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_inarp *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, int do_proxy); 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_inarp *dst, struct sockaddr_dl *sdl); 97 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); 98 static struct sockaddr_inarp *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 int expire_time, flags, doing_proxy, proxy_only; 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); } 114 115 int 116 main(int argc, char *argv[]) 117 { 118 int ch, func = 0; 119 int rtn = 0; 120 int aflag = 0; /* do it for all entries */ 121 122 while ((ch = getopt(argc, argv, "andfsSi:")) != -1) 123 switch(ch) { 124 case 'a': 125 aflag = 1; 126 break; 127 case 'd': 128 SETFUNC(F_DELETE); 129 break; 130 case 'n': 131 nflag = 1; 132 break; 133 case 'S': 134 SETFUNC(F_REPLACE); 135 break; 136 case 's': 137 SETFUNC(F_SET); 138 break; 139 case 'f' : 140 SETFUNC(F_FILESET); 141 break; 142 case 'i': 143 rifname = optarg; 144 break; 145 case '?': 146 default: 147 usage(); 148 } 149 argc -= optind; 150 argv += optind; 151 152 if (!func) 153 func = F_GET; 154 if (rifname) { 155 if (func != F_GET && !(func == F_DELETE && aflag)) 156 errx(1, "-i not applicable to this operation"); 157 if (if_nametoindex(rifname) == 0) { 158 if (errno == ENXIO) 159 errx(1, "interface %s does not exist", rifname); 160 else 161 err(1, "if_nametoindex(%s)", rifname); 162 } 163 } 164 switch (func) { 165 case F_GET: 166 if (aflag) { 167 if (argc != 0) 168 usage(); 169 search(0, print_entry); 170 } else { 171 if (argc != 1) 172 usage(); 173 rtn = get(argv[0]); 174 } 175 break; 176 case F_SET: 177 case F_REPLACE: 178 if (argc < 2 || argc > 6) 179 usage(); 180 if (func == F_REPLACE) 181 (void)delete(argv[0], 0); 182 rtn = set(argc, argv) ? 1 : 0; 183 break; 184 case F_DELETE: 185 if (aflag) { 186 if (argc != 0) 187 usage(); 188 search(0, nuke_entry); 189 } else { 190 if (argc == 2 && strncmp(argv[1], "pub", 3) == 0) 191 ch = SIN_PROXY; 192 else if (argc == 1) 193 ch = 0; 194 else 195 usage(); 196 rtn = delete(argv[0], ch); 197 } 198 break; 199 case F_FILESET: 200 if (argc != 1) 201 usage(); 202 rtn = file(argv[0]); 203 break; 204 } 205 206 return (rtn); 207 } 208 209 /* 210 * Process a file to set standard arp entries 211 */ 212 static int 213 file(char *name) 214 { 215 FILE *fp; 216 int i, retval; 217 char line[100], arg[5][50], *args[5], *p; 218 219 if ((fp = fopen(name, "r")) == NULL) 220 err(1, "cannot open %s", name); 221 args[0] = &arg[0][0]; 222 args[1] = &arg[1][0]; 223 args[2] = &arg[2][0]; 224 args[3] = &arg[3][0]; 225 args[4] = &arg[4][0]; 226 retval = 0; 227 while(fgets(line, sizeof(line), fp) != NULL) { 228 if ((p = strchr(line, '#')) != NULL) 229 *p = '\0'; 230 for (p = line; isblank(*p); p++); 231 if (*p == '\n' || *p == '\0') 232 continue; 233 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 234 arg[2], arg[3], arg[4]); 235 if (i < 2) { 236 warnx("bad line: %s", line); 237 retval = 1; 238 continue; 239 } 240 if (set(i, args)) 241 retval = 1; 242 } 243 fclose(fp); 244 return (retval); 245 } 246 247 /* 248 * Given a hostname, fills up a (static) struct sockaddr_inarp with 249 * the address of the host and returns a pointer to the 250 * structure. 251 */ 252 static struct sockaddr_inarp * 253 getaddr(char *host) 254 { 255 struct hostent *hp; 256 static struct sockaddr_inarp reply; 257 258 bzero(&reply, sizeof(reply)); 259 reply.sin_len = sizeof(reply); 260 reply.sin_family = AF_INET; 261 reply.sin_addr.s_addr = inet_addr(host); 262 if (reply.sin_addr.s_addr == INADDR_NONE) { 263 if (!(hp = gethostbyname(host))) { 264 warnx("%s: %s", host, hstrerror(h_errno)); 265 return (NULL); 266 } 267 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 268 sizeof reply.sin_addr); 269 } 270 return (&reply); 271 } 272 273 /* 274 * Returns true if the type is a valid one for ARP. 275 */ 276 static int 277 valid_type(int type) 278 { 279 280 switch (type) { 281 case IFT_ETHER: 282 case IFT_FDDI: 283 case IFT_ISO88023: 284 case IFT_ISO88024: 285 case IFT_ISO88025: 286 case IFT_L2VLAN: 287 case IFT_BRIDGE: 288 return (1); 289 default: 290 return (0); 291 } 292 } 293 294 /* 295 * Set an individual arp entry 296 */ 297 static int 298 set(int argc, char **argv) 299 { 300 struct sockaddr_inarp *addr; 301 struct sockaddr_inarp *dst; /* what are we looking for */ 302 struct sockaddr_dl *sdl; 303 struct rt_msghdr *rtm; 304 struct ether_addr *ea; 305 char *host = argv[0], *eaddr = argv[1]; 306 struct sockaddr_dl sdl_m; 307 308 argc -= 2; 309 argv += 2; 310 311 bzero(&sdl_m, sizeof(sdl_m)); 312 sdl_m.sdl_len = sizeof(sdl_m); 313 sdl_m.sdl_family = AF_LINK; 314 315 dst = getaddr(host); 316 if (dst == NULL) 317 return (1); 318 doing_proxy = flags = proxy_only = expire_time = 0; 319 while (argc-- > 0) { 320 if (strncmp(argv[0], "temp", 4) == 0) { 321 struct timeval tv; 322 gettimeofday(&tv, 0); 323 expire_time = tv.tv_sec + 20 * 60; 324 } else if (strncmp(argv[0], "pub", 3) == 0) { 325 flags |= RTF_ANNOUNCE; 326 doing_proxy = 1; 327 if (argc && strncmp(argv[1], "only", 3) == 0) { 328 proxy_only = 1; 329 argc--; argv++; 330 } 331 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 332 if (flags & RTF_REJECT) { 333 printf("Choose one of blackhole or reject, not both.\n"); 334 } 335 flags |= RTF_BLACKHOLE; 336 } else if (strncmp(argv[0], "reject", 6) == 0) { 337 if (flags & RTF_BLACKHOLE) { 338 printf("Choose one of blackhole or reject, not both.\n"); 339 } 340 flags |= RTF_REJECT; 341 } else if (strncmp(argv[0], "trail", 5) == 0) { 342 /* XXX deprecated and undocumented feature */ 343 printf("%s: Sending trailers is no longer supported\n", 344 host); 345 } 346 argv++; 347 } 348 ea = (struct ether_addr *)LLADDR(&sdl_m); 349 if (doing_proxy && !strcmp(eaddr, "auto")) { 350 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 351 printf("no interface found for %s\n", 352 inet_ntoa(dst->sin_addr)); 353 return (1); 354 } 355 sdl_m.sdl_alen = ETHER_ADDR_LEN; 356 } else { 357 struct ether_addr *ea1 = ether_aton(eaddr); 358 359 if (ea1 == NULL) { 360 warnx("invalid Ethernet address '%s'", eaddr); 361 return (1); 362 } else { 363 *ea = *ea1; 364 sdl_m.sdl_alen = ETHER_ADDR_LEN; 365 } 366 } 367 368 /* 369 * In the case a proxy-arp entry is being added for 370 * a remote end point, the RTF_ANNOUNCE flag in the 371 * RTM_GET command is an indication to the kernel 372 * routing code that the interface associated with 373 * the prefix route covering the local end of the 374 * PPP link should be returned, on which ARP applies. 375 */ 376 rtm = rtmsg(RTM_GET, dst, &sdl_m); 377 if (rtm == NULL) { 378 warn("%s", host); 379 return (1); 380 } 381 addr = (struct sockaddr_inarp *)(rtm + 1); 382 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 383 if (addr->sin_addr.s_addr == dst->sin_addr.s_addr) { 384 printf("set: proxy entry exists for non 802 device\n"); 385 return (1); 386 } 387 388 if ((sdl->sdl_family != AF_LINK) || 389 (rtm->rtm_flags & RTF_GATEWAY) || 390 !valid_type(sdl->sdl_type)) { 391 printf("cannot intuit interface index and type for %s\n", host); 392 return (1); 393 } 394 sdl_m.sdl_type = sdl->sdl_type; 395 sdl_m.sdl_index = sdl->sdl_index; 396 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 397 } 398 399 /* 400 * Display an individual arp entry 401 */ 402 static int 403 get(char *host) 404 { 405 struct sockaddr_inarp *addr; 406 407 addr = getaddr(host); 408 if (addr == NULL) 409 return (1); 410 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 411 printf("%s (%s) -- no entry", 412 host, inet_ntoa(addr->sin_addr)); 413 if (rifname) 414 printf(" on %s", rifname); 415 printf("\n"); 416 return (1); 417 } 418 return (0); 419 } 420 421 /* 422 * Delete an arp entry 423 */ 424 static int 425 delete(char *host, int do_proxy) 426 { 427 struct sockaddr_inarp *addr, *dst; 428 struct rt_msghdr *rtm; 429 struct sockaddr_dl *sdl; 430 struct sockaddr_dl sdl_m; 431 432 dst = getaddr(host); 433 if (dst == NULL) 434 return (1); 435 436 /* 437 * Perform a regular entry delete first. 438 */ 439 flags &= ~RTF_ANNOUNCE; 440 441 /* 442 * setup the data structure to notify the kernel 443 * it is the ARP entry the RTM_GET is interested 444 * in 445 */ 446 bzero(&sdl_m, sizeof(sdl_m)); 447 sdl_m.sdl_len = sizeof(sdl_m); 448 sdl_m.sdl_family = AF_LINK; 449 450 for (;;) { /* try twice */ 451 rtm = rtmsg(RTM_GET, dst, &sdl_m); 452 if (rtm == NULL) { 453 warn("%s", host); 454 return (1); 455 } 456 addr = (struct sockaddr_inarp *)(rtm + 1); 457 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 458 459 /* 460 * With the new L2/L3 restructure, the route 461 * returned is a prefix route. The important 462 * piece of information from the previous 463 * RTM_GET is the interface index. In the 464 * case of ECMP, the kernel will traverse 465 * the route group for the given entry. 466 */ 467 if (sdl->sdl_family == AF_LINK && 468 !(rtm->rtm_flags & RTF_GATEWAY) && 469 valid_type(sdl->sdl_type) ) { 470 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 471 break; 472 } 473 474 /* 475 * Regualar entry delete failed, now check if there 476 * is a proxy-arp entry to remove. 477 */ 478 if (flags & RTF_ANNOUNCE) { 479 fprintf(stderr, "delete: cannot locate %s\n",host); 480 return (1); 481 } 482 483 flags |= RTF_ANNOUNCE; 484 } 485 rtm->rtm_flags |= RTF_LLDATA; 486 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 487 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 488 return (0); 489 } 490 return (1); 491 } 492 493 494 /* 495 * Search the arp table and do some action on matching entries 496 */ 497 static int 498 search(u_long addr, action_fn *action) 499 { 500 int mib[6]; 501 size_t needed; 502 char *lim, *buf, *next; 503 struct rt_msghdr *rtm; 504 struct sockaddr_inarp *sin2; 505 struct sockaddr_dl *sdl; 506 char ifname[IF_NAMESIZE]; 507 int st, found_entry = 0; 508 509 mib[0] = CTL_NET; 510 mib[1] = PF_ROUTE; 511 mib[2] = 0; 512 mib[3] = AF_INET; 513 mib[4] = NET_RT_FLAGS; 514 #ifdef RTF_LLINFO 515 mib[5] = RTF_LLINFO; 516 #else 517 mib[5] = 0; 518 #endif 519 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 520 err(1, "route-sysctl-estimate"); 521 if (needed == 0) /* empty table */ 522 return 0; 523 buf = NULL; 524 for (;;) { 525 buf = reallocf(buf, needed); 526 if (buf == NULL) 527 errx(1, "could not reallocate memory"); 528 st = sysctl(mib, 6, buf, &needed, NULL, 0); 529 if (st == 0 || errno != ENOMEM) 530 break; 531 needed += needed / 8; 532 } 533 if (st == -1) 534 err(1, "actual retrieval of routing table"); 535 lim = buf + needed; 536 for (next = buf; next < lim; next += rtm->rtm_msglen) { 537 rtm = (struct rt_msghdr *)next; 538 sin2 = (struct sockaddr_inarp *)(rtm + 1); 539 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 540 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 541 strcmp(ifname, rifname)) 542 continue; 543 if (addr) { 544 if (addr != sin2->sin_addr.s_addr) 545 continue; 546 found_entry = 1; 547 } 548 (*action)(sdl, sin2, rtm); 549 } 550 free(buf); 551 return (found_entry); 552 } 553 554 /* 555 * Display an arp entry 556 */ 557 static void 558 print_entry(struct sockaddr_dl *sdl, 559 struct sockaddr_inarp *addr, struct rt_msghdr *rtm) 560 { 561 const char *host; 562 struct hostent *hp; 563 struct iso88025_sockaddr_dl_data *trld; 564 char ifname[IF_NAMESIZE]; 565 int seg; 566 567 if (nflag == 0) 568 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 569 sizeof addr->sin_addr, AF_INET); 570 else 571 hp = 0; 572 if (hp) 573 host = hp->h_name; 574 else { 575 host = "?"; 576 if (h_errno == TRY_AGAIN) 577 nflag = 1; 578 } 579 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 580 if (sdl->sdl_alen) { 581 if ((sdl->sdl_type == IFT_ETHER || 582 sdl->sdl_type == IFT_L2VLAN || 583 sdl->sdl_type == IFT_BRIDGE) && 584 sdl->sdl_alen == ETHER_ADDR_LEN) 585 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 586 else { 587 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 588 589 printf("%s", link_ntoa(sdl) + n); 590 } 591 } else 592 printf("(incomplete)"); 593 if (if_indextoname(sdl->sdl_index, ifname) != NULL) 594 printf(" on %s", ifname); 595 if (rtm->rtm_rmx.rmx_expire == 0) 596 printf(" permanent"); 597 if (addr->sin_other & SIN_PROXY) 598 printf(" published (proxy only)"); 599 if (rtm->rtm_flags & RTF_ANNOUNCE) 600 printf(" published"); 601 switch(sdl->sdl_type) { 602 case IFT_ETHER: 603 printf(" [ethernet]"); 604 break; 605 case IFT_ISO88025: 606 printf(" [token-ring]"); 607 trld = SDL_ISO88025(sdl); 608 if (trld->trld_rcf != 0) { 609 printf(" rt=%x", ntohs(trld->trld_rcf)); 610 for (seg = 0; 611 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 612 seg++) 613 printf(":%x", ntohs(*(trld->trld_route[seg]))); 614 } 615 break; 616 case IFT_FDDI: 617 printf(" [fddi]"); 618 break; 619 case IFT_ATM: 620 printf(" [atm]"); 621 break; 622 case IFT_L2VLAN: 623 printf(" [vlan]"); 624 break; 625 case IFT_IEEE1394: 626 printf(" [firewire]"); 627 break; 628 case IFT_BRIDGE: 629 printf(" [bridge]"); 630 break; 631 default: 632 break; 633 } 634 635 printf("\n"); 636 637 } 638 639 /* 640 * Nuke an arp entry 641 */ 642 static void 643 nuke_entry(struct sockaddr_dl *sdl __unused, 644 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused) 645 { 646 char ip[20]; 647 648 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 649 (void)delete(ip, 0); 650 } 651 652 static void 653 usage(void) 654 { 655 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 656 "usage: arp [-n] [-i interface] hostname", 657 " arp [-n] [-i interface] -a", 658 " arp -d hostname [pub]", 659 " arp -d [-i interface] -a", 660 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 661 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 662 " arp -f filename"); 663 exit(1); 664 } 665 666 static struct rt_msghdr * 667 rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl) 668 { 669 static int seq; 670 int rlen; 671 int l; 672 struct sockaddr_in so_mask, *som = &so_mask; 673 static int s = -1; 674 static pid_t pid; 675 676 static struct { 677 struct rt_msghdr m_rtm; 678 char m_space[512]; 679 } m_rtmsg; 680 681 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 682 char *cp = m_rtmsg.m_space; 683 684 if (s < 0) { /* first time: open socket, get pid */ 685 s = socket(PF_ROUTE, SOCK_RAW, 0); 686 if (s < 0) 687 err(1, "socket"); 688 pid = getpid(); 689 } 690 bzero(&so_mask, sizeof(so_mask)); 691 so_mask.sin_len = 8; 692 so_mask.sin_addr.s_addr = 0xffffffff; 693 694 errno = 0; 695 /* 696 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 697 * appropriately. 698 */ 699 if (cmd == RTM_DELETE) 700 goto doit; 701 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 702 rtm->rtm_flags = flags; 703 rtm->rtm_version = RTM_VERSION; 704 705 switch (cmd) { 706 default: 707 errx(1, "internal wrong cmd"); 708 case RTM_ADD: 709 rtm->rtm_addrs |= RTA_GATEWAY; 710 rtm->rtm_rmx.rmx_expire = expire_time; 711 rtm->rtm_inits = RTV_EXPIRE; 712 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 713 dst->sin_other = 0; 714 if (doing_proxy) { 715 if (proxy_only) 716 dst->sin_other = SIN_PROXY; 717 else { 718 rtm->rtm_addrs |= RTA_NETMASK; 719 rtm->rtm_flags &= ~RTF_HOST; 720 } 721 } 722 /* FALLTHROUGH */ 723 case RTM_GET: 724 rtm->rtm_addrs |= RTA_DST; 725 } 726 #define NEXTADDR(w, s) \ 727 do { \ 728 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 729 bcopy((s), cp, sizeof(*(s))); \ 730 cp += SA_SIZE(s); \ 731 } \ 732 } while (0) 733 734 NEXTADDR(RTA_DST, dst); 735 NEXTADDR(RTA_GATEWAY, sdl); 736 NEXTADDR(RTA_NETMASK, som); 737 738 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 739 doit: 740 l = rtm->rtm_msglen; 741 rtm->rtm_seq = ++seq; 742 rtm->rtm_type = cmd; 743 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 744 if (errno != ESRCH || cmd != RTM_DELETE) { 745 warn("writing to routing socket"); 746 return (NULL); 747 } 748 } 749 do { 750 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 751 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 752 if (l < 0) 753 warn("read from routing socket"); 754 return (rtm); 755 } 756 757 /* 758 * get_ether_addr - get the hardware address of an interface on the 759 * the same subnet as ipaddr. 760 */ 761 #define MAX_IFS 32 762 763 static int 764 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 765 { 766 struct ifreq *ifr, *ifend, *ifp; 767 in_addr_t ina, mask; 768 struct sockaddr_dl *dla; 769 struct ifreq ifreq; 770 struct ifconf ifc; 771 struct ifreq ifs[MAX_IFS]; 772 int sock; 773 int retval = 0; 774 775 sock = socket(AF_INET, SOCK_DGRAM, 0); 776 if (sock < 0) 777 err(1, "socket"); 778 779 ifc.ifc_len = sizeof(ifs); 780 ifc.ifc_req = ifs; 781 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 782 warnx("ioctl(SIOCGIFCONF)"); 783 goto done; 784 } 785 786 #define NEXTIFR(i) \ 787 ((struct ifreq *)((char *)&(i)->ifr_addr \ 788 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 789 790 /* 791 * Scan through looking for an interface with an Internet 792 * address on the same subnet as `ipaddr'. 793 */ 794 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 795 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 796 if (ifr->ifr_addr.sa_family != AF_INET) 797 continue; 798 strncpy(ifreq.ifr_name, ifr->ifr_name, 799 sizeof(ifreq.ifr_name)); 800 ifreq.ifr_addr = ifr->ifr_addr; 801 /* 802 * Check that the interface is up, 803 * and not point-to-point or loopback. 804 */ 805 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 806 continue; 807 if ((ifreq.ifr_flags & 808 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 809 IFF_LOOPBACK|IFF_NOARP)) 810 != (IFF_UP|IFF_BROADCAST)) 811 continue; 812 /* 813 * Get its netmask and check that it's on 814 * the right subnet. 815 */ 816 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 817 continue; 818 mask = ((struct sockaddr_in *) 819 &ifreq.ifr_addr)->sin_addr.s_addr; 820 ina = ((struct sockaddr_in *) 821 &ifr->ifr_addr)->sin_addr.s_addr; 822 if ((ipaddr & mask) == (ina & mask)) 823 break; /* ok, we got it! */ 824 } 825 826 if (ifr >= ifend) 827 goto done; 828 829 /* 830 * Now scan through again looking for a link-level address 831 * for this interface. 832 */ 833 ifp = ifr; 834 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 835 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 836 ifr->ifr_addr.sa_family == AF_LINK) 837 break; 838 if (ifr >= ifend) 839 goto done; 840 /* 841 * Found the link-level address - copy it out 842 */ 843 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 844 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 845 printf("using interface %s for proxy with address ", 846 ifp->ifr_name); 847 printf("%s\n", ether_ntoa(hwaddr)); 848 retval = dla->sdl_alen; 849 done: 850 close(sock); 851 return (retval); 852 } 853