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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 <rv@wallfire.org>
*/
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <stddef.h>
#include <linux/netfilter/x_tables.h>
/* For 64bit kernel / 32bit userspace */
#include <linux/netfilter/xt_limit.h>
#define XT_LIMIT_AVG "3/hour"
#define XT_LIMIT_BURST 5
static void limit_help(void)
{
printf(
"limit match options:\n"
"--limit avg max average match rate: default "XT_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",
XT_LIMIT_BURST);
}
static const struct option limit_opts[] = {
{.name = "limit", .has_arg = true, .val = '%'},
{.name = "limit-burst", .has_arg = true, .val = '$'},
XT_GETOPT_TABLEEND,
};
static
int parse_rate(const char *rate, u_int32_t *val)
{
const char *delim;
u_int32_t r;
u_int32_t mult = 1; /* Seconds by default. */
delim = strchr(rate, '/');
if (delim) {
if (strlen(delim+1) == 0)
return 0;
if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
mult = 1;
else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
mult = 60;
else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
mult = 60*60;
else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
mult = 24*60*60;
else
return 0;
}
r = atoi(rate);
if (!r)
return 0;
/* This would get mapped to infinite (1/day is minimum they
can specify, so we're ok at that end). */
if (r / mult > XT_LIMIT_SCALE)
xtables_error(PARAMETER_PROBLEM, "Rate too fast \"%s\"\n", rate);
*val = XT_LIMIT_SCALE * mult / r;
return 1;
}
static void limit_init(struct xt_entry_match *m)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)m->data;
parse_rate(XT_LIMIT_AVG, &r->avg);
r->burst = XT_LIMIT_BURST;
}
/* FIXME: handle overflow:
if (r->avg*r->burst/r->burst != r->avg)
xtables_error(PARAMETER_PROBLEM,
"Sorry: burst too large for that avg rate.\n");
*/
static int
limit_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)(*match)->data;
unsigned int num;
switch(c) {
case '%':
if (xtables_check_inverse(optarg, &invert, &optind, 0, argv)) break;
if (!parse_rate(optarg, &r->avg))
xtables_error(PARAMETER_PROBLEM,
"bad rate `%s'", optarg);
break;
case '$':
if (xtables_check_inverse(optarg, &invert, &optind, 0, argv)) break;
if (!xtables_strtoui(optarg, NULL, &num, 0, 10000))
xtables_error(PARAMETER_PROBLEM,
"bad --limit-burst `%s'", optarg);
r->burst = num;
break;
default:
return 0;
}
if (invert)
xtables_error(PARAMETER_PROBLEM,
"limit does not support invert");
return 1;
}
static const struct rates
{
const char *name;
u_int32_t mult;
} rates[] = { { "day", XT_LIMIT_SCALE*24*60*60 },
{ "hour", XT_LIMIT_SCALE*60*60 },
{ "min", XT_LIMIT_SCALE*60 },
{ "sec", XT_LIMIT_SCALE } };
static void print_rate(u_int32_t period)
{
unsigned int i;
for (i = 1; i < ARRAY_SIZE(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);
}
static void
limit_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
const struct xt_rateinfo *r = (const void *)match->data;
printf("limit: avg "); print_rate(r->avg);
printf("burst %u ", r->burst);
}
static void limit_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_rateinfo *r = (const void *)match->data;
printf("--limit "); print_rate(r->avg);
if (r->burst != XT_LIMIT_BURST)
printf("--limit-burst %u ", r->burst);
}
static struct xtables_match limit_match = {
.family = NFPROTO_UNSPEC,
.name = "limit",
.version = XTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_rateinfo)),
.userspacesize = offsetof(struct xt_rateinfo, prev),
.help = limit_help,
.init = limit_init,
.parse = limit_parse,
.print = limit_print,
.save = limit_save,
.extra_opts = limit_opts,
};
void _init(void)
{
xtables_register_match(&limit_match);
}
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