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