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_WLOCK(&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_WUNLOCK(&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_WUNLOCK(&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, or if 2MSL time is up from TIME_WAIT, delete connection 337 * control block. Otherwise, check again in a bit. 338 * 339 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, 340 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. 341 * Ignore fact that there were recent incoming segments. 342 */ 343 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 && 344 tp->t_inpcb && tp->t_inpcb->inp_socket && 345 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) { 346 TCPSTAT_INC(tcps_finwait2_drops); 347 tp = tcp_close(tp); 348 } else { 349 if (tp->t_state != TCPS_TIME_WAIT && 350 ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) 351 callout_reset_on(&tp->t_timers->tt_2msl, 352 TP_KEEPINTVL(tp), tcp_timer_2msl, tp, 353 inp_to_cpuid(inp)); 354 else 355 tp = tcp_close(tp); 356 } 357 358 #ifdef TCPDEBUG 359 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 360 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 361 PRU_SLOWTIMO); 362 #endif 363 if (tp != NULL) 364 INP_WUNLOCK(inp); 365 INP_INFO_WUNLOCK(&V_tcbinfo); 366 CURVNET_RESTORE(); 367 } 368 369 void 370 tcp_timer_keep(void *xtp) 371 { 372 struct tcpcb *tp = xtp; 373 struct tcptemp *t_template; 374 struct inpcb *inp; 375 CURVNET_SET(tp->t_vnet); 376 #ifdef TCPDEBUG 377 int ostate; 378 379 ostate = tp->t_state; 380 #endif 381 INP_INFO_WLOCK(&V_tcbinfo); 382 inp = tp->t_inpcb; 383 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 384 INP_WLOCK(inp); 385 if (callout_pending(&tp->t_timers->tt_keep) || 386 !callout_active(&tp->t_timers->tt_keep)) { 387 INP_WUNLOCK(inp); 388 INP_INFO_WUNLOCK(&V_tcbinfo); 389 CURVNET_RESTORE(); 390 return; 391 } 392 callout_deactivate(&tp->t_timers->tt_keep); 393 if ((inp->inp_flags & INP_DROPPED) != 0) { 394 INP_WUNLOCK(inp); 395 INP_INFO_WUNLOCK(&V_tcbinfo); 396 CURVNET_RESTORE(); 397 return; 398 } 399 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 400 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 401 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0, 402 ("%s: tp %p keep callout should be running", __func__, tp)); 403 /* 404 * Keep-alive timer went off; send something 405 * or drop connection if idle for too long. 406 */ 407 TCPSTAT_INC(tcps_keeptimeo); 408 if (tp->t_state < TCPS_ESTABLISHED) 409 goto dropit; 410 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 411 tp->t_state <= TCPS_CLOSING) { 412 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) 413 goto dropit; 414 /* 415 * Send a packet designed to force a response 416 * if the peer is up and reachable: 417 * either an ACK if the connection is still alive, 418 * or an RST if the peer has closed the connection 419 * due to timeout or reboot. 420 * Using sequence number tp->snd_una-1 421 * causes the transmitted zero-length segment 422 * to lie outside the receive window; 423 * by the protocol spec, this requires the 424 * correspondent TCP to respond. 425 */ 426 TCPSTAT_INC(tcps_keepprobe); 427 t_template = tcpip_maketemplate(inp); 428 if (t_template) { 429 tcp_respond(tp, t_template->tt_ipgen, 430 &t_template->tt_t, (struct mbuf *)NULL, 431 tp->rcv_nxt, tp->snd_una - 1, 0); 432 free(t_template, M_TEMP); 433 } 434 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), 435 tcp_timer_keep, tp, inp_to_cpuid(inp)); 436 } else 437 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), 438 tcp_timer_keep, tp, inp_to_cpuid(inp)); 439 440 #ifdef TCPDEBUG 441 if (inp->inp_socket->so_options & SO_DEBUG) 442 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 443 PRU_SLOWTIMO); 444 #endif 445 INP_WUNLOCK(inp); 446 INP_INFO_WUNLOCK(&V_tcbinfo); 447 CURVNET_RESTORE(); 448 return; 449 450 dropit: 451 TCPSTAT_INC(tcps_keepdrops); 452 tp = tcp_drop(tp, ETIMEDOUT); 453 454 #ifdef TCPDEBUG 455 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 456 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 457 PRU_SLOWTIMO); 458 #endif 459 if (tp != NULL) 460 INP_WUNLOCK(tp->t_inpcb); 461 INP_INFO_WUNLOCK(&V_tcbinfo); 462 CURVNET_RESTORE(); 463 } 464 465 void 466 tcp_timer_persist(void *xtp) 467 { 468 struct tcpcb *tp = xtp; 469 struct inpcb *inp; 470 CURVNET_SET(tp->t_vnet); 471 #ifdef TCPDEBUG 472 int ostate; 473 474 ostate = tp->t_state; 475 #endif 476 INP_INFO_WLOCK(&V_tcbinfo); 477 inp = tp->t_inpcb; 478 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 479 INP_WLOCK(inp); 480 if (callout_pending(&tp->t_timers->tt_persist) || 481 !callout_active(&tp->t_timers->tt_persist)) { 482 INP_WUNLOCK(inp); 483 INP_INFO_WUNLOCK(&V_tcbinfo); 484 CURVNET_RESTORE(); 485 return; 486 } 487 callout_deactivate(&tp->t_timers->tt_persist); 488 if ((inp->inp_flags & INP_DROPPED) != 0) { 489 INP_WUNLOCK(inp); 490 INP_INFO_WUNLOCK(&V_tcbinfo); 491 CURVNET_RESTORE(); 492 return; 493 } 494 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 495 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 496 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0, 497 ("%s: tp %p persist callout should be running", __func__, tp)); 498 /* 499 * Persistance timer into zero window. 500 * Force a byte to be output, if possible. 501 */ 502 TCPSTAT_INC(tcps_persisttimeo); 503 /* 504 * Hack: if the peer is dead/unreachable, we do not 505 * time out if the window is closed. After a full 506 * backoff, drop the connection if the idle time 507 * (no responses to probes) reaches the maximum 508 * backoff that we would use if retransmitting. 509 */ 510 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 511 (ticks - tp->t_rcvtime >= tcp_maxpersistidle || 512 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 513 TCPSTAT_INC(tcps_persistdrop); 514 tp = tcp_drop(tp, ETIMEDOUT); 515 goto out; 516 } 517 /* 518 * If the user has closed the socket then drop a persisting 519 * connection after a much reduced timeout. 520 */ 521 if (tp->t_state > TCPS_CLOSE_WAIT && 522 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { 523 TCPSTAT_INC(tcps_persistdrop); 524 tp = tcp_drop(tp, ETIMEDOUT); 525 goto out; 526 } 527 tcp_setpersist(tp); 528 tp->t_flags |= TF_FORCEDATA; 529 (void) tcp_output(tp); 530 tp->t_flags &= ~TF_FORCEDATA; 531 532 out: 533 #ifdef TCPDEBUG 534 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 535 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 536 #endif 537 if (tp != NULL) 538 INP_WUNLOCK(inp); 539 INP_INFO_WUNLOCK(&V_tcbinfo); 540 CURVNET_RESTORE(); 541 } 542 543 void 544 tcp_timer_rexmt(void * xtp) 545 { 546 struct tcpcb *tp = xtp; 547 CURVNET_SET(tp->t_vnet); 548 int rexmt; 549 int headlocked; 550 struct inpcb *inp; 551 #ifdef TCPDEBUG 552 int ostate; 553 554 ostate = tp->t_state; 555 #endif 556 557 INP_INFO_RLOCK(&V_tcbinfo); 558 inp = tp->t_inpcb; 559 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 560 INP_WLOCK(inp); 561 if (callout_pending(&tp->t_timers->tt_rexmt) || 562 !callout_active(&tp->t_timers->tt_rexmt)) { 563 INP_WUNLOCK(inp); 564 INP_INFO_RUNLOCK(&V_tcbinfo); 565 CURVNET_RESTORE(); 566 return; 567 } 568 callout_deactivate(&tp->t_timers->tt_rexmt); 569 if ((inp->inp_flags & INP_DROPPED) != 0) { 570 INP_WUNLOCK(inp); 571 INP_INFO_RUNLOCK(&V_tcbinfo); 572 CURVNET_RESTORE(); 573 return; 574 } 575 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 576 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 577 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0, 578 ("%s: tp %p rexmt callout should be running", __func__, tp)); 579 tcp_free_sackholes(tp); 580 /* 581 * Retransmission timer went off. Message has not 582 * been acked within retransmit interval. Back off 583 * to a longer retransmit interval and retransmit one segment. 584 */ 585 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 586 tp->t_rxtshift = TCP_MAXRXTSHIFT; 587 TCPSTAT_INC(tcps_timeoutdrop); 588 in_pcbref(inp); 589 INP_INFO_RUNLOCK(&V_tcbinfo); 590 INP_WUNLOCK(inp); 591 INP_INFO_WLOCK(&V_tcbinfo); 592 INP_WLOCK(inp); 593 if (in_pcbrele_wlocked(inp)) { 594 INP_INFO_WUNLOCK(&V_tcbinfo); 595 CURVNET_RESTORE(); 596 return; 597 } 598 if (inp->inp_flags & INP_DROPPED) { 599 INP_WUNLOCK(inp); 600 INP_INFO_WUNLOCK(&V_tcbinfo); 601 CURVNET_RESTORE(); 602 return; 603 } 604 605 tp = tcp_drop(tp, tp->t_softerror ? 606 tp->t_softerror : ETIMEDOUT); 607 headlocked = 1; 608 goto out; 609 } 610 INP_INFO_RUNLOCK(&V_tcbinfo); 611 headlocked = 0; 612 if (tp->t_state == TCPS_SYN_SENT) { 613 /* 614 * If the SYN was retransmitted, indicate CWND to be 615 * limited to 1 segment in cc_conn_init(). 616 */ 617 tp->snd_cwnd = 1; 618 } else if (tp->t_rxtshift == 1) { 619 /* 620 * first retransmit; record ssthresh and cwnd so they can 621 * be recovered if this turns out to be a "bad" retransmit. 622 * A retransmit is considered "bad" if an ACK for this 623 * segment is received within RTT/2 interval; the assumption 624 * here is that the ACK was already in flight. See 625 * "On Estimating End-to-End Network Path Properties" by 626 * Allman and Paxson for more details. 627 */ 628 tp->snd_cwnd_prev = tp->snd_cwnd; 629 tp->snd_ssthresh_prev = tp->snd_ssthresh; 630 tp->snd_recover_prev = tp->snd_recover; 631 if (IN_FASTRECOVERY(tp->t_flags)) 632 tp->t_flags |= TF_WASFRECOVERY; 633 else 634 tp->t_flags &= ~TF_WASFRECOVERY; 635 if (IN_CONGRECOVERY(tp->t_flags)) 636 tp->t_flags |= TF_WASCRECOVERY; 637 else 638 tp->t_flags &= ~TF_WASCRECOVERY; 639 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 640 tp->t_flags |= TF_PREVVALID; 641 } else 642 tp->t_flags &= ~TF_PREVVALID; 643 TCPSTAT_INC(tcps_rexmttimeo); 644 if (tp->t_state == TCPS_SYN_SENT) 645 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; 646 else 647 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 648 TCPT_RANGESET(tp->t_rxtcur, rexmt, 649 tp->t_rttmin, TCPTV_REXMTMAX); 650 651 /* 652 * We enter the path for PLMTUD if connection is established or, if 653 * connection is FIN_WAIT_1 status, reason for the last is that if 654 * amount of data we send is very small, we could send it in couple of 655 * packets and process straight to FIN. In that case we won't catch 656 * ESTABLISHED state. 657 */ 658 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED)) 659 || (tp->t_state == TCPS_FIN_WAIT_1))) { 660 int optlen; 661 #ifdef INET6 662 int isipv6; 663 #endif 664 665 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == 666 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && 667 (tp->t_rxtshift <= 2)) { 668 /* 669 * Enter Path MTU Black-hole Detection mechanism: 670 * - Disable Path MTU Discovery (IP "DF" bit). 671 * - Reduce MTU to lower value than what we 672 * negotiated with peer. 673 */ 674 /* Record that we may have found a black hole. */ 675 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; 676 677 /* Keep track of previous MSS. */ 678 optlen = tp->t_maxopd - tp->t_maxseg; 679 tp->t_pmtud_saved_maxopd = tp->t_maxopd; 680 681 /* 682 * Reduce the MSS to blackhole value or to the default 683 * in an attempt to retransmit. 684 */ 685 #ifdef INET6 686 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0; 687 if (isipv6 && 688 tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) { 689 /* Use the sysctl tuneable blackhole MSS. */ 690 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss; 691 V_tcp_pmtud_blackhole_activated++; 692 } else if (isipv6) { 693 /* Use the default MSS. */ 694 tp->t_maxopd = V_tcp_v6mssdflt; 695 /* 696 * Disable Path MTU Discovery when we switch to 697 * minmss. 698 */ 699 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 700 V_tcp_pmtud_blackhole_activated_min_mss++; 701 } 702 #endif 703 #if defined(INET6) && defined(INET) 704 else 705 #endif 706 #ifdef INET 707 if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) { 708 /* Use the sysctl tuneable blackhole MSS. */ 709 tp->t_maxopd = V_tcp_pmtud_blackhole_mss; 710 V_tcp_pmtud_blackhole_activated++; 711 } else { 712 /* Use the default MSS. */ 713 tp->t_maxopd = V_tcp_mssdflt; 714 /* 715 * Disable Path MTU Discovery when we switch to 716 * minmss. 717 */ 718 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 719 V_tcp_pmtud_blackhole_activated_min_mss++; 720 } 721 #endif 722 tp->t_maxseg = tp->t_maxopd - optlen; 723 /* 724 * Reset the slow-start flight size 725 * as it may depend on the new MSS. 726 */ 727 if (CC_ALGO(tp)->conn_init != NULL) 728 CC_ALGO(tp)->conn_init(tp->ccv); 729 } else { 730 /* 731 * If further retransmissions are still unsuccessful 732 * with a lowered MTU, maybe this isn't a blackhole and 733 * we restore the previous MSS and blackhole detection 734 * flags. 735 */ 736 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && 737 (tp->t_rxtshift > 4)) { 738 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 739 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; 740 optlen = tp->t_maxopd - tp->t_maxseg; 741 tp->t_maxopd = tp->t_pmtud_saved_maxopd; 742 tp->t_maxseg = tp->t_maxopd - optlen; 743 V_tcp_pmtud_blackhole_failed++; 744 /* 745 * Reset the slow-start flight size as it 746 * may depend on the new MSS. 747 */ 748 if (CC_ALGO(tp)->conn_init != NULL) 749 CC_ALGO(tp)->conn_init(tp->ccv); 750 } 751 } 752 } 753 754 /* 755 * Disable RFC1323 and SACK if we haven't got any response to 756 * our third SYN to work-around some broken terminal servers 757 * (most of which have hopefully been retired) that have bad VJ 758 * header compression code which trashes TCP segments containing 759 * unknown-to-them TCP options. 760 */ 761 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && 762 (tp->t_rxtshift == 3)) 763 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); 764 /* 765 * If we backed off this far, our srtt estimate is probably bogus. 766 * Clobber it so we'll take the next rtt measurement as our srtt; 767 * move the current srtt into rttvar to keep the current 768 * retransmit times until then. 769 */ 770 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 771 #ifdef INET6 772 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 773 in6_losing(tp->t_inpcb); 774 #endif 775 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 776 tp->t_srtt = 0; 777 } 778 tp->snd_nxt = tp->snd_una; 779 tp->snd_recover = tp->snd_max; 780 /* 781 * Force a segment to be sent. 782 */ 783 tp->t_flags |= TF_ACKNOW; 784 /* 785 * If timing a segment in this window, stop the timer. 786 */ 787 tp->t_rtttime = 0; 788 789 cc_cong_signal(tp, NULL, CC_RTO); 790 791 (void) tcp_output(tp); 792 793 out: 794 #ifdef TCPDEBUG 795 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 796 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 797 PRU_SLOWTIMO); 798 #endif 799 if (tp != NULL) 800 INP_WUNLOCK(inp); 801 if (headlocked) 802 INP_INFO_WUNLOCK(&V_tcbinfo); 803 CURVNET_RESTORE(); 804 } 805 806 void 807 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) 808 { 809 struct callout *t_callout; 810 timeout_t *f_callout; 811 struct inpcb *inp = tp->t_inpcb; 812 int cpu = inp_to_cpuid(inp); 813 814 #ifdef TCP_OFFLOAD 815 if (tp->t_flags & TF_TOE) 816 return; 817 #endif 818 819 if (tp->t_timers->tt_flags & TT_STOPPED) 820 return; 821 822 switch (timer_type) { 823 case TT_DELACK: 824 t_callout = &tp->t_timers->tt_delack; 825 f_callout = tcp_timer_delack; 826 break; 827 case TT_REXMT: 828 t_callout = &tp->t_timers->tt_rexmt; 829 f_callout = tcp_timer_rexmt; 830 break; 831 case TT_PERSIST: 832 t_callout = &tp->t_timers->tt_persist; 833 f_callout = tcp_timer_persist; 834 break; 835 case TT_KEEP: 836 t_callout = &tp->t_timers->tt_keep; 837 f_callout = tcp_timer_keep; 838 break; 839 case TT_2MSL: 840 t_callout = &tp->t_timers->tt_2msl; 841 f_callout = tcp_timer_2msl; 842 break; 843 default: 844 panic("tp %p bad timer_type %#x", tp, timer_type); 845 } 846 if (delta == 0) { 847 if ((tp->t_timers->tt_flags & timer_type) && 848 callout_stop(t_callout)) { 849 tp->t_timers->tt_flags &= ~timer_type; 850 } 851 } else { 852 if ((tp->t_timers->tt_flags & timer_type) == 0) { 853 tp->t_timers->tt_flags |= timer_type; 854 callout_reset_on(t_callout, delta, f_callout, tp, cpu); 855 } else { 856 /* Reset already running callout on the same CPU. */ 857 callout_reset(t_callout, delta, f_callout, tp); 858 } 859 } 860 } 861 862 int 863 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) 864 { 865 struct callout *t_callout; 866 867 switch (timer_type) { 868 case TT_DELACK: 869 t_callout = &tp->t_timers->tt_delack; 870 break; 871 case TT_REXMT: 872 t_callout = &tp->t_timers->tt_rexmt; 873 break; 874 case TT_PERSIST: 875 t_callout = &tp->t_timers->tt_persist; 876 break; 877 case TT_KEEP: 878 t_callout = &tp->t_timers->tt_keep; 879 break; 880 case TT_2MSL: 881 t_callout = &tp->t_timers->tt_2msl; 882 break; 883 default: 884 panic("tp %p bad timer_type %#x", tp, timer_type); 885 } 886 return callout_active(t_callout); 887 } 888 889 void 890 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) 891 { 892 struct callout *t_callout; 893 timeout_t *f_callout; 894 895 tp->t_timers->tt_flags |= TT_STOPPED; 896 897 switch (timer_type) { 898 case TT_DELACK: 899 t_callout = &tp->t_timers->tt_delack; 900 f_callout = tcp_timer_delack_discard; 901 break; 902 case TT_REXMT: 903 t_callout = &tp->t_timers->tt_rexmt; 904 f_callout = tcp_timer_rexmt_discard; 905 break; 906 case TT_PERSIST: 907 t_callout = &tp->t_timers->tt_persist; 908 f_callout = tcp_timer_persist_discard; 909 break; 910 case TT_KEEP: 911 t_callout = &tp->t_timers->tt_keep; 912 f_callout = tcp_timer_keep_discard; 913 break; 914 case TT_2MSL: 915 t_callout = &tp->t_timers->tt_2msl; 916 f_callout = tcp_timer_2msl_discard; 917 break; 918 default: 919 panic("tp %p bad timer_type %#x", tp, timer_type); 920 } 921 922 if (tp->t_timers->tt_flags & timer_type) { 923 if (callout_stop(t_callout)) { 924 tp->t_timers->tt_flags &= ~timer_type; 925 } else { 926 /* 927 * Can't stop the callout, defer tcpcb actual deletion 928 * to the last tcp timer discard callout. 929 * The TT_STOPPED flag will ensure that no tcp timer 930 * callouts can be restarted on our behalf, and 931 * past this point currently running callouts waiting 932 * on inp lock will return right away after the 933 * classical check for callout reset/stop events: 934 * callout_pending() || !callout_active() 935 */ 936 callout_reset(t_callout, 1, f_callout, tp); 937 } 938 } 939 } 940 941 #define ticks_to_msecs(t) (1000*(t) / hz) 942 943 void 944 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, 945 struct xtcp_timer *xtimer) 946 { 947 sbintime_t now; 948 949 bzero(xtimer, sizeof(*xtimer)); 950 if (timer == NULL) 951 return; 952 now = getsbinuptime(); 953 if (callout_active(&timer->tt_delack)) 954 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS; 955 if (callout_active(&timer->tt_rexmt)) 956 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS; 957 if (callout_active(&timer->tt_persist)) 958 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS; 959 if (callout_active(&timer->tt_keep)) 960 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS; 961 if (callout_active(&timer->tt_2msl)) 962 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS; 963 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime); 964 } 965