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