/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 *
 *      $KAME: in6_ifattach.c,v 1.118 2001/05/24 07:44:00 itojun Exp $
 */

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/systm.h>
#include <sys/counter.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/rmlock.h>
#include <sys/syslog.h>
#include <sys/md5.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/if_llatbl.h>
#include <net/route.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/mld6_var.h>
#include <netinet6/scope6_var.h>

#include <crypto/sha2/sha256.h>
#include <machine/atomic.h>

#ifdef IP6_AUTO_LINKLOCAL
VNET_DEFINE(int, ip6_auto_linklocal) = IP6_AUTO_LINKLOCAL;
#else
VNET_DEFINE(int, ip6_auto_linklocal) = 1;       /* enabled by default */
#endif

VNET_DEFINE(struct callout, in6_tmpaddrtimer_ch);
#define V_in6_tmpaddrtimer_ch           VNET(in6_tmpaddrtimer_ch)

VNET_DEFINE(int, ip6_stableaddr_netifsource) = IP6_STABLEADDR_NETIFSRC_NAME; /* Use interface name by default */

VNET_DECLARE(struct inpcbinfo, ripcbinfo);
#define V_ripcbinfo                     VNET(ripcbinfo)

static int get_rand_ifid(struct ifnet *, struct in6_addr *);
static int in6_ifattach_linklocal(struct ifnet *, struct ifnet *);
static int in6_ifattach_loopback(struct ifnet *);
static void in6_purgemaddrs(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))

#define HMAC_IPAD       0x36
#define HMAC_OPAD       0x5C

/*
 * 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.
 *
 * in6 - upper 64bits are preserved
 */
static int
get_rand_ifid(struct ifnet *ifp, struct in6_addr *in6)
{
        MD5_CTX ctxt;
        struct prison *pr;
        u_int8_t digest[16];
        int hostnamelen;

        pr = curthread->td_ucred->cr_prison;
        mtx_lock(&pr->pr_mtx);
        hostnamelen = strlen(pr->pr_hostname);
#if 0
        /* we need at least several letters as seed for ifid */
        if (hostnamelen < 3) {
                mtx_unlock(&pr->pr_mtx);
                return -1;
        }
#endif

        /* generate 8 bytes of pseudo-random value. */
        bzero(&ctxt, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, pr->pr_hostname, hostnamelen);
        mtx_unlock(&pr->pr_mtx);
        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 link level sockaddr
 */
static struct sockaddr_dl *
get_interface_link_level(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        struct sockaddr_dl *sdl;

        NET_EPOCH_ASSERT();

        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                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;

                return (sdl);
        }

        return (NULL);
}

/*
 * Get hwaddr from link interface
 */
static uint8_t *
in6_get_interface_hwaddr(struct ifnet *ifp, size_t *len)
{
        struct sockaddr_dl *sdl;
        u_int8_t *addr;
        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 };

        sdl = get_interface_link_level(ifp);
        if (sdl == NULL)
                return (NULL);

        addr = LLADDR(sdl);
        *len = sdl->sdl_alen;

        /* get EUI64 */
        switch (ifp->if_type) {
        case IFT_BRIDGE:
        case IFT_ETHER:
        case IFT_L2VLAN:
        case IFT_ATM:
        case IFT_IEEE1394:
                /* IEEE802/EUI64 cases - what others? */
                /* IEEE1394 uses 16byte length address starting with EUI64 */
                if (*len > 8)
                        *len = 8;

                /* look at IEEE802/EUI64 only */
                if (*len != 8 && *len != 6)
                        return (NULL);

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

                break;

        case IFT_GIF:
        case IFT_STF:
                /*
                 * RFC2893 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 (NULL);

        case IFT_INFINIBAND:
                if (*len != 20)
                        return (NULL);
                *len = 8;
                addr += 12;
                break;

        default:
                return (NULL);
        }

        return (addr);
}

/*
 * Get interface identifier for the specified interface.
 * XXX assumes single sockaddr_dl (AF_LINK address) per an interface
 *
 * in6 - upper 64bits are preserved
 */
int
in6_get_hw_ifid(struct ifnet *ifp, struct in6_addr *in6)
{
        size_t hwaddr_len;
        uint8_t *hwaddr;
        static u_int8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };

        hwaddr = in6_get_interface_hwaddr(ifp, &hwaddr_len);
        if (hwaddr == NULL || (hwaddr_len != 6 && hwaddr_len != 8))
                return (-1);

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

        /* 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;
}

/*
 * Validate generated interface id to make sure it does not fall in any reserved range:
 *
 * https://www.iana.org/assignments/ipv6-interface-ids/ipv6-interface-ids.xhtml
 */
static bool
validate_ifid(uint8_t *iid)
{
        static uint8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
        static uint8_t reserved_eth[5] = { 0x02, 0x00, 0x5E, 0xFF, 0xFE };
        static uint8_t reserved_anycast[7] = { 0xFD, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

        /* Subnet-Router Anycast (RFC 4291) */
        if (memcmp(iid, allzero, 8) == 0)
                return (false);

        /*
         * Reserved IPv6 Interface Identifiers corresponding to the IANA Ethernet Block (RFC 4291)
         * and
         * Proxy Mobile IPv6 (RFC 6543)
         */
        if (memcmp(iid, reserved_eth, 5) == 0)
                return (false);

        /* Reserved Subnet Anycast Addresses (RFC 2526) */
        if (memcmp(iid, reserved_anycast, 7) == 0 && iid[7] >= 0x80)
                return (false);

        return (true);
}

/*
 * Get interface identifier for the specified interface, according to
 * RFC 7217 Stable and Opaque IDs with SLAAC, using HMAC-SHA256 digest.
 *
 * in6 - upper 64bits are preserved
 */
bool
in6_get_stableifid(struct ifnet *ifp, struct in6_addr *in6, int prefixlen)
{
        struct sockaddr_dl *sdl;
        const uint8_t *netiface;
        size_t netiface_len, hostuuid_len;
        uint8_t hostuuid[HOSTUUIDLEN + 1], hmac_key[SHA256_BLOCK_LENGTH],
                hk_ipad[SHA256_BLOCK_LENGTH], hk_opad[SHA256_BLOCK_LENGTH];
        uint64_t dad_failures;
        SHA256_CTX ctxt;

        switch (V_ip6_stableaddr_netifsource) {
                case IP6_STABLEADDR_NETIFSRC_ID:
                        sdl = get_interface_link_level(ifp);
                        if (sdl == NULL)
                                return (false);
                        netiface = (uint8_t *)&LLINDEX(sdl);
                        netiface_len = sizeof(u_short); /* real return type of LLINDEX */
                        break;

                case IP6_STABLEADDR_NETIFSRC_MAC:
                        netiface = in6_get_interface_hwaddr(ifp, &netiface_len);
                        if (netiface == NULL)
                                return (false);
                        break;

                case IP6_STABLEADDR_NETIFSRC_NAME:
                default:
                        netiface = (const uint8_t *)if_name(ifp);
                        netiface_len = strlen(netiface);
                        break;
        }

        /* Use hostuuid as constant "secret" key */
        getcredhostuuid(curthread->td_ucred, hostuuid, sizeof(hostuuid));
        if (strncmp(hostuuid, DEFAULT_HOSTUUID, sizeof(hostuuid)) == 0) {
                /* If hostuuid is not set, use a random value */
                arc4rand(hostuuid, HOSTUUIDLEN, 0);
                hostuuid[HOSTUUIDLEN] = '\0';
        }
        hostuuid_len = strlen(hostuuid);

        dad_failures = atomic_load_int(&DAD_FAILURES(ifp));

        /* RFC 7217 section 7, default max retries */
        if (dad_failures > V_ip6_stableaddr_maxretries)
                return (false);

        /*
         * Use hostuuid as basis for HMAC key
         */
        memset(hmac_key, 0, sizeof(hmac_key));
        if (hostuuid_len <= SHA256_BLOCK_LENGTH) {
                /* copy to hmac key variable, zero padded */
                memcpy(hmac_key, hostuuid, hostuuid_len);
        } else {
                /* if longer than block length, use hash of the value, zero padded */
                SHA256_Init(&ctxt);
                SHA256_Update(&ctxt, hostuuid, hostuuid_len);
                SHA256_Final(hmac_key, &ctxt);
        }
        /* XOR key with ipad and opad values */
        for (uint16_t i = 0; i < sizeof(hmac_key); i++) {
                hk_ipad[i] = hmac_key[i] ^ HMAC_IPAD;
                hk_opad[i] = hmac_key[i] ^ HMAC_OPAD;
        }

        /*
         * Generate interface id in a loop, adding an offset to be factored in the hash function.
         * This is necessary, because if the generated interface id happens to be invalid we
         * want to force the hash function to generate a different one, otherwise we would end up
         * in an infinite loop trying the same invalid interface id over and over again.
         *
         * Using an uint8 counter for the offset, so limit iteration at UINT8_MAX. This is a safety
         * measure, this will never iterate more than once or twice in practice.
         */
        for(uint8_t offset = 0; offset < UINT8_MAX; offset++) {
                uint8_t digest[SHA256_DIGEST_LENGTH];

                /* Calculate inner hash */
                SHA256_Init(&ctxt);
                SHA256_Update(&ctxt, hk_ipad, sizeof(hk_ipad));
                SHA256_Update(&ctxt, in6->s6_addr, prefixlen / 8);
                SHA256_Update(&ctxt, netiface, netiface_len);
                SHA256_Update(&ctxt, (uint8_t *)&dad_failures, 8);
                SHA256_Update(&ctxt, hostuuid, hostuuid_len);
                SHA256_Update(&ctxt, &offset, 1);
                SHA256_Final(digest, &ctxt);

                /* Calculate outer hash */
                SHA256_Init(&ctxt);
                SHA256_Update(&ctxt, hk_opad, sizeof(hk_opad));
                SHA256_Update(&ctxt, digest, sizeof(digest));
                SHA256_Final(digest, &ctxt);

                if (validate_ifid(digest)) {
                        /* assumes sizeof(digest) > sizeof(ifid) */
                        memcpy(&in6->s6_addr[8], digest, 8);

                        return (true);
                }
        }

        return (false);
}

/*
 * Get interface identifier for the specified interface.  If it is not
 * available on ifp0, borrow interface identifier from other information
 * sources.
 *
 * altifp - secondary EUI64 source
 */
int
in6_get_ifid(struct ifnet *ifp0, struct ifnet *altifp,
    struct in6_addr *in6)
{
        struct ifnet *ifp;

        NET_EPOCH_ASSERT();

        /* first, try to get it from the interface itself, with stable algorithm, if configured */
        if ((ifp0->if_inet6->nd_flags & ND6_IFF_STABLEADDR) && in6_get_stableifid(ifp0, in6, 64) == 0) {
                nd6log((LOG_DEBUG, "%s: got interface identifier from itself (stable private)\n",
                    if_name(ifp0)));
                goto success;
        }

        /* then/otherwise try to get it from the interface itself */
        if (in6_get_hw_ifid(ifp0, in6) == 0) {
                nd6log((LOG_DEBUG, "%s: got interface identifier from itself\n",
                    if_name(ifp0)));
                goto success;
        }

        /* try secondary EUI64 source. this basically is for ATM PVC */
        if (altifp && in6_get_hw_ifid(altifp, in6) == 0) {
                nd6log((LOG_DEBUG, "%s: got interface identifier from %s\n",
                    if_name(ifp0), if_name(altifp)));
                goto success;
        }

        /* next, try to get it from some other hardware interface */
        CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                if (ifp == ifp0)
                        continue;
                if (in6_get_hw_ifid(ifp, in6) != 0)
                        continue;

                /*
                 * to borrow ifid from other interface, ifid needs to be
                 * globally unique
                 */
                if (IFID_UNIVERSAL(in6)) {
                        nd6log((LOG_DEBUG,
                            "%s: borrow interface identifier from %s\n",
                            if_name(ifp0), if_name(ifp)));
                        goto success;
                }
        }

        /* last resort: get from random number source */
        if (get_rand_ifid(ifp, in6) == 0) {
                nd6log((LOG_DEBUG,
                    "%s: interface identifier generated by random number\n",
                    if_name(ifp0)));
                goto success;
        }

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

success:
        nd6log((LOG_INFO, "%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]));
        return 0;
}

/*
 * altifp - secondary EUI64 source
 */
static int
in6_ifattach_linklocal(struct ifnet *ifp, struct ifnet *altifp)
{
        struct in6_ifaddr *ia;
        struct in6_aliasreq ifra;
        struct nd_prefixctl pr0;
        struct epoch_tracker et;
        struct nd_prefix *pr;
        int error;

        /*
         * configure link-local address.
         */
        in6_prepare_ifra(&ifra, NULL, &in6mask64);

        ifra.ifra_addr.sin6_addr.s6_addr32[0] = htonl(0xfe800000);
        ifra.ifra_addr.sin6_addr.s6_addr32[1] = 0;
        if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                ifra.ifra_addr.sin6_addr.s6_addr32[2] = 0;
                ifra.ifra_addr.sin6_addr.s6_addr32[3] = htonl(1);
        } else {
                NET_EPOCH_ENTER(et);
                error = in6_get_ifid(ifp, altifp, &ifra.ifra_addr.sin6_addr);
                NET_EPOCH_EXIT(et);
                if (error != 0) {
                        nd6log((LOG_ERR,
                            "%s: no ifid available\n", if_name(ifp)));
                        return (-1);
                }
        }
        if (in6_setscope(&ifra.ifra_addr.sin6_addr, ifp, NULL))
                return (-1);

        /* link-local addresses should NEVER expire. */
        ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
        ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;

        /*
         * Now call in6_update_ifa() to do a bunch of procedures to configure
         * a link-local address. We can set the 3rd argument to NULL, because
         * we know there's no other link-local address on the interface
         * and therefore we are adding one (instead of updating one).
         */
        if ((error = in6_update_ifa(ifp, &ifra, NULL,
                                    IN6_IFAUPDATE_DADDELAY)) != 0) {
                /*
                 * XXX: When the interface does not support IPv6, this call
                 * would fail in the SIOCSIFADDR ioctl.  I believe the
                 * notification is rather confusing in this case, so just
                 * suppress it.  (jinmei@kame.net 20010130)
                 */
                if (error != EAFNOSUPPORT)
                        nd6log((LOG_NOTICE, "in6_ifattach_linklocal: failed to "
                            "configure a link-local address on %s "
                            "(errno=%d)\n",
                            if_name(ifp), error));
                return (-1);
        }

        NET_EPOCH_ENTER(et);
        ia = in6ifa_ifpforlinklocal(ifp, 0);
        NET_EPOCH_EXIT(et);
        if (ia == NULL) {
                /*
                 * Another thread removed the address that we just added.
                 * This should be rare, but it happens.
                 */
                nd6log((LOG_NOTICE, "%s: %s: new link-local address "
                        "disappeared\n", __func__, if_name(ifp)));
                return (-1);
        }
        ifa_free(&ia->ia_ifa);

        /*
         * Make the link-local prefix (fe80::%link/64) as on-link.
         * Since we'd like to manage prefixes separately from addresses,
         * we make an ND6 prefix structure for the link-local prefix,
         * and add it to the prefix list as a never-expire prefix.
         * XXX: this change might affect some existing code base...
         */
        bzero(&pr0, sizeof(pr0));
        pr0.ndpr_ifp = ifp;
        /* this should be 64 at this moment. */
        pr0.ndpr_plen = in6_mask2len(&ifra.ifra_prefixmask.sin6_addr, NULL);
        pr0.ndpr_prefix = ifra.ifra_addr;
        /* apply the mask for safety. (nd6_prelist_add will apply it again) */
        IN6_MASK_ADDR(&pr0.ndpr_prefix.sin6_addr, &in6mask64);
        /*
         * Initialize parameters.  The link-local prefix must always be
         * on-link, and its lifetimes never expire.
         */
        pr0.ndpr_raf_onlink = 1;
        pr0.ndpr_raf_auto = 1;  /* probably meaningless */
        pr0.ndpr_vltime = ND6_INFINITE_LIFETIME;
        pr0.ndpr_pltime = ND6_INFINITE_LIFETIME;
        /*
         * Since there is no other link-local addresses, nd6_prefix_lookup()
         * probably returns NULL.  However, we cannot always expect the result.
         * For example, if we first remove the (only) existing link-local
         * address, and then reconfigure another one, the prefix is still
         * valid with referring to the old link-local address.
         */
        if ((pr = nd6_prefix_lookup(&pr0)) == NULL) {
                if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0)
                        return (error);
                /* Reference prefix */
                ia->ia6_ndpr = pr;
                pr->ndpr_addrcnt++;
        }
        nd6_prefix_rele(pr);

        return 0;
}

/*
 * ifp - must be IFT_LOOP
 */
static int
in6_ifattach_loopback(struct ifnet *ifp)
{
        struct in6_aliasreq ifra;
        int error;

        in6_prepare_ifra(&ifra, &in6addr_loopback, &in6mask128);

        /*
         * Always initialize ia_dstaddr (= broadcast address) to loopback
         * address.  Follows IPv4 practice - see in_ifinit().
         */
        ifra.ifra_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
        ifra.ifra_dstaddr.sin6_family = AF_INET6;
        ifra.ifra_dstaddr.sin6_addr = in6addr_loopback;

        /* the loopback  address should NEVER expire. */
        ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
        ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;

        /*
         * We are sure that this is a newly assigned address, so we can set
         * NULL to the 3rd arg.
         */
        if ((error = in6_update_ifa(ifp, &ifra, NULL, 0)) != 0) {
                nd6log((LOG_ERR, "in6_ifattach_loopback: failed to configure "
                    "the loopback address on %s (errno=%d)\n",
                    if_name(ifp), error));
                return (-1);
        }

        return 0;
}

/*
 * compute NI group address, based on the current hostname setting.
 * see RFC 4620.
 *
 * when ifp == NULL, the caller is responsible for filling scopeid.
 *
 * If oldmcprefix == 1, FF02:0:0:0:0:2::/96 is used for NI group address
 * while it is FF02:0:0:0:0:2:FF00::/104 in RFC 4620. 
 */
static int
in6_nigroup0(struct ifnet *ifp, const char *name, int namelen,
    struct in6_addr *in6, int oldmcprefix)
{
        struct prison *pr;
        const char *p;
        u_char *q;
        MD5_CTX ctxt;
        u_int8_t digest[16];
        char l;
        char n[64];     /* a single label must not exceed 63 chars */

        /*
         * If no name is given and namelen is -1,
         * we try to do the hostname lookup ourselves.
         */
        if (!name && namelen == -1) {
                pr = curthread->td_ucred->cr_prison;
                mtx_lock(&pr->pr_mtx);
                name = pr->pr_hostname;
                namelen = strlen(name);
        } else
                pr = NULL;
        if (!name || !namelen) {
                if (pr != NULL)
                        mtx_unlock(&pr->pr_mtx);
                return -1;
        }

        p = name;
        while (p && *p && *p != '.' && p - name < namelen)
                p++;
        if (p == name || p - name > sizeof(n) - 1) {
                if (pr != NULL)
                        mtx_unlock(&pr->pr_mtx);
                return -1;      /* label too long */
        }
        l = p - name;
        strncpy(n, name, l);
        if (pr != NULL)
                mtx_unlock(&pr->pr_mtx);
        n[(int)l] = '\0';
        for (q = n; *q; q++) {
                if ('A' <= *q && *q <= 'Z')
                        *q = *q - 'A' + 'a';
        }

        /* generate 16 bytes of pseudo-random value. */
        bzero(&ctxt, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, &l, sizeof(l));
        MD5Update(&ctxt, n, l);
        MD5Final(digest, &ctxt);

        bzero(in6, sizeof(*in6));
        in6->s6_addr16[0] = IPV6_ADDR_INT16_MLL;
        in6->s6_addr8[11] = 2;
        if (oldmcprefix == 0) {
                in6->s6_addr8[12] = 0xff;
                /* Copy the first 24 bits of 128-bit hash into the address. */
                bcopy(digest, &in6->s6_addr8[13], 3);
        } else {
                /* Copy the first 32 bits of 128-bit hash into the address. */
                bcopy(digest, &in6->s6_addr32[3], sizeof(in6->s6_addr32[3]));
        }
        if (in6_setscope(in6, ifp, NULL))
                return (-1); /* XXX: should not fail */

        return 0;
}

int
in6_nigroup(struct ifnet *ifp, const char *name, int namelen,
    struct in6_addr *in6)
{

        return (in6_nigroup0(ifp, name, namelen, in6, 0));
}

int
in6_nigroup_oldmcprefix(struct ifnet *ifp, const char *name, int namelen,
    struct in6_addr *in6)
{

        return (in6_nigroup0(ifp, name, namelen, in6, 1));
}

/*
 * 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
 *
 * altifp - secondary EUI64 source
 */
void
in6_ifattach(struct ifnet *ifp, struct ifnet *altifp)
{
        struct in6_ifaddr *ia;

        /* XXXGL: can this happen after IFT_PFLOG and IFT_PFSYNC are gone? */
        if (ifp->if_inet6 == NULL)
                return;
        /*
         * quirks based on interface type
         */
        switch (ifp->if_type) {
        case IFT_STF:
                /*
                 * 6to4 interface is a very special kind of beast.
                 * no multicast, no linklocal.  RFC2529 specifies how to make
                 * linklocals for 6to4 interface, but there's no use and
                 * it is rather harmful to have one.
                 */
                ifp->if_inet6->nd_flags &= ~ND6_IFF_AUTO_LINKLOCAL;
                ifp->if_inet6->nd_flags |= ND6_IFF_NO_DAD;
                break;
        default:
                break;
        }

        /*
         * usually, we require multicast capability to the interface
         */
        if ((ifp->if_flags & IFF_MULTICAST) == 0) {
                nd6log((LOG_INFO, "in6_ifattach: "
                    "%s is not multicast capable, IPv6 not enabled\n",
                    if_name(ifp)));
                return;
        }

        /*
         * assign loopback address for loopback interface.
         */
        if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                /*
                 * check that loopback address doesn't exist yet.
                 */
                ia = in6ifa_ifwithaddr(&in6addr_loopback, 0, false);
                if (ia == NULL)
                        in6_ifattach_loopback(ifp);
        }

        /*
         * assign a link-local address, if there's none.
         */
        if (!(ifp->if_inet6->nd_flags & ND6_IFF_IFDISABLED) &&
            ifp->if_inet6->nd_flags & ND6_IFF_AUTO_LINKLOCAL) {
                struct epoch_tracker et;

                NET_EPOCH_ENTER(et);
                ia = in6ifa_ifpforlinklocal(ifp, 0);
                NET_EPOCH_EXIT(et);
                if (ia == NULL)
                        in6_ifattach_linklocal(ifp, altifp);
                else
                        ifa_free(&ia->ia_ifa);
        }
}

/*
 * NOTE: in6_ifdetach() does not support loopback if at this moment.
 *
 * When shutting down a VNET we clean up layers top-down.  In that case
 * upper layer protocols (ulp) are cleaned up already and locks are destroyed
 * and we must not call into these cleanup functions anymore, thus purgeulp
 * is set to 0 in that case by in6_ifdetach_destroy().
 * The normal case of destroying a (cloned) interface still needs to cleanup
 * everything related to the interface and will have purgeulp set to 1.
 */
static void
_in6_ifdetach(struct ifnet *ifp, int purgeulp)
{
        struct ifaddr *ifa, *next;

        /* XXXGL: can this happen after IFT_PFLOG and IFT_PFSYNC are gone? */
        if (ifp->if_inet6 == NULL)
                return;

        /*
         * nuke any of IPv6 addresses we have
         */
        CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, next) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                in6_purgeaddr(ifa);
        }
        if (purgeulp) {
                IN6_MULTI_LOCK();
                in6_pcbpurgeif0(&V_udbinfo, ifp);
                in6_pcbpurgeif0(&V_ulitecbinfo, ifp);
                in6_pcbpurgeif0(&V_ripcbinfo, ifp);
                IN6_MULTI_UNLOCK();
        }
        /* leave from all multicast groups joined */
        in6_purgemaddrs(ifp);

        /*
         * Remove neighbor management table.
         * Enabling the nd6_purge will panic on vmove for interfaces on VNET
         * teardown as the IPv6 layer is cleaned up already and the locks
         * are destroyed.
         */
        if (purgeulp)
                nd6_purge(ifp);
}

void
in6_ifdetach(struct ifnet *ifp)
{

        _in6_ifdetach(ifp, 1);
}

static void
in6_ifextra_free(epoch_context_t ctx)
{
        struct in6_ifextra *ext =
             __containerof(ctx, struct in6_ifextra, epoch_ctx);

        COUNTER_ARRAY_FREE(ext->in6_ifstat,
            sizeof(struct in6_ifstat) / sizeof(uint64_t));
        COUNTER_ARRAY_FREE(ext->icmp6_ifstat,
            sizeof(struct icmp6_ifstat) / sizeof(uint64_t));
        free(ext, M_IFADDR);
}

static void
in6_ifdeparture(void *arg __unused, struct ifnet *ifp)
{
        struct in6_ifextra *ext = ifp->if_inet6;

        /* XXXGL: can this happen after IFT_PFLOG and IFT_PFSYNC are gone? */
        if (ifp->if_inet6 == NULL)
                return;

#ifdef VIMAGE
        /*
         * On VNET shutdown abort here as the stack teardown will do all
         * the work top-down for us.  XXXGL: see comment in in.c:in_ifdetach().
         */
        if (!VNET_IS_SHUTTING_DOWN(ifp->if_vnet))
#endif
                _in6_ifdetach(ifp, 1);
        /*
         * XXXGL: mld and nd bits are left in a consistent state after
         * destructors, but I'm not sure if it safe to call lltable_free() here.
         * Individual lle entries are epoch(9) protected, but the table itself
         * isn't.
         */
        mld_domifdetach(ifp);
        nd6_ifdetach(ifp);
        lltable_free(ext->lltable);
        NET_EPOCH_CALL(in6_ifextra_free, &ext->epoch_ctx);
}
EVENTHANDLER_DEFINE(ifnet_departure_event, in6_ifdeparture, NULL,
    EVENTHANDLER_PRI_ANY);

void
in6_ifdetach_destroy(struct ifnet *ifp)
{

        _in6_ifdetach(ifp, 0);
}

void
in6_tmpaddrtimer(void *arg)
{
        CURVNET_SET((struct vnet *) arg);

        callout_reset(&V_in6_tmpaddrtimer_ch,
            (V_ip6_temp_preferred_lifetime - V_ip6_desync_factor -
            V_ip6_temp_regen_advance) * hz, in6_tmpaddrtimer, curvnet);

        CURVNET_RESTORE();
}

static void
in6_purgemaddrs(struct ifnet *ifp)
{
        struct in6_multi_head inmh;

        SLIST_INIT(&inmh);
        IN6_MULTI_LOCK();
        IN6_MULTI_LIST_LOCK();
        mld_ifdetach(ifp, &inmh);
        IN6_MULTI_LIST_UNLOCK();
        IN6_MULTI_UNLOCK();
        in6m_release_list_deferred(&inmh);

        /*
         * Make sure all multicast deletions invoking if_ioctl() are
         * completed before returning. Else we risk accessing a freed
         * ifnet structure pointer.
         */
        in6m_release_wait(NULL);
}

void
in6_ifattach_destroy(void)
{

        callout_drain(&V_in6_tmpaddrtimer_ch);
}

static void
in6_ifattach_init(void *dummy)
{

        /* Timer for regeneranation of temporary addresses randomize ID. */
        callout_init(&V_in6_tmpaddrtimer_ch, 1);
        callout_reset(&V_in6_tmpaddrtimer_ch,
            (V_ip6_temp_preferred_lifetime - V_ip6_desync_factor -
            V_ip6_temp_regen_advance) * hz,
            in6_tmpaddrtimer, curvnet);
}

/*
 * Cheat.
 * This must be after route_init(), which is now SI_ORDER_THIRD.
 */
SYSINIT(in6_ifattach_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
    in6_ifattach_init, NULL);