FreeBSD/Linux Kernel Cross Reference
sys/netinet/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
     * $FreeBSD: src/sys/netinet/tcp_var.h,v 1.36.2.2 1999/09/05 08:18:46 peter Exp $
     */
    
    #ifndef _NETINET_TCP_VAR_H_
    #define _NETINET_TCP_VAR_H_
    /*
     * Kernel variables for tcp.
     */
    
    /*
     * Tcp control block, one per tcp; fields:
     */
    struct tcpcb {
            struct  tcpiphdr *seg_next;     /* sequencing queue */
            struct  tcpiphdr *seg_prev;
            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 */
            int     t_dupacks;              /* consecutive dup acks recd */
            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 */
   };
   
   /*
    * 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) \
           max((tp)->t_rttmin, (((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 */
   };
   
   /*
    * 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 }, \
   }
   
   #ifdef KERNEL
   extern  struct inpcbhead tcb;           /* head of queue of active tcpcb's */
   extern  struct inpcbinfo tcbinfo;
   extern  struct tcpstat tcpstat; /* tcp statistics */
   extern  int tcp_mssdflt;        /* XXX */
   extern  u_long tcp_now;         /* for RFC 1323 timestamps */
   
   void     tcp_canceltimers __P((struct tcpcb *));
   struct tcpcb *
            tcp_close __P((struct tcpcb *));
   void     tcp_ctlinput __P((int, struct sockaddr *, void *));
   int      tcp_ctloutput __P((int, struct socket *, int, int, struct mbuf **));
   struct tcpcb *
            tcp_drop __P((struct tcpcb *, int));
   void     tcp_drain __P((void));
   void     tcp_fasttimo __P((void));
   struct rmxp_tao *
            tcp_gettaocache __P((struct inpcb *));
   void     tcp_init __P((void));
   void     tcp_input __P((struct mbuf *, int));
   void     tcp_mss __P((struct tcpcb *, int));
   int      tcp_mssopt __P((struct tcpcb *));
   void     tcp_mtudisc __P((struct inpcb *, int));
   struct tcpcb *
            tcp_newtcpcb __P((struct inpcb *));
   int      tcp_output __P((struct tcpcb *));
   void     tcp_quench __P((struct inpcb *, int));
   void     tcp_respond __P((struct tcpcb *,
               struct tcpiphdr *, struct mbuf *, u_long, u_long, int));
   struct rtentry *
            tcp_rtlookup __P((struct inpcb *));
   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));
   
   extern  struct pr_usrreqs tcp_usrreqs;
   extern  u_long tcp_sendspace;
   extern  u_long tcp_recvspace;
   
   #endif /* KERNEL */
   
   #endif /* _NETINET_TCP_VAR_H_ */

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