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 static int tcp_twrespond(struct tcptw *, int); 126 127 /* 128 * tw_pcbref() bumps the reference count on an tw in order to maintain 129 * stability of an tw pointer despite the tw lock being released. 130 */ 131 static void 132 tw_pcbref(struct tcptw *tw) 133 { 134 135 KASSERT(tw->tw_refcount > 0, ("%s: refcount 0", __func__)); 136 refcount_acquire(&tw->tw_refcount); 137 } 138 139 /* 140 * Drop a refcount on an tw elevated using tw_pcbref(). 141 */ 142 static int 143 tw_pcbrele(struct tcptw *tw) 144 { 145 146 KASSERT(tw->tw_refcount > 0, ("%s: refcount 0", __func__)); 147 if (!refcount_release(&tw->tw_refcount)) 148 return (0); 149 uma_zfree(V_tcptw_zone, tw); 150 return (1); 151 } 152 153 static int 154 tcptw_auto_size(void) 155 { 156 int halfrange; 157 158 /* 159 * Max out at half the ephemeral port range so that TIME_WAIT 160 * sockets don't tie up too many ephemeral ports. 161 */ 162 if (V_ipport_lastauto > V_ipport_firstauto) 163 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 164 else 165 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 166 /* Protect against goofy port ranges smaller than 32. */ 167 return (imin(imax(halfrange, 32), maxsockets / 5)); 168 } 169 170 static int 171 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 172 { 173 int error, new; 174 175 if (maxtcptw == 0) 176 new = tcptw_auto_size(); 177 else 178 new = maxtcptw; 179 error = sysctl_handle_int(oidp, &new, 0, req); 180 if (error == 0 && req->newptr) 181 if (new >= 32) { 182 maxtcptw = new; 183 uma_zone_set_max(V_tcptw_zone, maxtcptw); 184 } 185 return (error); 186 } 187 188 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 189 &maxtcptw, 0, sysctl_maxtcptw, "IU", 190 "Maximum number of compressed TCP TIME_WAIT entries"); 191 192 VNET_DEFINE(int, nolocaltimewait) = 0; 193 #define V_nolocaltimewait VNET(nolocaltimewait) 194 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW, 195 &VNET_NAME(nolocaltimewait), 0, 196 "Do not create compressed TCP TIME_WAIT entries for local connections"); 197 198 void 199 tcp_tw_zone_change(void) 200 { 201 202 if (maxtcptw == 0) 203 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 204 } 205 206 void 207 tcp_tw_init(void) 208 { 209 210 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 211 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 212 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 213 if (maxtcptw == 0) 214 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 215 else 216 uma_zone_set_max(V_tcptw_zone, maxtcptw); 217 TAILQ_INIT(&V_twq_2msl); 218 TW_LOCK_INIT(V_tw_lock, "tcptw"); 219 } 220 221 #ifdef VIMAGE 222 void 223 tcp_tw_destroy(void) 224 { 225 struct tcptw *tw; 226 227 INP_INFO_WLOCK(&V_tcbinfo); 228 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 229 tcp_twclose(tw, 0); 230 INP_INFO_WUNLOCK(&V_tcbinfo); 231 232 TW_LOCK_DESTROY(V_tw_lock); 233 uma_zdestroy(V_tcptw_zone); 234 } 235 #endif 236 237 /* 238 * Move a TCP connection into TIME_WAIT state. 239 * tcbinfo is locked. 240 * inp is locked, and is unlocked before returning. 241 */ 242 void 243 tcp_twstart(struct tcpcb *tp) 244 { 245 struct tcptw *tw; 246 struct inpcb *inp = tp->t_inpcb; 247 int acknow; 248 struct socket *so; 249 #ifdef INET6 250 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 251 #endif 252 253 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 254 INP_WLOCK_ASSERT(inp); 255 256 if (V_nolocaltimewait) { 257 int error = 0; 258 #ifdef INET6 259 if (isipv6) 260 error = in6_localaddr(&inp->in6p_faddr); 261 #endif 262 #if defined(INET6) && defined(INET) 263 else 264 #endif 265 #ifdef INET 266 error = in_localip(inp->inp_faddr); 267 #endif 268 if (error) { 269 tp = tcp_close(tp); 270 if (tp != NULL) 271 INP_WUNLOCK(inp); 272 return; 273 } 274 } 275 276 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 277 if (tw == NULL) { 278 /* 279 * Reached limit on total number of TIMEWAIT connections 280 * allowed. Remove a connection from TIMEWAIT queue in LRU 281 * fashion to make room for this connection. 282 */ 283 tw = tcp_tw_2msl_reuse(); 284 if (tw == NULL) { 285 tp = tcp_close(tp); 286 if (tp != NULL) 287 INP_WUNLOCK(inp); 288 return; 289 } 290 } 291 tw->tw_inpcb = inp; 292 refcount_init(&tw->tw_refcount, 1); 293 294 /* 295 * Recover last window size sent. 296 */ 297 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 298 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 299 else 300 tw->last_win = 0; 301 302 /* 303 * Set t_recent if timestamps are used on the connection. 304 */ 305 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 306 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 307 tw->t_recent = tp->ts_recent; 308 tw->ts_offset = tp->ts_offset; 309 } else { 310 tw->t_recent = 0; 311 tw->ts_offset = 0; 312 } 313 314 tw->snd_nxt = tp->snd_nxt; 315 tw->rcv_nxt = tp->rcv_nxt; 316 tw->iss = tp->iss; 317 tw->irs = tp->irs; 318 tw->t_starttime = tp->t_starttime; 319 tw->tw_time = 0; 320 321 /* XXX 322 * If this code will 323 * be used for fin-wait-2 state also, then we may need 324 * a ts_recent from the last segment. 325 */ 326 acknow = tp->t_flags & TF_ACKNOW; 327 328 /* 329 * First, discard tcpcb state, which includes stopping its timers and 330 * freeing it. tcp_discardcb() used to also release the inpcb, but 331 * that work is now done in the caller. 332 * 333 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 334 * and might not be needed here any longer. 335 */ 336 tcp_discardcb(tp); 337 so = inp->inp_socket; 338 soisdisconnected(so); 339 tw->tw_cred = crhold(so->so_cred); 340 SOCK_LOCK(so); 341 tw->tw_so_options = so->so_options; 342 SOCK_UNLOCK(so); 343 if (acknow) 344 tcp_twrespond(tw, TH_ACK); 345 inp->inp_ppcb = tw; 346 inp->inp_flags |= INP_TIMEWAIT; 347 tcp_tw_2msl_reset(tw, 0); 348 349 /* 350 * If the inpcb owns the sole reference to the socket, then we can 351 * detach and free the socket as it is not needed in time wait. 352 */ 353 if (inp->inp_flags & INP_SOCKREF) { 354 KASSERT(so->so_state & SS_PROTOREF, 355 ("tcp_twstart: !SS_PROTOREF")); 356 inp->inp_flags &= ~INP_SOCKREF; 357 INP_WUNLOCK(inp); 358 ACCEPT_LOCK(); 359 SOCK_LOCK(so); 360 so->so_state &= ~SS_PROTOREF; 361 sofree(so); 362 } else 363 INP_WUNLOCK(inp); 364 } 365 366 /* 367 * Returns 1 if the TIME_WAIT state was killed and we should start over, 368 * looking for a pcb in the listen state. Returns 0 otherwise. 369 */ 370 int 371 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 372 struct mbuf *m, int tlen) 373 { 374 struct tcptw *tw; 375 int thflags; 376 tcp_seq seq; 377 378 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 379 INP_WLOCK_ASSERT(inp); 380 381 /* 382 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 383 * still present. This is undesirable, but temporarily necessary 384 * until we work out how to handle inpcb's who's timewait state has 385 * been removed. 386 */ 387 tw = intotw(inp); 388 if (tw == NULL) 389 goto drop; 390 391 thflags = th->th_flags; 392 393 /* 394 * NOTE: for FIN_WAIT_2 (to be added later), 395 * must validate sequence number before accepting RST 396 */ 397 398 /* 399 * If the segment contains RST: 400 * Drop the segment - see Stevens, vol. 2, p. 964 and 401 * RFC 1337. 402 */ 403 if (thflags & TH_RST) 404 goto drop; 405 406 #if 0 407 /* PAWS not needed at the moment */ 408 /* 409 * RFC 1323 PAWS: If we have a timestamp reply on this segment 410 * and it's less than ts_recent, drop it. 411 */ 412 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 413 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 414 if ((thflags & TH_ACK) == 0) 415 goto drop; 416 goto ack; 417 } 418 /* 419 * ts_recent is never updated because we never accept new segments. 420 */ 421 #endif 422 423 /* 424 * If a new connection request is received 425 * while in TIME_WAIT, drop the old connection 426 * and start over if the sequence numbers 427 * are above the previous ones. 428 */ 429 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 430 tcp_twclose(tw, 0); 431 return (1); 432 } 433 434 /* 435 * Drop the segment if it does not contain an ACK. 436 */ 437 if ((thflags & TH_ACK) == 0) 438 goto drop; 439 440 /* 441 * Reset the 2MSL timer if this is a duplicate FIN. 442 */ 443 if (thflags & TH_FIN) { 444 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 445 if (seq + 1 == tw->rcv_nxt) 446 tcp_tw_2msl_reset(tw, 1); 447 } 448 449 /* 450 * Acknowledge the segment if it has data or is not a duplicate ACK. 451 */ 452 if (thflags != TH_ACK || tlen != 0 || 453 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 454 tcp_twrespond(tw, TH_ACK); 455 drop: 456 INP_WUNLOCK(inp); 457 m_freem(m); 458 return (0); 459 } 460 461 void 462 tcp_twclose(struct tcptw *tw, int reuse) 463 { 464 struct socket *so; 465 struct inpcb *inp; 466 467 /* 468 * At this point, we are in one of two situations: 469 * 470 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 471 * all state. 472 * 473 * (2) We have a socket -- if we own a reference, release it and 474 * notify the socket layer. 475 */ 476 inp = tw->tw_inpcb; 477 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 478 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 479 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 480 INP_WLOCK_ASSERT(inp); 481 482 tw->tw_inpcb = NULL; 483 tcp_tw_2msl_stop(tw, reuse); 484 inp->inp_ppcb = NULL; 485 in_pcbdrop(inp); 486 487 so = inp->inp_socket; 488 if (so != NULL) { 489 /* 490 * If there's a socket, handle two cases: first, we own a 491 * strong reference, which we will now release, or we don't 492 * in which case another reference exists (XXXRW: think 493 * about this more), and we don't need to take action. 494 */ 495 if (inp->inp_flags & INP_SOCKREF) { 496 inp->inp_flags &= ~INP_SOCKREF; 497 INP_WUNLOCK(inp); 498 ACCEPT_LOCK(); 499 SOCK_LOCK(so); 500 KASSERT(so->so_state & SS_PROTOREF, 501 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 502 so->so_state &= ~SS_PROTOREF; 503 sofree(so); 504 } else { 505 /* 506 * If we don't own the only reference, the socket and 507 * inpcb need to be left around to be handled by 508 * tcp_usr_detach() later. 509 */ 510 INP_WUNLOCK(inp); 511 } 512 } else 513 in_pcbfree(inp); 514 TCPSTAT_INC(tcps_closed); 515 } 516 517 static int 518 tcp_twrespond(struct tcptw *tw, int flags) 519 { 520 struct inpcb *inp = tw->tw_inpcb; 521 #if defined(INET6) || defined(INET) 522 struct tcphdr *th = NULL; 523 #endif 524 struct mbuf *m; 525 #ifdef INET 526 struct ip *ip = NULL; 527 #endif 528 u_int hdrlen, optlen; 529 int error = 0; /* Keep compiler happy */ 530 struct tcpopt to; 531 #ifdef INET6 532 struct ip6_hdr *ip6 = NULL; 533 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 534 #endif 535 hdrlen = 0; /* Keep compiler happy */ 536 537 INP_WLOCK_ASSERT(inp); 538 539 m = m_gethdr(M_NOWAIT, MT_DATA); 540 if (m == NULL) 541 return (ENOBUFS); 542 m->m_data += max_linkhdr; 543 544 #ifdef MAC 545 mac_inpcb_create_mbuf(inp, m); 546 #endif 547 548 #ifdef INET6 549 if (isipv6) { 550 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 551 ip6 = mtod(m, struct ip6_hdr *); 552 th = (struct tcphdr *)(ip6 + 1); 553 tcpip_fillheaders(inp, ip6, th); 554 } 555 #endif 556 #if defined(INET6) && defined(INET) 557 else 558 #endif 559 #ifdef INET 560 { 561 hdrlen = sizeof(struct tcpiphdr); 562 ip = mtod(m, struct ip *); 563 th = (struct tcphdr *)(ip + 1); 564 tcpip_fillheaders(inp, ip, th); 565 } 566 #endif 567 to.to_flags = 0; 568 569 /* 570 * Send a timestamp and echo-reply if both our side and our peer 571 * have sent timestamps in our SYN's and this is not a RST. 572 */ 573 if (tw->t_recent && flags == TH_ACK) { 574 to.to_flags |= TOF_TS; 575 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 576 to.to_tsecr = tw->t_recent; 577 } 578 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 579 580 m->m_len = hdrlen + optlen; 581 m->m_pkthdr.len = m->m_len; 582 583 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 584 585 th->th_seq = htonl(tw->snd_nxt); 586 th->th_ack = htonl(tw->rcv_nxt); 587 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 588 th->th_flags = flags; 589 th->th_win = htons(tw->last_win); 590 591 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 592 #ifdef INET6 593 if (isipv6) { 594 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 595 th->th_sum = in6_cksum_pseudo(ip6, 596 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 597 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 598 error = ip6_output(m, inp->in6p_outputopts, NULL, 599 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 600 } 601 #endif 602 #if defined(INET6) && defined(INET) 603 else 604 #endif 605 #ifdef INET 606 { 607 m->m_pkthdr.csum_flags = CSUM_TCP; 608 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 609 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 610 ip->ip_len = htons(m->m_pkthdr.len); 611 if (V_path_mtu_discovery) 612 ip->ip_off |= htons(IP_DF); 613 error = ip_output(m, inp->inp_options, NULL, 614 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 615 NULL, inp); 616 } 617 #endif 618 if (flags & TH_ACK) 619 TCPSTAT_INC(tcps_sndacks); 620 else 621 TCPSTAT_INC(tcps_sndctrl); 622 TCPSTAT_INC(tcps_sndtotal); 623 return (error); 624 } 625 626 static void 627 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 628 { 629 630 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 631 INP_WLOCK_ASSERT(tw->tw_inpcb); 632 633 TW_WLOCK(V_tw_lock); 634 if (rearm) 635 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 636 tw->tw_time = ticks + 2 * tcp_msl; 637 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 638 TW_WUNLOCK(V_tw_lock); 639 } 640 641 static void 642 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 643 { 644 645 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 646 647 TW_WLOCK(V_tw_lock); 648 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 649 crfree(tw->tw_cred); 650 tw->tw_cred = NULL; 651 TW_WUNLOCK(V_tw_lock); 652 653 if (!reuse) 654 tw_pcbrele(tw); 655 } 656 657 struct tcptw * 658 tcp_tw_2msl_reuse(void) 659 { 660 struct tcptw *tw; 661 662 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 663 664 TW_WLOCK(V_tw_lock); 665 tw = TAILQ_FIRST(&V_twq_2msl); 666 if (tw == NULL) { 667 TW_WUNLOCK(V_tw_lock); 668 return NULL; 669 } 670 TW_WUNLOCK(V_tw_lock); 671 672 INP_WLOCK(tw->tw_inpcb); 673 tcp_twclose(tw, 1); 674 675 return (tw); 676 } 677 678 void 679 tcp_tw_2msl_scan(void) 680 { 681 struct tcptw *tw; 682 683 for (;;) { 684 TW_RLOCK(V_tw_lock); 685 tw = TAILQ_FIRST(&V_twq_2msl); 686 if (tw == NULL || tw->tw_time - ticks > 0) { 687 TW_RUNLOCK(V_tw_lock); 688 break; 689 } 690 tw_pcbref(tw); 691 TW_RUNLOCK(V_tw_lock); 692 693 /* Close timewait state */ 694 if (INP_INFO_TRY_WLOCK(&V_tcbinfo)) { 695 if (tw_pcbrele(tw)) { 696 INP_INFO_WUNLOCK(&V_tcbinfo); 697 continue; 698 } 699 700 KASSERT(tw->tw_inpcb != NULL, 701 ("%s: tw->tw_inpcb == NULL", __func__)); 702 INP_WLOCK(tw->tw_inpcb); 703 tcp_twclose(tw, 0); 704 INP_INFO_WUNLOCK(&V_tcbinfo); 705 } else { 706 /* INP_INFO lock is busy; continue later. */ 707 tw_pcbrele(tw); 708 break; 709 } 710 } 711 } 712