xref: /dragonfly/usr.sbin/rwhod/rwhod.c (revision cfd1aba3)
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. 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  * @(#) Copyright (c) 1983, 1993 The Regents of the University of California.  All rights reserved.
30  * @(#)rwhod.c	8.1 (Berkeley) 6/6/93
31  * $FreeBSD: src/usr.sbin/rwhod/rwhod.c,v 1.13.2.2 2000/12/23 15:28:12 iedowse Exp $
32  * $DragonFly: src/usr.sbin/rwhod/rwhod.c,v 1.24 2007/12/27 15:29:40 matthias Exp $
33  */
34 
35 #include <sys/param.h>
36 #include <sys/socket.h>
37 #include <sys/stat.h>
38 #include <sys/signal.h>
39 #include <sys/ioctl.h>
40 #include <sys/sysctl.h>
41 
42 #include <net/if.h>
43 #include <net/if_dl.h>
44 #include <net/route.h>
45 #include <netinet/in.h>
46 #include <arpa/inet.h>
47 #include <protocols/rwhod.h>
48 
49 #include <ctype.h>
50 #include <err.h>
51 #include <errno.h>
52 #include <fcntl.h>
53 #include <libutil.h>
54 #include <netdb.h>
55 #include <paths.h>
56 #include <poll.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <syslog.h>
61 #include <unistd.h>
62 #include <utmp.h>
63 #include <pwd.h>
64 #include <grp.h>
65 
66 /*
67  * This version of Berkeley's rwhod has been modified to use IP multicast
68  * datagrams, under control of a new command-line option:
69  *
70  *	rwhod -m	causes rwhod to use IP multicast (instead of
71  *			broadcast or unicast) on all interfaces that have
72  *			the IFF_MULTICAST flag set in their "ifnet" structs
73  *			(excluding the loopback interface).  The multicast
74  *			reports are sent with a time-to-live of 1, to prevent
75  *			forwarding beyond the directly-connected subnet(s).
76  *
77  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
78  *			time-to-live of <ttl>, via a SINGLE interface rather
79  *			than all interfaces.  <ttl> must be between 0 and
80  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
81  *			is different than "-m", in that "-m 1" specifies
82  *			transmission on one interface only.
83  *
84  * When "-m" is used without a <ttl> argument, the program accepts multicast
85  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
86  * is given, it accepts multicast reports from only one interface, the one
87  * on which reports are sent (which may be controlled via the host's routing
88  * table).  Regardless of the "-m" option, the program accepts broadcast or
89  * unicast reports from all interfaces.  Thus, this program will hear the
90  * reports of old, non-multicasting rwhods, but, if multicasting is used,
91  * those old rwhods won't hear the reports generated by this program.
92  *
93  *                  -- Steve Deering, Stanford University, February 1989
94  */
95 
96 #define	UNPRIV_USER		"daemon"
97 #define	UNPRIV_GROUP		"daemon"
98 
99 #define WITH_ERRNO		1	/* Write to syslog with errno (%m) */
100 #define WITHOUT_ERRNO		0	/* Write to syslog without errno */
101 
102 #define NO_MULTICAST		0	  /* multicast modes */
103 #define PER_INTERFACE_MULTICAST	1
104 #define SCOPED_MULTICAST	2
105 
106 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
107 
108 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
109 					  /* (belongs in protocols/rwhod.h) */
110 
111 int			insecure_mode;
112 int			quiet_mode;
113 int			iff_flag = IFF_POINTOPOINT;
114 int			multicast_mode  = NO_MULTICAST;
115 int			multicast_scope;
116 struct sockaddr_in	multicast_addr;
117 
118 char	myname[MAXHOSTNAMELEN];
119 
120 /*
121  * We communicate with each neighbor in a list constructed at the time we're
122  * started up.  Neighbors are currently directly connected via a hardware
123  * interface.
124  */
125 struct	neighbor {
126 	struct	neighbor *n_next;
127 	char	*n_name;		/* interface name */
128 	struct	sockaddr *n_addr;		/* who to send to */
129 	int	n_addrlen;		/* size of address */
130 	int	n_flags;		/* should forward?, interface flags */
131 };
132 
133 struct	neighbor *neighbors;
134 struct	whod mywd;
135 struct	servent *sp;
136 int	s, utmpf;
137 volatile sig_atomic_t	onsighup;
138 
139 #define	WHDRSIZE	(sizeof(mywd) - sizeof(mywd.wd_we))
140 
141 void	 run_as(uid_t *, gid_t *);
142 int	 configure(int);
143 void	 getboottime(void);
144 void	 send_host_information(void);
145 void	 hup(int);
146 void	 quit(const char *, int);
147 void	 rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
148 int	 verify(char *, int);
149 void	 handleread(int);
150 static void usage(void);
151 void	 timeadd(struct timeval *, time_t, struct timeval *);
152 
153 #ifdef DEBUG
154 char	*interval(int, const char *);
155 ssize_t	Sendto(int, const void *, size_t, int,
156 		     const struct sockaddr *, int);
157 #else
158 #define Sendto sendto
159 #endif
160 
161 int
162 main(int argc, char *argv[])
163 {
164 	struct pollfd pfd[1];
165 	char *ep, *cp;
166 	int on = 1;
167 	int send_time = 180;	/* Default time, 180 seconds (3 minutes) */
168 	struct sockaddr_in m_sin;
169 	uid_t unpriv_uid;
170 	gid_t unpriv_gid;
171 	long tmp;
172 	time_t delta = 0;
173 	struct timeval next, now;
174 
175 	if (getuid())
176 		errx(1, "not super user");
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 && *(argv + 1)[0] != '-') {
184 				/* Argument has been given */
185 				argv++, argc--;
186 				multicast_mode = SCOPED_MULTICAST;
187 				tmp = strtol(*argv, &ep, 10);
188 				if (*ep != '\0' || tmp < INT_MIN || tmp > INT_MAX)
189 					errx(1, "invalid ttl: %s", *argv);
190 				multicast_scope = (int)tmp;
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 		} else if (strcmp(*argv, "-g") == 0) {
197 			if (argc > 1 && *(argv + 1)[0] != '-') {
198 				argv++, argc--;
199 				send_time = (int)strtol(*argv, &ep, 10);
200 				if (send_time <= 0)
201 					errx(1, "time must be greater than 0");
202 
203 				if (ep[0] != '\0') {
204 					if (ep[1] != '\0')
205 						errx(1, "invalid argument: %s", *argv);
206 					if (*ep == 'M' || *ep == 'm') {
207 						/* Time in minutes. */
208 						send_time *= 60;
209 					} else
210 						errx(1, "invalid argument: %s", *argv);
211 				}
212 
213 				if (send_time > 180)
214 					errx(1, "cannot be greater than 180 seconds (3 minutes)");
215 			} else
216 				errx(1, "missing argument");
217 		} else if (strcmp(*argv, "-i") == 0)
218 			insecure_mode = 1;
219 		else if (strcmp(*argv, "-l") == 0)
220 			quiet_mode = 1;
221 		else if (strcmp(*argv, "-p") == 0)
222 			iff_flag = 0;
223 		else
224 			usage();
225 		argv++, argc--;
226 	}
227 	if (argc > 0)
228 		usage();
229 #ifndef DEBUG
230         struct pidfh *pfh = NULL;
231         pfh = pidfile_open(NULL, 600, NULL);
232 	daemon(1, 0);
233         pidfile_write(pfh);
234 #endif
235 	signal(SIGHUP, hup);
236 	openlog("rwhod", LOG_PID, LOG_DAEMON);
237 	sp = getservbyname("who", "udp");
238 	if (sp == NULL)
239 		quit("udp/who: unknown service", WITHOUT_ERRNO);
240 
241 	if (chdir(_PATH_RWHODIR) < 0)
242 		quit(_PATH_RWHODIR, WITH_ERRNO);
243 
244 	/*
245 	 * Establish host name as returned by system.
246 	 */
247 	if (gethostname(myname, sizeof(myname)) < 0)
248 		quit("gethostname", WITH_ERRNO);
249 
250 	if ((cp = strchr(myname, '.')) != NULL)
251 		*cp = '\0';
252 	strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
253 	utmpf = open(_PATH_UTMP, O_RDONLY|O_CREAT, 0644);
254 	if (utmpf < 0)
255 		quit(_PATH_UTMP, WITH_ERRNO);
256 
257 	getboottime();
258 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
259 		quit("socket", WITH_ERRNO);
260 
261 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0)
262 		quit("setsockopt SO_BROADCAST", WITH_ERRNO);
263 
264 	memset(&m_sin, 0, sizeof(m_sin));
265 	m_sin.sin_len = sizeof(m_sin);
266 	m_sin.sin_family = AF_INET;
267 	m_sin.sin_port = sp->s_port;
268 	if (bind(s, (struct sockaddr *)&m_sin, sizeof(m_sin)) < 0)
269 		quit("bind", WITH_ERRNO);
270 
271 	setgid(unpriv_gid);
272 	setgroups(1, &unpriv_gid);	/* XXX BOGUS groups[0] = egid */
273 	setuid(unpriv_uid);
274 	if (!configure(s))
275 		exit(1);
276 
277 	if (!quiet_mode) {
278 		send_host_information();
279 		delta = send_time;
280 		gettimeofday(&now, NULL);
281 		timeadd(&now, delta, &next);
282 	}
283 
284 	pfd[0].fd = s;
285 	pfd[0].events = POLLIN;
286 
287 	for (;;) {
288 		int n;
289 
290 		n = poll(pfd, 1, 1000);
291 
292 		if (onsighup) {
293 			onsighup = 0;
294 			getboottime();
295 		}
296 
297 		if (n == 1)
298 			handleread(s);
299 		if (!quiet_mode) {
300 			gettimeofday(&now, NULL);
301 			if (now.tv_sec > next.tv_sec) {
302 				send_host_information();
303 				timeadd(&now, delta, &next);
304 			}
305 		}
306 	}
307 }
308 
309 void
310 timeadd(struct timeval *now, time_t delta, struct timeval *next)
311 {
312 	(next)->tv_sec = (now)->tv_sec + delta;
313 }
314 
315 void
316 handleread(int sock)
317 {
318 	struct sockaddr_in from;
319 	struct stat st;
320 	char path[64];
321 	struct whod wd;
322 	int cc, whod;
323 	socklen_t len = sizeof(from);
324 
325 	cc = recvfrom(sock, (char *)&wd, sizeof(struct whod), 0,
326 		(struct sockaddr *)&from, &len);
327 	if (cc == 0)
328 		return;
329 
330 	if (cc < 0 && errno != EINTR) {
331 		syslog(LOG_WARNING, "recv: %m");
332 		return;
333 	}
334 
335 	if (from.sin_port != sp->s_port && !insecure_mode) {
336 		syslog(LOG_WARNING, "%d: bad source port from %s",
337 		    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
338 		return;
339 	}
340 	if (cc < (int)WHDRSIZE) {
341 		syslog(LOG_WARNING, "short packet from %s",
342 		    inet_ntoa(from.sin_addr));
343 		return;
344 	}
345 	if (wd.wd_vers != WHODVERSION)
346 		return;
347 	if (wd.wd_type != WHODTYPE_STATUS)
348 		return;
349 	if (!verify(wd.wd_hostname, sizeof wd.wd_hostname)) {
350 		syslog(LOG_WARNING, "malformed host name from %s",
351 		    inet_ntoa(from.sin_addr));
352 		return;
353 	}
354 	snprintf(path, sizeof path, "whod.%s", wd.wd_hostname);
355 	/*
356 	 * Rather than truncating and growing the file each time,
357 	 * use ftruncate if size is less than previous size.
358 	 */
359 	whod = open(path, O_WRONLY | O_CREAT, 0644);
360 	if (whod < 0) {
361 		syslog(LOG_WARNING, "%s: %m", path);
362 		return;
363 	}
364 #if ENDIAN != BIG_ENDIAN
365 	{
366 		int i, n = (cc - WHDRSIZE)/sizeof(struct whoent);
367 		struct whoent *we;
368 
369 		/* undo header byte swapping before writing to file */
370 		wd.wd_sendtime = ntohl(wd.wd_sendtime);
371 		for (i = 0; i < 3; i++)
372 			wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
373 		wd.wd_boottime = ntohl(wd.wd_boottime);
374 		we = wd.wd_we;
375 		for (i = 0; i < n; i++) {
376 			we->we_idle = ntohl(we->we_idle);
377 			we->we_utmp.out_time =
378 			    ntohl(we->we_utmp.out_time);
379 			we++;
380 		}
381 	}
382 #endif
383 	wd.wd_recvtime = time(NULL);
384 	write(whod, (char *)&wd, cc);
385 	if (fstat(whod, &st) < 0 || st.st_size > cc)
386 		ftruncate(whod, cc);
387 	close(whod);
388 }
389 
390 static void
391 usage(void)
392 {
393 	fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
394 	exit(1);
395 }
396 
397 void
398 hup(int signo __unused)
399 {
400 	onsighup = 1;
401 }
402 
403 void
404 run_as(uid_t *uid, gid_t *gid)
405 {
406 	struct passwd *pw;
407 	struct group *gr;
408 
409 	pw = getpwnam(UNPRIV_USER);
410 	if (!pw)
411 		quit("getpwnam(daemon)", WITH_ERRNO);
412 
413 	*uid = pw->pw_uid;
414 
415 	gr = getgrnam(UNPRIV_GROUP);
416 	if (!gr)
417 		quit("getgrnam(daemon)", WITH_ERRNO);
418 
419 	*gid = gr->gr_gid;
420 }
421 
422 /*
423  * Check out host name for unprintables
424  * and other funnies before allowing a file
425  * to be created.  Sorry, but blanks aren't allowed.
426  */
427 int
428 verify(char *name, int maxlen)
429 {
430 	int size = 0;
431 
432 	while (*name && size < maxlen - 1) {
433 		if (!isascii(*name) || !(isalnum(*name) || ispunct(*name)))
434 			return (0);
435 		name++, size++;
436 	}
437 	*name = '\0';
438 	return (size > 0);
439 }
440 
441 int	utmptime;
442 int	utmpent;
443 int	utmpsize;
444 struct	utmp *utmp;
445 int	alarmcount;
446 
447 void
448 send_host_information(void)
449 {
450 	struct neighbor *np;
451 	struct whoent *we = mywd.wd_we, *wlast;
452 	int i;
453 	struct stat stb;
454 	double avenrun[3];
455 	time_t now;
456 	int cc;
457 
458 	now = time(NULL);
459 	if (alarmcount % 10 == 0)
460 		getboottime();
461 	alarmcount++;
462 	fstat(utmpf, &stb);
463 	if ((stb.st_mtime != utmptime) || (stb.st_size > utmpsize)) {
464 		utmptime = stb.st_mtime;
465 		if (stb.st_size > utmpsize) {
466 			utmpsize = stb.st_size + 10 * sizeof(struct utmp);
467 			utmp = reallocf(utmp, utmpsize);
468 			if (utmp == NULL) {
469 				syslog(LOG_WARNING, "malloc failed: %m");
470 				utmpsize = 0;
471 				return;
472 			}
473 		}
474 		lseek(utmpf, (off_t)0, L_SET);
475 		cc = read(utmpf, (char *)utmp, stb.st_size);
476 		if (cc < 0) {
477 			syslog(LOG_ERR, "read(%s): %m", _PATH_UTMP);
478 			return;
479 		}
480 		wlast = &mywd.wd_we[1024 / sizeof(struct whoent) - 1];
481 		utmpent = cc / sizeof(struct utmp);
482 		for (i = 0; i < utmpent; i++)
483 			if (utmp[i].ut_name[0]) {
484 				memcpy(we->we_utmp.out_line, utmp[i].ut_line,
485 				   sizeof(utmp[i].ut_line));
486 				memcpy(we->we_utmp.out_name, utmp[i].ut_name,
487 				   sizeof(utmp[i].ut_name));
488 				we->we_utmp.out_time = htonl(utmp[i].ut_time);
489 				if (we >= wlast)
490 					break;
491 				we++;
492 			}
493 		utmpent = we - mywd.wd_we;
494 	}
495 
496 	/*
497 	 * The test on utmpent looks silly---after all, if no one is
498 	 * logged on, why worry about efficiency?---but is useful on
499 	 * (e.g.) compute servers.
500 	 */
501 	if (utmpent && chdir(_PATH_DEV)) {
502 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
503 		exit(1);
504 	}
505 
506 	we = mywd.wd_we;
507 	for (i = 0; i < utmpent; i++) {
508 		if (stat(we->we_utmp.out_line, &stb) >= 0)
509 			we->we_idle = htonl(now - stb.st_atime);
510 		we++;
511 	}
512 	getloadavg(avenrun, sizeof(avenrun)/sizeof(avenrun[0]));
513 	for (i = 0; i < 3; i++)
514 		mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
515 	cc = (char *)we - (char *)&mywd;
516 	mywd.wd_sendtime = htonl(time(0));
517 	mywd.wd_vers = WHODVERSION;
518 	mywd.wd_type = WHODTYPE_STATUS;
519 	if (multicast_mode == SCOPED_MULTICAST) {
520 		Sendto(s, (char *)&mywd, cc, 0,
521 				(struct sockaddr *)&multicast_addr,
522 				sizeof(multicast_addr));
523 	}
524 	else for (np = neighbors; np != NULL; np = np->n_next) {
525 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
526 		    np->n_flags & IFF_MULTICAST) {
527 			/*
528 			 * Select the outgoing interface for the multicast.
529 			 */
530 			if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF,
531 			    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
532 			    sizeof(struct in_addr)) < 0) {
533 				quit("setsockopt IP_MULTICAST_IF", WITH_ERRNO);
534 			}
535 			Sendto(s, (char *)&mywd, cc, 0,
536 				(struct sockaddr *)&multicast_addr,
537 				sizeof(multicast_addr));
538 		} else Sendto(s, (char *)&mywd, cc, 0,
539 				np->n_addr, np->n_addrlen);
540 	}
541 	if (utmpent && chdir(_PATH_RWHODIR)) {
542 		syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
543 		exit(1);
544 	}
545 }
546 
547 void
548 getboottime(void)
549 {
550 	int mib[2];
551 	size_t size;
552 	struct timeval tm;
553 
554 	mib[0] = CTL_KERN;
555 	mib[1] = KERN_BOOTTIME;
556 	size = sizeof(tm);
557 	if (sysctl(mib, 2, &tm, &size, NULL, 0) == -1)
558 		quit("cannot get boottime", WITH_ERRNO);
559 
560 	mywd.wd_boottime = htonl(tm.tv_sec);
561 }
562 
563 /*
564  * If wrterrno == WITH_ERRNO, we will print
565  * errno. If not, we leave errno out.
566  */
567 void
568 quit(const char *msg, int wrterrno)
569 {
570 	if (wrterrno)
571 		syslog(LOG_ERR, "%s: %m", msg);
572 	else
573 		syslog(LOG_ERR, "%s", msg);
574 	exit(1);
575 }
576 
577 #define ROUNDUP(a) \
578 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
579 #define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
580 
581 void
582 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
583 {
584 	struct sockaddr *sa;
585 	int i;
586 
587 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
588 	for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
589 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
590 			continue;
591 		rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
592 		ADVANCE(cp, sa);
593 	}
594 }
595 
596 /*
597  * Figure out device configuration and select
598  * networks which deserve status information.
599  */
600 int
601 configure(int c_sock)
602 {
603 	struct neighbor *np;
604 	struct if_msghdr *ifm;
605 	struct ifa_msghdr *ifam;
606 	struct sockaddr_dl *sdl;
607 	size_t needed;
608 	int mib[6], flags = 0, len;
609 	char *buf, *lim, *next;
610 	struct rt_addrinfo info;
611 
612 	if (multicast_mode != NO_MULTICAST) {
613 		multicast_addr.sin_len = sizeof(multicast_addr);
614 		multicast_addr.sin_family = AF_INET;
615 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
616 		multicast_addr.sin_port = sp->s_port;
617 	}
618 
619 	if (multicast_mode == SCOPED_MULTICAST) {
620 		struct ip_mreq mreq;
621 		unsigned char ttl;
622 
623 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
624 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
625 		if (setsockopt(c_sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
626 					&mreq, sizeof(mreq)) < 0) {
627 			syslog(LOG_ERR,
628 				"setsockopt IP_ADD_MEMBERSHIP: %m");
629 			return(0);
630 		}
631 		ttl = multicast_scope;
632 		if (setsockopt(c_sock, IPPROTO_IP, IP_MULTICAST_TTL,
633 					&ttl, sizeof(ttl)) < 0) {
634 			syslog(LOG_ERR,
635 				"setsockopt IP_MULTICAST_TTL: %m");
636 			return(0);
637 		}
638 		return(1);
639 	}
640 
641 	mib[0] = CTL_NET;
642 	mib[1] = PF_ROUTE;
643 	mib[2] = 0;
644 	mib[3] = AF_INET;
645 	mib[4] = NET_RT_IFLIST;
646 	mib[5] = 0;
647 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
648 		quit("route-sysctl-estimate", WITH_ERRNO);
649 	if ((buf = malloc(needed)) == NULL)
650 		quit("malloc", WITH_ERRNO);
651 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
652 		quit("actual retrieval of interface table", WITH_ERRNO);
653 	lim = buf + needed;
654 
655 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
656 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
657 		ifm = (struct if_msghdr *)next;
658 		if (ifm->ifm_type == RTM_IFINFO) {
659 			sdl = (struct sockaddr_dl *)(ifm + 1);
660 			flags = ifm->ifm_flags;
661 			continue;
662 		}
663 		if ((flags & IFF_UP) == 0 ||
664 		    (flags & (((multicast_mode == PER_INTERFACE_MULTICAST) ?
665 				IFF_MULTICAST : 0) |
666 				IFF_BROADCAST|iff_flag)) == 0)
667 			continue;
668 		if (ifm->ifm_type != RTM_NEWADDR)
669 			quit("out of sync parsing NET_RT_IFLIST", WITHOUT_ERRNO);
670 		ifam = (struct ifa_msghdr *)ifm;
671 		info.rti_addrs = ifam->ifam_addrs;
672 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
673 			&info);
674 		/* gag, wish we could get rid of Internet dependencies */
675 #define dstaddr	info.rti_info[RTAX_BRD]
676 #define ifaddr info.rti_info[RTAX_IFA]
677 #define IPADDR_SA(x) ((struct sockaddr_in *)(x))->sin_addr.s_addr
678 #define PORT_SA(x) ((struct sockaddr_in *)(x))->sin_port
679 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
680 			continue;
681 		PORT_SA(dstaddr) = sp->s_port;
682 		for (np = neighbors; np != NULL; np = np->n_next)
683 			if (memcmp(sdl->sdl_data, np->n_name,
684 				   sdl->sdl_nlen) == 0 &&
685 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr))
686 				break;
687 		if (np != NULL)
688 			continue;
689 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
690 		np = (struct neighbor *)malloc(len);
691 		if (np == NULL)
692 			quit("malloc of neighbor structure", WITH_ERRNO);
693 		memset(np, 0, len);
694 		np->n_flags = flags;
695 		np->n_addr = (struct sockaddr *)(np + 1);
696 		np->n_addrlen = dstaddr->sa_len;
697 		np->n_name = np->n_addrlen + (char *)np->n_addr;
698 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
699 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
700 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
701 		    (flags & IFF_MULTICAST) &&
702 		   !(flags & IFF_LOOPBACK)) {
703 			struct ip_mreq mreq;
704 
705 			memcpy((char *)np->n_addr, (char *)ifaddr,
706 				np->n_addrlen);
707 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
708 			mreq.imr_interface.s_addr =
709 			  ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
710 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
711 						&mreq, sizeof(mreq)) < 0) {
712 				syslog(LOG_ERR,
713 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
714 #if 0
715 				/* Fall back to broadcast on this if. */
716 				np->n_flags &= ~IFF_MULTICAST;
717 #else
718 				free((char *)np);
719 				continue;
720 #endif
721 			}
722 		}
723 		np->n_next = neighbors;
724 		neighbors = np;
725 	}
726 	free(buf);
727 	return (1);
728 }
729 
730 #ifdef DEBUG
731 ssize_t
732 Sendto(int s_debug, const void *buf, size_t cc, int flags,
733        const struct sockaddr *to, int tolen)
734 {
735 	const struct whod *w = (const struct whod *)buf;
736 	const struct whoent *we;
737 	const struct sockaddr_in *sock_in = (const struct sockaddr_in *)to;
738 	ssize_t ret;
739 	int idle_time;
740 
741 	ret = sendto(s_debug, buf, cc, flags, to, tolen);
742 
743 	printf("sendto %s:%d\n", inet_ntoa(sock_in->sin_addr),
744 				 ntohs(sock_in->sin_port));
745 	printf("hostname %s %s\n", w->wd_hostname,
746 	   interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
747 	printf("load %4.2f, %4.2f, %4.2f\n",
748 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
749 	    ntohl(w->wd_loadav[2]) / 100.0);
750 	cc -= WHDRSIZE;
751 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
752 		time_t t = ntohl(we->we_utmp.out_time);
753 		idle_time = we->we_idle;
754 		printf("%-8.8s %s:%s %.12s",
755 			we->we_utmp.out_name,
756 			w->wd_hostname, we->we_utmp.out_line,
757 			ctime(&t)+4);
758 		idle_time = ntohl(we->we_idle) / 60;
759 		if (idle_time) {
760 			if (idle_time >= 100*60)
761 				idle_time = 100*60 - 1;
762 			if (idle_time >= 60)
763 				printf(" %2d", idle_time / 60);
764 			else
765 				printf("   ");
766 			printf(":%02d", idle_time % 60);
767 		}
768 		printf("\n");
769 	}
770 	return(ret);
771 }
772 
773 char *
774 interval(int inter_time, const char *updown)
775 {
776 	static char resbuf[32];
777 	int days, hours, minutes;
778 
779 	if (inter_time < 0 || inter_time > 3*30*24*60*60) {
780 		snprintf(resbuf, sizeof(resbuf), "   %s ??:??", updown);
781 		return (resbuf);
782 	}
783 	minutes = (inter_time + 59) / 60;		/* round to minutes */
784 	hours = minutes / 60; minutes %= 60;
785 	days = hours / 24; hours %= 24;
786 	if (days)
787 		snprintf(resbuf, sizeof(resbuf), "%s %2d+%02d:%02d",
788 		    updown, days, hours, minutes);
789 	else
790 		snprintf(resbuf, sizeof(resbuf), "%s    %2d:%02d",
791 		    updown, hours, minutes);
792 	return (resbuf);
793 }
794 #endif
795