The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_var.h

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1993, 1994, 1995
    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  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)tcp_var.h   8.4 (Berkeley) 5/24/95
   30  * $FreeBSD: stable/7/sys/netinet/tcp_var.h 222935 2011-06-10 18:47:10Z jhb $
   31  */
   32 
   33 #ifndef _NETINET_TCP_VAR_H_
   34 #define _NETINET_TCP_VAR_H_
   35 
   36 #include <netinet/tcp.h>
   37 
   38 /*
   39  * Kernel variables for tcp.
   40  */
   41 extern int      tcp_do_rfc1323;
   42 
   43 /* TCP segment queue entry */
   44 struct tseg_qent {
   45         LIST_ENTRY(tseg_qent) tqe_q;
   46         int     tqe_len;                /* TCP segment data length */
   47         struct  tcphdr *tqe_th;         /* a pointer to tcp header */
   48         struct  mbuf    *tqe_m;         /* mbuf contains packet */
   49 };
   50 LIST_HEAD(tsegqe_head, tseg_qent);
   51 
   52 struct sackblk {
   53         tcp_seq start;          /* start seq no. of sack block */
   54         tcp_seq end;            /* end seq no. */
   55 };
   56 
   57 struct sackhole {
   58         tcp_seq start;          /* start seq no. of hole */
   59         tcp_seq end;            /* end seq no. */
   60         tcp_seq rxmit;          /* next seq. no in hole to be retransmitted */
   61         TAILQ_ENTRY(sackhole) scblink;  /* scoreboard linkage */
   62 };
   63 
   64 struct sackhint {
   65         struct sackhole *nexthole;
   66         int             sack_bytes_rexmit;
   67 };
   68 
   69 struct tcptemp {
   70         u_char  tt_ipgen[40]; /* the size must be of max ip header, now IPv6 */
   71         struct  tcphdr tt_t;
   72 };
   73 
   74 #define tcp6cb          tcpcb  /* for KAME src sync over BSD*'s */
   75 
   76 /* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
   77 #ifdef INET6
   78 #define ND6_HINT(tp)                                            \
   79 do {                                                            \
   80         if ((tp) && (tp)->t_inpcb &&                            \
   81             ((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0)         \
   82                 nd6_nud_hint(NULL, NULL, 0);                    \
   83 } while (0)
   84 #else
   85 #define ND6_HINT(tp)
   86 #endif
   87 
   88 /*
   89  * Tcp control block, one per tcp; fields:
   90  * Organized for 16 byte cacheline efficiency.
   91  */
   92 struct tcpcb {
   93         struct  tsegqe_head t_segq;     /* segment reassembly queue */
   94         int     t_segqlen;              /* segment reassembly queue length */
   95         int     t_dupacks;              /* consecutive dup acks recd */
   96 
   97         struct tcp_timer *t_timers;     /* All the TCP timers in one struct */
   98 
   99         struct  inpcb *t_inpcb;         /* back pointer to internet pcb */
  100         int     t_state;                /* state of this connection */
  101         u_int   t_flags;
  102 
  103         tcp_seq snd_una;                /* send unacknowledged */
  104         tcp_seq snd_max;                /* highest sequence number sent;
  105                                          * used to recognize retransmits
  106                                          */
  107         tcp_seq snd_nxt;                /* send next */
  108         tcp_seq snd_up;                 /* send urgent pointer */
  109 
  110         tcp_seq snd_wl1;                /* window update seg seq number */
  111         tcp_seq snd_wl2;                /* window update seg ack number */
  112         tcp_seq iss;                    /* initial send sequence number */
  113         tcp_seq irs;                    /* initial receive sequence number */
  114 
  115         tcp_seq rcv_nxt;                /* receive next */
  116         tcp_seq rcv_adv;                /* advertised window */
  117         u_long  rcv_wnd;                /* receive window */
  118         tcp_seq rcv_up;                 /* receive urgent pointer */
  119 
  120         u_long  snd_wnd;                /* send window */
  121         u_long  snd_cwnd;               /* congestion-controlled window */
  122         u_long  snd_bwnd;               /* bandwidth-controlled window */
  123         u_long  snd_ssthresh;           /* snd_cwnd size threshold for
  124                                          * for slow start exponential to
  125                                          * linear switch
  126                                          */
  127         u_long  snd_bandwidth;          /* calculated bandwidth or 0 */
  128         tcp_seq snd_recover;            /* for use in NewReno Fast Recovery */
  129 
  130         u_int   t_maxopd;               /* mss plus options */
  131 
  132         u_long  t_rcvtime;              /* inactivity time */
  133         u_long  t_starttime;            /* time connection was established */
  134         int     t_rtttime;              /* round trip time */
  135         tcp_seq t_rtseq;                /* sequence number being timed */
  136 
  137         int     t_bw_rtttime;           /* used for bandwidth calculation */
  138         tcp_seq t_bw_rtseq;             /* used for bandwidth calculation */
  139 
  140         int     t_rxtcur;               /* current retransmit value (ticks) */
  141         u_int   t_maxseg;               /* maximum segment size */
  142         int     t_srtt;                 /* smoothed round-trip time */
  143         int     t_rttvar;               /* variance in round-trip time */
  144 
  145         int     t_rxtshift;             /* log(2) of rexmt exp. backoff */
  146         u_int   t_rttmin;               /* minimum rtt allowed */
  147         u_int   t_rttbest;              /* best rtt we've seen */
  148         u_long  t_rttupdated;           /* number of times rtt sampled */
  149         u_long  max_sndwnd;             /* largest window peer has offered */
  150 
  151         int     t_softerror;            /* possible error not yet reported */
  152 /* out-of-band data */
  153         char    t_oobflags;             /* have some */
  154         char    t_iobc;                 /* input character */
  155 /* RFC 1323 variables */
  156         u_char  snd_scale;              /* window scaling for send window */
  157         u_char  rcv_scale;              /* window scaling for recv window */
  158         u_char  request_r_scale;        /* pending window scaling */
  159         u_int32_t  ts_recent;           /* timestamp echo data */
  160         u_long  ts_recent_age;          /* when last updated */
  161         u_int32_t  ts_offset;           /* our timestamp offset */
  162 
  163         tcp_seq last_ack_sent;
  164 /* experimental */
  165         u_long  snd_cwnd_prev;          /* cwnd prior to retransmit */
  166         u_long  snd_ssthresh_prev;      /* ssthresh prior to retransmit */
  167         tcp_seq snd_recover_prev;       /* snd_recover prior to retransmit */
  168         u_long  t_badrxtwin;            /* window for retransmit recovery */
  169         u_char  snd_limited;            /* segments limited transmitted */
  170 /* SACK related state */
  171         int     snd_numholes;           /* number of holes seen by sender */
  172         TAILQ_HEAD(sackhole_head, sackhole) snd_holes;
  173                                         /* SACK scoreboard (sorted) */
  174         tcp_seq snd_fack;               /* last seq number(+1) sack'd by rcv'r*/
  175         int     rcv_numsacks;           /* # distinct sack blks present */
  176         struct sackblk sackblks[MAX_SACK_BLKS]; /* seq nos. of sack blocks */
  177         tcp_seq sack_newdata;           /* New data xmitted in this recovery
  178                                            episode starts at this seq number */
  179         struct sackhint sackhint;       /* SACK scoreboard hint */
  180         int     t_rttlow;               /* smallest observerved RTT */
  181         u_int32_t       rfbuf_ts;       /* recv buffer autoscaling timestamp */
  182         int     rfbuf_cnt;              /* recv buffer autoscaling byte count */
  183         void    *t_pspare[3];           /* toe usrreqs / toepcb * / congestion algo / vimage / 1 general use */
  184         struct toe_usrreqs *t_tu;       /* offload operations vector */
  185         void    *t_toe;                 /* TOE pcb pointer */
  186 };
  187 
  188 /*
  189  * Flags and utility macros for the t_flags field.
  190  */
  191 #define TF_ACKNOW       0x000001        /* ack peer immediately */
  192 #define TF_DELACK       0x000002        /* ack, but try to delay it */
  193 #define TF_NODELAY      0x000004        /* don't delay packets to coalesce */
  194 #define TF_NOOPT        0x000008        /* don't use tcp options */
  195 #define TF_SENTFIN      0x000010        /* have sent FIN */
  196 #define TF_REQ_SCALE    0x000020        /* have/will request window scaling */
  197 #define TF_RCVD_SCALE   0x000040        /* other side has requested scaling */
  198 #define TF_REQ_TSTMP    0x000080        /* have/will request timestamps */
  199 #define TF_RCVD_TSTMP   0x000100        /* a timestamp was received in SYN */
  200 #define TF_SACK_PERMIT  0x000200        /* other side said I could SACK */
  201 #define TF_NEEDSYN      0x000400        /* send SYN (implicit state) */
  202 #define TF_NEEDFIN      0x000800        /* send FIN (implicit state) */
  203 #define TF_NOPUSH       0x001000        /* don't push */
  204 #define TF_PREVVALID    0x002000        /* saved values for bad rxmit valid */
  205 #define TF_MORETOCOME   0x010000        /* More data to be appended to sock */
  206 #define TF_LQ_OVERFLOW  0x020000        /* listen queue overflow */
  207 #define TF_LASTIDLE     0x040000        /* connection was previously idle */
  208 #define TF_RXWIN0SENT   0x080000        /* sent a receiver win 0 in response */
  209 #define TF_FASTRECOVERY 0x100000        /* in NewReno Fast Recovery */
  210 #define TF_WASFRECOVERY 0x200000        /* was in NewReno Fast Recovery */
  211 #define TF_SIGNATURE    0x400000        /* require MD5 digests (RFC2385) */
  212 #define TF_FORCEDATA    0x800000        /* force out a byte */
  213 #define TF_TSO          0x1000000       /* TSO enabled on this connection */
  214 #define TF_TOE          0x2000000       /* this connection is offloaded */
  215 
  216 #define IN_FASTRECOVERY(tp)     (tp->t_flags & TF_FASTRECOVERY)
  217 #define ENTER_FASTRECOVERY(tp)  tp->t_flags |= TF_FASTRECOVERY
  218 #define EXIT_FASTRECOVERY(tp)   tp->t_flags &= ~TF_FASTRECOVERY
  219 
  220 /*
  221  * Flags for the t_oobflags field.
  222  */
  223 #define TCPOOB_HAVEDATA 0x01
  224 #define TCPOOB_HADDATA  0x02
  225 
  226 #ifdef TCP_SIGNATURE
  227 /*
  228  * Defines which are needed by the xform_tcp module and tcp_[in|out]put
  229  * for SADB verification and lookup.
  230  */
  231 #define TCP_SIGLEN      16      /* length of computed digest in bytes */
  232 #define TCP_KEYLEN_MIN  1       /* minimum length of TCP-MD5 key */
  233 #define TCP_KEYLEN_MAX  80      /* maximum length of TCP-MD5 key */
  234 /*
  235  * Only a single SA per host may be specified at this time. An SPI is
  236  * needed in order for the KEY_ALLOCSA() lookup to work.
  237  */
  238 #define TCP_SIG_SPI     0x1000
  239 #endif /* TCP_SIGNATURE */
  240 
  241 /*
  242  * Structure to hold TCP options that are only used during segment
  243  * processing (in tcp_input), but not held in the tcpcb.
  244  * It's basically used to reduce the number of parameters
  245  * to tcp_dooptions and tcp_addoptions.
  246  * The binary order of the to_flags is relevant for packing of the
  247  * options in tcp_addoptions.
  248  */
  249 struct tcpopt {
  250         u_long          to_flags;       /* which options are present */
  251 #define TOF_MSS         0x0001          /* maximum segment size */
  252 #define TOF_SCALE       0x0002          /* window scaling */
  253 #define TOF_SACKPERM    0x0004          /* SACK permitted */
  254 #define TOF_TS          0x0010          /* timestamp */
  255 #define TOF_SIGNATURE   0x0040          /* TCP-MD5 signature option (RFC2385) */
  256 #define TOF_SACK        0x0080          /* Peer sent SACK option */
  257 #define TOF_MAXOPT      0x0100
  258         u_int32_t       to_tsval;       /* new timestamp */
  259         u_int32_t       to_tsecr;       /* reflected timestamp */
  260         u_int16_t       to_mss;         /* maximum segment size */
  261         u_int8_t        to_wscale;      /* window scaling */
  262         u_int8_t        to_nsacks;      /* number of SACK blocks */
  263         u_char          *to_sacks;      /* pointer to the first SACK blocks */
  264         u_char          *to_signature;  /* pointer to the TCP-MD5 signature */
  265 };
  266 
  267 /*
  268  * Flags for tcp_dooptions.
  269  */
  270 #define TO_SYN          0x01            /* parse SYN-only options */
  271 
  272 struct hc_metrics_lite {        /* must stay in sync with hc_metrics */
  273         u_long  rmx_mtu;        /* MTU for this path */
  274         u_long  rmx_ssthresh;   /* outbound gateway buffer limit */
  275         u_long  rmx_rtt;        /* estimated round trip time */
  276         u_long  rmx_rttvar;     /* estimated rtt variance */
  277         u_long  rmx_bandwidth;  /* estimated bandwidth */
  278         u_long  rmx_cwnd;       /* congestion window */
  279         u_long  rmx_sendpipe;   /* outbound delay-bandwidth product */
  280         u_long  rmx_recvpipe;   /* inbound delay-bandwidth product */
  281 };
  282 
  283 #ifndef _NETINET_IN_PCB_H_
  284 struct in_conninfo;
  285 #endif /* _NETINET_IN_PCB_H_ */
  286 
  287 struct tcptw {
  288         struct inpcb    *tw_inpcb;      /* XXX back pointer to internet pcb */
  289         tcp_seq         snd_nxt;
  290         tcp_seq         rcv_nxt;
  291         tcp_seq         iss;
  292         tcp_seq         irs;
  293         u_short         last_win;       /* cached window value */
  294         u_short         tw_so_options;  /* copy of so_options */
  295         struct ucred    *tw_cred;       /* user credentials */
  296         u_long          t_recent;
  297         u_int32_t       ts_offset;      /* our timestamp offset */
  298         u_long          t_starttime;
  299         int             tw_time;
  300         TAILQ_ENTRY(tcptw) tw_2msl;
  301 };
  302 
  303 #define intotcpcb(ip)   ((struct tcpcb *)(ip)->inp_ppcb)
  304 #define intotw(ip)      ((struct tcptw *)(ip)->inp_ppcb)
  305 #define sototcpcb(so)   (intotcpcb(sotoinpcb(so)))
  306 
  307 /*
  308  * The smoothed round-trip time and estimated variance
  309  * are stored as fixed point numbers scaled by the values below.
  310  * For convenience, these scales are also used in smoothing the average
  311  * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
  312  * With these scales, srtt has 3 bits to the right of the binary point,
  313  * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
  314  * binary point, and is smoothed with an ALPHA of 0.75.
  315  */
  316 #define TCP_RTT_SCALE           32      /* multiplier for srtt; 3 bits frac. */
  317 #define TCP_RTT_SHIFT           5       /* shift for srtt; 3 bits frac. */
  318 #define TCP_RTTVAR_SCALE        16      /* multiplier for rttvar; 2 bits */
  319 #define TCP_RTTVAR_SHIFT        4       /* shift for rttvar; 2 bits */
  320 #define TCP_DELTA_SHIFT         2       /* see tcp_input.c */
  321 
  322 /*
  323  * The initial retransmission should happen at rtt + 4 * rttvar.
  324  * Because of the way we do the smoothing, srtt and rttvar
  325  * will each average +1/2 tick of bias.  When we compute
  326  * the retransmit timer, we want 1/2 tick of rounding and
  327  * 1 extra tick because of +-1/2 tick uncertainty in the
  328  * firing of the timer.  The bias will give us exactly the
  329  * 1.5 tick we need.  But, because the bias is
  330  * statistical, we have to test that we don't drop below
  331  * the minimum feasible timer (which is 2 ticks).
  332  * This version of the macro adapted from a paper by Lawrence
  333  * Brakmo and Larry Peterson which outlines a problem caused
  334  * by insufficient precision in the original implementation,
  335  * which results in inappropriately large RTO values for very
  336  * fast networks.
  337  */
  338 #define TCP_REXMTVAL(tp) \
  339         max((tp)->t_rttmin, (((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT))  \
  340           + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)
  341 
  342 /*
  343  * TCP statistics.
  344  * Many of these should be kept per connection,
  345  * but that's inconvenient at the moment.
  346  */
  347 struct  tcpstat {
  348         u_long  tcps_connattempt;       /* connections initiated */
  349         u_long  tcps_accepts;           /* connections accepted */
  350         u_long  tcps_connects;          /* connections established */
  351         u_long  tcps_drops;             /* connections dropped */
  352         u_long  tcps_conndrops;         /* embryonic connections dropped */
  353         u_long  tcps_minmssdrops;       /* average minmss too low drops */
  354         u_long  tcps_closed;            /* conn. closed (includes drops) */
  355         u_long  tcps_segstimed;         /* segs where we tried to get rtt */
  356         u_long  tcps_rttupdated;        /* times we succeeded */
  357         u_long  tcps_delack;            /* delayed acks sent */
  358         u_long  tcps_timeoutdrop;       /* conn. dropped in rxmt timeout */
  359         u_long  tcps_rexmttimeo;        /* retransmit timeouts */
  360         u_long  tcps_persisttimeo;      /* persist timeouts */
  361         u_long  tcps_keeptimeo;         /* keepalive timeouts */
  362         u_long  tcps_keepprobe;         /* keepalive probes sent */
  363         u_long  tcps_keepdrops;         /* connections dropped in keepalive */
  364 
  365         u_long  tcps_sndtotal;          /* total packets sent */
  366         u_long  tcps_sndpack;           /* data packets sent */
  367         u_long  tcps_sndbyte;           /* data bytes sent */
  368         u_long  tcps_sndrexmitpack;     /* data packets retransmitted */
  369         u_long  tcps_sndrexmitbyte;     /* data bytes retransmitted */
  370         u_long  tcps_sndrexmitbad;      /* unnecessary packet retransmissions */
  371         u_long  tcps_sndacks;           /* ack-only packets sent */
  372         u_long  tcps_sndprobe;          /* window probes sent */
  373         u_long  tcps_sndurg;            /* packets sent with URG only */
  374         u_long  tcps_sndwinup;          /* window update-only packets sent */
  375         u_long  tcps_sndctrl;           /* control (SYN|FIN|RST) packets sent */
  376 
  377         u_long  tcps_rcvtotal;          /* total packets received */
  378         u_long  tcps_rcvpack;           /* packets received in sequence */
  379         u_long  tcps_rcvbyte;           /* bytes received in sequence */
  380         u_long  tcps_rcvbadsum;         /* packets received with ccksum errs */
  381         u_long  tcps_rcvbadoff;         /* packets received with bad offset */
  382         u_long  tcps_rcvmemdrop;        /* packets dropped for lack of memory */
  383         u_long  tcps_rcvshort;          /* packets received too short */
  384         u_long  tcps_rcvduppack;        /* duplicate-only packets received */
  385         u_long  tcps_rcvdupbyte;        /* duplicate-only bytes received */
  386         u_long  tcps_rcvpartduppack;    /* packets with some duplicate data */
  387         u_long  tcps_rcvpartdupbyte;    /* dup. bytes in part-dup. packets */
  388         u_long  tcps_rcvoopack;         /* out-of-order packets received */
  389         u_long  tcps_rcvoobyte;         /* out-of-order bytes received */
  390         u_long  tcps_rcvpackafterwin;   /* packets with data after window */
  391         u_long  tcps_rcvbyteafterwin;   /* bytes rcvd after window */
  392         u_long  tcps_rcvafterclose;     /* packets rcvd after "close" */
  393         u_long  tcps_rcvwinprobe;       /* rcvd window probe packets */
  394         u_long  tcps_rcvdupack;         /* rcvd duplicate acks */
  395         u_long  tcps_rcvacktoomuch;     /* rcvd acks for unsent data */
  396         u_long  tcps_rcvackpack;        /* rcvd ack packets */
  397         u_long  tcps_rcvackbyte;        /* bytes acked by rcvd acks */
  398         u_long  tcps_rcvwinupd;         /* rcvd window update packets */
  399         u_long  tcps_pawsdrop;          /* segments dropped due to PAWS */
  400         u_long  tcps_predack;           /* times hdr predict ok for acks */
  401         u_long  tcps_preddat;           /* times hdr predict ok for data pkts */
  402         u_long  tcps_pcbcachemiss;
  403         u_long  tcps_cachedrtt;         /* times cached RTT in route updated */
  404         u_long  tcps_cachedrttvar;      /* times cached rttvar updated */
  405         u_long  tcps_cachedssthresh;    /* times cached ssthresh updated */
  406         u_long  tcps_usedrtt;           /* times RTT initialized from route */
  407         u_long  tcps_usedrttvar;        /* times RTTVAR initialized from rt */
  408         u_long  tcps_usedssthresh;      /* times ssthresh initialized from rt*/
  409         u_long  tcps_persistdrop;       /* timeout in persist state */
  410         u_long  tcps_badsyn;            /* bogus SYN, e.g. premature ACK */
  411         u_long  tcps_mturesent;         /* resends due to MTU discovery */
  412         u_long  tcps_listendrop;        /* listen queue overflows */
  413         u_long  tcps_badrst;            /* ignored RSTs in the window */
  414 
  415         u_long  tcps_sc_added;          /* entry added to syncache */
  416         u_long  tcps_sc_retransmitted;  /* syncache entry was retransmitted */
  417         u_long  tcps_sc_dupsyn;         /* duplicate SYN packet */
  418         u_long  tcps_sc_dropped;        /* could not reply to packet */
  419         u_long  tcps_sc_completed;      /* successful extraction of entry */
  420         u_long  tcps_sc_bucketoverflow; /* syncache per-bucket limit hit */
  421         u_long  tcps_sc_cacheoverflow;  /* syncache cache limit hit */
  422         u_long  tcps_sc_reset;          /* RST removed entry from syncache */
  423         u_long  tcps_sc_stale;          /* timed out or listen socket gone */
  424         u_long  tcps_sc_aborted;        /* syncache entry aborted */
  425         u_long  tcps_sc_badack;         /* removed due to bad ACK */
  426         u_long  tcps_sc_unreach;        /* ICMP unreachable received */
  427         u_long  tcps_sc_zonefail;       /* zalloc() failed */
  428         u_long  tcps_sc_sendcookie;     /* SYN cookie sent */
  429         u_long  tcps_sc_recvcookie;     /* SYN cookie received */
  430 
  431         u_long  tcps_hc_added;          /* entry added to hostcache */
  432         u_long  tcps_hc_bucketoverflow; /* hostcache per bucket limit hit */
  433 
  434         u_long  tcps_finwait2_drops;    /* Drop FIN_WAIT_2 connection after time limit */
  435 
  436         /* SACK related stats */
  437         u_long  tcps_sack_recovery_episode; /* SACK recovery episodes */
  438         u_long  tcps_sack_rexmits;          /* SACK rexmit segments   */
  439         u_long  tcps_sack_rexmit_bytes;     /* SACK rexmit bytes      */
  440         u_long  tcps_sack_rcv_blocks;       /* SACK blocks (options) received */
  441         u_long  tcps_sack_send_blocks;      /* SACK blocks (options) sent     */
  442         u_long  tcps_sack_sboverflow;       /* times scoreboard overflowed */
  443 };
  444 
  445 /*
  446  * TCB structure exported to user-land via sysctl(3).
  447  * Evil hack: declare only if in_pcb.h and sys/socketvar.h have been
  448  * included.  Not all of our clients do.
  449  */
  450 #if defined(_NETINET_IN_PCB_H_) && defined(_SYS_SOCKETVAR_H_)
  451 struct  xtcpcb {
  452         size_t  xt_len;
  453         struct  inpcb   xt_inp;
  454         struct  tcpcb   xt_tp;
  455         struct  xsocket xt_socket;
  456         u_quad_t        xt_alignment_hack;
  457 };
  458 #endif
  459 
  460 /*
  461  * Names for TCP sysctl objects
  462  */
  463 #define TCPCTL_DO_RFC1323       1       /* use RFC-1323 extensions */
  464 #define TCPCTL_MSSDFLT          3       /* MSS default */
  465 #define TCPCTL_STATS            4       /* statistics (read-only) */
  466 #define TCPCTL_RTTDFLT          5       /* default RTT estimate */
  467 #define TCPCTL_KEEPIDLE         6       /* keepalive idle timer */
  468 #define TCPCTL_KEEPINTVL        7       /* interval to send keepalives */
  469 #define TCPCTL_SENDSPACE        8       /* send buffer space */
  470 #define TCPCTL_RECVSPACE        9       /* receive buffer space */
  471 #define TCPCTL_KEEPINIT         10      /* timeout for establishing syn */
  472 #define TCPCTL_PCBLIST          11      /* list of all outstanding PCBs */
  473 #define TCPCTL_DELACKTIME       12      /* time before sending delayed ACK */
  474 #define TCPCTL_V6MSSDFLT        13      /* MSS default for IPv6 */
  475 #define TCPCTL_SACK             14      /* Selective Acknowledgement,rfc 2018 */
  476 #define TCPCTL_DROP             15      /* drop tcp connection */
  477 #define TCPCTL_MAXID            16
  478 #define TCPCTL_FINWAIT2_TIMEOUT        17
  479 
  480 #define TCPCTL_NAMES { \
  481         { 0, 0 }, \
  482         { "rfc1323", CTLTYPE_INT }, \
  483         { "mssdflt", CTLTYPE_INT }, \
  484         { "stats", CTLTYPE_STRUCT }, \
  485         { "rttdflt", CTLTYPE_INT }, \
  486         { "keepidle", CTLTYPE_INT }, \
  487         { "keepintvl", CTLTYPE_INT }, \
  488         { "sendspace", CTLTYPE_INT }, \
  489         { "recvspace", CTLTYPE_INT }, \
  490         { "keepinit", CTLTYPE_INT }, \
  491         { "pcblist", CTLTYPE_STRUCT }, \
  492         { "delacktime", CTLTYPE_INT }, \
  493         { "v6mssdflt", CTLTYPE_INT }, \
  494         { "maxid", CTLTYPE_INT }, \
  495 }
  496 
  497 
  498 #ifdef _KERNEL
  499 #ifdef SYSCTL_DECL
  500 SYSCTL_DECL(_net_inet_tcp);
  501 SYSCTL_DECL(_net_inet_tcp_sack);
  502 MALLOC_DECLARE(M_TCPLOG);
  503 #endif
  504 
  505 struct sockopt;
  506 
  507 extern  struct inpcbhead tcb;           /* head of queue of active tcpcb's */
  508 extern  struct inpcbinfo tcbinfo;
  509 extern  struct tcpstat tcpstat; /* tcp statistics */
  510 extern  int tcp_log_in_vain;
  511 extern  int tcp_mssdflt;        /* XXX */
  512 extern  int tcp_minmss;
  513 extern  int tcp_delack_enabled;
  514 extern  int tcp_do_newreno;
  515 extern  int tcp_do_rfc3390;
  516 extern  int path_mtu_discovery;
  517 extern  int ss_fltsz;
  518 extern  int ss_fltsz_local;
  519 
  520 extern  int tcp_do_sack;                /* SACK enabled/disabled */
  521 extern  int tcp_sc_rst_sock_fail;       /* RST on sock alloc failure */
  522 
  523 int      tcp_addoptions(struct tcpopt *, u_char *);
  524 struct tcpcb *
  525          tcp_close(struct tcpcb *);
  526 void     tcp_discardcb(struct tcpcb *);
  527 void     tcp_twstart(struct tcpcb *);
  528 #if 0
  529 int      tcp_twrecycleable(struct tcptw *tw);
  530 #endif
  531 void     tcp_twclose(struct tcptw *_tw, int _reuse);
  532 void     tcp_ctlinput(int, struct sockaddr *, void *);
  533 int      tcp_ctloutput(struct socket *, struct sockopt *);
  534 struct tcpcb *
  535          tcp_drop(struct tcpcb *, int);
  536 void     tcp_drain(void);
  537 void     tcp_init(void);
  538 void     tcp_fini(void *);
  539 char    *tcp_log_addrs(struct in_conninfo *, struct tcphdr *, void *,
  540             const void *);
  541 char    *tcp_log_vain(struct in_conninfo *, struct tcphdr *, void *,
  542             const void *);
  543 int      tcp_reass(struct tcpcb *, struct tcphdr *, int *, struct mbuf *);
  544 void     tcp_reass_init(void);
  545 void     tcp_reass_flush(struct tcpcb *);
  546 void     tcp_input(struct mbuf *, int);
  547 u_long   tcp_maxmtu(struct in_conninfo *, int *);
  548 u_long   tcp_maxmtu6(struct in_conninfo *, int *);
  549 void     tcp_mss_update(struct tcpcb *, int, struct hc_metrics_lite *, int *);
  550 void     tcp_mss(struct tcpcb *, int);
  551 int      tcp_mssopt(struct in_conninfo *);
  552 struct inpcb *
  553          tcp_drop_syn_sent(struct inpcb *, int);
  554 struct inpcb *
  555          tcp_mtudisc(struct inpcb *, int);
  556 struct tcpcb *
  557          tcp_newtcpcb(struct inpcb *);
  558 int      tcp_output(struct tcpcb *);
  559 void     tcp_respond(struct tcpcb *, void *,
  560             struct tcphdr *, struct mbuf *, tcp_seq, tcp_seq, int);
  561 void     tcp_tw_init(void);
  562 void     tcp_tw_zone_change(void);
  563 int      tcp_twcheck(struct inpcb *, struct tcpopt *, struct tcphdr *,
  564             struct mbuf *, int);
  565 int      tcp_twrespond(struct tcptw *, int);
  566 void     tcp_setpersist(struct tcpcb *);
  567 #ifdef TCP_SIGNATURE
  568 int      tcp_signature_compute(struct mbuf *, int, int, int, u_char *, u_int);
  569 #endif
  570 void     tcp_slowtimo(void);
  571 struct tcptemp *
  572          tcpip_maketemplate(struct inpcb *);
  573 void     tcpip_fillheaders(struct inpcb *, void *, void *);
  574 void     tcp_timer_activate(struct tcpcb *, int, u_int);
  575 int      tcp_timer_active(struct tcpcb *, int);
  576 void     tcp_trace(short, short, struct tcpcb *, void *, struct tcphdr *, int);
  577 void     tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq);
  578 /*
  579  * All tcp_hc_* functions are IPv4 and IPv6 (via in_conninfo)
  580  */
  581 void     tcp_hc_init(void);
  582 void     tcp_hc_get(struct in_conninfo *, struct hc_metrics_lite *);
  583 u_long   tcp_hc_getmtu(struct in_conninfo *);
  584 void     tcp_hc_updatemtu(struct in_conninfo *, u_long);
  585 void     tcp_hc_update(struct in_conninfo *, struct hc_metrics_lite *);
  586 
  587 extern  struct pr_usrreqs tcp_usrreqs;
  588 extern  u_long tcp_sendspace;
  589 extern  u_long tcp_recvspace;
  590 tcp_seq tcp_new_isn(struct tcpcb *);
  591 
  592 void     tcp_sack_doack(struct tcpcb *, struct tcpopt *, tcp_seq);
  593 void     tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_laststart, tcp_seq rcv_lastend);
  594 void     tcp_clean_sackreport(struct tcpcb *tp);
  595 void     tcp_sack_adjust(struct tcpcb *tp);
  596 struct sackhole *tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt);
  597 void     tcp_sack_partialack(struct tcpcb *, struct tcphdr *);
  598 void     tcp_free_sackholes(struct tcpcb *tp);
  599 int      tcp_newreno(struct tcpcb *, struct tcphdr *);
  600 u_long   tcp_seq_subtract(u_long, u_long );
  601 
  602 #endif /* _KERNEL */
  603 
  604 #endif /* _NETINET_TCP_VAR_H_ */

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