xref: /freebsd/usr.sbin/rwhod/rwhod.c (revision e627b39baccd1ec9129690167cf5e6d860509655)
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  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 static char copyright[] =
36 "@(#) Copyright (c) 1983, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 static char sccsid[] = "@(#)rwhod.c	8.1 (Berkeley) 6/6/93";
42 #endif /* not lint */
43 
44 #include <sys/param.h>
45 #include <sys/socket.h>
46 #include <sys/stat.h>
47 #include <sys/signal.h>
48 #include <sys/ioctl.h>
49 #include <sys/sysctl.h>
50 
51 #include <net/if.h>
52 #include <net/if_dl.h>
53 #include <net/route.h>
54 #include <netinet/in.h>
55 #include <protocols/rwhod.h>
56 
57 #include <ctype.h>
58 #include <errno.h>
59 #include <fcntl.h>
60 #include <netdb.h>
61 #include <paths.h>
62 #include <stdio.h>
63 #include <stdlib.h>
64 #include <string.h>
65 #include <syslog.h>
66 #include <unistd.h>
67 #include <utmp.h>
68 #include <pwd.h>
69 #include <grp.h>
70 
71 /*
72  * This version of Berkeley's rwhod has been modified to use IP multicast
73  * datagrams, under control of a new command-line option:
74  *
75  *	rwhod -m	causes rwhod to use IP multicast (instead of
76  *			broadcast or unicast) on all interfaces that have
77  *			the IFF_MULTICAST flag set in their "ifnet" structs
78  *			(excluding the loopback interface).  The multicast
79  *			reports are sent with a time-to-live of 1, to prevent
80  *			forwarding beyond the directly-connected subnet(s).
81  *
82  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
83  *			time-to-live of <ttl>, via a SINGLE interface rather
84  *			than all interfaces.  <ttl> must be between 0 and
85  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
86  *			is different than "-m", in that "-m 1" specifies
87  *			transmission on one interface only.
88  *
89  * When "-m" is used without a <ttl> argument, the program accepts multicast
90  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
91  * is given, it accepts multicast reports from only one interface, the one
92  * on which reports are sent (which may be controlled via the host's routing
93  * table).  Regardless of the "-m" option, the program accepts broadcast or
94  * unicast reports from all interfaces.  Thus, this program will hear the
95  * reports of old, non-multicasting rwhods, but, if multicasting is used,
96  * those old rwhods won't hear the reports generated by this program.
97  *
98  *                  -- Steve Deering, Stanford University, February 1989
99  */
100 
101 #define	UNPRIV_USER		"daemon"
102 #define	UNPRIV_GROUP		"daemon"
103 
104 #define NO_MULTICAST		0	  /* multicast modes */
105 #define PER_INTERFACE_MULTICAST	1
106 #define SCOPED_MULTICAST	2
107 
108 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
109 
110 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
111 					  /* (belongs in protocols/rwhod.h) */
112 
113 int			multicast_mode  = NO_MULTICAST;
114 int			multicast_scope;
115 struct sockaddr_in	multicast_addr  = { sizeof multicast_addr, AF_INET };
116 
117 /*
118  * Alarm interval. Don't forget to change the down time check in ruptime
119  * if this is changed.
120  */
121 #define AL_INTERVAL (3 * 60)
122 
123 char	myname[MAXHOSTNAMELEN];
124 
125 /*
126  * We communicate with each neighbor in a list constructed at the time we're
127  * started up.  Neighbors are currently directly connected via a hardware
128  * interface.
129  */
130 struct	neighbor {
131 	struct	neighbor *n_next;
132 	char	*n_name;		/* interface name */
133 	struct	sockaddr *n_addr;		/* who to send to */
134 	int	n_addrlen;		/* size of address */
135 	int	n_flags;		/* should forward?, interface flags */
136 };
137 
138 struct	neighbor *neighbors;
139 struct	whod mywd;
140 struct	servent *sp;
141 int	s, utmpf;
142 
143 #define	WHDRSIZE	(sizeof(mywd) - sizeof(mywd.wd_we))
144 
145 void	 run_as __P((uid_t *, gid_t *));
146 int	 configure __P((int));
147 void	 getboottime __P((int));
148 void	 onalrm __P((int));
149 void	 quit __P((char *));
150 void	 rt_xaddrs __P((caddr_t, caddr_t, struct rt_addrinfo *));
151 int	 verify __P((char *, int));
152 #ifdef DEBUG
153 char	*interval __P((int, char *));
154 void	 Sendto __P((int, const void *, size_t, int,
155 		     const struct sockaddr *, int));
156 #define	 sendto Sendto
157 #endif
158 
159 int
160 main(argc, argv)
161 	int argc;
162 	char *argv[];
163 {
164 	struct sockaddr_in from;
165 	struct stat st;
166 	char path[64];
167 	int on = 1;
168 	char *cp;
169 	struct sockaddr_in sin;
170 	uid_t unpriv_uid;
171 	gid_t unpriv_gid;
172 
173 	if (getuid()) {
174 		fprintf(stderr, "rwhod: not super user\n");
175 		exit(1);
176 	}
177 
178 	run_as(&unpriv_uid, &unpriv_gid);
179 
180 	argv++; argc--;
181 	while (argc > 0 && *argv[0] == '-') {
182 		if (strcmp(*argv, "-m") == 0) {
183 			if (argc > 1 && isdigit(*(argv + 1)[0])) {
184 				argv++, argc--;
185 				multicast_mode  = SCOPED_MULTICAST;
186 				multicast_scope = atoi(*argv);
187 				if (multicast_scope > MAX_MULTICAST_SCOPE) {
188 					fprintf(stderr,
189 					"rwhod: ttl must not exceed %u\n",
190 					MAX_MULTICAST_SCOPE);
191 					exit(1);
192 				}
193 			}
194 			else multicast_mode = PER_INTERFACE_MULTICAST;
195 		}
196 		else goto usage;
197 		argv++, argc--;
198 	}
199 	if (argc > 0) {
200 usage:		fprintf(stderr, "usage: rwhod [ -m [ ttl ] ]\n");
201 		exit(1);
202 	}
203 #ifndef DEBUG
204 	daemon(1, 0);
205 #endif
206 	(void) signal(SIGHUP, getboottime);
207 	openlog("rwhod", LOG_PID, LOG_DAEMON);
208 	sp = getservbyname("who", "udp");
209 	if (sp == NULL) {
210 		syslog(LOG_ERR, "rwhod: udp/who: unknown service\n");
211 		exit(1);
212 	}
213 	if (chdir(_PATH_RWHODIR) < 0) {
214 		syslog(LOG_ERR, "rwhod: %s: %m\n", _PATH_RWHODIR);
215 		exit(1);
216 	}
217 	/*
218 	 * Establish host name as returned by system.
219 	 */
220 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
221 		syslog(LOG_ERR, "gethostname: %m");
222 		exit(1);
223 	}
224 	if ((cp = index(myname, '.')) != NULL)
225 		*cp = '\0';
226 	strncpy(mywd.wd_hostname, myname, sizeof(myname) - 1);
227 	utmpf = open(_PATH_UTMP, O_RDONLY|O_CREAT, 0644);
228 	if (utmpf < 0) {
229 		syslog(LOG_ERR, "%s: %m", _PATH_UTMP);
230 		exit(1);
231 	}
232 	getboottime(0);
233 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
234 		syslog(LOG_ERR, "socket: %m");
235 		exit(1);
236 	}
237 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
238 		syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
239 		exit(1);
240 	}
241 	memset(&sin, 0, sizeof(sin));
242 	sin.sin_len = sizeof(sin);
243 	sin.sin_family = AF_INET;
244 	sin.sin_port = sp->s_port;
245 	if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
246 		syslog(LOG_ERR, "bind: %m");
247 		exit(1);
248 	}
249 	setgid(unpriv_gid);
250 	setgroups(1, &unpriv_gid);	/* XXX BOGUS groups[0] = egid */
251 	setuid(unpriv_uid);
252 	if (!configure(s))
253 		exit(1);
254 	signal(SIGALRM, onalrm);
255 	onalrm(0);
256 	for (;;) {
257 		struct whod wd;
258 		int cc, whod, len = sizeof(from);
259 
260 		cc = recvfrom(s, (char *)&wd, sizeof(struct whod), 0,
261 			(struct sockaddr *)&from, &len);
262 		if (cc <= 0) {
263 			if (cc < 0 && errno != EINTR)
264 				syslog(LOG_WARNING, "recv: %m");
265 			continue;
266 		}
267 		if (from.sin_port != sp->s_port) {
268 			syslog(LOG_WARNING, "%d: bad from port",
269 				ntohs(from.sin_port));
270 			continue;
271 		}
272 		if (wd.wd_vers != WHODVERSION)
273 			continue;
274 		if (wd.wd_type != WHODTYPE_STATUS)
275 			continue;
276 		if (!verify(wd.wd_hostname, sizeof wd.wd_hostname)) {
277 			syslog(LOG_WARNING, "malformed host name from %x",
278 				from.sin_addr);
279 			continue;
280 		}
281 		(void) sprintf(path, "whod.%s", wd.wd_hostname);
282 		/*
283 		 * Rather than truncating and growing the file each time,
284 		 * use ftruncate if size is less than previous size.
285 		 */
286 		whod = open(path, O_WRONLY | O_CREAT, 0644);
287 		if (whod < 0) {
288 			syslog(LOG_WARNING, "%s: %m", path);
289 			continue;
290 		}
291 #if ENDIAN != BIG_ENDIAN
292 		{
293 			int i, n = (cc - WHDRSIZE)/sizeof(struct whoent);
294 			struct whoent *we;
295 
296 			/* undo header byte swapping before writing to file */
297 			wd.wd_sendtime = ntohl(wd.wd_sendtime);
298 			for (i = 0; i < 3; i++)
299 				wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
300 			wd.wd_boottime = ntohl(wd.wd_boottime);
301 			we = wd.wd_we;
302 			for (i = 0; i < n; i++) {
303 				we->we_idle = ntohl(we->we_idle);
304 				we->we_utmp.out_time =
305 				    ntohl(we->we_utmp.out_time);
306 				we++;
307 			}
308 		}
309 #endif
310 		(void) time((time_t *)&wd.wd_recvtime);
311 		(void) write(whod, (char *)&wd, cc);
312 		if (fstat(whod, &st) < 0 || st.st_size > cc)
313 			ftruncate(whod, cc);
314 		(void) close(whod);
315 	}
316 }
317 
318 
319 void
320 run_as(uid, gid)
321 	uid_t *uid;
322 	gid_t *gid;
323 {
324 	struct passwd *pw;
325 	struct group *gr;
326 
327 	pw = getpwnam(UNPRIV_USER);
328 	if (!pw) {
329 		syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
330 		exit(1);
331 	}
332 	*uid = pw->pw_uid;
333 
334 	gr = getgrnam(UNPRIV_GROUP);
335 	if (!gr) {
336 		syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
337 		exit(1);
338 	}
339 	*gid = gr->gr_gid;
340 }
341 
342 /*
343  * Check out host name for unprintables
344  * and other funnies before allowing a file
345  * to be created.  Sorry, but blanks aren't allowed.
346  */
347 int
348 verify(name, maxlen)
349 	register char *name;
350 	register int   maxlen;
351 {
352 	register int size = 0;
353 
354 	while (*name && size < maxlen) {
355 		if (!isascii(*name) || !(isalnum(*name) || ispunct(*name)))
356 			return (0);
357 		name++, size++;
358 	}
359 	*name = '\0';
360 	return (size > 0);
361 }
362 
363 int	utmptime;
364 int	utmpent;
365 int	utmpsize = 0;
366 struct	utmp *utmp;
367 int	alarmcount;
368 
369 void
370 onalrm(signo)
371 	int signo;
372 {
373 	register struct neighbor *np;
374 	register struct whoent *we = mywd.wd_we, *wlast;
375 	register int i;
376 	struct stat stb;
377 	double avenrun[3];
378 	time_t now;
379 	int cc;
380 
381 	now = time(NULL);
382 	if (alarmcount % 10 == 0)
383 		getboottime(0);
384 	alarmcount++;
385 	(void) fstat(utmpf, &stb);
386 	if ((stb.st_mtime != utmptime) || (stb.st_size > utmpsize)) {
387 		utmptime = stb.st_mtime;
388 		if (stb.st_size > utmpsize) {
389 			utmpsize = stb.st_size + 10 * sizeof(struct utmp);
390 			if (utmp)
391 				utmp = (struct utmp *)realloc(utmp, utmpsize);
392 			else
393 				utmp = (struct utmp *)malloc(utmpsize);
394 			if (! utmp) {
395 				fprintf(stderr, "rwhod: malloc failed\n");
396 				utmpsize = 0;
397 				goto done;
398 			}
399 		}
400 		(void) lseek(utmpf, (off_t)0, L_SET);
401 		cc = read(utmpf, (char *)utmp, stb.st_size);
402 		if (cc < 0) {
403 			fprintf(stderr, "rwhod: %s: %s\n",
404 			    _PATH_UTMP, strerror(errno));
405 			goto done;
406 		}
407 		wlast = &mywd.wd_we[1024 / sizeof(struct whoent) - 1];
408 		utmpent = cc / sizeof(struct utmp);
409 		for (i = 0; i < utmpent; i++)
410 			if (utmp[i].ut_name[0]) {
411 				memcpy(we->we_utmp.out_line, utmp[i].ut_line,
412 				   sizeof(utmp[i].ut_line));
413 				memcpy(we->we_utmp.out_name, utmp[i].ut_name,
414 				   sizeof(utmp[i].ut_name));
415 				we->we_utmp.out_time = htonl(utmp[i].ut_time);
416 				if (we >= wlast)
417 					break;
418 				we++;
419 			}
420 		utmpent = we - mywd.wd_we;
421 	}
422 
423 	/*
424 	 * The test on utmpent looks silly---after all, if no one is
425 	 * logged on, why worry about efficiency?---but is useful on
426 	 * (e.g.) compute servers.
427 	 */
428 	if (utmpent && chdir(_PATH_DEV)) {
429 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
430 		exit(1);
431 	}
432 	we = mywd.wd_we;
433 	for (i = 0; i < utmpent; i++) {
434 		if (stat(we->we_utmp.out_line, &stb) >= 0)
435 			we->we_idle = htonl(now - stb.st_atime);
436 		we++;
437 	}
438 	(void)getloadavg(avenrun, sizeof(avenrun)/sizeof(avenrun[0]));
439 	for (i = 0; i < 3; i++)
440 		mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
441 	cc = (char *)we - (char *)&mywd;
442 	mywd.wd_sendtime = htonl(time(0));
443 	mywd.wd_vers = WHODVERSION;
444 	mywd.wd_type = WHODTYPE_STATUS;
445 	if (multicast_mode == SCOPED_MULTICAST) {
446 		(void) sendto(s, (char *)&mywd, cc, 0,
447 				(struct sockaddr *)&multicast_addr,
448 				sizeof(multicast_addr));
449 	}
450 	else for (np = neighbors; np != NULL; np = np->n_next) {
451 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
452 		    np->n_flags & IFF_MULTICAST) {
453 			/*
454 			 * Select the outgoing interface for the multicast.
455 			 */
456 			if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
457 			    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
458 			    sizeof(struct in_addr)) < 0) {
459 				syslog(LOG_ERR,
460 					"setsockopt IP_MULTICAST_IF: %m");
461 				exit(1);
462 			}
463 			(void) sendto(s, (char *)&mywd, cc, 0,
464 				(struct sockaddr *)&multicast_addr,
465 				sizeof(multicast_addr));
466 		} else (void) sendto(s, (char *)&mywd, cc, 0,
467 					np->n_addr, np->n_addrlen);
468 	}
469 	if (utmpent && chdir(_PATH_RWHODIR)) {
470 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
471 		exit(1);
472 	}
473 done:
474 	(void) alarm(AL_INTERVAL);
475 }
476 
477 void
478 getboottime(signo)
479 	int signo;
480 {
481 	int mib[2];
482 	size_t size;
483 	struct timeval tm;
484 
485 	mib[0] = CTL_KERN;
486 	mib[1] = KERN_BOOTTIME;
487 	size = sizeof(tm);
488 	if (sysctl(mib, 2, &tm, &size, NULL, 0) == -1) {
489 		syslog(LOG_ERR, "cannot get boottime: %m");
490 		exit(1);
491 	}
492 	mywd.wd_boottime = htonl(tm.tv_sec);
493 }
494 
495 void
496 quit(msg)
497 	char *msg;
498 {
499 	syslog(LOG_ERR, msg);
500 	exit(1);
501 }
502 
503 #define ROUNDUP(a) \
504 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
505 #define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
506 
507 void
508 rt_xaddrs(cp, cplim, rtinfo)
509 	register caddr_t cp, cplim;
510 	register struct rt_addrinfo *rtinfo;
511 {
512 	register struct sockaddr *sa;
513 	register int i;
514 
515 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
516 	for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
517 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
518 			continue;
519 		rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
520 		ADVANCE(cp, sa);
521 	}
522 }
523 
524 /*
525  * Figure out device configuration and select
526  * networks which deserve status information.
527  */
528 int
529 configure(s)
530 	int s;
531 {
532 	register struct neighbor *np;
533 	register struct if_msghdr *ifm;
534 	register struct ifa_msghdr *ifam;
535 	struct sockaddr_dl *sdl;
536 	size_t needed;
537 	int mib[6], flags = 0, len;
538 	char *buf, *lim, *next;
539 	struct rt_addrinfo info;
540 
541 	if (multicast_mode != NO_MULTICAST) {
542 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
543 		multicast_addr.sin_port = sp->s_port;
544 	}
545 
546 	if (multicast_mode == SCOPED_MULTICAST) {
547 		struct ip_mreq mreq;
548 		unsigned char ttl;
549 
550 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
551 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
552 		if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
553 					&mreq, sizeof(mreq)) < 0) {
554 			syslog(LOG_ERR,
555 				"setsockopt IP_ADD_MEMBERSHIP: %m");
556 			return(0);
557 		}
558 		ttl = multicast_scope;
559 		if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL,
560 					&ttl, sizeof(ttl)) < 0) {
561 			syslog(LOG_ERR,
562 				"setsockopt IP_MULTICAST_TTL: %m");
563 			return(0);
564 		}
565 		return(1);
566 	}
567 
568 	mib[0] = CTL_NET;
569 	mib[1] = PF_ROUTE;
570 	mib[2] = 0;
571 	mib[3] = AF_INET;
572 	mib[4] = NET_RT_IFLIST;
573 	mib[5] = 0;
574 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
575 		quit("route-sysctl-estimate");
576 	if ((buf = malloc(needed)) == NULL)
577 		quit("malloc");
578 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
579 		quit("actual retrieval of interface table");
580 	lim = buf + needed;
581 
582 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
583 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
584 		ifm = (struct if_msghdr *)next;
585 		if (ifm->ifm_type == RTM_IFINFO) {
586 			sdl = (struct sockaddr_dl *)(ifm + 1);
587 			flags = ifm->ifm_flags;
588 			continue;
589 		}
590 		if ((flags & IFF_UP) == 0 ||
591 		    (flags & (((multicast_mode == PER_INTERFACE_MULTICAST) ?
592 				IFF_MULTICAST : 0) |
593 				IFF_BROADCAST|IFF_POINTOPOINT)) == 0)
594 			continue;
595 		if (ifm->ifm_type != RTM_NEWADDR)
596 			quit("out of sync parsing NET_RT_IFLIST");
597 		ifam = (struct ifa_msghdr *)ifm;
598 		info.rti_addrs = ifam->ifam_addrs;
599 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
600 			&info);
601 		/* gag, wish we could get rid of Internet dependencies */
602 #define dstaddr	info.rti_info[RTAX_BRD]
603 #define ifaddr info.rti_info[RTAX_IFA]
604 #define IPADDR_SA(x) ((struct sockaddr_in *)(x))->sin_addr.s_addr
605 #define PORT_SA(x) ((struct sockaddr_in *)(x))->sin_port
606 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
607 			continue;
608 		PORT_SA(dstaddr) = sp->s_port;
609 		for (np = neighbors; np != NULL; np = np->n_next)
610 			if (memcmp(sdl->sdl_data, np->n_name,
611 				   sdl->sdl_nlen) == 0 &&
612 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr))
613 				break;
614 		if (np != NULL)
615 			continue;
616 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
617 		np = (struct neighbor *)malloc(len);
618 		if (np == NULL)
619 			quit("malloc of neighbor structure");
620 		memset(np, 0, len);
621 		np->n_flags = flags;
622 		np->n_addr = (struct sockaddr *)(np + 1);
623 		np->n_addrlen = dstaddr->sa_len;
624 		np->n_name = np->n_addrlen + (char *)np->n_addr;
625 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
626 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
627 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
628 		    (flags & IFF_MULTICAST) &&
629 		   !(flags & IFF_LOOPBACK)) {
630 			struct ip_mreq mreq;
631 
632 			memcpy((char *)np->n_addr, (char *)ifaddr,
633 				np->n_addrlen);
634 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
635 			mreq.imr_interface.s_addr =
636 			  ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
637 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
638 						&mreq, sizeof(mreq)) < 0) {
639 				syslog(LOG_ERR,
640 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
641 #if 0
642 				/* Fall back to broadcast on this if. */
643 				np->n_flags &= ~IFF_MULTICAST;
644 #else
645 				free((char *)np);
646 				continue;
647 #endif
648 			}
649 		}
650 		np->n_next = neighbors;
651 		neighbors = np;
652 	}
653 	free(buf);
654 	return (1);
655 }
656 
657 #ifdef DEBUG
658 void
659 Sendto(s, buf, cc, flags, to, tolen)
660 	int s;
661 	const void *buf;
662 	size_t cc;
663 	int flags;
664 	const struct sockaddr *to;
665 	int tolen;
666 {
667 	register struct whod *w = (struct whod *)buf;
668 	register struct whoent *we;
669 	struct sockaddr_in *sin = (struct sockaddr_in *)to;
670 
671 	printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
672 				 ntohs(sin->sin_port));
673 	printf("hostname %s %s\n", w->wd_hostname,
674 	   interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
675 	printf("load %4.2f, %4.2f, %4.2f\n",
676 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
677 	    ntohl(w->wd_loadav[2]) / 100.0);
678 	cc -= WHDRSIZE;
679 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
680 		time_t t = ntohl(we->we_utmp.out_time);
681 		printf("%-8.8s %s:%s %.12s",
682 			we->we_utmp.out_name,
683 			w->wd_hostname, we->we_utmp.out_line,
684 			ctime(&t)+4);
685 		we->we_idle = ntohl(we->we_idle) / 60;
686 		if (we->we_idle) {
687 			if (we->we_idle >= 100*60)
688 				we->we_idle = 100*60 - 1;
689 			if (we->we_idle >= 60)
690 				printf(" %2d", we->we_idle / 60);
691 			else
692 				printf("   ");
693 			printf(":%02d", we->we_idle % 60);
694 		}
695 		printf("\n");
696 	}
697 }
698 
699 char *
700 interval(time, updown)
701 	int time;
702 	char *updown;
703 {
704 	static char resbuf[32];
705 	int days, hours, minutes;
706 
707 	if (time < 0 || time > 3*30*24*60*60) {
708 		(void) sprintf(resbuf, "   %s ??:??", updown);
709 		return (resbuf);
710 	}
711 	minutes = (time + 59) / 60;		/* round to minutes */
712 	hours = minutes / 60; minutes %= 60;
713 	days = hours / 24; hours %= 24;
714 	if (days)
715 		(void) sprintf(resbuf, "%s %2d+%02d:%02d",
716 		    updown, days, hours, minutes);
717 	else
718 		(void) sprintf(resbuf, "%s    %2d:%02d",
719 		    updown, hours, minutes);
720 	return (resbuf);
721 }
722 #endif
723