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 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_tcpdebug.h"
38 #include "opt_rss.h"
39
40 #include <sys/param.h>
41 #include <sys/kernel.h>
42 #include <sys/lock.h>
43 #include <sys/mbuf.h>
44 #include <sys/mutex.h>
45 #include <sys/protosw.h>
46 #include <sys/smp.h>
47 #include <sys/socket.h>
48 #include <sys/socketvar.h>
49 #include <sys/sysctl.h>
50 #include <sys/systm.h>
51
52 #include <net/if.h>
53 #include <net/route.h>
54 #include <net/rss_config.h>
55 #include <net/vnet.h>
56 #include <net/netisr.h>
57
58 #include <netinet/in.h>
59 #include <netinet/in_kdtrace.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/in_rss.h>
62 #include <netinet/in_systm.h>
63 #ifdef INET6
64 #include <netinet6/in6_pcb.h>
65 #endif
66 #include <netinet/ip_var.h>
67 #include <netinet/tcp.h>
68 #include <netinet/tcp_fsm.h>
69 #include <netinet/tcp_timer.h>
70 #include <netinet/tcp_var.h>
71 #include <netinet/cc/cc.h>
72 #ifdef INET6
73 #include <netinet6/tcp6_var.h>
74 #endif
75 #include <netinet/tcpip.h>
76 #ifdef TCPDEBUG
77 #include <netinet/tcp_debug.h>
78 #endif
79
80 int tcp_persmin;
81 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
82 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
83
84 int tcp_persmax;
85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
86 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
87
88 int tcp_keepinit;
89 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
91
92 int tcp_keepidle;
93 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
94 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
95
96 int tcp_keepintvl;
97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
98 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
99
100 int tcp_delacktime;
101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
102 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
103 "Time before a delayed ACK is sent");
104
105 int tcp_msl;
106 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
107 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
108
109 int tcp_rexmit_min;
110 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
111 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
112 "Minimum Retransmission Timeout");
113
114 int tcp_rexmit_slop;
115 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
116 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
117 "Retransmission Timer Slop");
118
119 int tcp_always_keepalive = 1;
120 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
121 &tcp_always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
122 __strong_reference(tcp_always_keepalive, always_keepalive);
123
124 int tcp_fast_finwait2_recycle = 0;
125 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
126 &tcp_fast_finwait2_recycle, 0,
127 "Recycle closed FIN_WAIT_2 connections faster");
128
129 int tcp_finwait2_timeout;
130 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
131 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
132
133 int tcp_keepcnt = TCPTV_KEEPCNT;
134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
135 "Number of keepalive probes to send");
136
137 /* max idle probes */
138 int tcp_maxpersistidle;
139
140 static int tcp_rexmit_drop_options = 0;
141 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
142 &tcp_rexmit_drop_options, 0,
143 "Drop TCP options from 3rd and later retransmitted SYN");
144
145 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
146 #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect)
147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
148 CTLFLAG_RW|CTLFLAG_VNET,
149 &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
150 "Path MTU Discovery Black Hole Detection Enabled");
151
152 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
153 #define V_tcp_pmtud_blackhole_activated \
154 VNET(tcp_pmtud_blackhole_activated)
155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
156 CTLFLAG_RD|CTLFLAG_VNET,
157 &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
158 "Path MTU Discovery Black Hole Detection, Activation Count");
159
160 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
161 #define V_tcp_pmtud_blackhole_activated_min_mss \
162 VNET(tcp_pmtud_blackhole_activated_min_mss)
163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
164 CTLFLAG_RD|CTLFLAG_VNET,
165 &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
166 "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
167
168 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
169 #define V_tcp_pmtud_blackhole_failed VNET(tcp_pmtud_blackhole_failed)
170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
171 CTLFLAG_RD|CTLFLAG_VNET,
172 &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
173 "Path MTU Discovery Black Hole Detection, Failure Count");
174
175 #ifdef INET
176 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
177 #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss)
178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
179 CTLFLAG_RW|CTLFLAG_VNET,
180 &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
181 "Path MTU Discovery Black Hole Detection lowered MSS");
182 #endif
183
184 #ifdef INET6
185 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
186 #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss)
187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
188 CTLFLAG_RW|CTLFLAG_VNET,
189 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
190 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
191 #endif
192
193 #ifdef RSS
194 static int per_cpu_timers = 1;
195 #else
196 static int per_cpu_timers = 0;
197 #endif
198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
199 &per_cpu_timers , 0, "run tcp timers on all cpus");
200
201 #if 0
202 #define INP_CPU(inp) (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
203 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
204 #endif
205
206 /*
207 * Map the given inp to a CPU id.
208 *
209 * This queries RSS if it's compiled in, else it defaults to the current
210 * CPU ID.
211 */
212 static inline int
inp_to_cpuid(struct inpcb * inp)213 inp_to_cpuid(struct inpcb *inp)
214 {
215 u_int cpuid;
216
217 #ifdef RSS
218 if (per_cpu_timers) {
219 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
220 if (cpuid == NETISR_CPUID_NONE)
221 return (curcpu); /* XXX */
222 else
223 return (cpuid);
224 }
225 #else
226 /* Legacy, pre-RSS behaviour */
227 if (per_cpu_timers) {
228 /*
229 * We don't have a flowid -> cpuid mapping, so cheat and
230 * just map unknown cpuids to curcpu. Not the best, but
231 * apparently better than defaulting to swi 0.
232 */
233 cpuid = inp->inp_flowid % (mp_maxid + 1);
234 if (! CPU_ABSENT(cpuid))
235 return (cpuid);
236 return (curcpu);
237 }
238 #endif
239 /* Default for RSS and non-RSS - cpuid 0 */
240 else {
241 return (0);
242 }
243 }
244
245 /*
246 * Tcp protocol timeout routine called every 500 ms.
247 * Updates timestamps used for TCP
248 * causes finite state machine actions if timers expire.
249 */
250 void
tcp_slowtimo(void)251 tcp_slowtimo(void)
252 {
253 VNET_ITERATOR_DECL(vnet_iter);
254
255 VNET_LIST_RLOCK_NOSLEEP();
256 VNET_FOREACH(vnet_iter) {
257 CURVNET_SET(vnet_iter);
258 (void) tcp_tw_2msl_scan(0);
259 CURVNET_RESTORE();
260 }
261 VNET_LIST_RUNLOCK_NOSLEEP();
262 }
263
264 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
265 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
266
267 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
268 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
269
270 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
271
272 /*
273 * TCP timer processing.
274 */
275
276 void
tcp_timer_delack(void * xtp)277 tcp_timer_delack(void *xtp)
278 {
279 struct tcpcb *tp = xtp;
280 struct inpcb *inp;
281 CURVNET_SET(tp->t_vnet);
282
283 inp = tp->t_inpcb;
284 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
285 INP_WLOCK(inp);
286 if (callout_pending(&tp->t_timers->tt_delack) ||
287 !callout_active(&tp->t_timers->tt_delack)) {
288 INP_WUNLOCK(inp);
289 CURVNET_RESTORE();
290 return;
291 }
292 callout_deactivate(&tp->t_timers->tt_delack);
293 if ((inp->inp_flags & INP_DROPPED) != 0) {
294 INP_WUNLOCK(inp);
295 CURVNET_RESTORE();
296 return;
297 }
298 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
299 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
300 KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0,
301 ("%s: tp %p delack callout should be running", __func__, tp));
302
303 tp->t_flags |= TF_ACKNOW;
304 TCPSTAT_INC(tcps_delack);
305 (void) tp->t_fb->tfb_tcp_output(tp);
306 INP_WUNLOCK(inp);
307 CURVNET_RESTORE();
308 }
309
310 void
tcp_timer_2msl(void * xtp)311 tcp_timer_2msl(void *xtp)
312 {
313 struct tcpcb *tp = xtp;
314 struct inpcb *inp;
315 CURVNET_SET(tp->t_vnet);
316 #ifdef TCPDEBUG
317 int ostate;
318
319 ostate = tp->t_state;
320 #endif
321 INP_INFO_RLOCK(&V_tcbinfo);
322 inp = tp->t_inpcb;
323 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
324 INP_WLOCK(inp);
325 tcp_free_sackholes(tp);
326 if (callout_pending(&tp->t_timers->tt_2msl) ||
327 !callout_active(&tp->t_timers->tt_2msl)) {
328 INP_WUNLOCK(tp->t_inpcb);
329 INP_INFO_RUNLOCK(&V_tcbinfo);
330 CURVNET_RESTORE();
331 return;
332 }
333 callout_deactivate(&tp->t_timers->tt_2msl);
334 if ((inp->inp_flags & INP_DROPPED) != 0) {
335 INP_WUNLOCK(inp);
336 INP_INFO_RUNLOCK(&V_tcbinfo);
337 CURVNET_RESTORE();
338 return;
339 }
340 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
341 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
342 KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0,
343 ("%s: tp %p 2msl callout should be running", __func__, tp));
344 /*
345 * 2 MSL timeout in shutdown went off. If we're closed but
346 * still waiting for peer to close and connection has been idle
347 * too long delete connection control block. Otherwise, check
348 * again in a bit.
349 *
350 * If in TIME_WAIT state just ignore as this timeout is handled in
351 * tcp_tw_2msl_scan().
352 *
353 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
354 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
355 * Ignore fact that there were recent incoming segments.
356 */
357 if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
358 INP_WUNLOCK(inp);
359 INP_INFO_RUNLOCK(&V_tcbinfo);
360 CURVNET_RESTORE();
361 return;
362 }
363 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
364 tp->t_inpcb && tp->t_inpcb->inp_socket &&
365 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
366 TCPSTAT_INC(tcps_finwait2_drops);
367 tp = tcp_close(tp);
368 } else {
369 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
370 if (!callout_reset(&tp->t_timers->tt_2msl,
371 TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) {
372 tp->t_timers->tt_flags &= ~TT_2MSL_RST;
373 }
374 } else
375 tp = tcp_close(tp);
376 }
377
378 #ifdef TCPDEBUG
379 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
380 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
381 PRU_SLOWTIMO);
382 #endif
383 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
384
385 if (tp != NULL)
386 INP_WUNLOCK(inp);
387 INP_INFO_RUNLOCK(&V_tcbinfo);
388 CURVNET_RESTORE();
389 }
390
391 void
tcp_timer_keep(void * xtp)392 tcp_timer_keep(void *xtp)
393 {
394 struct tcpcb *tp = xtp;
395 struct tcptemp *t_template;
396 struct inpcb *inp;
397 CURVNET_SET(tp->t_vnet);
398 #ifdef TCPDEBUG
399 int ostate;
400
401 ostate = tp->t_state;
402 #endif
403 INP_INFO_RLOCK(&V_tcbinfo);
404 inp = tp->t_inpcb;
405 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
406 INP_WLOCK(inp);
407 if (callout_pending(&tp->t_timers->tt_keep) ||
408 !callout_active(&tp->t_timers->tt_keep)) {
409 INP_WUNLOCK(inp);
410 INP_INFO_RUNLOCK(&V_tcbinfo);
411 CURVNET_RESTORE();
412 return;
413 }
414 callout_deactivate(&tp->t_timers->tt_keep);
415 if ((inp->inp_flags & INP_DROPPED) != 0) {
416 INP_WUNLOCK(inp);
417 INP_INFO_RUNLOCK(&V_tcbinfo);
418 CURVNET_RESTORE();
419 return;
420 }
421 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
422 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
423 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0,
424 ("%s: tp %p keep callout should be running", __func__, tp));
425 /*
426 * Keep-alive timer went off; send something
427 * or drop connection if idle for too long.
428 */
429 TCPSTAT_INC(tcps_keeptimeo);
430 if (tp->t_state < TCPS_ESTABLISHED)
431 goto dropit;
432 if ((tcp_always_keepalive ||
433 inp->inp_socket->so_options & SO_KEEPALIVE) &&
434 tp->t_state <= TCPS_CLOSING) {
435 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
436 goto dropit;
437 /*
438 * Send a packet designed to force a response
439 * if the peer is up and reachable:
440 * either an ACK if the connection is still alive,
441 * or an RST if the peer has closed the connection
442 * due to timeout or reboot.
443 * Using sequence number tp->snd_una-1
444 * causes the transmitted zero-length segment
445 * to lie outside the receive window;
446 * by the protocol spec, this requires the
447 * correspondent TCP to respond.
448 */
449 TCPSTAT_INC(tcps_keepprobe);
450 t_template = tcpip_maketemplate(inp);
451 if (t_template) {
452 tcp_respond(tp, t_template->tt_ipgen,
453 &t_template->tt_t, (struct mbuf *)NULL,
454 tp->rcv_nxt, tp->snd_una - 1, 0);
455 free(t_template, M_TEMP);
456 }
457 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
458 tcp_timer_keep, tp)) {
459 tp->t_timers->tt_flags &= ~TT_KEEP_RST;
460 }
461 } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
462 tcp_timer_keep, tp)) {
463 tp->t_timers->tt_flags &= ~TT_KEEP_RST;
464 }
465
466 #ifdef TCPDEBUG
467 if (inp->inp_socket->so_options & SO_DEBUG)
468 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
469 PRU_SLOWTIMO);
470 #endif
471 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
472 INP_WUNLOCK(inp);
473 INP_INFO_RUNLOCK(&V_tcbinfo);
474 CURVNET_RESTORE();
475 return;
476
477 dropit:
478 TCPSTAT_INC(tcps_keepdrops);
479 tp = tcp_drop(tp, ETIMEDOUT);
480
481 #ifdef TCPDEBUG
482 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
483 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
484 PRU_SLOWTIMO);
485 #endif
486 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
487 if (tp != NULL)
488 INP_WUNLOCK(tp->t_inpcb);
489 INP_INFO_RUNLOCK(&V_tcbinfo);
490 CURVNET_RESTORE();
491 }
492
493 void
tcp_timer_persist(void * xtp)494 tcp_timer_persist(void *xtp)
495 {
496 struct tcpcb *tp = xtp;
497 struct inpcb *inp;
498 CURVNET_SET(tp->t_vnet);
499 #ifdef TCPDEBUG
500 int ostate;
501
502 ostate = tp->t_state;
503 #endif
504 INP_INFO_RLOCK(&V_tcbinfo);
505 inp = tp->t_inpcb;
506 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
507 INP_WLOCK(inp);
508 if (callout_pending(&tp->t_timers->tt_persist) ||
509 !callout_active(&tp->t_timers->tt_persist)) {
510 INP_WUNLOCK(inp);
511 INP_INFO_RUNLOCK(&V_tcbinfo);
512 CURVNET_RESTORE();
513 return;
514 }
515 callout_deactivate(&tp->t_timers->tt_persist);
516 if ((inp->inp_flags & INP_DROPPED) != 0) {
517 INP_WUNLOCK(inp);
518 INP_INFO_RUNLOCK(&V_tcbinfo);
519 CURVNET_RESTORE();
520 return;
521 }
522 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
523 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
524 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0,
525 ("%s: tp %p persist callout should be running", __func__, tp));
526 /*
527 * Persistence timer into zero window.
528 * Force a byte to be output, if possible.
529 */
530 TCPSTAT_INC(tcps_persisttimeo);
531 /*
532 * Hack: if the peer is dead/unreachable, we do not
533 * time out if the window is closed. After a full
534 * backoff, drop the connection if the idle time
535 * (no responses to probes) reaches the maximum
536 * backoff that we would use if retransmitting.
537 */
538 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
539 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
540 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
541 TCPSTAT_INC(tcps_persistdrop);
542 tp = tcp_drop(tp, ETIMEDOUT);
543 goto out;
544 }
545 /*
546 * If the user has closed the socket then drop a persisting
547 * connection after a much reduced timeout.
548 */
549 if (tp->t_state > TCPS_CLOSE_WAIT &&
550 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
551 TCPSTAT_INC(tcps_persistdrop);
552 tp = tcp_drop(tp, ETIMEDOUT);
553 goto out;
554 }
555 tcp_setpersist(tp);
556 tp->t_flags |= TF_FORCEDATA;
557 (void) tp->t_fb->tfb_tcp_output(tp);
558 tp->t_flags &= ~TF_FORCEDATA;
559
560 out:
561 #ifdef TCPDEBUG
562 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
563 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
564 #endif
565 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
566 if (tp != NULL)
567 INP_WUNLOCK(inp);
568 INP_INFO_RUNLOCK(&V_tcbinfo);
569 CURVNET_RESTORE();
570 }
571
572 void
tcp_timer_rexmt(void * xtp)573 tcp_timer_rexmt(void * xtp)
574 {
575 struct tcpcb *tp = xtp;
576 CURVNET_SET(tp->t_vnet);
577 int rexmt;
578 int headlocked;
579 struct inpcb *inp;
580 #ifdef TCPDEBUG
581 int ostate;
582
583 ostate = tp->t_state;
584 #endif
585
586 INP_INFO_RLOCK(&V_tcbinfo);
587 inp = tp->t_inpcb;
588 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
589 INP_WLOCK(inp);
590 if (callout_pending(&tp->t_timers->tt_rexmt) ||
591 !callout_active(&tp->t_timers->tt_rexmt)) {
592 INP_WUNLOCK(inp);
593 INP_INFO_RUNLOCK(&V_tcbinfo);
594 CURVNET_RESTORE();
595 return;
596 }
597 callout_deactivate(&tp->t_timers->tt_rexmt);
598 if ((inp->inp_flags & INP_DROPPED) != 0) {
599 INP_WUNLOCK(inp);
600 INP_INFO_RUNLOCK(&V_tcbinfo);
601 CURVNET_RESTORE();
602 return;
603 }
604 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
605 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
606 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0,
607 ("%s: tp %p rexmt callout should be running", __func__, tp));
608 tcp_free_sackholes(tp);
609 if (tp->t_fb->tfb_tcp_rexmit_tmr) {
610 /* The stack has a timer action too. */
611 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
612 }
613 /*
614 * Retransmission timer went off. Message has not
615 * been acked within retransmit interval. Back off
616 * to a longer retransmit interval and retransmit one segment.
617 */
618 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
619 tp->t_rxtshift = TCP_MAXRXTSHIFT;
620 TCPSTAT_INC(tcps_timeoutdrop);
621
622 tp = tcp_drop(tp, ETIMEDOUT);
623 headlocked = 1;
624 goto out;
625 }
626 INP_INFO_RUNLOCK(&V_tcbinfo);
627 headlocked = 0;
628 if (tp->t_state == TCPS_SYN_SENT) {
629 /*
630 * If the SYN was retransmitted, indicate CWND to be
631 * limited to 1 segment in cc_conn_init().
632 */
633 tp->snd_cwnd = 1;
634 } else if (tp->t_rxtshift == 1) {
635 /*
636 * first retransmit; record ssthresh and cwnd so they can
637 * be recovered if this turns out to be a "bad" retransmit.
638 * A retransmit is considered "bad" if an ACK for this
639 * segment is received within RTT/2 interval; the assumption
640 * here is that the ACK was already in flight. See
641 * "On Estimating End-to-End Network Path Properties" by
642 * Allman and Paxson for more details.
643 */
644 tp->snd_cwnd_prev = tp->snd_cwnd;
645 tp->snd_ssthresh_prev = tp->snd_ssthresh;
646 tp->snd_recover_prev = tp->snd_recover;
647 if (IN_FASTRECOVERY(tp->t_flags))
648 tp->t_flags |= TF_WASFRECOVERY;
649 else
650 tp->t_flags &= ~TF_WASFRECOVERY;
651 if (IN_CONGRECOVERY(tp->t_flags))
652 tp->t_flags |= TF_WASCRECOVERY;
653 else
654 tp->t_flags &= ~TF_WASCRECOVERY;
655 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
656 tp->t_flags |= TF_PREVVALID;
657 } else
658 tp->t_flags &= ~TF_PREVVALID;
659 TCPSTAT_INC(tcps_rexmttimeo);
660 if ((tp->t_state == TCPS_SYN_SENT) ||
661 (tp->t_state == TCPS_SYN_RECEIVED))
662 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
663 else
664 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
665 TCPT_RANGESET(tp->t_rxtcur, rexmt,
666 tp->t_rttmin, TCPTV_REXMTMAX);
667
668 /*
669 * We enter the path for PLMTUD if connection is established or, if
670 * connection is FIN_WAIT_1 status, reason for the last is that if
671 * amount of data we send is very small, we could send it in couple of
672 * packets and process straight to FIN. In that case we won't catch
673 * ESTABLISHED state.
674 */
675 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
676 || (tp->t_state == TCPS_FIN_WAIT_1))) {
677 #ifdef INET6
678 int isipv6;
679 #endif
680
681 /*
682 * Idea here is that at each stage of mtu probe (usually, 1448
683 * -> 1188 -> 524) should be given 2 chances to recover before
684 * further clamping down. 'tp->t_rxtshift % 2 == 0' should
685 * take care of that.
686 */
687 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
688 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
689 (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
690 tp->t_rxtshift % 2 == 0)) {
691 /*
692 * Enter Path MTU Black-hole Detection mechanism:
693 * - Disable Path MTU Discovery (IP "DF" bit).
694 * - Reduce MTU to lower value than what we
695 * negotiated with peer.
696 */
697 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
698 /* Record that we may have found a black hole. */
699 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
700 /* Keep track of previous MSS. */
701 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
702 }
703
704 /*
705 * Reduce the MSS to blackhole value or to the default
706 * in an attempt to retransmit.
707 */
708 #ifdef INET6
709 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
710 if (isipv6 &&
711 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
712 /* Use the sysctl tuneable blackhole MSS. */
713 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
714 V_tcp_pmtud_blackhole_activated++;
715 } else if (isipv6) {
716 /* Use the default MSS. */
717 tp->t_maxseg = V_tcp_v6mssdflt;
718 /*
719 * Disable Path MTU Discovery when we switch to
720 * minmss.
721 */
722 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
723 V_tcp_pmtud_blackhole_activated_min_mss++;
724 }
725 #endif
726 #if defined(INET6) && defined(INET)
727 else
728 #endif
729 #ifdef INET
730 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
731 /* Use the sysctl tuneable blackhole MSS. */
732 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
733 V_tcp_pmtud_blackhole_activated++;
734 } else {
735 /* Use the default MSS. */
736 tp->t_maxseg = V_tcp_mssdflt;
737 /*
738 * Disable Path MTU Discovery when we switch to
739 * minmss.
740 */
741 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
742 V_tcp_pmtud_blackhole_activated_min_mss++;
743 }
744 #endif
745 /*
746 * Reset the slow-start flight size
747 * as it may depend on the new MSS.
748 */
749 if (CC_ALGO(tp)->conn_init != NULL)
750 CC_ALGO(tp)->conn_init(tp->ccv);
751 } else {
752 /*
753 * If further retransmissions are still unsuccessful
754 * with a lowered MTU, maybe this isn't a blackhole and
755 * we restore the previous MSS and blackhole detection
756 * flags.
757 * The limit '6' is determined by giving each probe
758 * stage (1448, 1188, 524) 2 chances to recover.
759 */
760 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
761 (tp->t_rxtshift >= 6)) {
762 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
763 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
764 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
765 V_tcp_pmtud_blackhole_failed++;
766 /*
767 * Reset the slow-start flight size as it
768 * may depend on the new MSS.
769 */
770 if (CC_ALGO(tp)->conn_init != NULL)
771 CC_ALGO(tp)->conn_init(tp->ccv);
772 }
773 }
774 }
775
776 /*
777 * Disable RFC1323 and SACK if we haven't got any response to
778 * our third SYN to work-around some broken terminal servers
779 * (most of which have hopefully been retired) that have bad VJ
780 * header compression code which trashes TCP segments containing
781 * unknown-to-them TCP options.
782 */
783 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
784 (tp->t_rxtshift == 3))
785 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
786 /*
787 * If we backed off this far, our srtt estimate is probably bogus.
788 * Clobber it so we'll take the next rtt measurement as our srtt;
789 * move the current srtt into rttvar to keep the current
790 * retransmit times until then.
791 */
792 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
793 #ifdef INET6
794 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
795 in6_losing(tp->t_inpcb);
796 else
797 #endif
798 in_losing(tp->t_inpcb);
799 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
800 tp->t_srtt = 0;
801 }
802 tp->snd_nxt = tp->snd_una;
803 tp->snd_recover = tp->snd_max;
804 /*
805 * Force a segment to be sent.
806 */
807 tp->t_flags |= TF_ACKNOW;
808 /*
809 * If timing a segment in this window, stop the timer.
810 */
811 tp->t_rtttime = 0;
812
813 cc_cong_signal(tp, NULL, CC_RTO);
814
815 (void) tp->t_fb->tfb_tcp_output(tp);
816
817 out:
818 #ifdef TCPDEBUG
819 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
820 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
821 PRU_SLOWTIMO);
822 #endif
823 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
824 if (tp != NULL)
825 INP_WUNLOCK(inp);
826 if (headlocked)
827 INP_INFO_RUNLOCK(&V_tcbinfo);
828 CURVNET_RESTORE();
829 }
830
831 void
tcp_timer_activate(struct tcpcb * tp,uint32_t timer_type,u_int delta)832 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
833 {
834 struct callout *t_callout;
835 timeout_t *f_callout;
836 struct inpcb *inp = tp->t_inpcb;
837 int cpu = inp_to_cpuid(inp);
838 uint32_t f_reset;
839
840 #ifdef TCP_OFFLOAD
841 if (tp->t_flags & TF_TOE)
842 return;
843 #endif
844
845 if (tp->t_timers->tt_flags & TT_STOPPED)
846 return;
847
848 switch (timer_type) {
849 case TT_DELACK:
850 t_callout = &tp->t_timers->tt_delack;
851 f_callout = tcp_timer_delack;
852 f_reset = TT_DELACK_RST;
853 break;
854 case TT_REXMT:
855 t_callout = &tp->t_timers->tt_rexmt;
856 f_callout = tcp_timer_rexmt;
857 f_reset = TT_REXMT_RST;
858 break;
859 case TT_PERSIST:
860 t_callout = &tp->t_timers->tt_persist;
861 f_callout = tcp_timer_persist;
862 f_reset = TT_PERSIST_RST;
863 break;
864 case TT_KEEP:
865 t_callout = &tp->t_timers->tt_keep;
866 f_callout = tcp_timer_keep;
867 f_reset = TT_KEEP_RST;
868 break;
869 case TT_2MSL:
870 t_callout = &tp->t_timers->tt_2msl;
871 f_callout = tcp_timer_2msl;
872 f_reset = TT_2MSL_RST;
873 break;
874 default:
875 if (tp->t_fb->tfb_tcp_timer_activate) {
876 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
877 return;
878 }
879 panic("tp %p bad timer_type %#x", tp, timer_type);
880 }
881 if (delta == 0) {
882 if ((tp->t_timers->tt_flags & timer_type) &&
883 (callout_stop(t_callout) > 0) &&
884 (tp->t_timers->tt_flags & f_reset)) {
885 tp->t_timers->tt_flags &= ~(timer_type | f_reset);
886 }
887 } else {
888 if ((tp->t_timers->tt_flags & timer_type) == 0) {
889 tp->t_timers->tt_flags |= (timer_type | f_reset);
890 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
891 } else {
892 /* Reset already running callout on the same CPU. */
893 if (!callout_reset(t_callout, delta, f_callout, tp)) {
894 /*
895 * Callout not cancelled, consider it as not
896 * properly restarted. */
897 tp->t_timers->tt_flags &= ~f_reset;
898 }
899 }
900 }
901 }
902
903 int
tcp_timer_active(struct tcpcb * tp,uint32_t timer_type)904 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
905 {
906 struct callout *t_callout;
907
908 switch (timer_type) {
909 case TT_DELACK:
910 t_callout = &tp->t_timers->tt_delack;
911 break;
912 case TT_REXMT:
913 t_callout = &tp->t_timers->tt_rexmt;
914 break;
915 case TT_PERSIST:
916 t_callout = &tp->t_timers->tt_persist;
917 break;
918 case TT_KEEP:
919 t_callout = &tp->t_timers->tt_keep;
920 break;
921 case TT_2MSL:
922 t_callout = &tp->t_timers->tt_2msl;
923 break;
924 default:
925 if (tp->t_fb->tfb_tcp_timer_active) {
926 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
927 }
928 panic("tp %p bad timer_type %#x", tp, timer_type);
929 }
930 return callout_active(t_callout);
931 }
932
933 void
tcp_timer_stop(struct tcpcb * tp,uint32_t timer_type)934 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
935 {
936 struct callout *t_callout;
937 uint32_t f_reset;
938
939 tp->t_timers->tt_flags |= TT_STOPPED;
940
941 switch (timer_type) {
942 case TT_DELACK:
943 t_callout = &tp->t_timers->tt_delack;
944 f_reset = TT_DELACK_RST;
945 break;
946 case TT_REXMT:
947 t_callout = &tp->t_timers->tt_rexmt;
948 f_reset = TT_REXMT_RST;
949 break;
950 case TT_PERSIST:
951 t_callout = &tp->t_timers->tt_persist;
952 f_reset = TT_PERSIST_RST;
953 break;
954 case TT_KEEP:
955 t_callout = &tp->t_timers->tt_keep;
956 f_reset = TT_KEEP_RST;
957 break;
958 case TT_2MSL:
959 t_callout = &tp->t_timers->tt_2msl;
960 f_reset = TT_2MSL_RST;
961 break;
962 default:
963 if (tp->t_fb->tfb_tcp_timer_stop) {
964 /*
965 * XXXrrs we need to look at this with the
966 * stop case below (flags).
967 */
968 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
969 return;
970 }
971 panic("tp %p bad timer_type %#x", tp, timer_type);
972 }
973
974 if (tp->t_timers->tt_flags & timer_type) {
975 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
976 /*
977 * Can't stop the callout, defer tcpcb actual deletion
978 * to the last one. We do this using the async drain
979 * function and incrementing the count in
980 */
981 tp->t_timers->tt_draincnt++;
982 }
983 }
984 }
985
986 #define ticks_to_msecs(t) (1000*(t) / hz)
987
988 void
tcp_timer_to_xtimer(struct tcpcb * tp,struct tcp_timer * timer,struct xtcp_timer * xtimer)989 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
990 struct xtcp_timer *xtimer)
991 {
992 sbintime_t now;
993
994 bzero(xtimer, sizeof(*xtimer));
995 if (timer == NULL)
996 return;
997 now = getsbinuptime();
998 if (callout_active(&timer->tt_delack))
999 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
1000 if (callout_active(&timer->tt_rexmt))
1001 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
1002 if (callout_active(&timer->tt_persist))
1003 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
1004 if (callout_active(&timer->tt_keep))
1005 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
1006 if (callout_active(&timer->tt_2msl))
1007 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
1008 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
1009 }
1010