_TOSNET	2		/* for tos and net */
136#define		ICMP_REDIRECT_TOSHOST	3		/* for tos and host */
137#define	ICMP_ECHO		8		/* echo service */
138#define	ICMP_ROUTERADVERT	9		/* router advertisement */
139#define	ICMP_ROUTERSOLICIT	10		/* router solicitation */
140#define	ICMP_TIMXCEED		11		/* time exceeded, code: */
141#define		ICMP_TIMXCEED_INTRANS	0		/* ttl==0 in transit */
142#define		ICMP_TIMXCEED_REASS	1		/* ttl==0 in reass */
143#define	ICMP_PARAMPROB		12		/* ip header bad */
144#define		ICMP_PARAMPROB_OPTABSENT 1		/* req. opt. absent */
145#define	ICMP_TSTAMP		13		/* timestamp request */
146#define	ICMP_TSTAMPREPLY	14		/* timestamp reply */
147#define	ICMP_IREQ		15		/* information request */
148#define	ICMP_IREQREPLY		16		/* information reply */
149#define	ICMP_MASKREQ		17		/* address mask request */
150#define	ICMP_MASKREPLY		18		/* address mask reply */
151
152#define	ICMP_MAXTYPE		18
153
154#define	ICMP_INFOTYPE(type) \
155	((type) == ICMP_ECHOREPLY || (type) == ICMP_ECHO || \
156	(type) == ICMP_ROUTERADVERT || (type) == ICMP_ROUTERSOLICIT || \
157	(type) == ICMP_TSTAMP || (type) == ICMP_TSTAMPREPLY || \
158	(type) == ICMP_IREQ || (type) == ICMP_IREQREPLY || \
159	(type) == ICMP_MASKREQ || (type) == ICMP_MASKREPLY)
160#define	ICMP_MPLS_EXT_TYPE(type) \
161	((type) == ICMP_UNREACH || \
162         (type) == ICMP_TIMXCEED || \
163         (type) == ICMP_PARAMPROB)
164/* rfc1700 */
165#ifndef ICMP_UNREACH_NET_UNKNOWN
166#define ICMP_UNREACH_NET_UNKNOWN	6	/* destination net unknown */
167#endif
168#ifndef ICMP_UNREACH_HOST_UNKNOWN
169#define ICMP_UNREACH_HOST_UNKNOWN	7	/* destination host unknown */
170#endif
171#ifndef ICMP_UNREACH_ISOLATED
172#define ICMP_UNREACH_ISOLATED		8	/* source host isolated */
173#endif
174#ifndef ICMP_UNREACH_NET_PROHIB
175#define ICMP_UNREACH_NET_PROHIB		9	/* admin prohibited net */
176#endif
177#ifndef ICMP_UNREACH_HOST_PROHIB
178#define ICMP_UNREACH_HOST_PROHIB	10	/* admin prohibited host */
179#endif
180#ifndef ICMP_UNREACH_TOSNET
181#define ICMP_UNREACH_TOSNET		11	/* tos prohibited net */
182#endif
183#ifndef ICMP_UNREACH_TOSHOST
184#define ICMP_UNREACH_TOSHOST		12	/* tos prohibited host */
185#endif
186
187/* rfc1716 */
188#ifndef ICMP_UNREACH_FILTER_PROHIB
189#define ICMP_UNREACH_FILTER_PROHIB	13	/* admin prohibited filter */
190#endif
191#ifndef ICMP_UNREACH_HOST_PRECEDENCE
192#define ICMP_UNREACH_HOST_PRECEDENCE	14	/* host precedence violation */
193#endif
194#ifndef ICMP_UNREACH_PRECEDENCE_CUTOFF
195#define ICMP_UNREACH_PRECEDENCE_CUTOFF	15	/* precedence cutoff */
196#endif
197
198/* Most of the icmp types */
199static struct tok icmp2str[] = {
200	{ ICMP_ECHOREPLY,		"echo reply" },
201	{ ICMP_SOURCEQUENCH,		"source quench" },
202	{ ICMP_ECHO,			"echo request" },
203	{ ICMP_ROUTERSOLICIT,		"router solicitation" },
204	{ ICMP_TSTAMP,			"time stamp request" },
205	{ ICMP_TSTAMPREPLY,		"time stamp reply" },
206	{ ICMP_IREQ,			"information request" },
207	{ ICMP_IREQREPLY,		"information reply" },
208	{ ICMP_MASKREQ,			"address mask request" },
209	{ 0,				NULL }
210};
211
212/* Formats for most of the ICMP_UNREACH codes */
213static struct tok unreach2str[] = {
214	{ ICMP_UNREACH_NET,		"net %s unreachable" },
215	{ ICMP_UNREACH_HOST,		"host %s unreachable" },
216	{ ICMP_UNREACH_SRCFAIL,
217	    "%s unreachable - source route failed" },
218	{ ICMP_UNREACH_NET_UNKNOWN,	"net %s unreachable - unknown" },
219	{ ICMP_UNREACH_HOST_UNKNOWN,	"host %s unreachable - unknown" },
220	{ ICMP_UNREACH_ISOLATED,
221	    "%s unreachable - source host isolated" },
222	{ ICMP_UNREACH_NET_PROHIB,
223	    "net %s unreachable - admin prohibited" },
224	{ ICMP_UNREACH_HOST_PROHIB,
225	    "host %s unreachable - admin prohibited" },
226	{ ICMP_UNREACH_TOSNET,
227	    "net %s unreachable - tos prohibited" },
228	{ ICMP_UNREACH_TOSHOST,
229	    "host %s unreachable - tos prohibited" },
230	{ ICMP_UNREACH_FILTER_PROHIB,
231	    "host %s unreachable - admin prohibited filter" },
232	{ ICMP_UNREACH_HOST_PRECEDENCE,
233	    "host %s unreachable - host precedence violation" },
234	{ ICMP_UNREACH_PRECEDENCE_CUTOFF,
235	    "host %s unreachable - precedence cutoff" },
236	{ 0,				NULL }
237};
238
239/* Formats for the ICMP_REDIRECT codes */
240static struct tok type2str[] = {
241	{ ICMP_REDIRECT_NET,		"redirect %s to net %s" },
242	{ ICMP_REDIRECT_HOST,		"redirect %s to host %s" },
243	{ ICMP_REDIRECT_TOSNET,		"redirect-tos %s to net %s" },
244	{ ICMP_REDIRECT_TOSHOST,	"redirect-tos %s to host %s" },
245	{ 0,				NULL }
246};
247
248/* rfc1191 */
249struct mtu_discovery {
250	u_int16_t unused;
251	u_int16_t nexthopmtu;
252};
253
254/* rfc1256 */
255struct ih_rdiscovery {
256	u_int8_t ird_addrnum;
257	u_int8_t ird_addrsiz;
258	u_int16_t ird_lifetime;
259};
260
261struct id_rdiscovery {
262	u_int32_t ird_addr;
263	u_int32_t ird_pref;
264};
265
266/*
267 * draft-bonica-internet-icmp-08
268 *
269 * The Destination Unreachable, Time Exceeded
270 * and Parameter Problem messages are slighly changed as per
271 * the above draft. A new Length field gets added to give
272 * the caller an idea about the length of the piggypacked
273 * IP packet before the MPLS extension header starts.
274 *
275 * The Length field represents length of the padded "original datagram"
276 * field  measured in 32-bit words.
277 *
278 * 0                   1                   2                   3
279 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
280 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
281 * |     Type      |     Code      |          Checksum             |
282 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
283 * |     unused    |    Length     |          unused               |
284 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
285 * |      Internet Header + leading octets of original datagram    |
286 * |                                                               |
287 * |                           //                                  |
288 * |                                                               |
289 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
290 */
291
292struct icmp_ext_t {
293    u_int8_t icmp_type;
294    u_int8_t icmp_code;
295    u_int8_t icmp_checksum[2];
296    u_int8_t icmp_reserved;
297    u_int8_t icmp_length;
298    u_int8_t icmp_reserved2[2];
299    u_int8_t icmp_ext_legacy_header[128]; /* extension header starts 128 bytes after ICMP header */
300    u_int8_t icmp_ext_version_res[2];
301    u_int8_t icmp_ext_checksum[2];
302    u_int8_t icmp_ext_data[1];
303};
304
305struct icmp_mpls_ext_object_header_t {
306    u_int8_t length[2];
307    u_int8_t class_num;
308    u_int8_t ctype;
309};
310
311static const struct tok icmp_mpls_ext_obj_values[] = {
312    { 1, "MPLS Stack Entry" },
313    { 2, "Extended Payload" },
314    { 0, NULL}
315};
316
317/* prototypes */
318const char *icmp_tstamp_print(u_int);
319
320/* print the milliseconds since midnight UTC */
321const char *
322icmp_tstamp_print(u_int tstamp) {
323    u_int msec,sec,min,hrs;
324
325    static char buf[64];
326
327    msec = tstamp % 1000;
328    sec = tstamp / 1000;
329    min = sec / 60; sec -= min * 60;
330    hrs = min / 60; min -= hrs * 60;
331    snprintf(buf, sizeof(buf), "%02u:%02u:%02u.%03u",hrs,min,sec,msec);
332    return buf;
333}
334
335void
336icmp_print(const u_char *bp, u_int plen, const u_char *bp2, int fragmented)
337{
338	char *cp;
339	const struct icmp *dp;
340        const struct icmp_ext_t *ext_dp;
341	const struct ip *ip;
342	const char *str, *fmt;
343	const struct ip *oip;
344	const struct udphdr *ouh;
345        const u_int8_t *obj_tptr;
346        u_int32_t raw_label;
347        const u_char *snapend_save;
348	const struct icmp_mpls_ext_object_header_t *icmp_mpls_ext_object_header;
349	u_int hlen, dport, mtu, obj_tlen, obj_class_num, obj_ctype;
350	char buf[MAXHOSTNAMELEN + 100];
351
352	dp = (struct icmp *)bp;
353        ext_dp = (struct icmp_ext_t *)bp;
354	ip = (struct ip *)bp2;
355	str = buf;
356
357	TCHECK(dp->icmp_code);
358	switch (dp->icmp_type) {
359
360	case ICMP_ECHO:
361	case ICMP_ECHOREPLY:
362		TCHECK(dp->icmp_seq);
363		(void)snprintf(buf, sizeof(buf), "echo %s, id %u, seq %u",
364                               dp->icmp_type == ICMP_ECHO ?
365                               "request" : "reply",
366                               EXTRACT_16BITS(&dp->icmp_id),
367                               EXTRACT_16BITS(&dp->icmp_seq));
368		break;
369
370	case ICMP_UNREACH:
371		TCHECK(dp->icmp_ip.ip_dst);
372		switch (dp->icmp_code) {
373
374		case ICMP_UNREACH_PROTOCOL:
375			TCHECK(dp->icmp_ip.ip_p);
376			(void)snprintf(buf, sizeof(buf),
377			    "%s protocol %d unreachable",
378			    ipaddr_string(&dp->icmp_ip.ip_dst),
379			    dp->icmp_ip.ip_p);
380			break;
381
382		case ICMP_UNREACH_PORT:
383			TCHECK(dp->icmp_ip.ip_p);
384			oip = &dp->icmp_ip;
385			hlen = IP_HL(oip) * 4;
386			ouh = (struct udphdr *)(((u_char *)oip) + hlen);
387			TCHECK(ouh->uh_dport);
388			dport = EXTRACT_16BITS(&ouh->uh_dport);
389			switch (oip->ip_p) {
390
391			case IPPROTO_TCP:
392				(void)snprintf(buf, sizeof(buf),
393					"%s tcp port %s unreachable",
394					ipaddr_string(&oip->ip_dst),
395					tcpport_string(dport));
396				break;
397
398			case IPPROTO_UDP:
399				(void)snprintf(buf, sizeof(buf),
400					"%s udp port %s unreachable",
401					ipaddr_string(&oip->ip_dst),
402					udpport_string(dport));
403				break;
404
405			default:
406				(void)snprintf(buf, sizeof(buf),
407					"%s protocol %d port %d unreachable",
408					ipaddr_string(&oip->ip_dst),
409					oip->ip_p, dport);
410				break;
411			}
412			break;
413
414		case ICMP_UNREACH_NEEDFRAG:
415		    {
416			register const struct mtu_discovery *mp;
417			mp = (struct mtu_discovery *)&dp->icmp_void;
418			mtu = EXTRACT_16BITS(&mp->nexthopmtu);
419			if (mtu) {
420				(void)snprintf(buf, sizeof(buf),
421				    "%s unreachable - need to frag (mtu %d)",
422				    ipaddr_string(&dp->icmp_ip.ip_dst), mtu);
423			} else {
424				(void)snprintf(buf, sizeof(buf),
425				    "%s unreachable - need to frag",
426				    ipaddr_string(&dp->icmp_ip.ip_dst));
427			}
428		    }
429			break;
430
431		default:
432			fmt = tok2str(unreach2str, "#%d %%s unreachable",
433			    dp->icmp_code);
434			(void)snprintf(buf, sizeof(buf), fmt,
435			    ipaddr_string(&dp->icmp_ip.ip_dst));
436			break;
437		}
438		break;
439
440	case ICMP_REDIRECT:
441		TCHECK(dp->icmp_ip.ip_dst);
442		fmt = tok2str(type2str, "redirect-#%d %%s to net %%s",
443		    dp->icmp_code);
444		(void)snprintf(buf, sizeof(buf), fmt,
445		    ipaddr_string(&dp->icmp_ip.ip_dst),
446		    ipaddr_string(&dp->icmp_gwaddr));
447		break;
448
449	case ICMP_ROUTERADVERT:
450	    {
451		register const struct ih_rdiscovery *ihp;
452		register const struct id_rdiscovery *idp;
453		u_int lifetime, num, size;
454
455		(void)snprintf(buf, sizeof(buf), "router advertisement");
456		cp = buf + strlen(buf);
457
458		ihp = (struct ih_rdiscovery *)&dp->icmp_void;
459		TCHECK(*ihp);
460		(void)strncpy(cp, " lifetime ", sizeof(buf) - (cp - buf));
461		cp = buf + strlen(buf);
462		lifetime = EXTRACT_16BITS(&ihp->ird_lifetime);
463		if (lifetime < 60) {
464			(void)snprintf(cp, sizeof(buf) - (cp - buf), "%u",
465			    lifetime);
466		} else if (lifetime < 60 * 60) {
467			(void)snprintf(cp, sizeof(buf) - (cp - buf), "%u:%02u",
468			    lifetime / 60, lifetime % 60);
469		} else {
470			(void)snprintf(cp, sizeof(buf) - (cp - buf),
471			    "%u:%02u:%02u",
472			    lifetime / 3600,
473			    (lifetime % 3600) / 60,
474			    lifetime % 60);
475		}
476		cp = buf + strlen(buf);
477
478		num = ihp->ird_addrnum;
479		(void)snprintf(cp, sizeof(buf) - (cp - buf), " %d:", num);
480		cp = buf + strlen(buf);
481
482		size = ihp->ird_addrsiz;
483		if (size != 2) {
484			(void)snprintf(cp, sizeof(buf) - (cp - buf),
485			    " [size %d]", size);
486			break;
487		}
488		idp = (struct id_rdiscovery *)&dp->icmp_data;
489		while (num-- > 0) {
490			TCHECK(*idp);
491			(void)snprintf(cp, sizeof(buf) - (cp - buf), " {%s %u}",
492			    ipaddr_string(&idp->ird_addr),
493			    EXTRACT_32BITS(&idp->ird_pref));
494			cp = buf + strlen(buf);
495			++idp;
496		}
497	    }
498		break;
499
500	case ICMP_TIMXCEED:
501		TCHECK(dp->icmp_ip.ip_dst);
502		switch (dp->icmp_code) {
503
504		case ICMP_TIMXCEED_INTRANS:
505			str = "time exceeded in-transit";
506			break;
507
508		case ICMP_TIMXCEED_REASS:
509			str = "ip reassembly time exceeded";
510			break;
511
512		default:
513			(void)snprintf(buf, sizeof(buf), "time exceeded-#%d",
514			    dp->icmp_code);
515			break;
516		}
517		break;
518
519	case ICMP_PARAMPROB:
520		if (dp->icmp_code)
521			(void)snprintf(buf, sizeof(buf),
522			    "parameter problem - code %d", dp->icmp_code);
523		else {
524			TCHECK(dp->icmp_pptr);
525			(void)snprintf(buf, sizeof(buf),
526			    "parameter problem - octet %d", dp->icmp_pptr);
527		}
528		break;
529
530	case ICMP_MASKREPLY:
531		TCHECK(dp->icmp_mask);
532		(void)snprintf(buf, sizeof(buf), "address mask is 0x%08x",
533		    EXTRACT_32BITS(&dp->icmp_mask));
534		break;
535
536	case ICMP_TSTAMP:
537		TCHECK(dp->icmp_seq);
538		(void)snprintf(buf, sizeof(buf),
539		    "time stamp query id %u seq %u",
540		    EXTRACT_16BITS(&dp->icmp_id),
541		    EXTRACT_16BITS(&dp->icmp_seq));
542		break;
543
544	case ICMP_TSTAMPREPLY:
545		TCHECK(dp->icmp_ttime);
546		(void)snprintf(buf, sizeof(buf),
547		    "time stamp reply id %u seq %u: org %s",
548                               EXTRACT_16BITS(&dp->icmp_id),
549                               EXTRACT_16BITS(&dp->icmp_seq),
550                               icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_otime)));
551
552                (void)snprintf(buf+strlen(buf),sizeof(buf)-strlen(buf),", recv %s",
553                         icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_rtime)));
554                (void)snprintf(buf+strlen(buf),sizeof(buf)-strlen(buf),", xmit %s",
555                         icmp_tstamp_print(EXTRACT_32BITS(&dp->icmp_ttime)));
556                break;
557
558	default:
559		str = tok2str(icmp2str, "type-#%d", dp->icmp_type);
560		break;
561	}
562	(void)printf("ICMP %s, length %u", str, plen);
563	if (vflag && !fragmented) { /* don't attempt checksumming if this is a frag */
564		u_int16_t sum, icmp_sum;
565		if (TTEST2(*bp, plen)) {
566			sum = in_cksum((u_short*)dp, plen, 0);
567			if (sum != 0) {
568				icmp_sum = EXTRACT_16BITS(&dp->icmp_cksum);
569				(void)printf(" (wrong icmp cksum %x (->%x)!)",
570					     icmp_sum,
571					     in_cksum_shouldbe(icmp_sum, sum));
572			}
573		}
574	}
575
576        /*
577         * print the remnants of the IP packet.
578         * save the snaplength as this may get overidden in the IP printer.
579         */
580	if (vflag >= 1 && !ICMP_INFOTYPE(dp->icmp_type)) {
581		bp += 8;
582		(void)printf("\n\t");
583		ip = (struct ip *)bp;
584		snaplen = snapend - bp;
585                snapend_save = snapend;
586		ip_print(gndo, bp, EXTRACT_16BITS(&ip->ip_len));
587                snapend = snapend_save;
588	}
589
590        /*
591         * Attempt to decode the MPLS extensions only for some ICMP types.
592         */
593        if (vflag >= 1 && plen > ICMP_EXTD_MINLEN && ICMP_MPLS_EXT_TYPE(dp->icmp_type)) {
594
595            TCHECK(*ext_dp);
596
597            /*
598             * Check first if the mpls extension header shows a non-zero length.
599             * If the length field is not set then silently verify the checksum
600             * to check if an extension header is present. This is expedient,
601             * however not all implementations set the length field proper.
602             */
603            if (!ext_dp->icmp_length &&
604                in_cksum((const u_short *)&ext_dp->icmp_ext_version_res,
605                         plen - ICMP_EXTD_MINLEN, 0)) {
606                return;
607            }
608
609            printf("\n\tMPLS extension v%u",
610                   ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)));
611
612            /*
613             * Sanity checking of the header.
614             */
615            if (ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)) !=
616                ICMP_MPLS_EXT_VERSION) {
617                printf(" packet not supported");
618                return;
619            }
620
621            hlen = plen - ICMP_EXTD_MINLEN;
622            printf(", checksum 0x%04x (%scorrect), length %u",
623                   EXTRACT_16BITS(ext_dp->icmp_ext_checksum),
624                   in_cksum((const u_short *)&ext_dp->icmp_ext_version_res,
625                            plen - ICMP_EXTD_MINLEN, 0) ? "in" : "",
626                   hlen);
627
628            hlen -= 4; /* subtract common header size */
629            obj_tptr = (u_int8_t *)ext_dp->icmp_ext_data;
630
631            while (hlen > sizeof(struct icmp_mpls_ext_object_header_t)) {
632
633                icmp_mpls_ext_object_header = (struct icmp_mpls_ext_object_header_t *)obj_tptr;
634                TCHECK(*icmp_mpls_ext_object_header);
635                obj_tlen = EXTRACT_16BITS(icmp_mpls_ext_object_header->length);
636                obj_class_num = icmp_mpls_ext_object_header->class_num;
637                obj_ctype = icmp_mpls_ext_object_header->ctype;
638                obj_tptr += sizeof(struct icmp_mpls_ext_object_header_t);
639
640                printf("\n\t  %s Object (%u), Class-Type: %u, length %u",
641                       tok2str(icmp_mpls_ext_obj_values,"unknown",obj_class_num),
642                       obj_class_num,
643                       obj_ctype,
644                       obj_tlen);
645
646                hlen-=sizeof(struct icmp_mpls_ext_object_header_t); /* length field includes tlv header */
647
648                /* infinite loop protection */
649                if ((obj_class_num == 0) ||
650                    (obj_tlen < sizeof(struct icmp_mpls_ext_object_header_t))) {
651                    return;
652                }
653                obj_tlen-=sizeof(struct icmp_mpls_ext_object_header_t);
654
655                switch (obj_class_num) {
656                case 1:
657                    switch(obj_ctype) {
658                    case 1:
659                        TCHECK2(*obj_tptr, 4);
660                        raw_label = EXTRACT_32BITS(obj_tptr);
661                        printf("\n\t    label %u, exp %u", MPLS_LABEL(raw_label), MPLS_EXP(raw_label));
662                        if (MPLS_STACK(raw_label))
663                            printf(", [S]");
664                        printf(", ttl %u", MPLS_TTL(raw_label));
665                        break;
666                    default:
667                        print_unknown_data(obj_tptr, "\n\t    ", obj_tlen);
668                    }
669                    break;
670
671               /*
672                *  FIXME those are the defined objects that lack a decoder
673                *  you are welcome to contribute code ;-)
674                */
675                case 2:
676                default:
677                    print_unknown_data(obj_tptr, "\n\t    ", obj_tlen);
678                    break;
679                }
680                if (hlen < obj_tlen)
681                    break;
682                hlen -= obj_tlen;
683                obj_tptr += obj_tlen;
684            }
685        }
686
687	return;
688trunc:
689	fputs("[|icmp]", stdout);
690}
691