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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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <ip6tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_hl.h>
static void help(void)
{
printf(
"HL match v%s options:\n"
" --hl-eq [!] value Match hop limit value\n"
" --hl-lt value Match HL < value\n"
" --hl-gt value Match HL > value\n"
, IPTABLES_VERSION);
}
static void init(struct ip6t_entry_match *m, unsigned int *nfcache)
{
/* caching not yet implemented */
*nfcache |= NFC_UNKNOWN;
}
static int parse(int c, char **argv, int invert, unsigned int *flags,
const struct ip6t_entry *entry, unsigned int *nfcache,
struct ip6t_entry_match **match)
{
struct ip6t_hl_info *info = (struct ip6t_hl_info *) (*match)->data;
u_int8_t value;
check_inverse(optarg, &invert, &optind, 0);
value = atoi(argv[optind-1]);
if (*flags)
exit_error(PARAMETER_PROBLEM,
"Can't specify HL option twice");
if (!optarg)
exit_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)
exit_error(PARAMETER_PROBLEM,
"hl: unexpected `!'");
info->mode = IP6T_HL_LT;
info->hop_limit = value;
*flags = 1;
break;
case '4':
if (invert)
exit_error(PARAMETER_PROBLEM,
"hl: unexpected `!'");
info->mode = IP6T_HL_GT;
info->hop_limit = value;
*flags = 1;
break;
default:
return 0;
}
return 1;
}
static void final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"HL match: You must specify one of "
"`--hl-eq', `--hl-lt', `--hl-gt'");
}
static void print(const struct ip6t_ip6 *ip,
const struct ip6t_entry_match *match,
int numeric)
{
static const char *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 save(const struct ip6t_ip6 *ip,
const struct ip6t_entry_match *match)
{
static const char *op[] = {
[IP6T_HL_EQ] = "eq",
[IP6T_HL_NE] = "eq !",
[IP6T_HL_LT] = "lt",
[IP6T_HL_GT] = "gt" };
const struct ip6t_hl_info *info =
(struct ip6t_hl_info *) match->data;
printf("--hl-%s %u ", op[info->mode], info->hop_limit);
}
static struct option opts[] = {
{ .name = "hl", .has_arg = 1, .flag = 0, .val = '2' },
{ .name = "hl-eq", .has_arg = 1, .flag = 0, .val = '2' },
{ .name = "hl-lt", .has_arg = 1, .flag = 0, .val = '3' },
{ .name = "hl-gt", .has_arg = 1, .flag = 0, .val = '4' },
{ 0 }
};
static
struct ip6tables_match hl = {
.name = "hl",
.version = IPTABLES_VERSION,
.size = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
.userspacesize = IP6T_ALIGN(sizeof(struct ip6t_hl_info)),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
register_match6(&hl);
}
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