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#include <stdio.h>
#include <xtables.h>
#include <linux/netfilter/xt_length.h>
enum {
O_LENGTH = 0,
};
static void length_help(void)
{
printf(
"length match options:\n"
"[!] --length length[:length] Match packet length against value or range\n"
" of values (inclusive)\n");
}
static const struct xt_option_entry length_opts[] = {
{.name = "length", .id = O_LENGTH, .type = XTTYPE_UINT16RC,
.flags = XTOPT_MAND | XTOPT_INVERT},
XTOPT_TABLEEND,
};
static void length_parse(struct xt_option_call *cb)
{
struct xt_length_info *info = cb->data;
xtables_option_parse(cb);
info->min = cb->val.u16_range[0];
info->max = cb->val.u16_range[0];
if (cb->nvals >= 2)
info->max = cb->val.u16_range[1];
if (cb->invert)
info->invert = 1;
}
static void
length_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
const struct xt_length_info *info = (void *)match->data;
printf(" length %s", info->invert ? "!" : "");
if (info->min == info->max)
printf("%u", info->min);
else
printf("%u:%u", info->min, info->max);
}
static void length_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_length_info *info = (void *)match->data;
printf("%s --length ", info->invert ? " !" : "");
if (info->min == info->max)
printf("%u", info->min);
else
printf("%u:%u", info->min, info->max);
}
static struct xtables_match length_match = {
.family = NFPROTO_UNSPEC,
.name = "length",
.version = XTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_length_info)),
.userspacesize = XT_ALIGN(sizeof(struct xt_length_info)),
.help = length_help,
.print = length_print,
.save = length_save,
.x6_parse = length_parse,
.x6_options = length_opts,
};
void _init(void)
{
xtables_register_match(&length_match);
}
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