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 #if 0
36 #ifndef lint
37 static char const copyright[] =
38 "@(#) Copyright (c) 1984, 1993\n\
39 The Regents of the University of California. All rights reserved.\n";
40 #endif /* not lint */
41
42 #ifndef lint
43 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
44 #endif /* not lint */
45 #endif
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
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/sockio.h>
57 #include <sys/sysctl.h>
58 #include <sys/ioctl.h>
59 #include <sys/time.h>
60
61 #include <net/if.h>
62 #include <net/if_dl.h>
63 #include <net/if_types.h>
64 #include <net/route.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 #include <libxo/xo.h>
83
84 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in,
85 struct rt_msghdr *rtm);
86
87 static int search(u_long addr, action_fn *action);
88 static action_fn print_entry;
89 static action_fn nuke_entry;
90
91 static int delete(char *host);
92 static void usage(void);
93 static int set(int argc, char **argv);
94 static int get(char *host);
95 static int file(char *name);
96 static struct rt_msghdr *rtmsg(int cmd,
97 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
98 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
99 static struct sockaddr_in *getaddr(char *host);
100 static int valid_type(int type);
101
102 static int nflag; /* no reverse dns lookups */
103 static char *rifname;
104
105 static time_t expire_time;
106 static int flags, doing_proxy;
107
108 struct if_nameindex *ifnameindex;
109
110 /* which function we're supposed to do */
111 #define F_GET 1
112 #define F_SET 2
113 #define F_FILESET 3
114 #define F_REPLACE 4
115 #define F_DELETE 5
116
117 #define SETFUNC(f) { if (func) usage(); func = (f); }
118
119 #define ARP_XO_VERSION "1"
120
121 int
main(int argc,char * argv[])122 main(int argc, char *argv[])
123 {
124 int ch, func = 0;
125 int rtn = 0;
126 int aflag = 0; /* do it for all entries */
127
128 argc = xo_parse_args(argc, argv);
129 if (argc < 0)
130 exit(1);
131
132 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
133 switch(ch) {
134 case 'a':
135 aflag = 1;
136 break;
137 case 'd':
138 SETFUNC(F_DELETE);
139 break;
140 case 'n':
141 nflag = 1;
142 break;
143 case 'S':
144 SETFUNC(F_REPLACE);
145 break;
146 case 's':
147 SETFUNC(F_SET);
148 break;
149 case 'f' :
150 SETFUNC(F_FILESET);
151 break;
152 case 'i':
153 rifname = optarg;
154 break;
155 case '?':
156 default:
157 usage();
158 }
159 argc -= optind;
160 argv += optind;
161
162 if (!func)
163 func = F_GET;
164 if (rifname) {
165 if (func != F_GET && !(func == F_DELETE && aflag))
166 xo_errx(1, "-i not applicable to this operation");
167 if (if_nametoindex(rifname) == 0) {
168 if (errno == ENXIO)
169 xo_errx(1, "interface %s does not exist",
170 rifname);
171 else
172 xo_err(1, "if_nametoindex(%s)", rifname);
173 }
174 }
175 switch (func) {
176 case F_GET:
177 if (aflag) {
178 if (argc != 0)
179 usage();
180
181 xo_set_version(ARP_XO_VERSION);
182 xo_open_container("arp");
183 xo_open_list("arp-cache");
184
185 search(0, print_entry);
186
187 xo_close_list("arp-cache");
188 xo_close_container("arp");
189 xo_finish();
190 } else {
191 if (argc != 1)
192 usage();
193 rtn = get(argv[0]);
194 }
195 break;
196 case F_SET:
197 case F_REPLACE:
198 if (argc < 2 || argc > 6)
199 usage();
200 if (func == F_REPLACE)
201 (void)delete(argv[0]);
202 rtn = set(argc, argv) ? 1 : 0;
203 break;
204 case F_DELETE:
205 if (aflag) {
206 if (argc != 0)
207 usage();
208 search(0, nuke_entry);
209 } else {
210 if (argc != 1)
211 usage();
212 rtn = delete(argv[0]);
213 }
214 break;
215 case F_FILESET:
216 if (argc != 1)
217 usage();
218 rtn = file(argv[0]);
219 break;
220 }
221
222 if (ifnameindex != NULL)
223 if_freenameindex(ifnameindex);
224
225 return (rtn);
226 }
227
228 /*
229 * Process a file to set standard arp entries
230 */
231 static int
file(char * name)232 file(char *name)
233 {
234 FILE *fp;
235 int i, retval;
236 char line[100], arg[5][50], *args[5], *p;
237
238 if ((fp = fopen(name, "r")) == NULL)
239 xo_err(1, "cannot open %s", name);
240 args[0] = &arg[0][0];
241 args[1] = &arg[1][0];
242 args[2] = &arg[2][0];
243 args[3] = &arg[3][0];
244 args[4] = &arg[4][0];
245 retval = 0;
246 while(fgets(line, sizeof(line), fp) != NULL) {
247 if ((p = strchr(line, '#')) != NULL)
248 *p = '\0';
249 for (p = line; isblank(*p); p++);
250 if (*p == '\n' || *p == '\0')
251 continue;
252 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
253 arg[2], arg[3], arg[4]);
254 if (i < 2) {
255 xo_warnx("bad line: %s", line);
256 retval = 1;
257 continue;
258 }
259 if (set(i, args))
260 retval = 1;
261 }
262 fclose(fp);
263 return (retval);
264 }
265
266 /*
267 * Given a hostname, fills up a (static) struct sockaddr_in with
268 * the address of the host and returns a pointer to the
269 * structure.
270 */
271 static struct sockaddr_in *
getaddr(char * host)272 getaddr(char *host)
273 {
274 struct hostent *hp;
275 static struct sockaddr_in reply;
276
277 bzero(&reply, sizeof(reply));
278 reply.sin_len = sizeof(reply);
279 reply.sin_family = AF_INET;
280 reply.sin_addr.s_addr = inet_addr(host);
281 if (reply.sin_addr.s_addr == INADDR_NONE) {
282 if (!(hp = gethostbyname(host))) {
283 xo_warnx("%s: %s", host, hstrerror(h_errno));
284 return (NULL);
285 }
286 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
287 sizeof reply.sin_addr);
288 }
289 return (&reply);
290 }
291
292 /*
293 * Returns true if the type is a valid one for ARP.
294 */
295 static int
valid_type(int type)296 valid_type(int type)
297 {
298
299 switch (type) {
300 case IFT_ETHER:
301 case IFT_FDDI:
302 case IFT_IEEE1394:
303 case IFT_INFINIBAND:
304 case IFT_ISO88023:
305 case IFT_ISO88024:
306 case IFT_L2VLAN:
307 case IFT_BRIDGE:
308 return (1);
309 default:
310 return (0);
311 }
312 }
313
314 /*
315 * Set an individual arp entry
316 */
317 static int
set(int argc,char ** argv)318 set(int argc, char **argv)
319 {
320 struct sockaddr_in *addr;
321 struct sockaddr_in *dst; /* what are we looking for */
322 struct sockaddr_dl *sdl;
323 struct rt_msghdr *rtm;
324 struct ether_addr *ea;
325 char *host = argv[0], *eaddr = argv[1];
326 struct sockaddr_dl sdl_m;
327
328 argc -= 2;
329 argv += 2;
330
331 bzero(&sdl_m, sizeof(sdl_m));
332 sdl_m.sdl_len = sizeof(sdl_m);
333 sdl_m.sdl_family = AF_LINK;
334
335 dst = getaddr(host);
336 if (dst == NULL)
337 return (1);
338 doing_proxy = flags = expire_time = 0;
339 while (argc-- > 0) {
340 if (strcmp(argv[0], "temp") == 0) {
341 struct timespec tp;
342 int max_age;
343 size_t len = sizeof(max_age);
344
345 clock_gettime(CLOCK_MONOTONIC, &tp);
346 if (sysctlbyname("net.link.ether.inet.max_age",
347 &max_age, &len, NULL, 0) != 0)
348 xo_err(1, "sysctlbyname");
349 expire_time = tp.tv_sec + max_age;
350 } else if (strcmp(argv[0], "pub") == 0) {
351 flags |= RTF_ANNOUNCE;
352 doing_proxy = 1;
353 if (argc && strcmp(argv[1], "only") == 0) {
354 /*
355 * Compatibility: in pre FreeBSD 8 times
356 * the "only" keyword used to mean that
357 * an ARP entry should be announced, but
358 * not installed into routing table.
359 */
360 argc--; argv++;
361 }
362 } else if (strcmp(argv[0], "blackhole") == 0) {
363 if (flags & RTF_REJECT) {
364 xo_errx(1, "Choose one of blackhole or reject, "
365 "not both.");
366 }
367 flags |= RTF_BLACKHOLE;
368 } else if (strcmp(argv[0], "reject") == 0) {
369 if (flags & RTF_BLACKHOLE) {
370 xo_errx(1, "Choose one of blackhole or reject, "
371 "not both.");
372 }
373 flags |= RTF_REJECT;
374 } else {
375 xo_warnx("Invalid parameter '%s'", argv[0]);
376 usage();
377 }
378 argv++;
379 }
380 ea = (struct ether_addr *)LLADDR(&sdl_m);
381 if (doing_proxy && !strcmp(eaddr, "auto")) {
382 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
383 xo_warnx("no interface found for %s",
384 inet_ntoa(dst->sin_addr));
385 return (1);
386 }
387 sdl_m.sdl_alen = ETHER_ADDR_LEN;
388 } else {
389 struct ether_addr *ea1 = ether_aton(eaddr);
390
391 if (ea1 == NULL) {
392 xo_warnx("invalid Ethernet address '%s'", eaddr);
393 return (1);
394 } else {
395 *ea = *ea1;
396 sdl_m.sdl_alen = ETHER_ADDR_LEN;
397 }
398 }
399
400 /*
401 * In the case a proxy-arp entry is being added for
402 * a remote end point, the RTF_ANNOUNCE flag in the
403 * RTM_GET command is an indication to the kernel
404 * routing code that the interface associated with
405 * the prefix route covering the local end of the
406 * PPP link should be returned, on which ARP applies.
407 */
408 rtm = rtmsg(RTM_GET, dst, NULL);
409 if (rtm == NULL) {
410 xo_warn("%s", host);
411 return (1);
412 }
413 addr = (struct sockaddr_in *)(rtm + 1);
414 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
415
416 if ((sdl->sdl_family != AF_LINK) ||
417 (rtm->rtm_flags & RTF_GATEWAY) ||
418 !valid_type(sdl->sdl_type)) {
419 xo_warnx("cannot intuit interface index and type for %s", host);
420 return (1);
421 }
422 sdl_m.sdl_type = sdl->sdl_type;
423 sdl_m.sdl_index = sdl->sdl_index;
424 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
425 }
426
427 /*
428 * Display an individual arp entry
429 */
430 static int
get(char * host)431 get(char *host)
432 {
433 struct sockaddr_in *addr;
434 int found;
435
436 addr = getaddr(host);
437 if (addr == NULL)
438 return (1);
439
440 xo_set_version(ARP_XO_VERSION);
441 xo_open_container("arp");
442 xo_open_list("arp-cache");
443
444 found = search(addr->sin_addr.s_addr, print_entry);
445
446 if (found == 0) {
447 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry",
448 host, inet_ntoa(addr->sin_addr));
449 if (rifname)
450 xo_emit(" on {d:interface/%s}", rifname);
451 xo_emit("\n");
452 }
453
454 xo_close_list("arp-cache");
455 xo_close_container("arp");
456 xo_finish();
457
458 return (found == 0);
459 }
460
461 /*
462 * Delete an arp entry
463 */
464 static int
delete(char * host)465 delete(char *host)
466 {
467 struct sockaddr_in *addr, *dst;
468 struct rt_msghdr *rtm;
469 struct sockaddr_dl *sdl;
470
471 dst = getaddr(host);
472 if (dst == NULL)
473 return (1);
474
475 /*
476 * Perform a regular entry delete first.
477 */
478 flags &= ~RTF_ANNOUNCE;
479
480 for (;;) { /* try twice */
481 rtm = rtmsg(RTM_GET, dst, NULL);
482 if (rtm == NULL) {
483 xo_warn("%s", host);
484 return (1);
485 }
486 addr = (struct sockaddr_in *)(rtm + 1);
487 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
488
489 /*
490 * With the new L2/L3 restructure, the route
491 * returned is a prefix route. The important
492 * piece of information from the previous
493 * RTM_GET is the interface index. In the
494 * case of ECMP, the kernel will traverse
495 * the route group for the given entry.
496 */
497 if (sdl->sdl_family == AF_LINK &&
498 !(rtm->rtm_flags & RTF_GATEWAY) &&
499 valid_type(sdl->sdl_type) ) {
500 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
501 break;
502 }
503
504 /*
505 * Regular entry delete failed, now check if there
506 * is a proxy-arp entry to remove.
507 */
508 if (flags & RTF_ANNOUNCE) {
509 xo_warnx("delete: cannot locate %s", host);
510 return (1);
511 }
512
513 flags |= RTF_ANNOUNCE;
514 }
515 rtm->rtm_flags |= RTF_LLDATA;
516 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
517 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
518 return (0);
519 }
520 return (1);
521 }
522
523
524 /*
525 * Search the arp table and do some action on matching entries
526 */
527 static int
search(u_long addr,action_fn * action)528 search(u_long addr, action_fn *action)
529 {
530 int mib[6];
531 size_t needed;
532 char *lim, *buf, *next;
533 struct rt_msghdr *rtm;
534 struct sockaddr_in *sin2;
535 struct sockaddr_dl *sdl;
536 char ifname[IF_NAMESIZE];
537 int st, found_entry = 0;
538
539 mib[0] = CTL_NET;
540 mib[1] = PF_ROUTE;
541 mib[2] = 0;
542 mib[3] = AF_INET;
543 mib[4] = NET_RT_FLAGS;
544 #ifdef RTF_LLINFO
545 mib[5] = RTF_LLINFO;
546 #else
547 mib[5] = 0;
548 #endif
549 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
550 xo_err(1, "route-sysctl-estimate");
551 if (needed == 0) /* empty table */
552 return 0;
553 buf = NULL;
554 for (;;) {
555 buf = reallocf(buf, needed);
556 if (buf == NULL)
557 xo_errx(1, "could not reallocate memory");
558 st = sysctl(mib, 6, buf, &needed, NULL, 0);
559 if (st == 0 || errno != ENOMEM)
560 break;
561 needed += needed / 8;
562 }
563 if (st == -1)
564 xo_err(1, "actual retrieval of routing table");
565 lim = buf + needed;
566 for (next = buf; next < lim; next += rtm->rtm_msglen) {
567 rtm = (struct rt_msghdr *)next;
568 sin2 = (struct sockaddr_in *)(rtm + 1);
569 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
570 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
571 strcmp(ifname, rifname))
572 continue;
573 if (addr) {
574 if (addr != sin2->sin_addr.s_addr)
575 continue;
576 found_entry = 1;
577 }
578 (*action)(sdl, sin2, rtm);
579 }
580 free(buf);
581 return (found_entry);
582 }
583
584 /*
585 * Display an arp entry
586 */
587
588 static void
print_entry(struct sockaddr_dl * sdl,struct sockaddr_in * addr,struct rt_msghdr * rtm)589 print_entry(struct sockaddr_dl *sdl,
590 struct sockaddr_in *addr, struct rt_msghdr *rtm)
591 {
592 const char *host;
593 struct hostent *hp;
594 struct if_nameindex *p;
595
596 if (ifnameindex == NULL)
597 if ((ifnameindex = if_nameindex()) == NULL)
598 xo_err(1, "cannot retrieve interface names");
599
600 xo_open_instance("arp-cache");
601
602 if (nflag == 0)
603 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
604 sizeof addr->sin_addr, AF_INET);
605 else
606 hp = 0;
607 if (hp)
608 host = hp->h_name;
609 else {
610 host = "?";
611 if (h_errno == TRY_AGAIN)
612 nflag = 1;
613 }
614 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host,
615 inet_ntoa(addr->sin_addr));
616 if (sdl->sdl_alen) {
617 if ((sdl->sdl_type == IFT_ETHER ||
618 sdl->sdl_type == IFT_L2VLAN ||
619 sdl->sdl_type == IFT_BRIDGE) &&
620 sdl->sdl_alen == ETHER_ADDR_LEN)
621 xo_emit("{:mac-address/%s}",
622 ether_ntoa((struct ether_addr *)LLADDR(sdl)));
623 else {
624 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
625
626 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n);
627 }
628 } else
629 xo_emit("{d:/(incomplete)}{en:incomplete/true}");
630
631 for (p = ifnameindex; p && p->if_index && p->if_name; p++) {
632 if (p->if_index == sdl->sdl_index) {
633 xo_emit(" on {:interface/%s}", p->if_name);
634 break;
635 }
636 }
637
638 if (rtm->rtm_rmx.rmx_expire == 0)
639 xo_emit("{d:/ permanent}{en:permanent/true}");
640 else {
641 static struct timespec tp;
642 if (tp.tv_sec == 0)
643 clock_gettime(CLOCK_MONOTONIC, &tp);
644 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
645 xo_emit(" expires in {:expires/%d} seconds",
646 (int)expire_time);
647 else
648 xo_emit("{d:/ expired}{en:expired/true}");
649 }
650
651 if (rtm->rtm_flags & RTF_ANNOUNCE)
652 xo_emit("{d:/ published}{en:published/true}");
653
654 switch(sdl->sdl_type) {
655 case IFT_ETHER:
656 xo_emit(" [{:type/ethernet}]");
657 break;
658 case IFT_FDDI:
659 xo_emit(" [{:type/fddi}]");
660 break;
661 case IFT_ATM:
662 xo_emit(" [{:type/atm}]");
663 break;
664 case IFT_L2VLAN:
665 xo_emit(" [{:type/vlan}]");
666 break;
667 case IFT_IEEE1394:
668 xo_emit(" [{:type/firewire}]");
669 break;
670 case IFT_BRIDGE:
671 xo_emit(" [{:type/bridge}]");
672 break;
673 case IFT_INFINIBAND:
674 xo_emit(" [{:type/infiniband}]");
675 break;
676 default:
677 break;
678 }
679
680 xo_emit("\n");
681
682 xo_close_instance("arp-cache");
683 }
684
685 /*
686 * Nuke an arp entry
687 */
688 static void
nuke_entry(struct sockaddr_dl * sdl __unused,struct sockaddr_in * addr,struct rt_msghdr * rtm)689 nuke_entry(struct sockaddr_dl *sdl __unused,
690 struct sockaddr_in *addr, struct rt_msghdr *rtm)
691 {
692 char ip[20];
693
694 if (rtm->rtm_flags & RTF_PINNED)
695 return;
696
697 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
698 delete(ip);
699 }
700
701 static void
usage(void)702 usage(void)
703 {
704 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
705 "usage: arp [-n] [-i interface] hostname",
706 " arp [-n] [-i interface] -a",
707 " arp -d hostname [pub]",
708 " arp -d [-i interface] -a",
709 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
710 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
711 " arp -f filename");
712 exit(1);
713 }
714
715 static struct rt_msghdr *
rtmsg(int cmd,struct sockaddr_in * dst,struct sockaddr_dl * sdl)716 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
717 {
718 static int seq;
719 int rlen;
720 int l;
721 static int s = -1;
722 static pid_t pid;
723
724 static struct {
725 struct rt_msghdr m_rtm;
726 char m_space[512];
727 } m_rtmsg;
728
729 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
730 char *cp = m_rtmsg.m_space;
731
732 if (s < 0) { /* first time: open socket, get pid */
733 s = socket(PF_ROUTE, SOCK_RAW, 0);
734 if (s < 0)
735 xo_err(1, "socket");
736 pid = getpid();
737 }
738
739 errno = 0;
740 /*
741 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
742 * appropriately.
743 */
744 if (cmd == RTM_DELETE)
745 goto doit;
746 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
747 rtm->rtm_flags = flags;
748 rtm->rtm_version = RTM_VERSION;
749
750 switch (cmd) {
751 default:
752 xo_errx(1, "internal wrong cmd");
753 case RTM_ADD:
754 rtm->rtm_addrs |= RTA_GATEWAY;
755 rtm->rtm_rmx.rmx_expire = expire_time;
756 rtm->rtm_inits = RTV_EXPIRE;
757 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
758 /* FALLTHROUGH */
759 case RTM_GET:
760 rtm->rtm_addrs |= RTA_DST;
761 }
762 #define NEXTADDR(w, s) \
763 do { \
764 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
765 bcopy((s), cp, sizeof(*(s))); \
766 cp += SA_SIZE(s); \
767 } \
768 } while (0)
769
770 NEXTADDR(RTA_DST, dst);
771 NEXTADDR(RTA_GATEWAY, sdl);
772
773 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
774 doit:
775 l = rtm->rtm_msglen;
776 rtm->rtm_seq = ++seq;
777 rtm->rtm_type = cmd;
778 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
779 if (errno != ESRCH || cmd != RTM_DELETE) {
780 xo_warn("writing to routing socket");
781 return (NULL);
782 }
783 }
784 do {
785 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
786 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq ||
787 rtm->rtm_pid != pid));
788 if (l < 0)
789 xo_warn("read from routing socket");
790 return (rtm);
791 }
792
793 /*
794 * get_ether_addr - get the hardware address of an interface on the
795 * the same subnet as ipaddr.
796 */
797 #define MAX_IFS 32
798
799 static int
get_ether_addr(in_addr_t ipaddr,struct ether_addr * hwaddr)800 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
801 {
802 struct ifreq *ifr, *ifend, *ifp;
803 in_addr_t ina, mask;
804 struct sockaddr_dl *dla;
805 struct ifreq ifreq;
806 struct ifconf ifc;
807 struct ifreq ifs[MAX_IFS];
808 int sock;
809 int retval = 0;
810
811 sock = socket(AF_INET, SOCK_DGRAM, 0);
812 if (sock < 0)
813 xo_err(1, "socket");
814
815 ifc.ifc_len = sizeof(ifs);
816 ifc.ifc_req = ifs;
817 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
818 xo_warnx("ioctl(SIOCGIFCONF)");
819 goto done;
820 }
821
822 #define NEXTIFR(i) \
823 ((struct ifreq *)((char *)&(i)->ifr_addr \
824 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
825
826 /*
827 * Scan through looking for an interface with an Internet
828 * address on the same subnet as `ipaddr'.
829 */
830 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
831 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
832 if (ifr->ifr_addr.sa_family != AF_INET)
833 continue;
834 strncpy(ifreq.ifr_name, ifr->ifr_name,
835 sizeof(ifreq.ifr_name));
836 ifreq.ifr_addr = ifr->ifr_addr;
837 /*
838 * Check that the interface is up,
839 * and not point-to-point or loopback.
840 */
841 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
842 continue;
843 if ((ifreq.ifr_flags &
844 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
845 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST))
846 continue;
847 /* Get its netmask and check that it's on the right subnet. */
848 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
849 continue;
850 mask = ((struct sockaddr_in *)
851 &ifreq.ifr_addr)->sin_addr.s_addr;
852 ina = ((struct sockaddr_in *)
853 &ifr->ifr_addr)->sin_addr.s_addr;
854 if ((ipaddr & mask) == (ina & mask))
855 break; /* ok, we got it! */
856 }
857
858 if (ifr >= ifend)
859 goto done;
860
861 /*
862 * Now scan through again looking for a link-level address
863 * for this interface.
864 */
865 ifp = ifr;
866 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
867 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
868 ifr->ifr_addr.sa_family == AF_LINK)
869 break;
870 if (ifr >= ifend)
871 goto done;
872 /*
873 * Found the link-level address - copy it out
874 */
875 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
876 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
877 printf("using interface %s for proxy with address %s\n", ifp->ifr_name,
878 ether_ntoa(hwaddr));
879 retval = dla->sdl_alen;
880 done:
881 close(sock);
882 return (retval);
883 }
884