xref: /onnv-gate/usr/src/cmd/cmd-inet/usr.sbin/in.rwhod.c (revision 473:9c6ea6da29de)

/*
 * 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