1 /* $NetBSD: arp.c,v 1.47 2008/07/21 13:36:57 lukem Exp $ */ 2 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 #include <sys/cdefs.h> 36 #ifndef lint 37 __COPYRIGHT("@(#) Copyright (c) 1984, 1993\ 38 The Regents of the University of California. All rights reserved."); 39 #endif /* not lint */ 40 41 #ifndef lint 42 #if 0 43 static char sccsid[] = "@(#)arp.c 8.3 (Berkeley) 4/28/95"; 44 #else 45 __RCSID("$NetBSD: arp.c,v 1.47 2008/07/21 13:36:57 lukem Exp $"); 46 #endif 47 #endif /* not lint */ 48 49 /* 50 * arp - display, set, and delete arp table entries 51 */ 52 53 /* Roundup the same way rt_xaddrs does */ 54 #define ROUNDUP(a) \ 55 ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long)) 56 57 #include <sys/param.h> 58 #include <sys/file.h> 59 #include <sys/socket.h> 60 #include <sys/sysctl.h> 61 #include <sys/ioctl.h> 62 63 #include <net/if.h> 64 #include <net/if_dl.h> 65 #include <net/if_ether.h> 66 #include <net/if_types.h> 67 #include <net/route.h> 68 #include <netinet/in.h> 69 #include <netinet/if_inarp.h> 70 #include <arpa/inet.h> 71 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 <unistd.h> 81 #include <ifaddrs.h> 82 83 static int is_llinfo(const struct sockaddr_dl *, int); 84 static int delete(const char *, const char *); 85 static void dump(uint32_t); 86 static void delete_all(void); 87 static void sdl_print(const struct sockaddr_dl *); 88 static int getifname(u_int16_t, char *, size_t); 89 static int atosdl(const char *s, struct sockaddr_dl *sdl); 90 static int file(const char *); 91 static void get(const char *); 92 static int getinetaddr(const char *, struct in_addr *); 93 static void getsocket(void); 94 static int rtmsg(int); 95 static int set(int, char **); 96 static void usage(void) __dead; 97 98 static pid_t pid; 99 static int aflag, nflag, vflag; 100 static int s = -1; 101 static struct ifaddrs* ifaddrs = NULL; 102 static struct sockaddr_in so_mask = { 103 .sin_len = 8, 104 .sin_addr = { 105 .s_addr = 0xffffffff 106 } 107 }; 108 static struct sockaddr_inarp blank_sin = { 109 .sin_len = sizeof(blank_sin), 110 .sin_family = AF_INET 111 }; 112 static struct sockaddr_inarp sin_m; 113 static struct sockaddr_dl blank_sdl = { 114 .sdl_len = sizeof(blank_sdl), 115 .sdl_family = AF_LINK 116 }; 117 static struct sockaddr_dl sdl_m; 118 119 static int expire_time, flags, export_only, doing_proxy, found_entry; 120 static struct { 121 struct rt_msghdr m_rtm; 122 char m_space[512]; 123 } m_rtmsg; 124 125 int 126 main(int argc, char **argv) 127 { 128 int ch; 129 int op = 0; 130 131 setprogname(argv[0]); 132 133 pid = getpid(); 134 135 while ((ch = getopt(argc, argv, "andsfv")) != -1) 136 switch((char)ch) { 137 case 'a': 138 aflag = 1; 139 break; 140 case 'd': 141 case 's': 142 case 'f': 143 if (op) 144 usage(); 145 op = ch; 146 break; 147 case 'n': 148 nflag = 1; 149 break; 150 case 'v': 151 vflag = 1; 152 break; 153 default: 154 usage(); 155 } 156 argc -= optind; 157 argv += optind; 158 159 if (!op && aflag) 160 op = 'a'; 161 162 switch((char)op) { 163 case 'a': 164 dump(0); 165 break; 166 case 'd': 167 if (aflag && argc == 0) 168 delete_all(); 169 else { 170 if (aflag || argc < 1 || argc > 2) 171 usage(); 172 (void)delete(argv[0], argv[1]); 173 } 174 break; 175 case 's': 176 if (argc < 2 || argc > 5) 177 usage(); 178 return (set(argc, argv) ? 1 : 0); 179 case 'f': 180 if (argc != 1) 181 usage(); 182 return (file(argv[0])); 183 default: 184 if (argc != 1) 185 usage(); 186 get(argv[0]); 187 break; 188 } 189 return (0); 190 } 191 192 /* 193 * Process a file to set standard arp entries 194 */ 195 static int 196 file(const char *name) 197 { 198 char *line, *argv[5]; 199 int i, retval; 200 FILE *fp; 201 202 if ((fp = fopen(name, "r")) == NULL) 203 err(1, "cannot open %s", name); 204 retval = 0; 205 for (; (line = fparseln(fp, NULL, NULL, NULL, 0)) != NULL; free(line)) { 206 char **ap, *inputstring; 207 208 inputstring = line; 209 for (ap = argv; ap < &argv[sizeof(argv) / sizeof(argv[0])] && 210 (*ap = stresep(&inputstring, " \t", '\\')) != NULL;) { 211 if (**ap != '\0') 212 ap++; 213 } 214 i = ap - argv; 215 if (i < 2) { 216 warnx("bad line: %s", line); 217 retval = 1; 218 continue; 219 } 220 if (set(i, argv)) 221 retval = 1; 222 } 223 (void)fclose(fp); 224 return retval; 225 } 226 227 static void 228 getsocket(void) 229 { 230 if (s >= 0) 231 return; 232 s = socket(PF_ROUTE, SOCK_RAW, 0); 233 if (s < 0) 234 err(1, "socket"); 235 } 236 237 /* 238 * Set an individual arp entry 239 */ 240 static int 241 set(int argc, char **argv) 242 { 243 struct sockaddr_inarp *sina; 244 struct sockaddr_dl *sdl; 245 struct rt_msghdr *rtm; 246 char *host = argv[0], *eaddr; 247 int rval; 248 249 sina = &sin_m; 250 rtm = &(m_rtmsg.m_rtm); 251 eaddr = argv[1]; 252 253 getsocket(); 254 argc -= 2; 255 argv += 2; 256 sdl_m = blank_sdl; /* struct copy */ 257 sin_m = blank_sin; /* struct copy */ 258 if (getinetaddr(host, &sina->sin_addr) == -1) 259 return (1); 260 if (atosdl(eaddr, &sdl_m)) 261 warnx("invalid link-level address '%s'", eaddr); 262 doing_proxy = flags = export_only = expire_time = 0; 263 while (argc-- > 0) { 264 if (strncmp(argv[0], "temp", 4) == 0) { 265 struct timeval timev; 266 (void)gettimeofday(&timev, 0); 267 expire_time = timev.tv_sec + 20 * 60; 268 } 269 else if (strncmp(argv[0], "pub", 3) == 0) { 270 flags |= RTF_ANNOUNCE; 271 doing_proxy = SIN_PROXY; 272 if (argc && strncmp(argv[1], "pro", 3) == 0) { 273 export_only = 1; 274 argc--; argv++; 275 } 276 } else if (strncmp(argv[0], "trail", 5) == 0) { 277 warnx("%s: Sending trailers is no longer supported", 278 host); 279 } 280 argv++; 281 } 282 tryagain: 283 if (rtmsg(RTM_GET) < 0) { 284 warn("%s", host); 285 return (1); 286 } 287 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 288 sdl = (struct sockaddr_dl *)(void *)(ROUNDUP(sina->sin_len) + 289 (char *)(void *)sina); 290 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 291 if (is_llinfo(sdl, rtm->rtm_flags)) 292 goto overwrite; 293 if (doing_proxy == 0) { 294 warnx("set: can only proxy for %s", host); 295 return (1); 296 } 297 if (sin_m.sin_other & SIN_PROXY) { 298 warnx("set: proxy entry exists for non 802 device"); 299 return (1); 300 } 301 sin_m.sin_other = SIN_PROXY; 302 export_only = 1; 303 goto tryagain; 304 } 305 overwrite: 306 if (sdl->sdl_family != AF_LINK) { 307 warnx("cannot intuit interface index and type for %s", 308 host); 309 return (1); 310 } 311 sdl_m.sdl_type = sdl->sdl_type; 312 sdl_m.sdl_index = sdl->sdl_index; 313 rval = rtmsg(RTM_ADD); 314 if (vflag) 315 (void)printf("%s (%s) added\n", host, eaddr); 316 return (rval); 317 } 318 319 /* 320 * Display an individual arp entry 321 */ 322 static void 323 get(const char *host) 324 { 325 struct sockaddr_inarp *sina; 326 327 sina = &sin_m; 328 sin_m = blank_sin; /* struct copy */ 329 if (getinetaddr(host, &sina->sin_addr) == -1) 330 exit(1); 331 dump(sina->sin_addr.s_addr); 332 if (found_entry == 0) 333 errx(1, "%s (%s) -- no entry", host, inet_ntoa(sina->sin_addr)); 334 } 335 336 337 static int 338 is_llinfo(const struct sockaddr_dl *sdl, int rtflags) 339 { 340 if (sdl->sdl_family != AF_LINK || 341 (rtflags & (RTF_LLINFO|RTF_GATEWAY)) != RTF_LLINFO) 342 return 0; 343 344 switch (sdl->sdl_type) { 345 case IFT_ETHER: 346 case IFT_FDDI: 347 case IFT_ISO88023: 348 case IFT_ISO88024: 349 case IFT_ISO88025: 350 case IFT_ARCNET: 351 return 1; 352 default: 353 return 0; 354 } 355 } 356 357 /* 358 * Delete an arp entry 359 */ 360 int 361 delete(const char *host, const char *info) 362 { 363 struct sockaddr_inarp *sina; 364 struct rt_msghdr *rtm; 365 struct sockaddr_dl *sdl; 366 367 sina = &sin_m; 368 rtm = &m_rtmsg.m_rtm; 369 370 getsocket(); 371 sin_m = blank_sin; /* struct copy */ 372 if (info && strncmp(info, "pro", 3) == 0) 373 sina->sin_other = SIN_PROXY; 374 if (getinetaddr(host, &sina->sin_addr) == -1) 375 return (1); 376 tryagain: 377 if (rtmsg(RTM_GET) < 0) { 378 warn("%s", host); 379 return (1); 380 } 381 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 382 sdl = (struct sockaddr_dl *)(void *)(ROUNDUP(sina->sin_len) + 383 (char *)(void *)sina); 384 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr && 385 is_llinfo(sdl, rtm->rtm_flags)) 386 goto delete; 387 if (sin_m.sin_other & SIN_PROXY) { 388 warnx("delete: can't locate %s", host); 389 return (1); 390 } else { 391 sin_m.sin_other = SIN_PROXY; 392 goto tryagain; 393 } 394 delete: 395 if (sdl->sdl_family != AF_LINK) { 396 (void)warnx("cannot locate %s", host); 397 return (1); 398 } 399 if (rtmsg(RTM_DELETE)) 400 return (1); 401 if (vflag) 402 (void)printf("%s (%s) deleted\n", host, 403 inet_ntoa(sina->sin_addr)); 404 return (0); 405 } 406 407 /* 408 * Dump the entire arp table 409 */ 410 void 411 dump(uint32_t addr) 412 { 413 int mib[6]; 414 size_t needed; 415 char ifname[IFNAMSIZ]; 416 char *lim, *buf, *next; 417 const char *host; 418 struct rt_msghdr *rtm; 419 struct sockaddr_inarp *sina; 420 struct sockaddr_dl *sdl; 421 struct hostent *hp; 422 423 mib[0] = CTL_NET; 424 mib[1] = PF_ROUTE; 425 mib[2] = 0; 426 mib[3] = AF_INET; 427 mib[4] = NET_RT_FLAGS; 428 mib[5] = RTF_LLINFO; 429 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 430 err(1, "route-sysctl-estimate"); 431 if (needed == 0) 432 return; 433 if ((buf = malloc(needed)) == NULL) 434 err(1, "malloc"); 435 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 436 err(1, "actual retrieval of routing table"); 437 lim = buf + needed; 438 for (next = buf; next < lim; next += rtm->rtm_msglen) { 439 rtm = (struct rt_msghdr *)(void *)next; 440 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 441 sdl = (struct sockaddr_dl *)(void *) 442 (ROUNDUP(sina->sin_len) + (char *)(void *)sina); 443 if (addr) { 444 if (addr != sina->sin_addr.s_addr) 445 continue; 446 found_entry = 1; 447 } 448 if (nflag == 0) 449 hp = gethostbyaddr((const char *)(void *) 450 &(sina->sin_addr), 451 sizeof sina->sin_addr, AF_INET); 452 else 453 hp = NULL; 454 455 host = hp ? hp->h_name : "?"; 456 457 (void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr)); 458 if (sdl->sdl_alen) 459 sdl_print(sdl); 460 else 461 (void)printf("(incomplete)"); 462 463 if (sdl->sdl_index) { 464 if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0) 465 (void)printf(" on %s", ifname); 466 } 467 468 if (rtm->rtm_rmx.rmx_expire == 0) 469 (void)printf(" permanent"); 470 if (sina->sin_other & SIN_PROXY) 471 (void)printf(" published (proxy only)"); 472 if (rtm->rtm_addrs & RTA_NETMASK) { 473 sina = (struct sockaddr_inarp *)(void *) 474 (ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl); 475 if (sina->sin_addr.s_addr == 0xffffffff) 476 (void)printf(" published"); 477 if (sina->sin_len != 8) 478 (void)printf("(weird)"); 479 } 480 (void)printf("\n"); 481 } 482 free(buf); 483 } 484 485 /* 486 * Delete the entire arp table 487 */ 488 void 489 delete_all(void) 490 { 491 int mib[6]; 492 size_t needed; 493 char addr[sizeof("000.000.000.000\0")]; 494 char *lim, *buf, *next; 495 struct rt_msghdr *rtm; 496 struct sockaddr_inarp *sina; 497 498 mib[0] = CTL_NET; 499 mib[1] = PF_ROUTE; 500 mib[2] = 0; 501 mib[3] = AF_INET; 502 mib[4] = NET_RT_FLAGS; 503 mib[5] = RTF_LLINFO; 504 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 505 err(1, "route-sysctl-estimate"); 506 if (needed == 0) 507 return; 508 if ((buf = malloc(needed)) == NULL) 509 err(1, "malloc"); 510 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 511 err(1, "actual retrieval of routing table"); 512 lim = buf + needed; 513 for (next = buf; next < lim; next += rtm->rtm_msglen) { 514 rtm = (struct rt_msghdr *)(void *)next; 515 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 516 (void)snprintf(addr, sizeof(addr), "%s", 517 inet_ntoa(sina->sin_addr)); 518 (void)delete(addr, NULL); 519 } 520 free(buf); 521 } 522 523 void 524 sdl_print(const struct sockaddr_dl *sdl) 525 { 526 char hbuf[NI_MAXHOST]; 527 528 if (getnameinfo((const struct sockaddr *)(const void *)sdl, 529 (socklen_t)sdl->sdl_len, 530 hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) 531 (void)printf("<invalid>"); 532 else 533 (void)printf("%s", hbuf); 534 } 535 536 static int 537 atosdl(const char *ss, struct sockaddr_dl *sdl) 538 { 539 int i; 540 unsigned long b; 541 char *endp; 542 char *p; 543 char *t, *r; 544 545 p = LLADDR(sdl); 546 endp = ((char *)(void *)sdl) + sdl->sdl_len; 547 i = 0; 548 549 b = strtoul(ss, &t, 16); 550 if (b > 255 || t == ss) 551 return 1; 552 553 *p++ = (char)b; 554 ++i; 555 while ((p < endp) && (*t++ == ':')) { 556 b = strtoul(t, &r, 16); 557 if (b > 255 || r == t) 558 break; 559 *p++ = (char)b; 560 ++i; 561 t = r; 562 } 563 sdl->sdl_alen = i; 564 565 return 0; 566 } 567 568 static void 569 usage(void) 570 { 571 const char *progname; 572 573 progname = getprogname(); 574 (void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname); 575 (void)fprintf(stderr, " %s [-nv] -a\n", progname); 576 (void)fprintf(stderr, " %s [-v] -d [-a|hostname [pub [proxy]]]\n", 577 progname); 578 (void)fprintf(stderr, " %s -s hostname ether_addr [temp] [pub [proxy]]\n", 579 progname); 580 (void)fprintf(stderr, " %s -f filename\n", progname); 581 exit(1); 582 } 583 584 static int 585 rtmsg(int cmd) 586 { 587 static int seq; 588 struct rt_msghdr *rtm; 589 char *cp; 590 int l; 591 592 rtm = &m_rtmsg.m_rtm; 593 cp = m_rtmsg.m_space; 594 errno = 0; 595 596 if (cmd == RTM_DELETE) 597 goto doit; 598 (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg)); 599 rtm->rtm_flags = flags; 600 rtm->rtm_version = RTM_VERSION; 601 602 switch (cmd) { 603 default: 604 errx(1, "internal wrong cmd"); 605 /*NOTREACHED*/ 606 case RTM_ADD: 607 rtm->rtm_addrs |= RTA_GATEWAY; 608 rtm->rtm_rmx.rmx_expire = expire_time; 609 rtm->rtm_inits = RTV_EXPIRE; 610 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 611 sin_m.sin_other = 0; 612 if (doing_proxy) { 613 if (export_only) 614 sin_m.sin_other = SIN_PROXY; 615 else { 616 rtm->rtm_addrs |= RTA_NETMASK; 617 rtm->rtm_flags &= ~RTF_HOST; 618 } 619 } 620 /* FALLTHROUGH */ 621 case RTM_GET: 622 rtm->rtm_addrs |= RTA_DST; 623 } 624 625 #define NEXTADDR(w, s) \ 626 if (rtm->rtm_addrs & (w)) { \ 627 (void)memcpy(cp, &s, \ 628 (size_t)((struct sockaddr *)(void *)&s)->sa_len); \ 629 cp += ROUNDUP(((struct sockaddr *)(void *)&s)->sa_len); \ 630 } 631 632 NEXTADDR(RTA_DST, sin_m); 633 NEXTADDR(RTA_GATEWAY, sdl_m); 634 NEXTADDR(RTA_NETMASK, so_mask); 635 636 rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg; 637 doit: 638 l = rtm->rtm_msglen; 639 rtm->rtm_seq = ++seq; 640 rtm->rtm_type = cmd; 641 if (write(s, &m_rtmsg, (size_t)l) < 0) { 642 if (errno != ESRCH || cmd != RTM_DELETE) { 643 warn("writing to routing socket"); 644 return (-1); 645 } 646 } 647 do { 648 l = read(s, &m_rtmsg, sizeof(m_rtmsg)); 649 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 650 if (l < 0) 651 warn("read from routing socket"); 652 return (0); 653 } 654 655 static int 656 getinetaddr(const char *host, struct in_addr *inap) 657 { 658 struct hostent *hp; 659 660 if (inet_aton(host, inap) == 1) 661 return (0); 662 if ((hp = gethostbyname(host)) == NULL) { 663 warnx("%s: %s", host, hstrerror(h_errno)); 664 return (-1); 665 } 666 (void)memcpy(inap, hp->h_addr, sizeof(*inap)); 667 return (0); 668 } 669 670 static int 671 getifname(u_int16_t ifindex, char *ifname, size_t l) 672 { 673 int i; 674 struct ifaddrs *addr; 675 const struct sockaddr_dl *sdl = NULL; 676 677 if (ifaddrs == NULL) { 678 i = getifaddrs(&ifaddrs); 679 if (i != 0) 680 err(1, "getifaddrs"); 681 } 682 683 for (addr = ifaddrs; addr; addr = addr->ifa_next) { 684 if (addr->ifa_addr == NULL || 685 addr->ifa_addr->sa_family != AF_LINK) 686 continue; 687 688 sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr; 689 if (sdl && sdl->sdl_index == ifindex) { 690 (void) strlcpy(ifname, addr->ifa_name, l); 691 return 0; 692 } 693 } 694 695 return -1; 696 } 697