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/* $OpenBSD: tcp.h,v 1.21 2019/07/10 18:45:31 bluhm Exp $ */
/* $NetBSD: tcp.h,v 1.8 1995/04/17 05:32:58 cgd Exp $ */
/*
* 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. 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
*/
#ifndef _NETINET_TCP_H_
#define _NETINET_TCP_H_
#include <sys/cdefs.h>
#if __BSD_VISIBLE
typedef u_int32_t tcp_seq;
/*
* TCP header.
* Per RFC 793, September, 1981.
*/
struct tcphdr {
u_int16_t th_sport; /* source port */
u_int16_t th_dport; /* destination port */
tcp_seq th_seq; /* sequence number */
tcp_seq th_ack; /* acknowledgement number */
#if _BYTE_ORDER == _LITTLE_ENDIAN
u_int32_t th_x2:4, /* (unused) */
th_off:4; /* data offset */
#endif
#if _BYTE_ORDER == _BIG_ENDIAN
u_int32_t th_off:4, /* data offset */
th_x2:4; /* (unused) */
#endif
u_int8_t 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
u_int16_t th_win; /* window */
u_int16_t th_sum; /* checksum */
u_int16_t th_urp; /* urgent pointer */
};
#define th_reseqlen th_urp /* TCP data length for
resequencing/reassembly */
#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 TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
#define TCPOPT_TIMESTAMP 8
#define TCPOLEN_TIMESTAMP 10
#define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
#define TCPOPT_SIGNATURE 19
#define TCPOLEN_SIGNATURE 18
#define TCPOLEN_SIGLEN (TCPOLEN_SIGNATURE+2) /* padding */
#define MAX_TCPOPTLEN 40 /* Absolute maximum TCP options len */
#define TCPOPT_TSTAMP_HDR \
(TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
/* Option definitions */
#define TCPOPT_SACK_PERMIT_HDR \
(TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK_PERMITTED<<8|TCPOLEN_SACK_PERMITTED)
#define TCPOPT_SACK_HDR (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK<<8)
/* Miscellaneous constants */
#define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at sender side */
#define TCP_MAX_SACK 3 /* Max # SACKs sent in any segment */
#define TCP_SACKHOLE_LIMIT 128 /* Max # SACK holes per connection */
#define TCP_MAXBURST 4 /* Max # packets after leaving Fast Rxmit */
/*
* 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
#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
#define TCP_MAX_WINSHIFT 14 /* maximum window shift */
#endif /* __BSD_VISIBLE */
/*
* User-settable options (used with setsockopt).
*/
#define TCP_NODELAY 0x01 /* don't delay send to coalesce pkts */
#define TCP_MAXSEG 0x02 /* set maximum segment size */
#define TCP_MD5SIG 0x04 /* enable TCP MD5 signature option */
#define TCP_SACK_ENABLE 0x08 /* enable SACKs (if disabled by def.) */
#define TCP_NOPUSH 0x10 /* don't push last block of write */
#endif /* _NETINET_TCP_H_ */
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