text: /*
   * 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/seq_file.h>
  #include <net/netfilter/nf_conntrack.h>
  
  struct nfattr;
  
  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.
  	 */
  	int (*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.
  	 */
  	int (*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 *);
  
  	/* Returns verdict for packet, or -1 for invalid. */
  	int (*packet)(struct nf_conn *conntrack,
  		      const struct sk_buff *skb,
  		      enum ip_conntrack_info ctinfo);
  
  	/*
  	 * Called when a new connection for this protocol found;
  	 * returns TRUE if it's OK.  If so, packet() called next.
  	 */
  	int (*new)(struct nf_conn *conntrack, const struct sk_buff *skb);
  
  	/*
  	 * Called before tracking. 
  	 *	*dataoff: offset of protocol header (TCP, UDP,...) in *pskb
  	 *	*protonum: protocol number
  	 */
  	int (*prepare)(struct sk_buff **pskb, unsigned int hooknum,
  		       unsigned int *dataoff, u_int8_t *protonum);
  
  	u_int32_t (*get_features)(const struct nf_conntrack_tuple *tuple);
  
  	int (*tuple_to_nfattr)(struct sk_buff *skb,
  			       const struct nf_conntrack_tuple *t);
  
  	int (*nfattr_to_tuple)(struct nfattr *tb[],
  			       struct nf_conntrack_tuple *t);
  
  #ifdef CONFIG_SYSCTL
  	struct ctl_table_header	*ctl_table_header;
  	struct ctl_table	*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 *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_ipv4;
  extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6;
  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*/
  