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 * 4. 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 #if 0
34 #ifndef lint
35 static char const copyright[] =
36 "@(#) Copyright (c) 1984, 1993\n\
37 The Regents of the University of California. All rights reserved.\n";
38 #endif /* not lint */
39
40 #ifndef lint
41 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
42 #endif /* not lint */
43 #endif
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
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/sockio.h>
56 #include <sys/sysctl.h>
57 #include <sys/ioctl.h>
58 #include <sys/time.h>
59
60 #include <net/if.h>
61 #include <net/if_dl.h>
62 #include <net/if_types.h>
63 #include <net/route.h>
64 #include <net/iso88025.h>
65
66 #include <netinet/in.h>
67 #include <netinet/if_ether.h>
68
69 #include <arpa/inet.h>
70
71 #include <ctype.h>
72 #include <err.h>
73 #include <errno.h>
74 #include <netdb.h>
75 #include <nlist.h>
76 #include <paths.h>
77 #include <stdio.h>
78 #include <stdlib.h>
79 #include <string.h>
80 #include <strings.h>
81 #include <unistd.h>
82
83 typedef void (action_fn)(struct sockaddr_dl *sdl,
84 struct sockaddr_in *s_in, struct rt_msghdr *rtm);
85
86 static int search(u_long addr, action_fn *action);
87 static action_fn print_entry;
88 static action_fn nuke_entry;
89
90 static int delete(char *host);
91 static void usage(void);
92 static int set(int argc, char **argv);
93 static int get(char *host);
94 static int file(char *name);
95 static struct rt_msghdr *rtmsg(int cmd,
96 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
97 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
98 static struct sockaddr_in *getaddr(char *host);
99 static int valid_type(int type);
100
101 static int nflag; /* no reverse dns lookups */
102 static char *rifname;
103
104 static time_t expire_time;
105 static int flags, doing_proxy;
106
107 struct if_nameindex *ifnameindex;
108
109 /* which function we're supposed to do */
110 #define F_GET 1
111 #define F_SET 2
112 #define F_FILESET 3
113 #define F_REPLACE 4
114 #define F_DELETE 5
115
116 #define SETFUNC(f) { if (func) usage(); func = (f); }
117
118 int
main(int argc,char * argv[])119 main(int argc, char *argv[])
120 {
121 int ch, func = 0;
122 int rtn = 0;
123 int aflag = 0; /* do it for all entries */
124
125 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
126 switch(ch) {
127 case 'a':
128 aflag = 1;
129 break;
130 case 'd':
131 SETFUNC(F_DELETE);
132 break;
133 case 'n':
134 nflag = 1;
135 break;
136 case 'S':
137 SETFUNC(F_REPLACE);
138 break;
139 case 's':
140 SETFUNC(F_SET);
141 break;
142 case 'f' :
143 SETFUNC(F_FILESET);
144 break;
145 case 'i':
146 rifname = optarg;
147 break;
148 case '?':
149 default:
150 usage();
151 }
152 argc -= optind;
153 argv += optind;
154
155 if (!func)
156 func = F_GET;
157 if (rifname) {
158 if (func != F_GET && !(func == F_DELETE && aflag))
159 errx(1, "-i not applicable to this operation");
160 if (if_nametoindex(rifname) == 0) {
161 if (errno == ENXIO)
162 errx(1, "interface %s does not exist", rifname);
163 else
164 err(1, "if_nametoindex(%s)", rifname);
165 }
166 }
167 switch (func) {
168 case F_GET:
169 if (aflag) {
170 if (argc != 0)
171 usage();
172 search(0, print_entry);
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 (aflag) {
189 if (argc != 0)
190 usage();
191 search(0, nuke_entry);
192 } else {
193 if (argc != 1)
194 usage();
195 rtn = delete(argv[0]);
196 }
197 break;
198 case F_FILESET:
199 if (argc != 1)
200 usage();
201 rtn = file(argv[0]);
202 break;
203 }
204
205 if (ifnameindex != NULL)
206 if_freenameindex(ifnameindex);
207
208 return (rtn);
209 }
210
211 /*
212 * Process a file to set standard arp entries
213 */
214 static int
file(char * name)215 file(char *name)
216 {
217 FILE *fp;
218 int i, retval;
219 char line[100], arg[5][50], *args[5], *p;
220
221 if ((fp = fopen(name, "r")) == NULL)
222 err(1, "cannot open %s", name);
223 args[0] = &arg[0][0];
224 args[1] = &arg[1][0];
225 args[2] = &arg[2][0];
226 args[3] = &arg[3][0];
227 args[4] = &arg[4][0];
228 retval = 0;
229 while(fgets(line, sizeof(line), fp) != NULL) {
230 if ((p = strchr(line, '#')) != NULL)
231 *p = '\0';
232 for (p = line; isblank(*p); p++);
233 if (*p == '\n' || *p == '\0')
234 continue;
235 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
236 arg[2], arg[3], arg[4]);
237 if (i < 2) {
238 warnx("bad line: %s", line);
239 retval = 1;
240 continue;
241 }
242 if (set(i, args))
243 retval = 1;
244 }
245 fclose(fp);
246 return (retval);
247 }
248
249 /*
250 * Given a hostname, fills up a (static) struct sockaddr_in with
251 * the address of the host and returns a pointer to the
252 * structure.
253 */
254 static struct sockaddr_in *
getaddr(char * host)255 getaddr(char *host)
256 {
257 struct hostent *hp;
258 static struct sockaddr_in reply;
259
260 bzero(&reply, sizeof(reply));
261 reply.sin_len = sizeof(reply);
262 reply.sin_family = AF_INET;
263 reply.sin_addr.s_addr = inet_addr(host);
264 if (reply.sin_addr.s_addr == INADDR_NONE) {
265 if (!(hp = gethostbyname(host))) {
266 warnx("%s: %s", host, hstrerror(h_errno));
267 return (NULL);
268 }
269 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
270 sizeof reply.sin_addr);
271 }
272 return (&reply);
273 }
274
275 /*
276 * Returns true if the type is a valid one for ARP.
277 */
278 static int
valid_type(int type)279 valid_type(int type)
280 {
281
282 switch (type) {
283 case IFT_ETHER:
284 case IFT_FDDI:
285 case IFT_INFINIBAND:
286 case IFT_ISO88023:
287 case IFT_ISO88024:
288 case IFT_ISO88025:
289 case IFT_L2VLAN:
290 case IFT_BRIDGE:
291 return (1);
292 default:
293 return (0);
294 }
295 }
296
297 /*
298 * Set an individual arp entry
299 */
300 static int
set(int argc,char ** argv)301 set(int argc, char **argv)
302 {
303 struct sockaddr_in *addr;
304 struct sockaddr_in *dst; /* what are we looking for */
305 struct sockaddr_dl *sdl;
306 struct rt_msghdr *rtm;
307 struct ether_addr *ea;
308 char *host = argv[0], *eaddr = argv[1];
309 struct sockaddr_dl sdl_m;
310
311 argc -= 2;
312 argv += 2;
313
314 bzero(&sdl_m, sizeof(sdl_m));
315 sdl_m.sdl_len = sizeof(sdl_m);
316 sdl_m.sdl_family = AF_LINK;
317
318 dst = getaddr(host);
319 if (dst == NULL)
320 return (1);
321 doing_proxy = flags = expire_time = 0;
322 while (argc-- > 0) {
323 if (strncmp(argv[0], "temp", 4) == 0) {
324 struct timespec tp;
325 int max_age;
326 size_t len = sizeof(max_age);
327
328 clock_gettime(CLOCK_MONOTONIC, &tp);
329 if (sysctlbyname("net.link.ether.inet.max_age",
330 &max_age, &len, NULL, 0) != 0)
331 err(1, "sysctlbyname");
332 expire_time = tp.tv_sec + max_age;
333 } else if (strncmp(argv[0], "pub", 3) == 0) {
334 flags |= RTF_ANNOUNCE;
335 doing_proxy = 1;
336 if (argc && strncmp(argv[1], "only", 3) == 0) {
337 /*
338 * Compatibility: in pre FreeBSD 8 times
339 * the "only" keyword used to mean that
340 * an ARP entry should be announced, but
341 * not installed into routing table.
342 */
343 argc--; argv++;
344 }
345 } else if (strncmp(argv[0], "blackhole", 9) == 0) {
346 if (flags & RTF_REJECT) {
347 printf("Choose one of blackhole or reject, not both.\n");
348 }
349 flags |= RTF_BLACKHOLE;
350 } else if (strncmp(argv[0], "reject", 6) == 0) {
351 if (flags & RTF_BLACKHOLE) {
352 printf("Choose one of blackhole or reject, not both.\n");
353 }
354 flags |= RTF_REJECT;
355 } else if (strncmp(argv[0], "trail", 5) == 0) {
356 /* XXX deprecated and undocumented feature */
357 printf("%s: Sending trailers is no longer supported\n",
358 host);
359 }
360 argv++;
361 }
362 ea = (struct ether_addr *)LLADDR(&sdl_m);
363 if (doing_proxy && !strcmp(eaddr, "auto")) {
364 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
365 printf("no interface found for %s\n",
366 inet_ntoa(dst->sin_addr));
367 return (1);
368 }
369 sdl_m.sdl_alen = ETHER_ADDR_LEN;
370 } else {
371 struct ether_addr *ea1 = ether_aton(eaddr);
372
373 if (ea1 == NULL) {
374 warnx("invalid Ethernet address '%s'", eaddr);
375 return (1);
376 } else {
377 *ea = *ea1;
378 sdl_m.sdl_alen = ETHER_ADDR_LEN;
379 }
380 }
381
382 /*
383 * In the case a proxy-arp entry is being added for
384 * a remote end point, the RTF_ANNOUNCE flag in the
385 * RTM_GET command is an indication to the kernel
386 * routing code that the interface associated with
387 * the prefix route covering the local end of the
388 * PPP link should be returned, on which ARP applies.
389 */
390 rtm = rtmsg(RTM_GET, dst, &sdl_m);
391 if (rtm == NULL) {
392 warn("%s", host);
393 return (1);
394 }
395 addr = (struct sockaddr_in *)(rtm + 1);
396 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
397
398 if ((sdl->sdl_family != AF_LINK) ||
399 (rtm->rtm_flags & RTF_GATEWAY) ||
400 !valid_type(sdl->sdl_type)) {
401 printf("cannot intuit interface index and type for %s\n", host);
402 return (1);
403 }
404 sdl_m.sdl_type = sdl->sdl_type;
405 sdl_m.sdl_index = sdl->sdl_index;
406 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
407 }
408
409 /*
410 * Display an individual arp entry
411 */
412 static int
get(char * host)413 get(char *host)
414 {
415 struct sockaddr_in *addr;
416
417 addr = getaddr(host);
418 if (addr == NULL)
419 return (1);
420 if (0 == search(addr->sin_addr.s_addr, print_entry)) {
421 printf("%s (%s) -- no entry",
422 host, inet_ntoa(addr->sin_addr));
423 if (rifname)
424 printf(" on %s", rifname);
425 printf("\n");
426 return (1);
427 }
428 return (0);
429 }
430
431 /*
432 * Delete an arp entry
433 */
434 static int
delete(char * host)435 delete(char *host)
436 {
437 struct sockaddr_in *addr, *dst;
438 struct rt_msghdr *rtm;
439 struct sockaddr_dl *sdl;
440 struct sockaddr_dl sdl_m;
441
442 dst = getaddr(host);
443 if (dst == NULL)
444 return (1);
445
446 /*
447 * Perform a regular entry delete first.
448 */
449 flags &= ~RTF_ANNOUNCE;
450
451 /*
452 * setup the data structure to notify the kernel
453 * it is the ARP entry the RTM_GET is interested
454 * in
455 */
456 bzero(&sdl_m, sizeof(sdl_m));
457 sdl_m.sdl_len = sizeof(sdl_m);
458 sdl_m.sdl_family = AF_LINK;
459
460 for (;;) { /* try twice */
461 rtm = rtmsg(RTM_GET, dst, &sdl_m);
462 if (rtm == NULL) {
463 warn("%s", host);
464 return (1);
465 }
466 addr = (struct sockaddr_in *)(rtm + 1);
467 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
468
469 /*
470 * With the new L2/L3 restructure, the route
471 * returned is a prefix route. The important
472 * piece of information from the previous
473 * RTM_GET is the interface index. In the
474 * case of ECMP, the kernel will traverse
475 * the route group for the given entry.
476 */
477 if (sdl->sdl_family == AF_LINK &&
478 !(rtm->rtm_flags & RTF_GATEWAY) &&
479 valid_type(sdl->sdl_type) ) {
480 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
481 break;
482 }
483
484 /*
485 * Regualar entry delete failed, now check if there
486 * is a proxy-arp entry to remove.
487 */
488 if (flags & RTF_ANNOUNCE) {
489 fprintf(stderr, "delete: cannot locate %s\n",host);
490 return (1);
491 }
492
493 flags |= RTF_ANNOUNCE;
494 }
495 rtm->rtm_flags |= RTF_LLDATA;
496 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
497 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
498 return (0);
499 }
500 return (1);
501 }
502
503
504 /*
505 * Search the arp table and do some action on matching entries
506 */
507 static int
search(u_long addr,action_fn * action)508 search(u_long addr, action_fn *action)
509 {
510 int mib[6];
511 size_t needed;
512 char *lim, *buf, *next;
513 struct rt_msghdr *rtm;
514 struct sockaddr_in *sin2;
515 struct sockaddr_dl *sdl;
516 char ifname[IF_NAMESIZE];
517 int st, found_entry = 0;
518
519 mib[0] = CTL_NET;
520 mib[1] = PF_ROUTE;
521 mib[2] = 0;
522 mib[3] = AF_INET;
523 mib[4] = NET_RT_FLAGS;
524 #ifdef RTF_LLINFO
525 mib[5] = RTF_LLINFO;
526 #else
527 mib[5] = 0;
528 #endif
529 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
530 err(1, "route-sysctl-estimate");
531 if (needed == 0) /* empty table */
532 return 0;
533 buf = NULL;
534 for (;;) {
535 buf = reallocf(buf, needed);
536 if (buf == NULL)
537 errx(1, "could not reallocate memory");
538 st = sysctl(mib, 6, buf, &needed, NULL, 0);
539 if (st == 0 || errno != ENOMEM)
540 break;
541 needed += needed / 8;
542 }
543 if (st == -1)
544 err(1, "actual retrieval of routing table");
545 lim = buf + needed;
546 for (next = buf; next < lim; next += rtm->rtm_msglen) {
547 rtm = (struct rt_msghdr *)next;
548 sin2 = (struct sockaddr_in *)(rtm + 1);
549 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
550 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
551 strcmp(ifname, rifname))
552 continue;
553 if (addr) {
554 if (addr != sin2->sin_addr.s_addr)
555 continue;
556 found_entry = 1;
557 }
558 (*action)(sdl, sin2, rtm);
559 }
560 free(buf);
561 return (found_entry);
562 }
563
564 /*
565 * Display an arp entry
566 */
567
568 static void
print_entry(struct sockaddr_dl * sdl,struct sockaddr_in * addr,struct rt_msghdr * rtm)569 print_entry(struct sockaddr_dl *sdl,
570 struct sockaddr_in *addr, struct rt_msghdr *rtm)
571 {
572 const char *host;
573 struct hostent *hp;
574 struct iso88025_sockaddr_dl_data *trld;
575 struct if_nameindex *p;
576 int seg;
577
578 if (ifnameindex == NULL)
579 if ((ifnameindex = if_nameindex()) == NULL)
580 err(1, "cannot retrieve interface names");
581
582 if (nflag == 0)
583 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
584 sizeof addr->sin_addr, AF_INET);
585 else
586 hp = 0;
587 if (hp)
588 host = hp->h_name;
589 else {
590 host = "?";
591 if (h_errno == TRY_AGAIN)
592 nflag = 1;
593 }
594 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
595 if (sdl->sdl_alen) {
596 if ((sdl->sdl_type == IFT_ETHER ||
597 sdl->sdl_type == IFT_L2VLAN ||
598 sdl->sdl_type == IFT_BRIDGE) &&
599 sdl->sdl_alen == ETHER_ADDR_LEN)
600 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
601 else {
602 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
603
604 printf("%s", link_ntoa(sdl) + n);
605 }
606 } else
607 printf("(incomplete)");
608
609 for (p = ifnameindex; p && ifnameindex->if_index &&
610 ifnameindex->if_name; p++) {
611 if (p->if_index == sdl->sdl_index) {
612 printf(" on %s", p->if_name);
613 break;
614 }
615 }
616
617 if (rtm->rtm_rmx.rmx_expire == 0)
618 printf(" permanent");
619 else {
620 static struct timespec tp;
621 if (tp.tv_sec == 0)
622 clock_gettime(CLOCK_MONOTONIC, &tp);
623 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
624 printf(" expires in %d seconds", (int)expire_time);
625 else
626 printf(" expired");
627 }
628 if (rtm->rtm_flags & RTF_ANNOUNCE)
629 printf(" published");
630 switch(sdl->sdl_type) {
631 case IFT_ETHER:
632 printf(" [ethernet]");
633 break;
634 case IFT_ISO88025:
635 printf(" [token-ring]");
636 trld = SDL_ISO88025(sdl);
637 if (trld->trld_rcf != 0) {
638 printf(" rt=%x", ntohs(trld->trld_rcf));
639 for (seg = 0;
640 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
641 seg++)
642 printf(":%x", ntohs(*(trld->trld_route[seg])));
643 }
644 break;
645 case IFT_FDDI:
646 printf(" [fddi]");
647 break;
648 case IFT_ATM:
649 printf(" [atm]");
650 break;
651 case IFT_L2VLAN:
652 printf(" [vlan]");
653 break;
654 case IFT_IEEE1394:
655 printf(" [firewire]");
656 break;
657 case IFT_BRIDGE:
658 printf(" [bridge]");
659 break;
660 case IFT_INFINIBAND:
661 printf(" [infiniband]");
662 break;
663 default:
664 break;
665 }
666
667 printf("\n");
668
669 }
670
671 /*
672 * Nuke an arp entry
673 */
674 static void
nuke_entry(struct sockaddr_dl * sdl __unused,struct sockaddr_in * addr,struct rt_msghdr * rtm __unused)675 nuke_entry(struct sockaddr_dl *sdl __unused,
676 struct sockaddr_in *addr, struct rt_msghdr *rtm __unused)
677 {
678 char ip[20];
679
680 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
681 delete(ip);
682 }
683
684 static void
usage(void)685 usage(void)
686 {
687 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
688 "usage: arp [-n] [-i interface] hostname",
689 " arp [-n] [-i interface] -a",
690 " arp -d hostname [pub]",
691 " arp -d [-i interface] -a",
692 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
693 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
694 " arp -f filename");
695 exit(1);
696 }
697
698 static struct rt_msghdr *
rtmsg(int cmd,struct sockaddr_in * dst,struct sockaddr_dl * sdl)699 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
700 {
701 static int seq;
702 int rlen;
703 int l;
704 struct sockaddr_in so_mask, *som = &so_mask;
705 static int s = -1;
706 static pid_t pid;
707
708 static struct {
709 struct rt_msghdr m_rtm;
710 char m_space[512];
711 } m_rtmsg;
712
713 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
714 char *cp = m_rtmsg.m_space;
715
716 if (s < 0) { /* first time: open socket, get pid */
717 s = socket(PF_ROUTE, SOCK_RAW, 0);
718 if (s < 0)
719 err(1, "socket");
720 pid = getpid();
721 }
722 bzero(&so_mask, sizeof(so_mask));
723 so_mask.sin_len = 8;
724 so_mask.sin_addr.s_addr = 0xffffffff;
725
726 errno = 0;
727 /*
728 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
729 * appropriately.
730 */
731 if (cmd == RTM_DELETE)
732 goto doit;
733 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
734 rtm->rtm_flags = flags;
735 rtm->rtm_version = RTM_VERSION;
736
737 switch (cmd) {
738 default:
739 errx(1, "internal wrong cmd");
740 case RTM_ADD:
741 rtm->rtm_addrs |= RTA_GATEWAY;
742 rtm->rtm_rmx.rmx_expire = expire_time;
743 rtm->rtm_inits = RTV_EXPIRE;
744 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
745 if (doing_proxy) {
746 rtm->rtm_addrs |= RTA_NETMASK;
747 rtm->rtm_flags &= ~RTF_HOST;
748 }
749 /* FALLTHROUGH */
750 case RTM_GET:
751 rtm->rtm_addrs |= RTA_DST;
752 }
753 #define NEXTADDR(w, s) \
754 do { \
755 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
756 bcopy((s), cp, sizeof(*(s))); \
757 cp += SA_SIZE(s); \
758 } \
759 } while (0)
760
761 NEXTADDR(RTA_DST, dst);
762 NEXTADDR(RTA_GATEWAY, sdl);
763 NEXTADDR(RTA_NETMASK, som);
764
765 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
766 doit:
767 l = rtm->rtm_msglen;
768 rtm->rtm_seq = ++seq;
769 rtm->rtm_type = cmd;
770 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
771 if (errno != ESRCH || cmd != RTM_DELETE) {
772 warn("writing to routing socket");
773 return (NULL);
774 }
775 }
776 do {
777 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
778 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
779 if (l < 0)
780 warn("read from routing socket");
781 return (rtm);
782 }
783
784 /*
785 * get_ether_addr - get the hardware address of an interface on the
786 * the same subnet as ipaddr.
787 */
788 #define MAX_IFS 32
789
790 static int
get_ether_addr(in_addr_t ipaddr,struct ether_addr * hwaddr)791 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
792 {
793 struct ifreq *ifr, *ifend, *ifp;
794 in_addr_t ina, mask;
795 struct sockaddr_dl *dla;
796 struct ifreq ifreq;
797 struct ifconf ifc;
798 struct ifreq ifs[MAX_IFS];
799 int sock;
800 int retval = 0;
801
802 sock = socket(AF_INET, SOCK_DGRAM, 0);
803 if (sock < 0)
804 err(1, "socket");
805
806 ifc.ifc_len = sizeof(ifs);
807 ifc.ifc_req = ifs;
808 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
809 warnx("ioctl(SIOCGIFCONF)");
810 goto done;
811 }
812
813 #define NEXTIFR(i) \
814 ((struct ifreq *)((char *)&(i)->ifr_addr \
815 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
816
817 /*
818 * Scan through looking for an interface with an Internet
819 * address on the same subnet as `ipaddr'.
820 */
821 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
822 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
823 if (ifr->ifr_addr.sa_family != AF_INET)
824 continue;
825 strncpy(ifreq.ifr_name, ifr->ifr_name,
826 sizeof(ifreq.ifr_name));
827 ifreq.ifr_addr = ifr->ifr_addr;
828 /*
829 * Check that the interface is up,
830 * and not point-to-point or loopback.
831 */
832 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
833 continue;
834 if ((ifreq.ifr_flags &
835 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
836 IFF_LOOPBACK|IFF_NOARP))
837 != (IFF_UP|IFF_BROADCAST))
838 continue;
839 /*
840 * Get its netmask and check that it's on
841 * the right subnet.
842 */
843 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
844 continue;
845 mask = ((struct sockaddr_in *)
846 &ifreq.ifr_addr)->sin_addr.s_addr;
847 ina = ((struct sockaddr_in *)
848 &ifr->ifr_addr)->sin_addr.s_addr;
849 if ((ipaddr & mask) == (ina & mask))
850 break; /* ok, we got it! */
851 }
852
853 if (ifr >= ifend)
854 goto done;
855
856 /*
857 * Now scan through again looking for a link-level address
858 * for this interface.
859 */
860 ifp = ifr;
861 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
862 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
863 ifr->ifr_addr.sa_family == AF_LINK)
864 break;
865 if (ifr >= ifend)
866 goto done;
867 /*
868 * Found the link-level address - copy it out
869 */
870 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
871 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
872 printf("using interface %s for proxy with address ",
873 ifp->ifr_name);
874 printf("%s\n", ether_ntoa(hwaddr));
875 retval = dla->sdl_alen;
876 done:
877 close(sock);
878 return (retval);
879 }
880