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/* Shared library add-on to iptables to add limit support.
*
* Jérôme de Vivie <devivie@info.enserb.u-bordeaux.fr>
* Hervé Eychenne <eychenne@info.enserb.u-bordeaux.fr>
*/
#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_limit.h>
#define IPT_LIMIT_AVG "3/hour"
#define IPT_LIMIT_BURST 5
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"limit v%s options:\n"
"--limit avg max average match rate: default "IPT_LIMIT_AVG"\n"
" [Packets per second unless followed by \n"
" /sec /minute /hour /day postfixes]\n"
"--limit-burst number number to match in a burst, default %u\n"
"\n", NETFILTER_VERSION, IPT_LIMIT_BURST);
}
static struct option opts[] = {
{ "limit", 1, 0, '%' },
{ "limit-burst", 1, 0, '$' },
{ 0 }
};
static
int parse_rate(const char *rate, u_int32_t *val)
{
const char *delim;
u_int32_t r;
u_int32_t mult = 1; /* Seconds by default. */
delim = strchr(rate, '/');
if (delim) {
if (strlen(delim+1) == 0)
return 0;
if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
mult = 1;
else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
mult = 60;
else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
mult = 60*60;
else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
mult = 24*60*60;
else
return 0;
}
r = atoi(rate);
if (!r)
return 0;
/* This would get mapped to infinite (1/day is minimum they
can specify, so we're ok at that end). */
if (r / mult > IPT_LIMIT_SCALE)
exit_error(PARAMETER_PROBLEM, "Rate too fast `%s'\n", rate);
*val = IPT_LIMIT_SCALE * mult / r;
return 1;
}
/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
struct ipt_rateinfo *r = (struct ipt_rateinfo *)m->data;
parse_rate(IPT_LIMIT_AVG, &r->avg);
r->burst = IPT_LIMIT_BURST;
/* Can't cache this */
*nfcache |= NFC_UNKNOWN;
}
/* FIXME: handle overflow:
if (r->avg*r->burst/r->burst != r->avg)
exit_error(PARAMETER_PROBLEM,
"Sorry: burst too large for that avg rate.\n");
*/
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_rateinfo *r = (struct ipt_rateinfo *)(*match)->data;
int num;
switch(c) {
case '%':
if (check_inverse(optarg, &invert))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --limit");
if (!parse_rate(optarg, &r->avg))
exit_error(PARAMETER_PROBLEM,
"bad rate `%s'", optarg);
break;
case '$':
if (check_inverse(optarg, &invert))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --limit-burst");
num = string_to_number(optarg, 0, 10000);
if (num <= 0)
exit_error(PARAMETER_PROBLEM,
"bad --limit-burst `%s'", optarg);
r->burst = num;
break;
default:
return 0;
}
return 1;
}
/* Final check; nothing. */
static void final_check(unsigned int flags)
{
}
static struct rates
{
const char *name;
u_int32_t mult;
} rates[] = { { "day", IPT_LIMIT_SCALE*24*60*60 },
{ "hour", IPT_LIMIT_SCALE*60*60 },
{ "min", IPT_LIMIT_SCALE*60 },
{ "sec", IPT_LIMIT_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 != 0)
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_rateinfo *r = (struct ipt_rateinfo *)match->data;
printf("limit: avg "); print_rate(r->avg);
printf("burst %u ", r->burst);
}
/* 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_rateinfo *r = (struct ipt_rateinfo *)match->data;
printf("--limit "); print_rate(r->avg);
if (r->burst != IPT_LIMIT_BURST)
printf("--limit-burst %u ", r->burst);
}
struct iptables_match limit
= { NULL,
"limit",
NETFILTER_VERSION,
IPT_ALIGN(sizeof(struct ipt_rateinfo)),
offsetof(struct ipt_rateinfo, prev),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void _init(void)
{
register_match(&limit);
}
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