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 1.37 1998/01/27 09:15:11 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 */ 69 extern char *tcpstates[]; /* XXX ??? */ 70 71 static int tcp_attach __P((struct socket *, struct proc *)); 72 static int tcp_connect __P((struct tcpcb *, struct sockaddr *, 73 struct proc *)); 74 static struct tcpcb * 75 tcp_disconnect __P((struct tcpcb *)); 76 static 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 */ 94 static int 95 tcp_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); 116 out: 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 */ 129 static int 130 tcp_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 */ 167 static int 168 tcp_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 */ 198 static int 199 tcp_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 */ 221 static int 222 tcp_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 */ 259 static int 260 tcp_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 */ 277 static int 278 tcp_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 */ 293 static int 294 tcp_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 */ 312 static int 313 tcp_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 */ 329 static int 330 tcp_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 */ 413 static int 414 tcp_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 */ 429 static int 430 tcp_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 */ 457 struct 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 */ 475 static int 476 tcp_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 } 562 563 /* 564 * The new sockopt interface makes it possible for us to block in the 565 * copyin/out step (if we take a page fault). Taking a page fault at 566 * splnet() is probably a Bad Thing. (Since sockets and pcbs both now 567 * use TSM, there probably isn't any need for this function to run at 568 * splnet() any more. This needs more examination.) 569 */ 570 int 571 tcp_ctloutput(so, sopt) 572 struct socket *so; 573 struct sockopt *sopt; 574 { 575 int error, opt, optval, s; 576 struct inpcb *inp; 577 struct tcpcb *tp; 578 struct mbuf *m; 579 580 error = 0; 581 s = splnet(); /* XXX */ 582 inp = sotoinpcb(so); 583 if (inp == NULL) { 584 splx(s); 585 return (ECONNRESET); 586 } 587 if (sopt->sopt_level != IPPROTO_TCP) { 588 error = ip_ctloutput(so, sopt); 589 splx(s); 590 return (error); 591 } 592 tp = intotcpcb(inp); 593 594 switch (sopt->sopt_dir) { 595 case SOPT_SET: 596 switch (sopt->sopt_name) { 597 case TCP_NODELAY: 598 case TCP_NOOPT: 599 case TCP_NOPUSH: 600 error = sooptcopyin(sopt, &optval, sizeof optval, 601 sizeof optval); 602 if (error) 603 break; 604 605 switch (sopt->sopt_name) { 606 case TCP_NODELAY: 607 opt = TF_NODELAY; 608 break; 609 case TCP_NOOPT: 610 opt = TF_NOOPT; 611 break; 612 case TCP_NOPUSH: 613 opt = TF_NOPUSH; 614 break; 615 default: 616 opt = 0; /* dead code to fool gcc */ 617 break; 618 } 619 620 if (optval) 621 tp->t_flags |= opt; 622 else 623 tp->t_flags &= ~opt; 624 break; 625 626 case TCP_MAXSEG: 627 error = sooptcopyin(sopt, &optval, sizeof optval, 628 sizeof optval); 629 if (error) 630 break; 631 632 if (optval > 0 && optval <= tp->t_maxseg) 633 tp->t_maxseg = optval; 634 else 635 error = EINVAL; 636 break; 637 638 default: 639 error = ENOPROTOOPT; 640 break; 641 } 642 break; 643 644 case SOPT_GET: 645 switch (sopt->sopt_name) { 646 case TCP_NODELAY: 647 optval = tp->t_flags & TF_NODELAY; 648 break; 649 case TCP_MAXSEG: 650 optval = tp->t_maxseg; 651 break; 652 case TCP_NOOPT: 653 optval = tp->t_flags & TF_NOOPT; 654 break; 655 case TCP_NOPUSH: 656 optval = tp->t_flags & TF_NOPUSH; 657 break; 658 default: 659 error = ENOPROTOOPT; 660 break; 661 } 662 if (error == 0) 663 error = sooptcopyout(sopt, &optval, sizeof optval); 664 break; 665 } 666 splx(s); 667 return (error); 668 } 669 670 /* 671 * tcp_sendspace and tcp_recvspace are the default send and receive window 672 * sizes, respectively. These are obsolescent (this information should 673 * be set by the route). 674 */ 675 u_long tcp_sendspace = 1024*16; 676 SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, 677 CTLFLAG_RW, &tcp_sendspace , 0, ""); 678 u_long tcp_recvspace = 1024*16; 679 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, 680 CTLFLAG_RW, &tcp_recvspace , 0, ""); 681 682 /* 683 * Attach TCP protocol to socket, allocating 684 * internet protocol control block, tcp control block, 685 * bufer space, and entering LISTEN state if to accept connections. 686 */ 687 static int 688 tcp_attach(so, p) 689 struct socket *so; 690 struct proc *p; 691 { 692 register struct tcpcb *tp; 693 struct inpcb *inp; 694 int error; 695 696 if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { 697 error = soreserve(so, tcp_sendspace, tcp_recvspace); 698 if (error) 699 return (error); 700 } 701 error = in_pcballoc(so, &tcbinfo, p); 702 if (error) 703 return (error); 704 inp = sotoinpcb(so); 705 tp = tcp_newtcpcb(inp); 706 if (tp == 0) { 707 int nofd = so->so_state & SS_NOFDREF; /* XXX */ 708 709 so->so_state &= ~SS_NOFDREF; /* don't free the socket yet */ 710 in_pcbdetach(inp); 711 so->so_state |= nofd; 712 return (ENOBUFS); 713 } 714 tp->t_state = TCPS_CLOSED; 715 return (0); 716 } 717 718 /* 719 * Initiate (or continue) disconnect. 720 * If embryonic state, just send reset (once). 721 * If in ``let data drain'' option and linger null, just drop. 722 * Otherwise (hard), mark socket disconnecting and drop 723 * current input data; switch states based on user close, and 724 * send segment to peer (with FIN). 725 */ 726 static struct tcpcb * 727 tcp_disconnect(tp) 728 register struct tcpcb *tp; 729 { 730 struct socket *so = tp->t_inpcb->inp_socket; 731 732 if (tp->t_state < TCPS_ESTABLISHED) 733 tp = tcp_close(tp); 734 else if ((so->so_options & SO_LINGER) && so->so_linger == 0) 735 tp = tcp_drop(tp, 0); 736 else { 737 soisdisconnecting(so); 738 sbflush(&so->so_rcv); 739 tp = tcp_usrclosed(tp); 740 if (tp) 741 (void) tcp_output(tp); 742 } 743 return (tp); 744 } 745 746 /* 747 * User issued close, and wish to trail through shutdown states: 748 * if never received SYN, just forget it. If got a SYN from peer, 749 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN. 750 * If already got a FIN from peer, then almost done; go to LAST_ACK 751 * state. In all other cases, have already sent FIN to peer (e.g. 752 * after PRU_SHUTDOWN), and just have to play tedious game waiting 753 * for peer to send FIN or not respond to keep-alives, etc. 754 * We can let the user exit from the close as soon as the FIN is acked. 755 */ 756 static struct tcpcb * 757 tcp_usrclosed(tp) 758 register struct tcpcb *tp; 759 { 760 761 switch (tp->t_state) { 762 763 case TCPS_CLOSED: 764 case TCPS_LISTEN: 765 tp->t_state = TCPS_CLOSED; 766 tp = tcp_close(tp); 767 break; 768 769 case TCPS_SYN_SENT: 770 case TCPS_SYN_RECEIVED: 771 tp->t_flags |= TF_NEEDFIN; 772 break; 773 774 case TCPS_ESTABLISHED: 775 tp->t_state = TCPS_FIN_WAIT_1; 776 break; 777 778 case TCPS_CLOSE_WAIT: 779 tp->t_state = TCPS_LAST_ACK; 780 break; 781 } 782 if (tp && tp->t_state >= TCPS_FIN_WAIT_2) { 783 soisdisconnected(tp->t_inpcb->inp_socket); 784 /* To prevent the connection hanging in FIN_WAIT_2 forever. */ 785 if (tp->t_state == TCPS_FIN_WAIT_2) 786 tp->t_timer[TCPT_2MSL] = tcp_maxidle; 787 } 788 return (tp); 789 } 790 791