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/* Kernel module to match connection tracking information.
* GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_state.h>
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_state_info *sinfo = matchinfo;
enum ip_conntrack_info ctinfo;
unsigned int statebit;
if (!ip_conntrack_get((struct sk_buff *)skb, &ctinfo))
statebit = IPT_STATE_INVALID;
else
statebit = IPT_STATE_BIT(ctinfo);
return (sinfo->statemask & statebit);
}
static int check(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
if (matchsize != IPT_ALIGN(sizeof(struct ipt_state_info)))
return 0;
return 1;
}
static struct ipt_match state_match
= { { NULL, NULL }, "state", &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(&state_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&state_match);
if (ip_conntrack_module)
__MOD_DEC_USE_COUNT(ip_conntrack_module);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
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