#include <stdio.h>

#include <xtables.h>

#include <linux/netfilter/xt_rpfilter.h>

enum {

	O_RPF_LOOSE = 0,

	O_RPF_VMARK = 1,

	O_RPF_ACCEPT_LOCAL = 2,

	O_RPF_INVERT = 3,

};

static void rpfilter_help(void)

{

	printf(

"rpfilter match options:\n"

"    --loose          permit reverse path via any interface\n"

"    --validmark      use skb nfmark when performing route lookup\n"

"    --accept-local   do not reject packets with a local source address\n"

"    --invert         match packets that failed the reverse path test\n"

	);

}

static const struct xt_option_entry rpfilter_opts[] = {

	{.name = "loose", .id = O_RPF_LOOSE, .type = XTTYPE_NONE, },

	{.name = "validmark", .id = O_RPF_VMARK, .type = XTTYPE_NONE, },

	{.name = "accept-local", .id = O_RPF_ACCEPT_LOCAL, .type = XTTYPE_NONE, },

	{.name = "invert", .id = O_RPF_INVERT, .type = XTTYPE_NONE, },

	XTOPT_TABLEEND,

};

static void rpfilter_parse(struct xt_option_call *cb)

{

	struct xt_rpfilter_info *rpfinfo = cb->data;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_RPF_LOOSE:

		rpfinfo->flags |= XT_RPFILTER_LOOSE;

		break;

	case O_RPF_VMARK:

		rpfinfo->flags |= XT_RPFILTER_VALID_MARK;

		break;

	case O_RPF_ACCEPT_LOCAL:

		rpfinfo->flags |= XT_RPFILTER_ACCEPT_LOCAL;

		break;

	case O_RPF_INVERT:

		rpfinfo->flags |= XT_RPFILTER_INVERT;

		break;

	}

}

static void

rpfilter_print_prefix(const void *ip, const void *matchinfo,

			const char *prefix)

{

	const struct xt_rpfilter_info *info = matchinfo;

	if (info->flags & XT_RPFILTER_LOOSE)

		printf(" %s%s", prefix, rpfilter_opts[O_RPF_LOOSE].name);

	if (info->flags & XT_RPFILTER_VALID_MARK)

		printf(" %s%s", prefix, rpfilter_opts[O_RPF_VMARK].name);

	if (info->flags & XT_RPFILTER_ACCEPT_LOCAL)

		printf(" %s%s", prefix, rpfilter_opts[O_RPF_ACCEPT_LOCAL].name);

	if (info->flags & XT_RPFILTER_INVERT)

		printf(" %s%s", prefix, rpfilter_opts[O_RPF_INVERT].name);

}

static void

rpfilter_print(const void *ip, const struct xt_entry_match *match, int numeric)

{

	printf(" rpfilter");

	return rpfilter_print_prefix(ip, match->data, "");

}

static void rpfilter_save(const void *ip, const struct xt_entry_match *match)

{

	return rpfilter_print_prefix(ip, match->data, "--");

}

static int rpfilter_xlate(struct xt_xlate *xl,

			  const struct xt_xlate_mt_params *params)

{

	const struct xt_rpfilter_info *info = (void *)params->match->data;

	bool invert = info->flags & XT_RPFILTER_INVERT;

	if (info->flags & XT_RPFILTER_ACCEPT_LOCAL) {

		if (invert)

			xt_xlate_add(xl, "fib saddr type != local ");

		else

			return 0;

	}

	xt_xlate_add(xl, "fib saddr ");

	if (info->flags & XT_RPFILTER_VALID_MARK)

		xt_xlate_add(xl, ". mark ");

	if (!(info->flags & XT_RPFILTER_LOOSE))

		xt_xlate_add(xl, ". iif ");

	xt_xlate_add(xl, "oif %s0", invert ? "" : "!= ");

	return 1;

}

static struct xtables_match rpfilter_match = {

	.family		= NFPROTO_UNSPEC,

	.name		= "rpfilter",

	.version	= XTABLES_VERSION,

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

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

	.help		= rpfilter_help,

	.print		= rpfilter_print,

	.save		= rpfilter_save,

	.x6_parse	= rpfilter_parse,

	.x6_options	= rpfilter_opts,

	.xlate		= rpfilter_xlate,

};

void _init(void)

{

	xtables_register_match(&rpfilter_match);

}