/*      $NetBSD: scope6.c,v 1.23 2020/06/16 17:12:18 maxv Exp $ */
/*      $KAME$  */

/*
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: scope6.c,v 1.23 2020/06/16 17:12:18 maxv Exp $");

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

#include <net/if.h>

#include <netinet/in.h>

#include <netinet6/in6_var.h>
#include <netinet6/scope6_var.h>

#ifdef ENABLE_DEFAULT_SCOPE
int ip6_use_defzone = 1;
#else
int ip6_use_defzone = 0;
#endif

static struct scope6_id sid_default;
#define SID(ifp) \
    ((ifp)->if_afdata[AF_INET6] == NULL ? NULL : \
        ((struct in6_ifextra *)(ifp)->if_afdata[AF_INET6])->scope6_id)

void
scope6_init(void)
{

        memset(&sid_default, 0, sizeof(sid_default));
}

struct scope6_id *
scope6_ifattach(struct ifnet *ifp)
{
        struct scope6_id *sid;

        sid = malloc(sizeof(*sid), M_IFADDR, M_WAITOK | M_ZERO);

        /*
         * XXX: IPV6_ADDR_SCOPE_xxx macros are not standard.
         * Should we rather hardcode here?
         */
        sid->s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL] = ifp->if_index;
        sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL] = ifp->if_index;
#ifdef MULTI_SCOPE
        /* by default, we don't care about scope boundary for these scopes. */
        sid->s6id_list[IPV6_ADDR_SCOPE_SITELOCAL] = 1;
        sid->s6id_list[IPV6_ADDR_SCOPE_ORGLOCAL] = 1;
#endif

        return sid;
}

void
scope6_ifdetach(struct scope6_id *sid)
{

        free(sid, M_IFADDR);
}

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

        if (addr->s6_addr[0] == 0xfe) {
                scope = addr->s6_addr[1] & 0xc0;

                switch (scope) {
                case 0x80:
                        return IPV6_ADDR_SCOPE_LINKLOCAL;
                case 0xc0:
                        return IPV6_ADDR_SCOPE_SITELOCAL;
                default:
                        return IPV6_ADDR_SCOPE_GLOBAL; /* just in case */
                }
        }

        if (addr->s6_addr[0] == 0xff) {
                scope = addr->s6_addr[1] & 0x0f;

                /*
                 * due to other scope such as reserved,
                 * return scope doesn't work.
                 */
                switch (scope) {
                case IPV6_ADDR_SCOPE_INTFACELOCAL:
                        return IPV6_ADDR_SCOPE_INTFACELOCAL;
                case IPV6_ADDR_SCOPE_LINKLOCAL:
                        return IPV6_ADDR_SCOPE_LINKLOCAL;
                case IPV6_ADDR_SCOPE_SITELOCAL:
                        return IPV6_ADDR_SCOPE_SITELOCAL;
                default:
                        return IPV6_ADDR_SCOPE_GLOBAL;
                }
        }

        if (memcmp(&in6addr_loopback, addr, sizeof(*addr) - 1) == 0) {
                if (addr->s6_addr[15] == 1) /* loopback */
                        return IPV6_ADDR_SCOPE_LINKLOCAL;
                if (addr->s6_addr[15] == 0) {
                        /*
                         * Regard the unspecified addresses as global,
                         * since it has no ambiguity.
                         * XXX: not sure if it's correct...
                         */
                        return IPV6_ADDR_SCOPE_GLOBAL;
                }
        }

        return IPV6_ADDR_SCOPE_GLOBAL;
}

uint32_t
scope6_addr2default(const struct in6_addr *addr)
{
        uint32_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?
         */
        id = sid_default.s6id_list[in6_addrscope(addr)];

        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)
{
        struct ifnet *ifp;
        uint32_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))) {
                int s;
                /*
                 * 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.
                 */
                s = pserialize_read_enter();
                ifp = if_byindex(zoneid);
                if (ifp == NULL) {
                        pserialize_read_exit(s);
                        return ENXIO;
                }
                pserialize_read_exit(s);

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

                sin6->sin6_scope_id = 0;
        }

        return 0;
}

struct sockaddr *
sockaddr_in6_externalize(struct sockaddr *dst, socklen_t socklen,
    const struct sockaddr *src)
{
        struct sockaddr_in6 *sin6;

        sin6 = satosin6(sockaddr_copy(dst, socklen, src));

        if (sin6 == NULL || sa6_recoverscope(sin6) != 0)
                return NULL;

        return dst;
}

/*
 * generate standard sockaddr_in6 from embedded form.
 */
int
sa6_recoverscope(struct sockaddr_in6 *sin6)
{
        uint32_t zoneid;
        char ip6buf[INET6_ADDRSTRLEN];

        if (sin6->sin6_scope_id != 0) {
                log(LOG_NOTICE,
                    "%s: assumption failure (non 0 ID): %s%%%d\n", __func__,
                    IN6_PRINT(ip6buf, &sin6->sin6_addr), sin6->sin6_scope_id);
                /* XXX: proceed anyway... */
        }
        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) {
                        int s = pserialize_read_enter();
                        if (!if_byindex(zoneid)) {
                                pserialize_read_exit(s);
                                return ENXIO;
                        }
                        pserialize_read_exit(s);
                        sin6->sin6_addr.s6_addr16[1] = 0;
                        sin6->sin6_scope_id = zoneid;
                }
        }

        return 0;
}

int
in6_setzoneid(struct in6_addr *in6, uint32_t zoneid)
{
        if (IN6_IS_SCOPE_EMBEDDABLE(in6))
                in6->s6_addr16[1] = htons(zoneid & 0xffff); /* XXX */

        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.
 */
int
in6_setscope(struct in6_addr *in6, const struct ifnet *ifp, uint32_t *ret_id)
{
        int scope;
        uint32_t zoneid = 0;
        const struct scope6_id *sid = SID(ifp);

        if (sid == NULL) {
                log(LOG_NOTICE, "%s: no scope id for %s\n", __func__,
                    if_name(ifp));
                return EINVAL;
        }

        /*
         * special case: the loopback address can only belong to a loopback
         * interface.
         */
        if (IN6_IS_ADDR_LOOPBACK(in6)) {
                if (!(ifp->if_flags & IFF_LOOPBACK)) {
                        char ip6buf[INET6_ADDRSTRLEN];
                        log(LOG_NOTICE, "%s: can't set scope for not loopback "
                            "interface %s and loopback address %s\n",
                            __func__, if_name(ifp), IN6_PRINT(ip6buf, in6));
                        return EINVAL;
                } else {
                        if (ret_id != NULL)
                                *ret_id = 0; /* there's no ambiguity */
                        return 0;
                }
        }

        scope = in6_addrscope(in6);

        switch (scope) {
        case IPV6_ADDR_SCOPE_INTFACELOCAL: /* should be interface index */
                zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_INTFACELOCAL];
                break;

        case IPV6_ADDR_SCOPE_LINKLOCAL:
                zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL];
                break;

        case IPV6_ADDR_SCOPE_SITELOCAL:
                zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_SITELOCAL];
                break;

        case IPV6_ADDR_SCOPE_ORGLOCAL:
                zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_ORGLOCAL];
                break;

        default:
                zoneid = 0;     /* XXX: treat as global. */
                break;
        }

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

        return in6_setzoneid(in6, zoneid);
}

const char *
in6_getscopename(const struct in6_addr *addr)
{
        switch (in6_addrscope(addr)) {
        case IPV6_ADDR_SCOPE_INTFACELOCAL:
                return "interface";
#if IPV6_ADDR_SCOPE_INTFACELOCAL != IPV6_ADDR_SCOPE_NODELOCAL
        case IPV6_ADDR_SCOPE_NODELOCAL:
                return "node";
#endif
        case IPV6_ADDR_SCOPE_LINKLOCAL:
                return "link";
        case IPV6_ADDR_SCOPE_SITELOCAL:
                return "site";
        case IPV6_ADDR_SCOPE_ORGLOCAL:
                return "organization";
        case IPV6_ADDR_SCOPE_GLOBAL:
                return "global";
        default:
                return "unknown";
        }
}

/*
 * 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;
}