ip/iptunnel.c

   1 /*
   2  * iptunnel.c          "ip tunnel"
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <unistd.h>
  17 #include <sys/types.h>
  18 #include <sys/socket.h>
  19 #include <arpa/inet.h>
  20 #include <sys/ioctl.h>
  21 #include <net/if.h>
  22 #include <net/if_arp.h>
  23 #include <linux/ip.h>
  24 #include <linux/if_tunnel.h>
  25
  26 #include "rt_names.h"
  27 #include "utils.h"
  28 #include "ip_common.h"
  29 #include "tunnel.h"
  30
  31 static void usage(void) __attribute__((noreturn));
  32
  33 static void usage(void)
  34 {
  35         fprintf(stderr, "Usage: ip tunnel { add | change | del | show | prl | 6rd } [ NAME ]\n");
  36         fprintf(stderr, "          [ mode { ipip | gre | sit | isatap | vti } ] [ remote ADDR ] [ local ADDR ]\n");
  37         fprintf(stderr, "          [ [i|o]seq ] [ [i|o]key KEY ] [ [i|o]csum ]\n");
  38         fprintf(stderr, "          [ prl-default ADDR ] [ prl-nodefault ADDR ] [ prl-delete ADDR ]\n");
  39         fprintf(stderr, "          [ 6rd-prefix ADDR ] [ 6rd-relay_prefix ADDR ] [ 6rd-reset ]\n");
  40         fprintf(stderr, "          [ ttl TTL ] [ tos TOS ] [ [no]pmtudisc ] [ dev PHYS_DEV ]\n");
  41         fprintf(stderr, "\n");
  42         fprintf(stderr, "Where: NAME := STRING\n");
  43         fprintf(stderr, "       ADDR := { IP_ADDRESS | any }\n");
  44         fprintf(stderr, "       TOS  := { STRING | 00..ff | inherit | inherit/STRING | inherit/00..ff }\n");
  45         fprintf(stderr, "       TTL  := { 1..255 | inherit }\n");
  46         fprintf(stderr, "       KEY  := { DOTTED_QUAD | NUMBER }\n");
  47         exit(-1);
  48 }
  49
  50 static void set_tunnel_proto(struct ip_tunnel_parm *p, int proto)
  51 {
  52         if (p->iph.protocol && p->iph.protocol != proto) {
  53                 fprintf(stderr,
  54                         "You managed to ask for more than one tunnel mode.\n");
  55                 exit(-1);
  56         }
  57         p->iph.protocol = proto;
  58 }
  59
  60 static int parse_args(int argc, char **argv, int cmd, struct ip_tunnel_parm *p)
  61 {
  62         int count = 0;
  63         const char *medium = NULL;
  64         int isatap = 0;
  65
  66         memset(p, 0, sizeof(*p));
  67         p->iph.version = 4;
  68         p->iph.ihl = 5;
  69 #ifndef IP_DF
  70 #define IP_DF           0x4000          /* Flag: "Don't Fragment"       */
  71 #endif
  72         p->iph.frag_off = htons(IP_DF);
  73
  74         while (argc > 0) {
  75                 if (strcmp(*argv, "mode") == 0) {
  76                         NEXT_ARG();
  77                         if (strcmp(*argv, "ipip") == 0 ||
  78                             strcmp(*argv, "ip/ip") == 0) {
  79                                 set_tunnel_proto(p, IPPROTO_IPIP);
  80                         } else if (strcmp(*argv, "gre") == 0 ||
  81                                    strcmp(*argv, "gre/ip") == 0) {
  82                                 set_tunnel_proto(p, IPPROTO_GRE);
  83                         } else if (strcmp(*argv, "sit") == 0 ||
  84                                    strcmp(*argv, "ipv6/ip") == 0) {
  85                                 set_tunnel_proto(p, IPPROTO_IPV6);
  86                         } else if (strcmp(*argv, "isatap") == 0) {
  87                                 set_tunnel_proto(p, IPPROTO_IPV6);
  88                                 isatap++;
  89                         } else if (strcmp(*argv, "vti") == 0) {
  90                                 set_tunnel_proto(p, IPPROTO_IPIP);
  91                                 p->i_flags |= VTI_ISVTI;
  92                         } else {
  93                                 fprintf(stderr,
  94                                         "Unknown tunnel mode \"%s\"\n", *argv);
  95                                 exit(-1);
  96                         }
  97                 } else if (strcmp(*argv, "key") == 0) {
  98                         NEXT_ARG();
  99                         p->i_flags |= GRE_KEY;
 100                         p->o_flags |= GRE_KEY;
 101                         p->i_key = p->o_key = tnl_parse_key("key", *argv);
 102                 } else if (strcmp(*argv, "ikey") == 0) {
 103                         NEXT_ARG();
 104                         p->i_flags |= GRE_KEY;
 105                         p->i_key = tnl_parse_key("ikey", *argv);
 106                 } else if (strcmp(*argv, "okey") == 0) {
 107                         NEXT_ARG();
 108                         p->o_flags |= GRE_KEY;
 109                         p->o_key = tnl_parse_key("okey", *argv);
 110                 } else if (strcmp(*argv, "seq") == 0) {
 111                         p->i_flags |= GRE_SEQ;
 112                         p->o_flags |= GRE_SEQ;
 113                 } else if (strcmp(*argv, "iseq") == 0) {
 114                         p->i_flags |= GRE_SEQ;
 115                 } else if (strcmp(*argv, "oseq") == 0) {
 116                         p->o_flags |= GRE_SEQ;
 117                 } else if (strcmp(*argv, "csum") == 0) {
 118                         p->i_flags |= GRE_CSUM;
 119                         p->o_flags |= GRE_CSUM;
 120                 } else if (strcmp(*argv, "icsum") == 0) {
 121                         p->i_flags |= GRE_CSUM;
 122                 } else if (strcmp(*argv, "ocsum") == 0) {
 123                         p->o_flags |= GRE_CSUM;
 124                 } else if (strcmp(*argv, "nopmtudisc") == 0) {
 125                         p->iph.frag_off = 0;
 126                 } else if (strcmp(*argv, "pmtudisc") == 0) {
 127                         p->iph.frag_off = htons(IP_DF);
 128                 } else if (strcmp(*argv, "remote") == 0) {
 129                         NEXT_ARG();
 130                         p->iph.daddr = get_addr32(*argv);
 131                 } else if (strcmp(*argv, "local") == 0) {
 132                         NEXT_ARG();
 133                         p->iph.saddr = get_addr32(*argv);
 134                 } else if (strcmp(*argv, "dev") == 0) {
 135                         NEXT_ARG();
 136                         medium = *argv;
 137                 } else if (strcmp(*argv, "ttl") == 0 ||
 138                            strcmp(*argv, "hoplimit") == 0 ||
 139                            strcmp(*argv, "hlim") == 0) {
 140                         __u8 uval;
 141
 142                         NEXT_ARG();
 143                         if (strcmp(*argv, "inherit") != 0) {
 144                                 if (get_u8(&uval, *argv, 0))
 145                                         invarg("invalid TTL\n", *argv);
 146                                 p->iph.ttl = uval;
 147                         }
 148                 } else if (strcmp(*argv, "tos") == 0 ||
 149                            strcmp(*argv, "tclass") == 0 ||
 150                            matches(*argv, "dsfield") == 0) {
 151                         char *dsfield;
 152                         __u32 uval;
 153
 154                         NEXT_ARG();
 155                         dsfield = *argv;
 156                         strsep(&dsfield, "/");
 157                         if (strcmp(*argv, "inherit") != 0) {
 158                                 dsfield = *argv;
 159                                 p->iph.tos = 0;
 160                         } else
 161                                 p->iph.tos = 1;
 162                         if (dsfield) {
 163                                 if (rtnl_dsfield_a2n(&uval, dsfield))
 164                                         invarg("bad TOS value", *argv);
 165                                 p->iph.tos |= uval;
 166                         }
 167                 } else {
 168                         if (strcmp(*argv, "name") == 0)
 169                                 NEXT_ARG();
 170                         else if (matches(*argv, "help") == 0)
 171                                 usage();
 172
 173                         if (p->name[0])
 174                                 duparg2("name", *argv);
 175                         if (get_ifname(p->name, *argv))
 176                                 invarg("\"name\" not a valid ifname", *argv);
 177                         if (cmd == SIOCCHGTUNNEL && count == 0) {
 178                                 struct ip_tunnel_parm old_p = {};
 179
 180                                 if (tnl_get_ioctl(*argv, &old_p))
 181                                         return -1;
 182                                 *p = old_p;
 183                         }
 184                 }
 185                 count++;
 186                 argc--; argv++;
 187         }
 188
 189
 190         if (p->iph.protocol == 0) {
 191                 if (memcmp(p->name, "gre", 3) == 0)
 192                         p->iph.protocol = IPPROTO_GRE;
 193                 else if (memcmp(p->name, "ipip", 4) == 0)
 194                         p->iph.protocol = IPPROTO_IPIP;
 195                 else if (memcmp(p->name, "sit", 3) == 0)
 196                         p->iph.protocol = IPPROTO_IPV6;
 197                 else if (memcmp(p->name, "isatap", 6) == 0) {
 198                         p->iph.protocol = IPPROTO_IPV6;
 199                         isatap++;
 200                 } else if (memcmp(p->name, "vti", 3) == 0) {
 201                         p->iph.protocol = IPPROTO_IPIP;
 202                         p->i_flags |= VTI_ISVTI;
 203                 }
 204         }
 205
 206         if ((p->i_flags & GRE_KEY) || (p->o_flags & GRE_KEY)) {
 207                 if (!(p->i_flags & VTI_ISVTI) &&
 208                     (p->iph.protocol != IPPROTO_GRE)) {
 209                         fprintf(stderr, "Keys are not allowed with ipip and sit tunnels\n");
 210                         return -1;
 211                 }
 212         }
 213
 214         if (medium) {
 215                 p->link = ll_name_to_index(medium);
 216                 if (p->link == 0) {
 217                         fprintf(stderr, "Cannot find device \"%s\"\n", medium);
 218                         return -1;
 219                 }
 220         }
 221
 222         if (p->i_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
 223                 p->i_key = p->iph.daddr;
 224                 p->i_flags |= GRE_KEY;
 225         }
 226         if (p->o_key == 0 && IN_MULTICAST(ntohl(p->iph.daddr))) {
 227                 p->o_key = p->iph.daddr;
 228                 p->o_flags |= GRE_KEY;
 229         }
 230         if (IN_MULTICAST(ntohl(p->iph.daddr)) && !p->iph.saddr) {
 231                 fprintf(stderr, "A broadcast tunnel requires a source address\n");
 232                 return -1;
 233         }
 234         if (isatap)
 235                 p->i_flags |= SIT_ISATAP;
 236
 237         return 0;
 238 }
 239
 240 static const char *tnl_defname(const struct ip_tunnel_parm *p)
 241 {
 242         switch (p->iph.protocol) {
 243         case IPPROTO_IPIP:
 244                 if (p->i_flags & VTI_ISVTI)
 245                         return "ip_vti0";
 246                 else
 247                         return "tunl0";
 248         case IPPROTO_GRE:
 249                 return "gre0";
 250         case IPPROTO_IPV6:
 251                 return "sit0";
 252         }
 253         return NULL;
 254 }
 255
 256 static int do_add(int cmd, int argc, char **argv)
 257 {
 258         struct ip_tunnel_parm p;
 259         const char *basedev;
 260
 261         if (parse_args(argc, argv, cmd, &p) < 0)
 262                 return -1;
 263
 264         if (p.iph.ttl && p.iph.frag_off == 0) {
 265                 fprintf(stderr, "ttl != 0 and nopmtudisc are incompatible\n");
 266                 return -1;
 267         }
 268
 269         basedev = tnl_defname(&p);
 270         if (!basedev) {
 271                 fprintf(stderr,
 272                         "cannot determine tunnel mode (ipip, gre, vti or sit)\n");
 273                 return -1;
 274         }
 275
 276         return tnl_add_ioctl(cmd, basedev, p.name, &p);
 277 }
 278
 279 static int do_del(int argc, char **argv)
 280 {
 281         struct ip_tunnel_parm p;
 282
 283         if (parse_args(argc, argv, SIOCDELTUNNEL, &p) < 0)
 284                 return -1;
 285
 286         return tnl_del_ioctl(tnl_defname(&p) ? : p.name, p.name, &p);
 287 }
 288
 289 static void print_tunnel(const void *t)
 290 {
 291         const struct ip_tunnel_parm *p = t;
 292         struct ip_tunnel_6rd ip6rd = {};
 293         char s1[1024];
 294         char s2[1024];
 295
 296         /* Do not use format_host() for local addr,
 297          * symbolic name will not be useful.
 298          */
 299         printf("%s: %s/ip remote %s local %s",
 300                p->name,
 301                tnl_strproto(p->iph.protocol),
 302                p->iph.daddr ? format_host_r(AF_INET, 4, &p->iph.daddr, s1, sizeof(s1)) : "any",
 303                p->iph.saddr ? rt_addr_n2a_r(AF_INET, 4, &p->iph.saddr, s2, sizeof(s2)) : "any");
 304
 305         if (p->iph.protocol == IPPROTO_IPV6 && (p->i_flags & SIT_ISATAP)) {
 306                 struct ip_tunnel_prl prl[16] = {};
 307                 int i;
 308
 309                 prl[0].datalen = sizeof(prl) - sizeof(prl[0]);
 310                 prl[0].addr = htonl(INADDR_ANY);
 311
 312                 if (!tnl_prl_ioctl(SIOCGETPRL, p->name, prl))
 313                         for (i = 1; i < ARRAY_SIZE(prl); i++) {
 314                                 if (prl[i].addr != htonl(INADDR_ANY)) {
 315                                         printf(" %s %s ",
 316                                                (prl[i].flags & PRL_DEFAULT) ? "pdr" : "pr",
 317                                                format_host(AF_INET, 4, &prl[i].addr));
 318                                 }
 319                         }
 320         }
 321
 322         if (p->link) {
 323                 const char *n = ll_index_to_name(p->link);
 324
 325                 if (n)
 326                         printf(" dev %s", n);
 327         }
 328
 329         if (p->iph.ttl)
 330                 printf(" ttl %u", p->iph.ttl);
 331         else
 332                 printf(" ttl inherit");
 333
 334         if (p->iph.tos) {
 335                 SPRINT_BUF(b1);
 336                 printf(" tos");
 337                 if (p->iph.tos & 1)
 338                         printf(" inherit");
 339                 if (p->iph.tos & ~1)
 340                         printf("%c%s ", p->iph.tos & 1 ? '/' : ' ',
 341                                rtnl_dsfield_n2a(p->iph.tos & ~1, b1, sizeof(b1)));
 342         }
 343
 344         if (!(p->iph.frag_off & htons(IP_DF)))
 345                 printf(" nopmtudisc");
 346
 347         if (p->iph.protocol == IPPROTO_IPV6 && !tnl_ioctl_get_6rd(p->name, &ip6rd) && ip6rd.prefixlen) {
 348                 printf(" 6rd-prefix %s/%u",
 349                        inet_ntop(AF_INET6, &ip6rd.prefix, s1, sizeof(s1)),
 350                        ip6rd.prefixlen);
 351                 if (ip6rd.relay_prefix) {
 352                         printf(" 6rd-relay_prefix %s/%u",
 353                                format_host(AF_INET, 4, &ip6rd.relay_prefix),
 354                                ip6rd.relay_prefixlen);
 355                 }
 356         }
 357
 358         if ((p->i_flags & GRE_KEY) && (p->o_flags & GRE_KEY) && p->o_key == p->i_key)
 359                 printf(" key %u", ntohl(p->i_key));
 360         else if ((p->i_flags | p->o_flags) & GRE_KEY) {
 361                 if (p->i_flags & GRE_KEY)
 362                         printf(" ikey %u", ntohl(p->i_key));
 363                 if (p->o_flags & GRE_KEY)
 364                         printf(" okey %u", ntohl(p->o_key));
 365         }
 366
 367         if (p->i_flags & GRE_SEQ)
 368                 printf("%s  Drop packets out of sequence.", _SL_);
 369         if (p->i_flags & GRE_CSUM)
 370                 printf("%s  Checksum in received packet is required.", _SL_);
 371         if (p->o_flags & GRE_SEQ)
 372                 printf("%s  Sequence packets on output.", _SL_);
 373         if (p->o_flags & GRE_CSUM)
 374                 printf("%s  Checksum output packets.", _SL_);
 375 }
 376
 377
 378 static void ip_tunnel_parm_initialize(const struct tnl_print_nlmsg_info *info)
 379 {
 380         struct ip_tunnel_parm *p2 = info->p2;
 381
 382         memset(p2, 0, sizeof(*p2));
 383 }
 384
 385 static bool ip_tunnel_parm_match(const struct tnl_print_nlmsg_info *info)
 386 {
 387         const struct ip_tunnel_parm *p1 = info->p1;
 388         const struct ip_tunnel_parm *p2 = info->p2;
 389
 390         return ((!p1->link || p1->link == p2->link) &&
 391                 (!p1->name[0] || strcmp(p1->name, p2->name) == 0) &&
 392                 (!p1->iph.daddr || p1->iph.daddr == p2->iph.daddr) &&
 393                 (!p1->iph.saddr || p1->iph.saddr == p2->iph.saddr) &&
 394                 (!p1->i_key || p1->i_key == p2->i_key));
 395 }
 396
 397 static int do_show(int argc, char **argv)
 398 {
 399         struct ip_tunnel_parm p, p1;
 400         const char *basedev;
 401
 402         if (parse_args(argc, argv, SIOCGETTUNNEL, &p) < 0)
 403                 return -1;
 404
 405         basedev = tnl_defname(&p);
 406         if (!basedev) {
 407                 struct tnl_print_nlmsg_info info = {
 408                         .p1    = &p,
 409                         .p2    = &p1,
 410                         .init  = ip_tunnel_parm_initialize,
 411                         .match = ip_tunnel_parm_match,
 412                         .print = print_tunnel,
 413                 };
 414
 415                 return do_tunnels_list(&info);
 416         }
 417
 418         if (tnl_get_ioctl(p.name[0] ? p.name : basedev, &p))
 419                 return -1;
 420
 421         print_tunnel(&p);
 422         fputc('\n', stdout);
 423         return 0;
 424 }
 425
 426 static int do_prl(int argc, char **argv)
 427 {
 428         struct ip_tunnel_prl p = {};
 429         int count = 0;
 430         int cmd = 0;
 431         const char *medium = NULL;
 432
 433         while (argc > 0) {
 434                 if (strcmp(*argv, "prl-default") == 0) {
 435                         NEXT_ARG();
 436                         cmd = SIOCADDPRL;
 437                         p.addr = get_addr32(*argv);
 438                         p.flags |= PRL_DEFAULT;
 439                         count++;
 440                 } else if (strcmp(*argv, "prl-nodefault") == 0) {
 441                         NEXT_ARG();
 442                         cmd = SIOCADDPRL;
 443                         p.addr = get_addr32(*argv);
 444                         count++;
 445                 } else if (strcmp(*argv, "prl-delete") == 0) {
 446                         NEXT_ARG();
 447                         cmd = SIOCDELPRL;
 448                         p.addr = get_addr32(*argv);
 449                         count++;
 450                 } else if (strcmp(*argv, "dev") == 0) {
 451                         NEXT_ARG();
 452                         if (check_ifname(*argv))
 453                                 invarg("\"dev\" not a valid ifname", *argv);
 454                         medium = *argv;
 455                 } else {
 456                         fprintf(stderr,
 457                                 "Invalid PRL parameter \"%s\"\n", *argv);
 458                         exit(-1);
 459                 }
 460                 if (count > 1) {
 461                         fprintf(stderr,
 462                                 "One PRL entry at a time\n");
 463                         exit(-1);
 464                 }
 465                 argc--; argv++;
 466         }
 467         if (!medium) {
 468                 fprintf(stderr, "Must specify device\n");
 469                 exit(-1);
 470         }
 471
 472         return tnl_prl_ioctl(cmd, medium, &p);
 473 }
 474
 475 static int do_6rd(int argc, char **argv)
 476 {
 477         struct ip_tunnel_6rd ip6rd = {};
 478         int cmd = 0;
 479         const char *medium = NULL;
 480         inet_prefix prefix;
 481
 482         while (argc > 0) {
 483                 if (strcmp(*argv, "6rd-prefix") == 0) {
 484                         NEXT_ARG();
 485                         if (get_prefix(&prefix, *argv, AF_INET6))
 486                                 invarg("invalid 6rd_prefix\n", *argv);
 487                         cmd = SIOCADD6RD;
 488                         memcpy(&ip6rd.prefix, prefix.data, 16);
 489                         ip6rd.prefixlen = prefix.bitlen;
 490                 } else if (strcmp(*argv, "6rd-relay_prefix") == 0) {
 491                         NEXT_ARG();
 492                         if (get_prefix(&prefix, *argv, AF_INET))
 493                                 invarg("invalid 6rd-relay_prefix\n", *argv);
 494                         cmd = SIOCADD6RD;
 495                         memcpy(&ip6rd.relay_prefix, prefix.data, 4);
 496                         ip6rd.relay_prefixlen = prefix.bitlen;
 497                 } else if (strcmp(*argv, "6rd-reset") == 0) {
 498                         cmd = SIOCDEL6RD;
 499                 } else if (strcmp(*argv, "dev") == 0) {
 500                         NEXT_ARG();
 501                         if (check_ifname(*argv))
 502                                 invarg("\"dev\" not a valid ifname", *argv);
 503                         medium = *argv;
 504                 } else {
 505                         fprintf(stderr,
 506                                 "Invalid 6RD parameter \"%s\"\n", *argv);
 507                         exit(-1);
 508                 }
 509                 argc--; argv++;
 510         }
 511         if (!medium) {
 512                 fprintf(stderr, "Must specify device\n");
 513                 exit(-1);
 514         }
 515
 516         return tnl_6rd_ioctl(cmd, medium, &ip6rd);
 517 }
 518
 519 static int tunnel_mode_is_ipv6(char *tunnel_mode)
 520 {
 521         static const char * const ipv6_modes[] = {
 522                 "ipv6/ipv6", "ip6ip6",
 523                 "vti6",
 524                 "ip/ipv6", "ipv4/ipv6", "ipip6", "ip4ip6",
 525                 "ip6gre", "gre/ipv6",
 526                 "any/ipv6", "any"
 527         };
 528         int i;
 529
 530         for (i = 0; i < ARRAY_SIZE(ipv6_modes); i++) {
 531                 if (strcmp(ipv6_modes[i], tunnel_mode) == 0)
 532                         return 1;
 533         }
 534         return 0;
 535 }
 536
 537 int do_iptunnel(int argc, char **argv)
 538 {
 539         int i;
 540
 541         for (i = 0; i < argc - 1; i++) {
 542                 if (strcmp(argv[i], "mode") == 0) {
 543                         if (tunnel_mode_is_ipv6(argv[i + 1]))
 544                                 preferred_family = AF_INET6;
 545                         break;
 546                 }
 547         }
 548         switch (preferred_family) {
 549         case AF_UNSPEC:
 550                 preferred_family = AF_INET;
 551                 break;
 552         case AF_INET:
 553                 break;
 554         /*
 555          * This is silly enough but we have no easy way to make it
 556          * protocol-independent because of unarranged structure between
 557          * IPv4 and IPv6.
 558          */
 559         case AF_INET6:
 560                 return do_ip6tunnel(argc, argv);
 561         default:
 562                 fprintf(stderr, "Unsupported protocol family: %d\n", preferred_family);
 563                 exit(-1);
 564         }
 565
 566         if (argc > 0) {
 567                 if (matches(*argv, "add") == 0)
 568                         return do_add(SIOCADDTUNNEL, argc - 1, argv + 1);
 569                 if (matches(*argv, "change") == 0)
 570                         return do_add(SIOCCHGTUNNEL, argc - 1, argv + 1);
 571                 if (matches(*argv, "delete") == 0)
 572                         return do_del(argc - 1, argv + 1);
 573                 if (matches(*argv, "show") == 0 ||
 574                     matches(*argv, "lst") == 0 ||
 575                     matches(*argv, "list") == 0)
 576                         return do_show(argc - 1, argv + 1);
 577                 if (matches(*argv, "prl") == 0)
 578                         return do_prl(argc - 1, argv + 1);
 579                 if (matches(*argv, "6rd") == 0)
 580                         return do_6rd(argc - 1, argv + 1);
 581                 if (matches(*argv, "help") == 0)
 582                         usage();
 583         } else
 584                 return do_show(0, NULL);
 585
 586         fprintf(stderr, "Command \"%s\" is unknown, try \"ip tunnel help\"\n", *argv);
 587         exit(-1);
 588 }