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 * 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_timer.c 8.2 (Berkeley) 5/24/95
| 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 * 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_timer.c 8.2 (Berkeley) 5/24/95
|
30 * $FreeBSD: head/sys/netinet/tcp_timer.c 169309 2007-05-06 13:38:25Z andre $
| 30 * $FreeBSD: head/sys/netinet/tcp_timer.c 169454 2007-05-10 15:58:48Z rwatson $
|
31 */
32
33#include "opt_inet6.h"
34#include "opt_tcpdebug.h"
35
36#include <sys/param.h>
37#include <sys/kernel.h>
38#include <sys/ktr.h>
39#include <sys/lock.h>
40#include <sys/limits.h>
41#include <sys/mbuf.h>
42#include <sys/mutex.h>
43#include <sys/protosw.h>
44#include <sys/socket.h>
45#include <sys/socketvar.h>
46#include <sys/sysctl.h>
47#include <sys/systm.h>
48
49#include <net/route.h>
50
51#include <netinet/in.h>
52#include <netinet/in_pcb.h>
53#include <netinet/in_systm.h>
54#ifdef INET6
55#include <netinet6/in6_pcb.h>
56#endif
57#include <netinet/ip_var.h>
58#include <netinet/tcp.h>
59#include <netinet/tcp_fsm.h>
60#include <netinet/tcp_timer.h>
61#include <netinet/tcp_var.h>
62#include <netinet/tcpip.h>
63#ifdef TCPDEBUG
64#include <netinet/tcp_debug.h>
65#endif
66
67int tcp_keepinit;
68SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
69 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
70
71int tcp_keepidle;
72SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
73 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
74
75int tcp_keepintvl;
76SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
77 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
78
79int tcp_delacktime;
80SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
81 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
82 "Time before a delayed ACK is sent");
83
84int tcp_msl;
85SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
86 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
87
88int tcp_rexmit_min;
89SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
91 "Minimum Retransmission Timeout");
92
93int tcp_rexmit_slop;
94SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
95 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
96 "Retransmission Timer Slop");
97
98static int always_keepalive = 1;
99SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
100 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
101
102int tcp_fast_finwait2_recycle = 0;
103SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
104 &tcp_fast_finwait2_recycle, 0,
105 "Recycle closed FIN_WAIT_2 connections faster");
106
107int tcp_finwait2_timeout;
108SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
109 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
110
111
112static int tcp_keepcnt = TCPTV_KEEPCNT;
113 /* max idle probes */
114int tcp_maxpersistidle;
115 /* max idle time in persist */
116int tcp_maxidle;
117
118static void tcp_timer(void *);
119static int tcp_timer_delack(struct tcpcb *, struct inpcb *);
120static int tcp_timer_2msl(struct tcpcb *, struct inpcb *);
121static int tcp_timer_keep(struct tcpcb *, struct inpcb *);
122static int tcp_timer_persist(struct tcpcb *, struct inpcb *);
123static int tcp_timer_rexmt(struct tcpcb *, struct inpcb *);
124
125/*
126 * Tcp protocol timeout routine called every 500 ms.
127 * Updates timestamps used for TCP
128 * causes finite state machine actions if timers expire.
129 */
130void
| 31 */
32
33#include "opt_inet6.h"
34#include "opt_tcpdebug.h"
35
36#include <sys/param.h>
37#include <sys/kernel.h>
38#include <sys/ktr.h>
39#include <sys/lock.h>
40#include <sys/limits.h>
41#include <sys/mbuf.h>
42#include <sys/mutex.h>
43#include <sys/protosw.h>
44#include <sys/socket.h>
45#include <sys/socketvar.h>
46#include <sys/sysctl.h>
47#include <sys/systm.h>
48
49#include <net/route.h>
50
51#include <netinet/in.h>
52#include <netinet/in_pcb.h>
53#include <netinet/in_systm.h>
54#ifdef INET6
55#include <netinet6/in6_pcb.h>
56#endif
57#include <netinet/ip_var.h>
58#include <netinet/tcp.h>
59#include <netinet/tcp_fsm.h>
60#include <netinet/tcp_timer.h>
61#include <netinet/tcp_var.h>
62#include <netinet/tcpip.h>
63#ifdef TCPDEBUG
64#include <netinet/tcp_debug.h>
65#endif
66
67int tcp_keepinit;
68SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
69 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
70
71int tcp_keepidle;
72SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
73 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
74
75int tcp_keepintvl;
76SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
77 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
78
79int tcp_delacktime;
80SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
81 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
82 "Time before a delayed ACK is sent");
83
84int tcp_msl;
85SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
86 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
87
88int tcp_rexmit_min;
89SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
91 "Minimum Retransmission Timeout");
92
93int tcp_rexmit_slop;
94SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
95 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
96 "Retransmission Timer Slop");
97
98static int always_keepalive = 1;
99SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
100 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
101
102int tcp_fast_finwait2_recycle = 0;
103SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
104 &tcp_fast_finwait2_recycle, 0,
105 "Recycle closed FIN_WAIT_2 connections faster");
106
107int tcp_finwait2_timeout;
108SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
109 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
110
111
112static int tcp_keepcnt = TCPTV_KEEPCNT;
113 /* max idle probes */
114int tcp_maxpersistidle;
115 /* max idle time in persist */
116int tcp_maxidle;
117
118static void tcp_timer(void *);
119static int tcp_timer_delack(struct tcpcb *, struct inpcb *);
120static int tcp_timer_2msl(struct tcpcb *, struct inpcb *);
121static int tcp_timer_keep(struct tcpcb *, struct inpcb *);
122static int tcp_timer_persist(struct tcpcb *, struct inpcb *);
123static int tcp_timer_rexmt(struct tcpcb *, struct inpcb *);
124
125/*
126 * Tcp protocol timeout routine called every 500 ms.
127 * Updates timestamps used for TCP
128 * causes finite state machine actions if timers expire.
129 */
130void
|
131tcp_slowtimo()
| 131tcp_slowtimo(void)
|
132{
133
134 tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
135 INP_INFO_WLOCK(&tcbinfo);
136 (void) tcp_timer_2msl_tw(0);
137 INP_INFO_WUNLOCK(&tcbinfo);
138}
139
140int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
141 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
142
143int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
144 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
145
146static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
147
148static int tcp_timer_race;
149SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
150 0, "Count of t_inpcb races on tcp_discardcb");
151
| 132{
133
134 tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
135 INP_INFO_WLOCK(&tcbinfo);
136 (void) tcp_timer_2msl_tw(0);
137 INP_INFO_WUNLOCK(&tcbinfo);
138}
139
140int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
141 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
142
143int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
144 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
145
146static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
147
148static int tcp_timer_race;
149SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
150 0, "Count of t_inpcb races on tcp_discardcb");
151
|
152
| |
153void
154tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
155{
156 struct inpcb *inp = tp->t_inpcb;
157 struct tcp_timer *tt = tp->t_timers;
158 int tick = ticks; /* Stable time base. */
159 int next = delta ? tick + delta : 0;
160
161 INP_LOCK_ASSERT(inp);
162
163 CTR6(KTR_NET, "%p %s inp %p active %x delta %i nextc %i",
164 tp, __func__, inp, tt->tt_active, delta, tt->tt_nextc);
165
166 /* Set new value for timer. */
167 switch(timer_type) {
168 case TT_DELACK:
169 CTR4(KTR_NET, "%p %s TT_DELACK old %i new %i",
170 tp, __func__, tt->tt_delack, next);
171 tt->tt_delack = next;
172 break;
173 case TT_REXMT:
174 CTR4(KTR_NET, "%p %s TT_REXMT old %i new %i",
175 tp, __func__, tt->tt_rexmt, next);
176 tt->tt_rexmt = next;
177 break;
178 case TT_PERSIST:
179 CTR4(KTR_NET, "%p %s TT_PERSIST old %i new %i",
180 tp, __func__, tt->tt_persist, next);
181 tt->tt_persist = next;
182 break;
183 case TT_KEEP:
184 CTR4(KTR_NET, "%p %s TT_KEEP old %i new %i",
185 tp, __func__, tt->tt_keep, next);
186 tt->tt_keep = next;
187 break;
188 case TT_2MSL:
189 CTR4(KTR_NET, "%p %s TT_2MSL old %i new %i",
190 tp, __func__, tt->tt_2msl, next);
191 tt->tt_2msl = next;
192 break;
193 case 0: /* Dummy for timer rescan. */
194 CTR3(KTR_NET, "%p %s timer rescan new %i", tp, __func__, next);
195 break;
196 }
197
198 /* If some other timer is active and is schedules sooner just return. */
199 if (tt->tt_active != timer_type && tt->tt_nextc < next &&
200 callout_active(&tt->tt_timer))
201 return;
202
203 /* Select next timer to schedule. */
204 tt->tt_nextc = INT_MAX;
205 tt->tt_active = 0;
206 if (tt->tt_delack && tt->tt_delack < tt->tt_nextc) {
207 tt->tt_nextc = tt->tt_delack;
208 tt->tt_active = TT_DELACK;
209 }
210 if (tt->tt_rexmt && tt->tt_rexmt < tt->tt_nextc) {
211 tt->tt_nextc = tt->tt_rexmt;
212 tt->tt_active = TT_REXMT;
213 }
214 if (tt->tt_persist && tt->tt_persist < tt->tt_nextc) {
215 tt->tt_nextc = tt->tt_persist;
216 tt->tt_active = TT_PERSIST;
217 }
218 if (tt->tt_keep && tt->tt_keep < tt->tt_nextc) {
219 tt->tt_nextc = tt->tt_keep;
220 tt->tt_active = TT_KEEP;
221 }
222 if (tt->tt_2msl && tt->tt_2msl < tt->tt_nextc) {
223 tt->tt_nextc = tt->tt_2msl;
224 tt->tt_active = TT_2MSL;
225 }
226
227 /* Rearm callout with new timer if we found one. */
228 if (tt->tt_active) {
229 CTR4(KTR_NET, "%p %s callout_reset active %x nextc in %i",
230 tp, __func__, tt->tt_active, tt->tt_nextc - tick);
231 callout_reset(&tt->tt_timer,
232 tt->tt_nextc - tick, tcp_timer, (void *)inp);
233 } else {
234 CTR2(KTR_NET, "%p %s callout_stop", tp, __func__);
235 callout_stop(&tt->tt_timer);
236 tt->tt_nextc = 0;
237 }
238
239 return;
240}
241
242int
243tcp_timer_active(struct tcpcb *tp, int timer_type)
244{
245
246 switch (timer_type) {
247 case TT_DELACK:
248 CTR3(KTR_NET, "%p %s TT_DELACK %i",
249 tp, __func__, tp->t_timers->tt_delack);
250 return (tp->t_timers->tt_delack ? 1 : 0);
251 break;
252 case TT_REXMT:
253 CTR3(KTR_NET, "%p %s TT_REXMT %i",
254 tp, __func__, tp->t_timers->tt_rexmt);
255 return (tp->t_timers->tt_rexmt ? 1 : 0);
256 break;
257 case TT_PERSIST:
258 CTR3(KTR_NET, "%p %s TT_PERSIST %i",
259 tp, __func__, tp->t_timers->tt_persist);
260 return (tp->t_timers->tt_persist ? 1 : 0);
261 break;
262 case TT_KEEP:
263 CTR3(KTR_NET, "%p %s TT_KEEP %i",
264 tp, __func__, tp->t_timers->tt_keep);
265 return (tp->t_timers->tt_keep ? 1 : 0);
266 break;
267 case TT_2MSL:
268 CTR3(KTR_NET, "%p %s TT_2MSL %i",
269 tp, __func__, tp->t_timers->tt_2msl);
270 return (tp->t_timers->tt_2msl ? 1 : 0);
271 break;
272 }
273 return (0);
274}
275
276static void
277tcp_timer(void *xinp)
278{
279 struct inpcb *inp = (struct inpcb *)xinp;
280 struct tcpcb *tp = intotcpcb(inp);
281 struct tcp_timer *tt;
282 int tick = ticks;
283 int down, timer;
284
285 /* INP lock was obtained by callout. */
286 INP_LOCK_ASSERT(inp);
287
288 /*
289 * We've got a couple of race conditions here:
290 * - The tcpcb was converted into a compressed TW pcb. All our
291 * timers have been stopped while this callout already tried
292 * to obtain the inpcb lock. TW pcbs have their own timers
293 * and we just return.
294 */
295 if (inp->inp_vflag & INP_TIMEWAIT)
296 return;
297 /*
298 * - The tcpcb was discarded. All our timers have been stopped
299 * while this callout already tried to obtain the inpcb lock
300 * and we just return.
301 */
302 if (tp == NULL)
303 return;
304
305 tt = tp->t_timers; /* Initialize. */
306 CTR6(KTR_NET, "%p %s inp %p active %x tick %i nextc %i",
307 tp, __func__, inp, tt->tt_active, tick, tt->tt_nextc);
308
309 /*
310 * - We may have been waiting on the lock while the tcpcb has
311 * been scheduled for destruction. In this case no active
312 * timers remain and we just return.
313 */
314 if (tt->tt_active == 0)
315 goto done;
316
317 /*
318 * - The timer was rescheduled while this callout was already
319 * waiting on the lock. This may happen when a packet just
320 * came in. Rescan and reschedule the the timer in case we
321 * just turned it off.
322 */
323 if (tick < tt->tt_nextc)
324 goto rescan;
325
326 /*
327 * Mark as done. The active bit in struct callout is not
328 * automatically cleared. See callout(9) for more info.
329 * In tcp_discardcb() we depend on the correctly cleared
330 * active bit for faster processing.
331 */
332 callout_deactivate(&tt->tt_timer);
333
334 /* Check which timer has fired and remove this timer activation. */
335 timer = tt->tt_active;
336 tt->tt_active = 0;
337 tt->tt_nextc = 0;
338
339 switch (timer) {
340 case TT_DELACK:
341 CTR2(KTR_NET, "%p %s running TT_DELACK", tp, __func__);
342 tt->tt_delack = 0;
343 down = tcp_timer_delack(tp, inp); /* down == 0 */
344 break;
345 case TT_REXMT:
346 CTR2(KTR_NET, "%p %s running TT_REXMT", tp, __func__);
347 tt->tt_rexmt = 0;
348 down = tcp_timer_rexmt(tp, inp);
349 break;
350 case TT_PERSIST:
351 CTR2(KTR_NET, "%p %s running TT_PERSIST", tp, __func__);
352 tt->tt_persist = 0;
353 down = tcp_timer_persist(tp, inp);
354 break;
355 case TT_KEEP:
356 CTR2(KTR_NET, "%p %s running TT_KEEP", tp, __func__);
357 tt->tt_keep = 0;
358 down = tcp_timer_keep(tp, inp);
359 break;
360 case TT_2MSL:
361 CTR2(KTR_NET, "%p %s running TT_2MSL", tp, __func__);
362 tt->tt_2msl = 0;
363 down = tcp_timer_2msl(tp, inp);
364 break;
365 default:
366 CTR2(KTR_NET, "%p %s running nothing", tp, __func__);
367 down = 0;
368 }
369
370 CTR4(KTR_NET, "%p %s down %i active %x",
371 tp, __func__, down, tt->tt_active);
372 /* Do we still exist? */
373 if (down)
374 goto shutdown;
375
376rescan:
377 /* Rescan if no timer was reactivated above. */
378 if (tt->tt_active == 0)
379 tcp_timer_activate(tp, 0, 0);
380
381done:
382 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
383 return;
384
385shutdown:
386 INP_UNLOCK(inp); /* Prevent LOR at expense of race. */
387 INP_INFO_WLOCK(&tcbinfo);
388 INP_LOCK(inp);
389
390 /* When tp is gone we've lost the race. */
391 if (inp->inp_ppcb == NULL) {
392 CTR3(KTR_NET, "%p %s inp %p lost shutdown race",
393 tp, __func__, inp);
394 tcp_timer_race++;
395 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
396 INP_INFO_WUNLOCK(&tcbinfo);
397 return;
398 }
399 KASSERT(tp == inp->inp_ppcb, ("%s: tp changed", __func__));
400
401 /* Shutdown the connection. */
402 switch (down) {
403 case 1:
404 tp = tcp_close(tp);
405 break;
406 case 2:
407 tp = tcp_drop(tp,
408 tp->t_softerror ? tp->t_softerror : ETIMEDOUT);
409 break;
410 }
411 CTR3(KTR_NET, "%p %s inp %p after shutdown", tp, __func__, inp);
412
413 if (tp)
414 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
415
416 INP_INFO_WUNLOCK(&tcbinfo);
417 return;
418}
419
| 152void
153tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
154{
155 struct inpcb *inp = tp->t_inpcb;
156 struct tcp_timer *tt = tp->t_timers;
157 int tick = ticks; /* Stable time base. */
158 int next = delta ? tick + delta : 0;
159
160 INP_LOCK_ASSERT(inp);
161
162 CTR6(KTR_NET, "%p %s inp %p active %x delta %i nextc %i",
163 tp, __func__, inp, tt->tt_active, delta, tt->tt_nextc);
164
165 /* Set new value for timer. */
166 switch(timer_type) {
167 case TT_DELACK:
168 CTR4(KTR_NET, "%p %s TT_DELACK old %i new %i",
169 tp, __func__, tt->tt_delack, next);
170 tt->tt_delack = next;
171 break;
172 case TT_REXMT:
173 CTR4(KTR_NET, "%p %s TT_REXMT old %i new %i",
174 tp, __func__, tt->tt_rexmt, next);
175 tt->tt_rexmt = next;
176 break;
177 case TT_PERSIST:
178 CTR4(KTR_NET, "%p %s TT_PERSIST old %i new %i",
179 tp, __func__, tt->tt_persist, next);
180 tt->tt_persist = next;
181 break;
182 case TT_KEEP:
183 CTR4(KTR_NET, "%p %s TT_KEEP old %i new %i",
184 tp, __func__, tt->tt_keep, next);
185 tt->tt_keep = next;
186 break;
187 case TT_2MSL:
188 CTR4(KTR_NET, "%p %s TT_2MSL old %i new %i",
189 tp, __func__, tt->tt_2msl, next);
190 tt->tt_2msl = next;
191 break;
192 case 0: /* Dummy for timer rescan. */
193 CTR3(KTR_NET, "%p %s timer rescan new %i", tp, __func__, next);
194 break;
195 }
196
197 /* If some other timer is active and is schedules sooner just return. */
198 if (tt->tt_active != timer_type && tt->tt_nextc < next &&
199 callout_active(&tt->tt_timer))
200 return;
201
202 /* Select next timer to schedule. */
203 tt->tt_nextc = INT_MAX;
204 tt->tt_active = 0;
205 if (tt->tt_delack && tt->tt_delack < tt->tt_nextc) {
206 tt->tt_nextc = tt->tt_delack;
207 tt->tt_active = TT_DELACK;
208 }
209 if (tt->tt_rexmt && tt->tt_rexmt < tt->tt_nextc) {
210 tt->tt_nextc = tt->tt_rexmt;
211 tt->tt_active = TT_REXMT;
212 }
213 if (tt->tt_persist && tt->tt_persist < tt->tt_nextc) {
214 tt->tt_nextc = tt->tt_persist;
215 tt->tt_active = TT_PERSIST;
216 }
217 if (tt->tt_keep && tt->tt_keep < tt->tt_nextc) {
218 tt->tt_nextc = tt->tt_keep;
219 tt->tt_active = TT_KEEP;
220 }
221 if (tt->tt_2msl && tt->tt_2msl < tt->tt_nextc) {
222 tt->tt_nextc = tt->tt_2msl;
223 tt->tt_active = TT_2MSL;
224 }
225
226 /* Rearm callout with new timer if we found one. */
227 if (tt->tt_active) {
228 CTR4(KTR_NET, "%p %s callout_reset active %x nextc in %i",
229 tp, __func__, tt->tt_active, tt->tt_nextc - tick);
230 callout_reset(&tt->tt_timer,
231 tt->tt_nextc - tick, tcp_timer, (void *)inp);
232 } else {
233 CTR2(KTR_NET, "%p %s callout_stop", tp, __func__);
234 callout_stop(&tt->tt_timer);
235 tt->tt_nextc = 0;
236 }
237
238 return;
239}
240
241int
242tcp_timer_active(struct tcpcb *tp, int timer_type)
243{
244
245 switch (timer_type) {
246 case TT_DELACK:
247 CTR3(KTR_NET, "%p %s TT_DELACK %i",
248 tp, __func__, tp->t_timers->tt_delack);
249 return (tp->t_timers->tt_delack ? 1 : 0);
250 break;
251 case TT_REXMT:
252 CTR3(KTR_NET, "%p %s TT_REXMT %i",
253 tp, __func__, tp->t_timers->tt_rexmt);
254 return (tp->t_timers->tt_rexmt ? 1 : 0);
255 break;
256 case TT_PERSIST:
257 CTR3(KTR_NET, "%p %s TT_PERSIST %i",
258 tp, __func__, tp->t_timers->tt_persist);
259 return (tp->t_timers->tt_persist ? 1 : 0);
260 break;
261 case TT_KEEP:
262 CTR3(KTR_NET, "%p %s TT_KEEP %i",
263 tp, __func__, tp->t_timers->tt_keep);
264 return (tp->t_timers->tt_keep ? 1 : 0);
265 break;
266 case TT_2MSL:
267 CTR3(KTR_NET, "%p %s TT_2MSL %i",
268 tp, __func__, tp->t_timers->tt_2msl);
269 return (tp->t_timers->tt_2msl ? 1 : 0);
270 break;
271 }
272 return (0);
273}
274
275static void
276tcp_timer(void *xinp)
277{
278 struct inpcb *inp = (struct inpcb *)xinp;
279 struct tcpcb *tp = intotcpcb(inp);
280 struct tcp_timer *tt;
281 int tick = ticks;
282 int down, timer;
283
284 /* INP lock was obtained by callout. */
285 INP_LOCK_ASSERT(inp);
286
287 /*
288 * We've got a couple of race conditions here:
289 * - The tcpcb was converted into a compressed TW pcb. All our
290 * timers have been stopped while this callout already tried
291 * to obtain the inpcb lock. TW pcbs have their own timers
292 * and we just return.
293 */
294 if (inp->inp_vflag & INP_TIMEWAIT)
295 return;
296 /*
297 * - The tcpcb was discarded. All our timers have been stopped
298 * while this callout already tried to obtain the inpcb lock
299 * and we just return.
300 */
301 if (tp == NULL)
302 return;
303
304 tt = tp->t_timers; /* Initialize. */
305 CTR6(KTR_NET, "%p %s inp %p active %x tick %i nextc %i",
306 tp, __func__, inp, tt->tt_active, tick, tt->tt_nextc);
307
308 /*
309 * - We may have been waiting on the lock while the tcpcb has
310 * been scheduled for destruction. In this case no active
311 * timers remain and we just return.
312 */
313 if (tt->tt_active == 0)
314 goto done;
315
316 /*
317 * - The timer was rescheduled while this callout was already
318 * waiting on the lock. This may happen when a packet just
319 * came in. Rescan and reschedule the the timer in case we
320 * just turned it off.
321 */
322 if (tick < tt->tt_nextc)
323 goto rescan;
324
325 /*
326 * Mark as done. The active bit in struct callout is not
327 * automatically cleared. See callout(9) for more info.
328 * In tcp_discardcb() we depend on the correctly cleared
329 * active bit for faster processing.
330 */
331 callout_deactivate(&tt->tt_timer);
332
333 /* Check which timer has fired and remove this timer activation. */
334 timer = tt->tt_active;
335 tt->tt_active = 0;
336 tt->tt_nextc = 0;
337
338 switch (timer) {
339 case TT_DELACK:
340 CTR2(KTR_NET, "%p %s running TT_DELACK", tp, __func__);
341 tt->tt_delack = 0;
342 down = tcp_timer_delack(tp, inp); /* down == 0 */
343 break;
344 case TT_REXMT:
345 CTR2(KTR_NET, "%p %s running TT_REXMT", tp, __func__);
346 tt->tt_rexmt = 0;
347 down = tcp_timer_rexmt(tp, inp);
348 break;
349 case TT_PERSIST:
350 CTR2(KTR_NET, "%p %s running TT_PERSIST", tp, __func__);
351 tt->tt_persist = 0;
352 down = tcp_timer_persist(tp, inp);
353 break;
354 case TT_KEEP:
355 CTR2(KTR_NET, "%p %s running TT_KEEP", tp, __func__);
356 tt->tt_keep = 0;
357 down = tcp_timer_keep(tp, inp);
358 break;
359 case TT_2MSL:
360 CTR2(KTR_NET, "%p %s running TT_2MSL", tp, __func__);
361 tt->tt_2msl = 0;
362 down = tcp_timer_2msl(tp, inp);
363 break;
364 default:
365 CTR2(KTR_NET, "%p %s running nothing", tp, __func__);
366 down = 0;
367 }
368
369 CTR4(KTR_NET, "%p %s down %i active %x",
370 tp, __func__, down, tt->tt_active);
371 /* Do we still exist? */
372 if (down)
373 goto shutdown;
374
375rescan:
376 /* Rescan if no timer was reactivated above. */
377 if (tt->tt_active == 0)
378 tcp_timer_activate(tp, 0, 0);
379
380done:
381 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
382 return;
383
384shutdown:
385 INP_UNLOCK(inp); /* Prevent LOR at expense of race. */
386 INP_INFO_WLOCK(&tcbinfo);
387 INP_LOCK(inp);
388
389 /* When tp is gone we've lost the race. */
390 if (inp->inp_ppcb == NULL) {
391 CTR3(KTR_NET, "%p %s inp %p lost shutdown race",
392 tp, __func__, inp);
393 tcp_timer_race++;
394 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
395 INP_INFO_WUNLOCK(&tcbinfo);
396 return;
397 }
398 KASSERT(tp == inp->inp_ppcb, ("%s: tp changed", __func__));
399
400 /* Shutdown the connection. */
401 switch (down) {
402 case 1:
403 tp = tcp_close(tp);
404 break;
405 case 2:
406 tp = tcp_drop(tp,
407 tp->t_softerror ? tp->t_softerror : ETIMEDOUT);
408 break;
409 }
410 CTR3(KTR_NET, "%p %s inp %p after shutdown", tp, __func__, inp);
411
412 if (tp)
413 INP_UNLOCK(inp); /* CALLOUT_RETURNUNLOCKED */
414
415 INP_INFO_WUNLOCK(&tcbinfo);
416 return;
417}
418
|
420
| |
421/*
422 * TCP timer processing.
423 */
424static int
425tcp_timer_delack(struct tcpcb *tp, struct inpcb *inp)
426{
427
428 tp->t_flags |= TF_ACKNOW;
429 tcpstat.tcps_delack++;
430 (void) tcp_output(tp);
431 return (0);
432}
433
434static int
435tcp_timer_2msl(struct tcpcb *tp, struct inpcb *inp)
436{
437#ifdef TCPDEBUG
438 int ostate;
439
440 ostate = tp->t_state;
441#endif
442 /*
443 * 2 MSL timeout in shutdown went off. If we're closed but
444 * still waiting for peer to close and connection has been idle
445 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
446 * control block. Otherwise, check again in a bit.
447 *
448 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
449 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
450 * Ignore fact that there were recent incoming segments.
451 */
452 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
453 tp->t_inpcb->inp_socket &&
454 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
455 tcpstat.tcps_finwait2_drops++;
456 return (1); /* tcp_close */
457 } else {
458 if (tp->t_state != TCPS_TIME_WAIT &&
459 (ticks - tp->t_rcvtime) <= tcp_maxidle)
460 tcp_timer_activate(tp, TT_2MSL, tcp_keepintvl);
461 else
462 return (1); /* tcp_close */
463 }
464
465#ifdef TCPDEBUG
466 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
467 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
468 PRU_SLOWTIMO);
469#endif
470 return (0);
471}
472
473/*
474 * The timed wait queue contains references to each of the TCP sessions
475 * currently in the TIME_WAIT state. The queue pointers, including the
476 * queue pointers in each tcptw structure, are protected using the global
477 * tcbinfo lock, which must be held over queue iteration and modification.
478 */
479static TAILQ_HEAD(, tcptw) twq_2msl;
480
481void
482tcp_timer_init(void)
483{
484
485 TAILQ_INIT(&twq_2msl);
486}
487
488void
489tcp_timer_2msl_reset(struct tcptw *tw, int rearm)
490{
491
492 INP_INFO_WLOCK_ASSERT(&tcbinfo);
493 INP_LOCK_ASSERT(tw->tw_inpcb);
494 if (rearm)
495 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
496 tw->tw_time = ticks + 2 * tcp_msl;
497 TAILQ_INSERT_TAIL(&twq_2msl, tw, tw_2msl);
498}
499
500void
501tcp_timer_2msl_stop(struct tcptw *tw)
502{
503
504 INP_INFO_WLOCK_ASSERT(&tcbinfo);
505 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
506}
507
508struct tcptw *
509tcp_timer_2msl_tw(int reuse)
510{
511 struct tcptw *tw;
512
513 INP_INFO_WLOCK_ASSERT(&tcbinfo);
514 for (;;) {
515 tw = TAILQ_FIRST(&twq_2msl);
516 if (tw == NULL || (!reuse && tw->tw_time > ticks))
517 break;
518 INP_LOCK(tw->tw_inpcb);
519 tcp_twclose(tw, reuse);
520 if (reuse)
521 return (tw);
522 }
523 return (NULL);
524}
525
526static int
527tcp_timer_keep(struct tcpcb *tp, struct inpcb *inp)
528{
529 struct tcptemp *t_template;
530#ifdef TCPDEBUG
531 int ostate;
532
533 ostate = tp->t_state;
534#endif
535 /*
536 * Keep-alive timer went off; send something
537 * or drop connection if idle for too long.
538 */
539 tcpstat.tcps_keeptimeo++;
540 if (tp->t_state < TCPS_ESTABLISHED)
541 goto dropit;
542 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
543 tp->t_state <= TCPS_CLOSING) {
544 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle)
545 goto dropit;
546 /*
547 * Send a packet designed to force a response
548 * if the peer is up and reachable:
549 * either an ACK if the connection is still alive,
550 * or an RST if the peer has closed the connection
551 * due to timeout or reboot.
552 * Using sequence number tp->snd_una-1
553 * causes the transmitted zero-length segment
554 * to lie outside the receive window;
555 * by the protocol spec, this requires the
556 * correspondent TCP to respond.
557 */
558 tcpstat.tcps_keepprobe++;
559 t_template = tcpip_maketemplate(inp);
560 if (t_template) {
561 tcp_respond(tp, t_template->tt_ipgen,
562 &t_template->tt_t, (struct mbuf *)NULL,
563 tp->rcv_nxt, tp->snd_una - 1, 0);
564 (void) m_free(dtom(t_template));
565 }
566 tcp_timer_activate(tp, TT_KEEP, tcp_keepintvl);
567 } else
568 tcp_timer_activate(tp, TT_KEEP, tcp_keepidle);
569
570#ifdef TCPDEBUG
571 if (inp->inp_socket->so_options & SO_DEBUG)
572 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
573 PRU_SLOWTIMO);
574#endif
575 return (0);
576
577dropit:
578 tcpstat.tcps_keepdrops++;
579 return (2); /* tcp_drop() */
580}
581
582static int
583tcp_timer_persist(struct tcpcb *tp, struct inpcb *inp)
584{
585#ifdef TCPDEBUG
586 int ostate;
587
588 ostate = tp->t_state;
589#endif
590 /*
591 * Persistance timer into zero window.
592 * Force a byte to be output, if possible.
593 */
594 tcpstat.tcps_persisttimeo++;
595 /*
596 * Hack: if the peer is dead/unreachable, we do not
597 * time out if the window is closed. After a full
598 * backoff, drop the connection if the idle time
599 * (no responses to probes) reaches the maximum
600 * backoff that we would use if retransmitting.
601 */
602 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
603 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle ||
604 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
605 tcpstat.tcps_persistdrop++;
606 return (2); /* tcp_drop() */
607 }
608 tcp_setpersist(tp);
609 tp->t_flags |= TF_FORCEDATA;
610 (void) tcp_output(tp);
611 tp->t_flags &= ~TF_FORCEDATA;
612
613#ifdef TCPDEBUG
614 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
615 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
616#endif
617 return (0);
618}
619
620static int
621tcp_timer_rexmt(struct tcpcb *tp, struct inpcb *inp)
622{
623 int rexmt;
624#ifdef TCPDEBUG
625 int ostate;
626
627 ostate = tp->t_state;
628#endif
629 tcp_free_sackholes(tp);
630 /*
631 * Retransmission timer went off. Message has not
632 * been acked within retransmit interval. Back off
633 * to a longer retransmit interval and retransmit one segment.
634 */
635 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
636 tp->t_rxtshift = TCP_MAXRXTSHIFT;
637 tcpstat.tcps_timeoutdrop++;
638 return (2); /* tcp_drop() */
639 }
640 if (tp->t_rxtshift == 1) {
641 /*
642 * first retransmit; record ssthresh and cwnd so they can
643 * be recovered if this turns out to be a "bad" retransmit.
644 * A retransmit is considered "bad" if an ACK for this
645 * segment is received within RTT/2 interval; the assumption
646 * here is that the ACK was already in flight. See
647 * "On Estimating End-to-End Network Path Properties" by
648 * Allman and Paxson for more details.
649 */
650 tp->snd_cwnd_prev = tp->snd_cwnd;
651 tp->snd_ssthresh_prev = tp->snd_ssthresh;
652 tp->snd_recover_prev = tp->snd_recover;
653 if (IN_FASTRECOVERY(tp))
654 tp->t_flags |= TF_WASFRECOVERY;
655 else
656 tp->t_flags &= ~TF_WASFRECOVERY;
657 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
658 }
659 tcpstat.tcps_rexmttimeo++;
660 if (tp->t_state == TCPS_SYN_SENT)
661 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift];
662 else
663 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
664 TCPT_RANGESET(tp->t_rxtcur, rexmt,
665 tp->t_rttmin, TCPTV_REXMTMAX);
666 /*
667 * Disable rfc1323 if we havn't got any response to
668 * our third SYN to work-around some broken terminal servers
669 * (most of which have hopefully been retired) that have bad VJ
670 * header compression code which trashes TCP segments containing
671 * unknown-to-them TCP options.
672 */
673 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3))
674 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP);
675 /*
676 * If we backed off this far, our srtt estimate is probably bogus.
677 * Clobber it so we'll take the next rtt measurement as our srtt;
678 * move the current srtt into rttvar to keep the current
679 * retransmit times until then.
680 */
681 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
682#ifdef INET6
683 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
684 in6_losing(tp->t_inpcb);
685 else
686#endif
687 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
688 tp->t_srtt = 0;
689 }
690 tp->snd_nxt = tp->snd_una;
691 tp->snd_recover = tp->snd_max;
692 /*
693 * Force a segment to be sent.
694 */
695 tp->t_flags |= TF_ACKNOW;
696 /*
697 * If timing a segment in this window, stop the timer.
698 */
699 tp->t_rtttime = 0;
700 /*
701 * Close the congestion window down to one segment
702 * (we'll open it by one segment for each ack we get).
703 * Since we probably have a window's worth of unacked
704 * data accumulated, this "slow start" keeps us from
705 * dumping all that data as back-to-back packets (which
706 * might overwhelm an intermediate gateway).
707 *
708 * There are two phases to the opening: Initially we
709 * open by one mss on each ack. This makes the window
710 * size increase exponentially with time. If the
711 * window is larger than the path can handle, this
712 * exponential growth results in dropped packet(s)
713 * almost immediately. To get more time between
714 * drops but still "push" the network to take advantage
715 * of improving conditions, we switch from exponential
716 * to linear window opening at some threshhold size.
717 * For a threshhold, we use half the current window
718 * size, truncated to a multiple of the mss.
719 *
720 * (the minimum cwnd that will give us exponential
721 * growth is 2 mss. We don't allow the threshhold
722 * to go below this.)
723 */
724 {
725 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
726 if (win < 2)
727 win = 2;
728 tp->snd_cwnd = tp->t_maxseg;
729 tp->snd_ssthresh = win * tp->t_maxseg;
730 tp->t_dupacks = 0;
731 }
732 EXIT_FASTRECOVERY(tp);
733 (void) tcp_output(tp);
734
735#ifdef TCPDEBUG
736 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
737 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
738 PRU_SLOWTIMO);
739#endif
740 return (0);
741}
| 419/*
420 * TCP timer processing.
421 */
422static int
423tcp_timer_delack(struct tcpcb *tp, struct inpcb *inp)
424{
425
426 tp->t_flags |= TF_ACKNOW;
427 tcpstat.tcps_delack++;
428 (void) tcp_output(tp);
429 return (0);
430}
431
432static int
433tcp_timer_2msl(struct tcpcb *tp, struct inpcb *inp)
434{
435#ifdef TCPDEBUG
436 int ostate;
437
438 ostate = tp->t_state;
439#endif
440 /*
441 * 2 MSL timeout in shutdown went off. If we're closed but
442 * still waiting for peer to close and connection has been idle
443 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
444 * control block. Otherwise, check again in a bit.
445 *
446 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
447 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
448 * Ignore fact that there were recent incoming segments.
449 */
450 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
451 tp->t_inpcb->inp_socket &&
452 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
453 tcpstat.tcps_finwait2_drops++;
454 return (1); /* tcp_close */
455 } else {
456 if (tp->t_state != TCPS_TIME_WAIT &&
457 (ticks - tp->t_rcvtime) <= tcp_maxidle)
458 tcp_timer_activate(tp, TT_2MSL, tcp_keepintvl);
459 else
460 return (1); /* tcp_close */
461 }
462
463#ifdef TCPDEBUG
464 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
465 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
466 PRU_SLOWTIMO);
467#endif
468 return (0);
469}
470
471/*
472 * The timed wait queue contains references to each of the TCP sessions
473 * currently in the TIME_WAIT state. The queue pointers, including the
474 * queue pointers in each tcptw structure, are protected using the global
475 * tcbinfo lock, which must be held over queue iteration and modification.
476 */
477static TAILQ_HEAD(, tcptw) twq_2msl;
478
479void
480tcp_timer_init(void)
481{
482
483 TAILQ_INIT(&twq_2msl);
484}
485
486void
487tcp_timer_2msl_reset(struct tcptw *tw, int rearm)
488{
489
490 INP_INFO_WLOCK_ASSERT(&tcbinfo);
491 INP_LOCK_ASSERT(tw->tw_inpcb);
492 if (rearm)
493 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
494 tw->tw_time = ticks + 2 * tcp_msl;
495 TAILQ_INSERT_TAIL(&twq_2msl, tw, tw_2msl);
496}
497
498void
499tcp_timer_2msl_stop(struct tcptw *tw)
500{
501
502 INP_INFO_WLOCK_ASSERT(&tcbinfo);
503 TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
504}
505
506struct tcptw *
507tcp_timer_2msl_tw(int reuse)
508{
509 struct tcptw *tw;
510
511 INP_INFO_WLOCK_ASSERT(&tcbinfo);
512 for (;;) {
513 tw = TAILQ_FIRST(&twq_2msl);
514 if (tw == NULL || (!reuse && tw->tw_time > ticks))
515 break;
516 INP_LOCK(tw->tw_inpcb);
517 tcp_twclose(tw, reuse);
518 if (reuse)
519 return (tw);
520 }
521 return (NULL);
522}
523
524static int
525tcp_timer_keep(struct tcpcb *tp, struct inpcb *inp)
526{
527 struct tcptemp *t_template;
528#ifdef TCPDEBUG
529 int ostate;
530
531 ostate = tp->t_state;
532#endif
533 /*
534 * Keep-alive timer went off; send something
535 * or drop connection if idle for too long.
536 */
537 tcpstat.tcps_keeptimeo++;
538 if (tp->t_state < TCPS_ESTABLISHED)
539 goto dropit;
540 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
541 tp->t_state <= TCPS_CLOSING) {
542 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle)
543 goto dropit;
544 /*
545 * Send a packet designed to force a response
546 * if the peer is up and reachable:
547 * either an ACK if the connection is still alive,
548 * or an RST if the peer has closed the connection
549 * due to timeout or reboot.
550 * Using sequence number tp->snd_una-1
551 * causes the transmitted zero-length segment
552 * to lie outside the receive window;
553 * by the protocol spec, this requires the
554 * correspondent TCP to respond.
555 */
556 tcpstat.tcps_keepprobe++;
557 t_template = tcpip_maketemplate(inp);
558 if (t_template) {
559 tcp_respond(tp, t_template->tt_ipgen,
560 &t_template->tt_t, (struct mbuf *)NULL,
561 tp->rcv_nxt, tp->snd_una - 1, 0);
562 (void) m_free(dtom(t_template));
563 }
564 tcp_timer_activate(tp, TT_KEEP, tcp_keepintvl);
565 } else
566 tcp_timer_activate(tp, TT_KEEP, tcp_keepidle);
567
568#ifdef TCPDEBUG
569 if (inp->inp_socket->so_options & SO_DEBUG)
570 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
571 PRU_SLOWTIMO);
572#endif
573 return (0);
574
575dropit:
576 tcpstat.tcps_keepdrops++;
577 return (2); /* tcp_drop() */
578}
579
580static int
581tcp_timer_persist(struct tcpcb *tp, struct inpcb *inp)
582{
583#ifdef TCPDEBUG
584 int ostate;
585
586 ostate = tp->t_state;
587#endif
588 /*
589 * Persistance timer into zero window.
590 * Force a byte to be output, if possible.
591 */
592 tcpstat.tcps_persisttimeo++;
593 /*
594 * Hack: if the peer is dead/unreachable, we do not
595 * time out if the window is closed. After a full
596 * backoff, drop the connection if the idle time
597 * (no responses to probes) reaches the maximum
598 * backoff that we would use if retransmitting.
599 */
600 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
601 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle ||
602 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
603 tcpstat.tcps_persistdrop++;
604 return (2); /* tcp_drop() */
605 }
606 tcp_setpersist(tp);
607 tp->t_flags |= TF_FORCEDATA;
608 (void) tcp_output(tp);
609 tp->t_flags &= ~TF_FORCEDATA;
610
611#ifdef TCPDEBUG
612 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
613 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
614#endif
615 return (0);
616}
617
618static int
619tcp_timer_rexmt(struct tcpcb *tp, struct inpcb *inp)
620{
621 int rexmt;
622#ifdef TCPDEBUG
623 int ostate;
624
625 ostate = tp->t_state;
626#endif
627 tcp_free_sackholes(tp);
628 /*
629 * Retransmission timer went off. Message has not
630 * been acked within retransmit interval. Back off
631 * to a longer retransmit interval and retransmit one segment.
632 */
633 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
634 tp->t_rxtshift = TCP_MAXRXTSHIFT;
635 tcpstat.tcps_timeoutdrop++;
636 return (2); /* tcp_drop() */
637 }
638 if (tp->t_rxtshift == 1) {
639 /*
640 * first retransmit; record ssthresh and cwnd so they can
641 * be recovered if this turns out to be a "bad" retransmit.
642 * A retransmit is considered "bad" if an ACK for this
643 * segment is received within RTT/2 interval; the assumption
644 * here is that the ACK was already in flight. See
645 * "On Estimating End-to-End Network Path Properties" by
646 * Allman and Paxson for more details.
647 */
648 tp->snd_cwnd_prev = tp->snd_cwnd;
649 tp->snd_ssthresh_prev = tp->snd_ssthresh;
650 tp->snd_recover_prev = tp->snd_recover;
651 if (IN_FASTRECOVERY(tp))
652 tp->t_flags |= TF_WASFRECOVERY;
653 else
654 tp->t_flags &= ~TF_WASFRECOVERY;
655 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
656 }
657 tcpstat.tcps_rexmttimeo++;
658 if (tp->t_state == TCPS_SYN_SENT)
659 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift];
660 else
661 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
662 TCPT_RANGESET(tp->t_rxtcur, rexmt,
663 tp->t_rttmin, TCPTV_REXMTMAX);
664 /*
665 * Disable rfc1323 if we havn't got any response to
666 * our third SYN to work-around some broken terminal servers
667 * (most of which have hopefully been retired) that have bad VJ
668 * header compression code which trashes TCP segments containing
669 * unknown-to-them TCP options.
670 */
671 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3))
672 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP);
673 /*
674 * If we backed off this far, our srtt estimate is probably bogus.
675 * Clobber it so we'll take the next rtt measurement as our srtt;
676 * move the current srtt into rttvar to keep the current
677 * retransmit times until then.
678 */
679 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
680#ifdef INET6
681 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
682 in6_losing(tp->t_inpcb);
683 else
684#endif
685 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
686 tp->t_srtt = 0;
687 }
688 tp->snd_nxt = tp->snd_una;
689 tp->snd_recover = tp->snd_max;
690 /*
691 * Force a segment to be sent.
692 */
693 tp->t_flags |= TF_ACKNOW;
694 /*
695 * If timing a segment in this window, stop the timer.
696 */
697 tp->t_rtttime = 0;
698 /*
699 * Close the congestion window down to one segment
700 * (we'll open it by one segment for each ack we get).
701 * Since we probably have a window's worth of unacked
702 * data accumulated, this "slow start" keeps us from
703 * dumping all that data as back-to-back packets (which
704 * might overwhelm an intermediate gateway).
705 *
706 * There are two phases to the opening: Initially we
707 * open by one mss on each ack. This makes the window
708 * size increase exponentially with time. If the
709 * window is larger than the path can handle, this
710 * exponential growth results in dropped packet(s)
711 * almost immediately. To get more time between
712 * drops but still "push" the network to take advantage
713 * of improving conditions, we switch from exponential
714 * to linear window opening at some threshhold size.
715 * For a threshhold, we use half the current window
716 * size, truncated to a multiple of the mss.
717 *
718 * (the minimum cwnd that will give us exponential
719 * growth is 2 mss. We don't allow the threshhold
720 * to go below this.)
721 */
722 {
723 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
724 if (win < 2)
725 win = 2;
726 tp->snd_cwnd = tp->t_maxseg;
727 tp->snd_ssthresh = win * tp->t_maxseg;
728 tp->t_dupacks = 0;
729 }
730 EXIT_FASTRECOVERY(tp);
731 (void) tcp_output(tp);
732
733#ifdef TCPDEBUG
734 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
735 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
736 PRU_SLOWTIMO);
737#endif
738 return (0);
739}
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