/*-
 * Copyright (c) 2016 Yandex LLC
 * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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/counter.h>
#include <sys/eventhandler.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/rmlock.h>
#include <sys/rwlock.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>

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

#include <netinet/in.h>
#include <netinet/ip_var.h>
#include <netinet/ip_fw.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>

#include <netpfil/ipfw/ip_fw_private.h>
#include <netpfil/ipfw/nptv6/nptv6.h>

VNET_DEFINE_STATIC(uint32_t, nptv6_eid) = 0;
#define V_nptv6_eid     VNET(nptv6_eid)
#define IPFW_TLV_NPTV6_NAME     IPFW_TLV_EACTION_NAME(V_nptv6_eid)

static eventhandler_tag nptv6_ifaddr_event;

static struct nptv6_cfg *nptv6_alloc_config(const char *name, uint8_t set);
static void nptv6_free_config(struct nptv6_cfg *cfg);
static struct nptv6_cfg *nptv6_find(struct namedobj_instance *ni,
    const char *name, uint8_t set);
static int nptv6_rewrite_internal(struct nptv6_cfg *cfg, struct mbuf **mp,
    int offset);
static int nptv6_rewrite_external(struct nptv6_cfg *cfg, struct mbuf **mp,
    int offset);

#define NPTV6_LOOKUP(chain, cmd)        \
    (struct nptv6_cfg *)SRV_OBJECT((chain), insntod(cmd, kidx)->kidx)

#ifndef IN6_MASK_ADDR
#define IN6_MASK_ADDR(a, m)     do { \
        (a)->s6_addr32[0] &= (m)->s6_addr32[0]; \
        (a)->s6_addr32[1] &= (m)->s6_addr32[1]; \
        (a)->s6_addr32[2] &= (m)->s6_addr32[2]; \
        (a)->s6_addr32[3] &= (m)->s6_addr32[3]; \
} while (0)
#endif
#ifndef IN6_ARE_MASKED_ADDR_EQUAL
#define IN6_ARE_MASKED_ADDR_EQUAL(d, a, m)      (       \
        (((d)->s6_addr32[0] ^ (a)->s6_addr32[0]) & (m)->s6_addr32[0]) == 0 && \
        (((d)->s6_addr32[1] ^ (a)->s6_addr32[1]) & (m)->s6_addr32[1]) == 0 && \
        (((d)->s6_addr32[2] ^ (a)->s6_addr32[2]) & (m)->s6_addr32[2]) == 0 && \
        (((d)->s6_addr32[3] ^ (a)->s6_addr32[3]) & (m)->s6_addr32[3]) == 0 )
#endif

#if 0
#define NPTV6_DEBUG(fmt, ...)   do {                    \
        printf("%s: " fmt "\n", __func__, ## __VA_ARGS__);      \
} while (0)
#define NPTV6_IPDEBUG(fmt, ...) do {                    \
        char _s[INET6_ADDRSTRLEN], _d[INET6_ADDRSTRLEN];        \
        printf("%s: " fmt "\n", __func__, ## __VA_ARGS__);      \
} while (0)
#else
#define NPTV6_DEBUG(fmt, ...)
#define NPTV6_IPDEBUG(fmt, ...)
#endif

static int
nptv6_getlasthdr(struct nptv6_cfg *cfg, struct mbuf *m, int *offset)
{
        struct ip6_hdr *ip6;
        struct ip6_hbh *hbh;
        int proto, hlen;

        hlen = (offset == NULL) ? 0: *offset;
        if (m->m_len < hlen)
                return (-1);
        ip6 = mtodo(m, hlen);
        hlen += sizeof(*ip6);
        proto = ip6->ip6_nxt;
        while (proto == IPPROTO_HOPOPTS || proto == IPPROTO_ROUTING ||
            proto == IPPROTO_DSTOPTS) {
                hbh = mtodo(m, hlen);
                if (m->m_len < hlen)
                        return (-1);
                proto = hbh->ip6h_nxt;
                hlen += (hbh->ip6h_len + 1) << 3;
        }
        if (offset != NULL)
                *offset = hlen;
        return (proto);
}

static int
nptv6_translate_icmpv6(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
{
        struct icmp6_hdr *icmp6;
        struct ip6_hdr *ip6;
        struct mbuf *m;

        m = *mp;
        if (offset > m->m_len)
                return (-1);
        icmp6 = mtodo(m, offset);
        NPTV6_DEBUG("ICMPv6 type %d", icmp6->icmp6_type);
        switch (icmp6->icmp6_type) {
        case ICMP6_DST_UNREACH:
        case ICMP6_PACKET_TOO_BIG:
        case ICMP6_TIME_EXCEEDED:
        case ICMP6_PARAM_PROB:
                break;
        case ICMP6_ECHO_REQUEST:
        case ICMP6_ECHO_REPLY:
                /* nothing to translate */
                return (0);
        default:
                /*
                 * XXX: We can add some checks to not translate NDP and MLD
                 * messages. Currently user must explicitly allow these message
                 * types, otherwise packets will be dropped.
                 */
                return (-1);
        }
        offset += sizeof(*icmp6);
        if (offset + sizeof(*ip6) > m->m_pkthdr.len)
                return (-1);
        if (offset + sizeof(*ip6) > m->m_len)
                *mp = m = m_pullup(m, offset + sizeof(*ip6));
        if (m == NULL)
                return (-1);
        ip6 = mtodo(m, offset);
        NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
            inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
            inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
            ip6->ip6_nxt);
        if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_src,
            &cfg->external, &cfg->mask))
                return (nptv6_rewrite_external(cfg, mp, offset));
        else if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
            &cfg->internal, &cfg->mask))
                return (nptv6_rewrite_internal(cfg, mp, offset));
        /*
         * Addresses in the inner IPv6 header doesn't matched to
         * our prefixes.
         */
        return (-1);
}

static int
nptv6_search_index(struct nptv6_cfg *cfg, struct in6_addr *a)
{
        int idx;

        if (cfg->flags & NPTV6_48PLEN)
                return (3);

        /* Search suitable word index for adjustment */
        for (idx = 4; idx < 8; idx++)
                if (a->s6_addr16[idx] != 0xffff)
                        break;
        /*
         * RFC 6296 p3.7: If an NPTv6 Translator discovers a datagram with
         * an IID of all-zeros while performing address mapping, that
         * datagram MUST be dropped, and an ICMPv6 Parameter Problem error
         * SHOULD be generated.
         */
        if (idx == 8 ||
            (a->s6_addr32[2] == 0 && a->s6_addr32[3] == 0))
                return (-1);
        return (idx);
}

static void
nptv6_copy_addr(struct in6_addr *src, struct in6_addr *dst,
    struct in6_addr *mask)
{
        int i;

        for (i = 0; i < 8 && mask->s6_addr8[i] != 0; i++) {
                dst->s6_addr8[i] &=  ~mask->s6_addr8[i];
                dst->s6_addr8[i] |= src->s6_addr8[i] & mask->s6_addr8[i];
        }
}

static int
nptv6_rewrite_internal(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
{
        struct in6_addr *addr;
        struct ip6_hdr *ip6;
        int idx, proto;
        uint16_t adj;

        ip6 = mtodo(*mp, offset);
        NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
            inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
            inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
            ip6->ip6_nxt);
        if (offset == 0)
                addr = &ip6->ip6_src;
        else {
                /*
                 * When we rewriting inner IPv6 header, we need to rewrite
                 * destination address back to external prefix. The datagram in
                 * the ICMPv6 payload should looks like it was send from
                 * external prefix.
                 */
                addr = &ip6->ip6_dst;
        }
        idx = nptv6_search_index(cfg, addr);
        if (idx < 0) {
                /*
                 * Do not send ICMPv6 error when offset isn't zero.
                 * This means we are rewriting inner IPv6 header in the
                 * ICMPv6 error message.
                 */
                if (offset == 0) {
                        icmp6_error2(*mp, ICMP6_DST_UNREACH,
                            ICMP6_DST_UNREACH_ADDR, 0, (*mp)->m_pkthdr.rcvif);
                        *mp = NULL;
                }
                return (IP_FW_DENY);
        }
        adj = addr->s6_addr16[idx];
        nptv6_copy_addr(&cfg->external, addr, &cfg->mask);
        adj = cksum_add(adj, cfg->adjustment);
        if (adj == 0xffff)
                adj = 0;
        addr->s6_addr16[idx] = adj;
        if (offset == 0) {
                /*
                 * We may need to translate addresses in the inner IPv6
                 * header for ICMPv6 error messages.
                 */
                proto = nptv6_getlasthdr(cfg, *mp, &offset);
                if (proto < 0 || (proto == IPPROTO_ICMPV6 &&
                    nptv6_translate_icmpv6(cfg, mp, offset) != 0))
                        return (IP_FW_DENY);
                NPTV6STAT_INC(cfg, in2ex);
        }
        return (0);
}

static int
nptv6_rewrite_external(struct nptv6_cfg *cfg, struct mbuf **mp, int offset)
{
        struct in6_addr *addr;
        struct ip6_hdr *ip6;
        int idx, proto;
        uint16_t adj;

        ip6 = mtodo(*mp, offset);
        NPTV6_IPDEBUG("offset %d, %s -> %s %d", offset,
            inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
            inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
            ip6->ip6_nxt);
        if (offset == 0)
                addr = &ip6->ip6_dst;
        else {
                /*
                 * When we rewriting inner IPv6 header, we need to rewrite
                 * source address back to internal prefix. The datagram in
                 * the ICMPv6 payload should looks like it was send from
                 * internal prefix.
                 */
                addr = &ip6->ip6_src;
        }
        idx = nptv6_search_index(cfg, addr);
        if (idx < 0) {
                /*
                 * Do not send ICMPv6 error when offset isn't zero.
                 * This means we are rewriting inner IPv6 header in the
                 * ICMPv6 error message.
                 */
                if (offset == 0) {
                        icmp6_error2(*mp, ICMP6_DST_UNREACH,
                            ICMP6_DST_UNREACH_ADDR, 0, (*mp)->m_pkthdr.rcvif);
                        *mp = NULL;
                }
                return (IP_FW_DENY);
        }
        adj = addr->s6_addr16[idx];
        nptv6_copy_addr(&cfg->internal, addr, &cfg->mask);
        adj = cksum_add(adj, ~cfg->adjustment);
        if (adj == 0xffff)
                adj = 0;
        addr->s6_addr16[idx] = adj;
        if (offset == 0) {
                /*
                 * We may need to translate addresses in the inner IPv6
                 * header for ICMPv6 error messages.
                 */
                proto = nptv6_getlasthdr(cfg, *mp, &offset);
                if (proto < 0 || (proto == IPPROTO_ICMPV6 &&
                    nptv6_translate_icmpv6(cfg, mp, offset) != 0))
                        return (IP_FW_DENY);
                NPTV6STAT_INC(cfg, ex2in);
        }
        return (0);
}

/*
 * ipfw external action handler.
 */
static int
ipfw_nptv6(struct ip_fw_chain *chain, struct ip_fw_args *args,
    ipfw_insn *cmd, int *done)
{
        struct ip6_hdr *ip6;
        struct nptv6_cfg *cfg;
        ipfw_insn *icmd;
        int ret;

        *done = 0; /* try next rule if not matched */
        ret = IP_FW_DENY;
        icmd = cmd + F_LEN(cmd);
        if (cmd->opcode != O_EXTERNAL_ACTION ||
            insntod(cmd, kidx)->kidx != V_nptv6_eid ||
            icmd->opcode != O_EXTERNAL_INSTANCE ||
            (cfg = NPTV6_LOOKUP(chain, icmd)) == NULL ||
            (cfg->flags & NPTV6_READY) == 0)
                return (ret);
        /*
         * We need act as router, so when forwarding is disabled -
         * do nothing.
         */
        if (V_ip6_forwarding == 0 || args->f_id.addr_type != 6)
                return (ret);
        /*
         * NOTE: we expect ipfw_chk() did m_pullup() up to upper level
         * protocol's headers. Also we skip some checks, that ip6_input(),
         * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did.
         */
        ip6 = mtod(args->m, struct ip6_hdr *);
        NPTV6_IPDEBUG("eid %u, oid %u, %s -> %s %d",
            insntod(cmd, kidx)->kidx, insntod(icmd, kidx)->kidx,
            inet_ntop(AF_INET6, &ip6->ip6_src, _s, sizeof(_s)),
            inet_ntop(AF_INET6, &ip6->ip6_dst, _d, sizeof(_d)),
            ip6->ip6_nxt);
        if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_src,
            &cfg->internal, &cfg->mask)) {
                /*
                 * XXX: Do not translate packets when both src and dst
                 * are from internal prefix.
                 */
                if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
                    &cfg->internal, &cfg->mask))
                        return (ret);
                ret = nptv6_rewrite_internal(cfg, &args->m, 0);
        } else if (IN6_ARE_MASKED_ADDR_EQUAL(&ip6->ip6_dst,
            &cfg->external, &cfg->mask))
                ret = nptv6_rewrite_external(cfg, &args->m, 0);
        else
                return (ret);
        /*
         * If address wasn't rewrited - free mbuf and terminate the search.
         */
        if (ret != 0) {
                if (args->m != NULL) {
                        m_freem(args->m);
                        args->m = NULL; /* mark mbuf as consumed */
                }
                NPTV6STAT_INC(cfg, dropped);
                *done = 1;
        } else {
                /* Terminate the search if one_pass is set */
                *done = V_fw_one_pass;
                /* Update args->f_id when one_pass is off */
                if (*done == 0) {
                        ip6 = mtod(args->m, struct ip6_hdr *);
                        args->f_id.src_ip6 = ip6->ip6_src;
                        args->f_id.dst_ip6 = ip6->ip6_dst;
                }
        }
        return (ret);
}

static struct nptv6_cfg *
nptv6_alloc_config(const char *name, uint8_t set)
{
        struct nptv6_cfg *cfg;

        cfg = malloc(sizeof(struct nptv6_cfg), M_IPFW, M_WAITOK | M_ZERO);
        COUNTER_ARRAY_ALLOC(cfg->stats, NPTV6STATS, M_WAITOK);
        cfg->no.name = cfg->name;
        cfg->no.etlv = IPFW_TLV_NPTV6_NAME;
        cfg->no.set = set;
        strlcpy(cfg->name, name, sizeof(cfg->name));
        return (cfg);
}

static void
nptv6_free_config(struct nptv6_cfg *cfg)
{

        COUNTER_ARRAY_FREE(cfg->stats, NPTV6STATS);
        free(cfg, M_IPFW);
}

static void
nptv6_export_config(struct ip_fw_chain *ch, struct nptv6_cfg *cfg,
    ipfw_nptv6_cfg *uc)
{

        uc->internal = cfg->internal;
        if (cfg->flags & NPTV6_DYNAMIC_PREFIX)
                memcpy(uc->if_name, cfg->if_name, IF_NAMESIZE);
        else
                uc->external = cfg->external;
        uc->plen = cfg->plen;
        uc->flags = cfg->flags & NPTV6_FLAGSMASK;
        uc->set = cfg->no.set;
        strlcpy(uc->name, cfg->no.name, sizeof(uc->name));
}

struct nptv6_dump_arg {
        struct ip_fw_chain *ch;
        struct sockopt_data *sd;
};

static int
export_config_cb(struct namedobj_instance *ni, struct named_object *no,
    void *arg)
{
        struct nptv6_dump_arg *da = (struct nptv6_dump_arg *)arg;
        ipfw_nptv6_cfg *uc;

        uc = (ipfw_nptv6_cfg *)ipfw_get_sopt_space(da->sd, sizeof(*uc));
        nptv6_export_config(da->ch, (struct nptv6_cfg *)no, uc);
        return (0);
}

static struct nptv6_cfg *
nptv6_find(struct namedobj_instance *ni, const char *name, uint8_t set)
{
        struct nptv6_cfg *cfg;

        cfg = (struct nptv6_cfg *)ipfw_objhash_lookup_name_type(ni, set,
            IPFW_TLV_NPTV6_NAME, name);

        return (cfg);
}

static void
nptv6_calculate_adjustment(struct nptv6_cfg *cfg)
{
        uint16_t i, e;
        uint16_t *p;

        /* Calculate checksum of internal prefix */
        for (i = 0, p = (uint16_t *)&cfg->internal;
            p < (uint16_t *)(&cfg->internal + 1); p++)
                i = cksum_add(i, *p);

        /* Calculate checksum of external prefix */
        for (e = 0, p = (uint16_t *)&cfg->external;
            p < (uint16_t *)(&cfg->external + 1); p++)
                e = cksum_add(e, *p);

        /* Adjustment value for Int->Ext direction */
        cfg->adjustment = cksum_add(~e, i);
}

static int
nptv6_check_prefix(const struct in6_addr *addr)
{

        if (IN6_IS_ADDR_MULTICAST(addr) ||
            IN6_IS_ADDR_LINKLOCAL(addr) ||
            IN6_IS_ADDR_LOOPBACK(addr) ||
            IN6_IS_ADDR_UNSPECIFIED(addr))
                return (EINVAL);
        return (0);
}

static void
nptv6_set_external(struct nptv6_cfg *cfg, struct in6_addr *addr)
{

        cfg->external = *addr;
        IN6_MASK_ADDR(&cfg->external, &cfg->mask);
        nptv6_calculate_adjustment(cfg);
        cfg->flags |= NPTV6_READY;
}

/*
 * Try to determine what prefix to use as external for
 * configured interface name.
 */
static void
nptv6_find_prefix(struct ip_fw_chain *ch, struct nptv6_cfg *cfg,
    struct ifnet *ifp)
{
        struct epoch_tracker et;
        struct ifaddr *ifa;
        struct in6_ifaddr *ia;

        MPASS(cfg->flags & NPTV6_DYNAMIC_PREFIX);
        IPFW_UH_WLOCK_ASSERT(ch);

        if (ifp == NULL) {
                ifp = ifunit_ref(cfg->if_name);
                if (ifp == NULL)
                        return;
        }
        NET_EPOCH_ENTER(et);
        CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                if (ifa->ifa_addr->sa_family != AF_INET6)
                        continue;
                ia = (struct in6_ifaddr *)ifa;
                if (nptv6_check_prefix(&ia->ia_addr.sin6_addr) ||
                    IN6_ARE_MASKED_ADDR_EQUAL(&ia->ia_addr.sin6_addr,
                    &cfg->internal, &cfg->mask))
                        continue;
                /* Suitable address is found. */
                nptv6_set_external(cfg, &ia->ia_addr.sin6_addr);
                break;
        }
        NET_EPOCH_EXIT(et);
        if_rele(ifp);
}

struct ifaddr_event_args {
        struct ifnet *ifp;
        const struct in6_addr *addr;
        int event;
};

static int
ifaddr_cb(struct namedobj_instance *ni, struct named_object *no,
    void *arg)
{
        struct ifaddr_event_args *args;
        struct ip_fw_chain *ch;
        struct nptv6_cfg *cfg;

        ch = &V_layer3_chain;
        cfg = (struct nptv6_cfg *)SRV_OBJECT(ch, no->kidx);
        if ((cfg->flags & NPTV6_DYNAMIC_PREFIX) == 0)
                return (0);

        args = arg;
        /* If interface name doesn't match, ignore */
        if (strncmp(args->ifp->if_xname, cfg->if_name, IF_NAMESIZE))
                return (0);
        if (args->ifp->if_flags & IFF_DYING) { /* XXX: is it possible? */
                cfg->flags &= ~NPTV6_READY;
                return (0);
        }
        if (args->event == IFADDR_EVENT_DEL) {
                /* If instance is not ready, ignore */
                if ((cfg->flags & NPTV6_READY) == 0)
                        return (0);
                /* If address does not match the external prefix, ignore */
                if (!IN6_ARE_MASKED_ADDR_EQUAL(&cfg->external, args->addr,
                    &cfg->mask))
                        return (0);
                /* Otherwise clear READY flag */
                cfg->flags &= ~NPTV6_READY;
        } else {/* IFADDR_EVENT_ADD */
                /* If instance is already ready, ignore */
                if (cfg->flags & NPTV6_READY)
                        return (0);
                /* If address is not suitable for prefix, ignore */
                if (nptv6_check_prefix(args->addr) ||
                    IN6_ARE_MASKED_ADDR_EQUAL(args->addr, &cfg->internal,
                    &cfg->mask))
                        return (0);
                /* FALLTHROUGH */
        }
        MPASS(!(cfg->flags & NPTV6_READY));
        /* Try to determine the prefix */
        if_ref(args->ifp);
        nptv6_find_prefix(ch, cfg, args->ifp);
        return (0);
}

static void
nptv6_ifaddrevent_handler(void *arg __unused, struct ifnet *ifp,
    struct ifaddr *ifa, int event)
{
        struct ifaddr_event_args args;
        struct ip_fw_chain *ch;

        if (ifa->ifa_addr->sa_family != AF_INET6)
                return;

        args.ifp = ifp;
        args.addr = &((struct sockaddr_in6 *)ifa->ifa_addr)->sin6_addr;
        args.event = event;

        ch = &V_layer3_chain;
        IPFW_UH_WLOCK(ch);
        ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), ifaddr_cb, &args,
            IPFW_TLV_NPTV6_NAME);
        IPFW_UH_WUNLOCK(ch);
}

/*
 * Creates new NPTv6 instance.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_lheader ipfw_nptv6_cfg ]
 *
 * Returns 0 on success
 */
static int
nptv6_create(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        struct in6_addr mask;
        ipfw_obj_lheader *olh;
        ipfw_nptv6_cfg *uc;
        struct namedobj_instance *ni;
        struct nptv6_cfg *cfg;

        if (sd->valsize != sizeof(*olh) + sizeof(*uc))
                return (EINVAL);

        olh = (ipfw_obj_lheader *)sd->kbuf;
        uc = (ipfw_nptv6_cfg *)(olh + 1);
        if (ipfw_check_object_name_generic(uc->name) != 0)
                return (EINVAL);
        if (uc->plen < 8 || uc->plen > 64 || uc->set >= IPFW_MAX_SETS)
                return (EINVAL);
        if (nptv6_check_prefix(&uc->internal))
                return (EINVAL);
        in6_prefixlen2mask(&mask, uc->plen);
        if ((uc->flags & NPTV6_DYNAMIC_PREFIX) == 0 && (
            nptv6_check_prefix(&uc->external) ||
            IN6_ARE_MASKED_ADDR_EQUAL(&uc->external, &uc->internal, &mask)))
                return (EINVAL);

        ni = CHAIN_TO_SRV(ch);
        IPFW_UH_RLOCK(ch);
        if (nptv6_find(ni, uc->name, uc->set) != NULL) {
                IPFW_UH_RUNLOCK(ch);
                return (EEXIST);
        }
        IPFW_UH_RUNLOCK(ch);

        cfg = nptv6_alloc_config(uc->name, uc->set);
        cfg->plen = uc->plen;
        cfg->flags = uc->flags & NPTV6_FLAGSMASK;
        if (cfg->plen <= 48)
                cfg->flags |= NPTV6_48PLEN;
        cfg->mask = mask;
        cfg->internal = uc->internal;
        IN6_MASK_ADDR(&cfg->internal, &mask);
        if (cfg->flags & NPTV6_DYNAMIC_PREFIX)
                memcpy(cfg->if_name, uc->if_name, IF_NAMESIZE);
        else
                nptv6_set_external(cfg, &uc->external);

        if ((uc->flags & NPTV6_DYNAMIC_PREFIX) != 0 &&
            nptv6_ifaddr_event == NULL)
                nptv6_ifaddr_event = EVENTHANDLER_REGISTER(
                    ifaddr_event_ext, nptv6_ifaddrevent_handler, NULL,
                    EVENTHANDLER_PRI_ANY);

        IPFW_UH_WLOCK(ch);
        if (ipfw_objhash_alloc_idx(ni, &cfg->no.kidx) != 0) {
                IPFW_UH_WUNLOCK(ch);
                nptv6_free_config(cfg);
                return (ENOSPC);
        }
        ipfw_objhash_add(ni, &cfg->no);
        SRV_OBJECT(ch, cfg->no.kidx) = cfg;
        if (cfg->flags & NPTV6_DYNAMIC_PREFIX)
                nptv6_find_prefix(ch, cfg, NULL);
        IPFW_UH_WUNLOCK(ch);

        return (0);
}

/*
 * Destroys NPTv6 instance.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 *
 * Returns 0 on success
 */
static int
nptv6_destroy(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        ipfw_obj_header *oh;
        struct nptv6_cfg *cfg;

        if (sd->valsize != sizeof(*oh))
                return (EINVAL);

        oh = (ipfw_obj_header *)sd->kbuf;
        if (ipfw_check_object_name_generic(oh->ntlv.name) != 0)
                return (EINVAL);

        IPFW_UH_WLOCK(ch);
        cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (cfg == NULL) {
                IPFW_UH_WUNLOCK(ch);
                return (ESRCH);
        }
        if (cfg->no.refcnt > 0) {
                IPFW_UH_WUNLOCK(ch);
                return (EBUSY);
        }

        ipfw_reset_eaction_instance(ch, V_nptv6_eid, cfg->no.kidx);
        SRV_OBJECT(ch, cfg->no.kidx) = NULL;
        ipfw_objhash_del(CHAIN_TO_SRV(ch), &cfg->no);
        ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), cfg->no.kidx);
        IPFW_UH_WUNLOCK(ch);

        nptv6_free_config(cfg);
        return (0);
}

/*
 * Get or change nptv6 instance config.
 * Request: [ ipfw_obj_header [ ipfw_nptv6_cfg ] ]
 */
static int
nptv6_config(struct ip_fw_chain *chain, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{

        return (EOPNOTSUPP);
}

/*
 * Lists all NPTv6 instances currently available in kernel.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_lheader ]
 * Reply: [ ipfw_obj_lheader ipfw_nptv6_cfg x N ]
 *
 * Returns 0 on success
 */
static int
nptv6_list(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        ipfw_obj_lheader *olh;
        struct nptv6_dump_arg da;

        /* Check minimum header size */
        if (sd->valsize < sizeof(ipfw_obj_lheader))
                return (EINVAL);

        olh = (ipfw_obj_lheader *)ipfw_get_sopt_header(sd, sizeof(*olh));

        IPFW_UH_RLOCK(ch);
        olh->count = ipfw_objhash_count_type(CHAIN_TO_SRV(ch),
            IPFW_TLV_NPTV6_NAME);
        olh->objsize = sizeof(ipfw_nptv6_cfg);
        olh->size = sizeof(*olh) + olh->count * olh->objsize;

        if (sd->valsize < olh->size) {
                IPFW_UH_RUNLOCK(ch);
                return (ENOMEM);
        }
        memset(&da, 0, sizeof(da));
        da.ch = ch;
        da.sd = sd;
        ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), export_config_cb,
            &da, IPFW_TLV_NPTV6_NAME);
        IPFW_UH_RUNLOCK(ch);

        return (0);
}

#define __COPY_STAT_FIELD(_cfg, _stats, _field) \
        (_stats)->_field = NPTV6STAT_FETCH(_cfg, _field)
static void
export_stats(struct ip_fw_chain *ch, struct nptv6_cfg *cfg,
    struct ipfw_nptv6_stats *stats)
{

        __COPY_STAT_FIELD(cfg, stats, in2ex);
        __COPY_STAT_FIELD(cfg, stats, ex2in);
        __COPY_STAT_FIELD(cfg, stats, dropped);
}

/*
 * Get NPTv6 statistics.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ]]
 *
 * Returns 0 on success
 */
static int
nptv6_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{
        struct ipfw_nptv6_stats stats;
        struct nptv6_cfg *cfg;
        ipfw_obj_header *oh;
        ipfw_obj_ctlv *ctlv;
        size_t sz;

        sz = sizeof(ipfw_obj_header) + sizeof(ipfw_obj_ctlv) + sizeof(stats);
        if (sd->valsize % sizeof(uint64_t))
                return (EINVAL);
        if (sd->valsize < sz)
                return (ENOMEM);
        oh = (ipfw_obj_header *)ipfw_get_sopt_header(sd, sz);
        if (oh == NULL)
                return (EINVAL);
        if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
            oh->ntlv.set >= IPFW_MAX_SETS)
                return (EINVAL);
        memset(&stats, 0, sizeof(stats));

        IPFW_UH_RLOCK(ch);
        cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (cfg == NULL) {
                IPFW_UH_RUNLOCK(ch);
                return (ESRCH);
        }
        export_stats(ch, cfg, &stats);
        IPFW_UH_RUNLOCK(ch);

        ctlv = (ipfw_obj_ctlv *)(oh + 1);
        memset(ctlv, 0, sizeof(*ctlv));
        ctlv->head.type = IPFW_TLV_COUNTERS;
        ctlv->head.length = sz - sizeof(ipfw_obj_header);
        ctlv->count = sizeof(stats) / sizeof(uint64_t);
        ctlv->objsize = sizeof(uint64_t);
        ctlv->version = 1;
        memcpy(ctlv + 1, &stats, sizeof(stats));
        return (0);
}

/*
 * Reset NPTv6 statistics.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 *
 * Returns 0 on success
 */
static int
nptv6_reset_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{
        struct nptv6_cfg *cfg;
        ipfw_obj_header *oh;

        if (sd->valsize != sizeof(*oh))
                return (EINVAL);
        oh = (ipfw_obj_header *)sd->kbuf;
        if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
            oh->ntlv.set >= IPFW_MAX_SETS)
                return (EINVAL);

        IPFW_UH_WLOCK(ch);
        cfg = nptv6_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (cfg == NULL) {
                IPFW_UH_WUNLOCK(ch);
                return (ESRCH);
        }
        COUNTER_ARRAY_ZERO(cfg->stats, NPTV6STATS);
        IPFW_UH_WUNLOCK(ch);
        return (0);
}

static struct ipfw_sopt_handler scodes[] = {
    { IP_FW_NPTV6_CREATE,       IP_FW3_OPVER, HDIR_SET, nptv6_create },
    { IP_FW_NPTV6_DESTROY,      IP_FW3_OPVER, HDIR_SET, nptv6_destroy },
    { IP_FW_NPTV6_CONFIG,       IP_FW3_OPVER, HDIR_BOTH,nptv6_config },
    { IP_FW_NPTV6_LIST,         IP_FW3_OPVER, HDIR_GET, nptv6_list },
    { IP_FW_NPTV6_STATS,        IP_FW3_OPVER, HDIR_GET, nptv6_stats },
    { IP_FW_NPTV6_RESET_STATS,  IP_FW3_OPVER, HDIR_SET, nptv6_reset_stats },
};

static int
nptv6_classify(ipfw_insn *cmd0, uint32_t *puidx, uint8_t *ptype)
{
        ipfw_insn *icmd;

        icmd = cmd0 - F_LEN(cmd0);
        NPTV6_DEBUG("opcode %u, kidx %u, opcode0 %u, kidx %u",
            cmd->opcode, insntod(cmd, kidx)->kidx,
            icmd->opcode, insntod(icmd, kidx)->kidx);
        if (icmd->opcode != O_EXTERNAL_ACTION ||
            insntod(icmd, kidx)->kidx != V_nptv6_eid)
                return (1);

        *puidx = insntod(cmd0, kidx)->kidx;
        *ptype = 0;
        return (0);
}

static void
nptv6_update_kidx(ipfw_insn *cmd0, uint32_t idx)
{

        insntod(cmd0, kidx)->kidx = idx;
        NPTV6_DEBUG("opcode %u, kidx -> %u", cmd->opcode, idx);
}

static int
nptv6_findbyname(struct ip_fw_chain *ch, struct tid_info *ti,
    struct named_object **pno)
{
        int err;

        err = ipfw_objhash_find_type(CHAIN_TO_SRV(ch), ti,
            IPFW_TLV_NPTV6_NAME, pno);
        NPTV6_DEBUG("uidx %u, type %u, err %d", ti->uidx, ti->type, err);
        return (err);
}

static struct named_object *
nptv6_findbykidx(struct ip_fw_chain *ch, uint32_t idx)
{
        struct namedobj_instance *ni;
        struct named_object *no;

        IPFW_UH_WLOCK_ASSERT(ch);
        ni = CHAIN_TO_SRV(ch);
        no = ipfw_objhash_lookup_kidx(ni, idx);
        KASSERT(no != NULL, ("NPT with index %u not found", idx));

        NPTV6_DEBUG("kidx %u -> %s", idx, no->name);
        return (no);
}

static int
nptv6_manage_sets(struct ip_fw_chain *ch, uint32_t set, uint8_t new_set,
    enum ipfw_sets_cmd cmd)
{

        return (ipfw_obj_manage_sets(CHAIN_TO_SRV(ch), IPFW_TLV_NPTV6_NAME,
            set, new_set, cmd));
}

static struct opcode_obj_rewrite opcodes[] = {
        {
                .opcode = O_EXTERNAL_INSTANCE,
                .etlv = IPFW_TLV_EACTION /* just show it isn't table */,
                .classifier = nptv6_classify,
                .update = nptv6_update_kidx,
                .find_byname = nptv6_findbyname,
                .find_bykidx = nptv6_findbykidx,
                .manage_sets = nptv6_manage_sets,
        },
};

static int
destroy_config_cb(struct namedobj_instance *ni, struct named_object *no,
    void *arg)
{
        struct nptv6_cfg *cfg;
        struct ip_fw_chain *ch;

        ch = (struct ip_fw_chain *)arg;
        IPFW_UH_WLOCK_ASSERT(ch);

        cfg = (struct nptv6_cfg *)SRV_OBJECT(ch, no->kidx);
        SRV_OBJECT(ch, no->kidx) = NULL;
        ipfw_objhash_del(ni, &cfg->no);
        ipfw_objhash_free_idx(ni, cfg->no.kidx);
        nptv6_free_config(cfg);
        return (0);
}

int
nptv6_init(struct ip_fw_chain *ch, int first)
{

        V_nptv6_eid = ipfw_add_eaction(ch, ipfw_nptv6, "nptv6");
        if (V_nptv6_eid == 0)
                return (ENXIO);
        IPFW_ADD_SOPT_HANDLER(first, scodes);
        IPFW_ADD_OBJ_REWRITER(first, opcodes);
        return (0);
}

void
nptv6_uninit(struct ip_fw_chain *ch, int last)
{

        if (last && nptv6_ifaddr_event != NULL)
                EVENTHANDLER_DEREGISTER(ifaddr_event_ext, nptv6_ifaddr_event);
        IPFW_DEL_OBJ_REWRITER(last, opcodes);
        IPFW_DEL_SOPT_HANDLER(last, scodes);
        ipfw_del_eaction(ch, V_nptv6_eid);
        /*
         * Since we already have deregistered external action,
         * our named objects become unaccessible via rules, because
         * all rules were truncated by ipfw_del_eaction().
         * So, we can unlink and destroy our named objects without holding
         * IPFW_WLOCK().
         */
        IPFW_UH_WLOCK(ch);
        ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), destroy_config_cb, ch,
            IPFW_TLV_NPTV6_NAME);
        V_nptv6_eid = 0;
        IPFW_UH_WUNLOCK(ch);
}