bsd/netinet/tcp_var.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1982, 1986, 1993, 1994, 1995
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  *      @(#)tcp_var.h   8.4 (Berkeley) 5/24/95
  55  */
  56
  57 #ifndef _NETINET_TCP_VAR_H_
  58 #define _NETINET_TCP_VAR_H_
  59 #define N_TIME_WAIT_SLOTS   128                /* must be power of 2 */
  60
  61 /*
  62  * Ip (reassembly or sequence) queue structures.
  63  *
  64  * XXX -- The following explains why the ipqe_m field is here, for TCP's use:
  65  * We want to avoid doing m_pullup on incoming packets but that
  66  * means avoiding dtom on the tcp reassembly code.  That in turn means
  67  * keeping an mbuf pointer in the reassembly queue (since we might
  68  * have a cluster).  As a quick hack, the source & destination
  69  * port numbers (which are no longer needed once we've located the
  70  * tcpcb) are overlayed with an mbuf pointer.
  71  */
  72 LIST_HEAD(ipqehead, ipqent);
  73 struct ipqent {
  74         LIST_ENTRY(ipqent) ipqe_q;
  75         union {
  76                 struct ip       *_ip;
  77 #if INET6
  78                 struct ipv6     *_ip6;
  79 #endif
  80                 struct tcpiphdr *_tcp;
  81         } _ipqe_u1;
  82         struct mbuf     *ipqe_m;        /* mbuf contains packet */
  83         u_int8_t        ipqe_mff;       /* for IP fragmentation */
  84 };
  85 #define ipqe_ip         _ipqe_u1._ip
  86 #if INET6
  87 #define ipqe_ip6        _ipqe_u1._ip6
  88 #endif
  89 #define ipqe_tcp        _ipqe_u1._tcp
  90 #define tcp6cb          tcpcb  /* for KAME src sync over BSD*'s */
  91
  92 #define TCP_DELACK_BITSET(hash_elem)\
  93 delack_bitmask[((hash_elem) >> 5)] |= 1 << ((hash_elem) & 0x1F)
  94
  95 #define DELACK_BITMASK_ON     1
  96 #define DELACK_BITMASK_THRESH 300
  97
  98 /*
  99  * Kernel variables for tcp.
 100  */
 101
 102 /*
 103  * Tcp control block, one per tcp; fields:
 104  * Organized for 16 byte cacheline efficiency.
 105  */
 106 struct tcpcb {
 107         struct ipqehead segq;           /* sequencing queue */
 108         int     t_dupacks;              /* consecutive dup acks recd */
 109         struct tcptemp  *t_template;    /* skeletal packet for transmit */
 110
 111         int     t_timer[TCPT_NTIMERS];  /* tcp timers */
 112
 113         struct  inpcb *t_inpcb;         /* back pointer to internet pcb */
 114         int     t_state;                /* state of this connection */
 115         u_int   t_flags;
 116 #define TF_ACKNOW       0x00001         /* ack peer immediately */
 117 #define TF_DELACK       0x00002         /* ack, but try to delay it */
 118 #define TF_NODELAY      0x00004         /* don't delay packets to coalesce */
 119 #define TF_NOOPT        0x00008         /* don't use tcp options */
 120 #define TF_SENTFIN      0x00010         /* have sent FIN */
 121 #define TF_REQ_SCALE    0x00020         /* have/will request window scaling */
 122 #define TF_RCVD_SCALE   0x00040         /* other side has requested scaling */
 123 #define TF_REQ_TSTMP    0x00080         /* have/will request timestamps */
 124 #define TF_RCVD_TSTMP   0x00100         /* a timestamp was received in SYN */
 125 #define TF_SACK_PERMIT  0x00200         /* other side said I could SACK */
 126 #define TF_NEEDSYN      0x00400         /* send SYN (implicit state) */
 127 #define TF_NEEDFIN      0x00800         /* send FIN (implicit state) */
 128 #define TF_NOPUSH       0x01000         /* don't push */
 129 #define TF_REQ_CC       0x02000         /* have/will request CC */
 130 #define TF_RCVD_CC      0x04000         /* a CC was received in SYN */
 131 #define TF_SENDCCNEW    0x08000         /* send CCnew instead of CC in SYN */
 132 #define TF_MORETOCOME   0x10000         /* More data to be appended to sock */
 133         int     t_force;                /* 1 if forcing out a byte */
 134
 135         tcp_seq snd_una;                /* send unacknowledged */
 136         tcp_seq snd_max;                /* highest sequence number sent;
 137                                          * used to recognize retransmits
 138                                          */
 139         tcp_seq snd_nxt;                /* send next */
 140         tcp_seq snd_up;                 /* send urgent pointer */
 141
 142         tcp_seq snd_wl1;                /* window update seg seq number */
 143         tcp_seq snd_wl2;                /* window update seg ack number */
 144         tcp_seq iss;                    /* initial send sequence number */
 145         tcp_seq irs;                    /* initial receive sequence number */
 146
 147         tcp_seq rcv_nxt;                /* receive next */
 148         tcp_seq rcv_adv;                /* advertised window */
 149         u_long  rcv_wnd;                /* receive window */
 150         tcp_seq rcv_up;                 /* receive urgent pointer */
 151
 152         u_long  snd_wnd;                /* send window */
 153         u_long  snd_cwnd;               /* congestion-controlled window */
 154         u_long  snd_ssthresh;           /* snd_cwnd size threshold for
 155                                          * for slow start exponential to
 156                                          * linear switch
 157                                          */
 158         u_int   t_maxopd;               /* mss plus options */
 159
 160         u_int   t_idle;                 /* inactivity time */
 161         u_long  t_duration;             /* connection duration */
 162         int     t_rtt;                  /* round trip time */
 163         tcp_seq t_rtseq;                /* sequence number being timed */
 164
 165         int     t_rxtcur;               /* current retransmit value */
 166         u_int   t_maxseg;               /* maximum segment size */
 167         int     t_srtt;                 /* smoothed round-trip time */
 168         int     t_rttvar;               /* variance in round-trip time */
 169
 170         int     t_rxtshift;             /* log(2) of rexmt exp. backoff */
 171         u_int   t_rttmin;               /* minimum rtt allowed */
 172         u_long  t_rttupdated;           /* number of times rtt sampled */
 173         u_long  max_sndwnd;             /* largest window peer has offered */
 174
 175         int     t_softerror;            /* possible error not yet reported */
 176 /* out-of-band data */
 177         char    t_oobflags;             /* have some */
 178         char    t_iobc;                 /* input character */
 179 #define TCPOOB_HAVEDATA 0x01
 180 #define TCPOOB_HADDATA  0x02
 181 /* RFC 1323 variables */
 182         u_char  snd_scale;              /* window scaling for send window */
 183         u_char  rcv_scale;              /* window scaling for recv window */
 184         u_char  request_r_scale;        /* pending window scaling */
 185         u_char  requested_s_scale;
 186         u_long  ts_recent;              /* timestamp echo data */
 187
 188         u_long  ts_recent_age;          /* when last updated */
 189         tcp_seq last_ack_sent;
 190 /* RFC 1644 variables */
 191         tcp_cc  cc_send;                /* send connection count */
 192         tcp_cc  cc_recv;                /* receive connection count */
 193 };
 194
 195 /*
 196  * Structure to hold TCP options that are only used during segment
 197  * processing (in tcp_input), but not held in the tcpcb.
 198  * It's basically used to reduce the number of parameters
 199  * to tcp_dooptions.
 200  */
 201 struct tcpopt {
 202         u_long  to_flag;                /* which options are present */
 203 #define TOF_TS          0x0001          /* timestamp */
 204 #define TOF_CC          0x0002          /* CC and CCnew are exclusive */
 205 #define TOF_CCNEW       0x0004
 206 #define TOF_CCECHO      0x0008
 207         u_long  to_tsval;
 208         u_long  to_tsecr;
 209         tcp_cc  to_cc;          /* holds CC or CCnew */
 210         tcp_cc  to_ccecho;
 211         u_short to_maxseg;
 212 };
 213
 214 /*
 215  * The TAO cache entry which is stored in the protocol family specific
 216  * portion of the route metrics.
 217  */
 218 struct rmxp_tao {
 219         tcp_cc  tao_cc;                 /* latest CC in valid SYN */
 220         tcp_cc  tao_ccsent;             /* latest CC sent to peer */
 221         u_short tao_mssopt;             /* peer's cached MSS */
 222 #ifdef notyet
 223         u_short tao_flags;              /* cache status flags */
 224 #define TAOF_DONT       0x0001          /* peer doesn't understand rfc1644 */
 225 #define TAOF_OK         0x0002          /* peer does understand rfc1644 */
 226 #define TAOF_UNDEF      0               /* we don't know yet */
 227 #endif /* notyet */
 228 };
 229 #define rmx_taop(r)     ((struct rmxp_tao *)(r).rmx_filler)
 230
 231 #define intotcpcb(ip)   ((struct tcpcb *)(ip)->inp_ppcb)
 232 #define sototcpcb(so)   (intotcpcb(sotoinpcb(so)))
 233
 234 /*
 235  * The smoothed round-trip time and estimated variance
 236  * are stored as fixed point numbers scaled by the values below.
 237  * For convenience, these scales are also used in smoothing the average
 238  * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
 239  * With these scales, srtt has 3 bits to the right of the binary point,
 240  * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
 241  * binary point, and is smoothed with an ALPHA of 0.75.
 242  */
 243 #define TCP_RTT_SCALE           32      /* multiplier for srtt; 3 bits frac. */
 244 #define TCP_RTT_SHIFT           5       /* shift for srtt; 3 bits frac. */
 245 #define TCP_RTTVAR_SCALE        16      /* multiplier for rttvar; 2 bits */
 246 #define TCP_RTTVAR_SHIFT        4       /* shift for rttvar; 2 bits */
 247 #define TCP_DELTA_SHIFT         2       /* see tcp_input.c */
 248
 249 /*
 250  * The initial retransmission should happen at rtt + 4 * rttvar.
 251  * Because of the way we do the smoothing, srtt and rttvar
 252  * will each average +1/2 tick of bias.  When we compute
 253  * the retransmit timer, we want 1/2 tick of rounding and
 254  * 1 extra tick because of +-1/2 tick uncertainty in the
 255  * firing of the timer.  The bias will give us exactly the
 256  * 1.5 tick we need.  But, because the bias is
 257  * statistical, we have to test that we don't drop below
 258  * the minimum feasible timer (which is 2 ticks).
 259  * This version of the macro adapted from a paper by Lawrence
 260  * Brakmo and Larry Peterson which outlines a problem caused
 261  * by insufficient precision in the original implementation,
 262  * which results in inappropriately large RTO values for very
 263  * fast networks.
 264  */
 265 #define TCP_REXMTVAL(tp) \
 266         max((tp)->t_rttmin, (((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT))  \
 267           + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)
 268
 269 /*
 270  * TCP statistics.
 271  * Many of these should be kept per connection,
 272  * but that's inconvenient at the moment.
 273  */
 274 struct  tcpstat {
 275         u_long  tcps_connattempt;       /* connections initiated */
 276         u_long  tcps_accepts;           /* connections accepted */
 277         u_long  tcps_connects;          /* connections established */
 278         u_long  tcps_drops;             /* connections dropped */
 279         u_long  tcps_conndrops;         /* embryonic connections dropped */
 280         u_long  tcps_closed;            /* conn. closed (includes drops) */
 281         u_long  tcps_segstimed;         /* segs where we tried to get rtt */
 282         u_long  tcps_rttupdated;        /* times we succeeded */
 283         u_long  tcps_delack;            /* delayed acks sent */
 284         u_long  tcps_timeoutdrop;       /* conn. dropped in rxmt timeout */
 285         u_long  tcps_rexmttimeo;        /* retransmit timeouts */
 286         u_long  tcps_persisttimeo;      /* persist timeouts */
 287         u_long  tcps_keeptimeo;         /* keepalive timeouts */
 288         u_long  tcps_keepprobe;         /* keepalive probes sent */
 289         u_long  tcps_keepdrops;         /* connections dropped in keepalive */
 290
 291         u_long  tcps_sndtotal;          /* total packets sent */
 292         u_long  tcps_sndpack;           /* data packets sent */
 293         u_long  tcps_sndbyte;           /* data bytes sent */
 294         u_long  tcps_sndrexmitpack;     /* data packets retransmitted */
 295         u_long  tcps_sndrexmitbyte;     /* data bytes retransmitted */
 296         u_long  tcps_sndacks;           /* ack-only packets sent */
 297         u_long  tcps_sndprobe;          /* window probes sent */
 298         u_long  tcps_sndurg;            /* packets sent with URG only */
 299         u_long  tcps_sndwinup;          /* window update-only packets sent */
 300         u_long  tcps_sndctrl;           /* control (SYN|FIN|RST) packets sent */
 301
 302         u_long  tcps_rcvtotal;          /* total packets received */
 303         u_long  tcps_rcvpack;           /* packets received in sequence */
 304         u_long  tcps_rcvbyte;           /* bytes received in sequence */
 305         u_long  tcps_rcvbadsum;         /* packets received with ccksum errs */
 306         u_long  tcps_rcvbadoff;         /* packets received with bad offset */
 307         u_long  tcps_rcvmemdrop;        /* packets dropped for lack of memory */
 308         u_long  tcps_rcvshort;          /* packets received too short */
 309         u_long  tcps_rcvduppack;        /* duplicate-only packets received */
 310         u_long  tcps_rcvdupbyte;        /* duplicate-only bytes received */
 311         u_long  tcps_rcvpartduppack;    /* packets with some duplicate data */
 312         u_long  tcps_rcvpartdupbyte;    /* dup. bytes in part-dup. packets */
 313         u_long  tcps_rcvoopack;         /* out-of-order packets received */
 314         u_long  tcps_rcvoobyte;         /* out-of-order bytes received */
 315         u_long  tcps_rcvpackafterwin;   /* packets with data after window */
 316         u_long  tcps_rcvbyteafterwin;   /* bytes rcvd after window */
 317         u_long  tcps_rcvafterclose;     /* packets rcvd after "close" */
 318         u_long  tcps_rcvwinprobe;       /* rcvd window probe packets */
 319         u_long  tcps_rcvdupack;         /* rcvd duplicate acks */
 320         u_long  tcps_rcvacktoomuch;     /* rcvd acks for unsent data */
 321         u_long  tcps_rcvackpack;        /* rcvd ack packets */
 322         u_long  tcps_rcvackbyte;        /* bytes acked by rcvd acks */
 323         u_long  tcps_rcvwinupd;         /* rcvd window update packets */
 324         u_long  tcps_pawsdrop;          /* segments dropped due to PAWS */
 325         u_long  tcps_predack;           /* times hdr predict ok for acks */
 326         u_long  tcps_preddat;           /* times hdr predict ok for data pkts */
 327         u_long  tcps_pcbcachemiss;
 328         u_long  tcps_cachedrtt;         /* times cached RTT in route updated */
 329         u_long  tcps_cachedrttvar;      /* times cached rttvar updated */
 330         u_long  tcps_cachedssthresh;    /* times cached ssthresh updated */
 331         u_long  tcps_usedrtt;           /* times RTT initialized from route */
 332         u_long  tcps_usedrttvar;        /* times RTTVAR initialized from rt */
 333         u_long  tcps_usedssthresh;      /* times ssthresh initialized from rt*/
 334         u_long  tcps_persistdrop;       /* timeout in persist state */
 335         u_long  tcps_badsyn;            /* bogus SYN, e.g. premature ACK */
 336         u_long  tcps_mturesent;         /* resends due to MTU discovery */
 337         u_long  tcps_listendrop;        /* listen queue overflows */
 338 };
 339
 340 /*
 341  * TCB structure exported to user-land via sysctl(3).
 342  * Evil hack: declare only if in_pcb.h and sys/socketvar.h have been
 343  * included.  Not all of our clients do.
 344  */
 345 #if defined(_NETINET_IN_PCB_H_) && defined(_SYS_SOCKETVAR_H_)
 346 struct  xtcpcb {
 347         size_t  xt_len;
 348         struct  inpcb   xt_inp;
 349         struct  tcpcb   xt_tp;
 350         struct  xsocket xt_socket;
 351         u_quad_t        xt_alignment_hack;
 352 };
 353 #endif
 354
 355 /*
 356  * Names for TCP sysctl objects
 357  */
 358 #define TCPCTL_DO_RFC1323       1       /* use RFC-1323 extensions */
 359 #define TCPCTL_DO_RFC1644       2       /* use RFC-1644 extensions */
 360 #define TCPCTL_MSSDFLT          3       /* MSS default */
 361 #define TCPCTL_STATS            4       /* statistics (read-only) */
 362 #define TCPCTL_RTTDFLT          5       /* default RTT estimate */
 363 #define TCPCTL_KEEPIDLE         6       /* keepalive idle timer */
 364 #define TCPCTL_KEEPINTVL        7       /* interval to send keepalives */
 365 #define TCPCTL_SENDSPACE        8       /* send buffer space */
 366 #define TCPCTL_RECVSPACE        9       /* receive buffer space */
 367 #define TCPCTL_KEEPINIT         10      /* receive buffer space */
 368 #define TCPCTL_PCBLIST          11      /* list of all outstanding PCBs */
 369 #define TCPCTL_V6MSSDFLT        12      /* MSS default for IPv6 */
 370 #define TCPCTL_MAXID            13
 371
 372 #define TCPCTL_NAMES { \
 373         { 0, 0 }, \
 374         { "rfc1323", CTLTYPE_INT }, \
 375         { "rfc1644", CTLTYPE_INT }, \
 376         { "mssdflt", CTLTYPE_INT }, \
 377         { "stats", CTLTYPE_STRUCT }, \
 378         { "rttdflt", CTLTYPE_INT }, \
 379         { "keepidle", CTLTYPE_INT }, \
 380         { "keepintvl", CTLTYPE_INT }, \
 381         { "sendspace", CTLTYPE_INT }, \
 382         { "recvspace", CTLTYPE_INT }, \
 383         { "keepinit", CTLTYPE_INT }, \
 384         { "pcblist", CTLTYPE_STRUCT }, \
 385         { "v6mssdflt", CTLTYPE_INT }, \
 386 }
 387
 388 #ifdef KERNEL
 389 #ifdef SYSCTL_DECL
 390 SYSCTL_DECL(_net_inet_tcp);
 391 #endif
 392
 393 extern  struct inpcbhead tcb;           /* head of queue of active tcpcb's */
 394 extern  struct inpcbinfo tcbinfo;
 395 extern  struct tcpstat tcpstat; /* tcp statistics */
 396 extern  int tcp_mssdflt;        /* XXX */
 397 extern  int tcp_v6mssdflt;      /* XXX */
 398 extern  u_long tcp_now;         /* for RFC 1323 timestamps */
 399 extern  int tcp_delack_enabled;
 400
 401 void     tcp_canceltimers __P((struct tcpcb *));
 402 struct tcpcb *
 403          tcp_close __P((struct tcpcb *));
 404 void     tcp_ctlinput __P((int, struct sockaddr *, void *));
 405 #if INET6
 406 struct ip6_hdr;
 407 void     tcp6_ctlinput __P((int, struct sockaddr *,void *));
 408 #endif
 409 int      tcp_ctloutput __P((struct socket *, struct sockopt *));
 410 struct tcpcb *
 411          tcp_drop __P((struct tcpcb *, int));
 412 void     tcp_drain __P((void));
 413 void     tcp_fasttimo __P((void));
 414 struct rmxp_tao *
 415          tcp_gettaocache __P((struct inpcb *));
 416 void     tcp_init __P((void));
 417 #if INET6
 418 void     tcp6_init __P((void));
 419 int      tcp6_input __P((struct mbuf **, int *, int));
 420 #endif /* INET6 */
 421 void     tcp_input __P((struct mbuf *, int));
 422 #if INET6
 423 void     tcp_mss __P((struct tcpcb *, int, int));
 424 int      tcp_mssopt __P((struct tcpcb *, int));
 425 #else /* INET6 */
 426 void     tcp_mss __P((struct tcpcb *, int));
 427 int      tcp_mssopt __P((struct tcpcb *));
 428 #endif /* INET6 */
 429
 430 void     tcp_mtudisc __P((struct inpcb *, int));
 431 struct tcpcb *
 432          tcp_newtcpcb __P((struct inpcb *));
 433 int      tcp_output __P((struct tcpcb *));
 434 void     tcp_quench __P((struct inpcb *, int));
 435 #if INET6
 436 void     tcp_respond __P((struct tcpcb *, void *, struct tcphdr *,
 437                           struct mbuf *, tcp_seq, tcp_seq, int, int));
 438 #else /* INET6 */
 439 void     tcp_respond __P((struct tcpcb *, void *, struct tcphdr *,
 440                           struct mbuf *, tcp_seq, tcp_seq, int));
 441 #endif /* INET6 */
 442
 443 struct rtentry *
 444          tcp_rtlookup __P((struct inpcb *));
 445 #if INET6
 446 struct rtentry *
 447          tcp_rtlookup6 __P((struct inpcb *));
 448 #endif /* INET6 */
 449 void     tcp_setpersist __P((struct tcpcb *));
 450 void     tcp_slowtimo __P((void));
 451 struct tcptemp *
 452          tcp_template __P((struct tcpcb *));
 453 struct tcpcb *
 454          tcp_timers __P((struct tcpcb *, int));
 455 #if INET6
 456 void     tcp_trace __P((int, int, struct tcpcb *, void *, struct tcphdr *,
 457                         int));
 458 #else
 459 void     tcp_trace __P((int, int, struct tcpcb *, struct ip *,
 460                         struct tcphdr *, int));
 461 #endif
 462
 463 #if INET6
 464 int      tcp_reass __P((struct tcpcb *, struct tcphdr *, int,
 465             struct mbuf *, int));
 466 #else /* INET6 */
 467 int      tcp_reass __P((struct tcpcb *, struct tcphdr *, int, struct mbuf *));
 468 /* suppress INET6 only args */
 469 #define tcp_reass(x, y, z, t, i)                tcp_reass(x, y, z, t)
 470 #define tcp_mss(x, y, i)                        tcp_mss(x, y)
 471 #define tcp_mssopt(x, i)                        tcp_mssopt(x)
 472 #define tcp_respond(x, y, z, m, s1, s2, f, i)   tcp_respond(x, y, z, m, s1, \
 473                                                             s2, f)
 474
 475 #endif /* INET6 */
 476
 477 extern  struct pr_usrreqs tcp_usrreqs;
 478 #if INET6
 479 extern  struct pr_usrreqs tcp6_usrreqs;
 480 #endif /* INET6 */
 481 extern  u_long tcp_sendspace;
 482 extern  u_long tcp_recvspace;
 483
 484 #endif /* KERNEL */
 485
 486 #endif /* _NETINET_TCP_VAR_H_ */