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TCP_VAR.H

/*
 * 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
 */

/*
 * Kernel variables for tcp.
 */

/*
 * 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 */

      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 */
      n_long      snd_wnd;          /* send window */
/* receive sequence variables */
      n_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) */
      n_long      snd_cwnd;         /* congestion-controlled window */
      n_long      snd_ssthresh;           /* snd_cwnd size threshhold 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_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 */
      n_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
      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;
      n_long      ts_recent;        /* timestamp echo data */
      n_long      ts_recent_age;          /* when last updated */
      tcp_seq     last_ack_sent;

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

#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           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)

/* 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 {
      n_long      tcps_connattempt; /* connections initiated */
      n_long      tcps_accepts;           /* connections accepted */
      n_long      tcps_connects;          /* connections established */
      n_long      tcps_drops;       /* connections dropped */
      n_long      tcps_conndrops;         /* embryonic connections dropped */
      n_long      tcps_closed;            /* conn. closed (includes drops) */
      n_long      tcps_segstimed;         /* segs where we tried to get rtt */
      n_long      tcps_rttupdated;  /* times we succeeded */
      n_long      tcps_delack;            /* delayed acks sent */
      n_long      tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
      n_long      tcps_rexmttimeo;  /* retransmit timeouts */
      n_long      tcps_persisttimeo;      /* persist timeouts */
      n_long      tcps_keeptimeo;         /* keepalive timeouts */
      n_long      tcps_keepprobe;         /* keepalive probes sent */
      n_long      tcps_keepdrops;         /* connections dropped in keepalive */

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

      n_long      tcps_rcvtotal;          /* total packets received */
      n_long      tcps_rcvpack;           /* packets received in sequence */
      n_long      tcps_rcvbyte;           /* bytes received in sequence */
      n_long      tcps_rcvbadsum;         /* packets received with ccksum errs */
      n_long      tcps_rcvbadoff;         /* packets received with bad offset */
      n_long      tcps_rcvshort;          /* packets received too short */
      n_long      tcps_rcvduppack;  /* duplicate-only packets received */
      n_long      tcps_rcvdupbyte;  /* duplicate-only bytes received */
      n_long      tcps_rcvpartduppack;    /* packets with some duplicate data */
      n_long      tcps_rcvpartdupbyte;    /* dup. bytes in part-dup. packets */
      n_long      tcps_rcvoopack;         /* out-of-order packets received */
      n_long      tcps_rcvoobyte;         /* out-of-order bytes received */
      n_long      tcps_rcvpackafterwin;   /* packets with data after window */
      n_long      tcps_rcvbyteafterwin;   /* bytes rcvd after window */
      n_long      tcps_rcvafterclose;     /* packets rcvd after "close" */
      n_long      tcps_rcvwinprobe; /* rcvd window probe packets */
      n_long      tcps_rcvdupack;         /* rcvd duplicate acks */
      n_long      tcps_rcvacktoomuch;     /* rcvd acks for unsent data */
      n_long      tcps_rcvackpack;  /* rcvd ack packets */
      n_long      tcps_rcvackbyte;  /* bytes acked by rcvd acks */
      n_long      tcps_rcvwinupd;         /* rcvd window update packets */
      n_long      tcps_pawsdrop;          /* segments dropped due to PAWS */
      n_long      tcps_predack;           /* times hdr predict ok for acks */
      n_long      tcps_preddat;           /* times hdr predict ok for data pkts */
      n_long      tcps_pcbcachemiss;
      n_long      tcps_persistdrop; /* timeout in persist state */
      n_long      tcps_badsyn;            /* bogus SYN, e.g. premature ACK */
};

#ifdef KERNEL
struct      inpcb tcb;        /* head of queue of active tcpcb's */
struct      tcpstat tcpstat;  /* tcp statistics */
n_long      tcp_now;          /* for RFC 1323 timestamps */

int    tcp_attach __P((struct socket *));
void   tcp_canceltimers __P((struct tcpcb *));
struct tcpcb *
       tcp_close __P((struct tcpcb *));
void   tcp_ctlinput __P((int, struct sockaddr *, struct ip *));
int    tcp_ctloutput __P((int, struct socket *, int, int, struct mbuf **));
struct tcpcb *
       tcp_disconnect __P((struct tcpcb *));
struct tcpcb *
       tcp_drop __P((struct tcpcb *, int));
void   tcp_dooptions __P((struct tcpcb *,
          u_char *, int, struct tcpiphdr *, int *, n_long *, n_long *));
void   tcp_drain __P((void));
void   tcp_fasttimo __P((void));
void   tcp_init __P((void));
void   tcp_input __P((struct mbuf *, int));
int    tcp_mss __P((struct tcpcb *, u_int));
struct tcpcb *
       tcp_newtcpcb __P((struct inpcb *));
void   tcp_notify __P((struct inpcb *, int));
int    tcp_output __P((struct tcpcb *));
void   tcp_pulloutofband __P((struct socket *,
          struct tcpiphdr *, struct mbuf *));
void   tcp_quench __P((struct inpcb *, int));
int    tcp_reass __P((struct tcpcb *, struct tcpiphdr *, struct mbuf *));
void   tcp_respond __P((struct tcpcb *,
          struct tcpiphdr *, struct mbuf *, n_long, n_long, int));
void   tcp_setpersist __P((struct tcpcb *));
void   tcp_slowtimo __P((void));
struct tcpiphdr *
       tcp_template __P((struct tcpcb *));
struct tcpcb *
       tcp_timers __P((struct tcpcb *, int));
void   tcp_trace __P((int, int, struct tcpcb *, struct tcpiphdr *, int));
struct tcpcb *
       tcp_usrclosed __P((struct tcpcb *));
int    tcp_usrreq __P((struct socket *,
          int, struct mbuf *, struct mbuf *, struct mbuf *));
void   tcp_xmit_timer __P((struct tcpcb *, int));
#endif

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