root/usr.sbin/traceroute6/traceroute6.c
/*      $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.
 */

/*
 * 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 net.inet.ip.ttl 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), 64 hops max, 40 byte packets
 *      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), 64 hops max, 40 byte packets
 *      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@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/ip.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 *, 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 as_path;                     /* print as numbers for each hop */
static int ecnflag;                     /* ECN bleaching detection flag */
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, ecn;
#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:dEf: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 'E':
                        ecnflag = 1;
                        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':
                        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:
        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);
        }

        if (ecnflag) {
                if (tclass != -1) {
                        tclass &= ~IPTOS_ECN_MASK;
                } else {
                        tclass = 0;
                }
                tclass |= IPTOS_ECN_ECT1;
        }

        /* 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;
                }
        }
        if (as_path)
                signal(SIGPIPE, SIG_IGN);

        /*
         * 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);
        }
        cap_rights_init(&rights, CAP_RECV, CAP_EVENT);
        if (caph_rights_limit(rcvsock, &rights) < 0) {
                fprintf(stderr, "caph_rights_limit rcvsock: %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, &ecn)) {
                                        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 (ecnflag) {
                                                switch (ecn) {
                                                case IPTOS_ECN_ECT1:
                                                        printf(" (ecn=passed)");
                                                        break;
                                                case IPTOS_ECN_NOTECT:
                                                        printf(" (ecn=bleached)");
                                                        break;
                                                case IPTOS_ECN_CE:
                                                        printf(" (ecn=congested)");
                                                        break;
                                                default:
                                                        printf(" (ecn=mangled)");
                                                        break;
                                                }
                                        }
                                        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;
                                                default:
                                                        ++unreachable;
                                                        printf(" !<%d>", code & 0xff);
                                                        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 &&
            pfd[0].revents & POLLIN)
                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 = 0;
                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_set_flags(tcp, 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,
    u_char *ecn)
{
        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);
                *ecn = ntohl(hip->ip6_flow & IPV6_ECN_MASK) >> 20;
                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(void)
{
#ifdef  WITH_CASPER
        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);
#endif  /* WITH_CASPER */
}

void
print(struct msghdr *mhdr, int cc)
{
        struct sockaddr_in6 *from = (struct sockaddr_in6 *)mhdr->msg_name;
        int as, status;
        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));
        while (as_path) {
                as = as_lookup(asn, hbuf, AF_INET6, &status);
                if (status) {
                        as_shutdown(asn);
                        asn = as_setup(as_server);
                        if (asn == NULL) {
                                fprintf(stderr, "traceroute6: as_setup failed, AS# lookups"
                                                " disabled\n");
                                (void)fflush(stderr);
                                as_path = 0;
                                break;
                        }
                        else
                                continue;
                }
                printf(" [AS%u]", as);
                break;
        }
        if (nflag)
                printf(" %s", hbuf);
        else
                printf(" %s (%s)", inetname((struct sockaddr *)from), hbuf);

        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 [-adEIlnNrSTUv] [-A as_server] [-f firsthop] [-g gateway]\n"
"\t[-m hoplimit] [-p port] [-q probes] [-s src] [-t tclass]\n"
"\t[-w waittime] target [datalen]\n");
        exit(1);
}