in6_src.c

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//==========================================================================
//
//      src/sys/netinet6/in6_src.c
//
//==========================================================================
//####BSDCOPYRIGHTBEGIN####
//
// -------------------------------------------
//
// Portions of this software may have been derived from OpenBSD, 
// FreeBSD or other sources, and are covered by the appropriate
// copyright disclaimers included herein.
//
// Portions created by Red Hat are
// Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
//
// -------------------------------------------
//
//####BSDCOPYRIGHTEND####
//==========================================================================

/*	$KAME: in6_src.c,v 1.96 2001/12/24 10:39:29 jinmei 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/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sockio.h>
#include <sys/errno.h>

#include <net/if.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/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/nd6.h>
#include <netinet6/scope6_var.h> 

#ifdef MIP6
#include <netinet6/mip6.h>
#endif /* MIP6 */

#if defined(__NetBSD__)
extern struct ifnet loif[NLOOP];
#endif

#define ADDR_LABEL_NOTAPP (-1)
struct in6_addrpolicy defaultaddrpolicy;

int ip6_prefer_tempaddr = 0;

#ifdef NEW_STRUCT_ROUTE
static int in6_selectif __P((struct sockaddr_in6 *, struct ip6_pktopts *,
			     struct ip6_moptions *, 
			     struct route *ro,
			     struct ifnet **));
#else
static int in6_selectif __P((struct sockaddr_in6 *, struct ip6_pktopts *,
			     struct ip6_moptions *, 
			     struct route_in6 *ro,
			     struct ifnet **));
#endif

static struct in6_addrpolicy *lookup_addrsel_policy __P((struct sockaddr_in6 *));

static void init_policy_queue __P((void));
static int add_addrsel_policyent __P((struct in6_addrpolicy *));
static int delete_addrsel_policyent __P((struct in6_addrpolicy *));
static struct in6_addrpolicy *match_addrsel_policy __P((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.
 */
#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)

struct in6_addr *
in6_selectsrc(struct sockaddr_in6 *dstsock, struct ip6_pktopts *opts,
              struct ip6_moptions *mopts, struct route *ro,
              struct ifnet **ifpp, struct in6_addr *laddr,
              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;
#ifdef MIP6
	struct hif_softc *sc;
#ifdef MIP6_ALLOW_COA_FALLBACK
	struct mip6_bu *mbu_dst;
	u_int8_t coafallback = 0;
#endif
#endif

	dst = &dstsock->sin6_addr;
	*errorp = 0;
	if (ifpp)
		*ifpp = NULL;

	/*
	 * 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;

		/* get the outgoing interface */
		if ((*errorp = in6_selectif(dstsock, opts, mopts, ro, &ifp))
		    != 0) {
			return(NULL);
		}

		/*
		 * determine the appropriate zone id of the source based on
		 * the zone of the destination and the outgoing interface.
		 */
		bzero(&srcsock, sizeof(srcsock));
		srcsock.sin6_family = AF_INET6;
		srcsock.sin6_len = sizeof(srcsock);
		srcsock.sin6_addr = pi->ipi6_addr;
		if (ifp) {
			int64_t zone;

			zone = in6_addr2zoneid(ifp, &pi->ipi6_addr);
			if (zone < 0) { /* XXX: this should not happen */
				*errorp = EINVAL;
				return(NULL);
			}
			srcsock.sin6_scope_id = zone;
		}
		if ((*errorp = in6_embedscope(&srcsock.sin6_addr, &srcsock))
		    != 0) {
			return(NULL);
		}
#ifndef SCOPEDROUTING
		srcsock.sin6_scope_id = 0; /* XXX: ifa_ifwithaddr expects 0 */
#endif
		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(&pi->ipi6_addr);
	}

	/*
	 * Otherwise, if the socket has already bound the source, just use it.
	 */
	if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr))
		return(laddr);

	/*
	 * If the address is not specified, choose the best one based on
	 * the outgoing interface and the destination address.
	 */
	/* get the outgoing interface */
	if ((*errorp = in6_selectif(dstsock, opts, mopts, ro, &ifp)) != 0)
		return(NULL);

#ifdef MIP6
#ifdef MIP6_ALLOW_COA_FALLBACK
	for (sc = TAILQ_FIRST(&hif_softc_list);
	     sc;
	     sc = TAILQ_NEXT(sc, hif_entry)) {
		mbu_dst = mip6_bu_list_find_withpaddr(&sc->hif_bu_list, dst);
		if (mbu_dst != NULL)
			coafallback = mbu_dst->mbu_coafallback;
	}
#endif /* MIP6_ALLOW_COA_FALLBACK */
#endif /* MIP6 */

#ifdef DIAGNOSTIC
	if (ifp == NULL)	/* this should not happen */
		panic("in6_selectsrc: NULL ifp");
#endif
	for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
		int new_scope = -1, new_matchlen = -1;
		struct in6_addrpolicy *new_policy = NULL;
		int64_t srczone, dstzone;
		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 ((dstzone = in6_addr2zoneid(ifp1, dst)) < 0 ||
		    dstzone != in6_addr2zoneid(ifp, dst)) {
			continue;
		}
		if ((srczone = in6_addr2zoneid(ifp1, &ia->ia_addr.sin6_addr))
		    < 0 ||
		    srczone != in6_addr2zoneid(ifp, &ia->ia_addr.sin6_addr)) {
			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;

		/* 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 */
		/*
		 * XXX: This is a TODO.  We should probably merge the MIP6
		 * case above.
		 */
#ifdef MIP6
		/*
		 * 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.
		 */
		{
			struct mip6_bu *mbu_ia_best = NULL, *mbu_ia = NULL;

			if (ia_best->ia6_flags & IN6_IFF_HOME) {
				/*
				 * find a binding update entry for ia_best.
				 */
				for (sc = TAILQ_FIRST(&hif_softc_list);
				     sc;
				     sc = TAILQ_NEXT(sc, hif_entry)) {
					mbu_ia_best = mip6_bu_list_find_home_registration(
						&sc->hif_bu_list,
						&ia->ia_addr.sin6_addr);
					if (mbu_ia_best)
						break;
				}
			}
			if (ia->ia6_flags & IN6_IFF_HOME) {
				/*
				 * find a binding update entry for ia.
				 */
				for (sc = TAILQ_FIRST(&hif_softc_list);
				     sc;
				     sc = TAILQ_NEXT(sc, hif_entry)) {
					mbu_ia = mip6_bu_list_find_home_registration(
						&sc->hif_bu_list,
						&ia->ia_addr.sin6_addr);
					if (mbu_ia)
						break;
				}
			}
			/*
			 * if the binding update entry for a certain address
			 * exists and its registration status is
			 * MIP6_BU_REG_STATE_NOTREG, the address is a home
			 * address and a care of addres simultaneously.
			 */
			if ((mbu_ia_best &&
			     (mbu_ia_best->mbu_reg_state
			      == MIP6_BU_REG_STATE_NOTREG))
			    &&
			    !(mbu_ia &&
			      (mbu_ia->mbu_reg_state
			       == MIP6_BU_REG_STATE_NOTREG))) {
				NEXT(4);
			}
			if (!(mbu_ia_best &&
			      (mbu_ia_best->mbu_reg_state
			       == MIP6_BU_REG_STATE_NOTREG))
			    &&
			    (mbu_ia &&
			     (mbu_ia->mbu_reg_state
			      == MIP6_BU_REG_STATE_NOTREG))) {
				REPLACE(4);
			}
		}
#ifdef MIP6_ALLOW_COA_FALLBACK
		if (coafallback) {
			/*
			 * if the peer doesn't recognize a home
			 * address destination option, we will use a
			 * CoA as a source address instead of a home
			 * address we have registered before.  Though
			 * this behavior may arouse a mip6 beleiver's
			 * anger, is very useful in the current
			 * transition period that many hosts don't
			 * recognize a home address destination
			 * option...
			 */
			if ((ia_best->ia6_flags & IN6_IFF_HOME) == 0 &&
			    (ia->ia6_flags & IN6_IFF_HOME) != 0) {
				/* XXX will break stat! */
				NEXT(0);
			}
			if ((ia_best->ia6_flags & IN6_IFF_HOME) != 0 &&
			    (ia->ia6_flags & IN6_IFF_HOME) == 0) {
				/* XXX will break stat! */
				REPLACE(0);
			}
		} else
#endif
		{
			/*
			 * 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);
			}