/*
 * 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/skbuff.h>
#include <uapi/linux/tcp.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;
}

/* TCP Fast Open */
#define TCP_FASTOPEN_COOKIE_MIN	4	/* Min Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_MAX	16	/* Max Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_SIZE 8	/* the size employed by this impl. */

/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
	s8	len;
	u8	val[TCP_FASTOPEN_COOKIE_MAX];
};

/* 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;
};

/*These are used to set the sack_ok field in struct tcp_options_received */
#define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
#define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
#define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/

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	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;
}

/* 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

enum tsq_flags {
	TSQ_THROTTLED,
	TSQ_QUEUED,
	TCP_TSQ_DEFERRED,	   /* tcp_tasklet_func() found socket was owned */
	TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
	TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
	TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
				    * tcp_v{4|6}_mtu_reduced()
				    */
};

#endif	/* _LINUX_TCP_H */