1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 /*
36 * arp - display, set, and delete arp table entries
37 */
38
39 #include <sys/param.h>
40 #include <sys/file.h>
41 #include <sys/socket.h>
42 #include <sys/sockio.h>
43 #include <sys/sysctl.h>
44 #include <sys/ioctl.h>
45 #include <sys/time.h>
46
47 #include <net/if.h>
48 #include <net/if_dl.h>
49 #include <net/if_types.h>
50 #include <net/route.h>
51
52 #include <netinet/in.h>
53 #include <netinet/if_ether.h>
54
55 #include <arpa/inet.h>
56
57 #include <ctype.h>
58 #include <errno.h>
59 #include <netdb.h>
60 #include <nlist.h>
61 #include <paths.h>
62 #include <stdbool.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <string.h>
66 #include <strings.h>
67 #include <unistd.h>
68 #include <ifaddrs.h>
69 #include <libxo/xo.h>
70 #include "arp.h"
71
72 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in,
73 struct rt_msghdr *rtm);
74 static void nuke_entries(uint32_t ifindex, struct in_addr addr);
75 static int print_entries(uint32_t ifindex, struct in_addr addr);
76
77 static int delete(char *host);
78 static void usage(void) __dead2;
79 static int set(int argc, char **argv);
80 static int get(char *host);
81 static int file(char *name);
82 static struct rt_msghdr *rtmsg(int cmd,
83 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
84 static int set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m,
85 char *host);
86
87 struct if_nameindex *ifnameindex;
88
89 struct arp_opts opts = {};
90
91 /* which function we're supposed to do */
92 #define F_GET 1
93 #define F_SET 2
94 #define F_FILESET 3
95 #define F_REPLACE 4
96 #define F_DELETE 5
97
98 #define SETFUNC(f) { if (func) usage(); func = (f); }
99
100 #define ARP_XO_VERSION "1"
101
102 int
main(int argc,char * argv[])103 main(int argc, char *argv[])
104 {
105 int ch, func = 0;
106 int rtn = 0;
107
108 argc = xo_parse_args(argc, argv);
109 if (argc < 0)
110 exit(1);
111
112 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
113 switch(ch) {
114 case 'a':
115 opts.aflag = true;
116 break;
117 case 'd':
118 SETFUNC(F_DELETE);
119 break;
120 case 'n':
121 opts.nflag = true;
122 break;
123 case 'S':
124 SETFUNC(F_REPLACE);
125 break;
126 case 's':
127 SETFUNC(F_SET);
128 break;
129 case 'f' :
130 SETFUNC(F_FILESET);
131 break;
132 case 'i':
133 opts.rifname = optarg;
134 break;
135 case '?':
136 default:
137 usage();
138 }
139 argc -= optind;
140 argv += optind;
141
142 if (!func)
143 func = F_GET;
144 if (opts.rifname) {
145 if (func != F_GET && func != F_SET && func != F_REPLACE &&
146 !(func == F_DELETE && opts.aflag))
147 xo_errx(1, "-i not applicable to this operation");
148 if ((opts.rifindex = if_nametoindex(opts.rifname)) == 0) {
149 if (errno == ENXIO)
150 xo_errx(1, "interface %s does not exist",
151 opts.rifname);
152 else
153 xo_err(1, "if_nametoindex(%s)", opts.rifname);
154 }
155 }
156 switch (func) {
157 case F_GET:
158 if (opts.aflag) {
159 if (argc != 0)
160 usage();
161
162 xo_set_version(ARP_XO_VERSION);
163 xo_open_container("arp");
164 xo_open_list("arp-cache");
165
166 struct in_addr all_addrs = {};
167 print_entries(opts.rifindex, all_addrs);
168
169 xo_close_list("arp-cache");
170 xo_close_container("arp");
171 if (xo_finish() < 0)
172 xo_err(1, "stdout");
173 } else {
174 if (argc != 1)
175 usage();
176 rtn = get(argv[0]);
177 }
178 break;
179 case F_SET:
180 case F_REPLACE:
181 if (argc < 2 || argc > 6)
182 usage();
183 if (func == F_REPLACE)
184 (void)delete(argv[0]);
185 rtn = set(argc, argv) ? 1 : 0;
186 break;
187 case F_DELETE:
188 if (opts.aflag) {
189 if (argc != 0)
190 usage();
191 struct in_addr all_addrs = {};
192 nuke_entries(0, all_addrs);
193 } else {
194 if (argc != 1)
195 usage();
196 rtn = delete(argv[0]);
197 }
198 break;
199 case F_FILESET:
200 if (argc != 1)
201 usage();
202 rtn = file(argv[0]);
203 break;
204 }
205
206 if (ifnameindex != NULL)
207 if_freenameindex(ifnameindex);
208
209 exit(rtn);
210 }
211
212 /*
213 * Process a file to set standard arp entries
214 */
215 static int
file(char * name)216 file(char *name)
217 {
218 FILE *fp;
219 int i, retval;
220 char line[100], arg[5][50], *args[5], *p;
221
222 if ((fp = fopen(name, "r")) == NULL)
223 xo_err(1, "cannot open %s", name);
224 args[0] = &arg[0][0];
225 args[1] = &arg[1][0];
226 args[2] = &arg[2][0];
227 args[3] = &arg[3][0];
228 args[4] = &arg[4][0];
229 retval = 0;
230 while(fgets(line, sizeof(line), fp) != NULL) {
231 if ((p = strchr(line, '#')) != NULL)
232 *p = '\0';
233 for (p = line; isblank(*p); p++);
234 if (*p == '\n' || *p == '\0')
235 continue;
236 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
237 arg[2], arg[3], arg[4]);
238 if (i < 2) {
239 xo_warnx("bad line: %s", line);
240 retval = 1;
241 continue;
242 }
243 if (set(i, args))
244 retval = 1;
245 }
246 fclose(fp);
247 return (retval);
248 }
249
250 /*
251 * Given a hostname, fills up a (static) struct sockaddr_in with
252 * the address of the host and returns a pointer to the
253 * structure.
254 */
255 struct sockaddr_in *
getaddr(char * host)256 getaddr(char *host)
257 {
258 struct hostent *hp;
259 static struct sockaddr_in reply;
260
261 bzero(&reply, sizeof(reply));
262 reply.sin_len = sizeof(reply);
263 reply.sin_family = AF_INET;
264 reply.sin_addr.s_addr = inet_addr(host);
265 if (reply.sin_addr.s_addr == INADDR_NONE) {
266 if (!(hp = gethostbyname(host))) {
267 xo_warnx("%s: %s", host, hstrerror(h_errno));
268 return (NULL);
269 }
270 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
271 sizeof reply.sin_addr);
272 }
273 return (&reply);
274 }
275
276 /*
277 * Returns true if the type is a valid one for ARP.
278 */
279 int
valid_type(int type)280 valid_type(int type)
281 {
282
283 switch (type) {
284 case IFT_ETHER:
285 case IFT_FDDI:
286 case IFT_IEEE1394:
287 case IFT_INFINIBAND:
288 case IFT_ISO88023:
289 case IFT_ISO88024:
290 case IFT_L2VLAN:
291 case IFT_BRIDGE:
292 return (1);
293 default:
294 return (0);
295 }
296 }
297
298 /*
299 * Set an individual arp entry
300 */
301 static int
set(int argc,char ** argv)302 set(int argc, char **argv)
303 {
304 struct sockaddr_in *dst; /* what are we looking for */
305 struct ether_addr *ea;
306 char *host = argv[0], *eaddr = argv[1];
307 struct sockaddr_dl sdl_m;
308
309 argc -= 2;
310 argv += 2;
311
312 bzero(&sdl_m, sizeof(sdl_m));
313 sdl_m.sdl_len = sizeof(sdl_m);
314 sdl_m.sdl_family = AF_LINK;
315
316 dst = getaddr(host);
317 if (dst == NULL)
318 return (1);
319 while (argc-- > 0) {
320 if (strcmp(argv[0], "temp") == 0) {
321 int max_age;
322 size_t len = sizeof(max_age);
323
324 if (sysctlbyname("net.link.ether.inet.max_age",
325 &max_age, &len, NULL, 0) != 0)
326 xo_err(1, "sysctlbyname");
327 opts.expire_time = max_age;
328 } else if (strcmp(argv[0], "pub") == 0) {
329 opts.flags |= RTF_ANNOUNCE;
330 if (argc && strcmp(argv[1], "only") == 0) {
331 /*
332 * Compatibility: in pre FreeBSD 8 times
333 * the "only" keyword used to mean that
334 * an ARP entry should be announced, but
335 * not installed into routing table.
336 */
337 argc--; argv++;
338 }
339 } else if (strcmp(argv[0], "blackhole") == 0) {
340 if (opts.flags & RTF_REJECT) {
341 xo_errx(1, "Choose one of blackhole or reject, "
342 "not both.");
343 }
344 opts.flags |= RTF_BLACKHOLE;
345 } else if (strcmp(argv[0], "reject") == 0) {
346 if (opts.flags & RTF_BLACKHOLE) {
347 xo_errx(1, "Choose one of blackhole or reject, "
348 "not both.");
349 }
350 opts.flags |= RTF_REJECT;
351 } else {
352 xo_warnx("Invalid parameter '%s'", argv[0]);
353 usage();
354 }
355 argv++;
356 }
357 ea = (struct ether_addr *)LLADDR(&sdl_m);
358 if ((opts.flags & RTF_ANNOUNCE) && !strcmp(eaddr, "auto")) {
359 uint32_t ifindex;
360 if (!get_ifinfo(dst->sin_addr.s_addr, ea, &ifindex)) {
361 xo_warnx("no interface found for %s",
362 inet_ntoa(dst->sin_addr));
363 return (1);
364 }
365 if (opts.rifindex == 0)
366 opts.rifindex = ifindex;
367 sdl_m.sdl_alen = ETHER_ADDR_LEN;
368 } else {
369 struct ether_addr *ea1 = ether_aton(eaddr);
370
371 if (ea1 == NULL) {
372 xo_warnx("invalid Ethernet address '%s'", eaddr);
373 return (1);
374 } else {
375 *ea = *ea1;
376 sdl_m.sdl_alen = ETHER_ADDR_LEN;
377 }
378 }
379 #ifndef WITHOUT_NETLINK
380 return (set_nl(dst, &sdl_m, host));
381 #else
382 return (set_rtsock(dst, &sdl_m, host));
383 #endif
384 }
385
386 #ifdef WITHOUT_NETLINK
387 static int
set_rtsock(struct sockaddr_in * dst,struct sockaddr_dl * sdl_m,char * host)388 set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, char *host)
389 {
390 struct sockaddr_in *addr;
391 struct sockaddr_dl *sdl;
392 struct rt_msghdr *rtm;
393
394 /*
395 * In the case a proxy-arp entry is being added for
396 * a remote end point, the RTF_ANNOUNCE flag in the
397 * RTM_GET command is an indication to the kernel
398 * routing code that the interface associated with
399 * the prefix route covering the local end of the
400 * PPP link should be returned, on which ARP applies.
401 */
402 rtm = rtmsg(RTM_GET, dst, NULL);
403 if (rtm == NULL) {
404 xo_warn("%s", host);
405 return (1);
406 }
407 addr = (struct sockaddr_in *)(rtm + 1);
408 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
409
410 if ((sdl->sdl_family != AF_LINK) ||
411 (rtm->rtm_flags & RTF_GATEWAY) ||
412 !valid_type(sdl->sdl_type)) {
413 xo_warnx("cannot intuit interface index and type for %s", host);
414 return (1);
415 }
416 sdl_m->sdl_type = sdl->sdl_type;
417 sdl_m->sdl_index = sdl->sdl_index;
418 return (rtmsg(RTM_ADD, dst, sdl_m) == NULL);
419 }
420 #endif
421
422 /*
423 * Display an individual arp entry
424 */
425 static int
get(char * host)426 get(char *host)
427 {
428 struct sockaddr_in *addr;
429 int found;
430
431 addr = getaddr(host);
432 if (addr == NULL)
433 return (1);
434
435 xo_set_version(ARP_XO_VERSION);
436 xo_open_container("arp");
437 xo_open_list("arp-cache");
438
439 found = print_entries(opts.rifindex, addr->sin_addr);
440
441 if (found == 0) {
442 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry",
443 host, inet_ntoa(addr->sin_addr));
444 if (opts.rifname)
445 xo_emit(" on {d:interface/%s}", opts.rifname);
446 xo_emit("\n");
447 }
448
449 xo_close_list("arp-cache");
450 xo_close_container("arp");
451 if (xo_finish() < 0)
452 xo_err(1, "stdout");
453
454 return (found == 0);
455 }
456
457 /*
458 * Delete an arp entry
459 */
460 #ifdef WITHOUT_NETLINK
461 static int
delete_rtsock(char * host)462 delete_rtsock(char *host)
463 {
464 struct sockaddr_in *addr, *dst;
465 struct rt_msghdr *rtm;
466 struct sockaddr_dl *sdl;
467
468 dst = getaddr(host);
469 if (dst == NULL)
470 return (1);
471
472 /*
473 * Perform a regular entry delete first.
474 */
475 opts.flags &= ~RTF_ANNOUNCE;
476
477 for (;;) { /* try twice */
478 rtm = rtmsg(RTM_GET, dst, NULL);
479 if (rtm == NULL) {
480 xo_warn("%s", host);
481 return (1);
482 }
483 addr = (struct sockaddr_in *)(rtm + 1);
484 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
485
486 /*
487 * With the new L2/L3 restructure, the route
488 * returned is a prefix route. The important
489 * piece of information from the previous
490 * RTM_GET is the interface index. In the
491 * case of ECMP, the kernel will traverse
492 * the route group for the given entry.
493 */
494 if (sdl->sdl_family == AF_LINK &&
495 !(rtm->rtm_flags & RTF_GATEWAY) &&
496 valid_type(sdl->sdl_type) ) {
497 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
498 break;
499 }
500
501 /*
502 * Regular entry delete failed, now check if there
503 * is a proxy-arp entry to remove.
504 */
505 if (opts.flags & RTF_ANNOUNCE) {
506 xo_warnx("delete: cannot locate %s", host);
507 return (1);
508 }
509
510 opts.flags |= RTF_ANNOUNCE;
511 }
512 rtm->rtm_flags |= RTF_LLDATA;
513 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
514 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
515 return (0);
516 }
517 return (1);
518 }
519 #endif
520
521 static int
delete(char * host)522 delete(char *host)
523 {
524 #ifdef WITHOUT_NETLINK
525 return (delete_rtsock(host));
526 #else
527 return (delete_nl(host));
528 #endif
529 }
530
531
532 /*
533 * Search the arp table and do some action on matching entries
534 */
535 static int
search(u_long addr,action_fn * action)536 search(u_long addr, action_fn *action)
537 {
538 int mib[6];
539 size_t needed;
540 char *lim, *buf, *next;
541 struct rt_msghdr *rtm;
542 struct sockaddr_in *sin2;
543 struct sockaddr_dl *sdl;
544 int st, found_entry = 0;
545
546 mib[0] = CTL_NET;
547 mib[1] = PF_ROUTE;
548 mib[2] = 0;
549 mib[3] = AF_INET;
550 mib[4] = NET_RT_FLAGS;
551 #ifdef RTF_LLINFO
552 mib[5] = RTF_LLINFO;
553 #else
554 mib[5] = 0;
555 #endif
556 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
557 xo_err(1, "route-sysctl-estimate");
558 if (needed == 0) /* empty table */
559 return 0;
560 buf = NULL;
561 for (;;) {
562 buf = reallocf(buf, needed);
563 if (buf == NULL)
564 xo_errx(1, "could not reallocate memory");
565 st = sysctl(mib, 6, buf, &needed, NULL, 0);
566 if (st == 0 || errno != ENOMEM)
567 break;
568 needed += needed / 8;
569 }
570 if (st == -1)
571 xo_err(1, "actual retrieval of routing table");
572 lim = buf + needed;
573 for (next = buf; next < lim; next += rtm->rtm_msglen) {
574 rtm = (struct rt_msghdr *)next;
575 sin2 = (struct sockaddr_in *)(rtm + 1);
576 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
577 if (opts.rifindex &&
578 (opts.rifindex != sdl->sdl_index))
579 continue;
580 if (addr &&
581 (addr != sin2->sin_addr.s_addr))
582 continue;
583 found_entry = 1;
584 (*action)(sdl, sin2, rtm);
585 }
586 free(buf);
587 return (found_entry);
588 }
589
590 /*
591 * Display an arp entry
592 */
593
594 static void
print_entry(struct sockaddr_dl * sdl,struct sockaddr_in * addr,struct rt_msghdr * rtm)595 print_entry(struct sockaddr_dl *sdl,
596 struct sockaddr_in *addr, struct rt_msghdr *rtm)
597 {
598 const char *host;
599 struct hostent *hp;
600 struct if_nameindex *p;
601
602 if (ifnameindex == NULL)
603 if ((ifnameindex = if_nameindex()) == NULL)
604 xo_err(1, "cannot retrieve interface names");
605
606 xo_open_instance("arp-cache");
607
608 if (!opts.nflag)
609 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
610 sizeof addr->sin_addr, AF_INET);
611 else
612 hp = 0;
613 if (hp)
614 host = hp->h_name;
615 else {
616 host = "?";
617 if (h_errno == TRY_AGAIN)
618 opts.nflag = true;
619 }
620 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host,
621 inet_ntoa(addr->sin_addr));
622 if (sdl->sdl_alen) {
623 if ((sdl->sdl_type == IFT_ETHER ||
624 sdl->sdl_type == IFT_L2VLAN ||
625 sdl->sdl_type == IFT_BRIDGE) &&
626 sdl->sdl_alen == ETHER_ADDR_LEN)
627 xo_emit("{:mac-address/%s}",
628 ether_ntoa((struct ether_addr *)LLADDR(sdl)));
629 else {
630 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
631
632 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n);
633 }
634 } else
635 xo_emit("{d:/(incomplete)}{en:incomplete/true}");
636
637 for (p = ifnameindex; p && p->if_index && p->if_name; p++) {
638 if (p->if_index == sdl->sdl_index) {
639 xo_emit(" on {:interface/%s}", p->if_name);
640 break;
641 }
642 }
643
644 if (rtm->rtm_rmx.rmx_expire == 0)
645 xo_emit("{d:/ permanent}{en:permanent/true}");
646 else {
647 static struct timespec tp;
648 time_t expire_time = 0;
649
650 if (tp.tv_sec == 0)
651 clock_gettime(CLOCK_MONOTONIC, &tp);
652 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
653 xo_emit(" expires in {:expires/%d} seconds",
654 (int)expire_time);
655 else
656 xo_emit("{d:/ expired}{en:expired/true}");
657 }
658
659 if (rtm->rtm_flags & RTF_ANNOUNCE)
660 xo_emit("{d:/ published}{en:published/true}");
661
662 switch(sdl->sdl_type) {
663 case IFT_ETHER:
664 xo_emit(" [{:type/ethernet}]");
665 break;
666 case IFT_FDDI:
667 xo_emit(" [{:type/fddi}]");
668 break;
669 case IFT_ATM:
670 xo_emit(" [{:type/atm}]");
671 break;
672 case IFT_L2VLAN:
673 xo_emit(" [{:type/vlan}]");
674 break;
675 case IFT_IEEE1394:
676 xo_emit(" [{:type/firewire}]");
677 break;
678 case IFT_BRIDGE:
679 xo_emit(" [{:type/bridge}]");
680 break;
681 case IFT_INFINIBAND:
682 xo_emit(" [{:type/infiniband}]");
683 break;
684 default:
685 break;
686 }
687
688 xo_emit("\n");
689
690 xo_close_instance("arp-cache");
691 }
692
693 static int
print_entries(uint32_t ifindex,struct in_addr addr)694 print_entries(uint32_t ifindex, struct in_addr addr)
695 {
696 #ifndef WITHOUT_NETLINK
697 return (print_entries_nl(ifindex, addr));
698 #else
699 return (search(addr.s_addr, print_entry));
700 #endif
701 }
702
703
704 /*
705 * Nuke an arp entry
706 */
707 static void
nuke_entry(struct sockaddr_dl * sdl __unused,struct sockaddr_in * addr,struct rt_msghdr * rtm)708 nuke_entry(struct sockaddr_dl *sdl __unused,
709 struct sockaddr_in *addr, struct rt_msghdr *rtm)
710 {
711 char ip[20];
712
713 if (rtm->rtm_flags & RTF_PINNED)
714 return;
715
716 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
717 delete(ip);
718 }
719
720 static void
nuke_entries(uint32_t ifindex,struct in_addr addr)721 nuke_entries(uint32_t ifindex, struct in_addr addr)
722 {
723 search(addr.s_addr, nuke_entry);
724 }
725
726 static void
usage(void)727 usage(void)
728 {
729 xo_error("%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
730 "usage: arp [-n] [-i interface] hostname",
731 " arp [-n] [-i interface] -a",
732 " arp -d hostname [pub]",
733 " arp -d [-i interface] -a",
734 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
735 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
736 " arp -f filename");
737 exit(1);
738 }
739
740 static struct rt_msghdr *
rtmsg(int cmd,struct sockaddr_in * dst,struct sockaddr_dl * sdl)741 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
742 {
743 static int seq;
744 int rlen;
745 int l;
746 static int s = -1;
747 static pid_t pid;
748
749 static struct {
750 struct rt_msghdr m_rtm;
751 char m_space[512];
752 } m_rtmsg;
753
754 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
755 char *cp = m_rtmsg.m_space;
756
757 if (s < 0) { /* first time: open socket, get pid */
758 s = socket(PF_ROUTE, SOCK_RAW, 0);
759 if (s < 0)
760 xo_err(1, "socket");
761 pid = getpid();
762 }
763
764 errno = 0;
765 /*
766 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
767 * appropriately.
768 */
769 if (cmd == RTM_DELETE)
770 goto doit;
771 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
772 rtm->rtm_flags = opts.flags;
773 rtm->rtm_version = RTM_VERSION;
774
775 switch (cmd) {
776 default:
777 xo_errx(1, "internal wrong cmd");
778 case RTM_ADD:
779 rtm->rtm_addrs |= RTA_GATEWAY;
780 if (opts.expire_time != 0) {
781 struct timespec tp;
782
783 clock_gettime(CLOCK_MONOTONIC, &tp);
784 rtm->rtm_rmx.rmx_expire = opts.expire_time + tp.tv_sec;
785 }
786 rtm->rtm_inits = RTV_EXPIRE;
787 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
788 /* FALLTHROUGH */
789 case RTM_GET:
790 rtm->rtm_addrs |= RTA_DST;
791 }
792 #define NEXTADDR(w, s) \
793 do { \
794 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
795 bcopy((s), cp, sizeof(*(s))); \
796 cp += SA_SIZE(s); \
797 } \
798 } while (0)
799
800 NEXTADDR(RTA_DST, dst);
801 NEXTADDR(RTA_GATEWAY, sdl);
802
803 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
804 doit:
805 l = rtm->rtm_msglen;
806 rtm->rtm_seq = ++seq;
807 rtm->rtm_type = cmd;
808 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
809 if (errno != ESRCH || cmd != RTM_DELETE) {
810 xo_warn("writing to routing socket");
811 return (NULL);
812 }
813 }
814 do {
815 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
816 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq ||
817 rtm->rtm_pid != pid));
818 if (l < 0)
819 xo_warn("read from routing socket");
820 return (rtm);
821 }
822
823 /*
824 * get_ifinfo - get the hardware address and if_index of an interface
825 * on the same subnet as ipaddr.
826 */
827 int
get_ifinfo(in_addr_t ipaddr,struct ether_addr * hwaddr,uint32_t * pifindex)828 get_ifinfo(in_addr_t ipaddr, struct ether_addr *hwaddr, uint32_t *pifindex)
829 {
830 struct ifaddrs *ifa, *ifd, *ifas = NULL;
831 in_addr_t ina, mask;
832 struct sockaddr_dl *dla;
833 int retval = 0;
834
835 /*
836 * Scan through looking for an interface with an Internet
837 * address on the same subnet as `ipaddr'.
838 */
839 if (getifaddrs(&ifas) < 0) {
840 xo_warnx("getifaddrs");
841 goto done;
842 }
843
844 for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) {
845 if (ifa->ifa_addr == NULL || ifa->ifa_netmask == NULL)
846 continue;
847 if (ifa->ifa_addr->sa_family != AF_INET)
848 continue;
849 /*
850 * Check that the interface is up,
851 * and not point-to-point or loopback.
852 */
853 if ((ifa->ifa_flags &
854 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
855 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST))
856 continue;
857 /* Get its netmask and check that it's on the right subnet. */
858 mask = ((struct sockaddr_in *)
859 ifa->ifa_netmask)->sin_addr.s_addr;
860 ina = ((struct sockaddr_in *)
861 ifa->ifa_addr)->sin_addr.s_addr;
862 if ((ipaddr & mask) == (ina & mask))
863 break; /* ok, we got it! */
864 }
865 if (ifa == NULL)
866 goto done;
867 if (pifindex != NULL)
868 *pifindex = if_nametoindex(ifa->ifa_name);
869 if (hwaddr == NULL) {
870 /* ether addr is not required */
871 retval = ETHER_ADDR_LEN;
872 goto done;
873 }
874 /*
875 * Now scan through again looking for a link-level address
876 * for this interface.
877 */
878 for (ifd = ifas; ifd != NULL; ifd = ifd->ifa_next) {
879 if (ifd->ifa_addr == NULL)
880 continue;
881 if (strcmp(ifa->ifa_name, ifd->ifa_name) == 0 &&
882 ifd->ifa_addr->sa_family == AF_LINK)
883 break;
884 }
885 if (ifd == NULL)
886 goto done;
887 /*
888 * Found the link-level address - copy it out
889 */
890 dla = (struct sockaddr_dl *)ifd->ifa_addr;
891 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
892 printf("using interface %s for proxy with address %s\n", ifa->ifa_name,
893 ether_ntoa(hwaddr));
894 retval = dla->sdl_alen;
895 done:
896 if (ifas != NULL)
897 freeifaddrs(ifas);
898 return (retval);
899 }
900