/*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		Definitions for the TCP protocol.
   *
   * Version:	@(#)tcp.h	1.0.2	04/28/93
   *
   * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   */
  #ifndef _LINUX_TCP_H
  #define _LINUX_TCP_H
  
  #include <linux/types.h>
  #include <asm/byteorder.h>

  #include <linux/socket.h>

  
  struct tcphdr {

  	__be16	source;
  	__be16	dest;
  	__be32	seq;
  	__be32	ack_seq;

  #if defined(__LITTLE_ENDIAN_BITFIELD)
  	__u16	res1:4,
  		doff:4,
  		fin:1,
  		syn:1,
  		rst:1,
  		psh:1,
  		ack:1,
  		urg:1,
  		ece:1,
  		cwr:1;
  #elif defined(__BIG_ENDIAN_BITFIELD)
  	__u16	doff:4,
  		res1:4,
  		cwr:1,
  		ece:1,
  		urg:1,
  		ack:1,
  		psh:1,
  		rst:1,
  		syn:1,
  		fin:1;
  #else
  #error	"Adjust your <asm/byteorder.h> defines"
  #endif	

  	__be16	window;

  	__sum16	check;

  	__be16	urg_ptr;

  };

  /*
   *	The union cast uses a gcc extension to avoid aliasing problems
   *  (union is compatible to any of its members)
   *  This means this part of the code is -fstrict-aliasing safe now.
   */
  union tcp_word_hdr { 
  	struct tcphdr hdr;

  	__be32 		  words[5];

  }; 
  
  #define tcp_flag_word(tp) ( ((union tcp_word_hdr *)(tp))->words [3]) 
  
  enum { 

  	TCP_FLAG_CWR = __cpu_to_be32(0x00800000),
  	TCP_FLAG_ECE = __cpu_to_be32(0x00400000),
  	TCP_FLAG_URG = __cpu_to_be32(0x00200000),
  	TCP_FLAG_ACK = __cpu_to_be32(0x00100000),
  	TCP_FLAG_PSH = __cpu_to_be32(0x00080000),
  	TCP_FLAG_RST = __cpu_to_be32(0x00040000),
  	TCP_FLAG_SYN = __cpu_to_be32(0x00020000),
  	TCP_FLAG_FIN = __cpu_to_be32(0x00010000),
  	TCP_RESERVED_BITS = __cpu_to_be32(0x0F000000),
  	TCP_DATA_OFFSET = __cpu_to_be32(0xF0000000)

  }; 

  /*
   * TCP general constants
   */
  #define TCP_MSS_DEFAULT		 536U	/* IPv4 (RFC1122, RFC2581) */
  #define TCP_MSS_DESIRED		1220U	/* IPv6 (tunneled), EDNS0 (RFC3226) */

  /* TCP socket options */
  #define TCP_NODELAY		1	/* Turn off Nagle's algorithm. */
  #define TCP_MAXSEG		2	/* Limit MSS */
  #define TCP_CORK		3	/* Never send partially complete segments */
  #define TCP_KEEPIDLE		4	/* Start keeplives after this period */
  #define TCP_KEEPINTVL		5	/* Interval between keepalives */
  #define TCP_KEEPCNT		6	/* Number of keepalives before death */
  #define TCP_SYNCNT		7	/* Number of SYN retransmits */
  #define TCP_LINGER2		8	/* Life time of orphaned FIN-WAIT-2 state */
  #define TCP_DEFER_ACCEPT	9	/* Wake up listener only when data arrive */
  #define TCP_WINDOW_CLAMP	10	/* Bound advertised window */
  #define TCP_INFO		11	/* Information about this connection. */
  #define TCP_QUICKACK		12	/* Block/reenable quick acks */

  #define TCP_CONGESTION		13	/* Congestion control algorithm */

  #define TCP_MD5SIG		14	/* TCP MD5 Signature (RFC2385) */

  #define TCP_COOKIE_TRANSACTIONS	15	/* TCP Cookie Transactions */

  #define TCP_THIN_LINEAR_TIMEOUTS 16      /* Use linear timeouts for thin streams*/

  #define TCP_THIN_DUPACK         17      /* Fast retrans. after 1 dupack */

  #define TCP_USER_TIMEOUT	18	/* How long for loss retry before timeout */

  /* for TCP_INFO socket option */

  #define TCPI_OPT_TIMESTAMPS	1
  #define TCPI_OPT_SACK		2
  #define TCPI_OPT_WSCALE		4

  #define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
  #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */

  enum tcp_ca_state {

  	TCP_CA_Open = 0,
  #define TCPF_CA_Open	(1<<TCP_CA_Open)
  	TCP_CA_Disorder = 1,
  #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
  	TCP_CA_CWR = 2,
  #define TCPF_CA_CWR	(1<<TCP_CA_CWR)
  	TCP_CA_Recovery = 3,
  #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
  	TCP_CA_Loss = 4
  #define TCPF_CA_Loss	(1<<TCP_CA_Loss)
  };

  struct tcp_info {

  	__u8	tcpi_state;
  	__u8	tcpi_ca_state;
  	__u8	tcpi_retransmits;
  	__u8	tcpi_probes;
  	__u8	tcpi_backoff;
  	__u8	tcpi_options;
  	__u8	tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
  
  	__u32	tcpi_rto;
  	__u32	tcpi_ato;
  	__u32	tcpi_snd_mss;
  	__u32	tcpi_rcv_mss;
  
  	__u32	tcpi_unacked;
  	__u32	tcpi_sacked;
  	__u32	tcpi_lost;
  	__u32	tcpi_retrans;
  	__u32	tcpi_fackets;
  
  	/* Times. */
  	__u32	tcpi_last_data_sent;
  	__u32	tcpi_last_ack_sent;     /* Not remembered, sorry. */
  	__u32	tcpi_last_data_recv;
  	__u32	tcpi_last_ack_recv;
  
  	/* Metrics. */
  	__u32	tcpi_pmtu;
  	__u32	tcpi_rcv_ssthresh;
  	__u32	tcpi_rtt;
  	__u32	tcpi_rttvar;
  	__u32	tcpi_snd_ssthresh;
  	__u32	tcpi_snd_cwnd;
  	__u32	tcpi_advmss;
  	__u32	tcpi_reordering;
  
  	__u32	tcpi_rcv_rtt;
  	__u32	tcpi_rcv_space;
  
  	__u32	tcpi_total_retrans;
  };

  /* for TCP_MD5SIG socket option */
  #define TCP_MD5SIG_MAXKEYLEN	80
  
  struct tcp_md5sig {
  	struct __kernel_sockaddr_storage tcpm_addr;	/* address associated */
  	__u16	__tcpm_pad1;				/* zero */
  	__u16	tcpm_keylen;				/* key length */
  	__u32	__tcpm_pad2;				/* zero */
  	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];		/* key (binary) */
  };

  /* for TCP_COOKIE_TRANSACTIONS (TCPCT) socket option */
  #define TCP_COOKIE_MIN		 8		/*  64-bits */
  #define TCP_COOKIE_MAX		16		/* 128-bits */
  #define TCP_COOKIE_PAIR_SIZE	(2*TCP_COOKIE_MAX)
  
  /* Flags for both getsockopt and setsockopt */
  #define TCP_COOKIE_IN_ALWAYS	(1 << 0)	/* Discard SYN without cookie */
  #define TCP_COOKIE_OUT_NEVER	(1 << 1)	/* Prohibit outgoing cookies,
  						 * supercedes everything. */
  
  /* Flags for getsockopt */
  #define TCP_S_DATA_IN		(1 << 2)	/* Was data received? */
  #define TCP_S_DATA_OUT		(1 << 3)	/* Was data sent? */
  
  /* TCP_COOKIE_TRANSACTIONS data */
  struct tcp_cookie_transactions {
  	__u16	tcpct_flags;			/* see above */
  	__u8	__tcpct_pad1;			/* zero */
  	__u8	tcpct_cookie_desired;		/* bytes */
  	__u16	tcpct_s_data_desired;		/* bytes of variable data */
  	__u16	tcpct_used;			/* bytes in value */
  	__u8	tcpct_value[TCP_MSS_DEFAULT];
  };

  #ifdef __KERNEL__

  #include <linux/skbuff.h>

  #include <linux/dmaengine.h>

  #include <net/sock.h>

  #include <net/inet_connection_sock.h>

  #include <net/inet_timewait_sock.h>

  static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
  {

  	return (struct tcphdr *)skb_transport_header(skb);

  }

  static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
  {

  	return tcp_hdr(skb)->doff * 4;

  }
  
  static inline unsigned int tcp_optlen(const struct sk_buff *skb)
  {

  	return (tcp_hdr(skb)->doff - 5) * 4;

  }

  /* This defines a selective acknowledgement block. */

  struct tcp_sack_block_wire {
  	__be32	start_seq;
  	__be32	end_seq;
  };

  struct tcp_sack_block {

  	u32	start_seq;
  	u32	end_seq;

  };

  struct tcp_options_received {
  /*	PAWS/RTTM data	*/
  	long	ts_recent_stamp;/* Time we stored ts_recent (for aging) */

  	u32	ts_recent;	/* Time stamp to echo next		*/
  	u32	rcv_tsval;	/* Time stamp value             	*/
  	u32	rcv_tsecr;	/* Time stamp echo reply        	*/
  	u16 	saw_tstamp : 1,	/* Saw TIMESTAMP on last packet		*/

  		tstamp_ok : 1,	/* TIMESTAMP seen on SYN packet		*/
  		dsack : 1,	/* D-SACK is scheduled			*/
  		wscale_ok : 1,	/* Wscale seen on SYN packet		*/
  		sack_ok : 4,	/* SACK seen on SYN packet		*/
  		snd_wscale : 4,	/* Window scaling received from sender	*/
  		rcv_wscale : 4;	/* Window scaling to send to receiver	*/

  	u8	cookie_plus:6,	/* bytes in authenticator/cookie option	*/
  		cookie_out_never:1,
  		cookie_in_always:1;

  	u8	num_sacks;	/* Number of SACK blocks		*/

  	u16	user_mss;	/* mss requested by user in ioctl	*/

  	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */

  };

  static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
  {

  	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
  	rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
  	rx_opt->cookie_plus = 0;

  }

  /* This is the max number of SACKS that we'll generate and process. It's safe

   * to increase this, although since:

   *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
   * only four options will fit in a standard TCP header */
  #define TCP_NUM_SACKS 4

  struct tcp_cookie_values;
  struct tcp_request_sock_ops;

  struct tcp_request_sock {

  	struct inet_request_sock 	req;
  #ifdef CONFIG_TCP_MD5SIG
  	/* Only used by TCP MD5 Signature so far. */

  	const struct tcp_request_sock_ops *af_specific;

  #endif

  	u32				rcv_isn;
  	u32				snt_isn;

  	u32				snt_synack; /* synack sent time */

  };

  static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)

  {
  	return (struct tcp_request_sock *)req;
  }

  struct tcp_sock {

  	/* inet_connection_sock has to be the first member of tcp_sock */
  	struct inet_connection_sock	inet_conn;

  	u16	tcp_header_len;	/* Bytes of tcp header to send		*/

  	u16	xmit_size_goal_segs; /* Goal for segmenting output packets */

  
  /*
   *	Header prediction flags
   *	0x5?10 << 16 + snd_wnd in net byte order
   */

  	__be32	pred_flags;

  
  /*
   *	RFC793 variables by their proper names. This means you can
   *	read the code and the spec side by side (and laugh ...)
   *	See RFC793 and RFC1122. The RFC writes these in capitals.
   */

   	u32	rcv_nxt;	/* What we want to receive next 	*/

  	u32	copied_seq;	/* Head of yet unread data		*/
  	u32	rcv_wup;	/* rcv_nxt on last window update sent	*/

   	u32	snd_nxt;	/* Next sequence we send		*/

   	u32	snd_una;	/* First byte we want an ack for	*/
   	u32	snd_sml;	/* Last byte of the most recently transmitted small packet */
  	u32	rcv_tstamp;	/* timestamp of last received ACK (for keepalives) */
  	u32	lsndtime;	/* timestamp of last sent data packet (for restart window) */

  
  	/* Data for direct copy to user */
  	struct {
  		struct sk_buff_head	prequeue;
  		struct task_struct	*task;
  		struct iovec		*iov;
  		int			memory;
  		int			len;

  #ifdef CONFIG_NET_DMA
  		/* members for async copy */
  		struct dma_chan		*dma_chan;
  		int			wakeup;
  		struct dma_pinned_list	*pinned_list;
  		dma_cookie_t		dma_cookie;
  #endif

  	} ucopy;

  	u32	snd_wl1;	/* Sequence for window update		*/
  	u32	snd_wnd;	/* The window we expect to receive	*/
  	u32	max_window;	/* Maximal window ever seen from peer	*/
  	u32	mss_cache;	/* Cached effective mss, not including SACKS */

  	u32	window_clamp;	/* Maximal window to advertise		*/
  	u32	rcv_ssthresh;	/* Current window clamp			*/

  	u32	frto_highmark;	/* snd_nxt when RTO occurred */

  	u16	advmss;		/* Advertised MSS			*/

  	u8	frto_counter;	/* Number of new acks after RTO */

  	u8	nonagle     : 4,/* Disable Nagle algorithm?             */
  		thin_lto    : 1,/* Use linear timeouts for thin streams */

  		thin_dupack : 1,/* Fast retransmit on first dupack      */
  		unused      : 2;

  
  /* RTT measurement */

  	u32	srtt;		/* smoothed round trip time << 3	*/
  	u32	mdev;		/* medium deviation			*/
  	u32	mdev_max;	/* maximal mdev for the last rtt period	*/
  	u32	rttvar;		/* smoothed mdev_max			*/
  	u32	rtt_seq;	/* sequence number to update rttvar	*/
  
  	u32	packets_out;	/* Packets which are "in flight"	*/

  	u32	retrans_out;	/* Retransmitted packets out		*/

  
  	u16	urg_data;	/* Saved octet of OOB data and control flags */

  	u8	ecn_flags;	/* ECN status bits.			*/

  	u8	reordering;	/* Packet reordering metric.		*/
  	u32	snd_up;		/* Urgent pointer		*/
  
  	u8	keepalive_probes; /* num of allowed keep alive probes	*/

  /*
   *      Options received (usually on last packet, some only on SYN packets).
   */

  	struct tcp_options_received rx_opt;
  
  /*
   *	Slow start and congestion control (see also Nagle, and Karn & Partridge)
   */

   	u32	snd_ssthresh;	/* Slow start size threshold		*/
   	u32	snd_cwnd;	/* Sending congestion window		*/

  	u32	snd_cwnd_cnt;	/* Linear increase counter		*/

  	u32	snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */

  	u32	snd_cwnd_used;
  	u32	snd_cwnd_stamp;

  	u32	prior_cwnd;	/* Congestion window at start of Recovery. */
  	u32	prr_delivered;	/* Number of newly delivered packets to
  				 * receiver in Recovery. */
  	u32	prr_out;	/* Total number of pkts sent during Recovery. */

   	u32	rcv_wnd;	/* Current receiver window		*/

  	u32	write_seq;	/* Tail(+1) of data held in tcp send buffer */
  	u32	pushed_seq;	/* Last pushed seq, required to talk to windows */

  	u32	lost_out;	/* Lost packets			*/
  	u32	sacked_out;	/* SACK'd packets			*/
  	u32	fackets_out;	/* FACK'd packets			*/
  	u32	tso_deferred;
  	u32	bytes_acked;	/* Appropriate Byte Counting - RFC3465 */

  	/* from STCP, retrans queue hinting */
  	struct sk_buff* lost_skb_hint;
  	struct sk_buff *scoreboard_skb_hint;
  	struct sk_buff *retransmit_skb_hint;

  
  	struct sk_buff_head	out_of_order_queue; /* Out of order segments go here */
  
  	/* SACKs data, these 2 need to be together (see tcp_build_and_update_options) */

  	struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
  	struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/

  	struct tcp_sack_block recv_sack_cache[4];

  	struct sk_buff *highest_sack;   /* highest skb with SACK received
  					 * (validity guaranteed only if
  					 * sacked_out > 0)
  					 */

  	int     lost_cnt_hint;

  	u32     retransmit_high;	/* L-bits may be on up to this seqno */

  	u32	lost_retrans_low;	/* Sent seq after any rxmit (lowest) */

  	u32	prior_ssthresh; /* ssthresh saved at recovery start	*/

  	u32	high_seq;	/* snd_nxt at onset of congestion	*/

  	u32	retrans_stamp;	/* Timestamp of the last retransmit,

  				 * also used in SYN-SENT to remember stamp of
  				 * the first SYN. */

  	u32	undo_marker;	/* tracking retrans started here. */

  	int	undo_retrans;	/* number of undoable retransmissions. */

  	u32	total_retrans;	/* Total retransmits for entire connection */

  	u32	urg_seq;	/* Seq of received urgent pointer */

  	unsigned int		keepalive_time;	  /* time before keep alive takes place */
  	unsigned int		keepalive_intvl;  /* time interval between keep alive probes */

  	int			linger2;

  
  /* Receiver side RTT estimation */
  	struct {

  		u32	rtt;
  		u32	seq;
  		u32	time;

  	} rcv_rtt_est;
  
  /* Receiver queue space */
  	struct {
  		int	space;

  		u32	seq;
  		u32	time;

  	} rcvq_space;

  
  /* TCP-specific MTU probe information. */
  	struct {

  		u32		  probe_seq_start;
  		u32		  probe_seq_end;

  	} mtu_probe;

  
  #ifdef CONFIG_TCP_MD5SIG
  /* TCP AF-Specific parts; only used by MD5 Signature support so far */

  	const struct tcp_sock_af_ops	*af_specific;

  /* TCP MD5 Signature Option information */

  	struct tcp_md5sig_info	*md5sig_info;
  #endif

  
  	/* When the cookie options are generated and exchanged, then this
  	 * object holds a reference to them (cookie_values->kref).  Also
  	 * contains related tcp_cookie_transactions fields.
  	 */
  	struct tcp_cookie_values  *cookie_values;

  };
  
  static inline struct tcp_sock *tcp_sk(const struct sock *sk)
  {
  	return (struct tcp_sock *)sk;
  }

  struct tcp_timewait_sock {
  	struct inet_timewait_sock tw_sk;

  	u32			  tw_rcv_nxt;
  	u32			  tw_snd_nxt;
  	u32			  tw_rcv_wnd;
  	u32			  tw_ts_recent;

  	long			  tw_ts_recent_stamp;

  #ifdef CONFIG_TCP_MD5SIG

  	u16			  tw_md5_keylen;
  	u8			  tw_md5_key[TCP_MD5SIG_MAXKEYLEN];

  #endif

  	/* Few sockets in timewait have cookies; in that case, then this
  	 * object holds a reference to them (tw_cookie_values->kref).
  	 */
  	struct tcp_cookie_values  *tw_cookie_values;

  };
  
  static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
  {
  	return (struct tcp_timewait_sock *)sk;
  }

  #endif	/* __KERNEL__ */

  
  #endif	/* _LINUX_TCP_H */