/* Kernel module to match connection tracking byte counter.
   * GPL (C) 2002 Martin Devera (devik@cdi.cz).

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>

  #include <linux/bitops.h>

  #include <linux/skbuff.h>

  #include <linux/math64.h>

  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter/xt_connbytes.h>

  #include <net/netfilter/nf_conntrack.h>

  #include <net/netfilter/nf_conntrack_acct.h>

  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");

  MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");

  MODULE_ALIAS("ipt_connbytes");

  MODULE_ALIAS("ip6t_connbytes");

  static bool

  connbytes_mt(const struct sk_buff *skb, struct xt_action_param *par)

  {

  	const struct xt_connbytes_info *sinfo = par->matchinfo;

  	const struct nf_conn *ct;

  	enum ip_conntrack_info ctinfo;

  	u_int64_t what = 0;	/* initialize to make gcc happy */

  	u_int64_t bytes = 0;
  	u_int64_t pkts = 0;

  	const struct nf_conn_acct *acct;

  	const struct nf_conn_counter *counters;

  	ct = nf_ct_get(skb, &ctinfo);
  	if (!ct)

  		return false;

  	acct = nf_conn_acct_find(ct);
  	if (!acct)

  		return false;

  	counters = acct->counter;

  	switch (sinfo->what) {

  	case XT_CONNBYTES_PKTS:

  		switch (sinfo->direction) {

  		case XT_CONNBYTES_DIR_ORIGINAL:

  			what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);

  			break;

  		case XT_CONNBYTES_DIR_REPLY:

  			what = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);

  			break;

  		case XT_CONNBYTES_DIR_BOTH:

  			what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
  			what += atomic64_read(&counters[IP_CT_DIR_REPLY].packets);

  			break;
  		}
  		break;

  	case XT_CONNBYTES_BYTES:

  		switch (sinfo->direction) {

  		case XT_CONNBYTES_DIR_ORIGINAL:

  			what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);

  			break;

  		case XT_CONNBYTES_DIR_REPLY:

  			what = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);

  			break;

  		case XT_CONNBYTES_DIR_BOTH:

  			what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
  			what += atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);

  			break;
  		}
  		break;

  	case XT_CONNBYTES_AVGPKT:

  		switch (sinfo->direction) {

  		case XT_CONNBYTES_DIR_ORIGINAL:

  			bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
  			pkts  = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);

  			break;

  		case XT_CONNBYTES_DIR_REPLY:

  			bytes = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
  			pkts  = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);

  			break;

  		case XT_CONNBYTES_DIR_BOTH:

  			bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes) +
  				atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
  			pkts  = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets) +
  				atomic64_read(&counters[IP_CT_DIR_REPLY].packets);

  			break;
  		}

  		if (pkts != 0)

  			what = div64_u64(bytes, pkts);

  		break;
  	}

  	if (sinfo->count.to >= sinfo->count.from)

  		return what <= sinfo->count.to && what >= sinfo->count.from;

  	else /* inverted */
  		return what < sinfo->count.to || what > sinfo->count.from;

  }

  static int connbytes_mt_check(const struct xt_mtchk_param *par)

  {

  	const struct xt_connbytes_info *sinfo = par->matchinfo;

  	int ret;

  	if (sinfo->what != XT_CONNBYTES_PKTS &&
  	    sinfo->what != XT_CONNBYTES_BYTES &&
  	    sinfo->what != XT_CONNBYTES_AVGPKT)

  		return -EINVAL;

  	if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
  	    sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
  	    sinfo->direction != XT_CONNBYTES_DIR_BOTH)

  		return -EINVAL;

  	ret = nf_ct_netns_get(par->net, par->family);

  	if (ret < 0)

  		pr_info_ratelimited("cannot load conntrack support for proto=%u
  ",
  				    par->family);

  
  	/*
  	 * This filter cannot function correctly unless connection tracking
  	 * accounting is enabled, so complain in the hope that someone notices.
  	 */
  	if (!nf_ct_acct_enabled(par->net)) {

  		pr_warn("Forcing CT accounting to be enabled
  ");

  		nf_ct_set_acct(par->net, true);
  	}

  	return ret;

  }

  static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)

  {

  	nf_ct_netns_put(par->net, par->family);

  }

  static struct xt_match connbytes_mt_reg __read_mostly = {
  	.name       = "connbytes",
  	.revision   = 0,
  	.family     = NFPROTO_UNSPEC,
  	.checkentry = connbytes_mt_check,
  	.match      = connbytes_mt,
  	.destroy    = connbytes_mt_destroy,
  	.matchsize  = sizeof(struct xt_connbytes_info),
  	.me         = THIS_MODULE,

  };

  static int __init connbytes_mt_init(void)

  {

  	return xt_register_match(&connbytes_mt_reg);

  }

  static void __exit connbytes_mt_exit(void)

  {

  	xt_unregister_match(&connbytes_mt_reg);

  }

  module_init(connbytes_mt_init);
  module_exit(connbytes_mt_exit);