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