/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2019 Yandex LLC
 * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
 * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com>
 *
 * 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/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/socket.h>

#include "ipfw2.h"

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <netdb.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_nat64.h>
#include <arpa/inet.h>

typedef int (nat64clat_cb_t)(ipfw_nat64clat_cfg *i, const char *name,
    uint8_t set);
static int nat64clat_foreach(nat64clat_cb_t *f, const char *name, uint8_t set,
    int sort);

static void nat64clat_create(const char *name, uint8_t set, int ac, char **av);
static void nat64clat_config(const char *name, uint8_t set, int ac, char **av);
static void nat64clat_destroy(const char *name, uint8_t set);
static void nat64clat_stats(const char *name, uint8_t set);
static void nat64clat_reset_stats(const char *name, uint8_t set);
static int nat64clat_show_cb(ipfw_nat64clat_cfg *cfg, const char *name,
    uint8_t set);
static int nat64clat_destroy_cb(ipfw_nat64clat_cfg *cfg, const char *name,
    uint8_t set);

static struct _s_x nat64cmds[] = {
      { "create",	TOK_CREATE },
      { "config",	TOK_CONFIG },
      { "destroy",	TOK_DESTROY },
      { "list",		TOK_LIST },
      { "show",		TOK_LIST },
      { "stats",	TOK_STATS },
      { NULL, 0 }
};

static struct _s_x nat64statscmds[] = {
      { "reset",	TOK_RESET },
      { NULL, 0 }
};

/*
 * This one handles all nat64clat-related commands
 *	ipfw [set N] nat64clat NAME {create | config} ...
 *	ipfw [set N] nat64clat NAME stats [reset]
 *	ipfw [set N] nat64clat {NAME | all} destroy
 *	ipfw [set N] nat64clat {NAME | all} {list | show}
 */
#define	nat64clat_check_name	table_check_name
void
ipfw_nat64clat_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("nat64clat needs instance name");
	name = *av;
	if (nat64clat_check_name(name) != 0) {
		if (strcmp(name, "all") == 0)
			name = NULL;
		else
			errx(EX_USAGE, "nat64clat instance name %s is invalid",
			    name);
	}
	ac--; av++;
	NEED1("nat64clat needs command");

	tcmd = get_token(nat64cmds, *av, "nat64clat command");
	if (name == NULL && tcmd != TOK_DESTROY && tcmd != TOK_LIST)
		errx(EX_USAGE, "nat64clat instance name required");
	switch (tcmd) {
	case TOK_CREATE:
		ac--; av++;
		nat64clat_create(name, set, ac, av);
		break;
	case TOK_CONFIG:
		ac--; av++;
		nat64clat_config(name, set, ac, av);
		break;
	case TOK_LIST:
		nat64clat_foreach(nat64clat_show_cb, name, set, 1);
		break;
	case TOK_DESTROY:
		if (name == NULL)
			nat64clat_foreach(nat64clat_destroy_cb, NULL, set, 0);
		else
			nat64clat_destroy(name, set);
		break;
	case TOK_STATS:
		ac--; av++;
		if (ac == 0) {
			nat64clat_stats(name, set);
			break;
		}
		tcmd = get_token(nat64statscmds, *av, "stats command");
		if (tcmd == TOK_RESET)
			nat64clat_reset_stats(name, set);
	}
}


static void
nat64clat_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 nat64newcmds[] = {
      { "plat_prefix",	TOK_PLAT_PREFIX },
      { "clat_prefix",	TOK_CLAT_PREFIX },
      { "log",		TOK_LOG },
      { "-log",		TOK_LOGOFF },
      { "allow_private", TOK_PRIVATE },
      { "-allow_private", TOK_PRIVATEOFF },
      { NULL, 0 }
};

/*
 * Creates new nat64clat instance
 * ipfw nat64clat <NAME> create clat_prefix <prefix> plat_prefix <prefix>
 * Request: [ ipfw_obj_lheader ipfw_nat64clat_cfg ]
 */
#define	NAT64CLAT_HAS_CLAT_PREFIX	0x01
#define	NAT64CLAT_HAS_PLAT_PREFIX	0x02
static void
nat64clat_create(const char *name, uint8_t set, int ac, char *av[])
{
	char buf[sizeof(ipfw_obj_lheader) + sizeof(ipfw_nat64clat_cfg)];
	ipfw_nat64clat_cfg *cfg;
	ipfw_obj_lheader *olh;
	int tcmd, flags;
	char *p;
	struct in6_addr prefix;
	uint8_t plen;

	memset(buf, 0, sizeof(buf));
	olh = (ipfw_obj_lheader *)buf;
	cfg = (ipfw_nat64clat_cfg *)(olh + 1);

	/* Some reasonable defaults */
	inet_pton(AF_INET6, "64:ff9b::", &cfg->plat_prefix);
	cfg->plat_plen = 96;
	cfg->set = set;
	flags = NAT64CLAT_HAS_PLAT_PREFIX;
	while (ac > 0) {
		tcmd = get_token(nat64newcmds, *av, "option");
		ac--; av++;

		switch (tcmd) {
		case TOK_PLAT_PREFIX:
		case TOK_CLAT_PREFIX:
			if (tcmd == TOK_PLAT_PREFIX) {
				NEED1("IPv6 plat_prefix required");
			} else {
				NEED1("IPv6 clat_prefix required");
			}

			if ((p = strchr(*av, '/')) != NULL)
				*p++ = '\0';
			if (inet_pton(AF_INET6, *av, &prefix) != 1)
				errx(EX_USAGE,
				    "Bad prefix: %s", *av);
			plen = strtol(p, NULL, 10);
			if (ipfw_check_nat64prefix(&prefix, plen) != 0)
				errx(EX_USAGE,
				    "Bad prefix length: %s", p);
			if (tcmd == TOK_PLAT_PREFIX) {
				flags |= NAT64CLAT_HAS_PLAT_PREFIX;
				cfg->plat_prefix = prefix;
				cfg->plat_plen = plen;
			} else {
				flags |= NAT64CLAT_HAS_CLAT_PREFIX;
				cfg->clat_prefix = prefix;
				cfg->clat_plen = plen;
			}
			ac--; av++;
			break;
		case TOK_LOG:
			cfg->flags |= NAT64_LOG;
			break;
		case TOK_LOGOFF:
			cfg->flags &= ~NAT64_LOG;
			break;
		case TOK_PRIVATE:
			cfg->flags |= NAT64_ALLOW_PRIVATE;
			break;
		case TOK_PRIVATEOFF:
			cfg->flags &= ~NAT64_ALLOW_PRIVATE;
			break;
		}
	}

	/* Check validness */
	if ((flags & NAT64CLAT_HAS_PLAT_PREFIX) != NAT64CLAT_HAS_PLAT_PREFIX)
		errx(EX_USAGE, "plat_prefix required");
	if ((flags & NAT64CLAT_HAS_CLAT_PREFIX) != NAT64CLAT_HAS_CLAT_PREFIX)
		errx(EX_USAGE, "clat_prefix required");

	olh->count = 1;
	olh->objsize = sizeof(*cfg);
	olh->size = sizeof(buf);
	strlcpy(cfg->name, name, sizeof(cfg->name));
	if (do_set3(IP_FW_NAT64CLAT_CREATE, &olh->opheader, sizeof(buf)) != 0)
		err(EX_OSERR, "nat64clat instance creation failed");
}

/*
 * Configures existing nat64clat instance
 * ipfw nat64clat <NAME> config <options>
 * Request: [ ipfw_obj_header ipfw_nat64clat_cfg ]
 */
static void
nat64clat_config(const char *name, uint8_t set, int ac, char **av)
{
	char buf[sizeof(ipfw_obj_header) + sizeof(ipfw_nat64clat_cfg)];
	ipfw_nat64clat_cfg *cfg;
	ipfw_obj_header *oh;
	char *opt;
	char *p;
	size_t sz;
	int tcmd;
	struct in6_addr prefix;
	uint8_t plen;

	if (ac == 0)
		errx(EX_USAGE, "config options required");
	memset(&buf, 0, sizeof(buf));
	oh = (ipfw_obj_header *)buf;
	cfg = (ipfw_nat64clat_cfg *)(oh + 1);
	sz = sizeof(buf);

	nat64clat_fill_ntlv(&oh->ntlv, name, set);
	if (do_get3(IP_FW_NAT64CLAT_CONFIG, &oh->opheader, &sz) != 0)
		err(EX_OSERR, "failed to get config for instance %s", name);

	while (ac > 0) {
		tcmd = get_token(nat64newcmds, *av, "option");
		opt = *av;
		ac--; av++;

		switch (tcmd) {
		case TOK_PLAT_PREFIX:
		case TOK_CLAT_PREFIX:
			if (tcmd == TOK_PLAT_PREFIX) {
				NEED1("IPv6 plat_prefix required");
			} else {
				NEED1("IPv6 clat_prefix required");
			}

			if ((p = strchr(*av, '/')) != NULL)
				*p++ = '\0';
			else
				errx(EX_USAGE,
				    "Prefix length required: %s", *av);
			if (inet_pton(AF_INET6, *av, &prefix) != 1)
				errx(EX_USAGE,
				    "Bad prefix: %s", *av);
			plen = strtol(p, NULL, 10);
			if (ipfw_check_nat64prefix(&prefix, plen) != 0)
				errx(EX_USAGE,
				    "Bad prefix length: %s", p);
			if (tcmd == TOK_PLAT_PREFIX) {
				cfg->plat_prefix = prefix;
				cfg->plat_plen = plen;
			} else {
				cfg->clat_prefix = prefix;
				cfg->clat_plen = plen;
			}
			ac--; av++;
			break;
		case TOK_LOG:
			cfg->flags |= NAT64_LOG;
			break;
		case TOK_LOGOFF:
			cfg->flags &= ~NAT64_LOG;
			break;
		case TOK_PRIVATE:
			cfg->flags |= NAT64_ALLOW_PRIVATE;
			break;
		case TOK_PRIVATEOFF:
			cfg->flags &= ~NAT64_ALLOW_PRIVATE;
			break;
		default:
			errx(EX_USAGE, "Can't change %s option", opt);
		}
	}

	if (do_set3(IP_FW_NAT64CLAT_CONFIG, &oh->opheader, sizeof(buf)) != 0)
		err(EX_OSERR, "nat64clat instance configuration failed");
}

/*
 * Destroys nat64clat instance.
 * Request: [ ipfw_obj_header ]
 */
static void
nat64clat_destroy(const char *name, uint8_t set)
{
	ipfw_obj_header oh;

	memset(&oh, 0, sizeof(oh));
	nat64clat_fill_ntlv(&oh.ntlv, name, set);
	if (do_set3(IP_FW_NAT64CLAT_DESTROY, &oh.opheader, sizeof(oh)) != 0)
		err(EX_OSERR, "failed to destroy nat instance %s", name);
}

/*
 * Get nat64clat instance statistics.
 * Request: [ ipfw_obj_header ]
 * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ] ]
 */
static int
nat64clat_get_stats(const char *name, uint8_t set,
    struct ipfw_nat64clat_stats *stats)
{
	ipfw_obj_header *oh;
	ipfw_obj_ctlv *oc;
	size_t sz;

	sz = sizeof(*oh) + sizeof(*oc) + sizeof(*stats);
	oh = calloc(1, sz);
	nat64clat_fill_ntlv(&oh->ntlv, name, set);
	if (do_get3(IP_FW_NAT64CLAT_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
nat64clat_stats(const char *name, uint8_t set)
{
	struct ipfw_nat64clat_stats stats;

	if (nat64clat_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("nat64clat %s\n", name);

	printf("\t%ju packets translated from IPv6 to IPv4\n",
	    (uintmax_t)stats.opcnt64);
	printf("\t%ju packets translated from IPv4 to IPv6\n",
	    (uintmax_t)stats.opcnt46);
	printf("\t%ju IPv6 fragments created\n",
	    (uintmax_t)stats.ofrags);
	printf("\t%ju IPv4 fragments received\n",
	    (uintmax_t)stats.ifrags);
	printf("\t%ju output packets dropped due to no bufs, etc.\n",
	    (uintmax_t)stats.oerrors);
	printf("\t%ju output packets discarded due to no IPv4 route\n",
	    (uintmax_t)stats.noroute4);
	printf("\t%ju output packets discarded due to no IPv6 route\n",
	    (uintmax_t)stats.noroute6);
	printf("\t%ju packets discarded due to unsupported protocol\n",
	    (uintmax_t)stats.noproto);
	printf("\t%ju packets discarded due to memory allocation problems\n",
	    (uintmax_t)stats.nomem);
	printf("\t%ju packets discarded due to some errors\n",
	    (uintmax_t)stats.dropped);
}

/*
 * Reset nat64clat instance statistics specified by @oh->ntlv.
 * Request: [ ipfw_obj_header ]
 */
static void
nat64clat_reset_stats(const char *name, uint8_t set)
{
	ipfw_obj_header oh;

	memset(&oh, 0, sizeof(oh));
	nat64clat_fill_ntlv(&oh.ntlv, name, set);
	if (do_set3(IP_FW_NAT64CLAT_RESET_STATS, &oh.opheader, sizeof(oh)) != 0)
		err(EX_OSERR, "failed to reset stats for instance %s", name);
}

static int
nat64clat_show_cb(ipfw_nat64clat_cfg *cfg, const char *name, uint8_t set)
{
	char plat_buf[INET6_ADDRSTRLEN], clat_buf[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->clat_prefix, clat_buf, sizeof(clat_buf));
	inet_ntop(AF_INET6, &cfg->plat_prefix, plat_buf, sizeof(plat_buf));
	printf("nat64clat %s clat_prefix %s/%u plat_prefix %s/%u",
	    cfg->name, clat_buf, cfg->clat_plen, plat_buf, cfg->plat_plen);
	if (cfg->flags & NAT64_LOG)
		printf(" log");
	if (cfg->flags & NAT64_ALLOW_PRIVATE)
		printf(" allow_private");
	printf("\n");
	return (0);
}

static int
nat64clat_destroy_cb(ipfw_nat64clat_cfg *cfg, const char *name __unused,
    uint8_t set)
{

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

	nat64clat_destroy(cfg->name, cfg->set);
	return (0);
}


/*
 * Compare nat64clat instances names.
 * Honor number comparison.
 */
static int
nat64name_cmp(const void *a, const void *b)
{
	const ipfw_nat64clat_cfg *ca, *cb;

	ca = (const ipfw_nat64clat_cfg *)a;
	cb = (const ipfw_nat64clat_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 nat64clat instance list from kernel,
 * optionally sorts it and calls requested function for each instance.
 *
 * Request: [ ipfw_obj_lheader ]
 * Reply: [ ipfw_obj_lheader ipfw_nat64clat_cfg x N ]
 */
static int
nat64clat_foreach(nat64clat_cb_t *f, const char *name, uint8_t set, int sort)
{
	ipfw_obj_lheader *olh;
	ipfw_nat64clat_cfg *cfg;
	size_t sz;
	uint32_t i;
	int error;

	/* 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_NAT64CLAT_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,
			    nat64name_cmp);

		cfg = (ipfw_nat64clat_cfg *)(olh + 1);
		for (i = 0; i < olh->count; i++) {
			error = f(cfg, name, set); /* Ignore errors for now */
			cfg = (ipfw_nat64clat_cfg *)((caddr_t)cfg +
			    olh->objsize);
		}
		free(olh);
		break;
	}
	return (0);
}