xref: /netbsd-src/usr.sbin/arp/arp.c (revision 6cf6fe02a981b55727c49c3d37b0d8191a98c0ee)
1 /*	$NetBSD: arp.c,v 1.51 2013/06/07 17:18:33 christos Exp $ */
2 
3 /*
4  * Copyright (c) 1984, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Sun Microsystems, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include <sys/cdefs.h>
36 #ifndef lint
37 __COPYRIGHT("@(#) Copyright (c) 1984, 1993\
38  The Regents of the University of California.  All rights reserved.");
39 #endif /* not lint */
40 
41 #ifndef lint
42 #if 0
43 static char sccsid[] = "@(#)arp.c	8.3 (Berkeley) 4/28/95";
44 #else
45 __RCSID("$NetBSD: arp.c,v 1.51 2013/06/07 17:18:33 christos Exp $");
46 #endif
47 #endif /* not lint */
48 
49 /*
50  * arp - display, set, and delete arp table entries
51  */
52 
53 #include <sys/param.h>
54 #include <sys/file.h>
55 #include <sys/socket.h>
56 #include <sys/sysctl.h>
57 #include <sys/ioctl.h>
58 
59 #include <net/if.h>
60 #include <net/if_dl.h>
61 #include <net/if_ether.h>
62 #include <net/if_types.h>
63 #include <net/route.h>
64 #include <netinet/in.h>
65 #include <netinet/if_inarp.h>
66 #include <arpa/inet.h>
67 
68 #include <err.h>
69 #include <errno.h>
70 #include <netdb.h>
71 #include <nlist.h>
72 #include <paths.h>
73 #include <stdio.h>
74 #include <stdlib.h>
75 #include <string.h>
76 #include <unistd.h>
77 #include <ifaddrs.h>
78 
79 static int is_llinfo(const struct sockaddr_dl *, int);
80 static int delete(const char *, const char *);
81 static void dump(uint32_t);
82 static void delete_all(void);
83 static void sdl_print(const struct sockaddr_dl *);
84 static int getifname(u_int16_t, char *, size_t);
85 static int atosdl(const char *s, struct sockaddr_dl *sdl);
86 static int file(const char *);
87 static void get(const char *);
88 static int getinetaddr(const char *, struct in_addr *);
89 static void getsocket(void);
90 static int rtmsg(int);
91 static int set(int, char **);
92 static void usage(void) __dead;
93 
94 static pid_t pid;
95 static int aflag, nflag, vflag;
96 static int s = -1;
97 static struct ifaddrs* ifaddrs = NULL;
98 static struct sockaddr_in so_mask = {
99 	.sin_len = 8,
100 	.sin_addr = {
101 		.s_addr = 0xffffffff
102 	}
103 };
104 static struct sockaddr_inarp blank_sin = {
105 	.sin_len = sizeof(blank_sin),
106 	.sin_family = AF_INET
107 };
108 static struct sockaddr_inarp sin_m;
109 static struct sockaddr_dl blank_sdl = {
110 	.sdl_len = sizeof(blank_sdl),
111 	.sdl_family = AF_LINK
112 };
113 static struct sockaddr_dl sdl_m;
114 
115 static int expire_time, flags, export_only, doing_proxy, found_entry;
116 static struct {
117 	struct	rt_msghdr m_rtm;
118 	char	m_space[512];
119 } m_rtmsg;
120 
121 int
122 main(int argc, char **argv)
123 {
124 	int ch;
125 	int op = 0;
126 
127 	setprogname(argv[0]);
128 
129 	pid = getpid();
130 
131 	while ((ch = getopt(argc, argv, "andsfv")) != -1)
132 		switch((char)ch) {
133 		case 'a':
134 			aflag = 1;
135 			break;
136 		case 'd':
137 		case 's':
138 		case 'f':
139 			if (op)
140 				usage();
141 			op = ch;
142 			break;
143 		case 'n':
144 			nflag = 1;
145 			break;
146 		case 'v':
147 			vflag = 1;
148 			break;
149 		default:
150 			usage();
151 		}
152 	argc -= optind;
153 	argv += optind;
154 
155 	if (!op && aflag)
156 		op = 'a';
157 
158 	switch((char)op) {
159 	case 'a':
160 		dump(0);
161 		break;
162 	case 'd':
163 		if (aflag && argc == 0)
164 			delete_all();
165 		else {
166 			if (aflag || argc < 1 || argc > 2)
167 				usage();
168 			(void)delete(argv[0], argv[1]);
169 		}
170 		break;
171 	case 's':
172 		if (argc < 2 || argc > 7)
173 			usage();
174 		return (set(argc, argv) ? 1 : 0);
175 	case 'f':
176 		if (argc != 1)
177 			usage();
178 		return (file(argv[0]));
179 	default:
180 		if (argc != 1)
181 			usage();
182 		get(argv[0]);
183 		break;
184 	}
185 	return (0);
186 }
187 
188 /*
189  * Process a file to set standard arp entries
190  */
191 static int
192 file(const char *name)
193 {
194 	char *line, *argv[5];
195 	int i, retval;
196 	FILE *fp;
197 
198 	if (!strcmp(name, "-")) {
199 		fp = stdin;
200 	} else {
201 		fp = fopen(name, "r");
202 		if (fp == NULL) {
203 			err(1, "Cannot open %s", name);
204 		}
205 	}
206 	retval = 0;
207 	for (; (line = fparseln(fp, NULL, NULL, NULL, 0)) != NULL; free(line)) {
208 		char **ap, *inputstring;
209 
210 		inputstring = line;
211 		for (ap = argv; ap < &argv[sizeof(argv) / sizeof(argv[0])] &&
212 		    (*ap = stresep(&inputstring, " \t", '\\')) != NULL;) {
213 		       if (**ap != '\0')
214 				ap++;
215 		}
216 		i = ap - argv;
217 		if (i < 2) {
218 			warnx("bad line: %s", line);
219 			retval = 1;
220 			continue;
221 		}
222 		if (set(i, argv))
223 			retval = 1;
224 	}
225 	if (fp != stdin)
226 		(void)fclose(fp);
227 	return retval;
228 }
229 
230 static void
231 getsocket(void)
232 {
233 	if (s >= 0)
234 		return;
235 	s = socket(PF_ROUTE, SOCK_RAW, 0);
236 	if (s < 0)
237 		err(1, "socket");
238 }
239 
240 static int
241 getlink(const char *name, struct sockaddr_dl *sdl)
242 {
243 	struct ifaddrs *ifap, *ifa;
244 
245 	if (getifaddrs(&ifap) != 0) {
246 		warn("getifaddrs");
247 		return 0;
248 	}
249 
250 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
251 		if (ifa->ifa_addr->sa_family != AF_LINK)
252 			continue;
253 		if (strcmp(ifa->ifa_name, name) != 0)
254 			continue;
255 		memcpy(sdl, ifa->ifa_addr, sizeof(*sdl));
256 		freeifaddrs(ifap);
257 		return 1;
258 	}
259 	freeifaddrs(ifap);
260 	return 0;
261 }
262 
263 /*
264  * Set an individual arp entry
265  */
266 static int
267 set(int argc, char **argv)
268 {
269 	struct sockaddr_inarp *sina;
270 	struct sockaddr_dl *sdl;
271 	struct rt_msghdr *rtm;
272 	char *host = argv[0], *eaddr;
273 	int rval;
274 
275 	sina = &sin_m;
276 	rtm = &(m_rtmsg.m_rtm);
277 	eaddr = argv[1];
278 
279 	getsocket();
280 	argc -= 2;
281 	argv += 2;
282 	sdl_m = blank_sdl;		/* struct copy */
283 	sin_m = blank_sin;		/* struct copy */
284 	if (getinetaddr(host, &sina->sin_addr) == -1)
285 		return (1);
286 	if (atosdl(eaddr, &sdl_m))
287 		warnx("invalid link-level address '%s'", eaddr);
288 	doing_proxy = flags = export_only = expire_time = 0;
289 	for (; argc-- > 0; argv++) {
290 		if (strncmp(argv[0], "temp", 4) == 0) {
291 			struct timeval timev;
292 			(void)gettimeofday(&timev, 0);
293 			expire_time = timev.tv_sec + 20 * 60;
294 		}
295 		else if (strncmp(argv[0], "pub", 3) == 0) {
296 			flags |= RTF_ANNOUNCE;
297 			doing_proxy = SIN_PROXY;
298 			if (argc && strncmp(argv[1], "pro", 3) == 0) {
299 			        export_only = 1;
300 			        argc--; argv++;
301 			}
302 		} else if (strncmp(argv[0], "trail", 5) == 0) {
303 			warnx("%s: Sending trailers is no longer supported",
304 			    host);
305 		} else if (strcmp(argv[0], "ifscope") == 0) {
306 			if (argc == 0) {
307 				warnx("missing interface for ifscope");
308 				continue;
309 			}
310 			argc--;
311 			argv++;
312 			if (!getlink(argv[0], &sdl_m))
313 				warnx("cannot get link address for %s", argv[0]);
314 		}
315 
316 	}
317 	if (memcmp(&sdl_m, &blank_sdl, sizeof(blank_sdl)))
318 		goto out;
319 tryagain:
320 	if (rtmsg(RTM_GET) < 0) {
321 		warn("%s", host);
322 		return (1);
323 	}
324 	sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
325 	sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
326 	    (char *)(void *)sina);
327 	if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
328 		if (is_llinfo(sdl, rtm->rtm_flags))
329 			goto overwrite;
330 		if (doing_proxy == 0) {
331 			warnx("set: can only proxy for %s", host);
332 			return (1);
333 		}
334 		if (sin_m.sin_other & SIN_PROXY) {
335 			warnx("set: proxy entry exists for non 802 device");
336 			return (1);
337 		}
338 		sin_m.sin_other = SIN_PROXY;
339 		export_only = 1;
340 		goto tryagain;
341 	}
342 overwrite:
343 	if (sdl->sdl_family != AF_LINK) {
344 		warnx("cannot intuit interface index and type for %s",
345 		    host);
346 		return (1);
347 	}
348 	sdl_m.sdl_type = sdl->sdl_type;
349 	sdl_m.sdl_index = sdl->sdl_index;
350 out:
351 	rval = rtmsg(RTM_ADD);
352 	if (vflag)
353 		(void)printf("%s (%s) added\n", host, eaddr);
354 	return (rval);
355 }
356 
357 /*
358  * Display an individual arp entry
359  */
360 static void
361 get(const char *host)
362 {
363 	struct sockaddr_inarp *sina;
364 
365 	sina = &sin_m;
366 	sin_m = blank_sin;		/* struct copy */
367 	if (getinetaddr(host, &sina->sin_addr) == -1)
368 		exit(1);
369 	dump(sina->sin_addr.s_addr);
370 	if (found_entry == 0)
371 		errx(1, "%s (%s) -- no entry", host, inet_ntoa(sina->sin_addr));
372 }
373 
374 
375 static int
376 is_llinfo(const struct sockaddr_dl *sdl, int rtflags)
377 {
378 	if (sdl->sdl_family != AF_LINK ||
379 	    (rtflags & (RTF_LLINFO|RTF_GATEWAY)) != RTF_LLINFO)
380 		return 0;
381 
382 	switch (sdl->sdl_type) {
383 	case IFT_ETHER:
384 	case IFT_FDDI:
385 	case IFT_ISO88023:
386 	case IFT_ISO88024:
387 	case IFT_ISO88025:
388 	case IFT_ARCNET:
389 		return 1;
390 	default:
391 		return 0;
392 	}
393 }
394 
395 /*
396  * Delete an arp entry
397  */
398 int
399 delete(const char *host, const char *info)
400 {
401 	struct sockaddr_inarp *sina;
402 	struct rt_msghdr *rtm;
403 	struct sockaddr_dl *sdl;
404 
405 	sina = &sin_m;
406 	rtm = &m_rtmsg.m_rtm;
407 
408 	getsocket();
409 	sin_m = blank_sin;		/* struct copy */
410 	if (info && strncmp(info, "pro", 3) == 0)
411 		 sina->sin_other = SIN_PROXY;
412 	if (getinetaddr(host, &sina->sin_addr) == -1)
413 		return (1);
414 tryagain:
415 	if (rtmsg(RTM_GET) < 0) {
416 		warn("%s", host);
417 		return (1);
418 	}
419 	sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
420 	sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
421 	    (char *)(void *)sina);
422 	if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr &&
423 	    is_llinfo(sdl, rtm->rtm_flags))
424 		goto delete;
425 	if (sin_m.sin_other & SIN_PROXY) {
426 		warnx("delete: can't locate %s", host);
427 		return (1);
428 	} else {
429 		sin_m.sin_other = SIN_PROXY;
430 		goto tryagain;
431 	}
432 delete:
433 	if (sdl->sdl_family != AF_LINK) {
434 		(void)warnx("cannot locate %s", host);
435 		return (1);
436 	}
437 	if (rtmsg(RTM_DELETE))
438 		return (1);
439 	if (vflag)
440 		(void)printf("%s (%s) deleted\n", host,
441 		    inet_ntoa(sina->sin_addr));
442 	return (0);
443 }
444 
445 /*
446  * Dump the entire arp table
447  */
448 void
449 dump(uint32_t addr)
450 {
451 	int mib[6];
452 	size_t needed;
453 	char ifname[IFNAMSIZ];
454 	char *lim, *buf, *next;
455         const char *host;
456 	struct rt_msghdr *rtm;
457 	struct sockaddr_inarp *sina;
458 	struct sockaddr_dl *sdl;
459 	struct hostent *hp;
460 
461 	mib[0] = CTL_NET;
462 	mib[1] = PF_ROUTE;
463 	mib[2] = 0;
464 	mib[3] = AF_INET;
465 	mib[4] = NET_RT_FLAGS;
466 	mib[5] = RTF_LLINFO;
467 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
468 		err(1, "route-sysctl-estimate");
469 	if (needed == 0)
470 		return;
471 	if ((buf = malloc(needed)) == NULL)
472 		err(1, "malloc");
473 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
474 		err(1, "actual retrieval of routing table");
475 	lim = buf + needed;
476 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
477 		rtm = (struct rt_msghdr *)(void *)next;
478 		sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
479 		sdl = (struct sockaddr_dl *)(void *)
480 		    (RT_ROUNDUP(sina->sin_len) + (char *)(void *)sina);
481 		if (addr) {
482 			if (addr != sina->sin_addr.s_addr)
483 				continue;
484 			found_entry = 1;
485 		}
486 		if (nflag == 0)
487 			hp = gethostbyaddr((const char *)(void *)
488 			    &(sina->sin_addr),
489 			    sizeof sina->sin_addr, AF_INET);
490 		else
491 			hp = NULL;
492 
493 		host = hp ? hp->h_name : "?";
494 
495 		(void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr));
496 		if (sdl->sdl_alen)
497 			sdl_print(sdl);
498 		else
499 			(void)printf("(incomplete)");
500 
501 		if (sdl->sdl_index) {
502 			if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0)
503 				(void)printf(" on %s", ifname);
504 		}
505 
506 		if (rtm->rtm_rmx.rmx_expire == 0)
507 			(void)printf(" permanent");
508 		if (sina->sin_other & SIN_PROXY)
509 			(void)printf(" published (proxy only)");
510 		if (rtm->rtm_addrs & RTA_NETMASK) {
511 			sina = (struct sockaddr_inarp *)(void *)
512 			    (RT_ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl);
513 			if (sina->sin_addr.s_addr == 0xffffffff)
514 				(void)printf(" published");
515 			if (sina->sin_len != 8)
516 				(void)printf("(weird)");
517 		}
518 		(void)printf("\n");
519 	}
520 	free(buf);
521 }
522 
523 /*
524  * Delete the entire arp table
525  */
526 void
527 delete_all(void)
528 {
529 	int mib[6];
530 	size_t needed;
531 	char addr[sizeof("000.000.000.000\0")];
532 	char *lim, *buf, *next;
533 	struct rt_msghdr *rtm;
534 	struct sockaddr_inarp *sina;
535 
536 	mib[0] = CTL_NET;
537 	mib[1] = PF_ROUTE;
538 	mib[2] = 0;
539 	mib[3] = AF_INET;
540 	mib[4] = NET_RT_FLAGS;
541 	mib[5] = RTF_LLINFO;
542 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
543 		err(1, "route-sysctl-estimate");
544 	if (needed == 0)
545 		return;
546 	if ((buf = malloc(needed)) == NULL)
547 		err(1, "malloc");
548 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
549 		err(1, "actual retrieval of routing table");
550 	lim = buf + needed;
551 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
552 		rtm = (struct rt_msghdr *)(void *)next;
553 		sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
554 		(void)snprintf(addr, sizeof(addr), "%s",
555 		    inet_ntoa(sina->sin_addr));
556 		(void)delete(addr, NULL);
557 	}
558 	free(buf);
559 }
560 
561 void
562 sdl_print(const struct sockaddr_dl *sdl)
563 {
564 	char hbuf[NI_MAXHOST];
565 
566 	if (getnameinfo((const struct sockaddr *)(const void *)sdl,
567 	    (socklen_t)sdl->sdl_len,
568 	    hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
569 		(void)printf("<invalid>");
570 	else
571 		(void)printf("%s", hbuf);
572 }
573 
574 static int
575 atosdl(const char *ss, struct sockaddr_dl *sdl)
576 {
577 	int i;
578 	unsigned long b;
579 	char *endp;
580 	char *p;
581 	char *t, *r;
582 
583 	p = LLADDR(sdl);
584 	endp = ((char *)(void *)sdl) + sdl->sdl_len;
585 	i = 0;
586 
587 	b = strtoul(ss, &t, 16);
588 	if (b > 255 || t == ss)
589 		return 1;
590 
591 	*p++ = (char)b;
592 	++i;
593 	while ((p < endp) && (*t++ == ':')) {
594 		b = strtoul(t, &r, 16);
595 		if (b > 255 || r == t)
596 			break;
597 		*p++ = (char)b;
598 		++i;
599 		t = r;
600 	}
601 	sdl->sdl_alen = i;
602 
603 	return 0;
604 }
605 
606 static void
607 usage(void)
608 {
609 	const char *progname;
610 
611 	progname = getprogname();
612 	(void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname);
613 	(void)fprintf(stderr, "	      %s [-nv] -a\n", progname);
614 	(void)fprintf(stderr, "	      %s [-v] -d [-a|hostname [pub [proxy]]]\n",
615 	    progname);
616 	(void)fprintf(stderr, "       %s -s hostname ether_addr [temp] [pub [proxy]]\n",
617 	    progname);
618 	(void)fprintf(stderr, "       %s -f filename\n", progname);
619 	exit(1);
620 }
621 
622 static int
623 rtmsg(int cmd)
624 {
625 	static int seq;
626 	struct rt_msghdr *rtm;
627 	char *cp;
628 	int l;
629 
630 	rtm = &m_rtmsg.m_rtm;
631 	cp = m_rtmsg.m_space;
632 	errno = 0;
633 
634 	if (cmd == RTM_DELETE)
635 		goto doit;
636 	(void)memset(&m_rtmsg, 0, sizeof(m_rtmsg));
637 	rtm->rtm_flags = flags;
638 	rtm->rtm_version = RTM_VERSION;
639 
640 	switch (cmd) {
641 	default:
642 		errx(1, "internal wrong cmd");
643 		/*NOTREACHED*/
644 	case RTM_ADD:
645 		rtm->rtm_addrs |= RTA_GATEWAY;
646 		rtm->rtm_rmx.rmx_expire = expire_time;
647 		rtm->rtm_inits = RTV_EXPIRE;
648 		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
649 		sin_m.sin_other = 0;
650 		if (doing_proxy) {
651 			if (export_only)
652 				sin_m.sin_other = SIN_PROXY;
653 			else {
654 				rtm->rtm_addrs |= RTA_NETMASK;
655 				rtm->rtm_flags &= ~RTF_HOST;
656 			}
657 		}
658 		/* FALLTHROUGH */
659 	case RTM_GET:
660 		rtm->rtm_addrs |= RTA_DST;
661 	}
662 
663 #define NEXTADDR(w, s) \
664 	if (rtm->rtm_addrs & (w)) { \
665 		(void)memcpy(cp, &s, \
666 		(size_t)((struct sockaddr *)(void *)&s)->sa_len); \
667 		RT_ADVANCE(cp, ((struct sockaddr *)(void *)&s)); \
668 	}
669 
670 	NEXTADDR(RTA_DST, sin_m);
671 	NEXTADDR(RTA_GATEWAY, sdl_m);
672 	NEXTADDR(RTA_NETMASK, so_mask);
673 
674 	rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg;
675 doit:
676 	l = rtm->rtm_msglen;
677 	rtm->rtm_seq = ++seq;
678 	rtm->rtm_type = cmd;
679 	if (write(s, &m_rtmsg, (size_t)l) < 0) {
680 		if (errno != ESRCH || cmd != RTM_DELETE) {
681 			warn("writing to routing socket");
682 			return (-1);
683 		}
684 	}
685 	do {
686 		l = read(s, &m_rtmsg, sizeof(m_rtmsg));
687 	} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
688 	if (l < 0)
689 		warn("read from routing socket");
690 	return (0);
691 }
692 
693 static int
694 getinetaddr(const char *host, struct in_addr *inap)
695 {
696 	struct hostent *hp;
697 
698 	if (inet_aton(host, inap) == 1)
699 		return (0);
700 	if ((hp = gethostbyname(host)) == NULL) {
701 		warnx("%s: %s", host, hstrerror(h_errno));
702 		return (-1);
703 	}
704 	(void)memcpy(inap, hp->h_addr, sizeof(*inap));
705 	return (0);
706 }
707 
708 static int
709 getifname(u_int16_t ifindex, char *ifname, size_t l)
710 {
711 	int i;
712 	struct ifaddrs *addr;
713 	const struct sockaddr_dl *sdl = NULL;
714 
715 	if (ifaddrs == NULL) {
716 		i = getifaddrs(&ifaddrs);
717 		if (i != 0)
718 			err(1, "getifaddrs");
719 	}
720 
721 	for (addr = ifaddrs; addr; addr = addr->ifa_next) {
722 		if (addr->ifa_addr == NULL ||
723 		    addr->ifa_addr->sa_family != AF_LINK)
724 			continue;
725 
726 		sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr;
727 		if (sdl && sdl->sdl_index == ifindex) {
728 			(void) strlcpy(ifname, addr->ifa_name, l);
729 			return 0;
730 		}
731 	}
732 
733 	return -1;
734 }
735