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      1 /*	$NetBSD: rwhod.c,v 1.41 2018/10/30 21:15:09 kre Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 __COPYRIGHT("@(#) Copyright (c) 1983, 1993\
     35  The Regents of the University of California.  All rights reserved.");
     36 #endif /* not lint */
     37 
     38 #ifndef lint
     39 #if 0
     40 static char sccsid[] = "@(#)rwhod.c	8.1 (Berkeley) 6/6/93";
     41 #else
     42 __RCSID("$NetBSD: rwhod.c,v 1.41 2018/10/30 21:15:09 kre Exp $");
     43 #endif
     44 #endif /* not lint */
     45 
     46 #include <sys/param.h>
     47 #include <sys/socket.h>
     48 #include <sys/stat.h>
     49 #include <sys/signal.h>
     50 #include <sys/ioctl.h>
     51 #include <sys/sysctl.h>
     52 
     53 #include <net/if.h>
     54 #include <net/if_dl.h>
     55 #include <net/route.h>
     56 #include <netinet/in.h>
     57 #include <protocols/rwhod.h>
     58 #include <arpa/inet.h>
     59 
     60 #include <ctype.h>
     61 #include <pwd.h>
     62 #include <err.h>
     63 #include <errno.h>
     64 #include <fcntl.h>
     65 #include <netdb.h>
     66 #include <paths.h>
     67 #include <poll.h>
     68 #include <stdio.h>
     69 #include <stdlib.h>
     70 #include <string.h>
     71 #include <syslog.h>
     72 #include <unistd.h>
     73 #include <util.h>
     74 
     75 #include "utmpentry.h"
     76 
     77 #define CHECK_INTERVAL (3 * 60)
     78 
     79 /* Time interval limit; ruptime will think that we are down > than this */
     80 #define MAX_INTERVAL (11 * 60)
     81 
     82 
     83 static char	myname[MAXHOSTNAMELEN + 1];
     84 
     85 /*
     86  * We communicate with each neighbor in a list constructed at the time we're
     87  * started up.  Neighbors are currently directly connected via a hardware
     88  * interface.
     89  */
     90 struct neighbor {
     91 	struct	neighbor *n_next;
     92 	char	*n_name;		/* interface name */
     93 	struct	sockaddr *n_addr;	/* who to send to */
     94 	int	n_addrlen;		/* size of address */
     95 	int	n_flags;		/* should forward?, interface flags */
     96 };
     97 
     98 static struct	neighbor *neighbors;
     99 static struct	whod mywd;
    100 static struct	servent *sp;
    101 static volatile sig_atomic_t  onsighup;
    102 
    103 #define	WHDRSIZE	(sizeof(mywd) - sizeof(mywd.wd_we))
    104 
    105 static int	 configure(int);
    106 static void	 getboottime(void);
    107 static void	 send_host_information(int);
    108 static void	 sighup(int);
    109 static void	 handleread(int);
    110 __dead static void	 quit(const char *);
    111 static void	 rt_xaddrs(void *, void *, struct rt_addrinfo *);
    112 static int	 drop_privs(char *);
    113 static void	 usage(void) __dead;
    114 static int	 verify(const char *);
    115 #ifdef DEBUG
    116 static char	*interval(int, const char *);
    117 static ssize_t	 Sendto(int, const void *, size_t, int,
    118     const struct sockaddr *, socklen_t);
    119 #else
    120 #define	 Sendto sendto
    121 #endif
    122 
    123 int
    124 main(int argc, char *argv[])
    125 {
    126 	int s, ch;
    127 	int time_interval = 180;	/* Default time (180 seconds) */
    128 	char *cp, *ep;
    129 	socklen_t on = 1;
    130 	struct sockaddr_in sasin;
    131 	struct pollfd pfd[1];
    132 	struct timeval delta, next, now;
    133 	char *newuser = NULL;
    134 
    135 	setprogname(argv[0]);
    136 
    137 	if (getuid())
    138 		errx(EXIT_FAILURE, "not super user");
    139 
    140 	while ((ch = getopt(argc, argv, "i:u:")) != -1) {
    141 		switch (ch) {
    142 		case 'i':
    143 			time_interval = (int)strtol(optarg, &ep, 10);
    144 
    145 			switch (*ep) {
    146 			case '\0':
    147 				break;
    148 			case 'm':
    149 			case 'M':
    150 				/* Time in minutes. */
    151 				time_interval *= 60;
    152 				if (ep[1] == '\0')
    153 					break;
    154 				/*FALLTHROUGH*/
    155 			default:
    156 				errx(1, "Invalid argument: `%s'", optarg);
    157 			}
    158 
    159 			if (time_interval <= 0)
    160 				errx(1, "Interval must be greater than 0");
    161 
    162 			if (time_interval > MAX_INTERVAL)
    163 				errx(1, "Interval cannot be greater than"
    164 				    " %d minutes", MAX_INTERVAL / 60);
    165 			break;
    166 
    167 		case 'u':
    168 			newuser = optarg;
    169 			break;
    170 
    171 		default:
    172 			usage();
    173 		}
    174 	}
    175 
    176 	sp = getservbyname("who", "udp");
    177 	if (sp == NULL)
    178 		errx(EXIT_FAILURE, "udp/who: unknown service");
    179 #ifndef DEBUG
    180 	(void)daemon(1, 0);
    181 	(void)pidfile(NULL);
    182 #endif
    183 	if (chdir(_PATH_RWHODIR) < 0)
    184 		err(EXIT_FAILURE, "%s", _PATH_RWHODIR);
    185 	(void)signal(SIGHUP, sighup);
    186 	openlog(getprogname(), LOG_PID, LOG_DAEMON);
    187 	/*
    188 	 * Establish host name as returned by system.
    189 	 */
    190 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
    191 		syslog(LOG_ERR, "gethostname: %m");
    192 		exit(EXIT_FAILURE);
    193 	}
    194 	myname[sizeof(myname) - 1] = '\0';
    195 	if ((cp = strchr(myname, '.')) != NULL)
    196 		*cp = '\0';
    197 	(void)strncpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname) - 1);
    198 	getboottime();
    199 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
    200 		syslog(LOG_ERR, "socket: %m");
    201 		exit(EXIT_FAILURE);
    202 	}
    203 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
    204 		syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
    205 		exit(EXIT_FAILURE);
    206 	}
    207 	(void)memset(&sasin, 0, sizeof(sasin));
    208 	sasin.sin_family = AF_INET;
    209 	sasin.sin_port = sp->s_port;
    210 	if (bind(s, (struct sockaddr *)&sasin, sizeof(sasin)) < 0) {
    211 		syslog(LOG_ERR, "bind: %m");
    212 		exit(EXIT_FAILURE);
    213 	}
    214 	if (!configure(s))
    215 		exit(EXIT_FAILURE);
    216 
    217 	if (newuser)
    218 		if (!drop_privs(newuser))
    219 			exit(EXIT_FAILURE);
    220 
    221 	send_host_information(s);
    222 	delta.tv_sec = time_interval;
    223 	delta.tv_usec = 0;
    224 	gettimeofday(&now, NULL);
    225 	timeradd(&now, &delta, &next);
    226 
    227 	pfd[0].fd = s;
    228 	pfd[0].events = POLLIN;
    229 
    230 	for (;;) {
    231 		int n;
    232 
    233 		n = poll(pfd, 1, 1000);
    234 
    235 		if (onsighup) {
    236 			onsighup = 0;
    237 			getboottime();
    238 		}
    239 
    240 		if (n == 1)
    241 			handleread(s);
    242 
    243 		(void)gettimeofday(&now, NULL);
    244 		if (timercmp(&now, &next, >)) {
    245 			send_host_information(s);
    246 			timeradd(&now, &delta, &next);
    247 		}
    248 	}
    249 
    250 	/* NOTREACHED */
    251 	return 0;
    252 }
    253 
    254 static void
    255 sighup(int signo __unused)
    256 {
    257 	onsighup = 1;
    258 }
    259 
    260 static void
    261 handleread(int s)
    262 {
    263 	struct sockaddr_in from;
    264 	struct stat st;
    265 	char path[64];
    266 	struct whod wd;
    267 	int cc, whod;
    268 	socklen_t len = sizeof(from);
    269 
    270 	cc = recvfrom(s, (char *)&wd, sizeof(struct whod), 0,
    271 		(struct sockaddr *)&from, &len);
    272 	if (cc <= 0) {
    273 		if (cc < 0 && errno != EINTR)
    274 			syslog(LOG_WARNING, "recv: %m");
    275 		return;
    276 	}
    277 	if (from.sin_port != sp->s_port) {
    278 		syslog(LOG_WARNING, "%d: bad from port",
    279 			ntohs(from.sin_port));
    280 		return;
    281 	}
    282 	if (cc < (int)WHDRSIZE) {
    283 		syslog(LOG_WARNING, "Short packet from %s",
    284 			inet_ntoa(from.sin_addr));
    285 		return;
    286 	}
    287 
    288 	if (wd.wd_vers != WHODVERSION)
    289 		return;
    290 	if (wd.wd_type != WHODTYPE_STATUS)
    291 		return;
    292 	/*
    293 	 * Ensure null termination of the name within the packet.
    294 	 * Otherwise we might overflow or read past the end.
    295 	 */
    296 	wd.wd_hostname[sizeof(wd.wd_hostname)-1] = 0;
    297 	if (!verify(wd.wd_hostname)) {
    298 		syslog(LOG_WARNING, "malformed host name from %s",
    299 		    inet_ntoa(from.sin_addr));
    300 		return;
    301 	}
    302 	(void)snprintf(path, sizeof(path), "whod.%s", wd.wd_hostname);
    303 	/*
    304 	 * Rather than truncating and growing the file each time,
    305 	 * use ftruncate if size is less than previous size.
    306 	 */
    307 	whod = open(path, O_WRONLY | O_CREAT, 0644);
    308 	if (whod < 0) {
    309 		syslog(LOG_WARNING, "%s: %m", path);
    310 		return;
    311 	}
    312 #if ENDIAN != BIG_ENDIAN
    313 	{
    314 		int i, n = (cc - WHDRSIZE) / sizeof(struct whoent);
    315 		struct whoent *we;
    316 
    317 		/* undo header byte swapping before writing to file */
    318 		wd.wd_sendtime = ntohl(wd.wd_sendtime);
    319 		for (i = 0; i < 3; i++)
    320 			wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
    321 		wd.wd_boottime = ntohl(wd.wd_boottime);
    322 		we = wd.wd_we;
    323 		for (i = 0; i < n; i++) {
    324 			we->we_idle = ntohl(we->we_idle);
    325 			we->we_utmp.out_time =
    326 			    ntohl(we->we_utmp.out_time);
    327 			we++;
    328 		}
    329 	}
    330 #endif
    331 	wd.wd_recvtime = time(NULL);
    332 	(void)write(whod, (char *)&wd, cc);
    333 	if (fstat(whod, &st) < 0 || st.st_size > cc)
    334 		(void)ftruncate(whod, cc);
    335 	(void)close(whod);
    336 }
    337 
    338 /*
    339  * Check out host name for unprintables
    340  * and other funnies before allowing a file
    341  * to be created.  Sorry, but blanks aren't allowed.
    342  */
    343 static int
    344 verify(const char *name)
    345 {
    346 	int size = 0;
    347 
    348 	while (*name) {
    349 		if (!isascii((unsigned char)*name) ||
    350 		    !(isalnum((unsigned char)*name) ||
    351 		    ispunct((unsigned char)*name)))
    352 			return 0;
    353 		name++, size++;
    354 	}
    355 	return size > 0;
    356 }
    357 
    358 static void
    359 send_host_information(int s)
    360 {
    361 	struct neighbor *np;
    362 	struct whoent *we = mywd.wd_we, *wlast;
    363 	int i, cc, utmpent = 0;
    364 	struct stat stb;
    365 	double avenrun[3];
    366 	time_t now;
    367 	static struct utmpentry *ohead = NULL;
    368 	struct utmpentry *ep;
    369 	static int count = 0;
    370 
    371 	now = time(NULL);
    372 	if (count % 10 == 0)
    373 		getboottime();
    374 	count++;
    375 
    376 	(void)getutentries(NULL, &ep);
    377 	/* XXX probably should expose utmp mtime, check that instead */
    378 	if (ep != ohead) {
    379 		wlast = &mywd.wd_we[1024 / sizeof(struct whoent) - 1];
    380 		for (; ep; ep = ep->next) {
    381 			(void)strncpy(we->we_utmp.out_line, ep->line,
    382 			    sizeof(we->we_utmp.out_line));
    383 			(void)strncpy(we->we_utmp.out_name, ep->name,
    384 			    sizeof(we->we_utmp.out_name));
    385 			we->we_utmp.out_time = htonl(ep->tv.tv_sec);
    386 			if (we >= wlast)
    387 				break;
    388 			we++;
    389 		}
    390 		utmpent = we - mywd.wd_we;
    391 	}
    392 
    393 	/*
    394 	 * The test on utmpent looks silly---after all, if no one is
    395 	 * logged on, why worry about efficiency?---but is useful on
    396 	 * (e.g.) compute servers.
    397 	 */
    398 	if (utmpent && chdir(_PATH_DEV)) {
    399 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
    400 		exit(EXIT_FAILURE);
    401 	}
    402 	we = mywd.wd_we;
    403 	for (i = 0; i < utmpent; i++) {
    404 		if (stat(we->we_utmp.out_line, &stb) >= 0)
    405 			we->we_idle = htonl(now - stb.st_atime);
    406 		we++;
    407 	}
    408 	(void)getloadavg(avenrun, sizeof(avenrun)/sizeof(avenrun[0]));
    409 	for (i = 0; i < 3; i++)
    410 		mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
    411 	cc = (char *)we - (char *)&mywd;
    412 	mywd.wd_sendtime = htonl(time(0));
    413 	mywd.wd_vers = WHODVERSION;
    414 	mywd.wd_type = WHODTYPE_STATUS;
    415 	for (np = neighbors; np != NULL; np = np->n_next)
    416 		(void)Sendto(s, (char *)&mywd, cc, 0,
    417 				np->n_addr, np->n_addrlen);
    418 	if (utmpent && chdir(_PATH_RWHODIR)) {
    419 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
    420 		exit(EXIT_FAILURE);
    421 	}
    422 }
    423 
    424 static void
    425 getboottime(void)
    426 {
    427 	int mib[2];
    428 	size_t size;
    429 	struct timespec tm;
    430 
    431 	mib[0] = CTL_KERN;
    432 	mib[1] = KERN_BOOTTIME;
    433 	size = sizeof(tm);
    434 	if (sysctl(mib, 2, &tm, &size, NULL, 0) == -1) {
    435 		syslog(LOG_ERR, "cannot get boottime: %m");
    436 		exit(EXIT_FAILURE);
    437 	}
    438 	mywd.wd_boottime = htonl(tm.tv_sec);
    439 }
    440 
    441 static void
    442 quit(const char *msg)
    443 {
    444 	syslog(LOG_ERR, "%s", msg);
    445 	exit(EXIT_FAILURE);
    446 }
    447 
    448 #define ROUNDUP(a) \
    449 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
    450 #define ADVANCE(x, n) ((char *)(x) + ROUNDUP((n)->sa_len))
    451 
    452 static void
    453 rt_xaddrs(void *cp, void *cplim, struct rt_addrinfo *rtinfo)
    454 {
    455 	struct sockaddr *sa;
    456 	int i;
    457 
    458 	(void)memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
    459 	for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
    460 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
    461 			continue;
    462 		rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
    463 		cp = ADVANCE(cp, sa);
    464 	}
    465 }
    466 
    467 /*
    468  * Figure out device configuration and select
    469  * networks which deserve status information.
    470  */
    471 static int
    472 configure(int s)
    473 {
    474 	struct neighbor *np;
    475 	struct if_msghdr *ifm;
    476 	struct ifa_msghdr *ifam;
    477 	struct sockaddr_dl *sdl;
    478 	size_t needed;
    479 	int mib[6], flags = 0, len;
    480 	char *buf, *lim, *next;
    481 	struct rt_addrinfo info;
    482 	struct sockaddr_in dstaddr;
    483 
    484 	mib[0] = CTL_NET;
    485 	mib[1] = PF_ROUTE;
    486 	mib[2] = 0;
    487 	mib[3] = AF_INET;
    488 	mib[4] = NET_RT_IFLIST;
    489 	mib[5] = 0;
    490 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
    491 		quit("route-sysctl-estimate");
    492 	if ((buf = malloc(needed)) == NULL)
    493 		quit("malloc");
    494 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
    495 		quit("actual retrieval of interface table");
    496 	lim = buf + needed;
    497 
    498 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
    499 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
    500 		ifm = (struct if_msghdr *)next;
    501 		if (ifm->ifm_type == RTM_IFINFO) {
    502 			sdl = (struct sockaddr_dl *)(ifm + 1);
    503 			flags = ifm->ifm_flags;
    504 			continue;
    505 		}
    506 		if ((flags & IFF_UP) == 0 ||
    507 		    (flags & (IFF_BROADCAST|IFF_POINTOPOINT)) == 0)
    508 			continue;
    509 		if (ifm->ifm_type != RTM_NEWADDR)
    510 			quit("out of sync parsing NET_RT_IFLIST");
    511 		ifam = (struct ifa_msghdr *)ifm;
    512 		info.rti_addrs = ifam->ifam_addrs;
    513 		rt_xaddrs((ifam + 1), ifam->ifam_msglen + (char *)ifam, &info);
    514 		/* gag, wish we could get rid of Internet dependencies */
    515 		if (info.rti_info[RTAX_BRD] == NULL ||
    516 		    info.rti_info[RTAX_BRD]->sa_family != AF_INET)
    517 			continue;
    518 		(void)memcpy(&dstaddr, info.rti_info[RTAX_BRD],
    519 		    sizeof(dstaddr));
    520 #define IPADDR_SA(x) ((struct sockaddr_in *)(x))->sin_addr.s_addr
    521 #define PORT_SA(x) ((struct sockaddr_in *)(x))->sin_port
    522 		PORT_SA(&dstaddr) = sp->s_port;
    523 		for (np = neighbors; np != NULL; np = np->n_next)
    524 			if (memcmp(sdl->sdl_data, np->n_name,
    525 				   sdl->sdl_nlen) == 0 &&
    526 			    IPADDR_SA(np->n_addr) == IPADDR_SA(&dstaddr))
    527 				break;
    528 		if (np != NULL)
    529 			continue;
    530 		len = sizeof(*np) + dstaddr.sin_len + sdl->sdl_nlen + 1;
    531 		np = (struct neighbor *)malloc(len);
    532 		if (np == NULL)
    533 			quit("malloc of neighbor structure");
    534 		(void)memset(np, 0, len);
    535 		np->n_flags = flags;
    536 		np->n_addr = (struct sockaddr *)(np + 1);
    537 		np->n_addrlen = dstaddr.sin_len;
    538 		np->n_name = np->n_addrlen + (char *)np->n_addr;
    539 		np->n_next = neighbors;
    540 		neighbors = np;
    541 		(void)memcpy(np->n_addr, &dstaddr, np->n_addrlen);
    542 		(void)memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
    543 	}
    544 	free(buf);
    545 	return (1);
    546 }
    547 
    548 #ifdef DEBUG
    549 static ssize_t
    550 Sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
    551     socklen_t tolen)
    552 {
    553 	struct whod *w = (struct whod *)buf;
    554 	struct whoent *we;
    555 	struct sockaddr_in *sasin = (struct sockaddr_in *)to;
    556 	ssize_t ret;
    557 
    558 	ret = sendto(s, buf, cc, flags, to, tolen);
    559 
    560 	printf("sendto %s.%d\n", inet_ntoa(sasin->sin_addr),
    561 	    ntohs(sasin->sin_port));
    562 	printf("hostname %s %s\n", w->wd_hostname,
    563 	   interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
    564 	printf("load %4.2f, %4.2f, %4.2f\n",
    565 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
    566 	    ntohl(w->wd_loadav[2]) / 100.0);
    567 	cc -= WHDRSIZE;
    568 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
    569 		time_t t = ntohl(we->we_utmp.out_time);
    570 		printf("%-8.8s %s:%s %.12s", we->we_utmp.out_name,
    571 		    w->wd_hostname, we->we_utmp.out_line, ctime(&t)+4);
    572 		we->we_idle = ntohl(we->we_idle) / 60;
    573 		if (we->we_idle) {
    574 			if (we->we_idle >= 100*60)
    575 				we->we_idle = 100*60 - 1;
    576 			if (we->we_idle >= 60)
    577 				printf(" %2d", we->we_idle / 60);
    578 			else
    579 				printf("   ");
    580 			printf(":%02d", we->we_idle % 60);
    581 		}
    582 		printf("\n");
    583 	}
    584 	return ret;
    585 }
    586 
    587 static char *
    588 interval(int time, const char *updown)
    589 {
    590 	static char resbuf[32];
    591 	int days, hours, minutes;
    592 
    593 	if (time < 0 || time > 3*30*24*60*60) {
    594 		(void)snprintf(resbuf, sizeof(resbuf), "   %s ??:??", updown);
    595 		return (resbuf);
    596 	}
    597 	minutes = (time + 59) / 60;		/* round to minutes */
    598 	hours = minutes / 60; minutes %= 60;
    599 	days = hours / 24; hours %= 24;
    600 	if (days)
    601 		(void)snprintf(resbuf, sizeof(resbuf), "%s %2d+%02d:%02d",
    602 		    updown, days, hours, minutes);
    603 	else
    604 		(void)snprintf(resbuf, sizeof(resbuf), "%s    %2d:%02d",
    605 		    updown, hours, minutes);
    606 	return resbuf;
    607 }
    608 #endif
    609 
    610 static int
    611 drop_privs(char *newuser)
    612 {
    613 	struct passwd *pw;
    614 	gid_t gidset[1];
    615 
    616 	pw = getpwnam(newuser);
    617 	if (pw == NULL) {
    618 		syslog(LOG_ERR, "no user %.100s", newuser);
    619 		return 0;
    620 	}
    621 
    622 	endpwent();
    623 
    624 	gidset[0] = pw->pw_gid;
    625 	if (setgroups(1, gidset) == -1) {
    626 		syslog(LOG_ERR, "setgroups: %m");
    627 		return 0;
    628 	}
    629 
    630 	if (setgid(pw->pw_gid) == -1) {
    631 		syslog(LOG_ERR, "setgid: %m");
    632 		return 0;
    633 	}
    634 
    635 	if (setuid(pw->pw_uid) == -1) {
    636 		syslog(LOG_ERR, "setuid: %m");
    637 		return 0;
    638 	}
    639 
    640 	return 1;
    641 }
    642 
    643 static void
    644 usage(void)
    645 {
    646 	(void)fprintf(stderr, "Usage: %s [-i interval] [-u user]\n", getprogname());
    647 	exit(EXIT_FAILURE);
    648 }
    649