/*

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

 *

 * Based on Rusty Russell's IPv4 SNAT 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_SRC = 0,

	O_RANDOM,

	O_RANDOM_FULLY,

	O_PERSISTENT,

	O_X_TO_SRC,

	F_TO_SRC       = 1 << O_TO_SRC,

	F_RANDOM       = 1 << O_RANDOM,

	F_RANDOM_FULLY = 1 << O_RANDOM_FULLY,

	F_X_TO_SRC     = 1 << O_X_TO_SRC,

};

static void SNAT_help(void)

{

	printf(

"SNAT target options:\n"

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

"				Address to map source to.\n"

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

}

static const struct xt_option_entry SNAT_opts[] = {

	{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND | XTOPT_MULTI},

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

	{.name = "random-fully", .id = O_RANDOM_FULLY, .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_range *range)

{

	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);

		}

		/* 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 SNAT_parse(struct xt_option_call *cb)

{

	const struct ip6t_entry *entry = cb->xt_entry;

	struct nf_nat_range *range = cb->data;

	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_SRC:

		if (cb->xflags & F_X_TO_SRC) {

			xtables_error(PARAMETER_PROBLEM,

				      "SNAT: Multiple --to-source not supported");

		}

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

		cb->xflags |= F_X_TO_SRC;

		break;

	case O_PERSISTENT:

		range->flags |= NF_NAT_RANGE_PERSISTENT;

		break;

	}

}

static void SNAT_fcheck(struct xt_fcheck_call *cb)

{

	static const unsigned int f = F_TO_SRC | F_RANDOM;

	static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY;

	struct nf_nat_range *range = cb->data;

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

		range->flags |= NF_NAT_RANGE_PROTO_RANDOM;

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

		range->flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;

}

static void print_range(const struct nf_nat_range *range)

{

	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));

	}

}

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

                       int numeric)

{

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

	printf(" to:");

	print_range(range);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)

		printf(" random");

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)

		printf(" random-fully");

	if (range->flags & NF_NAT_RANGE_PERSISTENT)

		printf(" persistent");

}

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

{

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

	printf(" --to-source ");

	print_range(range);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)

		printf(" --random");

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)

		printf(" --random-fully");

	if (range->flags & NF_NAT_RANGE_PERSISTENT)

		printf(" --persistent");

}

static void print_range_xlate(const struct nf_nat_range *range,

			      struct xt_xlate *xl)

{

	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 SNAT_xlate(struct xt_xlate *xl,

		      const struct xt_xlate_tg_params *params)

{

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

	bool sep_need = false;

	const char *sep = " ";

	xt_xlate_add(xl, "snat to ");

	print_range_xlate(range, xl);

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) {

		xt_xlate_add(xl, " random");

		sep_need = true;

	}

	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) {

		if (sep_need)

			sep = ",";

		xt_xlate_add(xl, "%sfully-random", sep);

		sep_need = true;

	}

	if (range->flags & NF_NAT_RANGE_PERSISTENT) {

		if (sep_need)

			sep = ",";

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

	}

	return 1;

}

static struct xtables_target snat_tg_reg = {

	.name		= "SNAT",

	.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		= SNAT_help,

	.x6_parse	= SNAT_parse,

	.x6_fcheck	= SNAT_fcheck,

	.print		= SNAT_print,

	.save		= SNAT_save,

	.x6_options	= SNAT_opts,

	.xlate		= SNAT_xlate,

};

void _init(void)

{

	xtables_register_target(&snat_tg_reg);

}