/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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/socket.h>

#include "ipfw2.h"

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>

#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip_fw.h>
#include <netinet6/ip_fw_nptv6.h>
#include <arpa/inet.h>


typedef int (nptv6_cb_t)(ipfw_nptv6_cfg *i, const char *name, uint8_t set);
static int nptv6_foreach(nptv6_cb_t *f, const char *name, uint8_t set,
    int sort);

static void nptv6_create(const char *name, uint8_t set, int ac, char **av);
static void nptv6_destroy(const char *name, uint8_t set);
static void nptv6_stats(const char *name, uint8_t set);
static void nptv6_reset_stats(const char *name, uint8_t set);
static int nptv6_show_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set);
static int nptv6_destroy_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set);

static struct _s_x nptv6cmds[] = {
      { "create",       TOK_CREATE },
      { "destroy",      TOK_DESTROY },
      { "list",         TOK_LIST },
      { "show",         TOK_LIST },
      { "stats",        TOK_STATS },
      { NULL, 0 }
};

static struct _s_x nptv6statscmds[] = {
      { "reset",        TOK_RESET },
      { NULL, 0 }
};

/*
 * This one handles all NPTv6-related commands
 *      ipfw [set N] nptv6 NAME {create | config} ...
 *      ipfw [set N] nptv6 NAME stats [reset]
 *      ipfw [set N] nptv6 {NAME | all} destroy
 *      ipfw [set N] nptv6 {NAME | all} {list | show}
 */
#define nptv6_check_name        table_check_name
void
ipfw_nptv6_handler(int ac, char *av[])
{
        const char *name;
        int tcmd;
        uint8_t set;

        if (g_co.use_set != 0)
                set = g_co.use_set - 1;
        else
                set = 0;
        ac--; av++;

        NEED1("nptv6 needs instance name");
        name = *av;
        if (nptv6_check_name(name) != 0) {
                if (strcmp(name, "all") == 0) {
                        name = NULL;
                } else
                        errx(EX_USAGE, "nptv6 instance name %s is invalid",
                            name);
        }
        ac--; av++;
        NEED1("nptv6 needs command");

        tcmd = get_token(nptv6cmds, *av, "nptv6 command");
        if (name == NULL && tcmd != TOK_DESTROY && tcmd != TOK_LIST)
                errx(EX_USAGE, "nptv6 instance name required");
        switch (tcmd) {
        case TOK_CREATE:
                ac--; av++;
                nptv6_create(name, set, ac, av);
                break;
        case TOK_LIST:
                nptv6_foreach(nptv6_show_cb, name, set, 1);
                break;
        case TOK_DESTROY:
                if (name == NULL)
                        nptv6_foreach(nptv6_destroy_cb, NULL, set, 0);
                else
                        nptv6_destroy(name, set);
                break;
        case TOK_STATS:
                ac--; av++;
                if (ac == 0) {
                        nptv6_stats(name, set);
                        break;
                }
                tcmd = get_token(nptv6statscmds, *av, "stats command");
                if (tcmd == TOK_RESET)
                        nptv6_reset_stats(name, set);
        }
}


static void
nptv6_fill_ntlv(ipfw_obj_ntlv *ntlv, const char *name, uint8_t set)
{

        ntlv->head.type = IPFW_TLV_EACTION_NAME(1); /* it doesn't matter */
        ntlv->head.length = sizeof(ipfw_obj_ntlv);
        ntlv->idx = 1;
        ntlv->set = set;
        strlcpy(ntlv->name, name, sizeof(ntlv->name));
}

static struct _s_x nptv6newcmds[] = {
      { "int_prefix",   TOK_INTPREFIX },
      { "ext_prefix",   TOK_EXTPREFIX },
      { "prefixlen",    TOK_PREFIXLEN },
      { "ext_if",       TOK_EXTIF },
      { NULL, 0 }
};

static void
nptv6_parse_prefix(const char *arg, struct in6_addr *prefix, int *len)
{
        long plen;
        char *p, *l;

        p = strdup(arg);
        if (p == NULL)
                err(EX_OSERR, NULL);
        if ((l = strchr(p, '/')) != NULL)
                *l++ = '\0';
        if (inet_pton(AF_INET6, p, prefix) != 1)
                errx(EX_USAGE, "Bad prefix: %s", p);
        if (l != NULL) {
                plen = strtol(l, &l, 10);
                if (*l != '\0' || plen < 8 || plen > 64)
                        errx(EX_USAGE, "Bad prefix length: %s", arg);
                *len = plen;
        } else
                *len = 0;
        free(p);
}

/*
 * Creates new nptv6 instance
 * ipfw nptv6 <NAME> create int_prefix <prefix> ext_prefix <prefix>
 * Request: [ ipfw_obj_lheader ipfw_nptv6_cfg ]
 */
#define NPTV6_HAS_INTPREFIX     0x01
#define NPTV6_HAS_EXTPREFIX     0x02
#define NPTV6_HAS_PREFIXLEN     0x04
static void
nptv6_create(const char *name, uint8_t set, int ac, char *av[])
{
        char buf[sizeof(ipfw_obj_lheader) + sizeof(ipfw_nptv6_cfg)];
        struct in6_addr mask;
        ipfw_nptv6_cfg *cfg;
        ipfw_obj_lheader *olh;
        int tcmd, flags, iplen, eplen, pplen;
        char *p;

        iplen = eplen = pplen = 0;
        memset(buf, 0, sizeof(buf));
        olh = (ipfw_obj_lheader *)buf;
        cfg = (ipfw_nptv6_cfg *)(olh + 1);
        cfg->set = set;
        flags = 0;
        while (ac > 0) {
                tcmd = get_token(nptv6newcmds, *av, "option");
                ac--; av++;

                switch (tcmd) {
                case TOK_INTPREFIX:
                        NEED1("IPv6 prefix required");
                        nptv6_parse_prefix(*av, &cfg->internal, &iplen);
                        flags |= NPTV6_HAS_INTPREFIX;
                        ac--; av++;
                        break;
                case TOK_EXTPREFIX:
                        if (flags & NPTV6_HAS_EXTPREFIX)
                                errx(EX_USAGE,
                                    "Only one ext_prefix or ext_if allowed");
                        NEED1("IPv6 prefix required");
                        nptv6_parse_prefix(*av, &cfg->external, &eplen);
                        flags |= NPTV6_HAS_EXTPREFIX;
                        ac--; av++;
                        break;
                case TOK_EXTIF:
                        if (flags & NPTV6_HAS_EXTPREFIX)
                                errx(EX_USAGE,
                                    "Only one ext_prefix or ext_if allowed");
                        NEED1("Interface name required");
                        if (strlen(*av) >= sizeof(cfg->if_name))
                                errx(EX_USAGE, "Invalid interface name");
                        flags |= NPTV6_HAS_EXTPREFIX;
                        cfg->flags |= NPTV6_DYNAMIC_PREFIX;
                        strncpy(cfg->if_name, *av, sizeof(cfg->if_name));
                        ac--; av++;
                        break;
                case TOK_PREFIXLEN:
                        NEED1("IPv6 prefix length required");
                        pplen = strtol(*av, &p, 10);
                        if (*p != '\0' || pplen < 8 || pplen > 64)
                                errx(EX_USAGE, "wrong prefix length: %s", *av);
                        ac--; av++;
                        break;
                }
        }

        /* RFC 6296 Sec. 3.1 */
        if (pplen != 0) {
                if ((eplen != 0 && eplen != pplen) ||
                    (iplen != 0 && iplen != pplen))
                        errx(EX_USAGE, "prefix length mismatch");
                cfg->plen = pplen;
                flags |= NPTV6_HAS_PREFIXLEN;
        } else if (eplen != 0 || iplen != 0) {
                if (eplen != 0 && iplen != 0 && eplen != iplen)
                        errx(EX_USAGE, "prefix length mismatch");
                warnx("use prefixlen instead");
                cfg->plen = eplen ? eplen : iplen;
                flags |= NPTV6_HAS_PREFIXLEN;
        }

        /* Check validness */
        if ((flags & NPTV6_HAS_INTPREFIX) != NPTV6_HAS_INTPREFIX)
                errx(EX_USAGE, "int_prefix required");
        if ((flags & NPTV6_HAS_EXTPREFIX) != NPTV6_HAS_EXTPREFIX)
                errx(EX_USAGE, "ext_prefix or ext_if required");
        if ((flags & NPTV6_HAS_PREFIXLEN) != NPTV6_HAS_PREFIXLEN)
                errx(EX_USAGE, "prefixlen required");

        n2mask(&mask, cfg->plen);
        APPLY_MASK(&cfg->internal, &mask);
        if ((cfg->flags & NPTV6_DYNAMIC_PREFIX) == 0)
                APPLY_MASK(&cfg->external, &mask);

        olh->count = 1;
        olh->objsize = sizeof(*cfg);
        olh->size = sizeof(buf);
        strlcpy(cfg->name, name, sizeof(cfg->name));
        if (do_set3(IP_FW_NPTV6_CREATE, &olh->opheader, sizeof(buf)) != 0)
                err(EX_OSERR, "nptv6 instance creation failed");
}

/*
 * Destroys NPTv6 instance.
 * Request: [ ipfw_obj_header ]
 */
static void
nptv6_destroy(const char *name, uint8_t set)
{
        ipfw_obj_header oh;

        memset(&oh, 0, sizeof(oh));
        nptv6_fill_ntlv(&oh.ntlv, name, set);
        if (do_set3(IP_FW_NPTV6_DESTROY, &oh.opheader, sizeof(oh)) != 0)
                err(EX_OSERR, "failed to destroy nat instance %s", name);
}

/*
 * Get NPTv6 instance statistics.
 * Request: [ ipfw_obj_header ]
 * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ] ]
 */
static int
nptv6_get_stats(const char *name, uint8_t set, struct ipfw_nptv6_stats *stats)
{
        ipfw_obj_header *oh;
        ipfw_obj_ctlv *oc;
        size_t sz;

        sz = sizeof(*oh) + sizeof(*oc) + sizeof(*stats);
        oh = calloc(1, sz);
        nptv6_fill_ntlv(&oh->ntlv, name, set);
        if (do_get3(IP_FW_NPTV6_STATS, &oh->opheader, &sz) == 0) {
                oc = (ipfw_obj_ctlv *)(oh + 1);
                memcpy(stats, oc + 1, sizeof(*stats));
                free(oh);
                return (0);
        }
        free(oh);
        return (-1);
}

static void
nptv6_stats(const char *name, uint8_t set)
{
        struct ipfw_nptv6_stats stats;

        if (nptv6_get_stats(name, set, &stats) != 0)
                err(EX_OSERR, "Error retrieving stats");

        if (g_co.use_set != 0 || set != 0)
                printf("set %u ", set);
        printf("nptv6 %s\n", name);
        printf("\t%ju packets translated (internal to external)\n",
            (uintmax_t)stats.in2ex);
        printf("\t%ju packets translated (external to internal)\n",
            (uintmax_t)stats.ex2in);
        printf("\t%ju packets dropped due to some error\n",
            (uintmax_t)stats.dropped);
}

/*
 * Reset NPTv6 instance statistics specified by @oh->ntlv.
 * Request: [ ipfw_obj_header ]
 */
static void
nptv6_reset_stats(const char *name, uint8_t set)
{
        ipfw_obj_header oh;

        memset(&oh, 0, sizeof(oh));
        nptv6_fill_ntlv(&oh.ntlv, name, set);
        if (do_set3(IP_FW_NPTV6_RESET_STATS, &oh.opheader, sizeof(oh)) != 0)
                err(EX_OSERR, "failed to reset stats for instance %s", name);
}

static int
nptv6_show_cb(ipfw_nptv6_cfg *cfg, const char *name, uint8_t set)
{
        char abuf[INET6_ADDRSTRLEN];

        if (name != NULL && strcmp(cfg->name, name) != 0)
                return (ESRCH);

        if (g_co.use_set != 0 && cfg->set != set)
                return (ESRCH);

        if (g_co.use_set != 0 || cfg->set != 0)
                printf("set %u ", cfg->set);
        inet_ntop(AF_INET6, &cfg->internal, abuf, sizeof(abuf));
        printf("nptv6 %s int_prefix %s ", cfg->name, abuf);
        if (cfg->flags & NPTV6_DYNAMIC_PREFIX)
                printf("ext_if %s ", cfg->if_name);
        else {
                inet_ntop(AF_INET6, &cfg->external, abuf, sizeof(abuf));
                printf("ext_prefix %s ", abuf);
        }
        printf("prefixlen %u\n", cfg->plen);
        return (0);
}

static int
nptv6_destroy_cb(ipfw_nptv6_cfg *cfg, const char *name __unused, uint8_t set)
{

        if (g_co.use_set != 0 && cfg->set != set)
                return (ESRCH);

        nptv6_destroy(cfg->name, cfg->set);
        return (0);
}


/*
 * Compare NPTv6 instances names.
 * Honor number comparison.
 */
static int
nptv6name_cmp(const void *a, const void *b)
{
        const ipfw_nptv6_cfg *ca, *cb;

        ca = (const ipfw_nptv6_cfg *)a;
        cb = (const ipfw_nptv6_cfg *)b;

        if (ca->set > cb->set)
                return (1);
        else if (ca->set < cb->set)
                return (-1);
        return (stringnum_cmp(ca->name, cb->name));
}

/*
 * Retrieves NPTv6 instance list from kernel,
 * Request: [ ipfw_obj_lheader ]
 * Reply: [ ipfw_obj_lheader ipfw_nptv6_cfg x N ]
 */
static int
nptv6_foreach(nptv6_cb_t *f, const char *name, uint8_t set, int sort)
{
        ipfw_obj_lheader *olh;
        ipfw_nptv6_cfg *cfg;
        size_t sz;
        uint32_t i;

        /* Start with reasonable default */
        sz = sizeof(*olh) + 16 * sizeof(*cfg);
        for (;;) {
                if ((olh = calloc(1, sz)) == NULL)
                        return (ENOMEM);

                olh->size = sz;
                if (do_get3(IP_FW_NPTV6_LIST, &olh->opheader, &sz) != 0) {
                        sz = olh->size;
                        free(olh);
                        if (errno != ENOMEM)
                                return (errno);
                        continue;
                }

                if (sort != 0)
                        qsort(olh + 1, olh->count, olh->objsize, nptv6name_cmp);

                cfg = (ipfw_nptv6_cfg *)(olh + 1);
                for (i = 0; i < olh->count; i++) {
                        (void)f(cfg, name, set);
                        cfg = (ipfw_nptv6_cfg *)((caddr_t)cfg + olh->objsize);
                }
                free(olh);
                break;
        }
        return (0);
}