xref: /netbsd-src/usr.sbin/traceroute/traceroute.c (revision 220b5c059a84c51ea44107ea8951a57ffaecdc8c)
1 /*	$NetBSD: traceroute.c,v 1.44 2001/11/04 23:14:35 atatat Exp $	*/
2 
3 /*
4  * Copyright (c) 1988, 1989, 1991, 1994, 1995, 1996, 1997
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that: (1) source code distributions
9  * retain the above copyright notice and this paragraph in its entirety, (2)
10  * distributions including binary code include the above copyright notice and
11  * this paragraph in its entirety in the documentation or other materials
12  * provided with the distribution, and (3) all advertising materials mentioning
13  * features or use of this software display the following acknowledgement:
14  * ``This product includes software developed by the University of California,
15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
16  * the University nor the names of its contributors may be used to endorse
17  * or promote products derived from this software without specific prior
18  * written permission.
19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
22  */
23 
24 #include <sys/cdefs.h>
25 #ifndef lint
26 #if 0
27 static const char rcsid[] =
28     "@(#)Header: traceroute.c,v 1.49 97/06/13 02:30:23 leres Exp  (LBL)";
29 #else
30 __COPYRIGHT("@(#) Copyright (c) 1988, 1989, 1991, 1994, 1995, 1996, 1997\n\
31 The Regents of the University of California.  All rights reserved.\n");
32 __RCSID("$NetBSD: traceroute.c,v 1.44 2001/11/04 23:14:35 atatat Exp $");
33 #endif
34 #endif
35 
36 /*
37  * traceroute host  - trace the route ip packets follow going to "host".
38  *
39  * Attempt to trace the route an ip packet would follow to some
40  * internet host.  We find out intermediate hops by launching probe
41  * packets with a small ttl (time to live) then listening for an
42  * icmp "time exceeded" reply from a gateway.  We start our probes
43  * with a ttl of one and increase by one until we get an icmp "port
44  * unreachable" (which means we got to "host") or hit a max (which
45  * defaults to 30 hops & can be changed with the -m flag).  Three
46  * probes (change with -q flag) are sent at each ttl setting and a
47  * line is printed showing the ttl, address of the gateway and
48  * round trip time of each probe.  If the probe answers come from
49  * different gateways, the address of each responding system will
50  * be printed.  If there is no response within a 5 sec. timeout
51  * interval (changed with the -w flag), a "*" is printed for that
52  * probe.
53  *
54  * Probe packets are UDP format.  We don't want the destination
55  * host to process them so the destination port is set to an
56  * unlikely value (if some clod on the destination is using that
57  * value, it can be changed with the -p flag).
58  *
59  * A sample use might be:
60  *
61  *     [yak 71]% traceroute nis.nsf.net.
62  *     traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
63  *      1  helios.ee.lbl.gov (128.3.112.1)  19 ms  19 ms  0 ms
64  *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
65  *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
66  *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  39 ms
67  *      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  39 ms  39 ms  39 ms
68  *      6  128.32.197.4 (128.32.197.4)  40 ms  59 ms  59 ms
69  *      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  59 ms
70  *      8  129.140.70.13 (129.140.70.13)  99 ms  99 ms  80 ms
71  *      9  129.140.71.6 (129.140.71.6)  139 ms  239 ms  319 ms
72  *     10  129.140.81.7 (129.140.81.7)  220 ms  199 ms  199 ms
73  *     11  nic.merit.edu (35.1.1.48)  239 ms  239 ms  239 ms
74  *
75  * Note that lines 2 & 3 are the same.  This is due to a buggy
76  * kernel on the 2nd hop system -- lbl-csam.arpa -- that forwards
77  * packets with a zero ttl.
78  *
79  * A more interesting example is:
80  *
81  *     [yak 72]% traceroute allspice.lcs.mit.edu.
82  *     traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
83  *      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
84  *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  19 ms  19 ms
85  *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  19 ms
86  *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  19 ms  39 ms  39 ms
87  *      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  20 ms  39 ms  39 ms
88  *      6  128.32.197.4 (128.32.197.4)  59 ms  119 ms  39 ms
89  *      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  39 ms
90  *      8  129.140.70.13 (129.140.70.13)  80 ms  79 ms  99 ms
91  *      9  129.140.71.6 (129.140.71.6)  139 ms  139 ms  159 ms
92  *     10  129.140.81.7 (129.140.81.7)  199 ms  180 ms  300 ms
93  *     11  129.140.72.17 (129.140.72.17)  300 ms  239 ms  239 ms
94  *     12  * * *
95  *     13  128.121.54.72 (128.121.54.72)  259 ms  499 ms  279 ms
96  *     14  * * *
97  *     15  * * *
98  *     16  * * *
99  *     17  * * *
100  *     18  ALLSPICE.LCS.MIT.EDU (18.26.0.115)  339 ms  279 ms  279 ms
101  *
102  * (I start to see why I'm having so much trouble with mail to
103  * MIT.)  Note that the gateways 12, 14, 15, 16 & 17 hops away
104  * either don't send ICMP "time exceeded" messages or send them
105  * with a ttl too small to reach us.  14 - 17 are running the
106  * MIT C Gateway code that doesn't send "time exceeded"s.  God
107  * only knows what's going on with 12.
108  *
109  * The silent gateway 12 in the above may be the result of a bug in
110  * the 4.[23]BSD network code (and its derivatives):  4.x (x <= 3)
111  * sends an unreachable message using whatever ttl remains in the
112  * original datagram.  Since, for gateways, the remaining ttl is
113  * zero, the icmp "time exceeded" is guaranteed to not make it back
114  * to us.  The behavior of this bug is slightly more interesting
115  * when it appears on the destination system:
116  *
117  *      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
118  *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  39 ms
119  *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  39 ms  19 ms
120  *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  19 ms
121  *      5  ccn-nerif35.Berkeley.EDU (128.32.168.35)  39 ms  39 ms  39 ms
122  *      6  csgw.Berkeley.EDU (128.32.133.254)  39 ms  59 ms  39 ms
123  *      7  * * *
124  *      8  * * *
125  *      9  * * *
126  *     10  * * *
127  *     11  * * *
128  *     12  * * *
129  *     13  rip.Berkeley.EDU (128.32.131.22)  59 ms !  39 ms !  39 ms !
130  *
131  * Notice that there are 12 "gateways" (13 is the final
132  * destination) and exactly the last half of them are "missing".
133  * What's really happening is that rip (a Sun-3 running Sun OS3.5)
134  * is using the ttl from our arriving datagram as the ttl in its
135  * icmp reply.  So, the reply will time out on the return path
136  * (with no notice sent to anyone since icmp's aren't sent for
137  * icmp's) until we probe with a ttl that's at least twice the path
138  * length.  I.e., rip is really only 7 hops away.  A reply that
139  * returns with a ttl of 1 is a clue this problem exists.
140  * Traceroute prints a "!" after the time if the ttl is <= 1.
141  * Since vendors ship a lot of obsolete (DEC's Ultrix, Sun 3.x) or
142  * non-standard (HPUX) software, expect to see this problem
143  * frequently and/or take care picking the target host of your
144  * probes.
145  *
146  * Other possible annotations after the time are !H, !N, !P (got a host,
147  * network or protocol unreachable, respectively), !S or !F (source
148  * route failed or fragmentation needed -- neither of these should
149  * ever occur and the associated gateway is busted if you see one).  If
150  * almost all the probes result in some kind of unreachable, traceroute
151  * will give up and exit.
152  *
153  * Notes
154  * -----
155  * This program must be run by root or be setuid.  (I suggest that
156  * you *don't* make it setuid -- casual use could result in a lot
157  * of unnecessary traffic on our poor, congested nets.)
158  *
159  * This program requires a kernel mod that does not appear in any
160  * system available from Berkeley:  A raw ip socket using proto
161  * IPPROTO_RAW must interpret the data sent as an ip datagram (as
162  * opposed to data to be wrapped in a ip datagram).  See the README
163  * file that came with the source to this program for a description
164  * of the mods I made to /sys/netinet/raw_ip.c.  Your mileage may
165  * vary.  But, again, ANY 4.x (x < 4) BSD KERNEL WILL HAVE TO BE
166  * MODIFIED TO RUN THIS PROGRAM.
167  *
168  * The udp port usage may appear bizarre (well, ok, it is bizarre).
169  * The problem is that an icmp message only contains 8 bytes of
170  * data from the original datagram.  8 bytes is the size of a udp
171  * header so, if we want to associate replies with the original
172  * datagram, the necessary information must be encoded into the
173  * udp header (the ip id could be used but there's no way to
174  * interlock with the kernel's assignment of ip id's and, anyway,
175  * it would have taken a lot more kernel hacking to allow this
176  * code to set the ip id).  So, to allow two or more users to
177  * use traceroute simultaneously, we use this task's pid as the
178  * source port (the high bit is set to move the port number out
179  * of the "likely" range).  To keep track of which probe is being
180  * replied to (so times and/or hop counts don't get confused by a
181  * reply that was delayed in transit), we increment the destination
182  * port number before each probe.
183  *
184  * Don't use this as a coding example.  I was trying to find a
185  * routing problem and this code sort-of popped out after 48 hours
186  * without sleep.  I was amazed it ever compiled, much less ran.
187  *
188  * I stole the idea for this program from Steve Deering.  Since
189  * the first release, I've learned that had I attended the right
190  * IETF working group meetings, I also could have stolen it from Guy
191  * Almes or Matt Mathis.  I don't know (or care) who came up with
192  * the idea first.  I envy the originators' perspicacity and I'm
193  * glad they didn't keep the idea a secret.
194  *
195  * Tim Seaver, Ken Adelman and C. Philip Wood provided bug fixes and/or
196  * enhancements to the original distribution.
197  *
198  * I've hacked up a round-trip-route version of this that works by
199  * sending a loose-source-routed udp datagram through the destination
200  * back to yourself.  Unfortunately, SO many gateways botch source
201  * routing, the thing is almost worthless.  Maybe one day...
202  *
203  *  -- Van Jacobson (van@ee.lbl.gov)
204  *     Tue Dec 20 03:50:13 PST 1988
205  */
206 
207 #include <sys/param.h>
208 #include <sys/file.h>
209 #include <sys/ioctl.h>
210 #ifdef HAVE_SYS_SELECT_H
211 #include <sys/select.h>
212 #endif
213 #include <sys/socket.h>
214 #include <sys/time.h>
215 
216 #include <netinet/in_systm.h>
217 #include <netinet/in.h>
218 #include <netinet/ip.h>
219 #include <netinet/ip_var.h>
220 #include <netinet/ip_icmp.h>
221 #include <netinet/udp.h>
222 #include <netinet/udp_var.h>
223 
224 #include <arpa/inet.h>
225 
226 #include <ctype.h>
227 #include <errno.h>
228 #ifdef HAVE_MALLOC_H
229 #include <malloc.h>
230 #endif
231 #include <memory.h>
232 #include <netdb.h>
233 #include <stdio.h>
234 #include <stdlib.h>
235 #include <string.h>
236 #include <unistd.h>
237 #ifdef IPSEC
238 #include <net/route.h>
239 #include <netinet6/ipsec.h>
240 #endif
241 
242 #include "gnuc.h"
243 #ifdef HAVE_OS_PROTO_H
244 #include "os-proto.h"
245 #endif
246 
247 #include "ifaddrlist.h"
248 #include "savestr.h"
249 #include "as.h"
250 
251 /* Maximum number of gateways (include room for one noop) */
252 #define NGATEWAYS ((int)((MAX_IPOPTLEN - IPOPT_MINOFF - 1) / sizeof(u_int32_t)))
253 
254 #ifndef MAXHOSTNAMELEN
255 #define MAXHOSTNAMELEN	64
256 #endif
257 
258 #define Fprintf (void)fprintf
259 #define Printf (void)printf
260 
261 /* Host name and address list */
262 struct hostinfo {
263 	char *name;
264 	int n;
265 	u_int32_t *addrs;
266 };
267 
268 /* Data section of the probe packet */
269 struct outdata {
270 	u_char seq;		/* sequence number of this packet */
271 	u_char ttl;		/* ttl packet left with */
272 	struct timeval tv;	/* time packet left */
273 };
274 
275 u_char	packet[512];		/* last inbound (icmp) packet */
276 
277 struct ip *outip;		/* last output (udp) packet */
278 struct udphdr *outudp;		/* last output (udp) packet */
279 void *outmark;			/* packed location of struct outdata */
280 struct outdata outsetup;	/* setup and copy for alignment */
281 
282 struct icmp *outicmp;		/* last output (icmp) packet */
283 
284 /* loose source route gateway list (including room for final destination) */
285 u_int32_t gwlist[NGATEWAYS + 1];
286 
287 int s;				/* receive (icmp) socket file descriptor */
288 int sndsock;			/* send (udp/icmp) socket file descriptor */
289 
290 struct sockaddr whereto;	/* Who to try to reach */
291 struct sockaddr_in wherefrom;	/* Who we are */
292 int packlen;			/* total length of packet */
293 int minpacket;			/* min ip packet size */
294 int maxpacket = 32 * 1024;	/* max ip packet size */
295 int printed_ttl = 0;
296 
297 char *prog;
298 char *source;
299 char *hostname;
300 char *device;
301 
302 int nprobes = 3;
303 int max_ttl = 30;
304 int first_ttl = 1;
305 u_short ident;
306 u_short port = 32768 + 666;	/* start udp dest port # for probe packets */
307 
308 int options;			/* socket options */
309 int verbose;
310 int waittime = 5;		/* time to wait for response (in seconds) */
311 int nflag;			/* print addresses numerically */
312 int dump;
313 int as_path;			/* print as numbers for each hop */
314 char *as_server = NULL;
315 void *asn;
316 int useicmp;			/* use icmp echo instead of udp packets */
317 #ifdef CANT_HACK_CKSUM
318 int docksum = 0;		/* don't calculate checksums */
319 #else
320 int docksum = 1;		/* calculate checksums */
321 #endif
322 int optlen;			/* length of ip options */
323 
324 int mtus[] = {
325         17914,
326          8166,
327          4464,
328          4352,
329          2048,
330          2002,
331          1536,
332          1500,
333          1492,
334 	 1480,
335 	 1280,
336          1006,
337           576,
338           552,
339           544,
340           512,
341           508,
342           296,
343            68,
344             0
345 };
346 int *mtuptr = &mtus[0];
347 int mtudisc = 0;
348 int nextmtu;   /* from ICMP error, set by packet_ok(), might be 0 */
349 
350 extern int optind;
351 extern int opterr;
352 extern char *optarg;
353 
354 /* Forwards */
355 double	deltaT(struct timeval *, struct timeval *);
356 void	freehostinfo(struct hostinfo *);
357 void	getaddr(u_int32_t *, char *);
358 struct	hostinfo *gethostinfo(char *);
359 u_short	in_cksum(u_short *, int);
360 u_short	in_cksum2(u_short, u_short *, int);
361 char	*inetname(struct in_addr);
362 int	main(int, char **);
363 int	packet_ok(u_char *, int, struct sockaddr_in *, int);
364 char	*pr_type(u_char);
365 void	print(u_char *, int, struct sockaddr_in *);
366 void	resize_packet(void);
367 void	dump_packet(void);
368 void	send_probe(int, int, struct timeval *);
369 void	setsin(struct sockaddr_in *, u_int32_t);
370 int	str2val(const char *, const char *, int, int);
371 void	tvsub(struct timeval *, struct timeval *);
372 __dead	void usage(void);
373 int	wait_for_reply(int, struct sockaddr_in *, struct timeval *);
374 void	frag_err(void);
375 int	find_local_ip(struct sockaddr_in *, struct sockaddr_in *);
376 #ifdef IPSEC
377 #ifdef IPSEC_POLICY_IPSEC
378 int	setpolicy(int so, char *policy);
379 #endif
380 #endif
381 
382 int
383 main(int argc, char **argv)
384 {
385 	register int op, code, n;
386 	register char *cp;
387 	register u_char *outp;
388 	register u_int32_t *ap;
389 	register struct sockaddr_in *from = &wherefrom;
390 	register struct sockaddr_in *to = (struct sockaddr_in *)&whereto;
391 	register struct hostinfo *hi;
392 	int on = 1;
393 	register struct protoent *pe;
394 	register int ttl, probe, i;
395 	register int seq = 0;
396 	int tos = 0, settos = 0, ttl_flag = 0;
397 	register int lsrr = 0;
398 	register u_short off = 0;
399 	struct ifaddrlist *al, *al2;
400 	char errbuf[132];
401 
402 	if ((cp = strrchr(argv[0], '/')) != NULL)
403 		prog = cp + 1;
404 	else
405 		prog = argv[0];
406 
407 	opterr = 0;
408 	while ((op = getopt(argc, argv, "aA:dDFPInlrvxf:g:i:m:p:q:s:t:w:")) != -1)
409 		switch (op) {
410 
411 		case 'a':
412 			as_path = 1;
413 			break;
414 
415 		case 'A':
416 			as_path = 1;
417 			as_server = optarg;
418 			break;
419 
420 		case 'd':
421 			options |= SO_DEBUG;
422 			break;
423 
424 		case 'D':
425 			dump = 1;
426 			break;
427 
428 		case 'f':
429 			first_ttl = str2val(optarg, "first ttl", 1, 255);
430 			break;
431 
432 		case 'F':
433 			off = IP_DF;
434 			break;
435 
436 		case 'g':
437 			if (lsrr >= NGATEWAYS) {
438 				Fprintf(stderr,
439 				    "%s: No more than %d gateways\n",
440 				    prog, NGATEWAYS);
441 				exit(1);
442 			}
443 			getaddr(gwlist + lsrr, optarg);
444 			++lsrr;
445 			break;
446 
447 		case 'i':
448 			device = optarg;
449 			break;
450 
451 		case 'I':
452 			++useicmp;
453 			break;
454 
455 		case 'l':
456 			++ttl_flag;
457 			break;
458 
459 		case 'm':
460 			max_ttl = str2val(optarg, "max ttl", 1, 255);
461 			break;
462 
463 		case 'n':
464 			++nflag;
465 			break;
466 
467 		case 'p':
468 			port = str2val(optarg, "port", 1, -1);
469 			break;
470 
471 		case 'q':
472 			nprobes = str2val(optarg, "nprobes", 1, -1);
473 			break;
474 
475 		case 'r':
476 			options |= SO_DONTROUTE;
477 			break;
478 
479 		case 's':
480 			/*
481 			 * set the ip source address of the outbound
482 			 * probe (e.g., on a multi-homed host).
483 			 */
484 			source = optarg;
485 			break;
486 
487 		case 't':
488 			tos = str2val(optarg, "tos", 0, 255);
489 			++settos;
490 			break;
491 
492 		case 'v':
493 			++verbose;
494 			break;
495 
496 		case 'x':
497 			docksum = (docksum == 0);
498 			break;
499 
500 		case 'w':
501 			waittime = str2val(optarg, "wait time", 2, 24 * 3600);
502 			break;
503 
504 		case 'P':
505 			off = IP_DF;
506 			mtudisc = 1;
507 			break;
508 
509 		default:
510 			usage();
511 		}
512 
513 	if (first_ttl > max_ttl) {
514 		Fprintf(stderr,
515 		    "%s: first ttl (%d) may not be greater than max ttl (%d)\n",
516 		    prog, first_ttl, max_ttl);
517 		exit(1);
518 	}
519 
520 	if (!docksum)
521 		Fprintf(stderr, "%s: Warning: ckecksums disabled\n", prog);
522 
523 	if (lsrr > 0)
524 		optlen = (lsrr + 1) * sizeof(gwlist[0]);
525 	minpacket = sizeof(*outip) + sizeof(struct outdata) + optlen;
526 	if (useicmp)
527 		minpacket += 8;			/* XXX magic number */
528 	else
529 		minpacket += sizeof(*outudp);
530 	if (packlen == 0)
531 		packlen = minpacket;		/* minimum sized packet */
532 	else if (minpacket > packlen || packlen > maxpacket) {
533 		Fprintf(stderr, "%s: packet size must be %d <= s <= %d\n",
534 		    prog, minpacket, maxpacket);
535 		exit(1);
536 	}
537 
538 	if (mtudisc)
539 		packlen = *mtuptr++;
540 
541 	/* Process destination and optional packet size */
542 	switch (argc - optind) {
543 
544 	case 2:
545 		packlen = str2val(argv[optind + 1],
546 		    "packet length", minpacket, -1);
547 		/* Fall through */
548 
549 	case 1:
550 		hostname = argv[optind];
551 		hi = gethostinfo(hostname);
552 		setsin(to, hi->addrs[0]);
553 		if (hi->n > 1)
554 			Fprintf(stderr,
555 		    "%s: Warning: %s has multiple addresses; using %s\n",
556 				prog, hostname, inet_ntoa(to->sin_addr));
557 		hostname = hi->name;
558 		hi->name = NULL;
559 		freehostinfo(hi);
560 		break;
561 
562 	default:
563 		usage();
564 	}
565 
566 #ifdef HAVE_SETLINEBUF
567 	setlinebuf (stdout);
568 #else
569 	setvbuf(stdout, NULL, _IOLBF, 0);
570 #endif
571 
572 	outip = (struct ip *)malloc((unsigned)packlen);
573 	if (outip == NULL) {
574 		Fprintf(stderr, "%s: malloc: %s\n", prog, strerror(errno));
575 		exit(1);
576 	}
577 	memset((char *)outip, 0, packlen);
578 
579 	outip->ip_v = IPVERSION;
580 	if (settos)
581 		outip->ip_tos = tos;
582 #ifdef BYTESWAP_IP_LEN
583 	outip->ip_len = htons(packlen);
584 #else
585 	outip->ip_len = packlen;
586 #endif
587 	outip->ip_off = off;
588 	outp = (u_char *)(outip + 1);
589 #ifdef HAVE_RAW_OPTIONS
590 	if (lsrr > 0) {
591 		register u_char *optlist;
592 
593 		optlist = outp;
594 		outp += optlen;
595 
596 		/* final hop */
597 		gwlist[lsrr] = to->sin_addr.s_addr;
598 
599 		outip->ip_dst.s_addr = gwlist[0];
600 
601 		/* force 4 byte alignment */
602 		optlist[0] = IPOPT_NOP;
603 		/* loose source route option */
604 		optlist[1] = IPOPT_LSRR;
605 		i = lsrr * sizeof(gwlist[0]);
606 		optlist[2] = i + 3;
607 		/* Pointer to LSRR addresses */
608 		optlist[3] = IPOPT_MINOFF;
609 		memcpy(optlist + 4, gwlist + 1, i);
610 	} else
611 #endif
612 		outip->ip_dst = to->sin_addr;
613 
614 	outip->ip_hl = (outp - (u_char *)outip) >> 2;
615 	ident = (getpid() & 0xffff) | 0x8000;
616 	if (useicmp) {
617 		outip->ip_p = IPPROTO_ICMP;
618 
619 		outicmp = (struct icmp *)outp;
620 		outicmp->icmp_type = ICMP_ECHO;
621 		outicmp->icmp_id = htons(ident);
622 
623 		outmark = outp + 8;	/* XXX magic number */
624 	} else {
625 		outip->ip_p = IPPROTO_UDP;
626 
627 		outudp = (struct udphdr *)outp;
628 		outudp->uh_sport = htons(ident);
629 		outudp->uh_ulen =
630 		    htons((u_short)(packlen - (sizeof(*outip) + optlen)));
631 		outmark = outudp + 1;
632 	}
633 
634 	cp = "icmp";
635 	if ((pe = getprotobyname(cp)) == NULL) {
636 		Fprintf(stderr, "%s: unknown protocol %s\n", prog, cp);
637 		exit(1);
638 	}
639 	if ((s = socket(AF_INET, SOCK_RAW, pe->p_proto)) < 0) {
640 		Fprintf(stderr, "%s: icmp socket: %s\n", prog, strerror(errno));
641 		exit(1);
642 	}
643 	if (options & SO_DEBUG)
644 		(void)setsockopt(s, SOL_SOCKET, SO_DEBUG, (char *)&on,
645 		    sizeof(on));
646 	if (options & SO_DONTROUTE)
647 		(void)setsockopt(s, SOL_SOCKET, SO_DONTROUTE, (char *)&on,
648 		    sizeof(on));
649 #ifdef IPSEC
650 #ifdef IPSEC_POLICY_IPSEC
651 	/*
652 	 * do not raise error even if setsockopt fails, kernel may have ipsec
653 	 * turned off.
654 	 */
655 	if (setpolicy(s, "in bypass") < 0)
656 		exit(1);
657 	if (setpolicy(s, "out bypass") < 0)
658 		exit(1);
659 #else
660     {
661 	int level = IPSEC_LEVEL_AVAIL;
662 
663 	(void)setsockopt(s, IPPROTO_IP, IP_ESP_TRANS_LEVEL, &level,
664 		sizeof(level));
665 	(void)setsockopt(s, IPPROTO_IP, IP_ESP_NETWORK_LEVEL, &level,
666 		sizeof(level));
667 #ifdef IP_AUTH_TRANS_LEVEL
668 	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_TRANS_LEVEL, &level,
669 		sizeof(level));
670 #else
671 	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_LEVEL, &level,
672 		sizeof(level));
673 #endif
674 #ifdef IP_AUTH_NETWORK_LEVEL
675 	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_NETWORK_LEVEL, &level,
676 		sizeof(level));
677 #endif
678     }
679 #endif /*IPSEC_POLICY_IPSEC*/
680 #endif /*IPSEC*/
681 
682 #ifndef __hpux
683 	sndsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
684 #else
685 	sndsock = socket(AF_INET, SOCK_RAW,
686 	    useicmp ? IPPROTO_ICMP : IPPROTO_UDP);
687 #endif
688 	if (sndsock < 0) {
689 		Fprintf(stderr, "%s: raw socket: %s\n", prog, strerror(errno));
690 		exit(1);
691 	}
692 
693 #ifdef IPSEC
694 #ifdef IPSEC_POLICY_IPSEC
695 	/*
696 	 * do not raise error even if setsockopt fails, kernel may have ipsec
697 	 * turned off.
698 	 */
699 	if (setpolicy(sndsock, "in bypass") < 0)
700 		exit(1);
701 	if (setpolicy(sndsock, "out bypass") < 0)
702 		exit(1);
703 #else
704     {
705 	int level = IPSEC_LEVEL_BYPASS;
706 
707 	(void)setsockopt(sndsock, IPPROTO_IP, IP_ESP_TRANS_LEVEL, &level,
708 		sizeof(level));
709 	(void)setsockopt(sndsock, IPPROTO_IP, IP_ESP_NETWORK_LEVEL, &level,
710 		sizeof(level));
711 #ifdef IP_AUTH_TRANS_LEVEL
712 	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_TRANS_LEVEL, &level,
713 		sizeof(level));
714 #else
715 	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_LEVEL, &level,
716 		sizeof(level));
717 #endif
718 #ifdef IP_AUTH_NETWORK_LEVEL
719 	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_NETWORK_LEVEL, &level,
720 		sizeof(level));
721 #endif
722     }
723 #endif /*IPSEC_POLICY_IPSEC*/
724 #endif /*IPSEC*/
725 
726 	/* Revert to non-privileged user after opening sockets */
727 	setuid(getuid());
728 
729 #if defined(IP_OPTIONS) && !defined(HAVE_RAW_OPTIONS)
730 	if (lsrr > 0) {
731 		u_char optlist[MAX_IPOPTLEN];
732 
733 		cp = "ip";
734 		if ((pe = getprotobyname(cp)) == NULL) {
735 			Fprintf(stderr, "%s: unknown protocol %s\n", prog, cp);
736 			exit(1);
737 		}
738 
739 		/* final hop */
740 		gwlist[lsrr] = to->sin_addr.s_addr;
741 		++lsrr;
742 
743 		/* force 4 byte alignment */
744 		optlist[0] = IPOPT_NOP;
745 		/* loose source route option */
746 		optlist[1] = IPOPT_LSRR;
747 		i = lsrr * sizeof(gwlist[0]);
748 		optlist[2] = i + 3;
749 		/* Pointer to LSRR addresses */
750 		optlist[3] = IPOPT_MINOFF;
751 		memcpy(optlist + 4, gwlist, i);
752 
753 		if ((setsockopt(sndsock, pe->p_proto, IP_OPTIONS, optlist,
754 		    i + sizeof(gwlist[0]))) < 0) {
755 			Fprintf(stderr, "%s: IP_OPTIONS: %s\n",
756 			    prog, strerror(errno));
757 			exit(1);
758 		    }
759 	}
760 #endif
761 
762 #ifdef SO_SNDBUF
763 	if (setsockopt(sndsock, SOL_SOCKET, SO_SNDBUF, (char *)&packlen,
764 	    sizeof(packlen)) < 0) {
765 		Fprintf(stderr, "%s: SO_SNDBUF: %s\n", prog, strerror(errno));
766 		exit(1);
767 	}
768 #endif
769 #ifdef IP_HDRINCL
770 	if (setsockopt(sndsock, IPPROTO_IP, IP_HDRINCL, (char *)&on,
771 	    sizeof(on)) < 0) {
772 		Fprintf(stderr, "%s: IP_HDRINCL: %s\n", prog, strerror(errno));
773 		exit(1);
774 	}
775 #else
776 #ifdef IP_TOS
777 	if (settos && setsockopt(sndsock, IPPROTO_IP, IP_TOS,
778 	    (char *)&tos, sizeof(tos)) < 0) {
779 		Fprintf(stderr, "%s: setsockopt tos %d: %s\n",
780 		    prog, tos, strerror(errno));
781 		exit(1);
782 	}
783 #endif
784 #endif
785 	if (options & SO_DEBUG)
786 		(void)setsockopt(sndsock, SOL_SOCKET, SO_DEBUG, (char *)&on,
787 		    sizeof(on));
788 	if (options & SO_DONTROUTE)
789 		(void)setsockopt(sndsock, SOL_SOCKET, SO_DONTROUTE, (char *)&on,
790 		    sizeof(on));
791 
792 	/* Get the interface address list */
793 	n = ifaddrlist(&al, errbuf, sizeof errbuf);
794 	al2 = al;
795 	if (n < 0) {
796 		Fprintf(stderr, "%s: ifaddrlist: %s\n", prog, errbuf);
797 		exit(1);
798 	}
799 	if (n == 0) {
800 		Fprintf(stderr,
801 		    "%s: Can't find any network interfaces\n", prog);
802 		exit(1);
803 	}
804 
805 	/* Look for a specific device */
806 	if (device != NULL) {
807 		for (i = n; i > 0; --i, ++al2)
808 			if (strcmp(device, al2->device) == 0)
809 				break;
810 		if (i <= 0) {
811 			Fprintf(stderr, "%s: Can't find interface %s\n",
812 			    prog, device);
813 			exit(1);
814 		}
815 	}
816 
817 	/* Determine our source address */
818 	if (source == NULL) {
819 		/*
820 		 * If a device was specified, use the interface address.
821 		 * Otherwise, use the first interface found.
822 		 * Warn if there are more than one.
823 		 */
824 		setsin(from, al2->addr);
825 		if (n > 1 && device == NULL && !find_local_ip(from, to)) {
826 			Fprintf(stderr,
827 		    "%s: Warning: Multiple interfaces found; using %s @ %s\n",
828 			    prog, inet_ntoa(from->sin_addr), al2->device);
829 		}
830 	} else {
831 		hi = gethostinfo(source);
832 		source = hi->name;
833 		hi->name = NULL;
834 		if (device == NULL) {
835 			/*
836 			 * Use the first interface found.
837 			 * Warn if there are more than one.
838 			 */
839 			setsin(from, hi->addrs[0]);
840 			if (hi->n > 1)
841 				Fprintf(stderr,
842 			"%s: Warning: %s has multiple addresses; using %s\n",
843 				    prog, source, inet_ntoa(from->sin_addr));
844 		} else {
845 			/*
846 			 * Make sure the source specified matches the
847 			 * interface address.
848 			 */
849 			for (i = hi->n, ap = hi->addrs; i > 0; --i, ++ap)
850 				if (*ap == al2->addr)
851 					break;
852 			if (i <= 0) {
853 				Fprintf(stderr,
854 				    "%s: %s is not on interface %s\n",
855 				    prog, source, device);
856 				exit(1);
857 			}
858 			setsin(from, *ap);
859 		}
860 		freehostinfo(hi);
861 	}
862 
863 	/*
864 	 * If not root, make sure source address matches a local interface.
865 	 * (The list of addresses produced by ifaddrlist() automatically
866 	 * excludes interfaces that are marked down and/or loopback.)
867 	 */
868 	if (getuid())  {
869 		al2 = al;
870 		for (i = n; i > 0; --i, ++al2)
871 			if (from->sin_addr.s_addr == al2->addr)
872 			    break;
873 		if (i <= 0) {
874 			Fprintf(stderr, "%s: %s is not a valid local address "
875 			    "and you are not superuser.\n", prog,
876 			    inet_ntoa(from->sin_addr));
877 			exit(1);
878 		}
879 	}
880 
881 	outip->ip_src = from->sin_addr;
882 #ifndef IP_HDRINCL
883 	if (bind(sndsock, (struct sockaddr *)from, sizeof(*from)) < 0) {
884 		Fprintf(stderr, "%s: bind: %s\n",
885 		    prog, strerror(errno));
886 		exit (1);
887 	}
888 #endif
889 
890 	if (as_path) {
891 		asn = as_setup(as_server);
892 		if (asn == NULL) {
893 			Fprintf(stderr, "%s: as_setup failed, AS# lookups disabled\n",
894 				prog);
895 			(void)fflush(stderr);
896 			as_path = 0;
897 		}
898 	}
899 
900 	setuid(getuid());
901 	Fprintf(stderr, "%s to %s (%s)",
902 	    prog, hostname, inet_ntoa(to->sin_addr));
903 	if (source)
904 		Fprintf(stderr, " from %s", source);
905 	Fprintf(stderr, ", %d hops max, %d byte packets\n", max_ttl, packlen);
906 	(void)fflush(stderr);
907 
908 	for (ttl = first_ttl; ttl <= max_ttl; ++ttl) {
909 		u_int32_t lastaddr = 0;
910 		int got_there = 0;
911 		int unreachable = 0;
912 
913 again:
914 		printed_ttl = 0;
915 		for (probe = 0; probe < nprobes; ++probe) {
916 			register int cc;
917 			struct timeval t1, t2;
918 			struct timezone tz;
919 			register struct ip *ip;
920 			(void)gettimeofday(&t1, &tz);
921 			send_probe(++seq, ttl, &t1);
922 			while ((cc = wait_for_reply(s, from, &t1)) != 0) {
923 				(void)gettimeofday(&t2, &tz);
924 				/*
925 				 * Since we'll be receiving all ICMP
926 				 * messages to this host above, we may
927 				 * never end up with cc=0, so we need
928 				 * an additional termination check.
929 				 */
930 				if (t2.tv_sec - t1.tv_sec > waittime) {
931 					cc = 0;
932 					break;
933 				}
934 				i = packet_ok(packet, cc, from, seq);
935 				/* Skip short packet */
936 				if (i == 0)
937 					continue;
938 				if (from->sin_addr.s_addr != lastaddr) {
939 					print(packet, cc, from);
940 					lastaddr = from->sin_addr.s_addr;
941 				}
942 				ip = (struct ip *)packet;
943 				Printf("  %.3f ms", deltaT(&t1, &t2));
944 				if (ttl_flag)
945 					Printf(" (ttl = %d)", ip->ip_ttl);
946 				if (i == -2) {
947 #ifndef ARCHAIC
948 					if (ip->ip_ttl <= 1)
949 						Printf(" !");
950 #endif
951 					++got_there;
952 					break;
953 				}
954 
955 				/* time exceeded in transit */
956 				if (i == -1)
957 					break;
958 				code = i - 1;
959 				switch (code) {
960 
961 				case ICMP_UNREACH_PORT:
962 #ifndef ARCHAIC
963 					if (ip->ip_ttl <= 1)
964 						Printf(" !");
965 #endif
966 					++got_there;
967 					break;
968 
969 				case ICMP_UNREACH_NET:
970 					++unreachable;
971 					Printf(" !N");
972 					break;
973 
974 				case ICMP_UNREACH_HOST:
975 					++unreachable;
976 					Printf(" !H");
977 					break;
978 
979 				case ICMP_UNREACH_PROTOCOL:
980 					++got_there;
981 					Printf(" !P");
982 					break;
983 
984 				case ICMP_UNREACH_NEEDFRAG:
985 					if (mtudisc) {
986 						frag_err();
987 						goto again;
988 					} else {
989 						++unreachable;
990 						Printf(" !F");
991 					}
992 					break;
993 
994 				case ICMP_UNREACH_SRCFAIL:
995 					++unreachable;
996 					Printf(" !S");
997 					break;
998 
999 /* rfc1716 */
1000 #ifndef ICMP_UNREACH_FILTER_PROHIB
1001 #define ICMP_UNREACH_FILTER_PROHIB	13	/* admin prohibited filter */
1002 #endif
1003 				case ICMP_UNREACH_FILTER_PROHIB:
1004 					++unreachable;
1005 					Printf(" !X");
1006 					break;
1007 
1008 				default:
1009 					++unreachable;
1010 					Printf(" !<%d>", code);
1011 					break;
1012 				}
1013 				break;
1014 			}
1015 			if (cc == 0)
1016 				Printf(" *");
1017 			(void)fflush(stdout);
1018 		}
1019 		putchar('\n');
1020 		if (got_there ||
1021 		    (unreachable > 0 && unreachable >= ((nprobes + 1) / 2)))
1022 			break;
1023 	}
1024 
1025 	if (as_path)
1026 		as_shutdown(asn);
1027 
1028 	exit(0);
1029 }
1030 
1031 int
1032 wait_for_reply(register int sock, register struct sockaddr_in *fromp,
1033     register struct timeval *tp)
1034 {
1035 	fd_set *fdsp;
1036 	size_t nfds;
1037 	struct timeval now, wait;
1038 	struct timezone tz;
1039 	register int cc = 0;
1040 	int fromlen = sizeof(*fromp);
1041 	int retval;
1042 
1043 	nfds = howmany(sock + 1, NFDBITS) * sizeof(fd_mask);
1044 	if ((fdsp = malloc(nfds)) == NULL) {
1045 		Fprintf(stderr, "%s: malloc: %s\n", prog, strerror(errno));
1046 		exit(1);
1047 	}
1048 	memset(fdsp, 0, nfds);
1049 	FD_SET(sock, fdsp);
1050 
1051 	wait.tv_sec = tp->tv_sec + waittime;
1052 	wait.tv_usec = tp->tv_usec;
1053 	(void)gettimeofday(&now, &tz);
1054 	tvsub(&wait, &now);
1055 
1056 	retval = select(sock + 1, fdsp, NULL, NULL, &wait);
1057 	free(fdsp);
1058 	if (retval < 0)  {
1059 		/* If we continue, we probably just flood the remote host. */
1060 		Fprintf(stderr, "%s: select: %s\n", prog, strerror(errno));
1061 		exit(1);
1062 	}
1063 	if (retval > 0)  {
1064 		cc = recvfrom(s, (char *)packet, sizeof(packet), 0,
1065 			    (struct sockaddr *)fromp, &fromlen);
1066 	}
1067 
1068 	return(cc);
1069 }
1070 
1071 void
1072 dump_packet()
1073 {
1074 	u_char *p;
1075 	int i;
1076 
1077 	Fprintf(stderr, "packet data:");
1078 
1079 #ifdef __hpux
1080 	for (p = useicmp ? (u_char *)outicmp : (u_char *)outudp, i = 0; i <
1081 	    i < packlen - (sizeof(*outip) + optlen); i++)
1082 #else
1083 	for (p = (u_char *)outip, i = 0; i < packlen; i++)
1084 #endif
1085 	{
1086 		if ((i % 24) == 0)
1087 			Fprintf(stderr, "\n ");
1088 		Fprintf(stderr, " %02x", *p++);
1089 	}
1090 	Fprintf(stderr, "\n");
1091 }
1092 
1093 void
1094 send_probe(register int seq, int ttl, register struct timeval *tp)
1095 {
1096 	register int cc;
1097 	register struct udpiphdr * ui;
1098 	int oldmtu = packlen;
1099 
1100 again:
1101 #ifdef BYTESWAP_IP_LEN
1102 	outip->ip_len = htons(packlen);
1103 #else
1104 	outip->ip_len = packlen;
1105 #endif
1106 	outip->ip_ttl = ttl;
1107 #ifndef __hpux
1108 	outip->ip_id = htons(ident + seq);
1109 #endif
1110 
1111 	/*
1112 	 * In most cases, the kernel will recalculate the ip checksum.
1113 	 * But we must do it anyway so that the udp checksum comes out
1114 	 * right.
1115 	 */
1116 	if (docksum) {
1117 		outip->ip_sum =
1118 		    in_cksum((u_short *)outip, sizeof(*outip) + optlen);
1119 		if (outip->ip_sum == 0)
1120 			outip->ip_sum = 0xffff;
1121 	}
1122 
1123 	/* Payload */
1124 	outsetup.seq = seq;
1125 	outsetup.ttl = ttl;
1126 	outsetup.tv  = *tp;
1127 	memcpy(outmark,&outsetup,sizeof(outsetup));
1128 
1129 	if (useicmp)
1130 		outicmp->icmp_seq = htons(seq);
1131 	else
1132 		outudp->uh_dport = htons(port + seq);
1133 
1134 	/* (We can only do the checksum if we know our ip address) */
1135 	if (docksum) {
1136 		if (useicmp) {
1137 			outicmp->icmp_cksum = 0;
1138 			outicmp->icmp_cksum = in_cksum((u_short *)outicmp,
1139 			    packlen - (sizeof(*outip) + optlen));
1140 			if (outicmp->icmp_cksum == 0)
1141 				outicmp->icmp_cksum = 0xffff;
1142 		} else {
1143 			u_short sum;
1144 			struct {
1145 				struct in_addr src;
1146 				struct in_addr dst;
1147 				u_int8_t zero;
1148 				u_int8_t protocol;
1149 				u_int16_t len;
1150 			} __attribute__((__packed__)) phdr;
1151 
1152 			/* Checksum */
1153 			ui = (struct udpiphdr *)outip;
1154 			memset(&phdr, 0, sizeof(phdr));
1155 			phdr.src = ui->ui_src;
1156 			phdr.dst = ((struct sockaddr_in *)&whereto)->sin_addr;
1157 			phdr.protocol = ui->ui_pr;
1158 			phdr.len = outudp->uh_ulen;
1159 			outudp->uh_sum = 0;
1160 			sum = in_cksum2(0, (u_short *)&phdr, sizeof(phdr));
1161 			sum = in_cksum2(sum, (u_short *)outudp, ntohs(outudp->uh_ulen));
1162 			outudp->uh_sum = ~sum;
1163 			if (outudp->uh_sum == 0)
1164 				outudp->uh_sum = 0xffff;
1165 		}
1166 	}
1167 
1168 	/* XXX undocumented debugging hack */
1169 	if (verbose > 1) {
1170 		register const u_short *sp;
1171 		register int nshorts, i;
1172 
1173 		sp = (u_short *)outip;
1174 		nshorts = (u_int)packlen / sizeof(u_short);
1175 		i = 0;
1176 		Printf("[ %d bytes", packlen);
1177 		while (--nshorts >= 0) {
1178 			if ((i++ % 8) == 0)
1179 				Printf("\n\t");
1180 			Printf(" %04x", ntohs(*sp++));
1181 		}
1182 		if (packlen & 1) {
1183 			if ((i % 8) == 0)
1184 				Printf("\n\t");
1185 			Printf(" %02x", *(u_char *)sp);
1186 		}
1187 		Printf("]\n");
1188 	}
1189 
1190 #if !defined(IP_HDRINCL) && defined(IP_TTL)
1191 	if (setsockopt(sndsock, IPPROTO_IP, IP_TTL,
1192 	    (char *)&ttl, sizeof(ttl)) < 0) {
1193 		Fprintf(stderr, "%s: setsockopt ttl %d: %s\n",
1194 		    prog, ttl, strerror(errno));
1195 		exit(1);
1196 	}
1197 #endif
1198 	if (dump)
1199 		dump_packet();
1200 
1201 #ifdef __hpux
1202 	cc = sendto(sndsock, useicmp ? (char *)outicmp : (char *)outudp,
1203 	    packlen - (sizeof(*outip) + optlen), 0, &whereto, sizeof(whereto));
1204 	if (cc > 0)
1205 		cc += sizeof(*outip) + optlen;
1206 #else
1207 	cc = sendto(sndsock, (char *)outip,
1208 	    packlen, 0, &whereto, sizeof(whereto));
1209 #endif
1210 	if (cc < 0 || cc != packlen)  {
1211 		if (cc < 0) {
1212 			/*
1213 			 * An errno of EMSGSIZE means we're writing too big a
1214 			 * datagram for the interface.  We have to just
1215 			 * decrease the packet size until we find one that
1216 			 * works.
1217 			 *
1218 			 * XXX maybe we should try to read the outgoing if's
1219 			 * mtu?
1220 			 */
1221 			if (errno == EMSGSIZE) {
1222 				packlen = *mtuptr++;
1223 				resize_packet();
1224 				goto again;
1225 			} else
1226 				Fprintf(stderr, "%s: sendto: %s\n",
1227 				    prog, strerror(errno));
1228 		}
1229 
1230 		Printf("%s: wrote %s %d chars, ret=%d\n",
1231 		    prog, hostname, packlen, cc);
1232 		(void)fflush(stdout);
1233 	}
1234 	if (oldmtu != packlen) {
1235 		Printf("message too big, "
1236 		    "trying new MTU = %d\n", packlen);
1237 		printed_ttl = 0;
1238 	}
1239 	if (!printed_ttl) {
1240 		Printf("%2d ", ttl);
1241 		printed_ttl = 1;
1242 	}
1243 
1244 }
1245 
1246 double
1247 deltaT(struct timeval *t1p, struct timeval *t2p)
1248 {
1249 	register double dt;
1250 
1251 	dt = (double)(t2p->tv_sec - t1p->tv_sec) * 1000.0 +
1252 	     (double)(t2p->tv_usec - t1p->tv_usec) / 1000.0;
1253 	return (dt);
1254 }
1255 
1256 /*
1257  * Convert an ICMP "type" field to a printable string.
1258  */
1259 char *
1260 pr_type(register u_char t)
1261 {
1262 	static char *ttab[] = {
1263 	"Echo Reply",	"ICMP 1",	"ICMP 2",	"Dest Unreachable",
1264 	"Source Quench", "Redirect",	"ICMP 6",	"ICMP 7",
1265 	"Echo",		"ICMP 9",	"ICMP 10",	"Time Exceeded",
1266 	"Param Problem", "Timestamp",	"Timestamp Reply", "Info Request",
1267 	"Info Reply"
1268 	};
1269 
1270 	if (t > 16)
1271 		return("OUT-OF-RANGE");
1272 
1273 	return(ttab[t]);
1274 }
1275 
1276 int
1277 packet_ok(register u_char *buf, int cc, register struct sockaddr_in *from,
1278     register int seq)
1279 {
1280 	register struct icmp *icp;
1281 	register u_char type, code;
1282 	register int hlen;
1283 #ifndef ARCHAIC
1284 	register struct ip *ip;
1285 
1286 	ip = (struct ip *) buf;
1287 	hlen = ip->ip_hl << 2;
1288 	if (cc < hlen + ICMP_MINLEN) {
1289 		if (verbose)
1290 			Printf("packet too short (%d bytes) from %s\n", cc,
1291 				inet_ntoa(from->sin_addr));
1292 		return (0);
1293 	}
1294 	cc -= hlen;
1295 	icp = (struct icmp *)(buf + hlen);
1296 #else
1297 	icp = (struct icmp *)buf;
1298 #endif
1299 	type = icp->icmp_type;
1300 	code = icp->icmp_code;
1301 	if ((type == ICMP_TIMXCEED && code == ICMP_TIMXCEED_INTRANS) ||
1302 	    type == ICMP_UNREACH || type == ICMP_ECHOREPLY) {
1303 		register struct ip *hip;
1304 		register struct udphdr *up;
1305 		register struct icmp *hicmp;
1306 
1307 		hip = &icp->icmp_ip;
1308 		hlen = hip->ip_hl << 2;
1309 
1310 		nextmtu = ntohs(icp->icmp_nextmtu);	/* for frag_err() */
1311 
1312 		if (useicmp) {
1313 			/* XXX */
1314 			if (type == ICMP_ECHOREPLY &&
1315 			    icp->icmp_id == htons(ident) &&
1316 			    icp->icmp_seq == htons(seq))
1317 				return (-2);
1318 
1319 			hicmp = (struct icmp *)((u_char *)hip + hlen);
1320 			/* XXX 8 is a magic number */
1321 			if (hlen + 8 <= cc &&
1322 			    hip->ip_p == IPPROTO_ICMP &&
1323 			    hicmp->icmp_id == htons(ident) &&
1324 			    hicmp->icmp_seq == htons(seq))
1325 				return (type == ICMP_TIMXCEED ? -1 : code + 1);
1326 		} else {
1327 			up = (struct udphdr *)((u_char *)hip + hlen);
1328 			/* XXX 8 is a magic number */
1329 			if (hlen + 12 <= cc &&
1330 			    hip->ip_p == IPPROTO_UDP &&
1331 			    up->uh_sport == htons(ident) &&
1332 			    up->uh_dport == htons(port + seq))
1333 				return (type == ICMP_TIMXCEED ? -1 : code + 1);
1334 		}
1335 	}
1336 #ifndef ARCHAIC
1337 	if (verbose) {
1338 		register int i;
1339 		u_int32_t *lp = (u_int32_t *)&icp->icmp_ip;
1340 
1341 		Printf("\n%d bytes from %s to ", cc, inet_ntoa(from->sin_addr));
1342 		Printf("%s: icmp type %d (%s) code %d\n",
1343 		    inet_ntoa(ip->ip_dst), type, pr_type(type), icp->icmp_code);
1344 		for (i = 4; i < cc ; i += sizeof(*lp))
1345 			Printf("%2d: x%8.8x\n", i, *lp++);
1346 	}
1347 #endif
1348 	return(0);
1349 }
1350 
1351 void resize_packet(void)
1352 {
1353 	if (useicmp) {
1354 		outicmp->icmp_cksum = 0;
1355 		outicmp->icmp_cksum = in_cksum((u_short *)outicmp,
1356 		    packlen - (sizeof(*outip) + optlen));
1357 		if (outicmp->icmp_cksum == 0)
1358 			outicmp->icmp_cksum = 0xffff;
1359 	} else {
1360 		outudp->uh_ulen =
1361 		    htons((u_short)(packlen - (sizeof(*outip) + optlen)));
1362 	}
1363 }
1364 
1365 void
1366 print(register u_char *buf, register int cc, register struct sockaddr_in *from)
1367 {
1368 	register struct ip *ip;
1369 	register int hlen;
1370 
1371 	ip = (struct ip *) buf;
1372 	hlen = ip->ip_hl << 2;
1373 	cc -= hlen;
1374 
1375 	if (as_path)
1376 		Printf(" [AS%d]", as_lookup(asn, &from->sin_addr));
1377 
1378 	if (nflag)
1379 		Printf(" %s", inet_ntoa(from->sin_addr));
1380 	else
1381 		Printf(" %s (%s)", inetname(from->sin_addr),
1382 		    inet_ntoa(from->sin_addr));
1383 
1384 	if (verbose)
1385 		Printf(" %d bytes to %s", cc, inet_ntoa (ip->ip_dst));
1386 }
1387 
1388 u_short
1389 in_cksum(u_short *addr, int len)
1390 {
1391 
1392 	return ~in_cksum2(0, addr, len);
1393 }
1394 
1395 /*
1396  * Checksum routine for Internet Protocol family headers (C Version)
1397  */
1398 u_short
1399 in_cksum2(u_short seed, register u_short *addr, register int len)
1400 {
1401 	register int nleft = len;
1402 	register u_short *w = addr;
1403 	register u_short answer;
1404 	register int sum = seed;
1405 
1406 	/*
1407 	 *  Our algorithm is simple, using a 32 bit accumulator (sum),
1408 	 *  we add sequential 16 bit words to it, and at the end, fold
1409 	 *  back all the carry bits from the top 16 bits into the lower
1410 	 *  16 bits.
1411 	 */
1412 	while (nleft > 1)  {
1413 		sum += *w++;
1414 		nleft -= 2;
1415 	}
1416 
1417 	/* mop up an odd byte, if necessary */
1418 	if (nleft == 1)
1419 		sum += *(u_char *)w;
1420 
1421 	/*
1422 	 * add back carry outs from top 16 bits to low 16 bits
1423 	 */
1424 	sum = (sum >> 16) + (sum & 0xffff);	/* add hi 16 to low 16 */
1425 	sum += (sum >> 16);			/* add carry */
1426 	answer = sum;				/* truncate to 16 bits */
1427 	return (answer);
1428 }
1429 
1430 /*
1431  * Subtract 2 timeval structs:  out = out - in.
1432  * Out is assumed to be >= in.
1433  */
1434 void
1435 tvsub(register struct timeval *out, register struct timeval *in)
1436 {
1437 
1438 	if ((out->tv_usec -= in->tv_usec) < 0)   {
1439 		--out->tv_sec;
1440 		out->tv_usec += 1000000;
1441 	}
1442 	out->tv_sec -= in->tv_sec;
1443 }
1444 
1445 /*
1446  * Construct an Internet address representation.
1447  * If the nflag has been supplied, give
1448  * numeric value, otherwise try for symbolic name.
1449  */
1450 char *
1451 inetname(struct in_addr in)
1452 {
1453 	register char *cp;
1454 	register struct hostent *hp;
1455 	static int first = 1;
1456 	static char domain[MAXHOSTNAMELEN + 1], line[MAXHOSTNAMELEN + 1];
1457 
1458 	if (first && !nflag) {
1459 		int rv;
1460 
1461 		first = 0;
1462 		rv = gethostname(domain, sizeof domain);
1463 		domain[sizeof(domain) - 1] = '\0';
1464 		if (rv == 0 && (cp = strchr(domain, '.')) != NULL) {
1465 			(void)strncpy(domain, cp + 1, sizeof(domain) - 1);
1466 		} else
1467 			domain[0] = '\0';
1468 	}
1469 	if (!nflag && in.s_addr != INADDR_ANY) {
1470 		hp = gethostbyaddr((char *)&in, sizeof(in), AF_INET);
1471 		if (hp != NULL) {
1472 			if ((cp = strchr(hp->h_name, '.')) != NULL &&
1473 			    strcmp(cp + 1, domain) == 0)
1474 				*cp = '\0';
1475 			(void)strncpy(line, hp->h_name, sizeof(line) - 1);
1476 			line[sizeof(line) - 1] = '\0';
1477 			return (line);
1478 		}
1479 	}
1480 	return (inet_ntoa(in));
1481 }
1482 
1483 struct hostinfo *
1484 gethostinfo(register char *hostname)
1485 {
1486 	register int n;
1487 	register struct hostent *hp;
1488 	register struct hostinfo *hi;
1489 	register char **p;
1490 	register u_int32_t *ap;
1491 	struct in_addr addr;
1492 
1493 	hi = calloc(1, sizeof(*hi));
1494 	if (hi == NULL) {
1495 		Fprintf(stderr, "%s: calloc %s\n", prog, strerror(errno));
1496 		exit(1);
1497 	}
1498 	if (inet_aton(hostname, &addr) != 0) {
1499 		hi->name = strdup(hostname);
1500 		hi->n = 1;
1501 		hi->addrs = calloc(1, sizeof(hi->addrs[0]));
1502 		if (hi->addrs == NULL) {
1503 			Fprintf(stderr, "%s: calloc %s\n",
1504 			    prog, strerror(errno));
1505 			exit(1);
1506 		}
1507 		hi->addrs[0] = addr.s_addr;
1508 		return (hi);
1509 	}
1510 
1511 	hp = gethostbyname(hostname);
1512 	if (hp == NULL) {
1513 		Fprintf(stderr, "%s: unknown host %s\n", prog, hostname);
1514 		exit(1);
1515 	}
1516 	if (hp->h_addrtype != AF_INET || hp->h_length != 4) {
1517 		Fprintf(stderr, "%s: bad host %s\n", prog, hostname);
1518 		exit(1);
1519 	}
1520 	hi->name = strdup(hp->h_name);
1521 	for (n = 0, p = hp->h_addr_list; *p != NULL; ++n, ++p)
1522 		continue;
1523 	hi->n = n;
1524 	hi->addrs = calloc(n, sizeof(hi->addrs[0]));
1525 	if (hi->addrs == NULL) {
1526 		Fprintf(stderr, "%s: calloc %s\n", prog, strerror(errno));
1527 		exit(1);
1528 	}
1529 	for (ap = hi->addrs, p = hp->h_addr_list; *p != NULL; ++ap, ++p)
1530 		memcpy(ap, *p, sizeof(*ap));
1531 	return (hi);
1532 }
1533 
1534 void
1535 freehostinfo(register struct hostinfo *hi)
1536 {
1537 	if (hi->name != NULL) {
1538 		free(hi->name);
1539 		hi->name = NULL;
1540 	}
1541 	free((char *)hi->addrs);
1542 	free((char *)hi);
1543 }
1544 
1545 void
1546 getaddr(register u_int32_t *ap, register char *hostname)
1547 {
1548 	register struct hostinfo *hi;
1549 
1550 	hi = gethostinfo(hostname);
1551 	*ap = hi->addrs[0];
1552 	freehostinfo(hi);
1553 }
1554 
1555 void
1556 setsin(register struct sockaddr_in *sin, register u_int32_t addr)
1557 {
1558 
1559 	memset(sin, 0, sizeof(*sin));
1560 #ifdef HAVE_SOCKADDR_SA_LEN
1561 	sin->sin_len = sizeof(*sin);
1562 #endif
1563 	sin->sin_family = AF_INET;
1564 	sin->sin_addr.s_addr = addr;
1565 }
1566 
1567 /* String to value with optional min and max. Handles decimal and hex. */
1568 int
1569 str2val(register const char *str, register const char *what,
1570     register int mi, register int ma)
1571 {
1572 	register const char *cp;
1573 	register int val;
1574 	char *ep;
1575 
1576 	if (str[0] == '0' && (str[1] == 'x' || str[1] == 'X')) {
1577 		cp = str + 2;
1578 		val = (int)strtol(cp, &ep, 16);
1579 	} else
1580 		val = (int)strtol(str, &ep, 10);
1581 	if (*ep != '\0') {
1582 		Fprintf(stderr, "%s: \"%s\" bad value for %s \n",
1583 		    prog, str, what);
1584 		exit(1);
1585 	}
1586 	if (val < mi && mi >= 0) {
1587 		if (mi == 0)
1588 			Fprintf(stderr, "%s: %s must be >= %d\n",
1589 			    prog, what, mi);
1590 		else
1591 			Fprintf(stderr, "%s: %s must be > %d\n",
1592 			    prog, what, mi - 1);
1593 		exit(1);
1594 	}
1595 	if (val > ma && ma >= 0) {
1596 		Fprintf(stderr, "%s: %s must be <= %d\n", prog, what, ma);
1597 		exit(1);
1598 	}
1599 	return (val);
1600 }
1601 
1602 __dead void
1603 usage(void)
1604 {
1605 	extern char version[];
1606 
1607 	Fprintf(stderr, "Version %s\n", version);
1608 	Fprintf(stderr, "Usage: %s [-adDFPIlnrvx] [-g gateway] [-i iface] \
1609 [-f first_ttl]\n\t[-m max_ttl] [-p port] [-q nqueries] [-s src_addr] [-t tos]\n\t\
1610 [-w waittime] [-A as_server] host [packetlen]\n",
1611 	    prog);
1612 	exit(1);
1613 }
1614 
1615 /*
1616  * Received ICMP unreachable (fragmentation required and DF set).
1617  * If the ICMP error was from a "new" router, it'll contain the next-hop
1618  * MTU that we should use next.  Otherwise we'll just keep going in the
1619  * mtus[] table, trying until we hit a valid MTU.
1620  */
1621 
1622 
1623 void
1624 frag_err()
1625 {
1626         int i;
1627 
1628         if (nextmtu > 0 && nextmtu < packlen) {
1629                 Printf("\nfragmentation required and DF set, "
1630 		     "next hop MTU = %d\n",
1631                         nextmtu);
1632                 packlen = nextmtu;
1633                 for (i = 0; mtus[i] > 0; i++) {
1634                         if (mtus[i] < nextmtu) {
1635                                 mtuptr = &mtus[i];    /* next one to try */
1636                                 break;
1637                         }
1638                 }
1639         } else {
1640                 Printf("\nfragmentation required and DF set. ");
1641 		if (nextmtu)
1642 			Printf("\nBogus next hop MTU = %d > last MTU = %d. ",
1643 			    nextmtu, packlen);
1644                 packlen = *mtuptr++;
1645 		Printf("Trying new MTU = %d\n", packlen);
1646         }
1647 	resize_packet();
1648 }
1649 
1650 int
1651 find_local_ip(struct sockaddr_in *from, struct sockaddr_in *to)
1652 {
1653 	int sock;
1654 	struct sockaddr_in help;
1655 	int help_len;
1656 
1657 	sock = socket(AF_INET, SOCK_DGRAM, 0);
1658 	if (sock < 0) return (0);
1659 
1660 	help.sin_family = AF_INET;
1661 	/*
1662 	 * At this point the port number doesn't matter
1663 	 * since it only has to be greater than zero.
1664 	 */
1665 	help.sin_port = 42;
1666 	help.sin_addr.s_addr = to->sin_addr.s_addr;
1667 	if (connect(sock, (struct sockaddr *)&help, sizeof(help)) < 0) {
1668 		(void)close(sock);
1669 		return (0);
1670 	}
1671 
1672 	help_len = sizeof(help);
1673 	if (getsockname(sock, (struct sockaddr *)&help, &help_len) < 0 ||
1674 	    help_len != sizeof(help) ||
1675 	    help.sin_addr.s_addr == INADDR_ANY) {
1676 		(void)close(sock);
1677 		return (0);
1678 	}
1679 
1680 	(void)close(sock);
1681 	setsin(from, help.sin_addr.s_addr);
1682 	return (1);
1683 }
1684 
1685 #ifdef IPSEC
1686 #ifdef IPSEC_POLICY_IPSEC
1687 int
1688 setpolicy(so, policy)
1689 	int so;
1690 	char *policy;
1691 {
1692 	char *buf;
1693 
1694 	buf = ipsec_set_policy(policy, strlen(policy));
1695 	if (buf == NULL) {
1696 		Fprintf(stderr, "%s: %s\n", prog, ipsec_strerror());
1697 		return -1;
1698 	}
1699 	(void)setsockopt(so, IPPROTO_IP, IP_IPSEC_POLICY,
1700 		buf, ipsec_get_policylen(buf));
1701 
1702 	free(buf);
1703 
1704 	return 0;
1705 }
1706 #endif
1707 #endif
1708 
1709