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/* Shared library add-on to iptables for the TTL target
* (C) 2000 by Harald Welte <laforge@gnumonks.org>
*
* $Id$
*
* This program is distributed under the terms of GNU GPL
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter_ipv4/ipt_TTL.h>
#define IPT_TTL_USED 1
static void TTL_help(void)
{
printf(
"TTL target options\n"
" --ttl-set value Set TTL to <value 0-255>\n"
" --ttl-dec value Decrement TTL by <value 1-255>\n"
" --ttl-inc value Increment TTL by <value 1-255>\n");
}
static int TTL_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_target **target)
{
struct ipt_TTL_info *info = (struct ipt_TTL_info *) (*target)->data;
unsigned int value;
if (*flags & IPT_TTL_USED) {
xtables_error(PARAMETER_PROBLEM,
"Can't specify TTL option twice");
}
if (!optarg)
xtables_error(PARAMETER_PROBLEM,
"TTL: You must specify a value");
if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
xtables_error(PARAMETER_PROBLEM,
"TTL: unexpected `!'");
if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX))
xtables_error(PARAMETER_PROBLEM,
"TTL: Expected value between 0 and 255");
switch (c) {
case '1':
info->mode = IPT_TTL_SET;
break;
case '2':
if (value == 0) {
xtables_error(PARAMETER_PROBLEM,
"TTL: decreasing by 0?");
}
info->mode = IPT_TTL_DEC;
break;
case '3':
if (value == 0) {
xtables_error(PARAMETER_PROBLEM,
"TTL: increasing by 0?");
}
info->mode = IPT_TTL_INC;
break;
default:
return 0;
}
info->ttl = value;
*flags |= IPT_TTL_USED;
return 1;
}
static void TTL_check(unsigned int flags)
{
if (!(flags & IPT_TTL_USED))
xtables_error(PARAMETER_PROBLEM,
"TTL: You must specify an action");
}
static void TTL_save(const void *ip, const struct xt_entry_target *target)
{
const struct ipt_TTL_info *info =
(struct ipt_TTL_info *) target->data;
switch (info->mode) {
case IPT_TTL_SET:
printf("--ttl-set ");
break;
case IPT_TTL_DEC:
printf("--ttl-dec ");
break;
case IPT_TTL_INC:
printf("--ttl-inc ");
break;
}
printf("%u ", info->ttl);
}
static void TTL_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct ipt_TTL_info *info =
(struct ipt_TTL_info *) target->data;
printf("TTL ");
switch (info->mode) {
case IPT_TTL_SET:
printf("set to ");
break;
case IPT_TTL_DEC:
printf("decrement by ");
break;
case IPT_TTL_INC:
printf("increment by ");
break;
}
printf("%u ", info->ttl);
}
static const struct option TTL_opts[] = {
{ "ttl-set", 1, NULL, '1' },
{ "ttl-dec", 1, NULL, '2' },
{ "ttl-inc", 1, NULL, '3' },
{ .name = NULL }
};
static struct xtables_target ttl_tg_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_target(&ttl_tg_reg);
}
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