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 if (!callout_reset(&tp->t_timers->tt_2msl, 360 TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) { 361 tp->t_timers->tt_flags &= ~TT_2MSL_RST; 362 } 363 } else 364 tp = tcp_close(tp); 365 } 366 367 #ifdef TCPDEBUG 368 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 369 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 370 PRU_SLOWTIMO); 371 #endif 372 if (tp != NULL) 373 INP_WUNLOCK(inp); 374 INP_INFO_RUNLOCK(&V_tcbinfo); 375 CURVNET_RESTORE(); 376 } 377 378 void 379 tcp_timer_keep(void *xtp) 380 { 381 struct tcpcb *tp = xtp; 382 struct tcptemp *t_template; 383 struct inpcb *inp; 384 CURVNET_SET(tp->t_vnet); 385 #ifdef TCPDEBUG 386 int ostate; 387 388 ostate = tp->t_state; 389 #endif 390 INP_INFO_RLOCK(&V_tcbinfo); 391 inp = tp->t_inpcb; 392 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 393 INP_WLOCK(inp); 394 if (callout_pending(&tp->t_timers->tt_keep) || 395 !callout_active(&tp->t_timers->tt_keep)) { 396 INP_WUNLOCK(inp); 397 INP_INFO_RUNLOCK(&V_tcbinfo); 398 CURVNET_RESTORE(); 399 return; 400 } 401 callout_deactivate(&tp->t_timers->tt_keep); 402 if ((inp->inp_flags & INP_DROPPED) != 0) { 403 INP_WUNLOCK(inp); 404 INP_INFO_RUNLOCK(&V_tcbinfo); 405 CURVNET_RESTORE(); 406 return; 407 } 408 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 409 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 410 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0, 411 ("%s: tp %p keep callout should be running", __func__, tp)); 412 /* 413 * Keep-alive timer went off; send something 414 * or drop connection if idle for too long. 415 */ 416 TCPSTAT_INC(tcps_keeptimeo); 417 if (tp->t_state < TCPS_ESTABLISHED) 418 goto dropit; 419 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && 420 tp->t_state <= TCPS_CLOSING) { 421 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) 422 goto dropit; 423 /* 424 * Send a packet designed to force a response 425 * if the peer is up and reachable: 426 * either an ACK if the connection is still alive, 427 * or an RST if the peer has closed the connection 428 * due to timeout or reboot. 429 * Using sequence number tp->snd_una-1 430 * causes the transmitted zero-length segment 431 * to lie outside the receive window; 432 * by the protocol spec, this requires the 433 * correspondent TCP to respond. 434 */ 435 TCPSTAT_INC(tcps_keepprobe); 436 t_template = tcpip_maketemplate(inp); 437 if (t_template) { 438 tcp_respond(tp, t_template->tt_ipgen, 439 &t_template->tt_t, (struct mbuf *)NULL, 440 tp->rcv_nxt, tp->snd_una - 1, 0); 441 free(t_template, M_TEMP); 442 } 443 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), 444 tcp_timer_keep, tp)) { 445 tp->t_timers->tt_flags &= ~TT_KEEP_RST; 446 } 447 } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), 448 tcp_timer_keep, tp)) { 449 tp->t_timers->tt_flags &= ~TT_KEEP_RST; 450 } 451 452 #ifdef TCPDEBUG 453 if (inp->inp_socket->so_options & SO_DEBUG) 454 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 455 PRU_SLOWTIMO); 456 #endif 457 INP_WUNLOCK(inp); 458 INP_INFO_RUNLOCK(&V_tcbinfo); 459 CURVNET_RESTORE(); 460 return; 461 462 dropit: 463 TCPSTAT_INC(tcps_keepdrops); 464 tp = tcp_drop(tp, ETIMEDOUT); 465 466 #ifdef TCPDEBUG 467 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 468 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 469 PRU_SLOWTIMO); 470 #endif 471 if (tp != NULL) 472 INP_WUNLOCK(tp->t_inpcb); 473 INP_INFO_RUNLOCK(&V_tcbinfo); 474 CURVNET_RESTORE(); 475 } 476 477 void 478 tcp_timer_persist(void *xtp) 479 { 480 struct tcpcb *tp = xtp; 481 struct inpcb *inp; 482 CURVNET_SET(tp->t_vnet); 483 #ifdef TCPDEBUG 484 int ostate; 485 486 ostate = tp->t_state; 487 #endif 488 INP_INFO_RLOCK(&V_tcbinfo); 489 inp = tp->t_inpcb; 490 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 491 INP_WLOCK(inp); 492 if (callout_pending(&tp->t_timers->tt_persist) || 493 !callout_active(&tp->t_timers->tt_persist)) { 494 INP_WUNLOCK(inp); 495 INP_INFO_RUNLOCK(&V_tcbinfo); 496 CURVNET_RESTORE(); 497 return; 498 } 499 callout_deactivate(&tp->t_timers->tt_persist); 500 if ((inp->inp_flags & INP_DROPPED) != 0) { 501 INP_WUNLOCK(inp); 502 INP_INFO_RUNLOCK(&V_tcbinfo); 503 CURVNET_RESTORE(); 504 return; 505 } 506 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 507 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 508 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0, 509 ("%s: tp %p persist callout should be running", __func__, tp)); 510 /* 511 * Persistance timer into zero window. 512 * Force a byte to be output, if possible. 513 */ 514 TCPSTAT_INC(tcps_persisttimeo); 515 /* 516 * Hack: if the peer is dead/unreachable, we do not 517 * time out if the window is closed. After a full 518 * backoff, drop the connection if the idle time 519 * (no responses to probes) reaches the maximum 520 * backoff that we would use if retransmitting. 521 */ 522 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 523 (ticks - tp->t_rcvtime >= tcp_maxpersistidle || 524 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { 525 TCPSTAT_INC(tcps_persistdrop); 526 tp = tcp_drop(tp, ETIMEDOUT); 527 goto out; 528 } 529 /* 530 * If the user has closed the socket then drop a persisting 531 * connection after a much reduced timeout. 532 */ 533 if (tp->t_state > TCPS_CLOSE_WAIT && 534 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { 535 TCPSTAT_INC(tcps_persistdrop); 536 tp = tcp_drop(tp, ETIMEDOUT); 537 goto out; 538 } 539 tcp_setpersist(tp); 540 tp->t_flags |= TF_FORCEDATA; 541 (void) tcp_output(tp); 542 tp->t_flags &= ~TF_FORCEDATA; 543 544 out: 545 #ifdef TCPDEBUG 546 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 547 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); 548 #endif 549 if (tp != NULL) 550 INP_WUNLOCK(inp); 551 INP_INFO_RUNLOCK(&V_tcbinfo); 552 CURVNET_RESTORE(); 553 } 554 555 void 556 tcp_timer_rexmt(void * xtp) 557 { 558 struct tcpcb *tp = xtp; 559 CURVNET_SET(tp->t_vnet); 560 int rexmt; 561 int headlocked; 562 struct inpcb *inp; 563 #ifdef TCPDEBUG 564 int ostate; 565 566 ostate = tp->t_state; 567 #endif 568 569 INP_INFO_RLOCK(&V_tcbinfo); 570 inp = tp->t_inpcb; 571 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); 572 INP_WLOCK(inp); 573 if (callout_pending(&tp->t_timers->tt_rexmt) || 574 !callout_active(&tp->t_timers->tt_rexmt)) { 575 INP_WUNLOCK(inp); 576 INP_INFO_RUNLOCK(&V_tcbinfo); 577 CURVNET_RESTORE(); 578 return; 579 } 580 callout_deactivate(&tp->t_timers->tt_rexmt); 581 if ((inp->inp_flags & INP_DROPPED) != 0) { 582 INP_WUNLOCK(inp); 583 INP_INFO_RUNLOCK(&V_tcbinfo); 584 CURVNET_RESTORE(); 585 return; 586 } 587 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, 588 ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); 589 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0, 590 ("%s: tp %p rexmt callout should be running", __func__, tp)); 591 tcp_free_sackholes(tp); 592 /* 593 * Retransmission timer went off. Message has not 594 * been acked within retransmit interval. Back off 595 * to a longer retransmit interval and retransmit one segment. 596 */ 597 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 598 tp->t_rxtshift = TCP_MAXRXTSHIFT; 599 TCPSTAT_INC(tcps_timeoutdrop); 600 601 tp = tcp_drop(tp, tp->t_softerror ? 602 tp->t_softerror : ETIMEDOUT); 603 headlocked = 1; 604 goto out; 605 } 606 INP_INFO_RUNLOCK(&V_tcbinfo); 607 headlocked = 0; 608 if (tp->t_state == TCPS_SYN_SENT) { 609 /* 610 * If the SYN was retransmitted, indicate CWND to be 611 * limited to 1 segment in cc_conn_init(). 612 */ 613 tp->snd_cwnd = 1; 614 } else if (tp->t_rxtshift == 1) { 615 /* 616 * first retransmit; record ssthresh and cwnd so they can 617 * be recovered if this turns out to be a "bad" retransmit. 618 * A retransmit is considered "bad" if an ACK for this 619 * segment is received within RTT/2 interval; the assumption 620 * here is that the ACK was already in flight. See 621 * "On Estimating End-to-End Network Path Properties" by 622 * Allman and Paxson for more details. 623 */ 624 tp->snd_cwnd_prev = tp->snd_cwnd; 625 tp->snd_ssthresh_prev = tp->snd_ssthresh; 626 tp->snd_recover_prev = tp->snd_recover; 627 if (IN_FASTRECOVERY(tp->t_flags)) 628 tp->t_flags |= TF_WASFRECOVERY; 629 else 630 tp->t_flags &= ~TF_WASFRECOVERY; 631 if (IN_CONGRECOVERY(tp->t_flags)) 632 tp->t_flags |= TF_WASCRECOVERY; 633 else 634 tp->t_flags &= ~TF_WASCRECOVERY; 635 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); 636 tp->t_flags |= TF_PREVVALID; 637 } else 638 tp->t_flags &= ~TF_PREVVALID; 639 TCPSTAT_INC(tcps_rexmttimeo); 640 if (tp->t_state == TCPS_SYN_SENT) 641 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; 642 else 643 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 644 TCPT_RANGESET(tp->t_rxtcur, rexmt, 645 tp->t_rttmin, TCPTV_REXMTMAX); 646 647 /* 648 * We enter the path for PLMTUD if connection is established or, if 649 * connection is FIN_WAIT_1 status, reason for the last is that if 650 * amount of data we send is very small, we could send it in couple of 651 * packets and process straight to FIN. In that case we won't catch 652 * ESTABLISHED state. 653 */ 654 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED)) 655 || (tp->t_state == TCPS_FIN_WAIT_1))) { 656 int optlen; 657 #ifdef INET6 658 int isipv6; 659 #endif 660 661 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == 662 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && 663 (tp->t_rxtshift <= 2)) { 664 /* 665 * Enter Path MTU Black-hole Detection mechanism: 666 * - Disable Path MTU Discovery (IP "DF" bit). 667 * - Reduce MTU to lower value than what we 668 * negotiated with peer. 669 */ 670 /* Record that we may have found a black hole. */ 671 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; 672 673 /* Keep track of previous MSS. */ 674 optlen = tp->t_maxopd - tp->t_maxseg; 675 tp->t_pmtud_saved_maxopd = tp->t_maxopd; 676 677 /* 678 * Reduce the MSS to blackhole value or to the default 679 * in an attempt to retransmit. 680 */ 681 #ifdef INET6 682 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0; 683 if (isipv6 && 684 tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) { 685 /* Use the sysctl tuneable blackhole MSS. */ 686 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss; 687 V_tcp_pmtud_blackhole_activated++; 688 } else if (isipv6) { 689 /* Use the default MSS. */ 690 tp->t_maxopd = V_tcp_v6mssdflt; 691 /* 692 * Disable Path MTU Discovery when we switch to 693 * minmss. 694 */ 695 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 696 V_tcp_pmtud_blackhole_activated_min_mss++; 697 } 698 #endif 699 #if defined(INET6) && defined(INET) 700 else 701 #endif 702 #ifdef INET 703 if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) { 704 /* Use the sysctl tuneable blackhole MSS. */ 705 tp->t_maxopd = V_tcp_pmtud_blackhole_mss; 706 V_tcp_pmtud_blackhole_activated++; 707 } else { 708 /* Use the default MSS. */ 709 tp->t_maxopd = V_tcp_mssdflt; 710 /* 711 * Disable Path MTU Discovery when we switch to 712 * minmss. 713 */ 714 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 715 V_tcp_pmtud_blackhole_activated_min_mss++; 716 } 717 #endif 718 tp->t_maxseg = tp->t_maxopd - optlen; 719 /* 720 * Reset the slow-start flight size 721 * as it may depend on the new MSS. 722 */ 723 if (CC_ALGO(tp)->conn_init != NULL) 724 CC_ALGO(tp)->conn_init(tp->ccv); 725 } else { 726 /* 727 * If further retransmissions are still unsuccessful 728 * with a lowered MTU, maybe this isn't a blackhole and 729 * we restore the previous MSS and blackhole detection 730 * flags. 731 */ 732 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && 733 (tp->t_rxtshift > 4)) { 734 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 735 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; 736 optlen = tp->t_maxopd - tp->t_maxseg; 737 tp->t_maxopd = tp->t_pmtud_saved_maxopd; 738 tp->t_maxseg = tp->t_maxopd - optlen; 739 V_tcp_pmtud_blackhole_failed++; 740 /* 741 * Reset the slow-start flight size as it 742 * may depend on the new MSS. 743 */ 744 if (CC_ALGO(tp)->conn_init != NULL) 745 CC_ALGO(tp)->conn_init(tp->ccv); 746 } 747 } 748 } 749 750 /* 751 * Disable RFC1323 and SACK if we haven't got any response to 752 * our third SYN to work-around some broken terminal servers 753 * (most of which have hopefully been retired) that have bad VJ 754 * header compression code which trashes TCP segments containing 755 * unknown-to-them TCP options. 756 */ 757 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && 758 (tp->t_rxtshift == 3)) 759 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); 760 /* 761 * If we backed off this far, our srtt estimate is probably bogus. 762 * Clobber it so we'll take the next rtt measurement as our srtt; 763 * move the current srtt into rttvar to keep the current 764 * retransmit times until then. 765 */ 766 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 767 #ifdef INET6 768 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 769 in6_losing(tp->t_inpcb); 770 #endif 771 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 772 tp->t_srtt = 0; 773 } 774 tp->snd_nxt = tp->snd_una; 775 tp->snd_recover = tp->snd_max; 776 /* 777 * Force a segment to be sent. 778 */ 779 tp->t_flags |= TF_ACKNOW; 780 /* 781 * If timing a segment in this window, stop the timer. 782 */ 783 tp->t_rtttime = 0; 784 785 cc_cong_signal(tp, NULL, CC_RTO); 786 787 (void) tcp_output(tp); 788 789 out: 790 #ifdef TCPDEBUG 791 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 792 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, 793 PRU_SLOWTIMO); 794 #endif 795 if (tp != NULL) 796 INP_WUNLOCK(inp); 797 if (headlocked) 798 INP_INFO_RUNLOCK(&V_tcbinfo); 799 CURVNET_RESTORE(); 800 } 801 802 void 803 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) 804 { 805 struct callout *t_callout; 806 timeout_t *f_callout; 807 struct inpcb *inp = tp->t_inpcb; 808 int cpu = inp_to_cpuid(inp); 809 uint32_t f_reset; 810 811 #ifdef TCP_OFFLOAD 812 if (tp->t_flags & TF_TOE) 813 return; 814 #endif 815 816 if (tp->t_timers->tt_flags & TT_STOPPED) 817 return; 818 819 switch (timer_type) { 820 case TT_DELACK: 821 t_callout = &tp->t_timers->tt_delack; 822 f_callout = tcp_timer_delack; 823 f_reset = TT_DELACK_RST; 824 break; 825 case TT_REXMT: 826 t_callout = &tp->t_timers->tt_rexmt; 827 f_callout = tcp_timer_rexmt; 828 f_reset = TT_REXMT_RST; 829 break; 830 case TT_PERSIST: 831 t_callout = &tp->t_timers->tt_persist; 832 f_callout = tcp_timer_persist; 833 f_reset = TT_PERSIST_RST; 834 break; 835 case TT_KEEP: 836 t_callout = &tp->t_timers->tt_keep; 837 f_callout = tcp_timer_keep; 838 f_reset = TT_KEEP_RST; 839 break; 840 case TT_2MSL: 841 t_callout = &tp->t_timers->tt_2msl; 842 f_callout = tcp_timer_2msl; 843 f_reset = TT_2MSL_RST; 844 break; 845 default: 846 panic("tp %p bad timer_type %#x", tp, timer_type); 847 } 848 if (delta == 0) { 849 if ((tp->t_timers->tt_flags & timer_type) && 850 callout_stop(t_callout) && 851 (tp->t_timers->tt_flags & f_reset)) { 852 tp->t_timers->tt_flags &= ~(timer_type | f_reset); 853 } 854 } else { 855 if ((tp->t_timers->tt_flags & timer_type) == 0) { 856 tp->t_timers->tt_flags |= (timer_type | f_reset); 857 callout_reset_on(t_callout, delta, f_callout, tp, cpu); 858 } else { 859 /* Reset already running callout on the same CPU. */ 860 if (!callout_reset(t_callout, delta, f_callout, tp)) { 861 /* 862 * Callout not cancelled, consider it as not 863 * properly restarted. */ 864 tp->t_timers->tt_flags &= ~f_reset; 865 } 866 } 867 } 868 } 869 870 int 871 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) 872 { 873 struct callout *t_callout; 874 875 switch (timer_type) { 876 case TT_DELACK: 877 t_callout = &tp->t_timers->tt_delack; 878 break; 879 case TT_REXMT: 880 t_callout = &tp->t_timers->tt_rexmt; 881 break; 882 case TT_PERSIST: 883 t_callout = &tp->t_timers->tt_persist; 884 break; 885 case TT_KEEP: 886 t_callout = &tp->t_timers->tt_keep; 887 break; 888 case TT_2MSL: 889 t_callout = &tp->t_timers->tt_2msl; 890 break; 891 default: 892 panic("tp %p bad timer_type %#x", tp, timer_type); 893 } 894 return callout_active(t_callout); 895 } 896 897 void 898 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) 899 { 900 struct callout *t_callout; 901 timeout_t *f_callout; 902 uint32_t f_reset; 903 904 tp->t_timers->tt_flags |= TT_STOPPED; 905 906 switch (timer_type) { 907 case TT_DELACK: 908 t_callout = &tp->t_timers->tt_delack; 909 f_callout = tcp_timer_delack_discard; 910 f_reset = TT_DELACK_RST; 911 break; 912 case TT_REXMT: 913 t_callout = &tp->t_timers->tt_rexmt; 914 f_callout = tcp_timer_rexmt_discard; 915 f_reset = TT_REXMT_RST; 916 break; 917 case TT_PERSIST: 918 t_callout = &tp->t_timers->tt_persist; 919 f_callout = tcp_timer_persist_discard; 920 f_reset = TT_PERSIST_RST; 921 break; 922 case TT_KEEP: 923 t_callout = &tp->t_timers->tt_keep; 924 f_callout = tcp_timer_keep_discard; 925 f_reset = TT_KEEP_RST; 926 break; 927 case TT_2MSL: 928 t_callout = &tp->t_timers->tt_2msl; 929 f_callout = tcp_timer_2msl_discard; 930 f_reset = TT_2MSL_RST; 931 break; 932 default: 933 panic("tp %p bad timer_type %#x", tp, timer_type); 934 } 935 936 if (tp->t_timers->tt_flags & timer_type) { 937 if (callout_stop(t_callout) && 938 (tp->t_timers->tt_flags & f_reset)) { 939 tp->t_timers->tt_flags &= ~(timer_type | f_reset); 940 } else { 941 /* 942 * Can't stop the callout, defer tcpcb actual deletion 943 * to the last tcp timer discard callout. 944 * The TT_STOPPED flag will ensure that no tcp timer 945 * callouts can be restarted on our behalf, and 946 * past this point currently running callouts waiting 947 * on inp lock will return right away after the 948 * classical check for callout reset/stop events: 949 * callout_pending() || !callout_active() 950 */ 951 callout_reset(t_callout, 1, f_callout, tp); 952 } 953 } 954 } 955 956 #define ticks_to_msecs(t) (1000*(t) / hz) 957 958 void 959 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, 960 struct xtcp_timer *xtimer) 961 { 962 sbintime_t now; 963 964 bzero(xtimer, sizeof(*xtimer)); 965 if (timer == NULL) 966 return; 967 now = getsbinuptime(); 968 if (callout_active(&timer->tt_delack)) 969 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS; 970 if (callout_active(&timer->tt_rexmt)) 971 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS; 972 if (callout_active(&timer->tt_persist)) 973 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS; 974 if (callout_active(&timer->tt_keep)) 975 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS; 976 if (callout_active(&timer->tt_2msl)) 977 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS; 978 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime); 979 } 980