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/*
* IPv6 Hop Limit Target module
* Maciej Soltysiak <solt@dns.toxicfilms.tv>
* Based on HW's ttl target
* This program is distributed under the terms of GNU GPL
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <ip6tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_HL.h>
#define IP6T_HL_USED 1
static void HL_help(void)
{
printf(
"HL target v%s options\n"
" --hl-set value Set HL to <value 0-255>\n"
" --hl-dec value Decrement HL by <value 1-255>\n"
" --hl-inc value Increment HL by <value 1-255>\n"
, IPTABLES_VERSION);
}
static int HL_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_target **target)
{
struct ip6t_HL_info *info = (struct ip6t_HL_info *) (*target)->data;
unsigned int value;
if (*flags & IP6T_HL_USED) {
exit_error(PARAMETER_PROBLEM,
"Can't specify HL option twice");
}
if (!optarg)
exit_error(PARAMETER_PROBLEM,
"HL: You must specify a value");
if (check_inverse(optarg, &invert, NULL, 0))
exit_error(PARAMETER_PROBLEM,
"HL: unexpected `!'");
if (string_to_number(optarg, 0, 255, &value) == -1)
exit_error(PARAMETER_PROBLEM,
"HL: Expected value between 0 and 255");
switch (c) {
case '1':
info->mode = IP6T_HL_SET;
break;
case '2':
if (value == 0) {
exit_error(PARAMETER_PROBLEM,
"HL: decreasing by 0?");
}
info->mode = IP6T_HL_DEC;
break;
case '3':
if (value == 0) {
exit_error(PARAMETER_PROBLEM,
"HL: increasing by 0?");
}
info->mode = IP6T_HL_INC;
break;
default:
return 0;
}
info->hop_limit = value;
*flags |= IP6T_HL_USED;
return 1;
}
static void HL_check(unsigned int flags)
{
if (!(flags & IP6T_HL_USED))
exit_error(PARAMETER_PROBLEM,
"HL: You must specify an action");
}
static void HL_save(const void *ip, const struct xt_entry_target *target)
{
const struct ip6t_HL_info *info =
(struct ip6t_HL_info *) target->data;
switch (info->mode) {
case IP6T_HL_SET:
printf("--hl-set ");
break;
case IP6T_HL_DEC:
printf("--hl-dec ");
break;
case IP6T_HL_INC:
printf("--hl-inc ");
break;
}
printf("%u ", info->hop_limit);
}
static void HL_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct ip6t_HL_info *info =
(struct ip6t_HL_info *) target->data;
printf("HL ");
switch (info->mode) {
case IP6T_HL_SET:
printf("set to ");
break;
case IP6T_HL_DEC:
printf("decrement by ");
break;
case IP6T_HL_INC:
printf("increment by ");
break;
}
printf("%u ", info->hop_limit);
}
static const struct option HL_opts[] = {
{ "hl-set", 1, NULL, '1' },
{ "hl-dec", 1, NULL, '2' },
{ "hl-inc", 1, NULL, '3' },
{ }
};
static struct ip6tables_target hl_target6 = {
.name = "HL",
.version = IPTABLES_VERSION,
.size = IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
.userspacesize = IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
.help = HL_help,
.parse = HL_parse,
.final_check = HL_check,
.print = HL_print,
.save = HL_save,
.extra_opts = HL_opts,
};
void _init(void)
{
register_target6(&hl_target6);
}
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