arp.c revision 225736
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 35static 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 41static 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: stable/9/usr.sbin/arp/arp.c 216078 2010-11-30 16:14:19Z glebius $"); 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 83typedef void (action_fn)(struct sockaddr_dl *sdl, 84 struct sockaddr_inarp *s_in, struct rt_msghdr *rtm); 85 86static int search(u_long addr, action_fn *action); 87static action_fn print_entry; 88static action_fn nuke_entry; 89 90static int delete(char *host, int do_proxy); 91static void usage(void); 92static int set(int argc, char **argv); 93static int get(char *host); 94static int file(char *name); 95static struct rt_msghdr *rtmsg(int cmd, 96 struct sockaddr_inarp *dst, struct sockaddr_dl *sdl); 97static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); 98static struct sockaddr_inarp *getaddr(char *host); 99static int valid_type(int type); 100 101static int nflag; /* no reverse dns lookups */ 102static char *rifname; 103 104static time_t expire_time; 105static int flags, doing_proxy, proxy_only; 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 116int 117main(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], 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 if (argc == 2 && strncmp(argv[1], "pub", 3) == 0) 192 ch = SIN_PROXY; 193 else if (argc == 1) 194 ch = 0; 195 else 196 usage(); 197 rtn = delete(argv[0], ch); 198 } 199 break; 200 case F_FILESET: 201 if (argc != 1) 202 usage(); 203 rtn = file(argv[0]); 204 break; 205 } 206 207 return (rtn); 208} 209 210/* 211 * Process a file to set standard arp entries 212 */ 213static int 214file(char *name) 215{ 216 FILE *fp; 217 int i, retval; 218 char line[100], arg[5][50], *args[5], *p; 219 220 if ((fp = fopen(name, "r")) == NULL) 221 err(1, "cannot open %s", name); 222 args[0] = &arg[0][0]; 223 args[1] = &arg[1][0]; 224 args[2] = &arg[2][0]; 225 args[3] = &arg[3][0]; 226 args[4] = &arg[4][0]; 227 retval = 0; 228 while(fgets(line, sizeof(line), fp) != NULL) { 229 if ((p = strchr(line, '#')) != NULL) 230 *p = '\0'; 231 for (p = line; isblank(*p); p++); 232 if (*p == '\n' || *p == '\0') 233 continue; 234 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], 235 arg[2], arg[3], arg[4]); 236 if (i < 2) { 237 warnx("bad line: %s", line); 238 retval = 1; 239 continue; 240 } 241 if (set(i, args)) 242 retval = 1; 243 } 244 fclose(fp); 245 return (retval); 246} 247 248/* 249 * Given a hostname, fills up a (static) struct sockaddr_inarp with 250 * the address of the host and returns a pointer to the 251 * structure. 252 */ 253static struct sockaddr_inarp * 254getaddr(char *host) 255{ 256 struct hostent *hp; 257 static struct sockaddr_inarp reply; 258 259 bzero(&reply, sizeof(reply)); 260 reply.sin_len = sizeof(reply); 261 reply.sin_family = AF_INET; 262 reply.sin_addr.s_addr = inet_addr(host); 263 if (reply.sin_addr.s_addr == INADDR_NONE) { 264 if (!(hp = gethostbyname(host))) { 265 warnx("%s: %s", host, hstrerror(h_errno)); 266 return (NULL); 267 } 268 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, 269 sizeof reply.sin_addr); 270 } 271 return (&reply); 272} 273 274/* 275 * Returns true if the type is a valid one for ARP. 276 */ 277static int 278valid_type(int type) 279{ 280 281 switch (type) { 282 case IFT_ETHER: 283 case IFT_FDDI: 284 case IFT_ISO88023: 285 case IFT_ISO88024: 286 case IFT_ISO88025: 287 case IFT_L2VLAN: 288 case IFT_BRIDGE: 289 return (1); 290 default: 291 return (0); 292 } 293} 294 295/* 296 * Set an individual arp entry 297 */ 298static int 299set(int argc, char **argv) 300{ 301 struct sockaddr_inarp *addr; 302 struct sockaddr_inarp *dst; /* what are we looking for */ 303 struct sockaddr_dl *sdl; 304 struct rt_msghdr *rtm; 305 struct ether_addr *ea; 306 char *host = argv[0], *eaddr = argv[1]; 307 struct sockaddr_dl sdl_m; 308 309 argc -= 2; 310 argv += 2; 311 312 bzero(&sdl_m, sizeof(sdl_m)); 313 sdl_m.sdl_len = sizeof(sdl_m); 314 sdl_m.sdl_family = AF_LINK; 315 316 dst = getaddr(host); 317 if (dst == NULL) 318 return (1); 319 doing_proxy = flags = proxy_only = expire_time = 0; 320 while (argc-- > 0) { 321 if (strncmp(argv[0], "temp", 4) == 0) { 322 struct timespec tp; 323 int max_age; 324 size_t len = sizeof(max_age); 325 326 clock_gettime(CLOCK_MONOTONIC, &tp); 327 if (sysctlbyname("net.link.ether.inet.max_age", 328 &max_age, &len, NULL, 0) != 0) 329 err(1, "sysctlbyname"); 330 expire_time = tp.tv_sec + max_age; 331 } else if (strncmp(argv[0], "pub", 3) == 0) { 332 flags |= RTF_ANNOUNCE; 333 doing_proxy = 1; 334 if (argc && strncmp(argv[1], "only", 3) == 0) { 335 proxy_only = 1; 336 argc--; argv++; 337 } 338 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 339 if (flags & RTF_REJECT) { 340 printf("Choose one of blackhole or reject, not both.\n"); 341 } 342 flags |= RTF_BLACKHOLE; 343 } else if (strncmp(argv[0], "reject", 6) == 0) { 344 if (flags & RTF_BLACKHOLE) { 345 printf("Choose one of blackhole or reject, not both.\n"); 346 } 347 flags |= RTF_REJECT; 348 } else if (strncmp(argv[0], "trail", 5) == 0) { 349 /* XXX deprecated and undocumented feature */ 350 printf("%s: Sending trailers is no longer supported\n", 351 host); 352 } 353 argv++; 354 } 355 ea = (struct ether_addr *)LLADDR(&sdl_m); 356 if (doing_proxy && !strcmp(eaddr, "auto")) { 357 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 358 printf("no interface found for %s\n", 359 inet_ntoa(dst->sin_addr)); 360 return (1); 361 } 362 sdl_m.sdl_alen = ETHER_ADDR_LEN; 363 } else { 364 struct ether_addr *ea1 = ether_aton(eaddr); 365 366 if (ea1 == NULL) { 367 warnx("invalid Ethernet address '%s'", eaddr); 368 return (1); 369 } else { 370 *ea = *ea1; 371 sdl_m.sdl_alen = ETHER_ADDR_LEN; 372 } 373 } 374 375 /* 376 * In the case a proxy-arp entry is being added for 377 * a remote end point, the RTF_ANNOUNCE flag in the 378 * RTM_GET command is an indication to the kernel 379 * routing code that the interface associated with 380 * the prefix route covering the local end of the 381 * PPP link should be returned, on which ARP applies. 382 */ 383 rtm = rtmsg(RTM_GET, dst, &sdl_m); 384 if (rtm == NULL) { 385 warn("%s", host); 386 return (1); 387 } 388 addr = (struct sockaddr_inarp *)(rtm + 1); 389 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 390 if (addr->sin_addr.s_addr == dst->sin_addr.s_addr) { 391 printf("set: proxy entry exists for non 802 device\n"); 392 return (1); 393 } 394 395 if ((sdl->sdl_family != AF_LINK) || 396 (rtm->rtm_flags & RTF_GATEWAY) || 397 !valid_type(sdl->sdl_type)) { 398 printf("cannot intuit interface index and type for %s\n", host); 399 return (1); 400 } 401 sdl_m.sdl_type = sdl->sdl_type; 402 sdl_m.sdl_index = sdl->sdl_index; 403 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 404} 405 406/* 407 * Display an individual arp entry 408 */ 409static int 410get(char *host) 411{ 412 struct sockaddr_inarp *addr; 413 414 addr = getaddr(host); 415 if (addr == NULL) 416 return (1); 417 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 418 printf("%s (%s) -- no entry", 419 host, inet_ntoa(addr->sin_addr)); 420 if (rifname) 421 printf(" on %s", rifname); 422 printf("\n"); 423 return (1); 424 } 425 return (0); 426} 427 428/* 429 * Delete an arp entry 430 */ 431static int 432delete(char *host, int do_proxy) 433{ 434 struct sockaddr_inarp *addr, *dst; 435 struct rt_msghdr *rtm; 436 struct sockaddr_dl *sdl; 437 struct sockaddr_dl sdl_m; 438 439 dst = getaddr(host); 440 if (dst == NULL) 441 return (1); 442 443 /* 444 * Perform a regular entry delete first. 445 */ 446 flags &= ~RTF_ANNOUNCE; 447 448 /* 449 * setup the data structure to notify the kernel 450 * it is the ARP entry the RTM_GET is interested 451 * in 452 */ 453 bzero(&sdl_m, sizeof(sdl_m)); 454 sdl_m.sdl_len = sizeof(sdl_m); 455 sdl_m.sdl_family = AF_LINK; 456 457 for (;;) { /* try twice */ 458 rtm = rtmsg(RTM_GET, dst, &sdl_m); 459 if (rtm == NULL) { 460 warn("%s", host); 461 return (1); 462 } 463 addr = (struct sockaddr_inarp *)(rtm + 1); 464 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 465 466 /* 467 * With the new L2/L3 restructure, the route 468 * returned is a prefix route. The important 469 * piece of information from the previous 470 * RTM_GET is the interface index. In the 471 * case of ECMP, the kernel will traverse 472 * the route group for the given entry. 473 */ 474 if (sdl->sdl_family == AF_LINK && 475 !(rtm->rtm_flags & RTF_GATEWAY) && 476 valid_type(sdl->sdl_type) ) { 477 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 478 break; 479 } 480 481 /* 482 * Regualar entry delete failed, now check if there 483 * is a proxy-arp entry to remove. 484 */ 485 if (flags & RTF_ANNOUNCE) { 486 fprintf(stderr, "delete: cannot locate %s\n",host); 487 return (1); 488 } 489 490 flags |= RTF_ANNOUNCE; 491 } 492 rtm->rtm_flags |= RTF_LLDATA; 493 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 494 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 495 return (0); 496 } 497 return (1); 498} 499 500 501/* 502 * Search the arp table and do some action on matching entries 503 */ 504static int 505search(u_long addr, action_fn *action) 506{ 507 int mib[6]; 508 size_t needed; 509 char *lim, *buf, *next; 510 struct rt_msghdr *rtm; 511 struct sockaddr_inarp *sin2; 512 struct sockaddr_dl *sdl; 513 char ifname[IF_NAMESIZE]; 514 int st, found_entry = 0; 515 516 mib[0] = CTL_NET; 517 mib[1] = PF_ROUTE; 518 mib[2] = 0; 519 mib[3] = AF_INET; 520 mib[4] = NET_RT_FLAGS; 521#ifdef RTF_LLINFO 522 mib[5] = RTF_LLINFO; 523#else 524 mib[5] = 0; 525#endif 526 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 527 err(1, "route-sysctl-estimate"); 528 if (needed == 0) /* empty table */ 529 return 0; 530 buf = NULL; 531 for (;;) { 532 buf = reallocf(buf, needed); 533 if (buf == NULL) 534 errx(1, "could not reallocate memory"); 535 st = sysctl(mib, 6, buf, &needed, NULL, 0); 536 if (st == 0 || errno != ENOMEM) 537 break; 538 needed += needed / 8; 539 } 540 if (st == -1) 541 err(1, "actual retrieval of routing table"); 542 lim = buf + needed; 543 for (next = buf; next < lim; next += rtm->rtm_msglen) { 544 rtm = (struct rt_msghdr *)next; 545 sin2 = (struct sockaddr_inarp *)(rtm + 1); 546 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 547 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 548 strcmp(ifname, rifname)) 549 continue; 550 if (addr) { 551 if (addr != sin2->sin_addr.s_addr) 552 continue; 553 found_entry = 1; 554 } 555 (*action)(sdl, sin2, rtm); 556 } 557 free(buf); 558 return (found_entry); 559} 560 561/* 562 * Display an arp entry 563 */ 564static char lifname[IF_NAMESIZE]; 565static int64_t lifindex = -1; 566 567static void 568print_entry(struct sockaddr_dl *sdl, 569 struct sockaddr_inarp *addr, struct rt_msghdr *rtm) 570{ 571 const char *host; 572 struct hostent *hp; 573 struct iso88025_sockaddr_dl_data *trld; 574 int seg; 575 576 if (nflag == 0) 577 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 578 sizeof addr->sin_addr, AF_INET); 579 else 580 hp = 0; 581 if (hp) 582 host = hp->h_name; 583 else { 584 host = "?"; 585 if (h_errno == TRY_AGAIN) 586 nflag = 1; 587 } 588 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 589 if (sdl->sdl_alen) { 590 if ((sdl->sdl_type == IFT_ETHER || 591 sdl->sdl_type == IFT_L2VLAN || 592 sdl->sdl_type == IFT_BRIDGE) && 593 sdl->sdl_alen == ETHER_ADDR_LEN) 594 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 595 else { 596 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 597 598 printf("%s", link_ntoa(sdl) + n); 599 } 600 } else 601 printf("(incomplete)"); 602 if (sdl->sdl_index != lifindex && 603 if_indextoname(sdl->sdl_index, lifname) != NULL) { 604 lifindex = sdl->sdl_index; 605 printf(" on %s", lifname); 606 } else if (sdl->sdl_index == lifindex) 607 printf(" on %s", lifname); 608 if (rtm->rtm_rmx.rmx_expire == 0) 609 printf(" permanent"); 610 else { 611 static struct timespec tp; 612 if (tp.tv_sec == 0) 613 clock_gettime(CLOCK_MONOTONIC, &tp); 614 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 615 printf(" expires in %d seconds", (int)expire_time); 616 else 617 printf(" expired"); 618 } 619 if (addr->sin_other & SIN_PROXY) 620 printf(" published (proxy only)"); 621 if (rtm->rtm_flags & RTF_ANNOUNCE) 622 printf(" published"); 623 switch(sdl->sdl_type) { 624 case IFT_ETHER: 625 printf(" [ethernet]"); 626 break; 627 case IFT_ISO88025: 628 printf(" [token-ring]"); 629 trld = SDL_ISO88025(sdl); 630 if (trld->trld_rcf != 0) { 631 printf(" rt=%x", ntohs(trld->trld_rcf)); 632 for (seg = 0; 633 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 634 seg++) 635 printf(":%x", ntohs(*(trld->trld_route[seg]))); 636 } 637 break; 638 case IFT_FDDI: 639 printf(" [fddi]"); 640 break; 641 case IFT_ATM: 642 printf(" [atm]"); 643 break; 644 case IFT_L2VLAN: 645 printf(" [vlan]"); 646 break; 647 case IFT_IEEE1394: 648 printf(" [firewire]"); 649 break; 650 case IFT_BRIDGE: 651 printf(" [bridge]"); 652 break; 653 default: 654 break; 655 } 656 657 printf("\n"); 658 659} 660 661/* 662 * Nuke an arp entry 663 */ 664static void 665nuke_entry(struct sockaddr_dl *sdl __unused, 666 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused) 667{ 668 char ip[20]; 669 670 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 671 (void)delete(ip, 0); 672} 673 674static void 675usage(void) 676{ 677 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 678 "usage: arp [-n] [-i interface] hostname", 679 " arp [-n] [-i interface] -a", 680 " arp -d hostname [pub]", 681 " arp -d [-i interface] -a", 682 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 683 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 684 " arp -f filename"); 685 exit(1); 686} 687 688static struct rt_msghdr * 689rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl) 690{ 691 static int seq; 692 int rlen; 693 int l; 694 struct sockaddr_in so_mask, *som = &so_mask; 695 static int s = -1; 696 static pid_t pid; 697 698 static struct { 699 struct rt_msghdr m_rtm; 700 char m_space[512]; 701 } m_rtmsg; 702 703 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 704 char *cp = m_rtmsg.m_space; 705 706 if (s < 0) { /* first time: open socket, get pid */ 707 s = socket(PF_ROUTE, SOCK_RAW, 0); 708 if (s < 0) 709 err(1, "socket"); 710 pid = getpid(); 711 } 712 bzero(&so_mask, sizeof(so_mask)); 713 so_mask.sin_len = 8; 714 so_mask.sin_addr.s_addr = 0xffffffff; 715 716 errno = 0; 717 /* 718 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 719 * appropriately. 720 */ 721 if (cmd == RTM_DELETE) 722 goto doit; 723 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 724 rtm->rtm_flags = flags; 725 rtm->rtm_version = RTM_VERSION; 726 727 switch (cmd) { 728 default: 729 errx(1, "internal wrong cmd"); 730 case RTM_ADD: 731 rtm->rtm_addrs |= RTA_GATEWAY; 732 rtm->rtm_rmx.rmx_expire = expire_time; 733 rtm->rtm_inits = RTV_EXPIRE; 734 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 735 dst->sin_other = 0; 736 if (doing_proxy) { 737 if (proxy_only) 738 dst->sin_other = SIN_PROXY; 739 else { 740 rtm->rtm_addrs |= RTA_NETMASK; 741 rtm->rtm_flags &= ~RTF_HOST; 742 } 743 } 744 /* FALLTHROUGH */ 745 case RTM_GET: 746 rtm->rtm_addrs |= RTA_DST; 747 } 748#define NEXTADDR(w, s) \ 749 do { \ 750 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 751 bcopy((s), cp, sizeof(*(s))); \ 752 cp += SA_SIZE(s); \ 753 } \ 754 } while (0) 755 756 NEXTADDR(RTA_DST, dst); 757 NEXTADDR(RTA_GATEWAY, sdl); 758 NEXTADDR(RTA_NETMASK, som); 759 760 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 761doit: 762 l = rtm->rtm_msglen; 763 rtm->rtm_seq = ++seq; 764 rtm->rtm_type = cmd; 765 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 766 if (errno != ESRCH || cmd != RTM_DELETE) { 767 warn("writing to routing socket"); 768 return (NULL); 769 } 770 } 771 do { 772 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 773 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 774 if (l < 0) 775 warn("read from routing socket"); 776 return (rtm); 777} 778 779/* 780 * get_ether_addr - get the hardware address of an interface on the 781 * the same subnet as ipaddr. 782 */ 783#define MAX_IFS 32 784 785static int 786get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 787{ 788 struct ifreq *ifr, *ifend, *ifp; 789 in_addr_t ina, mask; 790 struct sockaddr_dl *dla; 791 struct ifreq ifreq; 792 struct ifconf ifc; 793 struct ifreq ifs[MAX_IFS]; 794 int sock; 795 int retval = 0; 796 797 sock = socket(AF_INET, SOCK_DGRAM, 0); 798 if (sock < 0) 799 err(1, "socket"); 800 801 ifc.ifc_len = sizeof(ifs); 802 ifc.ifc_req = ifs; 803 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 804 warnx("ioctl(SIOCGIFCONF)"); 805 goto done; 806 } 807 808#define NEXTIFR(i) \ 809 ((struct ifreq *)((char *)&(i)->ifr_addr \ 810 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 811 812 /* 813 * Scan through looking for an interface with an Internet 814 * address on the same subnet as `ipaddr'. 815 */ 816 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 817 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 818 if (ifr->ifr_addr.sa_family != AF_INET) 819 continue; 820 strncpy(ifreq.ifr_name, ifr->ifr_name, 821 sizeof(ifreq.ifr_name)); 822 ifreq.ifr_addr = ifr->ifr_addr; 823 /* 824 * Check that the interface is up, 825 * and not point-to-point or loopback. 826 */ 827 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 828 continue; 829 if ((ifreq.ifr_flags & 830 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 831 IFF_LOOPBACK|IFF_NOARP)) 832 != (IFF_UP|IFF_BROADCAST)) 833 continue; 834 /* 835 * Get its netmask and check that it's on 836 * the right subnet. 837 */ 838 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 839 continue; 840 mask = ((struct sockaddr_in *) 841 &ifreq.ifr_addr)->sin_addr.s_addr; 842 ina = ((struct sockaddr_in *) 843 &ifr->ifr_addr)->sin_addr.s_addr; 844 if ((ipaddr & mask) == (ina & mask)) 845 break; /* ok, we got it! */ 846 } 847 848 if (ifr >= ifend) 849 goto done; 850 851 /* 852 * Now scan through again looking for a link-level address 853 * for this interface. 854 */ 855 ifp = ifr; 856 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 857 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 858 ifr->ifr_addr.sa_family == AF_LINK) 859 break; 860 if (ifr >= ifend) 861 goto done; 862 /* 863 * Found the link-level address - copy it out 864 */ 865 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 866 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 867 printf("using interface %s for proxy with address ", 868 ifp->ifr_name); 869 printf("%s\n", ether_ntoa(hwaddr)); 870 retval = dla->sdl_alen; 871done: 872 close(sock); 873 return (retval); 874} 875