/* $Id: tcp.h 69500 2017-10-28 15:14:05Z vboxsync $ */
/** @file
 * NAT - TCP.
 */

/*
 * Copyright (C) 2006-2017 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 */

/*
 * This code is based on:
 *
 * 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
 * tcp.h,v 1.3 1994/08/21 05:27:34 paul Exp
 */

#ifndef _TCP_H_
#define _TCP_H_

typedef uint32_t  tcp_seq;

#define PR_SLOWHZ       2               /* 2 slow timeouts per second (approx) */
#define PR_FASTHZ       5               /* 5 fast timeouts per second (not important) */

extern int tcp_rcvspace;
extern int tcp_sndspace;
extern struct socket *tcp_last_so;

#define TCP_SNDSPACE 8192
#define TCP_RCVSPACE 8192

/*
 * TCP header.
 * Per RFC 793, September, 1981.
 */
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 */
#ifdef WORDS_BIGENDIAN
# ifdef _MSC_VER
    uint8_t    th_off:4;               /* data offset */
    uint8_t    th_x2:4;                /* (unused) */
# else
    unsigned   th_off:4;               /* data offset */
    unsigned   th_x2:4;                /* (unused) */
# endif
#else
# ifdef _MSC_VER
    uint8_t    th_x2:4;                /* (unused) */
    uint8_t    th_off:4;               /* data offset */
# else
    unsigned   th_x2:4;                /* (unused) */
    unsigned   th_off:4;               /* data offset */
# endif
#endif
    uint8_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
    uint16_t   th_win;                 /* window */
    uint16_t   th_sum;                 /* checksum */
    uint16_t   th_urp;                 /* urgent pointer */
};
AssertCompileSize(struct tcphdr, 20);

#include "tcp_var.h"

#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)

/*
 * 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)).
 *
 * We make this 1460 because we only care about Ethernet in the qemu context.
 */
#define TCP_MSS (if_mtu - 80)

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

#define TCP_MAX_WINSHIFT        14      /* maximum window shift */

/*
 * User-settable options (used with setsockopt).
 *
 * We don't use the system headers on unix because we have conflicting
 * local structures. We can't avoid the system definitions on Windows,
 * so we undefine them.
 */
#undef TCP_NODELAY
#define TCP_NODELAY     0x01    /* don't delay send to coalesce packets */
#undef TCP_MAXSEG
/* #define      TCP_MAXSEG      0x02 */ /* set maximum segment size */

/*
 * TCP FSM state definitions.
 * Per RFC793, September, 1981.
 */

#define TCP_NSTATES     11

#define TCPS_CLOSED             0       /* closed */
#define TCPS_LISTEN             1       /* listening for connection */
#define TCPS_SYN_SENT           2       /* active, have sent syn */
#define TCPS_SYN_RECEIVED       3       /* have send and received syn */
/* states < TCPS_ESTABLISHED are those where connections not established */
#define TCPS_ESTABLISHED        4       /* established */
#define TCPS_CLOSE_WAIT         5       /* rcvd fin, waiting for close */
/* states > TCPS_CLOSE_WAIT are those where user has closed */
#define TCPS_FIN_WAIT_1         6       /* have closed, sent fin */
#define TCPS_CLOSING            7       /* closed xchd FIN; await FIN ACK */
#define TCPS_LAST_ACK           8       /* had fin and close; await FIN ACK */
/* states > TCPS_CLOSE_WAIT && < TCPS_FIN_WAIT_2 await ACK of FIN */
#define TCPS_FIN_WAIT_2         9       /* have closed, fin is acked */
#define TCPS_TIME_WAIT          10      /* in 2*msl quiet wait after close */

#define TCPS_HAVERCVDSYN(s)     ((s) >= TCPS_SYN_RECEIVED)
#define TCPS_HAVEESTABLISHED(s) ((s) >= TCPS_ESTABLISHED)
#define TCPS_HAVERCVDFIN(s)     ((s) >= TCPS_TIME_WAIT)

/*
 * TCP sequence numbers are 32 bit integers operated on with modular arithmetic.
 * These macros can be used to compare such integers.
 */
#define SEQ_LT(a,b)     ((int)((a)-(b)) < 0)
#define SEQ_LEQ(a,b)    ((int)((a)-(b)) <= 0)
#define SEQ_GT(a,b)     ((int)((a)-(b)) > 0)
#define SEQ_GEQ(a,b)    ((int)((a)-(b)) >= 0)

/*
 * Macros to initialize tcp sequence numbers for
 * send and receive from initial send and receive
 * sequence numbers.
 */
#define tcp_rcvseqinit(tp) \
     (tp)->rcv_adv = (tp)->rcv_nxt = (tp)->irs + 1

#define tcp_sendseqinit(tp) \
    (tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = (tp)->iss

#define TCP_ISSINCR     (125*1024)      /* increment for tcp_iss each second */


extern const char * const tcpstates[];

#endif