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sys/netinet/tcp_timer.c
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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 39 #include <sys/param.h> 40 #include <sys/kernel.h> 41 #include <sys/lock.h> 42 #include <sys/mbuf.h> 43 #include <sys/mutex.h> 44 #include <sys/protosw.h> 45 #include <sys/smp.h> 46 #include <sys/socket.h> 47 #include <sys/socketvar.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 51 #include <net/if.h> 52 #include <net/route.h> 53 #include <net/vnet.h> 54 55 #include <netinet/cc.h> 56 #include <netinet/in.h> 57 #include <netinet/in_pcb.h> 58 #include <netinet/in_systm.h> 59 #ifdef INET6 60 #include <netinet6/in6_pcb.h> 61 #endif 62 #include <netinet/ip_var.h> 63 #include <netinet/tcp_fsm.h> 64 #include <netinet/tcp_timer.h> 65 #include <netinet/tcp_var.h> 66 #ifdef INET6 67 #include <netinet6/tcp6_var.h> 68 #endif 69 #include <netinet/tcpip.h> 70 #ifdef TCPDEBUG 71 #include <netinet/tcp_debug.h> 72 #endif 73 74 int tcp_persmin; 75 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW, 76 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval"); 77 78 int tcp_persmax; 79 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW, 80 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval"); 81 82 int tcp_keepinit; 83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW, 84 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection"); 85 86 int tcp_keepidle; 87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW, 88 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin"); 89 90 int tcp_keepintvl; 91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW, 92 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes"); 93 94 int tcp_delacktime; 95 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW, 96 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", 97 "Time before a delayed ACK is sent"); 98 99 int tcp_msl; 100 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW, 101 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime"); 102 103 int tcp_rexmit_min; 104 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW, 105 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", 106 "Minimum Retransmission Timeout"); 107 108 int tcp_rexmit_slop; 109 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW, 110 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", 111 "Retransmission Timer Slop"); 112 113 int tcp_always_keepalive = 1; 114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, 115 &tcp_always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); 116 __strong_reference(tcp_always_keepalive, always_keepalive); 117 118 int tcp_fast_finwait2_recycle = 0; 119 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW, 120 &tcp_fast_finwait2_recycle, 0, 121 "Recycle closed FIN_WAIT_2 connections faster"); 122 123 int tcp_finwait2_timeout; 124 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW, 125 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout"); 126 127 int tcp_keepcnt = TCPTV_KEEPCNT; 128 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0, 129 "Number of keepalive probes to send"); 130 131 /* max idle probes */ 132 int tcp_maxpersistidle; 133 134 static int tcp_rexmit_drop_options = 0; 135 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW, 136 &tcp_rexmit_drop_options, 0, 137 "Drop TCP options from 3rd and later retransmitted SYN"); 138 139 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect); 140 #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect) 141 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, 142 CTLFLAG_RW, 143 &VNET_NAME(tcp_pmtud_blackhole_detect), 0, 144 "Path MTU Discovery Black Hole Detection Enabled"); 145 146 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated); 147 #define V_tcp_pmtud_blackhole_activated \ 148 VNET(tcp_pmtud_blackhole_activated) 149 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated, 150 CTLFLAG_RD, 151 &VNET_NAME(tcp_pmtud_blackhole_activated), 0, 152 "Path MTU Discovery Black Hole Detection, Activation Count"); 153 154 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss); 155 #define V_tcp_pmtud_blackhole_activated_min_mss \ 156 VNET(tcp_pmtud_blackhole_activated_min_mss) 157 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss, 158 CTLFLAG_RD, 159 &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0, 160 "Path MTU Discovery Black Hole Detection, Activation Count at min MSS"); 161 162 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed); 163 #define V_tcp_pmtud_blackhole_failed VNET(tcp_pmtud_blackhole_failed) 164 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed, 165 CTLFLAG_RD, 166 &VNET_NAME(tcp_pmtud_blackhole_failed), 0, 167 "Path MTU Discovery Black Hole Detection, Failure Count"); 168 169 #ifdef INET 170 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200; 171 #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss) 172 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, 173 CTLFLAG_RW, 174 &VNET_NAME(tcp_pmtud_blackhole_mss), 0, 175 "Path MTU Discovery Black Hole Detection lowered MSS"); 176 #endif 177 178 #ifdef INET6 179 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220; 180 #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss) 181 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss, 182 CTLFLAG_RW, 183 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0, 184 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS"); 185 #endif 186 187 static int per_cpu_timers = 0; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW, 189 &per_cpu_timers , 0, "run tcp timers on all cpus"); 190 191 #define INP_CPU(inp) (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \ 192 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0) 193 194 /* 195 * Tcp protocol timeout routine called every 500 ms. 196 * Updates timestamps used for TCP 197 * causes finite state machine actions if timers expire. 198 */ 199 void 200 tcp_slowtimo(void) 201 { 202 VNET_ITERATOR_DECL(vnet_iter); 203 204 VNET_LIST_RLOCK_NOSLEEP(); 205 VNET_FOREACH(vnet_iter) { 206 CURVNET_SET(vnet_iter); 207 (void) tcp_tw_2msl_scan(0); 208 CURVNET_RESTORE(); 209 } 210 VNET_LIST_RUNLOCK_NOSLEEP(); 211 } 212 213 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = 214 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; 215 216 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 217 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 218 219 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 220 221 /* 222 * TCP timer processing. 223 */ 224 225 void 226 tcp_timer_delack(void *xtp) 227 { 228 struct tcpcb *tp = xtp; 229 struct inpcb *inp; 230 CURVNET_SET(tp->t_vnet); 231 232 inp = tp->t_inpcb; 233 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 234 INP_WLOCK(inp); 235 if (callout_pending(&tp->t_timers->tt_delack) || 236 !callout_active(&tp->t_timers->tt_delack)) { 237 INP_WUNLOCK(inp); 238 CURVNET_RESTORE(); 239 return; 240 } 241 callout_deactivate(&tp->t_timers->tt_delack); 242 if ((inp->inp_flags & INP_DROPPED) != 0) { 243 INP_WUNLOCK(inp); 244 CURVNET_RESTORE(); 245 return; 246 } 247 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 248 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 249 KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0, 250 ("%s: tp %p delack callout should be running", __func__, tp)); 251 252 tp->t_flags |= TF_ACKNOW; 253 TCPSTAT_INC(tcps_delack); 254 (void) tcp_output(tp); 255 INP_WUNLOCK(inp); 256 CURVNET_RESTORE(); 257 } 258 259 void 260 tcp_timer_2msl(void *xtp) 261 { 262 struct tcpcb *tp = xtp; 263 struct inpcb *inp; 264 CURVNET_SET(tp->t_vnet); 265 #ifdef TCPDEBUG 266 int ostate; 267 268 ostate = tp->t_state; 269 #endif 270 INP_INFO_RLOCK(&V_tcbinfo); 271 inp = tp->t_inpcb; 272 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 273 INP_WLOCK(inp); 274 tcp_free_sackholes(tp); 275 if (callout_pending(&tp->t_timers->tt_2msl) || 276 !callout_active(&tp->t_timers->tt_2msl)) { 277 INP_WUNLOCK(tp->t_inpcb); 278 INP_INFO_RUNLOCK(&V_tcbinfo); 279 CURVNET_RESTORE(); 280 return; 281 } 282 callout_deactivate(&tp->t_timers->tt_2msl); 283 if ((inp->inp_flags & INP_DROPPED) != 0) { 284 INP_WUNLOCK(inp); 285 INP_INFO_RUNLOCK(&V_tcbinfo); 286 CURVNET_RESTORE(); 287 return; 288 } 289 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 290 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 291 KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0, 292 ("%s: tp %p 2msl callout should be running", __func__, tp)); 293 /* 294 * 2 MSL timeout in shutdown went off. If we're closed but 295 * still waiting for peer to close and connection has been idle 296 * too long delete connection control block. Otherwise, check 297 * again in a bit. 298 * 299 * If in TIME_WAIT state just ignore as this timeout is handled in 300 * tcp_tw_2msl_scan(). 301 * 302 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, 303 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. 304 * Ignore fact that there were recent incoming segments. 305 */ 306 if ((inp->inp_flags & INP_TIMEWAIT) != 0) { 307 INP_WUNLOCK(inp); 308 INP_INFO_RUNLOCK(&V_tcbinfo); 309 CURVNET_RESTORE(); 310 return; 311 } 312 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 && 313 tp->t_inpcb && tp->t_inpcb->inp_socket && 314 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) { 315 TCPSTAT_INC(tcps_finwait2_drops); 316 tp = tcp_close(tp); 317 } else { 318 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) { 319 if (!callout_reset(&tp->t_timers->tt_2msl, 320 TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) { 321 tp->t_timers->tt_flags &= ~TT_2MSL_RST; 322 } 323 } else 324 tp = tcp_close(tp); 325 } 326 327 #ifdef TCPDEBUG 328 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 329 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 330 PRU_SLOWTIMO); 331 #endif 332 if (tp != NULL) 333 INP_WUNLOCK(inp); 334 INP_INFO_RUNLOCK(&V_tcbinfo); 335 CURVNET_RESTORE(); 336 } 337 338 void 339 tcp_timer_keep(void *xtp) 340 { 341 struct tcpcb *tp = xtp; 342 struct tcptemp *t_template; 343 struct inpcb *inp; 344 CURVNET_SET(tp->t_vnet); 345 #ifdef TCPDEBUG 346 int ostate; 347 348 ostate = tp->t_state; 349 #endif 350 INP_INFO_RLOCK(&V_tcbinfo); 351 inp = tp->t_inpcb; 352 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 353 INP_WLOCK(inp); 354 if (callout_pending(&tp->t_timers->tt_keep) || 355 !callout_active(&tp->t_timers->tt_keep)) { 356 INP_WUNLOCK(inp); 357 INP_INFO_RUNLOCK(&V_tcbinfo); 358 CURVNET_RESTORE(); 359 return; 360 } 361 callout_deactivate(&tp->t_timers->tt_keep); 362 if ((inp->inp_flags & INP_DROPPED) != 0) { 363 INP_WUNLOCK(inp); 364 INP_INFO_RUNLOCK(&V_tcbinfo); 365 CURVNET_RESTORE(); 366 return; 367 } 368 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 369 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 370 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0, 371 ("%s: tp %p keep callout should be running", __func__, tp)); 372 /* 373 * Keep-alive timer went off; send something 374 * or drop connection if idle for too long. 375 */ 376 TCPSTAT_INC(tcps_keeptimeo); 377 if (tp->t_state < TCPS_ESTABLISHED) 378 goto dropit; 379 if ((tcp_always_keepalive || 380 inp->inp_socket->so_options & SO_KEEPALIVE) && 381 tp->t_state <= TCPS_CLOSING) { 382 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) 383 goto dropit; 384 /* 385 * Send a packet designed to force a response 386 * if the peer is up and reachable: 387 * either an ACK if the connection is still alive, 388 * or an RST if the peer has closed the connection 389 * due to timeout or reboot. 390 * Using sequence number tp->snd_una-1 391 * causes the transmitted zero-length segment 392 * to lie outside the receive window; 393 * by the protocol spec, this requires the 394 * correspondent TCP to respond. 395 */ 396 TCPSTAT_INC(tcps_keepprobe); 397 t_template = tcpip_maketemplate(inp); 398 if (t_template) { 399 tcp_respond(tp, t_template->tt_ipgen, 400 &t_template->tt_t, (struct mbuf *)NULL, 401 tp->rcv_nxt, tp->snd_una - 1, 0); 402 free(t_template, M_TEMP); 403 } 404 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), 405 tcp_timer_keep, tp)) { 406 tp->t_timers->tt_flags &= ~TT_KEEP_RST; 407 } 408 } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), 409 tcp_timer_keep, tp)) { 410 tp->t_timers->tt_flags &= ~TT_KEEP_RST; 411 } 412 413 #ifdef TCPDEBUG 414 if (inp->inp_socket->so_options & SO_DEBUG) 415 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 416 PRU_SLOWTIMO); 417 #endif 418 INP_WUNLOCK(inp); 419 INP_INFO_RUNLOCK(&V_tcbinfo); 420 CURVNET_RESTORE(); 421 return; 422 423 dropit: 424 TCPSTAT_INC(tcps_keepdrops); 425 tp = tcp_drop(tp, ETIMEDOUT); 426 427 #ifdef TCPDEBUG 428 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 429 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 430 PRU_SLOWTIMO); 431 #endif 432 if (tp != NULL) 433 INP_WUNLOCK(tp->t_inpcb); 434 INP_INFO_RUNLOCK(&V_tcbinfo); 435 CURVNET_RESTORE(); 436 } 437 438 void 439 tcp_timer_persist(void *xtp) 440 { 441 struct tcpcb *tp = xtp; 442 struct inpcb *inp; 443 CURVNET_SET(tp->t_vnet); 444 #ifdef TCPDEBUG 445 int ostate; 446 447 ostate = tp->t_state; 448 #endif 449 INP_INFO_RLOCK(&V_tcbinfo); 450 inp = tp->t_inpcb; 451 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 452 INP_WLOCK(inp); 453 if (callout_pending(&tp->t_timers->tt_persist) || 454 !callout_active(&tp->t_timers->tt_persist)) { 455 INP_WUNLOCK(inp); 456 INP_INFO_RUNLOCK(&V_tcbinfo); 457 CURVNET_RESTORE(); 458 return; 459 } 460 callout_deactivate(&tp->t_timers->tt_persist); 461 if ((inp->inp_flags & INP_DROPPED) != 0) { 462 INP_WUNLOCK(inp); 463 INP_INFO_RUNLOCK(&V_tcbinfo); 464 CURVNET_RESTORE(); 465 return; 466 } 467 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 468 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 469 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0, 470 ("%s: tp %p persist callout should be running", __func__, tp)); 471 /* 472 * Persistance timer into zero window. 473 * Force a byte to be output, if possible. 474 */ 475 TCPSTAT_INC(tcps_persisttimeo); 476 /* 477 * Hack: if the peer is dead/unreachable, we do not 478 * time out if the window is closed. After a full 479 * backoff, drop the connection if the idle time 480 * (no responses to probes) reaches the maximum 481 * backoff that we would use if retransmitting. 482 */ 483 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 484 (ticks - tp->t_rcvtime >= tcp_maxpersistidle || 485 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 486 TCPSTAT_INC(tcps_persistdrop); 487 tp = tcp_drop(tp, ETIMEDOUT); 488 goto out; 489 } 490 /* 491 * If the user has closed the socket then drop a persisting 492 * connection after a much reduced timeout. 493 */ 494 if (tp->t_state > TCPS_CLOSE_WAIT && 495 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { 496 TCPSTAT_INC(tcps_persistdrop); 497 tp = tcp_drop(tp, ETIMEDOUT); 498 goto out; 499 } 500 tcp_setpersist(tp); 501 tp->t_flags |= TF_FORCEDATA; 502 (void) tcp_output(tp); 503 tp->t_flags &= ~TF_FORCEDATA; 504 505 out: 506 #ifdef TCPDEBUG 507 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 508 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 509 #endif 510 if (tp != NULL) 511 INP_WUNLOCK(inp); 512 INP_INFO_RUNLOCK(&V_tcbinfo); 513 CURVNET_RESTORE(); 514 } 515 516 void 517 tcp_timer_rexmt(void * xtp) 518 { 519 struct tcpcb *tp = xtp; 520 CURVNET_SET(tp->t_vnet); 521 int rexmt; 522 int headlocked; 523 struct inpcb *inp; 524 #ifdef TCPDEBUG 525 int ostate; 526 527 ostate = tp->t_state; 528 #endif 529 530 INP_INFO_RLOCK(&V_tcbinfo); 531 inp = tp->t_inpcb; 532 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 533 INP_WLOCK(inp); 534 if (callout_pending(&tp->t_timers->tt_rexmt) || 535 !callout_active(&tp->t_timers->tt_rexmt)) { 536 INP_WUNLOCK(inp); 537 INP_INFO_RUNLOCK(&V_tcbinfo); 538 CURVNET_RESTORE(); 539 return; 540 } 541 callout_deactivate(&tp->t_timers->tt_rexmt); 542 if ((inp->inp_flags & INP_DROPPED) != 0) { 543 INP_WUNLOCK(inp); 544 INP_INFO_RUNLOCK(&V_tcbinfo); 545 CURVNET_RESTORE(); 546 return; 547 } 548 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 549 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 550 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0, 551 ("%s: tp %p rexmt callout should be running", __func__, tp)); 552 tcp_free_sackholes(tp); 553 /* 554 * Retransmission timer went off. Message has not 555 * been acked within retransmit interval. Back off 556 * to a longer retransmit interval and retransmit one segment. 557 */ 558 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 559 tp->t_rxtshift = TCP_MAXRXTSHIFT; 560 TCPSTAT_INC(tcps_timeoutdrop); 561 562 tp = tcp_drop(tp, tp->t_softerror ? 563 tp->t_softerror : ETIMEDOUT); 564 headlocked = 1; 565 goto out; 566 } 567 INP_INFO_RUNLOCK(&V_tcbinfo); 568 headlocked = 0; 569 if (tp->t_state == TCPS_SYN_SENT) { 570 /* 571 * If the SYN was retransmitted, indicate CWND to be 572 * limited to 1 segment in cc_conn_init(). 573 */ 574 tp->snd_cwnd = 1; 575 } else if (tp->t_rxtshift == 1) { 576 /* 577 * first retransmit; record ssthresh and cwnd so they can 578 * be recovered if this turns out to be a "bad" retransmit. 579 * A retransmit is considered "bad" if an ACK for this 580 * segment is received within RTT/2 interval; the assumption 581 * here is that the ACK was already in flight. See 582 * "On Estimating End-to-End Network Path Properties" by 583 * Allman and Paxson for more details. 584 */ 585 tp->snd_cwnd_prev = tp->snd_cwnd; 586 tp->snd_ssthresh_prev = tp->snd_ssthresh; 587 tp->snd_recover_prev = tp->snd_recover; 588 if (IN_FASTRECOVERY(tp->t_flags)) 589 tp->t_flags |= TF_WASFRECOVERY; 590 else 591 tp->t_flags &= ~TF_WASFRECOVERY; 592 if (IN_CONGRECOVERY(tp->t_flags)) 593 tp->t_flags |= TF_WASCRECOVERY; 594 else 595 tp->t_flags &= ~TF_WASCRECOVERY; 596 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 597 tp->t_flags |= TF_PREVVALID; 598 } else 599 tp->t_flags &= ~TF_PREVVALID; 600 TCPSTAT_INC(tcps_rexmttimeo); 601 if ((tp->t_state == TCPS_SYN_SENT) || 602 (tp->t_state == TCPS_SYN_RECEIVED)) 603 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; 604 else 605 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 606 TCPT_RANGESET(tp->t_rxtcur, rexmt, 607 tp->t_rttmin, TCPTV_REXMTMAX); 608 609 /* 610 * We enter the path for PLMTUD if connection is established or, if 611 * connection is FIN_WAIT_1 status, reason for the last is that if 612 * amount of data we send is very small, we could send it in couple of 613 * packets and process straight to FIN. In that case we won't catch 614 * ESTABLISHED state. 615 */ 616 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED)) 617 || (tp->t_state == TCPS_FIN_WAIT_1))) { 618 int optlen; 619 #ifdef INET6 620 int isipv6; 621 #endif 622 623 /* 624 * Idea here is that at each stage of mtu probe (usually, 1448 625 * -> 1188 -> 524) should be given 2 chances to recover before 626 * further clamping down. 'tp->t_rxtshift % 2 == 0' should 627 * take care of that. 628 */ 629 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == 630 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && 631 (tp->t_rxtshift >= 2 && tp->t_rxtshift % 2 == 0)) { 632 /* 633 * Enter Path MTU Black-hole Detection mechanism: 634 * - Disable Path MTU Discovery (IP "DF" bit). 635 * - Reduce MTU to lower value than what we 636 * negotiated with peer. 637 */ 638 /* Record that we may have found a black hole. */ 639 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; 640 641 /* Keep track of previous MSS. */ 642 optlen = tp->t_maxopd - tp->t_maxseg; 643 tp->t_pmtud_saved_maxopd = tp->t_maxopd; 644 645 /* 646 * Reduce the MSS to blackhole value or to the default 647 * in an attempt to retransmit. 648 */ 649 #ifdef INET6 650 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0; 651 if (isipv6 && 652 tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) { 653 /* Use the sysctl tuneable blackhole MSS. */ 654 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss; 655 V_tcp_pmtud_blackhole_activated++; 656 } else if (isipv6) { 657 /* Use the default MSS. */ 658 tp->t_maxopd = V_tcp_v6mssdflt; 659 /* 660 * Disable Path MTU Discovery when we switch to 661 * minmss. 662 */ 663 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 664 V_tcp_pmtud_blackhole_activated_min_mss++; 665 } 666 #endif 667 #if defined(INET6) && defined(INET) 668 else 669 #endif 670 #ifdef INET 671 if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) { 672 /* Use the sysctl tuneable blackhole MSS. */ 673 tp->t_maxopd = V_tcp_pmtud_blackhole_mss; 674 V_tcp_pmtud_blackhole_activated++; 675 } else { 676 /* Use the default MSS. */ 677 tp->t_maxopd = V_tcp_mssdflt; 678 /* 679 * Disable Path MTU Discovery when we switch to 680 * minmss. 681 */ 682 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 683 V_tcp_pmtud_blackhole_activated_min_mss++; 684 } 685 #endif 686 tp->t_maxseg = tp->t_maxopd - optlen; 687 /* 688 * Reset the slow-start flight size 689 * as it may depend on the new MSS. 690 */ 691 if (CC_ALGO(tp)->conn_init != NULL) 692 CC_ALGO(tp)->conn_init(tp->ccv); 693 } else { 694 /* 695 * If further retransmissions are still unsuccessful 696 * with a lowered MTU, maybe this isn't a blackhole and 697 * we restore the previous MSS and blackhole detection 698 * flags. 699 * The limit '6' is determined by giving each probe 700 * stage (1448, 1188, 524) 2 chances to recover. 701 */ 702 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && 703 (tp->t_rxtshift > 6)) { 704 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 705 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; 706 optlen = tp->t_maxopd - tp->t_maxseg; 707 tp->t_maxopd = tp->t_pmtud_saved_maxopd; 708 tp->t_maxseg = tp->t_maxopd - optlen; 709 V_tcp_pmtud_blackhole_failed++; 710 /* 711 * Reset the slow-start flight size as it 712 * may depend on the new MSS. 713 */ 714 if (CC_ALGO(tp)->conn_init != NULL) 715 CC_ALGO(tp)->conn_init(tp->ccv); 716 } 717 } 718 } 719 720 /* 721 * Disable RFC1323 and SACK if we haven't got any response to 722 * our third SYN to work-around some broken terminal servers 723 * (most of which have hopefully been retired) that have bad VJ 724 * header compression code which trashes TCP segments containing 725 * unknown-to-them TCP options. 726 */ 727 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && 728 (tp->t_rxtshift == 3)) 729 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); 730 /* 731 * If we backed off this far, our srtt estimate is probably bogus. 732 * Clobber it so we'll take the next rtt measurement as our srtt; 733 * move the current srtt into rttvar to keep the current 734 * retransmit times until then. 735 */ 736 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 737 #ifdef INET6 738 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 739 in6_losing(tp->t_inpcb); 740 #endif 741 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 742 tp->t_srtt = 0; 743 } 744 tp->snd_nxt = tp->snd_una; 745 tp->snd_recover = tp->snd_max; 746 /* 747 * Force a segment to be sent. 748 */ 749 tp->t_flags |= TF_ACKNOW; 750 /* 751 * If timing a segment in this window, stop the timer. 752 */ 753 tp->t_rtttime = 0; 754 755 cc_cong_signal(tp, NULL, CC_RTO); 756 757 (void) tcp_output(tp); 758 759 out: 760 #ifdef TCPDEBUG 761 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 762 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 763 PRU_SLOWTIMO); 764 #endif 765 if (tp != NULL) 766 INP_WUNLOCK(inp); 767 if (headlocked) 768 INP_INFO_RUNLOCK(&V_tcbinfo); 769 CURVNET_RESTORE(); 770 } 771 772 void 773 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) 774 { 775 struct callout *t_callout; 776 timeout_t *f_callout; 777 struct inpcb *inp = tp->t_inpcb; 778 int cpu = INP_CPU(inp); 779 uint32_t f_reset; 780 781 #ifdef TCP_OFFLOAD 782 if (tp->t_flags & TF_TOE) 783 return; 784 #endif 785 786 if (tp->t_timers->tt_flags & TT_STOPPED) 787 return; 788 789 switch (timer_type) { 790 case TT_DELACK: 791 t_callout = &tp->t_timers->tt_delack; 792 f_callout = tcp_timer_delack; 793 f_reset = TT_DELACK_RST; 794 break; 795 case TT_REXMT: 796 t_callout = &tp->t_timers->tt_rexmt; 797 f_callout = tcp_timer_rexmt; 798 f_reset = TT_REXMT_RST; 799 break; 800 case TT_PERSIST: 801 t_callout = &tp->t_timers->tt_persist; 802 f_callout = tcp_timer_persist; 803 f_reset = TT_PERSIST_RST; 804 break; 805 case TT_KEEP: 806 t_callout = &tp->t_timers->tt_keep; 807 f_callout = tcp_timer_keep; 808 f_reset = TT_KEEP_RST; 809 break; 810 case TT_2MSL: 811 t_callout = &tp->t_timers->tt_2msl; 812 f_callout = tcp_timer_2msl; 813 f_reset = TT_2MSL_RST; 814 break; 815 default: 816 panic("tp %p bad timer_type %#x", tp, timer_type); 817 } 818 if (delta == 0) { 819 if ((tp->t_timers->tt_flags & timer_type) && 820 callout_stop(t_callout) && 821 (tp->t_timers->tt_flags & f_reset)) { 822 tp->t_timers->tt_flags &= ~(timer_type | f_reset); 823 } 824 } else { 825 if ((tp->t_timers->tt_flags & timer_type) == 0) { 826 tp->t_timers->tt_flags |= (timer_type | f_reset); 827 callout_reset_on(t_callout, delta, f_callout, tp, cpu); 828 } else { 829 /* Reset already running callout on the same CPU. */ 830 if (!callout_reset(t_callout, delta, f_callout, tp)) { 831 /* 832 * Callout not cancelled, consider it as not 833 * properly restarted. */ 834 tp->t_timers->tt_flags &= ~f_reset; 835 } 836 } 837 } 838 } 839 840 int 841 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) 842 { 843 struct callout *t_callout; 844 845 switch (timer_type) { 846 case TT_DELACK: 847 t_callout = &tp->t_timers->tt_delack; 848 break; 849 case TT_REXMT: 850 t_callout = &tp->t_timers->tt_rexmt; 851 break; 852 case TT_PERSIST: 853 t_callout = &tp->t_timers->tt_persist; 854 break; 855 case TT_KEEP: 856 t_callout = &tp->t_timers->tt_keep; 857 break; 858 case TT_2MSL: 859 t_callout = &tp->t_timers->tt_2msl; 860 break; 861 default: 862 panic("tp %p bad timer_type %#x", tp, timer_type); 863 } 864 return callout_active(t_callout); 865 } 866 867 void 868 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) 869 { 870 struct callout *t_callout; 871 timeout_t *f_callout; 872 uint32_t f_reset; 873 874 tp->t_timers->tt_flags |= TT_STOPPED; 875 876 switch (timer_type) { 877 case TT_DELACK: 878 t_callout = &tp->t_timers->tt_delack; 879 f_callout = tcp_timer_delack_discard; 880 f_reset = TT_DELACK_RST; 881 break; 882 case TT_REXMT: 883 t_callout = &tp->t_timers->tt_rexmt; 884 f_callout = tcp_timer_rexmt_discard; 885 f_reset = TT_REXMT_RST; 886 break; 887 case TT_PERSIST: 888 t_callout = &tp->t_timers->tt_persist; 889 f_callout = tcp_timer_persist_discard; 890 f_reset = TT_PERSIST_RST; 891 break; 892 case TT_KEEP: 893 t_callout = &tp->t_timers->tt_keep; 894 f_callout = tcp_timer_keep_discard; 895 f_reset = TT_KEEP_RST; 896 break; 897 case TT_2MSL: 898 t_callout = &tp->t_timers->tt_2msl; 899 f_callout = tcp_timer_2msl_discard; 900 f_reset = TT_2MSL_RST; 901 break; 902 default: 903 panic("tp %p bad timer_type %#x", tp, timer_type); 904 } 905 906 if (tp->t_timers->tt_flags & timer_type) { 907 if (callout_stop(t_callout) && 908 (tp->t_timers->tt_flags & f_reset)) { 909 tp->t_timers->tt_flags &= ~(timer_type | f_reset); 910 } else { 911 /* 912 * Can't stop the callout, defer tcpcb actual deletion 913 * to the last tcp timer discard callout. 914 * The TT_STOPPED flag will ensure that no tcp timer 915 * callouts can be restarted on our behalf, and 916 * past this point currently running callouts waiting 917 * on inp lock will return right away after the 918 * classical check for callout reset/stop events: 919 * callout_pending() || !callout_active() 920 */ 921 callout_reset(t_callout, 1, f_callout, tp); 922 } 923 } 924 } 925 926 #define ticks_to_msecs(t) (1000*(t) / hz) 927 928 void 929 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, 930 struct xtcp_timer *xtimer) 931 { 932 sbintime_t now; 933 934 bzero(xtimer, sizeof(*xtimer)); 935 if (timer == NULL) 936 return; 937 now = getsbinuptime(); 938 if (callout_active(&timer->tt_delack)) 939 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS; 940 if (callout_active(&timer->tt_rexmt)) 941 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS; 942 if (callout_active(&timer->tt_persist)) 943 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS; 944 if (callout_active(&timer->tt_keep)) 945 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS; 946 if (callout_active(&timer->tt_2msl)) 947 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS; 948 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime); 949 }
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