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 * @(#) 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 $ 39 * $DragonFly: src/usr.sbin/arp/arp.c,v 1.11 2008/02/03 00:41:44 swildner Exp $ 40 */ 41 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> 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 <string.h> 74 #include <unistd.h> 75 76 void search(u_long addr, void (*action)(struct sockaddr_dl *sdl, 77 struct sockaddr_inarp *sin, struct rt_msghdr *rtm)); 78 void print_entry(struct sockaddr_dl *sdl, 79 struct sockaddr_inarp *addr, struct rt_msghdr *rtm); 80 void nuke_entry(struct sockaddr_dl *sdl, 81 struct sockaddr_inarp *addr, struct rt_msghdr *rtm); 82 int delete(char *host, char *info); 83 void usage(void); 84 int set(int argc, char **argv); 85 int get(char *host); 86 int file(char *name); 87 void getsocket(void); 88 int my_ether_aton(char *a, struct ether_addr *n); 89 int rtmsg(int cmd); 90 int get_ether_addr(u_int32_t ipaddr, struct ether_addr *hwaddr); 91 92 static int pid; 93 static int nflag; /* no reverse dns lookups */ 94 static int aflag; /* do it for all entries */ 95 static int cpuflag = -1; 96 static int s = -1; 97 98 struct sockaddr_in so_mask; 99 struct sockaddr_inarp blank_sin, sin_m; 100 struct sockaddr_dl blank_sdl, sdl_m; 101 int expire_time, flags, doing_proxy, proxy_only, found_entry; 102 struct { 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); } 117 118 int 119 main(int argc, char **argv) 120 { 121 int ch, func = 0; 122 int rtn = 0; 123 124 pid = getpid(); 125 while ((ch = getopt(argc, argv, "ac:ndfsS")) != -1) 126 switch((char)ch) { 127 case 'a': 128 aflag = 1; 129 break; 130 case 'c': 131 cpuflag = strtol(optarg, NULL, 0); 132 break; 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) 184 delete(argv[0], NULL); 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 */ 211 int 212 file(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); 243 return(retval); 244 } 245 246 void 247 getsocket(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 */ 259 int 260 set(int argc, char **argv) 261 { 262 struct hostent *hp; 263 struct sockaddr_inarp *addr = &sin_m; 264 struct sockaddr_dl *sdl; 265 struct rt_msghdr *rtm = &(m_rtmsg.m_rtm); 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)); 278 return(1); 279 } 280 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr, 281 sizeof(addr->sin_addr)); 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)); 309 return(1); 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 } 316 tryagain: 317 if (rtmsg(RTM_GET) < 0) { 318 warn("%s", host); 319 return(1); 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 case IFT_CARP: 330 goto overwrite; 331 } 332 if (doing_proxy == 0) { 333 printf("set: can only proxy for %s\n", host); 334 return(1); 335 } 336 if (sin_m.sin_other & SIN_PROXY) { 337 printf("set: proxy entry exists for non 802 device\n"); 338 return(1); 339 } 340 sin_m.sin_other = SIN_PROXY; 341 proxy_only = 1; 342 goto tryagain; 343 } 344 overwrite: 345 if (sdl->sdl_family != AF_LINK) { 346 printf("cannot intuit interface index and type for %s\n", host); 347 return(1); 348 } 349 sdl_m.sdl_type = sdl->sdl_type; 350 sdl_m.sdl_index = sdl->sdl_index; 351 return(rtmsg(RTM_ADD)); 352 } 353 354 /* 355 * Display an individual arp entry 356 */ 357 int 358 get(char *host) 359 { 360 struct hostent *hp; 361 struct sockaddr_inarp *addr = &sin_m; 362 363 sin_m = blank_sin; 364 addr->sin_addr.s_addr = inet_addr(host); 365 if (addr->sin_addr.s_addr == INADDR_NONE) { 366 if (!(hp = gethostbyname(host))) 367 errx(1, "%s: %s", host, hstrerror(h_errno)); 368 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr, 369 sizeof(addr->sin_addr)); 370 } 371 search(addr->sin_addr.s_addr, print_entry); 372 if (found_entry == 0) { 373 printf("%s (%s) -- no entry\n", 374 host, inet_ntoa(addr->sin_addr)); 375 return(1); 376 } 377 return(0); 378 } 379 380 /* 381 * Delete an arp entry 382 */ 383 int 384 delete(char *host, char *info) 385 { 386 struct hostent *hp; 387 struct sockaddr_inarp *addr = &sin_m; 388 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 389 struct sockaddr_dl *sdl; 390 391 getsocket(); 392 sin_m = blank_sin; 393 if (info) { 394 if (strncmp(info, "pub", 3) == 0) 395 sin_m.sin_other = SIN_PROXY; 396 else 397 usage(); 398 } 399 addr->sin_addr.s_addr = inet_addr(host); 400 if (addr->sin_addr.s_addr == INADDR_NONE) { 401 if (!(hp = gethostbyname(host))) { 402 warnx("%s: %s", host, hstrerror(h_errno)); 403 return(1); 404 } 405 bcopy((char *)hp->h_addr, (char *)&addr->sin_addr, 406 sizeof(addr->sin_addr)); 407 } 408 tryagain: 409 if (rtmsg(RTM_GET) < 0) { 410 warn("%s", host); 411 return(1); 412 } 413 addr = (struct sockaddr_inarp *)(rtm + 1); 414 sdl = (struct sockaddr_dl *)(ROUNDUP(addr->sin_len) + (char *)addr); 415 if (addr->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 416 if (sdl->sdl_family == AF_LINK && 417 (rtm->rtm_flags & RTF_LLINFO) && 418 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 419 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 420 case IFT_ISO88024: case IFT_ISO88025: case IFT_L2VLAN: 421 case IFT_CARP: 422 goto delete; 423 } 424 } 425 if (sin_m.sin_other & SIN_PROXY) { 426 fprintf(stderr, "delete: can't locate %s\n",host); 427 return(1); 428 } else { 429 sin_m.sin_other = SIN_PROXY; 430 goto tryagain; 431 } 432 delete: 433 if (sdl->sdl_family != AF_LINK) { 434 printf("cannot locate %s\n", host); 435 return(1); 436 } 437 if (aflag && (rtm->rtm_flags & RTF_STATIC)) { 438 sdl->sdl_alen = 0; 439 sdl->sdl_slen = 0; 440 if (rtmsg(RTM_CHANGE) == 0) { 441 printf("%s (%s) cleared\n", 442 host, inet_ntoa(addr->sin_addr)); 443 return(0); 444 } 445 } else { 446 if (rtmsg(RTM_DELETE) == 0) { 447 printf("%s (%s) deleted\n", 448 host, inet_ntoa(addr->sin_addr)); 449 return(0); 450 } 451 } 452 return(1); 453 } 454 455 /* 456 * Search the arp table and do some action on matching entries 457 */ 458 void 459 search(u_long addr, void (*action)(struct sockaddr_dl *sdl, 460 struct sockaddr_inarp *sin, struct rt_msghdr *rtm)) 461 { 462 int mib[7]; 463 int miblen; 464 size_t needed; 465 char *lim, *buf, *next; 466 struct rt_msghdr *rtm; 467 struct sockaddr_inarp *sin2; 468 struct sockaddr_dl *sdl; 469 470 mib[0] = CTL_NET; 471 mib[1] = PF_ROUTE; 472 mib[2] = 0; 473 mib[3] = AF_INET; 474 mib[4] = NET_RT_FLAGS; 475 mib[5] = RTF_LLINFO; 476 if (cpuflag >= 0) { 477 mib[6] = cpuflag; 478 miblen = 7; 479 } else { 480 miblen = 6; 481 } 482 if (sysctl(mib, miblen, NULL, &needed, NULL, 0) < 0) 483 errx(1, "route-sysctl-estimate"); 484 if ((buf = malloc(needed)) == NULL) 485 errx(1, "malloc"); 486 if (sysctl(mib, miblen, buf, &needed, NULL, 0) < 0) 487 errx(1, "actual retrieval of routing table"); 488 lim = buf + needed; 489 for (next = buf; next < lim; next += rtm->rtm_msglen) { 490 rtm = (struct rt_msghdr *)next; 491 sin2 = (struct sockaddr_inarp *)(rtm + 1); 492 sdl = (struct sockaddr_dl *)((char *)sin2 + ROUNDUP(sin2->sin_len)); 493 if (addr) { 494 if (addr != sin2->sin_addr.s_addr) 495 continue; 496 found_entry = 1; 497 } 498 (*action)(sdl, sin2, rtm); 499 } 500 free(buf); 501 } 502 503 /* 504 * Display an arp entry 505 */ 506 void 507 print_entry(struct sockaddr_dl *sdl, 508 struct sockaddr_inarp *addr, struct rt_msghdr *rtm) 509 { 510 const char *host; 511 struct hostent *hp; 512 char ifname[IF_NAMESIZE]; 513 514 if (nflag == 0) 515 hp = gethostbyaddr(&(addr->sin_addr), sizeof(addr->sin_addr), 516 AF_INET); 517 else 518 hp = 0; 519 if (hp) 520 host = hp->h_name; 521 else { 522 host = "?"; 523 if (h_errno == TRY_AGAIN) 524 nflag = 1; 525 } 526 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 527 if (sdl->sdl_alen) 528 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 529 else 530 printf("(incomplete)"); 531 if (if_indextoname(sdl->sdl_index, ifname) != NULL) 532 printf(" on %s", ifname); 533 if (rtm->rtm_rmx.rmx_expire == 0) 534 printf(" permanent"); 535 if (addr->sin_other & SIN_PROXY) 536 printf(" published (proxy only)"); 537 if (rtm->rtm_addrs & RTA_NETMASK) { 538 addr = (struct sockaddr_inarp *) 539 (ROUNDUP(sdl->sdl_len) + (char *)sdl); 540 if (addr->sin_addr.s_addr == 0xffffffff) 541 printf(" published"); 542 if (addr->sin_len != 8) 543 printf("(weird)"); 544 } 545 switch(sdl->sdl_type) { 546 case IFT_ETHER: 547 printf(" [ethernet]"); 548 break; 549 case IFT_L2VLAN: 550 printf(" [vlan]"); 551 break; 552 case IFT_CARP: 553 printf(" [carp]"); 554 default: 555 break; 556 } 557 558 printf("\n"); 559 560 } 561 562 /* 563 * Nuke an arp entry 564 */ 565 void 566 nuke_entry(struct sockaddr_dl *sdl __unused, 567 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused) 568 { 569 char ip[20]; 570 571 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 572 delete(ip, NULL); 573 } 574 575 int 576 my_ether_aton(char *a, struct ether_addr *n) 577 { 578 struct ether_addr *ea; 579 580 if ((ea = ether_aton(a)) == NULL) { 581 warnx("invalid Ethernet address '%s'", a); 582 return(1); 583 } 584 *n = *ea; 585 return(0); 586 } 587 588 void 589 usage(void) 590 { 591 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 592 "usage: arp [-n] [-c cpu] hostname", 593 " arp [-n] [-c cpu] -a", 594 " arp -d hostname [pub]", 595 " arp -d -a", 596 " arp -s hostname ether_addr [temp] [pub [only]]", 597 " arp -S hostname ether_addr [temp] [pub [only]]", 598 " arp -f filename"); 599 exit(1); 600 } 601 602 int 603 rtmsg(int cmd) 604 { 605 static int seq; 606 int rlen; 607 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 608 char *cp = m_rtmsg.m_space; 609 int l; 610 611 errno = 0; 612 if (cmd == RTM_DELETE || cmd == RTM_CHANGE) 613 goto doit; 614 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 615 rtm->rtm_flags = flags; 616 rtm->rtm_version = RTM_VERSION; 617 618 switch (cmd) { 619 default: 620 errx(1, "internal wrong cmd"); 621 case RTM_ADD: 622 rtm->rtm_addrs |= RTA_GATEWAY; 623 rtm->rtm_rmx.rmx_expire = expire_time; 624 rtm->rtm_inits = RTV_EXPIRE; 625 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 626 sin_m.sin_other = 0; 627 if (doing_proxy) { 628 if (proxy_only) 629 sin_m.sin_other = SIN_PROXY; 630 else { 631 rtm->rtm_addrs |= RTA_NETMASK; 632 rtm->rtm_flags &= ~RTF_HOST; 633 } 634 } 635 /* FALLTHROUGH */ 636 case RTM_GET: 637 rtm->rtm_addrs |= RTA_DST; 638 } 639 #define NEXTADDR(w, s) \ 640 if (rtm->rtm_addrs & (w)) { \ 641 bcopy((char *)&s, cp, sizeof(s)); cp += ROUNDUP(sizeof(s));} 642 643 NEXTADDR(RTA_DST, sin_m); 644 NEXTADDR(RTA_GATEWAY, sdl_m); 645 NEXTADDR(RTA_NETMASK, so_mask); 646 647 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 648 doit: 649 l = rtm->rtm_msglen; 650 rtm->rtm_seq = ++seq; 651 rtm->rtm_type = cmd; 652 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 653 if (errno != ESRCH || (cmd != RTM_DELETE && cmd != RTM_CHANGE)) { 654 warn("writing to routing socket"); 655 return(-1); 656 } 657 } 658 do { 659 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 660 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 661 if (l < 0) 662 warn("read from routing socket"); 663 return(0); 664 } 665 666 /* 667 * get_ether_addr - get the hardware address of an interface on the 668 * the same subnet as ipaddr. 669 */ 670 #define MAX_IFS 32 671 672 int 673 get_ether_addr(u_int32_t ipaddr, struct ether_addr *hwaddr) 674 { 675 struct ifreq *ifr, *ifend, *ifp; 676 u_int32_t ina, mask; 677 struct sockaddr_dl *dla; 678 struct ifreq ifreq; 679 struct ifconf ifc; 680 struct ifreq ifs[MAX_IFS]; 681 int sock; 682 683 sock = socket(AF_INET, SOCK_DGRAM, 0); 684 if (sock < 0) 685 err(1, "socket"); 686 687 ifc.ifc_len = sizeof(ifs); 688 ifc.ifc_req = ifs; 689 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 690 warnx("ioctl(SIOCGIFCONF)"); 691 close(sock); 692 return(0); 693 } 694 695 /* 696 * Scan through looking for an interface with an Internet 697 * address on the same subnet as `ipaddr'. 698 */ 699 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len); 700 for (ifr = ifc.ifc_req; ifr < ifend; ) { 701 if (ifr->ifr_addr.sa_family == AF_INET) { 702 ina = ((struct sockaddr_in *) 703 &ifr->ifr_addr)->sin_addr.s_addr; 704 strncpy(ifreq.ifr_name, ifr->ifr_name, 705 sizeof(ifreq.ifr_name)); 706 /* 707 * Check that the interface is up, 708 * and not point-to-point or loopback. 709 */ 710 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 711 continue; 712 if ((ifreq.ifr_flags & 713 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 714 IFF_LOOPBACK|IFF_NOARP)) 715 != (IFF_UP|IFF_BROADCAST)) 716 goto nextif; 717 /* 718 * Get its netmask and check that it's on 719 * the right subnet. 720 */ 721 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 722 continue; 723 mask = ((struct sockaddr_in *) 724 &ifreq.ifr_addr)->sin_addr.s_addr; 725 if ((ipaddr & mask) != (ina & mask)) 726 goto nextif; 727 break; 728 } 729 nextif: 730 ifr = (struct ifreq *) ((char *)&ifr->ifr_addr 731 + MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr))); 732 } 733 734 if (ifr >= ifend) { 735 close(sock); 736 return(0); 737 } 738 739 /* 740 * Now scan through again looking for a link-level address 741 * for this interface. 742 */ 743 ifp = ifr; 744 for (ifr = ifc.ifc_req; ifr < ifend; ) { 745 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 746 && ifr->ifr_addr.sa_family == AF_LINK) { 747 /* 748 * Found the link-level address - copy it out 749 */ 750 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 751 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 752 close (sock); 753 printf("using interface %s for proxy with address ", 754 ifp->ifr_name); 755 printf("%s\n", ether_ntoa(hwaddr)); 756 return(dla->sdl_alen); 757 } 758 ifr = (struct ifreq *) ((char *)&ifr->ifr_addr 759 + MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr))); 760 } 761 return(0); 762 } 763