arp.c revision 29060
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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#ifndef lint 38static char const copyright[] = 39"@(#) Copyright (c) 1984, 1993\n\ 40 The Regents of the University of California. All rights reserved.\n"; 41#endif /* not lint */ 42 43#ifndef lint 44#if 0 45static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; 46#endif 47static const char rcsid[] = 48 "$Id$"; 49#endif /* not lint */ 50 51/* 52 * arp - display, set, and delete arp table entries 53 */ 54 55 56#include <sys/param.h> 57#include <sys/file.h> 58#include <sys/socket.h> 59#include <sys/sockio.h> 60#include <sys/sysctl.h> 61#include <sys/ioctl.h> 62#include <sys/time.h> 63 64#include <net/if.h> 65#include <net/if_var.h> 66#include <net/if_dl.h> 67#include <net/if_types.h> 68#include <net/route.h> 69 70#include <netinet/in.h> 71#include <netinet/if_ether.h> 72 73#include <arpa/inet.h> 74 75#include <err.h> 76#include <errno.h> 77#include <netdb.h> 78#include <nlist.h> 79#include <paths.h> 80#include <stdio.h> 81#include <stdlib.h> 82#include <strings.h> 83#include <unistd.h> 84 85void dump(u_long addr); 86int delete(char *host, char *info); 87void ether_print(u_char *cp); 88void usage(void); 89int set(int argc, char **argv); 90void get(char *host); 91int file(char *name); 92void getsocket(void); 93int my_ether_aton(char *a, u_char *n); 94int rtmsg(int cmd); 95int get_ether_addr(u_long ipaddr, u_char *hwaddr); 96 97static int pid; 98static int nflag; 99static int s = -1; 100 101int 102main(argc, argv) 103 int argc; 104 char **argv; 105{ 106 int ch; 107 108 pid = getpid(); 109 while ((ch = getopt(argc, argv, "andfsS")) != -1) 110 switch((char)ch) { 111 case 'a': 112 dump(0); 113 exit(0); 114 case 'd': 115 if (argc < 3 || argc > 4) 116 usage(); 117 delete(argv[2], argv[3]); 118 exit(0); 119 case 'n': 120 nflag = 1; 121 continue; 122 case 'S': 123 delete(argv[2], NULL); 124 /* FALL THROUGH */ 125 case 's': 126 if (argc < 4 || argc > 7) 127 usage(); 128 exit(set(argc-2, &argv[2]) ? 1 : 0); 129 case 'f' : 130 if (argc != 3) 131 usage(); 132 return (file(argv[2])); 133 case '?': 134 default: 135 usage(); 136 } 137 if (argc != 2) 138 usage(); 139 get(argv[1]); 140 exit(0); 141} 142 143/* 144 * Process a file to set standard arp entries 145 */ 146int 147file(char *name) 148{ 149 FILE *fp; 150 int i, retval; 151 char line[100], arg[5][50], *args[5]; 152 153 if ((fp = fopen(name, "r")) == NULL) 154 errx(1, "cannot open %s", name); 155 args[0] = &arg[0][0]; 156 args[1] = &arg[1][0]; 157 args[2] = &arg[2][0]; 158 args[3] = &arg[3][0]; 159 args[4] = &arg[4][0]; 160 retval = 0; 161 while(fgets(line, 100, fp) != NULL) { 162 i = sscanf(line, "%s %s %s %s %s", arg[0], arg[1], arg[2], 163 arg[3], arg[4]); 164 if (i < 2) { 165 warnx("bad line: %s", line); 166 retval = 1; 167 continue; 168 } 169 if (set(i, args)) 170 retval = 1; 171 } 172 fclose(fp); 173 return (retval); 174} 175 176void 177getsocket(void) 178{ 179 if (s < 0) { 180 s = socket(PF_ROUTE, SOCK_RAW, 0); 181 if (s < 0) 182 err(1, "socket"); 183 } 184} 185 186struct sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}}; 187struct sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m; 188struct sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m; 189int expire_time, flags, export_only, doing_proxy, found_entry; 190struct { 191 struct rt_msghdr m_rtm; 192 char m_space[512]; 193} m_rtmsg; 194 195/* 196 * Set an individual arp entry 197 */ 198int 199set(int argc, char **argv) 200{ 201 struct hostent *hp; 202 register struct sockaddr_inarp *sin = &sin_m; 203 register struct sockaddr_dl *sdl; 204 register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm); 205 u_char *ea; 206 char *host = argv[0], *eaddr = argv[1]; 207 208 getsocket(); 209 argc -= 2; 210 argv += 2; 211 sdl_m = blank_sdl; 212 sin_m = blank_sin; 213 sin->sin_addr.s_addr = inet_addr(host); 214 if (sin->sin_addr.s_addr == -1) { 215 if (!(hp = gethostbyname(host))) { 216 warnx("%s: %s", host, hstrerror(h_errno)); 217 return (1); 218 } 219 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 220 sizeof sin->sin_addr); 221 } 222 doing_proxy = flags = export_only = expire_time = 0; 223 while (argc-- > 0) { 224 if (strncmp(argv[0], "temp", 4) == 0) { 225 struct timeval time; 226 gettimeofday(&time, 0); 227 expire_time = time.tv_sec + 20 * 60; 228 } 229 else if (strncmp(argv[0], "pub", 3) == 0) { 230 flags |= RTF_ANNOUNCE; 231 doing_proxy = SIN_PROXY; 232 } else if (strncmp(argv[0], "trail", 5) == 0) { 233 printf("%s: Sending trailers is no longer supported\n", 234 host); 235 } 236 argv++; 237 } 238 ea = (u_char *)LLADDR(&sdl_m); 239 if (doing_proxy && !strcmp(eaddr, "auto")) { 240 if (!get_ether_addr(sin->sin_addr.s_addr, ea)) { 241 return (1); 242 } 243 sdl_m.sdl_alen = 6; 244 } else { 245 if (my_ether_aton(eaddr, ea) == 0) 246 sdl_m.sdl_alen = 6; 247 } 248tryagain: 249 if (rtmsg(RTM_GET) < 0) { 250 warn("%s", host); 251 return (1); 252 } 253 sin = (struct sockaddr_inarp *)(rtm + 1); 254 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 255 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 256 if (sdl->sdl_family == AF_LINK && 257 (rtm->rtm_flags & RTF_LLINFO) && 258 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 259 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 260 case IFT_ISO88024: case IFT_ISO88025: 261 goto overwrite; 262 } 263 if (doing_proxy == 0) { 264 printf("set: can only proxy for %s\n", host); 265 return (1); 266 } 267 if (sin_m.sin_other & SIN_PROXY) { 268 printf("set: proxy entry exists for non 802 device\n"); 269 return(1); 270 } 271 sin_m.sin_other = SIN_PROXY; 272 export_only = 1; 273 goto tryagain; 274 } 275overwrite: 276 if (sdl->sdl_family != AF_LINK) { 277 printf("cannot intuit interface index and type for %s\n", host); 278 return (1); 279 } 280 sdl_m.sdl_type = sdl->sdl_type; 281 sdl_m.sdl_index = sdl->sdl_index; 282 return (rtmsg(RTM_ADD)); 283} 284 285/* 286 * Display an individual arp entry 287 */ 288void 289get(char *host) 290{ 291 struct hostent *hp; 292 struct sockaddr_inarp *sin = &sin_m; 293 294 sin_m = blank_sin; 295 sin->sin_addr.s_addr = inet_addr(host); 296 if (sin->sin_addr.s_addr == -1) { 297 if (!(hp = gethostbyname(host))) 298 errx(1, "%s: %s", host, hstrerror(h_errno)); 299 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 300 sizeof sin->sin_addr); 301 } 302 dump(sin->sin_addr.s_addr); 303 if (found_entry == 0) { 304 printf("%s (%s) -- no entry\n", 305 host, inet_ntoa(sin->sin_addr)); 306 exit(1); 307 } 308} 309 310/* 311 * Delete an arp entry 312 */ 313int 314delete(char *host, char *info) 315{ 316 struct hostent *hp; 317 register struct sockaddr_inarp *sin = &sin_m; 318 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 319 struct sockaddr_dl *sdl; 320 321 if (info && strncmp(info, "pro", 3) ) 322 export_only = 1; 323 getsocket(); 324 sin_m = blank_sin; 325 sin->sin_addr.s_addr = inet_addr(host); 326 if (sin->sin_addr.s_addr == -1) { 327 if (!(hp = gethostbyname(host))) { 328 warnx("%s: %s", host, hstrerror(h_errno)); 329 return (1); 330 } 331 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 332 sizeof sin->sin_addr); 333 } 334tryagain: 335 if (rtmsg(RTM_GET) < 0) { 336 warn("%s", host); 337 return (1); 338 } 339 sin = (struct sockaddr_inarp *)(rtm + 1); 340 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 341 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 342 if (sdl->sdl_family == AF_LINK && 343 (rtm->rtm_flags & RTF_LLINFO) && 344 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 345 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 346 case IFT_ISO88024: case IFT_ISO88025: 347 goto delete; 348 } 349 } 350 if (sin_m.sin_other & SIN_PROXY) { 351 fprintf(stderr, "delete: can't locate %s\n",host); 352 return (1); 353 } else { 354 sin_m.sin_other = SIN_PROXY; 355 goto tryagain; 356 } 357delete: 358 if (sdl->sdl_family != AF_LINK) { 359 printf("cannot locate %s\n", host); 360 return (1); 361 } 362 if (rtmsg(RTM_DELETE) == 0) { 363 printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr)); 364 return (0); 365 } 366 return (1); 367} 368 369/* 370 * Dump the entire arp table 371 */ 372void 373dump(u_long addr) 374{ 375 int mib[6]; 376 size_t needed; 377 char *host, *lim, *buf, *next; 378 struct rt_msghdr *rtm; 379 struct sockaddr_inarp *sin; 380 struct sockaddr_dl *sdl; 381 extern int h_errno; 382 struct hostent *hp; 383 384 mib[0] = CTL_NET; 385 mib[1] = PF_ROUTE; 386 mib[2] = 0; 387 mib[3] = AF_INET; 388 mib[4] = NET_RT_FLAGS; 389 mib[5] = RTF_LLINFO; 390 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 391 errx(1, "route-sysctl-estimate"); 392 if ((buf = malloc(needed)) == NULL) 393 errx(1, "malloc"); 394 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 395 errx(1, "actual retrieval of routing table"); 396 lim = buf + needed; 397 for (next = buf; next < lim; next += rtm->rtm_msglen) { 398 rtm = (struct rt_msghdr *)next; 399 sin = (struct sockaddr_inarp *)(rtm + 1); 400 sdl = (struct sockaddr_dl *)(sin + 1); 401 if (addr) { 402 if (addr != sin->sin_addr.s_addr) 403 continue; 404 found_entry = 1; 405 } 406 if (nflag == 0) 407 hp = gethostbyaddr((caddr_t)&(sin->sin_addr), 408 sizeof sin->sin_addr, AF_INET); 409 else 410 hp = 0; 411 if (hp) 412 host = hp->h_name; 413 else { 414 host = "?"; 415 if (h_errno == TRY_AGAIN) 416 nflag = 1; 417 } 418 printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr)); 419 if (sdl->sdl_alen) 420 ether_print(LLADDR(sdl)); 421 else 422 printf("(incomplete)"); 423 if (rtm->rtm_rmx.rmx_expire == 0) 424 printf(" permanent"); 425 if (sin->sin_other & SIN_PROXY) 426 printf(" published (proxy only)"); 427 if (rtm->rtm_addrs & RTA_NETMASK) { 428 sin = (struct sockaddr_inarp *) 429 (sdl->sdl_len + (char *)sdl); 430 if (sin->sin_addr.s_addr == 0xffffffff) 431 printf(" published"); 432 if (sin->sin_len != 8) 433 printf("(wierd)"); 434 } 435 printf("\n"); 436 } 437} 438 439void 440ether_print(u_char *cp) 441{ 442 printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]); 443} 444 445int 446my_ether_aton(char *a, u_char *n) 447{ 448 int i, o[6]; 449 450 i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2], 451 &o[3], &o[4], &o[5]); 452 if (i != 6) { 453 warnx("invalid Ethernet address '%s'", a); 454 return (1); 455 } 456 for (i=0; i<6; i++) 457 n[i] = o[i]; 458 return (0); 459} 460 461void 462usage(void) 463{ 464 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n", 465 "usage: arp [-n] hostname", 466 " arp [-n] -a [kernel] [kernel_memory]", 467 " arp -d hostname", 468 " arp -s hostname ether_addr [temp] [pub]", 469 " arp -S hostname ether_addr [temp] [pub]", 470 " arp -f filename"); 471 exit(1); 472} 473 474int 475rtmsg(int cmd) 476{ 477 static int seq; 478 int rlen; 479 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 480 register char *cp = m_rtmsg.m_space; 481 register int l; 482 483 errno = 0; 484 if (cmd == RTM_DELETE) 485 goto doit; 486 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 487 rtm->rtm_flags = flags; 488 rtm->rtm_version = RTM_VERSION; 489 490 switch (cmd) { 491 default: 492 errx(1, "internal wrong cmd"); 493 case RTM_ADD: 494 rtm->rtm_addrs |= RTA_GATEWAY; 495 rtm->rtm_rmx.rmx_expire = expire_time; 496 rtm->rtm_inits = RTV_EXPIRE; 497 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 498 sin_m.sin_other = 0; 499 if (doing_proxy) { 500 if (export_only) 501 sin_m.sin_other = SIN_PROXY; 502 else { 503 rtm->rtm_addrs |= RTA_NETMASK; 504 rtm->rtm_flags &= ~RTF_HOST; 505 } 506 } 507 /* FALLTHROUGH */ 508 case RTM_GET: 509 rtm->rtm_addrs |= RTA_DST; 510 } 511#define NEXTADDR(w, s) \ 512 if (rtm->rtm_addrs & (w)) { \ 513 bcopy((char *)&s, cp, sizeof(s)); cp += sizeof(s);} 514 515 NEXTADDR(RTA_DST, sin_m); 516 NEXTADDR(RTA_GATEWAY, sdl_m); 517 NEXTADDR(RTA_NETMASK, so_mask); 518 519 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 520doit: 521 l = rtm->rtm_msglen; 522 rtm->rtm_seq = ++seq; 523 rtm->rtm_type = cmd; 524 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 525 if (errno != ESRCH || cmd != RTM_DELETE) { 526 warn("writing to routing socket"); 527 return (-1); 528 } 529 } 530 do { 531 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 532 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 533 if (l < 0) 534 warn("read from routing socket"); 535 return (0); 536} 537 538/* 539 * get_ether_addr - get the hardware address of an interface on the 540 * the same subnet as ipaddr. 541 */ 542#define MAX_IFS 32 543 544int 545get_ether_addr(u_long ipaddr, u_char *hwaddr) 546{ 547 struct ifreq *ifr, *ifend, *ifp; 548 u_long ina, mask; 549 struct sockaddr_dl *dla; 550 struct ifreq ifreq; 551 struct ifconf ifc; 552 struct ifreq ifs[MAX_IFS]; 553 int s; 554 555 s = socket(AF_INET, SOCK_DGRAM, 0); 556 if (s < 0) 557 err(1, "socket"); 558 559 ifc.ifc_len = sizeof(ifs); 560 ifc.ifc_req = ifs; 561 if (ioctl(s, SIOCGIFCONF, &ifc) < 0) { 562 warnx("ioctl(SIOCGIFCONF)"); 563 close(s); 564 return 0; 565 } 566 567 /* 568 * Scan through looking for an interface with an Internet 569 * address on the same subnet as `ipaddr'. 570 */ 571 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len); 572 for (ifr = ifc.ifc_req; ifr < ifend; ) { 573 if (ifr->ifr_addr.sa_family == AF_INET) { 574 ina = ((struct sockaddr_in *) 575 &ifr->ifr_addr)->sin_addr.s_addr; 576 strncpy(ifreq.ifr_name, ifr->ifr_name, 577 sizeof(ifreq.ifr_name)); 578 /* 579 * Check that the interface is up, 580 * and not point-to-point or loopback. 581 */ 582 if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0) 583 continue; 584 if ((ifreq.ifr_flags & 585 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 586 IFF_LOOPBACK|IFF_NOARP)) 587 != (IFF_UP|IFF_BROADCAST)) 588 goto nextif; 589 /* 590 * Get its netmask and check that it's on 591 * the right subnet. 592 */ 593 if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0) 594 continue; 595 mask = ((struct sockaddr_in *) 596 &ifreq.ifr_addr)->sin_addr.s_addr; 597 if ((ipaddr & mask) != (ina & mask)) 598 goto nextif; 599 break; 600 } 601nextif: 602 ifr = (struct ifreq *) 603 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 604 } 605 606 if (ifr >= ifend) { 607 close(s); 608 return 0; 609 } 610 611 /* 612 * Now scan through again looking for a link-level address 613 * for this interface. 614 */ 615 ifp = ifr; 616 for (ifr = ifc.ifc_req; ifr < ifend; ) { 617 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 618 && ifr->ifr_addr.sa_family == AF_LINK) { 619 /* 620 * Found the link-level address - copy it out 621 */ 622 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 623 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 624 close (s); 625 printf("using interface %s for proxy with address ", 626 ifp->ifr_name); 627 ether_print(hwaddr); 628 printf("\n"); 629 return dla->sdl_alen; 630 } 631 ifr = (struct ifreq *) 632 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 633 } 634 return 0; 635} 636