1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_inet.h" 36 #include "opt_inet6.h" 37 #include "opt_tcpdebug.h" 38 #include "opt_rss.h" 39 40 #include <sys/param.h> 41 #include <sys/kernel.h> 42 #include <sys/lock.h> 43 #include <sys/mbuf.h> 44 #include <sys/mutex.h> 45 #include <sys/protosw.h> 46 #include <sys/smp.h> 47 #include <sys/socket.h> 48 #include <sys/socketvar.h> 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 52 #include <net/if.h> 53 #include <net/route.h> 54 #include <net/rss_config.h> 55 #include <net/vnet.h> 56 #include <net/netisr.h> 57 58 #include <netinet/cc.h> 59 #include <netinet/in.h> 60 #include <netinet/in_pcb.h> 61 #include <netinet/in_rss.h> 62 #include <netinet/in_systm.h> 63 #ifdef INET6 64 #include <netinet6/in6_pcb.h> 65 #endif 66 #include <netinet/ip_var.h> 67 #include <netinet/tcp_fsm.h> 68 #include <netinet/tcp_timer.h> 69 #include <netinet/tcp_var.h> 70 #ifdef INET6 71 #include <netinet6/tcp6_var.h> 72 #endif 73 #include <netinet/tcpip.h> 74 #ifdef TCPDEBUG 75 #include <netinet/tcp_debug.h> 76 #endif 77 78 int tcp_keepinit; 79 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW, 80 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection"); 81 82 int tcp_keepidle; 83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW, 84 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin"); 85 86 int tcp_keepintvl; 87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW, 88 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes"); 89 90 int tcp_delacktime; 91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW, 92 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", 93 "Time before a delayed ACK is sent"); 94 95 int tcp_msl; 96 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW, 97 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime"); 98 99 int tcp_rexmit_min; 100 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW, 101 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", 102 "Minimum Retransmission Timeout"); 103 104 int tcp_rexmit_slop; 105 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW, 106 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", 107 "Retransmission Timer Slop"); 108 109 static int always_keepalive = 1; 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, 111 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); 112 113 int tcp_fast_finwait2_recycle = 0; 114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW, 115 &tcp_fast_finwait2_recycle, 0, 116 "Recycle closed FIN_WAIT_2 connections faster"); 117 118 int tcp_finwait2_timeout; 119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW, 120 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout"); 121 122 int tcp_keepcnt = TCPTV_KEEPCNT; 123 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0, 124 "Number of keepalive probes to send"); 125 126 /* max idle probes */ 127 int tcp_maxpersistidle; 128 129 static int tcp_rexmit_drop_options = 0; 130 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW, 131 &tcp_rexmit_drop_options, 0, 132 "Drop TCP options from 3rd and later retransmitted SYN"); 133 134 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect); 135 #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect) 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, 137 CTLFLAG_RW|CTLFLAG_VNET, 138 &VNET_NAME(tcp_pmtud_blackhole_detect), 0, 139 "Path MTU Discovery Black Hole Detection Enabled"); 140 141 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated); 142 #define V_tcp_pmtud_blackhole_activated \ 143 VNET(tcp_pmtud_blackhole_activated) 144 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated, 145 CTLFLAG_RD|CTLFLAG_VNET, 146 &VNET_NAME(tcp_pmtud_blackhole_activated), 0, 147 "Path MTU Discovery Black Hole Detection, Activation Count"); 148 149 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss); 150 #define V_tcp_pmtud_blackhole_activated_min_mss \ 151 VNET(tcp_pmtud_blackhole_activated_min_mss) 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss, 153 CTLFLAG_RD|CTLFLAG_VNET, 154 &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0, 155 "Path MTU Discovery Black Hole Detection, Activation Count at min MSS"); 156 157 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed); 158 #define V_tcp_pmtud_blackhole_failed VNET(tcp_pmtud_blackhole_failed) 159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed, 160 CTLFLAG_RD|CTLFLAG_VNET, 161 &VNET_NAME(tcp_pmtud_blackhole_failed), 0, 162 "Path MTU Discovery Black Hole Detection, Failure Count"); 163 164 #ifdef INET 165 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200; 166 #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss) 167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, 168 CTLFLAG_RW|CTLFLAG_VNET, 169 &VNET_NAME(tcp_pmtud_blackhole_mss), 0, 170 "Path MTU Discovery Black Hole Detection lowered MSS"); 171 #endif 172 173 #ifdef INET6 174 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220; 175 #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss) 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss, 177 CTLFLAG_RW|CTLFLAG_VNET, 178 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0, 179 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS"); 180 #endif 181 182 #ifdef RSS 183 static int per_cpu_timers = 1; 184 #else 185 static int per_cpu_timers = 0; 186 #endif 187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW, 188 &per_cpu_timers , 0, "run tcp timers on all cpus"); 189 190 #if 0 191 #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 #endif 194 195 /* 196 * Map the given inp to a CPU id. 197 * 198 * This queries RSS if it's compiled in, else it defaults to the current 199 * CPU ID. 200 */ 201 static inline int 202 inp_to_cpuid(struct inpcb *inp) 203 { 204 u_int cpuid; 205 206 #ifdef RSS 207 if (per_cpu_timers) { 208 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype); 209 if (cpuid == NETISR_CPUID_NONE) 210 return (curcpu); /* XXX */ 211 else 212 return (cpuid); 213 } 214 #else 215 /* Legacy, pre-RSS behaviour */ 216 if (per_cpu_timers) { 217 /* 218 * We don't have a flowid -> cpuid mapping, so cheat and 219 * just map unknown cpuids to curcpu. Not the best, but 220 * apparently better than defaulting to swi 0. 221 */ 222 cpuid = inp->inp_flowid % (mp_maxid + 1); 223 if (! CPU_ABSENT(cpuid)) 224 return (cpuid); 225 return (curcpu); 226 } 227 #endif 228 /* Default for RSS and non-RSS - cpuid 0 */ 229 else { 230 return (0); 231 } 232 } 233 234 /* 235 * Tcp protocol timeout routine called every 500 ms. 236 * Updates timestamps used for TCP 237 * causes finite state machine actions if timers expire. 238 */ 239 void 240 tcp_slowtimo(void) 241 { 242 VNET_ITERATOR_DECL(vnet_iter); 243 244 VNET_LIST_RLOCK_NOSLEEP(); 245 VNET_FOREACH(vnet_iter) { 246 CURVNET_SET(vnet_iter); 247 (void) tcp_tw_2msl_scan(0); 248 CURVNET_RESTORE(); 249 } 250 VNET_LIST_RUNLOCK_NOSLEEP(); 251 } 252 253 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = 254 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; 255 256 int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 257 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; 258 259 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ 260 261 /* 262 * TCP timer processing. 263 */ 264 265 void 266 tcp_timer_delack(void *xtp) 267 { 268 struct tcpcb *tp = xtp; 269 struct inpcb *inp; 270 CURVNET_SET(tp->t_vnet); 271 272 inp = tp->t_inpcb; 273 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 274 INP_WLOCK(inp); 275 if (callout_pending(&tp->t_timers->tt_delack) || 276 !callout_active(&tp->t_timers->tt_delack)) { 277 INP_WUNLOCK(inp); 278 CURVNET_RESTORE(); 279 return; 280 } 281 callout_deactivate(&tp->t_timers->tt_delack); 282 if ((inp->inp_flags & INP_DROPPED) != 0) { 283 INP_WUNLOCK(inp); 284 CURVNET_RESTORE(); 285 return; 286 } 287 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 288 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 289 KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0, 290 ("%s: tp %p delack callout should be running", __func__, tp)); 291 292 tp->t_flags |= TF_ACKNOW; 293 TCPSTAT_INC(tcps_delack); 294 (void) tcp_output(tp); 295 INP_WUNLOCK(inp); 296 CURVNET_RESTORE(); 297 } 298 299 void 300 tcp_timer_2msl(void *xtp) 301 { 302 struct tcpcb *tp = xtp; 303 struct inpcb *inp; 304 CURVNET_SET(tp->t_vnet); 305 #ifdef TCPDEBUG 306 int ostate; 307 308 ostate = tp->t_state; 309 #endif 310 INP_INFO_RLOCK(&V_tcbinfo); 311 inp = tp->t_inpcb; 312 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 313 INP_WLOCK(inp); 314 tcp_free_sackholes(tp); 315 if (callout_pending(&tp->t_timers->tt_2msl) || 316 !callout_active(&tp->t_timers->tt_2msl)) { 317 INP_WUNLOCK(tp->t_inpcb); 318 INP_INFO_RUNLOCK(&V_tcbinfo); 319 CURVNET_RESTORE(); 320 return; 321 } 322 callout_deactivate(&tp->t_timers->tt_2msl); 323 if ((inp->inp_flags & INP_DROPPED) != 0) { 324 INP_WUNLOCK(inp); 325 INP_INFO_RUNLOCK(&V_tcbinfo); 326 CURVNET_RESTORE(); 327 return; 328 } 329 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 330 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 331 KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0, 332 ("%s: tp %p 2msl callout should be running", __func__, tp)); 333 /* 334 * 2 MSL timeout in shutdown went off. If we're closed but 335 * still waiting for peer to close and connection has been idle 336 * too long delete connection control block. Otherwise, check 337 * again in a bit. 338 * 339 * If in TIME_WAIT state just ignore as this timeout is handled in 340 * tcp_tw_2msl_scan(). 341 * 342 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, 343 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. 344 * Ignore fact that there were recent incoming segments. 345 */ 346 if ((inp->inp_flags & INP_TIMEWAIT) != 0) { 347 INP_WUNLOCK(inp); 348 INP_INFO_RUNLOCK(&V_tcbinfo); 349 CURVNET_RESTORE(); 350 return; 351 } 352 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 && 353 tp->t_inpcb && tp->t_inpcb->inp_socket && 354 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) { 355 TCPSTAT_INC(tcps_finwait2_drops); 356 tp = tcp_close(tp); 357 } else { 358 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) 359 callout_reset(&tp->t_timers->tt_2msl, 360 TP_KEEPINTVL(tp), tcp_timer_2msl, tp); 361 else 362 tp = tcp_close(tp); 363 } 364 365 #ifdef TCPDEBUG 366 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 367 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 368 PRU_SLOWTIMO); 369 #endif 370 if (tp != NULL) 371 INP_WUNLOCK(inp); 372 INP_INFO_RUNLOCK(&V_tcbinfo); 373 CURVNET_RESTORE(); 374 } 375 376 void 377 tcp_timer_keep(void *xtp) 378 { 379 struct tcpcb *tp = xtp; 380 struct tcptemp *t_template; 381 struct inpcb *inp; 382 CURVNET_SET(tp->t_vnet); 383 #ifdef TCPDEBUG 384 int ostate; 385 386 ostate = tp->t_state; 387 #endif 388 INP_INFO_RLOCK(&V_tcbinfo); 389 inp = tp->t_inpcb; 390 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 391 INP_WLOCK(inp); 392 if (callout_pending(&tp->t_timers->tt_keep) || 393 !callout_active(&tp->t_timers->tt_keep)) { 394 INP_WUNLOCK(inp); 395 INP_INFO_RUNLOCK(&V_tcbinfo); 396 CURVNET_RESTORE(); 397 return; 398 } 399 callout_deactivate(&tp->t_timers->tt_keep); 400 if ((inp->inp_flags & INP_DROPPED) != 0) { 401 INP_WUNLOCK(inp); 402 INP_INFO_RUNLOCK(&V_tcbinfo); 403 CURVNET_RESTORE(); 404 return; 405 } 406 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 407 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 408 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0, 409 ("%s: tp %p keep callout should be running", __func__, tp)); 410 /* 411 * Keep-alive timer went off; send something 412 * or drop connection if idle for too long. 413 */ 414 TCPSTAT_INC(tcps_keeptimeo); 415 if (tp->t_state < TCPS_ESTABLISHED) 416 goto dropit; 417 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 418 tp->t_state <= TCPS_CLOSING) { 419 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) 420 goto dropit; 421 /* 422 * Send a packet designed to force a response 423 * if the peer is up and reachable: 424 * either an ACK if the connection is still alive, 425 * or an RST if the peer has closed the connection 426 * due to timeout or reboot. 427 * Using sequence number tp->snd_una-1 428 * causes the transmitted zero-length segment 429 * to lie outside the receive window; 430 * by the protocol spec, this requires the 431 * correspondent TCP to respond. 432 */ 433 TCPSTAT_INC(tcps_keepprobe); 434 t_template = tcpip_maketemplate(inp); 435 if (t_template) { 436 tcp_respond(tp, t_template->tt_ipgen, 437 &t_template->tt_t, (struct mbuf *)NULL, 438 tp->rcv_nxt, tp->snd_una - 1, 0); 439 free(t_template, M_TEMP); 440 } 441 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), 442 tcp_timer_keep, tp); 443 } else 444 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), 445 tcp_timer_keep, tp); 446 447 #ifdef TCPDEBUG 448 if (inp->inp_socket->so_options & SO_DEBUG) 449 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 450 PRU_SLOWTIMO); 451 #endif 452 INP_WUNLOCK(inp); 453 INP_INFO_RUNLOCK(&V_tcbinfo); 454 CURVNET_RESTORE(); 455 return; 456 457 dropit: 458 TCPSTAT_INC(tcps_keepdrops); 459 tp = tcp_drop(tp, ETIMEDOUT); 460 461 #ifdef TCPDEBUG 462 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 463 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 464 PRU_SLOWTIMO); 465 #endif 466 if (tp != NULL) 467 INP_WUNLOCK(tp->t_inpcb); 468 INP_INFO_RUNLOCK(&V_tcbinfo); 469 CURVNET_RESTORE(); 470 } 471 472 void 473 tcp_timer_persist(void *xtp) 474 { 475 struct tcpcb *tp = xtp; 476 struct inpcb *inp; 477 CURVNET_SET(tp->t_vnet); 478 #ifdef TCPDEBUG 479 int ostate; 480 481 ostate = tp->t_state; 482 #endif 483 INP_INFO_RLOCK(&V_tcbinfo); 484 inp = tp->t_inpcb; 485 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 486 INP_WLOCK(inp); 487 if (callout_pending(&tp->t_timers->tt_persist) || 488 !callout_active(&tp->t_timers->tt_persist)) { 489 INP_WUNLOCK(inp); 490 INP_INFO_RUNLOCK(&V_tcbinfo); 491 CURVNET_RESTORE(); 492 return; 493 } 494 callout_deactivate(&tp->t_timers->tt_persist); 495 if ((inp->inp_flags & INP_DROPPED) != 0) { 496 INP_WUNLOCK(inp); 497 INP_INFO_RUNLOCK(&V_tcbinfo); 498 CURVNET_RESTORE(); 499 return; 500 } 501 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 502 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 503 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0, 504 ("%s: tp %p persist callout should be running", __func__, tp)); 505 /* 506 * Persistance timer into zero window. 507 * Force a byte to be output, if possible. 508 */ 509 TCPSTAT_INC(tcps_persisttimeo); 510 /* 511 * Hack: if the peer is dead/unreachable, we do not 512 * time out if the window is closed. After a full 513 * backoff, drop the connection if the idle time 514 * (no responses to probes) reaches the maximum 515 * backoff that we would use if retransmitting. 516 */ 517 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 518 (ticks - tp->t_rcvtime >= tcp_maxpersistidle || 519 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 520 TCPSTAT_INC(tcps_persistdrop); 521 tp = tcp_drop(tp, ETIMEDOUT); 522 goto out; 523 } 524 /* 525 * If the user has closed the socket then drop a persisting 526 * connection after a much reduced timeout. 527 */ 528 if (tp->t_state > TCPS_CLOSE_WAIT && 529 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { 530 TCPSTAT_INC(tcps_persistdrop); 531 tp = tcp_drop(tp, ETIMEDOUT); 532 goto out; 533 } 534 tcp_setpersist(tp); 535 tp->t_flags |= TF_FORCEDATA; 536 (void) tcp_output(tp); 537 tp->t_flags &= ~TF_FORCEDATA; 538 539 out: 540 #ifdef TCPDEBUG 541 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 542 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 543 #endif 544 if (tp != NULL) 545 INP_WUNLOCK(inp); 546 INP_INFO_RUNLOCK(&V_tcbinfo); 547 CURVNET_RESTORE(); 548 } 549 550 void 551 tcp_timer_rexmt(void * xtp) 552 { 553 struct tcpcb *tp = xtp; 554 CURVNET_SET(tp->t_vnet); 555 int rexmt; 556 int headlocked; 557 struct inpcb *inp; 558 #ifdef TCPDEBUG 559 int ostate; 560 561 ostate = tp->t_state; 562 #endif 563 564 INP_INFO_RLOCK(&V_tcbinfo); 565 inp = tp->t_inpcb; 566 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 567 INP_WLOCK(inp); 568 if (callout_pending(&tp->t_timers->tt_rexmt) || 569 !callout_active(&tp->t_timers->tt_rexmt)) { 570 INP_WUNLOCK(inp); 571 INP_INFO_RUNLOCK(&V_tcbinfo); 572 CURVNET_RESTORE(); 573 return; 574 } 575 callout_deactivate(&tp->t_timers->tt_rexmt); 576 if ((inp->inp_flags & INP_DROPPED) != 0) { 577 INP_WUNLOCK(inp); 578 INP_INFO_RUNLOCK(&V_tcbinfo); 579 CURVNET_RESTORE(); 580 return; 581 } 582 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 583 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 584 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0, 585 ("%s: tp %p rexmt callout should be running", __func__, tp)); 586 tcp_free_sackholes(tp); 587 /* 588 * Retransmission timer went off. Message has not 589 * been acked within retransmit interval. Back off 590 * to a longer retransmit interval and retransmit one segment. 591 */ 592 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 593 tp->t_rxtshift = TCP_MAXRXTSHIFT; 594 TCPSTAT_INC(tcps_timeoutdrop); 595 596 tp = tcp_drop(tp, tp->t_softerror ? 597 tp->t_softerror : ETIMEDOUT); 598 headlocked = 1; 599 goto out; 600 } 601 INP_INFO_RUNLOCK(&V_tcbinfo); 602 headlocked = 0; 603 if (tp->t_state == TCPS_SYN_SENT) { 604 /* 605 * If the SYN was retransmitted, indicate CWND to be 606 * limited to 1 segment in cc_conn_init(). 607 */ 608 tp->snd_cwnd = 1; 609 } else if (tp->t_rxtshift == 1) { 610 /* 611 * first retransmit; record ssthresh and cwnd so they can 612 * be recovered if this turns out to be a "bad" retransmit. 613 * A retransmit is considered "bad" if an ACK for this 614 * segment is received within RTT/2 interval; the assumption 615 * here is that the ACK was already in flight. See 616 * "On Estimating End-to-End Network Path Properties" by 617 * Allman and Paxson for more details. 618 */ 619 tp->snd_cwnd_prev = tp->snd_cwnd; 620 tp->snd_ssthresh_prev = tp->snd_ssthresh; 621 tp->snd_recover_prev = tp->snd_recover; 622 if (IN_FASTRECOVERY(tp->t_flags)) 623 tp->t_flags |= TF_WASFRECOVERY; 624 else 625 tp->t_flags &= ~TF_WASFRECOVERY; 626 if (IN_CONGRECOVERY(tp->t_flags)) 627 tp->t_flags |= TF_WASCRECOVERY; 628 else 629 tp->t_flags &= ~TF_WASCRECOVERY; 630 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 631 tp->t_flags |= TF_PREVVALID; 632 } else 633 tp->t_flags &= ~TF_PREVVALID; 634 TCPSTAT_INC(tcps_rexmttimeo); 635 if (tp->t_state == TCPS_SYN_SENT) 636 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; 637 else 638 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 639 TCPT_RANGESET(tp->t_rxtcur, rexmt, 640 tp->t_rttmin, TCPTV_REXMTMAX); 641 642 /* 643 * We enter the path for PLMTUD if connection is established or, if 644 * connection is FIN_WAIT_1 status, reason for the last is that if 645 * amount of data we send is very small, we could send it in couple of 646 * packets and process straight to FIN. In that case we won't catch 647 * ESTABLISHED state. 648 */ 649 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED)) 650 || (tp->t_state == TCPS_FIN_WAIT_1))) { 651 int optlen; 652 #ifdef INET6 653 int isipv6; 654 #endif 655 656 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == 657 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && 658 (tp->t_rxtshift <= 2)) { 659 /* 660 * Enter Path MTU Black-hole Detection mechanism: 661 * - Disable Path MTU Discovery (IP "DF" bit). 662 * - Reduce MTU to lower value than what we 663 * negotiated with peer. 664 */ 665 /* Record that we may have found a black hole. */ 666 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; 667 668 /* Keep track of previous MSS. */ 669 optlen = tp->t_maxopd - tp->t_maxseg; 670 tp->t_pmtud_saved_maxopd = tp->t_maxopd; 671 672 /* 673 * Reduce the MSS to blackhole value or to the default 674 * in an attempt to retransmit. 675 */ 676 #ifdef INET6 677 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0; 678 if (isipv6 && 679 tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) { 680 /* Use the sysctl tuneable blackhole MSS. */ 681 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss; 682 V_tcp_pmtud_blackhole_activated++; 683 } else if (isipv6) { 684 /* Use the default MSS. */ 685 tp->t_maxopd = V_tcp_v6mssdflt; 686 /* 687 * Disable Path MTU Discovery when we switch to 688 * minmss. 689 */ 690 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 691 V_tcp_pmtud_blackhole_activated_min_mss++; 692 } 693 #endif 694 #if defined(INET6) && defined(INET) 695 else 696 #endif 697 #ifdef INET 698 if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) { 699 /* Use the sysctl tuneable blackhole MSS. */ 700 tp->t_maxopd = V_tcp_pmtud_blackhole_mss; 701 V_tcp_pmtud_blackhole_activated++; 702 } else { 703 /* Use the default MSS. */ 704 tp->t_maxopd = V_tcp_mssdflt; 705 /* 706 * Disable Path MTU Discovery when we switch to 707 * minmss. 708 */ 709 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 710 V_tcp_pmtud_blackhole_activated_min_mss++; 711 } 712 #endif 713 tp->t_maxseg = tp->t_maxopd - optlen; 714 /* 715 * Reset the slow-start flight size 716 * as it may depend on the new MSS. 717 */ 718 if (CC_ALGO(tp)->conn_init != NULL) 719 CC_ALGO(tp)->conn_init(tp->ccv); 720 } else { 721 /* 722 * If further retransmissions are still unsuccessful 723 * with a lowered MTU, maybe this isn't a blackhole and 724 * we restore the previous MSS and blackhole detection 725 * flags. 726 */ 727 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && 728 (tp->t_rxtshift > 4)) { 729 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 730 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; 731 optlen = tp->t_maxopd - tp->t_maxseg; 732 tp->t_maxopd = tp->t_pmtud_saved_maxopd; 733 tp->t_maxseg = tp->t_maxopd - optlen; 734 V_tcp_pmtud_blackhole_failed++; 735 /* 736 * Reset the slow-start flight size as it 737 * may depend on the new MSS. 738 */ 739 if (CC_ALGO(tp)->conn_init != NULL) 740 CC_ALGO(tp)->conn_init(tp->ccv); 741 } 742 } 743 } 744 745 /* 746 * Disable RFC1323 and SACK if we haven't got any response to 747 * our third SYN to work-around some broken terminal servers 748 * (most of which have hopefully been retired) that have bad VJ 749 * header compression code which trashes TCP segments containing 750 * unknown-to-them TCP options. 751 */ 752 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && 753 (tp->t_rxtshift == 3)) 754 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); 755 /* 756 * If we backed off this far, our srtt estimate is probably bogus. 757 * Clobber it so we'll take the next rtt measurement as our srtt; 758 * move the current srtt into rttvar to keep the current 759 * retransmit times until then. 760 */ 761 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 762 #ifdef INET6 763 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 764 in6_losing(tp->t_inpcb); 765 #endif 766 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 767 tp->t_srtt = 0; 768 } 769 tp->snd_nxt = tp->snd_una; 770 tp->snd_recover = tp->snd_max; 771 /* 772 * Force a segment to be sent. 773 */ 774 tp->t_flags |= TF_ACKNOW; 775 /* 776 * If timing a segment in this window, stop the timer. 777 */ 778 tp->t_rtttime = 0; 779 780 cc_cong_signal(tp, NULL, CC_RTO); 781 782 (void) tcp_output(tp); 783 784 out: 785 #ifdef TCPDEBUG 786 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 787 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 788 PRU_SLOWTIMO); 789 #endif 790 if (tp != NULL) 791 INP_WUNLOCK(inp); 792 if (headlocked) 793 INP_INFO_RUNLOCK(&V_tcbinfo); 794 CURVNET_RESTORE(); 795 } 796 797 void 798 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) 799 { 800 struct callout *t_callout; 801 timeout_t *f_callout; 802 struct inpcb *inp = tp->t_inpcb; 803 int cpu = inp_to_cpuid(inp); 804 805 #ifdef TCP_OFFLOAD 806 if (tp->t_flags & TF_TOE) 807 return; 808 #endif 809 810 if (tp->t_timers->tt_flags & TT_STOPPED) 811 return; 812 813 switch (timer_type) { 814 case TT_DELACK: 815 t_callout = &tp->t_timers->tt_delack; 816 f_callout = tcp_timer_delack; 817 break; 818 case TT_REXMT: 819 t_callout = &tp->t_timers->tt_rexmt; 820 f_callout = tcp_timer_rexmt; 821 break; 822 case TT_PERSIST: 823 t_callout = &tp->t_timers->tt_persist; 824 f_callout = tcp_timer_persist; 825 break; 826 case TT_KEEP: 827 t_callout = &tp->t_timers->tt_keep; 828 f_callout = tcp_timer_keep; 829 break; 830 case TT_2MSL: 831 t_callout = &tp->t_timers->tt_2msl; 832 f_callout = tcp_timer_2msl; 833 break; 834 default: 835 panic("tp %p bad timer_type %#x", tp, timer_type); 836 } 837 if (delta == 0) { 838 if ((tp->t_timers->tt_flags & timer_type) && 839 callout_stop(t_callout)) { 840 tp->t_timers->tt_flags &= ~timer_type; 841 } 842 } else { 843 if ((tp->t_timers->tt_flags & timer_type) == 0) { 844 tp->t_timers->tt_flags |= timer_type; 845 callout_reset_on(t_callout, delta, f_callout, tp, cpu); 846 } else { 847 /* Reset already running callout on the same CPU. */ 848 callout_reset(t_callout, delta, f_callout, tp); 849 } 850 } 851 } 852 853 int 854 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) 855 { 856 struct callout *t_callout; 857 858 switch (timer_type) { 859 case TT_DELACK: 860 t_callout = &tp->t_timers->tt_delack; 861 break; 862 case TT_REXMT: 863 t_callout = &tp->t_timers->tt_rexmt; 864 break; 865 case TT_PERSIST: 866 t_callout = &tp->t_timers->tt_persist; 867 break; 868 case TT_KEEP: 869 t_callout = &tp->t_timers->tt_keep; 870 break; 871 case TT_2MSL: 872 t_callout = &tp->t_timers->tt_2msl; 873 break; 874 default: 875 panic("tp %p bad timer_type %#x", tp, timer_type); 876 } 877 return callout_active(t_callout); 878 } 879 880 void 881 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) 882 { 883 struct callout *t_callout; 884 timeout_t *f_callout; 885 886 tp->t_timers->tt_flags |= TT_STOPPED; 887 888 switch (timer_type) { 889 case TT_DELACK: 890 t_callout = &tp->t_timers->tt_delack; 891 f_callout = tcp_timer_delack_discard; 892 break; 893 case TT_REXMT: 894 t_callout = &tp->t_timers->tt_rexmt; 895 f_callout = tcp_timer_rexmt_discard; 896 break; 897 case TT_PERSIST: 898 t_callout = &tp->t_timers->tt_persist; 899 f_callout = tcp_timer_persist_discard; 900 break; 901 case TT_KEEP: 902 t_callout = &tp->t_timers->tt_keep; 903 f_callout = tcp_timer_keep_discard; 904 break; 905 case TT_2MSL: 906 t_callout = &tp->t_timers->tt_2msl; 907 f_callout = tcp_timer_2msl_discard; 908 break; 909 default: 910 panic("tp %p bad timer_type %#x", tp, timer_type); 911 } 912 913 if (tp->t_timers->tt_flags & timer_type) { 914 if (callout_stop(t_callout)) { 915 tp->t_timers->tt_flags &= ~timer_type; 916 } else { 917 /* 918 * Can't stop the callout, defer tcpcb actual deletion 919 * to the last tcp timer discard callout. 920 * The TT_STOPPED flag will ensure that no tcp timer 921 * callouts can be restarted on our behalf, and 922 * past this point currently running callouts waiting 923 * on inp lock will return right away after the 924 * classical check for callout reset/stop events: 925 * callout_pending() || !callout_active() 926 */ 927 callout_reset(t_callout, 1, f_callout, tp); 928 } 929 } 930 } 931 932 #define ticks_to_msecs(t) (1000*(t) / hz) 933 934 void 935 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, 936 struct xtcp_timer *xtimer) 937 { 938 sbintime_t now; 939 940 bzero(xtimer, sizeof(*xtimer)); 941 if (timer == NULL) 942 return; 943 now = getsbinuptime(); 944 if (callout_active(&timer->tt_delack)) 945 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS; 946 if (callout_active(&timer->tt_rexmt)) 947 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS; 948 if (callout_active(&timer->tt_persist)) 949 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS; 950 if (callout_active(&timer->tt_keep)) 951 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS; 952 if (callout_active(&timer->tt_2msl)) 953 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS; 954 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime); 955 } 956