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/* Shared library add-on to iptables to add related packet matching support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter/xt_helper.h>
/* Function which prints out usage message. */
static void helper_help(void)
{
printf(
"helper match v%s options:\n"
"[!] --helper string Match helper identified by string\n"
"\n",
IPTABLES_VERSION);
}
static const struct option helper_opts[] = {
{ "helper", 1, NULL, '1' },
{ .name = NULL }
};
/* Function which parses command options; returns true if it
ate an option */
static int
helper_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct xt_helper_info *info = (struct xt_helper_info *)(*match)->data;
switch (c) {
case '1':
if (*flags)
exit_error(PARAMETER_PROBLEM,
"helper match: Only use --helper ONCE!");
check_inverse(optarg, &invert, &invert, 0);
strncpy(info->name, optarg, 29);
info->name[29] = '\0';
if (invert)
info->invert = 1;
*flags = 1;
break;
default:
return 0;
}
return 1;
}
/* Final check; must have specified --helper. */
static void helper_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"helper match: You must specify `--helper'");
}
/* Prints out the info. */
static void
helper_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
struct xt_helper_info *info = (struct xt_helper_info *)match->data;
printf("helper match %s\"%s\" ", info->invert ? "! " : "", info->name);
}
/* Saves the union ipt_info in parsable form to stdout. */
static void helper_save(const void *ip, const struct xt_entry_match *match)
{
struct xt_helper_info *info = (struct xt_helper_info *)match->data;
printf("%s--helper ",info->invert ? "! " : "");
save_string(info->name);
}
static struct xtables_match helper_match = {
.family = AF_INET,
.name = "helper",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_helper_info)),
.help = helper_help,
.parse = helper_parse,
.final_check = helper_check,
.print = helper_print,
.save = helper_save,
.extra_opts = helper_opts,
};
static struct xtables_match helper_match6 = {
.family = AF_INET6,
.name = "helper",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_helper_info)),
.help = helper_help,
.parse = helper_parse,
.final_check = helper_check,
.print = helper_print,
.save = helper_save,
.extra_opts = helper_opts,
};
void _init(void)
{
xtables_register_match(&helper_match);
xtables_register_match(&helper_match6);
}
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