1/* vi: set sw=4 ts=4: */ 2/* 3 * arp.c - Manipulate the system ARP cache 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * Author: Fred N. van Kempen, <waltje at uwalt.nl.mugnet.org> 11 * Busybox port: Paul van Gool <pvangool at mimotech.com> 12 * 13 * modified for getopt32 by Arne Bernin <arne [at] alamut.de> 14 */ 15 16#include "libbb.h" 17#include "inet_common.h" 18 19#include <arpa/inet.h> 20#include <net/if.h> 21#include <net/if_arp.h> 22#include <netinet/ether.h> 23#include <netpacket/packet.h> 24 25#define DEBUG 0 26 27#define DFLT_AF "inet" 28#define DFLT_HW "ether" 29 30enum { 31 ARP_OPT_A = (1 << 0), 32 ARP_OPT_p = (1 << 1), 33 ARP_OPT_H = (1 << 2), 34 ARP_OPT_t = (1 << 3), 35 ARP_OPT_i = (1 << 4), 36 ARP_OPT_a = (1 << 5), 37 ARP_OPT_d = (1 << 6), 38 ARP_OPT_n = (1 << 7), /* do not resolve addresses */ 39 ARP_OPT_D = (1 << 8), /* HW-address is devicename */ 40 ARP_OPT_s = (1 << 9), 41 ARP_OPT_v = (1 << 10) * DEBUG, /* debugging output flag */ 42}; 43 44enum { 45 sockfd = 3, /* active socket descriptor */ 46}; 47 48struct globals { 49 const struct aftype *ap; /* current address family */ 50 const struct hwtype *hw; /* current hardware type */ 51 const char *device; /* current device */ 52 smallint hw_set; /* flag if hw-type was set (-H) */ 53 54} FIX_ALIASING; 55#define G (*(struct globals*)&bb_common_bufsiz1) 56#define ap (G.ap ) 57#define hw (G.hw ) 58#define device (G.device ) 59#define hw_set (G.hw_set ) 60#define INIT_G() do { \ 61 device = ""; \ 62} while (0) 63 64 65static const char options[] ALIGN1 = 66 "pub\0" 67 "priv\0" 68 "temp\0" 69 "trail\0" 70 "dontpub\0" 71 "auto\0" 72 "dev\0" 73 "netmask\0"; 74 75/* Delete an entry from the ARP cache. */ 76/* Called only from main, once */ 77static int arp_del(char **args) 78{ 79 char *host; 80 struct arpreq req; 81 struct sockaddr sa; 82 int flags = 0; 83 int err; 84 85 memset(&req, 0, sizeof(req)); 86 87 /* Resolve the host name. */ 88 host = *args; 89 if (ap->input(host, &sa) < 0) { 90 bb_herror_msg_and_die("%s", host); 91 } 92 93 /* If a host has more than one address, use the correct one! */ 94 memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr)); 95 96 if (hw_set) 97 req.arp_ha.sa_family = hw->type; 98 99 req.arp_flags = ATF_PERM; 100 args++; 101 while (*args != NULL) { 102 switch (index_in_strings(options, *args)) { 103 case 0: /* "pub" */ 104 flags |= 1; 105 args++; 106 break; 107 case 1: /* "priv" */ 108 flags |= 2; 109 args++; 110 break; 111 case 2: /* "temp" */ 112 req.arp_flags &= ~ATF_PERM; 113 args++; 114 break; 115 case 3: /* "trail" */ 116 req.arp_flags |= ATF_USETRAILERS; 117 args++; 118 break; 119 case 4: /* "dontpub" */ 120#ifdef HAVE_ATF_DONTPUB 121 req.arp_flags |= ATF_DONTPUB; 122#else 123 bb_error_msg("feature ATF_DONTPUB is not supported"); 124#endif 125 args++; 126 break; 127 case 5: /* "auto" */ 128#ifdef HAVE_ATF_MAGIC 129 req.arp_flags |= ATF_MAGIC; 130#else 131 bb_error_msg("feature ATF_MAGIC is not supported"); 132#endif 133 args++; 134 break; 135 case 6: /* "dev" */ 136 if (*++args == NULL) 137 bb_show_usage(); 138 device = *args; 139 args++; 140 break; 141 case 7: /* "netmask" */ 142 if (*++args == NULL) 143 bb_show_usage(); 144 if (strcmp(*args, "255.255.255.255") != 0) { 145 host = *args; 146 if (ap->input(host, &sa) < 0) { 147 bb_herror_msg_and_die("%s", host); 148 } 149 memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr)); 150 req.arp_flags |= ATF_NETMASK; 151 } 152 args++; 153 break; 154 default: 155 bb_show_usage(); 156 break; 157 } 158 } 159 if (flags == 0) 160 flags = 3; 161 162 strncpy(req.arp_dev, device, sizeof(req.arp_dev)); 163 164 err = -1; 165 166 /* Call the kernel. */ 167 if (flags & 2) { 168 if (option_mask32 & ARP_OPT_v) 169 bb_error_msg("SIOCDARP(nopub)"); 170 err = ioctl(sockfd, SIOCDARP, &req); 171 if (err < 0) { 172 if (errno == ENXIO) { 173 if (flags & 1) 174 goto nopub; 175 printf("No ARP entry for %s\n", host); 176 return -1; 177 } 178 bb_perror_msg_and_die("SIOCDARP(priv)"); 179 } 180 } 181 if ((flags & 1) && err) { 182 nopub: 183 req.arp_flags |= ATF_PUBL; 184 if (option_mask32 & ARP_OPT_v) 185 bb_error_msg("SIOCDARP(pub)"); 186 if (ioctl(sockfd, SIOCDARP, &req) < 0) { 187 if (errno == ENXIO) { 188 printf("No ARP entry for %s\n", host); 189 return -1; 190 } 191 bb_perror_msg_and_die("SIOCDARP(pub)"); 192 } 193 } 194 return 0; 195} 196 197/* Get the hardware address to a specified interface name */ 198static void arp_getdevhw(char *ifname, struct sockaddr *sa, 199 const struct hwtype *hwt) 200{ 201 struct ifreq ifr; 202 const struct hwtype *xhw; 203 204 strcpy(ifr.ifr_name, ifname); 205 ioctl_or_perror_and_die(sockfd, SIOCGIFHWADDR, &ifr, 206 "cant get HW-Address for '%s'", ifname); 207 if (hwt && (ifr.ifr_hwaddr.sa_family != hw->type)) { 208 bb_error_msg_and_die("protocol type mismatch"); 209 } 210 memcpy(sa, &(ifr.ifr_hwaddr), sizeof(struct sockaddr)); 211 212 if (option_mask32 & ARP_OPT_v) { 213 xhw = get_hwntype(ifr.ifr_hwaddr.sa_family); 214 if (!xhw || !xhw->print) { 215 xhw = get_hwntype(-1); 216 } 217 bb_error_msg("device '%s' has HW address %s '%s'", 218 ifname, xhw->name, 219 xhw->print((unsigned char *) &ifr.ifr_hwaddr.sa_data)); 220 } 221} 222 223/* Set an entry in the ARP cache. */ 224/* Called only from main, once */ 225static int arp_set(char **args) 226{ 227 char *host; 228 struct arpreq req; 229 struct sockaddr sa; 230 int flags; 231 232 memset(&req, 0, sizeof(req)); 233 234 host = *args++; 235 if (ap->input(host, &sa) < 0) { 236 bb_herror_msg_and_die("%s", host); 237 } 238 /* If a host has more than one address, use the correct one! */ 239 memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr)); 240 241 /* Fetch the hardware address. */ 242 if (*args == NULL) { 243 bb_error_msg_and_die("need hardware address"); 244 } 245 if (option_mask32 & ARP_OPT_D) { 246 arp_getdevhw(*args++, &req.arp_ha, hw_set ? hw : NULL); 247 } else { 248 if (hw->input(*args++, &req.arp_ha) < 0) { 249 bb_error_msg_and_die("invalid hardware address"); 250 } 251 } 252 253 /* Check out any modifiers. */ 254 flags = ATF_PERM | ATF_COM; 255 while (*args != NULL) { 256 switch (index_in_strings(options, *args)) { 257 case 0: /* "pub" */ 258 flags |= ATF_PUBL; 259 args++; 260 break; 261 case 1: /* "priv" */ 262 flags &= ~ATF_PUBL; 263 args++; 264 break; 265 case 2: /* "temp" */ 266 flags &= ~ATF_PERM; 267 args++; 268 break; 269 case 3: /* "trail" */ 270 flags |= ATF_USETRAILERS; 271 args++; 272 break; 273 case 4: /* "dontpub" */ 274#ifdef HAVE_ATF_DONTPUB 275 flags |= ATF_DONTPUB; 276#else 277 bb_error_msg("feature ATF_DONTPUB is not supported"); 278#endif 279 args++; 280 break; 281 case 5: /* "auto" */ 282#ifdef HAVE_ATF_MAGIC 283 flags |= ATF_MAGIC; 284#else 285 bb_error_msg("feature ATF_MAGIC is not supported"); 286#endif 287 args++; 288 break; 289 case 6: /* "dev" */ 290 if (*++args == NULL) 291 bb_show_usage(); 292 device = *args; 293 args++; 294 break; 295 case 7: /* "netmask" */ 296 if (*++args == NULL) 297 bb_show_usage(); 298 if (strcmp(*args, "255.255.255.255") != 0) { 299 host = *args; 300 if (ap->input(host, &sa) < 0) { 301 bb_herror_msg_and_die("%s", host); 302 } 303 memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr)); 304 flags |= ATF_NETMASK; 305 } 306 args++; 307 break; 308 default: 309 bb_show_usage(); 310 break; 311 } 312 } 313 314 /* Fill in the remainder of the request. */ 315 req.arp_flags = flags; 316 317 strncpy(req.arp_dev, device, sizeof(req.arp_dev)); 318 319 /* Call the kernel. */ 320 if (option_mask32 & ARP_OPT_v) 321 bb_error_msg("SIOCSARP()"); 322 xioctl(sockfd, SIOCSARP, &req); 323 return 0; 324} 325 326 327/* Print the contents of an ARP request block. */ 328static void 329arp_disp(const char *name, char *ip, int type, int arp_flags, 330 char *hwa, char *mask, char *dev) 331{ 332 static const int arp_masks[] = { 333 ATF_PERM, ATF_PUBL, 334#ifdef HAVE_ATF_MAGIC 335 ATF_MAGIC, 336#endif 337#ifdef HAVE_ATF_DONTPUB 338 ATF_DONTPUB, 339#endif 340 ATF_USETRAILERS, 341 }; 342 static const char arp_labels[] ALIGN1 = "PERM\0""PUP\0" 343#ifdef HAVE_ATF_MAGIC 344 "AUTO\0" 345#endif 346#ifdef HAVE_ATF_DONTPUB 347 "DONTPUB\0" 348#endif 349 "TRAIL\0" 350 ; 351 352 const struct hwtype *xhw; 353 354 xhw = get_hwntype(type); 355 if (xhw == NULL) 356 xhw = get_hwtype(DFLT_HW); 357 358 printf("%s (%s) at ", name, ip); 359 360 if (!(arp_flags & ATF_COM)) { 361 if (arp_flags & ATF_PUBL) 362 printf("* "); 363 else 364 printf("<incomplete> "); 365 } else { 366 printf("%s [%s] ", hwa, xhw->name); 367 } 368 369 if (arp_flags & ATF_NETMASK) 370 printf("netmask %s ", mask); 371 372 print_flags_separated(arp_masks, arp_labels, arp_flags, " "); 373 printf(" on %s\n", dev); 374} 375 376/* Display the contents of the ARP cache in the kernel. */ 377/* Called only from main, once */ 378static int arp_show(char *name) 379{ 380 const char *host; 381 const char *hostname; 382 FILE *fp; 383 struct sockaddr sa; 384 int type, flags; 385 int num; 386 unsigned entries = 0, shown = 0; 387 char ip[128]; 388 char hwa[128]; 389 char mask[128]; 390 char line[128]; 391 char dev[128]; 392 393 host = NULL; 394 if (name != NULL) { 395 /* Resolve the host name. */ 396 if (ap->input(name, &sa) < 0) { 397 bb_herror_msg_and_die("%s", name); 398 } 399 host = xstrdup(ap->sprint(&sa, 1)); 400 } 401 fp = xfopen_for_read("/proc/net/arp"); 402 /* Bypass header -- read one line */ 403 fgets(line, sizeof(line), fp); 404 405 /* Read the ARP cache entries. */ 406 while (fgets(line, sizeof(line), fp)) { 407 408 mask[0] = '-'; mask[1] = '\0'; 409 dev[0] = '-'; dev[1] = '\0'; 410 /* All these strings can't overflow 411 * because fgets above reads limited amount of data */ 412 num = sscanf(line, "%s 0x%x 0x%x %s %s %s\n", 413 ip, &type, &flags, hwa, mask, dev); 414 if (num < 4) 415 break; 416 417 entries++; 418 /* if the user specified hw-type differs, skip it */ 419 if (hw_set && (type != hw->type)) 420 continue; 421 422 /* if the user specified address differs, skip it */ 423 if (host && strcmp(ip, host) != 0) 424 continue; 425 426 /* if the user specified device differs, skip it */ 427 if (device[0] && strcmp(dev, device) != 0) 428 continue; 429 430 shown++; 431 /* This IS ugly but it works -be */ 432 hostname = "?"; 433 if (!(option_mask32 & ARP_OPT_n)) { 434 if (ap->input(ip, &sa) < 0) 435 hostname = ip; 436 else 437 hostname = ap->sprint(&sa, (option_mask32 & ARP_OPT_n) | 0x8000); 438 if (strcmp(hostname, ip) == 0) 439 hostname = "?"; 440 } 441 442 arp_disp(hostname, ip, type, flags, hwa, mask, dev); 443 } 444 if (option_mask32 & ARP_OPT_v) 445 printf("Entries: %d\tSkipped: %d\tFound: %d\n", 446 entries, entries - shown, shown); 447 448 if (!shown) { 449 if (hw_set || host || device[0]) 450 printf("No match found in %d entries\n", entries); 451 } 452 if (ENABLE_FEATURE_CLEAN_UP) { 453 free((char*)host); 454 fclose(fp); 455 } 456 return 0; 457} 458 459int arp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 460int arp_main(int argc UNUSED_PARAM, char **argv) 461{ 462 const char *hw_type = "ether"; 463 const char *protocol; 464 unsigned opts; 465 466 INIT_G(); 467 468 xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), sockfd); 469 ap = get_aftype(DFLT_AF); 470 if (!ap) 471 bb_error_msg_and_die("%s: %s not supported", DFLT_AF, "address family"); 472 473 opts = getopt32(argv, "A:p:H:t:i:adnDsv", &protocol, &protocol, 474 &hw_type, &hw_type, &device); 475 argv += optind; 476 if (opts & (ARP_OPT_A | ARP_OPT_p)) { 477 ap = get_aftype(protocol); 478 if (ap == NULL) 479 bb_error_msg_and_die("%s: unknown %s", protocol, "address family"); 480 } 481 if (opts & (ARP_OPT_A | ARP_OPT_p)) { 482 hw = get_hwtype(hw_type); 483 if (hw == NULL) 484 bb_error_msg_and_die("%s: unknown %s", hw_type, "hardware type"); 485 hw_set = 1; 486 } 487 //if (opts & ARP_OPT_i)... -i 488 489 if (ap->af != AF_INET) { 490 bb_error_msg_and_die("%s: kernel only supports 'inet'", ap->name); 491 } 492 493 /* If no hw type specified get default */ 494 if (!hw) { 495 hw = get_hwtype(DFLT_HW); 496 if (!hw) 497 bb_error_msg_and_die("%s: %s not supported", DFLT_HW, "hardware type"); 498 } 499 500 if (hw->alen <= 0) { 501 bb_error_msg_and_die("%s: %s without ARP support", 502 hw->name, "hardware type"); 503 } 504 505 /* Now see what we have to do here... */ 506 if (opts & (ARP_OPT_d | ARP_OPT_s)) { 507 if (argv[0] == NULL) 508 bb_error_msg_and_die("need host name"); 509 if (opts & ARP_OPT_s) 510 return arp_set(argv); 511 return arp_del(argv); 512 } 513 //if (opts & ARP_OPT_a) - default 514 return arp_show(argv[0]); 515} 516