Remove some unnecessary casts.
[dragonfly.git] / usr.sbin / arp / arp.c
CommitLineData
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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.
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35 *
36 * @(#) Copyright (c) 1984, 1993 The Regents of the University of California. All rights reserved.
37 * @(#)from: arp.c 8.2 (Berkeley) 1/2/94
38 * $FreeBSD: src/usr.sbin/arp/arp.c,v 1.22.2.12 2003/04/16 10:02:37 ru Exp $
92eb729a 39 * $DragonFly: src/usr.sbin/arp/arp.c,v 1.11 2008/02/03 00:41:44 swildner Exp $
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40 */
41
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42/*
43 * arp - display, set, and delete arp table entries
44 */
45
46
47#include <sys/param.h>
48#include <sys/file.h>
49#include <sys/socket.h>
50#include <sys/sockio.h>
51#include <sys/sysctl.h>
52#include <sys/ioctl.h>
53#include <sys/time.h>
54
55#include <net/if.h>
56#include <net/if_dl.h>
57#include <net/if_types.h>
58#include <net/route.h>
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59
60#include <netinet/in.h>
61#include <netinet/if_ether.h>
62
63#include <arpa/inet.h>
64
65#include <ctype.h>
66#include <err.h>
67#include <errno.h>
68#include <netdb.h>
69#include <nlist.h>
70#include <paths.h>
71#include <stdio.h>
72#include <stdlib.h>
73#include <strings.h>
74#include <unistd.h>
75
76void search(u_long addr, void (*action)(struct sockaddr_dl *sdl,
77 struct sockaddr_inarp *sin, struct rt_msghdr *rtm));
78void print_entry(struct sockaddr_dl *sdl,
79 struct sockaddr_inarp *addr, struct rt_msghdr *rtm);
80void nuke_entry(struct sockaddr_dl *sdl,
81 struct sockaddr_inarp *addr, struct rt_msghdr *rtm);
82int delete(char *host, char *info);
83void usage(void);
84int set(int argc, char **argv);
85int get(char *host);
86int file(char *name);
87void getsocket(void);
88int my_ether_aton(char *a, struct ether_addr *n);
89int rtmsg(int cmd);
90int get_ether_addr(u_int32_t ipaddr, struct ether_addr *hwaddr);
91
92static int pid;
93static int nflag; /* no reverse dns lookups */
94static int aflag; /* do it for all entries */
b06a5e2a 95static int cpuflag = -1;
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96static int s = -1;
97
98struct sockaddr_in so_mask;
99struct sockaddr_inarp blank_sin, sin_m;
100struct sockaddr_dl blank_sdl, sdl_m;
101int expire_time, flags, doing_proxy, proxy_only, found_entry;
102struct {
103 struct rt_msghdr m_rtm;
104 char m_space[512];
105} m_rtmsg;
106
107/* which function we're supposed to do */
108#define F_GET 1
109#define F_SET 2
110#define F_FILESET 3
111#define F_REPLACE 4
112#define F_DELETE 5
113
114#define ROUNDUP(a) \
115 ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
116#define SETFUNC(f) { if (func) usage(); func = (f); }
117
118int
0e2744ff 119main(int argc, char **argv)
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120{
121 int ch, func = 0;
122 int rtn = 0;
123
124 pid = getpid();
b06a5e2a 125 while ((ch = getopt(argc, argv, "ac:ndfsS")) != -1)
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126 switch((char)ch) {
127 case 'a':
128 aflag = 1;
129 break;
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130 case 'c':
131 cpuflag = strtol(optarg, NULL, 0);
132 break;
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133 case 'd':
134 SETFUNC(F_DELETE);
135 break;
136 case 'n':
137 nflag = 1;
138 break;
139 case 'S':
140 SETFUNC(F_REPLACE);
141 break;
142 case 's':
143 SETFUNC(F_SET);
144 break;
145 case 'f' :
146 SETFUNC(F_FILESET);
147 break;
148 case '?':
149 default:
150 usage();
151 }
152 argc -= optind;
153 argv += optind;
154
155 bzero(&so_mask, sizeof(so_mask));
156 so_mask.sin_len = 8;
157 so_mask.sin_addr.s_addr = 0xffffffff;
158 bzero(&blank_sin, sizeof(blank_sin));
159 blank_sin.sin_len = sizeof(blank_sin);
160 blank_sin.sin_family = AF_INET;
161 bzero(&blank_sdl, sizeof(blank_sdl));
162 blank_sdl.sdl_len = sizeof(blank_sdl);
163 blank_sdl.sdl_family = AF_LINK;
164
165 if (!func)
166 func = F_GET;
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 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)
71126e33 184 delete(argv[0], NULL);
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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 || argc > 2)
194 usage();
195 rtn = delete(argv[0], argv[1]);
196 }
197 break;
198 case F_FILESET:
199 if (argc != 1)
200 usage();
201 rtn = file(argv[0]);
202 break;
203 }
204
205 return(rtn);
206}
207
208/*
209 * Process a file to set standard arp entries
210 */
211int
212file(char *name)
213{
214 FILE *fp;
215 int i, retval;
216 char line[100], arg[5][50], *args[5], *p;
217
218 if ((fp = fopen(name, "r")) == NULL)
219 errx(1, "cannot open %s", name);
220 args[0] = &arg[0][0];
221 args[1] = &arg[1][0];
222 args[2] = &arg[2][0];
223 args[3] = &arg[3][0];
224 args[4] = &arg[4][0];
225 retval = 0;
226 while(fgets(line, 100, fp) != NULL) {
227 if ((p = strchr(line, '#')) != NULL)
228 *p = '\0';
229 for (p = line; isblank(*p); p++);
230 if (*p == '\n' || *p == '\0')
231 continue;
232 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
233 arg[2], arg[3], arg[4]);
234 if (i < 2) {
235 warnx("bad line: %s", line);
236 retval = 1;
237 continue;
238 }
239 if (set(i, args))
240 retval = 1;
241 }
242 fclose(fp);
0e2744ff 243 return(retval);
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244}
245
246void
247getsocket(void)
248{
249 if (s < 0) {
250 s = socket(PF_ROUTE, SOCK_RAW, 0);
251 if (s < 0)
252 err(1, "socket");
253 }
254}
255
256/*
257 * Set an individual arp entry
258 */
259int
260set(int argc, char **argv)
261{
262 struct hostent *hp;
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263 struct sockaddr_inarp *addr = &sin_m;
264 struct sockaddr_dl *sdl;
265 struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
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266 struct ether_addr *ea;
267 char *host = argv[0], *eaddr = argv[1];
268
269 getsocket();
270 argc -= 2;
271 argv += 2;
272 sdl_m = blank_sdl;
273 sin_m = blank_sin;
274 addr->sin_addr.s_addr = inet_addr(host);
275 if (addr->sin_addr.s_addr == INADDR_NONE) {
276 if (!(hp = gethostbyname(host))) {
277 warnx("%s: %s", host, hstrerror(h_errno));
0e2744ff 278 return(1);
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279 }
280 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
0e2744ff 281 sizeof(addr->sin_addr));
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282 }
283 doing_proxy = flags = proxy_only = expire_time = 0;
284 while (argc-- > 0) {
285 if (strncmp(argv[0], "temp", 4) == 0) {
286 struct timeval tv;
287 gettimeofday(&tv, 0);
288 expire_time = tv.tv_sec + 20 * 60;
289 }
290 else if (strncmp(argv[0], "pub", 3) == 0) {
291 flags |= RTF_ANNOUNCE;
292 doing_proxy = 1;
293 if (argc && strncmp(argv[1], "only", 3) == 0) {
294 proxy_only = 1;
295 sin_m.sin_other = SIN_PROXY;
296 argc--; argv++;
297 }
298 } else if (strncmp(argv[0], "trail", 5) == 0) {
299 printf("%s: Sending trailers is no longer supported\n",
300 host);
301 }
302 argv++;
303 }
304 ea = (struct ether_addr *)LLADDR(&sdl_m);
305 if (doing_proxy && !strcmp(eaddr, "auto")) {
306 if (!get_ether_addr(addr->sin_addr.s_addr, ea)) {
307 printf("no interface found for %s\n",
308 inet_ntoa(addr->sin_addr));
0e2744ff 309 return(1);
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310 }
311 sdl_m.sdl_alen = ETHER_ADDR_LEN;
312 } else {
313 if (my_ether_aton(eaddr, ea) == 0)
314 sdl_m.sdl_alen = ETHER_ADDR_LEN;
315 }
316tryagain:
317 if (rtmsg(RTM_GET) < 0) {
318 warn("%s", host);
0e2744ff 319 return(1);
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320 }
321 addr = (struct sockaddr_inarp *)(rtm + 1);
322 sdl = (struct sockaddr_dl *)(ROUNDUP(addr->sin_len) + (char *)addr);
323 if (addr->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
324 if (sdl->sdl_family == AF_LINK &&
325 (rtm->rtm_flags & RTF_LLINFO) &&
326 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
327 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
328 case IFT_ISO88024: case IFT_ISO88025: case IFT_L2VLAN:
329 goto overwrite;
330 }
331 if (doing_proxy == 0) {
332 printf("set: can only proxy for %s\n", host);
0e2744ff 333 return(1);
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334 }
335 if (sin_m.sin_other & SIN_PROXY) {
336 printf("set: proxy entry exists for non 802 device\n");
337 return(1);
338 }
339 sin_m.sin_other = SIN_PROXY;
340 proxy_only = 1;
341 goto tryagain;
342 }
343overwrite:
344 if (sdl->sdl_family != AF_LINK) {
345 printf("cannot intuit interface index and type for %s\n", host);
0e2744ff 346 return(1);
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347 }
348 sdl_m.sdl_type = sdl->sdl_type;
349 sdl_m.sdl_index = sdl->sdl_index;
0e2744ff 350 return(rtmsg(RTM_ADD));
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351}
352
353/*
354 * Display an individual arp entry
355 */
356int
357get(char *host)
358{
359 struct hostent *hp;
360 struct sockaddr_inarp *addr = &sin_m;
361
362 sin_m = blank_sin;
363 addr->sin_addr.s_addr = inet_addr(host);
364 if (addr->sin_addr.s_addr == INADDR_NONE) {
365 if (!(hp = gethostbyname(host)))
366 errx(1, "%s: %s", host, hstrerror(h_errno));
367 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
0e2744ff 368 sizeof(addr->sin_addr));
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369 }
370 search(addr->sin_addr.s_addr, print_entry);
371 if (found_entry == 0) {
372 printf("%s (%s) -- no entry\n",
373 host, inet_ntoa(addr->sin_addr));
374 return(1);
375 }
376 return(0);
377}
378
379/*
380 * Delete an arp entry
381 */
382int
383delete(char *host, char *info)
384{
385 struct hostent *hp;
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CP
386 struct sockaddr_inarp *addr = &sin_m;
387 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
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388 struct sockaddr_dl *sdl;
389
390 getsocket();
391 sin_m = blank_sin;
392 if (info) {
393 if (strncmp(info, "pub", 3) == 0)
394 sin_m.sin_other = SIN_PROXY;
395 else
396 usage();
397 }
398 addr->sin_addr.s_addr = inet_addr(host);
399 if (addr->sin_addr.s_addr == INADDR_NONE) {
400 if (!(hp = gethostbyname(host))) {
401 warnx("%s: %s", host, hstrerror(h_errno));
0e2744ff 402 return(1);
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403 }
404 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
0e2744ff 405 sizeof(addr->sin_addr));
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406 }
407tryagain:
408 if (rtmsg(RTM_GET) < 0) {
409 warn("%s", host);
0e2744ff 410 return(1);
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411 }
412 addr = (struct sockaddr_inarp *)(rtm + 1);
413 sdl = (struct sockaddr_dl *)(ROUNDUP(addr->sin_len) + (char *)addr);
414 if (addr->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
415 if (sdl->sdl_family == AF_LINK &&
416 (rtm->rtm_flags & RTF_LLINFO) &&
417 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
418 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
419 case IFT_ISO88024: case IFT_ISO88025: case IFT_L2VLAN:
420 goto delete;
421 }
422 }
423 if (sin_m.sin_other & SIN_PROXY) {
424 fprintf(stderr, "delete: can't locate %s\n",host);
0e2744ff 425 return(1);
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426 } else {
427 sin_m.sin_other = SIN_PROXY;
428 goto tryagain;
429 }
430delete:
431 if (sdl->sdl_family != AF_LINK) {
432 printf("cannot locate %s\n", host);
0e2744ff 433 return(1);
984263bc 434 }
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MD
435 if (aflag && (rtm->rtm_flags & RTF_STATIC)) {
436 sdl->sdl_alen = 0;
437 sdl->sdl_slen = 0;
438 if (rtmsg(RTM_CHANGE) == 0) {
439 printf("%s (%s) cleared\n",
440 host, inet_ntoa(addr->sin_addr));
441 return(0);
442 }
443 } else {
444 if (rtmsg(RTM_DELETE) == 0) {
445 printf("%s (%s) deleted\n",
446 host, inet_ntoa(addr->sin_addr));
447 return(0);
448 }
984263bc 449 }
0e2744ff 450 return(1);
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451}
452
453/*
454 * Search the arp table and do some action on matching entries
455 */
456void
457search(u_long addr, void (*action)(struct sockaddr_dl *sdl,
458 struct sockaddr_inarp *sin, struct rt_msghdr *rtm))
459{
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MD
460 int mib[7];
461 int miblen;
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462 size_t needed;
463 char *lim, *buf, *next;
464 struct rt_msghdr *rtm;
465 struct sockaddr_inarp *sin2;
466 struct sockaddr_dl *sdl;
467
468 mib[0] = CTL_NET;
469 mib[1] = PF_ROUTE;
470 mib[2] = 0;
471 mib[3] = AF_INET;
472 mib[4] = NET_RT_FLAGS;
473 mib[5] = RTF_LLINFO;
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MD
474 if (cpuflag >= 0) {
475 mib[6] = cpuflag;
476 miblen = 7;
477 } else {
478 miblen = 6;
479 }
480 if (sysctl(mib, miblen, NULL, &needed, NULL, 0) < 0)
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481 errx(1, "route-sysctl-estimate");
482 if ((buf = malloc(needed)) == NULL)
483 errx(1, "malloc");
b06a5e2a 484 if (sysctl(mib, miblen, buf, &needed, NULL, 0) < 0)
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485 errx(1, "actual retrieval of routing table");
486 lim = buf + needed;
487 for (next = buf; next < lim; next += rtm->rtm_msglen) {
488 rtm = (struct rt_msghdr *)next;
489 sin2 = (struct sockaddr_inarp *)(rtm + 1);
973543dc 490 sdl = (struct sockaddr_dl *)((char *)sin2 + ROUNDUP(sin2->sin_len));
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491 if (addr) {
492 if (addr != sin2->sin_addr.s_addr)
493 continue;
494 found_entry = 1;
495 }
496 (*action)(sdl, sin2, rtm);
497 }
498 free(buf);
499}
500
501/*
502 * Display an arp entry
503 */
504void
505print_entry(struct sockaddr_dl *sdl,
506 struct sockaddr_inarp *addr, struct rt_msghdr *rtm)
507{
508 const char *host;
509 struct hostent *hp;
984263bc 510 char ifname[IF_NAMESIZE];
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511
512 if (nflag == 0)
15b85273
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513 hp = gethostbyaddr(&(addr->sin_addr), sizeof(addr->sin_addr),
514 AF_INET);
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515 else
516 hp = 0;
517 if (hp)
518 host = hp->h_name;
519 else {
520 host = "?";
521 if (h_errno == TRY_AGAIN)
522 nflag = 1;
523 }
524 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
525 if (sdl->sdl_alen)
526 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
527 else
528 printf("(incomplete)");
529 if (if_indextoname(sdl->sdl_index, ifname) != NULL)
530 printf(" on %s", ifname);
531 if (rtm->rtm_rmx.rmx_expire == 0)
532 printf(" permanent");
533 if (addr->sin_other & SIN_PROXY)
534 printf(" published (proxy only)");
535 if (rtm->rtm_addrs & RTA_NETMASK) {
536 addr = (struct sockaddr_inarp *)
537 (ROUNDUP(sdl->sdl_len) + (char *)sdl);
538 if (addr->sin_addr.s_addr == 0xffffffff)
539 printf(" published");
540 if (addr->sin_len != 8)
541 printf("(weird)");
542 }
543 switch(sdl->sdl_type) {
544 case IFT_ETHER:
545 printf(" [ethernet]");
546 break;
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547 case IFT_L2VLAN:
548 printf(" [vlan]");
549 break;
550 default:
32e581b8 551 break;
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552 }
553
554 printf("\n");
555
556}
557
558/*
559 * Nuke an arp entry
560 */
561void
562nuke_entry(struct sockaddr_dl *sdl __unused,
563 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused)
564{
565 char ip[20];
566
567 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
568 delete(ip, NULL);
569}
570
571int
572my_ether_aton(char *a, struct ether_addr *n)
573{
574 struct ether_addr *ea;
575
576 if ((ea = ether_aton(a)) == NULL) {
577 warnx("invalid Ethernet address '%s'", a);
0e2744ff 578 return(1);
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579 }
580 *n = *ea;
0e2744ff 581 return(0);
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582}
583
584void
585usage(void)
586{
587 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
c27f6487
TN
588 "usage: arp [-n] [-c cpu] hostname",
589 " arp [-n] [-c cpu] -a",
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590 " arp -d hostname [pub]",
591 " arp -d -a",
c27f6487
TN
592 " arp -s hostname ether_addr [temp] [pub [only]]",
593 " arp -S hostname ether_addr [temp] [pub [only]]",
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594 " arp -f filename");
595 exit(1);
596}
597
598int
599rtmsg(int cmd)
600{
601 static int seq;
602 int rlen;
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CP
603 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
604 char *cp = m_rtmsg.m_space;
605 int l;
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606
607 errno = 0;
03f869ef 608 if (cmd == RTM_DELETE || cmd == RTM_CHANGE)
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609 goto doit;
610 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
611 rtm->rtm_flags = flags;
612 rtm->rtm_version = RTM_VERSION;
613
614 switch (cmd) {
615 default:
616 errx(1, "internal wrong cmd");
617 case RTM_ADD:
618 rtm->rtm_addrs |= RTA_GATEWAY;
619 rtm->rtm_rmx.rmx_expire = expire_time;
620 rtm->rtm_inits = RTV_EXPIRE;
621 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
622 sin_m.sin_other = 0;
623 if (doing_proxy) {
624 if (proxy_only)
625 sin_m.sin_other = SIN_PROXY;
626 else {
627 rtm->rtm_addrs |= RTA_NETMASK;
628 rtm->rtm_flags &= ~RTF_HOST;
629 }
630 }
631 /* FALLTHROUGH */
632 case RTM_GET:
633 rtm->rtm_addrs |= RTA_DST;
634 }
635#define NEXTADDR(w, s) \
636 if (rtm->rtm_addrs & (w)) { \
637 bcopy((char *)&s, cp, sizeof(s)); cp += ROUNDUP(sizeof(s));}
638
639 NEXTADDR(RTA_DST, sin_m);
640 NEXTADDR(RTA_GATEWAY, sdl_m);
641 NEXTADDR(RTA_NETMASK, so_mask);
642
643 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
644doit:
645 l = rtm->rtm_msglen;
646 rtm->rtm_seq = ++seq;
647 rtm->rtm_type = cmd;
648 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
03f869ef 649 if (errno != ESRCH || (cmd != RTM_DELETE && cmd != RTM_CHANGE)) {
984263bc 650 warn("writing to routing socket");
0e2744ff 651 return(-1);
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MD
652 }
653 }
654 do {
655 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
656 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
657 if (l < 0)
658 warn("read from routing socket");
0e2744ff 659 return(0);
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660}
661
662/*
663 * get_ether_addr - get the hardware address of an interface on the
664 * the same subnet as ipaddr.
665 */
666#define MAX_IFS 32
667
668int
669get_ether_addr(u_int32_t ipaddr, struct ether_addr *hwaddr)
670{
671 struct ifreq *ifr, *ifend, *ifp;
672 u_int32_t ina, mask;
673 struct sockaddr_dl *dla;
674 struct ifreq ifreq;
675 struct ifconf ifc;
676 struct ifreq ifs[MAX_IFS];
677 int sock;
678
679 sock = socket(AF_INET, SOCK_DGRAM, 0);
680 if (sock < 0)
681 err(1, "socket");
682
683 ifc.ifc_len = sizeof(ifs);
684 ifc.ifc_req = ifs;
685 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
686 warnx("ioctl(SIOCGIFCONF)");
687 close(sock);
0e2744ff 688 return(0);
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689 }
690
691 /*
692 * Scan through looking for an interface with an Internet
693 * address on the same subnet as `ipaddr'.
694 */
695 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
696 for (ifr = ifc.ifc_req; ifr < ifend; ) {
697 if (ifr->ifr_addr.sa_family == AF_INET) {
698 ina = ((struct sockaddr_in *)
699 &ifr->ifr_addr)->sin_addr.s_addr;
700 strncpy(ifreq.ifr_name, ifr->ifr_name,
701 sizeof(ifreq.ifr_name));
702 /*
703 * Check that the interface is up,
704 * and not point-to-point or loopback.
705 */
706 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
707 continue;
708 if ((ifreq.ifr_flags &
709 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
710 IFF_LOOPBACK|IFF_NOARP))
711 != (IFF_UP|IFF_BROADCAST))
712 goto nextif;
713 /*
714 * Get its netmask and check that it's on
715 * the right subnet.
716 */
717 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
718 continue;
719 mask = ((struct sockaddr_in *)
720 &ifreq.ifr_addr)->sin_addr.s_addr;
721 if ((ipaddr & mask) != (ina & mask))
722 goto nextif;
723 break;
724 }
725nextif:
726 ifr = (struct ifreq *) ((char *)&ifr->ifr_addr
727 + MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr)));
728 }
729
730 if (ifr >= ifend) {
731 close(sock);
0e2744ff 732 return(0);
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733 }
734
735 /*
736 * Now scan through again looking for a link-level address
737 * for this interface.
738 */
739 ifp = ifr;
740 for (ifr = ifc.ifc_req; ifr < ifend; ) {
741 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0
742 && ifr->ifr_addr.sa_family == AF_LINK) {
743 /*
744 * Found the link-level address - copy it out
745 */
746 dla = (struct sockaddr_dl *) &ifr->ifr_addr;
747 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
748 close (sock);
749 printf("using interface %s for proxy with address ",
750 ifp->ifr_name);
751 printf("%s\n", ether_ntoa(hwaddr));
0e2744ff 752 return(dla->sdl_alen);
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753 }
754 ifr = (struct ifreq *) ((char *)&ifr->ifr_addr
755 + MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr)));
756 }
0e2744ff 757 return(0);
984263bc 758}