/*
 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
 *
 * Based on Svenning Soerensen's IPv4 NETMAP target. Development of IPv6 NAT
 * funded by Astaro.
 */

#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <libiptc/libip6tc.h>
#include <linux/netfilter/nf_nat.h>

#define MODULENAME "NETMAP"

enum {
	O_TO = 0,
};

static const struct xt_option_entry NETMAP_opts[] = {
	{.name = "to", .id = O_TO, .type = XTTYPE_HOSTMASK,
	 .flags = XTOPT_MAND},
	XTOPT_TABLEEND,
};

static void NETMAP_help(void)
{
	printf(MODULENAME" target options:\n"
	       "  --%s address[/mask]\n"
	       "				Network address to map to.\n\n",
	       NETMAP_opts[0].name);
}

static void NETMAP_parse(struct xt_option_call *cb)
{
	struct nf_nat_range *range = cb->data;
	unsigned int i;

	xtables_option_parse(cb);
	range->flags |= NF_NAT_RANGE_MAP_IPS;
	for (i = 0; i < 4; i++) {
		range->min_addr.ip6[i] = cb->val.haddr.ip6[i] &
					 cb->val.hmask.ip6[i];
		range->max_addr.ip6[i] = range->min_addr.ip6[i] |
					 ~cb->val.hmask.ip6[i];
	}
}

static void NETMAP_print(const void *ip, const struct xt_entry_target *target,
                         int numeric)
{
	const struct nf_nat_range *r = (const void *)target->data;
	struct in6_addr a;
	unsigned int i;
	int bits;

	a = r->min_addr.in6;
	printf("%s", xtables_ip6addr_to_numeric(&a));
	for (i = 0; i < 4; i++)
		a.s6_addr32[i] = ~(r->min_addr.ip6[i] ^ r->max_addr.ip6[i]);
	bits = xtables_ip6mask_to_cidr(&a);
	if (bits < 0)
		printf("/%s", xtables_ip6addr_to_numeric(&a));
	else
		printf("/%d", bits);
}

static void NETMAP_save(const void *ip, const struct xt_entry_target *target)
{
	printf(" --%s ", NETMAP_opts[0].name);
	NETMAP_print(ip, target, 0);
}

static struct xtables_target netmap_tg_reg = {
	.name		= MODULENAME,
	.version	= XTABLES_VERSION,
	.family		= NFPROTO_IPV6,
	.size		= XT_ALIGN(sizeof(struct nf_nat_range)),
	.userspacesize	= XT_ALIGN(sizeof(struct nf_nat_range)),
	.help		= NETMAP_help,
	.x6_parse	= NETMAP_parse,
	.print		= NETMAP_print,
	.save		= NETMAP_save,
	.x6_options	= NETMAP_opts,
};

void _init(void)
{
	xtables_register_target(&netmap_tg_reg);
}