tcp_usrreq.c revision 46381
1/* 2 * Copyright (c) 1982, 1986, 1988, 1993 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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * From: @(#)tcp_usrreq.c 8.2 (Berkeley) 1/3/94 34 * $Id: tcp_usrreq.c,v 1.42 1999/04/28 11:37:50 phk Exp $ 35 */ 36 37#include "opt_tcpdebug.h" 38 39#include <sys/param.h> 40#include <sys/systm.h> 41#include <sys/kernel.h> 42#include <sys/sysctl.h> 43#include <sys/mbuf.h> 44#include <sys/socket.h> 45#include <sys/socketvar.h> 46#include <sys/protosw.h> 47 48#include <net/if.h> 49#include <net/route.h> 50 51#include <netinet/in.h> 52#include <netinet/in_systm.h> 53#include <netinet/in_pcb.h> 54#include <netinet/in_var.h> 55#include <netinet/ip_var.h> 56#include <netinet/tcp.h> 57#include <netinet/tcp_fsm.h> 58#include <netinet/tcp_seq.h> 59#include <netinet/tcp_timer.h> 60#include <netinet/tcp_var.h> 61#include <netinet/tcpip.h> 62#ifdef TCPDEBUG 63#include <netinet/tcp_debug.h> 64#endif 65 66/* 67 * TCP protocol interface to socket abstraction. 68 */ 69extern char *tcpstates[]; /* XXX ??? */ 70 71static int tcp_attach __P((struct socket *, struct proc *)); 72static int tcp_connect __P((struct tcpcb *, struct sockaddr *, 73 struct proc *)); 74static struct tcpcb * 75 tcp_disconnect __P((struct tcpcb *)); 76static struct tcpcb * 77 tcp_usrclosed __P((struct tcpcb *)); 78 79#ifdef TCPDEBUG 80#define TCPDEBUG0 int ostate 81#define TCPDEBUG1() ostate = tp ? tp->t_state : 0 82#define TCPDEBUG2(req) if (tp && (so->so_options & SO_DEBUG)) \ 83 tcp_trace(TA_USER, ostate, tp, 0, req) 84#else 85#define TCPDEBUG0 86#define TCPDEBUG1() 87#define TCPDEBUG2(req) 88#endif 89 90/* 91 * TCP attaches to socket via pru_attach(), reserving space, 92 * and an internet control block. 93 */ 94static int 95tcp_usr_attach(struct socket *so, int proto, struct proc *p) 96{ 97 int s = splnet(); 98 int error; 99 struct inpcb *inp = sotoinpcb(so); 100 struct tcpcb *tp = 0; 101 TCPDEBUG0; 102 103 TCPDEBUG1(); 104 if (inp) { 105 error = EISCONN; 106 goto out; 107 } 108 109 error = tcp_attach(so, p); 110 if (error) 111 goto out; 112 113 if ((so->so_options & SO_LINGER) && so->so_linger == 0) 114 so->so_linger = TCP_LINGERTIME; 115 tp = sototcpcb(so); 116out: 117 TCPDEBUG2(PRU_ATTACH); 118 splx(s); 119 return error; 120} 121 122/* 123 * pru_detach() detaches the TCP protocol from the socket. 124 * If the protocol state is non-embryonic, then can't 125 * do this directly: have to initiate a pru_disconnect(), 126 * which may finish later; embryonic TCB's can just 127 * be discarded here. 128 */ 129static int 130tcp_usr_detach(struct socket *so) 131{ 132 int s = splnet(); 133 int error = 0; 134 struct inpcb *inp = sotoinpcb(so); 135 struct tcpcb *tp; 136 TCPDEBUG0; 137 138 if (inp == 0) { 139 splx(s); 140 return EINVAL; /* XXX */ 141 } 142 tp = intotcpcb(inp); 143 TCPDEBUG1(); 144 tp = tcp_disconnect(tp); 145 146 TCPDEBUG2(PRU_DETACH); 147 splx(s); 148 return error; 149} 150 151#define COMMON_START() TCPDEBUG0; \ 152 do { \ 153 if (inp == 0) { \ 154 splx(s); \ 155 return EINVAL; \ 156 } \ 157 tp = intotcpcb(inp); \ 158 TCPDEBUG1(); \ 159 } while(0) 160 161#define COMMON_END(req) out: TCPDEBUG2(req); splx(s); return error; goto out 162 163 164/* 165 * Give the socket an address. 166 */ 167static int 168tcp_usr_bind(struct socket *so, struct sockaddr *nam, struct proc *p) 169{ 170 int s = splnet(); 171 int error = 0; 172 struct inpcb *inp = sotoinpcb(so); 173 struct tcpcb *tp; 174 struct sockaddr_in *sinp; 175 176 COMMON_START(); 177 178 /* 179 * Must check for multicast addresses and disallow binding 180 * to them. 181 */ 182 sinp = (struct sockaddr_in *)nam; 183 if (sinp->sin_family == AF_INET && 184 IN_MULTICAST(ntohl(sinp->sin_addr.s_addr))) { 185 error = EAFNOSUPPORT; 186 goto out; 187 } 188 error = in_pcbbind(inp, nam, p); 189 if (error) 190 goto out; 191 COMMON_END(PRU_BIND); 192 193} 194 195/* 196 * Prepare to accept connections. 197 */ 198static int 199tcp_usr_listen(struct socket *so, struct proc *p) 200{ 201 int s = splnet(); 202 int error = 0; 203 struct inpcb *inp = sotoinpcb(so); 204 struct tcpcb *tp; 205 206 COMMON_START(); 207 if (inp->inp_lport == 0) 208 error = in_pcbbind(inp, (struct sockaddr *)0, p); 209 if (error == 0) 210 tp->t_state = TCPS_LISTEN; 211 COMMON_END(PRU_LISTEN); 212} 213 214/* 215 * Initiate connection to peer. 216 * Create a template for use in transmissions on this connection. 217 * Enter SYN_SENT state, and mark socket as connecting. 218 * Start keep-alive timer, and seed output sequence space. 219 * Send initial segment on connection. 220 */ 221static int 222tcp_usr_connect(struct socket *so, struct sockaddr *nam, struct proc *p) 223{ 224 int s = splnet(); 225 int error = 0; 226 struct inpcb *inp = sotoinpcb(so); 227 struct tcpcb *tp; 228 struct sockaddr_in *sinp; 229 230 COMMON_START(); 231 232 /* 233 * Must disallow TCP ``connections'' to multicast addresses. 234 */ 235 sinp = (struct sockaddr_in *)nam; 236 if (sinp->sin_family == AF_INET 237 && IN_MULTICAST(ntohl(sinp->sin_addr.s_addr))) { 238 error = EAFNOSUPPORT; 239 goto out; 240 } 241 242 prison_remote_ip(p, 0, &sinp->sin_addr.s_addr); 243 244 if ((error = tcp_connect(tp, nam, p)) != 0) 245 goto out; 246 error = tcp_output(tp); 247 COMMON_END(PRU_CONNECT); 248} 249 250/* 251 * Initiate disconnect from peer. 252 * If connection never passed embryonic stage, just drop; 253 * else if don't need to let data drain, then can just drop anyways, 254 * else have to begin TCP shutdown process: mark socket disconnecting, 255 * drain unread data, state switch to reflect user close, and 256 * send segment (e.g. FIN) to peer. Socket will be really disconnected 257 * when peer sends FIN and acks ours. 258 * 259 * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB. 260 */ 261static int 262tcp_usr_disconnect(struct socket *so) 263{ 264 int s = splnet(); 265 int error = 0; 266 struct inpcb *inp = sotoinpcb(so); 267 struct tcpcb *tp; 268 269 COMMON_START(); 270 tp = tcp_disconnect(tp); 271 COMMON_END(PRU_DISCONNECT); 272} 273 274/* 275 * Accept a connection. Essentially all the work is 276 * done at higher levels; just return the address 277 * of the peer, storing through addr. 278 */ 279static int 280tcp_usr_accept(struct socket *so, struct sockaddr **nam) 281{ 282 int s = splnet(); 283 int error = 0; 284 struct inpcb *inp = sotoinpcb(so); 285 struct tcpcb *tp; 286 287 COMMON_START(); 288 in_setpeeraddr(so, nam); 289 COMMON_END(PRU_ACCEPT); 290} 291 292/* 293 * Mark the connection as being incapable of further output. 294 */ 295static int 296tcp_usr_shutdown(struct socket *so) 297{ 298 int s = splnet(); 299 int error = 0; 300 struct inpcb *inp = sotoinpcb(so); 301 struct tcpcb *tp; 302 303 COMMON_START(); 304 socantsendmore(so); 305 tp = tcp_usrclosed(tp); 306 if (tp) 307 error = tcp_output(tp); 308 COMMON_END(PRU_SHUTDOWN); 309} 310 311/* 312 * After a receive, possibly send window update to peer. 313 */ 314static int 315tcp_usr_rcvd(struct socket *so, int flags) 316{ 317 int s = splnet(); 318 int error = 0; 319 struct inpcb *inp = sotoinpcb(so); 320 struct tcpcb *tp; 321 322 COMMON_START(); 323 tcp_output(tp); 324 COMMON_END(PRU_RCVD); 325} 326 327/* 328 * Do a send by putting data in output queue and updating urgent 329 * marker if URG set. Possibly send more data. 330 */ 331static int 332tcp_usr_send(struct socket *so, int flags, struct mbuf *m, 333 struct sockaddr *nam, struct mbuf *control, struct proc *p) 334{ 335 int s = splnet(); 336 int error = 0; 337 struct inpcb *inp = sotoinpcb(so); 338 struct tcpcb *tp; 339 340 COMMON_START(); 341 if (control && control->m_len) { 342 m_freem(control); /* XXX shouldn't caller do this??? */ 343 if (m) 344 m_freem(m); 345 error = EINVAL; 346 goto out; 347 } 348 349 if(!(flags & PRUS_OOB)) { 350 sbappend(&so->so_snd, m); 351 if (nam && tp->t_state < TCPS_SYN_SENT) { 352 /* 353 * Do implied connect if not yet connected, 354 * initialize window to default value, and 355 * initialize maxseg/maxopd using peer's cached 356 * MSS. 357 */ 358 error = tcp_connect(tp, nam, p); 359 if (error) 360 goto out; 361 tp->snd_wnd = TTCP_CLIENT_SND_WND; 362 tcp_mss(tp, -1); 363 } 364 365 if (flags & PRUS_EOF) { 366 /* 367 * Close the send side of the connection after 368 * the data is sent. 369 */ 370 socantsendmore(so); 371 tp = tcp_usrclosed(tp); 372 } 373 if (tp != NULL) { 374 if (flags & PRUS_MORETOCOME) 375 tp->t_flags |= TF_MORETOCOME; 376 error = tcp_output(tp); 377 if (flags & PRUS_MORETOCOME) 378 tp->t_flags &= ~TF_MORETOCOME; 379 } 380 } else { 381 if (sbspace(&so->so_snd) < -512) { 382 m_freem(m); 383 error = ENOBUFS; 384 goto out; 385 } 386 /* 387 * According to RFC961 (Assigned Protocols), 388 * the urgent pointer points to the last octet 389 * of urgent data. We continue, however, 390 * to consider it to indicate the first octet 391 * of data past the urgent section. 392 * Otherwise, snd_up should be one lower. 393 */ 394 sbappend(&so->so_snd, m); 395 if (nam && tp->t_state < TCPS_SYN_SENT) { 396 /* 397 * Do implied connect if not yet connected, 398 * initialize window to default value, and 399 * initialize maxseg/maxopd using peer's cached 400 * MSS. 401 */ 402 error = tcp_connect(tp, nam, p); 403 if (error) 404 goto out; 405 tp->snd_wnd = TTCP_CLIENT_SND_WND; 406 tcp_mss(tp, -1); 407 } 408 tp->snd_up = tp->snd_una + so->so_snd.sb_cc; 409 tp->t_force = 1; 410 error = tcp_output(tp); 411 tp->t_force = 0; 412 } 413 COMMON_END((flags & PRUS_OOB) ? PRU_SENDOOB : 414 ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND)); 415} 416 417/* 418 * Abort the TCP. 419 */ 420static int 421tcp_usr_abort(struct socket *so) 422{ 423 int s = splnet(); 424 int error = 0; 425 struct inpcb *inp = sotoinpcb(so); 426 struct tcpcb *tp; 427 428 COMMON_START(); 429 tp = tcp_drop(tp, ECONNABORTED); 430 COMMON_END(PRU_ABORT); 431} 432 433/* 434 * Receive out-of-band data. 435 */ 436static int 437tcp_usr_rcvoob(struct socket *so, struct mbuf *m, int flags) 438{ 439 int s = splnet(); 440 int error = 0; 441 struct inpcb *inp = sotoinpcb(so); 442 struct tcpcb *tp; 443 444 COMMON_START(); 445 if ((so->so_oobmark == 0 && 446 (so->so_state & SS_RCVATMARK) == 0) || 447 so->so_options & SO_OOBINLINE || 448 tp->t_oobflags & TCPOOB_HADDATA) { 449 error = EINVAL; 450 goto out; 451 } 452 if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) { 453 error = EWOULDBLOCK; 454 goto out; 455 } 456 m->m_len = 1; 457 *mtod(m, caddr_t) = tp->t_iobc; 458 if ((flags & MSG_PEEK) == 0) 459 tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA); 460 COMMON_END(PRU_RCVOOB); 461} 462 463/* xxx - should be const */ 464struct pr_usrreqs tcp_usrreqs = { 465 tcp_usr_abort, tcp_usr_accept, tcp_usr_attach, tcp_usr_bind, 466 tcp_usr_connect, pru_connect2_notsupp, in_control, tcp_usr_detach, 467 tcp_usr_disconnect, tcp_usr_listen, in_setpeeraddr, tcp_usr_rcvd, 468 tcp_usr_rcvoob, tcp_usr_send, pru_sense_null, tcp_usr_shutdown, 469 in_setsockaddr, sosend, soreceive, sopoll 470}; 471 472/* 473 * Common subroutine to open a TCP connection to remote host specified 474 * by struct sockaddr_in in mbuf *nam. Call in_pcbbind to assign a local 475 * port number if needed. Call in_pcbladdr to do the routing and to choose 476 * a local host address (interface). If there is an existing incarnation 477 * of the same connection in TIME-WAIT state and if the remote host was 478 * sending CC options and if the connection duration was < MSL, then 479 * truncate the previous TIME-WAIT state and proceed. 480 * Initialize connection parameters and enter SYN-SENT state. 481 */ 482static int 483tcp_connect(tp, nam, p) 484 register struct tcpcb *tp; 485 struct sockaddr *nam; 486 struct proc *p; 487{ 488 struct inpcb *inp = tp->t_inpcb, *oinp; 489 struct socket *so = inp->inp_socket; 490 struct tcpcb *otp; 491 struct sockaddr_in *sin = (struct sockaddr_in *)nam; 492 struct sockaddr_in *ifaddr; 493 struct rmxp_tao *taop; 494 struct rmxp_tao tao_noncached; 495 int error; 496 497 if (inp->inp_lport == 0) { 498 error = in_pcbbind(inp, (struct sockaddr *)0, p); 499 if (error) 500 return error; 501 } 502 503 /* 504 * Cannot simply call in_pcbconnect, because there might be an 505 * earlier incarnation of this same connection still in 506 * TIME_WAIT state, creating an ADDRINUSE error. 507 */ 508 error = in_pcbladdr(inp, nam, &ifaddr); 509 if (error) 510 return error; 511 oinp = in_pcblookup_hash(inp->inp_pcbinfo, 512 sin->sin_addr, sin->sin_port, 513 inp->inp_laddr.s_addr != INADDR_ANY ? inp->inp_laddr 514 : ifaddr->sin_addr, 515 inp->inp_lport, 0); 516 if (oinp) { 517 if (oinp != inp && (otp = intotcpcb(oinp)) != NULL && 518 otp->t_state == TCPS_TIME_WAIT && 519 otp->t_duration < TCPTV_MSL && 520 (otp->t_flags & TF_RCVD_CC)) 521 otp = tcp_close(otp); 522 else 523 return EADDRINUSE; 524 } 525 if (inp->inp_laddr.s_addr == INADDR_ANY) 526 inp->inp_laddr = ifaddr->sin_addr; 527 inp->inp_faddr = sin->sin_addr; 528 inp->inp_fport = sin->sin_port; 529 in_pcbrehash(inp); 530 531 tp->t_template = tcp_template(tp); 532 if (tp->t_template == 0) { 533 in_pcbdisconnect(inp); 534 return ENOBUFS; 535 } 536 537 /* Compute window scaling to request. */ 538 while (tp->request_r_scale < TCP_MAX_WINSHIFT && 539 (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat) 540 tp->request_r_scale++; 541 542 soisconnecting(so); 543 tcpstat.tcps_connattempt++; 544 tp->t_state = TCPS_SYN_SENT; 545 tp->t_timer[TCPT_KEEP] = tcp_keepinit; 546 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 547 tcp_sendseqinit(tp); 548 549 /* 550 * Generate a CC value for this connection and 551 * check whether CC or CCnew should be used. 552 */ 553 if ((taop = tcp_gettaocache(tp->t_inpcb)) == NULL) { 554 taop = &tao_noncached; 555 bzero(taop, sizeof(*taop)); 556 } 557 558 tp->cc_send = CC_INC(tcp_ccgen); 559 if (taop->tao_ccsent != 0 && 560 CC_GEQ(tp->cc_send, taop->tao_ccsent)) { 561 taop->tao_ccsent = tp->cc_send; 562 } else { 563 taop->tao_ccsent = 0; 564 tp->t_flags |= TF_SENDCCNEW; 565 } 566 567 return 0; 568} 569 570/* 571 * The new sockopt interface makes it possible for us to block in the 572 * copyin/out step (if we take a page fault). Taking a page fault at 573 * splnet() is probably a Bad Thing. (Since sockets and pcbs both now 574 * use TSM, there probably isn't any need for this function to run at 575 * splnet() any more. This needs more examination.) 576 */ 577int 578tcp_ctloutput(so, sopt) 579 struct socket *so; 580 struct sockopt *sopt; 581{ 582 int error, opt, optval, s; 583 struct inpcb *inp; 584 struct tcpcb *tp; 585 586 error = 0; 587 s = splnet(); /* XXX */ 588 inp = sotoinpcb(so); 589 if (inp == NULL) { 590 splx(s); 591 return (ECONNRESET); 592 } 593 if (sopt->sopt_level != IPPROTO_TCP) { 594 error = ip_ctloutput(so, sopt); 595 splx(s); 596 return (error); 597 } 598 tp = intotcpcb(inp); 599 600 switch (sopt->sopt_dir) { 601 case SOPT_SET: 602 switch (sopt->sopt_name) { 603 case TCP_NODELAY: 604 case TCP_NOOPT: 605 case TCP_NOPUSH: 606 error = sooptcopyin(sopt, &optval, sizeof optval, 607 sizeof optval); 608 if (error) 609 break; 610 611 switch (sopt->sopt_name) { 612 case TCP_NODELAY: 613 opt = TF_NODELAY; 614 break; 615 case TCP_NOOPT: 616 opt = TF_NOOPT; 617 break; 618 case TCP_NOPUSH: 619 opt = TF_NOPUSH; 620 break; 621 default: 622 opt = 0; /* dead code to fool gcc */ 623 break; 624 } 625 626 if (optval) 627 tp->t_flags |= opt; 628 else 629 tp->t_flags &= ~opt; 630 break; 631 632 case TCP_MAXSEG: 633 error = sooptcopyin(sopt, &optval, sizeof optval, 634 sizeof optval); 635 if (error) 636 break; 637 638 if (optval > 0 && optval <= tp->t_maxseg) 639 tp->t_maxseg = optval; 640 else 641 error = EINVAL; 642 break; 643 644 default: 645 error = ENOPROTOOPT; 646 break; 647 } 648 break; 649 650 case SOPT_GET: 651 switch (sopt->sopt_name) { 652 case TCP_NODELAY: 653 optval = tp->t_flags & TF_NODELAY; 654 break; 655 case TCP_MAXSEG: 656 optval = tp->t_maxseg; 657 break; 658 case TCP_NOOPT: 659 optval = tp->t_flags & TF_NOOPT; 660 break; 661 case TCP_NOPUSH: 662 optval = tp->t_flags & TF_NOPUSH; 663 break; 664 default: 665 error = ENOPROTOOPT; 666 break; 667 } 668 if (error == 0) 669 error = sooptcopyout(sopt, &optval, sizeof optval); 670 break; 671 } 672 splx(s); 673 return (error); 674} 675 676/* 677 * tcp_sendspace and tcp_recvspace are the default send and receive window 678 * sizes, respectively. These are obsolescent (this information should 679 * be set by the route). 680 */ 681u_long tcp_sendspace = 1024*16; 682SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_RW, 683 &tcp_sendspace , 0, "Maximum outgoing TCP datagram size"); 684u_long tcp_recvspace = 1024*16; 685SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_RW, 686 &tcp_recvspace , 0, "Maximum incoming TCP datagram size"); 687 688/* 689 * Attach TCP protocol to socket, allocating 690 * internet protocol control block, tcp control block, 691 * bufer space, and entering LISTEN state if to accept connections. 692 */ 693static int 694tcp_attach(so, p) 695 struct socket *so; 696 struct proc *p; 697{ 698 register struct tcpcb *tp; 699 struct inpcb *inp; 700 int error; 701 702 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 703 error = soreserve(so, tcp_sendspace, tcp_recvspace); 704 if (error) 705 return (error); 706 } 707 error = in_pcballoc(so, &tcbinfo, p); 708 if (error) 709 return (error); 710 inp = sotoinpcb(so); 711 tp = tcp_newtcpcb(inp); 712 if (tp == 0) { 713 int nofd = so->so_state & SS_NOFDREF; /* XXX */ 714 715 so->so_state &= ~SS_NOFDREF; /* don't free the socket yet */ 716 in_pcbdetach(inp); 717 so->so_state |= nofd; 718 return (ENOBUFS); 719 } 720 tp->t_state = TCPS_CLOSED; 721 return (0); 722} 723 724/* 725 * Initiate (or continue) disconnect. 726 * If embryonic state, just send reset (once). 727 * If in ``let data drain'' option and linger null, just drop. 728 * Otherwise (hard), mark socket disconnecting and drop 729 * current input data; switch states based on user close, and 730 * send segment to peer (with FIN). 731 */ 732static struct tcpcb * 733tcp_disconnect(tp) 734 register struct tcpcb *tp; 735{ 736 struct socket *so = tp->t_inpcb->inp_socket; 737 738 if (tp->t_state < TCPS_ESTABLISHED) 739 tp = tcp_close(tp); 740 else if ((so->so_options & SO_LINGER) && so->so_linger == 0) 741 tp = tcp_drop(tp, 0); 742 else { 743 soisdisconnecting(so); 744 sbflush(&so->so_rcv); 745 tp = tcp_usrclosed(tp); 746 if (tp) 747 (void) tcp_output(tp); 748 } 749 return (tp); 750} 751 752/* 753 * User issued close, and wish to trail through shutdown states: 754 * if never received SYN, just forget it. If got a SYN from peer, 755 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN. 756 * If already got a FIN from peer, then almost done; go to LAST_ACK 757 * state. In all other cases, have already sent FIN to peer (e.g. 758 * after PRU_SHUTDOWN), and just have to play tedious game waiting 759 * for peer to send FIN or not respond to keep-alives, etc. 760 * We can let the user exit from the close as soon as the FIN is acked. 761 */ 762static struct tcpcb * 763tcp_usrclosed(tp) 764 register struct tcpcb *tp; 765{ 766 767 switch (tp->t_state) { 768 769 case TCPS_CLOSED: 770 case TCPS_LISTEN: 771 tp->t_state = TCPS_CLOSED; 772 tp = tcp_close(tp); 773 break; 774 775 case TCPS_SYN_SENT: 776 case TCPS_SYN_RECEIVED: 777 tp->t_flags |= TF_NEEDFIN; 778 break; 779 780 case TCPS_ESTABLISHED: 781 tp->t_state = TCPS_FIN_WAIT_1; 782 break; 783 784 case TCPS_CLOSE_WAIT: 785 tp->t_state = TCPS_LAST_ACK; 786 break; 787 } 788 if (tp && tp->t_state >= TCPS_FIN_WAIT_2) { 789 soisdisconnected(tp->t_inpcb->inp_socket); 790 /* To prevent the connection hanging in FIN_WAIT_2 forever. */ 791 if (tp->t_state == TCPS_FIN_WAIT_2) 792 tp->t_timer[TCPT_2MSL] = tcp_maxidle; 793 } 794 return (tp); 795} 796 797