cmd-inet/usr.sbin: remove -Wno-implicit-function-declaration

[unleashed.git] / usr / src / cmd / cmd-inet / usr.sbin / in.rwhod.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/file.h>
#include <sys/loadavg.h>

#include <net/if.h>
#include <netinet/in.h>

#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <utmpx.h>
#include <ctype.h>
#include <netdb.h>
#include <syslog.h>
#include <fcntl.h>
#include <sys/isa_defs.h>       /* for ENDIAN defines */
#include <arpa/inet.h>
#include <protocols/rwhod.h>

#include <strings.h>
#include <stdlib.h>
#include <unistd.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 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       (ulong_t)0xe0000103     /* 224.0.1.3 */
                                        /* (belongs in protocols/rwhod.h) */

static int                      multicast_mode  = NO_MULTICAST;
static int                      multicast_scope;
static struct sockaddr_in       multicast_addr  = { AF_INET };


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

static struct   sockaddr_in sin = { AF_INET };

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 */
        char    *n_addr;                /* who to send to */
        int     n_addrlen;              /* size of address */
        ulong_t n_subnet;               /* AF_INET subnet */
        uint_t  n_flags;                /* should forward?, interface flags */
};

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

#define WHDRSIZE        (sizeof (mywd) - sizeof (mywd.wd_we))
#define RWHODIR         "/var/spool/rwho"

static void             onalrm(void);
static void             getkmem(void);
static boolean_t        configure(int);
static int              verify(const struct whod *);

int
main(int argc, char *argv[])
{
        struct sockaddr_in from;
        struct stat st;
        char path[64];
        struct hostent *hp;
        int on = 1;
        char *cp;
        struct stat sb;

        if (getuid()) {
                (void) fprintf(stderr, "in.rwhod: not super user\n");
                exit(1);
        }
        sp = getservbyname("who", "udp");
        if (sp == NULL) {
                (void) fprintf(stderr, "in.rwhod: udp/who: unknown service\n");
                exit(1);
        }
        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) {
                                        (void) fprintf(stderr,
                                            "in.rwhod: "
                                            "ttl must not exceed %u\n",
                                            MAX_MULTICAST_SCOPE);
                                        exit(1);
                                }
                        } else {
                                multicast_mode = PER_INTERFACE_MULTICAST;
                        }
                } else {
                        goto usage;
                }
                argv++;
                argc--;
        }
        if (argc > 0)
                goto usage;
        if (chdir(RWHODIR) < 0) {
                perror(RWHODIR);
                exit(1);
        }
#ifndef DEBUG
        if (fork())
                exit(0);
        /* CSTYLED */
        {
                (void) close(0);
                (void) close(1);
                (void) close(2);
                (void) open("/", 0);
                (void) dup2(0, 1);
                (void) dup2(0, 2);
                (void) setsid();
        }
#endif
        (void) sigset(SIGHUP, (void (*)())getkmem);
        openlog("in.rwhod", LOG_PID, LOG_DAEMON);
        /*
         * Establish host name as returned by system.
         */
        if (gethostname(myname, sizeof (myname) - 1) < 0) {
                syslog(LOG_ERR, "main: gethostname: %m");
                exit(1);
        }
        if ((cp = index(myname, '.')) != NULL)
                *cp = '\0';
        (void) strlcpy(mywd.wd_hostname, myname, sizeof (mywd.wd_hostname));

        if (stat(UTMPX_FILE, &sb) < 0) {
                syslog(LOG_ERR, "main: stat: %s: %m", UTMPX_FILE);
                exit(1);
        }
        getkmem();
        if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
                syslog(LOG_ERR, "main: socket: %m");
                exit(1);
        }
        if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof (on)) < 0) {
                syslog(LOG_ERR, "main: setsockopt SO_BROADCAST: %m");
                exit(1);
        }
        hp = gethostbyname(myname);
        if (hp == NULL) {
                syslog(LOG_ERR, "main: %s: don't know my own name\n", myname);
                exit(1);
        }
        sin.sin_family = hp->h_addrtype;
        sin.sin_port = sp->s_port;
        if (bind(s, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
                syslog(LOG_ERR, "main: bind: %m");
                exit(1);
        }
        if (!configure(s))
                exit(1);
        (void) sigset(SIGALRM, (void (*)())onalrm);
        onalrm();
        for (;;) {
                struct whod wd;
                int cc, whod;
                socklen_t len = sizeof (from);

                cc = recvfrom(s, &wd, sizeof (struct whod), 0,
                    (struct sockaddr *)&from, &len);
                if (cc <= 0) {
                        if (cc < 0 && errno != EINTR)
                                syslog(LOG_WARNING, "main: recvfrom: %m");
                        continue;
                }
                if (from.sin_port != sp->s_port) {
                        syslog(LOG_WARNING, "main: %d: bad from port",
                            ntohs(from.sin_port));
                        continue;
                }
#ifdef notdef
                if (gethostbyname(wd.wd_hostname) == 0) {
                        syslog(LOG_WARNING, "main: %s: unknown host",
                            wd.wd_hostname);
                        continue;
                }
#endif
                if (wd.wd_vers != WHODVERSION)
                        continue;
                if (wd.wd_type != WHODTYPE_STATUS)
                        continue;
                if (!verify(&wd)) {
                        syslog(LOG_WARNING, "main: malformed host name from %x",
                            from.sin_addr.s_addr);
                        continue;
                }
                (void) sprintf(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, "main: open: %s: %m", path);
                        continue;
                }
#if defined(_LITTLE_ENDIAN)
                /* CSTYLED */
                {
                        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
                (void) time((time_t *)&wd.wd_recvtime);
                (void) write(whod, &wd, cc);
                if (fstat(whod, &st) < 0 || st.st_size > cc)
                        (void) ftruncate(whod, cc);
                (void) close(whod);
        }
        /* NOTREACHED */
usage:
        (void) fprintf(stderr, "usage: in.rwhod [ -m [ ttl ] ]\n");
        return (1);
}

/*
 * 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(const struct whod *wd)
{
        int size = 0;
        const char *name = wd->wd_hostname;

        /*
         * We shouldn't assume the name is NUL terminated, so bound the
         * checks at the size of the whod structures wd_hostname field.
         */
        while ((size < sizeof (wd->wd_hostname)) &&
            (*name != '\0')) {
                if (*name == '/' || !isascii(*name) ||
                    !(isalnum(*name) || ispunct(*name)))
                        return (0);
                name++, size++;
        }
        /*
         * Fail the verification if NULL name or it wasn't NUL terminated.
         */
        return ((size > 0) && (size < sizeof (wd->wd_hostname)));
}

static int      utmpxtime;
static int      utmpxent;
static int      alarmcount;
struct  utmpx *utmpx;

static void
onalrm(void)
{
        int i;
        struct stat stb;
        int     utmpxsize = 0;
        int     entries;
        struct  utmpx *utp;
        struct  utmpx *utmpxbegin;
        struct whoent *we = mywd.wd_we, *wlast;
        int cc, cnt;
        double avenrun[3];

        time_t now = time(0);
        struct neighbor *np;

        if (alarmcount % 10 == 0)
                getkmem();
        alarmcount++;
        (void) stat(UTMPX_FILE, &stb);
        entries = stb.st_size / sizeof (struct futmpx);
        if ((stb.st_mtime != utmpxtime) || (entries > utmpxent)) {
                utmpxtime = stb.st_mtime;
                if (entries > utmpxent) {
                        utmpxent = entries;
                        utmpxsize = utmpxent * sizeof (struct utmpx);
                        utmpx = realloc(utmpx, utmpxsize);
                        if (utmpx == NULL) {
                                syslog(LOG_ERR, "onalrm: realloc: %m");
                                utmpxsize = 0;
                                goto done;
                        }
                }
                utmpxbegin = utmpx;
                setutxent();
                cnt = 0;
                while (cnt++ < utmpxent && (utp = getutxent()) != NULL)
                        (void) memcpy(utmpxbegin++, utp, sizeof (struct utmpx));
                endutxent();
                wlast = &mywd.wd_we[1024 / sizeof (struct whoent) - 1];
                for (i = 0; i < utmpxent; i++) {
                        if (utmpx[i].ut_name[0] &&
                            utmpx[i].ut_type == USER_PROCESS) {
                                /*
                                 * XXX - utmpx name and line lengths should
                                 * be here
                                 */
                                bcopy(utmpx[i].ut_line, we->we_utmp.out_line,
                                    sizeof (we->we_utmp.out_line));
                                bcopy(utmpx[i].ut_name, we->we_utmp.out_name,
                                    sizeof (we->we_utmp.out_name));
                                we->we_utmp.out_time =
                                    htonl(utmpx[i].ut_xtime);
                                if (we >= wlast)
                                        break;
                                we++;
                        }
                }
                utmpxent = we - mywd.wd_we;
        }

        /*
         * The test on utmpxent looks silly---after all, if no one is
         * logged on, why worry about efficiency?---but is useful on
         * (e.g.) compute servers.
         */
        if (utmpxent > 0 && chdir("/dev") == -1) {
                syslog(LOG_ERR, "onalrm: chdir /dev: %m");
                exit(1);
        }
        we = mywd.wd_we;
        for (i = 0; i < utmpxent; i++) {
                if (stat(we->we_utmp.out_line, &stb) >= 0)
                        we->we_idle = htonl(now - stb.st_atime);
                we++;
        }
        if (getloadavg(avenrun, 3) == -1) {
                syslog(LOG_ERR, "onalrm: getloadavg: %m");
                exit(1);
        }

        for (i = 0; i < 3; i++)
                mywd.wd_loadav[i] = htonl((ulong_t)(avenrun[i] * 100));
        cc = (char *)we - (char *)&mywd;
        mywd.wd_sendtime = htonl(time(0));
        mywd.wd_vers = WHODVERSION;
        mywd.wd_type = WHODTYPE_STATUS;
        if (multicast_mode == SCOPED_MULTICAST) {
                (void) sendto(s, &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) {
                                syslog(LOG_ERR,
                                    "onalrm: setsockopt IP_MULTICAST_IF: %m");
                                exit(1);
                        }
                        (void) sendto(s, &mywd, cc, 0,
                            (struct sockaddr *)&multicast_addr,
                            sizeof (multicast_addr));
                } else {
                        (void) sendto(s, &mywd, cc, 0,
                            (struct sockaddr *)np->n_addr, np->n_addrlen);
                }
        }
        if (utmpxent > 0 && chdir(RWHODIR) == -1) {
                syslog(LOG_ERR, "onalrm: chdir %s: %m", RWHODIR);
                exit(1);
        }
done:
        (void) alarm(AL_INTERVAL);
}

static void
getkmem(void)
{
        struct utmpx *utmpx, utmpx_id;

        utmpx_id.ut_type = BOOT_TIME;
        if ((utmpx = getutxid(&utmpx_id)) != NULL)
                mywd.wd_boottime = utmpx->ut_xtime;
        endutxent();
        mywd.wd_boottime = htonl(mywd.wd_boottime);
}

/*
 * Figure out device configuration and select
 * networks which deserve status information.
 */
static boolean_t
configure(int s)
{
        char *buf;
        struct ifconf ifc;
        struct ifreq ifreq, *ifr;
        struct sockaddr_in *sin;
        struct neighbor *np;
        struct neighbor *np2;
        int n;
        int numifs;
        unsigned bufsize;

        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(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
                    sizeof (mreq)) < 0) {
                        syslog(LOG_ERR,
                            "configure: setsockopt IP_ADD_MEMBERSHIP: %m");
                        return (B_FALSE);
                }
                ttl = multicast_scope;
                if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
                    sizeof (ttl)) < 0) {
                        syslog(LOG_ERR,
                            "configure: setsockopt IP_MULTICAST_TTL: %m");
                        return (B_FALSE);
                }
                multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
                multicast_addr.sin_port = sp->s_port;
                return (B_TRUE);
        }

        if (ioctl(s, SIOCGIFNUM, (char *)&numifs) < 0) {
                syslog(LOG_ERR, "configure: ioctl SIOCGIFNUM: %m");
                return (B_FALSE);
        }
        bufsize = numifs * sizeof (struct ifreq);
        buf = malloc(bufsize);
        if (buf == NULL) {
                syslog(LOG_ERR, "configure: malloc: %m");
                return (B_FALSE);
        }
        ifc.ifc_len = bufsize;
        ifc.ifc_buf = buf;
        if (ioctl(s, SIOCGIFCONF, (char *)&ifc) < 0) {
                syslog(LOG_ERR,
                    "configure: ioctl (get interface configuration): %m");
                (void) free(buf);
                return (B_FALSE);
        }
        ifr = ifc.ifc_req;
        for (n = ifc.ifc_len / sizeof (struct ifreq); n > 0; n--, ifr++) {
                /* Skip all logical interfaces */
                if (index(ifr->ifr_name, ':') != NULL)
                        continue;

                for (np = neighbors; np != NULL; np = np->n_next) {
                        if (np->n_name &&
                            strcmp(ifr->ifr_name, np->n_name) == 0)
                                break;
                }
                if (np != NULL)
                        continue;
                ifreq = *ifr;
                np = (struct neighbor *)malloc(sizeof (*np));
                if (np == NULL)
                        continue;
                np->n_name = malloc(strlen(ifr->ifr_name) + 1);
                if (np->n_name == NULL) {
                        free(np);
                        continue;
                }
                (void) strcpy(np->n_name, ifr->ifr_name);
                np->n_addrlen = sizeof (ifr->ifr_addr);
                np->n_addr = malloc(np->n_addrlen);
                if (np->n_addr == NULL) {
                        free(np->n_name);
                        free(np);
                        continue;
                }
                bcopy(&ifr->ifr_addr, np->n_addr, np->n_addrlen);
                if (ioctl(s, SIOCGIFFLAGS, (char *)&ifreq) < 0) {
                        syslog(LOG_ERR,
                            "configure: ioctl (get interface flags): %m");
                        free(np->n_addr);
                        free(np->n_name);
                        free(np);
                        continue;
                }
                np->n_flags = ifreq.ifr_flags;
                if (((struct sockaddr_in *)np->n_addr)->sin_family == AF_INET &&
                    ioctl(s, SIOCGIFNETMASK, (char *)&ifreq) >= 0) {
                        sin = (struct sockaddr_in *)np->n_addr;

                        np->n_subnet = sin->sin_addr.s_addr &
                            ((struct sockaddr_in *)&ifreq.ifr_addr)->
                            sin_addr.s_addr;
                }
                if (multicast_mode == PER_INTERFACE_MULTICAST &&
                    (np->n_flags & IFF_UP) &&
                    (np->n_flags & IFF_MULTICAST) &&
                    !(np->n_flags & IFF_LOOPBACK)) {
                        struct ip_mreq mreq;

                        /*
                         * Skip interfaces that have matching subnets i.e.
                         * (addr & netmask) are identical.
                         * Such interfaces are connected to the same
                         * physical wire.
                         */
                        for (np2 = neighbors; np2 != NULL; np2 = np2->n_next) {

                                if (!(np->n_flags & IFF_POINTOPOINT) &&
                                    !(np2->n_flags & IFF_POINTOPOINT) &&
                                    (np->n_subnet == np2->n_subnet)) {
                                        free(np->n_addr);
                                        free(np->n_name);
                                        free(np);
                                        break;
                                }
                        }
                        if (np2 != NULL)
                                continue;

                        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,
                                    "configure: "
                                    "setsockopt IP_ADD_MEMBERSHIP: %m");
                                free(np->n_addr);
                                free(np->n_name);
                                free(np);
                                continue;
                        }
                        multicast_addr.sin_addr.s_addr =
                            htonl(INADDR_WHOD_GROUP);
                        multicast_addr.sin_port = sp->s_port;
                        np->n_next = neighbors;
                        neighbors = np;
                        continue;
                }
                if ((np->n_flags & IFF_UP) == 0 ||
                    (np->n_flags & (IFF_BROADCAST|IFF_POINTOPOINT)) == 0) {
                        free(np->n_addr);
                        free(np->n_name);
                        free(np);
                        continue;
                }
                if (np->n_flags & IFF_POINTOPOINT) {
                        if (ioctl(s, SIOCGIFDSTADDR, (char *)&ifreq) < 0) {
                                syslog(LOG_ERR,
                                    "configure: ioctl (get dstaddr): %m");
                                free(np->n_addr);
                                free(np->n_name);
                                free(np);
                                continue;
                        }
                        /* we assume addresses are all the same size */
                        bcopy(&ifreq.ifr_dstaddr, np->n_addr, np->n_addrlen);
                }
                if (np->n_flags & IFF_BROADCAST) {
                        if (ioctl(s, SIOCGIFBRDADDR, (char *)&ifreq) < 0) {
                                syslog(LOG_ERR,
                                    "configure: ioctl (get broadaddr): %m");
                                free(np->n_addr);
                                free(np->n_name);
                                free(np);
                                continue;
                        }
                        /* we assume addresses are all the same size */
                        bcopy(&ifreq.ifr_broadaddr, np->n_addr, np->n_addrlen);
                }
                /* gag, wish we could get rid of Internet dependencies */
                sin = (struct sockaddr_in *)np->n_addr;
                sin->sin_port = sp->s_port;

                /*
                 * Avoid adding duplicate broadcast and pt-pt destinations
                 * to the list.
                 */
                for (np2 = neighbors; np2 != NULL; np2 = np2->n_next) {
                        struct sockaddr_in *sin2;

                        sin2 = (struct sockaddr_in *)np2->n_addr;
                        if (sin2->sin_addr.s_addr == sin->sin_addr.s_addr) {
                                free(np->n_addr);
                                free(np->n_name);
                                free(np);
                                break;
                        }
                }
                if (np2 != NULL)
                        continue;

                np->n_next = neighbors;
                neighbors = np;
        }
        (void) free(buf);
        return (B_TRUE);
}

#ifdef DEBUG
static char *interval(uint_t, char *);

/* ARGSUSED */
static ssize_t
sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
    socklen_t tolen)
{
        struct whod *w = (struct whod *)buf;
        struct whoent *we;
        struct sockaddr_in *sin = (struct sockaddr_in *)to;
        int nsz;

        (void) printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
            ntohs(sin->sin_port));
        (void) printf("hostname %s %s\n", w->wd_hostname,
            interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
        (void) 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);

                nsz = sizeof (we->we_utmp.out_name);
                (void) printf("%-*.*s %s:%s %.12s",
                    nsz,
                    nsz,
                    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) {
                        if (we->we_idle >= 100*60)
                                we->we_idle = 100*60 - 1;
                        if (we->we_idle >= 60)
                                (void) printf(" %2d", we->we_idle / 60);
                        else
                                (void) printf("   ");
                        (void) printf(":%02d", we->we_idle % 60);
                }
                (void) printf("\n");
        }
        return (0);
}

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

        if (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