/*

 * Copyright (c) 2008-2013 Patrick McHardy <kaber@trash.net>

 */

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <math.h>

#include <xtables.h>

#include <linux/netfilter/x_tables.h>

#include <linux/netfilter/xt_RATEEST.h>

struct rateest_tg_udata {

	unsigned int interval;

	unsigned int ewma_log;

};

static void

RATEEST_help(void)

{

	printf(

"RATEEST target options:\n"

"  --rateest-name name		Rate estimator name\n"

"  --rateest-interval sec	Rate measurement interval in seconds\n"

"  --rateest-ewmalog value	Rate measurement averaging time constant\n");

}

enum {

	O_NAME = 0,

	O_INTERVAL,

	O_EWMALOG,

};

#define s struct xt_rateest_target_info

static const struct xt_option_entry RATEEST_opts[] = {

	{.name = "rateest-name", .id = O_NAME, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND | XTOPT_PUT, XTOPT_POINTER(s, name)},

	{.name = "rateest-interval", .id = O_INTERVAL, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND},

	{.name = "rateest-ewmalog", .id = O_EWMALOG, .type = XTTYPE_STRING,

	 .flags = XTOPT_MAND},

	XTOPT_TABLEEND,

};

#undef s

/* Copied from iproute */

#define TIME_UNITS_PER_SEC	1000000

static int

RATEEST_get_time(unsigned int *time, const char *str)

{

	double t;

	char *p;

	t = strtod(str, &p);

	if (p == str)

		return -1;

	if (*p) {

		if (strcasecmp(p, "s") == 0 || strcasecmp(p, "sec")==0 ||

		    strcasecmp(p, "secs")==0)

			t *= TIME_UNITS_PER_SEC;

		else if (strcasecmp(p, "ms") == 0 || strcasecmp(p, "msec")==0 ||

			 strcasecmp(p, "msecs") == 0)

			t *= TIME_UNITS_PER_SEC/1000;

		else if (strcasecmp(p, "us") == 0 || strcasecmp(p, "usec")==0 ||

			 strcasecmp(p, "usecs") == 0)

			t *= TIME_UNITS_PER_SEC/1000000;

		else

			return -1;

	}

	*time = t;

	return 0;

}

static void

RATEEST_print_time(unsigned int time)

{

	double tmp = time;

	if (tmp >= TIME_UNITS_PER_SEC)

		printf(" %.1fs", tmp / TIME_UNITS_PER_SEC);

	else if (tmp >= TIME_UNITS_PER_SEC/1000)

		printf(" %.1fms", tmp / (TIME_UNITS_PER_SEC / 1000));

	else

		printf(" %uus", time);

}

static void RATEEST_parse(struct xt_option_call *cb)

{

	struct rateest_tg_udata *udata = cb->udata;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_INTERVAL:

		if (RATEEST_get_time(&udata->interval, cb->arg) < 0)

			xtables_error(PARAMETER_PROBLEM,

				   "RATEEST: bad interval value \"%s\"",

				   cb->arg);

		break;

	case O_EWMALOG:

		if (RATEEST_get_time(&udata->ewma_log, cb->arg) < 0)

			xtables_error(PARAMETER_PROBLEM,

				   "RATEEST: bad ewmalog value \"%s\"",

				   cb->arg);

		break;

	}

}

static void RATEEST_final_check(struct xt_fcheck_call *cb)

{

	struct xt_rateest_target_info *info = cb->data;

	struct rateest_tg_udata *udata = cb->udata;

	for (info->interval = 0; info->interval <= 5; info->interval++) {

		if (udata->interval <= (1 << info->interval) * (TIME_UNITS_PER_SEC / 4))

			break;

	}

	if (info->interval > 5)

		xtables_error(PARAMETER_PROBLEM,

			   "RATEEST: interval value is too large");

	info->interval -= 2;

	for (info->ewma_log = 1; info->ewma_log < 32; info->ewma_log++) {

		double w = 1.0 - 1.0 / (1 << info->ewma_log);

		if (udata->interval / (-log(w)) > udata->ewma_log)

			break;

	}

	info->ewma_log--;

	if (info->ewma_log == 0 || info->ewma_log >= 31)

		xtables_error(PARAMETER_PROBLEM,

			   "RATEEST: ewmalog value is out of range");

}

static void

__RATEEST_print(const struct xt_entry_target *target, const char *prefix)

{

	const struct xt_rateest_target_info *info = (const void *)target->data;

	unsigned int local_interval;

	unsigned int local_ewma_log;

	local_interval = (TIME_UNITS_PER_SEC << (info->interval + 2)) / 4;

	local_ewma_log = local_interval * (1 << (info->ewma_log));

	printf(" %sname %s", prefix, info->name);

	printf(" %sinterval", prefix);

	RATEEST_print_time(local_interval);

	printf(" %sewmalog", prefix);

	RATEEST_print_time(local_ewma_log);

}

static void

RATEEST_print(const void *ip, const struct xt_entry_target *target,

	      int numeric)

{

	__RATEEST_print(target, "");

}

static void

RATEEST_save(const void *ip, const struct xt_entry_target *target)

{

	__RATEEST_print(target, "--rateest-");

}

static struct xtables_target rateest_tg_reg = {

	.family		= NFPROTO_UNSPEC,

	.name		= "RATEEST",

	.version	= XTABLES_VERSION,

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

	.userspacesize	= offsetof(struct xt_rateest_target_info, est),

	.help		= RATEEST_help,

	.x6_parse	= RATEEST_parse,

	.x6_fcheck	= RATEEST_final_check,

	.print		= RATEEST_print,

	.save		= RATEEST_save,

	.x6_options	= RATEEST_opts,

	.udata_size	= sizeof(struct rateest_tg_udata),

};

void _init(void)

{

	xtables_register_target(&rateest_tg_reg);

}