1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1984, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Sun Microsystems, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if 0 36 #ifndef lint 37 static char const copyright[] = 38 "@(#) Copyright (c) 1984, 1993\n\ 39 The Regents of the University of California. All rights reserved.\n"; 40 #endif /* not lint */ 41 42 #ifndef lint 43 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; 44 #endif /* not lint */ 45 #endif 46 #include <sys/cdefs.h> 47 __FBSDID("$FreeBSD$"); 48 49 /* 50 * arp - display, set, and delete arp table entries 51 */ 52 53 #include <sys/param.h> 54 #include <sys/file.h> 55 #include <sys/socket.h> 56 #include <sys/sockio.h> 57 #include <sys/sysctl.h> 58 #include <sys/ioctl.h> 59 #include <sys/time.h> 60 61 #include <net/if.h> 62 #include <net/if_dl.h> 63 #include <net/if_types.h> 64 #include <net/route.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 <stdbool.h> 78 #include <stdio.h> 79 #include <stdlib.h> 80 #include <string.h> 81 #include <strings.h> 82 #include <unistd.h> 83 #include <ifaddrs.h> 84 #include <libxo/xo.h> 85 #include "arp.h" 86 87 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in, 88 struct rt_msghdr *rtm); 89 static void nuke_entries(uint32_t ifindex, struct in_addr addr); 90 static int print_entries(uint32_t ifindex, struct in_addr addr); 91 92 static int delete(char *host); 93 static void usage(void) __dead2; 94 static int set(int argc, char **argv); 95 static int get(char *host); 96 static int file(char *name); 97 static struct rt_msghdr *rtmsg(int cmd, 98 struct sockaddr_in *dst, struct sockaddr_dl *sdl); 99 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); 100 static int set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, 101 char *host); 102 103 static char *rifname; 104 105 struct if_nameindex *ifnameindex; 106 107 struct arp_opts opts = {}; 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 #define ARP_XO_VERSION "1" 119 120 int 121 main(int argc, char *argv[]) 122 { 123 int ch, func = 0; 124 int rtn = 0; 125 126 argc = xo_parse_args(argc, argv); 127 if (argc < 0) 128 exit(1); 129 130 while ((ch = getopt(argc, argv, "andfsSi:")) != -1) 131 switch(ch) { 132 case 'a': 133 opts.aflag = true; 134 break; 135 case 'd': 136 SETFUNC(F_DELETE); 137 break; 138 case 'n': 139 opts.nflag = true; 140 break; 141 case 'S': 142 SETFUNC(F_REPLACE); 143 break; 144 case 's': 145 SETFUNC(F_SET); 146 break; 147 case 'f' : 148 SETFUNC(F_FILESET); 149 break; 150 case 'i': 151 rifname = optarg; 152 break; 153 case '?': 154 default: 155 usage(); 156 } 157 argc -= optind; 158 argv += optind; 159 160 if (!func) 161 func = F_GET; 162 if (rifname) { 163 if (func != F_GET && !(func == F_DELETE && opts.aflag)) 164 xo_errx(1, "-i not applicable to this operation"); 165 if (if_nametoindex(rifname) == 0) { 166 if (errno == ENXIO) 167 xo_errx(1, "interface %s does not exist", 168 rifname); 169 else 170 xo_err(1, "if_nametoindex(%s)", rifname); 171 } 172 } 173 switch (func) { 174 case F_GET: 175 if (opts.aflag) { 176 if (argc != 0) 177 usage(); 178 179 xo_set_version(ARP_XO_VERSION); 180 xo_open_container("arp"); 181 xo_open_list("arp-cache"); 182 183 struct in_addr all_addrs = {}; 184 print_entries(0, all_addrs); 185 186 xo_close_list("arp-cache"); 187 xo_close_container("arp"); 188 xo_finish(); 189 } else { 190 if (argc != 1) 191 usage(); 192 rtn = get(argv[0]); 193 } 194 break; 195 case F_SET: 196 case F_REPLACE: 197 if (argc < 2 || argc > 6) 198 usage(); 199 if (func == F_REPLACE) 200 (void)delete(argv[0]); 201 rtn = set(argc, argv) ? 1 : 0; 202 break; 203 case F_DELETE: 204 if (opts.aflag) { 205 if (argc != 0) 206 usage(); 207 struct in_addr all_addrs = {}; 208 nuke_entries(0, all_addrs); 209 } else { 210 if (argc != 1) 211 usage(); 212 rtn = delete(argv[0]); 213 } 214 break; 215 case F_FILESET: 216 if (argc != 1) 217 usage(); 218 rtn = file(argv[0]); 219 break; 220 } 221 222 if (ifnameindex != NULL) 223 if_freenameindex(ifnameindex); 224 225 return (rtn); 226 } 227 228 /* 229 * Process a file to set standard arp entries 230 */ 231 static int 232 file(char *name) 233 { 234 FILE *fp; 235 int i, retval; 236 char line[100], arg[5][50], *args[5], *p; 237 238 if ((fp = fopen(name, "r")) == NULL) 239 xo_err(1, "cannot open %s", name); 240 args[0] = &arg[0][0]; 241 args[1] = &arg[1][0]; 242 args[2] = &arg[2][0]; 243 args[3] = &arg[3][0]; 244 args[4] = &arg[4][0]; 245 retval = 0; 246 while(fgets(line, sizeof(line), fp) != NULL) { 247 if ((p = strchr(line, '#')) != NULL) 248 *p = '\0'; 249 for (p = line; isblank(*p); p++); 250 if (*p == '\n' || *p == '\0') 251 continue; 252 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 253 arg[2], arg[3], arg[4]); 254 if (i < 2) { 255 xo_warnx("bad line: %s", line); 256 retval = 1; 257 continue; 258 } 259 if (set(i, args)) 260 retval = 1; 261 } 262 fclose(fp); 263 return (retval); 264 } 265 266 /* 267 * Given a hostname, fills up a (static) struct sockaddr_in with 268 * the address of the host and returns a pointer to the 269 * structure. 270 */ 271 struct sockaddr_in * 272 getaddr(char *host) 273 { 274 struct hostent *hp; 275 static struct sockaddr_in reply; 276 277 bzero(&reply, sizeof(reply)); 278 reply.sin_len = sizeof(reply); 279 reply.sin_family = AF_INET; 280 reply.sin_addr.s_addr = inet_addr(host); 281 if (reply.sin_addr.s_addr == INADDR_NONE) { 282 if (!(hp = gethostbyname(host))) { 283 xo_warnx("%s: %s", host, hstrerror(h_errno)); 284 return (NULL); 285 } 286 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 287 sizeof reply.sin_addr); 288 } 289 return (&reply); 290 } 291 292 int valid_type(int type); 293 /* 294 * Returns true if the type is a valid one for ARP. 295 */ 296 int 297 valid_type(int type) 298 { 299 300 switch (type) { 301 case IFT_ETHER: 302 case IFT_FDDI: 303 case IFT_IEEE1394: 304 case IFT_INFINIBAND: 305 case IFT_ISO88023: 306 case IFT_ISO88024: 307 case IFT_L2VLAN: 308 case IFT_BRIDGE: 309 return (1); 310 default: 311 return (0); 312 } 313 } 314 315 /* 316 * Set an individual arp entry 317 */ 318 static int 319 set(int argc, char **argv) 320 { 321 struct sockaddr_in *dst; /* what are we looking for */ 322 struct ether_addr *ea; 323 char *host = argv[0], *eaddr = argv[1]; 324 struct sockaddr_dl sdl_m; 325 326 argc -= 2; 327 argv += 2; 328 329 bzero(&sdl_m, sizeof(sdl_m)); 330 sdl_m.sdl_len = sizeof(sdl_m); 331 sdl_m.sdl_family = AF_LINK; 332 333 dst = getaddr(host); 334 if (dst == NULL) 335 return (1); 336 while (argc-- > 0) { 337 if (strcmp(argv[0], "temp") == 0) { 338 int max_age; 339 size_t len = sizeof(max_age); 340 341 if (sysctlbyname("net.link.ether.inet.max_age", 342 &max_age, &len, NULL, 0) != 0) 343 xo_err(1, "sysctlbyname"); 344 opts.expire_time = max_age; 345 } else if (strcmp(argv[0], "pub") == 0) { 346 opts.flags |= RTF_ANNOUNCE; 347 if (argc && strcmp(argv[1], "only") == 0) { 348 /* 349 * Compatibility: in pre FreeBSD 8 times 350 * the "only" keyword used to mean that 351 * an ARP entry should be announced, but 352 * not installed into routing table. 353 */ 354 argc--; argv++; 355 } 356 } else if (strcmp(argv[0], "blackhole") == 0) { 357 if (opts.flags & RTF_REJECT) { 358 xo_errx(1, "Choose one of blackhole or reject, " 359 "not both."); 360 } 361 opts.flags |= RTF_BLACKHOLE; 362 } else if (strcmp(argv[0], "reject") == 0) { 363 if (opts.flags & RTF_BLACKHOLE) { 364 xo_errx(1, "Choose one of blackhole or reject, " 365 "not both."); 366 } 367 opts.flags |= RTF_REJECT; 368 } else { 369 xo_warnx("Invalid parameter '%s'", argv[0]); 370 usage(); 371 } 372 argv++; 373 } 374 ea = (struct ether_addr *)LLADDR(&sdl_m); 375 if ((opts.flags & RTF_ANNOUNCE) && !strcmp(eaddr, "auto")) { 376 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 377 xo_warnx("no interface found for %s", 378 inet_ntoa(dst->sin_addr)); 379 return (1); 380 } 381 sdl_m.sdl_alen = ETHER_ADDR_LEN; 382 } else { 383 struct ether_addr *ea1 = ether_aton(eaddr); 384 385 if (ea1 == NULL) { 386 xo_warnx("invalid Ethernet address '%s'", eaddr); 387 return (1); 388 } else { 389 *ea = *ea1; 390 sdl_m.sdl_alen = ETHER_ADDR_LEN; 391 } 392 } 393 #ifndef WITHOUT_NETLINK 394 return (set_nl(0, dst, &sdl_m, host)); 395 #else 396 return (set_rtsock(dst, &sdl_m, host)); 397 #endif 398 } 399 400 #ifdef WITHOUT_NETLINK 401 static int 402 set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, char *host) 403 { 404 struct sockaddr_in *addr; 405 struct sockaddr_dl *sdl; 406 struct rt_msghdr *rtm; 407 408 /* 409 * In the case a proxy-arp entry is being added for 410 * a remote end point, the RTF_ANNOUNCE flag in the 411 * RTM_GET command is an indication to the kernel 412 * routing code that the interface associated with 413 * the prefix route covering the local end of the 414 * PPP link should be returned, on which ARP applies. 415 */ 416 rtm = rtmsg(RTM_GET, dst, NULL); 417 if (rtm == NULL) { 418 xo_warn("%s", host); 419 return (1); 420 } 421 addr = (struct sockaddr_in *)(rtm + 1); 422 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 423 424 if ((sdl->sdl_family != AF_LINK) || 425 (rtm->rtm_flags & RTF_GATEWAY) || 426 !valid_type(sdl->sdl_type)) { 427 xo_warnx("cannot intuit interface index and type for %s", host); 428 return (1); 429 } 430 sdl_m->sdl_type = sdl->sdl_type; 431 sdl_m->sdl_index = sdl->sdl_index; 432 return (rtmsg(RTM_ADD, dst, sdl_m) == NULL); 433 } 434 #endif 435 436 /* 437 * Display an individual arp entry 438 */ 439 static int 440 get(char *host) 441 { 442 struct sockaddr_in *addr; 443 int found; 444 445 addr = getaddr(host); 446 if (addr == NULL) 447 return (1); 448 449 xo_set_version(ARP_XO_VERSION); 450 xo_open_container("arp"); 451 xo_open_list("arp-cache"); 452 453 found = print_entries(0, addr->sin_addr); 454 455 if (found == 0) { 456 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry", 457 host, inet_ntoa(addr->sin_addr)); 458 if (rifname) 459 xo_emit(" on {d:interface/%s}", rifname); 460 xo_emit("\n"); 461 } 462 463 xo_close_list("arp-cache"); 464 xo_close_container("arp"); 465 xo_finish(); 466 467 return (found == 0); 468 } 469 470 /* 471 * Delete an arp entry 472 */ 473 #ifdef WITHOUT_NETLINK 474 static int 475 delete_rtsock(char *host) 476 { 477 struct sockaddr_in *addr, *dst; 478 struct rt_msghdr *rtm; 479 struct sockaddr_dl *sdl; 480 481 dst = getaddr(host); 482 if (dst == NULL) 483 return (1); 484 485 /* 486 * Perform a regular entry delete first. 487 */ 488 opts.flags &= ~RTF_ANNOUNCE; 489 490 for (;;) { /* try twice */ 491 rtm = rtmsg(RTM_GET, dst, NULL); 492 if (rtm == NULL) { 493 xo_warn("%s", host); 494 return (1); 495 } 496 addr = (struct sockaddr_in *)(rtm + 1); 497 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 498 499 /* 500 * With the new L2/L3 restructure, the route 501 * returned is a prefix route. The important 502 * piece of information from the previous 503 * RTM_GET is the interface index. In the 504 * case of ECMP, the kernel will traverse 505 * the route group for the given entry. 506 */ 507 if (sdl->sdl_family == AF_LINK && 508 !(rtm->rtm_flags & RTF_GATEWAY) && 509 valid_type(sdl->sdl_type) ) { 510 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 511 break; 512 } 513 514 /* 515 * Regular entry delete failed, now check if there 516 * is a proxy-arp entry to remove. 517 */ 518 if (opts.flags & RTF_ANNOUNCE) { 519 xo_warnx("delete: cannot locate %s", host); 520 return (1); 521 } 522 523 opts.flags |= RTF_ANNOUNCE; 524 } 525 rtm->rtm_flags |= RTF_LLDATA; 526 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 527 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 528 return (0); 529 } 530 return (1); 531 } 532 #endif 533 534 static int 535 delete(char *host) 536 { 537 #ifdef WITHOUT_NETLINK 538 return (delete_rtsock(host)); 539 #else 540 return (delete_nl(0, host)); 541 #endif 542 } 543 544 545 /* 546 * Search the arp table and do some action on matching entries 547 */ 548 static int 549 search(u_long addr, action_fn *action) 550 { 551 int mib[6]; 552 size_t needed; 553 char *lim, *buf, *next; 554 struct rt_msghdr *rtm; 555 struct sockaddr_in *sin2; 556 struct sockaddr_dl *sdl; 557 char ifname[IF_NAMESIZE]; 558 int st, found_entry = 0; 559 560 mib[0] = CTL_NET; 561 mib[1] = PF_ROUTE; 562 mib[2] = 0; 563 mib[3] = AF_INET; 564 mib[4] = NET_RT_FLAGS; 565 #ifdef RTF_LLINFO 566 mib[5] = RTF_LLINFO; 567 #else 568 mib[5] = 0; 569 #endif 570 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 571 xo_err(1, "route-sysctl-estimate"); 572 if (needed == 0) /* empty table */ 573 return 0; 574 buf = NULL; 575 for (;;) { 576 buf = reallocf(buf, needed); 577 if (buf == NULL) 578 xo_errx(1, "could not reallocate memory"); 579 st = sysctl(mib, 6, buf, &needed, NULL, 0); 580 if (st == 0 || errno != ENOMEM) 581 break; 582 needed += needed / 8; 583 } 584 if (st == -1) 585 xo_err(1, "actual retrieval of routing table"); 586 lim = buf + needed; 587 for (next = buf; next < lim; next += rtm->rtm_msglen) { 588 rtm = (struct rt_msghdr *)next; 589 sin2 = (struct sockaddr_in *)(rtm + 1); 590 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 591 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 592 strcmp(ifname, rifname)) 593 continue; 594 if (addr) { 595 if (addr != sin2->sin_addr.s_addr) 596 continue; 597 found_entry = 1; 598 } 599 (*action)(sdl, sin2, rtm); 600 } 601 free(buf); 602 return (found_entry); 603 } 604 605 /* 606 * Display an arp entry 607 */ 608 609 static void 610 print_entry(struct sockaddr_dl *sdl, 611 struct sockaddr_in *addr, struct rt_msghdr *rtm) 612 { 613 const char *host; 614 struct hostent *hp; 615 struct if_nameindex *p; 616 617 if (ifnameindex == NULL) 618 if ((ifnameindex = if_nameindex()) == NULL) 619 xo_err(1, "cannot retrieve interface names"); 620 621 xo_open_instance("arp-cache"); 622 623 if (!opts.nflag) 624 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 625 sizeof addr->sin_addr, AF_INET); 626 else 627 hp = 0; 628 if (hp) 629 host = hp->h_name; 630 else { 631 host = "?"; 632 if (h_errno == TRY_AGAIN) 633 opts.nflag = true; 634 } 635 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host, 636 inet_ntoa(addr->sin_addr)); 637 if (sdl->sdl_alen) { 638 if ((sdl->sdl_type == IFT_ETHER || 639 sdl->sdl_type == IFT_L2VLAN || 640 sdl->sdl_type == IFT_BRIDGE) && 641 sdl->sdl_alen == ETHER_ADDR_LEN) 642 xo_emit("{:mac-address/%s}", 643 ether_ntoa((struct ether_addr *)LLADDR(sdl))); 644 else { 645 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 646 647 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n); 648 } 649 } else 650 xo_emit("{d:/(incomplete)}{en:incomplete/true}"); 651 652 for (p = ifnameindex; p && p->if_index && p->if_name; p++) { 653 if (p->if_index == sdl->sdl_index) { 654 xo_emit(" on {:interface/%s}", p->if_name); 655 break; 656 } 657 } 658 659 if (rtm->rtm_rmx.rmx_expire == 0) 660 xo_emit("{d:/ permanent}{en:permanent/true}"); 661 else { 662 static struct timespec tp; 663 time_t expire_time = 0; 664 665 if (tp.tv_sec == 0) 666 clock_gettime(CLOCK_MONOTONIC, &tp); 667 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 668 xo_emit(" expires in {:expires/%d} seconds", 669 (int)expire_time); 670 else 671 xo_emit("{d:/ expired}{en:expired/true}"); 672 } 673 674 if (rtm->rtm_flags & RTF_ANNOUNCE) 675 xo_emit("{d:/ published}{en:published/true}"); 676 677 switch(sdl->sdl_type) { 678 case IFT_ETHER: 679 xo_emit(" [{:type/ethernet}]"); 680 break; 681 case IFT_FDDI: 682 xo_emit(" [{:type/fddi}]"); 683 break; 684 case IFT_ATM: 685 xo_emit(" [{:type/atm}]"); 686 break; 687 case IFT_L2VLAN: 688 xo_emit(" [{:type/vlan}]"); 689 break; 690 case IFT_IEEE1394: 691 xo_emit(" [{:type/firewire}]"); 692 break; 693 case IFT_BRIDGE: 694 xo_emit(" [{:type/bridge}]"); 695 break; 696 case IFT_INFINIBAND: 697 xo_emit(" [{:type/infiniband}]"); 698 break; 699 default: 700 break; 701 } 702 703 xo_emit("\n"); 704 705 xo_close_instance("arp-cache"); 706 } 707 708 static int 709 print_entries(uint32_t ifindex, struct in_addr addr) 710 { 711 #ifndef WITHOUT_NETLINK 712 return (print_entries_nl(ifindex, addr)); 713 #else 714 return (search(addr.s_addr, print_entry)); 715 #endif 716 } 717 718 719 /* 720 * Nuke an arp entry 721 */ 722 static void 723 nuke_entry(struct sockaddr_dl *sdl __unused, 724 struct sockaddr_in *addr, struct rt_msghdr *rtm) 725 { 726 char ip[20]; 727 728 if (rtm->rtm_flags & RTF_PINNED) 729 return; 730 731 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 732 delete(ip); 733 } 734 735 static void 736 nuke_entries(uint32_t ifindex, struct in_addr addr) 737 { 738 search(addr.s_addr, nuke_entry); 739 } 740 741 static void 742 usage(void) 743 { 744 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 745 "usage: arp [-n] [-i interface] hostname", 746 " arp [-n] [-i interface] -a", 747 " arp -d hostname [pub]", 748 " arp -d [-i interface] -a", 749 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 750 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 751 " arp -f filename"); 752 exit(1); 753 } 754 755 static struct rt_msghdr * 756 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) 757 { 758 static int seq; 759 int rlen; 760 int l; 761 static int s = -1; 762 static pid_t pid; 763 764 static struct { 765 struct rt_msghdr m_rtm; 766 char m_space[512]; 767 } m_rtmsg; 768 769 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 770 char *cp = m_rtmsg.m_space; 771 772 if (s < 0) { /* first time: open socket, get pid */ 773 s = socket(PF_ROUTE, SOCK_RAW, 0); 774 if (s < 0) 775 xo_err(1, "socket"); 776 pid = getpid(); 777 } 778 779 errno = 0; 780 /* 781 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 782 * appropriately. 783 */ 784 if (cmd == RTM_DELETE) 785 goto doit; 786 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 787 rtm->rtm_flags = opts.flags; 788 rtm->rtm_version = RTM_VERSION; 789 790 switch (cmd) { 791 default: 792 xo_errx(1, "internal wrong cmd"); 793 case RTM_ADD: 794 rtm->rtm_addrs |= RTA_GATEWAY; 795 if (opts.expire_time != 0) { 796 struct timespec tp; 797 798 clock_gettime(CLOCK_MONOTONIC, &tp); 799 rtm->rtm_rmx.rmx_expire = opts.expire_time + tp.tv_sec; 800 } 801 rtm->rtm_inits = RTV_EXPIRE; 802 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 803 /* FALLTHROUGH */ 804 case RTM_GET: 805 rtm->rtm_addrs |= RTA_DST; 806 } 807 #define NEXTADDR(w, s) \ 808 do { \ 809 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 810 bcopy((s), cp, sizeof(*(s))); \ 811 cp += SA_SIZE(s); \ 812 } \ 813 } while (0) 814 815 NEXTADDR(RTA_DST, dst); 816 NEXTADDR(RTA_GATEWAY, sdl); 817 818 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 819 doit: 820 l = rtm->rtm_msglen; 821 rtm->rtm_seq = ++seq; 822 rtm->rtm_type = cmd; 823 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 824 if (errno != ESRCH || cmd != RTM_DELETE) { 825 xo_warn("writing to routing socket"); 826 return (NULL); 827 } 828 } 829 do { 830 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 831 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq || 832 rtm->rtm_pid != pid)); 833 if (l < 0) 834 xo_warn("read from routing socket"); 835 return (rtm); 836 } 837 838 /* 839 * get_ether_addr - get the hardware address of an interface on the 840 * the same subnet as ipaddr. 841 */ 842 static int 843 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 844 { 845 struct ifaddrs *ifa, *ifd, *ifas = NULL; 846 in_addr_t ina, mask; 847 struct sockaddr_dl *dla; 848 int retval = 0; 849 850 /* 851 * Scan through looking for an interface with an Internet 852 * address on the same subnet as `ipaddr'. 853 */ 854 if (getifaddrs(&ifas) < 0) { 855 xo_warnx("getifaddrs"); 856 goto done; 857 } 858 859 for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) { 860 if (ifa->ifa_addr == NULL || ifa->ifa_netmask == NULL) 861 continue; 862 if (ifa->ifa_addr->sa_family != AF_INET) 863 continue; 864 /* 865 * Check that the interface is up, 866 * and not point-to-point or loopback. 867 */ 868 if ((ifa->ifa_flags & 869 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 870 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST)) 871 continue; 872 /* Get its netmask and check that it's on the right subnet. */ 873 mask = ((struct sockaddr_in *) 874 ifa->ifa_netmask)->sin_addr.s_addr; 875 ina = ((struct sockaddr_in *) 876 ifa->ifa_addr)->sin_addr.s_addr; 877 if ((ipaddr & mask) == (ina & mask)) 878 break; /* ok, we got it! */ 879 } 880 if (ifa == NULL) 881 goto done; 882 883 /* 884 * Now scan through again looking for a link-level address 885 * for this interface. 886 */ 887 for (ifd = ifas; ifd != NULL; ifd = ifd->ifa_next) { 888 if (ifd->ifa_addr == NULL) 889 continue; 890 if (strcmp(ifa->ifa_name, ifd->ifa_name) == 0 && 891 ifd->ifa_addr->sa_family == AF_LINK) 892 break; 893 } 894 if (ifd == NULL) 895 goto done; 896 /* 897 * Found the link-level address - copy it out 898 */ 899 dla = (struct sockaddr_dl *)ifd->ifa_addr; 900 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 901 printf("using interface %s for proxy with address %s\n", ifa->ifa_name, 902 ether_ntoa(hwaddr)); 903 retval = dla->sdl_alen; 904 done: 905 if (ifas != NULL) 906 freeifaddrs(ifas); 907 return (retval); 908 } 909