xref: /src/usr.sbin/traceroute/traceroute.c

/*	$NetBSD: traceroute.c,v 1.64 2006/05/31 20:22:52 rpaulo Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1991, 1994, 1995, 1996, 1997
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static const char rcsid[] =
    "@(#)Header: traceroute.c,v 1.49 97/06/13 02:30:23 leres Exp  (LBL)";
#else
__COPYRIGHT("@(#) Copyright (c) 1988, 1989, 1991, 1994, 1995, 1996, 1997\n\
The Regents of the University of California.  All rights reserved.\n");
__RCSID("$NetBSD: traceroute.c,v 1.64 2006/05/31 20:22:52 rpaulo Exp $");
#endif
#endif

/*
 * traceroute host  - trace the route ip packets follow going to "host".
 *
 * Attempt to trace the route an ip packet would follow to some
 * internet host.  We find out intermediate hops by launching probe
 * packets with a small ttl (time to live) then listening for an
 * icmp "time exceeded" reply from a gateway.  We start our probes
 * with a ttl of one and increase by one until we get an icmp "port
 * unreachable" (which means we got to "host") or hit a max (which
 * defaults to 30 hops & can be changed with the -m flag).  Three
 * probes (change with -q flag) are sent at each ttl setting and a
 * line is printed showing the ttl, address of the gateway and
 * round trip time of each probe.  If the probe answers come from
 * different gateways, the address of each responding system will
 * be printed.  If there is no response within a 5 sec. timeout
 * interval (changed with the -w flag), a "*" is printed for that
 * probe.
 *
 * Probe packets are UDP format.  We don't want the destination
 * host to process them so the destination port is set to an
 * unlikely value (if some clod on the destination is using that
 * value, it can be changed with the -p flag).
 *
 * A sample use might be:
 *
 *     [yak 71]% traceroute nis.nsf.net.
 *     traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
 *      1  helios.ee.lbl.gov (128.3.112.1)  19 ms  19 ms  0 ms
 *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
 *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  39 ms  19 ms
 *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  39 ms
 *      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  39 ms  39 ms  39 ms
 *      6  128.32.197.4 (128.32.197.4)  40 ms  59 ms  59 ms
 *      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  59 ms
 *      8  129.140.70.13 (129.140.70.13)  99 ms  99 ms  80 ms
 *      9  129.140.71.6 (129.140.71.6)  139 ms  239 ms  319 ms
 *     10  129.140.81.7 (129.140.81.7)  220 ms  199 ms  199 ms
 *     11  nic.merit.edu (35.1.1.48)  239 ms  239 ms  239 ms
 *
 * Note that lines 2 & 3 are the same.  This is due to a buggy
 * kernel on the 2nd hop system -- lbl-csam.arpa -- that forwards
 * packets with a zero ttl.
 *
 * A more interesting example is:
 *
 *     [yak 72]% traceroute allspice.lcs.mit.edu.
 *     traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
 *      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
 *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  19 ms  19 ms
 *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  19 ms
 *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  19 ms  39 ms  39 ms
 *      5  ccn-nerif22.Berkeley.EDU (128.32.168.22)  20 ms  39 ms  39 ms
 *      6  128.32.197.4 (128.32.197.4)  59 ms  119 ms  39 ms
 *      7  131.119.2.5 (131.119.2.5)  59 ms  59 ms  39 ms
 *      8  129.140.70.13 (129.140.70.13)  80 ms  79 ms  99 ms
 *      9  129.140.71.6 (129.140.71.6)  139 ms  139 ms  159 ms
 *     10  129.140.81.7 (129.140.81.7)  199 ms  180 ms  300 ms
 *     11  129.140.72.17 (129.140.72.17)  300 ms  239 ms  239 ms
 *     12  * * *
 *     13  128.121.54.72 (128.121.54.72)  259 ms  499 ms  279 ms
 *     14  * * *
 *     15  * * *
 *     16  * * *
 *     17  * * *
 *     18  ALLSPICE.LCS.MIT.EDU (18.26.0.115)  339 ms  279 ms  279 ms
 *
 * (I start to see why I'm having so much trouble with mail to
 * MIT.)  Note that the gateways 12, 14, 15, 16 & 17 hops away
 * either don't send ICMP "time exceeded" messages or send them
 * with a ttl too small to reach us.  14 - 17 are running the
 * MIT C Gateway code that doesn't send "time exceeded"s.  God
 * only knows what's going on with 12.
 *
 * The silent gateway 12 in the above may be the result of a bug in
 * the 4.[23]BSD network code (and its derivatives):  4.x (x <= 3)
 * sends an unreachable message using whatever ttl remains in the
 * original datagram.  Since, for gateways, the remaining ttl is
 * zero, the icmp "time exceeded" is guaranteed to not make it back
 * to us.  The behavior of this bug is slightly more interesting
 * when it appears on the destination system:
 *
 *      1  helios.ee.lbl.gov (128.3.112.1)  0 ms  0 ms  0 ms
 *      2  lilac-dmc.Berkeley.EDU (128.32.216.1)  39 ms  19 ms  39 ms
 *      3  lilac-dmc.Berkeley.EDU (128.32.216.1)  19 ms  39 ms  19 ms
 *      4  ccngw-ner-cc.Berkeley.EDU (128.32.136.23)  39 ms  40 ms  19 ms
 *      5  ccn-nerif35.Berkeley.EDU (128.32.168.35)  39 ms  39 ms  39 ms
 *      6  csgw.Berkeley.EDU (128.32.133.254)  39 ms  59 ms  39 ms
 *      7  * * *
 *      8  * * *
 *      9  * * *
 *     10  * * *
 *     11  * * *
 *     12  * * *
 *     13  rip.Berkeley.EDU (128.32.131.22)  59 ms !  39 ms !  39 ms !
 *
 * Notice that there are 12 "gateways" (13 is the final
 * destination) and exactly the last half of them are "missing".
 * What's really happening is that rip (a Sun-3 running Sun OS3.5)
 * is using the ttl from our arriving datagram as the ttl in its
 * icmp reply.  So, the reply will time out on the return path
 * (with no notice sent to anyone since icmp's aren't sent for
 * icmp's) until we probe with a ttl that's at least twice the path
 * length.  I.e., rip is really only 7 hops away.  A reply that
 * returns with a ttl of 1 is a clue this problem exists.
 * Traceroute prints a "!" after the time if the ttl is <= 1.
 * Since vendors ship a lot of obsolete (DEC's Ultrix, Sun 3.x) or
 * non-standard (HPUX) software, expect to see this problem
 * frequently and/or take care picking the target host of your
 * probes.
 *
 * Other possible annotations after the time are !H, !N, !P (got a host,
 * network or protocol unreachable, respectively), !S or !F (source
 * route failed or fragmentation needed -- neither of these should
 * ever occur and the associated gateway is busted if you see one).  If
 * almost all the probes result in some kind of unreachable, traceroute
 * will give up and exit.
 *
 * Notes
 * -----
 * This program must be run by root or be setuid.  (I suggest that
 * you *don't* make it setuid -- casual use could result in a lot
 * of unnecessary traffic on our poor, congested nets.)
 *
 * This program requires a kernel mod that does not appear in any
 * system available from Berkeley:  A raw ip socket using proto
 * IPPROTO_RAW must interpret the data sent as an ip datagram (as
 * opposed to data to be wrapped in a ip datagram).  See the README
 * file that came with the source to this program for a description
 * of the mods I made to /sys/netinet/raw_ip.c.  Your mileage may
 * vary.  But, again, ANY 4.x (x < 4) BSD KERNEL WILL HAVE TO BE
 * MODIFIED TO RUN THIS PROGRAM.
 *
 * The udp port usage may appear bizarre (well, ok, it is bizarre).
 * The problem is that an icmp message only contains 8 bytes of
 * data from the original datagram.  8 bytes is the size of a udp
 * header so, if we want to associate replies with the original
 * datagram, the necessary information must be encoded into the
 * udp header (the ip id could be used but there's no way to
 * interlock with the kernel's assignment of ip id's and, anyway,
 * it would have taken a lot more kernel hacking to allow this
 * code to set the ip id).  So, to allow two or more users to
 * use traceroute simultaneously, we use this task's pid as the
 * source port (the high bit is set to move the port number out
 * of the "likely" range).  To keep track of which probe is being
 * replied to (so times and/or hop counts don't get confused by a
 * reply that was delayed in transit), we increment the destination
 * port number before each probe.
 *
 * Don't use this as a coding example.  I was trying to find a
 * routing problem and this code sort-of popped out after 48 hours
 * without sleep.  I was amazed it ever compiled, much less ran.
 *
 * I stole the idea for this program from Steve Deering.  Since
 * the first release, I've learned that had I attended the right
 * IETF working group meetings, I also could have stolen it from Guy
 * Almes or Matt Mathis.  I don't know (or care) who came up with
 * the idea first.  I envy the originators' perspicacity and I'm
 * glad they didn't keep the idea a secret.
 *
 * Tim Seaver, Ken Adelman and C. Philip Wood provided bug fixes and/or
 * enhancements to the original distribution.
 *
 * I've hacked up a round-trip-route version of this that works by
 * sending a loose-source-routed udp datagram through the destination
 * back to yourself.  Unfortunately, SO many gateways botch source
 * routing, the thing is almost worthless.  Maybe one day...
 *
 *  -- Van Jacobson (van (at) ee.lbl.gov)
 *     Tue Dec 20 03:50:13 PST 1988
 */

#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/sysctl.h>

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#include <arpa/inet.h>

#include <ctype.h>
#include <errno.h>
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif
#include <memory.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <poll.h>
#ifdef IPSEC
#include <net/route.h>
#include <netinet6/ipsec.h>
#endif

#include "gnuc.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

#include "ifaddrlist.h"
#include "as.h"

/* Maximum number of gateways (include room for one noop) */
#define NGATEWAYS ((int)((MAX_IPOPTLEN - IPOPT_MINOFF - 1) / sizeof(u_int32_t)))

#ifndef MAXHOSTNAMELEN
#define MAXHOSTNAMELEN	64
#endif

#define Fprintf (void)fprintf
#define Printf (void)printf

/* Host name and address list */
struct hostinfo {
	char *name;
	int n;
	u_int32_t *addrs;
};

/* Data section of the probe packet */
struct outdata {
	u_char seq;		/* sequence number of this packet */
	u_char ttl;		/* ttl packet left with */
	struct timeval tv;	/* time packet left */
};

/*
 * Support for ICMP extensions
 *
 * http://www.ietf.org/proceedings/01aug/I-D/draft-ietf-mpls-icmp-02.txt
 */
#define ICMP_EXT_OFFSET    8 /* ICMP type, code, checksum, unused */ + \
                         128 /* original datagram */
#define ICMP_EXT_VERSION 2
/*
 * ICMP extensions, common header
 */
struct icmp_ext_cmn_hdr {
#if BYTE_ORDER == BIG_ENDIAN
	unsigned char   version:4;
	unsigned char   reserved1:4;
#else
	unsigned char   reserved1:4;
	unsigned char   version:4;
#endif
	unsigned char   reserved2;
	unsigned short  checksum;
};

/*
 * ICMP extensions, object header
 */
struct icmp_ext_obj_hdr {
    u_short length;
    u_char  class_num;
#define MPLS_STACK_ENTRY_CLASS 1
    u_char  c_type;
#define MPLS_STACK_ENTRY_C_TYPE 1
};

struct mpls_header {
#if BYTE_ORDER == BIG_ENDIAN
	 uint32_t	label:20;
	 unsigned char  exp:3;
	 unsigned char  s:1;
	 unsigned char  ttl:8;
#else
	 unsigned char  ttl:8;
	 unsigned char  s:1;
	 unsigned char  exp:3;
	 uint32_t	label:20;
#endif
};

u_char	packet[512];		/* last inbound (icmp) packet */

struct ip *outip;		/* last output (udp) packet */
struct udphdr *outudp;		/* last output (udp) packet */
void *outmark;			/* packed location of struct outdata */
struct outdata outsetup;	/* setup and copy for alignment */

struct icmp *outicmp;		/* last output (icmp) packet */

/* loose source route gateway list (including room for final destination) */
u_int32_t gwlist[NGATEWAYS + 1];

int s;				/* receive (icmp) socket file descriptor */
int sndsock;			/* send (udp/icmp) socket file descriptor */

struct sockaddr whereto;	/* Who to try to reach */
struct sockaddr_in wherefrom;	/* Who we are */
int packlen;			/* total length of packet */
int minpacket;			/* min ip packet size */
int maxpacket = 32 * 1024;	/* max ip packet size */
int printed_ttl = 0;

char *prog;
char *source;
char *hostname;
char *device;

int nprobes = 3;
int max_ttl = 30;
int first_ttl = 1;
u_int16_t ident;
in_port_t port = 32768 + 666;	/* start udp dest port # for probe packets */

int options;			/* socket options */
int verbose;
int waittime = 5;		/* time to wait for response (in seconds) */
int nflag;			/* print addresses numerically */
int dump;
int Mflag;			/* show MPLS labels if any */
int as_path;			/* print as numbers for each hop */
char *as_server = NULL;
void *asn;
int useicmp;			/* use icmp echo instead of udp packets */
#ifdef CANT_HACK_CKSUM
int docksum = 0;		/* don't calculate checksums */
#else
int docksum = 1;		/* calculate checksums */
#endif
int optlen;			/* length of ip options */

int mtus[] = {
        17914,
         8166,
         4464,
         4352,
         2048,
         2002,
         1536,
         1500,
         1492,
	 1480,
	 1280,
         1006,
          576,
          552,
          544,
          512,
          508,
          296,
           68,
            0
};
int *mtuptr = &mtus[0];
int mtudisc = 0;
int nextmtu;   /* from ICMP error, set by packet_ok(), might be 0 */

extern int optind;
extern int opterr;
extern char *optarg;

/* Forwards */
double	deltaT(struct timeval *, struct timeval *);
void	freehostinfo(struct hostinfo *);
void	getaddr(u_int32_t *, char *);
struct	hostinfo *gethostinfo(char *);
u_int16_t in_cksum(u_int16_t *, int);
u_int16_t in_cksum2(u_int16_t, u_int16_t *, int);
char	*inetname(struct in_addr);
int	main(int, char **);
int	packet_ok(u_char *, int, struct sockaddr_in *, int);
char	*pr_type(u_char);
void	print(u_char *, int, struct sockaddr_in *);
void	resize_packet(void);
void	dump_packet(void);
void	send_probe(int, int, struct timeval *);
void	setsin(struct sockaddr_in *, u_int32_t);
int	str2val(const char *, const char *, int, int);
void	tvsub(struct timeval *, struct timeval *);
__dead	void usage(void);
int	wait_for_reply(int, struct sockaddr_in *, struct timeval *);
void	decode_extensions(unsigned char *buf, int ip_len);
void	frag_err(void);
int	find_local_ip(struct sockaddr_in *, struct sockaddr_in *);
#ifdef IPSEC
#ifdef IPSEC_POLICY_IPSEC
int	setpolicy(int so, char *policy);
#endif
#endif

int
main(int argc, char **argv)
{
	int op, code, n;
	char *cp;
	u_char *outp;
	u_int32_t *ap;
	struct sockaddr_in *from = &wherefrom;
	struct sockaddr_in *to = (struct sockaddr_in *)&whereto;
	struct hostinfo *hi;
	int on = 1;
	int ttl, probe, i;
	int seq = 0;
	int tos = 0, settos = 0, ttl_flag = 0;
	int lsrr = 0;
	u_int16_t off = 0;
	struct ifaddrlist *al, *al2;
	char errbuf[132];
	int mib[4] = { CTL_NET, PF_INET, IPPROTO_IP, IPCTL_DEFTTL };
	size_t size = sizeof(max_ttl);

	(void) sysctl(mib, sizeof(mib)/sizeof(mib[0]), &max_ttl, &size,
	    NULL, 0);

	if ((cp = strrchr(argv[0], '/')) != NULL)
		prog = cp + 1;
	else
		prog = argv[0];

	opterr = 0;
	while ((op = getopt(argc, argv, "aA:dDFPIMnlrvxf:g:i:m:p:q:s:t:w:")) != -1)
		switch (op) {

		case 'a':
			as_path = 1;
			break;

		case 'A':
			as_path = 1;
			as_server = optarg;
			break;

		case 'd':
			options |= SO_DEBUG;
			break;

		case 'D':
			dump = 1;
			break;

		case 'f':
			first_ttl = str2val(optarg, "first ttl", 1, 255);
			break;

		case 'F':
			off = IP_DF;
			break;

		case 'g':
			if (lsrr >= NGATEWAYS) {
				Fprintf(stderr,
				    "%s: No more than %d gateways\n",
				    prog, NGATEWAYS);
				exit(1);
			}
			getaddr(gwlist + lsrr, optarg);
			++lsrr;
			break;

		case 'i':
			device = optarg;
			break;

		case 'I':
			++useicmp;
			break;

		case 'l':
			++ttl_flag;
			break;

		case 'm':
			max_ttl = str2val(optarg, "max ttl", 1, 255);
			break;

		case 'M':
			Mflag = 1;
			break;

		case 'n':
			++nflag;
			break;

		case 'p':
			port = str2val(optarg, "port", 1, -1);
			break;

		case 'q':
			nprobes = str2val(optarg, "nprobes", 1, -1);
			break;

		case 'r':
			options |= SO_DONTROUTE;
			break;

		case 's':
			/*
			 * set the ip source address of the outbound
			 * probe (e.g., on a multi-homed host).
			 */
			source = optarg;
			break;

		case 't':
			tos = str2val(optarg, "tos", 0, 255);
			++settos;
			break;

		case 'v':
			++verbose;
			break;

		case 'x':
			docksum = (docksum == 0);
			break;

		case 'w':
			waittime = str2val(optarg, "wait time", 2, 24 * 3600);
			break;

		case 'P':
			off = IP_DF;
			mtudisc = 1;
			break;

		default:
			usage();
		}

	if (first_ttl > max_ttl) {
		Fprintf(stderr,
		    "%s: first ttl (%d) may not be greater than max ttl (%d)\n",
		    prog, first_ttl, max_ttl);
		exit(1);
	}

	if (!docksum)
		Fprintf(stderr, "%s: Warning: ckecksums disabled\n", prog);

	if (lsrr > 0)
		optlen = (lsrr + 1) * sizeof(gwlist[0]);
	minpacket = sizeof(*outip) + sizeof(struct outdata) + optlen;
	if (useicmp)
		minpacket += 8;			/* XXX magic number */
	else
		minpacket += sizeof(*outudp);
	if (packlen == 0)
		packlen = minpacket;		/* minimum sized packet */
	else if (minpacket > packlen || packlen > maxpacket) {
		Fprintf(stderr, "%s: packet size must be %d <= s <= %d\n",
		    prog, minpacket, maxpacket);
		exit(1);
	}

	if (mtudisc)
		packlen = *mtuptr++;

	/* Process destination and optional packet size */
	switch (argc - optind) {

	case 2:
		packlen = str2val(argv[optind + 1],
		    "packet length", minpacket, -1);
		/* Fall through */

	case 1:
		hostname = argv[optind];
		hi = gethostinfo(hostname);
		setsin(to, hi->addrs[0]);
		if (hi->n > 1)
			Fprintf(stderr,
		    "%s: Warning: %s has multiple addresses; using %s\n",
				prog, hostname, inet_ntoa(to->sin_addr));
		hostname = hi->name;
		hi->name = NULL;
		freehostinfo(hi);
		break;

	default:
		usage();
	}

#ifdef HAVE_SETLINEBUF
	setlinebuf (stdout);
#else
	setvbuf(stdout, NULL, _IOLBF, 0);
#endif

	outip = (struct ip *)malloc((unsigned)packlen);
	if (outip == NULL) {
		Fprintf(stderr, "%s: malloc: %s\n", prog, strerror(errno));
		exit(1);
	}
	memset((char *)outip, 0, packlen);

	outip->ip_v = IPVERSION;
	if (settos)
		outip->ip_tos = tos;
#ifdef BYTESWAP_IP_LEN
	outip->ip_len = htons(packlen);
#else
	outip->ip_len = packlen;
#endif
	outip->ip_off = off;
	outp = (u_char *)(outip + 1);
#ifdef HAVE_RAW_OPTIONS
	if (lsrr > 0) {
		u_char *optlist;

		optlist = outp;
		outp += optlen;

		/* final hop */
		gwlist[lsrr] = to->sin_addr.s_addr;

		outip->ip_dst.s_addr = gwlist[0];

		/* force 4 byte alignment */
		optlist[0] = IPOPT_NOP;
		/* loose source route option */
		optlist[1] = IPOPT_LSRR;
		i = lsrr * sizeof(gwlist[0]);
		optlist[2] = i + 3;
		/* Pointer to LSRR addresses */
		optlist[3] = IPOPT_MINOFF;
		memcpy(optlist + 4, gwlist + 1, i);
	} else
#endif
		outip->ip_dst = to->sin_addr;

	outip->ip_hl = (outp - (u_char *)outip) >> 2;
	ident = htons(arc4random() & 0xffff) | 0x8000;
	if (useicmp) {
		outip->ip_p = IPPROTO_ICMP;

		outicmp = (struct icmp *)outp;
		outicmp->icmp_type = ICMP_ECHO;
		outicmp->icmp_id = htons(ident);

		outmark = outp + 8;	/* XXX magic number */
	} else {
		outip->ip_p = IPPROTO_UDP;

		outudp = (struct udphdr *)outp;
		outudp->uh_sport = htons(ident);
		outudp->uh_ulen =
		    htons((u_int16_t)(packlen - (sizeof(*outip) + optlen)));
		outmark = outudp + 1;
	}

	if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
		Fprintf(stderr, "%s: icmp socket: %s\n", prog, strerror(errno));
		exit(1);
	}
	if (options & SO_DEBUG)
		(void)setsockopt(s, SOL_SOCKET, SO_DEBUG, (char *)&on,
		    sizeof(on));
#ifdef IPSEC
#ifdef IPSEC_POLICY_IPSEC
	/*
	 * do not raise error even if setsockopt fails, kernel may have ipsec
	 * turned off.
	 */
	if (setpolicy(s, "in bypass") < 0)
		exit(1);
	if (setpolicy(s, "out bypass") < 0)
		exit(1);
#else
    {
	int level = IPSEC_LEVEL_AVAIL;

	(void)setsockopt(s, IPPROTO_IP, IP_ESP_TRANS_LEVEL, &level,
		sizeof(level));
	(void)setsockopt(s, IPPROTO_IP, IP_ESP_NETWORK_LEVEL, &level,
		sizeof(level));
#ifdef IP_AUTH_TRANS_LEVEL
	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_TRANS_LEVEL, &level,
		sizeof(level));
#else
	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_LEVEL, &level,
		sizeof(level));
#endif
#ifdef IP_AUTH_NETWORK_LEVEL
	(void)setsockopt(s, IPPROTO_IP, IP_AUTH_NETWORK_LEVEL, &level,
		sizeof(level));
#endif
    }
#endif /*IPSEC_POLICY_IPSEC*/
#endif /*IPSEC*/

#ifndef __hpux
	sndsock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
#else
	sndsock = socket(AF_INET, SOCK_RAW,
	    useicmp ? IPPROTO_ICMP : IPPROTO_UDP);
#endif
	if (sndsock < 0) {
		Fprintf(stderr, "%s: raw socket: %s\n", prog, strerror(errno));
		exit(1);
	}

#ifdef IPSEC
#ifdef IPSEC_POLICY_IPSEC
	/*
	 * do not raise error even if setsockopt fails, kernel may have ipsec
	 * turned off.
	 */
	if (setpolicy(sndsock, "in bypass") < 0)
		exit(1);
	if (setpolicy(sndsock, "out bypass") < 0)
		exit(1);
#else
    {
	int level = IPSEC_LEVEL_BYPASS;

	(void)setsockopt(sndsock, IPPROTO_IP, IP_ESP_TRANS_LEVEL, &level,
		sizeof(level));
	(void)setsockopt(sndsock, IPPROTO_IP, IP_ESP_NETWORK_LEVEL, &level,
		sizeof(level));
#ifdef IP_AUTH_TRANS_LEVEL
	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_TRANS_LEVEL, &level,
		sizeof(level));
#else
	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_LEVEL, &level,
		sizeof(level));
#endif
#ifdef IP_AUTH_NETWORK_LEVEL
	(void)setsockopt(sndsock, IPPROTO_IP, IP_AUTH_NETWORK_LEVEL, &level,
		sizeof(level));
#endif
    }
#endif /*IPSEC_POLICY_IPSEC*/
#endif /*IPSEC*/

	/* Revert to non-privileged user after opening sockets */
	setuid(getuid());

#if defined(IP_OPTIONS) && !defined(HAVE_RAW_OPTIONS)
	if (lsrr > 0) {
		u_char optlist[MAX_IPOPTLEN];

		/* final hop */
		gwlist[lsrr] = to->sin_addr.s_addr;
		++lsrr;

		/* force 4 byte alignment */
		optlist[0] = IPOPT_NOP;
		/* loose source route option */
		optlist[1] = IPOPT_LSRR;
		i = lsrr * sizeof(gwlist[0]);
		optlist[2] = i + 3;
		/* Pointer to LSRR addresses */
		optlist[3] = IPOPT_MINOFF;
		memcpy(optlist + 4, gwlist, i);

		if ((setsockopt(sndsock, IPPROTO_IP, IP_OPTIONS, optlist,
		    i + sizeof(gwlist[0]))) < 0) {
			Fprintf(stderr, "%s: IP_OPTIONS: %s\n",
			    prog, strerror(errno));
			exit(1);
		    }
	}
#endif

#ifdef SO_SNDBUF
	if (setsockopt(sndsock, SOL_SOCKET, SO_SNDBUF, (char *)&packlen,
	    sizeof(packlen)) < 0) {
		Fprintf(stderr, "%s: SO_SNDBUF: %s\n", prog, strerror(errno));
		exit(1);
	}
#endif
#ifdef IP_HDRINCL
	if (setsockopt(sndsock, IPPROTO_IP, IP_HDRINCL, (char *)&on,
	    sizeof(on)) < 0) {
		Fprintf(stderr, "%s: IP_HDRINCL: %s\n", prog, strerror(errno));
		exit(1);
	}
#else
#ifdef IP_TOS
	if (settos && setsockopt(sndsock, IPPROTO_IP, IP_TOS,
	    (char *)&tos, sizeof(tos)) < 0) {
		Fprintf(stderr, "%s: setsockopt tos %d: %s\n",
		    prog, tos, strerror(errno));
		exit(1);
	}
#endif
#endif
	if (options & SO_DEBUG)
		(void)setsockopt(sndsock, SOL_SOCKET, SO_DEBUG, (char *)&on,
		    sizeof(on));
	if (options & SO_DONTROUTE)
		(void)setsockopt(sndsock, SOL_SOCKET, SO_DONTROUTE, (char *)&on,
		    sizeof(on));

	/* Get the interface address list */
	n = ifaddrlist(&al, errbuf, sizeof errbuf);
	al2 = al;
	if (n < 0) {
		Fprintf(stderr, "%s: ifaddrlist: %s\n", prog, errbuf);
		exit(1);
	}
	if (n == 0) {
		Fprintf(stderr,
		    "%s: Can't find any network interfaces\n", prog);
		exit(1);
	}

	/* Look for a specific device */
	if (device != NULL) {
		for (i = n; i > 0; --i, ++al2)
			if (strcmp(device, al2->device) == 0)
				break;
		if (i <= 0) {
			Fprintf(stderr, "%s: Can't find interface %s\n",
			    prog, device);
			exit(1);
		}
	}

	/* Determine our source address */
	if (source == NULL) {
		/*
		 * If a device was specified, use the interface address.
		 * Otherwise, use the first interface found.
		 * Warn if there are more than one.
		 */
		setsin(from, al2->addr);
		if (n > 1 && device == NULL && !find_local_ip(from, to)) {
			Fprintf(stderr,
		    "%s: Warning: Multiple interfaces found; using %s @ %s\n",
			    prog, inet_ntoa(from->sin_addr), al2->device);
		}
	} else {
		hi = gethostinfo(source);
		source = hi->name;
		hi->name = NULL;
		if (device == NULL) {
			/*
			 * Use the first interface found.
			 * Warn if there are more than one.
			 */
			setsin(from, hi->addrs[0]);
			if (hi->n > 1)
				Fprintf(stderr,
			"%s: Warning: %s has multiple addresses; using %s\n",
				    prog, source, inet_ntoa(from->sin_addr));
		} else {
			/*
			 * Make sure the source specified matches the
			 * interface address.
			 */
			for (i = hi->n, ap = hi->addrs; i > 0; --i, ++ap)
				if (*ap == al2->addr)
					break;
			if (i <= 0) {
				Fprintf(stderr,
				    "%s: %s is not on interface %s\n",
				    prog, source, device);
				exit(1);
			}
			setsin(from, *ap);
		}
		freehostinfo(hi);
	}

	/*
	 * If not root, make sure source address matches a local interface.
	 * (The list of addresses produced by ifaddrlist() automatically
	 * excludes interfaces that are marked down and/or loopback.)
	 */
	if (getuid())  {
		al2 = al;
		for (i = n; i > 0; --i, ++al2)
			if (from->sin_addr.s_addr == al2->addr)
			    break;
		if (i <= 0) {
			Fprintf(stderr, "%s: %s is not a valid local address "
			    "and you are not superuser.\n", prog,
			    inet_ntoa(from->sin_addr));
			exit(1);
		}
	}

	outip->ip_src = from->sin_addr;
#ifndef IP_HDRINCL
	if (bind(sndsock, (struct sockaddr *)from, sizeof(*from)) < 0) {
		Fprintf(stderr, "%s: bind: %s\n",
		    prog, strerror(errno));
		exit (1);
	}
#endif

	if (as_path) {
		asn = as_setup(as_server);
		if (asn == NULL) {
			Fprintf(stderr, "%s: as_setup failed, AS# lookups disabled\n",
				prog);
			(void)fflush(stderr);
			as_path = 0;
		}
	}

	setuid(getuid());
	Fprintf(stderr, "%s to %s (%s)",
	    prog, hostname, inet_ntoa(to->sin_addr));
	if (source)
		Fprintf(stderr, " from %s", source);
	Fprintf(stderr, ", %d hops max, %d byte packets\n", max_ttl, packlen);
	(void)fflush(stderr);

	for (ttl = first_ttl; ttl <= max_ttl; ++ttl) {
		u_int32_t lastaddr = 0;
		int got_there = 0;
		int unreachable = 0;

again:
		printed_ttl = 0;
		for (probe = 0; probe < nprobes; ++probe) {
			int cc;
			struct timeval t1, t2;
			struct ip *ip;
			(void)gettimeofday(&t1, NULL);
			send_probe(++seq, ttl, &t1);
			while ((cc = wait_for_reply(s, from, &t1)) != 0) {
				(void)gettimeofday(&t2, NULL);
				/*
				 * Since we'll be receiving all ICMP
				 * messages to this host above, we may
				 * never end up with cc=0, so we need
				 * an additional termination check.
				 */
				if (t2.tv_sec - t1.tv_sec > waittime) {
					cc = 0;
					break;
				}
				i = packet_ok(packet, cc, from, seq);
				/* Skip short packet */
				if (i == 0)
					continue;
				if (from->sin_addr.s_addr != lastaddr) {
					print(packet, cc, from);
					lastaddr = from->sin_addr.s_addr;
				}
				ip = (struct ip *)packet;
				Printf("  %.3f ms", deltaT(&t1, &t2));
				if (ttl_flag)
					Printf(" (ttl = %d)", ip->ip_ttl);
				if (i == -2) {
#ifndef ARCHAIC
					if (ip->ip_ttl <= 1)
						Printf(" !");
#endif
					++got_there;
					break;
				}

				/* time exceeded in transit */
				if (i == -1)
					break;
				code = i - 1;
				switch (code) {

				case ICMP_UNREACH_PORT:
#ifndef ARCHAIC
					if (ip->ip_ttl <= 1)
						Printf(" !");
#endif
					++got_there;
					break;

				case ICMP_UNREACH_NET:
					++unreachable;
					Printf(" !N");
					break;

				case ICMP_UNREACH_HOST:
					++unreachable;
					Printf(" !H");
					break;

				case ICMP_UNREACH_PROTOCOL:
					++got_there;
					Printf(" !P");
					break;

				case ICMP_UNREACH_NEEDFRAG:
					if (mtudisc) {
						frag_err();
						goto again;
					} else {
						++unreachable;
						Printf(" !F");
					}
					break;

				case ICMP_UNREACH_SRCFAIL:
					++unreachable;
					Printf(" !S");
					break;

/* rfc1716 */
#ifndef ICMP_UNREACH_FILTER_PROHIB
#define ICMP_UNREACH_FILTER_PROHIB	13	/* admin prohibited filter */
#endif
				case ICMP_UNREACH_FILTER_PROHIB:
					++unreachable;
					Printf(" !X");
					break;

				default:
					++unreachable;
					Printf(" !<%d>", code);
					break;
				}
				break;
			}
			if (cc == 0)
				Printf(" *");
			else if (cc && probe == nprobes - 1 && Mflag)
				decode_extensions(packet, cc);
			(void)fflush(stdout);
		}
		putchar('\n');
		if (got_there ||
		    (unreachable > 0 && unreachable >= ((nprobes + 1) / 2)))
			break;
	}

	if (as_path)
		as_shutdown(asn);

	exit(0);
}

int
wait_for_reply(int sock, struct sockaddr_in *fromp, struct timeval *tp)
{
	struct pollfd set[1];
	struct timeval now, wait;
	int cc = 0;
	socklen_t fromlen = sizeof(*fromp);
	int retval;

	set[0].fd = sock;
	set[0].events = POLLIN;

	wait.tv_sec = tp->tv_sec + waittime;
	wait.tv_usec = tp->tv_usec;
	(void)gettimeofday(&now, NULL);
	tvsub(&wait, &now);

	if (wait.tv_sec < 0) {
		wait.tv_sec = 0;
		wait.tv_usec = 0;
	}

	retval = poll(set, 1, wait.tv_sec * 1000 + wait.tv_usec / 1000);
	if (retval < 0)  {
		/* If we continue, we probably just flood the remote host. */
		Fprintf(stderr, "%s: select: %s\n", prog, strerror(errno));
		exit(1);
	}
	if (retval > 0)  {
		cc = recvfrom(s, (char *)packet, sizeof(packet), 0,
			    (struct sockaddr *)fromp, &fromlen);
	}

	return(cc);
}

void
decode_extensions(unsigned char *buf, int ip_len)
{
        struct icmp_ext_cmn_hdr *cmn_hdr;
        struct icmp_ext_obj_hdr *obj_hdr;
        union {
                struct mpls_header mpls;
                uint32_t mpls_h;
        } mpls;
        int datalen, obj_len;
        struct ip *ip;

        ip = (struct ip *)buf;

        if (ip_len <= sizeof(struct ip) + ICMP_EXT_OFFSET) {
		/*
		 * No support for ICMP extensions on this host
		 */
		return;
        }

        /*
         * Move forward to the start of the ICMP extensions, if present
         */
        buf += (ip->ip_hl << 2) + ICMP_EXT_OFFSET;
        cmn_hdr = (struct icmp_ext_cmn_hdr *)buf;

        if (cmn_hdr->version != ICMP_EXT_VERSION) {
		/*
		 * Unknown version
		 */
		return;
        }

        datalen = ip_len - ((u_char *)cmn_hdr - (u_char *)ip);

        /*
         * Check the checksum, cmn_hdr->checksum == 0 means no checksum'ing
         * done by sender.
         *
        * If the checksum is ok, we'll get 0, as the checksum is calculated
         * with the checksum field being 0'd.
         */
        if (ntohs(cmn_hdr->checksum) &&
            in_cksum((u_short *)cmn_hdr, datalen)) {

            return;
        }

        buf += sizeof(*cmn_hdr);
        datalen -= sizeof(*cmn_hdr);

        while (datalen > 0) {
		obj_hdr = (struct icmp_ext_obj_hdr *)buf;
		obj_len = ntohs(obj_hdr->length);

		/*
		 * Sanity check the length field
		 */
		if (obj_len > datalen) {
			return;
		}

		datalen -= obj_len;

		/*
		 * Move past the object header
		 */
		buf += sizeof(struct icmp_ext_obj_hdr);
		obj_len -= sizeof(struct icmp_ext_obj_hdr);

		switch (obj_hdr->class_num) {
		case MPLS_STACK_ENTRY_CLASS:
			switch (obj_hdr->c_type) {
			case MPLS_STACK_ENTRY_C_TYPE:
				while (obj_len >= sizeof(uint32_t)) {
					mpls.mpls_h = ntohl(*(uint32_t *)buf);

					buf += sizeof(uint32_t);
					obj_len -= sizeof(uint32_t);

					printf(" [MPLS: Label %d Exp %d]"
					    mpls.mpls.label, mpls.mpls.exp);
				}
				if (obj_len > 0) {
					/*
					 * Something went wrong, and we're at
					 * a unknown offset into the packet,
					 * ditch the rest of it.
					 */
					return;
				}
				break;
			default:
				/*
				 * Unknown object, skip past it
				 */
				buf += ntohs(obj_hdr->length) -
				    sizeof(struct icmp_ext_obj_hdr);
				break;
			}
			break;

		default:
			/*
			 * Unknown object, skip past it
			 */
			buf += ntohs(obj_hdr->length) -
			    sizeof(struct icmp_ext_obj_hdr);
			break;
		}
	}
}

void
dump_packet()
{
	u_char *p;
	int i;

	Fprintf(stderr, "packet data:");

#ifdef __hpux
	for (p = useicmp ? (u_char *)outicmp : (u_char *)outudp, i = 0; i <
	    i < packlen - (sizeof(*outip) + optlen); i++)
#else
	for (p = (u_char *)outip, i = 0; i < packlen; i++)
#endif
	{
		if ((i % 24) == 0)
			Fprintf(stderr, "\n ");
		Fprintf(stderr, " %02x", *p++);
	}
	Fprintf(stderr, "\n");
}

void
send_probe(int seq, int ttl, struct timeval *tp)
{
	int cc;
	struct udpiphdr * ui;
	int oldmtu = packlen;

again:
#ifdef BYTESWAP_IP_LEN
	outip->ip_len = htons(packlen);
#else
	outip->ip_len = packlen;
#endif
	outip->ip_ttl = ttl;
#ifndef __hpux
	outip->ip_id = htons(ident + seq);
#endif

	/*
	 * In most cases, the kernel will recalculate the ip checksum.
	 * But we must do it anyway so that the udp checksum comes out
	 * right.
	 */
	if (docksum) {
		outip->ip_sum =
		    in_cksum((u_int16_t *)outip, sizeof(*outip) + optlen);
		if (outip->ip_sum == 0)
			outip->ip_sum = 0xffff;
	}

	/* Payload */
	outsetup.seq = seq;
	outsetup.ttl = ttl;
	outsetup.tv  = *tp;
	memcpy(outmark,&outsetup,sizeof(outsetup));

	if (useicmp)
		outicmp->icmp_seq = htons(seq);
	else
		outudp->uh_dport = htons(port + seq);

	/* (We can only do the checksum if we know our ip address) */
	if (docksum) {
		if (useicmp) {
			outicmp->icmp_cksum = 0;
			outicmp->icmp_cksum = in_cksum((u_int16_t *)outicmp,
			    packlen - (sizeof(*outip) + optlen));
			if (outicmp->icmp_cksum == 0)
				outicmp->icmp_cksum = 0xffff;
		} else {
			u_int16_t sum;
			struct {
				struct in_addr src;
				struct in_addr dst;
				u_int8_t zero;
				u_int8_t protocol;
				u_int16_t len;
			} __attribute__((__packed__)) phdr;

			/* Checksum */
			ui = (struct udpiphdr *)outip;
			memset(&phdr, 0, sizeof(phdr));
			phdr.src = ui->ui_src;
			phdr.dst = ((struct sockaddr_in *)&whereto)->sin_addr;
			phdr.protocol = ui->ui_pr;
			phdr.len = outudp->uh_ulen;
			outudp->uh_sum = 0;
			sum = in_cksum2(0, (u_int16_t *)&phdr, sizeof(phdr));
			sum = in_cksum2(sum, (u_int16_t *)outudp, ntohs(outudp->uh_ulen));
			sum = ~sum;	/** XXXSCW: Quell SuperH Compiler Bug */
			outudp->uh_sum = sum;
			if (outudp->uh_sum == 0)
				outudp->uh_sum = 0xffff;
		}
	}

	/* XXX undocumented debugging hack */
	if (verbose > 1) {
		const u_int16_t *sp;
		int nshorts, i;

		sp = (u_int16_t *)outip;
		nshorts = (u_int)packlen / sizeof(u_int16_t);
		i = 0;
		Printf("[ %d bytes", packlen);
		while (--nshorts >= 0) {
			if ((i++ % 8) == 0)
				Printf("\n\t");
			Printf(" %04x", ntohs(*sp++));
		}
		if (packlen & 1) {
			if ((i % 8) == 0)
				Printf("\n\t");
			Printf(" %02x", *(u_char *)sp);
		}
		Printf("]\n");
	}

#if !defined(IP_HDRINCL) && defined(IP_TTL)
	if (setsockopt(sndsock, IPPROTO_IP, IP_TTL,
	    (char *)&ttl, sizeof(ttl)) < 0) {
		Fprintf(stderr, "%s: setsockopt ttl %d: %s\n",
		    prog, ttl, strerror(errno));
		exit(1);
	}
#endif
	if (dump)
		dump_packet();

#ifdef __hpux
	cc = sendto(sndsock, useicmp ? (char *)outicmp : (char *)outudp,
	    packlen - (sizeof(*outip) + optlen), 0, &whereto, sizeof(whereto));
	if (cc > 0)
		cc += sizeof(*outip) + optlen;
#else
	cc = sendto(sndsock, (char *)outip,
	    packlen, 0, &whereto, sizeof(whereto));
#endif
	if (cc < 0 || cc != packlen)  {
		if (cc < 0) {
			/*
			 * An errno of EMSGSIZE means we're writing too big a
			 * datagram for the interface.  We have to just
			 * decrease the packet size until we find one that
			 * works.
			 *
			 * XXX maybe we should try to read the outgoing if's
			 * mtu?
			 */
			if (errno == EMSGSIZE) {
				packlen = *mtuptr++;
				resize_packet();
				goto again;
			} else
				Fprintf(stderr, "%s: sendto: %s\n",
				    prog, strerror(errno));
		}

		Printf("%s: wrote %s %d chars, ret=%d\n",
		    prog, hostname, packlen, cc);
		(void)fflush(stdout);
	}
	if (oldmtu != packlen) {
		Printf("message too big, "
		    "trying new MTU = %d\n", packlen);
		printed_ttl = 0;
	}
	if (!printed_ttl) {
		Printf("%2d ", ttl);
		printed_ttl = 1;
	}

}

double
deltaT(struct timeval *t1p, struct timeval *t2p)
{
	double dt;

	dt = (double)(t2p->tv_sec - t1p->tv_sec) * 1000.0 +
	     (double)(t2p->tv_usec - t1p->tv_usec) / 1000.0;
	return (dt);
}

/*
 * Convert an ICMP "type" field to a printable string.
 */
char *
pr_type(u_char t)
{
	static char *ttab[] = {
	"Echo Reply",	"ICMP 1",	"ICMP 2",	"Dest Unreachable",
	"Source Quench", "Redirect",	"ICMP 6",	"ICMP 7",
	"Echo",		"ICMP 9",	"ICMP 10",	"Time Exceeded",
	"Param Problem", "Timestamp",	"Timestamp Reply", "Info Request",
	"Info Reply"
	};

	if (t > 16)
		return("OUT-OF-RANGE");

	return(ttab[t]);
}

int
packet_ok(u_char *buf, int cc, struct sockaddr_in *from, int seq)
{
	struct icmp *icp;
	u_char type, code;
	int hlen;
#ifndef ARCHAIC
	struct ip *ip;

	ip = (struct ip *) buf;
	hlen = ip->ip_hl << 2;
	if (cc < hlen + ICMP_MINLEN) {
		if (verbose)
			Printf("packet too short (%d bytes) from %s\n", cc,
				inet_ntoa(from->sin_addr));
		return (0);
	}
	cc -= hlen;
	icp = (struct icmp *)(buf + hlen);
#else
	icp = (struct icmp *)buf;
#endif
	type = icp->icmp_type;
	code = icp->icmp_code;
	if ((type == ICMP_TIMXCEED && code == ICMP_TIMXCEED_INTRANS) ||
	    type == ICMP_UNREACH || type == ICMP_ECHOREPLY) {
		struct ip *hip;
		struct udphdr *up;
		struct icmp *hicmp;

		hip = &icp->icmp_ip;
		hlen = hip->ip_hl << 2;

		nextmtu = ntohs(icp->icmp_nextmtu);	/* for frag_err() */

		if (useicmp) {
			/* XXX */
			if (type == ICMP_ECHOREPLY &&
			    icp->icmp_id == htons(ident) &&
			    icp->icmp_seq == htons(seq))
				return (-2);

			hicmp = (struct icmp *)((u_char *)hip + hlen);
			/* XXX 8 is a magic number */
			if (hlen + 8 <= cc &&
			    hip->ip_p == IPPROTO_ICMP &&
			    hicmp->icmp_id == htons(ident) &&
			    hicmp->icmp_seq == htons(seq))
				return (type == ICMP_TIMXCEED ? -1 : code + 1);
		} else {
			up = (struct udphdr *)((u_char *)hip + hlen);
			/* XXX 8 is a magic number */
			if (hlen + 12 <= cc &&
			    hip->ip_p == IPPROTO_UDP &&
			    up->uh_sport == htons(ident) &&
			    up->uh_dport == htons(port + seq))
				return (type == ICMP_TIMXCEED ? -1 : code + 1);
		}
	}
#ifndef ARCHAIC
	if (verbose) {
		int i;
		u_int32_t *lp = (u_int32_t *)&icp->icmp_ip;

		Printf("\n%d bytes from %s to ", cc, inet_ntoa(from->sin_addr));
		Printf("%s: icmp type %d (%s) code %d\n",
		    inet_ntoa(ip->ip_dst), type, pr_type(type), icp->icmp_code);
		for (i = 4; i < cc ; i += sizeof(*lp))
			Printf("%2d: x%8.8x\n", i, *lp++);
	}
#endif
	return(0);
}

void resize_packet(void)
{
	if (useicmp) {
		outicmp->icmp_cksum = 0;
		outicmp->icmp_cksum = in_cksum((u_int16_t *)outicmp,
		    packlen - (sizeof(*outip) + optlen));
		if (outicmp->icmp_cksum == 0)
			outicmp->icmp_cksum = 0xffff;
	} else {
		outudp->uh_ulen =
		    htons((u_int16_t)(packlen - (sizeof(*outip) + optlen)));
	}
}

void
print(u_char *buf, int cc, struct sockaddr_in *from)
{
	struct ip *ip;
	int hlen;

	ip = (struct ip *) buf;
	hlen = ip->ip_hl << 2;
	cc -= hlen;

	if (as_path)
		Printf(" [AS%d]", as_lookup(asn, &from->sin_addr));

	if (nflag)
		Printf(" %s", inet_ntoa(from->sin_addr));
	else
		Printf(" %s (%s)", inetname(from->sin_addr),
		    inet_ntoa(from->sin_addr));

	if (verbose)
		Printf(" %d bytes to %s", cc, inet_ntoa (ip->ip_dst));
}

u_int16_t
in_cksum(u_int16_t *addr, int len)
{

	return ~in_cksum2(0, addr, len);
}

/*
 * Checksum routine for Internet Protocol family headers (C Version)
 */
u_int16_t
in_cksum2(u_int16_t seed, u_int16_t *addr, int len)
{
	int nleft = len;
	u_int16_t *w = addr;
	union {
		u_int16_t w;
		u_int8_t b[2];
	} answer;
	int32_t sum = seed;

	/*
	 *  Our algorithm is simple, using a 32 bit accumulator (sum),
	 *  we add sequential 16 bit words to it, and at the end, fold
	 *  back all the carry bits from the top 16 bits into the lower
	 *  16 bits.
	 */
	while (nleft > 1)  {
		sum += *w++;
		nleft -= 2;
	}

	/* mop up an odd byte, if necessary */
	if (nleft == 1) {
		answer.b[0] = *(u_char *)w;
		answer.b[1] = 0;
		sum += answer.w;
	}

	/*
	 * add back carry outs from top 16 bits to low 16 bits
	 */
	sum = (sum >> 16) + (sum & 0xffff);	/* add hi 16 to low 16 */
	sum += (sum >> 16);			/* add carry */
	answer.w = sum;				/* truncate to 16 bits */
	return (answer.w);
}

/*
 * Subtract 2 timeval structs:  out = out - in.
 * Out is assumed to be >= in.
 */
void
tvsub(struct timeval *out, struct timeval *in)
{

	if ((out->tv_usec -= in->tv_usec) < 0)   {
		--out->tv_sec;
		out->tv_usec += 1000000;
	}
	out->tv_sec -= in->tv_sec;
}

/*
 * Construct an Internet address representation.
 * If the nflag has been supplied, give
 * numeric value, otherwise try for symbolic name.
 */
char *
inetname(struct in_addr in)
{
	char *cp;
	struct hostent *hp;
	static int first = 1;
	static char domain[MAXHOSTNAMELEN + 1], line[MAXHOSTNAMELEN + 1];

	if (first && !nflag) {
		int rv;

		first = 0;
		rv = gethostname(domain, sizeof domain);
		if (rv == 0 && (cp = strchr(domain, '.')) != NULL) {
			(void)strlcpy(domain, cp + 1, sizeof(domain));
		} else
			domain[0] = '\0';
	}
	if (!nflag && in.s_addr != INADDR_ANY) {
		hp = gethostbyaddr((char *)&in, sizeof(in), AF_INET);
		if (hp != NULL) {
			if ((cp = strchr(hp->h_name, '.')) != NULL &&
			    strcmp(cp + 1, domain) == 0)
				*cp = '\0';
			(void)strlcpy(line, hp->h_name, sizeof(line));
			return (line);
		}
	}
	return (inet_ntoa(in));
}

struct hostinfo *
gethostinfo(char *hostname)
{
	int n;
	struct hostent *hp;
	struct hostinfo *hi;
	char **p;
	u_int32_t *ap;
	struct in_addr addr;

	hi = calloc(1, sizeof(*hi));
	if (hi == NULL) {
		Fprintf(stderr, "%s: calloc %s\n", prog, strerror(errno));
		exit(1);
	}
	if (inet_aton(hostname, &addr) != 0) {
		hi->name = strdup(hostname);
		if (!hi->name) {
			Fprintf(stderr, "%s: strdup %s\n", prog,
			    strerror(errno));
			exit(1);
		}
		hi->n = 1;
		hi->addrs = calloc(1, sizeof(hi->addrs[0]));
		if (hi->addrs == NULL) {
			Fprintf(stderr, "%s: calloc %s\n",
			    prog, strerror(errno));
			exit(1);
		}
		hi->addrs[0] = addr.s_addr;
		return (hi);
	}

	hp = gethostbyname(hostname);
	if (hp == NULL) {
		Fprintf(stderr, "%s: unknown host %s\n", prog, hostname);
		exit(1);
	}
	if (hp->h_addrtype != AF_INET || hp->h_length != 4) {
		Fprintf(stderr, "%s: bad host %s\n", prog, hostname);
		exit(1);
	}
	hi->name = strdup(hp->h_name);
	if (!hi->name) {
		Fprintf(stderr, "%s: strdup %s\n", prog, strerror(errno));
		exit(1);
	}
	for (n = 0, p = hp->h_addr_list; *p != NULL; ++n, ++p)
		continue;
	hi->n = n;
	hi->addrs = calloc(n, sizeof(hi->addrs[0]));
	if (hi->addrs == NULL) {
		Fprintf(stderr, "%s: calloc %s\n", prog, strerror(errno));
		exit(1);
	}
	for (ap = hi->addrs, p = hp->h_addr_list; *p != NULL; ++ap, ++p)
		memcpy(ap, *p, sizeof(*ap));
	return (hi);
}

void
freehostinfo(struct hostinfo *hi)
{
	if (hi->name != NULL) {
		free(hi->name);
		hi->name = NULL;
	}
	free((char *)hi->addrs);
	free((char *)hi);
}

void
getaddr(u_int32_t *ap, char *hostname)
{
	struct hostinfo *hi;

	hi = gethostinfo(hostname);
	*ap = hi->addrs[0];
	freehostinfo(hi);
}

void
setsin(struct sockaddr_in *sin, u_int32_t addr)
{

	memset(sin, 0, sizeof(*sin));
#ifdef HAVE_SOCKADDR_SA_LEN
	sin->sin_len = sizeof(*sin);
#endif
	sin->sin_family = AF_INET;
	sin->sin_addr.s_addr = addr;
}

/* String to value with optional min and max. Handles decimal and hex. */
int
str2val(const char *str, const char *what, int mi, int ma)
{
	const char *cp;
	long val;
	char *ep;

	errno = 0;
	ep = NULL;
	if (str[0] == '0' && (str[1] == 'x' || str[1] == 'X')) {
		cp = str + 2;
		val = strtol(cp, &ep, 16);
	} else
		val = strtol(str, &ep, 10);
	if (errno || str[0] == '\0' || *ep != '\0') {
		Fprintf(stderr, "%s: \"%s\" bad value for %s \n",
		    prog, str, what);
		exit(1);
	}
	if (val < mi && mi >= 0) {
		if (mi == 0)
			Fprintf(stderr, "%s: %s must be >= %d\n",
			    prog, what, mi);
		else
			Fprintf(stderr, "%s: %s must be > %d\n",
			    prog, what, mi - 1);
		exit(1);
	}
	if (val > ma && ma >= 0) {
		Fprintf(stderr, "%s: %s must be <= %d\n", prog, what, ma);
		exit(1);
	}
	return ((int)val);
}

__dead void
usage(void)
{
	extern char version[];

	Fprintf(stderr, "Version %s\n", version);
	Fprintf(stderr, "usage: %s [-adDFPIlMnrvx] [-g gateway] [-i iface] \
[-f first_ttl]\n\t[-m max_ttl] [-p port] [-q nqueries] [-s src_addr] [-t tos]\n\t\
[-w waittime] [-A as_server] host [packetlen]\n",
	    prog);
	exit(1);
}

/*
 * Received ICMP unreachable (fragmentation required and DF set).
 * If the ICMP error was from a "new" router, it'll contain the next-hop
 * MTU that we should use next.  Otherwise we'll just keep going in the
 * mtus[] table, trying until we hit a valid MTU.
 */


void
frag_err()
{
        int i;

        if (nextmtu > 0 && nextmtu < packlen) {
                Printf("\nfragmentation required and DF set, "
		     "next hop MTU = %d\n",
                        nextmtu);
                packlen = nextmtu;
                for (i = 0; mtus[i] > 0; i++) {
                        if (mtus[i] < nextmtu) {
                                mtuptr = &mtus[i];    /* next one to try */
                                break;
                        }
                }
        } else {
                Printf("\nfragmentation required and DF set. ");
		if (nextmtu)
			Printf("\nBogus next hop MTU = %d > last MTU = %d. ",
			    nextmtu, packlen);
                packlen = *mtuptr++;
		Printf("Trying new MTU = %d\n", packlen);
        }
	resize_packet();
}

int
find_local_ip(struct sockaddr_in *from, struct sockaddr_in *to)
{
	int sock;
	struct sockaddr_in help;
	socklen_t help_len;

	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0) return (0);

	help.sin_family = AF_INET;
	/*
	 * At this point the port number doesn't matter
	 * since it only has to be greater than zero.
	 */
	help.sin_port = 42;
	help.sin_addr.s_addr = to->sin_addr.s_addr;
	if (connect(sock, (struct sockaddr *)&help, sizeof(help)) < 0) {
		(void)close(sock);
		return (0);
	}

	help_len = sizeof(help);
	if (getsockname(sock, (struct sockaddr *)&help, &help_len) < 0 ||
	    help_len != sizeof(help) ||
	    help.sin_addr.s_addr == INADDR_ANY) {
		(void)close(sock);
		return (0);
	}

	(void)close(sock);
	setsin(from, help.sin_addr.s_addr);
	return (1);
}

#ifdef IPSEC
#ifdef IPSEC_POLICY_IPSEC
int
setpolicy(so, policy)
	int so;
	char *policy;
{
	char *buf;

	buf = ipsec_set_policy(policy, strlen(policy));
	if (buf == NULL) {
		Fprintf(stderr, "%s: %s\n", prog, ipsec_strerror());
		return -1;
	}
	(void)setsockopt(so, IPPROTO_IP, IP_IPSEC_POLICY,
		buf, ipsec_get_policylen(buf));

	free(buf);

	return 0;
}
#endif
#endif