/* iptables match extension for limiting packets per destination
 *
 * (C) 2003 by Harald Welte <laforge@netfilter.org>
 *
 * Development of this code was funded by Astaro AG, http://www.astaro.com/
 *
 * Based on ipt_limit.c by
 * Jérôme de Vivie   <devivie@info.enserb.u-bordeaux.fr>
 * Hervé Eychenne    <rv@wallfire.org>
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <stddef.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_dstlimit.h>

#define IPT_DSTLIMIT_BURST	5

/* Function which prints out usage message. */
static void
help(void)
{
	printf(
"dstlimit v%s options:\n"
"--dstlimit <avg>		max average match rate\n"
"                                [Packets per second unless followed by \n"
"                                /sec /minute /hour /day postfixes]\n"
"--dstlimit-mode <mode>		mode (destip|destip-destport)\n"
"[--dstlimit-burst <num>]	number to match in a burst, default %u\n"
"[--dstlimit-htable-size <num>]	number of hashtable buckets\n"
"[--dstlimit-htable-max <num>]	number of hashtable entries\n"
"[--dstlimit-htable-gcinterval]	interval between garbage collection runs\n"
"[--dstlimit-htable-expire]	after which time are idle entries expired?\n"
"\n", IPTABLES_VERSION, IPT_DSTLIMIT_BURST);
}

static struct option opts[] = {
	{ "dstlimit", 1, 0, '%' },
	{ "dstlimit-burst", 1, 0, '$' },
	{ "dstlimit-htable-size", 1, 0, '&' },
	{ "dstlimit-htable-max", 1, 0, '*' },
	{ "dstlimit-htable-gcinterval", 1, 0, '(' },
	{ "dstlimit-htable-expire", 1, 0, ')' },
	{ "dstlimit-mode", 1, 0, '_' },
	{ 0 }
};

static
int parse_rate(const char *rate, u_int32_t *val)
{
	const char *delim;
	u_int32_t r;
	u_int32_t mult = 1;  /* Seconds by default. */

	delim = strchr(rate, '/');
	if (delim) {
		if (strlen(delim+1) == 0)
			return 0;

		if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
			mult = 1;
		else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
			mult = 60;
		else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
			mult = 60*60;
		else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
			mult = 24*60*60;
		else
			return 0;
	}
	r = atoi(rate);
	if (!r)
		return 0;

	/* This would get mapped to infinite (1/day is minimum they
           can specify, so we're ok at that end). */
	if (r / mult > IPT_DSTLIMIT_SCALE)
		exit_error(PARAMETER_PROBLEM, "Rate too fast `%s'\n", rate);

	*val = IPT_DSTLIMIT_SCALE * mult / r;
	return 1;
}

/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
	struct ipt_dstlimit_info *r = (struct ipt_dstlimit_info *)m->data;

	r->burst = IPT_DSTLIMIT_BURST;

	/* Can't cache this */
	*nfcache |= NFC_UNKNOWN;
}

#define PARAM_LIMIT		0x00000001
#define PARAM_BURST		0x00000002
#define PARAM_MODE		0x00000004
#define PARAM_SIZE		0x00000010
#define PARAM_MAX		0x00000020
#define PARAM_GCINTERVAL	0x00000040
#define PARAM_EXPIRE		0x00000080

/* Function which parses command options; returns true if it
   ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
      const struct ipt_entry *entry,
      unsigned int *nfcache,
      struct ipt_entry_match **match)
{
	struct ipt_dstlimit_info *r = 
			(struct ipt_dstlimit_info *)(*match)->data;
	unsigned int num;

	switch(c) {
	case '%':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM,
				   "Unexpected `!' after --dstlimit");
		if (!parse_rate(optarg, &r->avg))
			exit_error(PARAMETER_PROBLEM,
				   "bad rate `%s'", optarg);
		*flags |= PARAM_LIMIT;
		break;

	case '$':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM,
				   "Unexpected `!' after --dstlimit-burst");

		if (string_to_number(optarg, 0, 10000, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				   "bad --dstlimit-burst `%s'", optarg);
		r->burst = num;
		*flags |= PARAM_BURST;
		break;
	case '&':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM,
				"Unexpected `!' after --dstlimit-htable-size");

		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --dstlimit-htable-size: `%s'", optarg);
		r->hinfo.size = num;
		*flags |= PARAM_SIZE;
		break;
	case '*':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM,
				"Unexpected `!' after --dstlimit-htable-max");
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --dstlimit-htable-max: `%s'", optarg);
		r->hinfo.max = num;
		*flags |= PARAM_MAX;
		break;
	case '(':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM, "Unexpected `!' after "
					"--dstlimit-htable-gcinterval");
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --dstlimit-htable-gcinterval: `%s'", 
				optarg);
		/* FIXME: not HZ dependent!! */
		r->hinfo.gc_interval = num;
		*flags |= PARAM_GCINTERVAL;
		break;
	case ')':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM, "Unexpected `!' after " 
					"--dstlimit-htable-expire");
		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
			exit_error(PARAMETER_PROBLEM,
				"bad --dstlimit-htable-expire: `%s'", optarg);
		/* FIXME: not HZ dependent */
		r->hinfo.expire = num;
		*flags |= PARAM_EXPIRE;
		break;
	case '_':
		if (check_inverse(optarg, &invert, NULL, 0))
			exit_error(PARAMETER_PROBLEM, "Unexpected `!' after "
					"--dstlimit-mode");
		if (!strcmp(optarg, "destip"))
			r->mode = IPT_DSTLIMIT_MODE_DIP;
		else if (!strcmp(optarg, "destip-destport"))
			r->mode = IPT_DSTLIMIT_MODE_DIP_DPT;
		else
			exit_error(PARAMETER_PROBLEM, 
				"bad --dstlimit-mode: `%s'\n", optarg);
		*flags |= PARAM_MODE;
		break;
	default:
		return 0;
	}

	return 1;
}

/* Final check; nothing. */
static void final_check(unsigned int flags)
{
	if (!(flags & PARAM_LIMIT))
		exit_error(PARAMETER_PROBLEM,
				"You have to specify --dstlimit-rate");
	if (!(flags & PARAM_MODE))
		exit_error(PARAMETER_PROBLEM,
				"You have to specify --dstlimit-mode");
}

static struct rates
{
	const char *name;
	u_int32_t mult;
} rates[] = { { "day", IPT_DSTLIMIT_SCALE*24*60*60 },
	      { "hour", IPT_DSTLIMIT_SCALE*60*60 },
	      { "min", IPT_DSTLIMIT_SCALE*60 },
	      { "sec", IPT_DSTLIMIT_SCALE } };

static void print_rate(u_int32_t period)
{
	unsigned int i;

	for (i = 1; i < sizeof(rates)/sizeof(struct rates); i++) {
		if (period > rates[i].mult
            || rates[i].mult/period < rates[i].mult%period)
			break;
	}

	printf("%u/%s ", rates[i-1].mult / period, rates[i-1].name);
}

/* Prints out the matchinfo. */
static void
print(const struct ipt_ip *ip,
      const struct ipt_entry_match *match,
      int numeric)
{
	struct ipt_dstlimit_info *r = 
		(struct ipt_dstlimit_info *)match->data;
	printf("limit: avg "); print_rate(r->avg);
	printf("burst %u ", r->burst);
	switch (r->mode) {
		case IPT_DSTLIMIT_MODE_DIP:
			printf("mode dstip ");
			break;
		case IPT_DSTLIMIT_MODE_DIP_DPT:
			printf("mode dstip-dstport ");
			break;
	}
	printf("htable-size %u ", r->hinfo.size);
	printf("htable-max %u ", r->hinfo.max);
	printf("htable-gcinterval %u ", r->hinfo.gc_interval);
	printf("htable-expire %u ", r->hinfo.expire);
}

/* FIXME: Make minimalist: only print rate if not default --RR */
static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
	struct ipt_dstlimit_info *r = 
		(struct ipt_dstlimit_info *)match->data;

	printf("--limit "); print_rate(r->avg);
	if (r->burst != IPT_DSTLIMIT_BURST)
		printf("--limit-burst %u ", r->burst);
	switch (r->mode) {
		case IPT_DSTLIMIT_MODE_DIP:
			printf("--mode dstip ");
			break;
		case IPT_DSTLIMIT_MODE_DIP_DPT:
			printf("--mode dstip-dstport ");
			break;
	}
	printf("--htable-size %u ", r->hinfo.size);
	printf("--htable-max %u ", r->hinfo.max);
	printf("--htable-gcinterval %u", r->hinfo.gc_interval);
	printf("--htable-expire %u ", r->hinfo.expire);
}

static
struct iptables_match dstlimit
= { NULL,
    "dstlimit",
    IPTABLES_VERSION,
    IPT_ALIGN(sizeof(struct ipt_dstlimit_info)),
    IPT_ALIGN(sizeof(struct ipt_dstlimit_info)),
    //offsetof(struct ipt_dstlimit_info, prev),
    &help,
    &init,
    &parse,
    &final_check,
    &print,
    &save,
    opts
};

void _init(void)
{
	register_match(&dstlimit);
}