* Copyright (c) 1982, 1986, 1993

/* $NetBSD: tcp.h,v 1.37 2021/02/03 18:13:13 roy 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/featuretest.h>

#if defined(_NETBSD_SOURCE)
#include <sys/types.h>

typedef uint32_t tcp_seq;
/*
* TCP header.
* Per RFC 793, September, 1981.
* Updated by RFC 3168, September, 2001.
*/
struct tcphdr {
uint16_t th_sport; /* source port */
uint16_t th_dport; /* destination port */
tcp_seq th_seq; /* sequence number */
tcp_seq th_ack; /* acknowledgement number */
#if BYTE_ORDER == LITTLE_ENDIAN
/*LINTED non-portable bitfields*/
uint8_t th_x2:4, /* (unused) */
th_off:4; /* data offset */
#endif
#if BYTE_ORDER == BIG_ENDIAN
/*LINTED non-portable bitfields*/
uint8_t th_off:4, /* data offset */
th_x2:4; /* (unused) */
#endif
uint8_t th_flags;
#define TH_FIN 0x01 /* Final: Set on the last segment */
#define TH_SYN 0x02 /* Synchronization: New conn with dst port */
#define TH_RST 0x04 /* Reset: Announce to peer conn terminated */
#define TH_PUSH 0x08 /* Push: Immediately send, don't buffer seg */
#define TH_ACK 0x10 /* Acknowledge: Part of connection establish */
#define TH_URG 0x20 /* Urgent: send special marked segment now */
#define TH_ECE 0x40 /* ECN Echo */
#define TH_CWR 0x80 /* Congestion Window Reduced */
uint16_t th_win; /* window */
uint16_t th_sum; /* checksum */
uint16_t th_urp; /* urgent pointer */
};
#ifdef __CTASSERT
__CTASSERT(sizeof(struct tcphdr) == 20);
#endif

#define TCPOPT_EOL 0
#define TCPOLEN_EOL 1
#define TCPOPT_PAD 0
#define TCPOLEN_PAD 1
#define TCPOPT_NOP 1
#define TCPOLEN_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_SIGNATURE 19 /* Keyed MD5: RFC 2385 */
#define TCPOLEN_SIGNATURE 18
#define TCPOLEN_SIGLEN (TCPOLEN_SIGNATURE+2) /* padding */

#define MAX_TCPOPTLEN 40 /* max # bytes that go in options */

/*
* Default maximum segment size for TCP.
* This is defined by RFC 1112 Sec 4.2.2.6.
*/
#define TCP_MSS 536

#define TCP_MINMSS 216

#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */

#define TCP_MAX_WINSHIFT 14 /* maximum window shift */

#define TCP_MAXBURST 4 /* maximum segments in a burst */

#endif /* _NETBSD_SOURCE */

/*
* User-settable options (used with setsockopt).
*/
#define TCP_NODELAY 1 /* don't delay send to coalesce packets */
#define TCP_MAXSEG 2 /* set maximum segment size */
#define TCP_KEEPIDLE 3
#ifdef notyet
#define TCP_NOPUSH 4 /* reserved for FreeBSD compat */
#endif
#define TCP_KEEPINTVL 5
#define TCP_KEEPCNT 6
#define TCP_KEEPINIT 7
#ifdef notyet
#define TCP_NOOPT 8 /* reserved for FreeBSD compat */
#endif
#define TCP_INFO 9 /* retrieve tcp_info structure */
#define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */
#define TCP_CONGCTL 0x20 /* selected congestion control */

#define TCPI_OPT_TIMESTAMPS 0x01
#define TCPI_OPT_SACK 0x02
#define TCPI_OPT_WSCALE 0x04
#define TCPI_OPT_ECN 0x08
#define TCPI_OPT_TOE 0x10

/*
* The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
* the caller to query certain information about the state of a TCP
* connection. We provide an overlapping set of fields with the Linux
* implementation, but since this is a fixed size structure, room has been
* left for growth. In order to maximize potential future compatibility with
* the Linux API, the same variable names and order have been adopted, and
* padding left to make room for omitted fields in case they are added later.
*
* XXX: This is currently an unstable ABI/API, in that it is expected to
* change.
*/
struct tcp_info {
uint8_t tcpi_state; /* TCP FSM state. */
uint8_t __tcpi_ca_state;
uint8_t __tcpi_retransmits;
uint8_t __tcpi_probes;
uint8_t __tcpi_backoff;
uint8_t tcpi_options; /* Options enabled on conn. */
/*LINTED: non-portable bitfield*/
uint8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
/*LINTED: non-portable bitfield*/
tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */

uint32_t tcpi_rto; /* Retransmission timeout (usec). */
uint32_t __tcpi_ato;
uint32_t tcpi_snd_mss; /* Max segment size for send. */
uint32_t tcpi_rcv_mss; /* Max segment size for receive. */

uint32_t __tcpi_unacked;
uint32_t __tcpi_sacked;
uint32_t __tcpi_lost;
uint32_t __tcpi_retrans;
uint32_t __tcpi_fackets;

/* Times; measurements in usecs. */
uint32_t __tcpi_last_data_sent;
uint32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
uint32_t tcpi_last_data_recv; /* Time since last recv data. */
uint32_t __tcpi_last_ack_recv;

/* Metrics; variable units. */
uint32_t __tcpi_pmtu;
uint32_t __tcpi_rcv_ssthresh;
uint32_t tcpi_rtt; /* Smoothed RTT in usecs. */
uint32_t tcpi_rttvar; /* RTT variance in usecs. */
uint32_t tcpi_snd_ssthresh; /* Slow start threshold. */
uint32_t tcpi_snd_cwnd; /* Send congestion window. */
uint32_t __tcpi_advmss;
uint32_t __tcpi_reordering;

uint32_t __tcpi_rcv_rtt;
uint32_t tcpi_rcv_space; /* Advertised recv window. */

/* FreeBSD/NetBSD extensions to tcp_info. */
uint32_t tcpi_snd_wnd; /* Advertised send window. */
uint32_t tcpi_snd_bwnd; /* No longer used. */
uint32_t tcpi_snd_nxt; /* Next egress seqno */
uint32_t tcpi_rcv_nxt; /* Next ingress seqno */
uint32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
uint32_t tcpi_snd_rexmitpack; /* Retransmitted packets */
uint32_t tcpi_rcv_ooopack; /* Out-of-order packets */
uint32_t tcpi_snd_zerowin; /* Zero-sized windows sent */

/* Padding to grow without breaking ABI. */
uint32_t __tcpi_pad[26]; /* Padding. */
};

#endif /* !_NETINET_TCP_H_ */