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Annotation of Net2/netinet/tcp_var.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. All advertising materials mentioning features or use of this software
        !            14:  *    must display the following acknowledgement:
        !            15:  *     This product includes software developed by the University of
        !            16:  *     California, Berkeley and its contributors.
        !            17:  * 4. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  *
        !            33:  *     @(#)tcp_var.h   7.10 (Berkeley) 6/28/90
        !            34:  */
        !            35: 
        !            36: /*
        !            37:  * Kernel variables for tcp.
        !            38:  */
        !            39: 
        !            40: /*
        !            41:  * Tcp control block, one per tcp; fields:
        !            42:  */
        !            43: struct tcpcb {
        !            44:        struct  tcpiphdr *seg_next;     /* sequencing queue */
        !            45:        struct  tcpiphdr *seg_prev;
        !            46:        short   t_state;                /* state of this connection */
        !            47:        short   t_timer[TCPT_NTIMERS];  /* tcp timers */
        !            48:        short   t_rxtshift;             /* log(2) of rexmt exp. backoff */
        !            49:        short   t_rxtcur;               /* current retransmit value */
        !            50:        short   t_dupacks;              /* consecutive dup acks recd */
        !            51:        u_short t_maxseg;               /* maximum segment size */
        !            52:        char    t_force;                /* 1 if forcing out a byte */
        !            53:        u_char  t_flags;
        !            54: #define        TF_ACKNOW       0x01            /* ack peer immediately */
        !            55: #define        TF_DELACK       0x02            /* ack, but try to delay it */
        !            56: #define        TF_NODELAY      0x04            /* don't delay packets to coalesce */
        !            57: #define        TF_NOOPT        0x08            /* don't use tcp options */
        !            58: #define        TF_SENTFIN      0x10            /* have sent FIN */
        !            59:        struct  tcpiphdr *t_template;   /* skeletal packet for transmit */
        !            60:        struct  inpcb *t_inpcb;         /* back pointer to internet pcb */
        !            61: /*
        !            62:  * The following fields are used as in the protocol specification.
        !            63:  * See RFC783, Dec. 1981, page 21.
        !            64:  */
        !            65: /* send sequence variables */
        !            66:        tcp_seq snd_una;                /* send unacknowledged */
        !            67:        tcp_seq snd_nxt;                /* send next */
        !            68:        tcp_seq snd_up;                 /* send urgent pointer */
        !            69:        tcp_seq snd_wl1;                /* window update seg seq number */
        !            70:        tcp_seq snd_wl2;                /* window update seg ack number */
        !            71:        tcp_seq iss;                    /* initial send sequence number */
        !            72:        u_short snd_wnd;                /* send window */
        !            73: /* receive sequence variables */
        !            74:        u_short rcv_wnd;                /* receive window */
        !            75:        tcp_seq rcv_nxt;                /* receive next */
        !            76:        tcp_seq rcv_up;                 /* receive urgent pointer */
        !            77:        tcp_seq irs;                    /* initial receive sequence number */
        !            78: /*
        !            79:  * Additional variables for this implementation.
        !            80:  */
        !            81: /* receive variables */
        !            82:        tcp_seq rcv_adv;                /* advertised window */
        !            83: /* retransmit variables */
        !            84:        tcp_seq snd_max;                /* highest sequence number sent;
        !            85:                                         * used to recognize retransmits
        !            86:                                         */
        !            87: /* congestion control (for slow start, source quench, retransmit after loss) */
        !            88:        u_short snd_cwnd;               /* congestion-controlled window */
        !            89:        u_short snd_ssthresh;           /* snd_cwnd size threshhold for
        !            90:                                         * for slow start exponential to
        !            91:                                         * linear switch
        !            92:                                         */
        !            93: /*
        !            94:  * transmit timing stuff.  See below for scale of srtt and rttvar.
        !            95:  * "Variance" is actually smoothed difference.
        !            96:  */
        !            97:        short   t_idle;                 /* inactivity time */
        !            98:        short   t_rtt;                  /* round trip time */
        !            99:        tcp_seq t_rtseq;                /* sequence number being timed */
        !           100:        short   t_srtt;                 /* smoothed round-trip time */
        !           101:        short   t_rttvar;               /* variance in round-trip time */
        !           102:        u_short t_rttmin;               /* minimum rtt allowed */
        !           103:        u_short max_sndwnd;             /* largest window peer has offered */
        !           104: 
        !           105: /* out-of-band data */
        !           106:        char    t_oobflags;             /* have some */
        !           107:        char    t_iobc;                 /* input character */
        !           108: #define        TCPOOB_HAVEDATA 0x01
        !           109: #define        TCPOOB_HADDATA  0x02
        !           110:        short   t_softerror;            /* possible error not yet reported */
        !           111: };
        !           112: 
        !           113: #define        intotcpcb(ip)   ((struct tcpcb *)(ip)->inp_ppcb)
        !           114: #define        sototcpcb(so)   (intotcpcb(sotoinpcb(so)))
        !           115: 
        !           116: /*
        !           117:  * The smoothed round-trip time and estimated variance
        !           118:  * are stored as fixed point numbers scaled by the values below.
        !           119:  * For convenience, these scales are also used in smoothing the average
        !           120:  * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
        !           121:  * With these scales, srtt has 3 bits to the right of the binary point,
        !           122:  * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
        !           123:  * binary point, and is smoothed with an ALPHA of 0.75.
        !           124:  */
        !           125: #define        TCP_RTT_SCALE           8       /* multiplier for srtt; 3 bits frac. */
        !           126: #define        TCP_RTT_SHIFT           3       /* shift for srtt; 3 bits frac. */
        !           127: #define        TCP_RTTVAR_SCALE        4       /* multiplier for rttvar; 2 bits */
        !           128: #define        TCP_RTTVAR_SHIFT        2       /* multiplier for rttvar; 2 bits */
        !           129: 
        !           130: /*
        !           131:  * The initial retransmission should happen at rtt + 4 * rttvar.
        !           132:  * Because of the way we do the smoothing, srtt and rttvar
        !           133:  * will each average +1/2 tick of bias.  When we compute
        !           134:  * the retransmit timer, we want 1/2 tick of rounding and
        !           135:  * 1 extra tick because of +-1/2 tick uncertainty in the
        !           136:  * firing of the timer.  The bias will give us exactly the
        !           137:  * 1.5 tick we need.  But, because the bias is
        !           138:  * statistical, we have to test that we don't drop below
        !           139:  * the minimum feasible timer (which is 2 ticks).
        !           140:  * This macro assumes that the value of TCP_RTTVAR_SCALE
        !           141:  * is the same as the multiplier for rttvar.
        !           142:  */
        !           143: #define        TCP_REXMTVAL(tp) \
        !           144:        (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
        !           145: 
        !           146: /* XXX
        !           147:  * We want to avoid doing m_pullup on incoming packets but that
        !           148:  * means avoiding dtom on the tcp reassembly code.  That in turn means
        !           149:  * keeping an mbuf pointer in the reassembly queue (since we might
        !           150:  * have a cluster).  As a quick hack, the source & destination
        !           151:  * port numbers (which are no longer needed once we've located the
        !           152:  * tcpcb) are overlayed with an mbuf pointer.
        !           153:  */
        !           154: #define REASS_MBUF(ti) (*(struct mbuf **)&((ti)->ti_t))
        !           155: 
        !           156: /*
        !           157:  * TCP statistics.
        !           158:  * Many of these should be kept per connection,
        !           159:  * but that's inconvenient at the moment.
        !           160:  */
        !           161: struct tcpstat {
        !           162:        u_long  tcps_connattempt;       /* connections initiated */
        !           163:        u_long  tcps_accepts;           /* connections accepted */
        !           164:        u_long  tcps_connects;          /* connections established */
        !           165:        u_long  tcps_drops;             /* connections dropped */
        !           166:        u_long  tcps_conndrops;         /* embryonic connections dropped */
        !           167:        u_long  tcps_closed;            /* conn. closed (includes drops) */
        !           168:        u_long  tcps_segstimed;         /* segs where we tried to get rtt */
        !           169:        u_long  tcps_rttupdated;        /* times we succeeded */
        !           170:        u_long  tcps_delack;            /* delayed acks sent */
        !           171:        u_long  tcps_timeoutdrop;       /* conn. dropped in rxmt timeout */
        !           172:        u_long  tcps_rexmttimeo;        /* retransmit timeouts */
        !           173:        u_long  tcps_persisttimeo;      /* persist timeouts */
        !           174:        u_long  tcps_keeptimeo;         /* keepalive timeouts */
        !           175:        u_long  tcps_keepprobe;         /* keepalive probes sent */
        !           176:        u_long  tcps_keepdrops;         /* connections dropped in keepalive */
        !           177: 
        !           178:        u_long  tcps_sndtotal;          /* total packets sent */
        !           179:        u_long  tcps_sndpack;           /* data packets sent */
        !           180:        u_long  tcps_sndbyte;           /* data bytes sent */
        !           181:        u_long  tcps_sndrexmitpack;     /* data packets retransmitted */
        !           182:        u_long  tcps_sndrexmitbyte;     /* data bytes retransmitted */
        !           183:        u_long  tcps_sndacks;           /* ack-only packets sent */
        !           184:        u_long  tcps_sndprobe;          /* window probes sent */
        !           185:        u_long  tcps_sndurg;            /* packets sent with URG only */
        !           186:        u_long  tcps_sndwinup;          /* window update-only packets sent */
        !           187:        u_long  tcps_sndctrl;           /* control (SYN|FIN|RST) packets sent */
        !           188: 
        !           189:        u_long  tcps_rcvtotal;          /* total packets received */
        !           190:        u_long  tcps_rcvpack;           /* packets received in sequence */
        !           191:        u_long  tcps_rcvbyte;           /* bytes received in sequence */
        !           192:        u_long  tcps_rcvbadsum;         /* packets received with ccksum errs */
        !           193:        u_long  tcps_rcvbadoff;         /* packets received with bad offset */
        !           194:        u_long  tcps_rcvshort;          /* packets received too short */
        !           195:        u_long  tcps_rcvduppack;        /* duplicate-only packets received */
        !           196:        u_long  tcps_rcvdupbyte;        /* duplicate-only bytes received */
        !           197:        u_long  tcps_rcvpartduppack;    /* packets with some duplicate data */
        !           198:        u_long  tcps_rcvpartdupbyte;    /* dup. bytes in part-dup. packets */
        !           199:        u_long  tcps_rcvoopack;         /* out-of-order packets received */
        !           200:        u_long  tcps_rcvoobyte;         /* out-of-order bytes received */
        !           201:        u_long  tcps_rcvpackafterwin;   /* packets with data after window */
        !           202:        u_long  tcps_rcvbyteafterwin;   /* bytes rcvd after window */
        !           203:        u_long  tcps_rcvafterclose;     /* packets rcvd after "close" */
        !           204:        u_long  tcps_rcvwinprobe;       /* rcvd window probe packets */
        !           205:        u_long  tcps_rcvdupack;         /* rcvd duplicate acks */
        !           206:        u_long  tcps_rcvacktoomuch;     /* rcvd acks for unsent data */
        !           207:        u_long  tcps_rcvackpack;        /* rcvd ack packets */
        !           208:        u_long  tcps_rcvackbyte;        /* bytes acked by rcvd acks */
        !           209:        u_long  tcps_rcvwinupd;         /* rcvd window update packets */
        !           210: };
        !           211: 
        !           212: #ifdef KERNEL
        !           213: struct inpcb tcb;              /* head of queue of active tcpcb's */
        !           214: struct tcpstat tcpstat;        /* tcp statistics */
        !           215: struct tcpiphdr *tcp_template();
        !           216: struct tcpcb *tcp_close(), *tcp_drop();
        !           217: struct tcpcb *tcp_timers(), *tcp_disconnect(), *tcp_usrclosed();
        !           218: #endif

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