text: /*
   * Copyright (c) 1982, 1986, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)tcp.h	8.1 (Berkeley) 6/10/93
   * $FreeBSD: src/sys/netinet/tcp.h,v 1.16 2001/01/09 18:26:17 rwatson Exp $
   */
  
  #ifndef _NETINET_TCP_H_
  #define _NETINET_TCP_H_
  
  typedef u_int32_t tcp_seq;
  typedef u_int32_t tcp_cc; /* connection count per rfc1644 */
  
  #define tcp6_seq	tcp_seq	/* for KAME src sync over BSD*'s */
  #define tcp6hdr		tcphdr	/* for KAME src sync over BSD*'s */
  
  /*
   * TCP header.
   * Per RFC 793, September, 1981.
   */
  struct tcphdr {
  	u_short th_sport; /* source port */
  	u_short th_dport; /* destination port */
  	tcp_seq th_seq; /* sequence number */
  	tcp_seq th_ack; /* acknowledgement number */
  #if BYTE_ORDER == LITTLE_ENDIAN
  	u_int th_x2 :4, /* (unused) */
  	th_off :4; /* data offset */
  #endif
  #if BYTE_ORDER == BIG_ENDIAN
  	u_int th_off :4, /* data offset */
  	th_x2 :4; /* (unused) */
  #endif
  	u_char th_flags;
  #define	TH_FIN	0x01
  #define	TH_SYN	0x02
  #define	TH_RST	0x04
  #define	TH_PUSH	0x08
  #define	TH_ACK	0x10
  #define	TH_URG	0x20
  #define	TH_ECE	0x40
  #define	TH_CWR	0x80
  #define	TH_FLAGS	(TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
  
  	u_short th_win; /* window */
  	u_short th_sum; /* checksum */
  	u_short th_urp; /* urgent pointer */
  };
  
  #define	TCPOPT_EOL		0
  #define	TCPOPT_NOP		1
  #define	TCPOPT_MAXSEG		2
  #define    TCPOLEN_MAXSEG		4
  #define TCPOPT_WINDOW		3
  #define    TCPOLEN_WINDOW		3
  #define TCPOPT_SACK_PERMITTED	4		/* Experimental */
  #define    TCPOLEN_SACK_PERMITTED	2
  #define TCPOPT_SACK		5		/* Experimental */
  #define TCPOPT_TIMESTAMP	8
  #define    TCPOLEN_TIMESTAMP		10
  #define    TCPOLEN_TSTAMP_APPA		(TCPOLEN_TIMESTAMP+2) /* appendix A */
  #define    TCPOPT_TSTAMP_HDR		\
      (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
  
  #define	TCPOPT_CC		11		/* CC options: RFC-1644 */
  #define TCPOPT_CCNEW		12
  #define TCPOPT_CCECHO		13
  #define	   TCPOLEN_CC			6
  #define	   TCPOLEN_CC_APPA		(TCPOLEN_CC+2)
  #define	   TCPOPT_CC_HDR(ccopt)		\
      (TCPOPT_NOP<<24|TCPOPT_NOP<<16|(ccopt)<<8|TCPOLEN_CC)
  
  /*
   * Default maximum segment size for TCP.
   * With an IP MSS of 576, this is 536,
   * but 512 is probably more convenient.
   * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
   */
  /*#define	TCP_MSS	512*/
  
  /*
   * Default maximum segment size for TCP6.
   * With an IP6 MSS of 1280, this is 1220,
   * but 1024 is probably more convenient. (xxx kazu in doubt)
   * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
   */
  #define	TCP6_MSS	1024
  
  #define	TCP_MAXWIN	65535	/* largest value for (unscaled) window */
  #define	TTCP_CLIENT_SND_WND	4096	/* dflt send window for T/TCP client */
  
  #define TCP_MAX_WINSHIFT	14	/* maximum window shift */
  
  #define TCP_MAXBURST		4 	/* maximum segments in a burst */
  
  #define TCP_MAXHLEN	(0xf<<2)	/* max length of header in bytes */
  #define TCP_MAXOLEN	(TCP_MAXHLEN - sizeof(struct tcphdr))
  /* max space left for options */
  
  /*
   * User-settable options (used with setsockopt).
   */
  #define	TCP_NODELAY	0x01	/* don't delay send to coalesce packets */
  #define	TCP_MAXSEG	0x02	/* set maximum segment size */
  #define TCP_NOPUSH	0x04	/* don't push last block of write */
  #define TCP_NOOPT	0x08	/* don't use TCP options */
  
  #endif
  