text: /*
   * 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);
  }
  