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_ISO88023: 286 case IFT_ISO88024: 287 case IFT_ISO88025: 288 case IFT_L2VLAN: 289 case IFT_BRIDGE: 290 return (1); 291 default: 292 return (0); 293 } 294 } 295 296 /* 297 * Set an individual arp entry 298 */ 299 static int 300 set(int argc, char **argv) 301 { 302 struct sockaddr_in *addr; 303 struct sockaddr_in *dst; /* what are we looking for */ 304 struct sockaddr_dl *sdl; 305 struct rt_msghdr *rtm; 306 struct ether_addr *ea; 307 char *host = argv[0], *eaddr = argv[1]; 308 struct sockaddr_dl sdl_m; 309 310 argc -= 2; 311 argv += 2; 312 313 bzero(&sdl_m, sizeof(sdl_m)); 314 sdl_m.sdl_len = sizeof(sdl_m); 315 sdl_m.sdl_family = AF_LINK; 316 317 dst = getaddr(host); 318 if (dst == NULL) 319 return (1); 320 doing_proxy = flags = expire_time = 0; 321 while (argc-- > 0) { 322 if (strncmp(argv[0], "temp", 4) == 0) { 323 struct timespec tp; 324 int max_age; 325 size_t len = sizeof(max_age); 326 327 clock_gettime(CLOCK_MONOTONIC, &tp); 328 if (sysctlbyname("net.link.ether.inet.max_age", 329 &max_age, &len, NULL, 0) != 0) 330 err(1, "sysctlbyname"); 331 expire_time = tp.tv_sec + max_age; 332 } else if (strncmp(argv[0], "pub", 3) == 0) { 333 flags |= RTF_ANNOUNCE; 334 doing_proxy = 1; 335 if (argc && strncmp(argv[1], "only", 3) == 0) { 336 /* 337 * Compatibility: in pre FreeBSD 8 times 338 * the "only" keyword used to mean that 339 * an ARP entry should be announced, but 340 * not installed into routing table. 341 */ 342 argc--; argv++; 343 } 344 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 345 if (flags & RTF_REJECT) { 346 printf("Choose one of blackhole or reject, not both.\n"); 347 } 348 flags |= RTF_BLACKHOLE; 349 } else if (strncmp(argv[0], "reject", 6) == 0) { 350 if (flags & RTF_BLACKHOLE) { 351 printf("Choose one of blackhole or reject, not both.\n"); 352 } 353 flags |= RTF_REJECT; 354 } else if (strncmp(argv[0], "trail", 5) == 0) { 355 /* XXX deprecated and undocumented feature */ 356 printf("%s: Sending trailers is no longer supported\n", 357 host); 358 } 359 argv++; 360 } 361 ea = (struct ether_addr *)LLADDR(&sdl_m); 362 if (doing_proxy && !strcmp(eaddr, "auto")) { 363 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 364 printf("no interface found for %s\n", 365 inet_ntoa(dst->sin_addr)); 366 return (1); 367 } 368 sdl_m.sdl_alen = ETHER_ADDR_LEN; 369 } else { 370 struct ether_addr *ea1 = ether_aton(eaddr); 371 372 if (ea1 == NULL) { 373 warnx("invalid Ethernet address '%s'", eaddr); 374 return (1); 375 } else { 376 *ea = *ea1; 377 sdl_m.sdl_alen = ETHER_ADDR_LEN; 378 } 379 } 380 381 /* 382 * In the case a proxy-arp entry is being added for 383 * a remote end point, the RTF_ANNOUNCE flag in the 384 * RTM_GET command is an indication to the kernel 385 * routing code that the interface associated with 386 * the prefix route covering the local end of the 387 * PPP link should be returned, on which ARP applies. 388 */ 389 rtm = rtmsg(RTM_GET, dst, &sdl_m); 390 if (rtm == NULL) { 391 warn("%s", host); 392 return (1); 393 } 394 addr = (struct sockaddr_in *)(rtm + 1); 395 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 396 397 if ((sdl->sdl_family != AF_LINK) || 398 (rtm->rtm_flags & RTF_GATEWAY) || 399 !valid_type(sdl->sdl_type)) { 400 printf("cannot intuit interface index and type for %s\n", host); 401 return (1); 402 } 403 sdl_m.sdl_type = sdl->sdl_type; 404 sdl_m.sdl_index = sdl->sdl_index; 405 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 406 } 407 408 /* 409 * Display an individual arp entry 410 */ 411 static int 412 get(char *host) 413 { 414 struct sockaddr_in *addr; 415 416 addr = getaddr(host); 417 if (addr == NULL) 418 return (1); 419 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 420 printf("%s (%s) -- no entry", 421 host, inet_ntoa(addr->sin_addr)); 422 if (rifname) 423 printf(" on %s", rifname); 424 printf("\n"); 425 return (1); 426 } 427 return (0); 428 } 429 430 /* 431 * Delete an arp entry 432 */ 433 static int 434 delete(char *host) 435 { 436 struct sockaddr_in *addr, *dst; 437 struct rt_msghdr *rtm; 438 struct sockaddr_dl *sdl; 439 struct sockaddr_dl sdl_m; 440 441 dst = getaddr(host); 442 if (dst == NULL) 443 return (1); 444 445 /* 446 * Perform a regular entry delete first. 447 */ 448 flags &= ~RTF_ANNOUNCE; 449 450 /* 451 * setup the data structure to notify the kernel 452 * it is the ARP entry the RTM_GET is interested 453 * in 454 */ 455 bzero(&sdl_m, sizeof(sdl_m)); 456 sdl_m.sdl_len = sizeof(sdl_m); 457 sdl_m.sdl_family = AF_LINK; 458 459 for (;;) { /* try twice */ 460 rtm = rtmsg(RTM_GET, dst, &sdl_m); 461 if (rtm == NULL) { 462 warn("%s", host); 463 return (1); 464 } 465 addr = (struct sockaddr_in *)(rtm + 1); 466 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 467 468 /* 469 * With the new L2/L3 restructure, the route 470 * returned is a prefix route. The important 471 * piece of information from the previous 472 * RTM_GET is the interface index. In the 473 * case of ECMP, the kernel will traverse 474 * the route group for the given entry. 475 */ 476 if (sdl->sdl_family == AF_LINK && 477 !(rtm->rtm_flags & RTF_GATEWAY) && 478 valid_type(sdl->sdl_type) ) { 479 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 480 break; 481 } 482 483 /* 484 * Regualar entry delete failed, now check if there 485 * is a proxy-arp entry to remove. 486 */ 487 if (flags & RTF_ANNOUNCE) { 488 fprintf(stderr, "delete: cannot locate %s\n",host); 489 return (1); 490 } 491 492 flags |= RTF_ANNOUNCE; 493 } 494 rtm->rtm_flags |= RTF_LLDATA; 495 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 496 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 497 return (0); 498 } 499 return (1); 500 } 501 502 503 /* 504 * Search the arp table and do some action on matching entries 505 */ 506 static int 507 search(u_long addr, action_fn *action) 508 { 509 int mib[6]; 510 size_t needed; 511 char *lim, *buf, *next; 512 struct rt_msghdr *rtm; 513 struct sockaddr_in *sin2; 514 struct sockaddr_dl *sdl; 515 char ifname[IF_NAMESIZE]; 516 int st, found_entry = 0; 517 518 mib[0] = CTL_NET; 519 mib[1] = PF_ROUTE; 520 mib[2] = 0; 521 mib[3] = AF_INET; 522 mib[4] = NET_RT_FLAGS; 523 #ifdef RTF_LLINFO 524 mib[5] = RTF_LLINFO; 525 #else 526 mib[5] = 0; 527 #endif 528 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 529 err(1, "route-sysctl-estimate"); 530 if (needed == 0) /* empty table */ 531 return 0; 532 buf = NULL; 533 for (;;) { 534 buf = reallocf(buf, needed); 535 if (buf == NULL) 536 errx(1, "could not reallocate memory"); 537 st = sysctl(mib, 6, buf, &needed, NULL, 0); 538 if (st == 0 || errno != ENOMEM) 539 break; 540 needed += needed / 8; 541 } 542 if (st == -1) 543 err(1, "actual retrieval of routing table"); 544 lim = buf + needed; 545 for (next = buf; next < lim; next += rtm->rtm_msglen) { 546 rtm = (struct rt_msghdr *)next; 547 sin2 = (struct sockaddr_in *)(rtm + 1); 548 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 549 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 550 strcmp(ifname, rifname)) 551 continue; 552 if (addr) { 553 if (addr != sin2->sin_addr.s_addr) 554 continue; 555 found_entry = 1; 556 } 557 (*action)(sdl, sin2, rtm); 558 } 559 free(buf); 560 return (found_entry); 561 } 562 563 /* 564 * Display an arp entry 565 */ 566 567 static void 568 print_entry(struct sockaddr_dl *sdl, 569 struct sockaddr_in *addr, struct rt_msghdr *rtm) 570 { 571 const char *host; 572 struct hostent *hp; 573 struct iso88025_sockaddr_dl_data *trld; 574 struct if_nameindex *p; 575 int seg; 576 577 if (ifnameindex == NULL) 578 if ((ifnameindex = if_nameindex()) == NULL) 579 err(1, "cannot retrieve interface names"); 580 581 if (nflag == 0) 582 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 583 sizeof addr->sin_addr, AF_INET); 584 else 585 hp = 0; 586 if (hp) 587 host = hp->h_name; 588 else { 589 host = "?"; 590 if (h_errno == TRY_AGAIN) 591 nflag = 1; 592 } 593 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 594 if (sdl->sdl_alen) { 595 if ((sdl->sdl_type == IFT_ETHER || 596 sdl->sdl_type == IFT_L2VLAN || 597 sdl->sdl_type == IFT_BRIDGE) && 598 sdl->sdl_alen == ETHER_ADDR_LEN) 599 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 600 else { 601 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 602 603 printf("%s", link_ntoa(sdl) + n); 604 } 605 } else 606 printf("(incomplete)"); 607 608 for (p = ifnameindex; p && ifnameindex->if_index && 609 ifnameindex->if_name; p++) { 610 if (p->if_index == sdl->sdl_index) { 611 printf(" on %s", p->if_name); 612 break; 613 } 614 } 615 616 if (rtm->rtm_rmx.rmx_expire == 0) 617 printf(" permanent"); 618 else { 619 static struct timespec tp; 620 if (tp.tv_sec == 0) 621 clock_gettime(CLOCK_MONOTONIC, &tp); 622 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 623 printf(" expires in %d seconds", (int)expire_time); 624 else 625 printf(" expired"); 626 } 627 if (rtm->rtm_flags & RTF_ANNOUNCE) 628 printf(" published"); 629 switch(sdl->sdl_type) { 630 case IFT_ETHER: 631 printf(" [ethernet]"); 632 break; 633 case IFT_ISO88025: 634 printf(" [token-ring]"); 635 trld = SDL_ISO88025(sdl); 636 if (trld->trld_rcf != 0) { 637 printf(" rt=%x", ntohs(trld->trld_rcf)); 638 for (seg = 0; 639 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 640 seg++) 641 printf(":%x", ntohs(*(trld->trld_route[seg]))); 642 } 643 break; 644 case IFT_FDDI: 645 printf(" [fddi]"); 646 break; 647 case IFT_ATM: 648 printf(" [atm]"); 649 break; 650 case IFT_L2VLAN: 651 printf(" [vlan]"); 652 break; 653 case IFT_IEEE1394: 654 printf(" [firewire]"); 655 break; 656 case IFT_BRIDGE: 657 printf(" [bridge]"); 658 break; 659 default: 660 break; 661 } 662 663 printf("\n"); 664 665 } 666 667 /* 668 * Nuke an arp entry 669 */ 670 static void 671 nuke_entry(struct sockaddr_dl *sdl __unused, 672 struct sockaddr_in *addr, struct rt_msghdr *rtm __unused) 673 { 674 char ip[20]; 675 676 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 677 delete(ip); 678 } 679 680 static void 681 usage(void) 682 { 683 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 684 "usage: arp [-n] [-i interface] hostname", 685 " arp [-n] [-i interface] -a", 686 " arp -d hostname [pub]", 687 " arp -d [-i interface] -a", 688 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 689 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 690 " arp -f filename"); 691 exit(1); 692 } 693 694 static struct rt_msghdr * 695 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) 696 { 697 static int seq; 698 int rlen; 699 int l; 700 struct sockaddr_in so_mask, *som = &so_mask; 701 static int s = -1; 702 static pid_t pid; 703 704 static struct { 705 struct rt_msghdr m_rtm; 706 char m_space[512]; 707 } m_rtmsg; 708 709 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 710 char *cp = m_rtmsg.m_space; 711 712 if (s < 0) { /* first time: open socket, get pid */ 713 s = socket(PF_ROUTE, SOCK_RAW, 0); 714 if (s < 0) 715 err(1, "socket"); 716 pid = getpid(); 717 } 718 bzero(&so_mask, sizeof(so_mask)); 719 so_mask.sin_len = 8; 720 so_mask.sin_addr.s_addr = 0xffffffff; 721 722 errno = 0; 723 /* 724 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 725 * appropriately. 726 */ 727 if (cmd == RTM_DELETE) 728 goto doit; 729 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 730 rtm->rtm_flags = flags; 731 rtm->rtm_version = RTM_VERSION; 732 733 switch (cmd) { 734 default: 735 errx(1, "internal wrong cmd"); 736 case RTM_ADD: 737 rtm->rtm_addrs |= RTA_GATEWAY; 738 rtm->rtm_rmx.rmx_expire = expire_time; 739 rtm->rtm_inits = RTV_EXPIRE; 740 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 741 if (doing_proxy) { 742 rtm->rtm_addrs |= RTA_NETMASK; 743 rtm->rtm_flags &= ~RTF_HOST; 744 } 745 /* FALLTHROUGH */ 746 case RTM_GET: 747 rtm->rtm_addrs |= RTA_DST; 748 } 749 #define NEXTADDR(w, s) \ 750 do { \ 751 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 752 bcopy((s), cp, sizeof(*(s))); \ 753 cp += SA_SIZE(s); \ 754 } \ 755 } while (0) 756 757 NEXTADDR(RTA_DST, dst); 758 NEXTADDR(RTA_GATEWAY, sdl); 759 NEXTADDR(RTA_NETMASK, som); 760 761 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 762 doit: 763 l = rtm->rtm_msglen; 764 rtm->rtm_seq = ++seq; 765 rtm->rtm_type = cmd; 766 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 767 if (errno != ESRCH || cmd != RTM_DELETE) { 768 warn("writing to routing socket"); 769 return (NULL); 770 } 771 } 772 do { 773 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 774 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 775 if (l < 0) 776 warn("read from routing socket"); 777 return (rtm); 778 } 779 780 /* 781 * get_ether_addr - get the hardware address of an interface on the 782 * the same subnet as ipaddr. 783 */ 784 #define MAX_IFS 32 785 786 static int 787 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 788 { 789 struct ifreq *ifr, *ifend, *ifp; 790 in_addr_t ina, mask; 791 struct sockaddr_dl *dla; 792 struct ifreq ifreq; 793 struct ifconf ifc; 794 struct ifreq ifs[MAX_IFS]; 795 int sock; 796 int retval = 0; 797 798 sock = socket(AF_INET, SOCK_DGRAM, 0); 799 if (sock < 0) 800 err(1, "socket"); 801 802 ifc.ifc_len = sizeof(ifs); 803 ifc.ifc_req = ifs; 804 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 805 warnx("ioctl(SIOCGIFCONF)"); 806 goto done; 807 } 808 809 #define NEXTIFR(i) \ 810 ((struct ifreq *)((char *)&(i)->ifr_addr \ 811 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 812 813 /* 814 * Scan through looking for an interface with an Internet 815 * address on the same subnet as `ipaddr'. 816 */ 817 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 818 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 819 if (ifr->ifr_addr.sa_family != AF_INET) 820 continue; 821 strncpy(ifreq.ifr_name, ifr->ifr_name, 822 sizeof(ifreq.ifr_name)); 823 ifreq.ifr_addr = ifr->ifr_addr; 824 /* 825 * Check that the interface is up, 826 * and not point-to-point or loopback. 827 */ 828 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 829 continue; 830 if ((ifreq.ifr_flags & 831 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 832 IFF_LOOPBACK|IFF_NOARP)) 833 != (IFF_UP|IFF_BROADCAST)) 834 continue; 835 /* 836 * Get its netmask and check that it's on 837 * the right subnet. 838 */ 839 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 840 continue; 841 mask = ((struct sockaddr_in *) 842 &ifreq.ifr_addr)->sin_addr.s_addr; 843 ina = ((struct sockaddr_in *) 844 &ifr->ifr_addr)->sin_addr.s_addr; 845 if ((ipaddr & mask) == (ina & mask)) 846 break; /* ok, we got it! */ 847 } 848 849 if (ifr >= ifend) 850 goto done; 851 852 /* 853 * Now scan through again looking for a link-level address 854 * for this interface. 855 */ 856 ifp = ifr; 857 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 858 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 859 ifr->ifr_addr.sa_family == AF_LINK) 860 break; 861 if (ifr >= ifend) 862 goto done; 863 /* 864 * Found the link-level address - copy it out 865 */ 866 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 867 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 868 printf("using interface %s for proxy with address ", 869 ifp->ifr_name); 870 printf("%s\n", ether_ntoa(hwaddr)); 871 retval = dla->sdl_alen; 872 done: 873 close(sock); 874 return (retval); 875 } 876