tcp_timer.c revision 1.72
1 /* $NetBSD: tcp_timer.c,v 1.72 2005/07/19 17:00:02 christos Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /*- 33 * Copyright (c) 1997, 1998, 2001, 2005 The NetBSD Foundation, Inc. 34 * All rights reserved. 35 * 36 * This code is derived from software contributed to The NetBSD Foundation 37 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 38 * Facility, NASA Ames Research Center. 39 * This code is derived from software contributed to The NetBSD Foundation 40 * by Charles M. Hannum. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. All advertising materials mentioning features or use of this software 51 * must display the following acknowledgement: 52 * This product includes software developed by the NetBSD 53 * Foundation, Inc. and its contributors. 54 * 4. Neither the name of The NetBSD Foundation nor the names of its 55 * contributors may be used to endorse or promote products derived 56 * from this software without specific prior written permission. 57 * 58 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 59 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 60 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 61 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 62 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 63 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 64 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 65 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 66 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 67 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 68 * POSSIBILITY OF SUCH DAMAGE. 69 */ 70 71 /* 72 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 73 * The Regents of the University of California. All rights reserved. 74 * 75 * Redistribution and use in source and binary forms, with or without 76 * modification, are permitted provided that the following conditions 77 * are met: 78 * 1. Redistributions of source code must retain the above copyright 79 * notice, this list of conditions and the following disclaimer. 80 * 2. Redistributions in binary form must reproduce the above copyright 81 * notice, this list of conditions and the following disclaimer in the 82 * documentation and/or other materials provided with the distribution. 83 * 3. Neither the name of the University nor the names of its contributors 84 * may be used to endorse or promote products derived from this software 85 * without specific prior written permission. 86 * 87 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 88 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 89 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 90 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 91 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 92 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 93 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 94 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 95 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 96 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 97 * SUCH DAMAGE. 98 * 99 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 100 */ 101 102 #include <sys/cdefs.h> 103 __KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.72 2005/07/19 17:00:02 christos Exp $"); 104 105 #include "opt_inet.h" 106 #include "opt_tcp_debug.h" 107 108 #include <sys/param.h> 109 #include <sys/systm.h> 110 #include <sys/malloc.h> 111 #include <sys/mbuf.h> 112 #include <sys/socket.h> 113 #include <sys/socketvar.h> 114 #include <sys/protosw.h> 115 #include <sys/errno.h> 116 #include <sys/kernel.h> 117 118 #include <net/if.h> 119 #include <net/route.h> 120 121 #include <netinet/in.h> 122 #include <netinet/in_systm.h> 123 #include <netinet/ip.h> 124 #include <netinet/in_pcb.h> 125 #include <netinet/ip_var.h> 126 #include <netinet/ip_icmp.h> 127 128 #ifdef INET6 129 #ifndef INET 130 #include <netinet/in.h> 131 #endif 132 #include <netinet/ip6.h> 133 #include <netinet6/in6_pcb.h> 134 #endif 135 136 #include <netinet/tcp.h> 137 #include <netinet/tcp_fsm.h> 138 #include <netinet/tcp_seq.h> 139 #include <netinet/tcp_timer.h> 140 #include <netinet/tcp_var.h> 141 #include <netinet/tcpip.h> 142 #ifdef TCP_DEBUG 143 #include <netinet/tcp_debug.h> 144 #endif 145 146 /* 147 * Various tunable timer parameters. These are initialized in tcp_init(), 148 * unless they are patched. 149 */ 150 int tcp_keepidle = 0; 151 int tcp_keepintvl = 0; 152 int tcp_keepcnt = 0; /* max idle probes */ 153 int tcp_maxpersistidle = 0; /* max idle time in persist */ 154 int tcp_maxidle; /* computed in tcp_slowtimo() */ 155 156 /* 157 * Time to delay the ACK. This is initialized in tcp_init(), unless 158 * its patched. 159 */ 160 int tcp_delack_ticks = 0; 161 162 void tcp_timer_rexmt(void *); 163 void tcp_timer_persist(void *); 164 void tcp_timer_keep(void *); 165 void tcp_timer_2msl(void *); 166 167 const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS] = { 168 tcp_timer_rexmt, 169 tcp_timer_persist, 170 tcp_timer_keep, 171 tcp_timer_2msl, 172 }; 173 174 /* 175 * Timer state initialization, called from tcp_init(). 176 */ 177 void 178 tcp_timer_init(void) 179 { 180 181 if (tcp_keepidle == 0) 182 tcp_keepidle = TCPTV_KEEP_IDLE; 183 184 if (tcp_keepintvl == 0) 185 tcp_keepintvl = TCPTV_KEEPINTVL; 186 187 if (tcp_keepcnt == 0) 188 tcp_keepcnt = TCPTV_KEEPCNT; 189 190 if (tcp_maxpersistidle == 0) 191 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 192 193 if (tcp_delack_ticks == 0) 194 tcp_delack_ticks = TCP_DELACK_TICKS; 195 } 196 197 /* 198 * Return how many timers are currently being invoked. 199 */ 200 int 201 tcp_timers_invoking(struct tcpcb *tp) 202 { 203 int i; 204 int count = 0; 205 206 for (i = 0; i < TCPT_NTIMERS; i++) 207 if (callout_invoking(&tp->t_timer[i])) 208 count++; 209 if (callout_invoking(&tp->t_delack_ch)) 210 count++; 211 212 return count; 213 } 214 215 /* 216 * Callout to process delayed ACKs for a TCPCB. 217 */ 218 void 219 tcp_delack(void *arg) 220 { 221 struct tcpcb *tp = arg; 222 int s; 223 224 /* 225 * If tcp_output() wasn't able to transmit the ACK 226 * for whatever reason, it will restart the delayed 227 * ACK callout. 228 */ 229 230 s = splsoftnet(); 231 callout_ack(&tp->t_delack_ch); 232 if (tcp_isdead(tp)) { 233 splx(s); 234 return; 235 } 236 237 tp->t_flags |= TF_ACKNOW; 238 (void) tcp_output(tp); 239 splx(s); 240 } 241 242 /* 243 * Tcp protocol timeout routine called every 500 ms. 244 * Updates the timers in all active tcb's and 245 * causes finite state machine actions if timers expire. 246 */ 247 void 248 tcp_slowtimo(void) 249 { 250 int s; 251 252 s = splsoftnet(); 253 tcp_maxidle = tcp_keepcnt * tcp_keepintvl; 254 tcp_iss_seq += TCP_ISSINCR; /* increment iss */ 255 tcp_now++; /* for timestamps */ 256 splx(s); 257 } 258 259 /* 260 * Cancel all timers for TCP tp. 261 */ 262 void 263 tcp_canceltimers(struct tcpcb *tp) 264 { 265 int i; 266 267 for (i = 0; i < TCPT_NTIMERS; i++) 268 TCP_TIMER_DISARM(tp, i); 269 } 270 271 const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 272 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; 273 274 const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */ 275 276 /* 277 * TCP timer processing. 278 */ 279 280 void 281 tcp_timer_rexmt(void *arg) 282 { 283 struct tcpcb *tp = arg; 284 uint32_t rto; 285 int s; 286 #ifdef TCP_DEBUG 287 struct socket *so = NULL; 288 short ostate; 289 #endif 290 291 s = splsoftnet(); 292 callout_ack(&tp->t_timer[TCPT_REXMT]); 293 if (tcp_isdead(tp)) { 294 splx(s); 295 return; 296 } 297 298 if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb && 299 SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) && 300 SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) { 301 extern struct sockaddr_in icmpsrc; 302 struct icmp icmp; 303 304 tp->t_flags &= ~TF_PMTUD_PEND; 305 306 /* XXX create fake icmp message with relevant entries */ 307 icmp.icmp_nextmtu = tp->t_pmtud_nextmtu; 308 icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len; 309 icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl; 310 icmpsrc.sin_addr = tp->t_inpcb->inp_faddr; 311 icmp_mtudisc(&icmp, icmpsrc.sin_addr); 312 313 /* 314 * Notify all connections to the same peer about 315 * new mss and trigger retransmit. 316 */ 317 in_pcbnotifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE, 318 tcp_mtudisc); 319 splx(s); 320 return; 321 } 322 #ifdef TCP_DEBUG 323 #ifdef INET 324 if (tp->t_inpcb) 325 so = tp->t_inpcb->inp_socket; 326 #endif 327 #ifdef INET6 328 if (tp->t_in6pcb) 329 so = tp->t_in6pcb->in6p_socket; 330 #endif 331 ostate = tp->t_state; 332 #endif /* TCP_DEBUG */ 333 334 /* 335 * Clear the SACK scoreboard, reset FACK estimate. 336 */ 337 tcp_free_sackholes(tp); 338 tp->snd_fack = tp->snd_una; 339 340 /* 341 * Retransmission timer went off. Message has not 342 * been acked within retransmit interval. Back off 343 * to a longer retransmit interval and retransmit one segment. 344 */ 345 346 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 347 tp->t_rxtshift = TCP_MAXRXTSHIFT; 348 tcpstat.tcps_timeoutdrop++; 349 tp = tcp_drop(tp, tp->t_softerror ? 350 tp->t_softerror : ETIMEDOUT); 351 goto out; 352 } 353 tcpstat.tcps_rexmttimeo++; 354 rto = TCP_REXMTVAL(tp); 355 if (rto < tp->t_rttmin) 356 rto = tp->t_rttmin; 357 TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift], 358 tp->t_rttmin, TCPTV_REXMTMAX); 359 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 360 361 /* 362 * If we are losing and we are trying path MTU discovery, 363 * try turning it off. This will avoid black holes in 364 * the network which suppress or fail to send "packet 365 * too big" ICMP messages. We should ideally do 366 * lots more sophisticated searching to find the right 367 * value here... 368 */ 369 if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) { 370 tcpstat.tcps_pmtublackhole++; 371 372 #ifdef INET 373 /* try turning PMTUD off */ 374 if (tp->t_inpcb) 375 tp->t_mtudisc = 0; 376 #endif 377 #ifdef INET6 378 /* try using IPv6 minimum MTU */ 379 if (tp->t_in6pcb) 380 tp->t_mtudisc = 0; 381 #endif 382 383 /* XXX: more sophisticated Black hole recovery code? */ 384 } 385 386 /* 387 * If losing, let the lower level know and try for 388 * a better route. Also, if we backed off this far, 389 * our srtt estimate is probably bogus. Clobber it 390 * so we'll take the next rtt measurement as our srtt; 391 * move the current srtt into rttvar to keep the current 392 * retransmit times until then. 393 */ 394 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 395 #ifdef INET 396 if (tp->t_inpcb) 397 in_losing(tp->t_inpcb); 398 #endif 399 #ifdef INET6 400 if (tp->t_in6pcb) 401 in6_losing(tp->t_in6pcb); 402 #endif 403 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 404 tp->t_srtt = 0; 405 } 406 tp->snd_nxt = tp->snd_una; 407 tp->snd_high = tp->snd_max; 408 /* 409 * If timing a segment in this window, stop the timer. 410 */ 411 tp->t_rtttime = 0; 412 /* 413 * Remember if we are retransmitting a SYN, because if 414 * we do, set the initial congestion window must be set 415 * to 1 segment. 416 */ 417 if (tp->t_state == TCPS_SYN_SENT) 418 tp->t_flags |= TF_SYN_REXMT; 419 /* 420 * Close the congestion window down to one segment 421 * (we'll open it by one segment for each ack we get). 422 * Since we probably have a window's worth of unacked 423 * data accumulated, this "slow start" keeps us from 424 * dumping all that data as back-to-back packets (which 425 * might overwhelm an intermediate gateway). 426 * 427 * There are two phases to the opening: Initially we 428 * open by one mss on each ack. This makes the window 429 * size increase exponentially with time. If the 430 * window is larger than the path can handle, this 431 * exponential growth results in dropped packet(s) 432 * almost immediately. To get more time between 433 * drops but still "push" the network to take advantage 434 * of improving conditions, we switch from exponential 435 * to linear window opening at some threshhold size. 436 * For a threshhold, we use half the current window 437 * size, truncated to a multiple of the mss. 438 * 439 * (the minimum cwnd that will give us exponential 440 * growth is 2 mss. We don't allow the threshhold 441 * to go below this.) 442 */ 443 { 444 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_segsz; 445 if (win < 2) 446 win = 2; 447 /* Loss Window MUST be one segment. */ 448 tp->snd_cwnd = tp->t_segsz; 449 tp->snd_ssthresh = win * tp->t_segsz; 450 tp->t_partialacks = -1; 451 tp->t_dupacks = 0; 452 } 453 (void) tcp_output(tp); 454 455 out: 456 #ifdef TCP_DEBUG 457 if (tp && so->so_options & SO_DEBUG) 458 tcp_trace(TA_USER, ostate, tp, NULL, 459 PRU_SLOWTIMO | (TCPT_REXMT << 8)); 460 #endif 461 splx(s); 462 } 463 464 void 465 tcp_timer_persist(void *arg) 466 { 467 struct tcpcb *tp = arg; 468 uint32_t rto; 469 int s; 470 #ifdef TCP_DEBUG 471 struct socket *so = NULL; 472 short ostate; 473 #endif 474 475 s = splsoftnet(); 476 callout_ack(&tp->t_timer[TCPT_PERSIST]); 477 if (tcp_isdead(tp)) { 478 splx(s); 479 return; 480 } 481 482 #ifdef TCP_DEBUG 483 #ifdef INET 484 if (tp->t_inpcb) 485 so = tp->t_inpcb->inp_socket; 486 #endif 487 #ifdef INET6 488 if (tp->t_in6pcb) 489 so = tp->t_in6pcb->in6p_socket; 490 #endif 491 492 ostate = tp->t_state; 493 #endif /* TCP_DEBUG */ 494 495 /* 496 * Persistance timer into zero window. 497 * Force a byte to be output, if possible. 498 */ 499 500 /* 501 * Hack: if the peer is dead/unreachable, we do not 502 * time out if the window is closed. After a full 503 * backoff, drop the connection if the idle time 504 * (no responses to probes) reaches the maximum 505 * backoff that we would use if retransmitting. 506 */ 507 rto = TCP_REXMTVAL(tp); 508 if (rto < tp->t_rttmin) 509 rto = tp->t_rttmin; 510 if (tp->t_rxtshift == TCP_MAXRXTSHIFT && 511 ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle || 512 (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) { 513 tcpstat.tcps_persistdrops++; 514 tp = tcp_drop(tp, ETIMEDOUT); 515 goto out; 516 } 517 tcpstat.tcps_persisttimeo++; 518 tcp_setpersist(tp); 519 tp->t_force = 1; 520 (void) tcp_output(tp); 521 tp->t_force = 0; 522 523 out: 524 #ifdef TCP_DEBUG 525 if (tp && so->so_options & SO_DEBUG) 526 tcp_trace(TA_USER, ostate, tp, NULL, 527 PRU_SLOWTIMO | (TCPT_PERSIST << 8)); 528 #endif 529 splx(s); 530 } 531 532 void 533 tcp_timer_keep(void *arg) 534 { 535 struct tcpcb *tp = arg; 536 struct socket *so = NULL; /* Quell compiler warning */ 537 int s; 538 #ifdef TCP_DEBUG 539 short ostate; 540 #endif 541 542 s = splsoftnet(); 543 callout_ack(&tp->t_timer[TCPT_KEEP]); 544 if (tcp_isdead(tp)) { 545 splx(s); 546 return; 547 } 548 549 #ifdef TCP_DEBUG 550 ostate = tp->t_state; 551 #endif /* TCP_DEBUG */ 552 553 /* 554 * Keep-alive timer went off; send something 555 * or drop connection if idle for too long. 556 */ 557 558 tcpstat.tcps_keeptimeo++; 559 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 560 goto dropit; 561 #ifdef INET 562 if (tp->t_inpcb) 563 so = tp->t_inpcb->inp_socket; 564 #endif 565 #ifdef INET6 566 if (tp->t_in6pcb) 567 so = tp->t_in6pcb->in6p_socket; 568 #endif 569 if (so->so_options & SO_KEEPALIVE && 570 tp->t_state <= TCPS_CLOSE_WAIT) { 571 if ((tcp_maxidle > 0) && 572 ((tcp_now - tp->t_rcvtime) >= 573 tcp_keepidle + tcp_maxidle)) 574 goto dropit; 575 /* 576 * Send a packet designed to force a response 577 * if the peer is up and reachable: 578 * either an ACK if the connection is still alive, 579 * or an RST if the peer has closed the connection 580 * due to timeout or reboot. 581 * Using sequence number tp->snd_una-1 582 * causes the transmitted zero-length segment 583 * to lie outside the receive window; 584 * by the protocol spec, this requires the 585 * correspondent TCP to respond. 586 */ 587 tcpstat.tcps_keepprobe++; 588 if (tcp_compat_42) { 589 /* 590 * The keepalive packet must have nonzero 591 * length to get a 4.2 host to respond. 592 */ 593 (void)tcp_respond(tp, tp->t_template, 594 (struct mbuf *)NULL, NULL, tp->rcv_nxt - 1, 595 tp->snd_una - 1, 0); 596 } else { 597 (void)tcp_respond(tp, tp->t_template, 598 (struct mbuf *)NULL, NULL, tp->rcv_nxt, 599 tp->snd_una - 1, 0); 600 } 601 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepintvl); 602 } else 603 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 604 605 #ifdef TCP_DEBUG 606 if (tp && so->so_options & SO_DEBUG) 607 tcp_trace(TA_USER, ostate, tp, NULL, 608 PRU_SLOWTIMO | (TCPT_KEEP << 8)); 609 #endif 610 splx(s); 611 return; 612 613 dropit: 614 tcpstat.tcps_keepdrops++; 615 (void) tcp_drop(tp, ETIMEDOUT); 616 splx(s); 617 } 618 619 void 620 tcp_timer_2msl(void *arg) 621 { 622 struct tcpcb *tp = arg; 623 int s; 624 #ifdef TCP_DEBUG 625 struct socket *so = NULL; 626 short ostate; 627 #endif 628 629 s = splsoftnet(); 630 callout_ack(&tp->t_timer[TCPT_2MSL]); 631 if (tcp_isdead(tp)) { 632 splx(s); 633 return; 634 } 635 636 /* 637 * 2 MSL timeout went off, clear the SACK scoreboard, reset 638 * the FACK estimate. 639 */ 640 tcp_free_sackholes(tp); 641 tp->snd_fack = tp->snd_una; 642 643 #ifdef TCP_DEBUG 644 #ifdef INET 645 if (tp->t_inpcb) 646 so = tp->t_inpcb->inp_socket; 647 #endif 648 #ifdef INET6 649 if (tp->t_in6pcb) 650 so = tp->t_in6pcb->in6p_socket; 651 #endif 652 653 ostate = tp->t_state; 654 #endif /* TCP_DEBUG */ 655 656 /* 657 * 2 MSL timeout in shutdown went off. If we're closed but 658 * still waiting for peer to close and connection has been idle 659 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 660 * control block. Otherwise, check again in a bit. 661 */ 662 if (tp->t_state != TCPS_TIME_WAIT && 663 ((tcp_maxidle == 0) || ((tcp_now - tp->t_rcvtime) <= tcp_maxidle))) 664 TCP_TIMER_ARM(tp, TCPT_2MSL, tcp_keepintvl); 665 else 666 tp = tcp_close(tp); 667 668 #ifdef TCP_DEBUG 669 if (tp && so->so_options & SO_DEBUG) 670 tcp_trace(TA_USER, ostate, tp, NULL, 671 PRU_SLOWTIMO | (TCPT_2MSL << 8)); 672 #endif 673 splx(s); 674 } 675
Indexes created Sat Sep 20 22:09:52 GMT 2025