/* SPDX-License-Identifier: GPL-2.0-only */

  #ifndef _CCID_H
  #define _CCID_H
  /*
   *  net/dccp/ccid.h
   *
   *  An implementation of the DCCP protocol
   *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *
   *  CCID infrastructure

   */
  
  #include <net/sock.h>

  #include <linux/compiler.h>

  #include <linux/dccp.h>
  #include <linux/list.h>
  #include <linux/module.h>

  /* maximum value for a CCID (RFC 4340, 19.5) */
  #define CCID_MAX		255
  #define CCID_SLAB_NAME_LENGTH	32

  struct tcp_info;

  /**
   *  struct ccid_operations  -  Interface to Congestion-Control Infrastructure
   *
   *  @ccid_id: numerical CCID ID (up to %CCID_MAX, cf. table 5 in RFC 4340, 10.)

   *  @ccid_ccmps: the CCMPS including network/transport headers (0 when disabled)

   *  @ccid_name: alphabetical identifier string for @ccid_id

   *  @ccid_hc_{r,t}x_slab: memory pool for the receiver/sender half-connection
   *  @ccid_hc_{r,t}x_obj_size: size of the receiver/sender half-connection socket
   *
   *  @ccid_hc_{r,t}x_init: CCID-specific initialisation routine (before startup)
   *  @ccid_hc_{r,t}x_exit: CCID-specific cleanup routine (before destruction)
   *  @ccid_hc_rx_packet_recv: implements the HC-receiver side
   *  @ccid_hc_{r,t}x_parse_options: parsing routine for CCID/HC-specific options
   *  @ccid_hc_{r,t}x_insert_options: insert routine for CCID/HC-specific options
   *  @ccid_hc_tx_packet_recv: implements feedback processing for the HC-sender
   *  @ccid_hc_tx_send_packet: implements the sending part of the HC-sender
   *  @ccid_hc_tx_packet_sent: does accounting for packets in flight by HC-sender
   *  @ccid_hc_{r,t}x_get_info: INET_DIAG information for HC-receiver/sender
   *  @ccid_hc_{r,t}x_getsockopt: socket options specific to HC-receiver/sender
   */

  struct ccid_operations {

  	unsigned char		ccid_id;

  	__u32			ccid_ccmps;

  	const char		*ccid_name;

  	struct kmem_cache	*ccid_hc_rx_slab,
  				*ccid_hc_tx_slab;

  	char			ccid_hc_rx_slab_name[CCID_SLAB_NAME_LENGTH];
  	char			ccid_hc_tx_slab_name[CCID_SLAB_NAME_LENGTH];

  	__u32			ccid_hc_rx_obj_size,
  				ccid_hc_tx_obj_size;
  	/* Interface Routines */

  	int		(*ccid_hc_rx_init)(struct ccid *ccid, struct sock *sk);
  	int		(*ccid_hc_tx_init)(struct ccid *ccid, struct sock *sk);

  	void		(*ccid_hc_rx_exit)(struct sock *sk);
  	void		(*ccid_hc_tx_exit)(struct sock *sk);

  	void		(*ccid_hc_rx_packet_recv)(struct sock *sk,
  						  struct sk_buff *skb);

  	int		(*ccid_hc_rx_parse_options)(struct sock *sk, u8 pkt,
  						    u8 opt, u8 *val, u8 len);

  	int		(*ccid_hc_rx_insert_options)(struct sock *sk,

  						     struct sk_buff *skb);

  	void		(*ccid_hc_tx_packet_recv)(struct sock *sk,
  						  struct sk_buff *skb);

  	int		(*ccid_hc_tx_parse_options)(struct sock *sk, u8 pkt,
  						    u8 opt, u8 *val, u8 len);

  	int		(*ccid_hc_tx_send_packet)(struct sock *sk,

  						  struct sk_buff *skb);
  	void		(*ccid_hc_tx_packet_sent)(struct sock *sk,

  						  unsigned int len);

  	void		(*ccid_hc_rx_get_info)(struct sock *sk,
  					       struct tcp_info *info);
  	void		(*ccid_hc_tx_get_info)(struct sock *sk,
  					       struct tcp_info *info);

  	int		(*ccid_hc_rx_getsockopt)(struct sock *sk,
  						 const int optname, int len,
  						 u32 __user *optval,
  						 int __user *optlen);
  	int		(*ccid_hc_tx_getsockopt)(struct sock *sk,
  						 const int optname, int len,
  						 u32 __user *optval,
  						 int __user *optlen);

  };

  extern struct ccid_operations ccid2_ops;
  #ifdef CONFIG_IP_DCCP_CCID3
  extern struct ccid_operations ccid3_ops;
  #endif

  int ccid_initialize_builtins(void);
  void ccid_cleanup_builtins(void);

  struct ccid {
  	struct ccid_operations *ccid_ops;
  	char		       ccid_priv[0];
  };

  static inline void *ccid_priv(const struct ccid *ccid)

  {

  	return (void *)ccid->ccid_priv;

  }

  bool ccid_support_check(u8 const *ccid_array, u8 array_len);
  int ccid_get_builtin_ccids(u8 **ccid_array, u8 *array_len);
  int ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
  				  char __user *, int __user *);

  struct ccid *ccid_new(const u8 id, struct sock *sk, bool rx);

  static inline int ccid_get_current_rx_ccid(struct dccp_sock *dp)
  {
  	struct ccid *ccid = dp->dccps_hc_rx_ccid;
  
  	if (ccid == NULL || ccid->ccid_ops == NULL)
  		return -1;
  	return ccid->ccid_ops->ccid_id;
  }
  
  static inline int ccid_get_current_tx_ccid(struct dccp_sock *dp)
  {
  	struct ccid *ccid = dp->dccps_hc_tx_ccid;
  
  	if (ccid == NULL || ccid->ccid_ops == NULL)
  		return -1;
  	return ccid->ccid_ops->ccid_id;
  }

  void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk);
  void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk);

  /*
   * Congestion control of queued data packets via CCID decision.
   *
   * The TX CCID performs its congestion-control by indicating whether and when a
   * queued packet may be sent, using the return code of ccid_hc_tx_send_packet().
   * The following modes are supported via the symbolic constants below:
   * - timer-based pacing    (CCID returns a delay value in milliseconds);
   * - autonomous dequeueing (CCID internally schedules dccps_xmitlet).
   */
  
  enum ccid_dequeueing_decision {
  	CCID_PACKET_SEND_AT_ONCE =	 0x00000,  /* "green light": no delay */
  	CCID_PACKET_DELAY_MAX =		 0x0FFFF,  /* maximum delay in msecs  */
  	CCID_PACKET_DELAY =		 0x10000,  /* CCID msec-delay mode */
  	CCID_PACKET_WILL_DEQUEUE_LATER = 0x20000,  /* CCID autonomous mode */
  	CCID_PACKET_ERR =		 0xF0000,  /* error condition */
  };
  
  static inline int ccid_packet_dequeue_eval(const int return_code)
  {
  	if (return_code < 0)
  		return CCID_PACKET_ERR;
  	if (return_code == 0)
  		return CCID_PACKET_SEND_AT_ONCE;
  	if (return_code <= CCID_PACKET_DELAY_MAX)
  		return CCID_PACKET_DELAY;
  	return return_code;
  }

  static inline int ccid_hc_tx_send_packet(struct ccid *ccid, struct sock *sk,

  					 struct sk_buff *skb)

  {

  	if (ccid->ccid_ops->ccid_hc_tx_send_packet != NULL)

  		return ccid->ccid_ops->ccid_hc_tx_send_packet(sk, skb);
  	return CCID_PACKET_SEND_AT_ONCE;

  }
  
  static inline void ccid_hc_tx_packet_sent(struct ccid *ccid, struct sock *sk,

  					  unsigned int len)

  {

  	if (ccid->ccid_ops->ccid_hc_tx_packet_sent != NULL)

  		ccid->ccid_ops->ccid_hc_tx_packet_sent(sk, len);

  }
  
  static inline void ccid_hc_rx_packet_recv(struct ccid *ccid, struct sock *sk,
  					  struct sk_buff *skb)
  {

  	if (ccid->ccid_ops->ccid_hc_rx_packet_recv != NULL)
  		ccid->ccid_ops->ccid_hc_rx_packet_recv(sk, skb);

  }
  
  static inline void ccid_hc_tx_packet_recv(struct ccid *ccid, struct sock *sk,
  					  struct sk_buff *skb)
  {

  	if (ccid->ccid_ops->ccid_hc_tx_packet_recv != NULL)
  		ccid->ccid_ops->ccid_hc_tx_packet_recv(sk, skb);

  }

  /**
   * ccid_hc_tx_parse_options  -  Parse CCID-specific options sent by the receiver
   * @pkt: type of packet that @opt appears on (RFC 4340, 5.1)
   * @opt: the CCID-specific option type (RFC 4340, 5.8 and 10.3)
   * @val: value of @opt
   * @len: length of @val in bytes
   */

  static inline int ccid_hc_tx_parse_options(struct ccid *ccid, struct sock *sk,

  					   u8 pkt, u8 opt, u8 *val, u8 len)

  {

  	if (!ccid || !ccid->ccid_ops->ccid_hc_tx_parse_options)

  		return 0;
  	return ccid->ccid_ops->ccid_hc_tx_parse_options(sk, pkt, opt, val, len);

  }

  /**
   * ccid_hc_rx_parse_options  -  Parse CCID-specific options sent by the sender
   * Arguments are analogous to ccid_hc_tx_parse_options()
   */

  static inline int ccid_hc_rx_parse_options(struct ccid *ccid, struct sock *sk,

  					   u8 pkt, u8 opt, u8 *val, u8 len)

  {

  	if (!ccid || !ccid->ccid_ops->ccid_hc_rx_parse_options)

  		return 0;
  	return ccid->ccid_ops->ccid_hc_rx_parse_options(sk, pkt, opt, val, len);

  }

  static inline int ccid_hc_rx_insert_options(struct ccid *ccid, struct sock *sk,
  					    struct sk_buff *skb)

  {

  	if (ccid->ccid_ops->ccid_hc_rx_insert_options != NULL)

  		return ccid->ccid_ops->ccid_hc_rx_insert_options(sk, skb);
  	return 0;

  }

  
  static inline void ccid_hc_rx_get_info(struct ccid *ccid, struct sock *sk,
  				       struct tcp_info *info)
  {

  	if (ccid->ccid_ops->ccid_hc_rx_get_info != NULL)
  		ccid->ccid_ops->ccid_hc_rx_get_info(sk, info);

  }
  
  static inline void ccid_hc_tx_get_info(struct ccid *ccid, struct sock *sk,
  				       struct tcp_info *info)
  {

  	if (ccid->ccid_ops->ccid_hc_tx_get_info != NULL)
  		ccid->ccid_ops->ccid_hc_tx_get_info(sk, info);

  }

  
  static inline int ccid_hc_rx_getsockopt(struct ccid *ccid, struct sock *sk,
  					const int optname, int len,
  					u32 __user *optval, int __user *optlen)
  {
  	int rc = -ENOPROTOOPT;

  	if (ccid != NULL && ccid->ccid_ops->ccid_hc_rx_getsockopt != NULL)

  		rc = ccid->ccid_ops->ccid_hc_rx_getsockopt(sk, optname, len,

  						 optval, optlen);
  	return rc;
  }
  
  static inline int ccid_hc_tx_getsockopt(struct ccid *ccid, struct sock *sk,
  					const int optname, int len,
  					u32 __user *optval, int __user *optlen)
  {
  	int rc = -ENOPROTOOPT;

  	if (ccid != NULL && ccid->ccid_ops->ccid_hc_tx_getsockopt != NULL)

  		rc = ccid->ccid_ops->ccid_hc_tx_getsockopt(sk, optname, len,

  						 optval, optlen);
  	return rc;
  }

  #endif /* _CCID_H */