text: #ifndef _IP_CONNTRACK_TUPLE_H
  #define _IP_CONNTRACK_TUPLE_H
  
  /* A `tuple' is a structure containing the information to uniquely
    identify a connection.  ie. if two packets have the same tuple, they
    are in the same connection; if not, they are not.
  
    We divide the structure along "manipulatable" and
    "non-manipulatable" lines, for the benefit of the NAT code.
  */
  
  /* The protocol-specific manipulable parts of the tuple: always in
     network order! */
  union ip_conntrack_manip_proto
  {
  	/* Add other protocols here. */
  	u_int32_t all;
  
  	struct {
  		u_int16_t port;
  	} tcp;
  	struct {
  		u_int16_t port;
  	} udp;
  	struct {
  		u_int16_t id;
  	} icmp;
  	struct {
  		u_int32_t key;
  	} gre;
    struct {
      u_int32_t spi;
    } esp;
  };
  
  /* The manipulable part of the tuple. */
  struct ip_conntrack_manip
  {
  	u_int32_t ip;
  	union ip_conntrack_manip_proto u;
  };
  
  /* This contains the information to distinguish a connection. */
  struct ip_conntrack_tuple
  {
  	struct ip_conntrack_manip src;
  
  	/* These are the parts of the tuple which are fixed. */
  	struct {
  		u_int32_t ip;
  		union {
  			/* Add other protocols here. */
  			u_int64_t all;
  
  			struct {
  				u_int16_t port;
  			} tcp;
  			struct {
  				u_int16_t port;
  			} udp;
  			struct {
  				u_int8_t type, code;
  			} icmp;
  			struct {
  				u_int16_t protocol;
  				u_int8_t version;
  				u_int32_t key;
  			} gre;
  			struct {
  			   u_int32_t spi;
  			} esp;
  		} u;
  
  		/* The protocol. */
  		u_int16_t protonum;
  	} dst;
  };
  
  enum ip_conntrack_dir
  {
  	IP_CT_DIR_ORIGINAL,
  	IP_CT_DIR_REPLY,
  	IP_CT_DIR_MAX
  };
  
  #ifdef __KERNEL__
  
  #define DUMP_TUPLE(tp)						\
  DEBUGP("tuple %p: %u %u.%u.%u.%u:%u -> %u.%u.%u.%u:%u\n",	\
         (tp), (tp)->dst.protonum,				\
         NIPQUAD((tp)->src.ip), ntohl((tp)->src.u.all),		\
         NIPQUAD((tp)->dst.ip), ntohl((tp)->dst.u.all))
  
  #define DUMP_TUPLE_RAW(x) 						\
  	DEBUGP("tuple %p: %u %u.%u.%u.%u:0x%08x -> %u.%u.%u.%u:0x%08x\n",\
  	(x), (x)->dst.protonum,						\
  	NIPQUAD((x)->src.ip), ntohl((x)->src.u.all), 			\
  	NIPQUAD((x)->dst.ip), ntohl((x)->dst.u.all))
  
  #define CTINFO2DIR(ctinfo) ((ctinfo) >= IP_CT_IS_REPLY ? IP_CT_DIR_REPLY : IP_CT_DIR_ORIGINAL)
  
  /* If we're the first tuple, it's the original dir. */
  #define DIRECTION(h) ((enum ip_conntrack_dir)(&(h)->ctrack->tuplehash[1] == (h)))
  
  /* Connections have two entries in the hash table: one for each way */
  struct ip_conntrack_tuple_hash
  {
  	struct list_head list;
  
  	struct ip_conntrack_tuple tuple;
  
  	/* this == &ctrack->tuplehash[DIRECTION(this)]. */
  	struct ip_conntrack *ctrack;
  };
  
  #endif /* __KERNEL__ */
  
  static inline int ip_ct_tuple_src_equal(const struct ip_conntrack_tuple *t1,
  				        const struct ip_conntrack_tuple *t2)
  {
  	return t1->src.ip == t2->src.ip
  		&& t1->src.u.all == t2->src.u.all;
  }
  
  static inline int ip_ct_tuple_dst_equal(const struct ip_conntrack_tuple *t1,
  				        const struct ip_conntrack_tuple *t2)
  {
  	return t1->dst.ip == t2->dst.ip
  		&& t1->dst.u.all == t2->dst.u.all
  		&& t1->dst.protonum == t2->dst.protonum;
  }
  
  static inline int ip_ct_tuple_equal(const struct ip_conntrack_tuple *t1,
  				    const struct ip_conntrack_tuple *t2)
  {
  	return ip_ct_tuple_src_equal(t1, t2) && ip_ct_tuple_dst_equal(t1, t2);
  }
  
  static inline int ip_ct_tuple_mask_cmp(const struct ip_conntrack_tuple *t,
  				       const struct ip_conntrack_tuple *tuple,
  				       const struct ip_conntrack_tuple *mask)
  {
  	return !(((t->src.ip ^ tuple->src.ip) & mask->src.ip)
  		 || ((t->dst.ip ^ tuple->dst.ip) & mask->dst.ip)
  		 || ((t->src.u.all ^ tuple->src.u.all) & mask->src.u.all)
  		 || ((t->dst.u.all ^ tuple->dst.u.all) & mask->dst.u.all)
  		 || ((t->dst.protonum ^ tuple->dst.protonum)
  		     & mask->dst.protonum));
  }
  
  #endif /* _IP_CONNTRACK_TUPLE_H */
  