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[netbsd-mini2440.git] / sys / netinet6 / in6_src.c

/*      $KAME: in6_src.c,v 1.159 2005/10/19 01:40:32 t-momose Exp $     */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)in_pcb.c    8.2 (Berkeley) 1/4/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6_src.c,v 1.48 2009/05/12 22:22:46 elad Exp $");

#include "opt_inet.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/kauth.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/ip6_private.h>
#include <netinet6/nd6.h>
#include <netinet6/scope6_var.h>

#include <net/net_osdep.h>

#ifdef MIP6
#include <netinet6/mip6.h>
#include <netinet6/mip6_var.h>
#include "mip.h"
#if NMIP > 0
#include <net/if_mip.h>
#endif /* NMIP > 0 */
#endif /* MIP6 */

#define ADDR_LABEL_NOTAPP (-1)
struct in6_addrpolicy defaultaddrpolicy;

#ifdef notyet /* until introducing ND extensions and address selection */
int ip6_prefer_tempaddr = 0;
#endif

static int selectroute(struct sockaddr_in6 *, struct ip6_pktopts *,
        struct ip6_moptions *, struct route *, struct ifnet **,
        struct rtentry **, int, int);
static int in6_selectif(struct sockaddr_in6 *, struct ip6_pktopts *,
        struct ip6_moptions *, struct route *, struct ifnet **);

static struct in6_addrpolicy *lookup_addrsel_policy(struct sockaddr_in6 *);

static void init_policy_queue(void);
static int add_addrsel_policyent(struct in6_addrpolicy *);
static int delete_addrsel_policyent(struct in6_addrpolicy *);
static int walk_addrsel_policy(int (*)(struct in6_addrpolicy *, void *),
                                    void *);
static int dump_addrsel_policyent(struct in6_addrpolicy *, void *);
static struct in6_addrpolicy *match_addrsel_policy(struct sockaddr_in6 *);

/*
 * Return an IPv6 address, which is the most appropriate for a given
 * destination and user specified options.
 * If necessary, this function lookups the routing table and returns
 * an entry to the caller for later use.
 */
#if 0                           /* diabled ad-hoc */
#define REPLACE(r) do {\
        if ((r) < sizeof(ip6stat.ip6s_sources_rule) / \
                sizeof(ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
                ip6stat.ip6s_sources_rule[(r)]++; \
        /* printf("in6_selectsrc: replace %s with %s by %d\n", ia_best ? ip6_sprintf(&ia_best->ia_addr.sin6_addr) : "none", ip6_sprintf(&ia->ia_addr.sin6_addr), (r)); */ \
        goto replace; \
} while(0)
#define NEXT(r) do {\
        if ((r) < sizeof(ip6stat.ip6s_sources_rule) / \
                sizeof(ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
                ip6stat.ip6s_sources_rule[(r)]++; \
        /* printf("in6_selectsrc: keep %s against %s by %d\n", ia_best ? ip6_sprintf(&ia_best->ia_addr.sin6_addr) : "none", ip6_sprintf(&ia->ia_addr.sin6_addr), (r)); */ \
        goto next;              /* XXX: we can't use 'continue' here */ \
} while(0)
#define BREAK(r) do { \
        if ((r) < sizeof(ip6stat.ip6s_sources_rule) / \
                sizeof(ip6stat.ip6s_sources_rule[0])) /* check for safety */ \
                ip6stat.ip6s_sources_rule[(r)]++; \
        goto out;               /* XXX: we can't use 'break' here */ \
} while(0)
#else
#define REPLACE(r) goto replace
#define NEXT(r) goto next
#define BREAK(r) goto out
#endif

struct in6_addr *
in6_selectsrc(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 
        struct ip6_moptions *mopts, struct route *ro, struct in6_addr *laddr, 
        struct ifnet **ifpp, int *errorp)
{
        struct in6_addr dst;
        struct ifnet *ifp = NULL;
        struct in6_ifaddr *ia = NULL, *ia_best = NULL;
        struct in6_pktinfo *pi = NULL;
        int dst_scope = -1, best_scope = -1, best_matchlen = -1;
        struct in6_addrpolicy *dst_policy = NULL, *best_policy = NULL;
        u_int32_t odstzone;
        int error;
#ifdef notyet /* until introducing ND extensions and address selection */
        int prefer_tempaddr;
#endif
#if defined(MIP6) && NMIP > 0
        u_int8_t ip6po_usecoa = 0;
#endif /* MIP6 && NMIP > 0 */

        dst = dstsock->sin6_addr; /* make a copy for local operation */
        *errorp = 0;
        if (ifpp)
                *ifpp = NULL;

        /*
         * Try to determine the outgoing interface for the given destination.
         * We do this regardless of whether the socket is bound, since the
         * caller may need this information as a side effect of the call
         * to this function (e.g., for identifying the appropriate scope zone
         * ID).
         */
        error = in6_selectif(dstsock, opts, mopts, ro, &ifp);
        if (ifpp)
                *ifpp = ifp;

        /*
         * If the source address is explicitly specified by the caller,
         * check if the requested source address is indeed a unicast address
         * assigned to the node, and can be used as the packet's source
         * address.  If everything is okay, use the address as source.
         */
        if (opts && (pi = opts->ip6po_pktinfo) &&
            !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) {
                struct sockaddr_in6 srcsock;
                struct in6_ifaddr *ia6;

                /*
                 * Determine the appropriate zone id of the source based on
                 * the zone of the destination and the outgoing interface.
                 * If the specified address is ambiguous wrt the scope zone,
                 * the interface must be specified; otherwise, ifa_ifwithaddr()
                 * will fail matching the address.
                 */
                memset(&srcsock, 0, sizeof(srcsock));
                srcsock.sin6_family = AF_INET6;
                srcsock.sin6_len = sizeof(srcsock);
                srcsock.sin6_addr = pi->ipi6_addr;
                if (ifp) {
                        *errorp = in6_setscope(&srcsock.sin6_addr, ifp, NULL);
                        if (*errorp != 0)
                                return (NULL);
                }

                ia6 = (struct in6_ifaddr *)ifa_ifwithaddr((struct sockaddr *)(&srcsock));
                if (ia6 == NULL ||
                    (ia6->ia6_flags & (IN6_IFF_ANYCAST | IN6_IFF_NOTREADY))) {
                        *errorp = EADDRNOTAVAIL;
                        return (NULL);
                }
                pi->ipi6_addr = srcsock.sin6_addr; /* XXX: this overrides pi */
                if (ifpp)
                        *ifpp = ifp;
                return (&ia6->ia_addr.sin6_addr);
        }

        /*
         * If the socket has already bound the source, just use it.  We don't
         * care at the moment whether in6_selectif() succeeded above, even
         * though it would eventually cause an error.
         */
        if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr))
                return (laddr);

        /*
         * The outgoing interface is crucial in the general selection procedure
         * below.  If it is not known at this point, we fail.
         */
        if (ifp == NULL) {
                *errorp = error;
                return (NULL);
        }

        /*
         * If the address is not yet determined, choose the best one based on
         * the outgoing interface and the destination address.
         */

#if defined(MIP6) && NMIP > 0
        /*
         * a caller can specify IP6PO_USECOA to not to use a home
         * address.  for example, the case that the neighbour
         * unreachability detection to the global address.
         */
        if (opts != NULL &&
            (opts->ip6po_flags & IP6PO_USECOA) != 0) {
                ip6po_usecoa = 1;
        }
#endif /* MIP6 && NMIP > 0 */

#ifdef DIAGNOSTIC
        if (ifp == NULL)        /* this should not happen */
                panic("in6_selectsrc: NULL ifp");
#endif
        *errorp = in6_setscope(&dst, ifp, &odstzone);
        if (*errorp != 0)
                return (NULL);

        for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
                int new_scope = -1, new_matchlen = -1;
                struct in6_addrpolicy *new_policy = NULL;
                u_int32_t srczone, osrczone, dstzone;
                struct in6_addr src;
                struct ifnet *ifp1 = ia->ia_ifp;

                /*
                 * We'll never take an address that breaks the scope zone
                 * of the destination.  We also skip an address if its zone
                 * does not contain the outgoing interface.
                 * XXX: we should probably use sin6_scope_id here.
                 */
                if (in6_setscope(&dst, ifp1, &dstzone) ||
                    odstzone != dstzone) {
                        continue;
                }
                src = ia->ia_addr.sin6_addr;
                if (in6_setscope(&src, ifp, &osrczone) ||
                    in6_setscope(&src, ifp1, &srczone) ||
                    osrczone != srczone) {
                        continue;
                }

                /* avoid unusable addresses */
                if ((ia->ia6_flags &
                     (IN6_IFF_NOTREADY | IN6_IFF_ANYCAST | IN6_IFF_DETACHED))) {
                                continue;
                }
                if (!ip6_use_deprecated && IFA6_IS_DEPRECATED(ia))
                        continue;

#if defined(MIP6) && NMIP > 0
                /* avoid unusable home addresses. */
                if ((ia->ia6_flags & IN6_IFF_HOME) &&
                    !mip6_ifa6_is_addr_valid_hoa(ia))
                        continue;
#endif /* MIP6 && NMIP > 0 */

                /* Rule 1: Prefer same address */
                if (IN6_ARE_ADDR_EQUAL(&dst, &ia->ia_addr.sin6_addr)) {
                        ia_best = ia;
                        BREAK(1); /* there should be no better candidate */
                }

                if (ia_best == NULL)
                        REPLACE(0);

                /* Rule 2: Prefer appropriate scope */
                if (dst_scope < 0)
                        dst_scope = in6_addrscope(&dst);
                new_scope = in6_addrscope(&ia->ia_addr.sin6_addr);
                if (IN6_ARE_SCOPE_CMP(best_scope, new_scope) < 0) {
                        if (IN6_ARE_SCOPE_CMP(best_scope, dst_scope) < 0)
                                REPLACE(2);
                        NEXT(2);
                } else if (IN6_ARE_SCOPE_CMP(new_scope, best_scope) < 0) {
                        if (IN6_ARE_SCOPE_CMP(new_scope, dst_scope) < 0)
                                NEXT(2);
                        REPLACE(2);
                }

                /*
                 * Rule 3: Avoid deprecated addresses.  Note that the case of
                 * !ip6_use_deprecated is already rejected above.
                 */
                if (!IFA6_IS_DEPRECATED(ia_best) && IFA6_IS_DEPRECATED(ia))
                        NEXT(3);
                if (IFA6_IS_DEPRECATED(ia_best) && !IFA6_IS_DEPRECATED(ia))
                        REPLACE(3);

                /* Rule 4: Prefer home addresses */
#if defined(MIP6) && NMIP > 0
                if (!MIP6_IS_MN)
                        goto skip_rule4;

                if ((ia_best->ia6_flags & IN6_IFF_HOME) == 0 &&
                    (ia->ia6_flags & IN6_IFF_HOME) == 0) {
                        /* both address are not home addresses. */
                        goto skip_rule4;
                }

                /*
                 * If SA is simultaneously a home address and care-of
                 * address and SB is not, then prefer SA. Similarly,
                 * if SB is simultaneously a home address and care-of
                 * address and SA is not, then prefer SB.
                 */
                if (((ia_best->ia6_flags & IN6_IFF_HOME) != 0 &&
                        ia_best->ia_ifp->if_type != IFT_MIP)
                    &&
                    ((ia->ia6_flags & IN6_IFF_HOME) != 0 &&
                        ia->ia_ifp->if_type == IFT_MIP))
                        NEXT(4);
                if (((ia_best->ia6_flags & IN6_IFF_HOME) != 0 &&
                        ia_best->ia_ifp->if_type == IFT_MIP)
                    &&
                    ((ia->ia6_flags & IN6_IFF_HOME) != 0 &&
                        ia->ia_ifp->if_type != IFT_MIP))
                        REPLACE(4);
                if (ip6po_usecoa == 0) {
                        /*
                         * If SA is just a home address and SB is just
                         * a care-of address, then prefer
                         * SA. Similarly, if SB is just a home address
                         * and SA is just a care-of address, then
                         * prefer SB.
                         */
                        if ((ia_best->ia6_flags & IN6_IFF_HOME) != 0 &&
                            (ia->ia6_flags & IN6_IFF_HOME) == 0) {
                                NEXT(4);
                        }
                        if ((ia_best->ia6_flags & IN6_IFF_HOME) == 0 &&
                            (ia->ia6_flags & IN6_IFF_HOME) != 0) {
                                REPLACE(4);
                        }
                } else {
                        /*
                         * a sender don't want to use a home address
                         * because:
                         *
                         * 1) we cannot use.  (ex. NS or NA to global
                         * addresses.)
                         *
                         * 2) a user specified not to use.
                         * (ex. mip6control -u)
                         */
                        if ((ia_best->ia6_flags & IN6_IFF_HOME) == 0 &&
                            (ia->ia6_flags & IN6_IFF_HOME) != 0) {
                                /* XXX breaks stat */
                                NEXT(0);
                        }
                        if ((ia_best->ia6_flags & IN6_IFF_HOME) != 0 &&
                            (ia->ia6_flags & IN6_IFF_HOME) == 0) {
                                /* XXX breaks stat */
                                REPLACE(0);
                        }
                }                       
        skip_rule4:
#endif /* MIP6 && NMIP > 0 */

                /* Rule 5: Prefer outgoing interface */
                if (ia_best->ia_ifp == ifp && ia->ia_ifp != ifp)
                        NEXT(5);
                if (ia_best->ia_ifp != ifp && ia->ia_ifp == ifp)
                        REPLACE(5);

                /*
                 * Rule 6: Prefer matching label
                 * Note that best_policy should be non-NULL here.
                 */
                if (dst_policy == NULL)
                        dst_policy = lookup_addrsel_policy(dstsock);
                if (dst_policy->label != ADDR_LABEL_NOTAPP) {
                        new_policy = lookup_addrsel_policy(&ia->ia_addr);
                        if (dst_policy->label == best_policy->label &&
                            dst_policy->label != new_policy->label)
                                NEXT(6);
                        if (dst_policy->label != best_policy->label &&
                            dst_policy->label == new_policy->label)
                                REPLACE(6);
                }

                /*
                 * Rule 7: Prefer public addresses.
                 * We allow users to reverse the logic by configuring
                 * a sysctl variable, so that privacy conscious users can
                 * always prefer temporary addresses.
                 */
#ifdef notyet /* until introducing ND extensions and address selection */
                if (opts == NULL ||
                    opts->ip6po_prefer_tempaddr == IP6PO_TEMPADDR_SYSTEM) {
                        prefer_tempaddr = ip6_prefer_tempaddr;
                } else if (opts->ip6po_prefer_tempaddr ==
                    IP6PO_TEMPADDR_NOTPREFER) {
                        prefer_tempaddr = 0;
                } else
                        prefer_tempaddr = 1;
                if (!(ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
                    (ia->ia6_flags & IN6_IFF_TEMPORARY)) {
                        if (prefer_tempaddr)
                                REPLACE(7);
                        else
                                NEXT(7);
                }
                if ((ia_best->ia6_flags & IN6_IFF_TEMPORARY) &&
                    !(ia->ia6_flags & IN6_IFF_TEMPORARY)) {
                        if (prefer_tempaddr)
                                NEXT(7);
                        else
                                REPLACE(7);
                }
#endif

                /*
                 * Rule 8: prefer addresses on alive interfaces.
                 * This is a KAME specific rule.
                 */
                if ((ia_best->ia_ifp->if_flags & IFF_UP) &&
                    !(ia->ia_ifp->if_flags & IFF_UP))
                        NEXT(8);
                if (!(ia_best->ia_ifp->if_flags & IFF_UP) &&
                    (ia->ia_ifp->if_flags & IFF_UP))
                        REPLACE(8);

                /*
                 * Rule 9: prefer addresses on "preferred" interfaces.
                 * This is a KAME specific rule.
                 */
#ifdef notyet                   /* until introducing address selection */
#define NDI_BEST ND_IFINFO(ia_best->ia_ifp)
#define NDI_NEW  ND_IFINFO(ia->ia_ifp)
                if ((NDI_BEST->flags & ND6_IFF_PREFER_SOURCE) &&
                    !(NDI_NEW->flags & ND6_IFF_PREFER_SOURCE))
                        NEXT(9);
                if (!(NDI_BEST->flags & ND6_IFF_PREFER_SOURCE) &&
                    (NDI_NEW->flags & ND6_IFF_PREFER_SOURCE))
                        REPLACE(9);
#undef NDI_BEST
#undef NDI_NEW
#endif

                /*
                 * Rule 14: Use longest matching prefix.
                 * Note: in the address selection draft, this rule is
                 * documented as "Rule 8".  However, since it is also
                 * documented that this rule can be overridden, we assign
                 * a large number so that it is easy to assign smaller numbers
                 * to more preferred rules.
                 */
                new_matchlen = in6_matchlen(&ia->ia_addr.sin6_addr, &dst);
                if (best_matchlen < new_matchlen)
                        REPLACE(14);
                if (new_matchlen < best_matchlen)
                        NEXT(14);

                /* Rule 15 is reserved. */

                /*
                 * Last resort: just keep the current candidate.
                 * Or, do we need more rules?
                 */
                continue;

          replace:
                ia_best = ia;
                best_scope = (new_scope >= 0 ? new_scope :
                              in6_addrscope(&ia_best->ia_addr.sin6_addr));
                best_policy = (new_policy ? new_policy :
                               lookup_addrsel_policy(&ia_best->ia_addr));
                best_matchlen = (new_matchlen >= 0 ? new_matchlen :
                                 in6_matchlen(&ia_best->ia_addr.sin6_addr,
                                              &dst));

          next:
                continue;

          out:
                break;
        }

        if ((ia = ia_best) == NULL) {
                *errorp = EADDRNOTAVAIL;
                return (NULL);
        }

        return (&ia->ia_addr.sin6_addr);
}
#undef REPLACE
#undef BREAK
#undef NEXT

static int
selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 
        struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp, 
        struct rtentry **retrt, int clone, int norouteok)
{
        int error = 0;
        struct ifnet *ifp = NULL;
        struct rtentry *rt = NULL;
        struct sockaddr_in6 *sin6_next;
        struct in6_pktinfo *pi = NULL;
        struct in6_addr *dst;

        dst = &dstsock->sin6_addr;

#if 0
        if (dstsock->sin6_addr.s6_addr32[0] == 0 &&
            dstsock->sin6_addr.s6_addr32[1] == 0 &&
            !IN6_IS_ADDR_LOOPBACK(&dstsock->sin6_addr)) {
                printf("in6_selectroute: strange destination %s\n",
                       ip6_sprintf(&dstsock->sin6_addr));
        } else {
                printf("in6_selectroute: destination = %s%%%d\n",
                       ip6_sprintf(&dstsock->sin6_addr),
                       dstsock->sin6_scope_id); /* for debug */
        }
#endif

        /* If the caller specify the outgoing interface explicitly, use it. */
        if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) {
                /* XXX boundary check is assumed to be already done. */
                ifp = ifindex2ifnet[pi->ipi6_ifindex];
                if (ifp != NULL &&
                    (norouteok || retrt == NULL ||
                    IN6_IS_ADDR_MULTICAST(dst))) {
                        /*
                         * we do not have to check or get the route for
                         * multicast.
                         */
                        goto done;
                } else
                        goto getroute;
        }

        /*
         * If the destination address is a multicast address and the outgoing
         * interface for the address is specified by the caller, use it.
         */
        if (IN6_IS_ADDR_MULTICAST(dst) &&
            mopts != NULL && (ifp = mopts->im6o_multicast_ifp) != NULL) {
                goto done; /* we do not need a route for multicast. */
        }

  getroute:
        /*
         * If the next hop address for the packet is specified by the caller,
         * use it as the gateway.
         */
        if (opts && opts->ip6po_nexthop) {
                struct route *ron;

                sin6_next = satosin6(opts->ip6po_nexthop);

                /* at this moment, we only support AF_INET6 next hops */
                if (sin6_next->sin6_family != AF_INET6) {
                        error = EAFNOSUPPORT; /* or should we proceed? */
                        goto done;
                }

                /*
                 * If the next hop is an IPv6 address, then the node identified
                 * by that address must be a neighbor of the sending host.
                 */
                ron = &opts->ip6po_nextroute;
                if ((rt = rtcache_lookup(ron, sin6tosa(sin6_next))) == NULL ||
                    (rt->rt_flags & RTF_GATEWAY) != 0 ||
                    !nd6_is_addr_neighbor(sin6_next, rt->rt_ifp)) {
                        rtcache_free(ron);
                        error = EHOSTUNREACH;
                        goto done;
                }
                ifp = rt->rt_ifp;

                /*
                 * When cloning is required, try to allocate a route to the
                 * destination so that the caller can store path MTU
                 * information.
                 */
                if (!clone)
                        goto done;
        }

        /*
         * Use a cached route if it exists and is valid, else try to allocate
         * a new one.  Note that we should check the address family of the
         * cached destination, in case of sharing the cache with IPv4.
         */
        if (ro != NULL) {
                union {
                        struct sockaddr         dst;
                        struct sockaddr_in6     dst6;
                } u;

                /* No route yet, so try to acquire one */
                u.dst6 = *dstsock;
                u.dst6.sin6_scope_id = 0;
                rt = rtcache_lookup1(ro, &u.dst, clone);

                /*
                 * do not care about the result if we have the nexthop
                 * explicitly specified.
                 */
                if (opts && opts->ip6po_nexthop)
                        goto done;

                if (rt == NULL)
                        error = EHOSTUNREACH;
                else
                        ifp = rt->rt_ifp;

                /*
                 * Check if the outgoing interface conflicts with
                 * the interface specified by ipi6_ifindex (if specified).
                 * Note that loopback interface is always okay.
                 * (this may happen when we are sending a packet to one of
                 *  our own addresses.)
                 */
                if (opts && opts->ip6po_pktinfo &&
                    opts->ip6po_pktinfo->ipi6_ifindex) {
                        if (!(ifp->if_flags & IFF_LOOPBACK) &&
                            ifp->if_index !=
                            opts->ip6po_pktinfo->ipi6_ifindex) {
                                error = EHOSTUNREACH;
                                goto done;
                        }
                }
        }

  done:
        if (ifp == NULL && rt == NULL) {
                /*
                 * This can happen if the caller did not pass a cached route
                 * nor any other hints.  We treat this case an error.
                 */
                error = EHOSTUNREACH;
        }
        if (error == EHOSTUNREACH)
                IP6_STATINC(IP6_STAT_NOROUTE);

        if (retifp != NULL)
                *retifp = ifp;
        if (retrt != NULL)
                *retrt = rt;    /* rt may be NULL */

        return (error);
}

static int
in6_selectif(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 
        struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp)
{
        int error, clone;
        struct rtentry *rt = NULL;

        clone = IN6_IS_ADDR_MULTICAST(&dstsock->sin6_addr) ? 0 : 1;
        if ((error = selectroute(dstsock, opts, mopts, ro, retifp,
            &rt, clone, 1)) != 0) {
                return (error);
        }

        /*
         * do not use a rejected or black hole route.
         * XXX: this check should be done in the L2 output routine.
         * However, if we skipped this check here, we'd see the following
         * scenario:
         * - install a rejected route for a scoped address prefix
         *   (like fe80::/10)
         * - send a packet to a destination that matches the scoped prefix,
         *   with ambiguity about the scope zone.
         * - pick the outgoing interface from the route, and disambiguate the
         *   scope zone with the interface.
         * - ip6_output() would try to get another route with the "new"
         *   destination, which may be valid.
         * - we'd see no error on output.
         * Although this may not be very harmful, it should still be confusing.
         * We thus reject the case here.
         */
        if (rt && (rt->rt_flags & (RTF_REJECT | RTF_BLACKHOLE)))
                return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);

        /*
         * Adjust the "outgoing" interface.  If we're going to loop the packet
         * back to ourselves, the ifp would be the loopback interface.
         * However, we'd rather know the interface associated to the
         * destination address (which should probably be one of our own
         * addresses.)
         */
        if (rt && rt->rt_ifa && rt->rt_ifa->ifa_ifp)
                *retifp = rt->rt_ifa->ifa_ifp;

        return (0);
}

/*
 * close - meaningful only for bsdi and freebsd.
 */

int
in6_selectroute(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts, 
        struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp, 
        struct rtentry **retrt, int clone)
{
        return selectroute(dstsock, opts, mopts, ro, retifp,
            retrt, clone, 0);
}

/*
 * Default hop limit selection. The precedence is as follows:
 * 1. Hoplimit value specified via ioctl.
 * 2. (If the outgoing interface is detected) the current
 *     hop limit of the interface specified by router advertisement.
 * 3. The system default hoplimit.
*/
int
in6_selecthlim(struct in6pcb *in6p, struct ifnet *ifp)
{
        if (in6p && in6p->in6p_hops >= 0)
                return (in6p->in6p_hops);
        else if (ifp)
                return (ND_IFINFO(ifp)->chlim);
        else
                return (ip6_defhlim);
}

/*
 * Find an empty port and set it to the specified PCB.
 */
int
in6_pcbsetport(struct sockaddr_in6 *sin6, struct in6pcb *in6p, struct lwp *l)
{
        struct socket *so = in6p->in6p_socket;
        struct inpcbtable *table = in6p->in6p_table;
        int cnt;
        u_int16_t minport, maxport;
        u_int16_t lport, *lastport;
        int wild = 0;
        void *t;
        int error;
        enum kauth_network_req req;

        /* XXX: this is redundant when called from in6_pcbbind */
        if ((so->so_options & (SO_REUSEADDR|SO_REUSEPORT)) == 0 &&
           ((so->so_proto->pr_flags & PR_CONNREQUIRED) == 0 ||
            (so->so_options & SO_ACCEPTCONN) == 0))
                wild = 1;

        if (in6p->in6p_flags & IN6P_LOWPORT) {
#ifndef IPNOPRIVPORTS
                req = KAUTH_REQ_NETWORK_BIND_PRIVPORT;
#else
                req = KAUTH_REQ_NETWORK_BIND_PORT;
#endif

                minport = ip6_lowportmin;
                maxport = ip6_lowportmax;
                lastport = &table->inpt_lastlow;
        } else {
                req = KAUTH_REQ_NETWORK_BIND_PORT;

                minport = ip6_anonportmin;
                maxport = ip6_anonportmax;
                lastport = &table->inpt_lastport;
        }

        /* XXX-kauth: KAUTH_REQ_NETWORK_BIND_AUTOASSIGN_{,PRIV}PORT */
        error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_BIND, req, so,
            sin6, NULL);
        if (error)
                return (EACCES);

        if (minport > maxport) {        /* sanity check */
                u_int16_t swp;
                
                swp = minport;
                minport = maxport;
                maxport = swp;
        }

        lport = *lastport - 1;
        for (cnt = maxport - minport + 1; cnt; cnt--, lport--) {
                if (lport < minport || lport > maxport)
                        lport = maxport;
#ifdef INET
                if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
                        t = in_pcblookup_port(table,
                            *(struct in_addr *)&sin6->sin6_addr.s6_addr32[3],
                            htons(lport), wild);
                } else
#endif
                {
                        t = in6_pcblookup_port(table, &sin6->sin6_addr,
                            htons(lport), wild);
                }
                if (t == 0) {
                        /* We have a free port. Check with the secmodel. */
                        sin6->sin6_port = lport;
                        error = kauth_authorize_network(l->l_cred,
                            KAUTH_NETWORK_BIND, req, so, sin6, NULL);
                        if (error) {
                                /* Secmodel says no. Keep looking. */
                                continue;
                        }
        
                        goto found;
                }
        }

        return (EAGAIN);

found:
        in6p->in6p_flags |= IN6P_ANONPORT;
        *lastport = lport;
        in6p->in6p_lport = htons(lport);
        in6_pcbstate(in6p, IN6P_BOUND);
        return (0);             /* success */
}

void
addrsel_policy_init(void)
{
        init_policy_queue();

        /* initialize the "last resort" policy */
        memset(&defaultaddrpolicy, 0, sizeof(defaultaddrpolicy));
        defaultaddrpolicy.label = ADDR_LABEL_NOTAPP;
}

static struct in6_addrpolicy *
lookup_addrsel_policy(struct sockaddr_in6 *key)
{
        struct in6_addrpolicy *match = NULL;

        match = match_addrsel_policy(key);

        if (match == NULL)
                match = &defaultaddrpolicy;
        else
                match->use++;

        return (match);
}

/*
 * Subroutines to manage the address selection policy table via sysctl.
 */
struct sel_walkarg {
        size_t  w_total;
        size_t  w_given;
        void *  w_where;
        void *w_limit;
};

int
in6_src_sysctl(void *oldp, size_t *oldlenp, void *newp, size_t newlen)
{
        int error = 0;
        int s;

        s = splsoftnet();

        if (newp) {
                error = EPERM;
                goto end;
        }
        if (oldp && oldlenp == NULL) {
                error = EINVAL;
                goto end;
        }
        if (oldp || oldlenp) {
                struct sel_walkarg w;
                size_t oldlen = *oldlenp;

                memset(&w, 0, sizeof(w));
                w.w_given = oldlen;
                w.w_where = oldp;
                if (oldp)
                        w.w_limit = (char *)oldp + oldlen;

                error = walk_addrsel_policy(dump_addrsel_policyent, &w);

                *oldlenp = w.w_total;
                if (oldp && w.w_total > oldlen && error == 0)
                        error = ENOMEM;
        }

  end:
        splx(s);

        return (error);
}

int
in6_src_ioctl(u_long cmd, void *data)
{
        int i;
        struct in6_addrpolicy ent0;

        if (cmd != SIOCAADDRCTL_POLICY && cmd != SIOCDADDRCTL_POLICY)
                return (EOPNOTSUPP); /* check for safety */

        ent0 = *(struct in6_addrpolicy *)data;

        if (ent0.label == ADDR_LABEL_NOTAPP)
                return (EINVAL);
        /* check if the prefix mask is consecutive. */
        if (in6_mask2len(&ent0.addrmask.sin6_addr, NULL) < 0)
                return (EINVAL);
        /* clear trailing garbages (if any) of the prefix address. */
        for (i = 0; i < 4; i++) {
                ent0.addr.sin6_addr.s6_addr32[i] &=
                        ent0.addrmask.sin6_addr.s6_addr32[i];
        }
        ent0.use = 0;

        switch (cmd) {
        case SIOCAADDRCTL_POLICY:
                return (add_addrsel_policyent(&ent0));
        case SIOCDADDRCTL_POLICY:
                return (delete_addrsel_policyent(&ent0));
        }

        return (0);             /* XXX: compromise compilers */
}

/*
 * The followings are implementation of the policy table using a
 * simple tail queue.
 * XXX such details should be hidden.
 * XXX implementation using binary tree should be more efficient.
 */
struct addrsel_policyent {
        TAILQ_ENTRY(addrsel_policyent) ape_entry;
        struct in6_addrpolicy ape_policy;
};

TAILQ_HEAD(addrsel_policyhead, addrsel_policyent);

struct addrsel_policyhead addrsel_policytab;

static void
init_policy_queue(void)
{
        TAILQ_INIT(&addrsel_policytab);
}

static int
add_addrsel_policyent(struct in6_addrpolicy *newpolicy)
{
        struct addrsel_policyent *new, *pol;

        /* duplication check */
        for (pol = TAILQ_FIRST(&addrsel_policytab); pol;
             pol = TAILQ_NEXT(pol, ape_entry)) {
                if (IN6_ARE_ADDR_EQUAL(&newpolicy->addr.sin6_addr,
                    &pol->ape_policy.addr.sin6_addr) &&
                    IN6_ARE_ADDR_EQUAL(&newpolicy->addrmask.sin6_addr,
                    &pol->ape_policy.addrmask.sin6_addr)) {
                        return (EEXIST);        /* or override it? */
                }
        }

        new = malloc(sizeof(*new), M_IFADDR, M_WAITOK|M_ZERO);

        /* XXX: should validate entry */
        new->ape_policy = *newpolicy;

        TAILQ_INSERT_TAIL(&addrsel_policytab, new, ape_entry);

        return (0);
}

static int
delete_addrsel_policyent(struct in6_addrpolicy *key)
{
        struct addrsel_policyent *pol;

        /* search for the entry in the table */
        for (pol = TAILQ_FIRST(&addrsel_policytab); pol;
             pol = TAILQ_NEXT(pol, ape_entry)) {
                if (IN6_ARE_ADDR_EQUAL(&key->addr.sin6_addr,
                    &pol->ape_policy.addr.sin6_addr) &&
                    IN6_ARE_ADDR_EQUAL(&key->addrmask.sin6_addr,
                    &pol->ape_policy.addrmask.sin6_addr)) {
                        break;
                }
        }
        if (pol == NULL) {
                return (ESRCH);
        }

        TAILQ_REMOVE(&addrsel_policytab, pol, ape_entry);

        return (0);
}

static int
walk_addrsel_policy(int (*callback)(struct in6_addrpolicy *, void *), void *w)
{
        struct addrsel_policyent *pol;
        int error = 0;

        TAILQ_FOREACH(pol, &addrsel_policytab, ape_entry) {
                if ((error = (*callback)(&pol->ape_policy, w)) != 0)
                        return error;
        }

        return error;
}

static int
dump_addrsel_policyent(struct in6_addrpolicy *pol, void *arg)
{
        int error = 0;
        struct sel_walkarg *w = arg;

        if (w->w_where && (char *)w->w_where + sizeof(*pol) <= (char *)w->w_limit) {
                if ((error = copyout(pol, w->w_where, sizeof(*pol))) != 0)
                        return error;
                w->w_where = (char *)w->w_where + sizeof(*pol);
        }
        w->w_total += sizeof(*pol);

        return error;
}

static struct in6_addrpolicy *
match_addrsel_policy(struct sockaddr_in6 *key)
{
        struct addrsel_policyent *pent;
        struct in6_addrpolicy *bestpol = NULL, *pol;
        int matchlen, bestmatchlen = -1;
        u_char *mp, *ep, *k, *p, m;

        for (pent = TAILQ_FIRST(&addrsel_policytab); pent;
             pent = TAILQ_NEXT(pent, ape_entry)) {
                matchlen = 0;

                pol = &pent->ape_policy;
                mp = (u_char *)&pol->addrmask.sin6_addr;
                ep = mp + 16;   /* XXX: scope field? */
                k = (u_char *)&key->sin6_addr;
                p = (u_char *)&pol->addr.sin6_addr;
                for (; mp < ep && *mp; mp++, k++, p++) {
                        m = *mp;
                        if ((*k & m) != *p)
                                goto next; /* not match */
                        if (m == 0xff) /* short cut for a typical case */
                                matchlen += 8;
                        else {
                                while (m >= 0x80) {
                                        matchlen++;
                                        m <<= 1;
                                }
                        }
                }

                /* matched.  check if this is better than the current best. */
                if (bestpol == NULL ||
                    matchlen > bestmatchlen) {
                        bestpol = pol;
                        bestmatchlen = matchlen;
                }

          next:
                continue;
        }

        return (bestpol);
}