tcp_usrreq.c revision 42902
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 1.39 1998/12/07 21:58:42 archie 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 if (flags & PRUS_MORETOCOME) 373 tp->t_flags |= TF_MORETOCOME; 374 error = tcp_output(tp); 375 if (flags & PRUS_MORETOCOME) 376 tp->t_flags &= ~TF_MORETOCOME; 377 } 378 } else { 379 if (sbspace(&so->so_snd) < -512) { 380 m_freem(m); 381 error = ENOBUFS; 382 goto out; 383 } 384 /* 385 * According to RFC961 (Assigned Protocols), 386 * the urgent pointer points to the last octet 387 * of urgent data. We continue, however, 388 * to consider it to indicate the first octet 389 * of data past the urgent section. 390 * Otherwise, snd_up should be one lower. 391 */ 392 sbappend(&so->so_snd, m); 393 if (nam && tp->t_state < TCPS_SYN_SENT) { 394 /* 395 * Do implied connect if not yet connected, 396 * initialize window to default value, and 397 * initialize maxseg/maxopd using peer's cached 398 * MSS. 399 */ 400 error = tcp_connect(tp, nam, p); 401 if (error) 402 goto out; 403 tp->snd_wnd = TTCP_CLIENT_SND_WND; 404 tcp_mss(tp, -1); 405 } 406 tp->snd_up = tp->snd_una + so->so_snd.sb_cc; 407 tp->t_force = 1; 408 error = tcp_output(tp); 409 tp->t_force = 0; 410 } 411 COMMON_END((flags & PRUS_OOB) ? PRU_SENDOOB : 412 ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND)); 413} 414 415/* 416 * Abort the TCP. 417 */ 418static int 419tcp_usr_abort(struct socket *so) 420{ 421 int s = splnet(); 422 int error = 0; 423 struct inpcb *inp = sotoinpcb(so); 424 struct tcpcb *tp; 425 426 COMMON_START(); 427 tp = tcp_drop(tp, ECONNABORTED); 428 COMMON_END(PRU_ABORT); 429} 430 431/* 432 * Receive out-of-band data. 433 */ 434static int 435tcp_usr_rcvoob(struct socket *so, struct mbuf *m, int flags) 436{ 437 int s = splnet(); 438 int error = 0; 439 struct inpcb *inp = sotoinpcb(so); 440 struct tcpcb *tp; 441 442 COMMON_START(); 443 if ((so->so_oobmark == 0 && 444 (so->so_state & SS_RCVATMARK) == 0) || 445 so->so_options & SO_OOBINLINE || 446 tp->t_oobflags & TCPOOB_HADDATA) { 447 error = EINVAL; 448 goto out; 449 } 450 if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) { 451 error = EWOULDBLOCK; 452 goto out; 453 } 454 m->m_len = 1; 455 *mtod(m, caddr_t) = tp->t_iobc; 456 if ((flags & MSG_PEEK) == 0) 457 tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA); 458 COMMON_END(PRU_RCVOOB); 459} 460 461/* xxx - should be const */ 462struct pr_usrreqs tcp_usrreqs = { 463 tcp_usr_abort, tcp_usr_accept, tcp_usr_attach, tcp_usr_bind, 464 tcp_usr_connect, pru_connect2_notsupp, in_control, tcp_usr_detach, 465 tcp_usr_disconnect, tcp_usr_listen, in_setpeeraddr, tcp_usr_rcvd, 466 tcp_usr_rcvoob, tcp_usr_send, pru_sense_null, tcp_usr_shutdown, 467 in_setsockaddr, sosend, soreceive, sopoll 468}; 469 470/* 471 * Common subroutine to open a TCP connection to remote host specified 472 * by struct sockaddr_in in mbuf *nam. Call in_pcbbind to assign a local 473 * port number if needed. Call in_pcbladdr to do the routing and to choose 474 * a local host address (interface). If there is an existing incarnation 475 * of the same connection in TIME-WAIT state and if the remote host was 476 * sending CC options and if the connection duration was < MSL, then 477 * truncate the previous TIME-WAIT state and proceed. 478 * Initialize connection parameters and enter SYN-SENT state. 479 */ 480static int 481tcp_connect(tp, nam, p) 482 register struct tcpcb *tp; 483 struct sockaddr *nam; 484 struct proc *p; 485{ 486 struct inpcb *inp = tp->t_inpcb, *oinp; 487 struct socket *so = inp->inp_socket; 488 struct tcpcb *otp; 489 struct sockaddr_in *sin = (struct sockaddr_in *)nam; 490 struct sockaddr_in *ifaddr; 491 struct rmxp_tao *taop; 492 struct rmxp_tao tao_noncached; 493 int error; 494 495 if (inp->inp_lport == 0) { 496 error = in_pcbbind(inp, (struct sockaddr *)0, p); 497 if (error) 498 return error; 499 } 500 501 /* 502 * Cannot simply call in_pcbconnect, because there might be an 503 * earlier incarnation of this same connection still in 504 * TIME_WAIT state, creating an ADDRINUSE error. 505 */ 506 error = in_pcbladdr(inp, nam, &ifaddr); 507 if (error) 508 return error; 509 oinp = in_pcblookup_hash(inp->inp_pcbinfo, 510 sin->sin_addr, sin->sin_port, 511 inp->inp_laddr.s_addr != INADDR_ANY ? inp->inp_laddr 512 : ifaddr->sin_addr, 513 inp->inp_lport, 0); 514 if (oinp) { 515 if (oinp != inp && (otp = intotcpcb(oinp)) != NULL && 516 otp->t_state == TCPS_TIME_WAIT && 517 otp->t_duration < TCPTV_MSL && 518 (otp->t_flags & TF_RCVD_CC)) 519 otp = tcp_close(otp); 520 else 521 return EADDRINUSE; 522 } 523 if (inp->inp_laddr.s_addr == INADDR_ANY) 524 inp->inp_laddr = ifaddr->sin_addr; 525 inp->inp_faddr = sin->sin_addr; 526 inp->inp_fport = sin->sin_port; 527 in_pcbrehash(inp); 528 529 tp->t_template = tcp_template(tp); 530 if (tp->t_template == 0) { 531 in_pcbdisconnect(inp); 532 return ENOBUFS; 533 } 534 535 /* Compute window scaling to request. */ 536 while (tp->request_r_scale < TCP_MAX_WINSHIFT && 537 (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat) 538 tp->request_r_scale++; 539 540 soisconnecting(so); 541 tcpstat.tcps_connattempt++; 542 tp->t_state = TCPS_SYN_SENT; 543 tp->t_timer[TCPT_KEEP] = tcp_keepinit; 544 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 545 tcp_sendseqinit(tp); 546 547 /* 548 * Generate a CC value for this connection and 549 * check whether CC or CCnew should be used. 550 */ 551 if ((taop = tcp_gettaocache(tp->t_inpcb)) == NULL) { 552 taop = &tao_noncached; 553 bzero(taop, sizeof(*taop)); 554 } 555 556 tp->cc_send = CC_INC(tcp_ccgen); 557 if (taop->tao_ccsent != 0 && 558 CC_GEQ(tp->cc_send, taop->tao_ccsent)) { 559 taop->tao_ccsent = tp->cc_send; 560 } else { 561 taop->tao_ccsent = 0; 562 tp->t_flags |= TF_SENDCCNEW; 563 } 564 565 return 0; 566} 567 568/* 569 * The new sockopt interface makes it possible for us to block in the 570 * copyin/out step (if we take a page fault). Taking a page fault at 571 * splnet() is probably a Bad Thing. (Since sockets and pcbs both now 572 * use TSM, there probably isn't any need for this function to run at 573 * splnet() any more. This needs more examination.) 574 */ 575int 576tcp_ctloutput(so, sopt) 577 struct socket *so; 578 struct sockopt *sopt; 579{ 580 int error, opt, optval, s; 581 struct inpcb *inp; 582 struct tcpcb *tp; 583 584 error = 0; 585 s = splnet(); /* XXX */ 586 inp = sotoinpcb(so); 587 if (inp == NULL) { 588 splx(s); 589 return (ECONNRESET); 590 } 591 if (sopt->sopt_level != IPPROTO_TCP) { 592 error = ip_ctloutput(so, sopt); 593 splx(s); 594 return (error); 595 } 596 tp = intotcpcb(inp); 597 598 switch (sopt->sopt_dir) { 599 case SOPT_SET: 600 switch (sopt->sopt_name) { 601 case TCP_NODELAY: 602 case TCP_NOOPT: 603 case TCP_NOPUSH: 604 error = sooptcopyin(sopt, &optval, sizeof optval, 605 sizeof optval); 606 if (error) 607 break; 608 609 switch (sopt->sopt_name) { 610 case TCP_NODELAY: 611 opt = TF_NODELAY; 612 break; 613 case TCP_NOOPT: 614 opt = TF_NOOPT; 615 break; 616 case TCP_NOPUSH: 617 opt = TF_NOPUSH; 618 break; 619 default: 620 opt = 0; /* dead code to fool gcc */ 621 break; 622 } 623 624 if (optval) 625 tp->t_flags |= opt; 626 else 627 tp->t_flags &= ~opt; 628 break; 629 630 case TCP_MAXSEG: 631 error = sooptcopyin(sopt, &optval, sizeof optval, 632 sizeof optval); 633 if (error) 634 break; 635 636 if (optval > 0 && optval <= tp->t_maxseg) 637 tp->t_maxseg = optval; 638 else 639 error = EINVAL; 640 break; 641 642 default: 643 error = ENOPROTOOPT; 644 break; 645 } 646 break; 647 648 case SOPT_GET: 649 switch (sopt->sopt_name) { 650 case TCP_NODELAY: 651 optval = tp->t_flags & TF_NODELAY; 652 break; 653 case TCP_MAXSEG: 654 optval = tp->t_maxseg; 655 break; 656 case TCP_NOOPT: 657 optval = tp->t_flags & TF_NOOPT; 658 break; 659 case TCP_NOPUSH: 660 optval = tp->t_flags & TF_NOPUSH; 661 break; 662 default: 663 error = ENOPROTOOPT; 664 break; 665 } 666 if (error == 0) 667 error = sooptcopyout(sopt, &optval, sizeof optval); 668 break; 669 } 670 splx(s); 671 return (error); 672} 673 674/* 675 * tcp_sendspace and tcp_recvspace are the default send and receive window 676 * sizes, respectively. These are obsolescent (this information should 677 * be set by the route). 678 */ 679u_long tcp_sendspace = 1024*16; 680SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, 681 CTLFLAG_RW, &tcp_sendspace , 0, ""); 682u_long tcp_recvspace = 1024*16; 683SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, 684 CTLFLAG_RW, &tcp_recvspace , 0, ""); 685 686/* 687 * Attach TCP protocol to socket, allocating 688 * internet protocol control block, tcp control block, 689 * bufer space, and entering LISTEN state if to accept connections. 690 */ 691static int 692tcp_attach(so, p) 693 struct socket *so; 694 struct proc *p; 695{ 696 register struct tcpcb *tp; 697 struct inpcb *inp; 698 int error; 699 700 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 701 error = soreserve(so, tcp_sendspace, tcp_recvspace); 702 if (error) 703 return (error); 704 } 705 error = in_pcballoc(so, &tcbinfo, p); 706 if (error) 707 return (error); 708 inp = sotoinpcb(so); 709 tp = tcp_newtcpcb(inp); 710 if (tp == 0) { 711 int nofd = so->so_state & SS_NOFDREF; /* XXX */ 712 713 so->so_state &= ~SS_NOFDREF; /* don't free the socket yet */ 714 in_pcbdetach(inp); 715 so->so_state |= nofd; 716 return (ENOBUFS); 717 } 718 tp->t_state = TCPS_CLOSED; 719 return (0); 720} 721 722/* 723 * Initiate (or continue) disconnect. 724 * If embryonic state, just send reset (once). 725 * If in ``let data drain'' option and linger null, just drop. 726 * Otherwise (hard), mark socket disconnecting and drop 727 * current input data; switch states based on user close, and 728 * send segment to peer (with FIN). 729 */ 730static struct tcpcb * 731tcp_disconnect(tp) 732 register struct tcpcb *tp; 733{ 734 struct socket *so = tp->t_inpcb->inp_socket; 735 736 if (tp->t_state < TCPS_ESTABLISHED) 737 tp = tcp_close(tp); 738 else if ((so->so_options & SO_LINGER) && so->so_linger == 0) 739 tp = tcp_drop(tp, 0); 740 else { 741 soisdisconnecting(so); 742 sbflush(&so->so_rcv); 743 tp = tcp_usrclosed(tp); 744 if (tp) 745 (void) tcp_output(tp); 746 } 747 return (tp); 748} 749 750/* 751 * User issued close, and wish to trail through shutdown states: 752 * if never received SYN, just forget it. If got a SYN from peer, 753 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN. 754 * If already got a FIN from peer, then almost done; go to LAST_ACK 755 * state. In all other cases, have already sent FIN to peer (e.g. 756 * after PRU_SHUTDOWN), and just have to play tedious game waiting 757 * for peer to send FIN or not respond to keep-alives, etc. 758 * We can let the user exit from the close as soon as the FIN is acked. 759 */ 760static struct tcpcb * 761tcp_usrclosed(tp) 762 register struct tcpcb *tp; 763{ 764 765 switch (tp->t_state) { 766 767 case TCPS_CLOSED: 768 case TCPS_LISTEN: 769 tp->t_state = TCPS_CLOSED; 770 tp = tcp_close(tp); 771 break; 772 773 case TCPS_SYN_SENT: 774 case TCPS_SYN_RECEIVED: 775 tp->t_flags |= TF_NEEDFIN; 776 break; 777 778 case TCPS_ESTABLISHED: 779 tp->t_state = TCPS_FIN_WAIT_1; 780 break; 781 782 case TCPS_CLOSE_WAIT: 783 tp->t_state = TCPS_LAST_ACK; 784 break; 785 } 786 if (tp && tp->t_state >= TCPS_FIN_WAIT_2) { 787 soisdisconnected(tp->t_inpcb->inp_socket); 788 /* To prevent the connection hanging in FIN_WAIT_2 forever. */ 789 if (tp->t_state == TCPS_FIN_WAIT_2) 790 tp->t_timer[TCPT_2MSL] = tcp_maxidle; 791 } 792 return (tp); 793} 794 795