arp.c revision 1.45
1 /* $NetBSD: arp.c,v 1.45 2007/12/15 19:44:54 perry 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\n\ 38 The Regents of the University of California. All rights reserved.\n"); 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 1.45 2007/12/15 19:44:54 perry 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 } else if (strncmp(argv[0], "trail", 5) == 0) { 273 warnx("%s: Sending trailers is no longer supported", 274 host); 275 } 276 argv++; 277 } 278 tryagain: 279 if (rtmsg(RTM_GET) < 0) { 280 warn("%s", host); 281 return (1); 282 } 283 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 284 sdl = (struct sockaddr_dl *)(void *)(ROUNDUP(sina->sin_len) + 285 (char *)(void *)sina); 286 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 287 if (is_llinfo(sdl, rtm->rtm_flags)) 288 goto overwrite; 289 if (doing_proxy == 0) { 290 warnx("set: can only proxy for %s", host); 291 return (1); 292 } 293 if (sin_m.sin_other & SIN_PROXY) { 294 warnx("set: proxy entry exists for non 802 device"); 295 return (1); 296 } 297 sin_m.sin_other = SIN_PROXY; 298 export_only = 1; 299 goto tryagain; 300 } 301 overwrite: 302 if (sdl->sdl_family != AF_LINK) { 303 warnx("cannot intuit interface index and type for %s", 304 host); 305 return (1); 306 } 307 sdl_m.sdl_type = sdl->sdl_type; 308 sdl_m.sdl_index = sdl->sdl_index; 309 rval = rtmsg(RTM_ADD); 310 if (vflag) 311 (void)printf("%s (%s) added\n", host, eaddr); 312 return (rval); 313 } 314 315 /* 316 * Display an individual arp entry 317 */ 318 static void 319 get(const char *host) 320 { 321 struct sockaddr_inarp *sina; 322 323 sina = &sin_m; 324 sin_m = blank_sin; /* struct copy */ 325 if (getinetaddr(host, &sina->sin_addr) == -1) 326 exit(1); 327 dump(sina->sin_addr.s_addr); 328 if (found_entry == 0) 329 errx(1, "%s (%s) -- no entry", host, inet_ntoa(sina->sin_addr)); 330 } 331 332 333 static int 334 is_llinfo(const struct sockaddr_dl *sdl, int rtflags) 335 { 336 if (sdl->sdl_family != AF_LINK || 337 (rtflags & (RTF_LLINFO|RTF_GATEWAY)) != RTF_LLINFO) 338 return 0; 339 340 switch (sdl->sdl_type) { 341 case IFT_ETHER: 342 case IFT_FDDI: 343 case IFT_ISO88023: 344 case IFT_ISO88024: 345 case IFT_ISO88025: 346 case IFT_ARCNET: 347 return 1; 348 default: 349 return 0; 350 } 351 } 352 353 /* 354 * Delete an arp entry 355 */ 356 int 357 delete(const char *host, const char *info) 358 { 359 struct sockaddr_inarp *sina; 360 struct rt_msghdr *rtm; 361 struct sockaddr_dl *sdl; 362 363 sina = &sin_m; 364 rtm = &m_rtmsg.m_rtm; 365 366 if (info && strncmp(info, "pub", 3) == 0) 367 export_only = 1; 368 getsocket(); 369 sin_m = blank_sin; /* struct copy */ 370 if (getinetaddr(host, &sina->sin_addr) == -1) 371 return (1); 372 tryagain: 373 if (rtmsg(RTM_GET) < 0) { 374 warn("%s", host); 375 return (1); 376 } 377 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 378 sdl = (struct sockaddr_dl *)(void *)(ROUNDUP(sina->sin_len) + 379 (char *)(void *)sina); 380 if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr && 381 is_llinfo(sdl, rtm->rtm_flags)) 382 goto delete; 383 if (sin_m.sin_other & SIN_PROXY) { 384 warnx("delete: can't locate %s", host); 385 return (1); 386 } else { 387 sin_m.sin_other = SIN_PROXY; 388 goto tryagain; 389 } 390 delete: 391 if (sdl->sdl_family != AF_LINK) { 392 (void)warnx("cannot locate %s", host); 393 return (1); 394 } 395 if (rtmsg(RTM_DELETE)) 396 return (1); 397 if (vflag) 398 (void)printf("%s (%s) deleted\n", host, 399 inet_ntoa(sina->sin_addr)); 400 return (0); 401 } 402 403 /* 404 * Dump the entire arp table 405 */ 406 void 407 dump(uint32_t addr) 408 { 409 int mib[6]; 410 size_t needed; 411 char ifname[IFNAMSIZ]; 412 char *lim, *buf, *next; 413 const char *host; 414 struct rt_msghdr *rtm; 415 struct sockaddr_inarp *sina; 416 struct sockaddr_dl *sdl; 417 struct hostent *hp; 418 419 mib[0] = CTL_NET; 420 mib[1] = PF_ROUTE; 421 mib[2] = 0; 422 mib[3] = AF_INET; 423 mib[4] = NET_RT_FLAGS; 424 mib[5] = RTF_LLINFO; 425 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 426 err(1, "route-sysctl-estimate"); 427 if (needed == 0) 428 return; 429 if ((buf = malloc(needed)) == NULL) 430 err(1, "malloc"); 431 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 432 err(1, "actual retrieval of routing table"); 433 lim = buf + needed; 434 for (next = buf; next < lim; next += rtm->rtm_msglen) { 435 rtm = (struct rt_msghdr *)(void *)next; 436 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 437 sdl = (struct sockaddr_dl *)(void *) 438 (ROUNDUP(sina->sin_len) + (char *)(void *)sina); 439 if (addr) { 440 if (addr != sina->sin_addr.s_addr) 441 continue; 442 found_entry = 1; 443 } 444 if (nflag == 0) 445 hp = gethostbyaddr((const char *)(void *) 446 &(sina->sin_addr), 447 sizeof sina->sin_addr, AF_INET); 448 else 449 hp = NULL; 450 451 host = hp ? hp->h_name : "?"; 452 453 (void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr)); 454 if (sdl->sdl_alen) 455 sdl_print(sdl); 456 else 457 (void)printf("(incomplete)"); 458 459 if (sdl->sdl_index) { 460 if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0) 461 (void)printf(" on %s", ifname); 462 } 463 464 if (rtm->rtm_rmx.rmx_expire == 0) 465 (void)printf(" permanent"); 466 if (sina->sin_other & SIN_PROXY) 467 (void)printf(" published (proxy only)"); 468 if (rtm->rtm_addrs & RTA_NETMASK) { 469 sina = (struct sockaddr_inarp *)(void *) 470 (ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl); 471 if (sina->sin_addr.s_addr == 0xffffffff) 472 (void)printf(" published"); 473 if (sina->sin_len != 8) 474 (void)printf("(weird)"); 475 } 476 (void)printf("\n"); 477 } 478 free(buf); 479 } 480 481 /* 482 * Delete the entire arp table 483 */ 484 void 485 delete_all(void) 486 { 487 int mib[6]; 488 size_t needed; 489 char addr[sizeof("000.000.000.000\0")]; 490 char *lim, *buf, *next; 491 struct rt_msghdr *rtm; 492 struct sockaddr_inarp *sina; 493 494 mib[0] = CTL_NET; 495 mib[1] = PF_ROUTE; 496 mib[2] = 0; 497 mib[3] = AF_INET; 498 mib[4] = NET_RT_FLAGS; 499 mib[5] = RTF_LLINFO; 500 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 501 err(1, "route-sysctl-estimate"); 502 if (needed == 0) 503 return; 504 if ((buf = malloc(needed)) == NULL) 505 err(1, "malloc"); 506 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 507 err(1, "actual retrieval of routing table"); 508 lim = buf + needed; 509 for (next = buf; next < lim; next += rtm->rtm_msglen) { 510 rtm = (struct rt_msghdr *)(void *)next; 511 sina = (struct sockaddr_inarp *)(void *)(rtm + 1); 512 (void)snprintf(addr, sizeof(addr), "%s", 513 inet_ntoa(sina->sin_addr)); 514 (void)delete(addr, NULL); 515 } 516 free(buf); 517 } 518 519 void 520 sdl_print(const struct sockaddr_dl *sdl) 521 { 522 char hbuf[NI_MAXHOST]; 523 524 if (getnameinfo((const struct sockaddr *)(const void *)sdl, 525 (socklen_t)sdl->sdl_len, 526 hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) 527 (void)printf("<invalid>"); 528 else 529 (void)printf("%s", hbuf); 530 } 531 532 static int 533 atosdl(const char *ss, struct sockaddr_dl *sdl) 534 { 535 int i; 536 unsigned long b; 537 char *endp; 538 char *p; 539 char *t, *r; 540 541 p = LLADDR(sdl); 542 endp = ((char *)(void *)sdl) + sdl->sdl_len; 543 i = 0; 544 545 b = strtoul(ss, &t, 16); 546 if (b > 255 || t == ss) 547 return 1; 548 549 *p++ = (char)b; 550 ++i; 551 while ((p < endp) && (*t++ == ':')) { 552 b = strtoul(t, &r, 16); 553 if (b > 255 || r == t) 554 break; 555 *p++ = (char)b; 556 ++i; 557 t = r; 558 } 559 sdl->sdl_alen = i; 560 561 return 0; 562 } 563 564 static void 565 usage(void) 566 { 567 const char *progname; 568 569 progname = getprogname(); 570 (void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname); 571 (void)fprintf(stderr, " %s [-nv] -a\n", progname); 572 (void)fprintf(stderr, " %s [-v] -d [-a|hostname [pub]]\n", 573 progname); 574 (void)fprintf(stderr, " %s -s hostname ether_addr [temp] [pub]\n", 575 progname); 576 (void)fprintf(stderr, " %s -f filename\n", progname); 577 exit(1); 578 } 579 580 static int 581 rtmsg(int cmd) 582 { 583 static int seq; 584 struct rt_msghdr *rtm; 585 char *cp; 586 int l; 587 588 rtm = &m_rtmsg.m_rtm; 589 cp = m_rtmsg.m_space; 590 errno = 0; 591 592 if (cmd == RTM_DELETE) 593 goto doit; 594 (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg)); 595 rtm->rtm_flags = flags; 596 rtm->rtm_version = RTM_VERSION; 597 598 switch (cmd) { 599 default: 600 errx(1, "internal wrong cmd"); 601 /*NOTREACHED*/ 602 case RTM_ADD: 603 rtm->rtm_addrs |= RTA_GATEWAY; 604 rtm->rtm_rmx.rmx_expire = expire_time; 605 rtm->rtm_inits = RTV_EXPIRE; 606 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 607 sin_m.sin_other = 0; 608 if (doing_proxy) { 609 if (export_only) 610 sin_m.sin_other = SIN_PROXY; 611 else { 612 rtm->rtm_addrs |= RTA_NETMASK; 613 rtm->rtm_flags &= ~RTF_HOST; 614 } 615 } 616 /* FALLTHROUGH */ 617 case RTM_GET: 618 rtm->rtm_addrs |= RTA_DST; 619 } 620 621 #define NEXTADDR(w, s) \ 622 if (rtm->rtm_addrs & (w)) { \ 623 (void)memcpy(cp, &s, \ 624 (size_t)((struct sockaddr *)(void *)&s)->sa_len); \ 625 cp += ROUNDUP(((struct sockaddr *)(void *)&s)->sa_len); \ 626 } 627 628 NEXTADDR(RTA_DST, sin_m); 629 NEXTADDR(RTA_GATEWAY, sdl_m); 630 NEXTADDR(RTA_NETMASK, so_mask); 631 632 rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg; 633 doit: 634 l = rtm->rtm_msglen; 635 rtm->rtm_seq = ++seq; 636 rtm->rtm_type = cmd; 637 if (write(s, &m_rtmsg, (size_t)l) < 0) { 638 if (errno != ESRCH || cmd != RTM_DELETE) { 639 warn("writing to routing socket"); 640 return (-1); 641 } 642 } 643 do { 644 l = read(s, &m_rtmsg, sizeof(m_rtmsg)); 645 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 646 if (l < 0) 647 warn("read from routing socket"); 648 return (0); 649 } 650 651 static int 652 getinetaddr(const char *host, struct in_addr *inap) 653 { 654 struct hostent *hp; 655 656 if (inet_aton(host, inap) == 1) 657 return (0); 658 if ((hp = gethostbyname(host)) == NULL) { 659 warnx("%s: %s", host, hstrerror(h_errno)); 660 return (-1); 661 } 662 (void)memcpy(inap, hp->h_addr, sizeof(*inap)); 663 return (0); 664 } 665 666 static int 667 getifname(u_int16_t ifindex, char *ifname, size_t l) 668 { 669 int i; 670 struct ifaddrs *addr; 671 const struct sockaddr_dl *sdl = NULL; 672 673 if (ifaddrs == NULL) { 674 i = getifaddrs(&ifaddrs); 675 if (i != 0) 676 err(1, "getifaddrs"); 677 } 678 679 for (addr = ifaddrs; addr; addr = addr->ifa_next) { 680 if (addr->ifa_addr == NULL || 681 addr->ifa_addr->sa_family != AF_LINK) 682 continue; 683 684 sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr; 685 if (sdl && sdl->sdl_index == ifindex) { 686 (void) strlcpy(ifname, addr->ifa_name, l); 687 return 0; 688 } 689 } 690 691 return -1; 692 } 693
Indexes created Tue Sep 30 20:09:53 GMT 2025