text: /*
   * linux/include/linux/sunrpc/svc_xprt.h
   *
   * RPC server transport I/O
   */
  
  #ifndef SUNRPC_SVC_XPRT_H
  #define SUNRPC_SVC_XPRT_H
  
  #include <linux/sunrpc/svc.h>
  
  struct module;
  
  struct svc_xprt_ops {
  	struct svc_xprt	*(*xpo_create)(struct svc_serv *,
  				       struct net *net,
  				       struct sockaddr *, int,
  				       int);
  	struct svc_xprt	*(*xpo_accept)(struct svc_xprt *);
  	int		(*xpo_has_wspace)(struct svc_xprt *);
  	int		(*xpo_recvfrom)(struct svc_rqst *);
  	void		(*xpo_prep_reply_hdr)(struct svc_rqst *);
  	int		(*xpo_sendto)(struct svc_rqst *);
  	void		(*xpo_release_rqst)(struct svc_rqst *);
  	void		(*xpo_detach)(struct svc_xprt *);
  	void		(*xpo_free)(struct svc_xprt *);
  	int		(*xpo_secure_port)(struct svc_rqst *);
  	void		(*xpo_adjust_wspace)(struct svc_xprt *);
  };
  
  struct svc_xprt_class {
  	const char		*xcl_name;
  	struct module		*xcl_owner;
  	struct svc_xprt_ops	*xcl_ops;
  	struct list_head	xcl_list;
  	u32			xcl_max_payload;
  	int			xcl_ident;
  };
  
  /*
   * This is embedded in an object that wants a callback before deleting
   * an xprt; intended for use by NFSv4.1, which needs to know when a
   * client's tcp connection (and hence possibly a backchannel) goes away.
   */
  struct svc_xpt_user {
  	struct list_head list;
  	void (*callback)(struct svc_xpt_user *);
  };
  
  struct svc_xprt {
  	struct svc_xprt_class	*xpt_class;
  	struct svc_xprt_ops	*xpt_ops;
  	struct kref		xpt_ref;
  	struct list_head	xpt_list;
  	struct list_head	xpt_ready;
  	unsigned long		xpt_flags;
  #define	XPT_BUSY	0		/* enqueued/receiving */
  #define	XPT_CONN	1		/* conn pending */
  #define	XPT_CLOSE	2		/* dead or dying */
  #define	XPT_DATA	3		/* data pending */
  #define	XPT_TEMP	4		/* connected transport */
  #define	XPT_DEAD	6		/* transport closed */
  #define	XPT_CHNGBUF	7		/* need to change snd/rcv buf sizes */
  #define	XPT_DEFERRED	8		/* deferred request pending */
  #define	XPT_OLD		9		/* used for xprt aging mark+sweep */
  #define XPT_LISTENER	10		/* listening endpoint */
  #define XPT_CACHE_AUTH	11		/* cache auth info */
  #define XPT_LOCAL	12		/* connection from loopback interface */
  
  	struct svc_serv		*xpt_server;	/* service for transport */
  	atomic_t    	    	xpt_reserved;	/* space on outq that is rsvd */
  	struct mutex		xpt_mutex;	/* to serialize sending data */
  	spinlock_t		xpt_lock;	/* protects sk_deferred
  						 * and xpt_auth_cache */
  	void			*xpt_auth_cache;/* auth cache */
  	struct list_head	xpt_deferred;	/* deferred requests that need
  						 * to be revisted */
  	struct sockaddr_storage	xpt_local;	/* local address */
  	size_t			xpt_locallen;	/* length of address */
  	struct sockaddr_storage	xpt_remote;	/* remote peer's address */
  	size_t			xpt_remotelen;	/* length of address */
  	struct rpc_wait_queue	xpt_bc_pending;	/* backchannel wait queue */
  	struct list_head	xpt_users;	/* callbacks on free */
  
  	struct net		*xpt_net;
  	struct rpc_xprt		*xpt_bc_xprt;	/* NFSv4.1 backchannel */
  };
  
  static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)
  {
  	spin_lock(&xpt->xpt_lock);
  	list_del_init(&u->list);
  	spin_unlock(&xpt->xpt_lock);
  }
  
  static inline int register_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)
  {
  	spin_lock(&xpt->xpt_lock);
  	if (test_bit(XPT_CLOSE, &xpt->xpt_flags)) {
  		/*
  		 * The connection is about to be deleted soon (or,
  		 * worse, may already be deleted--in which case we've
  		 * already notified the xpt_users).
  		 */
  		spin_unlock(&xpt->xpt_lock);
  		return -ENOTCONN;
  	}
  	list_add(&u->list, &xpt->xpt_users);
  	spin_unlock(&xpt->xpt_lock);
  	return 0;
  }
  
  int	svc_reg_xprt_class(struct svc_xprt_class *);
  void	svc_unreg_xprt_class(struct svc_xprt_class *);
  void	svc_xprt_init(struct net *, struct svc_xprt_class *, struct svc_xprt *,
  		      struct svc_serv *);
  int	svc_create_xprt(struct svc_serv *, const char *, struct net *,
  			const int, const unsigned short, int);
  void	svc_xprt_do_enqueue(struct svc_xprt *xprt);
  void	svc_xprt_enqueue(struct svc_xprt *xprt);
  void	svc_xprt_put(struct svc_xprt *xprt);
  void	svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt);
  void	svc_close_xprt(struct svc_xprt *xprt);
  int	svc_port_is_privileged(struct sockaddr *sin);
  int	svc_print_xprts(char *buf, int maxlen);
  struct	svc_xprt *svc_find_xprt(struct svc_serv *serv, const char *xcl_name,
  			struct net *net, const sa_family_t af,
  			const unsigned short port);
  int	svc_xprt_names(struct svc_serv *serv, char *buf, const int buflen);
  void	svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *xprt);
  void	svc_age_temp_xprts_now(struct svc_serv *, struct sockaddr *);
  
  static inline void svc_xprt_get(struct svc_xprt *xprt)
  {
  	kref_get(&xprt->xpt_ref);
  }
  static inline void svc_xprt_set_local(struct svc_xprt *xprt,
  				      const struct sockaddr *sa,
  				      const size_t salen)
  {
  	memcpy(&xprt->xpt_local, sa, salen);
  	xprt->xpt_locallen = salen;
  }
  static inline void svc_xprt_set_remote(struct svc_xprt *xprt,
  				       const struct sockaddr *sa,
  				       const size_t salen)
  {
  	memcpy(&xprt->xpt_remote, sa, salen);
  	xprt->xpt_remotelen = salen;
  }
  static inline unsigned short svc_addr_port(const struct sockaddr *sa)
  {
  	const struct sockaddr_in *sin = (const struct sockaddr_in *)sa;
  	const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)sa;
  
  	switch (sa->sa_family) {
  	case AF_INET:
  		return ntohs(sin->sin_port);
  	case AF_INET6:
  		return ntohs(sin6->sin6_port);
  	}
  
  	return 0;
  }
  
  static inline size_t svc_addr_len(const struct sockaddr *sa)
  {
  	switch (sa->sa_family) {
  	case AF_INET:
  		return sizeof(struct sockaddr_in);
  	case AF_INET6:
  		return sizeof(struct sockaddr_in6);
  	}
  	BUG();
  }
  
  static inline unsigned short svc_xprt_local_port(const struct svc_xprt *xprt)
  {
  	return svc_addr_port((const struct sockaddr *)&xprt->xpt_local);
  }
  
  static inline unsigned short svc_xprt_remote_port(const struct svc_xprt *xprt)
  {
  	return svc_addr_port((const struct sockaddr *)&xprt->xpt_remote);
  }
  
  static inline char *__svc_print_addr(const struct sockaddr *addr,
  				     char *buf, const size_t len)
  {
  	const struct sockaddr_in *sin = (const struct sockaddr_in *)addr;
  	const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)addr;
  
  	switch (addr->sa_family) {
  	case AF_INET:
  		snprintf(buf, len, "%pI4, port=%u", &sin->sin_addr,
  			ntohs(sin->sin_port));
  		break;
  
  	case AF_INET6:
  		snprintf(buf, len, "%pI6, port=%u",
  			 &sin6->sin6_addr,
  			ntohs(sin6->sin6_port));
  		break;
  
  	default:
  		snprintf(buf, len, "unknown address type: %d", addr->sa_family);
  		break;
  	}
  
  	return buf;
  }
  #endif /* SUNRPC_SVC_XPRT_H */
  