/*

 * Copyright (c) 2006-2013 Patrick McHardy <kaber@trash.net>

 */

#include <math.h>

#include <stdio.h>

#include <string.h>

#include <xtables.h>

#include <linux/netfilter/xt_statistic.h>

enum {

	O_MODE = 0,

	O_PROBABILITY,

	O_EVERY,

	O_PACKET,

	F_PROBABILITY = 1 << O_PROBABILITY,

	F_EVERY       = 1 << O_EVERY,

	F_PACKET      = 1 << O_PACKET,

};

static void statistic_help(void)

{

	printf(

"statistic match options:\n"

" --mode mode                    Match mode (random, nth)\n"

" random mode:\n"

"[!] --probability p		 Probability\n"

" nth mode:\n"

"[!] --every n			 Match every nth packet\n"

" --packet p			 Initial counter value (0 <= p <= n-1, default 0)\n");

}

#define s struct xt_statistic_info

static const struct xt_option_entry statistic_opts[] = {

	{.name = "mode", .id = O_MODE, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND},

	{.name = "probability", .id = O_PROBABILITY, .type = XTTYPE_DOUBLE,

	 .flags = XTOPT_INVERT, .min = 0, .max = 1,

	 .excl = F_EVERY | F_PACKET},

	{.name = "every", .id = O_EVERY, .type = XTTYPE_UINT32, .min = 1,

	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, u.nth.every),

	 .excl = F_PROBABILITY, .also = F_PACKET},

	{.name = "packet", .id = O_PACKET, .type = XTTYPE_UINT32,

	 .flags = XTOPT_PUT, XTOPT_POINTER(s, u.nth.packet),

	 .excl = F_PROBABILITY, .also = F_EVERY},

	XTOPT_TABLEEND,

};

#undef s

static void statistic_parse(struct xt_option_call *cb)

{

	struct xt_statistic_info *info = cb->data;

	if (cb->invert)

		info->flags |= XT_STATISTIC_INVERT;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_MODE:

		if (strcmp(cb->arg, "random") == 0)

			info->mode = XT_STATISTIC_MODE_RANDOM;

		else if (strcmp(cb->arg, "nth") == 0)

			info->mode = XT_STATISTIC_MODE_NTH;

		else

			xtables_error(PARAMETER_PROBLEM, "Bad mode \"%s\"",

				cb->arg);

		break;

	case O_PROBABILITY:

		info->u.random.probability = lround(0x80000000 * cb->val.dbl);

		break;

	case O_EVERY:

		--info->u.nth.every;

		break;

	}

}

static void statistic_check(struct xt_fcheck_call *cb)

{

	struct xt_statistic_info *info = cb->data;

	if (info->mode == XT_STATISTIC_MODE_RANDOM &&

	    !(cb->xflags & F_PROBABILITY))

		xtables_error(PARAMETER_PROBLEM,

			"--probability must be specified when using "

			"random mode");

	if (info->mode == XT_STATISTIC_MODE_NTH &&

	    !(cb->xflags & (F_EVERY | F_PACKET)))

		xtables_error(PARAMETER_PROBLEM,

			"--every and --packet must be specified when "

			"using nth mode");

	/* at this point, info->u.nth.every have been decreased. */

	if (info->u.nth.packet > info->u.nth.every)

		xtables_error(PARAMETER_PROBLEM,

			  "the --packet p must be 0 <= p <= n-1");

	info->u.nth.count = info->u.nth.every - info->u.nth.packet;

}

static void print_match(const struct xt_statistic_info *info, char *prefix)

{

	switch (info->mode) {

	case XT_STATISTIC_MODE_RANDOM:

		printf(" %smode random%s %sprobability %.11f", prefix,

		       (info->flags & XT_STATISTIC_INVERT) ? " !" : "",

		       prefix,

		       1.0 * info->u.random.probability / 0x80000000);

		break;

	case XT_STATISTIC_MODE_NTH:

		printf(" %smode nth%s %severy %u", prefix,

		       (info->flags & XT_STATISTIC_INVERT) ? " !" : "",

		       prefix,

		       info->u.nth.every + 1);

		if (info->u.nth.packet || *prefix)

			printf(" %spacket %u", prefix, info->u.nth.packet);

		break;

	}

}

static void

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

{

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

	printf(" statistic");

	print_match(info, "");

}

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

{

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

	print_match(info, "--");

}

static int statistic_xlate(struct xt_xlate *xl,

			   const struct xt_xlate_mt_params *params)

{

	const struct xt_statistic_info *info =

		(struct xt_statistic_info *)params->match->data;

	switch (info->mode) {

	case XT_STATISTIC_MODE_RANDOM:

		return 0;

	case XT_STATISTIC_MODE_NTH:

		xt_xlate_add(xl, "numgen inc mod %u %s%u",

			     info->u.nth.every + 1,

			     info->flags & XT_STATISTIC_INVERT ? "!= " : "",

			     info->u.nth.packet);

		break;

	}

	return 1;

}

static struct xtables_match statistic_match = {

	.family		= NFPROTO_UNSPEC,

	.name		= "statistic",

	.version	= XTABLES_VERSION,

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

	.userspacesize	= offsetof(struct xt_statistic_info, u.nth.count),

	.help		= statistic_help,

	.x6_parse	= statistic_parse,

	.x6_fcheck	= statistic_check,

	.print		= statistic_print,

	.save		= statistic_save,

	.x6_options	= statistic_opts,

	.xlate		= statistic_xlate,

};

void _init(void)

{

	xtables_register_match(&statistic_match);

}