LXR busybox/networking/arp.c

   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