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_in *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); 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_in *dst, struct sockaddr_dl *sdl); 97 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); 98 static struct sockaddr_in *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 time_t expire_time; 105 static int flags, doing_proxy; 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 SETFUNC(f) { if (func) usage(); func = (f); } 115 116 int 117 main(int argc, char *argv[]) 118 { 119 int ch, func = 0; 120 int rtn = 0; 121 int aflag = 0; /* do it for all entries */ 122 123 while ((ch = getopt(argc, argv, "andfsSi:")) != -1) 124 switch(ch) { 125 case 'a': 126 aflag = 1; 127 break; 128 case 'd': 129 SETFUNC(F_DELETE); 130 break; 131 case 'n': 132 nflag = 1; 133 break; 134 case 'S': 135 SETFUNC(F_REPLACE); 136 break; 137 case 's': 138 SETFUNC(F_SET); 139 break; 140 case 'f' : 141 SETFUNC(F_FILESET); 142 break; 143 case 'i': 144 rifname = optarg; 145 break; 146 case '?': 147 default: 148 usage(); 149 } 150 argc -= optind; 151 argv += optind; 152 153 if (!func) 154 func = F_GET; 155 if (rifname) { 156 if (func != F_GET && !(func == F_DELETE && aflag)) 157 errx(1, "-i not applicable to this operation"); 158 if (if_nametoindex(rifname) == 0) { 159 if (errno == ENXIO) 160 errx(1, "interface %s does not exist", rifname); 161 else 162 err(1, "if_nametoindex(%s)", rifname); 163 } 164 } 165 switch (func) { 166 case F_GET: 167 if (aflag) { 168 if (argc != 0) 169 usage(); 170 search(0, print_entry); 171 } else { 172 if (argc != 1) 173 usage(); 174 rtn = get(argv[0]); 175 } 176 break; 177 case F_SET: 178 case F_REPLACE: 179 if (argc < 2 || argc > 6) 180 usage(); 181 if (func == F_REPLACE) 182 (void)delete(argv[0]); 183 rtn = set(argc, argv) ? 1 : 0; 184 break; 185 case F_DELETE: 186 if (aflag) { 187 if (argc != 0) 188 usage(); 189 search(0, nuke_entry); 190 } else { 191 if (argc != 1) 192 usage(); 193 rtn = delete(argv[0]); 194 } 195 break; 196 case F_FILESET: 197 if (argc != 1) 198 usage(); 199 rtn = file(argv[0]); 200 break; 201 } 202 203 return (rtn); 204 } 205 206 /* 207 * Process a file to set standard arp entries 208 */ 209 static int 210 file(char *name) 211 { 212 FILE *fp; 213 int i, retval; 214 char line[100], arg[5][50], *args[5], *p; 215 216 if ((fp = fopen(name, "r")) == NULL) 217 err(1, "cannot open %s", name); 218 args[0] = &arg[0][0]; 219 args[1] = &arg[1][0]; 220 args[2] = &arg[2][0]; 221 args[3] = &arg[3][0]; 222 args[4] = &arg[4][0]; 223 retval = 0; 224 while(fgets(line, sizeof(line), fp) != NULL) { 225 if ((p = strchr(line, '#')) != NULL) 226 *p = '\0'; 227 for (p = line; isblank(*p); p++); 228 if (*p == '\n' || *p == '\0') 229 continue; 230 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 231 arg[2], arg[3], arg[4]); 232 if (i < 2) { 233 warnx("bad line: %s", line); 234 retval = 1; 235 continue; 236 } 237 if (set(i, args)) 238 retval = 1; 239 } 240 fclose(fp); 241 return (retval); 242 } 243 244 /* 245 * Given a hostname, fills up a (static) struct sockaddr_in with 246 * the address of the host and returns a pointer to the 247 * structure. 248 */ 249 static struct sockaddr_in * 250 getaddr(char *host) 251 { 252 struct hostent *hp; 253 static struct sockaddr_in reply; 254 255 bzero(&reply, sizeof(reply)); 256 reply.sin_len = sizeof(reply); 257 reply.sin_family = AF_INET; 258 reply.sin_addr.s_addr = inet_addr(host); 259 if (reply.sin_addr.s_addr == INADDR_NONE) { 260 if (!(hp = gethostbyname(host))) { 261 warnx("%s: %s", host, hstrerror(h_errno)); 262 return (NULL); 263 } 264 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 265 sizeof reply.sin_addr); 266 } 267 return (&reply); 268 } 269 270 /* 271 * Returns true if the type is a valid one for ARP. 272 */ 273 static int 274 valid_type(int type) 275 { 276 277 switch (type) { 278 case IFT_ETHER: 279 case IFT_FDDI: 280 case IFT_ISO88023: 281 case IFT_ISO88024: 282 case IFT_ISO88025: 283 case IFT_L2VLAN: 284 case IFT_BRIDGE: 285 return (1); 286 default: 287 return (0); 288 } 289 } 290 291 /* 292 * Set an individual arp entry 293 */ 294 static int 295 set(int argc, char **argv) 296 { 297 struct sockaddr_in *addr; 298 struct sockaddr_in *dst; /* what are we looking for */ 299 struct sockaddr_dl *sdl; 300 struct rt_msghdr *rtm; 301 struct ether_addr *ea; 302 char *host = argv[0], *eaddr = argv[1]; 303 struct sockaddr_dl sdl_m; 304 305 argc -= 2; 306 argv += 2; 307 308 bzero(&sdl_m, sizeof(sdl_m)); 309 sdl_m.sdl_len = sizeof(sdl_m); 310 sdl_m.sdl_family = AF_LINK; 311 312 dst = getaddr(host); 313 if (dst == NULL) 314 return (1); 315 doing_proxy = flags = expire_time = 0; 316 while (argc-- > 0) { 317 if (strncmp(argv[0], "temp", 4) == 0) { 318 struct timespec tp; 319 int max_age; 320 size_t len = sizeof(max_age); 321 322 clock_gettime(CLOCK_MONOTONIC, &tp); 323 if (sysctlbyname("net.link.ether.inet.max_age", 324 &max_age, &len, NULL, 0) != 0) 325 err(1, "sysctlbyname"); 326 expire_time = tp.tv_sec + max_age; 327 } else if (strncmp(argv[0], "pub", 3) == 0) { 328 flags |= RTF_ANNOUNCE; 329 doing_proxy = 1; 330 if (argc && strncmp(argv[1], "only", 3) == 0) { 331 /* 332 * Compatibility: in pre FreeBSD 8 times 333 * the "only" keyword used to mean that 334 * an ARP entry should be announced, but 335 * not installed into routing table. 336 */ 337 argc--; argv++; 338 } 339 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 340 if (flags & RTF_REJECT) { 341 printf("Choose one of blackhole or reject, not both.\n"); 342 } 343 flags |= RTF_BLACKHOLE; 344 } else if (strncmp(argv[0], "reject", 6) == 0) { 345 if (flags & RTF_BLACKHOLE) { 346 printf("Choose one of blackhole or reject, not both.\n"); 347 } 348 flags |= RTF_REJECT; 349 } else if (strncmp(argv[0], "trail", 5) == 0) { 350 /* XXX deprecated and undocumented feature */ 351 printf("%s: Sending trailers is no longer supported\n", 352 host); 353 } 354 argv++; 355 } 356 ea = (struct ether_addr *)LLADDR(&sdl_m); 357 if (doing_proxy && !strcmp(eaddr, "auto")) { 358 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 359 printf("no interface found for %s\n", 360 inet_ntoa(dst->sin_addr)); 361 return (1); 362 } 363 sdl_m.sdl_alen = ETHER_ADDR_LEN; 364 } else { 365 struct ether_addr *ea1 = ether_aton(eaddr); 366 367 if (ea1 == NULL) { 368 warnx("invalid Ethernet address '%s'", eaddr); 369 return (1); 370 } else { 371 *ea = *ea1; 372 sdl_m.sdl_alen = ETHER_ADDR_LEN; 373 } 374 } 375 376 /* 377 * In the case a proxy-arp entry is being added for 378 * a remote end point, the RTF_ANNOUNCE flag in the 379 * RTM_GET command is an indication to the kernel 380 * routing code that the interface associated with 381 * the prefix route covering the local end of the 382 * PPP link should be returned, on which ARP applies. 383 */ 384 rtm = rtmsg(RTM_GET, dst, &sdl_m); 385 if (rtm == NULL) { 386 warn("%s", host); 387 return (1); 388 } 389 addr = (struct sockaddr_in *)(rtm + 1); 390 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 391 392 if ((sdl->sdl_family != AF_LINK) || 393 (rtm->rtm_flags & RTF_GATEWAY) || 394 !valid_type(sdl->sdl_type)) { 395 printf("cannot intuit interface index and type for %s\n", host); 396 return (1); 397 } 398 sdl_m.sdl_type = sdl->sdl_type; 399 sdl_m.sdl_index = sdl->sdl_index; 400 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 401 } 402 403 /* 404 * Display an individual arp entry 405 */ 406 static int 407 get(char *host) 408 { 409 struct sockaddr_in *addr; 410 411 addr = getaddr(host); 412 if (addr == NULL) 413 return (1); 414 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 415 printf("%s (%s) -- no entry", 416 host, inet_ntoa(addr->sin_addr)); 417 if (rifname) 418 printf(" on %s", rifname); 419 printf("\n"); 420 return (1); 421 } 422 return (0); 423 } 424 425 /* 426 * Delete an arp entry 427 */ 428 static int 429 delete(char *host) 430 { 431 struct sockaddr_in *addr, *dst; 432 struct rt_msghdr *rtm; 433 struct sockaddr_dl *sdl; 434 struct sockaddr_dl sdl_m; 435 436 dst = getaddr(host); 437 if (dst == NULL) 438 return (1); 439 440 /* 441 * Perform a regular entry delete first. 442 */ 443 flags &= ~RTF_ANNOUNCE; 444 445 /* 446 * setup the data structure to notify the kernel 447 * it is the ARP entry the RTM_GET is interested 448 * in 449 */ 450 bzero(&sdl_m, sizeof(sdl_m)); 451 sdl_m.sdl_len = sizeof(sdl_m); 452 sdl_m.sdl_family = AF_LINK; 453 454 for (;;) { /* try twice */ 455 rtm = rtmsg(RTM_GET, dst, &sdl_m); 456 if (rtm == NULL) { 457 warn("%s", host); 458 return (1); 459 } 460 addr = (struct sockaddr_in *)(rtm + 1); 461 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 462 463 /* 464 * With the new L2/L3 restructure, the route 465 * returned is a prefix route. The important 466 * piece of information from the previous 467 * RTM_GET is the interface index. In the 468 * case of ECMP, the kernel will traverse 469 * the route group for the given entry. 470 */ 471 if (sdl->sdl_family == AF_LINK && 472 !(rtm->rtm_flags & RTF_GATEWAY) && 473 valid_type(sdl->sdl_type) ) { 474 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 475 break; 476 } 477 478 /* 479 * Regualar entry delete failed, now check if there 480 * is a proxy-arp entry to remove. 481 */ 482 if (flags & RTF_ANNOUNCE) { 483 fprintf(stderr, "delete: cannot locate %s\n",host); 484 return (1); 485 } 486 487 flags |= RTF_ANNOUNCE; 488 } 489 rtm->rtm_flags |= RTF_LLDATA; 490 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 491 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 492 return (0); 493 } 494 return (1); 495 } 496 497 498 /* 499 * Search the arp table and do some action on matching entries 500 */ 501 static int 502 search(u_long addr, action_fn *action) 503 { 504 int mib[6]; 505 size_t needed; 506 char *lim, *buf, *next; 507 struct rt_msghdr *rtm; 508 struct sockaddr_in *sin2; 509 struct sockaddr_dl *sdl; 510 char ifname[IF_NAMESIZE]; 511 int st, found_entry = 0; 512 513 mib[0] = CTL_NET; 514 mib[1] = PF_ROUTE; 515 mib[2] = 0; 516 mib[3] = AF_INET; 517 mib[4] = NET_RT_FLAGS; 518 #ifdef RTF_LLINFO 519 mib[5] = RTF_LLINFO; 520 #else 521 mib[5] = 0; 522 #endif 523 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 524 err(1, "route-sysctl-estimate"); 525 if (needed == 0) /* empty table */ 526 return 0; 527 buf = NULL; 528 for (;;) { 529 buf = reallocf(buf, needed); 530 if (buf == NULL) 531 errx(1, "could not reallocate memory"); 532 st = sysctl(mib, 6, buf, &needed, NULL, 0); 533 if (st == 0 || errno != ENOMEM) 534 break; 535 needed += needed / 8; 536 } 537 if (st == -1) 538 err(1, "actual retrieval of routing table"); 539 lim = buf + needed; 540 for (next = buf; next < lim; next += rtm->rtm_msglen) { 541 rtm = (struct rt_msghdr *)next; 542 sin2 = (struct sockaddr_in *)(rtm + 1); 543 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 544 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 545 strcmp(ifname, rifname)) 546 continue; 547 if (addr) { 548 if (addr != sin2->sin_addr.s_addr) 549 continue; 550 found_entry = 1; 551 } 552 (*action)(sdl, sin2, rtm); 553 } 554 free(buf); 555 return (found_entry); 556 } 557 558 /* 559 * Display an arp entry 560 */ 561 static char lifname[IF_NAMESIZE]; 562 static int64_t lifindex = -1; 563 564 static void 565 print_entry(struct sockaddr_dl *sdl, 566 struct sockaddr_in *addr, struct rt_msghdr *rtm) 567 { 568 const char *host; 569 struct hostent *hp; 570 struct iso88025_sockaddr_dl_data *trld; 571 int seg; 572 573 if (nflag == 0) 574 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 575 sizeof addr->sin_addr, AF_INET); 576 else 577 hp = 0; 578 if (hp) 579 host = hp->h_name; 580 else { 581 host = "?"; 582 if (h_errno == TRY_AGAIN) 583 nflag = 1; 584 } 585 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 586 if (sdl->sdl_alen) { 587 if ((sdl->sdl_type == IFT_ETHER || 588 sdl->sdl_type == IFT_L2VLAN || 589 sdl->sdl_type == IFT_BRIDGE) && 590 sdl->sdl_alen == ETHER_ADDR_LEN) 591 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 592 else { 593 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 594 595 printf("%s", link_ntoa(sdl) + n); 596 } 597 } else 598 printf("(incomplete)"); 599 if (sdl->sdl_index != lifindex && 600 if_indextoname(sdl->sdl_index, lifname) != NULL) { 601 lifindex = sdl->sdl_index; 602 printf(" on %s", lifname); 603 } else if (sdl->sdl_index == lifindex) 604 printf(" on %s", lifname); 605 if (rtm->rtm_rmx.rmx_expire == 0) 606 printf(" permanent"); 607 else { 608 static struct timespec tp; 609 if (tp.tv_sec == 0) 610 clock_gettime(CLOCK_MONOTONIC, &tp); 611 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 612 printf(" expires in %d seconds", (int)expire_time); 613 else 614 printf(" expired"); 615 } 616 if (rtm->rtm_flags & RTF_ANNOUNCE) 617 printf(" published"); 618 switch(sdl->sdl_type) { 619 case IFT_ETHER: 620 printf(" [ethernet]"); 621 break; 622 case IFT_ISO88025: 623 printf(" [token-ring]"); 624 trld = SDL_ISO88025(sdl); 625 if (trld->trld_rcf != 0) { 626 printf(" rt=%x", ntohs(trld->trld_rcf)); 627 for (seg = 0; 628 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 629 seg++) 630 printf(":%x", ntohs(*(trld->trld_route[seg]))); 631 } 632 break; 633 case IFT_FDDI: 634 printf(" [fddi]"); 635 break; 636 case IFT_ATM: 637 printf(" [atm]"); 638 break; 639 case IFT_L2VLAN: 640 printf(" [vlan]"); 641 break; 642 case IFT_IEEE1394: 643 printf(" [firewire]"); 644 break; 645 case IFT_BRIDGE: 646 printf(" [bridge]"); 647 break; 648 default: 649 break; 650 } 651 652 printf("\n"); 653 654 } 655 656 /* 657 * Nuke an arp entry 658 */ 659 static void 660 nuke_entry(struct sockaddr_dl *sdl __unused, 661 struct sockaddr_in *addr, struct rt_msghdr *rtm __unused) 662 { 663 char ip[20]; 664 665 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 666 delete(ip); 667 } 668 669 static void 670 usage(void) 671 { 672 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 673 "usage: arp [-n] [-i interface] hostname", 674 " arp [-n] [-i interface] -a", 675 " arp -d hostname [pub]", 676 " arp -d [-i interface] -a", 677 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 678 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 679 " arp -f filename"); 680 exit(1); 681 } 682 683 static struct rt_msghdr * 684 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) 685 { 686 static int seq; 687 int rlen; 688 int l; 689 struct sockaddr_in so_mask, *som = &so_mask; 690 static int s = -1; 691 static pid_t pid; 692 693 static struct { 694 struct rt_msghdr m_rtm; 695 char m_space[512]; 696 } m_rtmsg; 697 698 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 699 char *cp = m_rtmsg.m_space; 700 701 if (s < 0) { /* first time: open socket, get pid */ 702 s = socket(PF_ROUTE, SOCK_RAW, 0); 703 if (s < 0) 704 err(1, "socket"); 705 pid = getpid(); 706 } 707 bzero(&so_mask, sizeof(so_mask)); 708 so_mask.sin_len = 8; 709 so_mask.sin_addr.s_addr = 0xffffffff; 710 711 errno = 0; 712 /* 713 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 714 * appropriately. 715 */ 716 if (cmd == RTM_DELETE) 717 goto doit; 718 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 719 rtm->rtm_flags = flags; 720 rtm->rtm_version = RTM_VERSION; 721 722 switch (cmd) { 723 default: 724 errx(1, "internal wrong cmd"); 725 case RTM_ADD: 726 rtm->rtm_addrs |= RTA_GATEWAY; 727 rtm->rtm_rmx.rmx_expire = expire_time; 728 rtm->rtm_inits = RTV_EXPIRE; 729 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 730 if (doing_proxy) { 731 rtm->rtm_addrs |= RTA_NETMASK; 732 rtm->rtm_flags &= ~RTF_HOST; 733 } 734 /* FALLTHROUGH */ 735 case RTM_GET: 736 rtm->rtm_addrs |= RTA_DST; 737 } 738 #define NEXTADDR(w, s) \ 739 do { \ 740 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 741 bcopy((s), cp, sizeof(*(s))); \ 742 cp += SA_SIZE(s); \ 743 } \ 744 } while (0) 745 746 NEXTADDR(RTA_DST, dst); 747 NEXTADDR(RTA_GATEWAY, sdl); 748 NEXTADDR(RTA_NETMASK, som); 749 750 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 751 doit: 752 l = rtm->rtm_msglen; 753 rtm->rtm_seq = ++seq; 754 rtm->rtm_type = cmd; 755 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 756 if (errno != ESRCH || cmd != RTM_DELETE) { 757 warn("writing to routing socket"); 758 return (NULL); 759 } 760 } 761 do { 762 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 763 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 764 if (l < 0) 765 warn("read from routing socket"); 766 return (rtm); 767 } 768 769 /* 770 * get_ether_addr - get the hardware address of an interface on the 771 * the same subnet as ipaddr. 772 */ 773 #define MAX_IFS 32 774 775 static int 776 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 777 { 778 struct ifreq *ifr, *ifend, *ifp; 779 in_addr_t ina, mask; 780 struct sockaddr_dl *dla; 781 struct ifreq ifreq; 782 struct ifconf ifc; 783 struct ifreq ifs[MAX_IFS]; 784 int sock; 785 int retval = 0; 786 787 sock = socket(AF_INET, SOCK_DGRAM, 0); 788 if (sock < 0) 789 err(1, "socket"); 790 791 ifc.ifc_len = sizeof(ifs); 792 ifc.ifc_req = ifs; 793 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 794 warnx("ioctl(SIOCGIFCONF)"); 795 goto done; 796 } 797 798 #define NEXTIFR(i) \ 799 ((struct ifreq *)((char *)&(i)->ifr_addr \ 800 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 801 802 /* 803 * Scan through looking for an interface with an Internet 804 * address on the same subnet as `ipaddr'. 805 */ 806 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 807 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 808 if (ifr->ifr_addr.sa_family != AF_INET) 809 continue; 810 strncpy(ifreq.ifr_name, ifr->ifr_name, 811 sizeof(ifreq.ifr_name)); 812 ifreq.ifr_addr = ifr->ifr_addr; 813 /* 814 * Check that the interface is up, 815 * and not point-to-point or loopback. 816 */ 817 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 818 continue; 819 if ((ifreq.ifr_flags & 820 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 821 IFF_LOOPBACK|IFF_NOARP)) 822 != (IFF_UP|IFF_BROADCAST)) 823 continue; 824 /* 825 * Get its netmask and check that it's on 826 * the right subnet. 827 */ 828 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 829 continue; 830 mask = ((struct sockaddr_in *) 831 &ifreq.ifr_addr)->sin_addr.s_addr; 832 ina = ((struct sockaddr_in *) 833 &ifr->ifr_addr)->sin_addr.s_addr; 834 if ((ipaddr & mask) == (ina & mask)) 835 break; /* ok, we got it! */ 836 } 837 838 if (ifr >= ifend) 839 goto done; 840 841 /* 842 * Now scan through again looking for a link-level address 843 * for this interface. 844 */ 845 ifp = ifr; 846 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 847 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 848 ifr->ifr_addr.sa_family == AF_LINK) 849 break; 850 if (ifr >= ifend) 851 goto done; 852 /* 853 * Found the link-level address - copy it out 854 */ 855 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 856 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 857 printf("using interface %s for proxy with address ", 858 ifp->ifr_name); 859 printf("%s\n", ether_ntoa(hwaddr)); 860 retval = dla->sdl_alen; 861 done: 862 close(sock); 863 return (retval); 864 } 865