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 /* 48 * arp - display, set, and delete arp table entries 49 */ 50 51 #include <sys/param.h> 52 #include <sys/file.h> 53 #include <sys/socket.h> 54 #include <sys/sockio.h> 55 #include <sys/sysctl.h> 56 #include <sys/ioctl.h> 57 #include <sys/time.h> 58 59 #include <net/if.h> 60 #include <net/if_dl.h> 61 #include <net/if_types.h> 62 #include <net/route.h> 63 64 #include <netinet/in.h> 65 #include <netinet/if_ether.h> 66 67 #include <arpa/inet.h> 68 69 #include <ctype.h> 70 #include <err.h> 71 #include <errno.h> 72 #include <netdb.h> 73 #include <nlist.h> 74 #include <paths.h> 75 #include <stdbool.h> 76 #include <stdio.h> 77 #include <stdlib.h> 78 #include <string.h> 79 #include <strings.h> 80 #include <unistd.h> 81 #include <ifaddrs.h> 82 #include <libxo/xo.h> 83 #include "arp.h" 84 85 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in, 86 struct rt_msghdr *rtm); 87 static void nuke_entries(uint32_t ifindex, struct in_addr addr); 88 static int print_entries(uint32_t ifindex, struct in_addr addr); 89 90 static int delete(char *host); 91 static void usage(void) __dead2; 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 int set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, 99 char *host); 100 101 static char *rifname; 102 103 struct if_nameindex *ifnameindex; 104 105 struct arp_opts opts = {}; 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 #define ARP_XO_VERSION "1" 117 118 int 119 main(int argc, char *argv[]) 120 { 121 int ch, func = 0; 122 int rtn = 0; 123 124 argc = xo_parse_args(argc, argv); 125 if (argc < 0) 126 exit(1); 127 128 while ((ch = getopt(argc, argv, "andfsSi:")) != -1) 129 switch(ch) { 130 case 'a': 131 opts.aflag = true; 132 break; 133 case 'd': 134 SETFUNC(F_DELETE); 135 break; 136 case 'n': 137 opts.nflag = true; 138 break; 139 case 'S': 140 SETFUNC(F_REPLACE); 141 break; 142 case 's': 143 SETFUNC(F_SET); 144 break; 145 case 'f' : 146 SETFUNC(F_FILESET); 147 break; 148 case 'i': 149 rifname = optarg; 150 break; 151 case '?': 152 default: 153 usage(); 154 } 155 argc -= optind; 156 argv += optind; 157 158 if (!func) 159 func = F_GET; 160 if (rifname) { 161 if (func != F_GET && !(func == F_DELETE && opts.aflag)) 162 xo_errx(1, "-i not applicable to this operation"); 163 if (if_nametoindex(rifname) == 0) { 164 if (errno == ENXIO) 165 xo_errx(1, "interface %s does not exist", 166 rifname); 167 else 168 xo_err(1, "if_nametoindex(%s)", rifname); 169 } 170 } 171 switch (func) { 172 case F_GET: 173 if (opts.aflag) { 174 if (argc != 0) 175 usage(); 176 177 xo_set_version(ARP_XO_VERSION); 178 xo_open_container("arp"); 179 xo_open_list("arp-cache"); 180 181 struct in_addr all_addrs = {}; 182 print_entries(0, all_addrs); 183 184 xo_close_list("arp-cache"); 185 xo_close_container("arp"); 186 xo_finish(); 187 } else { 188 if (argc != 1) 189 usage(); 190 rtn = get(argv[0]); 191 } 192 break; 193 case F_SET: 194 case F_REPLACE: 195 if (argc < 2 || argc > 6) 196 usage(); 197 if (func == F_REPLACE) 198 (void)delete(argv[0]); 199 rtn = set(argc, argv) ? 1 : 0; 200 break; 201 case F_DELETE: 202 if (opts.aflag) { 203 if (argc != 0) 204 usage(); 205 struct in_addr all_addrs = {}; 206 nuke_entries(0, all_addrs); 207 } else { 208 if (argc != 1) 209 usage(); 210 rtn = delete(argv[0]); 211 } 212 break; 213 case F_FILESET: 214 if (argc != 1) 215 usage(); 216 rtn = file(argv[0]); 217 break; 218 } 219 220 if (ifnameindex != NULL) 221 if_freenameindex(ifnameindex); 222 223 return (rtn); 224 } 225 226 /* 227 * Process a file to set standard arp entries 228 */ 229 static int 230 file(char *name) 231 { 232 FILE *fp; 233 int i, retval; 234 char line[100], arg[5][50], *args[5], *p; 235 236 if ((fp = fopen(name, "r")) == NULL) 237 xo_err(1, "cannot open %s", name); 238 args[0] = &arg[0][0]; 239 args[1] = &arg[1][0]; 240 args[2] = &arg[2][0]; 241 args[3] = &arg[3][0]; 242 args[4] = &arg[4][0]; 243 retval = 0; 244 while(fgets(line, sizeof(line), fp) != NULL) { 245 if ((p = strchr(line, '#')) != NULL) 246 *p = '\0'; 247 for (p = line; isblank(*p); p++); 248 if (*p == '\n' || *p == '\0') 249 continue; 250 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 251 arg[2], arg[3], arg[4]); 252 if (i < 2) { 253 xo_warnx("bad line: %s", line); 254 retval = 1; 255 continue; 256 } 257 if (set(i, args)) 258 retval = 1; 259 } 260 fclose(fp); 261 return (retval); 262 } 263 264 /* 265 * Given a hostname, fills up a (static) struct sockaddr_in with 266 * the address of the host and returns a pointer to the 267 * structure. 268 */ 269 struct sockaddr_in * 270 getaddr(char *host) 271 { 272 struct hostent *hp; 273 static struct sockaddr_in reply; 274 275 bzero(&reply, sizeof(reply)); 276 reply.sin_len = sizeof(reply); 277 reply.sin_family = AF_INET; 278 reply.sin_addr.s_addr = inet_addr(host); 279 if (reply.sin_addr.s_addr == INADDR_NONE) { 280 if (!(hp = gethostbyname(host))) { 281 xo_warnx("%s: %s", host, hstrerror(h_errno)); 282 return (NULL); 283 } 284 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 285 sizeof reply.sin_addr); 286 } 287 return (&reply); 288 } 289 290 int valid_type(int type); 291 /* 292 * Returns true if the type is a valid one for ARP. 293 */ 294 int 295 valid_type(int type) 296 { 297 298 switch (type) { 299 case IFT_ETHER: 300 case IFT_FDDI: 301 case IFT_IEEE1394: 302 case IFT_INFINIBAND: 303 case IFT_ISO88023: 304 case IFT_ISO88024: 305 case IFT_L2VLAN: 306 case IFT_BRIDGE: 307 return (1); 308 default: 309 return (0); 310 } 311 } 312 313 /* 314 * Set an individual arp entry 315 */ 316 static int 317 set(int argc, char **argv) 318 { 319 struct sockaddr_in *dst; /* what are we looking for */ 320 struct ether_addr *ea; 321 char *host = argv[0], *eaddr = argv[1]; 322 struct sockaddr_dl sdl_m; 323 324 argc -= 2; 325 argv += 2; 326 327 bzero(&sdl_m, sizeof(sdl_m)); 328 sdl_m.sdl_len = sizeof(sdl_m); 329 sdl_m.sdl_family = AF_LINK; 330 331 dst = getaddr(host); 332 if (dst == NULL) 333 return (1); 334 while (argc-- > 0) { 335 if (strcmp(argv[0], "temp") == 0) { 336 int max_age; 337 size_t len = sizeof(max_age); 338 339 if (sysctlbyname("net.link.ether.inet.max_age", 340 &max_age, &len, NULL, 0) != 0) 341 xo_err(1, "sysctlbyname"); 342 opts.expire_time = max_age; 343 } else if (strcmp(argv[0], "pub") == 0) { 344 opts.flags |= RTF_ANNOUNCE; 345 if (argc && strcmp(argv[1], "only") == 0) { 346 /* 347 * Compatibility: in pre FreeBSD 8 times 348 * the "only" keyword used to mean that 349 * an ARP entry should be announced, but 350 * not installed into routing table. 351 */ 352 argc--; argv++; 353 } 354 } else if (strcmp(argv[0], "blackhole") == 0) { 355 if (opts.flags & RTF_REJECT) { 356 xo_errx(1, "Choose one of blackhole or reject, " 357 "not both."); 358 } 359 opts.flags |= RTF_BLACKHOLE; 360 } else if (strcmp(argv[0], "reject") == 0) { 361 if (opts.flags & RTF_BLACKHOLE) { 362 xo_errx(1, "Choose one of blackhole or reject, " 363 "not both."); 364 } 365 opts.flags |= RTF_REJECT; 366 } else { 367 xo_warnx("Invalid parameter '%s'", argv[0]); 368 usage(); 369 } 370 argv++; 371 } 372 ea = (struct ether_addr *)LLADDR(&sdl_m); 373 if ((opts.flags & RTF_ANNOUNCE) && !strcmp(eaddr, "auto")) { 374 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 375 xo_warnx("no interface found for %s", 376 inet_ntoa(dst->sin_addr)); 377 return (1); 378 } 379 sdl_m.sdl_alen = ETHER_ADDR_LEN; 380 } else { 381 struct ether_addr *ea1 = ether_aton(eaddr); 382 383 if (ea1 == NULL) { 384 xo_warnx("invalid Ethernet address '%s'", eaddr); 385 return (1); 386 } else { 387 *ea = *ea1; 388 sdl_m.sdl_alen = ETHER_ADDR_LEN; 389 } 390 } 391 #ifndef WITHOUT_NETLINK 392 return (set_nl(0, dst, &sdl_m, host)); 393 #else 394 return (set_rtsock(dst, &sdl_m, host)); 395 #endif 396 } 397 398 #ifdef WITHOUT_NETLINK 399 static int 400 set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, char *host) 401 { 402 struct sockaddr_in *addr; 403 struct sockaddr_dl *sdl; 404 struct rt_msghdr *rtm; 405 406 /* 407 * In the case a proxy-arp entry is being added for 408 * a remote end point, the RTF_ANNOUNCE flag in the 409 * RTM_GET command is an indication to the kernel 410 * routing code that the interface associated with 411 * the prefix route covering the local end of the 412 * PPP link should be returned, on which ARP applies. 413 */ 414 rtm = rtmsg(RTM_GET, dst, NULL); 415 if (rtm == NULL) { 416 xo_warn("%s", host); 417 return (1); 418 } 419 addr = (struct sockaddr_in *)(rtm + 1); 420 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 421 422 if ((sdl->sdl_family != AF_LINK) || 423 (rtm->rtm_flags & RTF_GATEWAY) || 424 !valid_type(sdl->sdl_type)) { 425 xo_warnx("cannot intuit interface index and type for %s", host); 426 return (1); 427 } 428 sdl_m->sdl_type = sdl->sdl_type; 429 sdl_m->sdl_index = sdl->sdl_index; 430 return (rtmsg(RTM_ADD, dst, sdl_m) == NULL); 431 } 432 #endif 433 434 /* 435 * Display an individual arp entry 436 */ 437 static int 438 get(char *host) 439 { 440 struct sockaddr_in *addr; 441 int found; 442 443 addr = getaddr(host); 444 if (addr == NULL) 445 return (1); 446 447 xo_set_version(ARP_XO_VERSION); 448 xo_open_container("arp"); 449 xo_open_list("arp-cache"); 450 451 found = print_entries(0, addr->sin_addr); 452 453 if (found == 0) { 454 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry", 455 host, inet_ntoa(addr->sin_addr)); 456 if (rifname) 457 xo_emit(" on {d:interface/%s}", rifname); 458 xo_emit("\n"); 459 } 460 461 xo_close_list("arp-cache"); 462 xo_close_container("arp"); 463 xo_finish(); 464 465 return (found == 0); 466 } 467 468 /* 469 * Delete an arp entry 470 */ 471 #ifdef WITHOUT_NETLINK 472 static int 473 delete_rtsock(char *host) 474 { 475 struct sockaddr_in *addr, *dst; 476 struct rt_msghdr *rtm; 477 struct sockaddr_dl *sdl; 478 479 dst = getaddr(host); 480 if (dst == NULL) 481 return (1); 482 483 /* 484 * Perform a regular entry delete first. 485 */ 486 opts.flags &= ~RTF_ANNOUNCE; 487 488 for (;;) { /* try twice */ 489 rtm = rtmsg(RTM_GET, dst, NULL); 490 if (rtm == NULL) { 491 xo_warn("%s", host); 492 return (1); 493 } 494 addr = (struct sockaddr_in *)(rtm + 1); 495 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 496 497 /* 498 * With the new L2/L3 restructure, the route 499 * returned is a prefix route. The important 500 * piece of information from the previous 501 * RTM_GET is the interface index. In the 502 * case of ECMP, the kernel will traverse 503 * the route group for the given entry. 504 */ 505 if (sdl->sdl_family == AF_LINK && 506 !(rtm->rtm_flags & RTF_GATEWAY) && 507 valid_type(sdl->sdl_type) ) { 508 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 509 break; 510 } 511 512 /* 513 * Regular entry delete failed, now check if there 514 * is a proxy-arp entry to remove. 515 */ 516 if (opts.flags & RTF_ANNOUNCE) { 517 xo_warnx("delete: cannot locate %s", host); 518 return (1); 519 } 520 521 opts.flags |= RTF_ANNOUNCE; 522 } 523 rtm->rtm_flags |= RTF_LLDATA; 524 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 525 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 526 return (0); 527 } 528 return (1); 529 } 530 #endif 531 532 static int 533 delete(char *host) 534 { 535 #ifdef WITHOUT_NETLINK 536 return (delete_rtsock(host)); 537 #else 538 return (delete_nl(0, host)); 539 #endif 540 } 541 542 543 /* 544 * Search the arp table and do some action on matching entries 545 */ 546 static int 547 search(u_long addr, action_fn *action) 548 { 549 int mib[6]; 550 size_t needed; 551 char *lim, *buf, *next; 552 struct rt_msghdr *rtm; 553 struct sockaddr_in *sin2; 554 struct sockaddr_dl *sdl; 555 char ifname[IF_NAMESIZE]; 556 int st, found_entry = 0; 557 558 mib[0] = CTL_NET; 559 mib[1] = PF_ROUTE; 560 mib[2] = 0; 561 mib[3] = AF_INET; 562 mib[4] = NET_RT_FLAGS; 563 #ifdef RTF_LLINFO 564 mib[5] = RTF_LLINFO; 565 #else 566 mib[5] = 0; 567 #endif 568 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 569 xo_err(1, "route-sysctl-estimate"); 570 if (needed == 0) /* empty table */ 571 return 0; 572 buf = NULL; 573 for (;;) { 574 buf = reallocf(buf, needed); 575 if (buf == NULL) 576 xo_errx(1, "could not reallocate memory"); 577 st = sysctl(mib, 6, buf, &needed, NULL, 0); 578 if (st == 0 || errno != ENOMEM) 579 break; 580 needed += needed / 8; 581 } 582 if (st == -1) 583 xo_err(1, "actual retrieval of routing table"); 584 lim = buf + needed; 585 for (next = buf; next < lim; next += rtm->rtm_msglen) { 586 rtm = (struct rt_msghdr *)next; 587 sin2 = (struct sockaddr_in *)(rtm + 1); 588 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 589 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 590 strcmp(ifname, rifname)) 591 continue; 592 if (addr) { 593 if (addr != sin2->sin_addr.s_addr) 594 continue; 595 found_entry = 1; 596 } 597 (*action)(sdl, sin2, rtm); 598 } 599 free(buf); 600 return (found_entry); 601 } 602 603 /* 604 * Display an arp entry 605 */ 606 607 static void 608 print_entry(struct sockaddr_dl *sdl, 609 struct sockaddr_in *addr, struct rt_msghdr *rtm) 610 { 611 const char *host; 612 struct hostent *hp; 613 struct if_nameindex *p; 614 615 if (ifnameindex == NULL) 616 if ((ifnameindex = if_nameindex()) == NULL) 617 xo_err(1, "cannot retrieve interface names"); 618 619 xo_open_instance("arp-cache"); 620 621 if (!opts.nflag) 622 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 623 sizeof addr->sin_addr, AF_INET); 624 else 625 hp = 0; 626 if (hp) 627 host = hp->h_name; 628 else { 629 host = "?"; 630 if (h_errno == TRY_AGAIN) 631 opts.nflag = true; 632 } 633 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host, 634 inet_ntoa(addr->sin_addr)); 635 if (sdl->sdl_alen) { 636 if ((sdl->sdl_type == IFT_ETHER || 637 sdl->sdl_type == IFT_L2VLAN || 638 sdl->sdl_type == IFT_BRIDGE) && 639 sdl->sdl_alen == ETHER_ADDR_LEN) 640 xo_emit("{:mac-address/%s}", 641 ether_ntoa((struct ether_addr *)LLADDR(sdl))); 642 else { 643 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 644 645 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n); 646 } 647 } else 648 xo_emit("{d:/(incomplete)}{en:incomplete/true}"); 649 650 for (p = ifnameindex; p && p->if_index && p->if_name; p++) { 651 if (p->if_index == sdl->sdl_index) { 652 xo_emit(" on {:interface/%s}", p->if_name); 653 break; 654 } 655 } 656 657 if (rtm->rtm_rmx.rmx_expire == 0) 658 xo_emit("{d:/ permanent}{en:permanent/true}"); 659 else { 660 static struct timespec tp; 661 time_t expire_time = 0; 662 663 if (tp.tv_sec == 0) 664 clock_gettime(CLOCK_MONOTONIC, &tp); 665 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 666 xo_emit(" expires in {:expires/%d} seconds", 667 (int)expire_time); 668 else 669 xo_emit("{d:/ expired}{en:expired/true}"); 670 } 671 672 if (rtm->rtm_flags & RTF_ANNOUNCE) 673 xo_emit("{d:/ published}{en:published/true}"); 674 675 switch(sdl->sdl_type) { 676 case IFT_ETHER: 677 xo_emit(" [{:type/ethernet}]"); 678 break; 679 case IFT_FDDI: 680 xo_emit(" [{:type/fddi}]"); 681 break; 682 case IFT_ATM: 683 xo_emit(" [{:type/atm}]"); 684 break; 685 case IFT_L2VLAN: 686 xo_emit(" [{:type/vlan}]"); 687 break; 688 case IFT_IEEE1394: 689 xo_emit(" [{:type/firewire}]"); 690 break; 691 case IFT_BRIDGE: 692 xo_emit(" [{:type/bridge}]"); 693 break; 694 case IFT_INFINIBAND: 695 xo_emit(" [{:type/infiniband}]"); 696 break; 697 default: 698 break; 699 } 700 701 xo_emit("\n"); 702 703 xo_close_instance("arp-cache"); 704 } 705 706 static int 707 print_entries(uint32_t ifindex, struct in_addr addr) 708 { 709 #ifndef WITHOUT_NETLINK 710 return (print_entries_nl(ifindex, addr)); 711 #else 712 return (search(addr.s_addr, print_entry)); 713 #endif 714 } 715 716 717 /* 718 * Nuke an arp entry 719 */ 720 static void 721 nuke_entry(struct sockaddr_dl *sdl __unused, 722 struct sockaddr_in *addr, struct rt_msghdr *rtm) 723 { 724 char ip[20]; 725 726 if (rtm->rtm_flags & RTF_PINNED) 727 return; 728 729 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 730 delete(ip); 731 } 732 733 static void 734 nuke_entries(uint32_t ifindex, struct in_addr addr) 735 { 736 search(addr.s_addr, nuke_entry); 737 } 738 739 static void 740 usage(void) 741 { 742 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 743 "usage: arp [-n] [-i interface] hostname", 744 " arp [-n] [-i interface] -a", 745 " arp -d hostname [pub]", 746 " arp -d [-i interface] -a", 747 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 748 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 749 " arp -f filename"); 750 exit(1); 751 } 752 753 static struct rt_msghdr * 754 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) 755 { 756 static int seq; 757 int rlen; 758 int l; 759 static int s = -1; 760 static pid_t pid; 761 762 static struct { 763 struct rt_msghdr m_rtm; 764 char m_space[512]; 765 } m_rtmsg; 766 767 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 768 char *cp = m_rtmsg.m_space; 769 770 if (s < 0) { /* first time: open socket, get pid */ 771 s = socket(PF_ROUTE, SOCK_RAW, 0); 772 if (s < 0) 773 xo_err(1, "socket"); 774 pid = getpid(); 775 } 776 777 errno = 0; 778 /* 779 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 780 * appropriately. 781 */ 782 if (cmd == RTM_DELETE) 783 goto doit; 784 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 785 rtm->rtm_flags = opts.flags; 786 rtm->rtm_version = RTM_VERSION; 787 788 switch (cmd) { 789 default: 790 xo_errx(1, "internal wrong cmd"); 791 case RTM_ADD: 792 rtm->rtm_addrs |= RTA_GATEWAY; 793 if (opts.expire_time != 0) { 794 struct timespec tp; 795 796 clock_gettime(CLOCK_MONOTONIC, &tp); 797 rtm->rtm_rmx.rmx_expire = opts.expire_time + tp.tv_sec; 798 } 799 rtm->rtm_inits = RTV_EXPIRE; 800 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 801 /* FALLTHROUGH */ 802 case RTM_GET: 803 rtm->rtm_addrs |= RTA_DST; 804 } 805 #define NEXTADDR(w, s) \ 806 do { \ 807 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 808 bcopy((s), cp, sizeof(*(s))); \ 809 cp += SA_SIZE(s); \ 810 } \ 811 } while (0) 812 813 NEXTADDR(RTA_DST, dst); 814 NEXTADDR(RTA_GATEWAY, sdl); 815 816 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 817 doit: 818 l = rtm->rtm_msglen; 819 rtm->rtm_seq = ++seq; 820 rtm->rtm_type = cmd; 821 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 822 if (errno != ESRCH || cmd != RTM_DELETE) { 823 xo_warn("writing to routing socket"); 824 return (NULL); 825 } 826 } 827 do { 828 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 829 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq || 830 rtm->rtm_pid != pid)); 831 if (l < 0) 832 xo_warn("read from routing socket"); 833 return (rtm); 834 } 835 836 /* 837 * get_ether_addr - get the hardware address of an interface on the 838 * the same subnet as ipaddr. 839 */ 840 static int 841 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 842 { 843 struct ifaddrs *ifa, *ifd, *ifas = NULL; 844 in_addr_t ina, mask; 845 struct sockaddr_dl *dla; 846 int retval = 0; 847 848 /* 849 * Scan through looking for an interface with an Internet 850 * address on the same subnet as `ipaddr'. 851 */ 852 if (getifaddrs(&ifas) < 0) { 853 xo_warnx("getifaddrs"); 854 goto done; 855 } 856 857 for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) { 858 if (ifa->ifa_addr == NULL || ifa->ifa_netmask == NULL) 859 continue; 860 if (ifa->ifa_addr->sa_family != AF_INET) 861 continue; 862 /* 863 * Check that the interface is up, 864 * and not point-to-point or loopback. 865 */ 866 if ((ifa->ifa_flags & 867 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 868 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST)) 869 continue; 870 /* Get its netmask and check that it's on the right subnet. */ 871 mask = ((struct sockaddr_in *) 872 ifa->ifa_netmask)->sin_addr.s_addr; 873 ina = ((struct sockaddr_in *) 874 ifa->ifa_addr)->sin_addr.s_addr; 875 if ((ipaddr & mask) == (ina & mask)) 876 break; /* ok, we got it! */ 877 } 878 if (ifa == NULL) 879 goto done; 880 881 /* 882 * Now scan through again looking for a link-level address 883 * for this interface. 884 */ 885 for (ifd = ifas; ifd != NULL; ifd = ifd->ifa_next) { 886 if (ifd->ifa_addr == NULL) 887 continue; 888 if (strcmp(ifa->ifa_name, ifd->ifa_name) == 0 && 889 ifd->ifa_addr->sa_family == AF_LINK) 890 break; 891 } 892 if (ifd == NULL) 893 goto done; 894 /* 895 * Found the link-level address - copy it out 896 */ 897 dla = (struct sockaddr_dl *)ifd->ifa_addr; 898 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 899 printf("using interface %s for proxy with address %s\n", ifa->ifa_name, 900 ether_ntoa(hwaddr)); 901 retval = dla->sdl_alen; 902 done: 903 if (ifas != NULL) 904 freeifaddrs(ifas); 905 return (retval); 906 } 907