/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 1993 The Regents of the University of California.
 * Copyright (c) 2013 Mariusz Zaborski <oshogbo@FreeBSD.org>
 * 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.
 */

#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/ioctl.h>
#include <sys/procdesc.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <sys/sysctl.h>
#include <sys/wait.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 <capsicum_helpers.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <netdb.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <timeconv.h>
#include <utmpx.h>
#include <unistd.h>

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

#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) */

int     insecure_mode;
int     quiet_mode;
int     iff_flag = IFF_POINTOPOINT;
int     multicast_mode = NO_MULTICAST;
int     multicast_scope;
struct  sockaddr_in multicast_addr =
        { sizeof(multicast_addr), AF_INET, 0, { 0 }, { 0 } };

/*
 * Sleep interval. Don't forget to change the down time check in ruptime
 * if this is changed.
 */
#define SL_INTERVAL (3 * 60)

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 */
};

struct  neighbor *neighbors;
struct  whod mywd;
struct  servent *sp;
int     s;
int     fdp;
pid_t   pid_child_receiver;

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

int     configure(int so);
void    getboottime(int signo __unused);
void    receiver_process(void);
void    rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo);
void    run_as(uid_t *uid, gid_t *gid);
void    quit(const char *msg);
void    sender_process(void);
int     verify(char *name, int maxlen);
static void usage(void) __dead2;

#ifdef DEBUG
char    *interval(int time, char *updown);
void    Sendto(int s, const void *buf, size_t cc, int flags,
            const struct sockaddr *to, int tolen);
#define  sendto Sendto
#endif

/*
 * 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
 */
int
main(int argc, char *argv[])
{
        int on;
        char *cp;
        struct sockaddr_in soin;
        uid_t unpriv_uid;
        gid_t unpriv_gid;

        on = 1;
        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 && isdigit(*(argv + 1)[0])) {
                                argv++;
                                argc--;
                                multicast_mode  = SCOPED_MULTICAST;
                                multicast_scope = atoi(*argv);
                                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, "-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
        daemon(1, 0);
#endif
        (void) signal(SIGHUP, getboottime);
        openlog("rwhod", LOG_PID | LOG_NDELAY, LOG_DAEMON);
        sp = getservbyname("who", "udp");
        if (sp == NULL) {
                syslog(LOG_ERR, "who/udp: unknown service");
                exit(1);
        }
        if (chdir(_PATH_RWHODIR) < 0) {
                syslog(LOG_ERR, "%s: %m", _PATH_RWHODIR);
                exit(1);
        }
        /*
         * Establish host name as returned by system.
         */
        if (gethostname(myname, sizeof(myname) - 1) < 0) {
                syslog(LOG_ERR, "gethostname: %m");
                exit(1);
        }
        if ((cp = strchr(myname, '.')) != NULL)
                *cp = '\0';
        strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
        getboottime(0);
        if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
                syslog(LOG_ERR, "socket: %m");
                exit(1);
        }
        if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
                syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
                exit(1);
        }
        memset(&soin, 0, sizeof(soin));
        soin.sin_len = sizeof(soin);
        soin.sin_family = AF_INET;
        soin.sin_port = sp->s_port;
        if (bind(s, (struct sockaddr *)&soin, sizeof(soin)) < 0) {
                syslog(LOG_ERR, "bind: %m");
                exit(1);
        }
        if (setgroups(0, NULL) != 0) {
                syslog(LOG_ERR, "setgroups: %m");
                exit(1);
        }
        if (setgid(unpriv_gid) != 0) {
                syslog(LOG_ERR, "setgid: %m");
                exit(1);
        }
        if (setuid(unpriv_uid) != 0) {
                syslog(LOG_ERR, "setuid: %m");
                exit(1);
        }
        if (!configure(s))
                exit(1);
        if (!quiet_mode) {
                pid_child_receiver = pdfork(&fdp, 0);
                if (pid_child_receiver == 0) {
                        receiver_process();
                } else if (pid_child_receiver > 0) {
                        sender_process();
                } else if (pid_child_receiver == -1) {
                        if (errno == ENOSYS) {
                                syslog(LOG_ERR,
                                    "The pdfork(2) system call is not available - kernel too old.");
                        } else {
                                syslog(LOG_ERR, "pdfork: %m");
                        }
                        exit(1);
                }
        } else {
                receiver_process();
        }
}

static void
usage(void)
{

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

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

        pw = getpwnam(UNPRIV_USER);
        if (pw == NULL) {
                syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
                exit(1);
        }
        *uid = pw->pw_uid;

        gr = getgrnam(UNPRIV_GROUP);
        if (gr == NULL) {
                syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
                exit(1);
        }
        *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.
 */
int
verify(char *name, int maxlen)
{
        int size;

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

void
receiver_process(void)
{
        struct sockaddr_in from;
        struct stat st;
        cap_rights_t rights;
        char path[64];
        int dirfd;
        struct whod wd;
        socklen_t len;
        int cc, whod;
        time_t t;

        len = sizeof(from);
        dirfd = open(".", O_RDONLY | O_DIRECTORY);
        if (dirfd < 0) {
                syslog(LOG_WARNING, "%s: %m", _PATH_RWHODIR);
                exit(1);
        }
        cap_rights_init(&rights, CAP_CREATE, CAP_FSTAT, CAP_FTRUNCATE,
            CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
        if (caph_rights_limit(dirfd, &rights) < 0) {
                syslog(LOG_WARNING, "cap_rights_limit: %m");
                exit(1);
        }
        if (caph_enter() < 0) {
                syslog(LOG_ERR, "cap_enter: %m");
                exit(1);
        }
        for (;;) {
                cc = recvfrom(s, &wd, sizeof(wd), 0, (struct sockaddr *)&from,
                    &len);
                if (cc <= 0) {
                        if (cc < 0 && errno != EINTR)
                                syslog(LOG_WARNING, "recv: %m");
                        continue;
                }
                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));
                        continue;
                }
                if (cc < WHDRSIZE) {
                        syslog(LOG_WARNING, "short packet from %s",
                            inet_ntoa(from.sin_addr));
                        continue;
                }
                if (wd.wd_vers != WHODVERSION)
                        continue;
                if (wd.wd_type != WHODTYPE_STATUS)
                        continue;
                if (!verify(wd.wd_hostname, sizeof(wd.wd_hostname))) {
                        syslog(LOG_WARNING, "malformed host name from %s",
                            inet_ntoa(from.sin_addr));
                        continue;
                }
                (void) 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 = openat(dirfd, path, O_WRONLY | O_CREAT, 0644);
                if (whod < 0) {
                        syslog(LOG_WARNING, "%s: %m", path);
                        continue;
                }
                cap_rights_init(&rights, CAP_FSTAT, CAP_FTRUNCATE, CAP_WRITE);
                if (caph_rights_limit(whod, &rights) < 0) {
                        syslog(LOG_WARNING, "cap_rights_limit: %m");
                        exit(1);
                }
#if ENDIAN != BIG_ENDIAN
                {
                        struct whoent *we;
                        int i, n;

                        n = (cc - WHDRSIZE) / sizeof(struct whoent);
                        /* 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
                (void) time(&t);
                wd.wd_recvtime = _time_to_int(t);
                (void) write(whod, (char *)&wd, cc);
                if (fstat(whod, &st) < 0 || st.st_size > cc)
                        ftruncate(whod, cc);
                (void) close(whod);
        }
        (void) close(dirfd);
}

void
sender_process(void)
{
        int sendcount;
        double avenrun[3];
        time_t now;
        int i, cc, status;
        struct utmpx *ut;
        struct stat stb;
        struct neighbor *np;
        struct whoent *we, *wend;

        sendcount = 0;
        for (;;) {
                we = mywd.wd_we;
                now = time(NULL);
                if (sendcount % 10 == 0)
                        getboottime(0);
                sendcount++;
                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) < 0) {
                        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);
                }
                (void) getloadavg(avenrun,
                    nitems(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_to_time32(time(NULL)));
                mywd.wd_vers = WHODVERSION;
                mywd.wd_type = WHODTYPE_STATUS;
                if (multicast_mode == SCOPED_MULTICAST) {
                        (void) 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) != 0) {
                                        /*
                                         * 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) {
                                                syslog(LOG_ERR,
                                                    "setsockopt IP_MULTICAST_IF: %m");
                                                exit(1);
                                        }
                                        (void) sendto(s, (char *)&mywd, cc, 0,
                                            (struct sockaddr *)&multicast_addr,
                                            sizeof(multicast_addr));
                                } else {
                                        (void) sendto(s, (char *)&mywd, cc, 0,
                                            np->n_addr, np->n_addrlen);
                                }
                        }
                }
                if (chdir(_PATH_RWHODIR) < 0) {
                        syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
                        exit(1);
                }
                if (waitpid(pid_child_receiver, &status, WNOHANG) ==
                    pid_child_receiver) {
                        break;
                }
                sleep(SL_INTERVAL);
        }
}

void
getboottime(int signo __unused)
{
        int mib[2];
        size_t size;
        struct timeval tm;

        mib[0] = CTL_KERN;
        mib[1] = KERN_BOOTTIME;
        size = sizeof(tm);
        if (sysctl(mib, nitems(mib), &tm, &size, NULL, 0) == -1) {
                syslog(LOG_ERR, "cannot get boottime: %m");
                exit(1);
        }
        mywd.wd_boottime = htonl(_time_to_time32(tm.tv_sec));
}

void
quit(const char *msg)
{

        syslog(LOG_ERR, "%s", msg);
        exit(1);
}

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;
                sa = (struct sockaddr *)cp;
                rtinfo->rti_info[i] = sa;
                cp += SA_SIZE(sa);
        }
}

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

        flags = 0;
        if (multicast_mode != NO_MULTICAST) {
                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(so, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                    &mreq, sizeof(mreq)) < 0) {
                        syslog(LOG_ERR,
                            "setsockopt IP_ADD_MEMBERSHIP: %m");
                        return (0);
                }
                ttl = multicast_scope;
                if (setsockopt(so, 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, nitems(mib), NULL, &needed, NULL, 0) < 0)
                quit("route-sysctl-estimate");
        if ((buf = malloc(needed)) == NULL)
                quit("malloc");
        if (sysctl(mib, nitems(mib), buf, &needed, NULL, 0) < 0)
                quit("actual retrieval of interface table");
        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)
                        continue;
                lflags = IFF_BROADCAST | iff_flag;
                if (multicast_mode == PER_INTERFACE_MULTICAST)
                        lflags |= IFF_MULTICAST;
                if ((flags & lflags) == 0)
                        continue;
                if (ifm->ifm_type != RTM_NEWADDR)
                        quit("out of sync parsing NET_RT_IFLIST");
                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 = malloc(len);
                if (np == NULL)
                        quit("malloc of neighbor structure");
                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) != 0 &&
                    (flags & IFF_LOOPBACK) == 0) {
                        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(np);
                                continue;
#endif
                        }
                }
                np->n_next = neighbors;
                neighbors = np;
        }
        free(buf);
        return (1);
}

#ifdef DEBUG
void
Sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
    int tolen)
{
        struct whod *w;
        struct whoent *we;
        struct sockaddr_in *sin;

        w = (struct whod *)buf;
        sin = (struct sockaddr_in *)to;
        printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
            ntohs(sin->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 = _time32_to_time(ntohl(we->we_utmp.out_time));

                printf("%-8.8s %s:%s %.12s", we->we_utmp.out_name,
                    w->wd_hostname, we->we_utmp.out_line, ctime(&t) + 4);
                we->we_idle = ntohl(we->we_idle) / 60;
                if (we->we_idle != 0) {
                        if (we->we_idle >= 100 * 60)
                                we->we_idle = 100 * 60 - 1;
                        if (we->we_idle >= 60)
                                printf(" %2d", we->we_idle / 60);
                        else
                                printf("   ");
                        printf(":%02d", we->we_idle % 60);
                }
                printf("\n");
        }
}

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

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