/*

 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>

 *

 * Based on Rusty Russell's IPv4 DNAT target. Development of IPv6 NAT

 * funded by Astaro.

 */

#include <stdio.h>

#include <netdb.h>

#include <string.h>

#include <stdlib.h>

#include <xtables.h>

#include <iptables.h>

#include <limits.h> /* INT_MAX in ip_tables.h */

#include <linux/netfilter_ipv6/ip6_tables.h>

#include <linux/netfilter/nf_nat.h>

enum {

	O_TO_DEST = 0,

	O_RANDOM,

	O_PERSISTENT,

	O_X_TO_DEST,

	F_TO_DEST   = 1 << O_TO_DEST,

	F_RANDOM   = 1 << O_RANDOM,

	F_X_TO_DEST = 1 << O_X_TO_DEST,

};

static void DNAT_help(void)

{

	printf(

"DNAT target options:\n"

" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port]]\n"

"				Address to map destination to.\n"

"[--random] [--persistent]\n");

}

static void DNAT_help_v2(void)

{

	printf(

"DNAT target options:\n"

" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port[/port]]]\n"

"				Address to map destination to.\n"

"[--random] [--persistent]\n");

}

static const struct xt_option_entry DNAT_opts[] = {

	{.name = "to-destination", .id = O_TO_DEST, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND | XTOPT_MULTI},

	{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},

	{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},

	XTOPT_TABLEEND,

};

/* Ranges expected in network order. */

static void

parse_to(const char *orig_arg, int portok, struct nf_nat_range2 *range, int rev)

{

	char *arg, *start, *end = NULL, *colon = NULL, *dash, *error;

	const struct in6_addr *ip;

	arg = strdup(orig_arg);

	if (arg == NULL)

		xtables_error(RESOURCE_PROBLEM, "strdup");

	start = strchr(arg, '[');

	if (start == NULL) {

		start = arg;

		/* Lets assume one colon is port information. Otherwise its an IPv6 address */

		colon = strchr(arg, ':');

		if (colon && strchr(colon+1, ':'))

			colon = NULL;

	}

	else {

		start++;

		end = strchr(start, ']');

		if (end == NULL)

			xtables_error(PARAMETER_PROBLEM,

				      "Invalid address format");

		*end = '\0';

		colon = strchr(end + 1, ':');

	}

	if (colon) {

		int port;

		if (!portok)

			xtables_error(PARAMETER_PROBLEM,

				   "Need TCP, UDP, SCTP or DCCP with port specification");

		range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;

		port = atoi(colon+1);

		if (port <= 0 || port > 65535)

			xtables_error(PARAMETER_PROBLEM,

				   "Port `%s' not valid\n", colon+1);

		error = strchr(colon+1, ':');

		if (error)

			xtables_error(PARAMETER_PROBLEM,

				   "Invalid port:port syntax - use dash\n");

		dash = strchr(colon, '-');

		if (!dash) {

			range->min_proto.tcp.port

				= range->max_proto.tcp.port

				= htons(port);

		} else {

			int maxport;

			maxport = atoi(dash + 1);

			if (maxport <= 0 || maxport > 65535)

				xtables_error(PARAMETER_PROBLEM,

					   "Port `%s' not valid\n", dash+1);

			if (maxport < port)

				/* People are stupid. */

				xtables_error(PARAMETER_PROBLEM,

					   "Port range `%s' funky\n", colon+1);

			range->min_proto.tcp.port = htons(port);

			range->max_proto.tcp.port = htons(maxport);

			if (rev >= 2) {

				char *slash = strchr(dash, '/');

				if (slash) {

					int baseport;

					baseport = atoi(slash + 1);

					if (baseport <= 0 || baseport > 65535)

						xtables_error(PARAMETER_PROBLEM,

								 "Port `%s' not valid\n", slash+1);

					range->flags |= NF_NAT_RANGE_PROTO_OFFSET;

					range->base_proto.tcp.port = htons(baseport);

				}

			}

		}

		/* Starts with colon or [] colon? No IP info...*/

		if (colon == arg || colon == arg+2) {

			free(arg);

			return;

		}

		*colon = '\0';

	}

	range->flags |= NF_NAT_RANGE_MAP_IPS;

	dash = strchr(start, '-');

	if (colon && dash && dash > colon)

		dash = NULL;

	if (dash)

		*dash = '\0';

	ip = xtables_numeric_to_ip6addr(start);

	if (!ip)

		xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",

			      start);

	range->min_addr.in6 = *ip;

	if (dash) {

		ip = xtables_numeric_to_ip6addr(dash + 1);

		if (!ip)

			xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",

				      dash+1);

		range->max_addr.in6 = *ip;

	} else

		range->max_addr = range->min_addr;

	free(arg);

	return;

}

static void _DNAT_parse(struct xt_option_call *cb,

		struct nf_nat_range2 *range, int rev)

{

	const struct ip6t_entry *entry = cb->xt_entry;

	int portok;

	if (entry->ipv6.proto == IPPROTO_TCP ||

	    entry->ipv6.proto == IPPROTO_UDP ||

	    entry->ipv6.proto == IPPROTO_SCTP ||

	    entry->ipv6.proto == IPPROTO_DCCP ||

	    entry->ipv6.proto == IPPROTO_ICMP)

		portok = 1;

	else

		portok = 0;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_TO_DEST:

		if (cb->xflags & F_X_TO_DEST) {

			xtables_error(PARAMETER_PROBLEM,

				      "DNAT: Multiple --to-destination not supported");

		}

		parse_to(cb->arg, portok, range, rev);

		cb->xflags |= F_X_TO_DEST;

		break;

	case O_PERSISTENT:

		range->flags |= NF_NAT_RANGE_PERSISTENT;

		break;

	}

}

static void DNAT_parse(struct xt_option_call *cb)

{

	struct nf_nat_range *range_v1 = (void *)cb->data;

	struct nf_nat_range2 range = {};

	memcpy(&range, range_v1, sizeof(*range_v1));

	_DNAT_parse(cb, &range, 1);

	memcpy(range_v1, &range, sizeof(*range_v1));

}

static void DNAT_parse_v2(struct xt_option_call *cb)

{

	_DNAT_parse(cb, (struct nf_nat_range2 *)cb->data, 2);

}

static void _DNAT_fcheck(struct xt_fcheck_call *cb, unsigned int *flags)

{

	static const unsigned int f = F_TO_DEST | F_RANDOM;

	if ((cb->xflags & f) == f)

		*flags |= NF_NAT_RANGE_PROTO_RANDOM;

}

static void DNAT_fcheck(struct xt_fcheck_call *cb)

{

	_DNAT_fcheck(cb, &((struct nf_nat_range *)cb->data)->flags);

}

static void DNAT_fcheck_v2(struct xt_fcheck_call *cb)

{

	_DNAT_fcheck(cb, &((struct nf_nat_range2 *)cb->data)->flags);

}

static void print_range(const struct nf_nat_range2 *range, int rev)

{

	if (range->flags & NF_NAT_RANGE_MAP_IPS) {

		if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)

			printf("[");

		printf("%s", xtables_ip6addr_to_numeric(&range->min_addr.in6));

		if (memcmp(&range->min_addr, &range->max_addr,

			   sizeof(range->min_addr)))

			printf("-%s", xtables_ip6addr_to_numeric(&range->max_addr.in6));

		if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)

			printf("]");

	}

	if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {

		printf(":");

		printf("%hu", ntohs(range->min_proto.tcp.port));

		if (range->max_proto.tcp.port != range->min_proto.tcp.port)

			printf("-%hu", ntohs(range->max_proto.tcp.port));

		if (rev >= 2 && (range->flags & NF_NAT_RANGE_PROTO_OFFSET))

			printf("/%hu", ntohs(range->base_proto.tcp.port));

	}

}

static void _DNAT_print(const struct nf_nat_range2 *range, int rev)

{

	printf(" to:");

	print_range(range, rev);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)

		printf(" random");

	if (range->flags & NF_NAT_RANGE_PERSISTENT)

		printf(" persistent");

}

static void DNAT_print(const void *ip, const struct xt_entry_target *target,

                       int numeric)

{

	const struct nf_nat_range *range_v1 = (const void *)target->data;

	struct nf_nat_range2 range = {};

	memcpy(&range, range_v1, sizeof(*range_v1));

	_DNAT_print(&range, 1);

}

static void DNAT_print_v2(const void *ip, const struct xt_entry_target *target,

                          int numeric)

{

	_DNAT_print((const struct nf_nat_range2 *)target->data, 2);

}

static void _DNAT_save(const struct nf_nat_range2 *range, int rev)

{

	printf(" --to-destination ");

	print_range(range, rev);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)

		printf(" --random");

	if (range->flags & NF_NAT_RANGE_PERSISTENT)

		printf(" --persistent");

}

static void DNAT_save(const void *ip, const struct xt_entry_target *target)

{

	const struct nf_nat_range *range_v1 = (const void *)target->data;

	struct nf_nat_range2 range = {};

	memcpy(&range, range_v1, sizeof(*range_v1));

	_DNAT_save(&range, 1);

}

static void DNAT_save_v2(const void *ip, const struct xt_entry_target *target)

{

	_DNAT_save((const struct nf_nat_range2 *)target->data, 2);

}

static void print_range_xlate(const struct nf_nat_range2 *range,

			      struct xt_xlate *xl, int rev)

{

	bool proto_specified = range->flags & NF_NAT_RANGE_PROTO_SPECIFIED;

	if (range->flags & NF_NAT_RANGE_MAP_IPS) {

		xt_xlate_add(xl, "%s%s%s",

			     proto_specified ? "[" : "",

			     xtables_ip6addr_to_numeric(&range->min_addr.in6),

			     proto_specified ? "]" : "");

		if (memcmp(&range->min_addr, &range->max_addr,

			   sizeof(range->min_addr))) {

			xt_xlate_add(xl, "-%s%s%s",

				     proto_specified ? "[" : "",

				     xtables_ip6addr_to_numeric(&range->max_addr.in6),

				     proto_specified ? "]" : "");

		}

	}

	if (proto_specified) {

		xt_xlate_add(xl, ":%hu", ntohs(range->min_proto.tcp.port));

		if (range->max_proto.tcp.port != range->min_proto.tcp.port)

			xt_xlate_add(xl, "-%hu",

				   ntohs(range->max_proto.tcp.port));

	}

}

static int _DNAT_xlate(struct xt_xlate *xl,

		      const struct nf_nat_range2 *range, int rev)

{

	bool sep_need = false;

	const char *sep = " ";

	xt_xlate_add(xl, "dnat to ");

	print_range_xlate(range, xl, rev);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) {

		xt_xlate_add(xl, " random");

		sep_need = true;

	}

	if (range->flags & NF_NAT_RANGE_PERSISTENT) {

		if (sep_need)

			sep = ",";

		xt_xlate_add(xl, "%spersistent", sep);

	}

	return 1;

}

static int DNAT_xlate(struct xt_xlate *xl,

		      const struct xt_xlate_tg_params *params)

{

	const struct nf_nat_range *range_v1 = (const void *)params->target->data;

	struct nf_nat_range2 range = {};

	memcpy(&range, range_v1, sizeof(*range_v1));

	_DNAT_xlate(xl, &range, 1);

	return 1;

}

static int DNAT_xlate_v2(struct xt_xlate *xl,

		      const struct xt_xlate_tg_params *params)

{

	_DNAT_xlate(xl, (const struct nf_nat_range2 *)params->target->data, 2);

	return 1;

}

static struct xtables_target dnat_tg_reg[] = {

	{

		.name		= "DNAT",

		.version	= XTABLES_VERSION,

		.family		= NFPROTO_IPV6,

		.revision	= 1,

		.size		= XT_ALIGN(sizeof(struct nf_nat_range)),

		.userspacesize	= XT_ALIGN(sizeof(struct nf_nat_range)),

		.help		= DNAT_help,

		.print		= DNAT_print,

		.save		= DNAT_save,

		.x6_parse	= DNAT_parse,

		.x6_fcheck	= DNAT_fcheck,

		.x6_options	= DNAT_opts,

		.xlate		= DNAT_xlate,

	},

	{

		.name		= "DNAT",

		.version	= XTABLES_VERSION,

		.family		= NFPROTO_IPV6,

		.revision	= 2,

		.size		= XT_ALIGN(sizeof(struct nf_nat_range2)),

		.userspacesize	= XT_ALIGN(sizeof(struct nf_nat_range2)),

		.help		= DNAT_help_v2,

		.print		= DNAT_print_v2,

		.save		= DNAT_save_v2,

		.x6_parse	= DNAT_parse_v2,

		.x6_fcheck	= DNAT_fcheck_v2,

		.x6_options	= DNAT_opts,

		.xlate		= DNAT_xlate_v2,

	},

};

void _init(void)

{

	xtables_register_targets(dnat_tg_reg, ARRAY_SIZE(dnat_tg_reg));

}