/*      $OpenBSD: mtrace.c,v 1.41 2020/12/30 18:47:20 benno Exp $       */
/*      $NetBSD: mtrace.c,v 1.5 1995/12/10 10:57:15 mycroft Exp $       */

/*
 * mtrace.c
 *
 * This tool traces the branch of a multicast tree from a source to a
 * receiver for a particular multicast group and gives statistics
 * about packet rate and loss for each hop along the path.  It can
 * usually be invoked just as
 *
 *      mtrace source
 *
 * to trace the route from that source to the local host for a default
 * group when only the route is desired and not group-specific packet
 * counts.  See the usage line for more complex forms.
 *
 *
 * Released 4 Apr 1995.  This program was adapted by Steve Casner
 * (USC/ISI) from a prototype written by Ajit Thyagarajan (UDel and
 * Xerox PARC).  It attempts to parallel in command syntax and output
 * format the unicast traceroute program written by Van Jacobson (LBL)
 * for the parts where that makes sense.
 *
 * Copyright (c) 1998-2001.
 * The University of Southern California/Information Sciences Institute.
 * 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.
 */

#include <netdb.h>
#include <sys/time.h>
#include <string.h>
#include <poll.h>
#include <ctype.h>
#include <sys/ioctl.h>
#include "defs.h"
#include <arpa/inet.h>
#include <stdarg.h>
#ifdef SUNOS5
#include <sys/systeminfo.h>
#endif
#include <ifaddrs.h>
#include <err.h>

#define DEFAULT_TIMEOUT 3       /* How long to wait before retrying requests */
#define DEFAULT_RETRIES 3       /* How many times to try */
#define MAXHOPS UNREACHABLE     /* Don't need more hops than max metric */
#define UNICAST_TTL 255         /* TTL for unicast response */
#define MULTICAST_TTL1 64       /* Default TTL for multicast query/response */
#define MULTICAST_TTL_INC 32    /* TTL increment for increase after timeout */
#define MULTICAST_TTL_MAX 192   /* Maximum TTL allowed (protect low-BW links */

struct resp_buf {
    u_long qtime;               /* Time query was issued */
    u_long rtime;               /* Time response was received */
    int len;                    /* Number of reports or length of data */
    struct igmp igmp;           /* IGMP header */
    union {
        struct {
            struct tr_query q;          /* Query/response header */
            struct tr_resp r[MAXHOPS];  /* Per-hop reports */
        } t;
        char d[MAX_DVMRP_DATA_LEN];     /* Neighbor data */
    } u;
} base, incr[2];

#define qhdr u.t.q
#define resps u.t.r
#define ndata u.d

char names[MAXHOPS][40];
int reset[MAXHOPS];                     /* To get around 3.4 bug, ... */
int swaps[MAXHOPS];                     /* To get around 3.6 bug, ... */

int timeout = DEFAULT_TIMEOUT;
int nqueries = DEFAULT_RETRIES;
int numeric = FALSE;
int debug = 0;
int passive = FALSE;
int multicast = FALSE;
int statint = 10;
int verbose = 0;

u_int32_t defgrp;                       /* Default group if not specified */
u_int32_t query_cast;                   /* All routers multicast addr */
u_int32_t resp_cast;                    /* Mtrace response multicast addr */

u_int32_t lcl_addr = 0;                 /* This host address, in NET order */
u_int32_t dst_netmask;                  /* netmask to go with qdst */

/*
 * Query/response parameters, all initialized to zero and set later
 * to default values or from options.
 */
u_int32_t qsrc = 0;             /* Source address in the query */
u_int32_t qgrp = 0;             /* Group address in the query */
u_int32_t qdst = 0;             /* Destination (receiver) address in query */
u_char qno  = 0;                /* Max number of hops to query */
u_int32_t raddr = 0;            /* Address where response should be sent */
int    qttl = 0;                /* TTL for the query packet */
u_char rttl = 0;                /* TTL for the response packet */
u_int32_t gwy = 0;              /* User-supplied last-hop router address */
u_int32_t tdst = 0;             /* Address where trace is sent (last-hop) */

vifi_t  numvifs;                /* to keep loader happy */
                                /* (see kern.c) */

char *                  inet_name(u_int32_t addr);
u_int32_t                       host_addr(char *name);
/* u_int is promoted u_char */
char *                  proto_type(u_int type);
char *                  flag_type(u_int type);

u_int32_t                       get_netmask(int s, u_int32_t dst);
int                     get_ttl(struct resp_buf *buf);
int                     t_diff(u_long a, u_long b);
u_long                  fixtime(u_long time);
int                     send_recv(u_int32_t dst, int type, int code,
                            int tries, struct resp_buf *save);
char *                  print_host(u_int32_t addr);
char *                  print_host2(u_int32_t addr1, u_int32_t addr2);
void                    print_trace(int index, struct resp_buf *buf);
int                     what_kind(struct resp_buf *buf, char *why);
char *                  scale(int *hop);
void                    stat_line(struct tr_resp *r, struct tr_resp *s,
                            int have_next, int *res);
void                    fixup_stats(struct resp_buf *base,
                            struct resp_buf *prev, struct resp_buf *new);
int                     print_stats(struct resp_buf *base,
                            struct resp_buf *prev, struct resp_buf *new);
void                    check_vif_state(void);
u_long                  byteswap(u_long v);

int                     main(int argc, char *argv[]);



char   *
inet_name(u_int32_t addr)
{
    struct hostent *e;

    e = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET);

    return e ? e->h_name : "?";
}


u_int32_t
host_addr(char *name)
{
    struct hostent *e = NULL;
    u_int32_t  addr;
    int i, dots = 3;
    char        buf[40];
    char        *ip = name;
    char        *op = buf;

    /*
     * Undo BSD's favor -- take fewer than 4 octets as net/subnet address
     * if the name is all numeric.
     */
    for (i = sizeof(buf) - 7; i > 0; --i) {
        if (*ip == '.')
                --dots;
        else if (*ip == '\0')
                break;
        else if (!isdigit((unsigned char)*ip))
                dots = 0;  /* Not numeric, don't add zeroes */
        *op++ = *ip++;
    }
    for (i = 0; i < dots; ++i) {
        *op++ = '.';
        *op++ = '0';
    }
    *op = '\0';

    if (dots <= 0) e = gethostbyname(name);
    if (e) memcpy((char *)&addr, e->h_addr_list[0], e->h_length);
    else {
        addr = inet_addr(buf);
        if (addr == -1) {
            addr = 0;
            printf("Could not parse %s as host name or address\n", name);
        }
    }
    return addr;
}


char *
proto_type(u_int type)
{
    static char buf[80];

    switch (type) {
      case PROTO_DVMRP:
        return ("DVMRP");
      case PROTO_MOSPF:
        return ("MOSPF");
      case PROTO_PIM:
        return ("PIM");
      case PROTO_CBT:
        return ("CBT");
      default:
        (void) snprintf(buf, sizeof buf, "Unknown protocol code %d", type);
        return (buf);
    }
}


char *
flag_type(u_int type)
{
    static char buf[80];

    switch (type) {
      case TR_NO_ERR:
        return ("");
      case TR_WRONG_IF:
        return ("Wrong interface");
      case TR_PRUNED:
        return ("Prune sent upstream");
      case TR_OPRUNED:
        return ("Output pruned");
      case TR_SCOPED:
        return ("Hit scope boundary");
      case TR_NO_RTE:
        return ("No route");
      case TR_OLD_ROUTER:
        return ("Next router no mtrace");
      case TR_NO_FWD:
        return ("Not forwarding");
      case TR_NO_SPACE:
        return ("No space in packet");
      default:
        (void) snprintf(buf, sizeof buf, "Unknown error code %d", type);
        return (buf);
    }
}

/*
 * If destination is on a local net, get the netmask, else set the
 * netmask to all ones.  There are two side effects: if the local
 * address was not explicitly set, and if the destination is on a
 * local net, use that one; in either case, verify that the local
 * address is valid.
 */

u_int32_t
get_netmask(int s, u_int32_t dst)
{
    u_int32_t if_addr, if_mask;
    u_int32_t retval = 0xFFFFFFFF;
    int found = FALSE;
    struct ifaddrs *ifap, *ifa;

    if (getifaddrs(&ifap) != 0) {
        perror("getifaddrs");
        return (retval);
    }
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
        if (ifa->ifa_addr == NULL ||
            ifa->ifa_addr->sa_family != AF_INET)
                continue;
        if_addr = ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
        if_mask = ((struct sockaddr_in *)ifa->ifa_netmask)->sin_addr.s_addr;
        if ((dst & if_mask) == (if_addr & if_mask)) {
            retval = if_mask;
            if (lcl_addr == 0)
                lcl_addr = if_addr;
        }
        if (lcl_addr == if_addr)
            found = TRUE;
    }
    if (!found && lcl_addr != 0) {
        printf("Interface address is not valid\n");
        exit(1);
    }
    freeifaddrs(ifap);
    return (retval);
}


int
get_ttl(struct resp_buf *buf)
{
    int rno;
    struct tr_resp *b;
    u_int ttl;

    if (buf && (rno = buf->len) > 0) {
        b = buf->resps + rno - 1;
        ttl = b->tr_fttl;

        while (--rno > 0) {
            --b;
            if (ttl < b->tr_fttl) ttl = b->tr_fttl;
            else ++ttl;
        }
        ttl += MULTICAST_TTL_INC;
        if (ttl < MULTICAST_TTL1) ttl = MULTICAST_TTL1;
        if (ttl > MULTICAST_TTL_MAX) ttl = MULTICAST_TTL_MAX;
        return (ttl);
    } else return(MULTICAST_TTL1);
}

/*
 * Calculate the difference between two 32-bit NTP timestamps and return
 * the result in milliseconds.
 */
int
t_diff(u_long a, u_long b)
{
    int d = a - b;

    return ((d * 125) >> 13);
}

/*
 * Fixup for incorrect time format in 3.3 mrouted.
 * This is possible because (JAN_1970 mod 64K) is quite close to 32K,
 * so correct and incorrect times will be far apart.
 */
u_long
fixtime(u_long time)
{
    if (abs((int)(time-base.qtime)) > 0x3FFFFFFF)
        time = ((time & 0xFFFF0000) + (JAN_1970 << 16)) +
               ((time & 0xFFFF) << 14) / 15625;
    return (time);
}

/*
 * Swap bytes for poor little-endian machines that don't byte-swap
 */
u_long
byteswap(u_long v)
{
    return ((v << 24) | ((v & 0xff00) << 8) |
            ((v >> 8) & 0xff00) | (v >> 24));
}

int
send_recv(u_int32_t dst, int type, int code, int tries, struct resp_buf *save)
{
    struct timeval tq, tr, tv;
    struct ip *ip;
    struct igmp *igmp;
    struct tr_query *query, *rquery;
    int ipdatalen, iphdrlen, igmpdatalen;
    u_int32_t local, group;
    int datalen;
    struct pollfd pfd[1];
    int count, recvlen, dummy = 0;
    int len;
    int i;

    if (type == IGMP_MTRACE_QUERY) {
        group = qgrp;
        datalen = sizeof(struct tr_query);
    } else {
        group = htonl(MROUTED_LEVEL);
        datalen = 0;
    }
    if (IN_MULTICAST(ntohl(dst))) local = lcl_addr;
    else local = INADDR_ANY;

    /*
     * If the reply address was not explicitly specified, start off
     * with the unicast address of this host.  Then, if there is no
     * response after trying half the tries with unicast, switch to
     * the standard multicast reply address.  If the TTL was also not
     * specified, set a multicast TTL and if needed increase it for the
     * last quarter of the tries.
     */
    query = (struct tr_query *)(send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
    query->tr_raddr = raddr ? raddr : multicast ? resp_cast : lcl_addr;
    query->tr_rttl  = rttl ? rttl :
      IN_MULTICAST(ntohl(query->tr_raddr)) ? get_ttl(save) : UNICAST_TTL;
    query->tr_src   = qsrc;
    query->tr_dst   = qdst;

    for (i = tries ; i > 0; --i) {
        if (tries == nqueries && raddr == 0) {
            if (i == ((nqueries + 1) >> 1)) {
                query->tr_raddr = resp_cast;
                if (rttl == 0) query->tr_rttl = get_ttl(save);
            }
            if (i <= ((nqueries + 3) >> 2) && rttl == 0) {
                query->tr_rttl += MULTICAST_TTL_INC;
                if (query->tr_rttl > MULTICAST_TTL_MAX)
                  query->tr_rttl = MULTICAST_TTL_MAX;
            }
        }

        /*
         * Change the qid for each request sent to avoid being confused
         * by duplicate responses
         */
        query->tr_qid  = arc4random();

        /*
         * Set timer to calculate delays, then send query
         */
        gettimeofday(&tq, 0);
        send_igmp(local, dst, type, code, group, datalen);

        /*
         * Wait for response, discarding false alarms
         */
        pfd[0].fd = igmp_socket;
        pfd[0].events = POLLIN;
        while (TRUE) {
            gettimeofday(&tv, 0);
            tv.tv_sec = tq.tv_sec + timeout - tv.tv_sec;
            tv.tv_usec = tq.tv_usec - tv.tv_usec;
            if (tv.tv_usec < 0) tv.tv_usec += 1000000L, --tv.tv_sec;
            if (tv.tv_sec < 0) tv.tv_sec = tv.tv_usec = 0;

            count = poll(pfd, 1, tv.tv_sec * 1000);

            if (count == -1) {
                if (errno != EINTR) perror("poll");
                continue;
            } else if (count == 0) {
                printf("* ");
                fflush(stdout);
                break;
            }

            gettimeofday(&tr, 0);
            recvlen = recvfrom(igmp_socket, recv_buf, RECV_BUF_SIZE,
                               0, NULL, &dummy);

            if (recvlen <= 0) {
                if (recvlen && errno != EINTR) perror("recvfrom");
                continue;
            }

            if (recvlen < sizeof(struct ip)) {
                fprintf(stderr,
                        "packet too short (%u bytes) for IP header", recvlen);
                continue;
            }
            ip = (struct ip *) recv_buf;
            if (ip->ip_p == 0)  /* ignore cache creation requests */
                continue;

            iphdrlen = ip->ip_hl << 2;
            ipdatalen = ntohs(ip->ip_len) - iphdrlen;
            if (iphdrlen + ipdatalen != recvlen) {
                fprintf(stderr,
                        "packet shorter (%u bytes) than hdr+data len (%u+%u)\n",
                        recvlen, iphdrlen, ipdatalen);
                continue;
            }

            igmp = (struct igmp *) (recv_buf + iphdrlen);
            igmpdatalen = ipdatalen - IGMP_MINLEN;
            if (igmpdatalen < 0) {
                fprintf(stderr,
                        "IP data field too short (%u bytes) for IGMP from %s\n",
                        ipdatalen, inet_fmt(ip->ip_src.s_addr, s1));
                continue;
            }

            switch (igmp->igmp_type) {

              case IGMP_DVMRP:
                if (igmp->igmp_code != DVMRP_NEIGHBORS2) continue;
                len = igmpdatalen;
                /*
                 * Accept DVMRP_NEIGHBORS2 response if it comes from the
                 * address queried or if that address is one of the local
                 * addresses in the response.
                 */
                if (ip->ip_src.s_addr != dst) {
                    u_int32_t *p = (u_int32_t *)(igmp + 1);
                    u_int32_t *ep = p + (len >> 2);
                    while (p < ep) {
                        u_int32_t laddr = *p++;
                        int n = ntohl(*p++) & 0xFF;
                        if (laddr == dst) {
                            ep = p + 1;         /* ensure p < ep after loop */
                            break;
                        }
                        p += n;
                    }
                    if (p >= ep) continue;
                }
                break;

              case IGMP_MTRACE_QUERY:       /* For backward compatibility with 3.3 */
              case IGMP_MTRACE_REPLY:
                if (igmpdatalen <= QLEN) continue;
                if ((igmpdatalen - QLEN)%RLEN) {
                    printf("packet with incorrect datalen\n");
                    continue;
                }

                /*
                 * Ignore responses that don't match query.
                 */
                rquery = (struct tr_query *)(igmp + 1);
                if (rquery->tr_qid != query->tr_qid) continue;
                if (rquery->tr_src != qsrc) continue;
                if (rquery->tr_dst != qdst) continue;
                len = (igmpdatalen - QLEN)/RLEN;

                /*
                 * Ignore trace queries passing through this node when
                 * mtrace is run on an mrouter that is in the path
                 * (needed only because IGMP_MTRACE_QUERY is accepted above
                 * for backward compatibility with multicast release 3.3).
                 */
                if (igmp->igmp_type == IGMP_MTRACE_QUERY) {
                    struct tr_resp *r = (struct tr_resp *)(rquery+1) + len - 1;
                    u_int32_t smask;

                    VAL_TO_MASK(smask, r->tr_smask);
                    if (len < code && (r->tr_inaddr & smask) != (qsrc & smask)
                        && r->tr_rmtaddr != 0 && !(r->tr_rflags & 0x80))
                      continue;
                }

                /*
                 * A match, we'll keep this one.
                 */
                if (len > code) {
                    fprintf(stderr,
                            "Num hops received (%d) exceeds request (%d)\n",
                            len, code);
                }
                rquery->tr_raddr = query->tr_raddr;     /* Insure these are */
                rquery->tr_rttl = query->tr_rttl;       /* as we sent them */
                break;

              default:
                continue;
            }

            /*
             * Most of the sanity checking done at this point.
             * Return this packet we have been waiting for.
             */
            if (save) {
                save->qtime = ((tq.tv_sec + JAN_1970) << 16) +
                              (tq.tv_usec << 10) / 15625;
                save->rtime = ((tr.tv_sec + JAN_1970) << 16) +
                              (tr.tv_usec << 10) / 15625;
                save->len = len;
                bcopy((char *)igmp, (char *)&save->igmp, ipdatalen);
            }
            return (recvlen);
        }
    }
    return (0);
}

/*
 * Most of this code is duplicated elsewhere.  I'm not sure if
 * the duplication is absolutely required or not.
 *
 * Ideally, this would keep track of ongoing statistics
 * collection and print out statistics.  (& keep track
 * of h-b-h traces and only print the longest)  For now,
 * it just snoops on what traces it can.
 */
void
passive_mode(void)
{
    struct timeval tr;
    struct ip *ip;
    struct igmp *igmp;
    struct tr_resp *r;
    int ipdatalen, iphdrlen, igmpdatalen;
    int len, recvlen, dummy = 0;
    u_int32_t smask;

    if (raddr) {
        if (IN_MULTICAST(ntohl(raddr))) k_join(raddr, INADDR_ANY);
    } else k_join(htonl(0xE0000120), INADDR_ANY);

    while (1) {
        recvlen = recvfrom(igmp_socket, recv_buf, RECV_BUF_SIZE,
                           0, NULL, &dummy);
        gettimeofday(&tr,0);

        if (recvlen <= 0) {
            if (recvlen && errno != EINTR) perror("recvfrom");
            continue;
        }

        if (recvlen < sizeof(struct ip)) {
            fprintf(stderr,
                    "packet too short (%u bytes) for IP header", recvlen);
            continue;
        }
        ip = (struct ip *) recv_buf;
        if (ip->ip_p == 0)      /* ignore cache creation requests */
            continue;

        iphdrlen = ip->ip_hl << 2;
        ipdatalen = ntohs(ip->ip_len) - iphdrlen;
        if (iphdrlen + ipdatalen != recvlen) {
            fprintf(stderr,
                    "packet shorter (%u bytes) than hdr+data len (%u+%u)\n",
                    recvlen, iphdrlen, ipdatalen);
            continue;
        }

        igmp = (struct igmp *) (recv_buf + iphdrlen);
        igmpdatalen = ipdatalen - IGMP_MINLEN;
        if (igmpdatalen < 0) {
            fprintf(stderr,
                    "IP data field too short (%u bytes) for IGMP from %s\n",
                    ipdatalen, inet_fmt(ip->ip_src.s_addr, s1));
            continue;
        }

        switch (igmp->igmp_type) {

          case IGMP_MTRACE_QUERY:           /* For backward compatibility with 3.3 */
          case IGMP_MTRACE_REPLY:
            if (igmpdatalen < QLEN) continue;
            if ((igmpdatalen - QLEN)%RLEN) {
                printf("packet with incorrect datalen\n");
                continue;
            }

            len = (igmpdatalen - QLEN)/RLEN;

            break;

          default:
            continue;
        }

        base.qtime = ((tr.tv_sec + JAN_1970) << 16) +
                      (tr.tv_usec << 10) / 15625;
        base.rtime = ((tr.tv_sec + JAN_1970) << 16) +
                      (tr.tv_usec << 10) / 15625;
        base.len = len;
        bcopy((char *)igmp, (char *)&base.igmp, ipdatalen);
        /*
         * If the user specified which traces to monitor,
         * only accept traces that correspond to the
         * request
         */
        if ((qsrc != 0 && qsrc != base.qhdr.tr_src) ||
            (qdst != 0 && qdst != base.qhdr.tr_dst) ||
            (qgrp != 0 && qgrp != igmp->igmp_group.s_addr))
            continue;

        printf("Mtrace from %s to %s via group %s (mxhop=%d)\n",
                inet_fmt(base.qhdr.tr_dst, s1), inet_fmt(base.qhdr.tr_src, s2),
                inet_fmt(igmp->igmp_group.s_addr, s3), igmp->igmp_code);
        if (len == 0)
            continue;
        printf("  0  ");
        print_host(base.qhdr.tr_dst);
        printf("\n");
        print_trace(1, &base);
        r = base.resps + base.len - 1;
        VAL_TO_MASK(smask, r->tr_smask);
        if ((r->tr_inaddr & smask) == (base.qhdr.tr_src & smask)) {
            printf("%3d  ", -(base.len+1));
            print_host(base.qhdr.tr_src);
            printf("\n");
        } else if (r->tr_rmtaddr != 0) {
            printf("%3d  ", -(base.len+1));
            what_kind(&base, r->tr_rflags == TR_OLD_ROUTER ?
                                   "doesn't support mtrace"
                                 : "is the next hop");
        }
        printf("\n");
    }
}

char *
print_host(u_int32_t addr)
{
    return print_host2(addr, 0);
}

/*
 * On some routers, one interface has a name and the other doesn't.
 * We always print the address of the outgoing interface, but can
 * sometimes get the name from the incoming interface.  This might be
 * confusing but should be slightly more helpful than just a "?".
 */
char *
print_host2(u_int32_t addr1, u_int32_t addr2)
{
    char *name;

    if (numeric) {
        printf("%s", inet_fmt(addr1, s1));
        return ("");
    }
    name = inet_name(addr1);
    if (*name == '?' && *(name + 1) == '\0' && addr2 != 0)
        name = inet_name(addr2);
    printf("%s (%s)", name, inet_fmt(addr1, s1));
    return (name);
}

/*
 * Print responses as received (reverse path from dst to src)
 */
void
print_trace(int index, struct resp_buf *buf)
{
    struct tr_resp *r;
    char *name;
    int i;
    int hop;
    char *ms;

    i = abs(index);
    r = buf->resps + i - 1;

    for (; i <= buf->len; ++i, ++r) {
        if (index > 0) printf("%3d  ", -i);
        name = print_host2(r->tr_outaddr, r->tr_inaddr);
        printf("  %s  thresh^ %d", proto_type(r->tr_rproto), r->tr_fttl);
        if (verbose) {
            hop = t_diff(fixtime(ntohl(r->tr_qarr)), buf->qtime);
            ms = scale(&hop);
            printf("  %d%s", hop, ms);
        }
        printf("  %s\n", flag_type(r->tr_rflags));
        memcpy(names[i-1], name, sizeof(names[0]) - 1);
        names[i-1][sizeof(names[0])-1] = '\0';
    }
}

/*
 * See what kind of router is the next hop
 */
int
what_kind(struct resp_buf *buf, char *why)
{
    u_int32_t smask;
    int retval;
    int hops = buf->len;
    struct tr_resp *r = buf->resps + hops - 1;
    u_int32_t next = r->tr_rmtaddr;

    retval = send_recv(next, IGMP_DVMRP, DVMRP_ASK_NEIGHBORS2, 1, &incr[0]);
    print_host(next);
    if (retval) {
        u_int32_t version = ntohl(incr[0].igmp.igmp_group.s_addr);
        u_int32_t *p = (u_int32_t *)incr[0].ndata;
        u_int32_t *ep = p + (incr[0].len >> 2);
        char *type = "";
        retval = 0;
        switch (version & 0xFF) {
          case 1:
            type = "proteon/mrouted ";
            retval = 1;
            break;

          case 2:
          case 3:
            if (((version >> 8) & 0xFF) < 3) retval = 1;
                                /* Fall through */
          case 4:
            type = "mrouted ";
            break;

          case 10:
            type = "cisco ";
        }
        printf(" [%s%d.%d] %s\n",
               type, version & 0xFF, (version >> 8) & 0xFF,
               why);
        VAL_TO_MASK(smask, r->tr_smask);
        while (p < ep) {
            u_int32_t laddr = *p++;
            int flags = (ntohl(*p) & 0xFF00) >> 8;
            int n = ntohl(*p++) & 0xFF;
            if (!(flags & (DVMRP_NF_DOWN | DVMRP_NF_DISABLED)) &&
                 (laddr & smask) == (qsrc & smask)) {
                printf("%3d  ", -(hops+2));
                print_host(qsrc);
                printf("\n");
                return 1;
            }
            p += n;
        }
        return retval;
    }
    printf(" %s\n", why);
    return 0;
}


char *
scale(int *hop)
{
    if (*hop > -1000 && *hop < 10000) return (" ms");
    *hop /= 1000;
    if (*hop > -1000 && *hop < 10000) return (" s ");
    return ("s ");
}

/*
 * Calculate and print one line of packet loss and packet rate statistics.
 * Checks for count of all ones from mrouted 2.3 that doesn't have counters.
 */
#define NEITHER 0
#define INS     1
#define OUTS    2
#define BOTH    3
void
stat_line(struct tr_resp *r, struct tr_resp *s, int have_next, int *rst)
{
    int timediff = (fixtime(ntohl(s->tr_qarr)) -
                         fixtime(ntohl(r->tr_qarr))) >> 16;
    int v_lost, v_pct;
    int g_lost, g_pct;
    int v_out = ntohl(s->tr_vifout) - ntohl(r->tr_vifout);
    int g_out = ntohl(s->tr_pktcnt) - ntohl(r->tr_pktcnt);
    int v_pps, g_pps;
    char v_str[8], g_str[8];
    int have = NEITHER;
    int res = *rst;

    if (timediff == 0) timediff = 1;
    v_pps = v_out / timediff;
    g_pps = g_out / timediff;

    if ((v_out && (s->tr_vifout != 0xFFFFFFFF && s->tr_vifout != 0)) ||
                 (r->tr_vifout != 0xFFFFFFFF && r->tr_vifout != 0))
            have |= OUTS;

    if (have_next) {
        --r,  --s,  --rst;
        if ((s->tr_vifin != 0xFFFFFFFF && s->tr_vifin != 0) ||
            (r->tr_vifin != 0xFFFFFFFF && r->tr_vifin != 0))
          have |= INS;
        if (*rst)
          res = 1;
    }

    switch (have) {
      case BOTH:
        v_lost = v_out - (ntohl(s->tr_vifin) - ntohl(r->tr_vifin));
        if (v_out) v_pct = (v_lost * 100 + (v_out >> 1)) / v_out;
        else v_pct = 0;
        if (-100 < v_pct && v_pct < 101 && v_out > 10)
          snprintf(v_str, sizeof v_str, "%3d", v_pct);
        else memcpy(v_str, " --", 4);

        g_lost = g_out - (ntohl(s->tr_pktcnt) - ntohl(r->tr_pktcnt));
        if (g_out) g_pct = (g_lost * 100 + (g_out >> 1))/ g_out;
        else g_pct = 0;
        if (-100 < g_pct && g_pct < 101 && g_out > 10)
          snprintf(g_str, sizeof g_str, "%3d", g_pct);
        else memcpy(g_str, " --", 4);

        printf("%6d/%-5d=%s%%%4d pps",
               v_lost, v_out, v_str, v_pps);
        if (res)
            printf("\n");
        else
            printf("%6d/%-5d=%s%%%4d pps\n",
                   g_lost, g_out, g_str, g_pps);
        break;

      case INS:
        v_out = ntohl(s->tr_vifin) - ntohl(r->tr_vifin);
        v_pps = v_out / timediff;
        /* Fall through */

      case OUTS:
        printf("       %-5d     %4d pps",
               v_out, v_pps);
        if (res)
            printf("\n");
        else
            printf("       %-5d     %4d pps\n",
                   g_out, g_pps);
        break;

      case NEITHER:
        printf("\n");
        break;
    }

    if (debug > 2) {
        printf("\t\t\t\tv_in: %u ", ntohl(s->tr_vifin));
        printf("v_out: %u ", ntohl(s->tr_vifout));
        printf("pkts: %u\n", ntohl(s->tr_pktcnt));
        printf("\t\t\t\tv_in: %u ", ntohl(r->tr_vifin));
        printf("v_out: %u ", ntohl(r->tr_vifout));
        printf("pkts: %u\n", ntohl(r->tr_pktcnt));
        printf("\t\t\t\tv_in: %u ", ntohl(s->tr_vifin)-ntohl(r->tr_vifin));
        printf("v_out: %u ", ntohl(s->tr_vifout) - ntohl(r->tr_vifout));
        printf("pkts: %u ", ntohl(s->tr_pktcnt) - ntohl(r->tr_pktcnt));
        printf("time: %d\n", timediff);
        printf("\t\t\t\tres: %d\n", res);
    }
}

/*
 * A fixup to check if any pktcnt has been reset, and to fix the
 * byteorder bugs in mrouted 3.6 on little-endian machines.
 */
void
fixup_stats(struct resp_buf *base, struct resp_buf *prev, struct resp_buf *new)
{
    int rno = base->len;
    struct tr_resp *b = base->resps + rno;
    struct tr_resp *p = prev->resps + rno;
    struct tr_resp *n = new->resps + rno;
    int *r = reset + rno;
    int *s = swaps + rno;
    int res;

    /* Check for byte-swappers */
    while (--rno >= 0) {
        --n; --p; --b; --s;
        if (*s || ntohl(n->tr_vifout) - ntohl(p->tr_vifout) > 100000) {
            /* This host sends byteswapped reports; swap 'em */
            if (!*s) {
                *s = 1;
                b->tr_qarr = byteswap(b->tr_qarr);
                b->tr_vifin = byteswap(b->tr_vifin);
                b->tr_vifout = byteswap(b->tr_vifout);
                b->tr_pktcnt = byteswap(b->tr_pktcnt);
            }

            n->tr_qarr = byteswap(n->tr_qarr);
            n->tr_vifin = byteswap(n->tr_vifin);
            n->tr_vifout = byteswap(n->tr_vifout);
            n->tr_pktcnt = byteswap(n->tr_pktcnt);
        }
    }

    rno = base->len;
    b = base->resps + rno;
    p = prev->resps + rno;
    n = new->resps + rno;

    while (--rno >= 0) {
        --n; --p; --b; --r;
        res = ((ntohl(n->tr_pktcnt) < ntohl(b->tr_pktcnt)) ||
               (ntohl(n->tr_pktcnt) < ntohl(p->tr_pktcnt)));
        if (debug > 2)
            printf("\t\tr=%d, res=%d\n", *r, res);
        if (*r) {
            if (res || *r > 1) {
                /*
                 * This router appears to be a 3.4 with that nasty ol'
                 * neighbor version bug, which causes it to constantly
                 * reset.  Just nuke the statistics for this node, and
                 * don't even bother giving it the benefit of the
                 * doubt from now on.
                 */
                p->tr_pktcnt = b->tr_pktcnt = n->tr_pktcnt;
                r++;
            } else {
                /*
                 * This is simply the situation that the original
                 * fixup_stats was meant to deal with -- that a
                 * 3.3 or 3.4 router deleted a cache entry while
                 * traffic was still active.
                 */
                *r = 0;
                break;
            }
        } else
            *r = res;
    }

    if (rno < 0) return;

    rno = base->len;
    b = base->resps + rno;
    p = prev->resps + rno;

    while (--rno >= 0) (--b)->tr_pktcnt = (--p)->tr_pktcnt;
}

/*
 * Print responses with statistics for forward path (from src to dst)
 */
int
print_stats(struct resp_buf *base, struct resp_buf *prev, struct resp_buf *new)
{
    int rtt, hop;
    char *ms;
    u_int32_t smask;
    int rno = base->len - 1;
    struct tr_resp *b = base->resps + rno;
    struct tr_resp *p = prev->resps + rno;
    struct tr_resp *n = new->resps + rno;
    int *r = reset + rno;
    u_long resptime = new->rtime;
    u_long qarrtime = fixtime(ntohl(n->tr_qarr));
    u_int ttl = n->tr_fttl;
    int first = (base == prev);

    VAL_TO_MASK(smask, b->tr_smask);
    printf("  Source        Response Dest");
    printf("    Packet Statistics For     Only For Traffic\n");
    printf("%-15s %-15s  All Multicast Traffic     From %s\n",
           ((b->tr_inaddr & smask) == (qsrc & smask)) ? s1 : "   * * *       ",
           inet_fmt(base->qhdr.tr_raddr, s2), inet_fmt(qsrc, s1));
    rtt = t_diff(resptime, new->qtime);
    ms = scale(&rtt);
    printf("     %c       __/  rtt%5d%s    Lost/Sent = Pct  Rate       To %s\n",
           first ? 'v' : '|', rtt, ms, inet_fmt(qgrp, s2));
    if (!first) {
        hop = t_diff(resptime, qarrtime);
        ms = scale(&hop);
        printf("     v      /     hop%5d%s", hop, ms);
        printf("    ---------------------     --------------------\n");
    }
    if (debug > 2) {
        printf("\t\t\t\tv_in: %u ", ntohl(n->tr_vifin));
        printf("v_out: %u ", ntohl(n->tr_vifout));
        printf("pkts: %u\n", ntohl(n->tr_pktcnt));
        printf("\t\t\t\tv_in: %u ", ntohl(b->tr_vifin));
        printf("v_out: %u ", ntohl(b->tr_vifout));
        printf("pkts: %u\n", ntohl(b->tr_pktcnt));
        printf("\t\t\t\tv_in: %u ", ntohl(n->tr_vifin) - ntohl(b->tr_vifin));
        printf("v_out: %u ", ntohl(n->tr_vifout) - ntohl(b->tr_vifout));
        printf("pkts: %u\n", ntohl(n->tr_pktcnt) - ntohl(b->tr_pktcnt));
        printf("\t\t\t\treset: %d\n", *r);
    }

    while (TRUE) {
        if ((n->tr_inaddr != b->tr_inaddr) || (p->tr_inaddr != b->tr_inaddr))
          return 1;             /* Route changed */

        if ((n->tr_inaddr != n->tr_outaddr))
          printf("%-15s\n", inet_fmt(n->tr_inaddr, s1));
        printf("%-15s %-14s %s\n", inet_fmt(n->tr_outaddr, s1), names[rno],
                 flag_type(n->tr_rflags));

        if (rno-- < 1) break;

        printf("     %c     ^      ttl%5d   ", first ? 'v' : '|', ttl);
        stat_line(p, n, TRUE, r);
        if (!first) {
            resptime = qarrtime;
            qarrtime = fixtime(ntohl((n-1)->tr_qarr));
            hop = t_diff(resptime, qarrtime);
            ms = scale(&hop);
            printf("     v     |      hop%5d%s", hop, ms);
            stat_line(b, n, TRUE, r);
        }

        --b, --p, --n, --r;
        if (ttl < n->tr_fttl) ttl = n->tr_fttl;
        else ++ttl;
    }

    printf("     %c      \\__   ttl%5d   ", first ? 'v' : '|', ttl);
    stat_line(p, n, FALSE, r);
    if (!first) {
        hop = t_diff(qarrtime, new->qtime);
        ms = scale(&hop);
        printf("     v         \\  hop%5d%s", hop, ms);
        stat_line(b, n, FALSE, r);
    }
    printf("%-15s %s\n", inet_fmt(qdst, s1), inet_fmt(lcl_addr, s2));
    printf("  Receiver      Query Source\n\n");
    return 0;
}


/***************************************************************************
 *      main
 ***************************************************************************/

int
main(int argc, char *argv[])
{
    int udp;
    struct sockaddr_in addr;
    int addrlen = sizeof(addr);
    int recvlen;
    struct timeval tv;
    struct resp_buf *prev, *new;
    struct tr_resp *r;
    u_int32_t smask;
    int rno;
    int hops, nexthop, tries;
    u_int32_t lastout = 0;
    int numstats = 1;
    int waittime;
    uid_t uid;

    init_igmp();

    uid = getuid();
    if (setresuid(uid, uid, uid) == -1)
        err(1, "setresuid");

    argv++, argc--;
    if (argc == 0) goto usage;

    while (argc > 0 && *argv[0] == '-') {
        char *p = *argv++;  argc--;
        p++;
        do {
            char c = *p++;
            char *arg = NULL;
            if (isdigit((unsigned char)*p)) {
                arg = p;
                p = "";
            } else if (argc > 0) arg = argv[0];
            switch (c) {
              case 'd':                 /* Unlisted debug print option */
                if (arg && isdigit((unsigned char)*arg)) {
                    debug = atoi(arg);
                    if (debug < 0) debug = 0;
                    if (debug > 3) debug = 3;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'M':                 /* Use multicast for response */
                multicast = TRUE;
                break;
              case 'l':                 /* Loop updating stats indefinitely */
                numstats = 3153600;
                break;
              case 'n':                 /* Don't reverse map host addresses */
                numeric = TRUE;
                break;
              case 'p':                 /* Passive listen for traces */
                passive = TRUE;
                break;
              case 'v':                 /* Verbosity */
                verbose = TRUE;
                break;
              case 's':                 /* Short form, don't wait for stats */
                numstats = 0;
                break;
              case 'w':                 /* Time to wait for packet arrival */
                if (arg && isdigit((unsigned char)*arg)) {
                    timeout = atoi(arg);
                    if (timeout < 1) timeout = 1;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'm':                 /* Max number of hops to trace */
                if (arg && isdigit((unsigned char)*arg)) {
                    qno = atoi(arg);
                    if (qno > MAXHOPS) qno = MAXHOPS;
                    else if (qno < 1) qno = 0;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'q':                 /* Number of query retries */
                if (arg && isdigit((unsigned char)*arg)) {
                    nqueries = atoi(arg);
                    if (nqueries < 1) nqueries = 1;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'g':                 /* Last-hop gateway (dest of query) */
                if (arg && (gwy = host_addr(arg))) {
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 't':                 /* TTL for query packet */
                if (arg && isdigit((unsigned char)*arg)) {
                    qttl = atoi(arg);
                    if (qttl < 1) qttl = 1;
                    rttl = qttl;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'r':                 /* Dest for response packet */
                if (arg && (raddr = host_addr(arg))) {
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'i':                 /* Local interface address */
                if (arg && (lcl_addr = host_addr(arg))) {
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              case 'S':                 /* Stat accumulation interval */
                if (arg && isdigit((unsigned char)*arg)) {
                    statint = atoi(arg);
                    if (statint < 1) statint = 1;
                    if (arg == argv[0]) argv++, argc--;
                    break;
                } else
                    goto usage;
              default:
                goto usage;
            }
        } while (*p);
    }

    if (argc > 0 && (qsrc = host_addr(argv[0]))) {          /* Source of path */
        if (IN_MULTICAST(ntohl(qsrc))) goto usage;
        argv++, argc--;
        if (argc > 0 && (qdst = host_addr(argv[0]))) {      /* Dest of path */
            argv++, argc--;
            if (argc > 0 && (qgrp = host_addr(argv[0]))) {  /* Path via group */
                argv++, argc--;
            }
            if (IN_MULTICAST(ntohl(qdst))) {
                u_int32_t temp = qdst;
                qdst = qgrp;
                qgrp = temp;
                if (IN_MULTICAST(ntohl(qdst))) goto usage;
            } else if (qgrp && !IN_MULTICAST(ntohl(qgrp))) goto usage;
        }
    }

    if (passive) {
        passive_mode();
        return(0);
    }

    if (argc > 0 || qsrc == 0) {
usage:  printf("\
usage: mtrace [-lMnpsv] [-g gateway] [-i if_addr] [-m max_hops] [-q nqueries]\n\
              [-r host] [-S stat_int] [-t ttl] [-w waittime] source [receiver]\n\
              [group]\n");
        exit(1);
    }

    /*
     * Set useful defaults for as many parameters as possible.
     */

    defgrp = htonl(0xE0020001);         /* MBone Audio (224.2.0.1) */
    query_cast = htonl(0xE0000002);     /* All routers multicast addr */
    resp_cast = htonl(0xE0000120);      /* Mtrace response multicast addr */
    if (qgrp == 0) qgrp = defgrp;

    /*
     * Get default local address for multicasts to use in setting defaults.
     */
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_len = sizeof(addr);
    addr.sin_addr.s_addr = qgrp;
    addr.sin_port = htons(2000);        /* Any port above 1024 will do */

    if (((udp = socket(AF_INET, SOCK_DGRAM, 0)) == -1) ||
        (connect(udp, (struct sockaddr *) &addr, sizeof(addr)) == -1) ||
        getsockname(udp, (struct sockaddr *) &addr, &addrlen) == -1) {
        perror("Determining local address");
        exit(1);
    }

#ifdef SUNOS5
   /*
     * SunOS 5.X prior to SunOS 2.6, getsockname returns 0 for udp socket.
     * This call to sysinfo will return the hostname.
     * If the default multicast interface (set with the route
     * for 224.0.0.0) is not the same as the hostname,
     * mtrace -i [if_addr] will have to be used.
     */
    if (addr.sin_addr.s_addr == 0) {
        char myhostname[HOST_NAME_MAX+1];
        struct hostent *hp;
        int error;

        error = sysinfo(SI_HOSTNAME, myhostname, sizeof(myhostname));
        if (error == -1) {
            perror("Getting my hostname");
            exit(1);
        }

        hp = gethostbyname(myhostname);
        if (hp == NULL || hp->h_addrtype != AF_INET ||
            hp->h_length != sizeof(addr.sin_addr)) {
            perror("Finding IP address for my hostname");
            exit(1);
        }

        memcpy((char *)&addr.sin_addr.s_addr, hp->h_addr, hp->h_length);
    }
#endif

    /*
     * Default destination for path to be queried is the local host.
     */
    if (qdst == 0) qdst = lcl_addr ? lcl_addr : addr.sin_addr.s_addr;
    dst_netmask = get_netmask(udp, qdst);
    close(udp);
    if (lcl_addr == 0) lcl_addr = addr.sin_addr.s_addr;

    /*
     * Protect against unicast queries to mrouted versions that might crash.
     */
    if (gwy && !IN_MULTICAST(ntohl(gwy)))
      if (send_recv(gwy, IGMP_DVMRP, DVMRP_ASK_NEIGHBORS2, 1, &incr[0])) {
          int version = ntohl(incr[0].igmp.igmp_group.s_addr) & 0xFFFF;
          if (version == 0x0303 || version == 0x0503) {
            printf("Don't use -g to address an mrouted 3.%d, it might crash\n",
                   (version >> 8) & 0xFF);
            exit(0);
        }
      }

    printf("Mtrace from %s to %s via group %s\n",
           inet_fmt(qsrc, s1), inet_fmt(qdst, s2), inet_fmt(qgrp, s3));

    if ((qdst & dst_netmask) == (qsrc & dst_netmask)) {
        printf("Source & receiver are directly connected, no path to trace\n");
        exit(0);
    }

    /*
     * If the response is to be a multicast address, make sure we
     * are listening on that multicast address.
     */
    if (raddr) {
        if (IN_MULTICAST(ntohl(raddr))) k_join(raddr, lcl_addr);
    } else k_join(resp_cast, lcl_addr);

    /*
     * If the destination is on the local net, the last-hop router can
     * be found by multicast to the all-routers multicast group.
     * Otherwise, use the group address that is the subject of the
     * query since by definition the last-hop router will be a member.
     * Set default TTLs for local remote multicasts.
     */
    restart:

    if (gwy == 0)
      if ((qdst & dst_netmask) == (lcl_addr & dst_netmask)) tdst = query_cast;
      else tdst = qgrp;
    else tdst = gwy;

    if (IN_MULTICAST(ntohl(tdst))) {
      k_set_loop(1);    /* If I am running on a router, I need to hear this */
      if (tdst == query_cast) k_set_ttl(qttl ? qttl : 1);
      else k_set_ttl(qttl ? qttl : MULTICAST_TTL1);
    }

    /*
     * Try a query at the requested number of hops or MAXHOPS if unspecified.
     */
    if (qno == 0) {
        hops = MAXHOPS;
        tries = 1;
        printf("Querying full reverse path... ");
        fflush(stdout);
    } else {
        hops = qno;
        tries = nqueries;
        printf("Querying reverse path, maximum %d hops... ", qno);
        fflush(stdout);
    }
    base.rtime = 0;
    base.len = 0;

    recvlen = send_recv(tdst, IGMP_MTRACE_QUERY, hops, tries, &base);

    /*
     * If the initial query was successful, print it.  Otherwise, if
     * the query max hop count is the default of zero, loop starting
     * from one until there is no response for four hops.  The extra
     * hops allow getting past an mtrace-capable mrouter that can't
     * send multicast packets because all phyints are disabled.
     */
    if (recvlen) {
        printf("\n  0  ");
        print_host(qdst);
        printf("\n");
        print_trace(1, &base);
        r = base.resps + base.len - 1;
        if (r->tr_rflags == TR_OLD_ROUTER || r->tr_rflags == TR_NO_SPACE ||
                qno != 0) {
            printf("%3d  ", -(base.len+1));
            what_kind(&base, r->tr_rflags == TR_OLD_ROUTER ?
                                   "doesn't support mtrace"
                                 : "is the next hop");
        } else {
            VAL_TO_MASK(smask, r->tr_smask);
            if ((r->tr_inaddr & smask) == (qsrc & smask)) {
                printf("%3d  ", -(base.len+1));
                print_host(qsrc);
                printf("\n");
            }
        }
    } else if (qno == 0) {
        printf("switching to hop-by-hop:\n  0  ");
        print_host(qdst);
        printf("\n");

        for (hops = 1, nexthop = 1; hops <= MAXHOPS; ++hops) {
            printf("%3d  ", -hops);
            fflush(stdout);

            /*
             * After a successful first hop, try switching to the unicast
             * address of the last-hop router instead of multicasting the
             * trace query.  This should be safe for mrouted versions 3.3
             * and 3.5 because there is a long route timeout with metric
             * infinity before a route disappears.  Switching to unicast
             * reduces the amount of multicast traffic and avoids a bug
             * with duplicate suppression in mrouted 3.5.
             */
            if (hops == 2 && gwy == 0 &&
                (recvlen = send_recv(lastout, IGMP_MTRACE_QUERY, hops, 1, &base)))
              tdst = lastout;
            else recvlen = send_recv(tdst, IGMP_MTRACE_QUERY, hops, nqueries, &base);

            if (recvlen == 0) {
                if (hops == 1) break;
                if (hops == nexthop) {
                    if (what_kind(&base, "didn't respond")) {
                        /* the ask_neighbors determined that the
                         * not-responding router is the first-hop. */
                        break;
                    }
                } else if (hops < nexthop + 3) {
                    printf("\n");
                } else {
                    printf("...giving up\n");
                    break;
                }
                continue;
            }
            r = base.resps + base.len - 1;
            if (base.len == hops &&
                (hops == 1 || (base.resps+nexthop-2)->tr_outaddr == lastout)) {
                if (hops == nexthop) {
                    print_trace(-hops, &base);
                } else {
                    printf("\nResuming...\n");
                    print_trace(nexthop, &base);
                }
            } else {
                if (base.len < hops) {
                    /*
                     * A shorter trace than requested means a fatal error
                     * occurred along the path, or that the route changed
                     * to a shorter one.
                     *
                     * If the trace is longer than the last one we received,
                     * then we are resuming from a skipped router (but there
                     * is still probably a problem).
                     *
                     * If the trace is shorter than the last one we
                     * received, then the route must have changed (and
                     * there is still probably a problem).
                     */
                    if (nexthop <= base.len) {
                        printf("\nResuming...\n");
                        print_trace(nexthop, &base);
                    } else if (nexthop > base.len + 1) {
                        hops = base.len;
                        printf("\nRoute must have changed...\n");
                        print_trace(1, &base);
                    }
                } else {
                    /*
                     * The last hop address is not the same as it was;
                     * the route probably changed underneath us.
                     */
                    hops = base.len;
                    printf("\nRoute must have changed...\n");
                    print_trace(1, &base);
                }
            }
            lastout = r->tr_outaddr;

            if (base.len < hops ||
                r->tr_rmtaddr == 0 ||
                (r->tr_rflags & 0x80)) {
                VAL_TO_MASK(smask, r->tr_smask);
                if (r->tr_rmtaddr) {
                    if (hops != nexthop) {
                        printf("\n%3d  ", -(base.len+1));
                    }
                    what_kind(&base, r->tr_rflags == TR_OLD_ROUTER ?
                                "doesn't support mtrace" :
                                "would be the next hop");
                    /* XXX could do segmented trace if TR_NO_SPACE */
                } else if (r->tr_rflags == TR_NO_ERR &&
                           (r->tr_inaddr & smask) == (qsrc & smask)) {
                    printf("%3d  ", -(hops + 1));
                    print_host(qsrc);
                    printf("\n");
                }
                break;
            }

            nexthop = hops + 1;
        }
    }

    if (base.rtime == 0) {
        printf("Timed out receiving responses\n");
        if (IN_MULTICAST(ntohl(tdst))) {
          if (tdst == query_cast)
            printf("Perhaps no local router has a route for source %s\n",
                   inet_fmt(qsrc, s1));
          else
            printf("Perhaps receiver %s is not a member of group %s,\n\
or no router local to it has a route for source %s,\n\
or multicast at ttl %d doesn't reach its last-hop router for that source\n",
                   inet_fmt(qdst, s2), inet_fmt(qgrp, s3), inet_fmt(qsrc, s1),
                   qttl ? qttl : MULTICAST_TTL1);
        }
        exit(1);
    }

    printf("Round trip time %d ms\n\n", t_diff(base.rtime, base.qtime));

    /*
     * Use the saved response which was the longest one received,
     * and make additional probes after delay to measure loss.
     */
    raddr = base.qhdr.tr_raddr;
    rttl = base.qhdr.tr_rttl;
    gettimeofday(&tv, 0);
    waittime = statint - (((tv.tv_sec + JAN_1970) & 0xFFFF) - (base.qtime >> 16));
    prev = &base;
    new = &incr[numstats&1];

    while (numstats--) {
        if (waittime < 1)
                printf("\n");
        else {
                printf("Waiting to accumulate statistics... ");
                fflush(stdout);
                sleep((unsigned int)waittime);
        }
        rno = base.len;
        recvlen = send_recv(tdst, IGMP_MTRACE_QUERY, rno, nqueries, new);

        if (recvlen == 0) {
            printf("Timed out.\n");
            exit(1);
        }

        if (rno != new->len) {
            printf("Trace length doesn't match:\n");
            /*
             * XXX Should this trace result be printed, or is that
             * too verbose?  Perhaps it should just say restarting.
             * But if the path is changing quickly, this may be the
             * only snapshot of the current path.  But, if the path
             * is changing that quickly, does the current path really
             * matter?
             */
            print_trace(1, new);
            printf("Restarting.\n\n");
            numstats++;
            goto restart;
        }

        printf("Results after %d seconds:\n\n",
               (int)((new->qtime - base.qtime) >> 16));
        fixup_stats(&base, prev, new);
        if (print_stats(&base, prev, new)) {
            printf("Route changed:\n");
            print_trace(1, new);
            printf("Restarting.\n\n");
            goto restart;
        }
        prev = new;
        new = &incr[numstats&1];
        waittime = statint;
    }

    /*
     * If the response was multicast back, leave the group
     */
    if (raddr) {
        if (IN_MULTICAST(ntohl(raddr))) k_leave(raddr, lcl_addr);
    } else k_leave(resp_cast, lcl_addr);

    return (0);
}

void
check_vif_state(void)
{
    logit(LOG_WARNING, errno, "sendto");
}

/*
 * Log errors and other messages to stderr, according to the severity
 * of the message and the current debug level.  For errors of severity
 * LOG_ERR or worse, terminate the program.
 */
void
logit(int severity, int syserr, char *format, ...)
{
    va_list ap;

    switch (debug) {
        case 0: if (severity > LOG_WARNING) return;
        case 1: if (severity > LOG_NOTICE) return;
        case 2: if (severity > LOG_INFO  ) return;
        default:
            if (severity == LOG_WARNING)
                fprintf(stderr, "warning - ");
            va_start(ap, format);
            vfprintf(stderr, format, ap);
            va_end(ap);
            if (syserr == 0)
                fprintf(stderr, "\n");
            else if(syserr < sys_nerr)
                fprintf(stderr, ": %s\n", sys_errlist[syserr]);
            else
                fprintf(stderr, ": errno %d\n", syserr);
    }
    if (severity <= LOG_ERR) exit(1);
}

/* dummies */
void accept_probe(u_int32_t src, u_int32_t dst, char *p, int datalen,
    u_int32_t level)
{
}

void accept_group_report(u_int32_t src, u_int32_t dst, u_int32_t group,
    int r_type)
{
}

void accept_neighbor_request2(u_int32_t src, u_int32_t dst)
{
}

void accept_report(u_int32_t src, u_int32_t dst, char *p, int datalen,
    u_int32_t level)
{
}

void accept_neighbor_request(u_int32_t src, u_int32_t dst)
{
}

void accept_prune(u_int32_t src, u_int32_t dst, char *p, int datalen)
{
}

void accept_graft(u_int32_t src, u_int32_t dst, char *p, int datalen)
{
}

void accept_g_ack(u_int32_t src, u_int32_t dst, char *p, int datalen)
{
}

void add_table_entry(u_int32_t origin, u_int32_t mcastgrp)
{
}

void accept_leave_message(u_int32_t src, u_int32_t dst, u_int32_t group)
{
}

void accept_mtrace(u_int32_t src, u_int32_t dst, u_int32_t group, char *data,
    u_int no, int datalen)
{
}

void accept_membership_query(u_int32_t src, u_int32_t dst, u_int32_t group,
    int tmo)
{
}

void accept_neighbors(u_int32_t src, u_int32_t dst, u_char *p, int datalen,
    u_int32_t level)
{
}

void accept_neighbors2(u_int32_t src, u_int32_t dst, u_char *p, int datalen,
    u_int32_t level)
{
}

void accept_info_request(u_int32_t src, u_int32_t dst, u_char *p, int datalen)
{
}

void accept_info_reply(u_int32_t src, u_int32_t dst, u_char *p, int datalen)
{
}