/*
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that 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.
 *
 * @(#) Copyright (c) 1983, 1993 The Regents of the University of California.  All rights reserved.
 * @(#)rwhod.c  8.1 (Berkeley) 6/6/93
 * $FreeBSD: src/usr.sbin/rwhod/rwhod.c,v 1.13.2.2 2000/12/23 15:28:12 iedowse Exp $
 */

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <sys/ioctl.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <protocols/rwhod.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <netdb.h>
#include <paths.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <timeconv.h>
#include <unistd.h>
#include <utmpx.h>
#include <pwd.h>
#include <grp.h>

/*
 * This version of Berkeley's rwhod has been modified to use IP multicast
 * datagrams, under control of a new command-line option:
 *
 *      rwhod -m        causes rwhod to use IP multicast (instead of
 *                      broadcast or unicast) on all interfaces that have
 *                      the IFF_MULTICAST flag set in their "ifnet" structs
 *                      (excluding the loopback interface).  The multicast
 *                      reports are sent with a time-to-live of 1, to prevent
 *                      forwarding beyond the directly-connected subnet(s).
 *
 *      rwhod -m <ttl>  causes rwhod to send IP multicast datagrams with a
 *                      time-to-live of <ttl>, via a SINGLE interface rather
 *                      than all interfaces.  <ttl> must be between 0 and
 *                      MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
 *                      is different than "-m", in that "-m 1" specifies
 *                      transmission on one interface only.
 *
 * When "-m" is used without a <ttl> argument, the program accepts multicast
 * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
 * is given, it accepts multicast reports from only one interface, the one
 * on which reports are sent (which may be controlled via the host's routing
 * table).  Regardless of the "-m" option, the program accepts broadcast or
 * unicast reports from all interfaces.  Thus, this program will hear the
 * reports of old, non-multicasting rwhods, but, if multicasting is used,
 * those old rwhods won't hear the reports generated by this program.
 *
 *                  -- Steve Deering, Stanford University, February 1989
 */

#define UNPRIV_USER             "daemon"
#define UNPRIV_GROUP            "daemon"

#define WITH_ERRNO              1       /* Write to syslog with errno (%m) */
#define WITHOUT_ERRNO           0       /* Write to syslog without errno */

#define NO_MULTICAST            0         /* multicast modes */
#define PER_INTERFACE_MULTICAST 1
#define SCOPED_MULTICAST        2

#define MAX_MULTICAST_SCOPE     32        /* "site-wide", by convention */

#define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
                                          /* (belongs in protocols/rwhod.h) */

static int                      insecure_mode;
static int                      quiet_mode;
static int                      iff_flag = IFF_POINTOPOINT;
static int                      multicast_mode  = NO_MULTICAST;
static int                      multicast_scope;
static struct sockaddr_in       multicast_addr;

static char     myname[MAXHOSTNAMELEN];

/*
 * We communicate with each neighbor in a list constructed at the time we're
 * started up.  Neighbors are currently directly connected via a hardware
 * interface.
 */
struct  neighbor {
        struct  neighbor *n_next;
        char    *n_name;                /* interface name */
        struct  sockaddr *n_addr;               /* who to send to */
        int     n_addrlen;              /* size of address */
        int     n_flags;                /* should forward?, interface flags */
};

static struct   neighbor *neighbors;
static struct   whod mywd;
static struct   servent *sp;
static int      s;
static volatile sig_atomic_t    onsighup;

#define WHDRSIZE        (sizeof(mywd) - sizeof(mywd.wd_we))

static void      run_as(uid_t *, gid_t *);
static int       configure(int);
static void      getboottime(void);
static void      send_host_information(void);
static void      hup(int);
static void      quit(const char *, int) __dead2;
static void      rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
static int       verify(char *, int);
static void      handleread(int);
static void      usage(void) __dead2;
static void      timeadd(struct timeval *, time_t, struct timeval *);

#ifdef DEBUG
static char     *interval(int, const char *);
static ssize_t  Sendto(int, const void *, size_t, int,
                     const struct sockaddr *, int);
#else
#define Sendto sendto
#endif

int
main(int argc, char *argv[])
{
        struct pollfd pfd[1];
        char *ep, *cp;
        int on = 1;
        int send_time = 180;    /* Default time, 180 seconds (3 minutes) */
        struct sockaddr_in m_sin;
        uid_t unpriv_uid;
        gid_t unpriv_gid;
        long tmp;
        time_t delta = 0;
        struct timeval next = { .tv_sec = 0 }, now;

        if (getuid())
                errx(1, "not super user");

        run_as(&unpriv_uid, &unpriv_gid);

        argv++; argc--;
        while (argc > 0 && *argv[0] == '-') {
                if (strcmp(*argv, "-m") == 0) {
                        if (argc > 1 && *(argv + 1)[0] != '-') {
                                /* Argument has been given */
                                argv++, argc--;
                                multicast_mode = SCOPED_MULTICAST;
                                tmp = strtol(*argv, &ep, 10);
                                if (*ep != '\0' || tmp < INT_MIN || tmp > INT_MAX)
                                        errx(1, "invalid ttl: %s", *argv);
                                multicast_scope = (int)tmp;
                                if (multicast_scope > MAX_MULTICAST_SCOPE)
                                        errx(1, "ttl must not exceed %u",
                                        MAX_MULTICAST_SCOPE);
                        }
                        else multicast_mode = PER_INTERFACE_MULTICAST;
                } else if (strcmp(*argv, "-g") == 0) {
                        if (argc > 1 && *(argv + 1)[0] != '-') {
                                argv++, argc--;
                                send_time = (int)strtol(*argv, &ep, 10);
                                if (send_time <= 0)
                                        errx(1, "time must be greater than 0");

                                if (ep[0] != '\0') {
                                        if (ep[1] != '\0')
                                                errx(1, "invalid argument: %s", *argv);
                                        if (*ep == 'M' || *ep == 'm') {
                                                /* Time in minutes. */
                                                send_time *= 60;
                                        } else
                                                errx(1, "invalid argument: %s", *argv);
                                }

                                if (send_time > 180)
                                        errx(1, "cannot be greater than 180 seconds (3 minutes)");
                        } else
                                errx(1, "missing argument");
                } else if (strcmp(*argv, "-i") == 0)
                        insecure_mode = 1;
                else if (strcmp(*argv, "-l") == 0)
                        quiet_mode = 1;
                else if (strcmp(*argv, "-p") == 0)
                        iff_flag = 0;
                else
                        usage();
                argv++, argc--;
        }
        if (argc > 0)
                usage();
#ifndef DEBUG
        struct pidfh *pfh = NULL;
        pfh = pidfile_open(NULL, 600, NULL);
        daemon(1, 0);
        pidfile_write(pfh);
#endif
        signal(SIGHUP, hup);
        openlog("rwhod", LOG_PID, LOG_DAEMON);
        sp = getservbyname("who", "udp");
        if (sp == NULL)
                quit("udp/who: unknown service", WITHOUT_ERRNO);

        if (chdir(_PATH_RWHODIR) < 0)
                quit(_PATH_RWHODIR, WITH_ERRNO);

        /*
         * Establish host name as returned by system.
         */
        if (gethostname(myname, sizeof(myname)) < 0)
                quit("gethostname", WITH_ERRNO);

        if ((cp = strchr(myname, '.')) != NULL)
                *cp = '\0';
        strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
        getboottime();
        if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
                quit("socket", WITH_ERRNO);

        if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0)
                quit("setsockopt SO_BROADCAST", WITH_ERRNO);

        memset(&m_sin, 0, sizeof(m_sin));
        m_sin.sin_len = sizeof(m_sin);
        m_sin.sin_family = AF_INET;
        m_sin.sin_port = sp->s_port;
        if (bind(s, (struct sockaddr *)&m_sin, sizeof(m_sin)) < 0)
                quit("bind", WITH_ERRNO);

        setgid(unpriv_gid);
        setgroups(1, &unpriv_gid);      /* XXX BOGUS groups[0] = egid */
        setuid(unpriv_uid);
        if (!configure(s))
                exit(1);

        if (!quiet_mode) {
                send_host_information();
                delta = send_time;
                gettimeofday(&now, NULL);
                timeadd(&now, delta, &next);
        }

        pfd[0].fd = s;
        pfd[0].events = POLLIN;
 
        for (;;) {
                int n;

                n = poll(pfd, 1, 1000);

                if (onsighup) {
                        onsighup = 0;
                        getboottime();
                }

                if (n == 1)
                        handleread(s);
                if (!quiet_mode) {
                        gettimeofday(&now, NULL);
                        if (now.tv_sec > next.tv_sec) {
                                send_host_information();
                                timeadd(&now, delta, &next);
                        }
                }
        }
}

static void
timeadd(struct timeval *now, time_t delta, struct timeval *next)
{
        (next)->tv_sec = (now)->tv_sec + delta;
}

static void
handleread(int sock)
{
        struct sockaddr_in from;
        struct stat st;
        char path[64];
        struct whod wd;
        int cc, whod; 
        socklen_t len = sizeof(from);

        cc = recvfrom(sock, (char *)&wd, sizeof(struct whod), 0,
                (struct sockaddr *)&from, &len);
        if (cc == 0)
                return;

        if (cc < 0 && errno != EINTR) {
                syslog(LOG_WARNING, "recv: %m");
                return;
        }
        
        if (from.sin_port != sp->s_port && !insecure_mode) {
                syslog(LOG_WARNING, "%d: bad source port from %s",
                    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
                return;
        }
        if (cc < (int)WHDRSIZE) {
                syslog(LOG_WARNING, "short packet from %s",
                    inet_ntoa(from.sin_addr));
                return;
        }
        if (wd.wd_vers != WHODVERSION)
                return;
        if (wd.wd_type != WHODTYPE_STATUS)
                return;
        if (!verify(wd.wd_hostname, sizeof wd.wd_hostname)) {
                syslog(LOG_WARNING, "malformed host name from %s",
                    inet_ntoa(from.sin_addr));
                return;
        }
        snprintf(path, sizeof path, "whod.%s", wd.wd_hostname);
        /*
         * Rather than truncating and growing the file each time,
         * use ftruncate if size is less than previous size.
         */
        whod = open(path, O_WRONLY | O_CREAT, 0644);
        if (whod < 0) {
                syslog(LOG_WARNING, "%s: %m", path);
                return;
        }
#if _BYTE_ORDER != _BIG_ENDIAN
        {
                int i, n = (cc - WHDRSIZE)/sizeof(struct whoent);
                struct whoent *we;

                /* undo header byte swapping before writing to file */
                wd.wd_sendtime = ntohl(wd.wd_sendtime);
                for (i = 0; i < 3; i++)
                        wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
                wd.wd_boottime = ntohl(wd.wd_boottime);
                we = wd.wd_we;
                for (i = 0; i < n; i++) {
                        we->we_idle = ntohl(we->we_idle);
                        we->we_utmp.out_time =
                            ntohl(we->we_utmp.out_time);
                        we++;
                }
        }
#endif
        wd.wd_recvtime = time(NULL);
        write(whod, (char *)&wd, cc);
        if (fstat(whod, &st) < 0 || st.st_size > cc)
                ftruncate(whod, cc);
        close(whod);
}

static void
usage(void)
{
        fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
        exit(1);
}

static void
hup(int signo __unused)
{
        onsighup = 1;
}

static void
run_as(uid_t *uid, gid_t *gid)
{
        struct passwd *pw;
        struct group *gr;

        pw = getpwnam(UNPRIV_USER);
        if (!pw)
                quit("getpwnam(daemon)", WITH_ERRNO);

        *uid = pw->pw_uid;

        gr = getgrnam(UNPRIV_GROUP);
        if (!gr)
                quit("getgrnam(daemon)", WITH_ERRNO);

        *gid = gr->gr_gid;
}

/*
 * Check out host name for unprintables
 * and other funnies before allowing a file
 * to be created.  Sorry, but blanks aren't allowed.
 */
static int
verify(char *name, int maxlen)
{
        int size = 0;

        while (*name && size < maxlen - 1) {
                if (!isascii(*name) || !(isalnum(*name) || ispunct(*name)))
                        return (0);
                name++, size++;
        }
        *name = '\0';
        return (size > 0);
}

static void
send_host_information(void)
{
        struct neighbor *np;
        struct whoent *we = mywd.wd_we, *wend;
        struct stat stb;
        struct utmpx *ut;
        static int alarmcount = 0;
        double avenrun[3];
        time_t now;
        int i, cc;

        now = time(NULL);
        if (alarmcount % 10 == 0)
                getboottime();
        alarmcount++;
        wend = &mywd.wd_we[1024 / sizeof(struct whoent)];
        setutxent();
        while ((ut = getutxent()) != NULL && we < wend) {
                if (ut->ut_type != USER_PROCESS)
                        continue;
                strncpy(we->we_utmp.out_line, ut->ut_line,
                   sizeof(we->we_utmp.out_line));
                strncpy(we->we_utmp.out_name, ut->ut_user,
                   sizeof(we->we_utmp.out_name));
                we->we_utmp.out_time =
                    htonl(_time_to_time32(ut->ut_tv.tv_sec));
                we++;
        }
        endutxent();

        if (chdir(_PATH_DEV)) {
                syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
                exit(1);
        }

        wend = we;
        for (we = mywd.wd_we; we < wend; we++) {
                if (stat(we->we_utmp.out_line, &stb) >= 0)
                        we->we_idle = htonl(now - stb.st_atime);
        }
        getloadavg(avenrun, NELEM(avenrun));
        for (i = 0; i < 3; i++)
                mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
        cc = (char *)wend - (char *)&mywd;
        mywd.wd_sendtime = htonl(time(0));
        mywd.wd_vers = WHODVERSION;
        mywd.wd_type = WHODTYPE_STATUS;
        if (multicast_mode == SCOPED_MULTICAST) {
                Sendto(s, (char *)&mywd, cc, 0,
                                (struct sockaddr *)&multicast_addr,
                                sizeof(multicast_addr));
        }
        else for (np = neighbors; np != NULL; np = np->n_next) {
                if (multicast_mode == PER_INTERFACE_MULTICAST &&
                    np->n_flags & IFF_MULTICAST) {
                        /*
                         * Select the outgoing interface for the multicast.
                         */
                        if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
                            &(((struct sockaddr_in *)np->n_addr)->sin_addr),
                            sizeof(struct in_addr)) < 0) {
                                quit("setsockopt IP_MULTICAST_IF", WITH_ERRNO);
                        }
                        Sendto(s, (char *)&mywd, cc, 0,
                                (struct sockaddr *)&multicast_addr,
                                sizeof(multicast_addr));
                } else Sendto(s, (char *)&mywd, cc, 0,
                                np->n_addr, np->n_addrlen);
        }
        if (chdir(_PATH_RWHODIR)) {
                syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
                exit(1);
        }
}

static void
getboottime(void)
{
        struct timespec uts;

        clock_gettime(CLOCK_UPTIME, &uts);
        mywd.wd_boottime = htonl(time(NULL) - uts.tv_sec);
}

/*
 * If wrterrno == WITH_ERRNO, we will print
 * errno. If not, we leave errno out.
 */
static void
quit(const char *msg, int wrterrno)
{
        if (wrterrno)
                syslog(LOG_ERR, "%s: %m", msg);
        else
                syslog(LOG_ERR, "%s", msg);
        exit(1);
}

static void
rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
{
        struct sockaddr *sa;
        int i;

        memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
        for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
                if ((rtinfo->rti_addrs & (1 << i)) == 0)
                        continue;
                rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
                RT_ADVANCE(cp, sa);
        }
}

/*
 * Figure out device configuration and select
 * networks which deserve status information.
 */
static int
configure(int c_sock)
{
        struct neighbor *np;
        struct if_msghdr *ifm;
        struct ifa_msghdr *ifam;
        struct sockaddr_dl *sdl;
        size_t needed;
        int mib[6], flags = 0, len;
        char *buf, *lim, *next;
        struct rt_addrinfo info;

        if (multicast_mode != NO_MULTICAST) {
                multicast_addr.sin_len = sizeof(multicast_addr);
                multicast_addr.sin_family = AF_INET;
                multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
                multicast_addr.sin_port = sp->s_port;
        }

        if (multicast_mode == SCOPED_MULTICAST) {
                struct ip_mreq mreq;
                unsigned char ttl;

                mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
                mreq.imr_interface.s_addr = htonl(INADDR_ANY);
                if (setsockopt(c_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                                        &mreq, sizeof(mreq)) < 0) {
                        syslog(LOG_ERR,
                                "setsockopt IP_ADD_MEMBERSHIP: %m");
                        return(0);
                }
                ttl = multicast_scope;
                if (setsockopt(c_sock, IPPROTO_IP, IP_MULTICAST_TTL,
                                        &ttl, sizeof(ttl)) < 0) {
                        syslog(LOG_ERR,
                                "setsockopt IP_MULTICAST_TTL: %m");
                        return(0);
                }
                return(1);
        }

        mib[0] = CTL_NET;
        mib[1] = PF_ROUTE;
        mib[2] = 0;
        mib[3] = AF_INET;
        mib[4] = NET_RT_IFLIST;
        mib[5] = 0;
        if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
                quit("route-sysctl-estimate", WITH_ERRNO);
        if ((buf = malloc(needed)) == NULL)
                quit("malloc", WITH_ERRNO);
        if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
                quit("actual retrieval of interface table", WITH_ERRNO);
        lim = buf + needed;

        sdl = NULL;             /* XXX just to keep gcc -Wall happy */
        for (next = buf; next < lim; next += ifm->ifm_msglen) {
                ifm = (struct if_msghdr *)next;
                if (ifm->ifm_type == RTM_IFINFO) {
                        sdl = (struct sockaddr_dl *)(ifm + 1);
                        flags = ifm->ifm_flags;
                        continue;
                }
                if ((flags & IFF_UP) == 0 ||
                    (flags & (((multicast_mode == PER_INTERFACE_MULTICAST) ?
                                IFF_MULTICAST : 0) |
                                IFF_BROADCAST|iff_flag)) == 0)
                        continue;
                if (ifm->ifm_type != RTM_NEWADDR)
                        quit("out of sync parsing NET_RT_IFLIST", WITHOUT_ERRNO);
                ifam = (struct ifa_msghdr *)ifm;
                info.rti_addrs = ifam->ifam_addrs;
                rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
                        &info);
                /* gag, wish we could get rid of Internet dependencies */
#define dstaddr info.rti_info[RTAX_BRD]
#define ifaddr info.rti_info[RTAX_IFA]
#define IPADDR_SA(x) ((struct sockaddr_in *)(x))->sin_addr.s_addr
#define PORT_SA(x) ((struct sockaddr_in *)(x))->sin_port
                if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
                        continue;
                PORT_SA(dstaddr) = sp->s_port;
                for (np = neighbors; np != NULL; np = np->n_next)
                        if (memcmp(sdl->sdl_data, np->n_name,
                                   sdl->sdl_nlen) == 0 &&
                            IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr))
                                break;
                if (np != NULL)
                        continue;
                len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
                np = (struct neighbor *)malloc(len);
                if (np == NULL)
                        quit("malloc of neighbor structure", WITH_ERRNO);
                memset(np, 0, len);
                np->n_flags = flags;
                np->n_addr = (struct sockaddr *)(np + 1);
                np->n_addrlen = dstaddr->sa_len;
                np->n_name = np->n_addrlen + (char *)np->n_addr;
                memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
                memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
                if (multicast_mode == PER_INTERFACE_MULTICAST &&
                    (flags & IFF_MULTICAST) &&
                   !(flags & IFF_LOOPBACK)) {
                        struct ip_mreq mreq;

                        memcpy((char *)np->n_addr, (char *)ifaddr,
                                np->n_addrlen);
                        mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
                        mreq.imr_interface.s_addr =
                          ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
                        if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                                                &mreq, sizeof(mreq)) < 0) {
                                syslog(LOG_ERR,
                                    "setsockopt IP_ADD_MEMBERSHIP: %m");
#if 0
                                /* Fall back to broadcast on this if. */
                                np->n_flags &= ~IFF_MULTICAST;
#else
                                free((char *)np);
                                continue;
#endif
                        }
                }
                np->n_next = neighbors;
                neighbors = np;
        }
        free(buf);
        return (1);
}

#ifdef DEBUG
static ssize_t
Sendto(int s_debug, const void *buf, size_t cc, int flags,
       const struct sockaddr *to, int tolen)
{
        const struct whod *w = (const struct whod *)buf;
        const struct whoent *we;
        const struct sockaddr_in *sock_in = (const struct sockaddr_in *)to;
        ssize_t ret;
        int idle_time;

        ret = sendto(s_debug, buf, cc, flags, to, tolen);

        printf("sendto %s:%d\n", inet_ntoa(sock_in->sin_addr),
                                 ntohs(sock_in->sin_port));
        printf("hostname %s %s\n", w->wd_hostname,
           interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
        printf("load %4.2f, %4.2f, %4.2f\n",
            ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
            ntohl(w->wd_loadav[2]) / 100.0);
        cc -= WHDRSIZE;
        for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
                time_t t = ntohl(we->we_utmp.out_time);
                idle_time = we->we_idle;
                printf("%-8.8s %s:%s %.12s",
                        we->we_utmp.out_name,
                        w->wd_hostname, we->we_utmp.out_line,
                        ctime(&t)+4);
                idle_time = ntohl(we->we_idle) / 60;
                if (idle_time) {
                        if (idle_time >= 100*60)
                                idle_time = 100*60 - 1;
                        if (idle_time >= 60)
                                printf(" %2d", idle_time / 60);
                        else
                                printf("   ");
                        printf(":%02d", idle_time % 60);
                }
                printf("\n");
        }
        return(ret);
}

static char *
interval(int inter_time, const char *updown)
{
        static char resbuf[32];
        int days, hours, minutes;

        if (inter_time < 0 || inter_time > 3*30*24*60*60) {
                snprintf(resbuf, sizeof(resbuf), "   %s ??:??", updown);
                return (resbuf);
        }
        minutes = (inter_time + 59) / 60;               /* round to minutes */
        hours = minutes / 60; minutes %= 60;
        days = hours / 24; hours %= 24;
        if (days)
                snprintf(resbuf, sizeof(resbuf), "%s %2d+%02d:%02d",
                    updown, days, hours, minutes);
        else
                snprintf(resbuf, sizeof(resbuf), "%s    %2d:%02d",
                    updown, hours, minutes);
        return (resbuf);
}
#endif