LXR busybox/networking/ifconfig.c

   1/* vi: set sw=4 ts=4: */
   2/* ifconfig
   3 *
   4 * Similar to the standard Unix ifconfig, but with only the necessary
   5 * parts for AF_INET, and without any printing of if info (for now).
   6 *
   7 * Bjorn Wesen, Axis Communications AB
   8 *
   9 *
  10 * Authors of the original ifconfig was:
  11 *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  12 *
  13 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  14 */
  15
  16/*
  17 * Heavily modified by Manuel Novoa III       Mar 6, 2001
  18 *
  19 * From initial port to busybox, removed most of the redundancy by
  20 * converting to a table-driven approach.  Added several (optional)
  21 * args missing from initial port.
  22 *
  23 * Still missing:  media, tunnel.
  24 *
  25 * 2002-04-20
  26 * IPV6 support added by Bart Visscher <magick@linux-fan.com>
  27 */
  28
  29//usage:#define ifconfig_trivial_usage
  30//usage:        IF_FEATURE_IFCONFIG_STATUS("[-a]") " interface [address]"
  31//usage:#define ifconfig_full_usage "\n\n"
  32//usage:       "Configure a network interface\n"
  33//usage:     "\n"
  34//usage:        IF_FEATURE_IPV6(
  35//usage:       "        [add ADDRESS[/PREFIXLEN]]\n")
  36//usage:        IF_FEATURE_IPV6(
  37//usage:       "        [del ADDRESS[/PREFIXLEN]]\n")
  38//usage:       "        [[-]broadcast [ADDRESS]] [[-]pointopoint [ADDRESS]]\n"
  39//usage:       "        [netmask ADDRESS] [dstaddr ADDRESS]\n"
  40//usage:        IF_FEATURE_IFCONFIG_SLIP(
  41//usage:       "        [outfill NN] [keepalive NN]\n")
  42//usage:       "        " IF_FEATURE_IFCONFIG_HW("[hw ether" IF_FEATURE_HWIB("|infiniband")" ADDRESS] ") "[metric NN] [mtu NN]\n"
  43//usage:       "        [[-]trailers] [[-]arp] [[-]allmulti]\n"
  44//usage:       "        [multicast] [[-]promisc] [txqueuelen NN] [[-]dynamic]\n"
  45//usage:        IF_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ(
  46//usage:       "        [mem_start NN] [io_addr NN] [irq NN]\n")
  47//usage:       "        [up|down] ..."
  48
  49#include "libbb.h"
  50#include "inet_common.h"
  51#include <net/if.h>
  52#include <net/if_arp.h>
  53#include <netinet/in.h>
  54#ifdef HAVE_NET_ETHERNET_H
  55# include <net/ethernet.h>
  56#endif
  57
  58#if ENABLE_FEATURE_IFCONFIG_SLIP
  59# include <linux/if_slip.h>
  60#endif
  61
  62/* I don't know if this is needed for busybox or not.  Anyone? */
  63#define QUESTIONABLE_ALIAS_CASE
  64
  65
  66/* Defines for glibc2.0 users. */
  67#ifndef SIOCSIFTXQLEN
  68# define SIOCSIFTXQLEN      0x8943
  69# define SIOCGIFTXQLEN      0x8942
  70#endif
  71
  72/* ifr_qlen is ifru_ivalue, but it isn't present in 2.0 kernel headers */
  73#ifndef ifr_qlen
  74# define ifr_qlen        ifr_ifru.ifru_mtu
  75#endif
  76
  77#ifndef IFF_DYNAMIC
  78# define IFF_DYNAMIC     0x8000 /* dialup device with changing addresses */
  79#endif
  80
  81#if ENABLE_FEATURE_IPV6
  82struct in6_ifreq {
  83        struct in6_addr ifr6_addr;
  84        uint32_t ifr6_prefixlen;
  85        int ifr6_ifindex;
  86};
  87#endif
  88
  89/*
  90 * Here are the bit masks for the "flags" member of struct options below.
  91 * N_ signifies no arg prefix; M_ signifies arg prefixed by '-'.
  92 * CLR clears the flag; SET sets the flag; ARG signifies (optional) arg.
  93 */
  94#define N_CLR            0x01
  95#define M_CLR            0x02
  96#define N_SET            0x04
  97#define M_SET            0x08
  98#define N_ARG            0x10
  99#define M_ARG            0x20
 100
 101#define M_MASK           (M_CLR | M_SET | M_ARG)
 102#define N_MASK           (N_CLR | N_SET | N_ARG)
 103#define SET_MASK         (N_SET | M_SET)
 104#define CLR_MASK         (N_CLR | M_CLR)
 105#define SET_CLR_MASK     (SET_MASK | CLR_MASK)
 106#define ARG_MASK         (M_ARG | N_ARG)
 107
 108/*
 109 * Here are the bit masks for the "arg_flags" member of struct options below.
 110 */
 111
 112/*
 113 * cast type:
 114 *   00 int
 115 *   01 char *
 116 *   02 HOST_COPY in_ether
 117 *   03 HOST_COPY INET_resolve
 118 */
 119#define A_CAST_TYPE      0x03
 120/*
 121 * map type:
 122 *   00 not a map type (mem_start, io_addr, irq)
 123 *   04 memstart (unsigned long)
 124 *   08 io_addr  (unsigned short)
 125 *   0C irq      (unsigned char)
 126 */
 127#define A_MAP_TYPE       0x0C
 128#define A_ARG_REQ        0x10   /* Set if an arg is required. */
 129#define A_NETMASK        0x20   /* Set if netmask (check for multiple sets). */
 130#define A_SET_AFTER      0x40   /* Set a flag at the end. */
 131#define A_COLON_CHK      0x80   /* Is this needed?  See below. */
 132#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 133#define A_HOSTNAME      0x100   /* Set if it is ip addr. */
 134#define A_BROADCAST     0x200   /* Set if it is broadcast addr. */
 135#else
 136#define A_HOSTNAME          0
 137#define A_BROADCAST         0
 138#endif
 139
 140/*
 141 * These defines are for dealing with the A_CAST_TYPE field.
 142 */
 143#define A_CAST_CHAR_PTR  0x01
 144#define A_CAST_RESOLVE   0x01
 145#define A_CAST_HOST_COPY 0x02
 146#define A_CAST_HOST_COPY_IN_ETHER    A_CAST_HOST_COPY
 147#define A_CAST_HOST_COPY_RESOLVE     (A_CAST_HOST_COPY | A_CAST_RESOLVE)
 148
 149/*
 150 * These defines are for dealing with the A_MAP_TYPE field.
 151 */
 152#define A_MAP_ULONG      0x04   /* memstart */
 153#define A_MAP_USHORT     0x08   /* io_addr */
 154#define A_MAP_UCHAR      0x0C   /* irq */
 155
 156/*
 157 * Define the bit masks signifying which operations to perform for each arg.
 158 */
 159
 160#define ARG_METRIC       (A_ARG_REQ /*| A_CAST_INT*/)
 161#define ARG_MTU          (A_ARG_REQ /*| A_CAST_INT*/)
 162#define ARG_TXQUEUELEN   (A_ARG_REQ /*| A_CAST_INT*/)
 163#define ARG_MEM_START    (A_ARG_REQ | A_MAP_ULONG)
 164#define ARG_IO_ADDR      (A_ARG_REQ | A_MAP_ULONG)
 165#define ARG_IRQ          (A_ARG_REQ | A_MAP_UCHAR)
 166#define ARG_DSTADDR      (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE)
 167#define ARG_NETMASK      (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE | A_NETMASK)
 168#define ARG_BROADCAST    (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER | A_BROADCAST)
 169#define ARG_HW           (A_ARG_REQ | A_CAST_HOST_COPY_IN_ETHER)
 170#define ARG_POINTOPOINT  (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER)
 171#define ARG_KEEPALIVE    (A_ARG_REQ | A_CAST_CHAR_PTR)
 172#define ARG_OUTFILL      (A_ARG_REQ | A_CAST_CHAR_PTR)
 173#define ARG_HOSTNAME     (A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER | A_COLON_CHK | A_HOSTNAME)
 174#define ARG_ADD_DEL      (A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER)
 175
 176
 177struct arg1opt {
 178        const char *name;
 179        unsigned short selector;
 180        unsigned short ifr_offset;
 181};
 182
 183struct options {
 184        const char *name;
 185#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 186        const unsigned int flags:6;
 187        const unsigned int arg_flags:10;
 188#else
 189        const unsigned char flags;
 190        const unsigned char arg_flags;
 191#endif
 192        const unsigned short selector;
 193};
 194
 195#define ifreq_offsetof(x)  offsetof(struct ifreq, x)
 196
 197/*
 198 * Set up the tables.  Warning!  They must have corresponding order!
 199 */
 200
 201static const struct arg1opt Arg1Opt[] = {
 202        { "SIFMETRIC",  SIOCSIFMETRIC,  ifreq_offsetof(ifr_metric) },
 203        { "SIFMTU",     SIOCSIFMTU,     ifreq_offsetof(ifr_mtu) },
 204        { "SIFTXQLEN",  SIOCSIFTXQLEN,  ifreq_offsetof(ifr_qlen) },
 205        { "SIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr) },
 206        { "SIFNETMASK", SIOCSIFNETMASK, ifreq_offsetof(ifr_netmask) },
 207        { "SIFBRDADDR", SIOCSIFBRDADDR, ifreq_offsetof(ifr_broadaddr) },
 208#if ENABLE_FEATURE_IFCONFIG_HW
 209        { "SIFHWADDR",  SIOCSIFHWADDR,  ifreq_offsetof(ifr_hwaddr) },
 210#endif
 211        { "SIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr) },
 212#ifdef SIOCSKEEPALIVE
 213        { "SKEEPALIVE", SIOCSKEEPALIVE, ifreq_offsetof(ifr_data) },
 214#endif
 215#ifdef SIOCSOUTFILL
 216        { "SOUTFILL",   SIOCSOUTFILL,   ifreq_offsetof(ifr_data) },
 217#endif
 218#if ENABLE_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 219        { "SIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.mem_start) },
 220        { "SIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.base_addr) },
 221        { "SIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.irq) },
 222#endif
 223#if ENABLE_FEATURE_IPV6
 224        { "SIFADDR",    SIOCSIFADDR,    ifreq_offsetof(ifr_addr) }, /* IPv6 version ignores the offset */
 225        { "DIFADDR",    SIOCDIFADDR,    ifreq_offsetof(ifr_addr) }, /* IPv6 version ignores the offset */
 226#endif
 227        /* Last entry is for unmatched (assumed to be hostname/address) arg. */
 228        { "SIFADDR",    SIOCSIFADDR,    ifreq_offsetof(ifr_addr) },
 229};
 230
 231static const struct options OptArray[] = {
 232        { "metric",      N_ARG,         ARG_METRIC,      0 },
 233        { "mtu",         N_ARG,         ARG_MTU,         0 },
 234        { "txqueuelen",  N_ARG,         ARG_TXQUEUELEN,  0 },
 235        { "dstaddr",     N_ARG,         ARG_DSTADDR,     0 },
 236        { "netmask",     N_ARG,         ARG_NETMASK,     0 },
 237        { "broadcast",   N_ARG | M_CLR, ARG_BROADCAST,   IFF_BROADCAST },
 238#if ENABLE_FEATURE_IFCONFIG_HW
 239        { "hw",          N_ARG,         ARG_HW,          0 },
 240#endif
 241        { "pointopoint", N_ARG | M_CLR, ARG_POINTOPOINT, IFF_POINTOPOINT },
 242#ifdef SIOCSKEEPALIVE
 243        { "keepalive",   N_ARG,         ARG_KEEPALIVE,   0 },
 244#endif
 245#ifdef SIOCSOUTFILL
 246        { "outfill",     N_ARG,         ARG_OUTFILL,     0 },
 247#endif
 248#if ENABLE_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 249        { "mem_start",   N_ARG,         ARG_MEM_START,   0 },
 250        { "io_addr",     N_ARG,         ARG_IO_ADDR,     0 },
 251        { "irq",         N_ARG,         ARG_IRQ,         0 },
 252#endif
 253#if ENABLE_FEATURE_IPV6
 254        { "add",         N_ARG,         ARG_ADD_DEL,     0 },
 255        { "del",         N_ARG,         ARG_ADD_DEL,     0 },
 256#endif
 257        { "arp",         N_CLR | M_SET, 0,               IFF_NOARP },
 258        { "trailers",    N_CLR | M_SET, 0,               IFF_NOTRAILERS },
 259        { "promisc",     N_SET | M_CLR, 0,               IFF_PROMISC },
 260        { "multicast",   N_SET | M_CLR, 0,               IFF_MULTICAST },
 261        { "allmulti",    N_SET | M_CLR, 0,               IFF_ALLMULTI },
 262        { "dynamic",     N_SET | M_CLR, 0,               IFF_DYNAMIC },
 263        { "up",          N_SET,         0,               (IFF_UP | IFF_RUNNING) },
 264        { "down",        N_CLR,         0,               IFF_UP },
 265        { NULL,          0,             ARG_HOSTNAME,    (IFF_UP | IFF_RUNNING) }
 266};
 267
 268int ifconfig_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 269int ifconfig_main(int argc UNUSED_PARAM, char **argv)
 270{
 271        struct ifreq ifr;
 272        struct sockaddr_in sai;
 273#if ENABLE_FEATURE_IFCONFIG_HW
 274        struct sockaddr sa;
 275#endif
 276        const struct arg1opt *a1op;
 277        const struct options *op;
 278        int sockfd;                     /* socket fd we use to manipulate stuff with */
 279        int selector;
 280#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 281        unsigned int mask;
 282        unsigned int did_flags;
 283        unsigned int sai_hostname, sai_netmask;
 284#else
 285        unsigned char mask;
 286        unsigned char did_flags;
 287#endif
 288        char *p;
 289        /*char host[128];*/
 290        const char *host = NULL; /* make gcc happy */
 291
 292        did_flags = 0;
 293#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 294        sai_hostname = 0;
 295        sai_netmask = 0;
 296#endif
 297
 298        /* skip argv[0] */
 299        ++argv;
 300
 301#if ENABLE_FEATURE_IFCONFIG_STATUS
 302        if (argv[0] && (argv[0][0] == '-' && argv[0][1] == 'a' && !argv[0][2])) {
 303                interface_opt_a = 1;
 304                ++argv;
 305        }
 306#endif
 307
 308        if (!argv[0] || !argv[1]) { /* one or no args */
 309#if ENABLE_FEATURE_IFCONFIG_STATUS
 310                return display_interfaces(argv[0] /* can be NULL */);
 311#else
 312                bb_error_msg_and_die("no support for status display");
 313#endif
 314        }
 315
 316        /* Create a channel to the NET kernel. */
 317        sockfd = xsocket(AF_INET, SOCK_DGRAM, 0);
 318
 319        /* get interface name */
 320        strncpy_IFNAMSIZ(ifr.ifr_name, *argv);
 321
 322        /* Process the remaining arguments. */
 323        while (*++argv != NULL) {
 324                p = *argv;
 325                mask = N_MASK;
 326                if (*p == '-') {        /* If the arg starts with '-'... */
 327                        ++p;            /*    advance past it and */
 328                        mask = M_MASK;  /*    set the appropriate mask. */
 329                }
 330                for (op = OptArray; op->name; op++) {   /* Find table entry. */
 331                        if (strcmp(p, op->name) == 0) { /* If name matches... */
 332                                mask &= op->flags;
 333                                if (mask)       /* set the mask and go. */
 334                                        goto FOUND_ARG;
 335                                /* If we get here, there was a valid arg with an */
 336                                /* invalid '-' prefix. */
 337                                bb_error_msg_and_die("bad: '%s'", p-1);
 338                        }
 339                }
 340
 341                /* We fell through, so treat as possible hostname. */
 342                a1op = Arg1Opt + ARRAY_SIZE(Arg1Opt) - 1;
 343                mask = op->arg_flags;
 344                goto HOSTNAME;
 345
 346 FOUND_ARG:
 347                if (mask & ARG_MASK) {
 348                        mask = op->arg_flags;
 349                        if (mask & A_NETMASK & did_flags)
 350                                bb_show_usage();
 351                        a1op = Arg1Opt + (op - OptArray);
 352                        if (*++argv == NULL) {
 353                                if (mask & A_ARG_REQ)
 354                                        bb_show_usage();
 355                                --argv;
 356                                mask &= A_SET_AFTER;    /* just for broadcast */
 357                        } else {        /* got an arg so process it */
 358 HOSTNAME:
 359                                did_flags |= (mask & (A_NETMASK|A_HOSTNAME));
 360                                if (mask & A_CAST_HOST_COPY) {
 361#if ENABLE_FEATURE_IFCONFIG_HW
 362                                        if (mask & A_CAST_RESOLVE) {
 363#endif
 364                                                host = *argv;
 365                                                if (strcmp(host, "inet") == 0)
 366                                                        continue; /* compat stuff */
 367                                                sai.sin_family = AF_INET;
 368                                                sai.sin_port = 0;
 369                                                if (strcmp(host, "default") == 0) {
 370                                                        /* Default is special, meaning 0.0.0.0. */
 371                                                        sai.sin_addr.s_addr = INADDR_ANY;
 372                                                }
 373#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 374                                                else if ((host[0] == '+' && !host[1])
 375                                                 && (mask & A_BROADCAST)
 376                                                 && (did_flags & (A_NETMASK|A_HOSTNAME)) == (A_NETMASK|A_HOSTNAME)
 377                                                ) {
 378                                                        /* + is special, meaning broadcast is derived. */
 379                                                        sai.sin_addr.s_addr = (~sai_netmask) | (sai_hostname & sai_netmask);
 380                                                }
 381#endif
 382                                                else {
 383                                                        len_and_sockaddr *lsa;
 384#if ENABLE_FEATURE_IPV6
 385                                                        char *prefix;
 386                                                        int prefix_len = 0;
 387                                                        prefix = strchr(host, '/');
 388                                                        if (prefix) {
 389                                                                prefix_len = xatou_range(prefix + 1, 0, 128);
 390                                                                *prefix = '\0';
 391                                                        }
 392 resolve:
 393#endif
 394                                                        lsa = xhost2sockaddr(host, 0);
 395#if ENABLE_FEATURE_IPV6
 396                                                        if (lsa->u.sa.sa_family != AF_INET6 && prefix) {
 397/* TODO: we do not support "ifconfig eth0 up 1.2.3.4/17".
 398 * For now, just make it fail instead of silently ignoring "/17" part:
 399 */
 400                                                                *prefix = '/';
 401                                                                goto resolve;
 402                                                        }
 403                                                        if (lsa->u.sa.sa_family == AF_INET6) {
 404                                                                int sockfd6;
 405                                                                struct in6_ifreq ifr6;
 406
 407                                                                sockfd6 = xsocket(AF_INET6, SOCK_DGRAM, 0);
 408                                                                xioctl(sockfd6, SIOCGIFINDEX, &ifr);
 409                                                                ifr6.ifr6_ifindex = ifr.ifr_ifindex;
 410                                                                ifr6.ifr6_prefixlen = prefix_len;
 411                                                                memcpy(&ifr6.ifr6_addr,
 412                                                                                &lsa->u.sin6.sin6_addr,
 413                                                                                sizeof(struct in6_addr));
 414                                                                ioctl_or_perror_and_die(sockfd6, a1op->selector, &ifr6, "SIOC%s", a1op->name);
 415                                                                if (ENABLE_FEATURE_CLEAN_UP)
 416                                                                        free(lsa);
 417                                                                continue;
 418                                                        }
 419#endif
 420                                                        sai.sin_addr = lsa->u.sin.sin_addr;
 421                                                        if (ENABLE_FEATURE_CLEAN_UP)
 422                                                                free(lsa);
 423                                                }
 424#if ENABLE_FEATURE_IFCONFIG_BROADCAST_PLUS
 425                                                if (mask & A_HOSTNAME)
 426                                                        sai_hostname = sai.sin_addr.s_addr;
 427                                                if (mask & A_NETMASK)
 428                                                        sai_netmask = sai.sin_addr.s_addr;
 429#endif
 430                                                p = (char *) &sai;
 431#if ENABLE_FEATURE_IFCONFIG_HW
 432                                        } else {        /* A_CAST_HOST_COPY_IN_ETHER */
 433                                                /* This is the "hw" arg case. */
 434                                                smalluint hw_class = index_in_substrings("ether\0"
 435                                                                IF_FEATURE_HWIB("infiniband\0"), *argv) + 1;
 436                                                if (!hw_class || !*++argv)
 437                                                        bb_show_usage();
 438                                                host = *argv;
 439                                                if (hw_class == 1 ? in_ether(host, &sa) : in_ib(host, &sa))
 440                                                        bb_error_msg_and_die("invalid hw-addr %s", host);
 441                                                p = (char *) &sa;
 442                                        }
 443#endif
 444                                        memcpy( ((char *)&ifr) + a1op->ifr_offset,
 445                                                p, sizeof(struct sockaddr));
 446                                } else {
 447                                        /* FIXME: error check?? */
 448                                        unsigned long i = strtoul(*argv, NULL, 0);
 449                                        p = ((char *)&ifr) + a1op->ifr_offset;
 450#if ENABLE_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 451                                        if (mask & A_MAP_TYPE) {
 452                                                xioctl(sockfd, SIOCGIFMAP, &ifr);
 453                                                if ((mask & A_MAP_UCHAR) == A_MAP_UCHAR)
 454                                                        *(unsigned char *) p = i;
 455                                                else if (mask & A_MAP_USHORT)
 456                                                        *(unsigned short *) p = i;
 457                                                else
 458                                                        *(unsigned long *) p = i;
 459                                        } else
 460#endif
 461                                        if (mask & A_CAST_CHAR_PTR)
 462                                                *(caddr_t *) p = (caddr_t) i;
 463                                        else    /* A_CAST_INT */
 464                                                *(int *) p = i;
 465                                }
 466
 467                                ioctl_or_perror_and_die(sockfd, a1op->selector, &ifr, "SIOC%s", a1op->name);
 468#ifdef QUESTIONABLE_ALIAS_CASE
 469                                if (mask & A_COLON_CHK) {
 470                                        /*
 471                                         * Don't do the set_flag() if the address is an alias with
 472                                         * a '-' at the end, since it's deleted already! - Roman
 473                                         *
 474                                         * Should really use regex.h here, not sure though how well
 475                                         * it'll go with the cross-platform support etc.
 476                                         */
 477                                        char *ptr;
 478                                        short int found_colon = 0;
 479                                        for (ptr = ifr.ifr_name; *ptr; ptr++)
 480                                                if (*ptr == ':')
 481                                                        found_colon++;
 482                                        if (found_colon && ptr[-1] == '-')
 483                                                continue;
 484                                }
 485#endif
 486                        }
 487                        if (!(mask & A_SET_AFTER))
 488                                continue;
 489                        mask = N_SET;
 490                } /* if (mask & ARG_MASK) */
 491
 492                xioctl(sockfd, SIOCGIFFLAGS, &ifr);
 493                selector = op->selector;
 494                if (mask & SET_MASK)
 495                        ifr.ifr_flags |= selector;
 496                else
 497                        ifr.ifr_flags &= ~selector;
 498                xioctl(sockfd, SIOCSIFFLAGS, &ifr);
 499        } /* while () */
 500
 501        if (ENABLE_FEATURE_CLEAN_UP)
 502                close(sockfd);
 503        return 0;
 504}
 505