source: rtems/cpukit/libnetworking/netinet/tcp_timer.c @ c301570

4.104.114.84.9
Last change on this file since c301570 was c301570, checked in by Ralf Corsepius <ralf.corsepius@…>, on May 10, 2007 at 5:12:54 AM

Include <rtems/bsd/sys/queue.h> instead of <sys/queue.h>.

  • Property mode set to 100644
File size: 10.7 KB
Line 
1/*
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 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 * 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 8.2 (Berkeley) 5/24/95
34 *      $Id$
35 */
36
37#include "opt_tcpdebug.h"
38
39#ifndef TUBA_INCLUDE
40#include <sys/param.h>
41#include <rtems/bsd/sys/queue.h>
42#include <sys/systm.h>
43#include <sys/kernel.h>
44#include <sys/sysctl.h>
45#include <sys/malloc.h>
46#include <sys/mbuf.h>
47#include <sys/socket.h>
48#include <sys/socketvar.h>
49#include <sys/protosw.h>
50#include <sys/errno.h>
51
52#include <machine/cpu.h>        /* before tcp_seq.h, for tcp_random18() */
53
54#include <net/if.h>
55#include <net/route.h>
56
57#include <netinet/in.h>
58#include <netinet/in_systm.h>
59#include <netinet/ip.h>
60#include <netinet/in_pcb.h>
61#include <netinet/ip_var.h>
62#include <netinet/tcp.h>
63#include <netinet/tcp_fsm.h>
64#include <netinet/tcp_seq.h>
65#include <netinet/tcp_timer.h>
66#include <netinet/tcp_var.h>
67#include <netinet/tcpip.h>
68#ifdef TCPDEBUG
69#include <netinet/tcp_debug.h>
70#endif
71
72int     tcp_keepinit = TCPTV_KEEP_INIT;
73SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
74        CTLFLAG_RW, &tcp_keepinit , 0, "");
75
76int     tcp_keepidle = TCPTV_KEEP_IDLE;
77SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
78        CTLFLAG_RW, &tcp_keepidle , 0, "");
79
80static int      tcp_keepintvl = TCPTV_KEEPINTVL;
81SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
82        CTLFLAG_RW, &tcp_keepintvl , 0, "");
83
84static int      always_keepalive = 0;
85SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive,
86        CTLFLAG_RW, &always_keepalive , 0, "");
87
88static int      tcp_keepcnt = TCPTV_KEEPCNT;
89        /* max idle probes */
90static int      tcp_maxpersistidle = TCPTV_KEEP_IDLE;
91        /* max idle time in persist */
92int     tcp_maxidle;
93#else /* TUBA_INCLUDE */
94
95static  int tcp_maxpersistidle;
96#endif /* TUBA_INCLUDE */
97
98/*
99 * Fast timeout routine for processing delayed acks
100 */
101void
102tcp_fasttimo()
103{
104        register struct inpcb *inp;
105        register struct tcpcb *tp;
106        int s;
107
108        s = splnet();
109
110        for (inp = tcb.lh_first; inp != NULL; inp = inp->inp_list.le_next) {
111                if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
112                    (tp->t_flags & TF_DELACK)) {
113                        tp->t_flags &= ~TF_DELACK;
114                        tp->t_flags |= TF_ACKNOW;
115                        tcpstat.tcps_delack++;
116                        (void) tcp_output(tp);
117                }
118        }
119        splx(s);
120}
121
122/*
123 * Tcp protocol timeout routine called every 500 ms.
124 * Updates the timers in all active tcb's and
125 * causes finite state machine actions if timers expire.
126 */
127void
128tcp_slowtimo()
129{
130        register struct inpcb *ip, *ipnxt;
131        register struct tcpcb *tp;
132        register int i;
133        int s;
134#ifdef TCPDEBUG
135        int ostate;
136#endif
137
138        s = splnet();
139
140        tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
141
142        ip = tcb.lh_first;
143        if (ip == NULL) {
144                splx(s);
145                return;
146        }
147        /*
148         * Search through tcb's and update active timers.
149         */
150        for (; ip != NULL; ip = ipnxt) {
151                ipnxt = ip->inp_list.le_next;
152                tp = intotcpcb(ip);
153                if (tp == 0 || tp->t_state == TCPS_LISTEN)
154                        continue;
155                for (i = 0; i < TCPT_NTIMERS; i++) {
156                        if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
157#ifdef TCPDEBUG
158                                ostate = tp->t_state;
159#endif
160                                tp = tcp_timers(tp, i);
161                                if (tp == NULL)
162                                        goto tpgone;
163#ifdef TCPDEBUG
164                                if (tp->t_inpcb->inp_socket->so_options
165                                    & SO_DEBUG)
166                                        tcp_trace(TA_USER, ostate, tp,
167                                                  (struct tcpiphdr *)0,
168                                                  PRU_SLOWTIMO);
169#endif
170                        }
171                }
172                tp->t_idle++;
173                tp->t_duration++;
174                if (tp->t_rtt)
175                        tp->t_rtt++;
176tpgone:
177                ;
178        }
179        tcp_iss += TCP_ISSINCR/PR_SLOWHZ;               /* increment iss */
180#ifdef TCP_COMPAT_42
181        if ((int)tcp_iss < 0)
182                tcp_iss = TCP_ISSINCR;                  /* XXX */
183#endif
184        tcp_now++;                                      /* for timestamps */
185        splx(s);
186}
187#ifndef TUBA_INCLUDE
188
189/*
190 * Cancel all timers for TCP tp.
191 */
192void
193tcp_canceltimers(tp)
194        struct tcpcb *tp;
195{
196        register int i;
197
198        for (i = 0; i < TCPT_NTIMERS; i++)
199                tp->t_timer[i] = 0;
200}
201
202int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
203    { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
204
205static int tcp_totbackoff = 511;        /* sum of tcp_backoff[] */
206
207/*
208 * TCP timer processing.
209 */
210struct tcpcb *
211tcp_timers(tp, timer)
212        register struct tcpcb *tp;
213        int timer;
214{
215        register int rexmt;
216
217        switch (timer) {
218
219        /*
220         * 2 MSL timeout in shutdown went off.  If we're closed but
221         * still waiting for peer to close and connection has been idle
222         * too long, or if 2MSL time is up from TIME_WAIT, delete connection
223         * control block.  Otherwise, check again in a bit.
224         */
225        case TCPT_2MSL:
226                if (tp->t_state != TCPS_TIME_WAIT &&
227                    tp->t_idle <= tcp_maxidle)
228                        tp->t_timer[TCPT_2MSL] = tcp_keepintvl;
229                else
230                        tp = tcp_close(tp);
231                break;
232
233        /*
234         * Retransmission timer went off.  Message has not
235         * been acked within retransmit interval.  Back off
236         * to a longer retransmit interval and retransmit one segment.
237         */
238        case TCPT_REXMT:
239                if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
240                        tp->t_rxtshift = TCP_MAXRXTSHIFT;
241                        tcpstat.tcps_timeoutdrop++;
242                        tp = tcp_drop(tp, tp->t_softerror ?
243                            tp->t_softerror : ETIMEDOUT);
244                        break;
245                }
246                tcpstat.tcps_rexmttimeo++;
247                rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
248                TCPT_RANGESET(tp->t_rxtcur, rexmt,
249                    tp->t_rttmin, TCPTV_REXMTMAX);
250                tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
251                /*
252                 * If losing, let the lower level know and try for
253                 * a better route.  Also, if we backed off this far,
254                 * our srtt estimate is probably bogus.  Clobber it
255                 * so we'll take the next rtt measurement as our srtt;
256                 * move the current srtt into rttvar to keep the current
257                 * retransmit times until then.
258                 */
259                if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
260                        in_losing(tp->t_inpcb);
261                        tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
262                        tp->t_srtt = 0;
263                }
264                tp->snd_nxt = tp->snd_una;
265                /*
266                 * Force a segment to be sent.
267                 */
268                tp->t_flags |= TF_ACKNOW;
269                /*
270                 * If timing a segment in this window, stop the timer.
271                 */
272                tp->t_rtt = 0;
273                /*
274                 * Close the congestion window down to one segment
275                 * (we'll open it by one segment for each ack we get).
276                 * Since we probably have a window's worth of unacked
277                 * data accumulated, this "slow start" keeps us from
278                 * dumping all that data as back-to-back packets (which
279                 * might overwhelm an intermediate gateway).
280                 *
281                 * There are two phases to the opening: Initially we
282                 * open by one mss on each ack.  This makes the window
283                 * size increase exponentially with time.  If the
284                 * window is larger than the path can handle, this
285                 * exponential growth results in dropped packet(s)
286                 * almost immediately.  To get more time between
287                 * drops but still "push" the network to take advantage
288                 * of improving conditions, we switch from exponential
289                 * to linear window opening at some threshhold size.
290                 * For a threshhold, we use half the current window
291                 * size, truncated to a multiple of the mss.
292                 *
293                 * (the minimum cwnd that will give us exponential
294                 * growth is 2 mss.  We don't allow the threshhold
295                 * to go below this.)
296                 */
297                {
298                u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
299                if (win < 2)
300                        win = 2;
301                tp->snd_cwnd = tp->t_maxseg;
302                tp->snd_ssthresh = win * tp->t_maxseg;
303                tp->t_dupacks = 0;
304                }
305                (void) tcp_output(tp);
306                break;
307
308        /*
309         * Persistance timer into zero window.
310         * Force a byte to be output, if possible.
311         */
312        case TCPT_PERSIST:
313                tcpstat.tcps_persisttimeo++;
314                /*
315                 * Hack: if the peer is dead/unreachable, we do not
316                 * time out if the window is closed.  After a full
317                 * backoff, drop the connection if the idle time
318                 * (no responses to probes) reaches the maximum
319                 * backoff that we would use if retransmitting.
320                 */
321                if (tp->t_rxtshift == TCP_MAXRXTSHIFT) {
322                        u_long maxidle = TCP_REXMTVAL(tp);
323                        if (maxidle < tp->t_rttmin)
324                                maxidle = tp->t_rttmin;
325                        maxidle *= tcp_totbackoff;
326                        if (tp->t_idle >= tcp_maxpersistidle ||
327                            tp->t_idle >= maxidle) {
328                                tcpstat.tcps_persistdrop++;
329                                tp = tcp_drop(tp, ETIMEDOUT);
330                                break;
331                        }
332                }
333                tcp_setpersist(tp);
334                tp->t_force = 1;
335                (void) tcp_output(tp);
336                tp->t_force = 0;
337                break;
338
339        /*
340         * Keep-alive timer went off; send something
341         * or drop connection if idle for too long.
342         */
343        case TCPT_KEEP:
344                tcpstat.tcps_keeptimeo++;
345                if (tp->t_state < TCPS_ESTABLISHED)
346                        goto dropit;
347                if ((always_keepalive ||
348                    tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) &&
349                    tp->t_state <= TCPS_CLOSING) {
350                        if (tp->t_idle >= tcp_keepidle + tcp_maxidle)
351                                goto dropit;
352                        /*
353                         * Send a packet designed to force a response
354                         * if the peer is up and reachable:
355                         * either an ACK if the connection is still alive,
356                         * or an RST if the peer has closed the connection
357                         * due to timeout or reboot.
358                         * Using sequence number tp->snd_una-1
359                         * causes the transmitted zero-length segment
360                         * to lie outside the receive window;
361                         * by the protocol spec, this requires the
362                         * correspondent TCP to respond.
363                         */
364                        tcpstat.tcps_keepprobe++;
365#ifdef TCP_COMPAT_42
366                        /*
367                         * The keepalive packet must have nonzero length
368                         * to get a 4.2 host to respond.
369                         */
370                        tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
371                            tp->rcv_nxt - 1, tp->snd_una - 1, 0);
372#else
373                        tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
374                            tp->rcv_nxt, tp->snd_una - 1, 0);
375#endif
376                        tp->t_timer[TCPT_KEEP] = tcp_keepintvl;
377                } else
378                        tp->t_timer[TCPT_KEEP] = tcp_keepidle;
379                break;
380        dropit:
381                tcpstat.tcps_keepdrops++;
382                tp = tcp_drop(tp, ETIMEDOUT);
383                break;
384        }
385        return (tp);
386}
387#endif /* TUBA_INCLUDE */
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