1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_inet.h" 38 #include "opt_inet6.h" 39 #include "opt_tcpdebug.h" 40 #include "opt_rss.h" 41 42 #include <sys/param.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/mbuf.h> 46 #include <sys/mutex.h> 47 #include <sys/protosw.h> 48 #include <sys/smp.h> 49 #include <sys/socket.h> 50 #include <sys/socketvar.h> 51 #include <sys/sysctl.h> 52 #include <sys/systm.h> 53 54 #include <net/if.h> 55 #include <net/route.h> 56 #include <net/rss_config.h> 57 #include <net/vnet.h> 58 #include <net/netisr.h> 59 60 #include <netinet/in.h> 61 #include <netinet/in_kdtrace.h> 62 #include <netinet/in_pcb.h> 63 #include <netinet/in_rss.h> 64 #include <netinet/in_systm.h> 65 #ifdef INET6 66 #include <netinet6/in6_pcb.h> 67 #endif 68 #include <netinet/ip_var.h> 69 #include <netinet/tcp.h> 70 #include <netinet/tcp_fsm.h> 71 #include <netinet/tcp_log_buf.h> 72 #include <netinet/tcp_timer.h> 73 #include <netinet/tcp_var.h> 74 #include <netinet/tcp_seq.h> 75 #include <netinet/cc/cc.h> 76 #ifdef INET6 77 #include <netinet6/tcp6_var.h> 78 #endif 79 #include <netinet/tcpip.h> 80 #ifdef TCPDEBUG 81 #include <netinet/tcp_debug.h> 82 #endif 83 84 int tcp_persmin; 85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, 86 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 87 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", 88 "minimum persistence interval"); 89 90 int tcp_persmax; 91 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, 92 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 93 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", 94 "maximum persistence interval"); 95 96 int tcp_keepinit; 97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, 98 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 99 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", 100 "time to establish connection"); 101 102 int tcp_keepidle; 103 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, 104 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 105 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", 106 "time before keepalive probes begin"); 107 108 int tcp_keepintvl; 109 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, 110 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 111 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", 112 "time between keepalive probes"); 113 114 int tcp_delacktime; 115 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, 116 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 117 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", 118 "Time before a delayed ACK is sent"); 119 120 int tcp_msl; 121 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, 122 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 123 &tcp_msl, 0, sysctl_msec_to_ticks, "I", 124 "Maximum segment lifetime"); 125 126 int tcp_rexmit_initial; 127 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial, 128 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 129 &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I", 130 "Initial Retransmission Timeout"); 131 132 int tcp_rexmit_min; 133 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, 134 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 135 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", 136 "Minimum Retransmission Timeout"); 137 138 int tcp_rexmit_slop; 139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, 140 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 141 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", 142 "Retransmission Timer Slop"); 143 144 VNET_DEFINE(int, tcp_always_keepalive) = 1; 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW, 146 &VNET_NAME(tcp_always_keepalive) , 0, 147 "Assume SO_KEEPALIVE on all TCP connections"); 148 149 int tcp_fast_finwait2_recycle = 0; 150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW, 151 &tcp_fast_finwait2_recycle, 0, 152 "Recycle closed FIN_WAIT_2 connections faster"); 153 154 int tcp_finwait2_timeout; 155 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, 156 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 157 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", 158 "FIN-WAIT2 timeout"); 159 160 int tcp_keepcnt = TCPTV_KEEPCNT; 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0, 162 "Number of keepalive probes to send"); 163 164 /* max idle probes */ 165 int tcp_maxpersistidle; 166 167 int tcp_rexmit_drop_options = 0; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW, 169 &tcp_rexmit_drop_options, 0, 170 "Drop TCP options from 3rd and later retransmitted SYN"); 171 172 VNET_DEFINE(int, tcp_pmtud_blackhole_detect); 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, 174 CTLFLAG_RW|CTLFLAG_VNET, 175 &VNET_NAME(tcp_pmtud_blackhole_detect), 0, 176 "Path MTU Discovery Black Hole Detection Enabled"); 177 178 #ifdef INET 179 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200; 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, 181 CTLFLAG_RW|CTLFLAG_VNET, 182 &VNET_NAME(tcp_pmtud_blackhole_mss), 0, 183 "Path MTU Discovery Black Hole Detection lowered MSS"); 184 #endif 185 186 #ifdef INET6 187 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss, 189 CTLFLAG_RW|CTLFLAG_VNET, 190 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0, 191 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS"); 192 #endif 193 194 #ifdef RSS 195 static int per_cpu_timers = 1; 196 #else 197 static int per_cpu_timers = 0; 198 #endif 199 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW, 200 &per_cpu_timers , 0, "run tcp timers on all cpus"); 201 202 /* 203 * Map the given inp to a CPU id. 204 * 205 * This queries RSS if it's compiled in, else it defaults to the current 206 * CPU ID. 207 */ 208 inline int 209 inp_to_cpuid(struct inpcb *inp) 210 { 211 u_int cpuid; 212 213 #ifdef RSS 214 if (per_cpu_timers) { 215 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype); 216 if (cpuid == NETISR_CPUID_NONE) 217 return (curcpu); /* XXX */ 218 else 219 return (cpuid); 220 } 221 #else 222 /* Legacy, pre-RSS behaviour */ 223 if (per_cpu_timers) { 224 /* 225 * We don't have a flowid -> cpuid mapping, so cheat and 226 * just map unknown cpuids to curcpu. Not the best, but 227 * apparently better than defaulting to swi 0. 228 */ 229 cpuid = inp->inp_flowid % (mp_maxid + 1); 230 if (! CPU_ABSENT(cpuid)) 231 return (cpuid); 232 return (curcpu); 233 } 234 #endif 235 /* Default for RSS and non-RSS - cpuid 0 */ 236 else { 237 return (0); 238 } 239 } 240 241 /* 242 * Tcp protocol timeout routine called every 500 ms. 243 * Updates timestamps used for TCP 244 * causes finite state machine actions if timers expire. 245 */ 246 void 247 tcp_slowtimo(void) 248 { 249 VNET_ITERATOR_DECL(vnet_iter); 250 251 VNET_LIST_RLOCK_NOSLEEP(); 252 VNET_FOREACH(vnet_iter) { 253 CURVNET_SET(vnet_iter); 254 (void) tcp_tw_2msl_scan(0); 255 CURVNET_RESTORE(); 256 } 257 VNET_LIST_RUNLOCK_NOSLEEP(); 258 } 259 260 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 261 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 262 263 int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 264 265 /* 266 * TCP timer processing. 267 */ 268 269 void 270 tcp_timer_delack(void *xtp) 271 { 272 struct epoch_tracker et; 273 struct tcpcb *tp = xtp; 274 struct inpcb *inp; 275 CURVNET_SET(tp->t_vnet); 276 277 inp = tp->t_inpcb; 278 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 279 INP_WLOCK(inp); 280 if (callout_pending(&tp->t_timers->tt_delack) || 281 !callout_active(&tp->t_timers->tt_delack)) { 282 INP_WUNLOCK(inp); 283 CURVNET_RESTORE(); 284 return; 285 } 286 callout_deactivate(&tp->t_timers->tt_delack); 287 if ((inp->inp_flags & INP_DROPPED) != 0) { 288 INP_WUNLOCK(inp); 289 CURVNET_RESTORE(); 290 return; 291 } 292 tp->t_flags |= TF_ACKNOW; 293 TCPSTAT_INC(tcps_delack); 294 NET_EPOCH_ENTER(et); 295 (void) tp->t_fb->tfb_tcp_output(tp); 296 INP_WUNLOCK(inp); 297 NET_EPOCH_EXIT(et); 298 CURVNET_RESTORE(); 299 } 300 301 void 302 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp) 303 { 304 if (inp && tp != NULL) 305 INP_WUNLOCK(inp); 306 } 307 308 void 309 tcp_timer_2msl(void *xtp) 310 { 311 struct tcpcb *tp = xtp; 312 struct inpcb *inp; 313 struct epoch_tracker et; 314 CURVNET_SET(tp->t_vnet); 315 #ifdef TCPDEBUG 316 int ostate; 317 318 ostate = tp->t_state; 319 #endif 320 inp = tp->t_inpcb; 321 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 322 INP_WLOCK(inp); 323 tcp_free_sackholes(tp); 324 if (callout_pending(&tp->t_timers->tt_2msl) || 325 !callout_active(&tp->t_timers->tt_2msl)) { 326 INP_WUNLOCK(tp->t_inpcb); 327 CURVNET_RESTORE(); 328 return; 329 } 330 callout_deactivate(&tp->t_timers->tt_2msl); 331 if ((inp->inp_flags & INP_DROPPED) != 0) { 332 INP_WUNLOCK(inp); 333 CURVNET_RESTORE(); 334 return; 335 } 336 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 337 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 338 /* 339 * 2 MSL timeout in shutdown went off. If we're closed but 340 * still waiting for peer to close and connection has been idle 341 * too long delete connection control block. Otherwise, check 342 * again in a bit. 343 * 344 * If in TIME_WAIT state just ignore as this timeout is handled in 345 * tcp_tw_2msl_scan(). 346 * 347 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, 348 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. 349 * Ignore fact that there were recent incoming segments. 350 */ 351 if ((inp->inp_flags & INP_TIMEWAIT) != 0) { 352 INP_WUNLOCK(inp); 353 CURVNET_RESTORE(); 354 return; 355 } 356 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 && 357 tp->t_inpcb && tp->t_inpcb->inp_socket && 358 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) { 359 TCPSTAT_INC(tcps_finwait2_drops); 360 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 361 tcp_inpinfo_lock_del(inp, tp); 362 goto out; 363 } 364 NET_EPOCH_ENTER(et); 365 tp = tcp_close(tp); 366 NET_EPOCH_EXIT(et); 367 tcp_inpinfo_lock_del(inp, tp); 368 goto out; 369 } else { 370 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) { 371 callout_reset(&tp->t_timers->tt_2msl, 372 TP_KEEPINTVL(tp), tcp_timer_2msl, tp); 373 } else { 374 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 375 tcp_inpinfo_lock_del(inp, tp); 376 goto out; 377 } 378 NET_EPOCH_ENTER(et); 379 tp = tcp_close(tp); 380 NET_EPOCH_EXIT(et); 381 tcp_inpinfo_lock_del(inp, tp); 382 goto out; 383 } 384 } 385 386 #ifdef TCPDEBUG 387 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 388 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 389 PRU_SLOWTIMO); 390 #endif 391 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO); 392 393 if (tp != NULL) 394 INP_WUNLOCK(inp); 395 out: 396 CURVNET_RESTORE(); 397 } 398 399 void 400 tcp_timer_keep(void *xtp) 401 { 402 struct tcpcb *tp = xtp; 403 struct tcptemp *t_template; 404 struct inpcb *inp; 405 struct epoch_tracker et; 406 CURVNET_SET(tp->t_vnet); 407 #ifdef TCPDEBUG 408 int ostate; 409 410 ostate = tp->t_state; 411 #endif 412 inp = tp->t_inpcb; 413 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 414 INP_WLOCK(inp); 415 if (callout_pending(&tp->t_timers->tt_keep) || 416 !callout_active(&tp->t_timers->tt_keep)) { 417 INP_WUNLOCK(inp); 418 CURVNET_RESTORE(); 419 return; 420 } 421 callout_deactivate(&tp->t_timers->tt_keep); 422 if ((inp->inp_flags & INP_DROPPED) != 0) { 423 INP_WUNLOCK(inp); 424 CURVNET_RESTORE(); 425 return; 426 } 427 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 428 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 429 430 /* 431 * Because we don't regularly reset the keepalive callout in 432 * the ESTABLISHED state, it may be that we don't actually need 433 * to send a keepalive yet. If that occurs, schedule another 434 * call for the next time the keepalive timer might expire. 435 */ 436 if (TCPS_HAVEESTABLISHED(tp->t_state)) { 437 u_int idletime; 438 439 idletime = ticks - tp->t_rcvtime; 440 if (idletime < TP_KEEPIDLE(tp)) { 441 callout_reset(&tp->t_timers->tt_keep, 442 TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp); 443 INP_WUNLOCK(inp); 444 CURVNET_RESTORE(); 445 return; 446 } 447 } 448 449 /* 450 * Keep-alive timer went off; send something 451 * or drop connection if idle for too long. 452 */ 453 TCPSTAT_INC(tcps_keeptimeo); 454 if (tp->t_state < TCPS_ESTABLISHED) 455 goto dropit; 456 if ((V_tcp_always_keepalive || 457 inp->inp_socket->so_options & SO_KEEPALIVE) && 458 tp->t_state <= TCPS_CLOSING) { 459 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) 460 goto dropit; 461 /* 462 * Send a packet designed to force a response 463 * if the peer is up and reachable: 464 * either an ACK if the connection is still alive, 465 * or an RST if the peer has closed the connection 466 * due to timeout or reboot. 467 * Using sequence number tp->snd_una-1 468 * causes the transmitted zero-length segment 469 * to lie outside the receive window; 470 * by the protocol spec, this requires the 471 * correspondent TCP to respond. 472 */ 473 TCPSTAT_INC(tcps_keepprobe); 474 t_template = tcpip_maketemplate(inp); 475 if (t_template) { 476 NET_EPOCH_ENTER(et); 477 tcp_respond(tp, t_template->tt_ipgen, 478 &t_template->tt_t, (struct mbuf *)NULL, 479 tp->rcv_nxt, tp->snd_una - 1, 0); 480 NET_EPOCH_EXIT(et); 481 free(t_template, M_TEMP); 482 } 483 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), 484 tcp_timer_keep, tp); 485 } else 486 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), 487 tcp_timer_keep, tp); 488 489 #ifdef TCPDEBUG 490 if (inp->inp_socket->so_options & SO_DEBUG) 491 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 492 PRU_SLOWTIMO); 493 #endif 494 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO); 495 INP_WUNLOCK(inp); 496 CURVNET_RESTORE(); 497 return; 498 499 dropit: 500 TCPSTAT_INC(tcps_keepdrops); 501 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 502 tcp_inpinfo_lock_del(inp, tp); 503 goto out; 504 } 505 NET_EPOCH_ENTER(et); 506 tp = tcp_drop(tp, ETIMEDOUT); 507 508 #ifdef TCPDEBUG 509 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 510 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 511 PRU_SLOWTIMO); 512 #endif 513 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO); 514 NET_EPOCH_EXIT(et); 515 tcp_inpinfo_lock_del(inp, tp); 516 out: 517 CURVNET_RESTORE(); 518 } 519 520 void 521 tcp_timer_persist(void *xtp) 522 { 523 struct tcpcb *tp = xtp; 524 struct inpcb *inp; 525 struct epoch_tracker et; 526 CURVNET_SET(tp->t_vnet); 527 #ifdef TCPDEBUG 528 int ostate; 529 530 ostate = tp->t_state; 531 #endif 532 inp = tp->t_inpcb; 533 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 534 INP_WLOCK(inp); 535 if (callout_pending(&tp->t_timers->tt_persist) || 536 !callout_active(&tp->t_timers->tt_persist)) { 537 INP_WUNLOCK(inp); 538 CURVNET_RESTORE(); 539 return; 540 } 541 callout_deactivate(&tp->t_timers->tt_persist); 542 if ((inp->inp_flags & INP_DROPPED) != 0) { 543 INP_WUNLOCK(inp); 544 CURVNET_RESTORE(); 545 return; 546 } 547 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 548 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 549 /* 550 * Persistence timer into zero window. 551 * Force a byte to be output, if possible. 552 */ 553 TCPSTAT_INC(tcps_persisttimeo); 554 /* 555 * Hack: if the peer is dead/unreachable, we do not 556 * time out if the window is closed. After a full 557 * backoff, drop the connection if the idle time 558 * (no responses to probes) reaches the maximum 559 * backoff that we would use if retransmitting. 560 */ 561 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 562 (ticks - tp->t_rcvtime >= tcp_maxpersistidle || 563 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 564 TCPSTAT_INC(tcps_persistdrop); 565 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 566 tcp_inpinfo_lock_del(inp, tp); 567 goto out; 568 } 569 NET_EPOCH_ENTER(et); 570 tp = tcp_drop(tp, ETIMEDOUT); 571 NET_EPOCH_EXIT(et); 572 tcp_inpinfo_lock_del(inp, tp); 573 goto out; 574 } 575 /* 576 * If the user has closed the socket then drop a persisting 577 * connection after a much reduced timeout. 578 */ 579 if (tp->t_state > TCPS_CLOSE_WAIT && 580 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { 581 TCPSTAT_INC(tcps_persistdrop); 582 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 583 tcp_inpinfo_lock_del(inp, tp); 584 goto out; 585 } 586 NET_EPOCH_ENTER(et); 587 tp = tcp_drop(tp, ETIMEDOUT); 588 NET_EPOCH_EXIT(et); 589 tcp_inpinfo_lock_del(inp, tp); 590 goto out; 591 } 592 tcp_setpersist(tp); 593 tp->t_flags |= TF_FORCEDATA; 594 NET_EPOCH_ENTER(et); 595 (void) tp->t_fb->tfb_tcp_output(tp); 596 NET_EPOCH_EXIT(et); 597 tp->t_flags &= ~TF_FORCEDATA; 598 599 #ifdef TCPDEBUG 600 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 601 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 602 #endif 603 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO); 604 INP_WUNLOCK(inp); 605 out: 606 CURVNET_RESTORE(); 607 } 608 609 void 610 tcp_timer_rexmt(void * xtp) 611 { 612 struct tcpcb *tp = xtp; 613 CURVNET_SET(tp->t_vnet); 614 int rexmt; 615 struct inpcb *inp; 616 struct epoch_tracker et; 617 bool isipv6; 618 #ifdef TCPDEBUG 619 int ostate; 620 621 ostate = tp->t_state; 622 #endif 623 inp = tp->t_inpcb; 624 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 625 INP_WLOCK(inp); 626 if (callout_pending(&tp->t_timers->tt_rexmt) || 627 !callout_active(&tp->t_timers->tt_rexmt)) { 628 INP_WUNLOCK(inp); 629 CURVNET_RESTORE(); 630 return; 631 } 632 callout_deactivate(&tp->t_timers->tt_rexmt); 633 if ((inp->inp_flags & INP_DROPPED) != 0) { 634 INP_WUNLOCK(inp); 635 CURVNET_RESTORE(); 636 return; 637 } 638 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 639 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 640 tcp_free_sackholes(tp); 641 TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false); 642 if (tp->t_fb->tfb_tcp_rexmit_tmr) { 643 /* The stack has a timer action too. */ 644 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp); 645 } 646 /* 647 * Retransmission timer went off. Message has not 648 * been acked within retransmit interval. Back off 649 * to a longer retransmit interval and retransmit one segment. 650 */ 651 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 652 tp->t_rxtshift = TCP_MAXRXTSHIFT; 653 TCPSTAT_INC(tcps_timeoutdrop); 654 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) { 655 tcp_inpinfo_lock_del(inp, tp); 656 goto out; 657 } 658 NET_EPOCH_ENTER(et); 659 tp = tcp_drop(tp, ETIMEDOUT); 660 NET_EPOCH_EXIT(et); 661 tcp_inpinfo_lock_del(inp, tp); 662 goto out; 663 } 664 if (tp->t_state == TCPS_SYN_SENT) { 665 /* 666 * If the SYN was retransmitted, indicate CWND to be 667 * limited to 1 segment in cc_conn_init(). 668 */ 669 tp->snd_cwnd = 1; 670 } else if (tp->t_rxtshift == 1) { 671 /* 672 * first retransmit; record ssthresh and cwnd so they can 673 * be recovered if this turns out to be a "bad" retransmit. 674 * A retransmit is considered "bad" if an ACK for this 675 * segment is received within RTT/2 interval; the assumption 676 * here is that the ACK was already in flight. See 677 * "On Estimating End-to-End Network Path Properties" by 678 * Allman and Paxson for more details. 679 */ 680 tp->snd_cwnd_prev = tp->snd_cwnd; 681 tp->snd_ssthresh_prev = tp->snd_ssthresh; 682 tp->snd_recover_prev = tp->snd_recover; 683 if (IN_FASTRECOVERY(tp->t_flags)) 684 tp->t_flags |= TF_WASFRECOVERY; 685 else 686 tp->t_flags &= ~TF_WASFRECOVERY; 687 if (IN_CONGRECOVERY(tp->t_flags)) 688 tp->t_flags |= TF_WASCRECOVERY; 689 else 690 tp->t_flags &= ~TF_WASCRECOVERY; 691 if ((tp->t_flags & TF_RCVD_TSTMP) == 0) 692 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 693 /* In the event that we've negotiated timestamps 694 * badrxtwin will be set to the value that we set 695 * the retransmitted packet's to_tsval to by tcp_output 696 */ 697 tp->t_flags |= TF_PREVVALID; 698 } else 699 tp->t_flags &= ~TF_PREVVALID; 700 TCPSTAT_INC(tcps_rexmttimeo); 701 if ((tp->t_state == TCPS_SYN_SENT) || 702 (tp->t_state == TCPS_SYN_RECEIVED)) 703 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift]; 704 else 705 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 706 TCPT_RANGESET(tp->t_rxtcur, rexmt, 707 tp->t_rttmin, TCPTV_REXMTMAX); 708 709 /* 710 * We enter the path for PLMTUD if connection is established or, if 711 * connection is FIN_WAIT_1 status, reason for the last is that if 712 * amount of data we send is very small, we could send it in couple of 713 * packets and process straight to FIN. In that case we won't catch 714 * ESTABLISHED state. 715 */ 716 #ifdef INET6 717 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false; 718 #else 719 isipv6 = false; 720 #endif 721 if (((V_tcp_pmtud_blackhole_detect == 1) || 722 (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) || 723 (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) && 724 ((tp->t_state == TCPS_ESTABLISHED) || 725 (tp->t_state == TCPS_FIN_WAIT_1))) { 726 /* 727 * Idea here is that at each stage of mtu probe (usually, 1448 728 * -> 1188 -> 524) should be given 2 chances to recover before 729 * further clamping down. 'tp->t_rxtshift % 2 == 0' should 730 * take care of that. 731 */ 732 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == 733 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && 734 (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 && 735 tp->t_rxtshift % 2 == 0)) { 736 /* 737 * Enter Path MTU Black-hole Detection mechanism: 738 * - Disable Path MTU Discovery (IP "DF" bit). 739 * - Reduce MTU to lower value than what we 740 * negotiated with peer. 741 */ 742 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) { 743 /* Record that we may have found a black hole. */ 744 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; 745 /* Keep track of previous MSS. */ 746 tp->t_pmtud_saved_maxseg = tp->t_maxseg; 747 } 748 749 /* 750 * Reduce the MSS to blackhole value or to the default 751 * in an attempt to retransmit. 752 */ 753 #ifdef INET6 754 if (isipv6 && 755 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) { 756 /* Use the sysctl tuneable blackhole MSS. */ 757 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss; 758 TCPSTAT_INC(tcps_pmtud_blackhole_activated); 759 } else if (isipv6) { 760 /* Use the default MSS. */ 761 tp->t_maxseg = V_tcp_v6mssdflt; 762 /* 763 * Disable Path MTU Discovery when we switch to 764 * minmss. 765 */ 766 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 767 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss); 768 } 769 #endif 770 #if defined(INET6) && defined(INET) 771 else 772 #endif 773 #ifdef INET 774 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) { 775 /* Use the sysctl tuneable blackhole MSS. */ 776 tp->t_maxseg = V_tcp_pmtud_blackhole_mss; 777 TCPSTAT_INC(tcps_pmtud_blackhole_activated); 778 } else { 779 /* Use the default MSS. */ 780 tp->t_maxseg = V_tcp_mssdflt; 781 /* 782 * Disable Path MTU Discovery when we switch to 783 * minmss. 784 */ 785 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 786 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss); 787 } 788 #endif 789 /* 790 * Reset the slow-start flight size 791 * as it may depend on the new MSS. 792 */ 793 if (CC_ALGO(tp)->conn_init != NULL) 794 CC_ALGO(tp)->conn_init(tp->ccv); 795 } else { 796 /* 797 * If further retransmissions are still unsuccessful 798 * with a lowered MTU, maybe this isn't a blackhole and 799 * we restore the previous MSS and blackhole detection 800 * flags. 801 * The limit '6' is determined by giving each probe 802 * stage (1448, 1188, 524) 2 chances to recover. 803 */ 804 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && 805 (tp->t_rxtshift >= 6)) { 806 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 807 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; 808 tp->t_maxseg = tp->t_pmtud_saved_maxseg; 809 TCPSTAT_INC(tcps_pmtud_blackhole_failed); 810 /* 811 * Reset the slow-start flight size as it 812 * may depend on the new MSS. 813 */ 814 if (CC_ALGO(tp)->conn_init != NULL) 815 CC_ALGO(tp)->conn_init(tp->ccv); 816 } 817 } 818 } 819 820 /* 821 * Disable RFC1323 and SACK if we haven't got any response to 822 * our third SYN to work-around some broken terminal servers 823 * (most of which have hopefully been retired) that have bad VJ 824 * header compression code which trashes TCP segments containing 825 * unknown-to-them TCP options. 826 */ 827 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && 828 (tp->t_rxtshift == 3)) 829 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); 830 /* 831 * If we backed off this far, notify the L3 protocol that we're having 832 * connection problems. 833 */ 834 if (tp->t_rxtshift > TCP_RTT_INVALIDATE) { 835 #ifdef INET6 836 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 837 in6_losing(tp->t_inpcb); 838 else 839 #endif 840 in_losing(tp->t_inpcb); 841 } 842 tp->snd_nxt = tp->snd_una; 843 tp->snd_recover = tp->snd_max; 844 /* 845 * Force a segment to be sent. 846 */ 847 tp->t_flags |= TF_ACKNOW; 848 /* 849 * If timing a segment in this window, stop the timer. 850 */ 851 tp->t_rtttime = 0; 852 853 cc_cong_signal(tp, NULL, CC_RTO); 854 NET_EPOCH_ENTER(et); 855 (void) tp->t_fb->tfb_tcp_output(tp); 856 NET_EPOCH_EXIT(et); 857 #ifdef TCPDEBUG 858 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 859 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 860 PRU_SLOWTIMO); 861 #endif 862 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO); 863 INP_WUNLOCK(inp); 864 out: 865 CURVNET_RESTORE(); 866 } 867 868 void 869 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) 870 { 871 struct callout *t_callout; 872 callout_func_t *f_callout; 873 struct inpcb *inp = tp->t_inpcb; 874 int cpu = inp_to_cpuid(inp); 875 876 #ifdef TCP_OFFLOAD 877 if (tp->t_flags & TF_TOE) 878 return; 879 #endif 880 881 if (tp->t_timers->tt_flags & TT_STOPPED) 882 return; 883 884 switch (timer_type) { 885 case TT_DELACK: 886 t_callout = &tp->t_timers->tt_delack; 887 f_callout = tcp_timer_delack; 888 break; 889 case TT_REXMT: 890 t_callout = &tp->t_timers->tt_rexmt; 891 f_callout = tcp_timer_rexmt; 892 break; 893 case TT_PERSIST: 894 t_callout = &tp->t_timers->tt_persist; 895 f_callout = tcp_timer_persist; 896 break; 897 case TT_KEEP: 898 t_callout = &tp->t_timers->tt_keep; 899 f_callout = tcp_timer_keep; 900 break; 901 case TT_2MSL: 902 t_callout = &tp->t_timers->tt_2msl; 903 f_callout = tcp_timer_2msl; 904 break; 905 default: 906 if (tp->t_fb->tfb_tcp_timer_activate) { 907 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta); 908 return; 909 } 910 panic("tp %p bad timer_type %#x", tp, timer_type); 911 } 912 if (delta == 0) { 913 callout_stop(t_callout); 914 } else { 915 callout_reset_on(t_callout, delta, f_callout, tp, cpu); 916 } 917 } 918 919 int 920 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) 921 { 922 struct callout *t_callout; 923 924 switch (timer_type) { 925 case TT_DELACK: 926 t_callout = &tp->t_timers->tt_delack; 927 break; 928 case TT_REXMT: 929 t_callout = &tp->t_timers->tt_rexmt; 930 break; 931 case TT_PERSIST: 932 t_callout = &tp->t_timers->tt_persist; 933 break; 934 case TT_KEEP: 935 t_callout = &tp->t_timers->tt_keep; 936 break; 937 case TT_2MSL: 938 t_callout = &tp->t_timers->tt_2msl; 939 break; 940 default: 941 if (tp->t_fb->tfb_tcp_timer_active) { 942 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type)); 943 } 944 panic("tp %p bad timer_type %#x", tp, timer_type); 945 } 946 return callout_active(t_callout); 947 } 948 949 /* 950 * Stop the timer from running, and apply a flag 951 * against the timer_flags that will force the 952 * timer never to run. The flag is needed to assure 953 * a race does not leave it running and cause 954 * the timer to possibly restart itself (keep and persist 955 * especially do this). 956 */ 957 int 958 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type) 959 { 960 struct callout *t_callout; 961 uint32_t t_flags; 962 963 switch (timer_type) { 964 case TT_DELACK: 965 t_flags = TT_DELACK_SUS; 966 t_callout = &tp->t_timers->tt_delack; 967 break; 968 case TT_REXMT: 969 t_flags = TT_REXMT_SUS; 970 t_callout = &tp->t_timers->tt_rexmt; 971 break; 972 case TT_PERSIST: 973 t_flags = TT_PERSIST_SUS; 974 t_callout = &tp->t_timers->tt_persist; 975 break; 976 case TT_KEEP: 977 t_flags = TT_KEEP_SUS; 978 t_callout = &tp->t_timers->tt_keep; 979 break; 980 case TT_2MSL: 981 t_flags = TT_2MSL_SUS; 982 t_callout = &tp->t_timers->tt_2msl; 983 break; 984 default: 985 panic("tp:%p bad timer_type 0x%x", tp, timer_type); 986 } 987 tp->t_timers->tt_flags |= t_flags; 988 return (callout_stop(t_callout)); 989 } 990 991 void 992 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type) 993 { 994 switch (timer_type) { 995 case TT_DELACK: 996 if (tp->t_timers->tt_flags & TT_DELACK_SUS) { 997 tp->t_timers->tt_flags &= ~TT_DELACK_SUS; 998 if (tp->t_flags & TF_DELACK) { 999 /* Delayed ack timer should be up activate a timer */ 1000 tp->t_flags &= ~TF_DELACK; 1001 tcp_timer_activate(tp, TT_DELACK, 1002 tcp_delacktime); 1003 } 1004 } 1005 break; 1006 case TT_REXMT: 1007 if (tp->t_timers->tt_flags & TT_REXMT_SUS) { 1008 tp->t_timers->tt_flags &= ~TT_REXMT_SUS; 1009 if (SEQ_GT(tp->snd_max, tp->snd_una) && 1010 (tcp_timer_active((tp), TT_PERSIST) == 0) && 1011 tp->snd_wnd) { 1012 /* We have outstanding data activate a timer */ 1013 tcp_timer_activate(tp, TT_REXMT, 1014 tp->t_rxtcur); 1015 } 1016 } 1017 break; 1018 case TT_PERSIST: 1019 if (tp->t_timers->tt_flags & TT_PERSIST_SUS) { 1020 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS; 1021 if (tp->snd_wnd == 0) { 1022 /* Activate the persists timer */ 1023 tp->t_rxtshift = 0; 1024 tcp_setpersist(tp); 1025 } 1026 } 1027 break; 1028 case TT_KEEP: 1029 if (tp->t_timers->tt_flags & TT_KEEP_SUS) { 1030 tp->t_timers->tt_flags &= ~TT_KEEP_SUS; 1031 tcp_timer_activate(tp, TT_KEEP, 1032 TCPS_HAVEESTABLISHED(tp->t_state) ? 1033 TP_KEEPIDLE(tp) : TP_KEEPINIT(tp)); 1034 } 1035 break; 1036 case TT_2MSL: 1037 if (tp->t_timers->tt_flags &= TT_2MSL_SUS) { 1038 tp->t_timers->tt_flags &= ~TT_2MSL_SUS; 1039 if ((tp->t_state == TCPS_FIN_WAIT_2) && 1040 ((tp->t_inpcb->inp_socket == NULL) || 1041 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) { 1042 /* Star the 2MSL timer */ 1043 tcp_timer_activate(tp, TT_2MSL, 1044 (tcp_fast_finwait2_recycle) ? 1045 tcp_finwait2_timeout : TP_MAXIDLE(tp)); 1046 } 1047 } 1048 break; 1049 default: 1050 panic("tp:%p bad timer_type 0x%x", tp, timer_type); 1051 } 1052 } 1053 1054 void 1055 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) 1056 { 1057 struct callout *t_callout; 1058 1059 tp->t_timers->tt_flags |= TT_STOPPED; 1060 switch (timer_type) { 1061 case TT_DELACK: 1062 t_callout = &tp->t_timers->tt_delack; 1063 break; 1064 case TT_REXMT: 1065 t_callout = &tp->t_timers->tt_rexmt; 1066 break; 1067 case TT_PERSIST: 1068 t_callout = &tp->t_timers->tt_persist; 1069 break; 1070 case TT_KEEP: 1071 t_callout = &tp->t_timers->tt_keep; 1072 break; 1073 case TT_2MSL: 1074 t_callout = &tp->t_timers->tt_2msl; 1075 break; 1076 default: 1077 if (tp->t_fb->tfb_tcp_timer_stop) { 1078 /* 1079 * XXXrrs we need to look at this with the 1080 * stop case below (flags). 1081 */ 1082 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type); 1083 return; 1084 } 1085 panic("tp %p bad timer_type %#x", tp, timer_type); 1086 } 1087 1088 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) { 1089 /* 1090 * Can't stop the callout, defer tcpcb actual deletion 1091 * to the last one. We do this using the async drain 1092 * function and incrementing the count in 1093 */ 1094 tp->t_timers->tt_draincnt++; 1095 } 1096 } 1097