/*
 * Copyright (c) 1982, 1986, 1993, 1994
 *	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_var.h	8.3 (Berkeley) 4/10/94
 * tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
 */

#ifndef _TCP_VAR_H_
#define _TCP_VAR_H_

#include "tcpip.h"
#include "tcp_timer.h"

/*
 * Tcp control block, one per tcp; fields:
 */
struct tcpcb {
        struct tcpiphdr *seg_next; /* sequencing queue */
        struct tcpiphdr *seg_prev;
        short t_state;               /* state of this connection */
        short t_timer[TCPT_NTIMERS]; /* tcp timers */
        short t_rxtshift;            /* log(2) of rexmt exp. backoff */
        short t_rxtcur;              /* current retransmit value */
        short t_dupacks;             /* consecutive dup acks recd */
        u_short t_maxseg;            /* maximum segment size */
        char t_force;                /* 1 if forcing out a byte */
        u_short t_flags;
#define TF_ACKNOW 0x0001      /* ack peer immediately */
#define TF_DELACK 0x0002      /* ack, but try to delay it */
#define TF_NODELAY 0x0004     /* don't delay packets to coalesce */
#define TF_NOOPT 0x0008       /* don't use tcp options */
#define TF_SENTFIN 0x0010     /* have sent FIN */
#define TF_REQ_SCALE 0x0020   /* have/will request window scaling */
#define TF_RCVD_SCALE 0x0040  /* other side has requested scaling */
#define TF_REQ_TSTMP 0x0080   /* have/will request timestamps */
#define TF_RCVD_TSTMP 0x0100  /* a timestamp was received in SYN */
#define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */

        /* Make it static  for now */
        /*	struct	tcpiphdr *t_template;	/ * skeletal packet for transmit */
        struct tcpiphdr t_template;

        struct SLIRPsocket *t_socket; /* back pointer to socket */
                                      /*
                                       * The following fields are used as in the protocol specification.
                                       * See RFC783, Dec. 1981, page 21.
                                       */
                                      /* send sequence variables */
        tcp_seq snd_una;              /* send unacknowledged */
        tcp_seq snd_nxt;              /* send next */
        tcp_seq snd_up;               /* send urgent pointer */
        tcp_seq snd_wl1;              /* window update seg seq number */
        tcp_seq snd_wl2;              /* window update seg ack number */
        tcp_seq iss;                  /* initial send sequence number */
        u_int32_t snd_wnd;            /* send window */
                                      /* receive sequence variables */
        u_int32_t rcv_wnd;            /* receive window */
        tcp_seq rcv_nxt;              /* receive next */
        tcp_seq rcv_up;               /* receive urgent pointer */
        tcp_seq irs;                  /* initial receive sequence number */
                                      /*
                                       * Additional variables for this implementation.
                                       */
                                      /* receive variables */
        tcp_seq rcv_adv;              /* advertised window */
                                      /* retransmit variables */
        tcp_seq snd_max;              /* highest sequence number sent;
                                       * used to recognize retransmits
                                       */
                                      /* congestion control (for slow start, source quench, retransmit after loss) */
        u_int32_t snd_cwnd;           /* congestion-controlled window */
        u_int32_t snd_ssthresh;       /* snd_cwnd size threshold for
                                       * for slow start exponential to
                                       * linear switch
                                       */
                                      /*
                                       * transmit timing stuff.  See below for scale of srtt and rttvar.
                                       * "Variance" is actually smoothed difference.
                                       */
        short t_idle;                 /* inactivity time */
        short t_rtt;                  /* round trip time */
        tcp_seq t_rtseq;              /* sequence number being timed */
        short t_srtt;                 /* smoothed round-trip time */
        short t_rttvar;               /* variance in round-trip time */
        u_short t_rttmin;             /* minimum rtt allowed */
        u_int32_t max_sndwnd;         /* largest window peer has offered */

        /* out-of-band data */
        char t_oobflags; /* have some */
        char t_iobc;     /* input character */
#define TCPOOB_HAVEDATA 0x01
#define TCPOOB_HADDATA 0x02
        short t_softerror; /* possible error not yet reported */

        /* RFC 1323 variables */
        u_char snd_scale;       /* window scaling for send window */
        u_char rcv_scale;       /* window scaling for recv window */
        u_char request_r_scale; /* pending window scaling */
        u_char requested_s_scale;
        u_int32_t ts_recent;     /* timestamp echo data */
        u_int32_t ts_recent_age; /* when last updated */
        tcp_seq last_ack_sent;
};

#define sototcpcb(so) ((so)->so_tcpcb)

/*
 * The smoothed round-trip time and estimated variance
 * are stored as fixed point numbers scaled by the values below.
 * For convenience, these scales are also used in smoothing the average
 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
 * With these scales, srtt has 3 bits to the right of the binary point,
 * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
 * binary point, and is smoothed with an ALPHA of 0.75.
 */
#define TCP_RTT_SCALE 8    /* multiplier for srtt; 3 bits frac. */
#define TCP_RTT_SHIFT 3    /* shift for srtt; 3 bits frac. */
#define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
#define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */

/*
 * The initial retransmission should happen at rtt + 4 * rttvar.
 * Because of the way we do the smoothing, srtt and rttvar
 * will each average +1/2 tick of bias.  When we compute
 * the retransmit timer, we want 1/2 tick of rounding and
 * 1 extra tick because of +-1/2 tick uncertainty in the
 * firing of the timer.  The bias will give us exactly the
 * 1.5 tick we need.  But, because the bias is
 * statistical, we have to test that we don't drop below
 * the minimum feasible timer (which is 2 ticks).
 * This macro assumes that the value of TCP_RTTVAR_SCALE
 * is the same as the multiplier for rttvar.
 */
#define TCP_REXMTVAL(tp) (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)

/*
 * TCP statistics.
 * Many of these should be kept per connection,
 * but that's inconvenient at the moment.
 */
struct tcpstat {
        u_long tcps_connattempt;  /* connections initiated */
        u_long tcps_accepts;      /* connections accepted */
        u_long tcps_connects;     /* connections established */
        u_long tcps_drops;        /* connections dropped */
        u_long tcps_conndrops;    /* embryonic connections dropped */
        u_long tcps_closed;       /* conn. closed (includes drops) */
        u_long tcps_segstimed;    /* segs where we tried to get rtt */
        u_long tcps_rttupdated;   /* times we succeeded */
        u_long tcps_delack;       /* delayed acks sent */
        u_long tcps_timeoutdrop;  /* conn. dropped in rxmt timeout */
        u_long tcps_rexmttimeo;   /* retransmit timeouts */
        u_long tcps_persisttimeo; /* persist timeouts */
        u_long tcps_keeptimeo;    /* keepalive timeouts */
        u_long tcps_keepprobe;    /* keepalive probes sent */
        u_long tcps_keepdrops;    /* connections dropped in keepalive */

        u_long tcps_sndtotal;      /* total packets sent */
        u_long tcps_sndpack;       /* data packets sent */
        u_long tcps_sndbyte;       /* data bytes sent */
        u_long tcps_sndrexmitpack; /* data packets retransmitted */
        u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
        u_long tcps_sndacks;       /* ack-only packets sent */
        u_long tcps_sndprobe;      /* window probes sent */
        u_long tcps_sndurg;        /* packets sent with URG only */
        u_long tcps_sndwinup;      /* window update-only packets sent */
        u_long tcps_sndctrl;       /* control (SYN|FIN|RST) packets sent */

        u_long tcps_rcvtotal;              /* total packets received */
        u_long tcps_rcvpack;               /* packets received in sequence */
        u_long tcps_rcvbyte;               /* bytes received in sequence */
        u_long tcps_rcvbadsum;             /* packets received with ccksum errs */
        u_long tcps_rcvbadoff;             /* packets received with bad offset */
        /*	u_long	tcps_rcvshort;	*/ /* packets received too short */
        u_long tcps_rcvduppack;            /* duplicate-only packets received */
        u_long tcps_rcvdupbyte;            /* duplicate-only bytes received */
        u_long tcps_rcvpartduppack;        /* packets with some duplicate data */
        u_long tcps_rcvpartdupbyte;        /* dup. bytes in part-dup. packets */
        u_long tcps_rcvoopack;             /* out-of-order packets received */
        u_long tcps_rcvoobyte;             /* out-of-order bytes received */
        u_long tcps_rcvpackafterwin;       /* packets with data after window */
        u_long tcps_rcvbyteafterwin;       /* bytes rcvd after window */
        u_long tcps_rcvafterclose;         /* packets rcvd after "close" */
        u_long tcps_rcvwinprobe;           /* rcvd window probe packets */
        u_long tcps_rcvdupack;             /* rcvd duplicate acks */
        u_long tcps_rcvacktoomuch;         /* rcvd acks for unsent data */
        u_long tcps_rcvackpack;            /* rcvd ack packets */
        u_long tcps_rcvackbyte;            /* bytes acked by rcvd acks */
        u_long tcps_rcvwinupd;             /* rcvd window update packets */
        /*	u_long	tcps_pawsdrop;	*/ /* segments dropped due to PAWS */
        u_long tcps_predack;               /* times hdr predict ok for acks */
        u_long tcps_preddat;               /* times hdr predict ok for data pkts */
        u_long tcps_socachemiss;           /* tcp_last_so misses */
        u_long tcps_didnuttin;             /* Times tcp_output didn't do anything XXX */
};

extern struct tcpstat tcpstat; /* tcp statistics */
extern u_int32_t tcp_now;      /* for RFC 1323 timestamps */

#endif
