xref: /freebsd/usr.sbin/rwhod/rwhod.c (revision ddd5b8e9b4d8957fce018c520657cdfa4ecffad3)
1 /*
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #ifndef lint
31 static const char copyright[] =
32 "@(#) Copyright (c) 1983, 1993\n\
33 	The Regents of the University of California.  All rights reserved.\n";
34 #endif /* not lint */
35 
36 #if 0
37 #ifndef lint
38 static char sccsid[] = "@(#)rwhod.c	8.1 (Berkeley) 6/6/93";
39 #endif /* not lint */
40 #endif
41 
42 #include <sys/cdefs.h>
43 __FBSDID("$FreeBSD$");
44 
45 #include <sys/param.h>
46 #include <sys/socket.h>
47 #include <sys/stat.h>
48 #include <sys/signal.h>
49 #include <sys/ioctl.h>
50 #include <sys/sysctl.h>
51 
52 #include <net/if.h>
53 #include <net/if_dl.h>
54 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <arpa/inet.h>
57 #include <protocols/rwhod.h>
58 
59 #include <ctype.h>
60 #include <err.h>
61 #include <errno.h>
62 #include <fcntl.h>
63 #include <netdb.h>
64 #include <paths.h>
65 #include <stdio.h>
66 #include <stdlib.h>
67 #include <string.h>
68 #include <syslog.h>
69 #include <timeconv.h>
70 #include <unistd.h>
71 #include <utmpx.h>
72 #include <pwd.h>
73 #include <grp.h>
74 
75 /*
76  * This version of Berkeley's rwhod has been modified to use IP multicast
77  * datagrams, under control of a new command-line option:
78  *
79  *	rwhod -m	causes rwhod to use IP multicast (instead of
80  *			broadcast or unicast) on all interfaces that have
81  *			the IFF_MULTICAST flag set in their "ifnet" structs
82  *			(excluding the loopback interface).  The multicast
83  *			reports are sent with a time-to-live of 1, to prevent
84  *			forwarding beyond the directly-connected subnet(s).
85  *
86  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
87  *			time-to-live of <ttl>, via a SINGLE interface rather
88  *			than all interfaces.  <ttl> must be between 0 and
89  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
90  *			is different than "-m", in that "-m 1" specifies
91  *			transmission on one interface only.
92  *
93  * When "-m" is used without a <ttl> argument, the program accepts multicast
94  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
95  * is given, it accepts multicast reports from only one interface, the one
96  * on which reports are sent (which may be controlled via the host's routing
97  * table).  Regardless of the "-m" option, the program accepts broadcast or
98  * unicast reports from all interfaces.  Thus, this program will hear the
99  * reports of old, non-multicasting rwhods, but, if multicasting is used,
100  * those old rwhods won't hear the reports generated by this program.
101  *
102  *                  -- Steve Deering, Stanford University, February 1989
103  */
104 
105 #define	UNPRIV_USER		"daemon"
106 #define	UNPRIV_GROUP		"daemon"
107 
108 #define NO_MULTICAST		0	  /* multicast modes */
109 #define PER_INTERFACE_MULTICAST	1
110 #define SCOPED_MULTICAST	2
111 
112 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
113 
114 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
115 					  /* (belongs in protocols/rwhod.h) */
116 
117 int			insecure_mode;
118 int			quiet_mode;
119 int			iff_flag = IFF_POINTOPOINT;
120 int			multicast_mode  = NO_MULTICAST;
121 int			multicast_scope;
122 struct sockaddr_in	multicast_addr  =
123 	{ sizeof multicast_addr, AF_INET, 0, { 0 }, { 0 } };
124 
125 /*
126  * Alarm interval. Don't forget to change the down time check in ruptime
127  * if this is changed.
128  */
129 #define AL_INTERVAL (3 * 60)
130 
131 char	myname[MAXHOSTNAMELEN];
132 
133 /*
134  * We communicate with each neighbor in a list constructed at the time we're
135  * started up.  Neighbors are currently directly connected via a hardware
136  * interface.
137  */
138 struct	neighbor {
139 	struct	neighbor *n_next;
140 	char	*n_name;		/* interface name */
141 	struct	sockaddr *n_addr;		/* who to send to */
142 	int	n_addrlen;		/* size of address */
143 	int	n_flags;		/* should forward?, interface flags */
144 };
145 
146 struct	neighbor *neighbors;
147 struct	whod mywd;
148 struct	servent *sp;
149 int	s;
150 
151 #define	WHDRSIZE	(int)(sizeof(mywd) - sizeof(mywd.wd_we))
152 
153 void	 run_as(uid_t *, gid_t *);
154 int	 configure(int);
155 void	 getboottime(int);
156 void	 onalrm(int);
157 void	 quit(const char *);
158 void	 rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
159 int	 verify(char *, int);
160 static void usage(void);
161 #ifdef DEBUG
162 char	*interval(int, char *);
163 void	 Sendto(int, const void *, size_t, int, const struct sockaddr *, int);
164 #define	 sendto Sendto
165 #endif
166 
167 int
168 main(int argc, char *argv[])
169 {
170 	struct sockaddr_in from;
171 	struct stat st;
172 	char path[64];
173 	int on = 1;
174 	char *cp;
175 	struct sockaddr_in soin;
176 	uid_t unpriv_uid;
177 	gid_t unpriv_gid;
178 
179 	if (getuid())
180 		errx(1, "not super user");
181 
182 	run_as(&unpriv_uid, &unpriv_gid);
183 
184 	argv++; argc--;
185 	while (argc > 0 && *argv[0] == '-') {
186 		if (strcmp(*argv, "-m") == 0) {
187 			if (argc > 1 && isdigit(*(argv + 1)[0])) {
188 				argv++, argc--;
189 				multicast_mode  = SCOPED_MULTICAST;
190 				multicast_scope = atoi(*argv);
191 				if (multicast_scope > MAX_MULTICAST_SCOPE)
192 					errx(1, "ttl must not exceed %u",
193 					MAX_MULTICAST_SCOPE);
194 			}
195 			else multicast_mode = PER_INTERFACE_MULTICAST;
196 		}
197 		else if (strcmp(*argv, "-i") == 0)
198 			insecure_mode = 1;
199 		else if (strcmp(*argv, "-l") == 0)
200 			quiet_mode = 1;
201 		else if (strcmp(*argv, "-p") == 0)
202 			iff_flag = 0;
203 		else
204 			usage();
205 		argv++, argc--;
206 	}
207 	if (argc > 0)
208 		usage();
209 #ifndef DEBUG
210 	daemon(1, 0);
211 #endif
212 	(void) signal(SIGHUP, getboottime);
213 	openlog("rwhod", LOG_PID, LOG_DAEMON);
214 	sp = getservbyname("who", "udp");
215 	if (sp == NULL) {
216 		syslog(LOG_ERR, "who/udp: unknown service");
217 		exit(1);
218 	}
219 	if (chdir(_PATH_RWHODIR) < 0) {
220 		syslog(LOG_ERR, "%s: %m", _PATH_RWHODIR);
221 		exit(1);
222 	}
223 	/*
224 	 * Establish host name as returned by system.
225 	 */
226 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
227 		syslog(LOG_ERR, "gethostname: %m");
228 		exit(1);
229 	}
230 	if ((cp = strchr(myname, '.')) != NULL)
231 		*cp = '\0';
232 	strncpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname) - 1);
233 	mywd.wd_hostname[sizeof(mywd.wd_hostname) - 1] = '\0';
234 	getboottime(0);
235 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
236 		syslog(LOG_ERR, "socket: %m");
237 		exit(1);
238 	}
239 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
240 		syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
241 		exit(1);
242 	}
243 	memset(&soin, 0, sizeof(soin));
244 	soin.sin_len = sizeof(soin);
245 	soin.sin_family = AF_INET;
246 	soin.sin_port = sp->s_port;
247 	if (bind(s, (struct sockaddr *)&soin, sizeof(soin)) < 0) {
248 		syslog(LOG_ERR, "bind: %m");
249 		exit(1);
250 	}
251 	if (setgid(unpriv_gid) != 0) {
252 		syslog(LOG_ERR, "setgid: %m");
253 		exit(1);
254 	}
255 	if (setgroups(1, &unpriv_gid) != 0) { /* XXX BOGUS groups[0] = egid */
256 		syslog(LOG_ERR, "setgroups: %m");
257 		exit(1);
258 	}
259 	if (setuid(unpriv_uid) != 0) {
260 		syslog(LOG_ERR, "setuid: %m");
261 		exit(1);
262 	}
263 	if (!configure(s))
264 		exit(1);
265 	if (!quiet_mode) {
266 		signal(SIGALRM, onalrm);
267 		onalrm(0);
268 	}
269 	for (;;) {
270 		struct whod wd;
271 		socklen_t len = sizeof(from);
272 		int cc, whod;
273 		time_t t;
274 
275 		cc = recvfrom(s, (char *)&wd, sizeof(struct whod), 0,
276 			(struct sockaddr *)&from, &len);
277 		if (cc <= 0) {
278 			if (cc < 0 && errno != EINTR)
279 				syslog(LOG_WARNING, "recv: %m");
280 			continue;
281 		}
282 		if (from.sin_port != sp->s_port && !insecure_mode) {
283 			syslog(LOG_WARNING, "%d: bad source port from %s",
284 			    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
285 			continue;
286 		}
287 		if (cc < WHDRSIZE) {
288 			syslog(LOG_WARNING, "short packet from %s",
289 			    inet_ntoa(from.sin_addr));
290 			continue;
291 		}
292 		if (wd.wd_vers != WHODVERSION)
293 			continue;
294 		if (wd.wd_type != WHODTYPE_STATUS)
295 			continue;
296 		if (!verify(wd.wd_hostname, sizeof wd.wd_hostname)) {
297 			syslog(LOG_WARNING, "malformed host name from %s",
298 			    inet_ntoa(from.sin_addr));
299 			continue;
300 		}
301 		(void) snprintf(path, sizeof path, "whod.%s", wd.wd_hostname);
302 		/*
303 		 * Rather than truncating and growing the file each time,
304 		 * use ftruncate if size is less than previous size.
305 		 */
306 		whod = open(path, O_WRONLY | O_CREAT, 0644);
307 		if (whod < 0) {
308 			syslog(LOG_WARNING, "%s: %m", path);
309 			continue;
310 		}
311 #if ENDIAN != BIG_ENDIAN
312 		{
313 			int i, n = (cc - WHDRSIZE)/sizeof(struct whoent);
314 			struct whoent *we;
315 
316 			/* undo header byte swapping before writing to file */
317 			wd.wd_sendtime = ntohl(wd.wd_sendtime);
318 			for (i = 0; i < 3; i++)
319 				wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
320 			wd.wd_boottime = ntohl(wd.wd_boottime);
321 			we = wd.wd_we;
322 			for (i = 0; i < n; i++) {
323 				we->we_idle = ntohl(we->we_idle);
324 				we->we_utmp.out_time =
325 				    ntohl(we->we_utmp.out_time);
326 				we++;
327 			}
328 		}
329 #endif
330 		(void) time(&t);
331 		wd.wd_recvtime = _time_to_int(t);
332 		(void) write(whod, (char *)&wd, cc);
333 		if (fstat(whod, &st) < 0 || st.st_size > cc)
334 			ftruncate(whod, cc);
335 		(void) close(whod);
336 	}
337 }
338 
339 static void
340 usage()
341 {
342 	fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
343 	exit(1);
344 }
345 
346 void
347 run_as(uid, gid)
348 	uid_t *uid;
349 	gid_t *gid;
350 {
351 	struct passwd *pw;
352 	struct group *gr;
353 
354 	pw = getpwnam(UNPRIV_USER);
355 	if (!pw) {
356 		syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
357 		exit(1);
358 	}
359 	*uid = pw->pw_uid;
360 
361 	gr = getgrnam(UNPRIV_GROUP);
362 	if (!gr) {
363 		syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
364 		exit(1);
365 	}
366 	*gid = gr->gr_gid;
367 }
368 
369 /*
370  * Check out host name for unprintables
371  * and other funnies before allowing a file
372  * to be created.  Sorry, but blanks aren't allowed.
373  */
374 int
375 verify(name, maxlen)
376 	register char *name;
377 	register int   maxlen;
378 {
379 	register int size = 0;
380 
381 	while (*name && size < maxlen - 1) {
382 		if (!isascii(*name) || !(isalnum(*name) || ispunct(*name)))
383 			return (0);
384 		name++, size++;
385 	}
386 	*name = '\0';
387 	return (size > 0);
388 }
389 
390 void
391 onalrm(int signo __unused)
392 {
393 	struct neighbor *np;
394 	struct whoent *we = mywd.wd_we, *wend;
395 	struct stat stb;
396 	struct utmpx *ut;
397 	static int alarmcount = 0;
398 	double avenrun[3];
399 	time_t now;
400 	int i, cc;
401 
402 	now = time(NULL);
403 	if (alarmcount % 10 == 0)
404 		getboottime(0);
405 	alarmcount++;
406 	wend = &mywd.wd_we[1024 / sizeof(struct whoent)];
407 	setutxent();
408 	while ((ut = getutxent()) != NULL && we < wend) {
409 		if (ut->ut_type != USER_PROCESS)
410 			continue;
411 		strncpy(we->we_utmp.out_line, ut->ut_line,
412 		   sizeof(we->we_utmp.out_line));
413 		strncpy(we->we_utmp.out_name, ut->ut_user,
414 		   sizeof(we->we_utmp.out_name));
415 		we->we_utmp.out_time =
416 		    htonl(_time_to_time32(ut->ut_tv.tv_sec));
417 		we++;
418 	}
419 	endutxent();
420 
421 	if (chdir(_PATH_DEV)) {
422 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
423 		exit(1);
424 	}
425 	wend = we;
426 	for (we = mywd.wd_we; we < wend; we++) {
427 		if (stat(we->we_utmp.out_line, &stb) >= 0)
428 			we->we_idle = htonl(now - stb.st_atime);
429 		we++;
430 	}
431 	(void)getloadavg(avenrun, sizeof(avenrun)/sizeof(avenrun[0]));
432 	for (i = 0; i < 3; i++)
433 		mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
434 	cc = (char *)wend - (char *)&mywd;
435 	mywd.wd_sendtime = htonl(_time_to_time32(time(NULL)));
436 	mywd.wd_vers = WHODVERSION;
437 	mywd.wd_type = WHODTYPE_STATUS;
438 	if (multicast_mode == SCOPED_MULTICAST) {
439 		(void) sendto(s, (char *)&mywd, cc, 0,
440 				(struct sockaddr *)&multicast_addr,
441 				sizeof(multicast_addr));
442 	}
443 	else for (np = neighbors; np != NULL; np = np->n_next) {
444 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
445 		    np->n_flags & IFF_MULTICAST) {
446 			/*
447 			 * Select the outgoing interface for the multicast.
448 			 */
449 			if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
450 			    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
451 			    sizeof(struct in_addr)) < 0) {
452 				syslog(LOG_ERR,
453 					"setsockopt IP_MULTICAST_IF: %m");
454 				exit(1);
455 			}
456 			(void) sendto(s, (char *)&mywd, cc, 0,
457 				(struct sockaddr *)&multicast_addr,
458 				sizeof(multicast_addr));
459 		} else (void) sendto(s, (char *)&mywd, cc, 0,
460 					np->n_addr, np->n_addrlen);
461 	}
462 	if (chdir(_PATH_RWHODIR)) {
463 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
464 		exit(1);
465 	}
466 	(void) alarm(AL_INTERVAL);
467 }
468 
469 void
470 getboottime(signo)
471 	int signo __unused;
472 {
473 	int mib[2];
474 	size_t size;
475 	struct timeval tm;
476 
477 	mib[0] = CTL_KERN;
478 	mib[1] = KERN_BOOTTIME;
479 	size = sizeof(tm);
480 	if (sysctl(mib, 2, &tm, &size, NULL, 0) == -1) {
481 		syslog(LOG_ERR, "cannot get boottime: %m");
482 		exit(1);
483 	}
484 	mywd.wd_boottime = htonl(_time_to_time32(tm.tv_sec));
485 }
486 
487 void
488 quit(msg)
489 	const char *msg;
490 {
491 	syslog(LOG_ERR, "%s", msg);
492 	exit(1);
493 }
494 
495 void
496 rt_xaddrs(cp, cplim, rtinfo)
497 	register caddr_t cp, cplim;
498 	register struct rt_addrinfo *rtinfo;
499 {
500 	register struct sockaddr *sa;
501 	register int i;
502 
503 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
504 	for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
505 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
506 			continue;
507 		rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
508 		cp += SA_SIZE(sa);
509 	}
510 }
511 
512 /*
513  * Figure out device configuration and select
514  * networks which deserve status information.
515  */
516 int
517 configure(so)
518 	int so;
519 {
520 	register struct neighbor *np;
521 	register struct if_msghdr *ifm;
522 	register struct ifa_msghdr *ifam;
523 	struct sockaddr_dl *sdl;
524 	size_t needed;
525 	int mib[6], flags = 0, len;
526 	char *buf, *lim, *next;
527 	struct rt_addrinfo info;
528 
529 	if (multicast_mode != NO_MULTICAST) {
530 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
531 		multicast_addr.sin_port = sp->s_port;
532 	}
533 
534 	if (multicast_mode == SCOPED_MULTICAST) {
535 		struct ip_mreq mreq;
536 		unsigned char ttl;
537 
538 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
539 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
540 		if (setsockopt(so, IPPROTO_IP, IP_ADD_MEMBERSHIP,
541 					&mreq, sizeof(mreq)) < 0) {
542 			syslog(LOG_ERR,
543 				"setsockopt IP_ADD_MEMBERSHIP: %m");
544 			return(0);
545 		}
546 		ttl = multicast_scope;
547 		if (setsockopt(so, IPPROTO_IP, IP_MULTICAST_TTL,
548 					&ttl, sizeof(ttl)) < 0) {
549 			syslog(LOG_ERR,
550 				"setsockopt IP_MULTICAST_TTL: %m");
551 			return(0);
552 		}
553 		return(1);
554 	}
555 
556 	mib[0] = CTL_NET;
557 	mib[1] = PF_ROUTE;
558 	mib[2] = 0;
559 	mib[3] = AF_INET;
560 	mib[4] = NET_RT_IFLIST;
561 	mib[5] = 0;
562 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
563 		quit("route-sysctl-estimate");
564 	if ((buf = malloc(needed)) == NULL)
565 		quit("malloc");
566 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
567 		quit("actual retrieval of interface table");
568 	lim = buf + needed;
569 
570 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
571 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
572 		ifm = (struct if_msghdr *)next;
573 		if (ifm->ifm_type == RTM_IFINFO) {
574 			sdl = (struct sockaddr_dl *)(ifm + 1);
575 			flags = ifm->ifm_flags;
576 			continue;
577 		}
578 		if ((flags & IFF_UP) == 0 ||
579 		    (flags & (((multicast_mode == PER_INTERFACE_MULTICAST) ?
580 				IFF_MULTICAST : 0) |
581 				IFF_BROADCAST|iff_flag)) == 0)
582 			continue;
583 		if (ifm->ifm_type != RTM_NEWADDR)
584 			quit("out of sync parsing NET_RT_IFLIST");
585 		ifam = (struct ifa_msghdr *)ifm;
586 		info.rti_addrs = ifam->ifam_addrs;
587 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
588 			&info);
589 		/* gag, wish we could get rid of Internet dependencies */
590 #define dstaddr	info.rti_info[RTAX_BRD]
591 #define ifaddr info.rti_info[RTAX_IFA]
592 #define IPADDR_SA(x) ((struct sockaddr_in *)(x))->sin_addr.s_addr
593 #define PORT_SA(x) ((struct sockaddr_in *)(x))->sin_port
594 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
595 			continue;
596 		PORT_SA(dstaddr) = sp->s_port;
597 		for (np = neighbors; np != NULL; np = np->n_next)
598 			if (memcmp(sdl->sdl_data, np->n_name,
599 				   sdl->sdl_nlen) == 0 &&
600 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr))
601 				break;
602 		if (np != NULL)
603 			continue;
604 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
605 		np = (struct neighbor *)malloc(len);
606 		if (np == NULL)
607 			quit("malloc of neighbor structure");
608 		memset(np, 0, len);
609 		np->n_flags = flags;
610 		np->n_addr = (struct sockaddr *)(np + 1);
611 		np->n_addrlen = dstaddr->sa_len;
612 		np->n_name = np->n_addrlen + (char *)np->n_addr;
613 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
614 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
615 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
616 		    (flags & IFF_MULTICAST) &&
617 		   !(flags & IFF_LOOPBACK)) {
618 			struct ip_mreq mreq;
619 
620 			memcpy((char *)np->n_addr, (char *)ifaddr,
621 				np->n_addrlen);
622 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
623 			mreq.imr_interface.s_addr =
624 			  ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
625 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
626 						&mreq, sizeof(mreq)) < 0) {
627 				syslog(LOG_ERR,
628 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
629 #if 0
630 				/* Fall back to broadcast on this if. */
631 				np->n_flags &= ~IFF_MULTICAST;
632 #else
633 				free((char *)np);
634 				continue;
635 #endif
636 			}
637 		}
638 		np->n_next = neighbors;
639 		neighbors = np;
640 	}
641 	free(buf);
642 	return (1);
643 }
644 
645 #ifdef DEBUG
646 void
647 Sendto(s, buf, cc, flags, to, tolen)
648 	int s;
649 	const void *buf;
650 	size_t cc;
651 	int flags;
652 	const struct sockaddr *to;
653 	int tolen;
654 {
655 	register struct whod *w = (struct whod *)buf;
656 	register struct whoent *we;
657 	struct sockaddr_in *sin = (struct sockaddr_in *)to;
658 
659 	printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
660 				 ntohs(sin->sin_port));
661 	printf("hostname %s %s\n", w->wd_hostname,
662 	   interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
663 	printf("load %4.2f, %4.2f, %4.2f\n",
664 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
665 	    ntohl(w->wd_loadav[2]) / 100.0);
666 	cc -= WHDRSIZE;
667 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
668 		time_t t = _time32_to_time(ntohl(we->we_utmp.out_time));
669 		printf("%-8.8s %s:%s %.12s",
670 			we->we_utmp.out_name,
671 			w->wd_hostname, we->we_utmp.out_line,
672 			ctime(&t)+4);
673 		we->we_idle = ntohl(we->we_idle) / 60;
674 		if (we->we_idle) {
675 			if (we->we_idle >= 100*60)
676 				we->we_idle = 100*60 - 1;
677 			if (we->we_idle >= 60)
678 				printf(" %2d", we->we_idle / 60);
679 			else
680 				printf("   ");
681 			printf(":%02d", we->we_idle % 60);
682 		}
683 		printf("\n");
684 	}
685 }
686 
687 char *
688 interval(time, updown)
689 	int time;
690 	char *updown;
691 {
692 	static char resbuf[32];
693 	int days, hours, minutes;
694 
695 	if (time < 0 || time > 3*30*24*60*60) {
696 		(void) sprintf(resbuf, "   %s ??:??", updown);
697 		return (resbuf);
698 	}
699 	minutes = (time + 59) / 60;		/* round to minutes */
700 	hours = minutes / 60; minutes %= 60;
701 	days = hours / 24; hours %= 24;
702 	if (days)
703 		(void) sprintf(resbuf, "%s %2d+%02d:%02d",
704 		    updown, days, hours, minutes);
705 	else
706 		(void) sprintf(resbuf, "%s    %2d:%02d",
707 		    updown, hours, minutes);
708 	return (resbuf);
709 }
710 #endif
711