arp.c revision 216076
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: head/usr.sbin/arp/arp.c 216076 2010-11-30 16:00:59Z 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 clock_gettime(CLOCK_MONOTONIC, &tp); 324 expire_time = tp.tv_sec + 20 * 60; 325 } else if (strncmp(argv[0], "pub", 3) == 0) { 326 flags |= RTF_ANNOUNCE; 327 doing_proxy = 1; 328 if (argc && strncmp(argv[1], "only", 3) == 0) { 329 proxy_only = 1; 330 argc--; argv++; 331 } 332 } else if (strncmp(argv[0], "blackhole", 9) == 0) { 333 if (flags & RTF_REJECT) { 334 printf("Choose one of blackhole or reject, not both.\n"); 335 } 336 flags |= RTF_BLACKHOLE; 337 } else if (strncmp(argv[0], "reject", 6) == 0) { 338 if (flags & RTF_BLACKHOLE) { 339 printf("Choose one of blackhole or reject, not both.\n"); 340 } 341 flags |= RTF_REJECT; 342 } else if (strncmp(argv[0], "trail", 5) == 0) { 343 /* XXX deprecated and undocumented feature */ 344 printf("%s: Sending trailers is no longer supported\n", 345 host); 346 } 347 argv++; 348 } 349 ea = (struct ether_addr *)LLADDR(&sdl_m); 350 if (doing_proxy && !strcmp(eaddr, "auto")) { 351 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { 352 printf("no interface found for %s\n", 353 inet_ntoa(dst->sin_addr)); 354 return (1); 355 } 356 sdl_m.sdl_alen = ETHER_ADDR_LEN; 357 } else { 358 struct ether_addr *ea1 = ether_aton(eaddr); 359 360 if (ea1 == NULL) { 361 warnx("invalid Ethernet address '%s'", eaddr); 362 return (1); 363 } else { 364 *ea = *ea1; 365 sdl_m.sdl_alen = ETHER_ADDR_LEN; 366 } 367 } 368 369 /* 370 * In the case a proxy-arp entry is being added for 371 * a remote end point, the RTF_ANNOUNCE flag in the 372 * RTM_GET command is an indication to the kernel 373 * routing code that the interface associated with 374 * the prefix route covering the local end of the 375 * PPP link should be returned, on which ARP applies. 376 */ 377 rtm = rtmsg(RTM_GET, dst, &sdl_m); 378 if (rtm == NULL) { 379 warn("%s", host); 380 return (1); 381 } 382 addr = (struct sockaddr_inarp *)(rtm + 1); 383 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 384 if (addr->sin_addr.s_addr == dst->sin_addr.s_addr) { 385 printf("set: proxy entry exists for non 802 device\n"); 386 return (1); 387 } 388 389 if ((sdl->sdl_family != AF_LINK) || 390 (rtm->rtm_flags & RTF_GATEWAY) || 391 !valid_type(sdl->sdl_type)) { 392 printf("cannot intuit interface index and type for %s\n", host); 393 return (1); 394 } 395 sdl_m.sdl_type = sdl->sdl_type; 396 sdl_m.sdl_index = sdl->sdl_index; 397 return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); 398} 399 400/* 401 * Display an individual arp entry 402 */ 403static int 404get(char *host) 405{ 406 struct sockaddr_inarp *addr; 407 408 addr = getaddr(host); 409 if (addr == NULL) 410 return (1); 411 if (0 == search(addr->sin_addr.s_addr, print_entry)) { 412 printf("%s (%s) -- no entry", 413 host, inet_ntoa(addr->sin_addr)); 414 if (rifname) 415 printf(" on %s", rifname); 416 printf("\n"); 417 return (1); 418 } 419 return (0); 420} 421 422/* 423 * Delete an arp entry 424 */ 425static int 426delete(char *host, int do_proxy) 427{ 428 struct sockaddr_inarp *addr, *dst; 429 struct rt_msghdr *rtm; 430 struct sockaddr_dl *sdl; 431 struct sockaddr_dl sdl_m; 432 433 dst = getaddr(host); 434 if (dst == NULL) 435 return (1); 436 437 /* 438 * Perform a regular entry delete first. 439 */ 440 flags &= ~RTF_ANNOUNCE; 441 442 /* 443 * setup the data structure to notify the kernel 444 * it is the ARP entry the RTM_GET is interested 445 * in 446 */ 447 bzero(&sdl_m, sizeof(sdl_m)); 448 sdl_m.sdl_len = sizeof(sdl_m); 449 sdl_m.sdl_family = AF_LINK; 450 451 for (;;) { /* try twice */ 452 rtm = rtmsg(RTM_GET, dst, &sdl_m); 453 if (rtm == NULL) { 454 warn("%s", host); 455 return (1); 456 } 457 addr = (struct sockaddr_inarp *)(rtm + 1); 458 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); 459 460 /* 461 * With the new L2/L3 restructure, the route 462 * returned is a prefix route. The important 463 * piece of information from the previous 464 * RTM_GET is the interface index. In the 465 * case of ECMP, the kernel will traverse 466 * the route group for the given entry. 467 */ 468 if (sdl->sdl_family == AF_LINK && 469 !(rtm->rtm_flags & RTF_GATEWAY) && 470 valid_type(sdl->sdl_type) ) { 471 addr->sin_addr.s_addr = dst->sin_addr.s_addr; 472 break; 473 } 474 475 /* 476 * Regualar entry delete failed, now check if there 477 * is a proxy-arp entry to remove. 478 */ 479 if (flags & RTF_ANNOUNCE) { 480 fprintf(stderr, "delete: cannot locate %s\n",host); 481 return (1); 482 } 483 484 flags |= RTF_ANNOUNCE; 485 } 486 rtm->rtm_flags |= RTF_LLDATA; 487 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { 488 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); 489 return (0); 490 } 491 return (1); 492} 493 494 495/* 496 * Search the arp table and do some action on matching entries 497 */ 498static int 499search(u_long addr, action_fn *action) 500{ 501 int mib[6]; 502 size_t needed; 503 char *lim, *buf, *next; 504 struct rt_msghdr *rtm; 505 struct sockaddr_inarp *sin2; 506 struct sockaddr_dl *sdl; 507 char ifname[IF_NAMESIZE]; 508 int st, found_entry = 0; 509 510 mib[0] = CTL_NET; 511 mib[1] = PF_ROUTE; 512 mib[2] = 0; 513 mib[3] = AF_INET; 514 mib[4] = NET_RT_FLAGS; 515#ifdef RTF_LLINFO 516 mib[5] = RTF_LLINFO; 517#else 518 mib[5] = 0; 519#endif 520 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 521 err(1, "route-sysctl-estimate"); 522 if (needed == 0) /* empty table */ 523 return 0; 524 buf = NULL; 525 for (;;) { 526 buf = reallocf(buf, needed); 527 if (buf == NULL) 528 errx(1, "could not reallocate memory"); 529 st = sysctl(mib, 6, buf, &needed, NULL, 0); 530 if (st == 0 || errno != ENOMEM) 531 break; 532 needed += needed / 8; 533 } 534 if (st == -1) 535 err(1, "actual retrieval of routing table"); 536 lim = buf + needed; 537 for (next = buf; next < lim; next += rtm->rtm_msglen) { 538 rtm = (struct rt_msghdr *)next; 539 sin2 = (struct sockaddr_inarp *)(rtm + 1); 540 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); 541 if (rifname && if_indextoname(sdl->sdl_index, ifname) && 542 strcmp(ifname, rifname)) 543 continue; 544 if (addr) { 545 if (addr != sin2->sin_addr.s_addr) 546 continue; 547 found_entry = 1; 548 } 549 (*action)(sdl, sin2, rtm); 550 } 551 free(buf); 552 return (found_entry); 553} 554 555/* 556 * Display an arp entry 557 */ 558static char lifname[IF_NAMESIZE]; 559static int64_t lifindex = -1; 560 561static void 562print_entry(struct sockaddr_dl *sdl, 563 struct sockaddr_inarp *addr, struct rt_msghdr *rtm) 564{ 565 const char *host; 566 struct hostent *hp; 567 struct iso88025_sockaddr_dl_data *trld; 568 int seg; 569 570 if (nflag == 0) 571 hp = gethostbyaddr((caddr_t)&(addr->sin_addr), 572 sizeof addr->sin_addr, AF_INET); 573 else 574 hp = 0; 575 if (hp) 576 host = hp->h_name; 577 else { 578 host = "?"; 579 if (h_errno == TRY_AGAIN) 580 nflag = 1; 581 } 582 printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); 583 if (sdl->sdl_alen) { 584 if ((sdl->sdl_type == IFT_ETHER || 585 sdl->sdl_type == IFT_L2VLAN || 586 sdl->sdl_type == IFT_BRIDGE) && 587 sdl->sdl_alen == ETHER_ADDR_LEN) 588 printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); 589 else { 590 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; 591 592 printf("%s", link_ntoa(sdl) + n); 593 } 594 } else 595 printf("(incomplete)"); 596 if (sdl->sdl_index != lifindex && 597 if_indextoname(sdl->sdl_index, lifname) != NULL) { 598 lifindex = sdl->sdl_index; 599 printf(" on %s", lifname); 600 } else if (sdl->sdl_index == lifindex) 601 printf(" on %s", lifname); 602 if (rtm->rtm_rmx.rmx_expire == 0) 603 printf(" permanent"); 604 else { 605 static struct timespec tp; 606 if (tp.tv_sec == 0) 607 clock_gettime(CLOCK_MONOTONIC, &tp); 608 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) 609 printf(" expires in %d seconds", (int)expire_time); 610 else 611 printf(" expired"); 612 } 613 if (addr->sin_other & SIN_PROXY) 614 printf(" published (proxy only)"); 615 if (rtm->rtm_flags & RTF_ANNOUNCE) 616 printf(" published"); 617 switch(sdl->sdl_type) { 618 case IFT_ETHER: 619 printf(" [ethernet]"); 620 break; 621 case IFT_ISO88025: 622 printf(" [token-ring]"); 623 trld = SDL_ISO88025(sdl); 624 if (trld->trld_rcf != 0) { 625 printf(" rt=%x", ntohs(trld->trld_rcf)); 626 for (seg = 0; 627 seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); 628 seg++) 629 printf(":%x", ntohs(*(trld->trld_route[seg]))); 630 } 631 break; 632 case IFT_FDDI: 633 printf(" [fddi]"); 634 break; 635 case IFT_ATM: 636 printf(" [atm]"); 637 break; 638 case IFT_L2VLAN: 639 printf(" [vlan]"); 640 break; 641 case IFT_IEEE1394: 642 printf(" [firewire]"); 643 break; 644 case IFT_BRIDGE: 645 printf(" [bridge]"); 646 break; 647 default: 648 break; 649 } 650 651 printf("\n"); 652 653} 654 655/* 656 * Nuke an arp entry 657 */ 658static void 659nuke_entry(struct sockaddr_dl *sdl __unused, 660 struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused) 661{ 662 char ip[20]; 663 664 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); 665 (void)delete(ip, 0); 666} 667 668static void 669usage(void) 670{ 671 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", 672 "usage: arp [-n] [-i interface] hostname", 673 " arp [-n] [-i interface] -a", 674 " arp -d hostname [pub]", 675 " arp -d [-i interface] -a", 676 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 677 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", 678 " arp -f filename"); 679 exit(1); 680} 681 682static struct rt_msghdr * 683rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl) 684{ 685 static int seq; 686 int rlen; 687 int l; 688 struct sockaddr_in so_mask, *som = &so_mask; 689 static int s = -1; 690 static pid_t pid; 691 692 static struct { 693 struct rt_msghdr m_rtm; 694 char m_space[512]; 695 } m_rtmsg; 696 697 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 698 char *cp = m_rtmsg.m_space; 699 700 if (s < 0) { /* first time: open socket, get pid */ 701 s = socket(PF_ROUTE, SOCK_RAW, 0); 702 if (s < 0) 703 err(1, "socket"); 704 pid = getpid(); 705 } 706 bzero(&so_mask, sizeof(so_mask)); 707 so_mask.sin_len = 8; 708 so_mask.sin_addr.s_addr = 0xffffffff; 709 710 errno = 0; 711 /* 712 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer 713 * appropriately. 714 */ 715 if (cmd == RTM_DELETE) 716 goto doit; 717 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 718 rtm->rtm_flags = flags; 719 rtm->rtm_version = RTM_VERSION; 720 721 switch (cmd) { 722 default: 723 errx(1, "internal wrong cmd"); 724 case RTM_ADD: 725 rtm->rtm_addrs |= RTA_GATEWAY; 726 rtm->rtm_rmx.rmx_expire = expire_time; 727 rtm->rtm_inits = RTV_EXPIRE; 728 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 729 dst->sin_other = 0; 730 if (doing_proxy) { 731 if (proxy_only) 732 dst->sin_other = SIN_PROXY; 733 else { 734 rtm->rtm_addrs |= RTA_NETMASK; 735 rtm->rtm_flags &= ~RTF_HOST; 736 } 737 } 738 /* FALLTHROUGH */ 739 case RTM_GET: 740 rtm->rtm_addrs |= RTA_DST; 741 } 742#define NEXTADDR(w, s) \ 743 do { \ 744 if ((s) != NULL && rtm->rtm_addrs & (w)) { \ 745 bcopy((s), cp, sizeof(*(s))); \ 746 cp += SA_SIZE(s); \ 747 } \ 748 } while (0) 749 750 NEXTADDR(RTA_DST, dst); 751 NEXTADDR(RTA_GATEWAY, sdl); 752 NEXTADDR(RTA_NETMASK, som); 753 754 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 755doit: 756 l = rtm->rtm_msglen; 757 rtm->rtm_seq = ++seq; 758 rtm->rtm_type = cmd; 759 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 760 if (errno != ESRCH || cmd != RTM_DELETE) { 761 warn("writing to routing socket"); 762 return (NULL); 763 } 764 } 765 do { 766 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 767 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 768 if (l < 0) 769 warn("read from routing socket"); 770 return (rtm); 771} 772 773/* 774 * get_ether_addr - get the hardware address of an interface on the 775 * the same subnet as ipaddr. 776 */ 777#define MAX_IFS 32 778 779static int 780get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) 781{ 782 struct ifreq *ifr, *ifend, *ifp; 783 in_addr_t ina, mask; 784 struct sockaddr_dl *dla; 785 struct ifreq ifreq; 786 struct ifconf ifc; 787 struct ifreq ifs[MAX_IFS]; 788 int sock; 789 int retval = 0; 790 791 sock = socket(AF_INET, SOCK_DGRAM, 0); 792 if (sock < 0) 793 err(1, "socket"); 794 795 ifc.ifc_len = sizeof(ifs); 796 ifc.ifc_req = ifs; 797 if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { 798 warnx("ioctl(SIOCGIFCONF)"); 799 goto done; 800 } 801 802#define NEXTIFR(i) \ 803 ((struct ifreq *)((char *)&(i)->ifr_addr \ 804 + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) 805 806 /* 807 * Scan through looking for an interface with an Internet 808 * address on the same subnet as `ipaddr'. 809 */ 810 ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); 811 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { 812 if (ifr->ifr_addr.sa_family != AF_INET) 813 continue; 814 strncpy(ifreq.ifr_name, ifr->ifr_name, 815 sizeof(ifreq.ifr_name)); 816 ifreq.ifr_addr = ifr->ifr_addr; 817 /* 818 * Check that the interface is up, 819 * and not point-to-point or loopback. 820 */ 821 if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) 822 continue; 823 if ((ifreq.ifr_flags & 824 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 825 IFF_LOOPBACK|IFF_NOARP)) 826 != (IFF_UP|IFF_BROADCAST)) 827 continue; 828 /* 829 * Get its netmask and check that it's on 830 * the right subnet. 831 */ 832 if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) 833 continue; 834 mask = ((struct sockaddr_in *) 835 &ifreq.ifr_addr)->sin_addr.s_addr; 836 ina = ((struct sockaddr_in *) 837 &ifr->ifr_addr)->sin_addr.s_addr; 838 if ((ipaddr & mask) == (ina & mask)) 839 break; /* ok, we got it! */ 840 } 841 842 if (ifr >= ifend) 843 goto done; 844 845 /* 846 * Now scan through again looking for a link-level address 847 * for this interface. 848 */ 849 ifp = ifr; 850 for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) 851 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && 852 ifr->ifr_addr.sa_family == AF_LINK) 853 break; 854 if (ifr >= ifend) 855 goto done; 856 /* 857 * Found the link-level address - copy it out 858 */ 859 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 860 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 861 printf("using interface %s for proxy with address ", 862 ifp->ifr_name); 863 printf("%s\n", ether_ntoa(hwaddr)); 864 retval = dla->sdl_alen; 865done: 866 close(sock); 867 return (retval); 868} 869