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/* Shared library add-on to iptables to add TTL matching support
* (C) 2000 by Harald Welte <laforge@gnumonks.org>
*
* $Id$
*
* This program is released under the terms of GNU GPL */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ttl.h>
static void ttl_help(void)
{
printf(
"ttl match options:\n"
" --ttl-eq value Match time to live value\n"
" --ttl-lt value Match TTL < value\n"
" --ttl-gt value Match TTL > value\n");
}
static int ttl_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct ipt_ttl_info *info = (struct ipt_ttl_info *) (*match)->data;
unsigned int value;
check_inverse(optarg, &invert, &optind, 0);
switch (c) {
case '2':
if (string_to_number(optarg, 0, UINT8_MAX, &value) == -1)
exit_error(PARAMETER_PROBLEM,
"ttl: Expected value between 0 and 255");
if (invert)
info->mode = IPT_TTL_NE;
else
info->mode = IPT_TTL_EQ;
/* is 0 allowed? */
info->ttl = value;
break;
case '3':
if (string_to_number(optarg, 0, UINT8_MAX, &value) == -1)
exit_error(PARAMETER_PROBLEM,
"ttl: Expected value between 0 and 255");
if (invert)
exit_error(PARAMETER_PROBLEM,
"ttl: unexpected `!'");
info->mode = IPT_TTL_LT;
info->ttl = value;
break;
case '4':
if (string_to_number(optarg, 0, UINT8_MAX, &value) == -1)
exit_error(PARAMETER_PROBLEM,
"ttl: Expected value between 0 and 255");
if (invert)
exit_error(PARAMETER_PROBLEM,
"ttl: unexpected `!'");
info->mode = IPT_TTL_GT;
info->ttl = value;
break;
default:
return 0;
}
if (*flags)
exit_error(PARAMETER_PROBLEM,
"Can't specify TTL option twice");
*flags = 1;
return 1;
}
static void ttl_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"TTL match: You must specify one of "
"`--ttl-eq', `--ttl-lt', `--ttl-gt");
}
static void ttl_print(const void *ip, const struct xt_entry_match *match,
int numeric)
{
const struct ipt_ttl_info *info =
(struct ipt_ttl_info *) match->data;
printf("TTL match ");
switch (info->mode) {
case IPT_TTL_EQ:
printf("TTL == ");
break;
case IPT_TTL_NE:
printf("TTL != ");
break;
case IPT_TTL_LT:
printf("TTL < ");
break;
case IPT_TTL_GT:
printf("TTL > ");
break;
}
printf("%u ", info->ttl);
}
static void ttl_save(const void *ip, const struct xt_entry_match *match)
{
const struct ipt_ttl_info *info =
(struct ipt_ttl_info *) match->data;
switch (info->mode) {
case IPT_TTL_EQ:
printf("--ttl-eq ");
break;
case IPT_TTL_NE:
printf("! --ttl-eq ");
break;
case IPT_TTL_LT:
printf("--ttl-lt ");
break;
case IPT_TTL_GT:
printf("--ttl-gt ");
break;
default:
/* error */
break;
}
printf("%u ", info->ttl);
}
static const struct option ttl_opts[] = {
{ "ttl", 1, NULL, '2' },
{ "ttl-eq", 1, NULL, '2'},
{ "ttl-lt", 1, NULL, '3'},
{ "ttl-gt", 1, NULL, '4'},
{ .name = NULL }
};
static struct xtables_match ttl_mt_reg = {
.name = "ttl",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct ipt_ttl_info)),
.userspacesize = XT_ALIGN(sizeof(struct ipt_ttl_info)),
.help = ttl_help,
.parse = ttl_parse,
.final_check = ttl_check,
.print = ttl_print,
.save = ttl_save,
.extra_opts = ttl_opts,
};
void _init(void)
{
xtables_register_match(&ttl_mt_reg);
}
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