1 /* $NetBSD: arp.c,v 1.49 2010/06/10 06:03:20 dholland 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 1.49 2010/06/10 06:03:20 dholland Exp $"); 46 #endif 47 #endif /* not lint */ 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/sysctl.h> 57 #include <sys/ioctl.h> 58 59 #include <net/if.h> 60 #include <net/if_dl.h> 61 #include <net/if_ether.h> 62 #include <net/if_types.h> 63 #include <net/route.h> 64 #include <netinet/in.h> 65 #include <netinet/if_inarp.h> 66 #include <arpa/inet.h> 67 68 #include <err.h> 69 #include <errno.h> 70 #include <netdb.h> 71 #include <nlist.h> 72 #include <paths.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <unistd.h> 77 #include <ifaddrs.h> 78 79 static int is_llinfo(const struct sockaddr_dl *, int); 80 static int delete(const char *, const char *); 81 static void dump(uint32_t); 82 static void delete_all(void); 83 static void sdl_print(const struct sockaddr_dl *); 84 static int getifname(u_int16_t, char *, size_t); 85 static int atosdl(const char *s, struct sockaddr_dl *sdl); 86 static int file(const char *); 87 static void get(const char *); 88 static int getinetaddr(const char *, struct in_addr *); 89 static void getsocket(void); 90 static int rtmsg(int); 91 static int set(int, char **); 92 static void usage(void) __dead; 93 94 static pid_t pid; 95 static int aflag, nflag, vflag; 96 static int s = -1; 97 static struct ifaddrs* ifaddrs = NULL; 98 static struct sockaddr_in so_mask = { 99 .sin_len = 8, 100 .sin_addr = { 101 .s_addr = 0xffffffff 102 } 103 }; 104 static struct sockaddr_inarp blank_sin = { 105 .sin_len = sizeof(blank_sin), 106 .sin_family = AF_INET 107 }; 108 static struct sockaddr_inarp sin_m; 109 static struct sockaddr_dl blank_sdl = { 110 .sdl_len = sizeof(blank_sdl), 111 .sdl_family = AF_LINK 112 }; 113 static struct sockaddr_dl sdl_m; 114 115 static int expire_time, flags, export_only, doing_proxy, found_entry; 116 static struct { 117 struct rt_msghdr m_rtm; 118 char m_space[512]; 119 } m_rtmsg; 120 121 int 122 main(int argc, char **argv) 123 { 124 int ch; 125 int op = 0; 126 127 setprogname(argv[0]); 128 129 pid = getpid(); 130 131 while ((ch = getopt(argc, argv, "andsfv")) != -1) 132 switch((char)ch) { 133 case 'a': 134 aflag = 1; 135 break; 136 case 'd': 137 case 's': 138 case 'f': 139 if (op) 140 usage(); 141 op = ch; 142 break; 143 case 'n': 144 nflag = 1; 145 break; 146 case 'v': 147 vflag = 1; 148 break; 149 default: 150 usage(); 151 } 152 argc -= optind; 153 argv += optind; 154 155 if (!op && aflag) 156 op = 'a'; 157 158 switch((char)op) { 159 case 'a': 160 dump(0); 161 break; 162 case 'd': 163 if (aflag && argc == 0) 164 delete_all(); 165 else { 166 if (aflag || argc < 1 || argc > 2) 167 usage(); 168 (void)delete(argv[0], argv[1]); 169 } 170 break; 171 case 's': 172 if (argc < 2 || argc > 5) 173 usage(); 174 return (set(argc, argv) ? 1 : 0); 175 case 'f': 176 if (argc != 1) 177 usage(); 178 return (file(argv[0])); 179 default: 180 if (argc != 1) 181 usage(); 182 get(argv[0]); 183 break; 184 } 185 return (0); 186 } 187 188 /* 189 * Process a file to set standard arp entries 190 */ 191 static int 192 file(const char *name) 193 { 194 char *line, *argv[5]; 195 int i, retval; 196 FILE *fp; 197 198 if (!strcmp(name, "-")) { 199 fp = stdin; 200 } else { 201 fp = fopen(name, "r"); 202 if (fp == NULL) { 203 err(1, "Cannot open %s", name); 204 } 205 } 206 retval = 0; 207 for (; (line = fparseln(fp, NULL, NULL, NULL, 0)) != NULL; free(line)) { 208 char **ap, *inputstring; 209 210 inputstring = line; 211 for (ap = argv; ap < &argv[sizeof(argv) / sizeof(argv[0])] && 212 (*ap = stresep(&inputstring, " \t", '\\')) != NULL;) { 213 if (**ap != '\0') 214 ap++; 215 } 216 i = ap - argv; 217 if (i < 2) { 218 warnx("bad line: %s", line); 219 retval = 1; 220 continue; 221 } 222 if (set(i, argv)) 223 retval = 1; 224 } 225 if (fp != stdin) 226 (void)fclose(fp); 227 return retval; 228 } 229 230 static void 231 getsocket(void) 232 { 233 if (s >= 0) 234 return; 235 s = socket(PF_ROUTE, SOCK_RAW, 0); 236 if (s < 0) 237 err(1, "socket"); 238 } 239 240 /* 241 * Set an individual arp entry 242 */ 243 static int 244 set(int argc, char **argv) 245 { 246 struct sockaddr_inarp *sina; 247 struct sockaddr_dl *sdl; 248 struct rt_msghdr *rtm; 249 char *host = argv[0], *eaddr; 250 int rval; 251 252 sina = &sin_m; 253 rtm = &(m_rtmsg.m_rtm); 254 eaddr = argv[1]; 255 256 getsocket(); 257 argc -= 2; 258 argv += 2; 259 sdl_m = blank_sdl; /* struct copy */ 260 sin_m = blank_sin; /* struct copy */ 261 if (getinetaddr(host, &sina->sin_addr) == -1) 262 return (1); 263 if (atosdl(eaddr, &sdl_m)) 264 warnx("invalid link-level address '%s'", eaddr); 265 doing_proxy = flags = export_only = expire_time = 0; 266 while (argc-- > 0) { 267 if (strncmp(argv[0], "temp", 4) == 0) { 268 struct timeval timev; 269 (void)gettimeofday(&timev, 0); 270 expire_time = timev.tv_sec + 20 * 60; 271 } 272 else if (strncmp(argv[0], "pub", 3) == 0) { 273 flags |= RTF_ANNOUNCE; 274 doing_proxy = SIN_PROXY; 275 if (argc && strncmp(argv[1], "pro", 3) == 0) { 276 export_only = 1; 277 argc--; argv++; 278 } 279 } else if (strncmp(argv[0], "trail", 5) == 0) { 280 warnx("%s: Sending trailers is no longer supported", 281 host); 282 } 283 argv++; 284 } 285 tryagain: 286 if (rtmsg(RTM_GET) < 0) { 287 warn("%s", host); 288 return (1); 289 } 290 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 291 sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) + 292 (char *)(void *)sina); 293 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 294 if (is_llinfo(sdl, rtm->rtm_flags)) 295 goto overwrite; 296 if (doing_proxy == 0) { 297 warnx("set: can only proxy for %s", host); 298 return (1); 299 } 300 if (sin_m.sin_other & SIN_PROXY) { 301 warnx("set: proxy entry exists for non 802 device"); 302 return (1); 303 } 304 sin_m.sin_other = SIN_PROXY; 305 export_only = 1; 306 goto tryagain; 307 } 308 overwrite: 309 if (sdl->sdl_family != AF_LINK) { 310 warnx("cannot intuit interface index and type for %s", 311 host); 312 return (1); 313 } 314 sdl_m.sdl_type = sdl->sdl_type; 315 sdl_m.sdl_index = sdl->sdl_index; 316 rval = rtmsg(RTM_ADD); 317 if (vflag) 318 (void)printf("%s (%s) added\n", host, eaddr); 319 return (rval); 320 } 321 322 /* 323 * Display an individual arp entry 324 */ 325 static void 326 get(const char *host) 327 { 328 struct sockaddr_inarp *sina; 329 330 sina = &sin_m; 331 sin_m = blank_sin; /* struct copy */ 332 if (getinetaddr(host, &sina->sin_addr) == -1) 333 exit(1); 334 dump(sina->sin_addr.s_addr); 335 if (found_entry == 0) 336 errx(1, "%s (%s) -- no entry", host, inet_ntoa(sina->sin_addr)); 337 } 338 339 340 static int 341 is_llinfo(const struct sockaddr_dl *sdl, int rtflags) 342 { 343 if (sdl->sdl_family != AF_LINK || 344 (rtflags & (RTF_LLINFO|RTF_GATEWAY)) != RTF_LLINFO) 345 return 0; 346 347 switch (sdl->sdl_type) { 348 case IFT_ETHER: 349 case IFT_FDDI: 350 case IFT_ISO88023: 351 case IFT_ISO88024: 352 case IFT_ISO88025: 353 case IFT_ARCNET: 354 return 1; 355 default: 356 return 0; 357 } 358 } 359 360 /* 361 * Delete an arp entry 362 */ 363 int 364 delete(const char *host, const char *info) 365 { 366 struct sockaddr_inarp *sina; 367 struct rt_msghdr *rtm; 368 struct sockaddr_dl *sdl; 369 370 sina = &sin_m; 371 rtm = &m_rtmsg.m_rtm; 372 373 getsocket(); 374 sin_m = blank_sin; /* struct copy */ 375 if (info && strncmp(info, "pro", 3) == 0) 376 sina->sin_other = SIN_PROXY; 377 if (getinetaddr(host, &sina->sin_addr) == -1) 378 return (1); 379 tryagain: 380 if (rtmsg(RTM_GET) < 0) { 381 warn("%s", host); 382 return (1); 383 } 384 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 385 sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) + 386 (char *)(void *)sina); 387 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr && 388 is_llinfo(sdl, rtm->rtm_flags)) 389 goto delete; 390 if (sin_m.sin_other & SIN_PROXY) { 391 warnx("delete: can't locate %s", host); 392 return (1); 393 } else { 394 sin_m.sin_other = SIN_PROXY; 395 goto tryagain; 396 } 397 delete: 398 if (sdl->sdl_family != AF_LINK) { 399 (void)warnx("cannot locate %s", host); 400 return (1); 401 } 402 if (rtmsg(RTM_DELETE)) 403 return (1); 404 if (vflag) 405 (void)printf("%s (%s) deleted\n", host, 406 inet_ntoa(sina->sin_addr)); 407 return (0); 408 } 409 410 /* 411 * Dump the entire arp table 412 */ 413 void 414 dump(uint32_t addr) 415 { 416 int mib[6]; 417 size_t needed; 418 char ifname[IFNAMSIZ]; 419 char *lim, *buf, *next; 420 const char *host; 421 struct rt_msghdr *rtm; 422 struct sockaddr_inarp *sina; 423 struct sockaddr_dl *sdl; 424 struct hostent *hp; 425 426 mib[0] = CTL_NET; 427 mib[1] = PF_ROUTE; 428 mib[2] = 0; 429 mib[3] = AF_INET; 430 mib[4] = NET_RT_FLAGS; 431 mib[5] = RTF_LLINFO; 432 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 433 err(1, "route-sysctl-estimate"); 434 if (needed == 0) 435 return; 436 if ((buf = malloc(needed)) == NULL) 437 err(1, "malloc"); 438 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 439 err(1, "actual retrieval of routing table"); 440 lim = buf + needed; 441 for (next = buf; next < lim; next += rtm->rtm_msglen) { 442 rtm = (struct rt_msghdr *)(void *)next; 443 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 444 sdl = (struct sockaddr_dl *)(void *) 445 (RT_ROUNDUP(sina->sin_len) + (char *)(void *)sina); 446 if (addr) { 447 if (addr != sina->sin_addr.s_addr) 448 continue; 449 found_entry = 1; 450 } 451 if (nflag == 0) 452 hp = gethostbyaddr((const char *)(void *) 453 &(sina->sin_addr), 454 sizeof sina->sin_addr, AF_INET); 455 else 456 hp = NULL; 457 458 host = hp ? hp->h_name : "?"; 459 460 (void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr)); 461 if (sdl->sdl_alen) 462 sdl_print(sdl); 463 else 464 (void)printf("(incomplete)"); 465 466 if (sdl->sdl_index) { 467 if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0) 468 (void)printf(" on %s", ifname); 469 } 470 471 if (rtm->rtm_rmx.rmx_expire == 0) 472 (void)printf(" permanent"); 473 if (sina->sin_other & SIN_PROXY) 474 (void)printf(" published (proxy only)"); 475 if (rtm->rtm_addrs & RTA_NETMASK) { 476 sina = (struct sockaddr_inarp *)(void *) 477 (RT_ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl); 478 if (sina->sin_addr.s_addr == 0xffffffff) 479 (void)printf(" published"); 480 if (sina->sin_len != 8) 481 (void)printf("(weird)"); 482 } 483 (void)printf("\n"); 484 } 485 free(buf); 486 } 487 488 /* 489 * Delete the entire arp table 490 */ 491 void 492 delete_all(void) 493 { 494 int mib[6]; 495 size_t needed; 496 char addr[sizeof("000.000.000.000\0")]; 497 char *lim, *buf, *next; 498 struct rt_msghdr *rtm; 499 struct sockaddr_inarp *sina; 500 501 mib[0] = CTL_NET; 502 mib[1] = PF_ROUTE; 503 mib[2] = 0; 504 mib[3] = AF_INET; 505 mib[4] = NET_RT_FLAGS; 506 mib[5] = RTF_LLINFO; 507 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 508 err(1, "route-sysctl-estimate"); 509 if (needed == 0) 510 return; 511 if ((buf = malloc(needed)) == NULL) 512 err(1, "malloc"); 513 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 514 err(1, "actual retrieval of routing table"); 515 lim = buf + needed; 516 for (next = buf; next < lim; next += rtm->rtm_msglen) { 517 rtm = (struct rt_msghdr *)(void *)next; 518 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 519 (void)snprintf(addr, sizeof(addr), "%s", 520 inet_ntoa(sina->sin_addr)); 521 (void)delete(addr, NULL); 522 } 523 free(buf); 524 } 525 526 void 527 sdl_print(const struct sockaddr_dl *sdl) 528 { 529 char hbuf[NI_MAXHOST]; 530 531 if (getnameinfo((const struct sockaddr *)(const void *)sdl, 532 (socklen_t)sdl->sdl_len, 533 hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) 534 (void)printf("<invalid>"); 535 else 536 (void)printf("%s", hbuf); 537 } 538 539 static int 540 atosdl(const char *ss, struct sockaddr_dl *sdl) 541 { 542 int i; 543 unsigned long b; 544 char *endp; 545 char *p; 546 char *t, *r; 547 548 p = LLADDR(sdl); 549 endp = ((char *)(void *)sdl) + sdl->sdl_len; 550 i = 0; 551 552 b = strtoul(ss, &t, 16); 553 if (b > 255 || t == ss) 554 return 1; 555 556 *p++ = (char)b; 557 ++i; 558 while ((p < endp) && (*t++ == ':')) { 559 b = strtoul(t, &r, 16); 560 if (b > 255 || r == t) 561 break; 562 *p++ = (char)b; 563 ++i; 564 t = r; 565 } 566 sdl->sdl_alen = i; 567 568 return 0; 569 } 570 571 static void 572 usage(void) 573 { 574 const char *progname; 575 576 progname = getprogname(); 577 (void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname); 578 (void)fprintf(stderr, " %s [-nv] -a\n", progname); 579 (void)fprintf(stderr, " %s [-v] -d [-a|hostname [pub [proxy]]]\n", 580 progname); 581 (void)fprintf(stderr, " %s -s hostname ether_addr [temp] [pub [proxy]]\n", 582 progname); 583 (void)fprintf(stderr, " %s -f filename\n", progname); 584 exit(1); 585 } 586 587 static int 588 rtmsg(int cmd) 589 { 590 static int seq; 591 struct rt_msghdr *rtm; 592 char *cp; 593 int l; 594 595 rtm = &m_rtmsg.m_rtm; 596 cp = m_rtmsg.m_space; 597 errno = 0; 598 599 if (cmd == RTM_DELETE) 600 goto doit; 601 (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg)); 602 rtm->rtm_flags = flags; 603 rtm->rtm_version = RTM_VERSION; 604 605 switch (cmd) { 606 default: 607 errx(1, "internal wrong cmd"); 608 /*NOTREACHED*/ 609 case RTM_ADD: 610 rtm->rtm_addrs |= RTA_GATEWAY; 611 rtm->rtm_rmx.rmx_expire = expire_time; 612 rtm->rtm_inits = RTV_EXPIRE; 613 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 614 sin_m.sin_other = 0; 615 if (doing_proxy) { 616 if (export_only) 617 sin_m.sin_other = SIN_PROXY; 618 else { 619 rtm->rtm_addrs |= RTA_NETMASK; 620 rtm->rtm_flags &= ~RTF_HOST; 621 } 622 } 623 /* FALLTHROUGH */ 624 case RTM_GET: 625 rtm->rtm_addrs |= RTA_DST; 626 } 627 628 #define NEXTADDR(w, s) \ 629 if (rtm->rtm_addrs & (w)) { \ 630 (void)memcpy(cp, &s, \ 631 (size_t)((struct sockaddr *)(void *)&s)->sa_len); \ 632 RT_ADVANCE(cp, ((struct sockaddr *)(void *)&s)); \ 633 } 634 635 NEXTADDR(RTA_DST, sin_m); 636 NEXTADDR(RTA_GATEWAY, sdl_m); 637 NEXTADDR(RTA_NETMASK, so_mask); 638 639 rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg; 640 doit: 641 l = rtm->rtm_msglen; 642 rtm->rtm_seq = ++seq; 643 rtm->rtm_type = cmd; 644 if (write(s, &m_rtmsg, (size_t)l) < 0) { 645 if (errno != ESRCH || cmd != RTM_DELETE) { 646 warn("writing to routing socket"); 647 return (-1); 648 } 649 } 650 do { 651 l = read(s, &m_rtmsg, sizeof(m_rtmsg)); 652 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 653 if (l < 0) 654 warn("read from routing socket"); 655 return (0); 656 } 657 658 static int 659 getinetaddr(const char *host, struct in_addr *inap) 660 { 661 struct hostent *hp; 662 663 if (inet_aton(host, inap) == 1) 664 return (0); 665 if ((hp = gethostbyname(host)) == NULL) { 666 warnx("%s: %s", host, hstrerror(h_errno)); 667 return (-1); 668 } 669 (void)memcpy(inap, hp->h_addr, sizeof(*inap)); 670 return (0); 671 } 672 673 static int 674 getifname(u_int16_t ifindex, char *ifname, size_t l) 675 { 676 int i; 677 struct ifaddrs *addr; 678 const struct sockaddr_dl *sdl = NULL; 679 680 if (ifaddrs == NULL) { 681 i = getifaddrs(&ifaddrs); 682 if (i != 0) 683 err(1, "getifaddrs"); 684 } 685 686 for (addr = ifaddrs; addr; addr = addr->ifa_next) { 687 if (addr->ifa_addr == NULL || 688 addr->ifa_addr->sa_family != AF_LINK) 689 continue; 690 691 sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr; 692 if (sdl && sdl->sdl_index == ifindex) { 693 (void) strlcpy(ifname, addr->ifa_name, l); 694 return 0; 695 } 696 } 697 698 return -1; 699 } 700