#include <stdio.h>

#include <xtables.h>

#include <linux/netfilter/xt_length.h>

enum {

	O_LENGTH = 0,

};

static void length_help(void)

{

	printf(

"length match options:\n"

"[!] --length length[:length]    Match packet length against value or range\n"

"                                of values (inclusive)\n");

}

static const struct xt_option_entry length_opts[] = {

	{.name = "length", .id = O_LENGTH, .type = XTTYPE_UINT16RC,

	 .flags = XTOPT_MAND | XTOPT_INVERT},

	XTOPT_TABLEEND,

};

static void length_parse(struct xt_option_call *cb)

{

	struct xt_length_info *info = cb->data;

	xtables_option_parse(cb);

	info->min = cb->val.u16_range[0];

	info->max = cb->val.u16_range[0];

	if (cb->nvals >= 2)

		info->max = cb->val.u16_range[1];

	if (cb->invert)

		info->invert = 1;

}

static void

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

{

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

	printf(" length %s", info->invert ? "!" : "");

	if (info->min == info->max)

		printf("%u", info->min);

	else

		printf("%u:%u", info->min, info->max);

}

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

{

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

	printf("%s --length ", info->invert ? " !" : "");

	if (info->min == info->max)

		printf("%u", info->min);

	else

		printf("%u:%u", info->min, info->max);

}

static int length_xlate(struct xt_xlate *xl,

			const struct xt_xlate_mt_params *params)

{

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

	xt_xlate_add(xl, "meta length %s", info->invert ? "!= " : "");

	if (info->min == info->max)

		xt_xlate_add(xl, "%u", info->min);

	else

		xt_xlate_add(xl, "%u-%u", info->min, info->max);

	return 1;

}

static struct xtables_match length_match = {

	.family		= NFPROTO_UNSPEC,

	.name		= "length",

	.version	= XTABLES_VERSION,

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

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

	.help		= length_help,

	.print		= length_print,

	.save		= length_save,

	.x6_parse	= length_parse,

	.x6_options	= length_opts,

	.xlate		= length_xlate,

};

void _init(void)

{

	xtables_register_match(&length_match);

}