xref: /freebsd/usr.sbin/rwhod/rwhod.c (revision ca57a343e86ed3015596db68bda17518ad45436a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1983, 1993 The Regents of the University of California.
5  * Copyright (c) 2013 Mariusz Zaborski <oshogbo@FreeBSD.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 static const char copyright[] =
35 "@(#) Copyright (c) 1983, 1993\n\
36 	The Regents of the University of California.  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #if 0
40 #ifndef lint
41 static char sccsid[] = "@(#)rwhod.c	8.1 (Berkeley) 6/6/93";
42 #endif /* not lint */
43 #endif
44 
45 #include <sys/cdefs.h>
46 #include <sys/param.h>
47 #include <sys/capsicum.h>
48 #include <sys/ioctl.h>
49 #include <sys/procdesc.h>
50 #include <sys/socket.h>
51 #include <sys/stat.h>
52 #include <sys/signal.h>
53 #include <sys/sysctl.h>
54 #include <sys/wait.h>
55 
56 #include <net/if.h>
57 #include <net/if_dl.h>
58 #include <net/route.h>
59 #include <netinet/in.h>
60 #include <arpa/inet.h>
61 #include <protocols/rwhod.h>
62 
63 #include <ctype.h>
64 #include <capsicum_helpers.h>
65 #include <err.h>
66 #include <errno.h>
67 #include <fcntl.h>
68 #include <grp.h>
69 #include <netdb.h>
70 #include <paths.h>
71 #include <pwd.h>
72 #include <stdio.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <syslog.h>
76 #include <timeconv.h>
77 #include <utmpx.h>
78 #include <unistd.h>
79 
80 #define	UNPRIV_USER		"daemon"
81 #define	UNPRIV_GROUP		"daemon"
82 
83 #define NO_MULTICAST		0	  /* multicast modes */
84 #define PER_INTERFACE_MULTICAST	1
85 #define SCOPED_MULTICAST	2
86 
87 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
88 
89 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
90 						  /* (belongs in protocols/rwhod.h) */
91 
92 int	insecure_mode;
93 int	quiet_mode;
94 int	iff_flag = IFF_POINTOPOINT;
95 int	multicast_mode = NO_MULTICAST;
96 int	multicast_scope;
97 struct	sockaddr_in multicast_addr =
98 	{ sizeof(multicast_addr), AF_INET, 0, { 0 }, { 0 } };
99 
100 /*
101  * Sleep interval. Don't forget to change the down time check in ruptime
102  * if this is changed.
103  */
104 #define SL_INTERVAL (3 * 60)
105 
106 char	myname[MAXHOSTNAMELEN];
107 
108 /*
109  * We communicate with each neighbor in a list constructed at the time we're
110  * started up.  Neighbors are currently directly connected via a hardware
111  * interface.
112  */
113 struct	neighbor {
114 	struct	neighbor *n_next;
115 	char		 *n_name;		/* interface name */
116 	struct	sockaddr *n_addr;		/* who to send to */
117 	int		  n_addrlen;		/* size of address */
118 	int		  n_flags;		/* should forward?, interface flags */
119 };
120 
121 struct	neighbor *neighbors;
122 struct	whod mywd;
123 struct	servent	*sp;
124 int	s;
125 int	fdp;
126 pid_t	pid_child_receiver;
127 
128 #define	WHDRSIZE	(int)(sizeof(mywd) - sizeof(mywd.wd_we))
129 
130 int	configure(int so);
131 void	getboottime(int signo __unused);
132 void	receiver_process(void);
133 void	rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo);
134 void	run_as(uid_t *uid, gid_t *gid);
135 void	quit(const char *msg);
136 void	sender_process(void);
137 int	verify(char *name, int maxlen);
138 static void usage(void) __dead2;
139 
140 #ifdef DEBUG
141 char	*interval(int time, char *updown);
142 void	Sendto(int s, const void *buf, size_t cc, int flags,
143 	    const struct sockaddr *to, int tolen);
144 #define	 sendto Sendto
145 #endif
146 
147 /*
148  * This version of Berkeley's rwhod has been modified to use IP multicast
149  * datagrams, under control of a new command-line option:
150  *
151  *	rwhod -m	causes rwhod to use IP multicast (instead of
152  *			broadcast or unicast) on all interfaces that have
153  *			the IFF_MULTICAST flag set in their "ifnet" structs
154  *			(excluding the loopback interface).  The multicast
155  *			reports are sent with a time-to-live of 1, to prevent
156  *			forwarding beyond the directly-connected subnet(s).
157  *
158  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
159  *			time-to-live of <ttl>, via a SINGLE interface rather
160  *			than all interfaces.  <ttl> must be between 0 and
161  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
162  *			is different than "-m", in that "-m 1" specifies
163  *			transmission on one interface only.
164  *
165  * When "-m" is used without a <ttl> argument, the program accepts multicast
166  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
167  * is given, it accepts multicast reports from only one interface, the one
168  * on which reports are sent (which may be controlled via the host's routing
169  * table).  Regardless of the "-m" option, the program accepts broadcast or
170  * unicast reports from all interfaces.  Thus, this program will hear the
171  * reports of old, non-multicasting rwhods, but, if multicasting is used,
172  * those old rwhods won't hear the reports generated by this program.
173  *
174  *                  -- Steve Deering, Stanford University, February 1989
175  */
176 int
177 main(int argc, char *argv[])
178 {
179 	int on;
180 	char *cp;
181 	struct sockaddr_in soin;
182 	uid_t unpriv_uid;
183 	gid_t unpriv_gid;
184 
185 	on = 1;
186 	if (getuid())
187 		errx(1, "not super user");
188 
189 	run_as(&unpriv_uid, &unpriv_gid);
190 
191 	argv++;
192 	argc--;
193 	while (argc > 0 && *argv[0] == '-') {
194 		if (strcmp(*argv, "-m") == 0) {
195 			if (argc > 1 && isdigit(*(argv + 1)[0])) {
196 				argv++;
197 				argc--;
198 				multicast_mode  = SCOPED_MULTICAST;
199 				multicast_scope = atoi(*argv);
200 				if (multicast_scope > MAX_MULTICAST_SCOPE) {
201 					errx(1, "ttl must not exceed %u",
202 					    MAX_MULTICAST_SCOPE);
203 				}
204 			} else {
205 				multicast_mode = PER_INTERFACE_MULTICAST;
206 			}
207 		} else if (strcmp(*argv, "-i") == 0) {
208 			insecure_mode = 1;
209 		} else if (strcmp(*argv, "-l") == 0) {
210 			quiet_mode = 1;
211 		} else if (strcmp(*argv, "-p") == 0) {
212 			iff_flag = 0;
213 		} else {
214 			usage();
215 		}
216 		argv++;
217 		argc--;
218 	}
219 	if (argc > 0)
220 		usage();
221 #ifndef DEBUG
222 	daemon(1, 0);
223 #endif
224 	(void) signal(SIGHUP, getboottime);
225 	openlog("rwhod", LOG_PID | LOG_NDELAY, LOG_DAEMON);
226 	sp = getservbyname("who", "udp");
227 	if (sp == NULL) {
228 		syslog(LOG_ERR, "who/udp: unknown service");
229 		exit(1);
230 	}
231 	if (chdir(_PATH_RWHODIR) < 0) {
232 		syslog(LOG_ERR, "%s: %m", _PATH_RWHODIR);
233 		exit(1);
234 	}
235 	/*
236 	 * Establish host name as returned by system.
237 	 */
238 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
239 		syslog(LOG_ERR, "gethostname: %m");
240 		exit(1);
241 	}
242 	if ((cp = strchr(myname, '.')) != NULL)
243 		*cp = '\0';
244 	strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
245 	getboottime(0);
246 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
247 		syslog(LOG_ERR, "socket: %m");
248 		exit(1);
249 	}
250 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
251 		syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
252 		exit(1);
253 	}
254 	memset(&soin, 0, sizeof(soin));
255 	soin.sin_len = sizeof(soin);
256 	soin.sin_family = AF_INET;
257 	soin.sin_port = sp->s_port;
258 	if (bind(s, (struct sockaddr *)&soin, sizeof(soin)) < 0) {
259 		syslog(LOG_ERR, "bind: %m");
260 		exit(1);
261 	}
262 	if (setgid(unpriv_gid) != 0) {
263 		syslog(LOG_ERR, "setgid: %m");
264 		exit(1);
265 	}
266 	if (setgroups(1, &unpriv_gid) != 0) {	/* XXX BOGUS groups[0] = egid */
267 		syslog(LOG_ERR, "setgroups: %m");
268 		exit(1);
269 	}
270 	if (setuid(unpriv_uid) != 0) {
271 		syslog(LOG_ERR, "setuid: %m");
272 		exit(1);
273 	}
274 	if (!configure(s))
275 		exit(1);
276 	if (!quiet_mode) {
277 		pid_child_receiver = pdfork(&fdp, 0);
278 		if (pid_child_receiver == 0) {
279 			receiver_process();
280 		} else if (pid_child_receiver > 0) {
281 			sender_process();
282 		} else if (pid_child_receiver == -1) {
283 			if (errno == ENOSYS) {
284 				syslog(LOG_ERR,
285 				    "The pdfork(2) system call is not available - kernel too old.");
286 			} else {
287 				syslog(LOG_ERR, "pdfork: %m");
288 			}
289 			exit(1);
290 		}
291 	} else {
292 		receiver_process();
293 	}
294 }
295 
296 static void
297 usage(void)
298 {
299 
300 	fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
301 	exit(1);
302 }
303 
304 void
305 run_as(uid_t *uid, gid_t *gid)
306 {
307 	struct passwd *pw;
308 	struct group *gr;
309 
310 	pw = getpwnam(UNPRIV_USER);
311 	if (pw == NULL) {
312 		syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
313 		exit(1);
314 	}
315 	*uid = pw->pw_uid;
316 
317 	gr = getgrnam(UNPRIV_GROUP);
318 	if (gr == NULL) {
319 		syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
320 		exit(1);
321 	}
322 	*gid = gr->gr_gid;
323 }
324 
325 /*
326  * Check out host name for unprintables
327  * and other funnies before allowing a file
328  * to be created.  Sorry, but blanks aren't allowed.
329  */
330 int
331 verify(char *name, int maxlen)
332 {
333 	int size;
334 
335 	size = 0;
336 	while (*name != '\0' && size < maxlen - 1) {
337 		if (!isascii((unsigned char)*name) ||
338 		    !(isalnum((unsigned char)*name) ||
339 		    ispunct((unsigned char)*name))) {
340 			return (0);
341 		}
342 		name++;
343 		size++;
344 	}
345 	*name = '\0';
346 	return (size > 0);
347 }
348 
349 void
350 receiver_process(void)
351 {
352 	struct sockaddr_in from;
353 	struct stat st;
354 	cap_rights_t rights;
355 	char path[64];
356 	int dirfd;
357 	struct whod wd;
358 	socklen_t len;
359 	int cc, whod;
360 	time_t t;
361 
362 	len = sizeof(from);
363 	dirfd = open(".", O_RDONLY | O_DIRECTORY);
364 	if (dirfd < 0) {
365 		syslog(LOG_WARNING, "%s: %m", _PATH_RWHODIR);
366 		exit(1);
367 	}
368 	cap_rights_init(&rights, CAP_CREATE, CAP_FSTAT, CAP_FTRUNCATE,
369 	    CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
370 	if (caph_rights_limit(dirfd, &rights) < 0) {
371 		syslog(LOG_WARNING, "cap_rights_limit: %m");
372 		exit(1);
373 	}
374 	if (caph_enter() < 0) {
375 		syslog(LOG_ERR, "cap_enter: %m");
376 		exit(1);
377 	}
378 	for (;;) {
379 		cc = recvfrom(s, &wd, sizeof(wd), 0, (struct sockaddr *)&from,
380 		    &len);
381 		if (cc <= 0) {
382 			if (cc < 0 && errno != EINTR)
383 				syslog(LOG_WARNING, "recv: %m");
384 			continue;
385 		}
386 		if (from.sin_port != sp->s_port && !insecure_mode) {
387 			syslog(LOG_WARNING, "%d: bad source port from %s",
388 			    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
389 			continue;
390 		}
391 		if (cc < WHDRSIZE) {
392 			syslog(LOG_WARNING, "short packet from %s",
393 			    inet_ntoa(from.sin_addr));
394 			continue;
395 		}
396 		if (wd.wd_vers != WHODVERSION)
397 			continue;
398 		if (wd.wd_type != WHODTYPE_STATUS)
399 			continue;
400 		if (!verify(wd.wd_hostname, sizeof(wd.wd_hostname))) {
401 			syslog(LOG_WARNING, "malformed host name from %s",
402 			    inet_ntoa(from.sin_addr));
403 			continue;
404 		}
405 		(void) snprintf(path, sizeof(path), "whod.%s", wd.wd_hostname);
406 		/*
407 		 * Rather than truncating and growing the file each time,
408 		 * use ftruncate if size is less than previous size.
409 		 */
410 		whod = openat(dirfd, path, O_WRONLY | O_CREAT, 0644);
411 		if (whod < 0) {
412 			syslog(LOG_WARNING, "%s: %m", path);
413 			continue;
414 		}
415 		cap_rights_init(&rights, CAP_FSTAT, CAP_FTRUNCATE, CAP_WRITE);
416 		if (caph_rights_limit(whod, &rights) < 0) {
417 			syslog(LOG_WARNING, "cap_rights_limit: %m");
418 			exit(1);
419 		}
420 #if ENDIAN != BIG_ENDIAN
421 		{
422 			struct whoent *we;
423 			int i, n;
424 
425 			n = (cc - WHDRSIZE) / sizeof(struct whoent);
426 			/* undo header byte swapping before writing to file */
427 			wd.wd_sendtime = ntohl(wd.wd_sendtime);
428 			for (i = 0; i < 3; i++)
429 				wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
430 			wd.wd_boottime = ntohl(wd.wd_boottime);
431 			we = wd.wd_we;
432 			for (i = 0; i < n; i++) {
433 				we->we_idle = ntohl(we->we_idle);
434 				we->we_utmp.out_time =
435 				    ntohl(we->we_utmp.out_time);
436 				we++;
437 			}
438 		}
439 #endif
440 		(void) time(&t);
441 		wd.wd_recvtime = _time_to_int(t);
442 		(void) write(whod, (char *)&wd, cc);
443 		if (fstat(whod, &st) < 0 || st.st_size > cc)
444 			ftruncate(whod, cc);
445 		(void) close(whod);
446 	}
447 	(void) close(dirfd);
448 }
449 
450 void
451 sender_process(void)
452 {
453 	int sendcount;
454 	double avenrun[3];
455 	time_t now;
456 	int i, cc, status;
457 	struct utmpx *ut;
458 	struct stat stb;
459 	struct neighbor *np;
460 	struct whoent *we, *wend;
461 
462 	sendcount = 0;
463 	for (;;) {
464 		we = mywd.wd_we;
465 		now = time(NULL);
466 		if (sendcount % 10 == 0)
467 			getboottime(0);
468 		sendcount++;
469 		wend = &mywd.wd_we[1024 / sizeof(struct whoent)];
470 		setutxent();
471 		while ((ut = getutxent()) != NULL && we < wend) {
472 			if (ut->ut_type != USER_PROCESS)
473 				continue;
474 			strncpy(we->we_utmp.out_line, ut->ut_line,
475 			    sizeof(we->we_utmp.out_line));
476 			strncpy(we->we_utmp.out_name, ut->ut_user,
477 			    sizeof(we->we_utmp.out_name));
478 			we->we_utmp.out_time =
479 			    htonl(_time_to_time32(ut->ut_tv.tv_sec));
480 			we++;
481 		}
482 		endutxent();
483 
484 		if (chdir(_PATH_DEV) < 0) {
485 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
486 			exit(1);
487 		}
488 		wend = we;
489 		for (we = mywd.wd_we; we < wend; we++) {
490 			if (stat(we->we_utmp.out_line, &stb) >= 0)
491 				we->we_idle = htonl(now - stb.st_atime);
492 		}
493 		(void) getloadavg(avenrun,
494 		    sizeof(avenrun) / sizeof(avenrun[0]));
495 		for (i = 0; i < 3; i++)
496 			mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
497 		cc = (char *)wend - (char *)&mywd;
498 		mywd.wd_sendtime = htonl(_time_to_time32(time(NULL)));
499 		mywd.wd_vers = WHODVERSION;
500 		mywd.wd_type = WHODTYPE_STATUS;
501 		if (multicast_mode == SCOPED_MULTICAST) {
502 			(void) sendto(s, (char *)&mywd, cc, 0,
503 			    (struct sockaddr *)&multicast_addr,
504 			    sizeof(multicast_addr));
505 		} else {
506 			for (np = neighbors; np != NULL; np = np->n_next) {
507 				if (multicast_mode == PER_INTERFACE_MULTICAST &&
508 				    (np->n_flags & IFF_MULTICAST) != 0) {
509 					/*
510 					 * Select the outgoing interface for the
511 					 * multicast.
512 					 */
513 					if (setsockopt(s, IPPROTO_IP,
514 					    IP_MULTICAST_IF,
515 					    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
516 					    sizeof(struct in_addr)) < 0) {
517 						syslog(LOG_ERR,
518 						    "setsockopt IP_MULTICAST_IF: %m");
519 						exit(1);
520 					}
521 					(void) sendto(s, (char *)&mywd, cc, 0,
522 					    (struct sockaddr *)&multicast_addr,
523 					    sizeof(multicast_addr));
524 				} else {
525 					(void) sendto(s, (char *)&mywd, cc, 0,
526 					    np->n_addr, np->n_addrlen);
527 				}
528 			}
529 		}
530 		if (chdir(_PATH_RWHODIR) < 0) {
531 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
532 			exit(1);
533 		}
534 		if (waitpid(pid_child_receiver, &status, WNOHANG) ==
535 		    pid_child_receiver) {
536 			break;
537 		}
538 		sleep(SL_INTERVAL);
539 	}
540 }
541 
542 void
543 getboottime(int signo __unused)
544 {
545 	int mib[2];
546 	size_t size;
547 	struct timeval tm;
548 
549 	mib[0] = CTL_KERN;
550 	mib[1] = KERN_BOOTTIME;
551 	size = sizeof(tm);
552 	if (sysctl(mib, nitems(mib), &tm, &size, NULL, 0) == -1) {
553 		syslog(LOG_ERR, "cannot get boottime: %m");
554 		exit(1);
555 	}
556 	mywd.wd_boottime = htonl(_time_to_time32(tm.tv_sec));
557 }
558 
559 void
560 quit(const char *msg)
561 {
562 
563 	syslog(LOG_ERR, "%s", msg);
564 	exit(1);
565 }
566 
567 void
568 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
569 {
570 	struct sockaddr *sa;
571 	int i;
572 
573 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
574 	for (i = 0; i < RTAX_MAX && cp < cplim; i++) {
575 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
576 			continue;
577 		sa = (struct sockaddr *)cp;
578 		rtinfo->rti_info[i] = sa;
579 		cp += SA_SIZE(sa);
580 	}
581 }
582 
583 /*
584  * Figure out device configuration and select
585  * networks which deserve status information.
586  */
587 int
588 configure(int so)
589 {
590 	struct neighbor *np;
591 	struct if_msghdr *ifm;
592 	struct ifa_msghdr *ifam;
593 	struct sockaddr_dl *sdl;
594 	size_t needed;
595 	int mib[6], flags, lflags, len;
596 	char *buf, *lim, *next;
597 	struct rt_addrinfo info;
598 
599 	flags = 0;
600 	if (multicast_mode != NO_MULTICAST) {
601 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
602 		multicast_addr.sin_port = sp->s_port;
603 	}
604 
605 	if (multicast_mode == SCOPED_MULTICAST) {
606 		struct ip_mreq mreq;
607 		unsigned char ttl;
608 
609 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
610 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
611 		if (setsockopt(so, IPPROTO_IP, IP_ADD_MEMBERSHIP,
612 		    &mreq, sizeof(mreq)) < 0) {
613 			syslog(LOG_ERR,
614 			    "setsockopt IP_ADD_MEMBERSHIP: %m");
615 			return (0);
616 		}
617 		ttl = multicast_scope;
618 		if (setsockopt(so, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
619 		    sizeof(ttl)) < 0) {
620 			syslog(LOG_ERR,
621 			    "setsockopt IP_MULTICAST_TTL: %m");
622 			return (0);
623 		}
624 		return (1);
625 	}
626 
627 	mib[0] = CTL_NET;
628 	mib[1] = PF_ROUTE;
629 	mib[2] = 0;
630 	mib[3] = AF_INET;
631 	mib[4] = NET_RT_IFLIST;
632 	mib[5] = 0;
633 	if (sysctl(mib, nitems(mib), NULL, &needed, NULL, 0) < 0)
634 		quit("route-sysctl-estimate");
635 	if ((buf = malloc(needed)) == NULL)
636 		quit("malloc");
637 	if (sysctl(mib, nitems(mib), buf, &needed, NULL, 0) < 0)
638 		quit("actual retrieval of interface table");
639 	lim = buf + needed;
640 
641 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
642 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
643 		ifm = (struct if_msghdr *)next;
644 		if (ifm->ifm_type == RTM_IFINFO) {
645 			sdl = (struct sockaddr_dl *)(ifm + 1);
646 			flags = ifm->ifm_flags;
647 			continue;
648 		}
649 		if ((flags & IFF_UP) == 0)
650 			continue;
651 		lflags = IFF_BROADCAST | iff_flag;
652 		if (multicast_mode == PER_INTERFACE_MULTICAST)
653 			lflags |= IFF_MULTICAST;
654 		if ((flags & lflags) == 0)
655 			continue;
656 		if (ifm->ifm_type != RTM_NEWADDR)
657 			quit("out of sync parsing NET_RT_IFLIST");
658 		ifam = (struct ifa_msghdr *)ifm;
659 		info.rti_addrs = ifam->ifam_addrs;
660 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
661 		    &info);
662 		/* gag, wish we could get rid of Internet dependencies */
663 #define	dstaddr		info.rti_info[RTAX_BRD]
664 #define	ifaddr		info.rti_info[RTAX_IFA]
665 #define	IPADDR_SA(x)	((struct sockaddr_in *)(x))->sin_addr.s_addr
666 #define	PORT_SA(x)	((struct sockaddr_in *)(x))->sin_port
667 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
668 			continue;
669 		PORT_SA(dstaddr) = sp->s_port;
670 		for (np = neighbors; np != NULL; np = np->n_next) {
671 			if (memcmp(sdl->sdl_data, np->n_name,
672 			    sdl->sdl_nlen) == 0 &&
673 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr)) {
674 				break;
675 			}
676 		}
677 		if (np != NULL)
678 			continue;
679 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
680 		np = malloc(len);
681 		if (np == NULL)
682 			quit("malloc of neighbor structure");
683 		memset(np, 0, len);
684 		np->n_flags = flags;
685 		np->n_addr = (struct sockaddr *)(np + 1);
686 		np->n_addrlen = dstaddr->sa_len;
687 		np->n_name = np->n_addrlen + (char *)np->n_addr;
688 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
689 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
690 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
691 		    (flags & IFF_MULTICAST) != 0 &&
692 		    (flags & IFF_LOOPBACK) == 0) {
693 			struct ip_mreq mreq;
694 
695 			memcpy((char *)np->n_addr, (char *)ifaddr,
696 			    np->n_addrlen);
697 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
698 			mreq.imr_interface.s_addr =
699 			    ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
700 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
701 			    &mreq, sizeof(mreq)) < 0) {
702 				syslog(LOG_ERR,
703 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
704 #if 0
705 				/* Fall back to broadcast on this if. */
706 				np->n_flags &= ~IFF_MULTICAST;
707 #else
708 				free(np);
709 				continue;
710 #endif
711 			}
712 		}
713 		np->n_next = neighbors;
714 		neighbors = np;
715 	}
716 	free(buf);
717 	return (1);
718 }
719 
720 #ifdef DEBUG
721 void
722 Sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
723     int tolen)
724 {
725 	struct whod *w;
726 	struct whoent *we;
727 	struct sockaddr_in *sin;
728 
729 	w = (struct whod *)buf;
730 	sin = (struct sockaddr_in *)to;
731 	printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
732 	    ntohs(sin->sin_port));
733 	printf("hostname %s %s\n", w->wd_hostname,
734 	    interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
735 	printf("load %4.2f, %4.2f, %4.2f\n",
736 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
737 	    ntohl(w->wd_loadav[2]) / 100.0);
738 	cc -= WHDRSIZE;
739 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
740 		time_t t = _time32_to_time(ntohl(we->we_utmp.out_time));
741 
742 		printf("%-8.8s %s:%s %.12s", we->we_utmp.out_name,
743 		    w->wd_hostname, we->we_utmp.out_line, ctime(&t) + 4);
744 		we->we_idle = ntohl(we->we_idle) / 60;
745 		if (we->we_idle != 0) {
746 			if (we->we_idle >= 100 * 60)
747 				we->we_idle = 100 * 60 - 1;
748 			if (we->we_idle >= 60)
749 				printf(" %2d", we->we_idle / 60);
750 			else
751 				printf("   ");
752 			printf(":%02d", we->we_idle % 60);
753 		}
754 		printf("\n");
755 	}
756 }
757 
758 char *
759 interval(int time, char *updown)
760 {
761 	static char resbuf[32];
762 	int days, hours, minutes;
763 
764 	if (time < 0 || time > 3 * 30 * 24 * 60 * 60) {
765 		(void) sprintf(resbuf, "   %s ??:??", updown);
766 		return (resbuf);
767 	}
768 	minutes = (time + 59) / 60;		/* round to minutes */
769 	hours = minutes / 60;
770 	minutes %= 60;
771 	days = hours / 24;
772 	hours %= 24;
773 	if (days > 0) {
774 		(void) sprintf(resbuf, "%s %2d+%02d:%02d",
775 		    updown, days, hours, minutes);
776 	} else {
777 		(void) sprintf(resbuf, "%s    %2d:%02d",
778 		    updown, hours, minutes);
779 	}
780 	return (resbuf);
781 }
782 #endif
783