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/*
* iptables module to match on related connections
* (c) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
*
* Released under the terms of GNU GPLv2.
*
* 19 Mar 2002 Harald Welte <laforge@gnumonks.org>:
* - Port to newnat infrastructure
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_helper.h>
MODULE_LICENSE("GPL");
#define DEBUGP(format, args...)
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
const void *hdr,
u_int16_t datalen,
int *hotdrop)
{
const struct ipt_helper_info *info = matchinfo;
struct ip_conntrack_expect *exp;
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
if (!ct) {
DEBUGP("ipt_helper: Eek! invalid conntrack?\n");
return 0;
}
if (!ct->master) {
DEBUGP("ipt_helper: conntrack %p has no master\n", ct);
return 0;
}
exp = ct->master;
if (!exp->expectant) {
DEBUGP("ipt_helper: expectation %p without expectant !?!\n",
exp);
return 0;
}
if (!exp->expectant->helper) {
DEBUGP("ipt_helper: master ct %p has no helper\n",
exp->expectant);
return 0;
}
DEBUGP("master's name = %s , info->name = %s\n",
exp->expectant->helper->name, info->name);
return !strncmp(exp->expectant->helper->name, info->name,
strlen(exp->expectant->helper->name)) ^ info->invert;
}
static int check(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
struct ipt_helper_info *info = matchinfo;
info->name[29] = '\0';
/* verify size */
if (matchsize != IPT_ALIGN(sizeof(struct ipt_helper_info)))
return 0;
/* verify that we actually should match anything */
if ( strlen(info->name) == 0 )
return 0;
return 1;
}
static struct ipt_match helper_match
= { { NULL, NULL }, "helper", &match, &check, NULL, THIS_MODULE };
static int __init init(void)
{
/* NULL if ip_conntrack not a module */
if (ip_conntrack_module)
__MOD_INC_USE_COUNT(ip_conntrack_module);
return ipt_register_match(&helper_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&helper_match);
if (ip_conntrack_module)
__MOD_DEC_USE_COUNT(ip_conntrack_module);
}
module_init(init);
module_exit(fini);
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