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Annotation of qemu/slirp/tcp_var.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1993, 1994
        !             3:  *     The Regents of the University of California.  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   8.3 (Berkeley) 4/10/94
        !            34:  * tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
        !            35:  */
        !            36: 
        !            37: #ifndef _TCP_VAR_H_
        !            38: #define _TCP_VAR_H_
        !            39: 
        !            40: #include "tcpip.h"
        !            41: #include "tcp_timer.h"
        !            42: 
        !            43: #if SIZEOF_CHAR_P == 4
        !            44:  typedef struct tcpiphdr *tcpiphdrp_32;
        !            45: #else
        !            46:  typedef u_int32_t tcpiphdrp_32;
        !            47: #endif
        !            48: 
        !            49: /*
        !            50:  * Tcp control block, one per tcp; fields:
        !            51:  */
        !            52: struct tcpcb {
        !            53:        tcpiphdrp_32 seg_next;  /* sequencing queue */
        !            54:        tcpiphdrp_32 seg_prev;
        !            55:        short   t_state;                /* state of this connection */
        !            56:        short   t_timer[TCPT_NTIMERS];  /* tcp timers */
        !            57:        short   t_rxtshift;             /* log(2) of rexmt exp. backoff */
        !            58:        short   t_rxtcur;               /* current retransmit value */
        !            59:        short   t_dupacks;              /* consecutive dup acks recd */
        !            60:        u_short t_maxseg;               /* maximum segment size */
        !            61:        char    t_force;                /* 1 if forcing out a byte */
        !            62:        u_short t_flags;
        !            63: #define        TF_ACKNOW       0x0001          /* ack peer immediately */
        !            64: #define        TF_DELACK       0x0002          /* ack, but try to delay it */
        !            65: #define        TF_NODELAY      0x0004          /* don't delay packets to coalesce */
        !            66: #define        TF_NOOPT        0x0008          /* don't use tcp options */
        !            67: #define        TF_SENTFIN      0x0010          /* have sent FIN */
        !            68: #define        TF_REQ_SCALE    0x0020          /* have/will request window scaling */
        !            69: #define        TF_RCVD_SCALE   0x0040          /* other side has requested scaling */
        !            70: #define        TF_REQ_TSTMP    0x0080          /* have/will request timestamps */
        !            71: #define        TF_RCVD_TSTMP   0x0100          /* a timestamp was received in SYN */
        !            72: #define        TF_SACK_PERMIT  0x0200          /* other side said I could SACK */
        !            73: 
        !            74:        /* Make it static  for now */
        !            75: /*     struct  tcpiphdr *t_template;   / * skeletal packet for transmit */
        !            76:        struct  tcpiphdr t_template;
        !            77: 
        !            78:        struct  socket *t_socket;               /* back pointer to socket */
        !            79: /*
        !            80:  * The following fields are used as in the protocol specification.
        !            81:  * See RFC783, Dec. 1981, page 21.
        !            82:  */
        !            83: /* send sequence variables */
        !            84:        tcp_seq snd_una;                /* send unacknowledged */
        !            85:        tcp_seq snd_nxt;                /* send next */
        !            86:        tcp_seq snd_up;                 /* send urgent pointer */
        !            87:        tcp_seq snd_wl1;                /* window update seg seq number */
        !            88:        tcp_seq snd_wl2;                /* window update seg ack number */
        !            89:        tcp_seq iss;                    /* initial send sequence number */
        !            90:        u_int32_t snd_wnd;              /* send window */
        !            91: /* receive sequence variables */
        !            92:        u_int32_t rcv_wnd;              /* receive window */
        !            93:        tcp_seq rcv_nxt;                /* receive next */
        !            94:        tcp_seq rcv_up;                 /* receive urgent pointer */
        !            95:        tcp_seq irs;                    /* initial receive sequence number */
        !            96: /*
        !            97:  * Additional variables for this implementation.
        !            98:  */
        !            99: /* receive variables */
        !           100:        tcp_seq rcv_adv;                /* advertised window */
        !           101: /* retransmit variables */
        !           102:        tcp_seq snd_max;                /* highest sequence number sent;
        !           103:                                         * used to recognize retransmits
        !           104:                                         */
        !           105: /* congestion control (for slow start, source quench, retransmit after loss) */
        !           106:        u_int32_t snd_cwnd;             /* congestion-controlled window */
        !           107:        u_int32_t snd_ssthresh;         /* snd_cwnd size threshold for
        !           108:                                         * for slow start exponential to
        !           109:                                         * linear switch
        !           110:                                         */
        !           111: /*
        !           112:  * transmit timing stuff.  See below for scale of srtt and rttvar.
        !           113:  * "Variance" is actually smoothed difference.
        !           114:  */
        !           115:        short   t_idle;                 /* inactivity time */
        !           116:        short   t_rtt;                  /* round trip time */
        !           117:        tcp_seq t_rtseq;                /* sequence number being timed */
        !           118:        short   t_srtt;                 /* smoothed round-trip time */
        !           119:        short   t_rttvar;               /* variance in round-trip time */
        !           120:        u_short t_rttmin;               /* minimum rtt allowed */
        !           121:        u_int32_t max_sndwnd;           /* largest window peer has offered */
        !           122: 
        !           123: /* out-of-band data */
        !           124:        char    t_oobflags;             /* have some */
        !           125:        char    t_iobc;                 /* input character */
        !           126: #define        TCPOOB_HAVEDATA 0x01
        !           127: #define        TCPOOB_HADDATA  0x02
        !           128:        short   t_softerror;            /* possible error not yet reported */
        !           129: 
        !           130: /* RFC 1323 variables */
        !           131:        u_char  snd_scale;              /* window scaling for send window */
        !           132:        u_char  rcv_scale;              /* window scaling for recv window */
        !           133:        u_char  request_r_scale;        /* pending window scaling */
        !           134:        u_char  requested_s_scale;
        !           135:        u_int32_t       ts_recent;              /* timestamp echo data */
        !           136:        u_int32_t       ts_recent_age;          /* when last updated */
        !           137:        tcp_seq last_ack_sent;
        !           138: 
        !           139: };
        !           140: 
        !           141: #define        sototcpcb(so)   ((so)->so_tcpcb)
        !           142: 
        !           143: /*
        !           144:  * The smoothed round-trip time and estimated variance
        !           145:  * are stored as fixed point numbers scaled by the values below.
        !           146:  * For convenience, these scales are also used in smoothing the average
        !           147:  * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
        !           148:  * With these scales, srtt has 3 bits to the right of the binary point,
        !           149:  * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
        !           150:  * binary point, and is smoothed with an ALPHA of 0.75.
        !           151:  */
        !           152: #define        TCP_RTT_SCALE           8       /* multiplier for srtt; 3 bits frac. */
        !           153: #define        TCP_RTT_SHIFT           3       /* shift for srtt; 3 bits frac. */
        !           154: #define        TCP_RTTVAR_SCALE        4       /* multiplier for rttvar; 2 bits */
        !           155: #define        TCP_RTTVAR_SHIFT        2       /* multiplier for rttvar; 2 bits */
        !           156: 
        !           157: /*
        !           158:  * The initial retransmission should happen at rtt + 4 * rttvar.
        !           159:  * Because of the way we do the smoothing, srtt and rttvar
        !           160:  * will each average +1/2 tick of bias.  When we compute
        !           161:  * the retransmit timer, we want 1/2 tick of rounding and
        !           162:  * 1 extra tick because of +-1/2 tick uncertainty in the
        !           163:  * firing of the timer.  The bias will give us exactly the
        !           164:  * 1.5 tick we need.  But, because the bias is
        !           165:  * statistical, we have to test that we don't drop below
        !           166:  * the minimum feasible timer (which is 2 ticks).
        !           167:  * This macro assumes that the value of TCP_RTTVAR_SCALE
        !           168:  * is the same as the multiplier for rttvar.
        !           169:  */
        !           170: #define        TCP_REXMTVAL(tp) \
        !           171:        (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
        !           172: 
        !           173: /* XXX
        !           174:  * We want to avoid doing m_pullup on incoming packets but that
        !           175:  * means avoiding dtom on the tcp reassembly code.  That in turn means
        !           176:  * keeping an mbuf pointer in the reassembly queue (since we might
        !           177:  * have a cluster).  As a quick hack, the source & destination
        !           178:  * port numbers (which are no longer needed once we've located the
        !           179:  * tcpcb) are overlayed with an mbuf pointer.
        !           180:  */
        !           181: #if SIZEOF_CHAR_P == 4
        !           182: typedef struct mbuf *mbufp_32;
        !           183: #else
        !           184: typedef u_int32_t mbufp_32;
        !           185: #endif
        !           186: #define REASS_MBUF(ti) (*(mbufp_32 *)&((ti)->ti_t))
        !           187: 
        !           188: /*
        !           189:  * TCP statistics.
        !           190:  * Many of these should be kept per connection,
        !           191:  * but that's inconvenient at the moment.
        !           192:  */
        !           193: struct tcpstat {
        !           194:        u_long  tcps_connattempt;       /* connections initiated */
        !           195:        u_long  tcps_accepts;           /* connections accepted */
        !           196:        u_long  tcps_connects;          /* connections established */
        !           197:        u_long  tcps_drops;             /* connections dropped */
        !           198:        u_long  tcps_conndrops;         /* embryonic connections dropped */
        !           199:        u_long  tcps_closed;            /* conn. closed (includes drops) */
        !           200:        u_long  tcps_segstimed;         /* segs where we tried to get rtt */
        !           201:        u_long  tcps_rttupdated;        /* times we succeeded */
        !           202:        u_long  tcps_delack;            /* delayed acks sent */
        !           203:        u_long  tcps_timeoutdrop;       /* conn. dropped in rxmt timeout */
        !           204:        u_long  tcps_rexmttimeo;        /* retransmit timeouts */
        !           205:        u_long  tcps_persisttimeo;      /* persist timeouts */
        !           206:        u_long  tcps_keeptimeo;         /* keepalive timeouts */
        !           207:        u_long  tcps_keepprobe;         /* keepalive probes sent */
        !           208:        u_long  tcps_keepdrops;         /* connections dropped in keepalive */
        !           209: 
        !           210:        u_long  tcps_sndtotal;          /* total packets sent */
        !           211:        u_long  tcps_sndpack;           /* data packets sent */
        !           212:        u_long  tcps_sndbyte;           /* data bytes sent */
        !           213:        u_long  tcps_sndrexmitpack;     /* data packets retransmitted */
        !           214:        u_long  tcps_sndrexmitbyte;     /* data bytes retransmitted */
        !           215:        u_long  tcps_sndacks;           /* ack-only packets sent */
        !           216:        u_long  tcps_sndprobe;          /* window probes sent */
        !           217:        u_long  tcps_sndurg;            /* packets sent with URG only */
        !           218:        u_long  tcps_sndwinup;          /* window update-only packets sent */
        !           219:        u_long  tcps_sndctrl;           /* control (SYN|FIN|RST) packets sent */
        !           220: 
        !           221:        u_long  tcps_rcvtotal;          /* total packets received */
        !           222:        u_long  tcps_rcvpack;           /* packets received in sequence */
        !           223:        u_long  tcps_rcvbyte;           /* bytes received in sequence */
        !           224:        u_long  tcps_rcvbadsum;         /* packets received with ccksum errs */
        !           225:        u_long  tcps_rcvbadoff;         /* packets received with bad offset */
        !           226: /*     u_long  tcps_rcvshort;  */      /* packets received too short */
        !           227:        u_long  tcps_rcvduppack;        /* duplicate-only packets received */
        !           228:        u_long  tcps_rcvdupbyte;        /* duplicate-only bytes received */
        !           229:        u_long  tcps_rcvpartduppack;    /* packets with some duplicate data */
        !           230:        u_long  tcps_rcvpartdupbyte;    /* dup. bytes in part-dup. packets */
        !           231:        u_long  tcps_rcvoopack;         /* out-of-order packets received */
        !           232:        u_long  tcps_rcvoobyte;         /* out-of-order bytes received */
        !           233:        u_long  tcps_rcvpackafterwin;   /* packets with data after window */
        !           234:        u_long  tcps_rcvbyteafterwin;   /* bytes rcvd after window */
        !           235:        u_long  tcps_rcvafterclose;     /* packets rcvd after "close" */
        !           236:        u_long  tcps_rcvwinprobe;       /* rcvd window probe packets */
        !           237:        u_long  tcps_rcvdupack;         /* rcvd duplicate acks */
        !           238:        u_long  tcps_rcvacktoomuch;     /* rcvd acks for unsent data */
        !           239:        u_long  tcps_rcvackpack;        /* rcvd ack packets */
        !           240:        u_long  tcps_rcvackbyte;        /* bytes acked by rcvd acks */
        !           241:        u_long  tcps_rcvwinupd;         /* rcvd window update packets */
        !           242: /*     u_long  tcps_pawsdrop;  */      /* segments dropped due to PAWS */
        !           243:        u_long  tcps_predack;           /* times hdr predict ok for acks */
        !           244:        u_long  tcps_preddat;           /* times hdr predict ok for data pkts */
        !           245:        u_long  tcps_socachemiss;       /* tcp_last_so misses */
        !           246:        u_long  tcps_didnuttin;         /* Times tcp_output didn't do anything XXX */
        !           247: };
        !           248: 
        !           249: extern struct  tcpstat tcpstat;        /* tcp statistics */
        !           250: extern u_int32_t       tcp_now;                /* for RFC 1323 timestamps */
        !           251: 
        !           252: #endif

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