/* SPDX-License-Identifier: GPL-2.0 */
  /* Multipath TCP
   *
   * Copyright (c) 2017 - 2019, Intel Corporation.
   */
  
  #ifndef __MPTCP_PROTOCOL_H
  #define __MPTCP_PROTOCOL_H

  #include <linux/random.h>
  #include <net/tcp.h>
  #include <net/inet_connection_sock.h>

  #define MPTCP_SUPPORTED_VERSION	1

  
  /* MPTCP option bits */
  #define OPTION_MPTCP_MPC_SYN	BIT(0)
  #define OPTION_MPTCP_MPC_SYNACK	BIT(1)
  #define OPTION_MPTCP_MPC_ACK	BIT(2)

  #define OPTION_MPTCP_MPJ_SYN	BIT(3)
  #define OPTION_MPTCP_MPJ_SYNACK	BIT(4)
  #define OPTION_MPTCP_MPJ_ACK	BIT(5)

  #define OPTION_MPTCP_ADD_ADDR	BIT(6)
  #define OPTION_MPTCP_ADD_ADDR6	BIT(7)
  #define OPTION_MPTCP_RM_ADDR	BIT(8)

  
  /* MPTCP option subtypes */
  #define MPTCPOPT_MP_CAPABLE	0
  #define MPTCPOPT_MP_JOIN	1
  #define MPTCPOPT_DSS		2
  #define MPTCPOPT_ADD_ADDR	3
  #define MPTCPOPT_RM_ADDR	4
  #define MPTCPOPT_MP_PRIO	5
  #define MPTCPOPT_MP_FAIL	6
  #define MPTCPOPT_MP_FASTCLOSE	7
  
  /* MPTCP suboption lengths */

  #define TCPOLEN_MPTCP_MPC_SYN		4

  #define TCPOLEN_MPTCP_MPC_SYNACK	12
  #define TCPOLEN_MPTCP_MPC_ACK		20

  #define TCPOLEN_MPTCP_MPC_ACK_DATA	22

  #define TCPOLEN_MPTCP_MPJ_SYN		12
  #define TCPOLEN_MPTCP_MPJ_SYNACK	16
  #define TCPOLEN_MPTCP_MPJ_ACK		24

  #define TCPOLEN_MPTCP_DSS_BASE		4

  #define TCPOLEN_MPTCP_DSS_ACK32		4

  #define TCPOLEN_MPTCP_DSS_ACK64		8

  #define TCPOLEN_MPTCP_DSS_MAP32		10

  #define TCPOLEN_MPTCP_DSS_MAP64		14
  #define TCPOLEN_MPTCP_DSS_CHECKSUM	2

  #define TCPOLEN_MPTCP_ADD_ADDR		16
  #define TCPOLEN_MPTCP_ADD_ADDR_PORT	18
  #define TCPOLEN_MPTCP_ADD_ADDR_BASE	8
  #define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT	10
  #define TCPOLEN_MPTCP_ADD_ADDR6		28
  #define TCPOLEN_MPTCP_ADD_ADDR6_PORT	30
  #define TCPOLEN_MPTCP_ADD_ADDR6_BASE	20
  #define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT	22
  #define TCPOLEN_MPTCP_PORT_LEN		2
  #define TCPOLEN_MPTCP_RM_ADDR_BASE	4

  /* MPTCP MP_JOIN flags */

  #define MPTCPOPT_BACKUP		BIT(0)
  #define MPTCPOPT_HMAC_LEN	20

  #define MPTCPOPT_THMAC_LEN	8

  /* MPTCP MP_CAPABLE flags */
  #define MPTCP_VERSION_MASK	(0x0F)
  #define MPTCP_CAP_CHECKSUM_REQD	BIT(7)
  #define MPTCP_CAP_EXTENSIBILITY	BIT(6)

  #define MPTCP_CAP_HMAC_SHA256	BIT(0)

  #define MPTCP_CAP_FLAG_MASK	(0x3F)

  /* MPTCP DSS flags */
  #define MPTCP_DSS_DATA_FIN	BIT(4)
  #define MPTCP_DSS_DSN64		BIT(3)
  #define MPTCP_DSS_HAS_MAP	BIT(2)
  #define MPTCP_DSS_ACK64		BIT(1)
  #define MPTCP_DSS_HAS_ACK	BIT(0)

  #define MPTCP_DSS_FLAG_MASK	(0x1F)

  /* MPTCP ADD_ADDR flags */
  #define MPTCP_ADDR_ECHO		BIT(0)
  #define MPTCP_ADDR_HMAC_LEN	20
  #define MPTCP_ADDR_IPVERSION_4	4
  #define MPTCP_ADDR_IPVERSION_6	6

  /* MPTCP socket flags */

  #define MPTCP_DATA_READY	0
  #define MPTCP_SEND_SPACE	1

  #define MPTCP_WORK_RTX		2

  #define MPTCP_WORK_EOF		3

  static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
  {
  	return htonl((TCPOPT_MPTCP << 24) | (len << 16) | (subopt << 12) |
  		     ((nib & 0xF) << 8) | field);
  }

  #define MPTCP_PM_MAX_ADDR	4
  
  struct mptcp_addr_info {
  	sa_family_t		family;
  	__be16			port;
  	u8			id;
  	union {
  		struct in_addr addr;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  		struct in6_addr addr6;
  #endif
  	};
  };
  
  enum mptcp_pm_status {
  	MPTCP_PM_ADD_ADDR_RECEIVED,
  	MPTCP_PM_ESTABLISHED,
  	MPTCP_PM_SUBFLOW_ESTABLISHED,
  };
  
  struct mptcp_pm_data {
  	struct mptcp_addr_info local;
  	struct mptcp_addr_info remote;
  
  	spinlock_t	lock;		/*protects the whole PM data */
  
  	bool		addr_signal;
  	bool		server_side;
  	bool		work_pending;
  	bool		accept_addr;
  	bool		accept_subflow;
  	u8		add_addr_signaled;
  	u8		add_addr_accepted;
  	u8		local_addr_used;
  	u8		subflows;
  	u8		add_addr_signal_max;
  	u8		add_addr_accept_max;
  	u8		local_addr_max;
  	u8		subflows_max;
  	u8		status;
  
  	struct		work_struct work;
  };

  struct mptcp_data_frag {
  	struct list_head list;
  	u64 data_seq;
  	int data_len;
  	int offset;
  	int overhead;
  	struct page *page;
  };

  /* MPTCP connection sock */
  struct mptcp_sock {
  	/* inet_connection_sock must be the first member */
  	struct inet_connection_sock sk;

  	u64		local_key;
  	u64		remote_key;

  	u64		write_seq;
  	u64		ack_seq;

  	atomic64_t	snd_una;

  	unsigned long	timer_ival;

  	u32		token;

  	unsigned long	flags;

  	bool		can_ack;

  	spinlock_t	join_list_lock;

  	struct work_struct work;

  	struct list_head conn_list;

  	struct list_head rtx_queue;

  	struct list_head join_list;

  	struct skb_ext	*cached_ext;	/* for the next sendmsg */

  	struct socket	*subflow; /* outgoing connect/listener/!mp_capable */

  	struct sock	*first;

  	struct mptcp_pm_data	pm;

  };

  #define mptcp_for_each_subflow(__msk, __subflow)			\
  	list_for_each_entry(__subflow, &((__msk)->conn_list), node)

  static inline struct mptcp_sock *mptcp_sk(const struct sock *sk)
  {
  	return (struct mptcp_sock *)sk;
  }

  static inline struct mptcp_data_frag *mptcp_rtx_tail(const struct sock *sk)
  {
  	struct mptcp_sock *msk = mptcp_sk(sk);
  
  	if (list_empty(&msk->rtx_queue))
  		return NULL;
  
  	return list_last_entry(&msk->rtx_queue, struct mptcp_data_frag, list);
  }

  static inline struct mptcp_data_frag *mptcp_rtx_head(const struct sock *sk)
  {
  	struct mptcp_sock *msk = mptcp_sk(sk);
  
  	if (list_empty(&msk->rtx_queue))
  		return NULL;
  
  	return list_first_entry(&msk->rtx_queue, struct mptcp_data_frag, list);
  }

  struct mptcp_subflow_request_sock {
  	struct	tcp_request_sock sk;

  	u16	mp_capable : 1,

  		mp_join : 1,

  		backup : 1,
  		remote_key_valid : 1;

  	u8	local_id;

  	u8	remote_id;

  	u64	local_key;
  	u64	remote_key;

  	u64	idsn;
  	u32	token;

  	u32	ssn_offset;

  	u64	thmac;
  	u32	local_nonce;
  	u32	remote_nonce;

  };
  
  static inline struct mptcp_subflow_request_sock *
  mptcp_subflow_rsk(const struct request_sock *rsk)
  {
  	return (struct mptcp_subflow_request_sock *)rsk;
  }

  /* MPTCP subflow context */
  struct mptcp_subflow_context {

  	struct	list_head node;/* conn_list of subflows */
  	u64	local_key;
  	u64	remote_key;

  	u64	idsn;

  	u64	map_seq;

  	u32	snd_isn;

  	u32	token;

  	u32	rel_write_seq;

  	u32	map_subflow_seq;
  	u32	ssn_offset;
  	u32	map_data_len;

  	u32	request_mptcp : 1,  /* send MP_CAPABLE */

  		request_join : 1,   /* send MP_JOIN */
  		request_bkup : 1,

  		mp_capable : 1,	    /* remote is MPTCP capable */

  		mp_join : 1,	    /* remote is JOINing */

  		fully_established : 1,	    /* path validated */

  		pm_notified : 1,    /* PM hook called for established status */

  		conn_finished : 1,
  		map_valid : 1,

  		mpc_map : 1,

  		backup : 1,

  		data_avail : 1,

  		rx_eof : 1,

  		data_fin_tx_enable : 1,

  		can_ack : 1;	    /* only after processing the remote a key */

  	u64	data_fin_tx_seq;

  	u32	remote_nonce;
  	u64	thmac;
  	u32	local_nonce;

  	u32	remote_token;
  	u8	hmac[MPTCPOPT_HMAC_LEN];

  	u8	local_id;
  	u8	remote_id;

  	struct	sock *tcp_sock;	    /* tcp sk backpointer */
  	struct	sock *conn;	    /* parent mptcp_sock */

  	const	struct inet_connection_sock_af_ops *icsk_af_ops;

  	void	(*tcp_data_ready)(struct sock *sk);
  	void	(*tcp_state_change)(struct sock *sk);
  	void	(*tcp_write_space)(struct sock *sk);

  	struct	rcu_head rcu;
  };
  
  static inline struct mptcp_subflow_context *
  mptcp_subflow_ctx(const struct sock *sk)
  {
  	struct inet_connection_sock *icsk = inet_csk(sk);
  
  	/* Use RCU on icsk_ulp_data only for sock diag code */
  	return (__force struct mptcp_subflow_context *)icsk->icsk_ulp_data;
  }
  
  static inline struct sock *
  mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
  {
  	return subflow->tcp_sock;
  }

  static inline u64
  mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
  {
  	return tcp_sk(mptcp_subflow_tcp_sock(subflow))->copied_seq -
  		      subflow->ssn_offset -
  		      subflow->map_subflow_seq;
  }
  
  static inline u64
  mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
  {
  	return subflow->map_seq + mptcp_subflow_get_map_offset(subflow);
  }
  
  int mptcp_is_enabled(struct net *net);
  bool mptcp_subflow_data_available(struct sock *sk);

  void mptcp_subflow_init(void);

  
  /* called with sk socket lock held */
  int __mptcp_subflow_connect(struct sock *sk, int ifindex,
  			    const struct mptcp_addr_info *loc,
  			    const struct mptcp_addr_info *remote);

  int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock);

  static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
  					      struct mptcp_subflow_context *ctx)
  {
  	sk->sk_data_ready = ctx->tcp_data_ready;
  	sk->sk_state_change = ctx->tcp_state_change;
  	sk->sk_write_space = ctx->tcp_write_space;
  
  	inet_csk(sk)->icsk_af_ops = ctx->icsk_af_ops;
  }

  extern const struct inet_connection_sock_af_ops ipv4_specific;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  extern const struct inet_connection_sock_af_ops ipv6_specific;
  #endif

  void mptcp_proto_init(void);

  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  int mptcp_proto_v6_init(void);
  #endif

  struct sock *mptcp_sk_clone(const struct sock *sk, struct request_sock *req);

  void mptcp_get_options(const struct sk_buff *skb,
  		       struct tcp_options_received *opt_rx);
  
  void mptcp_finish_connect(struct sock *sk);

  void mptcp_data_ready(struct sock *sk, struct sock *ssk);

  bool mptcp_finish_join(struct sock *sk);

  void mptcp_data_acked(struct sock *sk);

  void mptcp_subflow_eof(struct sock *sk);

  int mptcp_token_new_request(struct request_sock *req);
  void mptcp_token_destroy_request(u32 token);
  int mptcp_token_new_connect(struct sock *sk);

  int mptcp_token_new_accept(u32 token, struct sock *conn);

  struct mptcp_sock *mptcp_token_get_sock(u32 token);

  void mptcp_token_destroy(u32 token);
  
  void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn);
  static inline void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
  {
  	/* we might consider a faster version that computes the key as a
  	 * hash of some information available in the MPTCP socket. Use
  	 * random data at the moment, as it's probably the safest option
  	 * in case multiple sockets are opened in different namespaces at
  	 * the same time.
  	 */
  	get_random_bytes(key, sizeof(u64));
  	mptcp_crypto_key_sha(*key, token, idsn);
  }

  void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);

  void mptcp_pm_init(void);
  void mptcp_pm_data_init(struct mptcp_sock *msk);

  void mptcp_pm_close(struct mptcp_sock *msk);

  void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side);
  void mptcp_pm_fully_established(struct mptcp_sock *msk);
  bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);
  void mptcp_pm_connection_closed(struct mptcp_sock *msk);
  void mptcp_pm_subflow_established(struct mptcp_sock *msk,
  				  struct mptcp_subflow_context *subflow);
  void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id);
  void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
  				const struct mptcp_addr_info *addr);
  
  int mptcp_pm_announce_addr(struct mptcp_sock *msk,
  			   const struct mptcp_addr_info *addr);
  int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id);
  int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id);
  
  static inline bool mptcp_pm_should_signal(struct mptcp_sock *msk)
  {
  	return READ_ONCE(msk->pm.addr_signal);
  }
  
  static inline unsigned int mptcp_add_addr_len(int family)
  {
  	if (family == AF_INET)
  		return TCPOLEN_MPTCP_ADD_ADDR;
  	return TCPOLEN_MPTCP_ADD_ADDR6;
  }
  
  bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
  			  struct mptcp_addr_info *saddr);
  int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);

  void mptcp_pm_nl_init(void);
  void mptcp_pm_nl_data_init(struct mptcp_sock *msk);
  void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
  void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
  void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk);
  int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);

  static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
  {
  	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);
  }

  static inline bool before64(__u64 seq1, __u64 seq2)
  {
  	return (__s64)(seq1 - seq2) < 0;
  }
  
  #define after64(seq2, seq1)	before64(seq1, seq2)

  void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops);

  #endif /* __MPTCP_PROTOCOL_H */