path: root/sys/netinet6/in6_ifattach.c

/*	$OpenBSD: in6_ifattach.c,v 1.10 2000/05/05 07:58:15 itojun Exp $	*/
/*	$KAME: in6_ifattach.c,v 1.53 2000/04/16 14:01:42 itojun 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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/kernel.h>
#include <sys/md5k.h>

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

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>

#include <net/net_osdep.h>

struct in6_ifstat **in6_ifstat = NULL;
struct icmp6_ifstat **icmp6_ifstat = NULL;
size_t in6_ifstatmax = 0;
size_t icmp6_ifstatmax = 0;
unsigned long in6_maxmtu = 0;

static int get_rand_ifid __P((struct ifnet *, struct in6_addr *));
static int get_hw_ifid __P((struct ifnet *, struct in6_addr *));
static int get_ifid __P((struct ifnet *, struct ifnet *, struct in6_addr *));
static int in6_ifattach_addaddr __P((struct ifnet *, struct in6_ifaddr *));
static int in6_ifattach_linklocal __P((struct ifnet *, struct ifnet *));
static int in6_ifattach_loopback __P((struct ifnet *));

#define EUI64_GBIT	0x01
#define EUI64_UBIT	0x02
#define EUI64_TO_IFID(in6)	do {(in6)->s6_addr[8] ^= EUI64_UBIT; } while (0)
#define EUI64_GROUP(in6)	((in6)->s6_addr[8] & EUI64_GBIT)
#define EUI64_INDIVIDUAL(in6)	(!EUI64_GROUP(in6))
#define EUI64_LOCAL(in6)	((in6)->s6_addr[8] & EUI64_UBIT)
#define EUI64_UNIVERSAL(in6)	(!EUI64_LOCAL(in6))

#define IFID_LOCAL(in6)		(!EUI64_LOCAL(in6))
#define IFID_UNIVERSAL(in6)	(!EUI64_UNIVERSAL(in6))

/*
 * Generate a last-resort interface identifier, when the machine has no
 * IEEE802/EUI64 address sources.
 * The goal here is to get an interface identifier that is
 * (1) random enough and (2) does not change across reboot.
 * We currently use MD5(hostname) for it.
 */
static int
get_rand_ifid(ifp, in6)
	struct ifnet *ifp;
	struct in6_addr *in6;	/*upper 64bits are preserved */
{
	MD5_CTX ctxt;
	u_int8_t digest[16];

#if 0
	/* we need at least several letters as seed for ifid */
	if (hostnamelen < 3)
		return -1;
#endif

	/* generate 8 bytes of pseudo-random value. */
	bzero(&ctxt, sizeof(ctxt));
	MD5Init(&ctxt);
	MD5Update(&ctxt, hostname, hostnamelen);
	MD5Final(digest, &ctxt);

	/* assumes sizeof(digest) > sizeof(ifid) */
	bcopy(digest, &in6->s6_addr[8], 8);

	/* make sure to set "u" bit to local, and "g" bit to individual. */
	in6->s6_addr[8] &= ~EUI64_GBIT;	/* g bit to "individual" */
	in6->s6_addr[8] |= EUI64_UBIT;	/* u bit to "local" */

	/* convert EUI64 into IPv6 interface identifier */
	EUI64_TO_IFID(in6);

	return 0;
}

/*
 * Get interface identifier for the specified interface.
 * XXX assumes single sockaddr_dl (AF_LINK address) per an interface
 */
static int
get_hw_ifid(ifp, in6)
	struct ifnet *ifp;
	struct in6_addr *in6;	/*upper 64bits are preserved */
{
	struct ifaddr *ifa;
	struct sockaddr_dl *sdl;
	u_int8_t *addr;
	size_t addrlen;
	static u_int8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
	static u_int8_t allone[8] =
		{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

	for (ifa = ifp->if_addrlist.tqh_first;
	     ifa;
	     ifa = ifa->ifa_list.tqe_next)
	{
		if (ifa->ifa_addr->sa_family != AF_LINK)
			continue;
		sdl = (struct sockaddr_dl *)ifa->ifa_addr;
		if (sdl == NULL)
			continue;
		if (sdl->sdl_alen == 0)
			continue;

		goto found;
	}

	return -1;

found:
	addr = LLADDR(sdl);
	addrlen = sdl->sdl_alen;

	/* get EUI64 */
	switch (ifp->if_type) {
	case IFT_ETHER:
	case IFT_FDDI:
	case IFT_ATM:
		/* IEEE802/EUI64 cases - what others? */

		/* look at IEEE802/EUI64 only */
		if (addrlen != 8 && addrlen != 6)
			return -1;

		/*
		 * check for invalid MAC address - on bsdi, we see it a lot
		 * since wildboar configures all-zero MAC on pccard before
		 * card insertion.
		 */
		if (bcmp(addr, allzero, addrlen) == 0)
			return -1;
		if (bcmp(addr, allone, addrlen) == 0)
			return -1;

		/* make EUI64 address */
		if (addrlen == 8)
			bcopy(addr, &in6->s6_addr[8], 8);
		else if (addrlen == 6) {
			in6->s6_addr[8] = addr[0];
			in6->s6_addr[9] = addr[1];
			in6->s6_addr[10] = addr[2];
			in6->s6_addr[11] = 0xff;
			in6->s6_addr[12] = 0xfe;
			in6->s6_addr[13] = addr[3];
			in6->s6_addr[14] = addr[4];
			in6->s6_addr[15] = addr[5];
		}
		break;

	case IFT_ARCNET:
		if (addrlen != 1)
			return -1;
		if (!addr[0])
			return -1;

		bzero(&in6->s6_addr[8], 8);
		in6->s6_addr[15] = addr[0];

		/*
		 * due to insufficient bitwidth, we mark it local.
		 */
		in6->s6_addr[8] &= ~EUI64_GBIT;	/* g bit to "individual" */
		in6->s6_addr[8] |= EUI64_UBIT;	/* u bit to "local" */
		break;

	case IFT_GIF:
#ifdef IFT_STF
	case IFT_STF:
#endif
		/*
		 * mech-06 says: "SHOULD use IPv4 address as ifid source".
		 * however, IPv4 address is not very suitable as unique
		 * identifier source (can be renumbered).
		 * we don't do this.
		 */
		return -1;

	default:
		return -1;
	}

	/* sanity check: g bit must not indicate "group" */
	if (EUI64_GROUP(in6))
		return -1;

	/* convert EUI64 into IPv6 interface identifier */
	EUI64_TO_IFID(in6);

	/*
	 * sanity check: ifid must not be all zero, avoid conflict with
	 * subnet router anycast
	 */
	if ((in6->s6_addr[8] & ~(EUI64_GBIT | EUI64_UBIT)) == 0x00 &&
	    bcmp(&in6->s6_addr[9], allzero, 7) == 0) {
		return -1;
	}

	return 0;
}

/*
 * Get interface identifier for the specified interface.  If it is not
 * available on ifp0, borrow interface identifier from other information
 * sources.
 */
static int
get_ifid(ifp0, altifp, in6)
	struct ifnet *ifp0;
	struct ifnet *altifp;	/*secondary EUI64 source*/
	struct in6_addr *in6;
{
	struct ifnet *ifp;

	/* first, try to get it from the interface itself */
	if (get_hw_ifid(ifp0, in6) == 0) {
#ifdef ND6_DEBUG
		printf("%s: got interface identifier from itself\n",
		    if_name(ifp0));
#endif
		goto success;
	}

	/* try secondary EUI64 source. this basically is for ATM PVC */
	if (altifp && get_hw_ifid(altifp, in6) == 0) {
#ifdef ND6_DEBUG
		printf("%s: got interface identifier from %s\n",
		    if_name(ifp0), ifname(altifp));
#endif
		goto success;
	}

	/* next, try to get it from some other hardware interface */
	for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_list.tqe_next)
	{
		if (ifp == ifp0)
			continue;
		if (get_hw_ifid(ifp, in6) != 0)
			continue;

		/*
		 * to borrow ifid from other interface, ifid needs to be
		 * globally unique
		 */
		if (IFID_UNIVERSAL(in6)) {

#ifdef ND6_DEBUG
			printf("%s: borrow interface identifier from %s\n",
			    if_name(ifp0), if_name(ifp));
#endif
			goto success;
		}
	}

	/* last resort: get from random number source */
	if (get_rand_ifid(ifp, in6) == 0) {
#ifdef ND6_DEBUG
		printf("%s: interface identifier generated by random number\n",
		    if_name(ifp0));
#endif
		goto success;
	}

	printf("%s: failed to get interface identifier", if_name(ifp0));
	return -1;

success:
#ifdef ND6_DEBUG
	printf("%s: ifid: "
		"%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
		if_name(ifp0),
		in6->s6_addr[8], in6->s6_addr[9],
		in6->s6_addr[10], in6->s6_addr[11],
		in6->s6_addr[12], in6->s6_addr[13],
		in6->s6_addr[14], in6->s6_addr[15]);
#endif
	return 0;
}

/*
 * configure IPv6 interface address.  XXX code duplicated with in.c
 */
static int
in6_ifattach_addaddr(ifp, ia)
	struct ifnet *ifp;
	struct in6_ifaddr *ia;
{
	struct in6_ifaddr *oia;
	struct ifaddr *ifa;
	int error;
	int rtflag;
	struct in6_addr llsol;

	/*
	 * initialize if_addrlist, if we are the very first one
	 */
	ifa = TAILQ_FIRST(&ifp->if_addrlist);
	if (ifa == NULL) {
		TAILQ_INIT(&ifp->if_addrlist);
	}

	/*
	 * link the interface address to global list
	 */
	TAILQ_INSERT_TAIL(&ifp->if_addrlist, (struct ifaddr *)ia, ifa_list);
	ia->ia_ifa.ifa_refcnt++;

	/*
	 * Also link into the IPv6 address chain beginning with in6_ifaddr.
	 * kazu opposed it, but itojun & jinmei wanted.
	 */
	if ((oia = in6_ifaddr) != NULL) {
		for (; oia->ia_next; oia = oia->ia_next)
			continue;
		oia->ia_next = ia;
	} else
		in6_ifaddr = ia;
	ia->ia_ifa.ifa_refcnt++;

	/*
	 * give the interface a chance to initialize, in case this
	 * is the first address to be added.
	 */
	if (ifp->if_ioctl != NULL) {
		int s;
		s = splimp();
		error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia);
		splx(s);
	} else
		error = 0;
	if (error) {
		switch (error) {
		case EAFNOSUPPORT:
			printf("%s: IPv6 not supported\n", if_name(ifp));
			break;
		default:
			printf("%s: SIOCSIFADDR error %d\n", if_name(ifp),
			    error);
			break;
		}

		/* undo changes */
		TAILQ_REMOVE(&ifp->if_addrlist, (struct ifaddr *)ia, ifa_list);
		IFAFREE(&ia->ia_ifa);
		if (oia)
			oia->ia_next = ia->ia_next;
		else
			in6_ifaddr = ia->ia_next;
		IFAFREE(&ia->ia_ifa);
		return -1;
	}

	/* configure link-layer address resolution */
	rtflag = 0;
	if (IN6_ARE_ADDR_EQUAL(&ia->ia_prefixmask.sin6_addr, &in6mask128))
		rtflag = RTF_HOST;
	else {
		switch (ifp->if_type) {
		case IFT_LOOP:
#ifdef IFT_STF
		case IFT_STF:
#endif
			rtflag = 0;
			break;
		default:
			ia->ia_ifa.ifa_rtrequest = nd6_rtrequest;
			ia->ia_ifa.ifa_flags |= RTF_CLONING;
			rtflag = RTF_CLONING;
			break;
		}
	}

	/* add route to the interface. */
	rtrequest(RTM_ADD,
		  (struct sockaddr *)&ia->ia_addr,
		  (struct sockaddr *)&ia->ia_addr,
		  (struct sockaddr *)&ia->ia_prefixmask,
		  RTF_UP | rtflag,
		  (struct rtentry **)0);
	ia->ia_flags |= IFA_ROUTE;

	if ((rtflag & RTF_CLONING) != 0 &&
	    (ifp->if_flags & IFF_MULTICAST) != 0) {
		/* Restore saved multicast addresses (if any). */
		in6_restoremkludge(ia, ifp);

		/*
		 * join solicited multicast address
		 */
		bzero(&llsol, sizeof(llsol));
		llsol.s6_addr16[0] = htons(0xff02);
		llsol.s6_addr16[1] = htons(ifp->if_index);
		llsol.s6_addr32[1] = 0;
		llsol.s6_addr32[2] = htonl(1);
		llsol.s6_addr32[3] = ia->ia_addr.sin6_addr.s6_addr32[3];
		llsol.s6_addr8[12] = 0xff;
		(void)in6_addmulti(&llsol, ifp, &error);

		/* XXX should we run DAD on other interface types? */
		switch (ifp->if_type) {
#if 1
		case IFT_ARCNET:
		case IFT_ETHER:
		case IFT_FDDI:
#else
		default:
#endif
			/* mark the address TENTATIVE, if needed. */
			ia->ia6_flags |= IN6_IFF_TENTATIVE;
			/* nd6_dad_start() will be called in in6_if_up */
		}
	}

	return 0;
}

static int
in6_ifattach_linklocal(ifp, altifp)
	struct ifnet *ifp;
	struct ifnet *altifp;	/*secondary EUI64 source*/
{
	struct in6_ifaddr *ia;

	/*
	 * configure link-local address
	 */
	ia = (struct in6_ifaddr *)malloc(sizeof(*ia), M_IFADDR, M_WAITOK);
	bzero((caddr_t)ia, sizeof(*ia));
	ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
	if (ifp->if_flags & IFF_POINTOPOINT)
		ia->ia_ifa.ifa_dstaddr = (struct sockaddr *)&ia->ia_dstaddr;
	else
		ia->ia_ifa.ifa_dstaddr = NULL;
	ia->ia_ifa.ifa_netmask = (struct sockaddr *)&ia->ia_prefixmask;
	ia->ia_ifp = ifp;

	bzero(&ia->ia_prefixmask, sizeof(ia->ia_prefixmask));
	ia->ia_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_prefixmask.sin6_family = AF_INET6;
	ia->ia_prefixmask.sin6_addr = in6mask64;

	/* just in case */
	bzero(&ia->ia_dstaddr, sizeof(ia->ia_dstaddr));
	ia->ia_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_dstaddr.sin6_family = AF_INET6;

	bzero(&ia->ia_addr, sizeof(ia->ia_addr));
	ia->ia_addr.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_addr.sin6_family = AF_INET6;
	ia->ia_addr.sin6_addr.s6_addr16[0] = htons(0xfe80);
	ia->ia_addr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
	ia->ia_addr.sin6_addr.s6_addr32[1] = 0;
	if (ifp->if_flags & IFF_LOOPBACK) {
		ia->ia_addr.sin6_addr.s6_addr32[2] = 0;
		ia->ia_addr.sin6_addr.s6_addr32[3] = htonl(1);
	} else {
		if (get_ifid(ifp, altifp, &ia->ia_addr.sin6_addr) != 0) {
#ifdef ND6_DEBUG
			printf("%s: no ifid available\n", if_name(ifp));
#endif
			free(ia, M_IFADDR);
			return -1;
		}
	}

	ia->ia_ifa.ifa_metric = ifp->if_metric;

	if (in6_ifattach_addaddr(ifp, ia) != 0) {
		/* ia will be freed on failure */
		return -1;
	}

	return 0;
}

static int
in6_ifattach_loopback(ifp)
	struct ifnet *ifp;	/* must be IFT_LOOP */
{
	struct in6_ifaddr *ia;

	/*
	 * configure link-local address
	 */
	ia = (struct in6_ifaddr *)malloc(sizeof(*ia), M_IFADDR, M_WAITOK);
	bzero((caddr_t)ia, sizeof(*ia));
	ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
	ia->ia_ifa.ifa_dstaddr = (struct sockaddr *)&ia->ia_dstaddr;
	ia->ia_ifa.ifa_netmask = (struct sockaddr *)&ia->ia_prefixmask;
	ia->ia_ifp = ifp;

	bzero(&ia->ia_prefixmask, sizeof(ia->ia_prefixmask));
	ia->ia_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_prefixmask.sin6_family = AF_INET6;
	ia->ia_prefixmask.sin6_addr = in6mask128;

	/*
	 * Always initialize ia_dstaddr (= broadcast address) to loopback
	 * address, to make getifaddr happier.
	 *
	 * For BSDI, it is mandatory.  The BSDI version of
	 * ifa_ifwithroute() rejects to add a route to the loopback
	 * interface.  Even for other systems, loopback looks somewhat
	 * special.
	 */
	bzero(&ia->ia_dstaddr, sizeof(ia->ia_dstaddr));
	ia->ia_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_dstaddr.sin6_family = AF_INET6;
	ia->ia_dstaddr.sin6_addr = in6addr_loopback;

	bzero(&ia->ia_addr, sizeof(ia->ia_addr));
	ia->ia_addr.sin6_len = sizeof(struct sockaddr_in6);
	ia->ia_addr.sin6_family = AF_INET6;
	ia->ia_addr.sin6_addr = in6addr_loopback;

	ia->ia_ifa.ifa_metric = ifp->if_metric;

	if (in6_ifattach_addaddr(ifp, ia) != 0) {
		/* ia will be freed on failure */
		return -1;
	}

	return 0;
}

/*
 * XXX multiple loopback interface needs more care.  for instance,
 * nodelocal address needs to be configured onto only one of them.
 * XXX multiple link-local address case
 */
void
in6_ifattach(ifp, altifp)
	struct ifnet *ifp;
	struct ifnet *altifp;	/* secondary EUI64 source */
{
	static size_t if_indexlim = 8;
	struct sockaddr_in6 mltaddr;
	struct sockaddr_in6 mltmask;
	struct sockaddr_in6 gate;
	struct sockaddr_in6 mask;
	struct in6_ifaddr *ia;
	struct in6_addr in6;

	/*
	 * We have some arrays that should be indexed by if_index.
	 * since if_index will grow dynamically, they should grow too.
	 *	struct in6_ifstat **in6_ifstat
	 *	struct icmp6_ifstat **icmp6_ifstat
	 */
	if (in6_ifstat == NULL || icmp6_ifstat == NULL ||
	    if_index >= if_indexlim) {
		size_t n;
		caddr_t q;
		size_t olim;

		olim = if_indexlim;
		while (if_index >= if_indexlim)
			if_indexlim <<= 1;

		/* grow in6_ifstat */
		n = if_indexlim * sizeof(struct in6_ifstat *);
		q = (caddr_t)malloc(n, M_IFADDR, M_WAITOK);
		bzero(q, n);
		if (in6_ifstat) {
			bcopy((caddr_t)in6_ifstat, q,
				olim * sizeof(struct in6_ifstat *));
			free((caddr_t)in6_ifstat, M_IFADDR);
		}
		in6_ifstat = (struct in6_ifstat **)q;
		in6_ifstatmax = if_indexlim;

		/* grow icmp6_ifstat */
		n = if_indexlim * sizeof(struct icmp6_ifstat *);
		q = (caddr_t)malloc(n, M_IFADDR, M_WAITOK);
		bzero(q, n);
		if (icmp6_ifstat) {
			bcopy((caddr_t)icmp6_ifstat, q,
				olim * sizeof(struct icmp6_ifstat *));
			free((caddr_t)icmp6_ifstat, M_IFADDR);
		}
		icmp6_ifstat = (struct icmp6_ifstat **)q;
		icmp6_ifstatmax = if_indexlim;
	}

	/*
	 * quirks based on interface type
	 */
	switch (ifp->if_type) {
#ifdef IFT_STF
	case IFT_STF:
		/*
		 * 6to4 interface is a very speical kind of beast.
		 * no multicast, no linklocal (based on 03 draft).
		 */
		goto statinit;
#endif
	default:
		break;
	}

	/*
	 * usually, we require multicast capability to the interface
	 */
	if ((ifp->if_flags & IFF_MULTICAST) == 0) {
		printf("%s: not multicast capable, IPv6 not enabled\n",
		    if_name(ifp));
		return;
	}

	/*
	 * assign link-local address, if there's none 
	 */
	ia = in6ifa_ifpforlinklocal(ifp, 0);
	if (ia == NULL) {
		if (in6_ifattach_linklocal(ifp, altifp) != 0)
			return;
		ia = in6ifa_ifpforlinklocal(ifp, 0);

		if (ia == NULL) {
			printf("%s: failed to add link-local address",
			    if_name(ifp));

			/* we can't initialize multicasts without link-local */
			goto statinit;
		}
	}

	if (ifp->if_flags & IFF_POINTOPOINT) {
		/*
		 * route local address to loopback
		 */
		bzero(&gate, sizeof(gate));
		gate.sin6_len = sizeof(struct sockaddr_in6);
		gate.sin6_family = AF_INET6;
		gate.sin6_addr = in6addr_loopback;
		bzero(&mask, sizeof(mask));
		mask.sin6_len = sizeof(struct sockaddr_in6);
		mask.sin6_family = AF_INET6;
		mask.sin6_addr = in6mask64;
		rtrequest(RTM_ADD,
			  (struct sockaddr *)&ia->ia_addr,
			  (struct sockaddr *)&gate,
			  (struct sockaddr *)&mask,
			  RTF_UP|RTF_HOST,
			  (struct rtentry **)0);
	}

	/*
	 * assign loopback address for loopback interface
	 * XXX multiple loopback interface case
	 */
	in6 = in6addr_loopback;
	if (ifp->if_flags & IFF_LOOPBACK) {
		if (in6ifa_ifpwithaddr(ifp, &in6) == NULL) {
			if (in6_ifattach_loopback(ifp) != 0)
				return;
		}
	}

#ifdef DIAGNOSTIC
	if (!ia) {
		panic("ia == NULL in in6_ifattach");
		/*NOTREACHED*/
	}
#endif

	/*
	 * join multicast
	 */
	if (ifp->if_flags & IFF_MULTICAST) {
		int error;	/* not used */
		struct in6_multi *in6m;

		/* Restore saved multicast addresses(if any). */
		in6_restoremkludge(ia, ifp);

		bzero(&mltmask, sizeof(mltmask));
		mltmask.sin6_len = sizeof(struct sockaddr_in6);
		mltmask.sin6_family = AF_INET6;
		mltmask.sin6_addr = in6mask32;

		/*
		 * join link-local all-nodes address
		 */
		bzero(&mltaddr, sizeof(mltaddr));
		mltaddr.sin6_len = sizeof(struct sockaddr_in6);
		mltaddr.sin6_family = AF_INET6;
		mltaddr.sin6_addr = in6addr_linklocal_allnodes;
		mltaddr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);

		IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
		if (in6m == NULL) {
			rtrequest(RTM_ADD,
				  (struct sockaddr *)&mltaddr,
				  (struct sockaddr *)&ia->ia_addr,
				  (struct sockaddr *)&mltmask,
				  RTF_UP|RTF_CLONING,  /* xxx */
				  (struct rtentry **)0);
			(void)in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
		}

		if (ifp->if_flags & IFF_LOOPBACK) {
			in6 = in6addr_loopback;
			ia = in6ifa_ifpwithaddr(ifp, &in6);
			/*
			 * join node-local all-nodes address, on loopback
			 */
			mltaddr.sin6_addr = in6addr_nodelocal_allnodes;

			IN6_LOOKUP_MULTI(mltaddr.sin6_addr, ifp, in6m);
			if (in6m == NULL && ia != NULL) {
				rtrequest(RTM_ADD,
					  (struct sockaddr *)&mltaddr,
					  (struct sockaddr *)&ia->ia_addr,
					  (struct sockaddr *)&mltmask,
					  RTF_UP,
					  (struct rtentry **)0);
				(void)in6_addmulti(&mltaddr.sin6_addr, ifp, &error);
			}
		}
	}

statinit:;

	/* update dynamically. */
	if (in6_maxmtu < ifp->if_mtu)
		in6_maxmtu = ifp->if_mtu;

	if (in6_ifstat[ifp->if_index] == NULL) {
		in6_ifstat[ifp->if_index] = (struct in6_ifstat *)
			malloc(sizeof(struct in6_ifstat), M_IFADDR, M_WAITOK);
		bzero(in6_ifstat[ifp->if_index], sizeof(struct in6_ifstat));
	}
	if (icmp6_ifstat[ifp->if_index] == NULL) {
		icmp6_ifstat[ifp->if_index] = (struct icmp6_ifstat *)
			malloc(sizeof(struct icmp6_ifstat), M_IFADDR, M_WAITOK);
		bzero(icmp6_ifstat[ifp->if_index], sizeof(struct icmp6_ifstat));
	}

	/* initialize NDP variables */
	nd6_ifattach(ifp);
}

/*
 * NOTE: in6_ifdetach() does not support loopback if at this moment.
 */
void
in6_ifdetach(ifp)
	struct ifnet *ifp;
{
	struct in6_ifaddr *ia, *oia;
	struct ifaddr *ifa, *next;
	struct rtentry *rt;
	short rtflags;
	struct sockaddr_in6 sin6;
	struct in6_multi *in6m;

	/* nuke prefix list.  this may try to remove some of ifaddrs as well */
	in6_purgeprefix(ifp);

	/* remove neighbor management table */
	nd6_purge(ifp);

	/* nuke any of IPv6 addresses we have */
	for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = next)
	{
		next = ifa->ifa_list.tqe_next;
		if (ifa->ifa_addr->sa_family != AF_INET6)
			continue;
		in6_purgeaddr(ifa, ifp);
	}

	/* undo everything done by in6_ifattach(), just in case */
	for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = next)
	{
		if (ifa->ifa_addr->sa_family != AF_INET6
		 || !IN6_IS_ADDR_LINKLOCAL(&satosin6(&ifa->ifa_addr)->sin6_addr)) {
			continue;
		}

		ia = (struct in6_ifaddr *)ifa;

		/* leave from all multicast groups joined */
		while ((in6m = LIST_FIRST(&ia->ia6_multiaddrs)) != NULL)
			in6_delmulti(in6m);

		/* remove from the routing table */
		if ((ia->ia_flags & IFA_ROUTE)
		 && (rt = rtalloc1((struct sockaddr *)&ia->ia_addr, 0))) {
			rtflags = rt->rt_flags;
			rtfree(rt);
			rtrequest(RTM_DELETE,
				(struct sockaddr *)&ia->ia_addr,
				(struct sockaddr *)&ia->ia_addr,
				(struct sockaddr *)&ia->ia_prefixmask,
				rtflags, (struct rtentry **)0);
		}

		/* remove from the linked list */
		TAILQ_REMOVE(&ifp->if_addrlist, (struct ifaddr *)ia, ifa_list);
		IFAFREE(&ia->ia_ifa);

		/* also remove from the IPv6 address chain(itojun&jinmei) */
		oia = ia;
		if (oia == (ia = in6_ifaddr))
			in6_ifaddr = ia->ia_next;
		else {
			while (ia->ia_next && (ia->ia_next != oia))
				ia = ia->ia_next;
			if (ia->ia_next)
				ia->ia_next = oia->ia_next;
#ifdef ND6_DEBUG
			else
				printf("%s: didn't unlink in6ifaddr from "
				    "list\n", if_name(ifp));
#endif
		}

		IFAFREE(&oia->ia_ifa);
	}

	/* cleanup multicast address kludge table, if there is any */
	in6_purgemkludge(ifp);

	/* remove neighbor management table */
	nd6_purge(ifp);

	/* remove route to link-local allnodes multicast (ff02::1) */
	bzero(&sin6, sizeof(sin6));
	sin6.sin6_len = sizeof(struct sockaddr_in6);
	sin6.sin6_family = AF_INET6;
	sin6.sin6_addr = in6addr_linklocal_allnodes;
	sin6.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
	if ((rt = rtalloc1((struct sockaddr *)&sin6, 0)) != NULL) {
		rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
			rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
		rtfree(rt);
	}
}