TCP_VAR.H

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/*
 * 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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