xref: /freebsd/usr.sbin/traceroute6/traceroute6.c (revision c70906519af35070e22b5833c478bbb8151b04f9)

/*	$KAME: traceroute6.c,v 1.68 2004/01/25 11:16:12 suz Exp $	*/

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project 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 BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Van Jacobson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1990, 1993\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)traceroute.c	8.1 (Berkeley) 6/6/93";
#endif
static const char rcsid[] =
  "$FreeBSD$";
#endif /* not lint */

/*
 * 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 an 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@helios.ee.lbl.gov)
 *     Tue Dec 20 03:50:13 PST 1988
 */

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

#include <netinet/in.h>

#include <arpa/inet.h>

#include <libcasper.h>
#include <casper/cap_dns.h>
#include <capsicum_helpers.h>

#include <netdb.h>
#include <stdio.h>
#include <err.h>
#ifdef HAVE_POLL
#include <poll.h>
#endif
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet/sctp.h>
#include <netinet/sctp_header.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>

#ifdef IPSEC
#include <net/route.h>
#include <netipsec/ipsec.h>
#endif

#include "as.h"

#define DUMMY_PORT 10010

#define	MAXPACKET	65535	/* max ip packet size */

static u_char	packet[512];		/* last inbound (icmp) packet */
static char 	*outpacket;		/* last output packet */

int	main(int, char *[]);
int	wait_for_reply(int, struct msghdr *);
#if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC)
int	setpolicy(int so, char *policy);
#endif
void	send_probe(int, u_long);
void	*get_uphdr(struct ip6_hdr *, u_char *);
void	capdns_open(void);
int	get_hoplim(struct msghdr *);
double	deltaT(struct timeval *, struct timeval *);
const char *pr_type(int);
int	packet_ok(struct msghdr *, int, int, u_char *, u_char *);
void	print(struct msghdr *, int);
const char *inetname(struct sockaddr *);
u_int32_t sctp_crc32c(void *, u_int32_t);
u_int16_t in_cksum(u_int16_t *addr, int);
u_int16_t udp_cksum(struct sockaddr_in6 *, struct sockaddr_in6 *,
    void *, u_int32_t);
u_int16_t tcp_chksum(struct sockaddr_in6 *, struct sockaddr_in6 *,
    void *, u_int32_t);
void	usage(void);

static int rcvsock;			/* receive (icmp) socket file descriptor */
static int sndsock;			/* send (raw/udp) socket file descriptor */

static struct msghdr rcvmhdr;
static struct iovec rcviov[2];
static int rcvhlim;
static struct in6_pktinfo *rcvpktinfo;

static struct sockaddr_in6 Src, Dst, Rcv;
static u_long datalen = 20;			/* How much data */
#define	ICMP6ECHOLEN	8
/* XXX: 2064 = 127(max hops in type 0 rthdr) * sizeof(ip6_hdr) + 16(margin) */
static char rtbuf[2064];
static struct ip6_rthdr *rth;
static struct cmsghdr *cmsg;

static char *source = NULL;
static char *hostname;

static cap_channel_t *capdns;

static u_long nprobes = 3;
static u_long first_hop = 1;
static u_long max_hops = 30;
static u_int16_t srcport;
static u_int16_t port = 32768+666;	/* start udp dest port # for probe packets */
static u_int16_t ident;
static int tclass = -1;
static int options;			/* socket options */
static int verbose;
static int waittime = 5;		/* time to wait for response (in seconds) */
static int nflag;			/* print addresses numerically */
static int useproto = IPPROTO_UDP;	/* protocol to use to send packet */
static int lflag;			/* print both numerical address & hostname */
static int as_path;			/* print as numbers for each hop */
static char *as_server = NULL;
static void *asn;

int
main(int argc, char *argv[])
{
	int mib[4] = { CTL_NET, PF_INET6, IPPROTO_IPV6, IPV6CTL_DEFHLIM };
	char hbuf[NI_MAXHOST], src0[NI_MAXHOST], *ep;
	int ch, i, on = 1, seq, rcvcmsglen, error;
	struct addrinfo hints, *res;
	static u_char *rcvcmsgbuf;
	u_long probe, hops, lport, ltclass;
	struct hostent *hp;
	size_t size, minlen;
	uid_t uid;
	u_char type, code;
#if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC)
	char ipsec_inpolicy[] = "in bypass";
	char ipsec_outpolicy[] = "out bypass";
#endif
	cap_rights_t rights;

	capdns_open();

	/*
	 * Receive ICMP
	 */
	if ((rcvsock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0) {
		perror("socket(ICMPv6)");
		exit(5);
	}

	size = sizeof(i);
	(void) sysctl(mib, sizeof(mib)/sizeof(mib[0]), &i, &size, NULL, 0);
	max_hops = i;

	/* specify to tell receiving interface */
#ifdef IPV6_RECVPKTINFO
	if (setsockopt(rcvsock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on,
	    sizeof(on)) < 0)
		err(1, "setsockopt(IPV6_RECVPKTINFO)");
#else  /* old adv. API */
	if (setsockopt(rcvsock, IPPROTO_IPV6, IPV6_PKTINFO, &on,
	    sizeof(on)) < 0)
		err(1, "setsockopt(IPV6_PKTINFO)");
#endif

	/* specify to tell value of hoplimit field of received IP6 hdr */
#ifdef IPV6_RECVHOPLIMIT
	if (setsockopt(rcvsock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on,
	    sizeof(on)) < 0)
		err(1, "setsockopt(IPV6_RECVHOPLIMIT)");
#else  /* old adv. API */
	if (setsockopt(rcvsock, IPPROTO_IPV6, IPV6_HOPLIMIT, &on,
	    sizeof(on)) < 0)
		err(1, "setsockopt(IPV6_HOPLIMIT)");
#endif

	seq = 0;
	ident = htons(getpid() & 0xffff); /* same as ping6 */

	while ((ch = getopt(argc, argv, "aA:df:g:Ilm:nNp:q:rs:St:TUvw:")) != -1)
		switch (ch) {
		case 'a':
			as_path = 1;
			break;
		case 'A':
			as_path = 1;
			as_server = optarg;
			break;
		case 'd':
			options |= SO_DEBUG;
			break;
		case 'f':
			ep = NULL;
			errno = 0;
			first_hop = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep || first_hop > 255) {
				fprintf(stderr,
				    "traceroute6: invalid min hoplimit.\n");
				exit(1);
			}
			break;
		case 'g':
			/* XXX use after capability mode is entered */
			hp = getipnodebyname(optarg, AF_INET6, 0, &h_errno);
			if (hp == NULL) {
				fprintf(stderr,
				    "traceroute6: unknown host %s\n", optarg);
				exit(1);
			}
			if (rth == NULL) {
				/*
				 * XXX: We can't detect the number of
				 * intermediate nodes yet.
				 */
				if ((rth = inet6_rth_init((void *)rtbuf,
				    sizeof(rtbuf), IPV6_RTHDR_TYPE_0,
				    0)) == NULL) {
					fprintf(stderr,
					    "inet6_rth_init failed.\n");
					exit(1);
				}
			}
			if (inet6_rth_add((void *)rth,
			    (struct in6_addr *)hp->h_addr)) {
				fprintf(stderr,
				    "inet6_rth_add failed for %s\n",
				    optarg);
				exit(1);
			}
			freehostent(hp);
			break;
		case 'I':
			useproto = IPPROTO_ICMPV6;
			break;
		case 'l':
			lflag++;
			break;
		case 'm':
			ep = NULL;
			errno = 0;
			max_hops = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep || max_hops > 255) {
				fprintf(stderr,
				    "traceroute6: invalid max hoplimit.\n");
				exit(1);
			}
			break;
		case 'n':
			nflag++;
			break;
		case 'N':
			useproto = IPPROTO_NONE;
			break;
		case 'p':
			ep = NULL;
			errno = 0;
			lport = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep) {
				fprintf(stderr, "traceroute6: invalid port.\n");
				exit(1);
			}
			if (lport == 0 || lport != (lport & 0xffff)) {
				fprintf(stderr,
				    "traceroute6: port out of range.\n");
				exit(1);
			}
			port = lport & 0xffff;
			break;
		case 'q':
			ep = NULL;
			errno = 0;
			nprobes = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep) {
				fprintf(stderr,
				    "traceroute6: invalid nprobes.\n");
				exit(1);
			}
			if (nprobes < 1) {
				fprintf(stderr,
				    "traceroute6: nprobes must be >0.\n");
				exit(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 'S':
			useproto = IPPROTO_SCTP;
			break;
		case 't':
			ep = NULL;
			errno = 0;
			ltclass = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep || ltclass > 255) {
				fprintf(stderr,
				    "traceroute6: invalid traffic class.\n");
				exit(1);
			}
			tclass = (int)ltclass;
			break;
		case 'T':
			useproto = IPPROTO_TCP;
			break;
		case 'U':
			useproto = IPPROTO_UDP;
			break;
		case 'v':
			verbose++;
			break;
		case 'w':
			ep = NULL;
			errno = 0;
			waittime = strtoul(optarg, &ep, 0);
			if (errno || !*optarg || *ep) {
				fprintf(stderr,
				    "traceroute6: invalid wait time.\n");
				exit(1);
			}
			if (waittime < 1) {
				fprintf(stderr,
				    "traceroute6: wait must be >= 1 sec.\n");
				exit(1);
			}
			break;
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	/*
	 * Open socket to send probe packets.
	 */
	switch (useproto) {
	case IPPROTO_ICMPV6:
		sndsock = rcvsock;
		break;
	case IPPROTO_NONE:
	case IPPROTO_SCTP:
	case IPPROTO_TCP:
	case IPPROTO_UDP:
		if ((sndsock = socket(AF_INET6, SOCK_RAW, useproto)) < 0) {
			perror("socket(SOCK_RAW)");
			exit(5);
		}
		break;
	default:
		fprintf(stderr, "traceroute6: unknown probe protocol %d\n",
		    useproto);
		exit(5);
	}
	if (max_hops < first_hop) {
		fprintf(stderr,
		    "traceroute6: max hoplimit must be larger than first hoplimit.\n");
		exit(1);
	}

	/* revoke privs */
	uid = getuid();
	if (setresuid(uid, uid, uid) == -1) {
		perror("setresuid");
		exit(1);
	}

	if (tclass != -1) {
		if (setsockopt(sndsock, IPPROTO_IPV6, IPV6_TCLASS, &tclass,
		    sizeof(int)) == -1) {
			perror("setsockopt(IPV6_TCLASS)");
			exit(7);
		}
	}

	if (argc < 1 || argc > 2)
		usage();

#if 1
	setvbuf(stdout, NULL, _IOLBF, BUFSIZ);
#else
	setlinebuf(stdout);
#endif

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_INET6;
	hints.ai_socktype = SOCK_RAW;
	hints.ai_protocol = IPPROTO_ICMPV6;
	hints.ai_flags = AI_CANONNAME;

	error = cap_getaddrinfo(capdns, *argv, NULL, &hints, &res);

	if (error) {
		fprintf(stderr,
		    "traceroute6: %s\n", gai_strerror(error));
		exit(1);
	}
	if (res->ai_addrlen != sizeof(Dst)) {
		fprintf(stderr,
		    "traceroute6: size of sockaddr mismatch\n");
		exit(1);
	}
	memcpy(&Dst, res->ai_addr, res->ai_addrlen);
	hostname = res->ai_canonname ? strdup(res->ai_canonname) : *argv;
	if (!hostname) {
		fprintf(stderr, "traceroute6: not enough core\n");
		exit(1);
	}
	if (res->ai_next) {
		if (cap_getnameinfo(capdns, res->ai_addr, res->ai_addrlen, hbuf,
		    sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
			strlcpy(hbuf, "?", sizeof(hbuf));
		fprintf(stderr, "traceroute6: Warning: %s has multiple "
		    "addresses; using %s\n", hostname, hbuf);
	}
	freeaddrinfo(res);
	if (*++argv) {
		ep = NULL;
		errno = 0;
		datalen = strtoul(*argv, &ep, 0);
		if (errno || *ep) {
			fprintf(stderr,
			    "traceroute6: invalid packet length.\n");
			exit(1);
		}
	}
	switch (useproto) {
	case IPPROTO_ICMPV6:
		minlen = ICMP6ECHOLEN;
		break;
	case IPPROTO_UDP:
		minlen = sizeof(struct udphdr);
		break;
	case IPPROTO_NONE:
		minlen = 0;
		datalen = 0;
		break;
	case IPPROTO_SCTP:
		minlen = sizeof(struct sctphdr);
		break;
	case IPPROTO_TCP:
		minlen = sizeof(struct tcphdr);
		break;
	default:
		fprintf(stderr, "traceroute6: unknown probe protocol %d.\n",
		    useproto);
		exit(1);
	}
	if (datalen < minlen)
		datalen = minlen;
	else if (datalen >= MAXPACKET) {
		fprintf(stderr,
		    "traceroute6: packet size must be %zu <= s < %d.\n",
		    minlen, MAXPACKET);
		exit(1);
	}
	if ((useproto == IPPROTO_SCTP) && (datalen & 3)) {
		fprintf(stderr,
		    "traceroute6: packet size must be a multiple of 4.\n");
		exit(1);
	}
	outpacket = malloc(datalen);
	if (!outpacket) {
		perror("malloc");
		exit(1);
	}
	(void) bzero((char *)outpacket, datalen);

	/* initialize msghdr for receiving packets */
	rcviov[0].iov_base = (caddr_t)packet;
	rcviov[0].iov_len = sizeof(packet);
	rcvmhdr.msg_name = (caddr_t)&Rcv;
	rcvmhdr.msg_namelen = sizeof(Rcv);
	rcvmhdr.msg_iov = rcviov;
	rcvmhdr.msg_iovlen = 1;
	rcvcmsglen = CMSG_SPACE(sizeof(struct in6_pktinfo)) +
	    CMSG_SPACE(sizeof(int));
	if ((rcvcmsgbuf = malloc(rcvcmsglen)) == NULL) {
		fprintf(stderr, "traceroute6: malloc failed\n");
		exit(1);
	}
	rcvmhdr.msg_control = (caddr_t) rcvcmsgbuf;
	rcvmhdr.msg_controllen = rcvcmsglen;

	if (options & SO_DEBUG)
		(void) setsockopt(rcvsock, SOL_SOCKET, SO_DEBUG,
		    (char *)&on, sizeof(on));
	if (options & SO_DONTROUTE)
		(void) setsockopt(rcvsock, SOL_SOCKET, SO_DONTROUTE,
		    (char *)&on, sizeof(on));
#if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC)
	/*
	 * do not raise error even if setsockopt fails, kernel may have ipsec
	 * turned off.
	 */
	if (setpolicy(rcvsock, ipsec_inpolicy) < 0)
		errx(1, "%s", ipsec_strerror());
	if (setpolicy(rcvsock, ipsec_outpolicy) < 0)
		errx(1, "%s", ipsec_strerror());
#else
    {
	int level = IPSEC_LEVEL_NONE;

	(void)setsockopt(rcvsock, IPPROTO_IPV6, IPV6_ESP_TRANS_LEVEL, &level,
	    sizeof(level));
	(void)setsockopt(rcvsock, IPPROTO_IPV6, IPV6_ESP_NETWORK_LEVEL, &level,
	    sizeof(level));
#ifdef IP_AUTH_TRANS_LEVEL
	(void)setsockopt(rcvsock, IPPROTO_IPV6, IPV6_AUTH_TRANS_LEVEL, &level,
	    sizeof(level));
#else
	(void)setsockopt(rcvsock, IPPROTO_IPV6, IPV6_AUTH_LEVEL, &level,
	    sizeof(level));
#endif
#ifdef IP_AUTH_NETWORK_LEVEL
	(void)setsockopt(rcvsock, IPPROTO_IPV6, IPV6_AUTH_NETWORK_LEVEL, &level,
	    sizeof(level));
#endif
    }
#endif /* !(IPSEC && IPSEC_POLICY_IPSEC) */

#ifdef SO_SNDBUF
	i = datalen;
	if (i == 0)
		i = 1;
	if (setsockopt(sndsock, SOL_SOCKET, SO_SNDBUF, (char *)&i,
	    sizeof(i)) < 0) {
		perror("setsockopt(SO_SNDBUF)");
		exit(6);
	}
#endif /* SO_SNDBUF */
	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));
	if (rth) {/* XXX: there is no library to finalize the header... */
		rth->ip6r_len = rth->ip6r_segleft * 2;
		if (setsockopt(sndsock, IPPROTO_IPV6, IPV6_RTHDR,
		    (void *)rth, (rth->ip6r_len + 1) << 3)) {
			fprintf(stderr, "setsockopt(IPV6_RTHDR): %s\n",
			    strerror(errno));
			exit(1);
		}
	}
#if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC)
	/*
	 * do not raise error even if setsockopt fails, kernel may have ipsec
	 * turned off.
	 */
	if (setpolicy(sndsock, ipsec_inpolicy) < 0)
		errx(1, "%s", ipsec_strerror());
	if (setpolicy(sndsock, ipsec_outpolicy) < 0)
		errx(1, "%s", ipsec_strerror());
#else
    {
	int level = IPSEC_LEVEL_BYPASS;

	(void)setsockopt(sndsock, IPPROTO_IPV6, IPV6_ESP_TRANS_LEVEL, &level,
	    sizeof(level));
	(void)setsockopt(sndsock, IPPROTO_IPV6, IPV6_ESP_NETWORK_LEVEL, &level,
	    sizeof(level));
#ifdef IP_AUTH_TRANS_LEVEL
	(void)setsockopt(sndsock, IPPROTO_IPV6, IPV6_AUTH_TRANS_LEVEL, &level,
	    sizeof(level));
#else
	(void)setsockopt(sndsock, IPPROTO_IPV6, IPV6_AUTH_LEVEL, &level,
	    sizeof(level));
#endif
#ifdef IP_AUTH_NETWORK_LEVEL
	(void)setsockopt(sndsock, IPPROTO_IPV6, IPV6_AUTH_NETWORK_LEVEL, &level,
	    sizeof(level));
#endif
    }
#endif /* !(IPSEC && IPSEC_POLICY_IPSEC) */

	/*
	 * Source selection
	 */
	bzero(&Src, sizeof(Src));
	if (source) {
		memset(&hints, 0, sizeof(hints));
		hints.ai_family = AF_INET6;
		hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
		hints.ai_flags = AI_NUMERICHOST;
		error = cap_getaddrinfo(capdns, source, "0", &hints, &res);
		if (error) {
			printf("traceroute6: %s: %s\n", source,
			    gai_strerror(error));
			exit(1);
		}
		if (res->ai_addrlen > sizeof(Src)) {
			printf("traceroute6: %s: %s\n", source,
			    gai_strerror(error));
			exit(1);
		}
		memcpy(&Src, res->ai_addr, res->ai_addrlen);
		freeaddrinfo(res);
	} else {
		struct sockaddr_in6 Nxt;
		int dummy;
		socklen_t len;

		Nxt = Dst;
		Nxt.sin6_port = htons(DUMMY_PORT);
		if (cmsg != NULL)
			bcopy(inet6_rthdr_getaddr(cmsg, 1), &Nxt.sin6_addr,
			    sizeof(Nxt.sin6_addr));
		if ((dummy = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
			perror("socket");
			exit(1);
		}
		if (connect(dummy, (struct sockaddr *)&Nxt, Nxt.sin6_len) < 0) {
			perror("connect");
			exit(1);
		}
		len = sizeof(Src);
		if (getsockname(dummy, (struct sockaddr *)&Src, &len) < 0) {
			perror("getsockname");
			exit(1);
		}
		if (cap_getnameinfo(capdns, (struct sockaddr *)&Src, Src.sin6_len,
		    src0, sizeof(src0), NULL, 0, NI_NUMERICHOST)) {
			fprintf(stderr, "getnameinfo failed for source\n");
			exit(1);
		}
		source = src0;
		close(dummy);
	}

	Src.sin6_port = htons(0);
	if (bind(sndsock, (struct sockaddr *)&Src, Src.sin6_len) < 0) {
		perror("bind");
		exit(1);
	}

	{
		socklen_t len;

		len = sizeof(Src);
		if (getsockname(sndsock, (struct sockaddr *)&Src, &len) < 0) {
			perror("getsockname");
			exit(1);
		}
		srcport = ntohs(Src.sin6_port);
	}

	if (as_path) {
		asn = as_setup(as_server);
		if (asn == NULL) {
			fprintf(stderr,
			    "traceroute6: as_setup failed, AS# lookups"
			    " disabled\n");
			(void)fflush(stderr);
			as_path = 0;
		}
	}

	/*
	 * Message to users
	 */
	if (cap_getnameinfo(capdns, (struct sockaddr *)&Dst, Dst.sin6_len, hbuf,
	    sizeof(hbuf), NULL, 0, NI_NUMERICHOST))
		strlcpy(hbuf, "(invalid)", sizeof(hbuf));
	fprintf(stderr, "traceroute6");
	fprintf(stderr, " to %s (%s)", hostname, hbuf);
	if (source)
		fprintf(stderr, " from %s", source);
	fprintf(stderr, ", %lu hops max, %lu byte packets\n",
	    max_hops,
	    datalen + ((useproto == IPPROTO_UDP) ? sizeof(struct udphdr) : 0));
	(void) fflush(stderr);

	if (first_hop > 1)
		printf("Skipping %lu intermediate hops\n", first_hop - 1);

	if (connect(sndsock, (struct sockaddr *)&Dst,
	    sizeof(Dst)) != 0) {
		fprintf(stderr, "connect: %s\n", strerror(errno));
		exit(1);
	}

	/*
	 * Here we enter capability mode. Further down access to global
	 * namespaces (e.g filesystem) is restricted (see capsicum(4)).
	 * We must connect(2) our socket before this point.
	 */

	if (caph_enter_casper() < 0) {
		fprintf(stderr, "caph_enter_casper: %s\n", strerror(errno));
		exit(1);
	}

	cap_rights_init(&rights, CAP_SEND, CAP_SETSOCKOPT);
	if (caph_rights_limit(sndsock, &rights) < 0) {
		fprintf(stderr, "caph_rights_limit sndsock: %s\n",
		    strerror(errno));
		exit(1);
	}

	/*
	 * Main loop
	 */
	for (hops = first_hop; hops <= max_hops; ++hops) {
		struct in6_addr lastaddr;
		int got_there = 0;
		unsigned unreachable = 0;

		printf("%2lu ", hops);
		bzero(&lastaddr, sizeof(lastaddr));
		for (probe = 0; probe < nprobes; ++probe) {
			int cc;
			struct timeval t1, t2;

			(void) gettimeofday(&t1, NULL);
			send_probe(++seq, hops);
			while ((cc = wait_for_reply(rcvsock, &rcvmhdr))) {
				(void) gettimeofday(&t2, NULL);
				if (packet_ok(&rcvmhdr, cc, seq, &type, &code)) {
					if (!IN6_ARE_ADDR_EQUAL(&Rcv.sin6_addr,
					    &lastaddr)) {
						if (probe > 0)
							fputs("\n   ", stdout);
						print(&rcvmhdr, cc);
						lastaddr = Rcv.sin6_addr;
					}
					printf("  %.3f ms", deltaT(&t1, &t2));
					if (type == ICMP6_DST_UNREACH) {
						switch (code) {
						case ICMP6_DST_UNREACH_NOROUTE:
							++unreachable;
							printf(" !N");
							break;
						case ICMP6_DST_UNREACH_ADMIN:
							++unreachable;
							printf(" !P");
							break;
						case ICMP6_DST_UNREACH_NOTNEIGHBOR:
							++unreachable;
							printf(" !S");
							break;
						case ICMP6_DST_UNREACH_ADDR:
							++unreachable;
							printf(" !A");
							break;
						case ICMP6_DST_UNREACH_NOPORT:
							if (rcvhlim >= 0 &&
							    rcvhlim <= 1)
								printf(" !");
							++got_there;
							break;
						}
					} else if (type == ICMP6_PARAM_PROB &&
					    code == ICMP6_PARAMPROB_NEXTHEADER) {
						printf(" !H");
						++got_there;
					} else if (type == ICMP6_ECHO_REPLY) {
						if (rcvhlim >= 0 &&
						    rcvhlim <= 1)
							printf(" !");
						++got_there;
					}
					break;
				} else if (deltaT(&t1, &t2) > waittime * 1000) {
					cc = 0;
					break;
				}
			}
			if (cc == 0)
				printf(" *");
			(void) fflush(stdout);
		}
		putchar('\n');
		if (got_there ||
		    (unreachable > 0 && unreachable >= ((nprobes + 1) / 2))) {
			exit(0);
		}
	}
	if (as_path)
		as_shutdown(asn);

	exit(0);
}

int
wait_for_reply(int sock, struct msghdr *mhdr)
{
#ifdef HAVE_POLL
	struct pollfd pfd[1];
	int cc = 0;

	pfd[0].fd = sock;
	pfd[0].events = POLLIN;
	pfd[0].revents = 0;

	if (poll(pfd, 1, waittime * 1000) > 0)
		cc = recvmsg(rcvsock, mhdr, 0);

	return (cc);
#else
	fd_set *fdsp;
	struct timeval wait;
	int cc = 0, fdsn;

	fdsn = howmany(sock + 1, NFDBITS) * sizeof(fd_mask);
	if ((fdsp = (fd_set *)malloc(fdsn)) == NULL)
		err(1, "malloc");
	memset(fdsp, 0, fdsn);
	FD_SET(sock, fdsp);
	wait.tv_sec = waittime; wait.tv_usec = 0;

	if (select(sock+1, fdsp, (fd_set *)0, (fd_set *)0, &wait) > 0)
		cc = recvmsg(rcvsock, mhdr, 0);

	free(fdsp);
	return (cc);
#endif
}

#if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC)
int
setpolicy(int so, char *policy)
{
	char *buf;

	buf = ipsec_set_policy(policy, strlen(policy));
	if (buf == NULL) {
		warnx("%s", ipsec_strerror());
		return -1;
	}
	(void)setsockopt(so, IPPROTO_IPV6, IPV6_IPSEC_POLICY,
	    buf, ipsec_get_policylen(buf));

	free(buf);

	return 0;
}
#endif

void
send_probe(int seq, u_long hops)
{
	struct icmp6_hdr *icp;
	struct sctphdr *sctp;
	struct udphdr *outudp;
	struct sctp_chunkhdr *chk;
	struct sctp_init_chunk *init;
	struct sctp_paramhdr *param;
	struct tcphdr *tcp;
	int i;

	i = hops;
	if (setsockopt(sndsock, IPPROTO_IPV6, IPV6_UNICAST_HOPS,
	    (char *)&i, sizeof(i)) < 0) {
		perror("setsockopt IPV6_UNICAST_HOPS");
	}

	Dst.sin6_port = htons(port + seq);

	switch (useproto) {
	case IPPROTO_ICMPV6:
		icp = (struct icmp6_hdr *)outpacket;

		icp->icmp6_type = ICMP6_ECHO_REQUEST;
		icp->icmp6_code = 0;
		icp->icmp6_cksum = 0;
		icp->icmp6_id = ident;
		icp->icmp6_seq = htons(seq);
		break;
	case IPPROTO_UDP:
		outudp = (struct udphdr *) outpacket;
		outudp->uh_sport = htons(ident);
		outudp->uh_dport = htons(port+seq);
		outudp->uh_ulen = htons(datalen);
		outudp->uh_sum = udp_cksum(&Src, &Dst, outpacket, datalen);
		break;
	case IPPROTO_NONE:
		/* No space for anything. No harm as seq/tv32 are decorative. */
		break;
	case IPPROTO_SCTP:
		sctp = (struct sctphdr *)outpacket;

		sctp->src_port = htons(ident);
		sctp->dest_port = htons(port + seq);
		if (datalen >= (u_long)(sizeof(struct sctphdr) +
		    sizeof(struct sctp_init_chunk))) {
			sctp->v_tag = 0;
		} else {
			sctp->v_tag = (sctp->src_port << 16) | sctp->dest_port;
		}
		sctp->checksum = htonl(0);
		if (datalen >= (u_long)(sizeof(struct sctphdr) +
		    sizeof(struct sctp_init_chunk))) {
			/*
			 * Send a packet containing an INIT chunk. This works
			 * better in case of firewalls on the path, but
			 * results in a probe packet containing at least
			 * 32 bytes of payload. For shorter payloads, use
			 * SHUTDOWN-ACK chunks.
			 */
			init = (struct sctp_init_chunk *)(sctp + 1);
			init->ch.chunk_type = SCTP_INITIATION;
			init->ch.chunk_flags = 0;
			init->ch.chunk_length = htons((u_int16_t)(datalen -
			    sizeof(struct sctphdr)));
			init->init.initiate_tag = (sctp->src_port << 16) |
			    sctp->dest_port;
			init->init.a_rwnd = htonl(1500);
			init->init.num_outbound_streams = htons(1);
			init->init.num_inbound_streams = htons(1);
			init->init.initial_tsn = htonl(0);
			if (datalen >= (u_long)(sizeof(struct sctphdr) +
			    sizeof(struct sctp_init_chunk) +
			    sizeof(struct sctp_paramhdr))) {
				param = (struct sctp_paramhdr *)(init + 1);
				param->param_type = htons(SCTP_PAD);
				param->param_length =
				    htons((u_int16_t)(datalen -
				    sizeof(struct sctphdr) -
				    sizeof(struct sctp_init_chunk)));
			}
		} else {
			/*
			 * Send a packet containing a SHUTDOWN-ACK chunk,
			 * possibly followed by a PAD chunk.
			 */
			if (datalen >= (u_long)(sizeof(struct sctphdr) +
			    sizeof(struct sctp_chunkhdr))) {
				chk = (struct sctp_chunkhdr *)(sctp + 1);
				chk->chunk_type = SCTP_SHUTDOWN_ACK;
				chk->chunk_flags = 0;
				chk->chunk_length = htons(4);
			}
			if (datalen >= (u_long)(sizeof(struct sctphdr) +
			    2 * sizeof(struct sctp_chunkhdr))) {
				chk = chk + 1;
				chk->chunk_type = SCTP_PAD_CHUNK;
				chk->chunk_flags = 0;
				chk->chunk_length = htons((u_int16_t)(datalen -
				    sizeof(struct sctphdr) -
				    sizeof(struct sctp_chunkhdr)));
			}
		}
		sctp->checksum = sctp_crc32c(outpacket, datalen);
		break;
	case IPPROTO_TCP:
		tcp = (struct tcphdr *)outpacket;

		tcp->th_sport = htons(ident);
		tcp->th_dport = htons(port + seq);
		tcp->th_seq = (tcp->th_sport << 16) | tcp->th_dport;
		tcp->th_ack = 0;
		tcp->th_off = 5;
		tcp->th_flags = TH_SYN;
		tcp->th_sum = 0;
		tcp->th_sum = tcp_chksum(&Src, &Dst, outpacket, datalen);
		break;
	default:
		fprintf(stderr, "Unknown probe protocol %d.\n", useproto);
		exit(1);
	}

	i = send(sndsock, (char *)outpacket, datalen, 0);
	if (i < 0 || (u_long)i != datalen)  {
		if (i < 0)
			perror("send");
		printf("traceroute6: wrote %s %lu chars, ret=%d\n",
		    hostname, datalen, i);
		(void) fflush(stdout);
	}
}

int
get_hoplim(struct msghdr *mhdr)
{
	struct cmsghdr *cm;

	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(mhdr); cm;
	    cm = (struct cmsghdr *)CMSG_NXTHDR(mhdr, cm)) {
		if (cm->cmsg_level == IPPROTO_IPV6 &&
		    cm->cmsg_type == IPV6_HOPLIMIT &&
		    cm->cmsg_len == CMSG_LEN(sizeof(int)))
			return (*(int *)CMSG_DATA(cm));
	}

	return (-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.
 */
const char *
pr_type(int t0)
{
	u_char t = t0 & 0xff;
	const char *cp;

	switch (t) {
	case ICMP6_DST_UNREACH:
		cp = "Destination Unreachable";
		break;
	case ICMP6_PACKET_TOO_BIG:
		cp = "Packet Too Big";
		break;
	case ICMP6_TIME_EXCEEDED:
		cp = "Time Exceeded";
		break;
	case ICMP6_PARAM_PROB:
		cp = "Parameter Problem";
		break;
	case ICMP6_ECHO_REQUEST:
		cp = "Echo Request";
		break;
	case ICMP6_ECHO_REPLY:
		cp = "Echo Reply";
		break;
	case ICMP6_MEMBERSHIP_QUERY:
		cp = "Group Membership Query";
		break;
	case ICMP6_MEMBERSHIP_REPORT:
		cp = "Group Membership Report";
		break;
	case ICMP6_MEMBERSHIP_REDUCTION:
		cp = "Group Membership Reduction";
		break;
	case ND_ROUTER_SOLICIT:
		cp = "Router Solicitation";
		break;
	case ND_ROUTER_ADVERT:
		cp = "Router Advertisement";
		break;
	case ND_NEIGHBOR_SOLICIT:
		cp = "Neighbor Solicitation";
		break;
	case ND_NEIGHBOR_ADVERT:
		cp = "Neighbor Advertisement";
		break;
	case ND_REDIRECT:
		cp = "Redirect";
		break;
	default:
		cp = "Unknown";
		break;
	}
	return cp;
}

int
packet_ok(struct msghdr *mhdr, int cc, int seq, u_char *type, u_char *code)
{
	struct icmp6_hdr *icp;
	struct sockaddr_in6 *from = (struct sockaddr_in6 *)mhdr->msg_name;
	char *buf = (char *)mhdr->msg_iov[0].iov_base;
	struct cmsghdr *cm;
	int *hlimp;
	char hbuf[NI_MAXHOST];

#ifdef OLDRAWSOCKET
	int hlen;
	struct ip6_hdr *ip;
#endif

#ifdef OLDRAWSOCKET
	ip = (struct ip6_hdr *) buf;
	hlen = sizeof(struct ip6_hdr);
	if (cc < hlen + sizeof(struct icmp6_hdr)) {
		if (verbose) {
			if (cap_getnameinfo(capdns, (struct sockaddr *)from, from->sin6_len,
			    hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
				strlcpy(hbuf, "invalid", sizeof(hbuf));
			printf("packet too short (%d bytes) from %s\n", cc,
			    hbuf);
		}
		return (0);
	}
	cc -= hlen;
	icp = (struct icmp6_hdr *)(buf + hlen);
#else
	if (cc < (int)sizeof(struct icmp6_hdr)) {
		if (verbose) {
			if (cap_getnameinfo(capdns, (struct sockaddr *)from, from->sin6_len,
			    hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
				strlcpy(hbuf, "invalid", sizeof(hbuf));
			printf("data too short (%d bytes) from %s\n", cc, hbuf);
		}
		return (0);
	}
	icp = (struct icmp6_hdr *)buf;
#endif
	/* get optional information via advanced API */
	rcvpktinfo = NULL;
	hlimp = NULL;
	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(mhdr); cm;
	    cm = (struct cmsghdr *)CMSG_NXTHDR(mhdr, cm)) {
		if (cm->cmsg_level == IPPROTO_IPV6 &&
		    cm->cmsg_type == IPV6_PKTINFO &&
		    cm->cmsg_len ==
		    CMSG_LEN(sizeof(struct in6_pktinfo)))
			rcvpktinfo = (struct in6_pktinfo *)(CMSG_DATA(cm));

		if (cm->cmsg_level == IPPROTO_IPV6 &&
		    cm->cmsg_type == IPV6_HOPLIMIT &&
		    cm->cmsg_len == CMSG_LEN(sizeof(int)))
			hlimp = (int *)CMSG_DATA(cm);
	}
	if (rcvpktinfo == NULL || hlimp == NULL) {
		warnx("failed to get received hop limit or packet info");
#if 0
		return (0);
#else
		rcvhlim = 0;	/*XXX*/
#endif
	}
	else
		rcvhlim = *hlimp;

	*type = icp->icmp6_type;
	*code = icp->icmp6_code;
	if ((*type == ICMP6_TIME_EXCEEDED &&
	    *code == ICMP6_TIME_EXCEED_TRANSIT) ||
	    (*type == ICMP6_DST_UNREACH) ||
	    (*type == ICMP6_PARAM_PROB &&
	    *code == ICMP6_PARAMPROB_NEXTHEADER)) {
		struct ip6_hdr *hip;
		struct icmp6_hdr *icmp;
		struct sctp_init_chunk *init;
		struct sctphdr *sctp;
		struct tcphdr *tcp;
		struct udphdr *udp;
		void *up;

		hip = (struct ip6_hdr *)(icp + 1);
		if ((up = get_uphdr(hip, (u_char *)(buf + cc))) == NULL) {
			if (verbose)
				warnx("failed to get upper layer header");
			return (0);
		}
		switch (useproto) {
		case IPPROTO_ICMPV6:
			icmp = (struct icmp6_hdr *)up;
			if (icmp->icmp6_id == ident &&
			    icmp->icmp6_seq == htons(seq))
				return (1);
			break;
		case IPPROTO_UDP:
			udp = (struct udphdr *)up;
			if (udp->uh_sport == htons(ident) &&
			    udp->uh_dport == htons(port + seq))
				return (1);
			break;
		case IPPROTO_SCTP:
			sctp = (struct sctphdr *)up;
			if (sctp->src_port != htons(ident) ||
			    sctp->dest_port != htons(port + seq)) {
				break;
			}
			if (datalen >= (u_long)(sizeof(struct sctphdr) +
			    sizeof(struct sctp_init_chunk))) {
				if (sctp->v_tag != 0) {
					break;
				}
				init = (struct sctp_init_chunk *)(sctp + 1);
				/* Check the initiate tag, if available. */
				if ((char *)&init->init.a_rwnd > buf + cc) {
					return (1);
				}
				if (init->init.initiate_tag == (u_int32_t)
				    ((sctp->src_port << 16) | sctp->dest_port)) {
					return (1);
				}
			} else {
				if (sctp->v_tag ==
				    (u_int32_t)((sctp->src_port << 16) |
				    sctp->dest_port)) {
					return (1);
				}
			}
			break;
		case IPPROTO_TCP:
			tcp = (struct tcphdr *)up;
			if (tcp->th_sport == htons(ident) &&
			    tcp->th_dport == htons(port + seq) &&
			    tcp->th_seq ==
			    (tcp_seq)((tcp->th_sport << 16) | tcp->th_dport))
				return (1);
			break;
		case IPPROTO_NONE:
			return (1);
		default:
			fprintf(stderr, "Unknown probe proto %d.\n", useproto);
			break;
		}
	} else if (useproto == IPPROTO_ICMPV6 && *type == ICMP6_ECHO_REPLY) {
		if (icp->icmp6_id == ident &&
		    icp->icmp6_seq == htons(seq))
			return (1);
	}
	if (verbose) {
		char sbuf[NI_MAXHOST+1], dbuf[INET6_ADDRSTRLEN];
		u_int8_t *p;
		int i;

		if (cap_getnameinfo(capdns, (struct sockaddr *)from, from->sin6_len,
		    sbuf, sizeof(sbuf), NULL, 0, NI_NUMERICHOST) != 0)
			strlcpy(sbuf, "invalid", sizeof(sbuf));
		printf("\n%d bytes from %s to %s", cc, sbuf,
		    rcvpktinfo ? inet_ntop(AF_INET6, &rcvpktinfo->ipi6_addr,
		    dbuf, sizeof(dbuf)) : "?");
		printf(": icmp type %d (%s) code %d\n", *type, pr_type(*type),
		    *code);
		p = (u_int8_t *)(icp + 1);
#define WIDTH	16
		for (i = 0; i < cc; i++) {
			if (i % WIDTH == 0)
				printf("%04x:", i);
			if (i % 4 == 0)
				printf(" ");
			printf("%02x", p[i]);
			if (i % WIDTH == WIDTH - 1)
				printf("\n");
		}
		if (cc % WIDTH != 0)
			printf("\n");
	}
	return (0);
}

/*
 * Increment pointer until find the UDP or ICMP header.
 */
void *
get_uphdr(struct ip6_hdr *ip6, u_char *lim)
{
	u_char *cp = (u_char *)ip6, nh;
	int hlen;
	static u_char none_hdr[1]; /* Fake pointer for IPPROTO_NONE. */

	if (cp + sizeof(*ip6) > lim)
		return (NULL);

	nh = ip6->ip6_nxt;
	cp += sizeof(struct ip6_hdr);

	while (lim - cp >= (nh == IPPROTO_NONE ? 0 : 8)) {
		switch (nh) {
		case IPPROTO_ESP:
			return (NULL);
		case IPPROTO_ICMPV6:
			return (useproto == nh ? cp : NULL);
		case IPPROTO_SCTP:
		case IPPROTO_TCP:
		case IPPROTO_UDP:
			return (useproto == nh ? cp : NULL);
		case IPPROTO_NONE:
			return (useproto == nh ? none_hdr : NULL);
		case IPPROTO_FRAGMENT:
			hlen = sizeof(struct ip6_frag);
			nh = ((struct ip6_frag *)cp)->ip6f_nxt;
			break;
		case IPPROTO_AH:
			hlen = (((struct ip6_ext *)cp)->ip6e_len + 2) << 2;
			nh = ((struct ip6_ext *)cp)->ip6e_nxt;
			break;
		default:
			hlen = (((struct ip6_ext *)cp)->ip6e_len + 1) << 3;
			nh = ((struct ip6_ext *)cp)->ip6e_nxt;
			break;
		}

		cp += hlen;
	}

	return (NULL);
}

void
capdns_open()
{
	const char *types[] = { "NAME", "ADDR" };
	int families[1];
	cap_channel_t *casper;

	casper = cap_init();
	if (casper == NULL)
		errx(1, "unable to create casper process");
	capdns = cap_service_open(casper, "system.dns");
	if (capdns == NULL)
		errx(1, "unable to open system.dns service");
	if (cap_dns_type_limit(capdns, types, nitems(types)) < 0)
		errx(1, "unable to limit access to system.dns service");
	families[0] = AF_INET6;
	if (cap_dns_family_limit(capdns, families, nitems(families)) < 0)
		errx(1, "unable to limit access to system.dns service");
	cap_close(casper);
}

void
print(struct msghdr *mhdr, int cc)
{
	struct sockaddr_in6 *from = (struct sockaddr_in6 *)mhdr->msg_name;
	char hbuf[NI_MAXHOST];

	if (cap_getnameinfo(capdns, (struct sockaddr *)from, from->sin6_len,
	    hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
		strlcpy(hbuf, "invalid", sizeof(hbuf));
	if (as_path)
		printf(" [AS%u]", as_lookup(asn, hbuf, AF_INET6));
	if (nflag)
		printf(" %s", hbuf);
	else if (lflag)
		printf(" %s (%s)", inetname((struct sockaddr *)from), hbuf);
	else
		printf(" %s", inetname((struct sockaddr *)from));

	if (verbose) {
#ifdef OLDRAWSOCKET
		printf(" %d bytes to %s", cc,
		    rcvpktinfo ? inet_ntop(AF_INET6, &rcvpktinfo->ipi6_addr,
		    hbuf, sizeof(hbuf)) : "?");
#else
		printf(" %d bytes of data to %s", cc,
		    rcvpktinfo ?  inet_ntop(AF_INET6, &rcvpktinfo->ipi6_addr,
		    hbuf, sizeof(hbuf)) : "?");
#endif
	}
}

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

	if (first && !nflag) {
		first = 0;
		if (gethostname(domain, sizeof(domain)) == 0 &&
		    (cp = strchr(domain, '.')))
			(void) strlcpy(domain, cp + 1, sizeof(domain));
		else
			domain[0] = 0;
	}
	cp = NULL;
	if (!nflag) {
		if (cap_getnameinfo(capdns, sa, sa->sa_len, line, sizeof(line), NULL, 0,
		    NI_NAMEREQD) == 0) {
			if ((cp = strchr(line, '.')) &&
			    !strcmp(cp + 1, domain))
				*cp = 0;
			cp = line;
		}
	}
	if (cp)
		return cp;

	if (cap_getnameinfo(capdns, sa, sa->sa_len, line, sizeof(line), NULL, 0,
	    NI_NUMERICHOST) != 0)
		strlcpy(line, "invalid", sizeof(line));
	return line;
}

/*
 * CRC32C routine for the Stream Control Transmission Protocol
 */

#define CRC32C(c, d) (c = (c>>8) ^ crc_c[(c^(d))&0xFF])

static u_int32_t crc_c[256] = {
	0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
	0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
	0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
	0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
	0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
	0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
	0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
	0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
	0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
	0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
	0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
	0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
	0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
	0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
	0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
	0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
	0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
	0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
	0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
	0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
	0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
	0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
	0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
	0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
	0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
	0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
	0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
	0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
	0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
	0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
	0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
	0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
	0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
	0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
	0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
	0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
	0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
	0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
	0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
	0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
	0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
	0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
	0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
	0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
	0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
	0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
	0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
	0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
	0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
	0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
	0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
	0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
	0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
	0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
	0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
	0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
	0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
	0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
	0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
	0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
	0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
	0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
	0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
	0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351
};

u_int32_t
sctp_crc32c(void *pack, u_int32_t len)
{
	u_int32_t i, crc32c;
	u_int8_t byte0, byte1, byte2, byte3;
	u_int8_t *buf = (u_int8_t *)pack;

	crc32c = ~0;
	for (i = 0; i < len; i++)
		CRC32C(crc32c, buf[i]);
	crc32c = ~crc32c;
	byte0  = crc32c & 0xff;
	byte1  = (crc32c>>8) & 0xff;
	byte2  = (crc32c>>16) & 0xff;
	byte3  = (crc32c>>24) & 0xff;
	crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
	return htonl(crc32c);
}

u_int16_t
in_cksum(u_int16_t *addr, int len)
{
	int nleft = len;
	u_int16_t *w = addr;
	u_int16_t answer;
	int sum = 0;

	/*
	 *  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)
		sum += *(u_char *)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 = ~sum;				/* truncate to 16 bits */
	return (answer);
}

u_int16_t
udp_cksum(struct sockaddr_in6 *src, struct sockaddr_in6 *dst,
    void *payload, u_int32_t len)
{
	struct {
		struct in6_addr src;
		struct in6_addr dst;
		u_int32_t len;
		u_int8_t zero[3];
		u_int8_t next;
	} pseudo_hdr;
	u_int16_t sum[2];

	pseudo_hdr.src = src->sin6_addr;
	pseudo_hdr.dst = dst->sin6_addr;
	pseudo_hdr.len = htonl(len);
	pseudo_hdr.zero[0] = 0;
	pseudo_hdr.zero[1] = 0;
	pseudo_hdr.zero[2] = 0;
	pseudo_hdr.next = IPPROTO_UDP;

	sum[1] = in_cksum((u_int16_t *)&pseudo_hdr, sizeof(pseudo_hdr));
	sum[0] = in_cksum(payload, len);

	return (~in_cksum(sum, sizeof(sum)));
}

u_int16_t
tcp_chksum(struct sockaddr_in6 *src, struct sockaddr_in6 *dst,
    void *payload, u_int32_t len)
{
	struct {
		struct in6_addr src;
		struct in6_addr dst;
		u_int32_t len;
		u_int8_t zero[3];
		u_int8_t next;
	} pseudo_hdr;
	u_int16_t sum[2];

	pseudo_hdr.src = src->sin6_addr;
	pseudo_hdr.dst = dst->sin6_addr;
	pseudo_hdr.len = htonl(len);
	pseudo_hdr.zero[0] = 0;
	pseudo_hdr.zero[1] = 0;
	pseudo_hdr.zero[2] = 0;
	pseudo_hdr.next = IPPROTO_TCP;

	sum[1] = in_cksum((u_int16_t *)&pseudo_hdr, sizeof(pseudo_hdr));
	sum[0] = in_cksum(payload, len);

	return (~in_cksum(sum, sizeof(sum)));
}

void
usage(void)
{

	fprintf(stderr,
"usage: traceroute6 [-adIlnNrSTUv] [-A as_server] [-f firsthop] [-g gateway]\n"
"       [-m hoplimit] [-p port] [-q probes] [-s src] [-w waittime] target\n"
"       [datalen]\n");
	exit(1);
}