1 /**	$MirOS: src/usr.sbin/arp/arp.c,v 1.4 2005/04/26 21:06:01 tg Exp $ */
2 /*	$OpenBSD: arp.c,v 1.36 2005/04/04 16:14:45 deraadt Exp $ */
3 /*	$NetBSD: arp.c,v 1.12 1995/04/24 13:25:18 cgd Exp $ */
4 
5 /*
6  * Copyright (c) 1984, 1993
7  *	The Regents of the University of California.  All rights reserved.
8  *
9  * This code is derived from software contributed to Berkeley by
10  * Sun Microsystems, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 /*
38  * arp - display, set, and delete arp table entries
39  */
40 
41 #include <sys/param.h>
42 #include <sys/file.h>
43 #include <sys/socket.h>
44 #include <sys/sysctl.h>
45 
46 #include <net/if.h>
47 #include <net/if_dl.h>
48 #include <net/if_types.h>
49 #include <net/route.h>
50 #include <netinet/in.h>
51 #include <netinet/if_ether.h>
52 #include <arpa/inet.h>
53 
54 #include <netdb.h>
55 #include <errno.h>
56 #include <err.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <paths.h>
61 #include <unistd.h>
62 
63 __RCSID("$MirOS: src/usr.sbin/arp/arp.c,v 1.4 2005/04/26 21:06:01 tg Exp $");
64 
65 int delete(const char *, const char *);
66 void search(in_addr_t addr, void (*action)(struct sockaddr_dl *sdl,
67 	struct sockaddr_inarp *sin, struct rt_msghdr *rtm));
68 void print_entry(struct sockaddr_dl *sdl,
69 	struct sockaddr_inarp *sin, struct rt_msghdr *rtm);
70 void nuke_entry(struct sockaddr_dl *sdl,
71 	struct sockaddr_inarp *sin, struct rt_msghdr *rtm);
72 void ether_print(const char *);
73 int file(char *);
74 int get(const char *);
75 int getinetaddr(const char *, struct in_addr *);
76 void getsocket(void);
77 int rtmsg(int);
78 int set(int, char **);
79 void usage(void);
80 
81 static pid_t pid;
82 static int replace;	/* replace entries when adding */
83 static int nflag;	/* no reverse dns lookups */
84 static int aflag;	/* do it for all entries */
85 static int s = -1;
86 
87 extern int h_errno;
88 
89 /* ROUNDUP() is nasty, but it is identical to what's in the kernel. */
90 #define ROUNDUP(a)					\
91 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
92 
93 /* which function we're supposed to do */
94 #define F_GET		1
95 #define F_SET		2
96 #define F_FILESET	3
97 #define F_DELETE	4
98 
99 int
main(int argc,char * argv[])100 main(int argc, char *argv[])
101 {
102 	int	ch, func = 0, rtn;
103 
104 	pid = getpid();
105 	opterr = 0;
106 	while ((ch = getopt(argc, argv, "andSsFf")) != -1) {
107 		switch (ch) {
108 		case 'a':
109 			aflag = 1;
110 			break;
111 		case 'n':
112 			nflag = 1;
113 			break;
114 		case 'd':
115 			if (func)
116 				usage();
117 			func = F_DELETE;
118 			break;
119 		case 's':
120 			if (func)
121 				usage();
122 			func = F_SET;
123 			break;
124 		case 'F':
125 			replace = 1;
126 			break;
127 		case 'f':
128 			if (func)
129 				usage();
130 			func = F_FILESET;
131 			break;
132 		default:
133 			usage();
134 			break;
135 		}
136 	}
137 	argc -= optind;
138 	argv += optind;
139 
140 	if (!func)
141 		func = F_GET;
142 	rtn = 0;
143 
144 	switch (func) {
145 	case F_GET:
146 		if (aflag && argc == 0)
147 			search(0, print_entry);
148 		else if (!aflag && argc == 1)
149 			rtn = get(argv[0]);
150 		else
151 			usage();
152 		break;
153 	case F_SET:
154 		if (argc < 2 || argc > 5)
155 			usage();
156 		if (replace)
157 			delete(argv[0], NULL);
158 		rtn = set(argc, argv) ? 1 : 0;
159 		break;
160 	case F_DELETE:
161 		if (aflag && argc == 0)
162 			search(0, nuke_entry);
163 		else if (!aflag && argc == 1)
164 			rtn = delete(argv[0], argv[1]);
165 		else
166 			usage();
167 		break;
168 	case F_FILESET:
169 		if (argc != 1)
170 			usage();
171 		rtn = file(argv[0]);
172 		break;
173 	}
174 	return (rtn);
175 }
176 
177 /*
178  * Process a file to set standard arp entries
179  */
180 int
file(char * name)181 file(char *name)
182 {
183 	char	 line[100], arg[5][50], *args[5];
184 	int	 i, retval;
185 	FILE	*fp;
186 
187 	if ((fp = fopen(name, "r")) == NULL)
188 		err(1, "cannot open %s", name);
189 	args[0] = &arg[0][0];
190 	args[1] = &arg[1][0];
191 	args[2] = &arg[2][0];
192 	args[3] = &arg[3][0];
193 	args[4] = &arg[4][0];
194 	retval = 0;
195 	while (fgets(line, 100, fp) != NULL) {
196 		if ((line[0] == '#') || (line[0] == '\n'))
197 			continue;
198 		i = sscanf(line, "%49s %49s %49s %49s %49s", arg[0], arg[1],
199 		    arg[2], arg[3], arg[4]);
200 		if (i < 2) {
201 			warnx("bad line: %s", line);
202 			retval = 1;
203 			continue;
204 		}
205 		if (replace)
206 			delete(arg[0], NULL);
207 		if (set(i, args))
208 			retval = 1;
209 	}
210 	fclose(fp);
211 	return (retval);
212 }
213 
214 void
getsocket(void)215 getsocket(void)
216 {
217 	if (s >= 0)
218 		return;
219 	s = socket(PF_ROUTE, SOCK_RAW, 0);
220 	if (s < 0)
221 		err(1, "socket");
222 }
223 
224 struct sockaddr_in	so_mask = { 8, 0, 0, { 0xffffffff } };
225 struct sockaddr_inarp	blank_sin = { sizeof(blank_sin), AF_INET }, sin_m;
226 struct sockaddr_dl	blank_sdl = { sizeof(blank_sdl), AF_LINK }, sdl_m;
227 int			expire_time, flags, export_only, doing_proxy,
228 			    found_entry;
229 struct	{
230 	struct rt_msghdr	m_rtm;
231 	char			m_space[512];
232 }	m_rtmsg;
233 
234 /*
235  * Set an individual arp entry
236  */
237 int
set(int argc,char * argv[])238 set(int argc, char *argv[])
239 {
240 	struct sockaddr_inarp *sin;
241 	struct sockaddr_dl *sdl;
242 	struct rt_msghdr *rtm;
243 	char *eaddr = argv[1], *host = argv[0];
244 	struct ether_addr *ea;
245 
246 	sin = &sin_m;
247 	rtm = &(m_rtmsg.m_rtm);
248 
249 	getsocket();
250 	argc -= 2;
251 	argv += 2;
252 	sdl_m = blank_sdl;		/* struct copy */
253 	sin_m = blank_sin;		/* struct copy */
254 	if (getinetaddr(host, &sin->sin_addr) == -1)
255 		return (1);
256 	ea = ether_aton(eaddr);
257 	if (ea == NULL)
258 		errx(1, "invalid ethernet address: %s", eaddr);
259 	memcpy(LLADDR(&sdl_m), ea, sizeof(*ea));
260 	sdl_m.sdl_alen = 6;
261 	doing_proxy = flags = export_only = expire_time = 0;
262 	while (argc-- > 0) {
263 		if (strncmp(argv[0], "temp", 4) == 0) {
264 			struct timeval time;
265 
266 			gettimeofday(&time, 0);
267 			expire_time = time.tv_sec + 20 * 60;
268 			if (flags & RTF_PERMANENT_ARP) {
269 				/* temp or permanent, not both */
270 				usage();
271 				return (0);
272 			}
273 		} else if (strncmp(argv[0], "pub", 3) == 0) {
274 			flags |= RTF_ANNOUNCE;
275 			doing_proxy = SIN_PROXY;
276 		} else if (strncmp(argv[0], "permanent", 9) == 0) {
277 			flags |= RTF_PERMANENT_ARP;
278 			if (expire_time != 0) {
279 				/* temp or permanent, not both */
280 				usage();
281 				return (0);
282 			}
283 		} else if (strncmp(argv[0], "trail", 5) == 0)
284 			printf("%s: Sending trailers is no longer supported\n",
285 			    host);
286 
287 		argv++;
288 	}
289 
290 tryagain:
291 	if (rtmsg(RTM_GET) < 0) {
292 		warn("%s", host);
293 		return (1);
294 	}
295 	sin = (struct sockaddr_inarp *)(rtm + 1);
296 	sdl = (struct sockaddr_dl *)(ROUNDUP(sin->sin_len) + (char *)sin);
297 	if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
298 		if (sdl->sdl_family == AF_LINK &&
299 		    (rtm->rtm_flags & RTF_LLINFO) &&
300 		    !(rtm->rtm_flags & RTF_GATEWAY))
301 			switch (sdl->sdl_type) {
302 			case IFT_ETHER:
303 			case IFT_FDDI:
304 			case IFT_ISO88023:
305 			case IFT_ISO88024:
306 			case IFT_ISO88025:
307 #ifdef IFT_CARP
308 			case IFT_CARP:
309 #endif
310 				goto overwrite;
311 			}
312 
313 		if (doing_proxy == 0) {
314 			printf("set: can only proxy for %s\n", host);
315 			return (1);
316 		}
317 		if (sin_m.sin_other & SIN_PROXY) {
318 			printf("set: proxy entry exists for non 802 device\n");
319 			return (1);
320 		}
321 		sin_m.sin_other = SIN_PROXY;
322 		export_only = 1;
323 		goto tryagain;
324 	}
325 
326 overwrite:
327 	if (sdl->sdl_family != AF_LINK) {
328 		printf("cannot intuit interface index and type for %s\n", host);
329 		return (1);
330 	}
331 	sdl_m.sdl_type = sdl->sdl_type;
332 	sdl_m.sdl_index = sdl->sdl_index;
333 	return (rtmsg(RTM_ADD));
334 }
335 
336 /*
337  * Display an individual arp entry
338  */
339 int
get(const char * host)340 get(const char *host)
341 {
342 	struct sockaddr_inarp *sin;
343 
344 	sin = &sin_m;
345 	sin_m = blank_sin;		/* struct copy */
346 	if (getinetaddr(host, &sin->sin_addr) == -1)
347 		exit(1);
348 	search(sin->sin_addr.s_addr, print_entry);
349 	if (found_entry == 0) {
350 		printf("%s (%s) -- no entry\n", host, inet_ntoa(sin->sin_addr));
351 		return (1);
352 	}
353 	return (0);
354 }
355 
356 /*
357  * Delete an arp entry
358  */
359 int
delete(const char * host,const char * info)360 delete(const char *host, const char *info)
361 {
362 	struct sockaddr_inarp *sin;
363 	struct rt_msghdr *rtm;
364 	struct sockaddr_dl *sdl;
365 
366 	sin = &sin_m;
367 	rtm = &m_rtmsg.m_rtm;
368 
369 	if (info && strncmp(info, "pro", 3) )
370 		export_only = 1;
371 	getsocket();
372 	sin_m = blank_sin;		/* struct copy */
373 	if (getinetaddr(host, &sin->sin_addr) == -1)
374 		return (1);
375 tryagain:
376 	if (rtmsg(RTM_GET) < 0) {
377 		warn("%s", host);
378 		return (1);
379 	}
380 	sin = (struct sockaddr_inarp *)(rtm + 1);
381 	sdl = (struct sockaddr_dl *)(ROUNDUP(sin->sin_len) + (char *)sin);
382 	if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr)
383 		if (sdl->sdl_family == AF_LINK &&
384 		    (rtm->rtm_flags & RTF_LLINFO) &&
385 		    !(rtm->rtm_flags & RTF_GATEWAY))
386 			switch (sdl->sdl_type) {
387 			case IFT_ETHER:
388 			case IFT_FDDI:
389 			case IFT_ISO88023:
390 			case IFT_ISO88024:
391 			case IFT_ISO88025:
392 #ifdef IFT_CARP
393 			case IFT_CARP:
394 #endif
395 				goto delete;
396 			}
397 
398 	if (sin_m.sin_other & SIN_PROXY) {
399 		warnx("delete: can't locate %s", host);
400 		return (1);
401 	} else {
402 		sin_m.sin_other = SIN_PROXY;
403 		goto tryagain;
404 	}
405 delete:
406 	if (sdl->sdl_family != AF_LINK) {
407 		printf("cannot locate %s\n", host);
408 		return (1);
409 	}
410 	if (rtmsg(RTM_DELETE))
411 		return (1);
412 	printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr));
413 	return (0);
414 }
415 
416 /*
417  * Search the entire arp table, and do some action on matching entries.
418  */
419 void
search(in_addr_t addr,void (* action)(struct sockaddr_dl * sdl,struct sockaddr_inarp * sin,struct rt_msghdr * rtm))420 search(in_addr_t addr, void (*action)(struct sockaddr_dl *sdl,
421     struct sockaddr_inarp *sin, struct rt_msghdr *rtm))
422 {
423 	int mib[6];
424 	size_t needed;
425 	char *lim, *buf, *next;
426 	struct rt_msghdr *rtm;
427 	struct sockaddr_inarp *sin;
428 	struct sockaddr_dl *sdl;
429 
430 	mib[0] = CTL_NET;
431 	mib[1] = PF_ROUTE;
432 	mib[2] = 0;
433 	mib[3] = AF_INET;
434 	mib[4] = NET_RT_FLAGS;
435 	mib[5] = RTF_LLINFO;
436 	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
437 		err(1, "route-sysctl-estimate");
438 	if (needed == 0)
439 		return;
440 	if ((buf = malloc(needed)) == NULL)
441 		err(1, "malloc");
442 	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
443 		err(1, "actual retrieval of routing table");
444 	lim = buf + needed;
445 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
446 		rtm = (struct rt_msghdr *)next;
447 		sin = (struct sockaddr_inarp *)(rtm + 1);
448 		sdl = (struct sockaddr_dl *)(sin + 1);
449 		if (addr) {
450 			if (addr != sin->sin_addr.s_addr)
451 				continue;
452 			found_entry = 1;
453 		}
454 		(*action)(sdl, sin, rtm);
455 	}
456 	free(buf);
457 }
458 
459 /*
460  * Display an arp entry
461  */
462 void
print_entry(struct sockaddr_dl * sdl,struct sockaddr_inarp * sin,struct rt_msghdr * rtm)463 print_entry(struct sockaddr_dl *sdl, struct sockaddr_inarp *sin,
464     struct rt_msghdr *rtm)
465 {
466 	char ifname[IFNAMSIZ], *host;
467 	struct hostent *hp;
468 
469 	if (nflag == 0)
470 		hp = gethostbyaddr((caddr_t)&(sin->sin_addr),
471 		    sizeof(sin->sin_addr), AF_INET);
472 	else
473 		hp = 0;
474 	if (hp)
475 		host = hp->h_name;
476 	else {
477 		host = "?";
478 		if (h_errno == TRY_AGAIN)
479 			nflag = 1;
480 	}
481 	printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr));
482 	if (sdl->sdl_alen)
483 		ether_print(LLADDR(sdl));
484 	else
485 		printf("(incomplete)");
486 	if (if_indextoname(sdl->sdl_index, ifname) != NULL)
487 		printf(" on %s", ifname);
488 	if (rtm->rtm_flags & RTF_PERMANENT_ARP)
489 		printf(" permanent");
490 	if (rtm->rtm_rmx.rmx_expire == 0)
491 		printf(" static");
492 	if (sin->sin_other & SIN_PROXY)
493 		printf(" published (proxy only)");
494 	if (rtm->rtm_addrs & RTA_NETMASK) {
495 		sin = (struct sockaddr_inarp *)
496 		    (ROUNDUP(sdl->sdl_len) + (char *)sdl);
497 		if (sin->sin_addr.s_addr == 0xffffffff)
498 			printf(" published");
499 		if (sin->sin_len != 8)
500 			printf("(weird %d)", sin->sin_len);
501 	}
502 	printf("\n");
503 }
504 
505 /*
506  * Nuke an arp entry
507  */
508 void
nuke_entry(struct sockaddr_dl * sdl,struct sockaddr_inarp * sin,struct rt_msghdr * rtm)509 nuke_entry(struct sockaddr_dl *sdl, struct sockaddr_inarp *sin,
510     struct rt_msghdr *rtm)
511 {
512 	char ip[20];
513 
514 	strlcpy(ip, inet_ntoa(sin->sin_addr), sizeof(ip));
515 	delete(ip, NULL);
516 }
517 
518 void
ether_print(const char * scp)519 ether_print(const char *scp)
520 {
521 	const u_char *cp = (u_char *)scp;
522 
523 	printf("%02x:%02x:%02x:%02x:%02x:%02x",
524 	    cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
525 }
526 
527 void
usage(void)528 usage(void)
529 {
530 	fprintf(stderr, "usage: arp [-n] hostname\n");
531 	fprintf(stderr, "usage: arp [-n] -a\n");
532 	fprintf(stderr, "usage: arp -d hostname\n");
533 	fprintf(stderr, "usage: arp -d -a\n");
534 	fprintf(stderr, "usage: arp [-F] -s hostname ether_addr "
535 	    "[temp | permanent] [pub]\n");
536 	fprintf(stderr, "usage: arp [-F] -f filename\n");
537 	exit(1);
538 }
539 
540 int
rtmsg(int cmd)541 rtmsg(int cmd)
542 {
543 	static int seq;
544 	struct rt_msghdr *rtm;
545 	char *cp;
546 	int l;
547 
548 	rtm = &m_rtmsg.m_rtm;
549 	cp = m_rtmsg.m_space;
550 	errno = 0;
551 
552 	if (cmd == RTM_DELETE)
553 		goto doit;
554 	memset(&m_rtmsg, 0, sizeof(m_rtmsg));
555 	rtm->rtm_flags = flags;
556 	rtm->rtm_version = RTM_VERSION;
557 
558 	switch (cmd) {
559 	default:
560 		errx(1, "internal wrong cmd");
561 		/*NOTREACHED*/
562 	case RTM_ADD:
563 		rtm->rtm_addrs |= RTA_GATEWAY;
564 		rtm->rtm_rmx.rmx_expire = expire_time;
565 		rtm->rtm_inits = RTV_EXPIRE;
566 		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
567 		sin_m.sin_other = 0;
568 		if (doing_proxy) {
569 			if (export_only)
570 				sin_m.sin_other = SIN_PROXY;
571 			else {
572 				rtm->rtm_addrs |= RTA_NETMASK;
573 				rtm->rtm_flags &= ~RTF_HOST;
574 			}
575 		}
576 		/* FALLTHROUGH */
577 	case RTM_GET:
578 		rtm->rtm_addrs |= RTA_DST;
579 	}
580 
581 #define NEXTADDR(w, s)					\
582 	if (rtm->rtm_addrs & (w)) {			\
583 		memcpy(cp, &s, sizeof(s));		\
584 		cp += ROUNDUP(sizeof(s));		\
585 	}
586 
587 	NEXTADDR(RTA_DST, sin_m);
588 	NEXTADDR(RTA_GATEWAY, sdl_m);
589 	NEXTADDR(RTA_NETMASK, so_mask);
590 
591 	rtm->rtm_msglen = cp - (char *)&m_rtmsg;
592 doit:
593 	l = rtm->rtm_msglen;
594 	rtm->rtm_seq = ++seq;
595 	rtm->rtm_type = cmd;
596 	if (write(s, (char *)&m_rtmsg, l) < 0)
597 		if (errno != ESRCH || cmd != RTM_DELETE) {
598 			warn("writing to routing socket");
599 			return (-1);
600 		}
601 
602 	do {
603 		l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
604 	} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
605 
606 	if (l < 0)
607 		warn("read from routing socket");
608 	return (0);
609 }
610 
611 int
getinetaddr(const char * host,struct in_addr * inap)612 getinetaddr(const char *host, struct in_addr *inap)
613 {
614 	struct hostent *hp;
615 
616 	if (inet_aton(host, inap) == 1)
617 		return (0);
618 	if ((hp = gethostbyname(host)) == NULL) {
619 		warnx("%s: %s", host, hstrerror(h_errno));
620 		return (-1);
621 	}
622 	memcpy(inap, hp->h_addr, sizeof(*inap));
623 	return (0);
624 }
625