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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>
*/
#define _BSD_SOURCE 1
#define _ISOC99_SOURCE 1
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <xtables.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_limit.h>
#define XT_LIMIT_AVG "3/hour"
#define XT_LIMIT_BURST 5
enum {
O_LIMIT = 0,
O_BURST,
};
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 xt_option_entry limit_opts[] = {
{.name = "limit", .id = O_LIMIT, .type = XTTYPE_STRING},
{.name = "limit-burst", .id = O_BURST, .type = XTTYPE_UINT32,
.flags = XTOPT_PUT, XTOPT_POINTER(struct xt_rateinfo, burst),
.min = 0, .max = 10000},
XTOPT_TABLEEND,
};
static
int parse_rate(const char *rate, uint32_t *val)
{
const char *delim;
uint32_t r;
uint32_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;
*val = XT_LIMIT_SCALE * mult / r;
if (*val == 0)
/*
* The rate maps to infinity. (1/day is the minimum they can
* specify, so we are ok at that end).
*/
xtables_error(PARAMETER_PROBLEM, "Rate too fast \"%s\"\n", rate);
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 void limit_parse(struct xt_option_call *cb)
{
struct xt_rateinfo *r = cb->data;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_LIMIT:
if (!parse_rate(cb->arg, &r->avg))
xtables_error(PARAMETER_PROBLEM,
"bad rate \"%s\"'", cb->arg);
break;
}
if (cb->invert)
xtables_error(PARAMETER_PROBLEM,
"limit does not support invert");
}
static const struct rates
{
const char *name;
uint32_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(uint32_t period)
{
unsigned int i;
if (period == 0) {
printf(" %f", INFINITY);
return;
}
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 const struct rates rates_xlate[] = {
{ "day", XT_LIMIT_SCALE * 24 * 60 * 60 },
{ "hour", XT_LIMIT_SCALE * 60 * 60 },
{ "minute", XT_LIMIT_SCALE * 60 },
{ "second", XT_LIMIT_SCALE }
};
static void print_rate_xlate(uint32_t period, struct xt_buf *buf)
{
unsigned int i;
if (period == 0) {
xt_buf_add(buf, " %f ", INFINITY);
return;
}
for (i = 1; i < ARRAY_SIZE(rates); ++i)
if (period > rates_xlate[i].mult ||
rates_xlate[i].mult / period < rates_xlate[i].mult % period)
break;
xt_buf_add(buf, " %u/%s ", rates_xlate[i - 1].mult / period,
rates_xlate[i - 1].name);
}
static int limit_xlate(const struct xt_entry_match *match,
struct xt_buf *buf, int numeric)
{
const struct xt_rateinfo *r = (const void *)match->data;
xt_buf_add(buf, "limit rate");
print_rate_xlate(r->avg, buf);
if (r->burst != XT_LIMIT_BURST)
xt_buf_add(buf, "burst %u packets ", r->burst);
return 1;
}
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,
.x6_parse = limit_parse,
.print = limit_print,
.save = limit_save,
.x6_options = limit_opts,
.xlate = limit_xlate,
};
void _init(void)
{
xtables_register_match(&limit_match);
}
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