sys/net/sl/if_sl.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1987, 1989, 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)if_sl.c     8.6 (Berkeley) 2/1/94
  32  * $FreeBSD: src/sys/net/if_sl.c,v 1.84.2.2 2002/02/13 00:43:10 dillon Exp $
  33  * $DragonFly: src/sys/net/sl/if_sl.c,v 1.32 2008/05/14 11:59:23 sephe Exp $
  34  */
  35
  36 /*
  37  * Serial Line interface
  38  *
  39  * Rick Adams
  40  * Center for Seismic Studies
  41  * 1300 N 17th Street, Suite 1450
  42  * Arlington, Virginia 22209
  43  * (703)276-7900
  44  * rick@seismo.ARPA
  45  * seismo!rick
  46  *
  47  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  48  * N.B.: this belongs in netinet, not net, the way it stands now.
  49  * Should have a link-layer type designation, but wouldn't be
  50  * backwards-compatible.
  51  *
  52  * Converted to 4.3BSD Beta by Chris Torek.
  53  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  54  * W. Jolitz added slip abort.
  55  *
  56  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  57  * Added priority queuing for "interactive" traffic; hooks for TCP
  58  * header compression; ICMP filtering (at 2400 baud, some cretin
  59  * pinging you can use up all your bandwidth).  Made low clist behavior
  60  * more robust and slightly less likely to hang serial line.
  61  * Sped up a bunch of things.
  62  */
  63
  64 #include "use_sl.h"
  65
  66 #include "opt_inet.h"
  67 #if !defined(KLD_MODULE)
  68 #include "opt_slip.h"
  69 #endif
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/proc.h>
  73 #include <sys/priv.h>
  74 #include <sys/malloc.h>
  75 #include <sys/mbuf.h>
  76 #include <sys/dkstat.h>
  77 #include <sys/socket.h>
  78 #include <sys/sockio.h>
  79 #include <sys/fcntl.h>
  80 #include <sys/signalvar.h>
  81 #include <sys/tty.h>
  82 #include <sys/clist.h>
  83 #include <sys/kernel.h>
  84 #include <sys/conf.h>
  85 #include <sys/thread2.h>
  86
  87 #include <net/if.h>
  88 #include <net/if_types.h>
  89 #include <net/ifq_var.h>
  90 #include <net/netisr.h>
  91
  92 #if INET
  93 #include <netinet/in.h>
  94 #include <netinet/in_systm.h>
  95 #include <netinet/in_var.h>
  96 #include <netinet/ip.h>
  97 #else
  98 #error "Huh? Slip without inet?"
  99 #endif
 100
 101 #include <net/slcompress.h>
 102 #include "if_slvar.h"
 103 #include <net/slip.h>
 104
 105 #include <net/bpf.h>
 106
 107 static void slattach (void *);
 108 PSEUDO_SET(slattach, if_sl);
 109
 110 /*
 111  * SLRMAX is a hard limit on input packet size.  To simplify the code
 112  * and improve performance, we require that packets fit in an mbuf
 113  * cluster, and if we get a compressed packet, there's enough extra
 114  * room to expand the header into a max length tcp/ip header (128
 115  * bytes).  So, SLRMAX can be at most
 116  *      MCLBYTES - 128
 117  *
 118  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 119  * small enough so that interactive use doesn't suffer, but large
 120  * enough to provide good performance. 552 is a good choice for SLMTU
 121  * because it is high enough to not fragment TCP packets being routed
 122  * through this host. Packet fragmentation is bad with SLIP because
 123  * fragment headers aren't compressed. The previous assumptions about
 124  * the best MTU value don't really hold when using modern modems with
 125  * BTLZ data compression because the modem buffers play a much larger
 126  * role in interactive performance than the MTU. The MTU can be changed
 127  * at any time to suit the specific environment with ifconfig(8), and
 128  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 129  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 130  * handles this better).
 131  *
 132  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 133  * of us (i.e., in clists waiting to be picked up by the tty output
 134  * interrupt).  If we queue a lot of data downstream, it's immune to
 135  * our t.o.s. queuing.
 136  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 137  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 138  * wait is dependent on the ftp window size but that's typically
 139  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 140  * the cost (in idle time on the wire) of the tty driver running
 141  * off the end of its clists & having to call back slstart for a
 142  * new packet.  For a tty interface with any buffering at all, this
 143  * cost will be zero.  Even with a totally brain dead interface (like
 144  * the one on a typical workstation), the cost will be <= 1 character
 145  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 146  * at most 1% while maintaining good interactive response.
 147  */
 148 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 149 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 150 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 151 #ifndef SLMTU
 152 #define SLMTU           552             /* default MTU */
 153 #endif
 154 #define SLTMAX          1500            /* maximum MTU */
 155 #define SLIP_HIWAT      roundup(50,CBSIZE)
 156 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 157
 158 /*
 159  * SLIP ABORT ESCAPE MECHANISM:
 160  *      (inspired by HAYES modem escape arrangement)
 161  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 162  *      within window time signals a "soft" exit from slip mode by remote end
 163  *      if the IFF_DEBUG flag is on.
 164  */
 165 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 166 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 167 #define ABT_COUNT       3       /* count of escapes for abort */
 168 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 169
 170 static struct sl_softc sl_softc[NSL];
 171
 172 #define FRAME_END               0xc0            /* Frame End */
 173 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 174 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 175 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 176
 177 static int slinit (struct sl_softc *);
 178 static struct mbuf *sl_btom (struct sl_softc *, int);
 179 static timeout_t sl_keepalive;
 180 static timeout_t sl_outfill;
 181 static int      slclose (struct tty *,int);
 182 static int      slinput (int, struct tty *);
 183 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 184 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct ucred *);
 185 static int      slopen (cdev_t, struct tty *);
 186 static int      sloutput (struct ifnet *,
 187             struct mbuf *, struct sockaddr *, struct rtentry *);
 188 static int      slstart (struct tty *);
 189
 190 static struct linesw slipdisc = {
 191         slopen,         slclose,        l_noread,       l_nowrite,
 192         sltioctl,       slinput,        slstart,        ttymodem,
 193         FRAME_END
 194 };
 195
 196 /*
 197  * Called from boot code to establish sl interfaces.
 198  */
 199 static void
 200 slattach(void *dummy)
 201 {
 202         struct sl_softc *sc;
 203         int i = 0;
 204
 205         lwkt_gettoken(&tty_token);
 206         linesw[SLIPDISC] = slipdisc;
 207
 208         for (sc = sl_softc; i < NSL; sc++) {
 209                 if_initname(&(sc->sc_if), "sl", i++);
 210                 sc->sc_if.if_mtu = SLMTU;
 211                 sc->sc_if.if_flags =
 212 #ifdef SLIP_IFF_OPTS
 213                     SLIP_IFF_OPTS;
 214 #else
 215                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 216 #endif
 217                 sc->sc_if.if_type = IFT_SLIP;
 218                 sc->sc_if.if_ioctl = slioctl;
 219                 sc->sc_if.if_output = sloutput;
 220                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 221                 ifq_set_ready(&sc->sc_if.if_snd);
 222                 sc->sc_fastq.ifq_maxlen = 32;
 223                 sc->sc_if.if_linkmib = sc;
 224                 sc->sc_if.if_linkmiblen = sizeof *sc;
 225                 callout_init_mp(&sc->sc_oftimeout);
 226                 callout_init_mp(&sc->sc_katimeout);
 227                 if_attach(&sc->sc_if, NULL);
 228                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 229         }
 230         lwkt_reltoken(&tty_token);
 231 }
 232
 233 static int
 234 slinit(struct sl_softc *sc)
 235 {
 236         lwkt_gettoken(&tty_token);
 237         if (sc->sc_ep == NULL)
 238                 sc->sc_ep = kmalloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 239         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 240         sc->sc_mp = sc->sc_buf;
 241         sl_compress_init(&sc->sc_comp, -1);
 242         lwkt_reltoken(&tty_token);
 243         return (1);
 244 }
 245
 246 /*
 247  * Line specific open routine.
 248  * Attach the given tty to the first available sl unit.
 249  */
 250 /* ARGSUSED */
 251 static int
 252 slopen(cdev_t dev, struct tty *tp)
 253 {
 254         struct sl_softc *sc;
 255         int nsl;
 256         int error;
 257         struct thread *td = curthread;  /* XXX */
 258
 259         error = priv_check(td, PRIV_ROOT);
 260         if (error)
 261                 return (error);
 262
 263         lwkt_gettoken(&tty_token);
 264         if (tp->t_line == SLIPDISC) {
 265                 lwkt_reltoken(&tty_token);
 266                 return (0);
 267         }
 268
 269         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 270                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 271                         if (slinit(sc) == 0) {
 272                                 lwkt_reltoken(&tty_token);
 273                                 return (ENOBUFS);
 274                         }
 275                         tp->t_sc = (caddr_t)sc;
 276                         sc->sc_ttyp = tp;
 277                         sc->sc_if.if_baudrate = tp->t_ospeed;
 278                         ttyflush(tp, FREAD | FWRITE);
 279
 280                         tp->t_line = SLIPDISC;
 281                         /*
 282                          * We don't use t_canq or t_rawq, so reduce their
 283                          * cblock resources to 0.  Reserve enough cblocks
 284                          * for t_outq to guarantee that we can fit a full
 285                          * packet if the SLIP_HIWAT check allows slstart()
 286                          * to loop.  Use the same value for the cblock
 287                          * limit since the reserved blocks should always
 288                          * be enough.  Reserving cblocks probably makes
 289                          * the CLISTRESERVE check unnecessary and wasteful.
 290                          */
 291                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 292                         clist_alloc_cblocks(&tp->t_outq,
 293                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 294                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 295                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 296
 297                         crit_enter();
 298                         if_up(&sc->sc_if);
 299                         crit_exit();
 300                         lwkt_reltoken(&tty_token);
 301                         return (0);
 302                 }
 303         lwkt_reltoken(&tty_token);
 304         return (ENXIO);
 305 }
 306
 307 /*
 308  * Line specific close routine.
 309  * Detach the tty from the sl unit.
 310  */
 311 static int
 312 slclose(struct tty *tp, int flag)
 313 {
 314         struct sl_softc *sc;
 315
 316         lwkt_gettoken(&tty_token);
 317         ttyflush(tp, FREAD | FWRITE);
 318         crit_enter();
 319
 320         clist_free_cblocks(&tp->t_outq);
 321         tp->t_line = 0;
 322         sc = (struct sl_softc *)tp->t_sc;
 323         if (sc != NULL) {
 324                 if (sc->sc_outfill) {
 325                         sc->sc_outfill = 0;
 326                         callout_stop(&sc->sc_oftimeout);
 327                 }
 328                 if (sc->sc_keepalive) {
 329                         sc->sc_keepalive = 0;
 330                         callout_stop(&sc->sc_katimeout);
 331                 }
 332                 if_down(&sc->sc_if);
 333                 sc->sc_flags &= SC_STATIC;
 334                 sc->sc_ttyp = NULL;
 335                 tp->t_sc = NULL;
 336                 if (sc->sc_ep) {
 337                         kfree(sc->sc_ep, M_DEVBUF);
 338                         sc->sc_ep = NULL;
 339                 }
 340                 sc->sc_mp = 0;
 341                 sc->sc_buf = 0;
 342         }
 343         crit_exit();
 344         lwkt_reltoken(&tty_token);
 345         return 0;
 346 }
 347
 348 /*
 349  * Line specific (tty) ioctl routine.
 350  * Provide a way to get the sl unit number.
 351  */
 352 /* ARGSUSED */
 353 static int
 354 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
 355 {
 356         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 357         int nsl;
 358
 359         crit_enter();
 360         lwkt_gettoken(&tty_token);
 361
 362         switch (cmd) {
 363         case SLIOCGUNIT:
 364                 *(int *)data = sc->sc_if.if_dunit;
 365                 break;
 366
 367         case SLIOCSUNIT:
 368                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 369                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 370                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 371                                     && nc->sc_ttyp == NULL
 372                                    ) {
 373                                         tmpnc = kmalloc(sizeof *tmpnc, M_TEMP,
 374                                                        M_WAITOK);
 375                                         *tmpnc = *nc;
 376                                         *nc = *sc;
 377                                         nc->sc_if = tmpnc->sc_if;
 378                                         tmpnc->sc_if = sc->sc_if;
 379                                         *sc = *tmpnc;
 380                                         kfree(tmpnc, M_TEMP);
 381                                         if (sc->sc_if.if_flags & IFF_UP) {
 382                                                 if_down(&sc->sc_if);
 383                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 384                                                         if_up(&nc->sc_if);
 385                                         } else if (nc->sc_if.if_flags & IFF_UP)
 386                                                 if_down(&nc->sc_if);
 387                                         sc->sc_flags &= ~SC_STATIC;
 388                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 389                                         tp->t_sc = sc = nc;
 390                                         clist_alloc_cblocks(&tp->t_outq,
 391                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 392                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 393                                         sl_compress_init(&sc->sc_comp, -1);
 394                                         goto slfound;
 395                                 }
 396                         }
 397                         lwkt_reltoken(&tty_token);
 398                         crit_exit();
 399                         return (ENXIO);
 400                 }
 401         slfound:
 402                 sc->sc_flags |= SC_STATIC;
 403                 break;
 404
 405         case SLIOCSKEEPAL:
 406                 sc->sc_keepalive = *(u_int *)data * hz;
 407                 if (sc->sc_keepalive) {
 408                         sc->sc_flags |= SC_KEEPALIVE;
 409                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 410                                         sl_keepalive, sc);
 411                 } else {
 412                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 413                                 callout_stop(&sc->sc_katimeout);
 414                                 sc->sc_flags &= ~SC_KEEPALIVE;
 415                         }
 416                 }
 417                 break;
 418
 419         case SLIOCGKEEPAL:
 420                 *(int *)data = sc->sc_keepalive / hz;
 421                 break;
 422
 423         case SLIOCSOUTFILL:
 424                 sc->sc_outfill = *(u_int *)data * hz;
 425                 if (sc->sc_outfill) {
 426                         sc->sc_flags |= SC_OUTWAIT;
 427                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 428                                         sl_outfill, sc);
 429                 } else {
 430                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 431                                 callout_stop(&sc->sc_oftimeout);
 432                                 sc->sc_flags &= ~SC_OUTWAIT;
 433                         }
 434                 }
 435                 break;
 436
 437         case SLIOCGOUTFILL:
 438                 *(int *)data = sc->sc_outfill / hz;
 439                 break;
 440
 441         default:
 442                 lwkt_reltoken(&tty_token);
 443                 crit_exit();
 444                 return (ENOIOCTL);
 445         }
 446         lwkt_reltoken(&tty_token);
 447         crit_exit();
 448         return (0);
 449 }
 450
 451 /*
 452  * Queue a packet.  Start transmission if not active.
 453  * Compression happens in slstart; if we do it here, IP TOS
 454  * will cause us to not compress "background" packets, because
 455  * ordering gets trashed.  It can be done for all packets in slstart.
 456  */
 457 static int
 458 sloutput_serialized(struct ifnet *ifp, struct ifaltq_subque *ifsq,
 459     struct mbuf *m, struct sockaddr *dst, struct rtentry *rtp)
 460 {
 461         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 462         struct ip *ip;
 463         int error;
 464         struct altq_pktattr pktattr;
 465
 466         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 467
 468         /*
 469          * `Cannot happen' (see slioctl).  Someday we will extend
 470          * the line protocol to support other address families.
 471          */
 472         if (dst->sa_family != AF_INET) {
 473                 kprintf("%s: af%d not supported\n", sc->sc_if.if_xname,
 474                         dst->sa_family);
 475                 m_freem(m);
 476                 IFNET_STAT_INC(&sc->sc_if, noproto, 1);
 477                 return (EAFNOSUPPORT);
 478         }
 479
 480         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 481                 m_freem(m);
 482                 return (ENETDOWN);
 483         }
 484         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 485                 m_freem(m);
 486                 return (EHOSTUNREACH);
 487         }
 488         ip = mtod(m, struct ip *);
 489         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 490                 m_freem(m);
 491                 return (ENETRESET);             /* XXX ? */
 492         }
 493
 494         crit_enter();
 495
 496         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 497                 if (IF_QFULL(&sc->sc_fastq)) {
 498                         IF_DROP(&sc->sc_fastq);
 499                         m_freem(m);
 500                         error = ENOBUFS;
 501                 } else {
 502                         IF_ENQUEUE(&sc->sc_fastq, m);
 503                         error = 0;
 504                 }
 505         } else {
 506                 error = ifsq_enqueue(ifsq, m, &pktattr);
 507         }
 508         if (error) {
 509                 IFNET_STAT_INC(&sc->sc_if, oerrors, 1);
 510                 crit_exit();
 511                 return (error);
 512         }
 513         if (sc->sc_ttyp->t_outq.c_cc == 0)
 514                 slstart(sc->sc_ttyp);
 515         crit_exit();
 516         return (0);
 517 }
 518
 519 static int
 520 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 521          struct rtentry *rtp)
 522 {
 523         struct ifaltq_subque *ifsq = ifq_get_subq_default(&ifp->if_snd);
 524         int error;
 525
 526         ifsq_serialize_hw(ifsq);
 527         error = sloutput_serialized(ifp, ifsq, m, dst, rtp);
 528         ifsq_deserialize_hw(ifsq);
 529
 530         return error;
 531 }
 532
 533 /*
 534  * Start output on interface.  Get another datagram
 535  * to send from the interface queue and map it to
 536  * the interface before starting output.
 537  */
 538 static int
 539 slstart(struct tty *tp)
 540 {
 541         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 542         struct ifaltq_subque *ifsq = ifq_get_subq_default(&sc->sc_if.if_snd);
 543         struct mbuf *m;
 544         u_char *cp;
 545         struct ip *ip;
 546         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 547         int len = 0;
 548
 549         lwkt_gettoken(&tty_token);
 550         for (;;) {
 551                 /*
 552                  * Call output process whether or not there is more in the
 553                  * output queue.  We are being called in lieu of ttstart
 554                  * and must do what it would.
 555                  */
 556                 (*tp->t_oproc)(tp);
 557
 558                 if (tp->t_outq.c_cc != 0) {
 559                         if (sc != NULL)
 560                                 sc->sc_flags &= ~SC_OUTWAIT;
 561                         if (tp->t_outq.c_cc > SLIP_HIWAT) {
 562                                 lwkt_reltoken(&tty_token);
 563                                 return 0;
 564                         }
 565                 }
 566
 567                 /*
 568                  * This happens briefly when the line shuts down.
 569                  */
 570                 if (sc == NULL) {
 571                         lwkt_reltoken(&tty_token);
 572                         return 0;
 573                 }
 574
 575                 /*
 576                  * Get a packet and send it to the interface.
 577                  */
 578                 crit_enter();
 579                 IF_DEQUEUE(&sc->sc_fastq, m);
 580                 if (m)
 581                         IFNET_STAT_INC(&sc->sc_if, omcasts, 1); /* XXX */
 582                 else
 583                         m = ifsq_dequeue(ifsq);
 584                 crit_exit();
 585                 if (m == NULL) {
 586                         lwkt_reltoken(&tty_token);
 587                         return 0;
 588                 }
 589
 590                 /*
 591                  * We do the header compression here rather than in sloutput
 592                  * because the packets will be out of order if we are using TOS
 593                  * queueing, and the connection id compression will get
 594                  * munged when this happens.
 595                  */
 596                 if (sc->sc_if.if_bpf) {
 597                         /*
 598                          * We need to save the TCP/IP header before it's
 599                          * compressed.  To avoid complicated code, we just
 600                          * copy the entire packet into a stack buffer (since
 601                          * this is a serial line, packets should be short
 602                          * and/or the copy should be negligible cost compared
 603                          * to the packet transmission time).
 604                          */
 605                         struct mbuf *m1 = m;
 606                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 607
 608                         len = 0;
 609                         do {
 610                                 int mlen = m1->m_len;
 611
 612                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 613                                 cp += mlen;
 614                                 len += mlen;
 615                         } while ((m1 = m1->m_next) != NULL);
 616                 }
 617                 ip = mtod(m, struct ip *);
 618                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 619                         if (sc->sc_if.if_flags & SC_COMPRESS)
 620                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 621                                     &sc->sc_comp, 1);
 622                 }
 623                 if (sc->sc_if.if_bpf) {
 624                         bpf_gettoken();
 625
 626                         if (sc->sc_if.if_bpf) {
 627                                 /*
 628                                  * Put the SLIP pseudo-"link header" in place.
 629                                  * The compressed header is now at the
 630                                  * beginning of the mbuf.
 631                                  */
 632                                 bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 633                                 bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR],
 634                                     CHDR_LEN);
 635                                 bpf_tap(sc->sc_if.if_bpf, bpfbuf,
 636                                     len + SLIP_HDRLEN);
 637                         }
 638
 639                         bpf_reltoken();
 640                 }
 641
 642                 /*
 643                  * If system is getting low on clists, just flush our
 644                  * output queue (if the stuff was important, it'll get
 645                  * retransmitted). Note that SLTMAX is used instead of
 646                  * the current if_mtu setting because connections that
 647                  * have already been established still use the original
 648                  * (possibly larger) mss.
 649                  */
 650                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 651                         m_freem(m);
 652                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 653                         continue;
 654                 }
 655
 656                 sc->sc_flags &= ~SC_OUTWAIT;
 657                 /*
 658                  * The extra FRAME_END will start up a new packet, and thus
 659                  * will flush any accumulated garbage.  We do this whenever
 660                  * the line may have been idle for some time.
 661                  */
 662                 if (tp->t_outq.c_cc == 0) {
 663                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 664                         clist_putc(FRAME_END, &tp->t_outq);
 665                 }
 666
 667                 while (m) {
 668                         u_char *ep;
 669
 670                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 671                         while (cp < ep) {
 672                                 /*
 673                                  * Find out how many bytes in the string we can
 674                                  * handle without doing something special.
 675                                  */
 676                                 u_char *bp = cp;
 677
 678                                 while (cp < ep) {
 679                                         switch (*cp++) {
 680                                         case FRAME_ESCAPE:
 681                                         case FRAME_END:
 682                                                 --cp;
 683                                                 goto out;
 684                                         }
 685                                 }
 686                                 out:
 687                                 if (cp > bp) {
 688                                         /*
 689                                          * Put n characters at once
 690                                          * into the tty output queue.
 691                                          */
 692                                         if (b_to_q((char *)bp, cp - bp,
 693                                             &tp->t_outq))
 694                                                 break;
 695                                         IFNET_STAT_INC(&sc->sc_if, obytes,
 696                                             cp - bp);
 697                                 }
 698                                 /*
 699                                  * If there are characters left in the mbuf,
 700                                  * the first one must be special..
 701                                  * Put it out in a different form.
 702                                  */
 703                                 if (cp < ep) {
 704                                         if (clist_putc(FRAME_ESCAPE, &tp->t_outq))
 705                                                 break;
 706                                         if (clist_putc(*cp++ == FRAME_ESCAPE ?
 707                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 708                                            &tp->t_outq)) {
 709                                                 clist_unputc(&tp->t_outq);
 710                                                 break;
 711                                         }
 712                                         IFNET_STAT_INC(&sc->sc_if, obytes, 2);
 713                                 }
 714                         }
 715                         m = m_free(m);
 716                 }
 717
 718                 if (clist_putc(FRAME_END, &tp->t_outq)) {
 719                         /*
 720                          * Not enough room.  Remove a char to make room
 721                          * and end the packet normally.
 722                          * If you get many collisions (more than one or two
 723                          * a day) you probably do not have enough clists
 724                          * and you should increase "nclist" in param.c.
 725                          */
 726                         clist_unputc(&tp->t_outq);
 727                         clist_putc(FRAME_END, &tp->t_outq);
 728                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 729                 } else {
 730                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 731                         IFNET_STAT_INC(&sc->sc_if, opackets, 1);
 732                 }
 733         }
 734         lwkt_reltoken(&tty_token);
 735         return 0;
 736 }
 737
 738 /*
 739  * Copy data buffer to mbuf chain; add ifnet pointer.
 740  */
 741 static struct mbuf *
 742 sl_btom(struct sl_softc *sc, int len)
 743 {
 744         struct mbuf *m;
 745
 746         if (len >= MCLBYTES)
 747                 return (NULL);
 748
 749         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 750         if (m == NULL)
 751                 return (NULL);
 752
 753         /*
 754          * If we have more than MHLEN bytes, it's cheaper to
 755          * queue the cluster we just filled & allocate a new one
 756          * for the input buffer.  Otherwise, fill the mbuf we
 757          * allocated above.  Note that code in the input routine
 758          * guarantees that packet will fit in a cluster.
 759          */
 760         if (len >= MHLEN) {
 761                 MCLGET(m, MB_DONTWAIT);
 762                 if ((m->m_flags & M_EXT) == 0) {
 763                         /*
 764                          * we couldn't get a cluster - if memory's this
 765                          * low, it's time to start dropping packets.
 766                          */
 767                         m_free(m);
 768                         return (NULL);
 769                 }
 770         }
 771         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 772         m->m_len = len;
 773         m->m_pkthdr.len = len;
 774         m->m_pkthdr.rcvif = &sc->sc_if;
 775         return (m);
 776 }
 777
 778 /*
 779  * tty interface receiver interrupt.
 780  */
 781 static int
 782 slinput(int c, struct tty *tp)
 783 {
 784         struct sl_softc *sc;
 785         struct mbuf *m;
 786         int len;
 787         u_char chdr[CHDR_LEN];
 788
 789         lwkt_gettoken(&tty_token);
 790         tk_nin++;
 791         sc = (struct sl_softc *)tp->t_sc;
 792         if (sc == NULL) {
 793                 lwkt_reltoken(&tty_token);
 794                 return 0;
 795         }
 796         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 797                 sc->sc_flags |= SC_ERROR;
 798                 lwkt_reltoken(&tty_token);
 799                 return 0;
 800         }
 801         c &= TTY_CHARMASK;
 802
 803         IFNET_STAT_INC(&sc->sc_if, ibytes, 1);
 804
 805         if (sc->sc_if.if_flags & IFF_DEBUG) {
 806                 if (c == ABT_ESC) {
 807                         /*
 808                          * If we have a previous abort, see whether
 809                          * this one is within the time limit.
 810                          */
 811                         if (sc->sc_abortcount &&
 812                             time_uptime >= sc->sc_starttime + ABT_WINDOW)
 813                                 sc->sc_abortcount = 0;
 814                         /*
 815                          * If we see an abort after "idle" time, count it;
 816                          * record when the first abort escape arrived.
 817                          */
 818                         if (time_uptime >= sc->sc_lasttime + ABT_IDLE) {
 819                                 if (++sc->sc_abortcount == 1)
 820                                         sc->sc_starttime = time_uptime;
 821                                 if (sc->sc_abortcount >= ABT_COUNT) {
 822                                         slclose(tp,0);
 823                                         lwkt_reltoken(&tty_token);
 824                                         return 0;
 825                                 }
 826                         }
 827                 } else
 828                         sc->sc_abortcount = 0;
 829                 sc->sc_lasttime = time_uptime;
 830         }
 831
 832         switch (c) {
 833
 834         case TRANS_FRAME_ESCAPE:
 835                 if (sc->sc_escape)
 836                         c = FRAME_ESCAPE;
 837                 break;
 838
 839         case TRANS_FRAME_END:
 840                 if (sc->sc_escape)
 841                         c = FRAME_END;
 842                 break;
 843
 844         case FRAME_ESCAPE:
 845                 sc->sc_escape = 1;
 846                 lwkt_reltoken(&tty_token);
 847                 return 0;
 848
 849         case FRAME_END:
 850                 sc->sc_flags &= ~SC_KEEPALIVE;
 851                 if(sc->sc_flags & SC_ERROR) {
 852                         sc->sc_flags &= ~SC_ERROR;
 853                         goto newpack;
 854                 }
 855                 len = sc->sc_mp - sc->sc_buf;
 856                 if (len < 3)
 857                         /* less than min length packet - ignore */
 858                         goto newpack;
 859
 860                 if (sc->sc_if.if_bpf) {
 861                         /*
 862                          * Save the compressed header, so we
 863                          * can tack it on later.  Note that we
 864                          * will end up copying garbage in some
 865                          * cases but this is okay.  We remember
 866                          * where the buffer started so we can
 867                          * compute the new header length.
 868                          */
 869                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 870                 }
 871
 872                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 873                         if (c & 0x80)
 874                                 c = TYPE_COMPRESSED_TCP;
 875                         else if (c == TYPE_UNCOMPRESSED_TCP)
 876                                 *sc->sc_buf &= 0x4f; /* XXX */
 877                         /*
 878                          * We've got something that's not an IP packet.
 879                          * If compression is enabled, try to decompress it.
 880                          * Otherwise, if `auto-enable' compression is on and
 881                          * it's a reasonable packet, decompress it and then
 882                          * enable compression.  Otherwise, drop it.
 883                          */
 884                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 885                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 886                                                         (u_int)c, &sc->sc_comp);
 887                                 if (len <= 0)
 888                                         goto error;
 889                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 890                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 891                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 892                                                         (u_int)c, &sc->sc_comp);
 893                                 if (len <= 0)
 894                                         goto error;
 895                                 sc->sc_if.if_flags |= SC_COMPRESS;
 896                         } else
 897                                 goto error;
 898                 }
 899                 if (sc->sc_if.if_bpf) {
 900                         bpf_gettoken();
 901
 902                         if (sc->sc_if.if_bpf) {
 903                                 /*
 904                                  * Put the SLIP pseudo-"link header" in place.
 905                                  * We couldn't do this any earlier since
 906                                  * decompression probably moved the buffer
 907                                  * pointer.  Then, invoke BPF.
 908                                  */
 909                                 u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 910
 911                                 hp[SLX_DIR] = SLIPDIR_IN;
 912                                 bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 913                                 bpf_tap(sc->sc_if.if_bpf, hp,
 914                                     len + SLIP_HDRLEN);
 915                         }
 916
 917                         bpf_reltoken();
 918                 }
 919                 m = sl_btom(sc, len);
 920                 if (m == NULL)
 921                         goto error;
 922
 923                 IFNET_STAT_INC(&sc->sc_if, ipackets, 1);
 924
 925                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 926                         m_freem(m);
 927                         goto newpack;
 928                 }
 929
 930                 if (netisr_queue(NETISR_IP, m)) {
 931                         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 932                         IFNET_STAT_INC(&sc->sc_if, iqdrops, 1);
 933                 }
 934
 935                 goto newpack;
 936         }
 937         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 938                 *sc->sc_mp++ = c;
 939                 sc->sc_escape = 0;
 940                 lwkt_reltoken(&tty_token);
 941                 return 0;
 942         }
 943
 944         /* can't put lower; would miss an extra frame */
 945         sc->sc_flags |= SC_ERROR;
 946
 947 error:
 948         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 949 newpack:
 950         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 951         sc->sc_escape = 0;
 952         lwkt_reltoken(&tty_token);
 953         return 0;
 954 }
 955
 956 /*
 957  * Process an ioctl request.
 958  */
 959 static int
 960 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 961 {
 962         struct ifaddr *ifa = (struct ifaddr *)data;
 963         struct ifreq *ifr = (struct ifreq *)data;
 964         int error = 0;
 965
 966         crit_enter();
 967
 968         switch (cmd) {
 969
 970         case SIOCSIFFLAGS:
 971                 /*
 972                  * if.c will set the interface up even if we
 973                  * don't want it to.
 974                  */
 975                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 976                         ifp->if_flags &= ~IFF_UP;
 977                 }
 978                 break;
 979         case SIOCSIFADDR:
 980                 /*
 981                  * This is "historical" - set the interface up when
 982                  * setting the address.
 983                  */
 984                 if (ifa->ifa_addr->sa_family == AF_INET) {
 985                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 986                                 ifp->if_flags |= IFF_UP;
 987                 } else {
 988                         error = EAFNOSUPPORT;
 989                 }
 990                 break;
 991
 992         case SIOCSIFDSTADDR:
 993                 if (ifa->ifa_addr->sa_family != AF_INET)
 994                         error = EAFNOSUPPORT;
 995                 break;
 996
 997         case SIOCADDMULTI:
 998         case SIOCDELMULTI:
 999                 break;
1000
1001         case SIOCSIFMTU:
1002                 /*
1003                  * Set the interface MTU.
1004                  */
1005                 if (ifr->ifr_mtu > SLTMAX)
1006                         error = EINVAL;
1007                 else {
1008                         struct tty *tp;
1009
1010                         ifp->if_mtu = ifr->ifr_mtu;
1011                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
1012                         if (tp != NULL)
1013                                 clist_alloc_cblocks(&tp->t_outq,
1014                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
1015                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
1016                 }
1017                 break;
1018
1019         default:
1020                 error = EINVAL;
1021         }
1022
1023         crit_exit();
1024         return (error);
1025 }
1026
1027 static void
1028 sl_keepalive(void *chan)
1029 {
1030         struct sl_softc *sc = chan;
1031
1032         lwkt_gettoken(&tty_token);
1033         lwkt_gettoken(&proc_token);
1034         if (sc->sc_keepalive) {
1035                 if (sc->sc_flags & SC_KEEPALIVE)
1036                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
1037                 else
1038                         sc->sc_flags |= SC_KEEPALIVE;
1039                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
1040                                 sl_keepalive, sc);
1041         } else {
1042                 sc->sc_flags &= ~SC_KEEPALIVE;
1043         }
1044         lwkt_reltoken(&proc_token);
1045         lwkt_reltoken(&tty_token);
1046 }
1047
1048 static void
1049 sl_outfill(void *chan)
1050 {
1051         struct sl_softc *sc = chan;
1052         struct tty *tp = sc->sc_ttyp;
1053
1054         lwkt_gettoken(&tty_token);
1055
1056         if (sc->sc_outfill && tp != NULL) {
1057                 if (sc->sc_flags & SC_OUTWAIT) {
1058                         crit_enter();
1059                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
1060                         clist_putc(FRAME_END, &tp->t_outq);
1061                         (*tp->t_oproc)(tp);
1062                         crit_exit();
1063                 } else
1064                         sc->sc_flags |= SC_OUTWAIT;
1065                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1066                                 sl_outfill, sc);
1067         } else {
1068                 sc->sc_flags &= ~SC_OUTWAIT;
1069         }
1070         lwkt_reltoken(&tty_token);
1071 }