reactos/lib/drivers/oskittcp/oskittcp/tcp_timer.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993
   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_timer.c 8.1 (Berkeley) 6/10/93
  34  */
  35
  36 #ifndef TUBA_INCLUDE
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/malloc.h>
  40 #include <sys/mbuf.h>
  41 #include <sys/socket.h>
  42 #include <sys/socketvar.h>
  43 #include <sys/protosw.h>
  44 #include <sys/errno.h>
  45 #include <sys/queue.h>
  46
  47 #include <net/if.h>
  48 #include <net/route.h>
  49
  50 #include <netinet/in.h>
  51 #include <netinet/in_systm.h>
  52 #include <netinet/ip.h>
  53 #include <netinet/in_pcb.h>
  54 #include <netinet/ip_var.h>
  55 #include <netinet/tcp.h>
  56 #include <netinet/tcp_fsm.h>
  57 #include <netinet/tcp_seq.h>
  58 #include <netinet/tcp_timer.h>
  59 #include <netinet/tcp_var.h>
  60 #include <netinet/tcpip.h>
  61 #ifdef TCPDEBUG
  62 #include <netinet/tcp_debug.h>
  63 #endif
  64
  65 int     tcp_keepidle = TCPTV_KEEP_IDLE;
  66 int     tcp_keepintvl = TCPTV_KEEPINTVL;
  67 int     tcp_keepinit = TCPTV_KEEP_INIT;
  68 int     tcp_maxidle;
  69 int     tcp_maxpersistidle = TCPTV_KEEP_IDLE;
  70 int     tcp_totbackoff = 511;
  71 #endif /* TUBA_INCLUDE */
  72 /*
  73  * Fast timeout routine for processing delayed acks
  74  */
  75 void
  76 tcp_fasttimo()
  77 {
  78         register struct inpcb *inp;
  79         register struct tcpcb *tp;
  80         int s;
  81
  82         s = splnet();
  83
  84         for (inp = tcb.lh_first; inp != NULL; inp = inp->inp_list.le_next) {
  85                 if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
  86                     (tp->t_flags & TF_DELACK)) {
  87                         tp->t_flags &= ~TF_DELACK;
  88                         tp->t_flags |= TF_ACKNOW;
  89                         tcpstat.tcps_delack++;
  90                         (void) tcp_output(tp);
  91                 }
  92         }
  93         splx(s);
  94 }
  95
  96 /*
  97  * Tcp protocol timeout routine called every 500 ms.
  98  * Updates the timers in all active tcb's and
  99  * causes finite state machine actions if timers expire.
 100  */
 101 void
 102 tcp_slowtimo()
 103 {
 104         register struct inpcb *ip, *ipnxt;
 105         register struct tcpcb *tp;
 106         register int i;
 107         int s;
 108 #ifdef TCPDEBUG
 109         int ostate;
 110 #endif
 111
 112         s = splnet();
 113
 114         tcp_maxidle = TCPTV_KEEPCNT * tcp_keepintvl;
 115
 116         ip = tcb.lh_first;
 117         if (ip == NULL) {
 118                 splx(s);
 119                 return;
 120         }
 121         /*
 122          * Search through tcb's and update active timers.
 123          */
 124         for (; ip != NULL; ip = ipnxt) {
 125                 ipnxt = ip->inp_list.le_next;
 126                 tp = intotcpcb(ip);
 127                 if (tp == 0)
 128                         continue;
 129                 for (i = 0; i < TCPT_NTIMERS; i++) {
 130                         if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
 131 #ifdef TCPDEBUG
 132                                 ostate = tp->t_state;
 133 #endif
 134                                 tp = tcp_timers(tp, i);
 135                                 if (tp == NULL)
 136                                         goto tpgone;
 137 #ifdef TCPDEBUG
 138                                 if (tp->t_inpcb->inp_socket->so_options
 139                                     & SO_DEBUG)
 140                                         tcp_trace(TA_USER, ostate, tp,
 141                                                   (struct tcpiphdr *)0,
 142                                                   PRU_SLOWTIMO);
 143 #endif
 144                         }
 145                 }
 146                 tp->t_idle++;
 147                 tp->t_duration++;
 148                 if (tp->t_rtt)
 149                         tp->t_rtt++;
 150 tpgone:
 151                 ;
 152         }
 153         tcp_iss += TCP_ISSINCR/PR_SLOWHZ;               /* increment iss */
 154 #ifdef TCP_COMPAT_42
 155         if ((int)tcp_iss < 0)
 156                 tcp_iss = 0;                            /* XXX */
 157 #endif
 158         tcp_now++;                                      /* for timestamps */
 159         splx(s);
 160 }
 161 #ifndef TUBA_INCLUDE
 162
 163 /*
 164  * Cancel all timers for TCP tp.
 165  */
 166 void
 167 tcp_canceltimers(tp)
 168         struct tcpcb *tp;
 169 {
 170         register int i;
 171
 172         for (i = 0; i < TCPT_NTIMERS; i++)
 173                 tp->t_timer[i] = 0;
 174 }
 175
 176 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 177     { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
 178
 179 /*
 180  * TCP timer processing.
 181  */
 182 struct tcpcb *
 183 tcp_timers(tp, timer)
 184         register struct tcpcb *tp;
 185         int timer;
 186 {
 187         register int rexmt;
 188
 189         switch (timer) {
 190
 191         /*
 192          * 2 MSL timeout in shutdown went off.  If we're closed but
 193          * still waiting for peer to close and connection has been idle
 194          * too long, or if 2MSL time is up from TIME_WAIT, delete connection
 195          * control block.  Otherwise, check again in a bit.
 196          */
 197         case TCPT_2MSL:
 198                 if (tp->t_state != TCPS_TIME_WAIT &&
 199                     tp->t_idle <= tcp_maxidle)
 200                         tp->t_timer[TCPT_2MSL] = tcp_keepintvl;
 201                 else
 202                         tp = tcp_close(tp);
 203                 break;
 204
 205         /*
 206          * Retransmission timer went off.  Message has not
 207          * been acked within retransmit interval.  Back off
 208          * to a longer retransmit interval and retransmit one segment.
 209          */
 210         case TCPT_REXMT:
 211                 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 212                         tp->t_rxtshift = TCP_MAXRXTSHIFT;
 213                         tcpstat.tcps_timeoutdrop++;
 214                         tp = tcp_drop(tp, tp->t_softerror ?
 215                             tp->t_softerror : ETIMEDOUT);
 216                         break;
 217                 }
 218                 tcpstat.tcps_rexmttimeo++;
 219                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 220                 TCPT_RANGESET(tp->t_rxtcur, rexmt,
 221                     tp->t_rttmin, TCPTV_REXMTMAX);
 222                 tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
 223                 /*
 224                  * If losing, let the lower level know and try for
 225                  * a better route.  Also, if we backed off this far,
 226                  * our srtt estimate is probably bogus.  Clobber it
 227                  * so we'll take the next rtt measurement as our srtt;
 228                  * move the current srtt into rttvar to keep the current
 229                  * retransmit times until then.
 230                  */
 231                 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 232                         in_losing(tp->t_inpcb);
 233                         tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 234                         tp->t_srtt = 0;
 235                 }
 236                 tp->snd_nxt = tp->snd_una;
 237                 /*
 238                  * Force a segment to be sent.
 239                  */
 240                 tp->t_flags |= TF_ACKNOW;
 241                 /*
 242                  * If timing a segment in this window, stop the timer.
 243                  */
 244                 tp->t_rtt = 0;
 245                 /*
 246                  * Close the congestion window down to one segment
 247                  * (we'll open it by one segment for each ack we get).
 248                  * Since we probably have a window's worth of unacked
 249                  * data accumulated, this "slow start" keeps us from
 250                  * dumping all that data as back-to-back packets (which
 251                  * might overwhelm an intermediate gateway).
 252                  *
 253                  * There are two phases to the opening: Initially we
 254                  * open by one mss on each ack.  This makes the window
 255                  * size increase exponentially with time.  If the
 256                  * window is larger than the path can handle, this
 257                  * exponential growth results in dropped packet(s)
 258                  * almost immediately.  To get more time between
 259                  * drops but still "push" the network to take advantage
 260                  * of improving conditions, we switch from exponential
 261                  * to linear window opening at some threshhold size.
 262                  * For a threshhold, we use half the current window
 263                  * size, truncated to a multiple of the mss.
 264                  *
 265                  * (the minimum cwnd that will give us exponential
 266                  * growth is 2 mss.  We don't allow the threshhold
 267                  * to go below this.)
 268                  */
 269                 {
 270                 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
 271                 if (win < 2)
 272                         win = 2;
 273                 tp->snd_cwnd = tp->t_maxseg;
 274                 tp->snd_ssthresh = win * tp->t_maxseg;
 275                 tp->t_dupacks = 0;
 276                 }
 277                 (void) tcp_output(tp);
 278                 break;
 279
 280         /*
 281          * Persistance timer into zero window.
 282          * Force a byte to be output, if possible.
 283          */
 284         case TCPT_PERSIST:
 285                 tcpstat.tcps_persisttimeo++;
 286                 /*
 287                  * Hack: if the peer is dead/unreachable, we do not
 288                  * time out if the window is closed.  After a full
 289                  * backoff, drop the connection if the idle time
 290                  * (no responses to probes) reaches the maximum
 291                  * backoff that we would use if retransmitting.
 292                  */
 293                 if (tp->t_rxtshift == TCP_MAXRXTSHIFT) {
 294                         u_long maxidle = TCP_REXMTVAL(tp);
 295                         if (maxidle < tp->t_rttmin)
 296                                 maxidle = tp->t_rttmin;
 297                         maxidle *= tcp_totbackoff;
 298                         if (tp->t_idle >= tcp_maxpersistidle ||
 299                             tp->t_idle >= maxidle) {
 300                                 tcpstat.tcps_persistdrop++;
 301                                 tp = tcp_drop(tp, ETIMEDOUT);
 302                                 break;
 303                         }
 304                 }
 305                 tcp_setpersist(tp);
 306                 tp->t_force = 1;
 307                 (void) tcp_output(tp);
 308                 tp->t_force = 0;
 309                 break;
 310
 311         /*
 312          * Keep-alive timer went off; send something
 313          * or drop connection if idle for too long.
 314          */
 315         case TCPT_KEEP:
 316                 tcpstat.tcps_keeptimeo++;
 317                 if (tp->t_state < TCPS_ESTABLISHED)
 318                         goto dropit;
 319                 if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE &&
 320                     tp->t_state <= TCPS_CLOSING) {
 321                         if (tp->t_idle >= tcp_keepidle + tcp_maxidle)
 322                                 goto dropit;
 323                         /*
 324                          * Send a packet designed to force a response
 325                          * if the peer is up and reachable:
 326                          * either an ACK if the connection is still alive,
 327                          * or an RST if the peer has closed the connection
 328                          * due to timeout or reboot.
 329                          * Using sequence number tp->snd_una-1
 330                          * causes the transmitted zero-length segment
 331                          * to lie outside the receive window;
 332                          * by the protocol spec, this requires the
 333                          * correspondent TCP to respond.
 334                          */
 335                         tcpstat.tcps_keepprobe++;
 336 #ifdef TCP_COMPAT_42
 337                         /*
 338                          * The keepalive packet must have nonzero length
 339                          * to get a 4.2 host to respond.
 340                          */
 341                         tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
 342                             tp->rcv_nxt - 1, tp->snd_una - 1, 0);
 343 #else
 344                         tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
 345                             tp->rcv_nxt, tp->snd_una - 1, 0);
 346 #endif
 347                         tp->t_timer[TCPT_KEEP] = tcp_keepintvl;
 348                 } else
 349                         tp->t_timer[TCPT_KEEP] = tcp_keepidle;
 350                 break;
 351         dropit:
 352                 tcpstat.tcps_keepdrops++;
 353                 tp = tcp_drop(tp, ETIMEDOUT);
 354                 break;
 355         }
 356         return (tp);
 357 }
 358 #endif /* TUBA_INCLUDE */