bsd/netinet6/in6_src.c

   1 /*      $FreeBSD: src/sys/netinet6/in6_src.c,v 1.1.2.2 2001/07/03 11:01:52 ume Exp $    */
   2 /*      $KAME: in6_src.c,v 1.37 2001/03/29 05:34:31 itojun Exp $        */
   3
   4 /*
   5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the project nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * Copyright (c) 1982, 1986, 1991, 1993
  35  *      The Regents of the University of California.  All rights reserved.
  36  *
  37  * Redistribution and use in source and binary forms, with or without
  38  * modification, are permitted provided that the following conditions
  39  * are met:
  40  * 1. Redistributions of source code must retain the above copyright
  41  *    notice, this list of conditions and the following disclaimer.
  42  * 2. Redistributions in binary form must reproduce the above copyright
  43  *    notice, this list of conditions and the following disclaimer in the
  44  *    documentation and/or other materials provided with the distribution.
  45  * 3. All advertising materials mentioning features or use of this software
  46  *    must display the following acknowledgement:
  47  *      This product includes software developed by the University of
  48  *      California, Berkeley and its contributors.
  49  * 4. Neither the name of the University nor the names of its contributors
  50  *    may be used to endorse or promote products derived from this software
  51  *    without specific prior written permission.
  52  *
  53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  63  * SUCH DAMAGE.
  64  *
  65  *      @(#)in_pcb.c    8.2 (Berkeley) 1/4/94
  66  */
  67
  68
  69 #include <sys/param.h>
  70 #include <sys/systm.h>
  71 #include <sys/malloc.h>
  72 #include <sys/mbuf.h>
  73 #include <sys/protosw.h>
  74 #include <sys/socket.h>
  75 #include <sys/socketvar.h>
  76 #include <sys/errno.h>
  77 #include <sys/time.h>
  78 #include <sys/proc.h>
  79 #include <kern/lock.h>
  80
  81 #include <net/if.h>
  82 #include <net/route.h>
  83
  84 #include <netinet/in.h>
  85 #include <netinet/in_var.h>
  86 #include <netinet/in_systm.h>
  87 #include <netinet/ip.h>
  88 #include <netinet/in_pcb.h>
  89 #include <netinet6/in6_var.h>
  90 #include <netinet/ip6.h>
  91 #include <netinet6/in6_pcb.h>
  92 #include <netinet6/ip6_var.h>
  93 #include <netinet6/nd6.h>
  94 #if ENABLE_DEFAULT_SCOPE
  95 #include <netinet6/scope6_var.h>
  96 #endif
  97
  98 #include <net/net_osdep.h>
  99
 100 #include "loop.h"
 101
 102 /*
 103  * Return an IPv6 address, which is the most appropriate for a given
 104  * destination and user specified options.
 105  * If necessary, this function lookups the routing table and returns
 106  * an entry to the caller for later use.
 107  */
 108 struct in6_addr *
 109 in6_selectsrc(
 110         struct sockaddr_in6 *dstsock,
 111         struct ip6_pktopts *opts,
 112         struct ip6_moptions *mopts,
 113         struct route_in6 *ro,
 114         struct in6_addr *laddr,
 115         struct in6_addr *src_storage,
 116         int *errorp)
 117 {
 118         struct in6_addr *dst;
 119         struct in6_ifaddr *ia6 = 0;
 120         struct in6_pktinfo *pi = NULL;
 121
 122         dst = &dstsock->sin6_addr;
 123         *errorp = 0;
 124
 125         /*
 126          * If the source address is explicitly specified by the caller,
 127          * use it.
 128          */
 129         if (opts && (pi = opts->ip6po_pktinfo) &&
 130             !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr))
 131                 return(&pi->ipi6_addr);
 132
 133         /*
 134          * If the source address is not specified but the socket(if any)
 135          * is already bound, use the bound address.
 136          */
 137         if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr))
 138                 return(laddr);
 139
 140         /*
 141          * If the caller doesn't specify the source address but
 142          * the outgoing interface, use an address associated with
 143          * the interface.
 144          */
 145         if (pi && pi->ipi6_ifindex) {
 146                 /* XXX boundary check is assumed to be already done. */
 147                 ia6 = in6_ifawithscope(ifindex2ifnet[pi->ipi6_ifindex],
 148                                        dst);
 149                 if (ia6 == 0) {
 150                         *errorp = EADDRNOTAVAIL;
 151                         return(0);
 152                 }
 153                 *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 154                 return src_storage;
 155         }
 156
 157         /*
 158          * If the destination address is a link-local unicast address or
 159          * a multicast address, and if the outgoing interface is specified
 160          * by the sin6_scope_id filed, use an address associated with the
 161          * interface.
 162          * XXX: We're now trying to define more specific semantics of
 163          *      sin6_scope_id field, so this part will be rewritten in
 164          *      the near future.
 165          */
 166         if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MULTICAST(dst)) &&
 167             dstsock->sin6_scope_id) {
 168                 /*
 169                  * I'm not sure if boundary check for scope_id is done
 170                  * somewhere...
 171                  */
 172                 if (dstsock->sin6_scope_id < 0 ||
 173                     if_index < dstsock->sin6_scope_id) {
 174                         *errorp = ENXIO; /* XXX: better error? */
 175                         return(0);
 176                 }
 177                 ia6 = in6_ifawithscope(ifindex2ifnet[dstsock->sin6_scope_id],
 178                                        dst);
 179                 if (ia6 == 0) {
 180                         *errorp = EADDRNOTAVAIL;
 181                         return(0);
 182                 }
 183                 *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 184                 return src_storage;
 185         }
 186
 187         /*
 188          * If the destination address is a multicast address and
 189          * the outgoing interface for the address is specified
 190          * by the caller, use an address associated with the interface.
 191          * There is a sanity check here; if the destination has node-local
 192          * scope, the outgoing interfacde should be a loopback address.
 193          * Even if the outgoing interface is not specified, we also
 194          * choose a loopback interface as the outgoing interface.
 195          */
 196         if (IN6_IS_ADDR_MULTICAST(dst)) {
 197                 struct ifnet *ifp = mopts ? mopts->im6o_multicast_ifp : NULL;
 198
 199                 if (ifp == NULL && IN6_IS_ADDR_MC_NODELOCAL(dst)) {
 200                         ifp = lo_ifp;
 201                 }
 202
 203                 if (ifp) {
 204                         ia6 = in6_ifawithscope(ifp, dst);
 205                         if (ia6 == 0) {
 206                                 *errorp = EADDRNOTAVAIL;
 207                                 return(0);
 208                         }
 209                         *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 210                         return src_storage;
 211                 }
 212         }
 213
 214         /*
 215          * If the next hop address for the packet is specified
 216          * by caller, use an address associated with the route
 217          * to the next hop.
 218          */
 219         {
 220                 struct sockaddr_in6 *sin6_next;
 221                 struct rtentry *rt;
 222
 223                 if (opts && opts->ip6po_nexthop) {
 224                         sin6_next = satosin6(opts->ip6po_nexthop);
 225                         rt = nd6_lookup(&sin6_next->sin6_addr, 1, NULL, 0);
 226                         if (rt) {
 227                                 ia6 = in6_ifawithscope(rt->rt_ifp, dst);
 228                                 if (ia6 == 0)
 229                                         ia6 = ifatoia6(rt->rt_ifa);
 230                         }
 231                         if (ia6 == 0) {
 232                                 *errorp = EADDRNOTAVAIL;
 233                                 return(0);
 234                         }
 235                         *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 236                         return src_storage;
 237                 }
 238         }
 239
 240         /*
 241          * If route is known or can be allocated now,
 242          * our src addr is taken from the i/f, else punt.
 243          */
 244         if (ro) {
 245                 lck_mtx_lock(rt_mtx);
 246                 if (ro->ro_rt &&
 247                     (!(ro->ro_rt->rt_flags & RTF_UP) ||
 248                      satosin6(&ro->ro_dst)->sin6_family != AF_INET6 ||
 249                      !IN6_ARE_ADDR_EQUAL(&satosin6(&ro->ro_dst)->sin6_addr,
 250                                          dst))) {
 251                         rtfree_locked(ro->ro_rt);
 252                         ro->ro_rt = (struct rtentry *)0;
 253                 }
 254                 if (ro->ro_rt == (struct rtentry *)0 ||
 255                     ro->ro_rt->rt_ifp == 0) {
 256                         struct sockaddr_in6 *sa6;
 257
 258                         /* No route yet, so try to acquire one */
 259                         bzero(&ro->ro_dst, sizeof(struct sockaddr_in6));
 260                         sa6 = (struct sockaddr_in6 *)&ro->ro_dst;
 261                         sa6->sin6_family = AF_INET6;
 262                         sa6->sin6_len = sizeof(struct sockaddr_in6);
 263                         sa6->sin6_addr = *dst;
 264 #if SCOPEDROUTING
 265                         sa6->sin6_scope_id = dstsock->sin6_scope_id;
 266 #endif
 267                         if (IN6_IS_ADDR_MULTICAST(dst)) {
 268                                 ro->ro_rt = rtalloc1_locked(
 269                                     &((struct route *)ro)->ro_dst, 0, 0UL);
 270                         } else {
 271                                 rtalloc_ign_locked((struct route *)ro, 0UL);
 272                         }
 273                 }
 274                 lck_mtx_unlock(rt_mtx);
 275
 276                 /*
 277                  * in_pcbconnect() checks out IFF_LOOPBACK to skip using
 278                  * the address. But we don't know why it does so.
 279                  * It is necessary to ensure the scope even for lo0
 280                  * so doesn't check out IFF_LOOPBACK.
 281                  */
 282
 283                 if (ro->ro_rt) {
 284                         ia6 = in6_ifawithscope(ro->ro_rt->rt_ifa->ifa_ifp, dst);
 285                         if (ia6 == 0) {
 286                                 ia6 = ifatoia6(ro->ro_rt->rt_ifa);
 287                                 if (ia6)
 288                                         ifaref(&ia6->ia_ifa);
 289                         }
 290                         else {
 291                                 ifaref(&ia6->ia_ifa);
 292                         }
 293                 }
 294 #if 0
 295                 /*
 296                  * xxx The followings are necessary? (kazu)
 297                  * I don't think so.
 298                  * It's for SO_DONTROUTE option in IPv4.(jinmei)
 299                  */
 300                 if (ia6 == 0) {
 301                         struct sockaddr_in6 sin6 = {sizeof(sin6), AF_INET6, 0};
 302
 303                         sin6->sin6_addr = *dst;
 304
 305                         ia6 = ifatoia6(ifa_ifwithdstaddr(sin6tosa(&sin6)));
 306                         if (ia6 == 0)
 307                                 ia6 = ifatoia6(ifa_ifwithnet(sin6tosa(&sin6)));
 308                         if (ia6 == 0)
 309                                 return(0);
 310                         *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 311                         return src_storage;
 312                 }
 313 #endif /* 0 */
 314                 if (ia6 == 0) {
 315                         *errorp = EHOSTUNREACH; /* no route */
 316                         return(0);
 317                 }
 318                 *src_storage = satosin6(&ia6->ia_addr)->sin6_addr;
 319                 ifafree(&ia6->ia_ifa);
 320                 return src_storage;
 321         }
 322
 323         *errorp = EADDRNOTAVAIL;
 324         return(0);
 325 }
 326
 327 /*
 328  * Default hop limit selection. The precedence is as follows:
 329  * 1. Hoplimit value specified via ioctl.
 330  * 2. (If the outgoing interface is detected) the current
 331  *     hop limit of the interface specified by router advertisement.
 332  * 3. The system default hoplimit.
 333 */
 334 int
 335 in6_selecthlim(
 336         struct in6pcb *in6p,
 337         struct ifnet *ifp)
 338 {
 339         if (in6p && in6p->in6p_hops >= 0)
 340                 return(in6p->in6p_hops);
 341         else if (ifp)
 342                 return(nd_ifinfo[ifp->if_index].chlim);
 343         else
 344                 return(ip6_defhlim);
 345 }
 346
 347 /*
 348  * XXX: this is borrowed from in6_pcbbind(). If possible, we should
 349  * share this function by all *bsd*...
 350  */
 351 int
 352 in6_pcbsetport(
 353         __unused struct in6_addr *laddr,
 354         struct inpcb *inp,
 355         struct proc *p,
 356         int locked)
 357 {
 358         struct socket *so = inp->inp_socket;
 359         u_int16_t lport = 0, first, last, *lastport;
 360         int count, error = 0, wild = 0;
 361         struct inpcbinfo *pcbinfo = inp->inp_pcbinfo;
 362         if (!locked) { /* Make sure we don't run into a deadlock: 4052373 */
 363                 if (!lck_rw_try_lock_exclusive(pcbinfo->mtx)) {
 364                         socket_unlock(inp->inp_socket, 0);
 365                         lck_rw_lock_exclusive(pcbinfo->mtx);
 366                         socket_lock(inp->inp_socket, 0);
 367                 }
 368         }
 369
 370         /* XXX: this is redundant when called from in6_pcbbind */
 371         if ((so->so_options & (SO_REUSEADDR|SO_REUSEPORT)) == 0)
 372                 wild = INPLOOKUP_WILDCARD;
 373
 374         inp->inp_flags |= INP_ANONPORT;
 375
 376         if (inp->inp_flags & INP_HIGHPORT) {
 377                 first = ipport_hifirstauto;     /* sysctl */
 378                 last  = ipport_hilastauto;
 379                 lastport = &pcbinfo->lasthi;
 380         } else if (inp->inp_flags & INP_LOWPORT) {
 381                 if (p && (error = proc_suser(p))) {
 382                         if (!locked)
 383                                 lck_rw_done(pcbinfo->mtx);
 384                         return error;
 385                 }
 386                 first = ipport_lowfirstauto;    /* 1023 */
 387                 last  = ipport_lowlastauto;     /* 600 */
 388                 lastport = &pcbinfo->lastlow;
 389         } else {
 390                 first = ipport_firstauto;       /* sysctl */
 391                 last  = ipport_lastauto;
 392                 lastport = &pcbinfo->lastport;
 393         }
 394         /*
 395          * Simple check to ensure all ports are not used up causing
 396          * a deadlock here.
 397          *
 398          * We split the two cases (up and down) so that the direction
 399          * is not being tested on each round of the loop.
 400          */
 401         if (first > last) {
 402                 /*
 403                  * counting down
 404                  */
 405                 count = first - last;
 406
 407                 do {
 408                         if (count-- < 0) {      /* completely used? */
 409                                 /*
 410                                  * Undo any address bind that may have
 411                                  * occurred above.
 412                                  */
 413                                 inp->in6p_laddr = in6addr_any;
 414                                 if (!locked)
 415                                         lck_rw_done(pcbinfo->mtx);
 416                                 return (EAGAIN);
 417                         }
 418                         --*lastport;
 419                         if (*lastport > first || *lastport < last)
 420                                 *lastport = first;
 421                         lport = htons(*lastport);
 422                 } while (in6_pcblookup_local(pcbinfo,
 423                                              &inp->in6p_laddr, lport, wild));
 424         } else {
 425                 /*
 426                          * counting up
 427                          */
 428                 count = last - first;
 429
 430                 do {
 431                         if (count-- < 0) {      /* completely used? */
 432                                 /*
 433                                  * Undo any address bind that may have
 434                                  * occurred above.
 435                                  */
 436                                 inp->in6p_laddr = in6addr_any;
 437                                 if (!locked)
 438                                         lck_rw_done(pcbinfo->mtx);
 439                                 return (EAGAIN);
 440                         }
 441                         ++*lastport;
 442                         if (*lastport < first || *lastport > last)
 443                                 *lastport = first;
 444                         lport = htons(*lastport);
 445                 } while (in6_pcblookup_local(pcbinfo,
 446                                              &inp->in6p_laddr, lport, wild));
 447         }
 448
 449         inp->inp_lport = lport;
 450         if (in_pcbinshash(inp, 1) != 0) {
 451                 inp->in6p_laddr = in6addr_any;
 452                 inp->inp_lport = 0;
 453                 if (!locked)
 454                         lck_rw_done(pcbinfo->mtx);
 455                 return (EAGAIN);
 456         }
 457
 458         if (!locked)
 459                 lck_rw_done(pcbinfo->mtx);
 460         return(0);
 461 }
 462
 463 /*
 464  * generate kernel-internal form (scopeid embedded into s6_addr16[1]).
 465  * If the address scope of is link-local, embed the interface index in the
 466  * address.  The routine determines our precedence
 467  * between advanced API scope/interface specification and basic API
 468  * specification.
 469  *
 470  * this function should be nuked in the future, when we get rid of
 471  * embedded scopeid thing.
 472  *
 473  * XXX actually, it is over-specification to return ifp against sin6_scope_id.
 474  * there can be multiple interfaces that belong to a particular scope zone
 475  * (in specification, we have 1:N mapping between a scope zone and interfaces).
 476  * we may want to change the function to return something other than ifp.
 477  */
 478 int
 479 in6_embedscope(
 480         struct in6_addr *in6,
 481         const struct sockaddr_in6 *sin6,
 482 #ifdef HAVE_NRL_INPCB
 483         struct inpcb *in6p,
 484 #define in6p_outputopts inp_outputopts6
 485 #define in6p_moptions   inp_moptions6
 486 #else
 487         struct in6pcb *in6p,
 488 #endif
 489         struct ifnet **ifpp)
 490 {
 491         struct ifnet *ifp = NULL;
 492         u_int32_t scopeid;
 493
 494         *in6 = sin6->sin6_addr;
 495         scopeid = sin6->sin6_scope_id;
 496         if (ifpp)
 497                 *ifpp = NULL;
 498
 499         /*
 500          * don't try to read sin6->sin6_addr beyond here, since the caller may
 501          * ask us to overwrite existing sockaddr_in6
 502          */
 503
 504 #ifdef ENABLE_DEFAULT_SCOPE
 505         if (scopeid == 0)
 506                 scopeid = scope6_addr2default(in6);
 507 #endif
 508
 509         if (IN6_IS_SCOPE_LINKLOCAL(in6)) {
 510                 struct in6_pktinfo *pi;
 511
 512                 /*
 513                  * KAME assumption: link id == interface id
 514                  */
 515
 516                 if (in6p && in6p->in6p_outputopts &&
 517                     (pi = in6p->in6p_outputopts->ip6po_pktinfo) &&
 518                     pi->ipi6_ifindex) {
 519                         ifp = ifindex2ifnet[pi->ipi6_ifindex];
 520                         in6->s6_addr16[1] = htons(pi->ipi6_ifindex);
 521                 } else if (in6p && IN6_IS_ADDR_MULTICAST(in6) &&
 522                            in6p->in6p_moptions &&
 523                            in6p->in6p_moptions->im6o_multicast_ifp) {
 524                         ifp = in6p->in6p_moptions->im6o_multicast_ifp;
 525                         in6->s6_addr16[1] = htons(ifp->if_index);
 526                 } else if (scopeid) {
 527                         /* boundary check */
 528                         if (scopeid < 0 || if_index < scopeid)
 529                                 return ENXIO;  /* XXX EINVAL? */
 530                         ifp = ifindex2ifnet[scopeid];
 531                         /*XXX assignment to 16bit from 32bit variable */
 532                         in6->s6_addr16[1] = htons(scopeid & 0xffff);
 533                 }
 534
 535                 if (ifpp)
 536                         *ifpp = ifp;
 537         }
 538
 539         return 0;
 540 }
 541 #if HAVE_NRL_INPCB
 542 #undef in6p_outputopts
 543 #undef in6p_moptions
 544 #endif
 545
 546 /*
 547  * generate standard sockaddr_in6 from embedded form.
 548  * touches sin6_addr and sin6_scope_id only.
 549  *
 550  * this function should be nuked in the future, when we get rid of
 551  * embedded scopeid thing.
 552  */
 553 int
 554 in6_recoverscope(
 555         struct sockaddr_in6 *sin6,
 556         const struct in6_addr *in6,
 557         struct ifnet *ifp)
 558 {
 559         u_int32_t scopeid;
 560
 561         sin6->sin6_addr = *in6;
 562
 563         /*
 564          * don't try to read *in6 beyond here, since the caller may
 565          * ask us to overwrite existing sockaddr_in6
 566          */
 567
 568         sin6->sin6_scope_id = 0;
 569         if (IN6_IS_SCOPE_LINKLOCAL(in6)) {
 570                 /*
 571                  * KAME assumption: link id == interface id
 572                  */
 573                 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]);
 574                 if (scopeid) {
 575                         /* sanity check */
 576                         if (scopeid < 0 || if_index < scopeid)
 577                                 return ENXIO;
 578                         if (ifp && ifp->if_index != scopeid)
 579                                 return ENXIO;
 580                         sin6->sin6_addr.s6_addr16[1] = 0;
 581                         sin6->sin6_scope_id = scopeid;
 582                 }
 583         }
 584
 585         return 0;
 586 }
 587
 588 /*
 589  * just clear the embedded scope identifer.
 590  * XXX: currently used for bsdi4 only as a supplement function.
 591  */
 592 void
 593 in6_clearscope(addr)
 594         struct in6_addr *addr;
 595 {
 596         if (IN6_IS_SCOPE_LINKLOCAL(addr))
 597                 addr->s6_addr16[1] = 0;
 598 }