arp.c revision 9874 
1/*
2 * Copyright (c) 1984, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Sun Microsystems, Inc.
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. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. 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#ifndef lint
38static char copyright[] =
39"@(#) Copyright (c) 1984, 1993\n\
40	The Regents of the University of California.  All rights reserved.\n";
41#endif /* not lint */
42
43#ifndef lint
44static char sccsid[] = "@(#)arp.c	8.2 (Berkeley) 1/2/94";
45#endif /* not lint */
46
47/*
48 * arp - display, set, and delete arp table entries
49 */
50
51
52#include <sys/param.h>
53#include <sys/file.h>
54#include <sys/socket.h>
55#include <sys/sysctl.h>
56
57#include <net/if.h>
58#include <net/if_dl.h>
59#include <net/if_types.h>
60#include <net/route.h>
61
62#include <netinet/in.h>
63#include <netinet/if_ether.h>
64
65#include <arpa/inet.h>
66
67#include <netdb.h>
68#include <errno.h>
69#include <nlist.h>
70#include <stdio.h>
71#include <paths.h>
72
73extern int errno;
74static int pid;
75static int kflag;
76static int nflag;
77static int s = -1;
78
79main(argc, argv)
80	int argc;
81	char **argv;
82{
83	int ch;
84
85	pid = getpid();
86	while ((ch = getopt(argc, argv, "andfs")) != EOF)
87		switch((char)ch) {
88		case 'a':
89			dump(0);
90			exit(0);
91		case 'd':
92			if (argc < 3 || argc > 4)
93				usage();
94			delete(argv[2], argv[3]);
95			exit(0);
96		case 'n':
97			nflag = 1;
98			continue;
99		case 's':
100			if (argc < 4 || argc > 7)
101				usage();
102			exit(set(argc-2, &argv[2]) ? 1 : 0);
103		case 'f' :
104			if (argc != 3)
105				usage();
106			file(argv[2]);
107			exit(0);
108		case '?':
109		default:
110			usage();
111		}
112	if (argc != 2)
113		usage();
114	get(argv[1]);
115	exit(0);
116}
117
118/*
119 * Process a file to set standard arp entries
120 */
121file(name)
122	char *name;
123{
124	FILE *fp;
125	int i, retval;
126	char line[100], arg[5][50], *args[5];
127
128	if ((fp = fopen(name, "r")) == NULL) {
129		fprintf(stderr, "arp: cannot open %s\n", name);
130		exit(1);
131	}
132	args[0] = &arg[0][0];
133	args[1] = &arg[1][0];
134	args[2] = &arg[2][0];
135	args[3] = &arg[3][0];
136	args[4] = &arg[4][0];
137	retval = 0;
138	while(fgets(line, 100, fp) != NULL) {
139		i = sscanf(line, "%s %s %s %s %s", arg[0], arg[1], arg[2],
140		    arg[3], arg[4]);
141		if (i < 2) {
142			fprintf(stderr, "arp: bad line: %s\n", line);
143			retval = 1;
144			continue;
145		}
146		if (set(i, args))
147			retval = 1;
148	}
149	fclose(fp);
150	return (retval);
151}
152
153getsocket() {
154	if (s < 0) {
155		s = socket(PF_ROUTE, SOCK_RAW, 0);
156		if (s < 0) {
157			perror("arp: socket");
158			exit(1);
159		}
160	}
161}
162
163struct	sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}};
164struct	sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m;
165struct	sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m;
166int	expire_time, flags, export_only, doing_proxy, found_entry;
167struct	{
168	struct	rt_msghdr m_rtm;
169	char	m_space[512];
170}	m_rtmsg;
171
172/*
173 * Set an individual arp entry
174 */
175set(argc, argv)
176	int argc;
177	char **argv;
178{
179	struct hostent *hp;
180	register struct sockaddr_inarp *sin = &sin_m;
181	register struct sockaddr_dl *sdl;
182	register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
183	u_char *ea;
184	char *host = argv[0], *eaddr = argv[1];
185
186	getsocket();
187	argc -= 2;
188	argv += 2;
189	sdl_m = blank_sdl;
190	sin_m = blank_sin;
191	sin->sin_addr.s_addr = inet_addr(host);
192	if (sin->sin_addr.s_addr == -1) {
193		if (!(hp = gethostbyname(host))) {
194			fprintf(stderr, "arp: %s: ", host);
195			herror((char *)NULL);
196			return (1);
197		}
198		bcopy((char *)hp->h_addr, (char *)&sin->sin_addr,
199		    sizeof sin->sin_addr);
200	}
201	ea = (u_char *)LLADDR(&sdl_m);
202	if (ether_aton(eaddr, ea) == 0)
203		sdl_m.sdl_alen = 6;
204	doing_proxy = flags = export_only = expire_time = 0;
205	while (argc-- > 0) {
206		if (strncmp(argv[0], "temp", 4) == 0) {
207			struct timeval time;
208			gettimeofday(&time, 0);
209			expire_time = time.tv_sec + 20 * 60;
210		}
211		else if (strncmp(argv[0], "pub", 3) == 0) {
212			flags |= RTF_ANNOUNCE;
213			doing_proxy = SIN_PROXY;
214		} else if (strncmp(argv[0], "trail", 5) == 0) {
215			printf("%s: Sending trailers is no longer supported\n",
216				host);
217		}
218		argv++;
219	}
220tryagain:
221	if (rtmsg(RTM_GET) < 0) {
222		perror(host);
223		return (1);
224	}
225	sin = (struct sockaddr_inarp *)(rtm + 1);
226	sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin);
227	if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
228		if (sdl->sdl_family == AF_LINK &&
229		    (rtm->rtm_flags & RTF_LLINFO) &&
230		    !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
231		case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
232		case IFT_ISO88024: case IFT_ISO88025:
233			goto overwrite;
234		}
235		if (doing_proxy == 0) {
236			printf("set: can only proxy for %s\n", host);
237			return (1);
238		}
239		if (sin_m.sin_other & SIN_PROXY) {
240			printf("set: proxy entry exists for non 802 device\n");
241			return(1);
242		}
243		sin_m.sin_other = SIN_PROXY;
244		export_only = 1;
245		goto tryagain;
246	}
247overwrite:
248	if (sdl->sdl_family != AF_LINK) {
249		printf("cannot intuit interface index and type for %s\n", host);
250		return (1);
251	}
252	sdl_m.sdl_type = sdl->sdl_type;
253	sdl_m.sdl_index = sdl->sdl_index;
254	return (rtmsg(RTM_ADD));
255}
256
257/*
258 * Display an individual arp entry
259 */
260get(host)
261	char *host;
262{
263	struct hostent *hp;
264	struct sockaddr_inarp *sin = &sin_m;
265	u_char *ea;
266
267	sin_m = blank_sin;
268	sin->sin_addr.s_addr = inet_addr(host);
269	if (sin->sin_addr.s_addr == -1) {
270		if (!(hp = gethostbyname(host))) {
271			fprintf(stderr, "arp: %s: ", host);
272			herror((char *)NULL);
273			exit(1);
274		}
275		bcopy((char *)hp->h_addr, (char *)&sin->sin_addr,
276		    sizeof sin->sin_addr);
277	}
278	dump(sin->sin_addr.s_addr);
279	if (found_entry == 0) {
280		printf("%s (%s) -- no entry\n",
281		    host, inet_ntoa(sin->sin_addr));
282		exit(1);
283	}
284}
285
286/*
287 * Delete an arp entry
288 */
289delete(host, info)
290	char *host;
291	char *info;
292{
293	struct hostent *hp;
294	register struct sockaddr_inarp *sin = &sin_m;
295	register struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
296	struct sockaddr_dl *sdl;
297	u_char *ea;
298	char *eaddr;
299
300	if (info && strncmp(info, "pro", 3) )
301		export_only = 1;
302	getsocket();
303	sin_m = blank_sin;
304	sin->sin_addr.s_addr = inet_addr(host);
305	if (sin->sin_addr.s_addr == -1) {
306		if (!(hp = gethostbyname(host))) {
307			fprintf(stderr, "arp: %s: ", host);
308			herror((char *)NULL);
309			return (1);
310		}
311		bcopy((char *)hp->h_addr, (char *)&sin->sin_addr,
312		    sizeof sin->sin_addr);
313	}
314tryagain:
315	if (rtmsg(RTM_GET) < 0) {
316		perror(host);
317		return (1);
318	}
319	sin = (struct sockaddr_inarp *)(rtm + 1);
320	sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin);
321	if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
322		if (sdl->sdl_family == AF_LINK &&
323		    (rtm->rtm_flags & RTF_LLINFO) &&
324		    !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
325		case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
326		case IFT_ISO88024: case IFT_ISO88025:
327			goto delete;
328		}
329	}
330	if (sin_m.sin_other & SIN_PROXY) {
331		fprintf(stderr, "delete: can't locate %s\n",host);
332		return (1);
333	} else {
334		sin_m.sin_other = SIN_PROXY;
335		goto tryagain;
336	}
337delete:
338	if (sdl->sdl_family != AF_LINK) {
339		printf("cannot locate %s\n", host);
340		return (1);
341	}
342	if (rtmsg(RTM_DELETE) == 0)
343		printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr));
344}
345
346/*
347 * Dump the entire arp table
348 */
349dump(addr)
350u_long addr;
351{
352	int mib[6];
353	size_t needed;
354	char *host, *malloc(), *lim, *buf, *next;
355	struct rt_msghdr *rtm;
356	struct sockaddr_inarp *sin;
357	struct sockaddr_dl *sdl;
358	extern int h_errno;
359	struct hostent *hp;
360
361	mib[0] = CTL_NET;
362	mib[1] = PF_ROUTE;
363	mib[2] = 0;
364	mib[3] = AF_INET;
365	mib[4] = NET_RT_FLAGS;
366	mib[5] = RTF_LLINFO;
367	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
368		quit("route-sysctl-estimate");
369	if ((buf = malloc(needed)) == NULL)
370		quit("malloc");
371	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
372		quit("actual retrieval of routing table");
373	lim = buf + needed;
374	for (next = buf; next < lim; next += rtm->rtm_msglen) {
375		rtm = (struct rt_msghdr *)next;
376		sin = (struct sockaddr_inarp *)(rtm + 1);
377		sdl = (struct sockaddr_dl *)(sin + 1);
378		if (addr) {
379			if (addr != sin->sin_addr.s_addr)
380				continue;
381			found_entry = 1;
382		}
383		if (nflag == 0)
384			hp = gethostbyaddr((caddr_t)&(sin->sin_addr),
385			    sizeof sin->sin_addr, AF_INET);
386		else
387			hp = 0;
388		if (hp)
389			host = hp->h_name;
390		else {
391			host = "?";
392			if (h_errno == TRY_AGAIN)
393				nflag = 1;
394		}
395		printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr));
396		if (sdl->sdl_alen)
397			ether_print(LLADDR(sdl));
398		else
399			printf("(incomplete)");
400		if (rtm->rtm_rmx.rmx_expire == 0)
401			printf(" permanent");
402		if (sin->sin_other & SIN_PROXY)
403			printf(" published (proxy only)");
404		if (rtm->rtm_addrs & RTA_NETMASK) {
405			sin = (struct sockaddr_inarp *)
406				(sdl->sdl_len + (char *)sdl);
407			if (sin->sin_addr.s_addr == 0xffffffff)
408				printf(" published");
409			if (sin->sin_len != 8)
410				printf("(wierd)");
411		}
412		printf("\n");
413	}
414}
415
416ether_print(cp)
417	u_char *cp;
418{
419	printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
420}
421
422ether_aton(a, n)
423	char *a;
424	u_char *n;
425{
426	int i, o[6];
427
428	i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2],
429					   &o[3], &o[4], &o[5]);
430	if (i != 6) {
431		fprintf(stderr, "arp: invalid Ethernet address '%s'\n", a);
432		return (1);
433	}
434	for (i=0; i<6; i++)
435		n[i] = o[i];
436	return (0);
437}
438
439usage()
440{
441	printf("usage: arp hostname\n");
442	printf("       arp -a [kernel] [kernel_memory]\n");
443	printf("       arp -d hostname\n");
444	printf("       arp -s hostname ether_addr [temp] [pub]\n");
445	printf("       arp -f filename\n");
446	exit(1);
447}
448
449rtmsg(cmd)
450{
451	static int seq;
452	int rlen;
453	register struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
454	register char *cp = m_rtmsg.m_space;
455	register int l;
456
457	errno = 0;
458	if (cmd == RTM_DELETE)
459		goto doit;
460	bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
461	rtm->rtm_flags = flags;
462	rtm->rtm_version = RTM_VERSION;
463
464	switch (cmd) {
465	default:
466		fprintf(stderr, "arp: internal wrong cmd\n");
467		exit(1);
468	case RTM_ADD:
469		rtm->rtm_addrs |= RTA_GATEWAY;
470		rtm->rtm_rmx.rmx_expire = expire_time;
471		rtm->rtm_inits = RTV_EXPIRE;
472		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
473		sin_m.sin_other = 0;
474		if (doing_proxy) {
475			if (export_only)
476				sin_m.sin_other = SIN_PROXY;
477			else {
478				rtm->rtm_addrs |= RTA_NETMASK;
479				rtm->rtm_flags &= ~RTF_HOST;
480			}
481		}
482		/* FALLTHROUGH */
483	case RTM_GET:
484		rtm->rtm_addrs |= RTA_DST;
485	}
486#define NEXTADDR(w, s) \
487	if (rtm->rtm_addrs & (w)) { \
488		bcopy((char *)&s, cp, sizeof(s)); cp += sizeof(s);}
489
490	NEXTADDR(RTA_DST, sin_m);
491	NEXTADDR(RTA_GATEWAY, sdl_m);
492	NEXTADDR(RTA_NETMASK, so_mask);
493
494	rtm->rtm_msglen = cp - (char *)&m_rtmsg;
495doit:
496	l = rtm->rtm_msglen;
497	rtm->rtm_seq = ++seq;
498	rtm->rtm_type = cmd;
499	if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
500		if (errno != ESRCH || cmd != RTM_DELETE) {
501			perror("writing to routing socket");
502			return (-1);
503		}
504	}
505	do {
506		l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
507	} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
508	if (l < 0)
509		(void) fprintf(stderr, "arp: read from routing socket: %s\n",
510		    strerror(errno));
511	return (0);
512}
513
514quit(msg)
515char *msg;
516{
517	fprintf(stderr, "%s\n", msg);
518	exit(1);
519}
520