/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2015-2019 Yandex LLC
 * Copyright (c) 2015 Alexander V. Chernikov <melifaro@FreeBSD.org>
 * Copyright (c) 2015-2019 Andrey V. Elsukov <ae@FreeBSD.org>
 *
 * 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/ck.h>
#include <sys/epoch.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/sockopt.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_fw.h>
#include <netinet6/ip_fw_nat64.h>

#include <netpfil/ipfw/ip_fw_private.h>

#include "nat64lsn.h"

VNET_DEFINE(uint32_t, nat64lsn_eid) = 0;

static struct nat64lsn_instance *
nat64lsn_find(struct namedobj_instance *ni, const char *name, uint8_t set)
{
        struct named_object *no;

        no = ipfw_objhash_lookup_name_type(ni, set,
            IPFW_TLV_NAT64LSN_NAME, name);
        if (no == NULL)
                return (NULL);
        return (__containerof(no, struct nat64lsn_instance, no));
}

static void
nat64lsn_default_config(ipfw_nat64lsn_cfg *uc)
{

        if (uc->jmaxlen == 0)
                uc->jmaxlen = NAT64LSN_JMAXLEN;
        if (uc->jmaxlen > 65536)
                uc->jmaxlen = 65536;
        if (uc->nh_delete_delay == 0)
                uc->nh_delete_delay = NAT64LSN_HOST_AGE;
        if (uc->pg_delete_delay == 0)
                uc->pg_delete_delay = NAT64LSN_PG_AGE;
        if (uc->st_syn_ttl == 0)
                uc->st_syn_ttl = NAT64LSN_TCP_SYN_AGE;
        if (uc->st_close_ttl == 0)
                uc->st_close_ttl = NAT64LSN_TCP_FIN_AGE;
        if (uc->st_estab_ttl == 0)
                uc->st_estab_ttl = NAT64LSN_TCP_EST_AGE;
        if (uc->st_udp_ttl == 0)
                uc->st_udp_ttl = NAT64LSN_UDP_AGE;
        if (uc->st_icmp_ttl == 0)
                uc->st_icmp_ttl = NAT64LSN_ICMP_AGE;

        if (uc->states_chunks == 0)
                uc->states_chunks = 1;
        else if (uc->states_chunks >= 128)
                uc->states_chunks = 128;
        else if (!powerof2(uc->states_chunks))
                uc->states_chunks = 1 << fls(uc->states_chunks);
}

/*
 * Creates new nat64lsn instance.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_lheader ipfw_nat64lsn_cfg ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_create(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        ipfw_obj_lheader *olh;
        ipfw_nat64lsn_cfg *uc;
        struct nat64lsn_instance *i;
        struct nat64lsn_cfg *cfg;
        struct namedobj_instance *ni;
        uint32_t addr4, mask4;

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

        olh = (ipfw_obj_lheader *)sd->kbuf;
        uc = (ipfw_nat64lsn_cfg *)(olh + 1);

        if (ipfw_check_object_name_generic(uc->name) != 0)
                return (EINVAL);

        if (uc->set >= IPFW_MAX_SETS)
                return (EINVAL);

        if (uc->plen4 > 32)
                return (EINVAL);

        /*
         * Unspecified address has special meaning. But it must
         * have valid prefix length. This length will be used to
         * correctly extract and embedd IPv4 address into IPv6.
         */
        if (nat64_check_prefix6(&uc->prefix6, uc->plen6) != 0 &&
            IN6_IS_ADDR_UNSPECIFIED(&uc->prefix6) &&
            nat64_check_prefixlen(uc->plen6) != 0)
                return (EINVAL);

        /* XXX: Check prefix4 to be global */
        addr4 = ntohl(uc->prefix4.s_addr);
        mask4 = ~((1 << (32 - uc->plen4)) - 1);
        if ((addr4 & mask4) != addr4)
                return (EINVAL);

        nat64lsn_default_config(uc);

        ni = CHAIN_TO_SRV(ch);
        IPFW_UH_RLOCK(ch);
        if (nat64lsn_find(ni, uc->name, uc->set) != NULL) {
                IPFW_UH_RUNLOCK(ch);
                return (EEXIST);
        }
        IPFW_UH_RUNLOCK(ch);

        i = malloc(sizeof(struct nat64lsn_instance), M_NAT64LSN,
            M_WAITOK | M_ZERO);
        strlcpy(i->name, uc->name, sizeof(i->name));
        i->no.name = i->name;
        i->no.etlv = IPFW_TLV_NAT64LSN_NAME;
        i->no.set = uc->set;

        cfg = nat64lsn_init_config(ch, addr4, uc->plen4);
        cfg->base.plat_prefix = uc->prefix6;
        cfg->base.plat_plen = uc->plen6;
        cfg->base.flags = (uc->flags & NAT64LSN_FLAGSMASK) | NAT64_PLATPFX;
        if (IN6_IS_ADDR_WKPFX(&cfg->base.plat_prefix))
                cfg->base.flags |= NAT64_WKPFX;
        else if (IN6_IS_ADDR_UNSPECIFIED(&cfg->base.plat_prefix))
                cfg->base.flags |= NAT64LSN_ANYPREFIX;

        cfg->states_chunks = uc->states_chunks;
        cfg->jmaxlen = uc->jmaxlen;
        cfg->host_delete_delay = uc->nh_delete_delay;
        cfg->pg_delete_delay = uc->pg_delete_delay;
        cfg->st_syn_ttl = uc->st_syn_ttl;
        cfg->st_close_ttl = uc->st_close_ttl;
        cfg->st_estab_ttl = uc->st_estab_ttl;
        cfg->st_udp_ttl = uc->st_udp_ttl;
        cfg->st_icmp_ttl = uc->st_icmp_ttl;
        cfg->nomatch_verdict = IP_FW_DENY;

        IPFW_UH_WLOCK(ch);

        if (nat64lsn_find(ni, uc->name, uc->set) != NULL) {
                IPFW_UH_WUNLOCK(ch);
                nat64lsn_destroy_config(cfg);
                free(i, M_NAT64LSN);
                return (EEXIST);
        }

        if (ipfw_objhash_alloc_idx(ni, &i->no.kidx) != 0) {
                IPFW_UH_WUNLOCK(ch);
                nat64lsn_destroy_config(cfg);
                free(i, M_NAT64LSN);
                return (ENOSPC);
        }
        ipfw_objhash_add(ni, &i->no);

        /* Okay, let's link data */
        i->cfg = cfg;
        SRV_OBJECT(ch, i->no.kidx) = i;
        nat64lsn_start_instance(cfg);

        IPFW_UH_WUNLOCK(ch);
        return (0);
}

static void
nat64lsn_detach_instance(struct ip_fw_chain *ch,
    struct nat64lsn_instance *i)
{

        IPFW_UH_WLOCK_ASSERT(ch);
        SRV_OBJECT(ch, i->no.kidx) = NULL;
        ipfw_objhash_del(CHAIN_TO_SRV(ch), &i->no);
        ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), i->no.kidx);
}

/*
 * Destroys nat64 instance.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_destroy(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        struct nat64lsn_instance *i;
        ipfw_obj_header *oh;

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

        oh = (ipfw_obj_header *)op3;

        IPFW_UH_WLOCK(ch);
        i = nat64lsn_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (i == NULL) {
                IPFW_UH_WUNLOCK(ch);
                return (ENOENT);
        }

        if (i->no.refcnt > 0) {
                IPFW_UH_WUNLOCK(ch);
                return (EBUSY);
        }

        ipfw_reset_eaction_instance(ch, V_nat64lsn_eid, i->no.kidx);
        nat64lsn_detach_instance(ch, i);
        IPFW_UH_WUNLOCK(ch);

        nat64lsn_destroy_config(i->cfg);
        free(i, M_NAT64LSN);
        return (0);
}

#define __COPY_STAT_FIELD(_cfg, _stats, _field) \
        (_stats)->_field = NAT64STAT_FETCH(&(_cfg)->base.stats, _field)
static void
export_stats(struct ip_fw_chain *ch, struct nat64lsn_cfg *cfg,
    struct ipfw_nat64lsn_stats *stats)
{
        struct nat64lsn_alias *alias;
        int i;

        __COPY_STAT_FIELD(cfg, stats, opcnt64);
        __COPY_STAT_FIELD(cfg, stats, opcnt46);
        __COPY_STAT_FIELD(cfg, stats, ofrags);
        __COPY_STAT_FIELD(cfg, stats, ifrags);
        __COPY_STAT_FIELD(cfg, stats, oerrors);
        __COPY_STAT_FIELD(cfg, stats, noroute4);
        __COPY_STAT_FIELD(cfg, stats, noroute6);
        __COPY_STAT_FIELD(cfg, stats, nomatch4);
        __COPY_STAT_FIELD(cfg, stats, noproto);
        __COPY_STAT_FIELD(cfg, stats, nomem);
        __COPY_STAT_FIELD(cfg, stats, dropped);

        __COPY_STAT_FIELD(cfg, stats, jcalls);
        __COPY_STAT_FIELD(cfg, stats, jrequests);
        __COPY_STAT_FIELD(cfg, stats, jhostsreq);
        __COPY_STAT_FIELD(cfg, stats, jportreq);
        __COPY_STAT_FIELD(cfg, stats, jhostfails);
        __COPY_STAT_FIELD(cfg, stats, jportfails);
        __COPY_STAT_FIELD(cfg, stats, jmaxlen);
        __COPY_STAT_FIELD(cfg, stats, jnomem);
        __COPY_STAT_FIELD(cfg, stats, jreinjected);
        __COPY_STAT_FIELD(cfg, stats, screated);
        __COPY_STAT_FIELD(cfg, stats, sdeleted);
        __COPY_STAT_FIELD(cfg, stats, spgcreated);
        __COPY_STAT_FIELD(cfg, stats, spgdeleted);

        stats->hostcount = cfg->hosts_count;
        for (i = 0; i < (1 << (32 - cfg->plen4)); i++) {
                alias = &cfg->aliases[i];
                stats->tcpchunks += alias->tcp_pgcount;
                stats->udpchunks += alias->udp_pgcount;
                stats->icmpchunks += alias->icmp_pgcount;
        }
}
#undef  __COPY_STAT_FIELD

static void
nat64lsn_export_config(struct ip_fw_chain *ch, struct nat64lsn_instance *i,
    ipfw_nat64lsn_cfg *uc)
{
        struct nat64lsn_cfg *cfg;

        strlcpy(uc->name, i->no.name, sizeof(uc->name));
        uc->set = i->no.set;
        cfg = i->cfg;

        uc->flags = cfg->base.flags & NAT64LSN_FLAGSMASK;
        uc->states_chunks = cfg->states_chunks;
        uc->jmaxlen = cfg->jmaxlen;
        uc->nh_delete_delay = cfg->host_delete_delay;
        uc->pg_delete_delay = cfg->pg_delete_delay;
        uc->st_syn_ttl = cfg->st_syn_ttl;
        uc->st_close_ttl = cfg->st_close_ttl;
        uc->st_estab_ttl = cfg->st_estab_ttl;
        uc->st_udp_ttl = cfg->st_udp_ttl;
        uc->st_icmp_ttl = cfg->st_icmp_ttl;
        uc->prefix4.s_addr = htonl(cfg->prefix4);
        uc->prefix6 = cfg->base.plat_prefix;
        uc->plen4 = cfg->plen4;
        uc->plen6 = cfg->base.plat_plen;
}

struct nat64_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 nat64_dump_arg *da;
        ipfw_nat64lsn_cfg *uc;

        da = (struct nat64_dump_arg *)arg;
        uc = (struct _ipfw_nat64lsn_cfg *)ipfw_get_sopt_space(da->sd,
            sizeof(*uc));
        nat64lsn_export_config(da->ch,
            __containerof(no, struct nat64lsn_instance, no), uc);
        return (0);
}

/*
 * Lists all nat64 lsn instances currently available in kernel.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_lheader ]
 * Reply: [ ipfw_obj_lheader ipfw_nat64lsn_cfg x N ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_list(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        ipfw_obj_lheader *olh;
        struct nat64_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_NAT64LSN_NAME);
        olh->objsize = sizeof(ipfw_nat64lsn_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_NAT64LSN_NAME);
        IPFW_UH_RUNLOCK(ch);

        return (0);
}

/*
 * Change existing nat64lsn instance configuration.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ipfw_nat64lsn_cfg ]
 * Reply: [ ipfw_obj_header ipfw_nat64lsn_cfg ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_config(struct ip_fw_chain *ch, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{
        ipfw_obj_header *oh;
        ipfw_nat64lsn_cfg *uc;
        struct nat64lsn_instance *i;
        struct nat64lsn_cfg *cfg;
        struct namedobj_instance *ni;

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

        oh = (ipfw_obj_header *)ipfw_get_sopt_space(sd,
            sizeof(*oh) + sizeof(*uc));
        uc = (ipfw_nat64lsn_cfg *)(oh + 1);

        if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
            oh->ntlv.set >= IPFW_MAX_SETS)
                return (EINVAL);

        ni = CHAIN_TO_SRV(ch);
        if (sd->sopt->sopt_dir == SOPT_GET) {
                IPFW_UH_RLOCK(ch);
                i = nat64lsn_find(ni, oh->ntlv.name, oh->ntlv.set);
                if (i == NULL) {
                        IPFW_UH_RUNLOCK(ch);
                        return (ENOENT);
                }
                nat64lsn_export_config(ch, i, uc);
                IPFW_UH_RUNLOCK(ch);
                return (0);
        }

        nat64lsn_default_config(uc);

        IPFW_UH_WLOCK(ch);
        i = nat64lsn_find(ni, oh->ntlv.name, oh->ntlv.set);
        if (i == NULL) {
                IPFW_UH_WUNLOCK(ch);
                return (ENOENT);
        }

        /*
         * For now allow to change only following values:
         *  jmaxlen, nh_del_age, pg_del_age, tcp_syn_age, tcp_close_age,
         *  tcp_est_age, udp_age, icmp_age, flags, states_chunks.
         */
        cfg = i->cfg;
        cfg->states_chunks = uc->states_chunks;
        cfg->jmaxlen = uc->jmaxlen;
        cfg->host_delete_delay = uc->nh_delete_delay;
        cfg->pg_delete_delay = uc->pg_delete_delay;
        cfg->st_syn_ttl = uc->st_syn_ttl;
        cfg->st_close_ttl = uc->st_close_ttl;
        cfg->st_estab_ttl = uc->st_estab_ttl;
        cfg->st_udp_ttl = uc->st_udp_ttl;
        cfg->st_icmp_ttl = uc->st_icmp_ttl;
        cfg->base.flags &= ~NAT64LSN_FLAGSMASK;
        cfg->base.flags |= uc->flags & NAT64LSN_FLAGSMASK;

        IPFW_UH_WUNLOCK(ch);

        return (0);
}

/*
 * Get nat64lsn statistics.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 * Reply: [ ipfw_obj_header ipfw_counter_tlv ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{
        struct ipfw_nat64lsn_stats stats;
        struct nat64lsn_instance *i;
        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);
        memset(&stats, 0, sizeof(stats));

        IPFW_UH_RLOCK(ch);
        i = nat64lsn_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (i == NULL) {
                IPFW_UH_RUNLOCK(ch);
                return (ENOENT);
        }

        export_stats(ch, i->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 = IPFW_NAT64_VERSION;
        memcpy(ctlv + 1, &stats, sizeof(stats));
        return (0);
}

/*
 * Reset nat64lsn statistics.
 * Data layout (v0)(current):
 * Request: [ ipfw_obj_header ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_reset_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
    struct sockopt_data *sd)
{
        struct nat64lsn_instance *i;
        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);
        i = nat64lsn_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (i == NULL) {
                IPFW_UH_WUNLOCK(ch);
                return (ENOENT);
        }
        COUNTER_ARRAY_ZERO(i->cfg->base.stats.cnt, NAT64STATS);
        IPFW_UH_WUNLOCK(ch);
        return (0);
}

#ifdef __LP64__
#define FREEMASK_COPY(pg, n, out)       (out) = *FREEMASK_CHUNK((pg), (n))
#else
#define FREEMASK_COPY(pg, n, out)       (out) = *FREEMASK_CHUNK((pg), (n)) | \
    ((uint64_t)*(FREEMASK_CHUNK((pg), (n)) + 1) << 32)
#endif
/*
 * Reply: [ ipfw_obj_header ipfw_obj_data [ ipfw_nat64lsn_stg
 *      ipfw_nat64lsn_state x count, ... ] ]
 */
static int
nat64lsn_export_states(struct nat64lsn_cfg *cfg, union nat64lsn_pgidx *idx,
    struct nat64lsn_pg *pg, struct sockopt_data *sd, uint32_t *ret_count)
{
        ipfw_nat64lsn_state_v1 *s;
        struct nat64lsn_state *state;
        uint64_t freemask;
        uint32_t i, count;

        /* validate user input */
        if (idx->chunk > pg->chunks_count - 1)
                return (EINVAL);

        FREEMASK_COPY(pg, idx->chunk, freemask);
        count = 64 - bitcount64(freemask);
        if (count == 0)
                return (0);     /* Try next PG/chunk */

        DPRINTF(DP_STATE, "EXPORT PG 0x%16jx, count %d",
            (uintmax_t)idx->index, count);

        s = (ipfw_nat64lsn_state_v1 *)ipfw_get_sopt_space(sd,
            count * sizeof(ipfw_nat64lsn_state_v1));
        if (s == NULL)
                return (ENOMEM);

        for (i = 0; i < 64; i++) {
                if (ISSET64(freemask, i))
                        continue;
                state = pg->chunks_count == 1 ? &pg->states->state[i] :
                    &pg->states_chunk[idx->chunk]->state[i];

                s->host6 = state->host->addr;
                s->daddr.s_addr = htonl(state->ip_dst);
                s->dport = state->dport;
                s->sport = state->sport;
                s->aport = state->aport;
                s->flags = (uint8_t)(state->flags & 7);
                s->proto = state->proto;
                s->idle = GET_AGE(state->timestamp);
                s++;
        }
        *ret_count = count;
        return (0);
}

#define LAST_IDX        0xFF
static int
nat64lsn_next_pgidx(struct nat64lsn_cfg *cfg, struct nat64lsn_pg *pg,
    union nat64lsn_pgidx *idx)
{

        /* First iterate over chunks */
        if (pg != NULL) {
                if (idx->chunk < pg->chunks_count - 1) {
                        idx->chunk++;
                        return (0);
                }
        }
        idx->chunk = 0;
        /* Then over PGs */
        if (idx->port < UINT16_MAX - 64) {
                idx->port += 64;
                return (0);
        }
        idx->port = NAT64_MIN_PORT;
        /* Then over supported protocols */
        switch (idx->proto) {
        case IPPROTO_ICMP:
                idx->proto = IPPROTO_TCP;
                return (0);
        case IPPROTO_TCP:
                idx->proto = IPPROTO_UDP;
                return (0);
        default:
                idx->proto = IPPROTO_ICMP;
        }
        /* And then over IPv4 alias addresses */
        if (idx->addr < cfg->pmask4) {
                idx->addr++;
                return (1);     /* New states group is needed */
        }
        idx->index = LAST_IDX;
        return (-1);            /* No more states */
}

static struct nat64lsn_pg*
nat64lsn_get_pg_byidx(struct nat64lsn_cfg *cfg, union nat64lsn_pgidx *idx)
{
        struct nat64lsn_alias *alias;
        int pg_idx;

        alias = &cfg->aliases[idx->addr & ((1 << (32 - cfg->plen4)) - 1)];
        MPASS(alias->addr == idx->addr);

        pg_idx = (idx->port - NAT64_MIN_PORT) / 64;
        switch (idx->proto) {
        case IPPROTO_ICMP:
                if (ISSET32(alias->icmp_pgmask[pg_idx / 32], pg_idx % 32))
                        return (alias->icmp[pg_idx / 32]->pgptr[pg_idx % 32]);
                break;
        case IPPROTO_TCP:
                if (ISSET32(alias->tcp_pgmask[pg_idx / 32], pg_idx % 32))
                        return (alias->tcp[pg_idx / 32]->pgptr[pg_idx % 32]);
                break;
        case IPPROTO_UDP:
                if (ISSET32(alias->udp_pgmask[pg_idx / 32], pg_idx % 32))
                        return (alias->udp[pg_idx / 32]->pgptr[pg_idx % 32]);
                break;
        }
        return (NULL);
}

/*
 * Lists nat64lsn states.
 * Data layout (v1)(current):
 * Request: [ ipfw_obj_header ipfw_obj_data [ uint64_t ]]
 * Reply: [ ipfw_obj_header ipfw_obj_data [
 *              ipfw_nat64lsn_stg_v1 ipfw_nat64lsn_state_v1 x N] ]
 *
 * Returns 0 on success
 */
static int
nat64lsn_states(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
    struct sockopt_data *sd)
{
        ipfw_obj_header *oh;
        ipfw_obj_data *od;
        ipfw_nat64lsn_stg_v1 *stg;
        struct nat64lsn_instance *i;
        struct nat64lsn_cfg *cfg;
        struct nat64lsn_pg *pg;
        union nat64lsn_pgidx idx;
        size_t sz;
        uint32_t count, total;
        int ret;

        sz = sizeof(ipfw_obj_header) + sizeof(ipfw_obj_data) +
            sizeof(uint64_t);
        /* Check minimum header size */
        if (sd->valsize < sz)
                return (EINVAL);

        oh = (ipfw_obj_header *)sd->kbuf;
        od = (ipfw_obj_data *)(oh + 1);
        if (od->head.type != IPFW_TLV_OBJDATA ||
            od->head.length != sz - sizeof(ipfw_obj_header))
                return (EINVAL);

        idx.index = *(uint64_t *)(od + 1);
        if (idx.index != 0 && idx.proto != IPPROTO_ICMP &&
            idx.proto != IPPROTO_TCP && idx.proto != IPPROTO_UDP)
                return (EINVAL);
        if (idx.index == LAST_IDX)
                return (EINVAL);

        IPFW_UH_RLOCK(ch);
        i = nat64lsn_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
        if (i == NULL) {
                IPFW_UH_RUNLOCK(ch);
                return (ENOENT);
        }
        cfg = i->cfg;
        if (idx.index == 0) {   /* Fill in starting point */
                idx.addr = cfg->prefix4;
                idx.proto = IPPROTO_ICMP;
                idx.port = NAT64_MIN_PORT;
        }
        if (idx.addr < cfg->prefix4 || idx.addr > cfg->pmask4 ||
            idx.port < NAT64_MIN_PORT) {
                IPFW_UH_RUNLOCK(ch);
                return (EINVAL);
        }
        sz = sizeof(ipfw_obj_header) + sizeof(ipfw_obj_data) +
            sizeof(ipfw_nat64lsn_stg_v1);
        if (sd->valsize < sz) {
                IPFW_UH_RUNLOCK(ch);
                return (ENOMEM);
        }
        oh = (ipfw_obj_header *)ipfw_get_sopt_space(sd, sz);
        od = (ipfw_obj_data *)(oh + 1);
        od->head.type = IPFW_TLV_OBJDATA;
        od->head.length = sz - sizeof(ipfw_obj_header);
        stg = (ipfw_nat64lsn_stg_v1 *)(od + 1);
        stg->count = total = 0;
        stg->next.index = idx.index;
        /*
         * Acquire CALLOUT_LOCK to avoid races with expiration code.
         * Thus states, hosts and PGs will not expire while we hold it.
         */
        CALLOUT_LOCK(cfg);
        ret = 0;
        do {
                pg = nat64lsn_get_pg_byidx(cfg, &idx);
                if (pg != NULL) {
                        count = 0;
                        ret = nat64lsn_export_states(cfg, &idx, pg,
                            sd, &count);
                        if (ret != 0)
                                break;
                        if (count > 0) {
                                stg->count += count;
                                total += count;
                                /* Update total size of reply */
                                od->head.length +=
                                    count * sizeof(ipfw_nat64lsn_state_v1);
                                sz += count * sizeof(ipfw_nat64lsn_state_v1);
                        }
                        stg->alias4.s_addr = htonl(idx.addr);
                }
                /* Determine new index */
                switch (nat64lsn_next_pgidx(cfg, pg, &idx)) {
                case -1:
                        ret = ENOENT; /* End of search */
                        break;
                case 1: /*
                         * Next alias address, new group may be needed.
                         * If states count is zero, use this group.
                         */
                        if (stg->count == 0)
                                continue;
                        /* Otherwise try to create new group */
                        sz += sizeof(ipfw_nat64lsn_stg_v1);
                        if (sd->valsize < sz) {
                                ret = ENOMEM;
                                break;
                        }
                        /* Save next index in current group */
                        stg->next.index = idx.index;
                        stg = (ipfw_nat64lsn_stg_v1 *)ipfw_get_sopt_space(sd,
                            sizeof(ipfw_nat64lsn_stg_v1));
                        od->head.length += sizeof(ipfw_nat64lsn_stg_v1);
                        stg->count = 0;
                        break;
                }
                stg->next.index = idx.index;
        } while (ret == 0);
        CALLOUT_UNLOCK(cfg);
        IPFW_UH_RUNLOCK(ch);
        return ((total > 0 || idx.index == LAST_IDX) ? 0: ret);
}

static struct ipfw_sopt_handler scodes[] = {
    { IP_FW_NAT64LSN_CREATE,    IP_FW3_OPVER,   HDIR_BOTH, nat64lsn_create },
    { IP_FW_NAT64LSN_DESTROY,   IP_FW3_OPVER,   HDIR_SET,  nat64lsn_destroy },
    { IP_FW_NAT64LSN_CONFIG,    IP_FW3_OPVER,   HDIR_BOTH, nat64lsn_config },
    { IP_FW_NAT64LSN_LIST,      IP_FW3_OPVER,   HDIR_GET,  nat64lsn_list },
    { IP_FW_NAT64LSN_STATS,     IP_FW3_OPVER,   HDIR_GET,  nat64lsn_stats },
    { IP_FW_NAT64LSN_RESET_STATS, IP_FW3_OPVER, HDIR_SET,  nat64lsn_reset_stats },
    { IP_FW_NAT64LSN_LIST_STATES, IP_FW3_OPVER, HDIR_GET,  nat64lsn_states },
};

#define NAT64LSN_ARE_EQUAL(v)   (cfg0->v == cfg1->v)
static int
nat64lsn_cmp_configs(struct nat64lsn_cfg *cfg0, struct nat64lsn_cfg *cfg1)
{

        if ((cfg0->base.flags & cfg1->base.flags & NAT64LSN_ALLOW_SWAPCONF) &&
            NAT64LSN_ARE_EQUAL(prefix4) &&
            NAT64LSN_ARE_EQUAL(pmask4) &&
            NAT64LSN_ARE_EQUAL(plen4) &&
            NAT64LSN_ARE_EQUAL(base.plat_plen) &&
            IN6_ARE_ADDR_EQUAL(&cfg0->base.plat_prefix,
                &cfg1->base.plat_prefix))
                return (0);
        return (1);
}
#undef NAT64LSN_ARE_EQUAL

static void
nat64lsn_swap_configs(struct nat64lsn_instance *i0,
    struct nat64lsn_instance *i1)
{
        struct nat64lsn_cfg *cfg;

        cfg = i0->cfg;
        i0->cfg = i1->cfg;
        i1->cfg = cfg;
}

/*
 * NAT64LSN sets swap handler.
 *
 * When two sets have NAT64LSN instance with the same name, we check
 * most important configuration parameters, and if there are no difference,
 * and both instances have NAT64LSN_ALLOW_SWAPCONF flag, we will exchange
 * configs between instances. This allows to keep NAT64 states when ipfw's
 * rules are reloaded using new set.
 *
 * XXX: since manage_sets caller doesn't hold IPFW_WLOCK(), it is possible
 * that some states will be created during switching, because set of rules
 * is changed a bit earley than named objects.
 */
static int
nat64lsn_swap_sets_cb(struct namedobj_instance *ni, struct named_object *no,
    void *arg)
{
        struct nat64lsn_instance *i0, *i1;
        uint8_t *sets;

        sets = arg;
        if (no->set == sets[0]) {
                /*
                 * Check if we have instance in new set with the same
                 * config that is sets aware and ready to swap configs.
                 */
                i0 = __containerof(no, struct nat64lsn_instance, no);
                if ((i0->cfg->base.flags & NAT64LSN_ALLOW_SWAPCONF) &&
                    (i1 = nat64lsn_find(ni, no->name, sets[1])) != NULL) {
                        /* Compare configs */
                        if (nat64lsn_cmp_configs(i0->cfg, i1->cfg) == 0) {
                                IPFW_UH_WLOCK_ASSERT(&V_layer3_chain);
                                IPFW_WLOCK(&V_layer3_chain);
                                nat64lsn_swap_configs(i0, i1);
                                IPFW_WUNLOCK(&V_layer3_chain);
                        }
                }
        }
        return (0);
}

static int
nat64lsn_manage_sets(struct ip_fw_chain *ch, uint32_t set, uint8_t new_set,
    enum ipfw_sets_cmd cmd)
{
        uint8_t sets[2];

        if (cmd == SWAP_ALL) {
                sets[0] = (uint8_t)set;
                sets[1] = new_set;
                ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch),
                    nat64lsn_swap_sets_cb, &sets, IPFW_TLV_NAT64LSN_NAME);
        }
        return (ipfw_obj_manage_sets(CHAIN_TO_SRV(ch), IPFW_TLV_NAT64LSN_NAME,
            set, new_set, cmd));
}
NAT64_DEFINE_OPCODE_REWRITER(nat64lsn, NAT64LSN, opcodes);

static int
destroy_config_cb(struct namedobj_instance *ni, struct named_object *no,
    void *arg)
{
        struct nat64lsn_instance *i;
        struct ip_fw_chain *ch;

        ch = (struct ip_fw_chain *)arg;
        i = (struct nat64lsn_instance *)SRV_OBJECT(ch, no->kidx);
        nat64lsn_detach_instance(ch, i);
        nat64lsn_destroy_config(i->cfg);
        free(i, M_NAT64LSN);
        return (0);
}

int
nat64lsn_init(struct ip_fw_chain *ch, int first)
{

        if (first != 0)
                nat64lsn_init_internal();
        V_nat64lsn_eid = ipfw_add_eaction(ch, ipfw_nat64lsn, "nat64lsn");
        if (V_nat64lsn_eid == 0)
                return (ENXIO);
        IPFW_ADD_SOPT_HANDLER(first, scodes);
        IPFW_ADD_OBJ_REWRITER(first, opcodes);
        return (0);
}

void
nat64lsn_uninit(struct ip_fw_chain *ch, int last)
{

        IPFW_DEL_OBJ_REWRITER(last, opcodes);
        IPFW_DEL_SOPT_HANDLER(last, scodes);
        ipfw_del_eaction(ch, V_nat64lsn_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_NAT64LSN_NAME);
        V_nat64lsn_eid = 0;
        IPFW_UH_WUNLOCK(ch);
        if (last != 0)
                nat64lsn_uninit_internal();
}