arp.c revision 44627
1/* 2 * Copyright (c) 1984, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Sun Microsystems, Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#ifndef lint 38static char const copyright[] = 39"@(#) Copyright (c) 1984, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41#endif /* not lint */ 42 43#ifndef lint 44#if 0 45static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; 46#endif 47static const char rcsid[] = 48 "$Id: arp.c,v 1.14 1998/01/16 17:38:51 bde Exp $"; 49#endif /* not lint */ 50 51/* 52 * arp - display, set, and delete arp table entries 53 */ 54 55 56#include <sys/param.h> 57#include <sys/file.h> 58#include <sys/socket.h> 59#include <sys/sockio.h> 60#include <sys/sysctl.h> 61#include <sys/ioctl.h> 62#include <sys/time.h> 63 64#include <net/if.h> 65#include <net/if_dl.h> 66#include <net/if_types.h> 67#include <net/route.h> 68 69#include <netinet/in.h> 70#include <netinet/if_ether.h> 71 72#include <arpa/inet.h> 73 74#include <err.h> 75#include <errno.h> 76#include <netdb.h> 77#include <nlist.h> 78#include <paths.h> 79#include <stdio.h> 80#include <stdlib.h> 81#include <strings.h> 82#include <unistd.h> 83 84void search(u_long addr, void (*action)(struct sockaddr_dl *sdl, 85 struct sockaddr_inarp *sin, struct rt_msghdr *rtm)); 86void print_entry(struct sockaddr_dl *sdl, 87 struct sockaddr_inarp *sin, struct rt_msghdr *rtm); 88void nuke_entry(struct sockaddr_dl *sdl, 89 struct sockaddr_inarp *sin, struct rt_msghdr *rtm); 90int delete(char *host, char *info); 91void ether_print(u_char *cp); 92void usage(void); 93int set(int argc, char **argv); 94int get(char *host); 95int file(char *name); 96void getsocket(void); 97int my_ether_aton(char *a, u_char *n); 98int rtmsg(int cmd); 99int get_ether_addr(u_long ipaddr, u_char *hwaddr); 100 101static int pid; 102static int nflag; /* no reverse dns lookups */ 103static int aflag; /* do it for all entries */ 104static int s = -1; 105 106/* which function we're supposed to do */ 107#define F_GET 1 108#define F_SET 2 109#define F_FILESET 3 110#define F_REPLACE 4 111#define F_DELETE 5 112 113#define SETFUNC(f) { if (func) usage(); func = (f); } 114 115int 116main(argc, argv) 117 int argc; 118 char **argv; 119{ 120 int ch, func = 0; 121 int rtn = 0; 122 123 pid = getpid(); 124 while ((ch = getopt(argc, argv, "andfsS")) != -1) 125 switch((char)ch) { 126 case 'a': 127 aflag = 1; 128 break; 129 case 'd': 130 SETFUNC(F_DELETE); 131 break; 132 case 'n': 133 nflag = 1; 134 break; 135 case 'S': 136 SETFUNC(F_REPLACE); 137 break; 138 case 's': 139 SETFUNC(F_SET); 140 break; 141 case 'f' : 142 SETFUNC(F_FILESET); 143 break; 144 case '?': 145 default: 146 usage(); 147 } 148 argc -= optind; 149 argv += optind; 150 151 if (!func) 152 func = F_GET; 153 switch (func) { 154 case F_GET: 155 if (aflag) { 156 if (argc != 0) 157 usage(); 158 search(0, print_entry); 159 } else { 160 if (argc != 1) 161 usage(); 162 get(argv[0]); 163 } 164 break; 165 case F_SET: 166 case F_REPLACE: 167 if (argc < 2 || argc > 5) 168 usage(); 169 if (func == F_REPLACE) 170 (void) delete(argv[0], NULL); 171 rtn = set(argc, argv) ? 1 : 0; 172 break; 173 case F_DELETE: 174 if (aflag) { 175 if (argc != 0) 176 usage(); 177 search(0, nuke_entry); 178 } else { 179 if (argc < 1 || argc > 2) 180 usage(); 181 rtn = delete(argv[0], argv[1]); 182 } 183 break; 184 case F_FILESET: 185 if (argc != 1) 186 usage(); 187 rtn = file(argv[0]); 188 break; 189 } 190 191 return(rtn); 192} 193 194/* 195 * Process a file to set standard arp entries 196 */ 197int 198file(char *name) 199{ 200 FILE *fp; 201 int i, retval; 202 char line[100], arg[5][50], *args[5]; 203 204 if ((fp = fopen(name, "r")) == NULL) 205 errx(1, "cannot open %s", name); 206 args[0] = &arg[0][0]; 207 args[1] = &arg[1][0]; 208 args[2] = &arg[2][0]; 209 args[3] = &arg[3][0]; 210 args[4] = &arg[4][0]; 211 retval = 0; 212 while(fgets(line, 100, fp) != NULL) { 213 i = sscanf(line, "%s %s %s %s %s", arg[0], arg[1], arg[2], 214 arg[3], arg[4]); 215 if (i < 2) { 216 warnx("bad line: %s", line); 217 retval = 1; 218 continue; 219 } 220 if (set(i, args)) 221 retval = 1; 222 } 223 fclose(fp); 224 return (retval); 225} 226 227void 228getsocket(void) 229{ 230 if (s < 0) { 231 s = socket(PF_ROUTE, SOCK_RAW, 0); 232 if (s < 0) 233 err(1, "socket"); 234 } 235} 236 237struct sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}}; 238struct sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m; 239struct sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m; 240int expire_time, flags, export_only, doing_proxy, found_entry; 241struct { 242 struct rt_msghdr m_rtm; 243 char m_space[512]; 244} m_rtmsg; 245 246/* 247 * Set an individual arp entry 248 */ 249int 250set(int argc, char **argv) 251{ 252 struct hostent *hp; 253 register struct sockaddr_inarp *sin = &sin_m; 254 register struct sockaddr_dl *sdl; 255 register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm); 256 u_char *ea; 257 char *host = argv[0], *eaddr = argv[1]; 258 259 getsocket(); 260 argc -= 2; 261 argv += 2; 262 sdl_m = blank_sdl; 263 sin_m = blank_sin; 264 sin->sin_addr.s_addr = inet_addr(host); 265 if (sin->sin_addr.s_addr == -1) { 266 if (!(hp = gethostbyname(host))) { 267 warnx("%s: %s", host, hstrerror(h_errno)); 268 return (1); 269 } 270 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 271 sizeof sin->sin_addr); 272 } 273 doing_proxy = flags = export_only = expire_time = 0; 274 while (argc-- > 0) { 275 if (strncmp(argv[0], "temp", 4) == 0) { 276 struct timeval time; 277 gettimeofday(&time, 0); 278 expire_time = time.tv_sec + 20 * 60; 279 } 280 else if (strncmp(argv[0], "pub", 3) == 0) { 281 flags |= RTF_ANNOUNCE; 282 doing_proxy = SIN_PROXY; 283 } else if (strncmp(argv[0], "trail", 5) == 0) { 284 printf("%s: Sending trailers is no longer supported\n", 285 host); 286 } 287 argv++; 288 } 289 ea = (u_char *)LLADDR(&sdl_m); 290 if (doing_proxy && !strcmp(eaddr, "auto")) { 291 if (!get_ether_addr(sin->sin_addr.s_addr, ea)) { 292 return (1); 293 } 294 sdl_m.sdl_alen = 6; 295 } else { 296 if (my_ether_aton(eaddr, ea) == 0) 297 sdl_m.sdl_alen = 6; 298 } 299tryagain: 300 if (rtmsg(RTM_GET) < 0) { 301 warn("%s", host); 302 return (1); 303 } 304 sin = (struct sockaddr_inarp *)(rtm + 1); 305 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 306 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 307 if (sdl->sdl_family == AF_LINK && 308 (rtm->rtm_flags & RTF_LLINFO) && 309 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 310 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 311 case IFT_ISO88024: case IFT_ISO88025: 312 goto overwrite; 313 } 314 if (doing_proxy == 0) { 315 printf("set: can only proxy for %s\n", host); 316 return (1); 317 } 318 if (sin_m.sin_other & SIN_PROXY) { 319 printf("set: proxy entry exists for non 802 device\n"); 320 return(1); 321 } 322 sin_m.sin_other = SIN_PROXY; 323 export_only = 1; 324 goto tryagain; 325 } 326overwrite: 327 if (sdl->sdl_family != AF_LINK) { 328 printf("cannot intuit interface index and type for %s\n", host); 329 return (1); 330 } 331 sdl_m.sdl_type = sdl->sdl_type; 332 sdl_m.sdl_index = sdl->sdl_index; 333 return (rtmsg(RTM_ADD)); 334} 335 336/* 337 * Display an individual arp entry 338 */ 339int 340get(char *host) 341{ 342 struct hostent *hp; 343 struct sockaddr_inarp *sin = &sin_m; 344 345 sin_m = blank_sin; 346 sin->sin_addr.s_addr = inet_addr(host); 347 if (sin->sin_addr.s_addr == -1) { 348 if (!(hp = gethostbyname(host))) 349 errx(1, "%s: %s", host, hstrerror(h_errno)); 350 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 351 sizeof sin->sin_addr); 352 } 353 search(sin->sin_addr.s_addr, print_entry); 354 if (found_entry == 0) { 355 printf("%s (%s) -- no entry\n", 356 host, inet_ntoa(sin->sin_addr)); 357 return(1); 358 } 359 return(0); 360} 361 362/* 363 * Delete an arp entry 364 */ 365int 366delete(char *host, char *info) 367{ 368 struct hostent *hp; 369 register struct sockaddr_inarp *sin = &sin_m; 370 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 371 struct sockaddr_dl *sdl; 372 373 if (info && strncmp(info, "pro", 3) ) 374 export_only = 1; 375 getsocket(); 376 sin_m = blank_sin; 377 sin->sin_addr.s_addr = inet_addr(host); 378 if (sin->sin_addr.s_addr == -1) { 379 if (!(hp = gethostbyname(host))) { 380 warnx("%s: %s", host, hstrerror(h_errno)); 381 return (1); 382 } 383 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 384 sizeof sin->sin_addr); 385 } 386tryagain: 387 if (rtmsg(RTM_GET) < 0) { 388 warn("%s", host); 389 return (1); 390 } 391 sin = (struct sockaddr_inarp *)(rtm + 1); 392 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 393 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 394 if (sdl->sdl_family == AF_LINK && 395 (rtm->rtm_flags & RTF_LLINFO) && 396 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 397 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 398 case IFT_ISO88024: case IFT_ISO88025: 399 goto delete; 400 } 401 } 402 if (sin_m.sin_other & SIN_PROXY) { 403 fprintf(stderr, "delete: can't locate %s\n",host); 404 return (1); 405 } else { 406 sin_m.sin_other = SIN_PROXY; 407 goto tryagain; 408 } 409delete: 410 if (sdl->sdl_family != AF_LINK) { 411 printf("cannot locate %s\n", host); 412 return (1); 413 } 414 if (rtmsg(RTM_DELETE) == 0) { 415 printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr)); 416 return (0); 417 } 418 return (1); 419} 420 421/* 422 * Search the arp table and do some action on matching entries 423 */ 424void 425search(u_long addr, void (*action)(struct sockaddr_dl *sdl, 426 struct sockaddr_inarp *sin, struct rt_msghdr *rtm)) 427{ 428 int mib[6]; 429 size_t needed; 430 char *lim, *buf, *next; 431 struct rt_msghdr *rtm; 432 struct sockaddr_inarp *sin; 433 struct sockaddr_dl *sdl; 434 extern int h_errno; 435 436 mib[0] = CTL_NET; 437 mib[1] = PF_ROUTE; 438 mib[2] = 0; 439 mib[3] = AF_INET; 440 mib[4] = NET_RT_FLAGS; 441 mib[5] = RTF_LLINFO; 442 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 443 errx(1, "route-sysctl-estimate"); 444 if ((buf = malloc(needed)) == NULL) 445 errx(1, "malloc"); 446 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 447 errx(1, "actual retrieval of routing table"); 448 lim = buf + needed; 449 for (next = buf; next < lim; next += rtm->rtm_msglen) { 450 rtm = (struct rt_msghdr *)next; 451 sin = (struct sockaddr_inarp *)(rtm + 1); 452 sdl = (struct sockaddr_dl *)(sin + 1); 453 if (addr) { 454 if (addr != sin->sin_addr.s_addr) 455 continue; 456 found_entry = 1; 457 } 458 (*action)(sdl, sin, rtm); 459 } 460} 461 462/* 463 * Display an arp entry 464 */ 465void 466print_entry(struct sockaddr_dl *sdl, 467 struct sockaddr_inarp *sin, struct rt_msghdr *rtm) 468{ 469 char *host; 470 extern int h_errno; 471 struct hostent *hp; 472 int seg; 473 474 if (nflag == 0) 475 hp = gethostbyaddr((caddr_t)&(sin->sin_addr), 476 sizeof sin->sin_addr, AF_INET); 477 else 478 hp = 0; 479 if (hp) 480 host = hp->h_name; 481 else { 482 host = "?"; 483 if (h_errno == TRY_AGAIN) 484 nflag = 1; 485 } 486 printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr)); 487 if (sdl->sdl_alen) 488 ether_print(LLADDR(sdl)); 489 else 490 printf("(incomplete)"); 491 if (rtm->rtm_rmx.rmx_expire == 0) 492 printf(" permanent"); 493 if (sin->sin_other & SIN_PROXY) 494 printf(" published (proxy only)"); 495 if (rtm->rtm_addrs & RTA_NETMASK) { 496 sin = (struct sockaddr_inarp *) 497 (sdl->sdl_len + (char *)sdl); 498 if (sin->sin_addr.s_addr == 0xffffffff) 499 printf(" published"); 500 if (sin->sin_len != 8) 501 printf("(wierd)"); 502 } 503 switch(sdl->sdl_type) { 504 case IFT_ETHER: 505 printf(" [ethernet]"); 506 break; 507 case IFT_ISO88025: 508 printf(" [token-ring]"); 509 break; 510 default: 511 } 512 if (sdl->sdl_rcf != NULL) { 513 printf(" rt=%x", ntohs(sdl->sdl_rcf)); 514 for (seg = 0; seg < ((((ntohs(sdl->sdl_rcf) & 0x1f00) >> 8) - 2 ) / 2); seg++) 515 printf(":%x", ntohs(sdl->sdl_route[seg])); 516 } 517 518 printf("\n"); 519 520} 521 522/* 523 * Nuke an arp entry 524 */ 525void 526nuke_entry(struct sockaddr_dl *sdl, 527 struct sockaddr_inarp *sin, struct rt_msghdr *rtm) 528{ 529 char ip[20]; 530 531 snprintf(ip, sizeof(ip), "%s", inet_ntoa(sin->sin_addr)); 532 delete(ip, NULL); 533} 534 535void 536ether_print(u_char *cp) 537{ 538 printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]); 539} 540 541int 542my_ether_aton(char *a, u_char *n) 543{ 544 int i, o[6]; 545 546 i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2], 547 &o[3], &o[4], &o[5]); 548 if (i != 6) { 549 warnx("invalid Ethernet address '%s'", a); 550 return (1); 551 } 552 for (i=0; i<6; i++) 553 n[i] = o[i]; 554 return (0); 555} 556 557void 558usage(void) 559{ 560 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 561 "usage: arp [-n] hostname", 562 " arp [-n] -a", 563 " arp -d hostname [proxy]", 564 " arp -d -a", 565 " arp -s hostname ether_addr [temp] [pub]", 566 " arp -S hostname ether_addr [temp] [pub]", 567 " arp -f filename"); 568 exit(1); 569} 570 571int 572rtmsg(int cmd) 573{ 574 static int seq; 575 int rlen; 576 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 577 register char *cp = m_rtmsg.m_space; 578 register int l; 579 580 errno = 0; 581 if (cmd == RTM_DELETE) 582 goto doit; 583 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 584 rtm->rtm_flags = flags; 585 rtm->rtm_version = RTM_VERSION; 586 587 switch (cmd) { 588 default: 589 errx(1, "internal wrong cmd"); 590 case RTM_ADD: 591 rtm->rtm_addrs |= RTA_GATEWAY; 592 rtm->rtm_rmx.rmx_expire = expire_time; 593 rtm->rtm_inits = RTV_EXPIRE; 594 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 595 sin_m.sin_other = 0; 596 if (doing_proxy) { 597 if (export_only) 598 sin_m.sin_other = SIN_PROXY; 599 else { 600 rtm->rtm_addrs |= RTA_NETMASK; 601 rtm->rtm_flags &= ~RTF_HOST; 602 } 603 } 604 /* FALLTHROUGH */ 605 case RTM_GET: 606 rtm->rtm_addrs |= RTA_DST; 607 } 608#define NEXTADDR(w, s) \ 609 if (rtm->rtm_addrs & (w)) { \ 610 bcopy((char *)&s, cp, sizeof(s)); cp += sizeof(s);} 611 612 NEXTADDR(RTA_DST, sin_m); 613 NEXTADDR(RTA_GATEWAY, sdl_m); 614 NEXTADDR(RTA_NETMASK, so_mask); 615 616 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 617doit: 618 l = rtm->rtm_msglen; 619 rtm->rtm_seq = ++seq; 620 rtm->rtm_type = cmd; 621 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 622 if (errno != ESRCH || cmd != RTM_DELETE) { 623 warn("writing to routing socket"); 624 return (-1); 625 } 626 } 627 do { 628 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 629 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 630 if (l < 0) 631 warn("read from routing socket"); 632 return (0); 633} 634 635/* 636 * get_ether_addr - get the hardware address of an interface on the 637 * the same subnet as ipaddr. 638 */ 639#define MAX_IFS 32 640 641int 642get_ether_addr(u_long ipaddr, u_char *hwaddr) 643{ 644 struct ifreq *ifr, *ifend, *ifp; 645 u_long ina, mask; 646 struct sockaddr_dl *dla; 647 struct ifreq ifreq; 648 struct ifconf ifc; 649 struct ifreq ifs[MAX_IFS]; 650 int s; 651 652 s = socket(AF_INET, SOCK_DGRAM, 0); 653 if (s < 0) 654 err(1, "socket"); 655 656 ifc.ifc_len = sizeof(ifs); 657 ifc.ifc_req = ifs; 658 if (ioctl(s, SIOCGIFCONF, &ifc) < 0) { 659 warnx("ioctl(SIOCGIFCONF)"); 660 close(s); 661 return 0; 662 } 663 664 /* 665 * Scan through looking for an interface with an Internet 666 * address on the same subnet as `ipaddr'. 667 */ 668 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len); 669 for (ifr = ifc.ifc_req; ifr < ifend; ) { 670 if (ifr->ifr_addr.sa_family == AF_INET) { 671 ina = ((struct sockaddr_in *) 672 &ifr->ifr_addr)->sin_addr.s_addr; 673 strncpy(ifreq.ifr_name, ifr->ifr_name, 674 sizeof(ifreq.ifr_name)); 675 /* 676 * Check that the interface is up, 677 * and not point-to-point or loopback. 678 */ 679 if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0) 680 continue; 681 if ((ifreq.ifr_flags & 682 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 683 IFF_LOOPBACK|IFF_NOARP)) 684 != (IFF_UP|IFF_BROADCAST)) 685 goto nextif; 686 /* 687 * Get its netmask and check that it's on 688 * the right subnet. 689 */ 690 if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0) 691 continue; 692 mask = ((struct sockaddr_in *) 693 &ifreq.ifr_addr)->sin_addr.s_addr; 694 if ((ipaddr & mask) != (ina & mask)) 695 goto nextif; 696 break; 697 } 698nextif: 699 ifr = (struct ifreq *) 700 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 701 } 702 703 if (ifr >= ifend) { 704 close(s); 705 return 0; 706 } 707 708 /* 709 * Now scan through again looking for a link-level address 710 * for this interface. 711 */ 712 ifp = ifr; 713 for (ifr = ifc.ifc_req; ifr < ifend; ) { 714 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 715 && ifr->ifr_addr.sa_family == AF_LINK) { 716 /* 717 * Found the link-level address - copy it out 718 */ 719 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 720 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 721 close (s); 722 printf("using interface %s for proxy with address ", 723 ifp->ifr_name); 724 ether_print(hwaddr); 725 printf("\n"); 726 return dla->sdl_alen; 727 } 728 ifr = (struct ifreq *) 729 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 730 } 731 return 0; 732} 733