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#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter/xt_statistic.h>
static void statistic_help(void)
{
printf(
"statistic match options:\n"
" --mode mode Match mode (random, nth)\n"
" random mode:\n"
" --probability p Probability\n"
" nth mode:\n"
" --every n Match every nth packet\n"
" --packet p Initial counter value (0 <= p <= n-1, default 0)\n");
}
static const struct option statistic_opts[] = {
{ "mode", 1, NULL, '1' },
{ "probability", 1, NULL, '2' },
{ "every", 1, NULL, '3' },
{ "packet", 1, NULL, '4' },
{ .name = NULL }
};
static struct xt_statistic_info *global_info;
static void statistic_mt_init(struct xt_entry_match *match)
{
global_info = (void *)match->data;
}
static int
statistic_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct xt_statistic_info *info = (void *)(*match)->data;
unsigned int val;
double prob;
if (invert)
info->flags |= XT_STATISTIC_INVERT;
switch (c) {
case '1':
if (*flags & 0x1)
xtables_error(PARAMETER_PROBLEM, "double --mode");
if (!strcmp(optarg, "random"))
info->mode = XT_STATISTIC_MODE_RANDOM;
else if (!strcmp(optarg, "nth"))
info->mode = XT_STATISTIC_MODE_NTH;
else
xtables_error(PARAMETER_PROBLEM, "Bad mode \"%s\"", optarg);
*flags |= 0x1;
break;
case '2':
if (*flags & 0x2)
xtables_error(PARAMETER_PROBLEM, "double --probability");
prob = atof(optarg);
if (prob < 0 || prob > 1)
xtables_error(PARAMETER_PROBLEM,
"--probability must be between 0 and 1");
info->u.random.probability = 0x80000000 * prob;
*flags |= 0x2;
break;
case '3':
if (*flags & 0x4)
xtables_error(PARAMETER_PROBLEM, "double --every");
if (!xtables_strtoui(optarg, NULL, &val, 0, UINT32_MAX))
xtables_error(PARAMETER_PROBLEM,
"cannot parse --every `%s'", optarg);
info->u.nth.every = val;
if (info->u.nth.every == 0)
xtables_error(PARAMETER_PROBLEM, "--every cannot be 0");
info->u.nth.every--;
*flags |= 0x4;
break;
case '4':
if (*flags & 0x8)
xtables_error(PARAMETER_PROBLEM, "double --packet");
if (!xtables_strtoui(optarg, NULL, &val, 0, UINT32_MAX))
xtables_error(PARAMETER_PROBLEM,
"cannot parse --packet `%s'", optarg);
info->u.nth.packet = val;
*flags |= 0x8;
break;
default:
return 0;
}
return 1;
}
static void statistic_check(unsigned int flags)
{
if (!(flags & 0x1))
xtables_error(PARAMETER_PROBLEM, "no mode specified");
if ((flags & 0x2) && (flags & (0x4 | 0x8)))
xtables_error(PARAMETER_PROBLEM,
"both nth and random parameters given");
if (flags & 0x2 && global_info->mode != XT_STATISTIC_MODE_RANDOM)
xtables_error(PARAMETER_PROBLEM,
"--probability can only be used in random mode");
if (flags & 0x4 && global_info->mode != XT_STATISTIC_MODE_NTH)
xtables_error(PARAMETER_PROBLEM,
"--every can only be used in nth mode");
if (flags & 0x8 && global_info->mode != XT_STATISTIC_MODE_NTH)
xtables_error(PARAMETER_PROBLEM,
"--packet can only be used in nth mode");
if ((flags & 0x8) && !(flags & 0x4))
xtables_error(PARAMETER_PROBLEM,
"--packet can only be used with --every");
/* at this point, info->u.nth.every have been decreased. */
if (global_info->u.nth.packet > global_info->u.nth.every)
xtables_error(PARAMETER_PROBLEM,
"the --packet p must be 0 <= p <= n-1");
global_info->u.nth.count = global_info->u.nth.every -
global_info->u.nth.packet;
}
static void print_match(const struct xt_statistic_info *info, char *prefix)
{
if (info->flags & XT_STATISTIC_INVERT)
printf("! ");
switch (info->mode) {
case XT_STATISTIC_MODE_RANDOM:
printf("%smode random %sprobability %f ", prefix, prefix,
1.0 * info->u.random.probability / 0x80000000);
break;
case XT_STATISTIC_MODE_NTH:
printf("%smode nth %severy %u ", prefix, prefix,
info->u.nth.every + 1);
if (info->u.nth.packet)
printf("%spacket %u ", prefix, info->u.nth.packet);
break;
}
}
static void
statistic_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
const struct xt_statistic_info *info = (const void *)match->data;
printf("statistic ");
print_match(info, "");
}
static void statistic_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_statistic_info *info = (const void *)match->data;
print_match(info, "--");
}
static struct xtables_match statistic_match = {
.family = NFPROTO_UNSPEC,
.name = "statistic",
.version = XTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_statistic_info)),
.userspacesize = offsetof(struct xt_statistic_info, u.nth.count),
.init = statistic_mt_init,
.help = statistic_help,
.parse = statistic_parse,
.final_check = statistic_check,
.print = statistic_print,
.save = statistic_save,
.extra_opts = statistic_opts,
};
void _init(void)
{
xtables_register_match(&statistic_match);
}
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