/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (C) 2000 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: scope6.c,v 1.10 2000/07/24 13:29:31 itojun Exp $
 */

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/vnet.h>

#include <netinet/in.h>

#include <netinet/ip6.h>
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>

#ifdef ENABLE_DEFAULT_SCOPE
VNET_DEFINE(int, ip6_use_defzone) = 1;
#else
VNET_DEFINE(int, ip6_use_defzone) = 0;
#endif
SYSCTL_DECL(_net_inet6_ip6);

/*
 * The scope6_lock protects the global sid default stored in
 * sid_default below.
 */
static struct mtx scope6_lock;
#define SCOPE6_LOCK_INIT()      mtx_init(&scope6_lock, "scope6_lock", NULL, MTX_DEF)
#define SCOPE6_LOCK()           mtx_lock(&scope6_lock)
#define SCOPE6_UNLOCK()         mtx_unlock(&scope6_lock)
#define SCOPE6_LOCK_ASSERT()    mtx_assert(&scope6_lock, MA_OWNED)

VNET_DEFINE_STATIC(struct scope6_id, sid_default);
#define V_sid_default                   VNET(sid_default)

#define SID(ifp)        (&(ifp)->if_inet6->scope6_id)

static int      scope6_get(struct ifnet *, struct scope6_id *);
static int      scope6_set(struct ifnet *, struct scope6_id *);
static int      scope6_get_default(struct scope6_id *);

void
scope6_init(void)
{

        bzero(&V_sid_default, sizeof(V_sid_default));

        if (!IS_DEFAULT_VNET(curvnet))
                return;

        SCOPE6_LOCK_INIT();
}

void
scope6_ifattach(struct ifnet *ifp)
{
        struct scope6_id *sid = &ifp->if_inet6->scope6_id;

        /*
         * XXX: IPV6_ADDR_SCOPE_xxx macros are not standard.
         * Should we rather hardcode here?
         */
        bzero(sid, sizeof(*sid));
        sid->s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL] = ifp->if_index;
        sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL] = ifp->if_index;
}

int
scope6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
{
        struct in6_ifreq *ifr;

        if (ifp->if_inet6 == NULL)
                return (EPFNOSUPPORT);

        ifr = (struct in6_ifreq *)data;
        switch (cmd) {
        case SIOCSSCOPE6:
                return (scope6_set(ifp,
                    (struct scope6_id *)ifr->ifr_ifru.ifru_scope_id));
        case SIOCGSCOPE6:
                return (scope6_get(ifp,
                    (struct scope6_id *)ifr->ifr_ifru.ifru_scope_id));
        case SIOCGSCOPE6DEF:
                return (scope6_get_default(
                    (struct scope6_id *)ifr->ifr_ifru.ifru_scope_id));
        default:
                return (EOPNOTSUPP);
        }
}

/*
 * XXXGL: The use of IF_ADDR_WLOCK (previously it was IF_AFDATA_LOCK) in this
 * function is quite strange.
 */
static int
scope6_set(struct ifnet *ifp, struct scope6_id *idlist)
{
        int i;
        int error = 0;
        struct scope6_id *sid = NULL;

        IF_ADDR_WLOCK(ifp);
        sid = SID(ifp);

        if (!sid) {     /* paranoid? */
                IF_ADDR_WUNLOCK(ifp);
                return (EINVAL);
        }

        /*
         * XXX: We need more consistency checks of the relationship among
         * scopes (e.g. an organization should be larger than a site).
         */

        /*
         * TODO(XXX): after setting, we should reflect the changes to
         * interface addresses, routing table entries, PCB entries...
         */

        for (i = 0; i < 16; i++) {
                if (idlist->s6id_list[i] &&
                    idlist->s6id_list[i] != sid->s6id_list[i]) {
                        /*
                         * An interface zone ID must be the corresponding
                         * interface index by definition.
                         */
                        if (i == IPV6_ADDR_SCOPE_INTFACELOCAL &&
                            idlist->s6id_list[i] != ifp->if_index) {
                                IF_ADDR_WUNLOCK(ifp);
                                return (EINVAL);
                        }

                        if (i == IPV6_ADDR_SCOPE_LINKLOCAL) {
                                struct epoch_tracker et;

                                NET_EPOCH_ENTER(et);
                                if (!ifnet_byindex(idlist->s6id_list[i])) {
                                        /*
                                         * XXX: theoretically, there should be
                                         * no relationship between link IDs and
                                         * interface IDs, but we check the
                                         * consistency for safety in later use.
                                         */
                                        NET_EPOCH_EXIT(et);
                                        IF_ADDR_WUNLOCK(ifp);
                                        return (EINVAL);
                                }
                                NET_EPOCH_EXIT(et);
                        }

                        /*
                         * XXX: we must need lots of work in this case,
                         * but we simply set the new value in this initial
                         * implementation.
                         */
                        sid->s6id_list[i] = idlist->s6id_list[i];
                }
        }
        IF_ADDR_WUNLOCK(ifp);

        return (error);
}

static int
scope6_get(struct ifnet *ifp, struct scope6_id *idlist)
{
        struct epoch_tracker et;
        struct scope6_id *sid;

        /* We only need to lock the interface's afdata for SID() to work. */
        NET_EPOCH_ENTER(et);
        sid = SID(ifp);
        if (sid == NULL) {      /* paranoid? */
                NET_EPOCH_EXIT(et);
                return (EINVAL);
        }

        *idlist = *sid;

        NET_EPOCH_EXIT(et);
        return (0);
}

/*
 * Get a scope of the address. Node-local, link-local, site-local or global.
 */
int
in6_addrscope(const struct in6_addr *addr)
{

        if (IN6_IS_ADDR_MULTICAST(addr)) {
                /*
                 * Addresses with reserved value F must be treated as
                 * global multicast addresses.
                 */
                if (IPV6_ADDR_MC_SCOPE(addr) == 0x0f)
                        return (IPV6_ADDR_SCOPE_GLOBAL);
                return (IPV6_ADDR_MC_SCOPE(addr));
        }
        if (IN6_IS_ADDR_LINKLOCAL(addr) ||
            IN6_IS_ADDR_LOOPBACK(addr))
                return (IPV6_ADDR_SCOPE_LINKLOCAL);
        if (IN6_IS_ADDR_SITELOCAL(addr))
                return (IPV6_ADDR_SCOPE_SITELOCAL);
        return (IPV6_ADDR_SCOPE_GLOBAL);
}

/*
 * ifp - note that this might be NULL
 */

void
scope6_setdefault(struct ifnet *ifp)
{

        /*
         * Currently, this function just sets the default "interfaces"
         * and "links" according to the given interface.
         * We might eventually have to separate the notion of "link" from
         * "interface" and provide a user interface to set the default.
         */
        SCOPE6_LOCK();
        if (ifp) {
                V_sid_default.s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL] =
                        ifp->if_index;
                V_sid_default.s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL] =
                        ifp->if_index;
        } else {
                V_sid_default.s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL] = 0;
                V_sid_default.s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL] = 0;
        }
        SCOPE6_UNLOCK();
}

static int
scope6_get_default(struct scope6_id *idlist)
{

        SCOPE6_LOCK();
        *idlist = V_sid_default;
        SCOPE6_UNLOCK();

        return (0);
}

u_int32_t
scope6_addr2default(struct in6_addr *addr)
{
        u_int32_t id;

        /*
         * special case: The loopback address should be considered as
         * link-local, but there's no ambiguity in the syntax.
         */
        if (IN6_IS_ADDR_LOOPBACK(addr))
                return (0);

        /*
         * XXX: 32-bit read is atomic on all our platforms, is it OK
         * not to lock here?
         */
        SCOPE6_LOCK();
        id = V_sid_default.s6id_list[in6_addrscope(addr)];
        SCOPE6_UNLOCK();
        return (id);
}

/*
 * Validate the specified scope zone ID in the sin6_scope_id field.  If the ID
 * is unspecified (=0), needs to be specified, and the default zone ID can be
 * used, the default value will be used.
 * This routine then generates the kernel-internal form: if the address scope
 * of is interface-local or link-local, embed the interface index in the
 * address.
 */
int
sa6_embedscope(struct sockaddr_in6 *sin6, int defaultok)
{
        u_int32_t zoneid;

        if ((zoneid = sin6->sin6_scope_id) == 0 && defaultok)
                zoneid = scope6_addr2default(&sin6->sin6_addr);

        if (zoneid != 0 &&
            (IN6_IS_SCOPE_LINKLOCAL(&sin6->sin6_addr) ||
            IN6_IS_ADDR_MC_INTFACELOCAL(&sin6->sin6_addr))) {
                struct epoch_tracker et;

                /*
                 * At this moment, we only check interface-local and
                 * link-local scope IDs, and use interface indices as the
                 * zone IDs assuming a one-to-one mapping between interfaces
                 * and links.
                 */
                NET_EPOCH_ENTER(et);
                if (ifnet_byindex(zoneid) == NULL) {
                        NET_EPOCH_EXIT(et);
                        return (ENXIO);
                }
                NET_EPOCH_EXIT(et);

                /* XXX assignment to 16bit from 32bit variable */
                sin6->sin6_addr.s6_addr16[1] = htons(zoneid & 0xffff);
                sin6->sin6_scope_id = 0;
        }

        return 0;
}

/*
 * generate standard sockaddr_in6 from embedded form.
 */
int
sa6_recoverscope(struct sockaddr_in6 *sin6)
{
        char ip6buf[INET6_ADDRSTRLEN];
        u_int32_t zoneid;

        if (IN6_IS_SCOPE_LINKLOCAL(&sin6->sin6_addr) ||
            IN6_IS_ADDR_MC_INTFACELOCAL(&sin6->sin6_addr)) {
                /*
                 * KAME assumption: link id == interface id
                 */
                zoneid = ntohs(sin6->sin6_addr.s6_addr16[1]);
                if (zoneid) {
                        struct epoch_tracker et;

                        NET_EPOCH_ENTER(et);
                        /* sanity check */
                        if (!ifnet_byindex(zoneid)) {
                                NET_EPOCH_EXIT(et);
                                return (ENXIO);
                        }
                        NET_EPOCH_EXIT(et);
                        if (sin6->sin6_scope_id != 0 &&
                            zoneid != sin6->sin6_scope_id) {
                                log(LOG_NOTICE,
                                    "%s: embedded scope mismatch: %s%%%d. "
                                    "sin6_scope_id was overridden\n", __func__,
                                    ip6_sprintf(ip6buf, &sin6->sin6_addr),
                                    sin6->sin6_scope_id);
                        }
                        sin6->sin6_addr.s6_addr16[1] = 0;
                        sin6->sin6_scope_id = zoneid;
                }
        }

        return 0;
}

/*
 * Determine the appropriate scope zone ID for in6 and ifp.  If ret_id is
 * non NULL, it is set to the zone ID.  If the zone ID needs to be embedded
 * in the in6_addr structure, in6 will be modified.
 *
 * ret_id - unnecessary?
 */
int
in6_setscope(struct in6_addr *in6, struct ifnet *ifp, u_int32_t *ret_id)
{
        int scope;
        u_int32_t zoneid = 0;
        struct scope6_id *sid;

        /*
         * special case: the loopback address can only belong to a loopback
         * interface.
         */
        if (IN6_IS_ADDR_LOOPBACK(in6)) {
                if (!(ifp->if_flags & IFF_LOOPBACK))
                        return (EINVAL);
        } else {
                scope = in6_addrscope(in6);
                if (scope == IPV6_ADDR_SCOPE_INTFACELOCAL ||
                    scope == IPV6_ADDR_SCOPE_LINKLOCAL) {
                        /*
                         * Currently we use interface indices as the
                         * zone IDs for interface-local and link-local
                         * scopes.
                         */
                        zoneid = ifp->if_index;
                        in6->s6_addr16[1] = htons(zoneid & 0xffff); /* XXX */
                } else if (scope != IPV6_ADDR_SCOPE_GLOBAL) {
                        struct epoch_tracker et;

                        NET_EPOCH_ENTER(et);
                        /* XXXGL */
                        if (ifp->if_inet6 == NULL) {
                                NET_EPOCH_EXIT(et);
                                return (ENETDOWN);
                        }
                        sid = SID(ifp);
                        zoneid = sid->s6id_list[scope];
                        NET_EPOCH_EXIT(et);
                }
        }

        if (ret_id != NULL)
                *ret_id = zoneid;

        return (0);
}

/*
 * Just clear the embedded scope identifier.  Return 0 if the original address
 * is intact; return non 0 if the address is modified.
 */
int
in6_clearscope(struct in6_addr *in6)
{
        int modified = 0;

        if (IN6_IS_SCOPE_LINKLOCAL(in6) || IN6_IS_ADDR_MC_INTFACELOCAL(in6)) {
                if (in6->s6_addr16[1] != 0)
                        modified = 1;
                in6->s6_addr16[1] = 0;
        }

        return (modified);
}

/*
 * Return the scope identifier or zero.
 */
uint16_t
in6_getscope(const struct in6_addr *in6)
{

        if (IN6_IS_SCOPE_LINKLOCAL(in6) || IN6_IS_ADDR_MC_INTFACELOCAL(in6))
                return (in6->s6_addr16[1]);

        return (0);
}

/*
 * Returns scope zone id for the unicast address @in6.
 *
 * Returns 0 for global unicast and loopback addresses.
 * Returns interface index for the link-local addresses.
 */
uint32_t
in6_get_unicast_scopeid(const struct in6_addr *in6, const struct ifnet *ifp)
{

        if (IN6_IS_SCOPE_LINKLOCAL(in6))
                return (ifp->if_index);
        return (0);
}

void
in6_set_unicast_scopeid(struct in6_addr *in6, uint32_t scopeid)
{

        in6->s6_addr16[1] = htons(scopeid & 0xffff);
}

/*
 * Return pointer to ifnet structure, corresponding to the zone id of
 * link-local scope.
 */
struct ifnet*
in6_getlinkifnet(uint32_t zoneid)
{
        struct ifnet *ifp;

        ifp = ifnet_byindex((u_short)zoneid);

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

        /* An interface might not be IPv6 capable. */
        if (ifp->if_inet6 == NULL) {
                log(LOG_NOTICE,
                    "%s: embedded scope points to an interface without "
                    "IPv6: %s%%%d.\n", __func__,
                    if_name(ifp), zoneid);
                return (NULL);
        }

        return (ifp);
}

/*
 * Return zone id for the specified scope.
 */
uint32_t
in6_getscopezone(const struct ifnet *ifp, int scope)
{

        if (scope == IPV6_ADDR_SCOPE_INTFACELOCAL ||
            scope == IPV6_ADDR_SCOPE_LINKLOCAL)
                return (ifp->if_index);
        if (scope >= 0 && scope < IPV6_ADDR_SCOPES_COUNT)
                return (SID(ifp)->s6id_list[scope]);
        return (0);
}

/*
 * Extracts scope from address @dst, stores cleared address
 * inside @dst and zone inside @scopeid
 */
void
in6_splitscope(const struct in6_addr *src, struct in6_addr *dst,
    uint32_t *scopeid)
{
        uint32_t zoneid;

        *dst = *src;
        zoneid = ntohs(in6_getscope(dst));
        in6_clearscope(dst);
        *scopeid = zoneid;
}

/*
 * This function is for checking sockaddr_in6 structure passed
 * from the application level (usually).
 *
 * sin6_scope_id should be set for link-local unicast, link-local and
 * interface-local  multicast addresses.
 *
 * If it is zero, then look into default zone ids. If default zone id is
 * not set or disabled, then return error.
 */
int
sa6_checkzone(struct sockaddr_in6 *sa6)
{
        int scope;

        scope = in6_addrscope(&sa6->sin6_addr);
        if (scope == IPV6_ADDR_SCOPE_GLOBAL)
                return (sa6->sin6_scope_id ? EINVAL: 0);
        if (IN6_IS_ADDR_MULTICAST(&sa6->sin6_addr) &&
            scope != IPV6_ADDR_SCOPE_LINKLOCAL &&
            scope != IPV6_ADDR_SCOPE_INTFACELOCAL) {
                if (sa6->sin6_scope_id == 0 && V_ip6_use_defzone != 0)
                        sa6->sin6_scope_id = V_sid_default.s6id_list[scope];
                return (0);
        }
        /*
         * Since ::1 address always configured on the lo0, we can
         * automatically set its zone id, when it is not specified.
         * Return error, when specified zone id doesn't match with
         * actual value.
         */
        if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr)) {
                if (sa6->sin6_scope_id == 0)
                        sa6->sin6_scope_id = in6_getscopezone(V_loif, scope);
                else if (sa6->sin6_scope_id != in6_getscopezone(V_loif, scope))
                        return (EADDRNOTAVAIL);
        }
        /* XXX: we can validate sin6_scope_id here */
        if (sa6->sin6_scope_id != 0)
                return (0);
        if (V_ip6_use_defzone != 0)
                sa6->sin6_scope_id = V_sid_default.s6id_list[scope];
        /* Return error if we can't determine zone id */
        return (sa6->sin6_scope_id ? 0: EADDRNOTAVAIL);
}

/*
 * This function is similar to sa6_checkzone, but it uses given ifp
 * to initialize sin6_scope_id.
 */
int
sa6_checkzone_ifp(struct ifnet *ifp, struct sockaddr_in6 *sa6)
{
        int scope;

        scope = in6_addrscope(&sa6->sin6_addr);
        if (scope == IPV6_ADDR_SCOPE_LINKLOCAL ||
            scope == IPV6_ADDR_SCOPE_INTFACELOCAL) {
                if (sa6->sin6_scope_id == 0) {
                        sa6->sin6_scope_id = in6_getscopezone(ifp, scope);
                        return (0);
                } else if (sa6->sin6_scope_id != in6_getscopezone(ifp, scope))
                        return (EADDRNOTAVAIL);
        }
        return (sa6_checkzone(sa6));
}