arp.c revision 22997
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 44static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; 45static char const freebsdid[] = "$Id$"; 46#endif /* not lint */ 47 48/* 49 * arp - display, set, and delete arp table entries 50 */ 51 52 53#include <sys/param.h> 54#include <sys/file.h> 55#include <sys/socket.h> 56#include <sys/sockio.h> 57#include <sys/sysctl.h> 58#include <sys/ioctl.h> 59#include <sys/time.h> 60 61#include <net/if.h> 62#include <net/if_var.h> 63#include <net/if_dl.h> 64#include <net/if_types.h> 65#include <net/route.h> 66 67#include <netinet/in.h> 68#include <netinet/if_ether.h> 69 70#include <arpa/inet.h> 71 72#include <netdb.h> 73#include <errno.h> 74#include <nlist.h> 75#include <stdio.h> 76#include <stdlib.h> 77#include <unistd.h> 78#include <strings.h> 79#include <paths.h> 80 81void dump(u_long addr); 82int delete(char *host, char *info); 83void ether_print(u_char *cp); 84void usage(void); 85int set(int argc, char **argv); 86void get(char *host); 87int file(char *name); 88void getsocket(void); 89int my_ether_aton(char *a, u_char *n); 90int rtmsg(int cmd); 91void quit(char *msg); 92int get_ether_addr(u_long ipaddr, u_char *hwaddr); 93 94static int pid; 95static int nflag; 96static int s = -1; 97 98int 99main(argc, argv) 100 int argc; 101 char **argv; 102{ 103 int ch; 104 105 pid = getpid(); 106 while ((ch = getopt(argc, argv, "andfsS")) != EOF) 107 switch((char)ch) { 108 case 'a': 109 dump(0); 110 exit(0); 111 case 'd': 112 if (argc < 3 || argc > 4) 113 usage(); 114 delete(argv[2], argv[3]); 115 exit(0); 116 case 'n': 117 nflag = 1; 118 continue; 119 case 'S': 120 delete(argv[2], NULL); 121 /* FALL THROUGH */ 122 case 's': 123 if (argc < 4 || argc > 7) 124 usage(); 125 exit(set(argc-2, &argv[2]) ? 1 : 0); 126 case 'f' : 127 if (argc != 3) 128 usage(); 129 return (file(argv[2])); 130 case '?': 131 default: 132 usage(); 133 } 134 if (argc != 2) 135 usage(); 136 get(argv[1]); 137 exit(0); 138} 139 140/* 141 * Process a file to set standard arp entries 142 */ 143int 144file(char *name) 145{ 146 FILE *fp; 147 int i, retval; 148 char line[100], arg[5][50], *args[5]; 149 150 if ((fp = fopen(name, "r")) == NULL) { 151 fprintf(stderr, "arp: cannot open %s\n", name); 152 exit(1); 153 } 154 args[0] = &arg[0][0]; 155 args[1] = &arg[1][0]; 156 args[2] = &arg[2][0]; 157 args[3] = &arg[3][0]; 158 args[4] = &arg[4][0]; 159 retval = 0; 160 while(fgets(line, 100, fp) != NULL) { 161 i = sscanf(line, "%s %s %s %s %s", arg[0], arg[1], arg[2], 162 arg[3], arg[4]); 163 if (i < 2) { 164 fprintf(stderr, "arp: bad line: %s\n", line); 165 retval = 1; 166 continue; 167 } 168 if (set(i, args)) 169 retval = 1; 170 } 171 fclose(fp); 172 return (retval); 173} 174 175void 176getsocket(void) 177{ 178 if (s < 0) { 179 s = socket(PF_ROUTE, SOCK_RAW, 0); 180 if (s < 0) { 181 perror("arp: socket"); 182 exit(1); 183 } 184 } 185} 186 187struct sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}}; 188struct sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m; 189struct sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m; 190int expire_time, flags, export_only, doing_proxy, found_entry; 191struct { 192 struct rt_msghdr m_rtm; 193 char m_space[512]; 194} m_rtmsg; 195 196/* 197 * Set an individual arp entry 198 */ 199int 200set(int argc, char **argv) 201{ 202 struct hostent *hp; 203 register struct sockaddr_inarp *sin = &sin_m; 204 register struct sockaddr_dl *sdl; 205 register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm); 206 u_char *ea; 207 char *host = argv[0], *eaddr = argv[1]; 208 209 getsocket(); 210 argc -= 2; 211 argv += 2; 212 sdl_m = blank_sdl; 213 sin_m = blank_sin; 214 sin->sin_addr.s_addr = inet_addr(host); 215 if (sin->sin_addr.s_addr == -1) { 216 if (!(hp = gethostbyname(host))) { 217 fprintf(stderr, "arp: %s: ", host); 218 herror((char *)NULL); 219 return (1); 220 } 221 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 222 sizeof sin->sin_addr); 223 } 224 doing_proxy = flags = export_only = expire_time = 0; 225 while (argc-- > 0) { 226 if (strncmp(argv[0], "temp", 4) == 0) { 227 struct timeval time; 228 gettimeofday(&time, 0); 229 expire_time = time.tv_sec + 20 * 60; 230 } 231 else if (strncmp(argv[0], "pub", 3) == 0) { 232 flags |= RTF_ANNOUNCE; 233 doing_proxy = SIN_PROXY; 234 } else if (strncmp(argv[0], "trail", 5) == 0) { 235 printf("%s: Sending trailers is no longer supported\n", 236 host); 237 } 238 argv++; 239 } 240 ea = (u_char *)LLADDR(&sdl_m); 241 if (doing_proxy && !strcmp(eaddr, "auto")) { 242 if (!get_ether_addr(sin->sin_addr.s_addr, ea)) { 243 return (1); 244 } 245 sdl_m.sdl_alen = 6; 246 } else { 247 if (my_ether_aton(eaddr, ea) == 0) 248 sdl_m.sdl_alen = 6; 249 } 250tryagain: 251 if (rtmsg(RTM_GET) < 0) { 252 perror(host); 253 return (1); 254 } 255 sin = (struct sockaddr_inarp *)(rtm + 1); 256 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 257 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 258 if (sdl->sdl_family == AF_LINK && 259 (rtm->rtm_flags & RTF_LLINFO) && 260 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 261 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 262 case IFT_ISO88024: case IFT_ISO88025: 263 goto overwrite; 264 } 265 if (doing_proxy == 0) { 266 printf("set: can only proxy for %s\n", host); 267 return (1); 268 } 269 if (sin_m.sin_other & SIN_PROXY) { 270 printf("set: proxy entry exists for non 802 device\n"); 271 return(1); 272 } 273 sin_m.sin_other = SIN_PROXY; 274 export_only = 1; 275 goto tryagain; 276 } 277overwrite: 278 if (sdl->sdl_family != AF_LINK) { 279 printf("cannot intuit interface index and type for %s\n", host); 280 return (1); 281 } 282 sdl_m.sdl_type = sdl->sdl_type; 283 sdl_m.sdl_index = sdl->sdl_index; 284 return (rtmsg(RTM_ADD)); 285} 286 287/* 288 * Display an individual arp entry 289 */ 290void 291get(char *host) 292{ 293 struct hostent *hp; 294 struct sockaddr_inarp *sin = &sin_m; 295 296 sin_m = blank_sin; 297 sin->sin_addr.s_addr = inet_addr(host); 298 if (sin->sin_addr.s_addr == -1) { 299 if (!(hp = gethostbyname(host))) { 300 fprintf(stderr, "arp: %s: ", host); 301 herror((char *)NULL); 302 exit(1); 303 } 304 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 305 sizeof sin->sin_addr); 306 } 307 dump(sin->sin_addr.s_addr); 308 if (found_entry == 0) { 309 printf("%s (%s) -- no entry\n", 310 host, inet_ntoa(sin->sin_addr)); 311 exit(1); 312 } 313} 314 315/* 316 * Delete an arp entry 317 */ 318int 319delete(char *host, char *info) 320{ 321 struct hostent *hp; 322 register struct sockaddr_inarp *sin = &sin_m; 323 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 324 struct sockaddr_dl *sdl; 325 326 if (info && strncmp(info, "pro", 3) ) 327 export_only = 1; 328 getsocket(); 329 sin_m = blank_sin; 330 sin->sin_addr.s_addr = inet_addr(host); 331 if (sin->sin_addr.s_addr == -1) { 332 if (!(hp = gethostbyname(host))) { 333 fprintf(stderr, "arp: %s: ", host); 334 herror((char *)NULL); 335 return (1); 336 } 337 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 338 sizeof sin->sin_addr); 339 } 340tryagain: 341 if (rtmsg(RTM_GET) < 0) { 342 perror(host); 343 return (1); 344 } 345 sin = (struct sockaddr_inarp *)(rtm + 1); 346 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 347 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 348 if (sdl->sdl_family == AF_LINK && 349 (rtm->rtm_flags & RTF_LLINFO) && 350 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 351 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 352 case IFT_ISO88024: case IFT_ISO88025: 353 goto delete; 354 } 355 } 356 if (sin_m.sin_other & SIN_PROXY) { 357 fprintf(stderr, "delete: can't locate %s\n",host); 358 return (1); 359 } else { 360 sin_m.sin_other = SIN_PROXY; 361 goto tryagain; 362 } 363delete: 364 if (sdl->sdl_family != AF_LINK) { 365 printf("cannot locate %s\n", host); 366 return (1); 367 } 368 if (rtmsg(RTM_DELETE) == 0) { 369 printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr)); 370 return (0); 371 } 372 return (1); 373} 374 375/* 376 * Dump the entire arp table 377 */ 378void 379dump(u_long addr) 380{ 381 int mib[6]; 382 size_t needed; 383 char *host, *malloc(), *lim, *buf, *next; 384 struct rt_msghdr *rtm; 385 struct sockaddr_inarp *sin; 386 struct sockaddr_dl *sdl; 387 extern int h_errno; 388 struct hostent *hp; 389 390 mib[0] = CTL_NET; 391 mib[1] = PF_ROUTE; 392 mib[2] = 0; 393 mib[3] = AF_INET; 394 mib[4] = NET_RT_FLAGS; 395 mib[5] = RTF_LLINFO; 396 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 397 quit("route-sysctl-estimate"); 398 if ((buf = malloc(needed)) == NULL) 399 quit("malloc"); 400 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 401 quit("actual retrieval of routing table"); 402 lim = buf + needed; 403 for (next = buf; next < lim; next += rtm->rtm_msglen) { 404 rtm = (struct rt_msghdr *)next; 405 sin = (struct sockaddr_inarp *)(rtm + 1); 406 sdl = (struct sockaddr_dl *)(sin + 1); 407 if (addr) { 408 if (addr != sin->sin_addr.s_addr) 409 continue; 410 found_entry = 1; 411 } 412 if (nflag == 0) 413 hp = gethostbyaddr((caddr_t)&(sin->sin_addr), 414 sizeof sin->sin_addr, AF_INET); 415 else 416 hp = 0; 417 if (hp) 418 host = hp->h_name; 419 else { 420 host = "?"; 421 if (h_errno == TRY_AGAIN) 422 nflag = 1; 423 } 424 printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr)); 425 if (sdl->sdl_alen) 426 ether_print(LLADDR(sdl)); 427 else 428 printf("(incomplete)"); 429 if (rtm->rtm_rmx.rmx_expire == 0) 430 printf(" permanent"); 431 if (sin->sin_other & SIN_PROXY) 432 printf(" published (proxy only)"); 433 if (rtm->rtm_addrs & RTA_NETMASK) { 434 sin = (struct sockaddr_inarp *) 435 (sdl->sdl_len + (char *)sdl); 436 if (sin->sin_addr.s_addr == 0xffffffff) 437 printf(" published"); 438 if (sin->sin_len != 8) 439 printf("(wierd)"); 440 } 441 printf("\n"); 442 } 443} 444 445void 446ether_print(u_char *cp) 447{ 448 printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]); 449} 450 451int 452my_ether_aton(char *a, u_char *n) 453{ 454 int i, o[6]; 455 456 i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2], 457 &o[3], &o[4], &o[5]); 458 if (i != 6) { 459 fprintf(stderr, "arp: invalid Ethernet address '%s'\n", a); 460 return (1); 461 } 462 for (i=0; i<6; i++) 463 n[i] = o[i]; 464 return (0); 465} 466 467void 468usage(void) 469{ 470 printf("usage: arp hostname\n"); 471 printf(" arp -a [kernel] [kernel_memory]\n"); 472 printf(" arp -d hostname\n"); 473 printf(" arp -s hostname ether_addr [temp] [pub]\n"); 474 printf(" arp -S hostname ether_addr [temp] [pub]\n"); 475 printf(" arp -f filename\n"); 476 exit(1); 477} 478 479int 480rtmsg(int cmd) 481{ 482 static int seq; 483 int rlen; 484 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 485 register char *cp = m_rtmsg.m_space; 486 register int l; 487 488 errno = 0; 489 if (cmd == RTM_DELETE) 490 goto doit; 491 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 492 rtm->rtm_flags = flags; 493 rtm->rtm_version = RTM_VERSION; 494 495 switch (cmd) { 496 default: 497 fprintf(stderr, "arp: internal wrong cmd\n"); 498 exit(1); 499 case RTM_ADD: 500 rtm->rtm_addrs |= RTA_GATEWAY; 501 rtm->rtm_rmx.rmx_expire = expire_time; 502 rtm->rtm_inits = RTV_EXPIRE; 503 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 504 sin_m.sin_other = 0; 505 if (doing_proxy) { 506 if (export_only) 507 sin_m.sin_other = SIN_PROXY; 508 else { 509 rtm->rtm_addrs |= RTA_NETMASK; 510 rtm->rtm_flags &= ~RTF_HOST; 511 } 512 } 513 /* FALLTHROUGH */ 514 case RTM_GET: 515 rtm->rtm_addrs |= RTA_DST; 516 } 517#define NEXTADDR(w, s) \ 518 if (rtm->rtm_addrs & (w)) { \ 519 bcopy((char *)&s, cp, sizeof(s)); cp += sizeof(s);} 520 521 NEXTADDR(RTA_DST, sin_m); 522 NEXTADDR(RTA_GATEWAY, sdl_m); 523 NEXTADDR(RTA_NETMASK, so_mask); 524 525 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 526doit: 527 l = rtm->rtm_msglen; 528 rtm->rtm_seq = ++seq; 529 rtm->rtm_type = cmd; 530 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 531 if (errno != ESRCH || cmd != RTM_DELETE) { 532 perror("writing to routing socket"); 533 return (-1); 534 } 535 } 536 do { 537 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 538 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 539 if (l < 0) 540 (void) fprintf(stderr, "arp: read from routing socket: %s\n", 541 strerror(errno)); 542 return (0); 543} 544 545void 546quit(char *msg) 547{ 548 fprintf(stderr, "%s\n", msg); 549 exit(1); 550} 551 552/* 553 * get_ether_addr - get the hardware address of an interface on the 554 * the same subnet as ipaddr. 555 */ 556#define MAX_IFS 32 557 558int 559get_ether_addr(u_long ipaddr, u_char *hwaddr) 560{ 561 struct ifreq *ifr, *ifend, *ifp; 562 u_long ina, mask; 563 struct sockaddr_dl *dla; 564 struct ifreq ifreq; 565 struct ifconf ifc; 566 struct ifreq ifs[MAX_IFS]; 567 int s; 568 569 s = socket(AF_INET, SOCK_DGRAM, 0); 570 if (s < 0) { 571 perror("socket"); 572 exit(1); 573 } 574 575 ifc.ifc_len = sizeof(ifs); 576 ifc.ifc_req = ifs; 577 if (ioctl(s, SIOCGIFCONF, &ifc) < 0) { 578 fprintf(stderr, "ioctl(SIOCGIFCONF): \n"); 579 close(s); 580 return 0; 581 } 582 583 /* 584 * Scan through looking for an interface with an Internet 585 * address on the same subnet as `ipaddr'. 586 */ 587 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len); 588 for (ifr = ifc.ifc_req; ifr < ifend; ) { 589 if (ifr->ifr_addr.sa_family == AF_INET) { 590 ina = ((struct sockaddr_in *) 591 &ifr->ifr_addr)->sin_addr.s_addr; 592 strncpy(ifreq.ifr_name, ifr->ifr_name, 593 sizeof(ifreq.ifr_name)); 594 /* 595 * Check that the interface is up, 596 * and not point-to-point or loopback. 597 */ 598 if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0) 599 continue; 600 if ((ifreq.ifr_flags & 601 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 602 IFF_LOOPBACK|IFF_NOARP)) 603 != (IFF_UP|IFF_BROADCAST)) 604 goto nextif; 605 /* 606 * Get its netmask and check that it's on 607 * the right subnet. 608 */ 609 if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0) 610 continue; 611 mask = ((struct sockaddr_in *) 612 &ifreq.ifr_addr)->sin_addr.s_addr; 613 if ((ipaddr & mask) != (ina & mask)) 614 goto nextif; 615 break; 616 } 617nextif: 618 ifr = (struct ifreq *) 619 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 620 } 621 622 if (ifr >= ifend) { 623 close(s); 624 return 0; 625 } 626 627 /* 628 * Now scan through again looking for a link-level address 629 * for this interface. 630 */ 631 ifp = ifr; 632 for (ifr = ifc.ifc_req; ifr < ifend; ) { 633 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 634 && ifr->ifr_addr.sa_family == AF_LINK) { 635 /* 636 * Found the link-level address - copy it out 637 */ 638 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 639 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 640 close (s); 641 printf("using interface %s for proxy with address ", 642 ifp->ifr_name); 643 ether_print(hwaddr); 644 printf("\n"); 645 return dla->sdl_alen; 646 } 647 ifr = (struct ifreq *) 648 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 649 } 650 return 0; 651} 652