xref: /freebsd/usr.sbin/rwhod/rwhod.c (revision fd45b686f9d92f583366c75b22c04c7ee49709c0)
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 #include <sys/param.h>
34 #include <sys/capsicum.h>
35 #include <sys/ioctl.h>
36 #include <sys/procdesc.h>
37 #include <sys/socket.h>
38 #include <sys/stat.h>
39 #include <sys/signal.h>
40 #include <sys/sysctl.h>
41 #include <sys/wait.h>
42 
43 #include <net/if.h>
44 #include <net/if_dl.h>
45 #include <net/route.h>
46 #include <netinet/in.h>
47 #include <arpa/inet.h>
48 #include <protocols/rwhod.h>
49 
50 #include <ctype.h>
51 #include <capsicum_helpers.h>
52 #include <err.h>
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <grp.h>
56 #include <netdb.h>
57 #include <paths.h>
58 #include <pwd.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 #include <syslog.h>
63 #include <timeconv.h>
64 #include <utmpx.h>
65 #include <unistd.h>
66 
67 #define	UNPRIV_USER		"daemon"
68 #define	UNPRIV_GROUP		"daemon"
69 
70 #define NO_MULTICAST		0	  /* multicast modes */
71 #define PER_INTERFACE_MULTICAST	1
72 #define SCOPED_MULTICAST	2
73 
74 #define MAX_MULTICAST_SCOPE	32	  /* "site-wide", by convention */
75 
76 #define INADDR_WHOD_GROUP (u_long)0xe0000103      /* 224.0.1.3 */
77 						  /* (belongs in protocols/rwhod.h) */
78 
79 int	insecure_mode;
80 int	quiet_mode;
81 int	iff_flag = IFF_POINTOPOINT;
82 int	multicast_mode = NO_MULTICAST;
83 int	multicast_scope;
84 struct	sockaddr_in multicast_addr =
85 	{ sizeof(multicast_addr), AF_INET, 0, { 0 }, { 0 } };
86 
87 /*
88  * Sleep interval. Don't forget to change the down time check in ruptime
89  * if this is changed.
90  */
91 #define SL_INTERVAL (3 * 60)
92 
93 char	myname[MAXHOSTNAMELEN];
94 
95 /*
96  * We communicate with each neighbor in a list constructed at the time we're
97  * started up.  Neighbors are currently directly connected via a hardware
98  * interface.
99  */
100 struct	neighbor {
101 	struct	neighbor *n_next;
102 	char		 *n_name;		/* interface name */
103 	struct	sockaddr *n_addr;		/* who to send to */
104 	int		  n_addrlen;		/* size of address */
105 	int		  n_flags;		/* should forward?, interface flags */
106 };
107 
108 struct	neighbor *neighbors;
109 struct	whod mywd;
110 struct	servent	*sp;
111 int	s;
112 int	fdp;
113 pid_t	pid_child_receiver;
114 
115 #define	WHDRSIZE	(int)(sizeof(mywd) - sizeof(mywd.wd_we))
116 
117 int	configure(int so);
118 void	getboottime(int signo __unused);
119 void	receiver_process(void);
120 void	rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo);
121 void	run_as(uid_t *uid, gid_t *gid);
122 void	quit(const char *msg);
123 void	sender_process(void);
124 int	verify(char *name, int maxlen);
125 static void usage(void) __dead2;
126 
127 #ifdef DEBUG
128 char	*interval(int time, char *updown);
129 void	Sendto(int s, const void *buf, size_t cc, int flags,
130 	    const struct sockaddr *to, int tolen);
131 #define	 sendto Sendto
132 #endif
133 
134 /*
135  * This version of Berkeley's rwhod has been modified to use IP multicast
136  * datagrams, under control of a new command-line option:
137  *
138  *	rwhod -m	causes rwhod to use IP multicast (instead of
139  *			broadcast or unicast) on all interfaces that have
140  *			the IFF_MULTICAST flag set in their "ifnet" structs
141  *			(excluding the loopback interface).  The multicast
142  *			reports are sent with a time-to-live of 1, to prevent
143  *			forwarding beyond the directly-connected subnet(s).
144  *
145  *	rwhod -m <ttl>	causes rwhod to send IP multicast datagrams with a
146  *			time-to-live of <ttl>, via a SINGLE interface rather
147  *			than all interfaces.  <ttl> must be between 0 and
148  *			MAX_MULTICAST_SCOPE, defined below.  Note that "-m 1"
149  *			is different than "-m", in that "-m 1" specifies
150  *			transmission on one interface only.
151  *
152  * When "-m" is used without a <ttl> argument, the program accepts multicast
153  * rwhod reports from all multicast-capable interfaces.  If a <ttl> argument
154  * is given, it accepts multicast reports from only one interface, the one
155  * on which reports are sent (which may be controlled via the host's routing
156  * table).  Regardless of the "-m" option, the program accepts broadcast or
157  * unicast reports from all interfaces.  Thus, this program will hear the
158  * reports of old, non-multicasting rwhods, but, if multicasting is used,
159  * those old rwhods won't hear the reports generated by this program.
160  *
161  *                  -- Steve Deering, Stanford University, February 1989
162  */
163 int
164 main(int argc, char *argv[])
165 {
166 	int on;
167 	char *cp;
168 	struct sockaddr_in soin;
169 	uid_t unpriv_uid;
170 	gid_t unpriv_gid;
171 
172 	on = 1;
173 	if (getuid())
174 		errx(1, "not super user");
175 
176 	run_as(&unpriv_uid, &unpriv_gid);
177 
178 	argv++;
179 	argc--;
180 	while (argc > 0 && *argv[0] == '-') {
181 		if (strcmp(*argv, "-m") == 0) {
182 			if (argc > 1 && isdigit(*(argv + 1)[0])) {
183 				argv++;
184 				argc--;
185 				multicast_mode  = SCOPED_MULTICAST;
186 				multicast_scope = atoi(*argv);
187 				if (multicast_scope > MAX_MULTICAST_SCOPE) {
188 					errx(1, "ttl must not exceed %u",
189 					    MAX_MULTICAST_SCOPE);
190 				}
191 			} else {
192 				multicast_mode = PER_INTERFACE_MULTICAST;
193 			}
194 		} else if (strcmp(*argv, "-i") == 0) {
195 			insecure_mode = 1;
196 		} else if (strcmp(*argv, "-l") == 0) {
197 			quiet_mode = 1;
198 		} else if (strcmp(*argv, "-p") == 0) {
199 			iff_flag = 0;
200 		} else {
201 			usage();
202 		}
203 		argv++;
204 		argc--;
205 	}
206 	if (argc > 0)
207 		usage();
208 #ifndef DEBUG
209 	daemon(1, 0);
210 #endif
211 	(void) signal(SIGHUP, getboottime);
212 	openlog("rwhod", LOG_PID | LOG_NDELAY, LOG_DAEMON);
213 	sp = getservbyname("who", "udp");
214 	if (sp == NULL) {
215 		syslog(LOG_ERR, "who/udp: unknown service");
216 		exit(1);
217 	}
218 	if (chdir(_PATH_RWHODIR) < 0) {
219 		syslog(LOG_ERR, "%s: %m", _PATH_RWHODIR);
220 		exit(1);
221 	}
222 	/*
223 	 * Establish host name as returned by system.
224 	 */
225 	if (gethostname(myname, sizeof(myname) - 1) < 0) {
226 		syslog(LOG_ERR, "gethostname: %m");
227 		exit(1);
228 	}
229 	if ((cp = strchr(myname, '.')) != NULL)
230 		*cp = '\0';
231 	strlcpy(mywd.wd_hostname, myname, sizeof(mywd.wd_hostname));
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(&soin, 0, sizeof(soin));
242 	soin.sin_len = sizeof(soin);
243 	soin.sin_family = AF_INET;
244 	soin.sin_port = sp->s_port;
245 	if (bind(s, (struct sockaddr *)&soin, sizeof(soin)) < 0) {
246 		syslog(LOG_ERR, "bind: %m");
247 		exit(1);
248 	}
249 	if (setgid(unpriv_gid) != 0) {
250 		syslog(LOG_ERR, "setgid: %m");
251 		exit(1);
252 	}
253 	if (setgroups(1, &unpriv_gid) != 0) {	/* XXX BOGUS groups[0] = egid */
254 		syslog(LOG_ERR, "setgroups: %m");
255 		exit(1);
256 	}
257 	if (setuid(unpriv_uid) != 0) {
258 		syslog(LOG_ERR, "setuid: %m");
259 		exit(1);
260 	}
261 	if (!configure(s))
262 		exit(1);
263 	if (!quiet_mode) {
264 		pid_child_receiver = pdfork(&fdp, 0);
265 		if (pid_child_receiver == 0) {
266 			receiver_process();
267 		} else if (pid_child_receiver > 0) {
268 			sender_process();
269 		} else if (pid_child_receiver == -1) {
270 			if (errno == ENOSYS) {
271 				syslog(LOG_ERR,
272 				    "The pdfork(2) system call is not available - kernel too old.");
273 			} else {
274 				syslog(LOG_ERR, "pdfork: %m");
275 			}
276 			exit(1);
277 		}
278 	} else {
279 		receiver_process();
280 	}
281 }
282 
283 static void
284 usage(void)
285 {
286 
287 	fprintf(stderr, "usage: rwhod [-i] [-p] [-l] [-m [ttl]]\n");
288 	exit(1);
289 }
290 
291 void
292 run_as(uid_t *uid, gid_t *gid)
293 {
294 	struct passwd *pw;
295 	struct group *gr;
296 
297 	pw = getpwnam(UNPRIV_USER);
298 	if (pw == NULL) {
299 		syslog(LOG_ERR, "getpwnam(%s): %m", UNPRIV_USER);
300 		exit(1);
301 	}
302 	*uid = pw->pw_uid;
303 
304 	gr = getgrnam(UNPRIV_GROUP);
305 	if (gr == NULL) {
306 		syslog(LOG_ERR, "getgrnam(%s): %m", UNPRIV_GROUP);
307 		exit(1);
308 	}
309 	*gid = gr->gr_gid;
310 }
311 
312 /*
313  * Check out host name for unprintables
314  * and other funnies before allowing a file
315  * to be created.  Sorry, but blanks aren't allowed.
316  */
317 int
318 verify(char *name, int maxlen)
319 {
320 	int size;
321 
322 	size = 0;
323 	while (*name != '\0' && size < maxlen - 1) {
324 		if (!isascii((unsigned char)*name) ||
325 		    !(isalnum((unsigned char)*name) ||
326 		    ispunct((unsigned char)*name))) {
327 			return (0);
328 		}
329 		name++;
330 		size++;
331 	}
332 	*name = '\0';
333 	return (size > 0);
334 }
335 
336 void
337 receiver_process(void)
338 {
339 	struct sockaddr_in from;
340 	struct stat st;
341 	cap_rights_t rights;
342 	char path[64];
343 	int dirfd;
344 	struct whod wd;
345 	socklen_t len;
346 	int cc, whod;
347 	time_t t;
348 
349 	len = sizeof(from);
350 	dirfd = open(".", O_RDONLY | O_DIRECTORY);
351 	if (dirfd < 0) {
352 		syslog(LOG_WARNING, "%s: %m", _PATH_RWHODIR);
353 		exit(1);
354 	}
355 	cap_rights_init(&rights, CAP_CREATE, CAP_FSTAT, CAP_FTRUNCATE,
356 	    CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
357 	if (caph_rights_limit(dirfd, &rights) < 0) {
358 		syslog(LOG_WARNING, "cap_rights_limit: %m");
359 		exit(1);
360 	}
361 	if (caph_enter() < 0) {
362 		syslog(LOG_ERR, "cap_enter: %m");
363 		exit(1);
364 	}
365 	for (;;) {
366 		cc = recvfrom(s, &wd, sizeof(wd), 0, (struct sockaddr *)&from,
367 		    &len);
368 		if (cc <= 0) {
369 			if (cc < 0 && errno != EINTR)
370 				syslog(LOG_WARNING, "recv: %m");
371 			continue;
372 		}
373 		if (from.sin_port != sp->s_port && !insecure_mode) {
374 			syslog(LOG_WARNING, "%d: bad source port from %s",
375 			    ntohs(from.sin_port), inet_ntoa(from.sin_addr));
376 			continue;
377 		}
378 		if (cc < WHDRSIZE) {
379 			syslog(LOG_WARNING, "short packet from %s",
380 			    inet_ntoa(from.sin_addr));
381 			continue;
382 		}
383 		if (wd.wd_vers != WHODVERSION)
384 			continue;
385 		if (wd.wd_type != WHODTYPE_STATUS)
386 			continue;
387 		if (!verify(wd.wd_hostname, sizeof(wd.wd_hostname))) {
388 			syslog(LOG_WARNING, "malformed host name from %s",
389 			    inet_ntoa(from.sin_addr));
390 			continue;
391 		}
392 		(void) snprintf(path, sizeof(path), "whod.%s", wd.wd_hostname);
393 		/*
394 		 * Rather than truncating and growing the file each time,
395 		 * use ftruncate if size is less than previous size.
396 		 */
397 		whod = openat(dirfd, path, O_WRONLY | O_CREAT, 0644);
398 		if (whod < 0) {
399 			syslog(LOG_WARNING, "%s: %m", path);
400 			continue;
401 		}
402 		cap_rights_init(&rights, CAP_FSTAT, CAP_FTRUNCATE, CAP_WRITE);
403 		if (caph_rights_limit(whod, &rights) < 0) {
404 			syslog(LOG_WARNING, "cap_rights_limit: %m");
405 			exit(1);
406 		}
407 #if ENDIAN != BIG_ENDIAN
408 		{
409 			struct whoent *we;
410 			int i, n;
411 
412 			n = (cc - WHDRSIZE) / sizeof(struct whoent);
413 			/* undo header byte swapping before writing to file */
414 			wd.wd_sendtime = ntohl(wd.wd_sendtime);
415 			for (i = 0; i < 3; i++)
416 				wd.wd_loadav[i] = ntohl(wd.wd_loadav[i]);
417 			wd.wd_boottime = ntohl(wd.wd_boottime);
418 			we = wd.wd_we;
419 			for (i = 0; i < n; i++) {
420 				we->we_idle = ntohl(we->we_idle);
421 				we->we_utmp.out_time =
422 				    ntohl(we->we_utmp.out_time);
423 				we++;
424 			}
425 		}
426 #endif
427 		(void) time(&t);
428 		wd.wd_recvtime = _time_to_int(t);
429 		(void) write(whod, (char *)&wd, cc);
430 		if (fstat(whod, &st) < 0 || st.st_size > cc)
431 			ftruncate(whod, cc);
432 		(void) close(whod);
433 	}
434 	(void) close(dirfd);
435 }
436 
437 void
438 sender_process(void)
439 {
440 	int sendcount;
441 	double avenrun[3];
442 	time_t now;
443 	int i, cc, status;
444 	struct utmpx *ut;
445 	struct stat stb;
446 	struct neighbor *np;
447 	struct whoent *we, *wend;
448 
449 	sendcount = 0;
450 	for (;;) {
451 		we = mywd.wd_we;
452 		now = time(NULL);
453 		if (sendcount % 10 == 0)
454 			getboottime(0);
455 		sendcount++;
456 		wend = &mywd.wd_we[1024 / sizeof(struct whoent)];
457 		setutxent();
458 		while ((ut = getutxent()) != NULL && we < wend) {
459 			if (ut->ut_type != USER_PROCESS)
460 				continue;
461 			strncpy(we->we_utmp.out_line, ut->ut_line,
462 			    sizeof(we->we_utmp.out_line));
463 			strncpy(we->we_utmp.out_name, ut->ut_user,
464 			    sizeof(we->we_utmp.out_name));
465 			we->we_utmp.out_time =
466 			    htonl(_time_to_time32(ut->ut_tv.tv_sec));
467 			we++;
468 		}
469 		endutxent();
470 
471 		if (chdir(_PATH_DEV) < 0) {
472 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_DEV);
473 			exit(1);
474 		}
475 		wend = we;
476 		for (we = mywd.wd_we; we < wend; we++) {
477 			if (stat(we->we_utmp.out_line, &stb) >= 0)
478 				we->we_idle = htonl(now - stb.st_atime);
479 		}
480 		(void) getloadavg(avenrun,
481 		    sizeof(avenrun) / sizeof(avenrun[0]));
482 		for (i = 0; i < 3; i++)
483 			mywd.wd_loadav[i] = htonl((u_long)(avenrun[i] * 100));
484 		cc = (char *)wend - (char *)&mywd;
485 		mywd.wd_sendtime = htonl(_time_to_time32(time(NULL)));
486 		mywd.wd_vers = WHODVERSION;
487 		mywd.wd_type = WHODTYPE_STATUS;
488 		if (multicast_mode == SCOPED_MULTICAST) {
489 			(void) sendto(s, (char *)&mywd, cc, 0,
490 			    (struct sockaddr *)&multicast_addr,
491 			    sizeof(multicast_addr));
492 		} else {
493 			for (np = neighbors; np != NULL; np = np->n_next) {
494 				if (multicast_mode == PER_INTERFACE_MULTICAST &&
495 				    (np->n_flags & IFF_MULTICAST) != 0) {
496 					/*
497 					 * Select the outgoing interface for the
498 					 * multicast.
499 					 */
500 					if (setsockopt(s, IPPROTO_IP,
501 					    IP_MULTICAST_IF,
502 					    &(((struct sockaddr_in *)np->n_addr)->sin_addr),
503 					    sizeof(struct in_addr)) < 0) {
504 						syslog(LOG_ERR,
505 						    "setsockopt IP_MULTICAST_IF: %m");
506 						exit(1);
507 					}
508 					(void) sendto(s, (char *)&mywd, cc, 0,
509 					    (struct sockaddr *)&multicast_addr,
510 					    sizeof(multicast_addr));
511 				} else {
512 					(void) sendto(s, (char *)&mywd, cc, 0,
513 					    np->n_addr, np->n_addrlen);
514 				}
515 			}
516 		}
517 		if (chdir(_PATH_RWHODIR) < 0) {
518 			syslog(LOG_ERR, "chdir(%s): %m", _PATH_RWHODIR);
519 			exit(1);
520 		}
521 		if (waitpid(pid_child_receiver, &status, WNOHANG) ==
522 		    pid_child_receiver) {
523 			break;
524 		}
525 		sleep(SL_INTERVAL);
526 	}
527 }
528 
529 void
530 getboottime(int signo __unused)
531 {
532 	int mib[2];
533 	size_t size;
534 	struct timeval tm;
535 
536 	mib[0] = CTL_KERN;
537 	mib[1] = KERN_BOOTTIME;
538 	size = sizeof(tm);
539 	if (sysctl(mib, nitems(mib), &tm, &size, NULL, 0) == -1) {
540 		syslog(LOG_ERR, "cannot get boottime: %m");
541 		exit(1);
542 	}
543 	mywd.wd_boottime = htonl(_time_to_time32(tm.tv_sec));
544 }
545 
546 void
547 quit(const char *msg)
548 {
549 
550 	syslog(LOG_ERR, "%s", msg);
551 	exit(1);
552 }
553 
554 void
555 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
556 {
557 	struct sockaddr *sa;
558 	int i;
559 
560 	memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
561 	for (i = 0; i < RTAX_MAX && cp < cplim; i++) {
562 		if ((rtinfo->rti_addrs & (1 << i)) == 0)
563 			continue;
564 		sa = (struct sockaddr *)cp;
565 		rtinfo->rti_info[i] = sa;
566 		cp += SA_SIZE(sa);
567 	}
568 }
569 
570 /*
571  * Figure out device configuration and select
572  * networks which deserve status information.
573  */
574 int
575 configure(int so)
576 {
577 	struct neighbor *np;
578 	struct if_msghdr *ifm;
579 	struct ifa_msghdr *ifam;
580 	struct sockaddr_dl *sdl;
581 	size_t needed;
582 	int mib[6], flags, lflags, len;
583 	char *buf, *lim, *next;
584 	struct rt_addrinfo info;
585 
586 	flags = 0;
587 	if (multicast_mode != NO_MULTICAST) {
588 		multicast_addr.sin_addr.s_addr = htonl(INADDR_WHOD_GROUP);
589 		multicast_addr.sin_port = sp->s_port;
590 	}
591 
592 	if (multicast_mode == SCOPED_MULTICAST) {
593 		struct ip_mreq mreq;
594 		unsigned char ttl;
595 
596 		mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
597 		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
598 		if (setsockopt(so, IPPROTO_IP, IP_ADD_MEMBERSHIP,
599 		    &mreq, sizeof(mreq)) < 0) {
600 			syslog(LOG_ERR,
601 			    "setsockopt IP_ADD_MEMBERSHIP: %m");
602 			return (0);
603 		}
604 		ttl = multicast_scope;
605 		if (setsockopt(so, IPPROTO_IP, IP_MULTICAST_TTL, &ttl,
606 		    sizeof(ttl)) < 0) {
607 			syslog(LOG_ERR,
608 			    "setsockopt IP_MULTICAST_TTL: %m");
609 			return (0);
610 		}
611 		return (1);
612 	}
613 
614 	mib[0] = CTL_NET;
615 	mib[1] = PF_ROUTE;
616 	mib[2] = 0;
617 	mib[3] = AF_INET;
618 	mib[4] = NET_RT_IFLIST;
619 	mib[5] = 0;
620 	if (sysctl(mib, nitems(mib), NULL, &needed, NULL, 0) < 0)
621 		quit("route-sysctl-estimate");
622 	if ((buf = malloc(needed)) == NULL)
623 		quit("malloc");
624 	if (sysctl(mib, nitems(mib), buf, &needed, NULL, 0) < 0)
625 		quit("actual retrieval of interface table");
626 	lim = buf + needed;
627 
628 	sdl = NULL;		/* XXX just to keep gcc -Wall happy */
629 	for (next = buf; next < lim; next += ifm->ifm_msglen) {
630 		ifm = (struct if_msghdr *)next;
631 		if (ifm->ifm_type == RTM_IFINFO) {
632 			sdl = (struct sockaddr_dl *)(ifm + 1);
633 			flags = ifm->ifm_flags;
634 			continue;
635 		}
636 		if ((flags & IFF_UP) == 0)
637 			continue;
638 		lflags = IFF_BROADCAST | iff_flag;
639 		if (multicast_mode == PER_INTERFACE_MULTICAST)
640 			lflags |= IFF_MULTICAST;
641 		if ((flags & lflags) == 0)
642 			continue;
643 		if (ifm->ifm_type != RTM_NEWADDR)
644 			quit("out of sync parsing NET_RT_IFLIST");
645 		ifam = (struct ifa_msghdr *)ifm;
646 		info.rti_addrs = ifam->ifam_addrs;
647 		rt_xaddrs((char *)(ifam + 1), ifam->ifam_msglen + (char *)ifam,
648 		    &info);
649 		/* gag, wish we could get rid of Internet dependencies */
650 #define	dstaddr		info.rti_info[RTAX_BRD]
651 #define	ifaddr		info.rti_info[RTAX_IFA]
652 #define	IPADDR_SA(x)	((struct sockaddr_in *)(x))->sin_addr.s_addr
653 #define	PORT_SA(x)	((struct sockaddr_in *)(x))->sin_port
654 		if (dstaddr == 0 || dstaddr->sa_family != AF_INET)
655 			continue;
656 		PORT_SA(dstaddr) = sp->s_port;
657 		for (np = neighbors; np != NULL; np = np->n_next) {
658 			if (memcmp(sdl->sdl_data, np->n_name,
659 			    sdl->sdl_nlen) == 0 &&
660 			    IPADDR_SA(np->n_addr) == IPADDR_SA(dstaddr)) {
661 				break;
662 			}
663 		}
664 		if (np != NULL)
665 			continue;
666 		len = sizeof(*np) + dstaddr->sa_len + sdl->sdl_nlen + 1;
667 		np = malloc(len);
668 		if (np == NULL)
669 			quit("malloc of neighbor structure");
670 		memset(np, 0, len);
671 		np->n_flags = flags;
672 		np->n_addr = (struct sockaddr *)(np + 1);
673 		np->n_addrlen = dstaddr->sa_len;
674 		np->n_name = np->n_addrlen + (char *)np->n_addr;
675 		memcpy((char *)np->n_addr, (char *)dstaddr, np->n_addrlen);
676 		memcpy(np->n_name, sdl->sdl_data, sdl->sdl_nlen);
677 		if (multicast_mode == PER_INTERFACE_MULTICAST &&
678 		    (flags & IFF_MULTICAST) != 0 &&
679 		    (flags & IFF_LOOPBACK) == 0) {
680 			struct ip_mreq mreq;
681 
682 			memcpy((char *)np->n_addr, (char *)ifaddr,
683 			    np->n_addrlen);
684 			mreq.imr_multiaddr.s_addr = htonl(INADDR_WHOD_GROUP);
685 			mreq.imr_interface.s_addr =
686 			    ((struct sockaddr_in *)np->n_addr)->sin_addr.s_addr;
687 			if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
688 			    &mreq, sizeof(mreq)) < 0) {
689 				syslog(LOG_ERR,
690 				    "setsockopt IP_ADD_MEMBERSHIP: %m");
691 #if 0
692 				/* Fall back to broadcast on this if. */
693 				np->n_flags &= ~IFF_MULTICAST;
694 #else
695 				free(np);
696 				continue;
697 #endif
698 			}
699 		}
700 		np->n_next = neighbors;
701 		neighbors = np;
702 	}
703 	free(buf);
704 	return (1);
705 }
706 
707 #ifdef DEBUG
708 void
709 Sendto(int s, const void *buf, size_t cc, int flags, const struct sockaddr *to,
710     int tolen)
711 {
712 	struct whod *w;
713 	struct whoent *we;
714 	struct sockaddr_in *sin;
715 
716 	w = (struct whod *)buf;
717 	sin = (struct sockaddr_in *)to;
718 	printf("sendto %x.%d\n", ntohl(sin->sin_addr.s_addr),
719 	    ntohs(sin->sin_port));
720 	printf("hostname %s %s\n", w->wd_hostname,
721 	    interval(ntohl(w->wd_sendtime) - ntohl(w->wd_boottime), "  up"));
722 	printf("load %4.2f, %4.2f, %4.2f\n",
723 	    ntohl(w->wd_loadav[0]) / 100.0, ntohl(w->wd_loadav[1]) / 100.0,
724 	    ntohl(w->wd_loadav[2]) / 100.0);
725 	cc -= WHDRSIZE;
726 	for (we = w->wd_we, cc /= sizeof(struct whoent); cc > 0; cc--, we++) {
727 		time_t t = _time32_to_time(ntohl(we->we_utmp.out_time));
728 
729 		printf("%-8.8s %s:%s %.12s", we->we_utmp.out_name,
730 		    w->wd_hostname, we->we_utmp.out_line, ctime(&t) + 4);
731 		we->we_idle = ntohl(we->we_idle) / 60;
732 		if (we->we_idle != 0) {
733 			if (we->we_idle >= 100 * 60)
734 				we->we_idle = 100 * 60 - 1;
735 			if (we->we_idle >= 60)
736 				printf(" %2d", we->we_idle / 60);
737 			else
738 				printf("   ");
739 			printf(":%02d", we->we_idle % 60);
740 		}
741 		printf("\n");
742 	}
743 }
744 
745 char *
746 interval(int time, char *updown)
747 {
748 	static char resbuf[32];
749 	int days, hours, minutes;
750 
751 	if (time < 0 || time > 3 * 30 * 24 * 60 * 60) {
752 		(void) sprintf(resbuf, "   %s ??:??", updown);
753 		return (resbuf);
754 	}
755 	minutes = (time + 59) / 60;		/* round to minutes */
756 	hours = minutes / 60;
757 	minutes %= 60;
758 	days = hours / 24;
759 	hours %= 24;
760 	if (days > 0) {
761 		(void) sprintf(resbuf, "%s %2d+%02d:%02d",
762 		    updown, days, hours, minutes);
763 	} else {
764 		(void) sprintf(resbuf, "%s    %2d:%02d",
765 		    updown, hours, minutes);
766 	}
767 	return (resbuf);
768 }
769 #endif
770