xref: /freebsd/usr.sbin/rwhod/rwhod.c (revision 56e53cb8ef000c3ef72337a4095987a932cdedef)
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 __FBSDID("$FreeBSD$");
47 
48 #include <sys/param.h>
49 #include <sys/capsicum.h>
50 #include <sys/ioctl.h>
51 #include <sys/procdesc.h>
52 #include <sys/socket.h>
53 #include <sys/stat.h>
54 #include <sys/signal.h>
55 #include <sys/sysctl.h>
56 #include <sys/wait.h>
57 
58 #include <net/if.h>
59 #include <net/if_dl.h>
60 #include <net/route.h>
61 #include <netinet/in.h>
62 #include <arpa/inet.h>
63 #include <protocols/rwhod.h>
64 
65 #include <ctype.h>
66 #include <err.h>
67 #include <errno.h>
68 #include <fcntl.h>
69 #include <grp.h>
70 #include <netdb.h>
71 #include <paths.h>
72 #include <pwd.h>
73 #include <stdio.h>
74 #include <stdlib.h>
75 #include <string.h>
76 #include <syslog.h>
77 #include <timeconv.h>
78 #include <utmpx.h>
79 #include <unistd.h>
80 
81 #define	UNPRIV_USER		"daemon"
82 #define	UNPRIV_GROUP		"daemon"
83 
84 #define NO_MULTICAST		0	  /* multicast modes */
85 #define PER_INTERFACE_MULTICAST	1
86 #define SCOPED_MULTICAST	2
87 
88 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
89 
90 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
91 						  /* (belongs in protocols/rwhod.h) */
92 
93 int	insecure_mode;
94 int	quiet_mode;
95 int	iff_flag = IFF_POINTOPOINT;
96 int	multicast_mode = NO_MULTICAST;
97 int	multicast_scope;
98 struct	sockaddr_in multicast_addr =
99 	{ sizeof(multicast_addr), AF_INET, 0, { 0 }, { 0 } };
100 
101 /*
102  * Sleep interval. Don't forget to change the down time check in ruptime
103  * if this is changed.
104  */
105 #define SL_INTERVAL (3 * 60)
106 
107 char	myname[MAXHOSTNAMELEN];
108 
109 /*
110  * We communicate with each neighbor in a list constructed at the time we're
111  * started up.  Neighbors are currently directly connected via a hardware
112  * interface.
113  */
114 struct	neighbor {
115 	struct	neighbor *n_next;
116 	char		 *n_name;		/* interface name */
117 	struct	sockaddr *n_addr;		/* who to send to */
118 	int		  n_addrlen;		/* size of address */
119 	int		  n_flags;		/* should forward?, interface flags */
120 };
121 
122 struct	neighbor *neighbors;
123 struct	whod mywd;
124 struct	servent	*sp;
125 int	s;
126 int	fdp;
127 pid_t	pid_child_receiver;
128 
129 #define	WHDRSIZE	(int)(sizeof(mywd) - sizeof(mywd.wd_we))
130 
131 int	configure(int so);
132 void	getboottime(int signo __unused);
133 void	receiver_process(void);
134 void	rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo);
135 void	run_as(uid_t *uid, gid_t *gid);
136 void	quit(const char *msg);
137 void	sender_process(void);
138 int	verify(char *name, int maxlen);
139 static void usage(void);
140 
141 #ifdef DEBUG
142 char	*interval(int time, char *updown);
143 void	Sendto(int s, const void *buf, size_t cc, int flags,
144 	    const struct sockaddr *to, int tolen);
145 #define	 sendto Sendto
146 #endif
147 
148 /*
149  * This version of Berkeley's rwhod has been modified to use IP multicast
150  * datagrams, under control of a new command-line option:
151  *
152  *	rwhod -m	causes rwhod to use IP multicast (instead of
153  *			broadcast or unicast) on all interfaces that have
154  *			the IFF_MULTICAST flag set in their "ifnet" structs
155  *			(excluding the loopback interface).  The multicast
156  *			reports are sent with a time-to-live of 1, to prevent
157  *			forwarding beyond the directly-connected subnet(s).
158  *
159  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
160  *			time-to-live of <ttl>, via a SINGLE interface rather
161  *			than all interfaces.  <ttl> must be between 0 and
162  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
163  *			is different than "-m", in that "-m 1" specifies
164  *			transmission on one interface only.
165  *
166  * When "-m" is used without a <ttl> argument, the program accepts multicast
167  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
168  * is given, it accepts multicast reports from only one interface, the one
169  * on which reports are sent (which may be controlled via the host's routing
170  * table).  Regardless of the "-m" option, the program accepts broadcast or
171  * unicast reports from all interfaces.  Thus, this program will hear the
172  * reports of old, non-multicasting rwhods, but, if multicasting is used,
173  * those old rwhods won't hear the reports generated by this program.
174  *
175  *                  -- Steve Deering, Stanford University, February 1989
176  */
177 int
178 main(int argc, char *argv[])
179 {
180 	int on;
181 	char *cp;
182 	struct sockaddr_in soin;
183 	uid_t unpriv_uid;
184 	gid_t unpriv_gid;
185 
186 	on = 1;
187 	if (getuid())
188 		errx(1, "not super user");
189 
190 	run_as(&unpriv_uid, &unpriv_gid);
191 
192 	argv++;
193 	argc--;
194 	while (argc > 0 && *argv[0] == '-') {
195 		if (strcmp(*argv, "-m") == 0) {
196 			if (argc > 1 && isdigit(*(argv + 1)[0])) {
197 				argv++;
198 				argc--;
199 				multicast_mode  = SCOPED_MULTICAST;
200 				multicast_scope = atoi(*argv);
201 				if (multicast_scope > MAX_MULTICAST_SCOPE) {
202 					errx(1, "ttl must not exceed %u",
203 					    MAX_MULTICAST_SCOPE);
204 				}
205 			} else {
206 				multicast_mode = PER_INTERFACE_MULTICAST;
207 			}
208 		} else if (strcmp(*argv, "-i") == 0) {
209 			insecure_mode = 1;
210 		} else if (strcmp(*argv, "-l") == 0) {
211 			quiet_mode = 1;
212 		} else if (strcmp(*argv, "-p") == 0) {
213 			iff_flag = 0;
214 		} else {
215 			usage();
216 		}
217 		argv++;
218 		argc--;
219 	}
220 	if (argc > 0)
221 		usage();
222 #ifndef DEBUG
223 	daemon(1, 0);
224 #endif
225 	(void) signal(SIGHUP, getboottime);
226 	openlog("rwhod", LOG_PID | LOG_NDELAY, LOG_DAEMON);
227 	sp = getservbyname("who", "udp");
228 	if (sp == NULL) {
229 		syslog(LOG_ERR, "who/udp: unknown service");
230 		exit(1);
231 	}
232 	if (chdir(_PATH_RWHODIR) < 0) {
233 		syslog(LOG_ERR, "%s: %m", _PATH_RWHODIR);
234 		exit(1);
235 	}
236 	/*
237 	 * Establish host name as returned by system.
238 	 */
239 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
240 		syslog(LOG_ERR, "gethostname: %m");
241 		exit(1);
242 	}
243 	if ((cp = strchr(myname, '.')) != NULL)
244 		*cp = '\0';
245 	strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
246 	getboottime(0);
247 	if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
248 		syslog(LOG_ERR, "socket: %m");
249 		exit(1);
250 	}
251 	if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0) {
252 		syslog(LOG_ERR, "setsockopt SO_BROADCAST: %m");
253 		exit(1);
254 	}
255 	memset(&soin, 0, sizeof(soin));
256 	soin.sin_len = sizeof(soin);
257 	soin.sin_family = AF_INET;
258 	soin.sin_port = sp->s_port;
259 	if (bind(s, (struct sockaddr *)&soin, sizeof(soin)) < 0) {
260 		syslog(LOG_ERR, "bind: %m");
261 		exit(1);
262 	}
263 	if (setgid(unpriv_gid) != 0) {
264 		syslog(LOG_ERR, "setgid: %m");
265 		exit(1);
266 	}
267 	if (setgroups(1, &unpriv_gid) != 0) {	/* XXX BOGUS groups[0] = egid */
268 		syslog(LOG_ERR, "setgroups: %m");
269 		exit(1);
270 	}
271 	if (setuid(unpriv_uid) != 0) {
272 		syslog(LOG_ERR, "setuid: %m");
273 		exit(1);
274 	}
275 	if (!configure(s))
276 		exit(1);
277 	if (!quiet_mode) {
278 		pid_child_receiver = pdfork(&fdp, 0);
279 		if (pid_child_receiver == 0) {
280 			receiver_process();
281 		} else if (pid_child_receiver > 0) {
282 			sender_process();
283 		} else if (pid_child_receiver == -1) {
284 			if (errno == ENOSYS) {
285 				syslog(LOG_ERR,
286 				    "The pdfork(2) system call is not available - kernel too old.");
287 			} else {
288 				syslog(LOG_ERR, "pdfork: %m");
289 			}
290 			exit(1);
291 		}
292 	} else {
293 		receiver_process();
294 	}
295 }
296 
297 static void
298 usage(void)
299 {
300 
301 	fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
302 	exit(1);
303 }
304 
305 void
306 run_as(uid_t *uid, gid_t *gid)
307 {
308 	struct passwd *pw;
309 	struct group *gr;
310 
311 	pw = getpwnam(UNPRIV_USER);
312 	if (pw == NULL) {
313 		syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
314 		exit(1);
315 	}
316 	*uid = pw->pw_uid;
317 
318 	gr = getgrnam(UNPRIV_GROUP);
319 	if (gr == NULL) {
320 		syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
321 		exit(1);
322 	}
323 	*gid = gr->gr_gid;
324 }
325 
326 /*
327  * Check out host name for unprintables
328  * and other funnies before allowing a file
329  * to be created.  Sorry, but blanks aren't allowed.
330  */
331 int
332 verify(char *name, int maxlen)
333 {
334 	int size;
335 
336 	size = 0;
337 	while (*name != '\0' && size < maxlen - 1) {
338 		if (!isascii((unsigned char)*name) ||
339 		    !(isalnum((unsigned char)*name) ||
340 		    ispunct((unsigned char)*name))) {
341 			return (0);
342 		}
343 		name++;
344 		size++;
345 	}
346 	*name = '\0';
347 	return (size > 0);
348 }
349 
350 void
351 receiver_process(void)
352 {
353 	struct sockaddr_in from;
354 	struct stat st;
355 	cap_rights_t rights;
356 	char path[64];
357 	int dirfd;
358 	struct whod wd;
359 	socklen_t len;
360 	int cc, whod;
361 	time_t t;
362 
363 	len = sizeof(from);
364 	dirfd = open(".", O_RDONLY | O_DIRECTORY);
365 	if (dirfd < 0) {
366 		syslog(LOG_WARNING, "%s: %m", _PATH_RWHODIR);
367 		exit(1);
368 	}
369 	cap_rights_init(&rights, CAP_CREATE, CAP_FSTAT, CAP_FTRUNCATE,
370 	    CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
371 	if (cap_rights_limit(dirfd, &rights) < 0 && errno != ENOSYS) {
372 		syslog(LOG_WARNING, "cap_rights_limit: %m");
373 		exit(1);
374 	}
375 	if (cap_enter() < 0 && errno != ENOSYS) {
376 		syslog(LOG_ERR, "cap_enter: %m");
377 		exit(1);
378 	}
379 	for (;;) {
380 		cc = recvfrom(s, &wd, sizeof(wd), 0, (struct sockaddr *)&from,
381 		    &len);
382 		if (cc <= 0) {
383 			if (cc < 0 && errno != EINTR)
384 				syslog(LOG_WARNING, "recv: %m");
385 			continue;
386 		}
387 		if (from.sin_port != sp->s_port && !insecure_mode) {
388 			syslog(LOG_WARNING, "%d: bad source port from %s",
389 			    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
390 			continue;
391 		}
392 		if (cc < WHDRSIZE) {
393 			syslog(LOG_WARNING, "short packet from %s",
394 			    inet_ntoa(from.sin_addr));
395 			continue;
396 		}
397 		if (wd.wd_vers != WHODVERSION)
398 			continue;
399 		if (wd.wd_type != WHODTYPE_STATUS)
400 			continue;
401 		if (!verify(wd.wd_hostname, sizeof(wd.wd_hostname))) {
402 			syslog(LOG_WARNING, "malformed host name from %s",
403 			    inet_ntoa(from.sin_addr));
404 			continue;
405 		}
406 		(void) snprintf(path, sizeof(path), "whod.%s", wd.wd_hostname);
407 		/*
408 		 * Rather than truncating and growing the file each time,
409 		 * use ftruncate if size is less than previous size.
410 		 */
411 		whod = openat(dirfd, path, O_WRONLY | O_CREAT, 0644);
412 		if (whod < 0) {
413 			syslog(LOG_WARNING, "%s: %m", path);
414 			continue;
415 		}
416 		cap_rights_init(&rights, CAP_FSTAT, CAP_FTRUNCATE, CAP_WRITE);
417 		if (cap_rights_limit(whod, &rights) < 0 && errno != ENOSYS) {
418 			syslog(LOG_WARNING, "cap_rights_limit: %m");
419 			exit(1);
420 		}
421 #if ENDIAN != BIG_ENDIAN
422 		{
423 			struct whoent *we;
424 			int i, n;
425 
426 			n = (cc - WHDRSIZE) / sizeof(struct whoent);
427 			/* undo header byte swapping before writing to file */
428 			wd.wd_sendtime = ntohl(wd.wd_sendtime);
429 			for (i = 0; i < 3; i++)
430 				wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
431 			wd.wd_boottime = ntohl(wd.wd_boottime);
432 			we = wd.wd_we;
433 			for (i = 0; i < n; i++) {
434 				we->we_idle = ntohl(we->we_idle);
435 				we->we_utmp.out_time =
436 				    ntohl(we->we_utmp.out_time);
437 				we++;
438 			}
439 		}
440 #endif
441 		(void) time(&t);
442 		wd.wd_recvtime = _time_to_int(t);
443 		(void) write(whod, (char *)&wd, cc);
444 		if (fstat(whod, &st) < 0 || st.st_size > cc)
445 			ftruncate(whod, cc);
446 		(void) close(whod);
447 	}
448 	(void) close(dirfd);
449 }
450 
451 void
452 sender_process(void)
453 {
454 	int sendcount;
455 	double avenrun[3];
456 	time_t now;
457 	int i, cc, status;
458 	struct utmpx *ut;
459 	struct stat stb;
460 	struct neighbor *np;
461 	struct whoent *we, *wend;
462 
463 	sendcount = 0;
464 	for (;;) {
465 		we = mywd.wd_we;
466 		now = time(NULL);
467 		if (sendcount % 10 == 0)
468 			getboottime(0);
469 		sendcount++;
470 		wend = &mywd.wd_we[1024 / sizeof(struct whoent)];
471 		setutxent();
472 		while ((ut = getutxent()) != NULL && we < wend) {
473 			if (ut->ut_type != USER_PROCESS)
474 				continue;
475 			strncpy(we->we_utmp.out_line, ut->ut_line,
476 			    sizeof(we->we_utmp.out_line));
477 			strncpy(we->we_utmp.out_name, ut->ut_user,
478 			    sizeof(we->we_utmp.out_name));
479 			we->we_utmp.out_time =
480 			    htonl(_time_to_time32(ut->ut_tv.tv_sec));
481 			we++;
482 		}
483 		endutxent();
484 
485 		if (chdir(_PATH_DEV) < 0) {
486 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
487 			exit(1);
488 		}
489 		wend = we;
490 		for (we = mywd.wd_we; we < wend; we++) {
491 			if (stat(we->we_utmp.out_line, &stb) >= 0)
492 				we->we_idle = htonl(now - stb.st_atime);
493 		}
494 		(void) getloadavg(avenrun,
495 		    sizeof(avenrun) / sizeof(avenrun[0]));
496 		for (i = 0; i < 3; i++)
497 			mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
498 		cc = (char *)wend - (char *)&mywd;
499 		mywd.wd_sendtime = htonl(_time_to_time32(time(NULL)));
500 		mywd.wd_vers = WHODVERSION;
501 		mywd.wd_type = WHODTYPE_STATUS;
502 		if (multicast_mode == SCOPED_MULTICAST) {
503 			(void) sendto(s, (char *)&mywd, cc, 0,
504 			    (struct sockaddr *)&multicast_addr,
505 			    sizeof(multicast_addr));
506 		} else {
507 			for (np = neighbors; np != NULL; np = np->n_next) {
508 				if (multicast_mode == PER_INTERFACE_MULTICAST &&
509 				    (np->n_flags & IFF_MULTICAST) != 0) {
510 					/*
511 					 * Select the outgoing interface for the
512 					 * multicast.
513 					 */
514 					if (setsockopt(s, IPPROTO_IP,
515 					    IP_MULTICAST_IF,
516 					    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
517 					    sizeof(struct in_addr)) < 0) {
518 						syslog(LOG_ERR,
519 						    "setsockopt IP_MULTICAST_IF: %m");
520 						exit(1);
521 					}
522 					(void) sendto(s, (char *)&mywd, cc, 0,
523 					    (struct sockaddr *)&multicast_addr,
524 					    sizeof(multicast_addr));
525 				} else {
526 					(void) sendto(s, (char *)&mywd, cc, 0,
527 					    np->n_addr, np->n_addrlen);
528 				}
529 			}
530 		}
531 		if (chdir(_PATH_RWHODIR) < 0) {
532 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
533 			exit(1);
534 		}
535 		if (waitpid(pid_child_receiver, &status, WNOHANG) ==
536 		    pid_child_receiver) {
537 			break;
538 		}
539 		sleep(SL_INTERVAL);
540 	}
541 }
542 
543 void
544 getboottime(int signo __unused)
545 {
546 	int mib[2];
547 	size_t size;
548 	struct timeval tm;
549 
550 	mib[0] = CTL_KERN;
551 	mib[1] = KERN_BOOTTIME;
552 	size = sizeof(tm);
553 	if (sysctl(mib, nitems(mib), &tm, &size, NULL, 0) == -1) {
554 		syslog(LOG_ERR, "cannot get boottime: %m");
555 		exit(1);
556 	}
557 	mywd.wd_boottime = htonl(_time_to_time32(tm.tv_sec));
558 }
559 
560 void
561 quit(const char *msg)
562 {
563 
564 	syslog(LOG_ERR, "%s", msg);
565 	exit(1);
566 }
567 
568 void
569 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
570 {
571 	struct sockaddr *sa;
572 	int i;
573 
574 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
575 	for (i = 0; i < RTAX_MAX && cp < cplim; i++) {
576 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
577 			continue;
578 		sa = (struct sockaddr *)cp;
579 		rtinfo->rti_info[i] = sa;
580 		cp += SA_SIZE(sa);
581 	}
582 }
583 
584 /*
585  * Figure out device configuration and select
586  * networks which deserve status information.
587  */
588 int
589 configure(int so)
590 {
591 	struct neighbor *np;
592 	struct if_msghdr *ifm;
593 	struct ifa_msghdr *ifam;
594 	struct sockaddr_dl *sdl;
595 	size_t needed;
596 	int mib[6], flags, lflags, len;
597 	char *buf, *lim, *next;
598 	struct rt_addrinfo info;
599 
600 	flags = 0;
601 	if (multicast_mode != NO_MULTICAST) {
602 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
603 		multicast_addr.sin_port = sp->s_port;
604 	}
605 
606 	if (multicast_mode == SCOPED_MULTICAST) {
607 		struct ip_mreq mreq;
608 		unsigned char ttl;
609 
610 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
611 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
612 		if (setsockopt(so, IPPROTO_IP, IP_ADD_MEMBERSHIP,
613 		    &mreq, sizeof(mreq)) < 0) {
614 			syslog(LOG_ERR,
615 			    "setsockopt IP_ADD_MEMBERSHIP: %m");
616 			return (0);
617 		}
618 		ttl = multicast_scope;
619 		if (setsockopt(so, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
620 		    sizeof(ttl)) < 0) {
621 			syslog(LOG_ERR,
622 			    "setsockopt IP_MULTICAST_TTL: %m");
623 			return (0);
624 		}
625 		return (1);
626 	}
627 
628 	mib[0] = CTL_NET;
629 	mib[1] = PF_ROUTE;
630 	mib[2] = 0;
631 	mib[3] = AF_INET;
632 	mib[4] = NET_RT_IFLIST;
633 	mib[5] = 0;
634 	if (sysctl(mib, nitems(mib), NULL, &needed, NULL, 0) < 0)
635 		quit("route-sysctl-estimate");
636 	if ((buf = malloc(needed)) == NULL)
637 		quit("malloc");
638 	if (sysctl(mib, nitems(mib), buf, &needed, NULL, 0) < 0)
639 		quit("actual retrieval of interface table");
640 	lim = buf + needed;
641 
642 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
643 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
644 		ifm = (struct if_msghdr *)next;
645 		if (ifm->ifm_type == RTM_IFINFO) {
646 			sdl = (struct sockaddr_dl *)(ifm + 1);
647 			flags = ifm->ifm_flags;
648 			continue;
649 		}
650 		if ((flags & IFF_UP) == 0)
651 			continue;
652 		lflags = IFF_BROADCAST | iff_flag;
653 		if (multicast_mode == PER_INTERFACE_MULTICAST)
654 			lflags |= IFF_MULTICAST;
655 		if ((flags & lflags) == 0)
656 			continue;
657 		if (ifm->ifm_type != RTM_NEWADDR)
658 			quit("out of sync parsing NET_RT_IFLIST");
659 		ifam = (struct ifa_msghdr *)ifm;
660 		info.rti_addrs = ifam->ifam_addrs;
661 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
662 		    &info);
663 		/* gag, wish we could get rid of Internet dependencies */
664 #define	dstaddr		info.rti_info[RTAX_BRD]
665 #define	ifaddr		info.rti_info[RTAX_IFA]
666 #define	IPADDR_SA(x)	((struct sockaddr_in *)(x))->sin_addr.s_addr
667 #define	PORT_SA(x)	((struct sockaddr_in *)(x))->sin_port
668 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
669 			continue;
670 		PORT_SA(dstaddr) = sp->s_port;
671 		for (np = neighbors; np != NULL; np = np->n_next) {
672 			if (memcmp(sdl->sdl_data, np->n_name,
673 			    sdl->sdl_nlen) == 0 &&
674 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr)) {
675 				break;
676 			}
677 		}
678 		if (np != NULL)
679 			continue;
680 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
681 		np = malloc(len);
682 		if (np == NULL)
683 			quit("malloc of neighbor structure");
684 		memset(np, 0, len);
685 		np->n_flags = flags;
686 		np->n_addr = (struct sockaddr *)(np + 1);
687 		np->n_addrlen = dstaddr->sa_len;
688 		np->n_name = np->n_addrlen + (char *)np->n_addr;
689 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
690 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
691 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
692 		    (flags & IFF_MULTICAST) != 0 &&
693 		    (flags & IFF_LOOPBACK) == 0) {
694 			struct ip_mreq mreq;
695 
696 			memcpy((char *)np->n_addr, (char *)ifaddr,
697 			    np->n_addrlen);
698 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
699 			mreq.imr_interface.s_addr =
700 			    ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
701 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
702 			    &mreq, sizeof(mreq)) < 0) {
703 				syslog(LOG_ERR,
704 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
705 #if 0
706 				/* Fall back to broadcast on this if. */
707 				np->n_flags &= ~IFF_MULTICAST;
708 #else
709 				free(np);
710 				continue;
711 #endif
712 			}
713 		}
714 		np->n_next = neighbors;
715 		neighbors = np;
716 	}
717 	free(buf);
718 	return (1);
719 }
720 
721 #ifdef DEBUG
722 void
723 Sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
724     int tolen)
725 {
726 	struct whod *w;
727 	struct whoent *we;
728 	struct sockaddr_in *sin;
729 
730 	w = (struct whod *)buf;
731 	sin = (struct sockaddr_in *)to;
732 	printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
733 	    ntohs(sin->sin_port));
734 	printf("hostname %s %s\n", w->wd_hostname,
735 	    interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
736 	printf("load %4.2f, %4.2f, %4.2f\n",
737 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
738 	    ntohl(w->wd_loadav[2]) / 100.0);
739 	cc -= WHDRSIZE;
740 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
741 		time_t t = _time32_to_time(ntohl(we->we_utmp.out_time));
742 
743 		printf("%-8.8s %s:%s %.12s", we->we_utmp.out_name,
744 		    w->wd_hostname, we->we_utmp.out_line, ctime(&t) + 4);
745 		we->we_idle = ntohl(we->we_idle) / 60;
746 		if (we->we_idle != 0) {
747 			if (we->we_idle >= 100 * 60)
748 				we->we_idle = 100 * 60 - 1;
749 			if (we->we_idle >= 60)
750 				printf(" %2d", we->we_idle / 60);
751 			else
752 				printf("   ");
753 			printf(":%02d", we->we_idle % 60);
754 		}
755 		printf("\n");
756 	}
757 }
758 
759 char *
760 interval(int time, char *updown)
761 {
762 	static char resbuf[32];
763 	int days, hours, minutes;
764 
765 	if (time < 0 || time > 3 * 30 * 24 * 60 * 60) {
766 		(void) sprintf(resbuf, "   %s ??:??", updown);
767 		return (resbuf);
768 	}
769 	minutes = (time + 59) / 60;		/* round to minutes */
770 	hours = minutes / 60;
771 	minutes %= 60;
772 	days = hours / 24;
773 	hours %= 24;
774 	if (days > 0) {
775 		(void) sprintf(resbuf, "%s %2d+%02d:%02d",
776 		    updown, days, hours, minutes);
777 	} else {
778 		(void) sprintf(resbuf, "%s    %2d:%02d",
779 		    updown, hours, minutes);
780 	}
781 	return (resbuf);
782 }
783 #endif
784