/*
   * Copyright (C)2003,2004 USAGI/WIDE Project
   *
   * Header for use in defining a given L3 protocol for connection tracking.
   *
   * Author:
   *	Yasuyuki Kozakai @USAGI	<yasuyuki.kozakai@toshiba.co.jp>
   *
   * Derived from include/netfilter_ipv4/ip_conntrack_protocol.h
   */
  
  #ifndef _NF_CONNTRACK_L3PROTO_H
  #define _NF_CONNTRACK_L3PROTO_H

  #include <linux/netlink.h>

  #include <net/netlink.h>

  #include <linux/seq_file.h>
  #include <net/netfilter/nf_conntrack.h>

  struct nf_conntrack_l3proto {

  	/* L3 Protocol Family number. ex) PF_INET */
  	u_int16_t l3proto;
  
  	/* Protocol name */
  	const char *name;
  
  	/*
  	 * Try to fill in the third arg: nhoff is offset of l3 proto
           * hdr.  Return true if possible.
  	 */

  	bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int nhoff,
  			     struct nf_conntrack_tuple *tuple);

  
  	/*
  	 * Invert the per-proto part of the tuple: ie. turn xmit into reply.
  	 * Some packets can't be inverted: return 0 in that case.
  	 */

  	bool (*invert_tuple)(struct nf_conntrack_tuple *inverse,
  			     const struct nf_conntrack_tuple *orig);

  
  	/* Print out the per-protocol part of the tuple. */
  	int (*print_tuple)(struct seq_file *s,
  			   const struct nf_conntrack_tuple *);

  	/*
  	 * Called before tracking. 

  	 *	*dataoff: offset of protocol header (TCP, UDP,...) in skb

  	 *	*protonum: protocol number
  	 */

  	int (*get_l4proto)(const struct sk_buff *skb, unsigned int nhoff,
  			   unsigned int *dataoff, u_int8_t *protonum);

  	int (*tuple_to_nlattr)(struct sk_buff *skb,

  			       const struct nf_conntrack_tuple *t);

  	/*
  	 * Calculate size of tuple nlattr
  	 */
  	int (*nlattr_tuple_size)(void);

  	int (*nlattr_to_tuple)(struct nlattr *tb[],

  			       struct nf_conntrack_tuple *t);

  	const struct nla_policy *nla_policy;

  	size_t nla_size;

  #ifdef CONFIG_SYSCTL
  	struct ctl_table_header	*ctl_table_header;

  	struct ctl_path		*ctl_table_path;

  	struct ctl_table	*ctl_table;
  #endif /* CONFIG_SYSCTL */

  	/* Module (if any) which this is connected to. */
  	struct module *me;
  };

  extern struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX];

  
  /* Protocol registration. */
  extern int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto);

  extern void nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto);

  extern struct nf_conntrack_l3proto *nf_ct_l3proto_find_get(u_int16_t l3proto);

  extern void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p);

  /* Existing built-in protocols */

  extern struct nf_conntrack_l3proto nf_conntrack_l3proto_generic;

  
  static inline struct nf_conntrack_l3proto *
  __nf_ct_l3proto_find(u_int16_t l3proto)
  {
  	if (unlikely(l3proto >= AF_MAX))

  		return &nf_conntrack_l3proto_generic;

  	return rcu_dereference(nf_ct_l3protos[l3proto]);

  }

  #endif /*_NF_CONNTRACK_L3PROTO_H*/