sys/net/tun/if_tun.c

   1 /*      $NetBSD: if_tun.c,v 1.14 1994/06/29 06:36:25 cgd Exp $  */
   2
   3 /*
   4  * Copyright (c) 1988, Julian Onions <jpo@cs.nott.ac.uk>
   5  * Nottingham University 1987.
   6  *
   7  * This source may be freely distributed, however I would be interested
   8  * in any changes that are made.
   9  *
  10  * This driver takes packets off the IP i/f and hands them up to a
  11  * user process to have its wicked way with. This driver has it's
  12  * roots in a similar driver written by Phil Cockcroft (formerly) at
  13  * UCL. This driver is based much more on read/write/poll mode of
  14  * operation though.
  15  *
  16  * $FreeBSD: src/sys/net/if_tun.c,v 1.74.2.8 2002/02/13 00:43:11 dillon Exp $
  17  * $DragonFly: src/sys/net/tun/if_tun.c,v 1.35 2008/04/05 06:28:35 sephe Exp $
  18  */
  19
  20 #include "opt_atalk.h"
  21 #include "opt_inet.h"
  22 #include "opt_inet6.h"
  23 #include "opt_ipx.h"
  24
  25 #include <sys/param.h>
  26 #include <sys/proc.h>
  27 #include <sys/systm.h>
  28 #include <sys/mbuf.h>
  29 #include <sys/socket.h>
  30 #include <sys/conf.h>
  31 #include <sys/device.h>
  32 #include <sys/filio.h>
  33 #include <sys/sockio.h>
  34 #include <sys/thread2.h>
  35 #include <sys/ttycom.h>
  36 #include <sys/poll.h>
  37 #include <sys/signalvar.h>
  38 #include <sys/filedesc.h>
  39 #include <sys/kernel.h>
  40 #include <sys/sysctl.h>
  41 #include <sys/uio.h>
  42 #include <sys/vnode.h>
  43 #include <sys/malloc.h>
  44
  45 #include <net/if.h>
  46 #include <net/if_types.h>
  47 #include <net/ifq_var.h>
  48 #include <net/netisr.h>
  49 #include <net/route.h>
  50
  51 #ifdef INET
  52 #include <netinet/in.h>
  53 #endif
  54
  55 #include <net/bpf.h>
  56
  57 #include "if_tunvar.h"
  58 #include "if_tun.h"
  59
  60 static MALLOC_DEFINE(M_TUN, "tun", "Tunnel Interface");
  61
  62 static void tunattach (void *);
  63 PSEUDO_SET(tunattach, if_tun);
  64
  65 static void tuncreate (cdev_t dev);
  66
  67 #define TUNDEBUG        if (tundebug) if_printf
  68 static int tundebug = 0;
  69 SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0, "");
  70
  71 static int tunoutput (struct ifnet *, struct mbuf *, struct sockaddr *,
  72             struct rtentry *rt);
  73 static int tunifioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
  74 static int tuninit (struct ifnet *);
  75 static void tunstart(struct ifnet *);
  76
  77 static  d_open_t        tunopen;
  78 static  d_close_t       tunclose;
  79 static  d_read_t        tunread;
  80 static  d_write_t       tunwrite;
  81 static  d_ioctl_t       tunioctl;
  82 static  d_poll_t        tunpoll;
  83
  84 #define CDEV_MAJOR 52
  85 static struct dev_ops tun_ops = {
  86         { "tun", CDEV_MAJOR, 0 },
  87         .d_open =       tunopen,
  88         .d_close =      tunclose,
  89         .d_read =       tunread,
  90         .d_write =      tunwrite,
  91         .d_ioctl =      tunioctl,
  92         .d_poll =       tunpoll,
  93 };
  94
  95 static void
  96 tunattach(void *dummy)
  97 {
  98         dev_ops_add(&tun_ops, 0, 0);
  99 }
 100
 101 static void
 102 tuncreate(cdev_t dev)
 103 {
 104         struct tun_softc *sc;
 105         struct ifnet *ifp;
 106
 107         dev = make_dev(&tun_ops, minor(dev),
 108             UID_UUCP, GID_DIALER, 0600, "tun%d", lminor(dev));
 109
 110         MALLOC(sc, struct tun_softc *, sizeof(*sc), M_TUN, M_WAITOK | M_ZERO);
 111         sc->tun_flags = TUN_INITED;
 112
 113         ifp = &sc->tun_if;
 114         if_initname(ifp, "tun", lminor(dev));
 115         ifp->if_mtu = TUNMTU;
 116         ifp->if_ioctl = tunifioctl;
 117         ifp->if_output = tunoutput;
 118         ifp->if_start = tunstart;
 119         ifp->if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
 120         ifp->if_type = IFT_PPP;
 121         ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
 122         ifq_set_ready(&ifp->if_snd);
 123         ifp->if_softc = sc;
 124         if_attach(ifp, NULL);
 125         bpfattach(ifp, DLT_NULL, sizeof(u_int));
 126         dev->si_drv1 = sc;
 127 }
 128
 129 /*
 130  * tunnel open - must be superuser & the device must be
 131  * configured in
 132  */
 133 static  int
 134 tunopen(struct dev_open_args *ap)
 135 {
 136         cdev_t dev = ap->a_head.a_dev;
 137         struct ifnet    *ifp;
 138         struct tun_softc *tp;
 139         int     error;
 140
 141         if ((error = suser_cred(ap->a_cred, 0)) != NULL)
 142                 return (error);
 143
 144         tp = dev->si_drv1;
 145         if (!tp) {
 146                 tuncreate(dev);
 147                 tp = dev->si_drv1;
 148         }
 149         if (tp->tun_flags & TUN_OPEN)
 150                 return EBUSY;
 151         tp->tun_pid = curproc->p_pid;
 152         ifp = &tp->tun_if;
 153         tp->tun_flags |= TUN_OPEN;
 154         TUNDEBUG(ifp, "open\n");
 155         return (0);
 156 }
 157
 158 /*
 159  * tunclose - close the device - mark i/f down & delete
 160  * routing info
 161  */
 162 static  int
 163 tunclose(struct dev_close_args *ap)
 164 {
 165         cdev_t dev = ap->a_head.a_dev;
 166         struct tun_softc *tp;
 167         struct ifnet    *ifp;
 168
 169         tp = dev->si_drv1;
 170         ifp = &tp->tun_if;
 171
 172         tp->tun_flags &= ~TUN_OPEN;
 173         tp->tun_pid = 0;
 174
 175         /* Junk all pending output. */
 176         lwkt_serialize_enter(ifp->if_serializer);
 177         ifq_purge(&ifp->if_snd);
 178         lwkt_serialize_exit(ifp->if_serializer);
 179
 180         if (ifp->if_flags & IFF_UP) {
 181                 lwkt_serialize_enter(ifp->if_serializer);
 182                 if_down(ifp);
 183                 lwkt_serialize_exit(ifp->if_serializer);
 184         }
 185         ifp->if_flags &= ~IFF_RUNNING;
 186         if_purgeaddrs_nolink(ifp);
 187
 188         funsetown(tp->tun_sigio);
 189         selwakeup(&tp->tun_rsel);
 190
 191         TUNDEBUG(ifp, "closed\n");
 192         return (0);
 193 }
 194
 195 static int
 196 tuninit(struct ifnet *ifp)
 197 {
 198         struct tun_softc *tp = ifp->if_softc;
 199         struct ifaddr_container *ifac;
 200         int error = 0;
 201
 202         TUNDEBUG(ifp, "tuninit\n");
 203
 204         ifp->if_flags |= IFF_UP | IFF_RUNNING;
 205         getmicrotime(&ifp->if_lastchange);
 206
 207         TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
 208                 struct ifaddr *ifa = ifac->ifa;
 209
 210                 if (ifa->ifa_addr == NULL) {
 211                         error = EFAULT;
 212                         /* XXX: Should maybe return straight off? */
 213                 } else {
 214 #ifdef INET
 215                         if (ifa->ifa_addr->sa_family == AF_INET) {
 216                             struct sockaddr_in *si;
 217
 218                             si = (struct sockaddr_in *)ifa->ifa_addr;
 219                             if (si->sin_addr.s_addr)
 220                                     tp->tun_flags |= TUN_IASET;
 221                         }
 222 #endif
 223                 }
 224         }
 225         return (error);
 226 }
 227
 228 /*
 229  * Process an ioctl request.
 230  *
 231  * MPSAFE
 232  */
 233 int
 234 tunifioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 235 {
 236         struct ifreq *ifr = (struct ifreq *)data;
 237         struct tun_softc *tp = ifp->if_softc;
 238         struct ifstat *ifs;
 239         int error = 0;
 240
 241         switch(cmd) {
 242         case SIOCGIFSTATUS:
 243                 ifs = (struct ifstat *)data;
 244                 if (tp->tun_pid)
 245                         ksprintf(ifs->ascii + strlen(ifs->ascii),
 246                             "\tOpened by PID %d\n", tp->tun_pid);
 247                 break;
 248         case SIOCSIFADDR:
 249                 error = tuninit(ifp);
 250                 TUNDEBUG(ifp, "address set, error=%d\n", error);
 251                 break;
 252         case SIOCSIFDSTADDR:
 253                 error = tuninit(ifp);
 254                 TUNDEBUG(ifp, "destination address set, error=%d\n", error);
 255                 break;
 256         case SIOCSIFMTU:
 257                 ifp->if_mtu = ifr->ifr_mtu;
 258                 TUNDEBUG(ifp, "mtu set\n");
 259                 break;
 260         case SIOCSIFFLAGS:
 261         case SIOCADDMULTI:
 262         case SIOCDELMULTI:
 263                 break;
 264         default:
 265                 error = EINVAL;
 266         }
 267         return (error);
 268 }
 269
 270 /*
 271  * tunoutput - queue packets from higher level ready to put out.
 272  *
 273  * MPSAFE
 274  */
 275 static int
 276 tunoutput(struct ifnet *ifp, struct mbuf *m0, struct sockaddr *dst,
 277           struct rtentry *rt)
 278 {
 279         struct tun_softc *tp = ifp->if_softc;
 280         int error;
 281         struct altq_pktattr pktattr;
 282
 283         TUNDEBUG(ifp, "tunoutput\n");
 284
 285         if ((tp->tun_flags & TUN_READY) != TUN_READY) {
 286                 TUNDEBUG(ifp, "not ready 0%o\n", tp->tun_flags);
 287                 m_freem (m0);
 288                 return EHOSTDOWN;
 289         }
 290
 291         /*
 292          * if the queueing discipline needs packet classification,
 293          * do it before prepending link headers.
 294          */
 295         ifq_classify(&ifp->if_snd, m0, dst->sa_family, &pktattr);
 296
 297         /* BPF write needs to be handled specially */
 298         if (dst->sa_family == AF_UNSPEC) {
 299                 dst->sa_family = *(mtod(m0, int *));
 300                 m0->m_len -= sizeof(int);
 301                 m0->m_pkthdr.len -= sizeof(int);
 302                 m0->m_data += sizeof(int);
 303         }
 304
 305         if (ifp->if_bpf) {
 306                 /*
 307                  * We need to prepend the address family as
 308                  * a four byte field.
 309                  */
 310                 uint32_t af = dst->sa_family;
 311
 312                 bpf_ptap(ifp->if_bpf, m0, &af, sizeof(af));
 313         }
 314
 315         /* prepend sockaddr? this may abort if the mbuf allocation fails */
 316         if (tp->tun_flags & TUN_LMODE) {
 317                 /* allocate space for sockaddr */
 318                 M_PREPEND(m0, dst->sa_len, MB_DONTWAIT);
 319
 320                 /* if allocation failed drop packet */
 321                 if (m0 == NULL){
 322                         IF_DROP(&ifp->if_snd);
 323                         ifp->if_oerrors++;
 324                         return (ENOBUFS);
 325                 } else {
 326                         bcopy(dst, m0->m_data, dst->sa_len);
 327                 }
 328         }
 329
 330         if (tp->tun_flags & TUN_IFHEAD) {
 331                 /* Prepend the address family */
 332                 M_PREPEND(m0, 4, MB_DONTWAIT);
 333
 334                 /* if allocation failed drop packet */
 335                 if (m0 == NULL){
 336                         IF_DROP(&ifp->if_snd);
 337                         ifp->if_oerrors++;
 338                         return ENOBUFS;
 339                 } else
 340                         *(u_int32_t *)m0->m_data = htonl(dst->sa_family);
 341         } else {
 342 #ifdef INET
 343                 if (dst->sa_family != AF_INET)
 344 #endif
 345                 {
 346                         m_freem(m0);
 347                         return EAFNOSUPPORT;
 348                 }
 349         }
 350
 351         error = ifq_handoff(ifp, m0, &pktattr);
 352         if (error) {
 353                 ifp->if_collisions++;
 354         } else {
 355                 ifp->if_opackets++;
 356                 if (tp->tun_flags & TUN_RWAIT) {
 357                         tp->tun_flags &= ~TUN_RWAIT;
 358                         wakeup((caddr_t)tp);
 359                 }
 360                 get_mplock();
 361                 if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
 362                         pgsigio(tp->tun_sigio, SIGIO, 0);
 363                 selwakeup(&tp->tun_rsel);
 364                 rel_mplock();
 365         }
 366         return (error);
 367 }
 368
 369 /*
 370  * the ops interface is now pretty minimal.
 371  */
 372 static  int
 373 tunioctl(struct dev_ioctl_args *ap)
 374 {
 375         cdev_t dev = ap->a_head.a_dev;
 376         struct tun_softc *tp = dev->si_drv1;
 377         struct tuninfo *tunp;
 378
 379         switch (ap->a_cmd) {
 380         case TUNSIFINFO:
 381                 tunp = (struct tuninfo *)ap->a_data;
 382                 if (tunp->mtu < IF_MINMTU)
 383                         return (EINVAL);
 384                 tp->tun_if.if_mtu = tunp->mtu;
 385                 tp->tun_if.if_type = tunp->type;
 386                 tp->tun_if.if_baudrate = tunp->baudrate;
 387                 break;
 388         case TUNGIFINFO:
 389                 tunp = (struct tuninfo *)ap->a_data;
 390                 tunp->mtu = tp->tun_if.if_mtu;
 391                 tunp->type = tp->tun_if.if_type;
 392                 tunp->baudrate = tp->tun_if.if_baudrate;
 393                 break;
 394         case TUNSDEBUG:
 395                 tundebug = *(int *)ap->a_data;
 396                 break;
 397         case TUNGDEBUG:
 398                 *(int *)ap->a_data = tundebug;
 399                 break;
 400         case TUNSLMODE:
 401                 if (*(int *)ap->a_data) {
 402                         tp->tun_flags |= TUN_LMODE;
 403                         tp->tun_flags &= ~TUN_IFHEAD;
 404                 } else
 405                         tp->tun_flags &= ~TUN_LMODE;
 406                 break;
 407         case TUNSIFHEAD:
 408                 if (*(int *)ap->a_data) {
 409                         tp->tun_flags |= TUN_IFHEAD;
 410                         tp->tun_flags &= ~TUN_LMODE;
 411                 } else
 412                         tp->tun_flags &= ~TUN_IFHEAD;
 413                 break;
 414         case TUNGIFHEAD:
 415                 *(int *)ap->a_data = (tp->tun_flags & TUN_IFHEAD) ? 1 : 0;
 416                 break;
 417         case TUNSIFMODE:
 418                 /* deny this if UP */
 419                 if (tp->tun_if.if_flags & IFF_UP)
 420                         return(EBUSY);
 421
 422                 switch (*(int *)ap->a_data & ~IFF_MULTICAST) {
 423                 case IFF_POINTOPOINT:
 424                 case IFF_BROADCAST:
 425                         tp->tun_if.if_flags &= ~(IFF_BROADCAST|IFF_POINTOPOINT);
 426                         tp->tun_if.if_flags |= *(int *)ap->a_data;
 427                         break;
 428                 default:
 429                         return(EINVAL);
 430                 }
 431                 break;
 432         case TUNSIFPID:
 433                 tp->tun_pid = curproc->p_pid;
 434                 break;
 435         case FIOASYNC:
 436                 if (*(int *)ap->a_data)
 437                         tp->tun_flags |= TUN_ASYNC;
 438                 else
 439                         tp->tun_flags &= ~TUN_ASYNC;
 440                 break;
 441         case FIONREAD:
 442                 lwkt_serialize_enter(tp->tun_if.if_serializer);
 443                 if (!ifq_is_empty(&tp->tun_if.if_snd)) {
 444                         struct mbuf *mb;
 445
 446                         mb = ifq_poll(&tp->tun_if.if_snd);
 447                         for( *(int *)ap->a_data = 0; mb != 0; mb = mb->m_next)
 448                                 *(int *)ap->a_data += mb->m_len;
 449                 } else {
 450                         *(int *)ap->a_data = 0;
 451                 }
 452                 lwkt_serialize_exit(tp->tun_if.if_serializer);
 453                 break;
 454         case FIOSETOWN:
 455                 return (fsetown(*(int *)ap->a_data, &tp->tun_sigio));
 456
 457         case FIOGETOWN:
 458                 *(int *)ap->a_data = fgetown(tp->tun_sigio);
 459                 return (0);
 460
 461         /* This is deprecated, FIOSETOWN should be used instead. */
 462         case TIOCSPGRP:
 463                 return (fsetown(-(*(int *)ap->a_data), &tp->tun_sigio));
 464
 465         /* This is deprecated, FIOGETOWN should be used instead. */
 466         case TIOCGPGRP:
 467                 *(int *)ap->a_data = -fgetown(tp->tun_sigio);
 468                 return (0);
 469
 470         default:
 471                 return (ENOTTY);
 472         }
 473         return (0);
 474 }
 475
 476 /*
 477  * The ops read interface - reads a packet at a time, or at
 478  * least as much of a packet as can be read.
 479  */
 480 static  int
 481 tunread(struct dev_read_args *ap)
 482 {
 483         cdev_t dev = ap->a_head.a_dev;
 484         struct uio *uio = ap->a_uio;
 485         struct tun_softc *tp = dev->si_drv1;
 486         struct ifnet    *ifp = &tp->tun_if;
 487         struct mbuf     *m0;
 488         int             error=0, len;
 489
 490         TUNDEBUG(ifp, "read\n");
 491         if ((tp->tun_flags & TUN_READY) != TUN_READY) {
 492                 TUNDEBUG(ifp, "not ready 0%o\n", tp->tun_flags);
 493                 return EHOSTDOWN;
 494         }
 495
 496         tp->tun_flags &= ~TUN_RWAIT;
 497
 498         lwkt_serialize_enter(ifp->if_serializer);
 499
 500         while ((m0 = ifq_dequeue(&ifp->if_snd, NULL)) == NULL) {
 501                 if (ap->a_ioflag & IO_NDELAY) {
 502                         lwkt_serialize_exit(ifp->if_serializer);
 503                         return EWOULDBLOCK;
 504                 }
 505                 tp->tun_flags |= TUN_RWAIT;
 506                 lwkt_serialize_exit(ifp->if_serializer);
 507                 if ((error = tsleep(tp, PCATCH, "tunread", 0)) != 0)
 508                         return error;
 509                 lwkt_serialize_enter(ifp->if_serializer);
 510         }
 511
 512         lwkt_serialize_exit(ifp->if_serializer);
 513
 514         while (m0 && uio->uio_resid > 0 && error == 0) {
 515                 len = min(uio->uio_resid, m0->m_len);
 516                 if (len != 0)
 517                         error = uiomove(mtod(m0, caddr_t), len, uio);
 518                 m0 = m_free(m0);
 519         }
 520
 521         if (m0) {
 522                 TUNDEBUG(ifp, "Dropping mbuf\n");
 523                 m_freem(m0);
 524         }
 525         return error;
 526 }
 527
 528 /*
 529  * the ops write interface - an atomic write is a packet - or else!
 530  */
 531 static  int
 532 tunwrite(struct dev_write_args *ap)
 533 {
 534         cdev_t dev = ap->a_head.a_dev;
 535         struct uio *uio = ap->a_uio;
 536         struct tun_softc *tp = dev->si_drv1;
 537         struct ifnet    *ifp = &tp->tun_if;
 538         struct mbuf     *top, **mp, *m;
 539         int             error=0, tlen, mlen;
 540         uint32_t        family;
 541         int             isr;
 542
 543         TUNDEBUG(ifp, "tunwrite\n");
 544
 545         if (uio->uio_resid == 0)
 546                 return 0;
 547
 548         if (uio->uio_resid < 0 || uio->uio_resid > TUNMRU) {
 549                 TUNDEBUG(ifp, "len=%d!\n", uio->uio_resid);
 550                 return EIO;
 551         }
 552         tlen = uio->uio_resid;
 553
 554         /* get a header mbuf */
 555         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 556         if (m == NULL)
 557                 return ENOBUFS;
 558         mlen = MHLEN;
 559
 560         top = 0;
 561         mp = &top;
 562         while (error == 0 && uio->uio_resid > 0) {
 563                 m->m_len = min(mlen, uio->uio_resid);
 564                 error = uiomove(mtod (m, caddr_t), m->m_len, uio);
 565                 *mp = m;
 566                 mp = &m->m_next;
 567                 if (uio->uio_resid > 0) {
 568                         MGET (m, MB_DONTWAIT, MT_DATA);
 569                         if (m == 0) {
 570                                 error = ENOBUFS;
 571                                 break;
 572                         }
 573                         mlen = MLEN;
 574                 }
 575         }
 576         if (error) {
 577                 if (top)
 578                         m_freem (top);
 579                 ifp->if_ierrors++;
 580                 return error;
 581         }
 582
 583         top->m_pkthdr.len = tlen;
 584         top->m_pkthdr.rcvif = ifp;
 585
 586         if (ifp->if_bpf) {
 587                 if (tp->tun_flags & TUN_IFHEAD) {
 588                         /*
 589                          * Conveniently, we already have a 4-byte address
 590                          * family prepended to our packet !
 591                          * Inconveniently, it's in the wrong byte order !
 592                          */
 593                         if ((top = m_pullup(top, sizeof(family))) == NULL)
 594                                 return ENOBUFS;
 595                         *mtod(top, u_int32_t *) =
 596                             ntohl(*mtod(top, u_int32_t *));
 597                         bpf_mtap(ifp->if_bpf, top);
 598                         *mtod(top, u_int32_t *) =
 599                             htonl(*mtod(top, u_int32_t *));
 600                 } else {
 601                         /*
 602                          * We need to prepend the address family as
 603                          * a four byte field.
 604                          */
 605                         static const uint32_t af = AF_INET;
 606
 607                         bpf_ptap(ifp->if_bpf, top, &af, sizeof(af));
 608                 }
 609         }
 610
 611         if (tp->tun_flags & TUN_IFHEAD) {
 612                 if (top->m_len < sizeof(family) &&
 613                     (top = m_pullup(top, sizeof(family))) == NULL)
 614                                 return ENOBUFS;
 615                 family = ntohl(*mtod(top, u_int32_t *));
 616                 m_adj(top, sizeof(family));
 617         } else
 618                 family = AF_INET;
 619
 620         ifp->if_ibytes += top->m_pkthdr.len;
 621         ifp->if_ipackets++;
 622
 623         switch (family) {
 624 #ifdef INET
 625         case AF_INET:
 626                 isr = NETISR_IP;
 627                 break;
 628 #endif
 629 #ifdef INET6
 630         case AF_INET6:
 631                 isr = NETISR_IPV6;
 632                 break;
 633 #endif
 634 #ifdef IPX
 635         case AF_IPX:
 636                 isr = NETISR_IPX;
 637                 break;
 638 #endif
 639 #ifdef NETATALK
 640         case AF_APPLETALK:
 641                 isr = NETISR_ATALK2;
 642                 break;
 643 #endif
 644         default:
 645                 m_freem(m);
 646                 return (EAFNOSUPPORT);
 647         }
 648
 649         netisr_dispatch(isr, top);
 650         return (0);
 651 }
 652
 653 /*
 654  * tunpoll - the poll interface, this is only useful on reads
 655  * really. The write detect always returns true, write never blocks
 656  * anyway, it either accepts the packet or drops it.
 657  */
 658 static  int
 659 tunpoll(struct dev_poll_args *ap)
 660 {
 661         cdev_t dev = ap->a_head.a_dev;
 662         struct tun_softc *tp = dev->si_drv1;
 663         struct ifnet    *ifp = &tp->tun_if;
 664         int             revents = 0;
 665
 666         TUNDEBUG(ifp, "tunpoll\n");
 667
 668         lwkt_serialize_enter(ifp->if_serializer);
 669
 670         if (ap->a_events & (POLLIN | POLLRDNORM)) {
 671                 if (!ifq_is_empty(&ifp->if_snd)) {
 672                         TUNDEBUG(ifp, "tunpoll q=%d\n", ifp->if_snd.ifq_len);
 673                         revents |= ap->a_events & (POLLIN | POLLRDNORM);
 674                 } else {
 675                         TUNDEBUG(ifp, "tunpoll waiting\n");
 676                         selrecord(curthread, &tp->tun_rsel);
 677                 }
 678         }
 679         if (ap->a_events & (POLLOUT | POLLWRNORM))
 680                 revents |= ap->a_events & (POLLOUT | POLLWRNORM);
 681
 682         lwkt_serialize_exit(ifp->if_serializer);
 683         ap->a_events = revents;
 684         return(0);
 685 }
 686
 687 /*
 688  * Start packet transmission on the interface.
 689  * when the interface queue is rate-limited by ALTQ,
 690  * if_start is needed to drain packets from the queue in order
 691  * to notify readers when outgoing packets become ready.
 692  */
 693 static void
 694 tunstart(struct ifnet *ifp)
 695 {
 696         struct tun_softc *tp = ifp->if_softc;
 697         struct mbuf *m;
 698
 699         if (!ifq_is_enabled(&ifp->if_snd))
 700                 return;
 701
 702         m = ifq_poll(&ifp->if_snd);
 703         if (m != NULL) {
 704                 if (tp->tun_flags & TUN_RWAIT) {
 705                         tp->tun_flags &= ~TUN_RWAIT;
 706                         wakeup((caddr_t)tp);
 707                 }
 708                 if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio)
 709                         pgsigio(tp->tun_sigio, SIGIO, 0);
 710                 selwakeup(&tp->tun_rsel);
 711         }
 712 }