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_subr.c 8.2 (Berkeley) 5/24/95 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_inet.h" 36 #include "opt_inet6.h" 37 #include "opt_tcpdebug.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/callout.h> 42 #include <sys/kernel.h> 43 #include <sys/sysctl.h> 44 #include <sys/malloc.h> 45 #include <sys/mbuf.h> 46 #include <sys/priv.h> 47 #include <sys/proc.h> 48 #include <sys/socket.h> 49 #include <sys/socketvar.h> 50 #include <sys/protosw.h> 51 #include <sys/random.h> 52 #include <sys/refcount.h> 53 54 #include <vm/uma.h> 55 56 #include <net/route.h> 57 #include <net/if.h> 58 #include <net/if_var.h> 59 #include <net/vnet.h> 60 61 #include <netinet/in.h> 62 #include <netinet/in_pcb.h> 63 #include <netinet/in_systm.h> 64 #include <netinet/in_var.h> 65 #include <netinet/ip.h> 66 #include <netinet/ip_icmp.h> 67 #include <netinet/ip_var.h> 68 #ifdef INET6 69 #include <netinet/ip6.h> 70 #include <netinet6/in6_pcb.h> 71 #include <netinet6/ip6_var.h> 72 #include <netinet6/scope6_var.h> 73 #include <netinet6/nd6.h> 74 #endif 75 #include <netinet/tcp.h> 76 #include <netinet/tcp_fsm.h> 77 #include <netinet/tcp_seq.h> 78 #include <netinet/tcp_timer.h> 79 #include <netinet/tcp_var.h> 80 #ifdef INET6 81 #include <netinet6/tcp6_var.h> 82 #endif 83 #include <netinet/tcpip.h> 84 #ifdef TCPDEBUG 85 #include <netinet/tcp_debug.h> 86 #endif 87 #ifdef INET6 88 #include <netinet6/ip6protosw.h> 89 #endif 90 91 #include <machine/in_cksum.h> 92 93 #include <security/mac/mac_framework.h> 94 95 static VNET_DEFINE(uma_zone_t, tcptw_zone); 96 #define V_tcptw_zone VNET(tcptw_zone) 97 static int maxtcptw; 98 99 /* 100 * The timed wait queue contains references to each of the TCP sessions 101 * currently in the TIME_WAIT state. The queue pointers, including the 102 * queue pointers in each tcptw structure, are protected using the global 103 * timewait lock, which must be held over queue iteration and modification. 104 */ 105 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 106 #define V_twq_2msl VNET(twq_2msl) 107 108 /* Global timewait lock */ 109 static VNET_DEFINE(struct rwlock, tw_lock); 110 #define V_tw_lock VNET(tw_lock) 111 112 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 113 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 114 #define TW_RLOCK(tw) rw_rlock(&(tw)) 115 #define TW_WLOCK(tw) rw_wlock(&(tw)) 116 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 117 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 118 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 119 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 120 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 121 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 122 123 static void tcp_tw_2msl_reset(struct tcptw *, int); 124 static void tcp_tw_2msl_stop(struct tcptw *, int); 125 126 /* 127 * tw_pcbref() bumps the reference count on an tw in order to maintain 128 * stability of an tw pointer despite the tw lock being released. 129 */ 130 static void 131 tw_pcbref(struct tcptw *tw) 132 { 133 134 KASSERT(tw->tw_refcount > 0, ("%s: refcount 0", __func__)); 135 refcount_acquire(&tw->tw_refcount); 136 } 137 138 /* 139 * Drop a refcount on an tw elevated using tw_pcbref(). 140 */ 141 static int 142 tw_pcbrele(struct tcptw *tw) 143 { 144 145 KASSERT(tw->tw_refcount > 0, ("%s: refcount 0", __func__)); 146 if (!refcount_release(&tw->tw_refcount)) 147 return (0); 148 uma_zfree(V_tcptw_zone, tw); 149 return (1); 150 } 151 152 static int 153 tcptw_auto_size(void) 154 { 155 int halfrange; 156 157 /* 158 * Max out at half the ephemeral port range so that TIME_WAIT 159 * sockets don't tie up too many ephemeral ports. 160 */ 161 if (V_ipport_lastauto > V_ipport_firstauto) 162 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 163 else 164 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 165 /* Protect against goofy port ranges smaller than 32. */ 166 return (imin(imax(halfrange, 32), maxsockets / 5)); 167 } 168 169 static int 170 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 171 { 172 int error, new; 173 174 if (maxtcptw == 0) 175 new = tcptw_auto_size(); 176 else 177 new = maxtcptw; 178 error = sysctl_handle_int(oidp, &new, 0, req); 179 if (error == 0 && req->newptr) 180 if (new >= 32) { 181 maxtcptw = new; 182 uma_zone_set_max(V_tcptw_zone, maxtcptw); 183 } 184 return (error); 185 } 186 187 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 188 &maxtcptw, 0, sysctl_maxtcptw, "IU", 189 "Maximum number of compressed TCP TIME_WAIT entries"); 190 191 VNET_DEFINE(int, nolocaltimewait) = 0; 192 #define V_nolocaltimewait VNET(nolocaltimewait) 193 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW, 194 &VNET_NAME(nolocaltimewait), 0, 195 "Do not create compressed TCP TIME_WAIT entries for local connections"); 196 197 void 198 tcp_tw_zone_change(void) 199 { 200 201 if (maxtcptw == 0) 202 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 203 } 204 205 void 206 tcp_tw_init(void) 207 { 208 209 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 210 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 211 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 212 if (maxtcptw == 0) 213 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 214 else 215 uma_zone_set_max(V_tcptw_zone, maxtcptw); 216 TAILQ_INIT(&V_twq_2msl); 217 TW_LOCK_INIT(V_tw_lock, "tcptw"); 218 } 219 220 #ifdef VIMAGE 221 void 222 tcp_tw_destroy(void) 223 { 224 struct tcptw *tw; 225 226 INP_INFO_WLOCK(&V_tcbinfo); 227 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 228 tcp_twclose(tw, 0); 229 INP_INFO_WUNLOCK(&V_tcbinfo); 230 231 TW_LOCK_DESTROY(V_tw_lock); 232 uma_zdestroy(V_tcptw_zone); 233 } 234 #endif 235 236 /* 237 * Move a TCP connection into TIME_WAIT state. 238 * tcbinfo is locked. 239 * inp is locked, and is unlocked before returning. 240 */ 241 void 242 tcp_twstart(struct tcpcb *tp) 243 { 244 struct tcptw *tw; 245 struct inpcb *inp = tp->t_inpcb; 246 int acknow; 247 struct socket *so; 248 #ifdef INET6 249 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 250 #endif 251 252 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 253 INP_WLOCK_ASSERT(inp); 254 255 if (V_nolocaltimewait) { 256 int error = 0; 257 #ifdef INET6 258 if (isipv6) 259 error = in6_localaddr(&inp->in6p_faddr); 260 #endif 261 #if defined(INET6) && defined(INET) 262 else 263 #endif 264 #ifdef INET 265 error = in_localip(inp->inp_faddr); 266 #endif 267 if (error) { 268 tp = tcp_close(tp); 269 if (tp != NULL) 270 INP_WUNLOCK(inp); 271 return; 272 } 273 } 274 275 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 276 if (tw == NULL) { 277 tw = tcp_tw_2msl_reuse(); 278 if (tw == NULL) { 279 tp = tcp_close(tp); 280 if (tp != NULL) 281 INP_WUNLOCK(inp); 282 return; 283 } 284 } 285 tw->tw_inpcb = inp; 286 refcount_init(&tw->tw_refcount, 1); 287 288 /* 289 * Recover last window size sent. 290 */ 291 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 292 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 293 else 294 tw->last_win = 0; 295 296 /* 297 * Set t_recent if timestamps are used on the connection. 298 */ 299 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 300 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 301 tw->t_recent = tp->ts_recent; 302 tw->ts_offset = tp->ts_offset; 303 } else { 304 tw->t_recent = 0; 305 tw->ts_offset = 0; 306 } 307 308 tw->snd_nxt = tp->snd_nxt; 309 tw->rcv_nxt = tp->rcv_nxt; 310 tw->iss = tp->iss; 311 tw->irs = tp->irs; 312 tw->t_starttime = tp->t_starttime; 313 tw->tw_time = 0; 314 315 /* XXX 316 * If this code will 317 * be used for fin-wait-2 state also, then we may need 318 * a ts_recent from the last segment. 319 */ 320 acknow = tp->t_flags & TF_ACKNOW; 321 322 /* 323 * First, discard tcpcb state, which includes stopping its timers and 324 * freeing it. tcp_discardcb() used to also release the inpcb, but 325 * that work is now done in the caller. 326 * 327 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 328 * and might not be needed here any longer. 329 */ 330 tcp_discardcb(tp); 331 so = inp->inp_socket; 332 soisdisconnected(so); 333 tw->tw_cred = crhold(so->so_cred); 334 SOCK_LOCK(so); 335 tw->tw_so_options = so->so_options; 336 SOCK_UNLOCK(so); 337 if (acknow) 338 tcp_twrespond(tw, TH_ACK); 339 inp->inp_ppcb = tw; 340 inp->inp_flags |= INP_TIMEWAIT; 341 tcp_tw_2msl_reset(tw, 0); 342 343 /* 344 * If the inpcb owns the sole reference to the socket, then we can 345 * detach and free the socket as it is not needed in time wait. 346 */ 347 if (inp->inp_flags & INP_SOCKREF) { 348 KASSERT(so->so_state & SS_PROTOREF, 349 ("tcp_twstart: !SS_PROTOREF")); 350 inp->inp_flags &= ~INP_SOCKREF; 351 INP_WUNLOCK(inp); 352 ACCEPT_LOCK(); 353 SOCK_LOCK(so); 354 so->so_state &= ~SS_PROTOREF; 355 sofree(so); 356 } else 357 INP_WUNLOCK(inp); 358 } 359 360 /* 361 * Returns 1 if the TIME_WAIT state was killed and we should start over, 362 * looking for a pcb in the listen state. Returns 0 otherwise. 363 */ 364 int 365 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 366 struct mbuf *m, int tlen) 367 { 368 struct tcptw *tw; 369 int thflags; 370 tcp_seq seq; 371 372 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 373 INP_WLOCK_ASSERT(inp); 374 375 /* 376 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 377 * still present. This is undesirable, but temporarily necessary 378 * until we work out how to handle inpcb's who's timewait state has 379 * been removed. 380 */ 381 tw = intotw(inp); 382 if (tw == NULL) 383 goto drop; 384 385 thflags = th->th_flags; 386 387 /* 388 * NOTE: for FIN_WAIT_2 (to be added later), 389 * must validate sequence number before accepting RST 390 */ 391 392 /* 393 * If the segment contains RST: 394 * Drop the segment - see Stevens, vol. 2, p. 964 and 395 * RFC 1337. 396 */ 397 if (thflags & TH_RST) 398 goto drop; 399 400 #if 0 401 /* PAWS not needed at the moment */ 402 /* 403 * RFC 1323 PAWS: If we have a timestamp reply on this segment 404 * and it's less than ts_recent, drop it. 405 */ 406 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 407 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 408 if ((thflags & TH_ACK) == 0) 409 goto drop; 410 goto ack; 411 } 412 /* 413 * ts_recent is never updated because we never accept new segments. 414 */ 415 #endif 416 417 /* 418 * If a new connection request is received 419 * while in TIME_WAIT, drop the old connection 420 * and start over if the sequence numbers 421 * are above the previous ones. 422 */ 423 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 424 tcp_twclose(tw, 0); 425 return (1); 426 } 427 428 /* 429 * Drop the segment if it does not contain an ACK. 430 */ 431 if ((thflags & TH_ACK) == 0) 432 goto drop; 433 434 /* 435 * Reset the 2MSL timer if this is a duplicate FIN. 436 */ 437 if (thflags & TH_FIN) { 438 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 439 if (seq + 1 == tw->rcv_nxt) 440 tcp_tw_2msl_reset(tw, 1); 441 } 442 443 /* 444 * Acknowledge the segment if it has data or is not a duplicate ACK. 445 */ 446 if (thflags != TH_ACK || tlen != 0 || 447 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 448 tcp_twrespond(tw, TH_ACK); 449 drop: 450 INP_WUNLOCK(inp); 451 m_freem(m); 452 return (0); 453 } 454 455 void 456 tcp_twclose(struct tcptw *tw, int reuse) 457 { 458 struct socket *so; 459 struct inpcb *inp; 460 461 /* 462 * At this point, we are in one of two situations: 463 * 464 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 465 * all state. 466 * 467 * (2) We have a socket -- if we own a reference, release it and 468 * notify the socket layer. 469 */ 470 inp = tw->tw_inpcb; 471 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 472 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 473 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 474 INP_WLOCK_ASSERT(inp); 475 476 tw->tw_inpcb = NULL; 477 tcp_tw_2msl_stop(tw, reuse); 478 inp->inp_ppcb = NULL; 479 in_pcbdrop(inp); 480 481 so = inp->inp_socket; 482 if (so != NULL) { 483 /* 484 * If there's a socket, handle two cases: first, we own a 485 * strong reference, which we will now release, or we don't 486 * in which case another reference exists (XXXRW: think 487 * about this more), and we don't need to take action. 488 */ 489 if (inp->inp_flags & INP_SOCKREF) { 490 inp->inp_flags &= ~INP_SOCKREF; 491 INP_WUNLOCK(inp); 492 ACCEPT_LOCK(); 493 SOCK_LOCK(so); 494 KASSERT(so->so_state & SS_PROTOREF, 495 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 496 so->so_state &= ~SS_PROTOREF; 497 sofree(so); 498 } else { 499 /* 500 * If we don't own the only reference, the socket and 501 * inpcb need to be left around to be handled by 502 * tcp_usr_detach() later. 503 */ 504 INP_WUNLOCK(inp); 505 } 506 } else 507 in_pcbfree(inp); 508 TCPSTAT_INC(tcps_closed); 509 } 510 511 int 512 tcp_twrespond(struct tcptw *tw, int flags) 513 { 514 struct inpcb *inp = tw->tw_inpcb; 515 #if defined(INET6) || defined(INET) 516 struct tcphdr *th = NULL; 517 #endif 518 struct mbuf *m; 519 #ifdef INET 520 struct ip *ip = NULL; 521 #endif 522 u_int hdrlen, optlen; 523 int error = 0; /* Keep compiler happy */ 524 struct tcpopt to; 525 #ifdef INET6 526 struct ip6_hdr *ip6 = NULL; 527 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 528 #endif 529 hdrlen = 0; /* Keep compiler happy */ 530 531 INP_WLOCK_ASSERT(inp); 532 533 m = m_gethdr(M_NOWAIT, MT_DATA); 534 if (m == NULL) 535 return (ENOBUFS); 536 m->m_data += max_linkhdr; 537 538 #ifdef MAC 539 mac_inpcb_create_mbuf(inp, m); 540 #endif 541 542 #ifdef INET6 543 if (isipv6) { 544 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 545 ip6 = mtod(m, struct ip6_hdr *); 546 th = (struct tcphdr *)(ip6 + 1); 547 tcpip_fillheaders(inp, ip6, th); 548 } 549 #endif 550 #if defined(INET6) && defined(INET) 551 else 552 #endif 553 #ifdef INET 554 { 555 hdrlen = sizeof(struct tcpiphdr); 556 ip = mtod(m, struct ip *); 557 th = (struct tcphdr *)(ip + 1); 558 tcpip_fillheaders(inp, ip, th); 559 } 560 #endif 561 to.to_flags = 0; 562 563 /* 564 * Send a timestamp and echo-reply if both our side and our peer 565 * have sent timestamps in our SYN's and this is not a RST. 566 */ 567 if (tw->t_recent && flags == TH_ACK) { 568 to.to_flags |= TOF_TS; 569 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 570 to.to_tsecr = tw->t_recent; 571 } 572 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 573 574 m->m_len = hdrlen + optlen; 575 m->m_pkthdr.len = m->m_len; 576 577 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 578 579 th->th_seq = htonl(tw->snd_nxt); 580 th->th_ack = htonl(tw->rcv_nxt); 581 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 582 th->th_flags = flags; 583 th->th_win = htons(tw->last_win); 584 585 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 586 #ifdef INET6 587 if (isipv6) { 588 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 589 th->th_sum = in6_cksum_pseudo(ip6, 590 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 591 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 592 error = ip6_output(m, inp->in6p_outputopts, NULL, 593 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 594 } 595 #endif 596 #if defined(INET6) && defined(INET) 597 else 598 #endif 599 #ifdef INET 600 { 601 m->m_pkthdr.csum_flags = CSUM_TCP; 602 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 603 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 604 ip->ip_len = htons(m->m_pkthdr.len); 605 if (V_path_mtu_discovery) 606 ip->ip_off |= htons(IP_DF); 607 error = ip_output(m, inp->inp_options, NULL, 608 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 609 NULL, inp); 610 } 611 #endif 612 if (flags & TH_ACK) 613 TCPSTAT_INC(tcps_sndacks); 614 else 615 TCPSTAT_INC(tcps_sndctrl); 616 TCPSTAT_INC(tcps_sndtotal); 617 return (error); 618 } 619 620 static void 621 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 622 { 623 624 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 625 INP_WLOCK_ASSERT(tw->tw_inpcb); 626 627 TW_WLOCK(V_tw_lock); 628 if (rearm) 629 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 630 tw->tw_time = ticks + 2 * tcp_msl; 631 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 632 TW_WUNLOCK(V_tw_lock); 633 } 634 635 static void 636 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 637 { 638 639 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 640 641 TW_WLOCK(V_tw_lock); 642 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 643 crfree(tw->tw_cred); 644 tw->tw_cred = NULL; 645 TW_WUNLOCK(V_tw_lock); 646 647 if (!reuse) 648 tw_pcbrele(tw); 649 } 650 651 struct tcptw * 652 tcp_tw_2msl_reuse(void) 653 { 654 struct tcptw *tw; 655 656 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 657 658 TW_WLOCK(V_tw_lock); 659 tw = TAILQ_FIRST(&V_twq_2msl); 660 if (tw == NULL) { 661 TW_WUNLOCK(V_tw_lock); 662 return NULL; 663 } 664 TW_WUNLOCK(V_tw_lock); 665 666 INP_WLOCK(tw->tw_inpcb); 667 tcp_twclose(tw, 1); 668 669 return (tw); 670 } 671 672 void 673 tcp_tw_2msl_scan(void) 674 { 675 struct tcptw *tw; 676 677 for (;;) { 678 TW_RLOCK(V_tw_lock); 679 tw = TAILQ_FIRST(&V_twq_2msl); 680 if (tw == NULL || tw->tw_time - ticks > 0) { 681 TW_RUNLOCK(V_tw_lock); 682 break; 683 } 684 tw_pcbref(tw); 685 TW_RUNLOCK(V_tw_lock); 686 687 /* Close timewait state */ 688 if (INP_INFO_TRY_WLOCK(&V_tcbinfo)) { 689 if (tw_pcbrele(tw)) { 690 INP_INFO_WUNLOCK(&V_tcbinfo); 691 continue; 692 } 693 694 KASSERT(tw->tw_inpcb != NULL, 695 ("%s: tw->tw_inpcb == NULL", __func__)); 696 INP_WLOCK(tw->tw_inpcb); 697 tcp_twclose(tw, 0); 698 INP_INFO_WUNLOCK(&V_tcbinfo); 699 } else { 700 /* INP_INFO lock is busy; continue later. */ 701 tw_pcbrele(tw); 702 break; 703 } 704 } 705 } 706