tcp_usrreq.c revision 32821
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 1.36 1997/12/18 09:50:38 davidg 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 * hz; 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 if ((error = tcp_connect(tp, nam, p)) != 0) 243 goto out; 244 error = tcp_output(tp); 245 COMMON_END(PRU_CONNECT); 246} 247 248/* 249 * Initiate disconnect from peer. 250 * If connection never passed embryonic stage, just drop; 251 * else if don't need to let data drain, then can just drop anyways, 252 * else have to begin TCP shutdown process: mark socket disconnecting, 253 * drain unread data, state switch to reflect user close, and 254 * send segment (e.g. FIN) to peer. Socket will be really disconnected 255 * when peer sends FIN and acks ours. 256 * 257 * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB. 258 */ 259static int 260tcp_usr_disconnect(struct socket *so) 261{ 262 int s = splnet(); 263 int error = 0; 264 struct inpcb *inp = sotoinpcb(so); 265 struct tcpcb *tp; 266 267 COMMON_START(); 268 tp = tcp_disconnect(tp); 269 COMMON_END(PRU_DISCONNECT); 270} 271 272/* 273 * Accept a connection. Essentially all the work is 274 * done at higher levels; just return the address 275 * of the peer, storing through addr. 276 */ 277static int 278tcp_usr_accept(struct socket *so, struct sockaddr **nam) 279{ 280 int s = splnet(); 281 int error = 0; 282 struct inpcb *inp = sotoinpcb(so); 283 struct tcpcb *tp; 284 285 COMMON_START(); 286 in_setpeeraddr(so, nam); 287 COMMON_END(PRU_ACCEPT); 288} 289 290/* 291 * Mark the connection as being incapable of further output. 292 */ 293static int 294tcp_usr_shutdown(struct socket *so) 295{ 296 int s = splnet(); 297 int error = 0; 298 struct inpcb *inp = sotoinpcb(so); 299 struct tcpcb *tp; 300 301 COMMON_START(); 302 socantsendmore(so); 303 tp = tcp_usrclosed(tp); 304 if (tp) 305 error = tcp_output(tp); 306 COMMON_END(PRU_SHUTDOWN); 307} 308 309/* 310 * After a receive, possibly send window update to peer. 311 */ 312static int 313tcp_usr_rcvd(struct socket *so, int flags) 314{ 315 int s = splnet(); 316 int error = 0; 317 struct inpcb *inp = sotoinpcb(so); 318 struct tcpcb *tp; 319 320 COMMON_START(); 321 tcp_output(tp); 322 COMMON_END(PRU_RCVD); 323} 324 325/* 326 * Do a send by putting data in output queue and updating urgent 327 * marker if URG set. Possibly send more data. 328 */ 329static int 330tcp_usr_send(struct socket *so, int flags, struct mbuf *m, 331 struct sockaddr *nam, struct mbuf *control, struct proc *p) 332{ 333 int s = splnet(); 334 int error = 0; 335 struct inpcb *inp = sotoinpcb(so); 336 struct tcpcb *tp; 337 338 COMMON_START(); 339 if (control && control->m_len) { 340 m_freem(control); /* XXX shouldn't caller do this??? */ 341 if (m) 342 m_freem(m); 343 error = EINVAL; 344 goto out; 345 } 346 347 if(!(flags & PRUS_OOB)) { 348 sbappend(&so->so_snd, m); 349 if (nam && tp->t_state < TCPS_SYN_SENT) { 350 /* 351 * Do implied connect if not yet connected, 352 * initialize window to default value, and 353 * initialize maxseg/maxopd using peer's cached 354 * MSS. 355 */ 356 error = tcp_connect(tp, nam, p); 357 if (error) 358 goto out; 359 tp->snd_wnd = TTCP_CLIENT_SND_WND; 360 tcp_mss(tp, -1); 361 } 362 363 if (flags & PRUS_EOF) { 364 /* 365 * Close the send side of the connection after 366 * the data is sent. 367 */ 368 socantsendmore(so); 369 tp = tcp_usrclosed(tp); 370 } 371 if (tp != NULL) 372 error = tcp_output(tp); 373 } else { 374 if (sbspace(&so->so_snd) < -512) { 375 m_freem(m); 376 error = ENOBUFS; 377 goto out; 378 } 379 /* 380 * According to RFC961 (Assigned Protocols), 381 * the urgent pointer points to the last octet 382 * of urgent data. We continue, however, 383 * to consider it to indicate the first octet 384 * of data past the urgent section. 385 * Otherwise, snd_up should be one lower. 386 */ 387 sbappend(&so->so_snd, m); 388 if (nam && tp->t_state < TCPS_SYN_SENT) { 389 /* 390 * Do implied connect if not yet connected, 391 * initialize window to default value, and 392 * initialize maxseg/maxopd using peer's cached 393 * MSS. 394 */ 395 error = tcp_connect(tp, nam, p); 396 if (error) 397 goto out; 398 tp->snd_wnd = TTCP_CLIENT_SND_WND; 399 tcp_mss(tp, -1); 400 } 401 tp->snd_up = tp->snd_una + so->so_snd.sb_cc; 402 tp->t_force = 1; 403 error = tcp_output(tp); 404 tp->t_force = 0; 405 } 406 COMMON_END((flags & PRUS_OOB) ? PRU_SENDOOB : 407 ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND)); 408} 409 410/* 411 * Abort the TCP. 412 */ 413static int 414tcp_usr_abort(struct socket *so) 415{ 416 int s = splnet(); 417 int error = 0; 418 struct inpcb *inp = sotoinpcb(so); 419 struct tcpcb *tp; 420 421 COMMON_START(); 422 tp = tcp_drop(tp, ECONNABORTED); 423 COMMON_END(PRU_ABORT); 424} 425 426/* 427 * Receive out-of-band data. 428 */ 429static int 430tcp_usr_rcvoob(struct socket *so, struct mbuf *m, int flags) 431{ 432 int s = splnet(); 433 int error = 0; 434 struct inpcb *inp = sotoinpcb(so); 435 struct tcpcb *tp; 436 437 COMMON_START(); 438 if ((so->so_oobmark == 0 && 439 (so->so_state & SS_RCVATMARK) == 0) || 440 so->so_options & SO_OOBINLINE || 441 tp->t_oobflags & TCPOOB_HADDATA) { 442 error = EINVAL; 443 goto out; 444 } 445 if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) { 446 error = EWOULDBLOCK; 447 goto out; 448 } 449 m->m_len = 1; 450 *mtod(m, caddr_t) = tp->t_iobc; 451 if ((flags & MSG_PEEK) == 0) 452 tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA); 453 COMMON_END(PRU_RCVOOB); 454} 455 456/* xxx - should be const */ 457struct pr_usrreqs tcp_usrreqs = { 458 tcp_usr_abort, tcp_usr_accept, tcp_usr_attach, tcp_usr_bind, 459 tcp_usr_connect, pru_connect2_notsupp, in_control, tcp_usr_detach, 460 tcp_usr_disconnect, tcp_usr_listen, in_setpeeraddr, tcp_usr_rcvd, 461 tcp_usr_rcvoob, tcp_usr_send, pru_sense_null, tcp_usr_shutdown, 462 in_setsockaddr, sosend, soreceive, sopoll 463}; 464 465/* 466 * Common subroutine to open a TCP connection to remote host specified 467 * by struct sockaddr_in in mbuf *nam. Call in_pcbbind to assign a local 468 * port number if needed. Call in_pcbladdr to do the routing and to choose 469 * a local host address (interface). If there is an existing incarnation 470 * of the same connection in TIME-WAIT state and if the remote host was 471 * sending CC options and if the connection duration was < MSL, then 472 * truncate the previous TIME-WAIT state and proceed. 473 * Initialize connection parameters and enter SYN-SENT state. 474 */ 475static int 476tcp_connect(tp, nam, p) 477 register struct tcpcb *tp; 478 struct sockaddr *nam; 479 struct proc *p; 480{ 481 struct inpcb *inp = tp->t_inpcb, *oinp; 482 struct socket *so = inp->inp_socket; 483 struct tcpcb *otp; 484 struct sockaddr_in *sin = (struct sockaddr_in *)nam; 485 struct sockaddr_in *ifaddr; 486 struct rmxp_tao *taop; 487 struct rmxp_tao tao_noncached; 488 int error; 489 490 if (inp->inp_lport == 0) { 491 error = in_pcbbind(inp, (struct sockaddr *)0, p); 492 if (error) 493 return error; 494 } 495 496 /* 497 * Cannot simply call in_pcbconnect, because there might be an 498 * earlier incarnation of this same connection still in 499 * TIME_WAIT state, creating an ADDRINUSE error. 500 */ 501 error = in_pcbladdr(inp, nam, &ifaddr); 502 if (error) 503 return error; 504 oinp = in_pcblookup_hash(inp->inp_pcbinfo, 505 sin->sin_addr, sin->sin_port, 506 inp->inp_laddr.s_addr != INADDR_ANY ? inp->inp_laddr 507 : ifaddr->sin_addr, 508 inp->inp_lport, 0); 509 if (oinp) { 510 if (oinp != inp && (otp = intotcpcb(oinp)) != NULL && 511 otp->t_state == TCPS_TIME_WAIT && 512 otp->t_duration < TCPTV_MSL && 513 (otp->t_flags & TF_RCVD_CC)) 514 otp = tcp_close(otp); 515 else 516 return EADDRINUSE; 517 } 518 if (inp->inp_laddr.s_addr == INADDR_ANY) 519 inp->inp_laddr = ifaddr->sin_addr; 520 inp->inp_faddr = sin->sin_addr; 521 inp->inp_fport = sin->sin_port; 522 in_pcbrehash(inp); 523 524 tp->t_template = tcp_template(tp); 525 if (tp->t_template == 0) { 526 in_pcbdisconnect(inp); 527 return ENOBUFS; 528 } 529 530 /* Compute window scaling to request. */ 531 while (tp->request_r_scale < TCP_MAX_WINSHIFT && 532 (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat) 533 tp->request_r_scale++; 534 535 soisconnecting(so); 536 tcpstat.tcps_connattempt++; 537 tp->t_state = TCPS_SYN_SENT; 538 tp->t_timer[TCPT_KEEP] = tcp_keepinit; 539 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 540 tcp_sendseqinit(tp); 541 542 /* 543 * Generate a CC value for this connection and 544 * check whether CC or CCnew should be used. 545 */ 546 if ((taop = tcp_gettaocache(tp->t_inpcb)) == NULL) { 547 taop = &tao_noncached; 548 bzero(taop, sizeof(*taop)); 549 } 550 551 tp->cc_send = CC_INC(tcp_ccgen); 552 if (taop->tao_ccsent != 0 && 553 CC_GEQ(tp->cc_send, taop->tao_ccsent)) { 554 taop->tao_ccsent = tp->cc_send; 555 } else { 556 taop->tao_ccsent = 0; 557 tp->t_flags |= TF_SENDCCNEW; 558 } 559 560 return 0; 561} 562 563int 564tcp_ctloutput(op, so, level, optname, mp, p) 565 int op; 566 struct socket *so; 567 int level, optname; 568 struct mbuf **mp; 569 struct proc *p; 570{ 571 int error = 0, s; 572 struct inpcb *inp; 573 register struct tcpcb *tp; 574 register struct mbuf *m; 575 register int i; 576 577 s = splnet(); 578 inp = sotoinpcb(so); 579 if (inp == NULL) { 580 splx(s); 581 if (op == PRCO_SETOPT && *mp) 582 (void) m_free(*mp); 583 return (ECONNRESET); 584 } 585 if (level != IPPROTO_TCP) { 586 error = ip_ctloutput(op, so, level, optname, mp, p); 587 splx(s); 588 return (error); 589 } 590 tp = intotcpcb(inp); 591 592 switch (op) { 593 594 case PRCO_SETOPT: 595 m = *mp; 596 switch (optname) { 597 598 case TCP_NODELAY: 599 if (m == NULL || m->m_len < sizeof (int)) 600 error = EINVAL; 601 else if (*mtod(m, int *)) 602 tp->t_flags |= TF_NODELAY; 603 else 604 tp->t_flags &= ~TF_NODELAY; 605 break; 606 607 case TCP_MAXSEG: 608 if (m && (i = *mtod(m, int *)) > 0 && i <= tp->t_maxseg) 609 tp->t_maxseg = i; 610 else 611 error = EINVAL; 612 break; 613 614 case TCP_NOOPT: 615 if (m == NULL || m->m_len < sizeof (int)) 616 error = EINVAL; 617 else if (*mtod(m, int *)) 618 tp->t_flags |= TF_NOOPT; 619 else 620 tp->t_flags &= ~TF_NOOPT; 621 break; 622 623 case TCP_NOPUSH: 624 if (m == NULL || m->m_len < sizeof (int)) 625 error = EINVAL; 626 else if (*mtod(m, int *)) 627 tp->t_flags |= TF_NOPUSH; 628 else 629 tp->t_flags &= ~TF_NOPUSH; 630 break; 631 632 default: 633 error = ENOPROTOOPT; 634 break; 635 } 636 if (m) 637 (void) m_free(m); 638 break; 639 640 case PRCO_GETOPT: 641 *mp = m = m_get(M_WAIT, MT_SOOPTS); 642 m->m_len = sizeof(int); 643 644 switch (optname) { 645 case TCP_NODELAY: 646 *mtod(m, int *) = tp->t_flags & TF_NODELAY; 647 break; 648 case TCP_MAXSEG: 649 *mtod(m, int *) = tp->t_maxseg; 650 break; 651 case TCP_NOOPT: 652 *mtod(m, int *) = tp->t_flags & TF_NOOPT; 653 break; 654 case TCP_NOPUSH: 655 *mtod(m, int *) = tp->t_flags & TF_NOPUSH; 656 break; 657 default: 658 error = ENOPROTOOPT; 659 break; 660 } 661 break; 662 } 663 splx(s); 664 return (error); 665} 666 667/* 668 * tcp_sendspace and tcp_recvspace are the default send and receive window 669 * sizes, respectively. These are obsolescent (this information should 670 * be set by the route). 671 */ 672u_long tcp_sendspace = 1024*16; 673SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, 674 CTLFLAG_RW, &tcp_sendspace , 0, ""); 675u_long tcp_recvspace = 1024*16; 676SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, 677 CTLFLAG_RW, &tcp_recvspace , 0, ""); 678 679/* 680 * Attach TCP protocol to socket, allocating 681 * internet protocol control block, tcp control block, 682 * bufer space, and entering LISTEN state if to accept connections. 683 */ 684static int 685tcp_attach(so, p) 686 struct socket *so; 687 struct proc *p; 688{ 689 register struct tcpcb *tp; 690 struct inpcb *inp; 691 int error; 692 693 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 694 error = soreserve(so, tcp_sendspace, tcp_recvspace); 695 if (error) 696 return (error); 697 } 698 error = in_pcballoc(so, &tcbinfo, p); 699 if (error) 700 return (error); 701 inp = sotoinpcb(so); 702 tp = tcp_newtcpcb(inp); 703 if (tp == 0) { 704 int nofd = so->so_state & SS_NOFDREF; /* XXX */ 705 706 so->so_state &= ~SS_NOFDREF; /* don't free the socket yet */ 707 in_pcbdetach(inp); 708 so->so_state |= nofd; 709 return (ENOBUFS); 710 } 711 tp->t_state = TCPS_CLOSED; 712 return (0); 713} 714 715/* 716 * Initiate (or continue) disconnect. 717 * If embryonic state, just send reset (once). 718 * If in ``let data drain'' option and linger null, just drop. 719 * Otherwise (hard), mark socket disconnecting and drop 720 * current input data; switch states based on user close, and 721 * send segment to peer (with FIN). 722 */ 723static struct tcpcb * 724tcp_disconnect(tp) 725 register struct tcpcb *tp; 726{ 727 struct socket *so = tp->t_inpcb->inp_socket; 728 729 if (tp->t_state < TCPS_ESTABLISHED) 730 tp = tcp_close(tp); 731 else if ((so->so_options & SO_LINGER) && so->so_linger == 0) 732 tp = tcp_drop(tp, 0); 733 else { 734 soisdisconnecting(so); 735 sbflush(&so->so_rcv); 736 tp = tcp_usrclosed(tp); 737 if (tp) 738 (void) tcp_output(tp); 739 } 740 return (tp); 741} 742 743/* 744 * User issued close, and wish to trail through shutdown states: 745 * if never received SYN, just forget it. If got a SYN from peer, 746 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN. 747 * If already got a FIN from peer, then almost done; go to LAST_ACK 748 * state. In all other cases, have already sent FIN to peer (e.g. 749 * after PRU_SHUTDOWN), and just have to play tedious game waiting 750 * for peer to send FIN or not respond to keep-alives, etc. 751 * We can let the user exit from the close as soon as the FIN is acked. 752 */ 753static struct tcpcb * 754tcp_usrclosed(tp) 755 register struct tcpcb *tp; 756{ 757 758 switch (tp->t_state) { 759 760 case TCPS_CLOSED: 761 case TCPS_LISTEN: 762 tp->t_state = TCPS_CLOSED; 763 tp = tcp_close(tp); 764 break; 765 766 case TCPS_SYN_SENT: 767 case TCPS_SYN_RECEIVED: 768 tp->t_flags |= TF_NEEDFIN; 769 break; 770 771 case TCPS_ESTABLISHED: 772 tp->t_state = TCPS_FIN_WAIT_1; 773 break; 774 775 case TCPS_CLOSE_WAIT: 776 tp->t_state = TCPS_LAST_ACK; 777 break; 778 } 779 if (tp && tp->t_state >= TCPS_FIN_WAIT_2) { 780 soisdisconnected(tp->t_inpcb->inp_socket); 781 /* To prevent the connection hanging in FIN_WAIT_2 forever. */ 782 if (tp->t_state == TCPS_FIN_WAIT_2) 783 tp->t_timer[TCPT_2MSL] = tcp_maxidle; 784 } 785 return (tp); 786} 787 788