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/*
* IPv6 Hop Limit matching module
* Maciej Soltysiak <solt@dns.toxicfilms.tv>
* Based on HW's ttl match
* This program is released under the terms of GNU GPL
* Cleanups by Stephane Ouellette <ouellettes@videotron.ca>
*/
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter_ipv6/ip6t_hl.h>
static void hl_help(void)
{
printf(
"hl match options:\n"
"[!] --hl-eq value Match hop limit value\n"
" --hl-lt value Match HL < value\n"
" --hl-gt value Match HL > value\n");
}
static int hl_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct ip6t_hl_info *info = (struct ip6t_hl_info *) (*match)->data;
uint8_t value;
xtables_check_inverse(optarg, &invert, &optind, 0, argv);
value = atoi(optarg);
if (*flags)
xtables_error(PARAMETER_PROBLEM,
"Can't specify HL option twice");
if (!optarg)
xtables_error(PARAMETER_PROBLEM,
"hl: You must specify a value");
switch (c) {
case '2':
if (invert)
info->mode = IP6T_HL_NE;
else
info->mode = IP6T_HL_EQ;
/* is 0 allowed? */
info->hop_limit = value;
*flags = 1;
break;
case '3':
if (invert)
xtables_error(PARAMETER_PROBLEM,
"hl: unexpected `!'");
info->mode = IP6T_HL_LT;
info->hop_limit = value;
*flags = 1;
break;
case '4':
if (invert)
xtables_error(PARAMETER_PROBLEM,
"hl: unexpected `!'");
info->mode = IP6T_HL_GT;
info->hop_limit = value;
*flags = 1;
break;
}
return 1;
}
static void hl_check(unsigned int flags)
{
if (!flags)
xtables_error(PARAMETER_PROBLEM,
"HL match: You must specify one of "
"`--hl-eq', `--hl-lt', `--hl-gt'");
}
static void hl_print(const void *ip, const struct xt_entry_match *match,
int numeric)
{
static const char *const op[] = {
[IP6T_HL_EQ] = "==",
[IP6T_HL_NE] = "!=",
[IP6T_HL_LT] = "<",
[IP6T_HL_GT] = ">" };
const struct ip6t_hl_info *info =
(struct ip6t_hl_info *) match->data;
printf(" HL match HL %s %u", op[info->mode], info->hop_limit);
}
static void hl_save(const void *ip, const struct xt_entry_match *match)
{
static const char *const op[] = {
[IP6T_HL_EQ] = "--hl-eq",
[IP6T_HL_NE] = "! --hl-eq",
[IP6T_HL_LT] = "--hl-lt",
[IP6T_HL_GT] = "--hl-gt" };
const struct ip6t_hl_info *info =
(struct ip6t_hl_info *) match->data;
printf(" %s %u", op[info->mode], info->hop_limit);
}
static const struct option hl_opts[] = {
{.name = "hl", .has_arg = true, .val = '2'},
{.name = "hl-eq", .has_arg = true, .val = '2'},
{.name = "hl-lt", .has_arg = true, .val = '3'},
{.name = "hl-gt", .has_arg = true, .val = '4'},
XT_GETOPT_TABLEEND,
};
static struct xtables_match hl_mt6_reg = {
.name = "hl",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV6,
.size = XT_ALIGN(sizeof(struct ip6t_hl_info)),
.userspacesize = XT_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)
{
xtables_register_match(&hl_mt6_reg);
}
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