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/*!\file netinet/tcp_var.h

 * Internal TCP structures and statistics.

 */

/*

 * Copyright (c) 1982, 1986, 1993, 1994, 1995

 *      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_var.h   8.4 (Berkeley) 5/24/95

 *      $Id: tcp_var.h,v 1.36 1996/09/13 23:54:03 pst Exp $

 */

#ifndef __NETINET_TCP_VAR_H

#define __NETINET_TCP_VAR_H

/*

 * Kernel variables for tcp.

 */

#ifdef TCP_AUTO

  /* AUTO_RCV_HITHRESH flush reassembly queue, drop incoming packets

   */

  #define AUTO_RCV_HITHRESH   (u_long)(0.95 * NMBCLUSTERS)

  /* AUTO_RCV_LOWTHRESH drop incoming packets

   */

  #define AUTO_RCV_LOWTHRESH  (u_long)(0.9 * NMBCLUSTERS)

  /* AUTO_SND_THRESH reduce so_snd.sb_hiwat by acked

   */

  #define AUTO_SND_THRESH     (u_long)(0.50 * NMBCLUSTERS)

#endif

#if defined(TCP_SACK) || defined(TCP_FACK)

#include <netinet/tcp_scor.h>

struct sackblock {

       tcp_seq start;

       tcp_seq end;

     };

#endif

/*

 * Tcp control block, one per tcp; fields:

 */

struct tcpcb {

        struct  tcpiphdr *seg_next;     /* sequencing queue */

        struct  tcpiphdr *seg_prev;

  /* !! struct  ipqehead segq; */       /* sequencing queue */

        int     t_state;                /* state of this connection */

        int     t_timer[TCPT_NTIMERS];  /* tcp timers */

        int     t_rxtshift;             /* log(2) of rexmt exp. backoff */

        int     t_rxtcur;               /* current retransmit value */

#ifdef TCP_FACK

        short   t_padd;                 /* filler to preserve alignment */

#else

        short   t_dupacks;              /* consecutive dup acks recd */

#endif

        u_int   t_maxseg;               /* maximum segment size */

        u_int   t_maxopd;               /* mss plus options */

        int     t_force;                /* 1 if forcing out a byte */

        u_int   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 */

#define TF_NEEDSYN      0x0400          /* send SYN (implicit state) */

#define TF_NEEDFIN      0x0800          /* send FIN (implicit state) */

#define TF_NOPUSH       0x1000          /* don't push */

#define TF_REQ_CC       0x2000          /* have/will request CC */

#define TF_RCVD_CC      0x4000          /* a CC was received in SYN */

#define TF_SENDCCNEW    0x8000          /* send CCnew instead of CC in SYN */

        struct  tcpiphdr *t_template;   /* skeletal packet for transmit */

        struct  inpcb *t_inpcb;         /* back pointer to internet pcb */

/*

 * 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_long  snd_wnd;                /* send window */

/* receive sequence variables */

        u_long  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_long  snd_cwnd;               /* congestion-controlled window */

        u_long  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.

 */

        u_int   t_idle;                 /* inactivity time */

        int     t_rtt;                  /* round trip time */

        tcp_seq t_rtseq;                /* sequence number being timed */

        int     t_srtt;                 /* smoothed round-trip time */

        int     t_rttvar;               /* variance in round-trip time */

        u_int   t_rttmin;               /* minimum rtt allowed */

        u_long  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

        int     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_long  ts_recent;              /* timestamp echo data */

        u_long  ts_recent_age;          /* when last updated */

        tcp_seq last_ack_sent;

/* RFC 1644 variables */

        tcp_cc  cc_send;                /* send connection count */

        tcp_cc  cc_recv;                /* receive connection count */

        u_long  t_duration;             /* connection duration */

/* TUBA stuff */

        caddr_t t_tuba_pcb;             /* next level down pcb for TCP over z */

/* More RTT stuff */

        u_long  t_rttupdated;           /* number of times rtt sampled */

#if defined(TCP_FACK) || defined(TCP_AUTO)

        u_short t_alt_flags;   /* experimental flags */

#define TAF_SACK_SEEN   0x0001 /* other side can send SACKs */

#define TAF_RECOVERY    0x0002 /* We are recovering from a lost segment */

#define TAF_RATEHALF    0x0004 /* We are reducing the window during recovery */

#define TAF_REPAIRED    0x0008 /* We have retransmitted something */

#define TAF_WHOLD       0x0010 /* we are in the window hold state */

#define TAF_TOGGLE      0x0020 /* divide by 2 toggle */

#define TAF_AUTO_OFF    0x0040 /* autotuning is forced off */

#endif

#if defined(TCP_SACK) || defined(TCP_FACK)

#define SACK_LIST_LEN 10

/* Needed for SACK and FACK:  */

        struct sackblock sack_list[SACK_LIST_LEN];  /*  Hack, keep 5 most recent SACKs  */

        struct scoreboard scrb;

        int snd_retran_data;

        tcp_seq recover;

#endif

#ifdef TCP_SACK

        int pipe;

#endif

#ifdef TCP_FACK

        tcp_seq snd_fack;

#define TCP_FACK_REXMTTHRESH 3    /* number of SACKs before retransmitting a block */

        u_long lothresh;                /* recovery window floor */

        u_long hithresh;                /* maximum window following recovery */

#endif

};

/*

 * Structure to hold TCP options that are only used during segment

 * processing (in tcp_input), but not held in the tcpcb.

 * It's basically used to reduce the number of parameters

 * to tcp_dooptions.

 */

struct tcpopt {

        u_long  to_flag;                /* which options are present */

#define TOF_TS          0x0001          /* timestamp */

#define TOF_CC          0x0002          /* CC and CCnew are exclusive */

#define TOF_CCNEW       0x0004

#define TOF_CCECHO      0x0008

        u_long  to_tsval;

        u_long  to_tsecr;

        tcp_cc  to_cc;          /* holds CC or CCnew */

        tcp_cc  to_ccecho;

};

/*

 * The TAO cache entry which is stored in the protocol family specific

 * portion of the route metrics.

 */

struct rmxp_tao {

        tcp_cc  tao_cc;                 /* latest CC in valid SYN */

        tcp_cc  tao_ccsent;             /* latest CC sent to peer */

        u_short tao_mssopt;             /* peer's cached MSS */

#ifdef notyet

        u_short tao_flags;              /* cache status flags */

#define TAOF_DONT       0x0001          /* peer doesn't understand rfc1644 */

#define TAOF_OK         0x0002          /* peer does understand rfc1644 */

#define TAOF_UNDEF      0               /* we don't know yet */

#endif /* notyet */

};

#define rmx_taop(r)     ((struct rmxp_tao *)(r).rmx_filler)

#define intotcpcb(ip)   ((struct tcpcb *)(ip)->inp_ppcb)

#define sototcpcb(so)   (intotcpcb(sotoinpcb(so)))

/*

 * 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           32      /* multiplier for srtt; 3 bits frac. */

#define TCP_RTT_SHIFT           5       /* shift for srtt; 3 bits frac. */

#define TCP_RTTVAR_SCALE        16      /* multiplier for rttvar; 2 bits */

#define TCP_RTTVAR_SHIFT        4       /* shift for rttvar; 2 bits */

#define TCP_DELTA_SHIFT         2       /* see tcp_input.c */

/*

 * 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 version of the macro adapted from a paper by Lawrence

 * Brakmo and Larry Peterson which outlines a problem caused

 * by insufficient precision in the original implementation,

 * which results in inappropriately large RTO values for very

 * fast networks.

 */

#define TCP_REXMTVAL(tp) \

        ((((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT))  \

          + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)

/* XXX

 * We want to avoid doing m_pullup on incoming packets but that

 * means avoiding dtom on the tcp reassembly code.  That in turn means

 * keeping an mbuf pointer in the reassembly queue (since we might

 * have a cluster).  As a quick hack, the source & destination

 * port numbers (which are no longer needed once we've located the

 * tcpcb) are overlayed with an mbuf pointer.

 */

#define REASS_MBUF(ti) (*(struct mbuf **)&((ti)->ti_t))

/*

 * 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_pcbcachemiss;

        u_long  tcps_cachedrtt;         /* times cached RTT in route updated */

        u_long  tcps_cachedrttvar;      /* times cached rttvar updated */

        u_long  tcps_cachedssthresh;    /* times cached ssthresh updated */

        u_long  tcps_usedrtt;           /* times RTT initialized from route */

        u_long  tcps_usedrttvar;        /* times RTTVAR initialized from rt */

        u_long  tcps_usedssthresh;      /* times ssthresh initialized from rt*/

        u_long  tcps_persistdrop;       /* timeout in persist state */

        u_long  tcps_badsyn;            /* bogus SYN, e.g. premature ACK */

        u_long  tcps_mturesent;         /* resends due to MTU discovery */

        u_long  tcps_listendrop;        /* listen queue overflows */

#ifdef TCP_FACK

       /* NOTE: This may break some programs that rely on this structure

        * being fixed length.

        */

        u_long  tcps_fack_recovery;     /* fack: recovery episodes */

        u_long  tcps_fack_sndpack;      /* fack: data packets sent */

        u_long  tcps_fack_sndbyte;      /* fack: data bytes sent */

        u_long  tcps_fack_sndrexmitpack;/* fack: data packets retransmitted */

        u_long  tcps_fack_sndrexmitbyte;/* fack: data bytes retransmitted */

#endif

};

/*

 * Names for TCP sysctl objects

 */

#define TCPCTL_DO_RFC1323       1       /* use RFC-1323 extensions */

#define TCPCTL_DO_RFC1644       2       /* use RFC-1644 extensions */

#define TCPCTL_MSSDFLT          3       /* MSS default */

#define TCPCTL_STATS            4       /* statistics (read-only) */

#define TCPCTL_RTTDFLT          5       /* default RTT estimate */

#define TCPCTL_KEEPIDLE         6       /* keepalive idle timer */

#define TCPCTL_KEEPINTVL        7       /* interval to send keepalives */

#define TCPCTL_SENDSPACE        8       /* send buffer space */

#define TCPCTL_RECVSPACE        9       /* receive buffer space */

#define TCPCTL_KEEPINIT         10      /* receive buffer space */

#define TCPCTL_MAXID            11

#define TCPCTL_NAMES { \

        { 0, 0 }, \

        { "rfc1323", CTLTYPE_INT }, \

        { "rfc1644", CTLTYPE_INT }, \

        { "mssdflt", CTLTYPE_INT }, \

        { "stats", CTLTYPE_STRUCT }, \

        { "rttdflt", CTLTYPE_INT }, \

        { "keepidle", CTLTYPE_INT }, \

        { "keepintvl", CTLTYPE_INT }, \

        { "sendspace", CTLTYPE_INT }, \

        { "recvspace", CTLTYPE_INT }, \

        { "keepinit", CTLTYPE_INT }, \

}

#endif