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/* Kernel module to match connection tracking byte counter.
* GPL (C) 2002 Martin Devera (devik@cdi.cz).
*
* 2004-07-20 Harald Welte <laforge@netfilter.org>
* - reimplemented to use per-connection accounting counters
* - add functionality to match number of packets
* - add functionality to match average packet size
* - add support to match directions seperately
* 2005-10-16 Harald Welte <laforge@netfilter.org>
* - Port to x_tables
*
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack_compat.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_connbytes.h>
#include <asm/div64.h>
#include <asm/bitops.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection");
MODULE_ALIAS("ipt_connbytes");
/* 64bit divisor, dividend and result. dynamic precision */
static u_int64_t div64_64(u_int64_t dividend, u_int64_t divisor)
{
u_int32_t d = divisor;
if (divisor > 0xffffffffULL) {
unsigned int shift = fls(divisor >> 32);
d = divisor >> shift;
dividend >>= shift;
}
do_div(dividend, d);
return dividend;
}
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
const struct xt_connbytes_info *sinfo = matchinfo;
u_int64_t what = 0; /* initialize to make gcc happy */
const struct ip_conntrack_counter *counters;
if (!(counters = nf_ct_get_counters(skb)))
return 0; /* no match */
switch (sinfo->what) {
case XT_CONNBYTES_PKTS:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = counters[IP_CT_DIR_ORIGINAL].packets;
break;
case XT_CONNBYTES_DIR_REPLY:
what = counters[IP_CT_DIR_REPLY].packets;
break;
case XT_CONNBYTES_DIR_BOTH:
what = counters[IP_CT_DIR_ORIGINAL].packets;
what += counters[IP_CT_DIR_REPLY].packets;
break;
}
break;
case XT_CONNBYTES_BYTES:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = counters[IP_CT_DIR_ORIGINAL].bytes;
break;
case XT_CONNBYTES_DIR_REPLY:
what = counters[IP_CT_DIR_REPLY].bytes;
break;
case XT_CONNBYTES_DIR_BOTH:
what = counters[IP_CT_DIR_ORIGINAL].bytes;
what += counters[IP_CT_DIR_REPLY].bytes;
break;
}
break;
case XT_CONNBYTES_AVGPKT:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = div64_64(counters[IP_CT_DIR_ORIGINAL].bytes,
counters[IP_CT_DIR_ORIGINAL].packets);
break;
case XT_CONNBYTES_DIR_REPLY:
what = div64_64(counters[IP_CT_DIR_REPLY].bytes,
counters[IP_CT_DIR_REPLY].packets);
break;
case XT_CONNBYTES_DIR_BOTH:
{
u_int64_t bytes;
u_int64_t pkts;
bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
counters[IP_CT_DIR_REPLY].bytes;
pkts = counters[IP_CT_DIR_ORIGINAL].packets+
counters[IP_CT_DIR_REPLY].packets;
/* FIXME_THEORETICAL: what to do if sum
* overflows ? */
what = div64_64(bytes, pkts);
}
break;
}
break;
}
if (sinfo->count.to)
return (what <= sinfo->count.to && what >= sinfo->count.from);
else
return (what >= sinfo->count.from);
}
static int check(const char *tablename,
const void *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
const struct xt_connbytes_info *sinfo = matchinfo;
if (matchsize != XT_ALIGN(sizeof(struct xt_connbytes_info)))
return 0;
if (sinfo->what != XT_CONNBYTES_PKTS &&
sinfo->what != XT_CONNBYTES_BYTES &&
sinfo->what != XT_CONNBYTES_AVGPKT)
return 0;
if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
sinfo->direction != XT_CONNBYTES_DIR_BOTH)
return 0;
return 1;
}
static struct xt_match connbytes_match = {
.name = "connbytes",
.match = &match,
.checkentry = &check,
.me = THIS_MODULE
};
static struct xt_match connbytes6_match = {
.name = "connbytes",
.match = &match,
.checkentry = &check,
.me = THIS_MODULE
};
static int __init init(void)
{
int ret;
ret = xt_register_match(AF_INET, &connbytes_match);
if (ret)
return ret;
ret = xt_register_match(AF_INET6, &connbytes6_match);
if (ret)
xt_unregister_match(AF_INET, &connbytes_match);
return ret;
}
static void __exit fini(void)
{
xt_unregister_match(AF_INET, &connbytes_match);
xt_unregister_match(AF_INET6, &connbytes6_match);
}
module_init(init);
module_exit(fini);
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