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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 <iptables.h>
#include <linux/netfilter_ipv4/ipt_helper.h>
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"helper match v%s options:\n"
"[!] --helper string Match helper identified by string\n"
"\n",
IPTABLES_VERSION);
}
static struct option opts[] = {
{ "helper", 1, 0, '1' },
{0}
};
/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
/* Can't cache this. */
*nfcache |= NFC_UNKNOWN;
}
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_helper_info *info = (struct ipt_helper_info *)(*match)->data;
switch (c) {
case '1':
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
final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"helper match: You must specify `--helper'");
}
/* Prints out the info. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_match *match,
int numeric)
{
struct ipt_helper_info *info = (struct ipt_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
save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
struct ipt_helper_info *info = (struct ipt_helper_info *)match->data;
printf("%s--helper \"%s\" ",info->invert ? "! " : "", info->name);
}
static
struct iptables_match helper
= { NULL,
"helper",
IPTABLES_VERSION,
IPT_ALIGN(sizeof(struct ipt_helper_info)),
IPT_ALIGN(sizeof(struct ipt_helper_info)),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void _init(void)
{
register_match(&helper);
}
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