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      1 /* ifconfig.c - Configure network interface.
      2  *
      3  * Copyright 2012 Ranjan Kumar <ranjankumar.bth (at) gmail.com>
      4  * Copyright 2012 Kyungwan Han <asura321 (at) gamil.com>
      5  * Reviewed by Kyungsu Kim <kaspyx (at) gmail.com>
      6  *
      7  * Not in SUSv4.
      8  *
      9  * Obsolete fields included for historical purposes:
     10  * irq|io_addr|mem_start ADDR - micromanage obsolete hardware
     11  * outfill|keepalive INTEGER - SLIP analog dialup line quality monitoring
     12  * metric INTEGER - added to Linux 0.9.10 with comment "never used", still true
     13 
     14 USE_IFCONFIG(NEWTOY(ifconfig, "^?aS", TOYFLAG_SBIN))
     15 
     16 config IFCONFIG
     17   bool "ifconfig"
     18   default y
     19   help
     20     usage: ifconfig [-aS] [INTERFACE [ACTION...]]
     21 
     22     Display or configure network interface.
     23 
     24     With no arguments, display active interfaces. First argument is interface
     25     to operate on, one argument by itself displays that interface.
     26 
     27     -a	All interfaces displayed, not just active ones
     28     -S	Short view, one line per interface
     29 
     30     Standard ACTIONs to perform on an INTERFACE:
     31 
     32     ADDR[/MASK]        - set IPv4 address (1.2.3.4/5) and activate interface
     33     add|del ADDR[/LEN] - add/remove IPv6 address (1111::8888/128)
     34     up|down            - activate or deactivate interface
     35 
     36     Advanced ACTIONs (default values usually suffice):
     37 
     38     default          - remove IPv4 address
     39     netmask ADDR     - set IPv4 netmask via 255.255.255.0 instead of /24
     40     txqueuelen LEN   - number of buffered packets before output blocks
     41     mtu LEN          - size of outgoing packets (Maximum Transmission Unit)
     42     broadcast ADDR   - Set broadcast address
     43     pointopoint ADDR - PPP and PPPOE use this instead of "route add default gw"
     44     hw TYPE ADDR     - set hardware (mac) address (type = ether|infiniband)
     45 
     46     Flags you can set on an interface (or -remove by prefixing with -):
     47 
     48     arp       - don't use Address Resolution Protocol to map LAN routes
     49     promisc   - don't discard packets that aren't to this LAN hardware address
     50     multicast - force interface into multicast mode if the driver doesn't
     51     allmulti  - promisc for multicast packets
     52 */
     53 
     54 #define FOR_ifconfig
     55 #include "toys.h"
     56 
     57 #include <net/if_arp.h>
     58 #include <net/ethernet.h>
     59 
     60 GLOBALS(
     61   int sockfd;
     62 )
     63 
     64 // Convert hostname to binary address for AF_INET or AF_INET6
     65 // return /prefix (or range max if none)
     66 static int get_addrinfo(char *host, sa_family_t af, void *addr)
     67 {
     68   struct addrinfo hints, *result, *rp = 0;
     69   int status, len;
     70   char *from, *slash;
     71 
     72   memset(&hints, 0 , sizeof(struct addrinfo));
     73   hints.ai_family = af;
     74   hints.ai_socktype = SOCK_STREAM;
     75 
     76   slash = strchr(host, '/');
     77   if (slash) *slash = 0;
     78 
     79   status = getaddrinfo(host, NULL, &hints, &result);
     80   if (!status)
     81     for (rp = result; rp; rp = rp->ai_next)
     82       if (rp->ai_family == af) break;
     83   if (!rp) error_exit("bad address '%s' : %s", host, gai_strerror(status));
     84 
     85   // ai_addr isn't struct in_addr or in6_addr, it's struct sockaddr. Of course.
     86   // You'd think ipv4 and ipv6 would have some basic compatibility, but no.
     87   from = ((char *)rp->ai_addr) + 4;
     88   if (af == AF_INET6) {
     89     len = 16;
     90     from += 4;  // skip "flowinfo" field ipv6 puts before address
     91   } else len = 4;
     92   memcpy(addr, from, len);
     93   freeaddrinfo(result);
     94 
     95   len = -1;
     96   if (slash) len = atolx_range(slash+1, 0, (af == AF_INET) ? 32 : 128);
     97 
     98   return len;
     99 }
    100 
    101 static void display_ifconfig(char *name, int always, unsigned long long val[])
    102 {
    103   struct ifreq ifre;
    104   struct sockaddr_in *si = (void *)&ifre.ifr_addr;
    105   struct {
    106     int type;
    107     char *title;
    108   } types[] = {
    109     {ARPHRD_LOOPBACK, "Local Loopback"}, {ARPHRD_ETHER, "Ethernet"},
    110     {ARPHRD_PPP, "Point-to-Point Protocol"}, {ARPHRD_INFINIBAND, "InfiniBand"},
    111     {ARPHRD_SIT, "IPv6-in-IPv4"}, {-1, "UNSPEC"}
    112   };
    113   int i;
    114   char *pp;
    115   FILE *fp;
    116   short flags;
    117 
    118   xstrncpy(ifre.ifr_name, name, IFNAMSIZ);
    119   if (ioctl(TT.sockfd, SIOCGIFFLAGS, &ifre)<0) perror_exit_raw(name);
    120   flags = ifre.ifr_flags;
    121   if (!always && !(flags & IFF_UP)) return;
    122 
    123   if (toys.optflags&FLAG_S) {
    124     unsigned uu = 0;
    125     int len;
    126 
    127     ioctl(TT.sockfd, SIOCGIFADDR, &ifre);
    128     len = printf("%*s %s", -9, name, inet_ntoa(si->sin_addr));
    129     if (!ioctl(TT.sockfd, SIOCGIFNETMASK, &ifre))
    130       uu = htonl(*(unsigned *)&(si->sin_addr));
    131     for (i = 0; uu; i++) uu <<= 1;
    132     len += printf("/%d", i);
    133     printf("%*c", 29-len, ' ');
    134   }
    135 
    136   // query hardware type and hardware address
    137   xioctl(TT.sockfd, SIOCGIFHWADDR, &ifre);
    138 
    139   if (toys.optflags&FLAG_S)
    140     for (i=0; i<6; i++) printf(":%02x"+!i, ifre.ifr_hwaddr.sa_data[i]);
    141   else {
    142     for (i=0; i < ARRAY_LEN(types)-1; i++)
    143       if (ifre.ifr_hwaddr.sa_family == types[i].type) break;
    144     xprintf("%-9s Link encap:%s  ", name, types[i].title);
    145     if(ifre.ifr_hwaddr.sa_family == ARPHRD_ETHER) {
    146       xprintf("HWaddr ");
    147       for (i=0; i<6; i++) xprintf(":%02x"+!i, ifre.ifr_hwaddr.sa_data[i]);
    148     }
    149     sprintf(toybuf, "/sys/class/net/%.15s/device/driver", name);
    150     if (readlink0(toybuf, toybuf, sizeof(toybuf))>0)
    151       if ((pp = strrchr(toybuf, '/'))) xprintf("  Driver %s", pp+1);
    152     xputc('\n');
    153   }
    154 
    155   // If an address is assigned record that.
    156 
    157   ifre.ifr_addr.sa_family = AF_INET;
    158   memset(&ifre.ifr_addr, 0, sizeof(ifre.ifr_addr));
    159   ioctl(TT.sockfd, SIOCGIFADDR, &ifre);
    160   pp = (char *)&ifre.ifr_addr;
    161   for (i = 0; i<sizeof(ifre.ifr_addr); i++) if (pp[i]) break;
    162 
    163   if (!(toys.optflags&FLAG_S) && i != sizeof(ifre.ifr_addr)) {
    164     struct sockaddr_in *si = (struct sockaddr_in *)&ifre.ifr_addr;
    165     struct {
    166       char *name;
    167       int flag, ioctl;
    168     } addr[] = {
    169       {"addr", 0, 0},
    170       {"P-t-P", IFF_POINTOPOINT, SIOCGIFDSTADDR},
    171       {"Bcast", IFF_BROADCAST, SIOCGIFBRDADDR},
    172       {"Mask", 0, SIOCGIFNETMASK}
    173     };
    174 
    175     // TODO: can this be ipv6? Why are we checking here when ipv6 source later?
    176     xprintf("%10c%s", ' ', (si->sin_family == AF_INET) ? "inet" :
    177         (si->sin_family == AF_INET6) ? "inet6" : "unspec");
    178 
    179     for (i=0; i<ARRAY_LEN(addr); i++) {
    180       if (!addr[i].flag || (flags & addr[i].flag)) {
    181         if (addr[i].ioctl && ioctl(TT.sockfd, addr[i].ioctl, &ifre))
    182           si->sin_family = 0;
    183         xprintf(" %s:%s ", addr[i].name,
    184           (si->sin_family == 0xFFFF || !si->sin_family)
    185             ? "[NOT SET]" : inet_ntoa(si->sin_addr));
    186       }
    187     }
    188 
    189     xputc('\n');
    190   }
    191 
    192   fp = fopen(pp = "/proc/net/if_inet6", "r");
    193   if (fp) {
    194     char iface_name[IFNAMSIZ];
    195     int plen, iscope;
    196 
    197     while (fgets(toybuf, sizeof(toybuf), fp)) {
    198       int nitems;
    199       char ipv6_addr[40];
    200 
    201       nitems = sscanf(toybuf, "%32s %*08x %02x %02x %*02x %15s\n",
    202                       ipv6_addr, &plen, &iscope, iface_name);
    203       if (nitems<0 && feof(fp)) break;
    204       if (nitems != 4) perror_exit("bad %s", pp);
    205 
    206       if (!strcmp(name, iface_name)) {
    207         struct sockaddr_in6 s6;
    208         char *ptr = ipv6_addr+sizeof(ipv6_addr)-1;
    209 
    210         // convert giant hex string into colon-spearated ipv6 address by
    211         // inserting ':' every 4 characters.
    212         for (i = 32; i; i--)
    213           if ((*(ptr--) = ipv6_addr[i])) if (!(i&3)) *(ptr--) = ':';
    214 
    215         // Convert to binary and back to get abbreviated :: version
    216         if (inet_pton(AF_INET6, ipv6_addr, (void *)&s6.sin6_addr) > 0) {
    217           if (inet_ntop(AF_INET6, &s6.sin6_addr, toybuf, sizeof(toybuf))) {
    218             char *scopes[] = {"Global","Host","Link","Site","Compat"},
    219                  *scope = "Unknown";
    220 
    221             for (i=0; i<ARRAY_LEN(scopes); i++)
    222               if (iscope == (!!i)<<(i+3)) scope = scopes[i];
    223             if (toys.optflags&FLAG_S) xprintf(" %s/%d@%c", toybuf, plen,*scope);
    224             else xprintf("%10cinet6 addr: %s/%d Scope: %s\n",
    225                          ' ', toybuf, plen, scope);
    226           }
    227         }
    228       }
    229     }
    230     fclose(fp);
    231   }
    232 
    233   if (toys.optflags&FLAG_S) {
    234     xputc('\n');
    235     return;
    236   }
    237 
    238   xprintf("%10c", ' ');
    239 
    240   if (flags) {
    241     unsigned short mask = 1;
    242     char **s, *str[] = {
    243       "UP", "BROADCAST", "DEBUG", "LOOPBACK", "POINTOPOINT", "NOTRAILERS",
    244       "RUNNING", "NOARP", "PROMISC", "ALLMULTI", "MASTER", "SLAVE", "MULTICAST",
    245       "PORTSEL", "AUTOMEDIA", "DYNAMIC", NULL
    246     };
    247 
    248     for (s = str; *s; s++) {
    249       if (flags & mask) xprintf("%s ", *s);
    250       mask = mask << 1;
    251     }
    252   } else xprintf("[NO FLAGS] ");
    253 
    254   if (ioctl(TT.sockfd, SIOCGIFMTU, &ifre) < 0) ifre.ifr_mtu = 0;
    255   xprintf(" MTU:%d", ifre.ifr_mtu);
    256   if (ioctl(TT.sockfd, SIOCGIFMETRIC, &ifre) < 0) ifre.ifr_metric = 0;
    257   if (!ifre.ifr_metric) ifre.ifr_metric = 1;
    258   xprintf("  Metric:%d", ifre.ifr_metric);
    259 
    260   // non-virtual interface
    261 
    262   if (val) {
    263     char *label[] = {"RX bytes", "RX packets", "errors", "dropped", "overruns",
    264       "frame", 0, 0, "TX bytes", "TX packets", "errors", "dropped", "overruns",
    265       "collisions", "carrier", 0, "txqueuelen"};
    266     signed char order[] = {-1, 1, 2, 3, 4, 5, -1, 9, 10, 11, 12, 14, -1,
    267       13, 16, -1, 0, 8};
    268     int i;
    269 
    270     // Query txqueuelen
    271     if (ioctl(TT.sockfd, SIOCGIFTXQLEN, &ifre) >= 0) val[16] = ifre.ifr_qlen;
    272     else val[16] = -1;
    273 
    274     for (i = 0; i<sizeof(order); i++) {
    275       int j = order[i];
    276 
    277       if (j < 0) xprintf("\n%10c", ' ');
    278       else xprintf("%s:%llu ", label[j], val[j]);
    279     }
    280   }
    281   xputc('\n');
    282 
    283   if(!ioctl(TT.sockfd, SIOCGIFMAP, &ifre) && (ifre.ifr_map.irq ||
    284       ifre.ifr_map.mem_start || ifre.ifr_map.dma || ifre.ifr_map.base_addr))
    285   {
    286     xprintf("%10c", ' ');
    287     if(ifre.ifr_map.irq) xprintf("Interrupt:%d ", ifre.ifr_map.irq);
    288     if(ifre.ifr_map.base_addr >= 0x100) // IO_MAP_INDEX
    289       xprintf("Base address:0x%x ", ifre.ifr_map.base_addr);
    290     if(ifre.ifr_map.mem_start)
    291       xprintf("Memory:%lx-%lx ", ifre.ifr_map.mem_start, ifre.ifr_map.mem_end);
    292     if(ifre.ifr_map.dma) xprintf("DMA chan:%x ", ifre.ifr_map.dma);
    293     xputc('\n');
    294   }
    295   xputc('\n');
    296 }
    297 
    298 static void show_iface(char *iface_name)
    299 {
    300   char *name;
    301   struct string_list *ifaces = 0, *sl;
    302   int i, j;
    303   FILE *fp;
    304 
    305   fp = xfopen("/proc/net/dev", "r");
    306 
    307   for (i=0; fgets(toybuf, sizeof(toybuf), fp); i++) {
    308     char *buf = toybuf;
    309     unsigned long long val[17];
    310 
    311     if (i<2) continue;
    312 
    313     while (isspace(*buf)) buf++;
    314     name = strsep(&buf, ":");
    315     if(!buf) error_exit("bad name %s", name);
    316 
    317     errno = 0;
    318     for (j=0; j<16 && !errno; j++) val[j] = strtoll(buf, &buf, 0);
    319     if (errno) perror_exit("bad %s at %s", name, buf);
    320 
    321     if (iface_name) {
    322       if (!strcmp(iface_name, name)) {
    323         display_ifconfig(iface_name, 1, val);
    324 
    325         return;
    326       }
    327     } else {
    328       sl = xmalloc(sizeof(*sl)+strlen(name)+1);
    329       strcpy(sl->str, name);
    330       sl->next = ifaces;
    331       ifaces = sl;
    332 
    333       display_ifconfig(sl->str, toys.optflags & FLAG_a, val);
    334     }
    335   }
    336   fclose(fp);
    337 
    338   if (iface_name) display_ifconfig(iface_name, 1, 0);
    339   else {
    340     struct ifconf ifcon;
    341     struct ifreq *ifre;
    342     int num;
    343 
    344     // Loop until buffer's big enough
    345     ifcon.ifc_buf = NULL;
    346     for (num = 30;;num += 10) {
    347       ifcon.ifc_len = sizeof(struct ifreq)*num;
    348       ifcon.ifc_buf = xrealloc(ifcon.ifc_buf, ifcon.ifc_len);
    349       xioctl(TT.sockfd, SIOCGIFCONF, &ifcon);
    350       if (ifcon.ifc_len != sizeof(struct ifreq)*num) break;
    351     }
    352 
    353     ifre = ifcon.ifc_req;
    354     for(num = 0; num < ifcon.ifc_len && ifre; num += sizeof(struct ifreq), ifre++)
    355     {
    356       // Skip duplicates
    357       for(sl = ifaces; sl; sl = sl->next)
    358         if(!strcmp(sl->str, ifre->ifr_name)) break;
    359 
    360       if(!sl) display_ifconfig(ifre->ifr_name, toys.optflags & FLAG_a, 0);
    361     }
    362 
    363     free(ifcon.ifc_buf);
    364   }
    365 
    366   llist_traverse(ifaces, free);
    367 }
    368 
    369 // Encode offset and size of field into an int, and make result negative
    370 #define IFREQ_OFFSZ(x) -(int)((offsetof(struct ifreq, x)<<16) + sizeof(ifre.x))
    371 
    372 void ifconfig_main(void)
    373 {
    374   char **argv = toys.optargs;
    375   struct ifreq ifre;
    376   int i;
    377 
    378   TT.sockfd = xsocket(AF_INET, SOCK_DGRAM, 0);
    379   if(toys.optc < 2) {
    380     show_iface(*argv);
    381     return;
    382   }
    383 
    384   // Open interface
    385   memset(&ifre, 0, sizeof(struct ifreq));
    386   xstrncpy(ifre.ifr_name, *argv, IFNAMSIZ);
    387 
    388   // Perform operations on interface
    389   while(*++argv) {
    390     // Table of known operations
    391     struct argh {
    392       char *name;
    393       int on, off; // set, clear
    394     } try[] = {
    395       {0, IFF_UP|IFF_RUNNING, SIOCSIFADDR},
    396       {"up", IFF_UP|IFF_RUNNING, 0},
    397       {"down", 0, IFF_UP},
    398       {"arp", 0, IFF_NOARP},
    399       {"promisc", IFF_PROMISC, 0},
    400       {"allmulti", IFF_ALLMULTI, 0},
    401       {"multicast", IFF_MULTICAST, 0},
    402       {"pointopoint", IFF_POINTOPOINT, SIOCSIFDSTADDR},
    403       {"broadcast", IFF_BROADCAST, SIOCSIFBRDADDR},
    404       {"netmask", 0, SIOCSIFNETMASK},
    405       {"dstaddr", 0, SIOCSIFDSTADDR},
    406       {"mtu", IFREQ_OFFSZ(ifr_mtu), SIOCSIFMTU},
    407       {"keepalive", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE}, // SIOCSKEEPALIVE
    408       {"outfill", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE+2}, // SIOCSOUTFILL
    409       {"metric", IFREQ_OFFSZ(ifr_metric), SIOCSIFMETRIC},
    410       {"txqueuelen", IFREQ_OFFSZ(ifr_qlen), SIOCSIFTXQLEN},
    411       {"mem_start", IFREQ_OFFSZ(ifr_map.mem_start), SIOCSIFMAP},
    412       {"io_addr", IFREQ_OFFSZ(ifr_map.base_addr), SIOCSIFMAP},
    413       {"irq", IFREQ_OFFSZ(ifr_map.irq), SIOCSIFMAP},
    414       {"inet", 0, 0},
    415       {"inet6", 0, 0}
    416     };
    417     char *s = *argv;
    418     int rev = (*s == '-');
    419 
    420     s += rev;
    421 
    422     // "set hardware address" is oddball enough to special case
    423     if (!strcmp(*argv, "hw")) {
    424       char *hw_addr, *ptr, *p;
    425       struct sockaddr *sock = &ifre.ifr_hwaddr;
    426       int count = 6;
    427 
    428       ptr = p = (char *)sock->sa_data;
    429       memset(sock, 0, sizeof(struct sockaddr));
    430       if (argv[1]) {
    431         if (!strcmp("ether", *++argv)) sock->sa_family = ARPHRD_ETHER;
    432         else if (!strcmp("infiniband", *argv)) {
    433           sock->sa_family = ARPHRD_INFINIBAND;
    434           count = 20;
    435           p = ptr = toybuf;
    436         }
    437       }
    438       if (!sock->sa_family || !argv[1]) help_exit("bad hw '%s'", *argv);
    439       hw_addr = *++argv;
    440 
    441       // Parse and verify address.
    442       while (*hw_addr && (p-ptr) < count) {
    443         int val, len = 0;
    444 
    445         if (*hw_addr == ':') hw_addr++;
    446         sscanf(hw_addr, "%2x%n", &val, &len);
    447         if (!len || len > 2) break; // 1 nibble can be set e.g. C2:79:38:95:D:A
    448         hw_addr += len;
    449         *p++ = val;
    450       }
    451 
    452       if ((p-ptr) != count || *hw_addr)
    453         error_exit("bad hw-addr '%s'", *argv);
    454 
    455       // the linux kernel's "struct sockaddr" (include/linux/socket.h in the
    456       // kernel source) only has 14 bytes of sa_data, and an infiniband address
    457       // is 20. So if we go through the ioctl, the kernel will truncate
    458       // infiniband addresses, meaning we have to go through sysfs instead.
    459       if (sock->sa_family == ARPHRD_INFINIBAND && !strchr(ifre.ifr_name, '/')) {
    460         int fd;
    461 
    462         sprintf(toybuf, "/sys/class/net/%s/address", ifre.ifr_name);
    463         fd = xopen(toybuf, O_RDWR);
    464         xwrite(fd, *argv, strlen(*argv));
    465         close(fd);
    466       } else xioctl(TT.sockfd, SIOCSIFHWADDR, &ifre);
    467       continue;
    468 
    469     // Add/remove ipv6 address to interface
    470 
    471     } else if (!strcmp(*argv, "add") || !strcmp(*argv, "del")) {
    472       struct ifreq_inet6 {
    473         struct in6_addr addr;
    474         unsigned prefix;
    475         int index;
    476       } ifre6;
    477       int plen, fd6 = xsocket(AF_INET6, SOCK_DGRAM, 0);
    478 
    479       if (!argv[1]) help_exit("%s", *argv);
    480 
    481       plen = get_addrinfo(argv[1], AF_INET6, &ifre6.addr);
    482       if (plen < 0) plen = 128;
    483       xioctl(fd6, SIOCGIFINDEX, &ifre);
    484       ifre6.index = ifre.ifr_ifindex;
    485       ifre6.prefix = plen;
    486       xioctl(fd6, **(argv++)=='a' ? SIOCSIFADDR : SIOCDIFADDR, &ifre6);
    487 
    488       close(fd6);
    489       continue;
    490     // Iterate through table to find/perform operation
    491     } else for (i = 0; i<ARRAY_LEN(try); i++) {
    492       struct argh *t = try+i;
    493       int on = t->on, off = t->off;
    494 
    495       if (!t->name) {
    496         if (isdigit(**argv) || !strcmp(*argv, "default")) argv--;
    497         else continue;
    498       } else if (strcmp(t->name, s)) continue;
    499 
    500       // Is this an SIOCSI entry?
    501       if ((off|0xff) == 0x89ff) {
    502         if (!rev) {
    503           if (!*++argv) error_exit("%s needs argument", t->name);
    504 
    505           // Assign value to ifre field and call ioctl? (via IFREQ_OFFSZ.)
    506           if (on < 0) {
    507             long l = strtoul(*argv, 0, 0);
    508 
    509             if (off == SIOCSIFMAP) xioctl(TT.sockfd, SIOCGIFMAP, &ifre);
    510             on = -on;
    511             poke((on>>16) + (char *)&ifre, l, on&15);
    512             xioctl(TT.sockfd, off, &ifre);
    513             break;
    514           } else {
    515             struct sockaddr_in *si = (struct sockaddr_in *)&ifre.ifr_addr;
    516             int mask = -1;
    517 
    518             si->sin_family = AF_INET;
    519 
    520             if (!strcmp(*argv, "default")) si->sin_addr.s_addr = INADDR_ANY;
    521             else mask = get_addrinfo(*argv, AF_INET, &si->sin_addr);
    522             xioctl(TT.sockfd, off, &ifre);
    523 
    524             // Handle /netmask
    525             if (mask >= 0) {
    526               // sin_addr probably isn't unaligned, but just in case...
    527               mask = htonl((~0)<<(32-mask));
    528               memcpy(&si->sin_addr, &mask, 4);
    529               xioctl(TT.sockfd, SIOCSIFNETMASK, &ifre);
    530             }
    531           }
    532         }
    533         off = 0;
    534       }
    535 
    536       // Set flags
    537       if (on || off) {
    538         xioctl(TT.sockfd, SIOCGIFFLAGS, &ifre);
    539         ifre.ifr_flags &= ~(rev ? on : off);
    540         ifre.ifr_flags |= (rev ? off : on);
    541         xioctl(TT.sockfd, SIOCSIFFLAGS, &ifre);
    542       }
    543 
    544       break;
    545     }
    546     if (i == ARRAY_LEN(try)) help_exit("bad argument '%s'", *argv);
    547   }
    548   close(TT.sockfd);
    549 }
    550