newlib-cygwin/winsup/cygwin/include/netinet/tcp.h

/*
 * 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
 * $FreeBSD: src/sys/netinet/tcp.h,v 1.13 2000/01/09 19:17:25 shin Exp $
 */

#ifndef _NETINET_TCP_H
#define _NETINET_TCP_H

#include <bits/endian.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_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
	unsigned int  th_x2:4,          /* (unused) */
		      th_off:4;         /* data offset */
#endif
#if __BYTE_ORDER == __BIG_ENDIAN
	unsigned int  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_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG)

	u_int16_t th_win;                 /* window */
	u_int16_t th_sum;                 /* checksum */
	u_int16_t 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_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      0x04    /* get maximum segment size (r/o on windows) */
#define TCP_FASTOPEN    0x0f    /* enable FastOpen on listeners */

#endif