/*      $NetBSD: in6_ifattach.c,v 1.122 2024/04/11 07:34:37 knakahara Exp $     */
/*      $KAME: in6_ifattach.c,v 1.124 2001/07/18 08:32:51 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6_ifattach.c,v 1.122 2024/04/11 07:34:37 knakahara Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kmem.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/md5.h>
#include <sys/socketvar.h>
#include <sys/cprng.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/ip6.h>
#include <netinet6/in6_ifattach.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#include <netinet6/ip6_mroute.h>
#include <netinet6/scope6_var.h>

int ip6_auto_linklocal = 1;     /* enable by default */

#if 0
static int get_hostid_ifid(struct ifnet *, struct in6_addr *);
#endif
static int get_ifid(struct ifnet *, struct ifnet *, struct in6_addr *);
static int in6_ifattach_linklocal(struct ifnet *, struct ifnet *);
static int in6_ifattach_loopback(struct ifnet *);

#define EUI64_GBIT      0x01
#define EUI64_UBIT      0x02
#define EUI64_TO_IFID(in6)      do {(in6)->s6_addr[8] ^= EUI64_UBIT; } while (/*CONSTCOND*/ 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))

#if 0
/*
 * Generate a last-resort interface identifier from hostid.
 * works only for certain architectures (like sparc).
 * also, using hostid itself may constitute a privacy threat, much worse
 * than MAC addresses (hostids are used for software licensing).
 * maybe we should use MD5(hostid) instead.
 *
 * in6 - upper 64bits are preserved
 */
static int
get_hostid_ifid(struct ifnet *ifp, struct in6_addr *in6)
{
        int off, len;
        static const uint8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
        static const uint8_t allone[8] =
            { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

        if (!hostid)
                return -1;

        /* get up to 8 bytes from the hostid field - should we get */
        len = (sizeof(hostid) > 8) ? 8 : sizeof(hostid);
        off = sizeof(*in6) - len;
        memcpy(&in6->s6_addr[off], &hostid, len);

        /* make sure we do not return anything bogus */
        if (memcmp(&in6->s6_addr[8], allzero, sizeof(allzero)))
                return -1;
        if (memcmp(&in6->s6_addr[8], allone, sizeof(allone)))
                return -1;

        /* 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;
}
#endif

/*
 * 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(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. */
        memset(&ctxt, 0, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, (u_char *)hostname, hostnamelen);
        MD5Final(digest, &ctxt);

        /* assumes sizeof(digest) > sizeof(ifid) */
        memcpy(&in6->s6_addr[8], digest, 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.
 *
 * in6 - upper 64bits are preserved
 */
int
in6_get_hw_ifid(struct ifnet *ifp, struct in6_addr *in6)
{
        struct ifaddr *ifa;
        const struct sockaddr_dl *sdl = NULL;
        const char *addr = NULL; /* XXX gcc 4.8 -Werror=maybe-uninitialized */
        size_t addrlen = 0; /* XXX gcc 4.8 -Werror=maybe-uninitialized */
        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 };
        int s;

        s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                const struct sockaddr_dl *tsdl;
                if (ifa->ifa_addr->sa_family != AF_LINK)
                        continue;
                tsdl = satocsdl(ifa->ifa_addr);
                if (tsdl == NULL || tsdl->sdl_alen == 0)
                        continue;
                if (sdl == NULL || ifa == ifp->if_dl || ifa == ifp->if_hwdl) {
                        sdl = tsdl;
                        addr = CLLADDR(sdl);
                        addrlen = sdl->sdl_alen;
                }
                if (ifa == ifp->if_hwdl)
                        break;
        }
        pserialize_read_exit(s);

        if (sdl == NULL)
                return -1;

        switch (ifp->if_type) {
        case IFT_IEEE1394:
        case IFT_IEEE80211:
                /* IEEE1394 uses 16byte length address starting with EUI64 */
                if (addrlen > 8)
                        addrlen = 8;
                break;
        default:
                break;
        }

        /* get EUI64 */
        switch (ifp->if_type) {
        /* IEEE802/EUI64 cases - what others? */
        case IFT_ETHER:
        case IFT_ATM:
        case IFT_IEEE1394:
        case IFT_IEEE80211:
                /* 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 (memcmp(addr, allzero, addrlen) == 0)
                        return -1;
                if (memcmp(addr, allone, addrlen) == 0)
                        return -1;

                /* make EUI64 address */
                if (addrlen == 8)
                        memcpy(&in6->s6_addr[8], addr, 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;

                memset(&in6->s6_addr[8], 0, 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:
        case IFT_IPSEC:
#ifdef IFT_STF
        case IFT_STF:
#endif
                /*
                 * 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 -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 &&
            memcmp(&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.
 *
 * altifp - secondary EUI64 source
 */
static int
get_ifid(struct ifnet *ifp0, struct ifnet *altifp, 
        struct in6_addr *in6)
{
        struct ifnet *ifp;
        int s;

        /* first, 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 */
        s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                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));
                        pserialize_read_exit(s);
                        goto success;
                }
        }
        pserialize_read_exit(s);

#if 0
        /* get from hostid - only for certain architectures */
        if (get_hostid_ifid(ifp, in6) == 0) {
                nd6log(LOG_DEBUG,
                    "%s: interface identifier generated by hostid\n",
                    if_name(ifp0));
                goto success;
        }
#endif

        /* last resort: get from random number source */
        if (get_rand_ifid(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_aliasreq ifra;
        int error;

        /*
         * configure link-local address.
         */
        memset(&ifra, 0, sizeof(ifra));

        /*
         * in6_update_ifa() does not use ifra_name, but we accurately set it
         * for safety.
         */
        strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));

        ifra.ifra_addr.sin6_family = AF_INET6;
        ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
        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 {
                if (get_ifid(ifp, altifp, &ifra.ifra_addr.sin6_addr) != 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;

        sockaddr_in6_init(&ifra.ifra_prefixmask, &in6mask64, 0, 0, 0);
        /* 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, IN6_IFAUPDATE_DADDELAY)) != 0) {
                /*
                 * XXX: When the interface does not support IPv6, this call
                 * would fail in the SIOCINITIFADDR 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,
                            "failed to configure a link-local address on %s "
                            "(errno=%d)\n",
                            if_name(ifp), error);
                return -1;
        }

        return 0;
}

/*
 * ifp - must be IFT_LOOP
 */

static int
in6_ifattach_loopback(struct ifnet *ifp)
{
        struct in6_aliasreq ifra;
        int error;

        memset(&ifra, 0, sizeof(ifra));

        /*
         * in6_update_ifa() does not use ifra_name, but we accurately set it
         * for safety.
         */
        strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));

        sockaddr_in6_init(&ifra.ifra_prefixmask, &in6mask128, 0, 0, 0);

        /*
         * Always initialize ia_dstaddr (= broadcast address) to loopback
         * address.  Follows IPv4 practice - see in_ifinit().
         */
        sockaddr_in6_init(&ifra.ifra_dstaddr, &in6addr_loopback, 0, 0, 0);

        sockaddr_in6_init(&ifra.ifra_addr, &in6addr_loopback, 0, 0, 0);

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

        /* we don't need to perform DAD on loopback interfaces. */
        ifra.ifra_flags |= IN6_IFF_NODAD;

        /*
         * 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, 0)) != 0) {
                nd6log(LOG_ERR, "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 draft-ietf-ipngwg-icmp-name-lookup-* (04 and later).
 *
 * when ifp == NULL, the caller is responsible for filling scopeid.
 */
int
in6_nigroup(struct ifnet *ifp, const char *name, int namelen, 
        struct sockaddr_in6 *sa6)
{
        const char *p;
        u_int8_t *q;
        MD5_CTX ctxt;
        u_int8_t digest[16];
        u_int8_t l;
        u_int8_t n[64]; /* a single label must not exceed 63 chars */

        if (!namelen || !name)
                return -1;

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

        /* generate 8 bytes of pseudo-random value. */
        memset(&ctxt, 0, sizeof(ctxt));
        MD5Init(&ctxt);
        MD5Update(&ctxt, &l, sizeof(l));
        MD5Update(&ctxt, n, l);
        MD5Final(digest, &ctxt);

        memset(sa6, 0, sizeof(*sa6));
        sa6->sin6_family = AF_INET6;
        sa6->sin6_len = sizeof(*sa6);
        sa6->sin6_addr.s6_addr16[0] = htons(0xff02);
        sa6->sin6_addr.s6_addr8[11] = 2;
        memcpy(&sa6->sin6_addr.s6_addr32[3], digest,
            sizeof(sa6->sin6_addr.s6_addr32[3]));
        if (in6_setscope(&sa6->sin6_addr, ifp, NULL))
                return -1; /* XXX: should not fail */

        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
 *
 * altifp - secondary EUI64 source
 */
void
in6_ifattach(struct ifnet *ifp, struct ifnet *altifp)
{
        struct in6_ifaddr *ia;
        struct in6_addr in6;

        KASSERT(IFNET_LOCKED(ifp));

        /* some of the interfaces are inherently not IPv6 capable */
        switch (ifp->if_type) {
        case IFT_BRIDGE:
        case IFT_L2TP:
        case IFT_IEEE8023ADLAG:
#ifdef IFT_PFLOG
        case IFT_PFLOG:
#endif
#ifdef IFT_PFSYNC
        case IFT_PFSYNC:
#endif
                ND_IFINFO(ifp)->flags &= ~ND6_IFF_AUTO_LINKLOCAL;
                ND_IFINFO(ifp)->flags |= ND6_IFF_IFDISABLED;
                return;
        }

        /*
         * if link mtu is too small, don't try to configure IPv6.
         * remember there could be some link-layer that has special
         * fragmentation logic.
         */
        if (ifp->if_mtu < IPV6_MMTU) {
                nd6log(LOG_INFO, "%s has too small MTU, IPv6 not enabled\n",
                    if_name(ifp));
                return;
        }

        /*
         * quirks based on interface type
         */
        switch (ifp->if_type) {
#ifdef IFT_STF
        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.
                 */
                ND_IFINFO(ifp)->flags &= ~ND6_IFF_AUTO_LINKLOCAL;
                return;
#endif
        case IFT_CARP:
                return;
        default:
                break;
        }

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

        /*
         * assign loopback address for loopback interface.
         * XXX multiple loopback interface case.
         */
        if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
                in6 = in6addr_loopback;
                /* These are safe and atomic thanks to IFNET_LOCK */
                if (in6ifa_ifpwithaddr(ifp, &in6) == NULL) {
                        if (in6_ifattach_loopback(ifp) != 0)
                                return;
                }
        }

        /*
         * assign a link-local address, if there's none.
         */
        if (!(ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) &&
            ND_IFINFO(ifp)->flags & ND6_IFF_AUTO_LINKLOCAL) {
                int bound = curlwp_bind();
                struct psref psref;
                ia = in6ifa_ifpforlinklocal_psref(ifp, 0, &psref);
                if (ia == NULL && in6_ifattach_linklocal(ifp, altifp) != 0) {
                        printf("%s: cannot assign link-local address\n",
                            ifp->if_xname);
                }
                ia6_release(ia, &psref);
                curlwp_bindx(bound);
        }
}

/*
 * NOTE: in6_ifdetach() does not support loopback if at this moment.
 * We don't need this function in bsdi, because interfaces are never removed
 * from the ifnet list in bsdi.
 */
void
in6_ifdetach(struct ifnet *ifp)
{

        /* nuke any of IPv6 addresses we have */
        if_purgeaddrs(ifp, AF_INET6, in6_purgeaddr);

        in6_purge_multi(ifp);

        /* remove ip6_mrouter stuff */
        ip6_mrouter_detach(ifp);

        /* remove neighbor management table */
        nd6_purge(ifp, NULL);
}