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 struct if_nameindex *ifnameindex; 108 109 /* which function we're supposed to do */ 110 #define F_GET 1 111 #define F_SET 2 112 #define F_FILESET 3 113 #define F_REPLACE 4 114 #define F_DELETE 5 115 116 #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 int aflag = 0; /* do it for all entries */ 124 125 while ((ch = getopt(argc, argv, "andfsSi:")) != -1) 126 switch(ch) { 127 case 'a': 128 aflag = 1; 129 break; 130 case 'd': 131 SETFUNC(F_DELETE); 132 break; 133 case 'n': 134 nflag = 1; 135 break; 136 case 'S': 137 SETFUNC(F_REPLACE); 138 break; 139 case 's': 140 SETFUNC(F_SET); 141 break; 142 case 'f' : 143 SETFUNC(F_FILESET); 144 break; 145 case 'i': 146 rifname = optarg; 147 break; 148 case '?': 149 default: 150 usage(); 151 } 152 argc -= optind; 153 argv += optind; 154 155 if (!func) 156 func = F_GET; 157 if (rifname) { 158 if (func != F_GET && !(func == F_DELETE && aflag)) 159 errx(1, "-i not applicable to this operation"); 160 if (if_nametoindex(rifname) == 0) { 161 if (errno == ENXIO) 162 errx(1, "interface %s does not exist", rifname); 163 else 164 err(1, "if_nametoindex(%s)", rifname); 165 } 166 } 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 rtn = 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 (void)delete(argv[0]); 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) 194 usage(); 195 rtn = delete(argv[0]); 196 } 197 break; 198 case F_FILESET: 199 if (argc != 1) 200 usage(); 201 rtn = file(argv[0]); 202 break; 203 } 204 205 if (ifnameindex != NULL) 206 if_freenameindex(ifnameindex); 207 208 return (rtn); 209 } 210 211 /* 212 * Process a file to set standard arp entries 213 */ 214 static int 215 file(char *name) 216 { 217 FILE *fp; 218 int i, retval; 219 char line[100], arg[5][50], *args[5], *p; 220 221 if ((fp = fopen(name, "r")) == NULL) 222 err(1, "cannot open %s", name); 223 args[0] = &arg[0][0]; 224 args[1] = &arg[1][0]; 225 args[2] = &arg[2][0]; 226 args[3] = &arg[3][0]; 227 args[4] = &arg[4][0]; 228 retval = 0; 229 while(fgets(line, sizeof(line), fp) != NULL) { 230 if ((p = strchr(line, '#')) != NULL) 231 *p = '\0'; 232 for (p = line; isblank(*p); p++); 233 if (*p == '\n' || *p == '\0') 234 continue; 235 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 236 arg[2], arg[3], arg[4]); 237 if (i < 2) { 238 warnx("bad line: %s", line); 239 retval = 1; 240 continue; 241 } 242 if (set(i, args)) 243 retval = 1; 244 } 245 fclose(fp); 246 return (retval); 247 } 248 249 /* 250 * Given a hostname, fills up a (static) struct sockaddr_in with 251 * the address of the host and returns a pointer to the 252 * structure. 253 */ 254 static struct sockaddr_in * 255 getaddr(char *host) 256 { 257 struct hostent *hp; 258 static struct sockaddr_in reply; 259 260 bzero(&reply, sizeof(reply)); 261 reply.sin_len = sizeof(reply); 262 reply.sin_family = AF_INET; 263 reply.sin_addr.s_addr = inet_addr(host); 264 if (reply.sin_addr.s_addr == INADDR_NONE) { 265 if (!(hp = gethostbyname(host))) { 266 warnx("%s: %s", host, hstrerror(h_errno)); 267 return (NULL); 268 } 269 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 270 sizeof reply.sin_addr); 271 } 272 return (&reply); 273 } 274 275 /* 276 * Returns true if the type is a valid one for ARP. 277 */ 278 static int 279 valid_type(int type) 280 { 281 282 switch (type) { 283 case IFT_ETHER: 284 case IFT_FDDI: 285 case IFT_INFINIBAND: 286 case IFT_ISO88023: 287 case IFT_ISO88024: 288 case IFT_ISO88025: 289 case IFT_L2VLAN: 290 case IFT_BRIDGE: 291 return (1); 292 default: 293 return (0); 294 } 295 } 296 297 /* 298 * Set an individual arp entry 299 */ 300 static int 301 set(int argc, char **argv) 302 { 303 struct sockaddr_in *addr; 304 struct sockaddr_in *dst; /* what are we looking for */ 305 struct sockaddr_dl *sdl; 306 struct rt_msghdr *rtm; 307 struct ether_addr *ea; 308 char *host = argv[0], *eaddr = argv[1]; 309 struct sockaddr_dl sdl_m; 310 311 argc -= 2; 312 argv += 2; 313 314 bzero(&sdl_m, sizeof(sdl_m)); 315 sdl_m.sdl_len = sizeof(sdl_m); 316 sdl_m.sdl_family = AF_LINK; 317 318 dst = getaddr(host); 319 if (dst == NULL) 320 return (1); 321 doing_proxy = flags = expire_time = 0; 322 while (argc-- > 0) { 323 if (strncmp(argv[0], "temp", 4) == 0) { 324 struct timespec tp; 325 int max_age; 326 size_t len = sizeof(max_age); 327 328 clock_gettime(CLOCK_MONOTONIC, &tp); 329 if (sysctlbyname("net.link.ether.inet.max_age", 330 &max_age, &len, NULL, 0) != 0) 331 err(1, "sysctlbyname"); 332 expire_time = tp.tv_sec + max_age; 333 } else if (strncmp(argv[0], "pub", 3) == 0) { 334 flags |= RTF_ANNOUNCE; 335 doing_proxy = 1; 336 if (argc && strncmp(argv[1], "only", 3) == 0) { 337 /* 338 * Compatibility: in pre FreeBSD 8 times 339 * the "only" keyword used to mean that 340 * an ARP entry should be announced, but 341 * not installed into routing table. 342 */ 343 argc--; argv++; 344 } 345 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 346 if (flags & RTF_REJECT) { 347 printf("Choose one of blackhole or reject, not both.\n"); 348 } 349 flags |= RTF_BLACKHOLE; 350 } else if (strncmp(argv[0], "reject", 6) == 0) { 351 if (flags & RTF_BLACKHOLE) { 352 printf("Choose one of blackhole or reject, not both.\n"); 353 } 354 flags |= RTF_REJECT; 355 } else if (strncmp(argv[0], "trail", 5) == 0) { 356 /* XXX deprecated and undocumented feature */ 357 printf("%s: Sending trailers is no longer supported\n", 358 host); 359 } 360 argv++; 361 } 362 ea = (struct ether_addr *)LLADDR(&sdl_m); 363 if (doing_proxy && !strcmp(eaddr, "auto")) { 364 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 365 printf("no interface found for %s\n", 366 inet_ntoa(dst->sin_addr)); 367 return (1); 368 } 369 sdl_m.sdl_alen = ETHER_ADDR_LEN; 370 } else { 371 struct ether_addr *ea1 = ether_aton(eaddr); 372 373 if (ea1 == NULL) { 374 warnx("invalid Ethernet address '%s'", eaddr); 375 return (1); 376 } else { 377 *ea = *ea1; 378 sdl_m.sdl_alen = ETHER_ADDR_LEN; 379 } 380 } 381 382 /* 383 * In the case a proxy-arp entry is being added for 384 * a remote end point, the RTF_ANNOUNCE flag in the 385 * RTM_GET command is an indication to the kernel 386 * routing code that the interface associated with 387 * the prefix route covering the local end of the 388 * PPP link should be returned, on which ARP applies. 389 */ 390 rtm = rtmsg(RTM_GET, dst, &sdl_m); 391 if (rtm == NULL) { 392 warn("%s", host); 393 return (1); 394 } 395 addr = (struct sockaddr_in *)(rtm + 1); 396 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 397 398 if ((sdl->sdl_family != AF_LINK) || 399 (rtm->rtm_flags & RTF_GATEWAY) || 400 !valid_type(sdl->sdl_type)) { 401 printf("cannot intuit interface index and type for %s\n", host); 402 return (1); 403 } 404 sdl_m.sdl_type = sdl->sdl_type; 405 sdl_m.sdl_index = sdl->sdl_index; 406 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 407 } 408 409 /* 410 * Display an individual arp entry 411 */ 412 static int 413 get(char *host) 414 { 415 struct sockaddr_in *addr; 416 417 addr = getaddr(host); 418 if (addr == NULL) 419 return (1); 420 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 421 printf("%s (%s) -- no entry", 422 host, inet_ntoa(addr->sin_addr)); 423 if (rifname) 424 printf(" on %s", rifname); 425 printf("\n"); 426 return (1); 427 } 428 return (0); 429 } 430 431 /* 432 * Delete an arp entry 433 */ 434 static int 435 delete(char *host) 436 { 437 struct sockaddr_in *addr, *dst; 438 struct rt_msghdr *rtm; 439 struct sockaddr_dl *sdl; 440 struct sockaddr_dl sdl_m; 441 442 dst = getaddr(host); 443 if (dst == NULL) 444 return (1); 445 446 /* 447 * Perform a regular entry delete first. 448 */ 449 flags &= ~RTF_ANNOUNCE; 450 451 /* 452 * setup the data structure to notify the kernel 453 * it is the ARP entry the RTM_GET is interested 454 * in 455 */ 456 bzero(&sdl_m, sizeof(sdl_m)); 457 sdl_m.sdl_len = sizeof(sdl_m); 458 sdl_m.sdl_family = AF_LINK; 459 460 for (;;) { /* try twice */ 461 rtm = rtmsg(RTM_GET, dst, &sdl_m); 462 if (rtm == NULL) { 463 warn("%s", host); 464 return (1); 465 } 466 addr = (struct sockaddr_in *)(rtm + 1); 467 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 468 469 /* 470 * With the new L2/L3 restructure, the route 471 * returned is a prefix route. The important 472 * piece of information from the previous 473 * RTM_GET is the interface index. In the 474 * case of ECMP, the kernel will traverse 475 * the route group for the given entry. 476 */ 477 if (sdl->sdl_family == AF_LINK && 478 !(rtm->rtm_flags & RTF_GATEWAY) && 479 valid_type(sdl->sdl_type) ) { 480 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 481 break; 482 } 483 484 /* 485 * Regualar entry delete failed, now check if there 486 * is a proxy-arp entry to remove. 487 */ 488 if (flags & RTF_ANNOUNCE) { 489 fprintf(stderr, "delete: cannot locate %s\n",host); 490 return (1); 491 } 492 493 flags |= RTF_ANNOUNCE; 494 } 495 rtm->rtm_flags |= RTF_LLDATA; 496 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 497 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 498 return (0); 499 } 500 return (1); 501 } 502 503 504 /* 505 * Search the arp table and do some action on matching entries 506 */ 507 static int 508 search(u_long addr, action_fn *action) 509 { 510 int mib[6]; 511 size_t needed; 512 char *lim, *buf, *next; 513 struct rt_msghdr *rtm; 514 struct sockaddr_in *sin2; 515 struct sockaddr_dl *sdl; 516 char ifname[IF_NAMESIZE]; 517 int st, found_entry = 0; 518 519 mib[0] = CTL_NET; 520 mib[1] = PF_ROUTE; 521 mib[2] = 0; 522 mib[3] = AF_INET; 523 mib[4] = NET_RT_FLAGS; 524 #ifdef RTF_LLINFO 525 mib[5] = RTF_LLINFO; 526 #else 527 mib[5] = 0; 528 #endif 529 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 530 err(1, "route-sysctl-estimate"); 531 if (needed == 0) /* empty table */ 532 return 0; 533 buf = NULL; 534 for (;;) { 535 buf = reallocf(buf, needed); 536 if (buf == NULL) 537 errx(1, "could not reallocate memory"); 538 st = sysctl(mib, 6, buf, &needed, NULL, 0); 539 if (st == 0 || errno != ENOMEM) 540 break; 541 needed += needed / 8; 542 } 543 if (st == -1) 544 err(1, "actual retrieval of routing table"); 545 lim = buf + needed; 546 for (next = buf; next < lim; next += rtm->rtm_msglen) { 547 rtm = (struct rt_msghdr *)next; 548 sin2 = (struct sockaddr_in *)(rtm + 1); 549 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 550 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 551 strcmp(ifname, rifname)) 552 continue; 553 if (addr) { 554 if (addr != sin2->sin_addr.s_addr) 555 continue; 556 found_entry = 1; 557 } 558 (*action)(sdl, sin2, rtm); 559 } 560 free(buf); 561 return (found_entry); 562 } 563 564 /* 565 * Display an arp entry 566 */ 567 568 static void 569 print_entry(struct sockaddr_dl *sdl, 570 struct sockaddr_in *addr, struct rt_msghdr *rtm) 571 { 572 const char *host; 573 struct hostent *hp; 574 struct iso88025_sockaddr_dl_data *trld; 575 struct if_nameindex *p; 576 int seg; 577 578 if (ifnameindex == NULL) 579 if ((ifnameindex = if_nameindex()) == NULL) 580 err(1, "cannot retrieve interface names"); 581 582 if (nflag == 0) 583 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 584 sizeof addr->sin_addr, AF_INET); 585 else 586 hp = 0; 587 if (hp) 588 host = hp->h_name; 589 else { 590 host = "?"; 591 if (h_errno == TRY_AGAIN) 592 nflag = 1; 593 } 594 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 595 if (sdl->sdl_alen) { 596 if ((sdl->sdl_type == IFT_ETHER || 597 sdl->sdl_type == IFT_L2VLAN || 598 sdl->sdl_type == IFT_BRIDGE) && 599 sdl->sdl_alen == ETHER_ADDR_LEN) 600 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 601 else { 602 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 603 604 printf("%s", link_ntoa(sdl) + n); 605 } 606 } else 607 printf("(incomplete)"); 608 609 for (p = ifnameindex; p && ifnameindex->if_index && 610 ifnameindex->if_name; p++) { 611 if (p->if_index == sdl->sdl_index) { 612 printf(" on %s", p->if_name); 613 break; 614 } 615 } 616 617 if (rtm->rtm_rmx.rmx_expire == 0) 618 printf(" permanent"); 619 else { 620 static struct timespec tp; 621 if (tp.tv_sec == 0) 622 clock_gettime(CLOCK_MONOTONIC, &tp); 623 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 624 printf(" expires in %d seconds", (int)expire_time); 625 else 626 printf(" expired"); 627 } 628 if (rtm->rtm_flags & RTF_ANNOUNCE) 629 printf(" published"); 630 switch(sdl->sdl_type) { 631 case IFT_ETHER: 632 printf(" [ethernet]"); 633 break; 634 case IFT_ISO88025: 635 printf(" [token-ring]"); 636 trld = SDL_ISO88025(sdl); 637 if (trld->trld_rcf != 0) { 638 printf(" rt=%x", ntohs(trld->trld_rcf)); 639 for (seg = 0; 640 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 641 seg++) 642 printf(":%x", ntohs(*(trld->trld_route[seg]))); 643 } 644 break; 645 case IFT_FDDI: 646 printf(" [fddi]"); 647 break; 648 case IFT_ATM: 649 printf(" [atm]"); 650 break; 651 case IFT_L2VLAN: 652 printf(" [vlan]"); 653 break; 654 case IFT_IEEE1394: 655 printf(" [firewire]"); 656 break; 657 case IFT_BRIDGE: 658 printf(" [bridge]"); 659 break; 660 case IFT_INFINIBAND: 661 printf(" [infiniband]"); 662 break; 663 default: 664 break; 665 } 666 667 printf("\n"); 668 669 } 670 671 /* 672 * Nuke an arp entry 673 */ 674 static void 675 nuke_entry(struct sockaddr_dl *sdl __unused, 676 struct sockaddr_in *addr, struct rt_msghdr *rtm) 677 { 678 char ip[20]; 679 680 if (rtm->rtm_flags & RTF_PINNED) 681 return; 682 683 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 684 delete(ip); 685 } 686 687 static void 688 usage(void) 689 { 690 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 691 "usage: arp [-n] [-i interface] hostname", 692 " arp [-n] [-i interface] -a", 693 " arp -d hostname [pub]", 694 " arp -d [-i interface] -a", 695 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 696 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 697 " arp -f filename"); 698 exit(1); 699 } 700 701 static struct rt_msghdr * 702 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) 703 { 704 static int seq; 705 int rlen; 706 int l; 707 struct sockaddr_in so_mask, *som = &so_mask; 708 static int s = -1; 709 static pid_t pid; 710 711 static struct { 712 struct rt_msghdr m_rtm; 713 char m_space[512]; 714 } m_rtmsg; 715 716 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 717 char *cp = m_rtmsg.m_space; 718 719 if (s < 0) { /* first time: open socket, get pid */ 720 s = socket(PF_ROUTE, SOCK_RAW, 0); 721 if (s < 0) 722 err(1, "socket"); 723 pid = getpid(); 724 } 725 bzero(&so_mask, sizeof(so_mask)); 726 so_mask.sin_len = 8; 727 so_mask.sin_addr.s_addr = 0xffffffff; 728 729 errno = 0; 730 /* 731 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 732 * appropriately. 733 */ 734 if (cmd == RTM_DELETE) 735 goto doit; 736 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 737 rtm->rtm_flags = flags; 738 rtm->rtm_version = RTM_VERSION; 739 740 switch (cmd) { 741 default: 742 errx(1, "internal wrong cmd"); 743 case RTM_ADD: 744 rtm->rtm_addrs |= RTA_GATEWAY; 745 rtm->rtm_rmx.rmx_expire = expire_time; 746 rtm->rtm_inits = RTV_EXPIRE; 747 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 748 if (doing_proxy) { 749 rtm->rtm_addrs |= RTA_NETMASK; 750 rtm->rtm_flags &= ~RTF_HOST; 751 } 752 /* FALLTHROUGH */ 753 case RTM_GET: 754 rtm->rtm_addrs |= RTA_DST; 755 } 756 #define NEXTADDR(w, s) \ 757 do { \ 758 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 759 bcopy((s), cp, sizeof(*(s))); \ 760 cp += SA_SIZE(s); \ 761 } \ 762 } while (0) 763 764 NEXTADDR(RTA_DST, dst); 765 NEXTADDR(RTA_GATEWAY, sdl); 766 NEXTADDR(RTA_NETMASK, som); 767 768 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 769 doit: 770 l = rtm->rtm_msglen; 771 rtm->rtm_seq = ++seq; 772 rtm->rtm_type = cmd; 773 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 774 if (errno != ESRCH || cmd != RTM_DELETE) { 775 warn("writing to routing socket"); 776 return (NULL); 777 } 778 } 779 do { 780 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 781 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 782 if (l < 0) 783 warn("read from routing socket"); 784 return (rtm); 785 } 786 787 /* 788 * get_ether_addr - get the hardware address of an interface on the 789 * the same subnet as ipaddr. 790 */ 791 #define MAX_IFS 32 792 793 static int 794 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 795 { 796 struct ifreq *ifr, *ifend, *ifp; 797 in_addr_t ina, mask; 798 struct sockaddr_dl *dla; 799 struct ifreq ifreq; 800 struct ifconf ifc; 801 struct ifreq ifs[MAX_IFS]; 802 int sock; 803 int retval = 0; 804 805 sock = socket(AF_INET, SOCK_DGRAM, 0); 806 if (sock < 0) 807 err(1, "socket"); 808 809 ifc.ifc_len = sizeof(ifs); 810 ifc.ifc_req = ifs; 811 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 812 warnx("ioctl(SIOCGIFCONF)"); 813 goto done; 814 } 815 816 #define NEXTIFR(i) \ 817 ((struct ifreq *)((char *)&(i)->ifr_addr \ 818 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 819 820 /* 821 * Scan through looking for an interface with an Internet 822 * address on the same subnet as `ipaddr'. 823 */ 824 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 825 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 826 if (ifr->ifr_addr.sa_family != AF_INET) 827 continue; 828 strncpy(ifreq.ifr_name, ifr->ifr_name, 829 sizeof(ifreq.ifr_name)); 830 ifreq.ifr_addr = ifr->ifr_addr; 831 /* 832 * Check that the interface is up, 833 * and not point-to-point or loopback. 834 */ 835 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 836 continue; 837 if ((ifreq.ifr_flags & 838 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 839 IFF_LOOPBACK|IFF_NOARP)) 840 != (IFF_UP|IFF_BROADCAST)) 841 continue; 842 /* 843 * Get its netmask and check that it's on 844 * the right subnet. 845 */ 846 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 847 continue; 848 mask = ((struct sockaddr_in *) 849 &ifreq.ifr_addr)->sin_addr.s_addr; 850 ina = ((struct sockaddr_in *) 851 &ifr->ifr_addr)->sin_addr.s_addr; 852 if ((ipaddr & mask) == (ina & mask)) 853 break; /* ok, we got it! */ 854 } 855 856 if (ifr >= ifend) 857 goto done; 858 859 /* 860 * Now scan through again looking for a link-level address 861 * for this interface. 862 */ 863 ifp = ifr; 864 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 865 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 866 ifr->ifr_addr.sa_family == AF_LINK) 867 break; 868 if (ifr >= ifend) 869 goto done; 870 /* 871 * Found the link-level address - copy it out 872 */ 873 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 874 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 875 printf("using interface %s for proxy with address ", 876 ifp->ifr_name); 877 printf("%s\n", ether_ntoa(hwaddr)); 878 retval = dla->sdl_alen; 879 done: 880 close(sock); 881 return (retval); 882 } 883