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/* Shared library add-on to iptables to add TTL matching support
* (C) 2000 by Harald Welte <laforge@gnumonks.org>
*
* Version: 1.3
*
* This program is released under the terms of GNU GPL */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ttl.h>
static void help(void)
{
printf(
"TTL match v%s options:\n"
" --ttl value Match time to live value\n", NETFILTER_VERSION);
}
static void init(struct ipt_entry_match *m, unsigned int *nfcache)
{
/* caching not yet implemented */
}
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_ttl_info *info = (struct ipt_ttl_info *) (*match)->data;
u_int8_t value;
switch (c) {
case '1':
if (check_inverse(optarg, &invert))
optind++;
value = atoi(argv[optind-1]);
/* is 0 allowed? */
info->ttl = value;
if (invert)
info->invert = 1;
break;
default:
return 0;
}
return 1;
}
static void final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"TTL match: You must specify `--ttl'");
}
static void print(const struct ipt_ip *ip,
const struct ipt_entry_match *match,
int numeric)
{
const struct ipt_ttl_info *info =
(struct ipt_ttl_info *) match->data;
printf("TTL match ");
if (info->invert)
printf("!");
printf("%u ", info->ttl);
}
static void save(const struct ipt_ip *ip,
const struct ipt_entry_match *match)
{
const struct ipt_ttl_info *info =
(struct ipt_ttl_info *) match->data;
printf("--ttl ");
if (info->invert)
printf("!");
printf("%u ", info->ttl);
}
static struct option opts[] = {
{ "ttl", 0, '1' },
{ 0 }
};
struct iptables_match ttl = {
NULL,
"ttl",
NETFILTER_VERSION,
IPT_ALIGN(sizeof(struct ipt_ttl_info)),
IPT_ALIGN(sizeof(struct ipt_ttl_info)),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void _init(void)
{
register_match(&ttl);
}
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