sys/netinet/tcp_usrreq.c

   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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      From: @(#)tcp_usrreq.c  8.2 (Berkeley) 1/3/94
  30  * $FreeBSD$
  31  */
  32
  33 #include "opt_inet.h"
  34 #include "opt_inet6.h"
  35 #include "opt_tcpdebug.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/malloc.h>
  40 #include <sys/kernel.h>
  41 #include <sys/sysctl.h>
  42 #include <sys/mbuf.h>
  43 #ifdef INET6
  44 #include <sys/domain.h>
  45 #endif /* INET6 */
  46 #include <sys/socket.h>
  47 #include <sys/socketvar.h>
  48 #include <sys/protosw.h>
  49 #include <sys/proc.h>
  50 #include <sys/jail.h>
  51
  52 #include <net/if.h>
  53 #include <net/route.h>
  54
  55 #include <netinet/in.h>
  56 #include <netinet/in_systm.h>
  57 #ifdef INET6
  58 #include <netinet/ip6.h>
  59 #endif
  60 #include <netinet/in_pcb.h>
  61 #ifdef INET6
  62 #include <netinet6/in6_pcb.h>
  63 #endif
  64 #include <netinet/in_var.h>
  65 #include <netinet/ip_var.h>
  66 #ifdef INET6
  67 #include <netinet6/ip6_var.h>
  68 #include <netinet6/scope6_var.h>
  69 #endif
  70 #include <netinet/tcp.h>
  71 #include <netinet/tcp_fsm.h>
  72 #include <netinet/tcp_seq.h>
  73 #include <netinet/tcp_timer.h>
  74 #include <netinet/tcp_var.h>
  75 #include <netinet/tcpip.h>
  76 #ifdef TCPDEBUG
  77 #include <netinet/tcp_debug.h>
  78 #endif
  79
  80 /*
  81  * TCP protocol interface to socket abstraction.
  82  */
  83 extern  char *tcpstates[];      /* XXX ??? */
  84
  85 static int      tcp_attach(struct socket *);
  86 static int      tcp_connect(struct tcpcb *, struct sockaddr *,
  87                     struct thread *td);
  88 #ifdef INET6
  89 static int      tcp6_connect(struct tcpcb *, struct sockaddr *,
  90                     struct thread *td);
  91 #endif /* INET6 */
  92 static struct tcpcb *
  93                 tcp_disconnect(struct tcpcb *);
  94 static struct tcpcb *
  95                 tcp_usrclosed(struct tcpcb *);
  96 static void     tcp_fill_info(struct tcpcb *, struct tcp_info *);
  97
  98 #ifdef TCPDEBUG
  99 #define TCPDEBUG0       int ostate = 0
 100 #define TCPDEBUG1()     ostate = tp ? tp->t_state : 0
 101 #define TCPDEBUG2(req)  if (tp && (so->so_options & SO_DEBUG)) \
 102                                 tcp_trace(TA_USER, ostate, tp, 0, 0, req)
 103 #else
 104 #define TCPDEBUG0
 105 #define TCPDEBUG1()
 106 #define TCPDEBUG2(req)
 107 #endif
 108
 109 /*
 110  * TCP attaches to socket via pru_attach(), reserving space,
 111  * and an internet control block.
 112  */
 113 static int
 114 tcp_usr_attach(struct socket *so, int proto, struct thread *td)
 115 {
 116         int error;
 117         struct inpcb *inp;
 118         struct tcpcb *tp = 0;
 119         TCPDEBUG0;
 120
 121         INP_INFO_WLOCK(&tcbinfo);
 122         TCPDEBUG1();
 123         inp = sotoinpcb(so);
 124         if (inp) {
 125                 error = EISCONN;
 126                 goto out;
 127         }
 128
 129         error = tcp_attach(so);
 130         if (error)
 131                 goto out;
 132
 133         if ((so->so_options & SO_LINGER) && so->so_linger == 0)
 134                 so->so_linger = TCP_LINGERTIME;
 135
 136         inp = sotoinpcb(so);
 137         tp = intotcpcb(inp);
 138 out:
 139         TCPDEBUG2(PRU_ATTACH);
 140         INP_INFO_WUNLOCK(&tcbinfo);
 141         return error;
 142 }
 143
 144 /*
 145  * pru_detach() detaches the TCP protocol from the socket.
 146  * If the protocol state is non-embryonic, then can't
 147  * do this directly: have to initiate a pru_disconnect(),
 148  * which may finish later; embryonic TCB's can just
 149  * be discarded here.
 150  */
 151 static int
 152 tcp_usr_detach(struct socket *so)
 153 {
 154         int error = 0;
 155         struct inpcb *inp;
 156         struct tcpcb *tp;
 157         TCPDEBUG0;
 158
 159         INP_INFO_WLOCK(&tcbinfo);
 160         inp = sotoinpcb(so);
 161         if (inp == NULL) {
 162                 INP_INFO_WUNLOCK(&tcbinfo);
 163                 return error;
 164         }
 165         INP_LOCK(inp);
 166         tp = intotcpcb(inp);
 167         TCPDEBUG1();
 168         tp = tcp_disconnect(tp);
 169
 170         TCPDEBUG2(PRU_DETACH);
 171         if (tp)
 172                 INP_UNLOCK(inp);
 173         INP_INFO_WUNLOCK(&tcbinfo);
 174         return error;
 175 }
 176
 177 #define INI_NOLOCK      0
 178 #define INI_READ        1
 179 #define INI_WRITE       2
 180
 181 #define COMMON_START()                                          \
 182         TCPDEBUG0;                                              \
 183         do {                                                    \
 184                 if (inirw == INI_READ)                          \
 185                         INP_INFO_RLOCK(&tcbinfo);               \
 186                 else if (inirw == INI_WRITE)                    \
 187                         INP_INFO_WLOCK(&tcbinfo);               \
 188                 inp = sotoinpcb(so);                            \
 189                 if (inp == 0) {                                 \
 190                         if (inirw == INI_READ)                  \
 191                                 INP_INFO_RUNLOCK(&tcbinfo);     \
 192                         else if (inirw == INI_WRITE)            \
 193                                 INP_INFO_WUNLOCK(&tcbinfo);     \
 194                         return EINVAL;                          \
 195                 }                                               \
 196                 INP_LOCK(inp);                                  \
 197                 if (inirw == INI_READ)                          \
 198                         INP_INFO_RUNLOCK(&tcbinfo);             \
 199                 tp = intotcpcb(inp);                            \
 200                 TCPDEBUG1();                                    \
 201 } while(0)
 202
 203 #define COMMON_END(req)                                         \
 204 out:    TCPDEBUG2(req);                                         \
 205         do {                                                    \
 206                 if (tp)                                         \
 207                         INP_UNLOCK(inp);                        \
 208                 if (inirw == INI_WRITE)                         \
 209                         INP_INFO_WUNLOCK(&tcbinfo);             \
 210                 return error;                                   \
 211                 goto out;                                       \
 212 } while(0)
 213
 214 /*
 215  * Give the socket an address.
 216  */
 217 static int
 218 tcp_usr_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
 219 {
 220         int error = 0;
 221         struct inpcb *inp;
 222         struct tcpcb *tp;
 223         struct sockaddr_in *sinp;
 224         const int inirw = INI_WRITE;
 225
 226         sinp = (struct sockaddr_in *)nam;
 227         if (nam->sa_len != sizeof (*sinp))
 228                 return (EINVAL);
 229         /*
 230          * Must check for multicast addresses and disallow binding
 231          * to them.
 232          */
 233         if (sinp->sin_family == AF_INET &&
 234             IN_MULTICAST(ntohl(sinp->sin_addr.s_addr)))
 235                 return (EAFNOSUPPORT);
 236
 237         COMMON_START();
 238         error = in_pcbbind(inp, nam, td->td_ucred);
 239         if (error)
 240                 goto out;
 241         COMMON_END(PRU_BIND);
 242 }
 243
 244 #ifdef INET6
 245 static int
 246 tcp6_usr_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
 247 {
 248         int error = 0;
 249         struct inpcb *inp;
 250         struct tcpcb *tp;
 251         struct sockaddr_in6 *sin6p;
 252         const int inirw = INI_WRITE;
 253
 254         sin6p = (struct sockaddr_in6 *)nam;
 255         if (nam->sa_len != sizeof (*sin6p))
 256                 return (EINVAL);
 257         /*
 258          * Must check for multicast addresses and disallow binding
 259          * to them.
 260          */
 261         if (sin6p->sin6_family == AF_INET6 &&
 262             IN6_IS_ADDR_MULTICAST(&sin6p->sin6_addr))
 263                 return (EAFNOSUPPORT);
 264
 265         COMMON_START();
 266         inp->inp_vflag &= ~INP_IPV4;
 267         inp->inp_vflag |= INP_IPV6;
 268         if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
 269                 if (IN6_IS_ADDR_UNSPECIFIED(&sin6p->sin6_addr))
 270                         inp->inp_vflag |= INP_IPV4;
 271                 else if (IN6_IS_ADDR_V4MAPPED(&sin6p->sin6_addr)) {
 272                         struct sockaddr_in sin;
 273
 274                         in6_sin6_2_sin(&sin, sin6p);
 275                         inp->inp_vflag |= INP_IPV4;
 276                         inp->inp_vflag &= ~INP_IPV6;
 277                         error = in_pcbbind(inp, (struct sockaddr *)&sin,
 278                             td->td_ucred);
 279                         goto out;
 280                 }
 281         }
 282         error = in6_pcbbind(inp, nam, td->td_ucred);
 283         if (error)
 284                 goto out;
 285         COMMON_END(PRU_BIND);
 286 }
 287 #endif /* INET6 */
 288
 289 /*
 290  * Prepare to accept connections.
 291  */
 292 static int
 293 tcp_usr_listen(struct socket *so, int backlog, struct thread *td)
 294 {
 295         int error = 0;
 296         struct inpcb *inp;
 297         struct tcpcb *tp;
 298         const int inirw = INI_WRITE;
 299
 300         COMMON_START();
 301         SOCK_LOCK(so);
 302         error = solisten_proto_check(so);
 303         if (error == 0 && inp->inp_lport == 0)
 304                 error = in_pcbbind(inp, (struct sockaddr *)0, td->td_ucred);
 305         if (error == 0) {
 306                 tp->t_state = TCPS_LISTEN;
 307                 solisten_proto(so, backlog);
 308         }
 309         SOCK_UNLOCK(so);
 310         COMMON_END(PRU_LISTEN);
 311 }
 312
 313 #ifdef INET6
 314 static int
 315 tcp6_usr_listen(struct socket *so, int backlog, struct thread *td)
 316 {
 317         int error = 0;
 318         struct inpcb *inp;
 319         struct tcpcb *tp;
 320         const int inirw = INI_WRITE;
 321
 322         COMMON_START();
 323         SOCK_LOCK(so);
 324         error = solisten_proto_check(so);
 325         if (error == 0 && inp->inp_lport == 0) {
 326                 inp->inp_vflag &= ~INP_IPV4;
 327                 if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0)
 328                         inp->inp_vflag |= INP_IPV4;
 329                 error = in6_pcbbind(inp, (struct sockaddr *)0, td->td_ucred);
 330         }
 331         if (error == 0) {
 332                 tp->t_state = TCPS_LISTEN;
 333                 solisten_proto(so, backlog);
 334         }
 335         SOCK_UNLOCK(so);
 336         COMMON_END(PRU_LISTEN);
 337 }
 338 #endif /* INET6 */
 339
 340 /*
 341  * Initiate connection to peer.
 342  * Create a template for use in transmissions on this connection.
 343  * Enter SYN_SENT state, and mark socket as connecting.
 344  * Start keep-alive timer, and seed output sequence space.
 345  * Send initial segment on connection.
 346  */
 347 static int
 348 tcp_usr_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
 349 {
 350         int error = 0;
 351         struct inpcb *inp;
 352         struct tcpcb *tp;
 353         struct sockaddr_in *sinp;
 354         const int inirw = INI_WRITE;
 355
 356         sinp = (struct sockaddr_in *)nam;
 357         if (nam->sa_len != sizeof (*sinp))
 358                 return (EINVAL);
 359         /*
 360          * Must disallow TCP ``connections'' to multicast addresses.
 361          */
 362         if (sinp->sin_family == AF_INET
 363             && IN_MULTICAST(ntohl(sinp->sin_addr.s_addr)))
 364                 return (EAFNOSUPPORT);
 365         if (jailed(td->td_ucred))
 366                 prison_remote_ip(td->td_ucred, 0, &sinp->sin_addr.s_addr);
 367
 368         COMMON_START();
 369         if ((error = tcp_connect(tp, nam, td)) != 0)
 370                 goto out;
 371         error = tcp_output(tp);
 372         COMMON_END(PRU_CONNECT);
 373 }
 374
 375 #ifdef INET6
 376 static int
 377 tcp6_usr_connect(struct socket *so, struct sockaddr *nam, struct thread *td)
 378 {
 379         int error = 0;
 380         struct inpcb *inp;
 381         struct tcpcb *tp;
 382         struct sockaddr_in6 *sin6p;
 383         const int inirw = INI_WRITE;
 384
 385         sin6p = (struct sockaddr_in6 *)nam;
 386         if (nam->sa_len != sizeof (*sin6p))
 387                 return (EINVAL);
 388         /*
 389          * Must disallow TCP ``connections'' to multicast addresses.
 390          */
 391         if (sin6p->sin6_family == AF_INET6
 392             && IN6_IS_ADDR_MULTICAST(&sin6p->sin6_addr))
 393                 return (EAFNOSUPPORT);
 394
 395         COMMON_START();
 396         if (IN6_IS_ADDR_V4MAPPED(&sin6p->sin6_addr)) {
 397                 struct sockaddr_in sin;
 398
 399                 if ((inp->inp_flags & IN6P_IPV6_V6ONLY) != 0) {
 400                         error = EINVAL;
 401                         goto out;
 402                 }
 403
 404                 in6_sin6_2_sin(&sin, sin6p);
 405                 inp->inp_vflag |= INP_IPV4;
 406                 inp->inp_vflag &= ~INP_IPV6;
 407                 if ((error = tcp_connect(tp, (struct sockaddr *)&sin, td)) != 0)
 408                         goto out;
 409                 error = tcp_output(tp);
 410                 goto out;
 411         }
 412         inp->inp_vflag &= ~INP_IPV4;
 413         inp->inp_vflag |= INP_IPV6;
 414         inp->inp_inc.inc_isipv6 = 1;
 415         if ((error = tcp6_connect(tp, nam, td)) != 0)
 416                 goto out;
 417         error = tcp_output(tp);
 418         COMMON_END(PRU_CONNECT);
 419 }
 420 #endif /* INET6 */
 421
 422 /*
 423  * Initiate disconnect from peer.
 424  * If connection never passed embryonic stage, just drop;
 425  * else if don't need to let data drain, then can just drop anyways,
 426  * else have to begin TCP shutdown process: mark socket disconnecting,
 427  * drain unread data, state switch to reflect user close, and
 428  * send segment (e.g. FIN) to peer.  Socket will be really disconnected
 429  * when peer sends FIN and acks ours.
 430  *
 431  * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
 432  */
 433 static int
 434 tcp_usr_disconnect(struct socket *so)
 435 {
 436         int error = 0;
 437         struct inpcb *inp;
 438         struct tcpcb *tp;
 439         const int inirw = INI_WRITE;
 440
 441         COMMON_START();
 442         tp = tcp_disconnect(tp);
 443         COMMON_END(PRU_DISCONNECT);
 444 }
 445
 446 /*
 447  * Accept a connection.  Essentially all the work is
 448  * done at higher levels; just return the address
 449  * of the peer, storing through addr.
 450  */
 451 static int
 452 tcp_usr_accept(struct socket *so, struct sockaddr **nam)
 453 {
 454         int error = 0;
 455         struct inpcb *inp = NULL;
 456         struct tcpcb *tp = NULL;
 457         struct in_addr addr;
 458         in_port_t port = 0;
 459         TCPDEBUG0;
 460
 461         if (so->so_state & SS_ISDISCONNECTED) {
 462                 error = ECONNABORTED;
 463                 goto out;
 464         }
 465
 466         INP_INFO_RLOCK(&tcbinfo);
 467         inp = sotoinpcb(so);
 468         if (!inp) {
 469                 INP_INFO_RUNLOCK(&tcbinfo);
 470                 return (EINVAL);
 471         }
 472         INP_LOCK(inp);
 473         INP_INFO_RUNLOCK(&tcbinfo);
 474         tp = intotcpcb(inp);
 475         TCPDEBUG1();
 476
 477         /*
 478          * We inline in_setpeeraddr and COMMON_END here, so that we can
 479          * copy the data of interest and defer the malloc until after we
 480          * release the lock.
 481          */
 482         port = inp->inp_fport;
 483         addr = inp->inp_faddr;
 484
 485 out:    TCPDEBUG2(PRU_ACCEPT);
 486         if (tp)
 487                 INP_UNLOCK(inp);
 488         if (error == 0)
 489                 *nam = in_sockaddr(port, &addr);
 490         return error;
 491 }
 492
 493 #ifdef INET6
 494 static int
 495 tcp6_usr_accept(struct socket *so, struct sockaddr **nam)
 496 {
 497         struct inpcb *inp = NULL;
 498         int error = 0;
 499         struct tcpcb *tp = NULL;
 500         struct in_addr addr;
 501         struct in6_addr addr6;
 502         in_port_t port = 0;
 503         int v4 = 0;
 504         TCPDEBUG0;
 505
 506         if (so->so_state & SS_ISDISCONNECTED) {
 507                 error = ECONNABORTED;
 508                 goto out;
 509         }
 510
 511         INP_INFO_RLOCK(&tcbinfo);
 512         inp = sotoinpcb(so);
 513         if (inp == 0) {
 514                 INP_INFO_RUNLOCK(&tcbinfo);
 515                 return (EINVAL);
 516         }
 517         INP_LOCK(inp);
 518         INP_INFO_RUNLOCK(&tcbinfo);
 519         tp = intotcpcb(inp);
 520         TCPDEBUG1();
 521         /*
 522          * We inline in6_mapped_peeraddr and COMMON_END here, so that we can
 523          * copy the data of interest and defer the malloc until after we
 524          * release the lock.
 525          */
 526         if (inp->inp_vflag & INP_IPV4) {
 527                 v4 = 1;
 528                 port = inp->inp_fport;
 529                 addr = inp->inp_faddr;
 530         } else {
 531                 port = inp->inp_fport;
 532                 addr6 = inp->in6p_faddr;
 533         }
 534
 535 out:    TCPDEBUG2(PRU_ACCEPT);
 536         if (tp)
 537                 INP_UNLOCK(inp);
 538         if (error == 0) {
 539                 if (v4)
 540                         *nam = in6_v4mapsin6_sockaddr(port, &addr);
 541                 else
 542                         *nam = in6_sockaddr(port, &addr6);
 543         }
 544         return error;
 545 }
 546 #endif /* INET6 */
 547
 548 /*
 549  * This is the wrapper function for in_setsockaddr. We just pass down
 550  * the pcbinfo for in_setsockaddr to lock. We don't want to do the locking
 551  * here because in_setsockaddr will call malloc and can block.
 552  */
 553 static int
 554 tcp_sockaddr(struct socket *so, struct sockaddr **nam)
 555 {
 556         return (in_setsockaddr(so, nam, &tcbinfo));
 557 }
 558
 559 /*
 560  * This is the wrapper function for in_setpeeraddr. We just pass down
 561  * the pcbinfo for in_setpeeraddr to lock.
 562  */
 563 static int
 564 tcp_peeraddr(struct socket *so, struct sockaddr **nam)
 565 {
 566         return (in_setpeeraddr(so, nam, &tcbinfo));
 567 }
 568
 569 /*
 570  * Mark the connection as being incapable of further output.
 571  */
 572 static int
 573 tcp_usr_shutdown(struct socket *so)
 574 {
 575         int error = 0;
 576         struct inpcb *inp;
 577         struct tcpcb *tp;
 578         const int inirw = INI_WRITE;
 579
 580         COMMON_START();
 581         socantsendmore(so);
 582         tp = tcp_usrclosed(tp);
 583         if (tp)
 584                 error = tcp_output(tp);
 585         COMMON_END(PRU_SHUTDOWN);
 586 }
 587
 588 /*
 589  * After a receive, possibly send window update to peer.
 590  */
 591 static int
 592 tcp_usr_rcvd(struct socket *so, int flags)
 593 {
 594         int error = 0;
 595         struct inpcb *inp;
 596         struct tcpcb *tp;
 597         const int inirw = INI_READ;
 598
 599         COMMON_START();
 600         tcp_output(tp);
 601         COMMON_END(PRU_RCVD);
 602 }
 603
 604 /*
 605  * Do a send by putting data in output queue and updating urgent
 606  * marker if URG set.  Possibly send more data.  Unlike the other
 607  * pru_*() routines, the mbuf chains are our responsibility.  We
 608  * must either enqueue them or free them.  The other pru_* routines
 609  * generally are caller-frees.
 610  */
 611 static int
 612 tcp_usr_send(struct socket *so, int flags, struct mbuf *m,
 613              struct sockaddr *nam, struct mbuf *control, struct thread *td)
 614 {
 615         int error = 0;
 616         struct inpcb *inp;
 617         struct tcpcb *tp;
 618         int unlocked = 0;
 619 #ifdef INET6
 620         int isipv6;
 621 #endif
 622         TCPDEBUG0;
 623
 624         /*
 625          * Need write lock here because this function might call
 626          * tcp_connect or tcp_usrclosed.
 627          * We really want to have to this function upgrade from read lock
 628          * to write lock.  XXX
 629          */
 630         INP_INFO_WLOCK(&tcbinfo);
 631         inp = sotoinpcb(so);
 632         if (inp == NULL) {
 633                 /*
 634                  * OOPS! we lost a race, the TCP session got reset after
 635                  * we checked SBS_CANTSENDMORE, eg: while doing uiomove or a
 636                  * network interrupt in the non-splnet() section of sosend().
 637                  */
 638                 if (m)
 639                         m_freem(m);
 640                 if (control)
 641                         m_freem(control);
 642                 error = ECONNRESET;     /* XXX EPIPE? */
 643                 tp = NULL;
 644                 TCPDEBUG1();
 645                 goto out;
 646         }
 647         INP_LOCK(inp);
 648 #ifdef INET6
 649         isipv6 = nam && nam->sa_family == AF_INET6;
 650 #endif /* INET6 */
 651         tp = intotcpcb(inp);
 652         TCPDEBUG1();
 653         if (control) {
 654                 /* TCP doesn't do control messages (rights, creds, etc) */
 655                 if (control->m_len) {
 656                         m_freem(control);
 657                         if (m)
 658                                 m_freem(m);
 659                         error = EINVAL;
 660                         goto out;
 661                 }
 662                 m_freem(control);       /* empty control, just free it */
 663         }
 664         if (!(flags & PRUS_OOB)) {
 665                 sbappendstream(&so->so_snd, m);
 666                 if (nam && tp->t_state < TCPS_SYN_SENT) {
 667                         /*
 668                          * Do implied connect if not yet connected,
 669                          * initialize window to default value, and
 670                          * initialize maxseg/maxopd using peer's cached
 671                          * MSS.
 672                          */
 673 #ifdef INET6
 674                         if (isipv6)
 675                                 error = tcp6_connect(tp, nam, td);
 676                         else
 677 #endif /* INET6 */
 678                         error = tcp_connect(tp, nam, td);
 679                         if (error)
 680                                 goto out;
 681                         tp->snd_wnd = TTCP_CLIENT_SND_WND;
 682                         tcp_mss(tp, -1);
 683                 }
 684
 685                 if (flags & PRUS_EOF) {
 686                         /*
 687                          * Close the send side of the connection after
 688                          * the data is sent.
 689                          */
 690                         socantsendmore(so);
 691                         tp = tcp_usrclosed(tp);
 692                 }
 693                 INP_INFO_WUNLOCK(&tcbinfo);
 694                 unlocked = 1;
 695                 if (tp != NULL) {
 696                         if (flags & PRUS_MORETOCOME)
 697                                 tp->t_flags |= TF_MORETOCOME;
 698                         error = tcp_output(tp);
 699                         if (flags & PRUS_MORETOCOME)
 700                                 tp->t_flags &= ~TF_MORETOCOME;
 701                 }
 702         } else {
 703                 SOCKBUF_LOCK(&so->so_snd);
 704                 if (sbspace(&so->so_snd) < -512) {
 705                         SOCKBUF_UNLOCK(&so->so_snd);
 706                         m_freem(m);
 707                         error = ENOBUFS;
 708                         goto out;
 709                 }
 710                 /*
 711                  * According to RFC961 (Assigned Protocols),
 712                  * the urgent pointer points to the last octet
 713                  * of urgent data.  We continue, however,
 714                  * to consider it to indicate the first octet
 715                  * of data past the urgent section.
 716                  * Otherwise, snd_up should be one lower.
 717                  */
 718                 sbappendstream_locked(&so->so_snd, m);
 719                 SOCKBUF_UNLOCK(&so->so_snd);
 720                 if (nam && tp->t_state < TCPS_SYN_SENT) {
 721                         /*
 722                          * Do implied connect if not yet connected,
 723                          * initialize window to default value, and
 724                          * initialize maxseg/maxopd using peer's cached
 725                          * MSS.
 726                          */
 727 #ifdef INET6
 728                         if (isipv6)
 729                                 error = tcp6_connect(tp, nam, td);
 730                         else
 731 #endif /* INET6 */
 732                         error = tcp_connect(tp, nam, td);
 733                         if (error)
 734                                 goto out;
 735                         tp->snd_wnd = TTCP_CLIENT_SND_WND;
 736                         tcp_mss(tp, -1);
 737                 }
 738                 INP_INFO_WUNLOCK(&tcbinfo);
 739                 unlocked = 1;
 740                 tp->snd_up = tp->snd_una + so->so_snd.sb_cc;
 741                 tp->t_flags |= TF_FORCEDATA;
 742                 error = tcp_output(tp);
 743                 tp->t_flags &= ~TF_FORCEDATA;
 744         }
 745 out:
 746         TCPDEBUG2((flags & PRUS_OOB) ? PRU_SENDOOB :
 747                   ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND));
 748         if (tp)
 749                 INP_UNLOCK(inp);
 750         if (!unlocked)
 751                 INP_INFO_WUNLOCK(&tcbinfo);
 752         return (error);
 753 }
 754
 755 /*
 756  * Abort the TCP.
 757  */
 758 static int
 759 tcp_usr_abort(struct socket *so)
 760 {
 761         int error = 0;
 762         struct inpcb *inp;
 763         struct tcpcb *tp;
 764         const int inirw = INI_WRITE;
 765
 766         COMMON_START();
 767         tp = tcp_drop(tp, ECONNABORTED);
 768         COMMON_END(PRU_ABORT);
 769 }
 770
 771 /*
 772  * Receive out-of-band data.
 773  */
 774 static int
 775 tcp_usr_rcvoob(struct socket *so, struct mbuf *m, int flags)
 776 {
 777         int error = 0;
 778         struct inpcb *inp;
 779         struct tcpcb *tp;
 780         const int inirw = INI_READ;
 781
 782         COMMON_START();
 783         if ((so->so_oobmark == 0 &&
 784              (so->so_rcv.sb_state & SBS_RCVATMARK) == 0) ||
 785             so->so_options & SO_OOBINLINE ||
 786             tp->t_oobflags & TCPOOB_HADDATA) {
 787                 error = EINVAL;
 788                 goto out;
 789         }
 790         if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
 791                 error = EWOULDBLOCK;
 792                 goto out;
 793         }
 794         m->m_len = 1;
 795         *mtod(m, caddr_t) = tp->t_iobc;
 796         if ((flags & MSG_PEEK) == 0)
 797                 tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA);
 798         COMMON_END(PRU_RCVOOB);
 799 }
 800
 801 struct pr_usrreqs tcp_usrreqs = {
 802         .pru_abort =            tcp_usr_abort,
 803         .pru_accept =           tcp_usr_accept,
 804         .pru_attach =           tcp_usr_attach,
 805         .pru_bind =             tcp_usr_bind,
 806         .pru_connect =          tcp_usr_connect,
 807         .pru_control =          in_control,
 808         .pru_detach =           tcp_usr_detach,
 809         .pru_disconnect =       tcp_usr_disconnect,
 810         .pru_listen =           tcp_usr_listen,
 811         .pru_peeraddr =         tcp_peeraddr,
 812         .pru_rcvd =             tcp_usr_rcvd,
 813         .pru_rcvoob =           tcp_usr_rcvoob,
 814         .pru_send =             tcp_usr_send,
 815         .pru_shutdown =         tcp_usr_shutdown,
 816         .pru_sockaddr =         tcp_sockaddr,
 817         .pru_sosetlabel =       in_pcbsosetlabel
 818 };
 819
 820 #ifdef INET6
 821 struct pr_usrreqs tcp6_usrreqs = {
 822         .pru_abort =            tcp_usr_abort,
 823         .pru_accept =           tcp6_usr_accept,
 824         .pru_attach =           tcp_usr_attach,
 825         .pru_bind =             tcp6_usr_bind,
 826         .pru_connect =          tcp6_usr_connect,
 827         .pru_control =          in6_control,
 828         .pru_detach =           tcp_usr_detach,
 829         .pru_disconnect =       tcp_usr_disconnect,
 830         .pru_listen =           tcp6_usr_listen,
 831         .pru_peeraddr =         in6_mapped_peeraddr,
 832         .pru_rcvd =             tcp_usr_rcvd,
 833         .pru_rcvoob =           tcp_usr_rcvoob,
 834         .pru_send =             tcp_usr_send,
 835         .pru_shutdown =         tcp_usr_shutdown,
 836         .pru_sockaddr =         in6_mapped_sockaddr,
 837         .pru_sosetlabel =       in_pcbsosetlabel
 838 };
 839 #endif /* INET6 */
 840
 841 /*
 842  * Common subroutine to open a TCP connection to remote host specified
 843  * by struct sockaddr_in in mbuf *nam.  Call in_pcbbind to assign a local
 844  * port number if needed.  Call in_pcbconnect_setup to do the routing and
 845  * to choose a local host address (interface).  If there is an existing
 846  * incarnation of the same connection in TIME-WAIT state and if the remote
 847  * host was sending CC options and if the connection duration was < MSL, then
 848  * truncate the previous TIME-WAIT state and proceed.
 849  * Initialize connection parameters and enter SYN-SENT state.
 850  */
 851 static int
 852 tcp_connect(tp, nam, td)
 853         register struct tcpcb *tp;
 854         struct sockaddr *nam;
 855         struct thread *td;
 856 {
 857         struct inpcb *inp = tp->t_inpcb, *oinp;
 858         struct socket *so = inp->inp_socket;
 859         struct in_addr laddr;
 860         u_short lport;
 861         int error;
 862
 863         if (inp->inp_lport == 0) {
 864                 error = in_pcbbind(inp, (struct sockaddr *)0, td->td_ucred);
 865                 if (error)
 866                         return error;
 867         }
 868
 869         /*
 870          * Cannot simply call in_pcbconnect, because there might be an
 871          * earlier incarnation of this same connection still in
 872          * TIME_WAIT state, creating an ADDRINUSE error.
 873          */
 874         laddr = inp->inp_laddr;
 875         lport = inp->inp_lport;
 876         error = in_pcbconnect_setup(inp, nam, &laddr.s_addr, &lport,
 877             &inp->inp_faddr.s_addr, &inp->inp_fport, &oinp, td->td_ucred);
 878         if (error && oinp == NULL)
 879                 return error;
 880         if (oinp)
 881                 return EADDRINUSE;
 882         inp->inp_laddr = laddr;
 883         in_pcbrehash(inp);
 884
 885         /* Compute window scaling to request.  */
 886         while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 887             (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 888                 tp->request_r_scale++;
 889
 890         soisconnecting(so);
 891         tcpstat.tcps_connattempt++;
 892         tp->t_state = TCPS_SYN_SENT;
 893         callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
 894         tp->iss = tcp_new_isn(tp);
 895         tp->t_bw_rtseq = tp->iss;
 896         tcp_sendseqinit(tp);
 897
 898         return 0;
 899 }
 900
 901 #ifdef INET6
 902 static int
 903 tcp6_connect(tp, nam, td)
 904         register struct tcpcb *tp;
 905         struct sockaddr *nam;
 906         struct thread *td;
 907 {
 908         struct inpcb *inp = tp->t_inpcb, *oinp;
 909         struct socket *so = inp->inp_socket;
 910         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)nam;
 911         struct in6_addr *addr6;
 912         int error;
 913
 914         if (inp->inp_lport == 0) {
 915                 error = in6_pcbbind(inp, (struct sockaddr *)0, td->td_ucred);
 916                 if (error)
 917                         return error;
 918         }
 919
 920         /*
 921          * Cannot simply call in_pcbconnect, because there might be an
 922          * earlier incarnation of this same connection still in
 923          * TIME_WAIT state, creating an ADDRINUSE error.
 924          * in6_pcbladdr() also handles scope zone IDs.
 925          */
 926         error = in6_pcbladdr(inp, nam, &addr6);
 927         if (error)
 928                 return error;
 929         oinp = in6_pcblookup_hash(inp->inp_pcbinfo,
 930                                   &sin6->sin6_addr, sin6->sin6_port,
 931                                   IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)
 932                                   ? addr6
 933                                   : &inp->in6p_laddr,
 934                                   inp->inp_lport,  0, NULL);
 935         if (oinp)
 936                 return EADDRINUSE;
 937         if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
 938                 inp->in6p_laddr = *addr6;
 939         inp->in6p_faddr = sin6->sin6_addr;
 940         inp->inp_fport = sin6->sin6_port;
 941         /* update flowinfo - draft-itojun-ipv6-flowlabel-api-00 */
 942         inp->in6p_flowinfo &= ~IPV6_FLOWLABEL_MASK;
 943         if (inp->in6p_flags & IN6P_AUTOFLOWLABEL)
 944                 inp->in6p_flowinfo |=
 945                     (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK);
 946         in_pcbrehash(inp);
 947
 948         /* Compute window scaling to request.  */
 949         while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
 950             (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
 951                 tp->request_r_scale++;
 952
 953         soisconnecting(so);
 954         tcpstat.tcps_connattempt++;
 955         tp->t_state = TCPS_SYN_SENT;
 956         callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp);
 957         tp->iss = tcp_new_isn(tp);
 958         tp->t_bw_rtseq = tp->iss;
 959         tcp_sendseqinit(tp);
 960
 961         return 0;
 962 }
 963 #endif /* INET6 */
 964
 965 /*
 966  * Export TCP internal state information via a struct tcp_info, based on the
 967  * Linux 2.6 API.  Not ABI compatible as our constants are mapped differently
 968  * (TCP state machine, etc).  We export all information using FreeBSD-native
 969  * constants -- for example, the numeric values for tcpi_state will differ
 970  * from Linux.
 971  */
 972 static void
 973 tcp_fill_info(tp, ti)
 974         struct tcpcb *tp;
 975         struct tcp_info *ti;
 976 {
 977
 978         INP_LOCK_ASSERT(tp->t_inpcb);
 979         bzero(ti, sizeof(*ti));
 980
 981         ti->tcpi_state = tp->t_state;
 982         if ((tp->t_flags & TF_REQ_TSTMP) && (tp->t_flags & TF_RCVD_TSTMP))
 983                 ti->tcpi_options |= TCPI_OPT_TIMESTAMPS;
 984         if (tp->sack_enable)
 985                 ti->tcpi_options |= TCPI_OPT_SACK;
 986         if ((tp->t_flags & TF_REQ_SCALE) && (tp->t_flags & TF_RCVD_SCALE)) {
 987                 ti->tcpi_options |= TCPI_OPT_WSCALE;
 988                 ti->tcpi_snd_wscale = tp->snd_scale;
 989                 ti->tcpi_rcv_wscale = tp->rcv_scale;
 990         }
 991         ti->tcpi_snd_ssthresh = tp->snd_ssthresh;
 992         ti->tcpi_snd_cwnd = tp->snd_cwnd;
 993
 994         /*
 995          * FreeBSD-specific extension fields for tcp_info.
 996          */
 997         ti->tcpi_rcv_space = tp->rcv_wnd;
 998         ti->tcpi_snd_wnd = tp->snd_wnd;
 999         ti->tcpi_snd_bwnd = tp->snd_bwnd;
1000 }
1001
1002 /*
1003  * The new sockopt interface makes it possible for us to block in the
1004  * copyin/out step (if we take a page fault).  Taking a page fault at
1005  * splnet() is probably a Bad Thing.  (Since sockets and pcbs both now
1006  * use TSM, there probably isn't any need for this function to run at
1007  * splnet() any more.  This needs more examination.)
1008  *
1009  * XXXRW: The locking here is wrong; we may take a page fault while holding
1010  * the inpcb lock.
1011  */
1012 int
1013 tcp_ctloutput(so, sopt)
1014         struct socket *so;
1015         struct sockopt *sopt;
1016 {
1017         int     error, opt, optval;
1018         struct  inpcb *inp;
1019         struct  tcpcb *tp;
1020         struct  tcp_info ti;
1021
1022         error = 0;
1023         INP_INFO_RLOCK(&tcbinfo);
1024         inp = sotoinpcb(so);
1025         if (inp == NULL) {
1026                 INP_INFO_RUNLOCK(&tcbinfo);
1027                 return (ECONNRESET);
1028         }
1029         INP_LOCK(inp);
1030         INP_INFO_RUNLOCK(&tcbinfo);
1031         if (sopt->sopt_level != IPPROTO_TCP) {
1032                 INP_UNLOCK(inp);
1033 #ifdef INET6
1034                 if (INP_CHECK_SOCKAF(so, AF_INET6))
1035                         error = ip6_ctloutput(so, sopt);
1036                 else
1037 #endif /* INET6 */
1038                 error = ip_ctloutput(so, sopt);
1039                 return (error);
1040         }
1041         tp = intotcpcb(inp);
1042
1043         switch (sopt->sopt_dir) {
1044         case SOPT_SET:
1045                 switch (sopt->sopt_name) {
1046 #ifdef TCP_SIGNATURE
1047                 case TCP_MD5SIG:
1048                         error = sooptcopyin(sopt, &optval, sizeof optval,
1049                                             sizeof optval);
1050                         if (error)
1051                                 break;
1052
1053                         if (optval > 0)
1054                                 tp->t_flags |= TF_SIGNATURE;
1055                         else
1056                                 tp->t_flags &= ~TF_SIGNATURE;
1057                         break;
1058 #endif /* TCP_SIGNATURE */
1059                 case TCP_NODELAY:
1060                 case TCP_NOOPT:
1061                         error = sooptcopyin(sopt, &optval, sizeof optval,
1062                                             sizeof optval);
1063                         if (error)
1064                                 break;
1065
1066                         switch (sopt->sopt_name) {
1067                         case TCP_NODELAY:
1068                                 opt = TF_NODELAY;
1069                                 break;
1070                         case TCP_NOOPT:
1071                                 opt = TF_NOOPT;
1072                                 break;
1073                         default:
1074                                 opt = 0; /* dead code to fool gcc */
1075                                 break;
1076                         }
1077
1078                         if (optval)
1079                                 tp->t_flags |= opt;
1080                         else
1081                                 tp->t_flags &= ~opt;
1082                         break;
1083
1084                 case TCP_NOPUSH:
1085                         error = sooptcopyin(sopt, &optval, sizeof optval,
1086                                             sizeof optval);
1087                         if (error)
1088                                 break;
1089
1090                         if (optval)
1091                                 tp->t_flags |= TF_NOPUSH;
1092                         else {
1093                                 tp->t_flags &= ~TF_NOPUSH;
1094                                 error = tcp_output(tp);
1095                         }
1096                         break;
1097
1098                 case TCP_MAXSEG:
1099                         error = sooptcopyin(sopt, &optval, sizeof optval,
1100                                             sizeof optval);
1101                         if (error)
1102                                 break;
1103
1104                         if (optval > 0 && optval <= tp->t_maxseg &&
1105                             optval + 40 >= tcp_minmss)
1106                                 tp->t_maxseg = optval;
1107                         else
1108                                 error = EINVAL;
1109                         break;
1110
1111                 case TCP_INFO:
1112                         error = EINVAL;
1113                         break;
1114
1115                 default:
1116                         error = ENOPROTOOPT;
1117                         break;
1118                 }
1119                 break;
1120
1121         case SOPT_GET:
1122                 switch (sopt->sopt_name) {
1123 #ifdef TCP_SIGNATURE
1124                 case TCP_MD5SIG:
1125                         optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;
1126                         error = sooptcopyout(sopt, &optval, sizeof optval);
1127                         break;
1128 #endif
1129                 case TCP_NODELAY:
1130                         optval = tp->t_flags & TF_NODELAY;
1131                         error = sooptcopyout(sopt, &optval, sizeof optval);
1132                         break;
1133                 case TCP_MAXSEG:
1134                         optval = tp->t_maxseg;
1135                         error = sooptcopyout(sopt, &optval, sizeof optval);
1136                         break;
1137                 case TCP_NOOPT:
1138                         optval = tp->t_flags & TF_NOOPT;
1139                         error = sooptcopyout(sopt, &optval, sizeof optval);
1140                         break;
1141                 case TCP_NOPUSH:
1142                         optval = tp->t_flags & TF_NOPUSH;
1143                         error = sooptcopyout(sopt, &optval, sizeof optval);
1144                         break;
1145                 case TCP_INFO:
1146                         tcp_fill_info(tp, &ti);
1147                         error = sooptcopyout(sopt, &ti, sizeof ti);
1148                         break;
1149                 default:
1150                         error = ENOPROTOOPT;
1151                         break;
1152                 }
1153                 break;
1154         }
1155         INP_UNLOCK(inp);
1156         return (error);
1157 }
1158
1159 /*
1160  * tcp_sendspace and tcp_recvspace are the default send and receive window
1161  * sizes, respectively.  These are obsolescent (this information should
1162  * be set by the route).
1163  */
1164 u_long  tcp_sendspace = 1024*32;
1165 SYSCTL_ULONG(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_RW,
1166     &tcp_sendspace , 0, "Maximum outgoing TCP datagram size");
1167 u_long  tcp_recvspace = 1024*64;
1168 SYSCTL_ULONG(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_RW,
1169     &tcp_recvspace , 0, "Maximum incoming TCP datagram size");
1170
1171 /*
1172  * Attach TCP protocol to socket, allocating
1173  * internet protocol control block, tcp control block,
1174  * bufer space, and entering LISTEN state if to accept connections.
1175  */
1176 static int
1177 tcp_attach(so)
1178         struct socket *so;
1179 {
1180         register struct tcpcb *tp;
1181         struct inpcb *inp;
1182         int error;
1183 #ifdef INET6
1184         int isipv6 = INP_CHECK_SOCKAF(so, AF_INET6) != 0;
1185 #endif
1186
1187         INP_INFO_WLOCK_ASSERT(&tcbinfo);
1188
1189         if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
1190                 error = soreserve(so, tcp_sendspace, tcp_recvspace);
1191                 if (error)
1192                         return (error);
1193         }
1194         error = in_pcballoc(so, &tcbinfo, "tcpinp");
1195         if (error)
1196                 return (error);
1197         inp = sotoinpcb(so);
1198 #ifdef INET6
1199         if (isipv6) {
1200                 inp->inp_vflag |= INP_IPV6;
1201                 inp->in6p_hops = -1;    /* use kernel default */
1202         }
1203         else
1204 #endif
1205         inp->inp_vflag |= INP_IPV4;
1206         tp = tcp_newtcpcb(inp);
1207         if (tp == 0) {
1208                 int nofd = so->so_state & SS_NOFDREF;   /* XXX */
1209
1210                 so->so_state &= ~SS_NOFDREF;    /* don't free the socket yet */
1211
1212                 INP_LOCK(inp);
1213 #ifdef INET6
1214                 if (isipv6)
1215                         in6_pcbdetach(inp);
1216                 else
1217 #endif
1218                 in_pcbdetach(inp);
1219                 so->so_state |= nofd;
1220                 return (ENOBUFS);
1221         }
1222         tp->t_state = TCPS_CLOSED;
1223         return (0);
1224 }
1225
1226 /*
1227  * Initiate (or continue) disconnect.
1228  * If embryonic state, just send reset (once).
1229  * If in ``let data drain'' option and linger null, just drop.
1230  * Otherwise (hard), mark socket disconnecting and drop
1231  * current input data; switch states based on user close, and
1232  * send segment to peer (with FIN).
1233  */
1234 static struct tcpcb *
1235 tcp_disconnect(tp)
1236         register struct tcpcb *tp;
1237 {
1238         struct inpcb *inp = tp->t_inpcb;
1239         struct socket *so = inp->inp_socket;
1240
1241         INP_INFO_WLOCK_ASSERT(&tcbinfo);
1242         INP_LOCK_ASSERT(inp);
1243
1244         if (tp->t_state < TCPS_ESTABLISHED)
1245                 tp = tcp_close(tp);
1246         else if ((so->so_options & SO_LINGER) && so->so_linger == 0)
1247                 tp = tcp_drop(tp, 0);
1248         else {
1249                 soisdisconnecting(so);
1250                 sbflush(&so->so_rcv);
1251                 tp = tcp_usrclosed(tp);
1252                 if (tp)
1253                         (void) tcp_output(tp);
1254         }
1255         return (tp);
1256 }
1257
1258 /*
1259  * User issued close, and wish to trail through shutdown states:
1260  * if never received SYN, just forget it.  If got a SYN from peer,
1261  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
1262  * If already got a FIN from peer, then almost done; go to LAST_ACK
1263  * state.  In all other cases, have already sent FIN to peer (e.g.
1264  * after PRU_SHUTDOWN), and just have to play tedious game waiting
1265  * for peer to send FIN or not respond to keep-alives, etc.
1266  * We can let the user exit from the close as soon as the FIN is acked.
1267  */
1268 static struct tcpcb *
1269 tcp_usrclosed(tp)
1270         register struct tcpcb *tp;
1271 {
1272
1273         INP_INFO_WLOCK_ASSERT(&tcbinfo);
1274         INP_LOCK_ASSERT(tp->t_inpcb);
1275
1276         switch (tp->t_state) {
1277
1278         case TCPS_CLOSED:
1279         case TCPS_LISTEN:
1280                 tp->t_state = TCPS_CLOSED;
1281                 tp = tcp_close(tp);
1282                 break;
1283
1284         case TCPS_SYN_SENT:
1285         case TCPS_SYN_RECEIVED:
1286                 tp->t_flags |= TF_NEEDFIN;
1287                 break;
1288
1289         case TCPS_ESTABLISHED:
1290                 tp->t_state = TCPS_FIN_WAIT_1;
1291                 break;
1292
1293         case TCPS_CLOSE_WAIT:
1294                 tp->t_state = TCPS_LAST_ACK;
1295                 break;
1296         }
1297         if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
1298                 soisdisconnected(tp->t_inpcb->inp_socket);
1299                 /* To prevent the connection hanging in FIN_WAIT_2 forever. */
1300                 if (tp->t_state == TCPS_FIN_WAIT_2)
1301                         callout_reset(tp->tt_2msl, tcp_maxidle,
1302                                       tcp_timer_2msl, tp);
1303         }
1304         return (tp);
1305 }