arp.c revision 13977
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 60#include <net/if.h> 61#include <net/if_dl.h> 62#include <net/if_types.h> 63#include <net/route.h> 64 65#include <netinet/in.h> 66#include <netinet/if_ether.h> 67 68#include <arpa/inet.h> 69 70#include <netdb.h> 71#include <errno.h> 72#include <nlist.h> 73#include <stdio.h> 74#include <stdlib.h> 75#include <unistd.h> 76#include <strings.h> 77#include <paths.h> 78 79void dump(u_long addr); 80int delete(char *host, char *info); 81void ether_print(u_char *cp); 82void usage(void); 83int set(int argc, char **argv); 84void get(char *host); 85int file(char *name); 86void getsocket(void); 87int ether_aton(char *a, u_char *n); 88int rtmsg(int cmd); 89void quit(char *msg); 90int get_ether_addr(u_long ipaddr, u_char *hwaddr); 91 92extern int errno; 93static int pid; 94static int nflag; 95static int s = -1; 96 97int 98main(argc, argv) 99 int argc; 100 char **argv; 101{ 102 int ch; 103 104 pid = getpid(); 105 while ((ch = getopt(argc, argv, "andfsS")) != EOF) 106 switch((char)ch) { 107 case 'a': 108 dump(0); 109 exit(0); 110 case 'd': 111 if (argc < 3 || argc > 4) 112 usage(); 113 delete(argv[2], argv[3]); 114 exit(0); 115 case 'n': 116 nflag = 1; 117 continue; 118 case 'S': 119 delete(argv[2], NULL); 120 /* FALL THROUGH */ 121 case 's': 122 if (argc < 4 || argc > 7) 123 usage(); 124 exit(set(argc-2, &argv[2]) ? 1 : 0); 125 case 'f' : 126 if (argc != 3) 127 usage(); 128 return (file(argv[2])); 129 case '?': 130 default: 131 usage(); 132 } 133 if (argc != 2) 134 usage(); 135 get(argv[1]); 136 exit(0); 137} 138 139/* 140 * Process a file to set standard arp entries 141 */ 142int 143file(char *name) 144{ 145 FILE *fp; 146 int i, retval; 147 char line[100], arg[5][50], *args[5]; 148 149 if ((fp = fopen(name, "r")) == NULL) { 150 fprintf(stderr, "arp: cannot open %s\n", name); 151 exit(1); 152 } 153 args[0] = &arg[0][0]; 154 args[1] = &arg[1][0]; 155 args[2] = &arg[2][0]; 156 args[3] = &arg[3][0]; 157 args[4] = &arg[4][0]; 158 retval = 0; 159 while(fgets(line, 100, fp) != NULL) { 160 i = sscanf(line, "%s %s %s %s %s", arg[0], arg[1], arg[2], 161 arg[3], arg[4]); 162 if (i < 2) { 163 fprintf(stderr, "arp: bad line: %s\n", line); 164 retval = 1; 165 continue; 166 } 167 if (set(i, args)) 168 retval = 1; 169 } 170 fclose(fp); 171 return (retval); 172} 173 174void 175getsocket(void) 176{ 177 if (s < 0) { 178 s = socket(PF_ROUTE, SOCK_RAW, 0); 179 if (s < 0) { 180 perror("arp: socket"); 181 exit(1); 182 } 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 fprintf(stderr, "arp: %s: ", host); 217 herror((char *)NULL); 218 return (1); 219 } 220 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 221 sizeof sin->sin_addr); 222 } 223 doing_proxy = flags = export_only = expire_time = 0; 224 while (argc-- > 0) { 225 if (strncmp(argv[0], "temp", 4) == 0) { 226 struct timeval time; 227 gettimeofday(&time, 0); 228 expire_time = time.tv_sec + 20 * 60; 229 } 230 else if (strncmp(argv[0], "pub", 3) == 0) { 231 flags |= RTF_ANNOUNCE; 232 doing_proxy = SIN_PROXY; 233 } else if (strncmp(argv[0], "trail", 5) == 0) { 234 printf("%s: Sending trailers is no longer supported\n", 235 host); 236 } 237 argv++; 238 } 239 ea = (u_char *)LLADDR(&sdl_m); 240 if (doing_proxy && !strcmp(eaddr, "auto")) { 241 if (!get_ether_addr(sin->sin_addr.s_addr, ea)) { 242 return (1); 243 } 244 sdl_m.sdl_alen = 6; 245 } else { 246 if (ether_aton(eaddr, ea) == 0) 247 sdl_m.sdl_alen = 6; 248 } 249tryagain: 250 if (rtmsg(RTM_GET) < 0) { 251 perror(host); 252 return (1); 253 } 254 sin = (struct sockaddr_inarp *)(rtm + 1); 255 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 256 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 257 if (sdl->sdl_family == AF_LINK && 258 (rtm->rtm_flags & RTF_LLINFO) && 259 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 260 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 261 case IFT_ISO88024: case IFT_ISO88025: 262 goto overwrite; 263 } 264 if (doing_proxy == 0) { 265 printf("set: can only proxy for %s\n", host); 266 return (1); 267 } 268 if (sin_m.sin_other & SIN_PROXY) { 269 printf("set: proxy entry exists for non 802 device\n"); 270 return(1); 271 } 272 sin_m.sin_other = SIN_PROXY; 273 export_only = 1; 274 goto tryagain; 275 } 276overwrite: 277 if (sdl->sdl_family != AF_LINK) { 278 printf("cannot intuit interface index and type for %s\n", host); 279 return (1); 280 } 281 sdl_m.sdl_type = sdl->sdl_type; 282 sdl_m.sdl_index = sdl->sdl_index; 283 return (rtmsg(RTM_ADD)); 284} 285 286/* 287 * Display an individual arp entry 288 */ 289void 290get(char *host) 291{ 292 struct hostent *hp; 293 struct sockaddr_inarp *sin = &sin_m; 294 295 sin_m = blank_sin; 296 sin->sin_addr.s_addr = inet_addr(host); 297 if (sin->sin_addr.s_addr == -1) { 298 if (!(hp = gethostbyname(host))) { 299 fprintf(stderr, "arp: %s: ", host); 300 herror((char *)NULL); 301 exit(1); 302 } 303 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 304 sizeof sin->sin_addr); 305 } 306 dump(sin->sin_addr.s_addr); 307 if (found_entry == 0) { 308 printf("%s (%s) -- no entry\n", 309 host, inet_ntoa(sin->sin_addr)); 310 exit(1); 311 } 312} 313 314/* 315 * Delete an arp entry 316 */ 317int 318delete(char *host, char *info) 319{ 320 struct hostent *hp; 321 register struct sockaddr_inarp *sin = &sin_m; 322 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 323 struct sockaddr_dl *sdl; 324 325 if (info && strncmp(info, "pro", 3) ) 326 export_only = 1; 327 getsocket(); 328 sin_m = blank_sin; 329 sin->sin_addr.s_addr = inet_addr(host); 330 if (sin->sin_addr.s_addr == -1) { 331 if (!(hp = gethostbyname(host))) { 332 fprintf(stderr, "arp: %s: ", host); 333 herror((char *)NULL); 334 return (1); 335 } 336 bcopy((char *)hp->h_addr, (char *)&sin->sin_addr, 337 sizeof sin->sin_addr); 338 } 339tryagain: 340 if (rtmsg(RTM_GET) < 0) { 341 perror(host); 342 return (1); 343 } 344 sin = (struct sockaddr_inarp *)(rtm + 1); 345 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 346 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 347 if (sdl->sdl_family == AF_LINK && 348 (rtm->rtm_flags & RTF_LLINFO) && 349 !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) { 350 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023: 351 case IFT_ISO88024: case IFT_ISO88025: 352 goto delete; 353 } 354 } 355 if (sin_m.sin_other & SIN_PROXY) { 356 fprintf(stderr, "delete: can't locate %s\n",host); 357 return (1); 358 } else { 359 sin_m.sin_other = SIN_PROXY; 360 goto tryagain; 361 } 362delete: 363 if (sdl->sdl_family != AF_LINK) { 364 printf("cannot locate %s\n", host); 365 return (1); 366 } 367 if (rtmsg(RTM_DELETE) == 0) { 368 printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr)); 369 return (0); 370 } 371 return (1); 372} 373 374/* 375 * Dump the entire arp table 376 */ 377void 378dump(u_long addr) 379{ 380 int mib[6]; 381 size_t needed; 382 char *host, *malloc(), *lim, *buf, *next; 383 struct rt_msghdr *rtm; 384 struct sockaddr_inarp *sin; 385 struct sockaddr_dl *sdl; 386 extern int h_errno; 387 struct hostent *hp; 388 389 mib[0] = CTL_NET; 390 mib[1] = PF_ROUTE; 391 mib[2] = 0; 392 mib[3] = AF_INET; 393 mib[4] = NET_RT_FLAGS; 394 mib[5] = RTF_LLINFO; 395 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) 396 quit("route-sysctl-estimate"); 397 if ((buf = malloc(needed)) == NULL) 398 quit("malloc"); 399 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) 400 quit("actual retrieval of routing table"); 401 lim = buf + needed; 402 for (next = buf; next < lim; next += rtm->rtm_msglen) { 403 rtm = (struct rt_msghdr *)next; 404 sin = (struct sockaddr_inarp *)(rtm + 1); 405 sdl = (struct sockaddr_dl *)(sin + 1); 406 if (addr) { 407 if (addr != sin->sin_addr.s_addr) 408 continue; 409 found_entry = 1; 410 } 411 if (nflag == 0) 412 hp = gethostbyaddr((caddr_t)&(sin->sin_addr), 413 sizeof sin->sin_addr, AF_INET); 414 else 415 hp = 0; 416 if (hp) 417 host = hp->h_name; 418 else { 419 host = "?"; 420 if (h_errno == TRY_AGAIN) 421 nflag = 1; 422 } 423 printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr)); 424 if (sdl->sdl_alen) 425 ether_print(LLADDR(sdl)); 426 else 427 printf("(incomplete)"); 428 if (rtm->rtm_rmx.rmx_expire == 0) 429 printf(" permanent"); 430 if (sin->sin_other & SIN_PROXY) 431 printf(" published (proxy only)"); 432 if (rtm->rtm_addrs & RTA_NETMASK) { 433 sin = (struct sockaddr_inarp *) 434 (sdl->sdl_len + (char *)sdl); 435 if (sin->sin_addr.s_addr == 0xffffffff) 436 printf(" published"); 437 if (sin->sin_len != 8) 438 printf("(wierd)"); 439 } 440 printf("\n"); 441 } 442} 443 444void 445ether_print(u_char *cp) 446{ 447 printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]); 448} 449 450int 451ether_aton(char *a, u_char *n) 452{ 453 int i, o[6]; 454 455 i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2], 456 &o[3], &o[4], &o[5]); 457 if (i != 6) { 458 fprintf(stderr, "arp: invalid Ethernet address '%s'\n", a); 459 return (1); 460 } 461 for (i=0; i<6; i++) 462 n[i] = o[i]; 463 return (0); 464} 465 466void 467usage(void) 468{ 469 printf("usage: arp hostname\n"); 470 printf(" arp -a [kernel] [kernel_memory]\n"); 471 printf(" arp -d hostname\n"); 472 printf(" arp -s hostname ether_addr [temp] [pub]\n"); 473 printf(" arp -S hostname ether_addr [temp] [pub]\n"); 474 printf(" arp -f filename\n"); 475 exit(1); 476} 477 478int 479rtmsg(int cmd) 480{ 481 static int seq; 482 int rlen; 483 register struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 484 register char *cp = m_rtmsg.m_space; 485 register int l; 486 487 errno = 0; 488 if (cmd == RTM_DELETE) 489 goto doit; 490 bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); 491 rtm->rtm_flags = flags; 492 rtm->rtm_version = RTM_VERSION; 493 494 switch (cmd) { 495 default: 496 fprintf(stderr, "arp: internal wrong cmd\n"); 497 exit(1); 498 case RTM_ADD: 499 rtm->rtm_addrs |= RTA_GATEWAY; 500 rtm->rtm_rmx.rmx_expire = expire_time; 501 rtm->rtm_inits = RTV_EXPIRE; 502 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 503 sin_m.sin_other = 0; 504 if (doing_proxy) { 505 if (export_only) 506 sin_m.sin_other = SIN_PROXY; 507 else { 508 rtm->rtm_addrs |= RTA_NETMASK; 509 rtm->rtm_flags &= ~RTF_HOST; 510 } 511 } 512 /* FALLTHROUGH */ 513 case RTM_GET: 514 rtm->rtm_addrs |= RTA_DST; 515 } 516#define NEXTADDR(w, s) \ 517 if (rtm->rtm_addrs & (w)) { \ 518 bcopy((char *)&s, cp, sizeof(s)); cp += sizeof(s);} 519 520 NEXTADDR(RTA_DST, sin_m); 521 NEXTADDR(RTA_GATEWAY, sdl_m); 522 NEXTADDR(RTA_NETMASK, so_mask); 523 524 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 525doit: 526 l = rtm->rtm_msglen; 527 rtm->rtm_seq = ++seq; 528 rtm->rtm_type = cmd; 529 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 530 if (errno != ESRCH || cmd != RTM_DELETE) { 531 perror("writing to routing socket"); 532 return (-1); 533 } 534 } 535 do { 536 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 537 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 538 if (l < 0) 539 (void) fprintf(stderr, "arp: read from routing socket: %s\n", 540 strerror(errno)); 541 return (0); 542} 543 544void 545quit(char *msg) 546{ 547 fprintf(stderr, "%s\n", msg); 548 exit(1); 549} 550 551/* 552 * get_ether_addr - get the hardware address of an interface on the 553 * the same subnet as ipaddr. 554 */ 555#define MAX_IFS 32 556 557int 558get_ether_addr(u_long ipaddr, u_char *hwaddr) 559{ 560 struct ifreq *ifr, *ifend, *ifp; 561 u_long ina, mask; 562 struct sockaddr_dl *dla; 563 struct ifreq ifreq; 564 struct ifconf ifc; 565 struct ifreq ifs[MAX_IFS]; 566 int s; 567 568 s = socket(AF_INET, SOCK_DGRAM, 0); 569 if (s < 0) { 570 perror("socket"); 571 exit(1); 572 } 573 574 ifc.ifc_len = sizeof(ifs); 575 ifc.ifc_req = ifs; 576 if (ioctl(s, SIOCGIFCONF, &ifc) < 0) { 577 fprintf(stderr, "ioctl(SIOCGIFCONF): \n"); 578 close(s); 579 return 0; 580 } 581 582 /* 583 * Scan through looking for an interface with an Internet 584 * address on the same subnet as `ipaddr'. 585 */ 586 ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len); 587 for (ifr = ifc.ifc_req; ifr < ifend; ) { 588 if (ifr->ifr_addr.sa_family == AF_INET) { 589 ina = ((struct sockaddr_in *) 590 &ifr->ifr_addr)->sin_addr.s_addr; 591 strncpy(ifreq.ifr_name, ifr->ifr_name, 592 sizeof(ifreq.ifr_name)); 593 /* 594 * Check that the interface is up, 595 * and not point-to-point or loopback. 596 */ 597 if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0) 598 continue; 599 if ((ifreq.ifr_flags & 600 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| 601 IFF_LOOPBACK|IFF_NOARP)) 602 != (IFF_UP|IFF_BROADCAST)) 603 goto nextif; 604 /* 605 * Get its netmask and check that it's on 606 * the right subnet. 607 */ 608 if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0) 609 continue; 610 mask = ((struct sockaddr_in *) 611 &ifreq.ifr_addr)->sin_addr.s_addr; 612 if ((ipaddr & mask) != (ina & mask)) 613 goto nextif; 614 break; 615 } 616nextif: 617 ifr = (struct ifreq *) 618 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 619 } 620 621 if (ifr >= ifend) { 622 close(s); 623 return 0; 624 } 625 626 /* 627 * Now scan through again looking for a link-level address 628 * for this interface. 629 */ 630 ifp = ifr; 631 for (ifr = ifc.ifc_req; ifr < ifend; ) { 632 if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 633 && ifr->ifr_addr.sa_family == AF_LINK) { 634 /* 635 * Found the link-level address - copy it out 636 */ 637 dla = (struct sockaddr_dl *) &ifr->ifr_addr; 638 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); 639 close (s); 640 printf("using interface %s for proxy with address ", 641 ifp->ifr_name); 642 ether_print(hwaddr); 643 printf("\n"); 644 return dla->sdl_alen; 645 } 646 ifr = (struct ifreq *) 647 ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len); 648 } 649 return 0; 650} 651