sys/net/sl/if_sl.c

   1 /*
   2  * Copyright (c) 1987, 1989, 1992, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)if_sl.c     8.6 (Berkeley) 2/1/94
  34  * $FreeBSD: src/sys/net/if_sl.c,v 1.84.2.2 2002/02/13 00:43:10 dillon Exp $
  35  * $DragonFly: src/sys/net/sl/if_sl.c,v 1.12 2004/04/22 04:22:06 dillon Exp $
  36  */
  37
  38 /*
  39  * Serial Line interface
  40  *
  41  * Rick Adams
  42  * Center for Seismic Studies
  43  * 1300 N 17th Street, Suite 1450
  44  * Arlington, Virginia 22209
  45  * (703)276-7900
  46  * rick@seismo.ARPA
  47  * seismo!rick
  48  *
  49  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  50  * N.B.: this belongs in netinet, not net, the way it stands now.
  51  * Should have a link-layer type designation, but wouldn't be
  52  * backwards-compatible.
  53  *
  54  * Converted to 4.3BSD Beta by Chris Torek.
  55  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  56  * W. Jolitz added slip abort.
  57  *
  58  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  59  * Added priority queuing for "interactive" traffic; hooks for TCP
  60  * header compression; ICMP filtering (at 2400 baud, some cretin
  61  * pinging you can use up all your bandwidth).  Made low clist behavior
  62  * more robust and slightly less likely to hang serial line.
  63  * Sped up a bunch of things.
  64  *
  65  * Note that splimp() is used throughout to block both (tty) input
  66  * interrupts and network activity; thus, splimp must be >= spltty.
  67  */
  68
  69 #include "use_sl.h"
  70
  71 #include "opt_inet.h"
  72 #if !defined(KLD_MODULE)
  73 #include "opt_slip.h"
  74 #endif
  75 #include <sys/param.h>
  76 #include <sys/systm.h>
  77 #include <sys/proc.h>
  78 #include <sys/malloc.h>
  79 #include <sys/mbuf.h>
  80 #include <sys/dkstat.h>
  81 #include <sys/socket.h>
  82 #include <sys/sockio.h>
  83 #include <sys/fcntl.h>
  84 #include <sys/signalvar.h>
  85 #include <sys/tty.h>
  86 #include <sys/clist.h>
  87 #include <sys/kernel.h>
  88 #include <sys/conf.h>
  89
  90 #include <net/if.h>
  91 #include <net/if_types.h>
  92 #include <net/netisr.h>
  93
  94 #if INET
  95 #include <netinet/in.h>
  96 #include <netinet/in_systm.h>
  97 #include <netinet/in_var.h>
  98 #include <netinet/ip.h>
  99 #else
 100 #error "Huh? Slip without inet?"
 101 #endif
 102
 103 #include <net/slcompress.h>
 104 #include "if_slvar.h"
 105 #include <net/slip.h>
 106
 107 #include <net/bpf.h>
 108
 109 #ifdef __i386__
 110 #include <i386/isa/intr_machdep.h>
 111 #endif
 112
 113 static void slattach (void *);
 114 PSEUDO_SET(slattach, if_sl);
 115
 116 /*
 117  * SLRMAX is a hard limit on input packet size.  To simplify the code
 118  * and improve performance, we require that packets fit in an mbuf
 119  * cluster, and if we get a compressed packet, there's enough extra
 120  * room to expand the header into a max length tcp/ip header (128
 121  * bytes).  So, SLRMAX can be at most
 122  *      MCLBYTES - 128
 123  *
 124  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 125  * small enough so that interactive use doesn't suffer, but large
 126  * enough to provide good performance. 552 is a good choice for SLMTU
 127  * because it is high enough to not fragment TCP packets being routed
 128  * through this host. Packet fragmentation is bad with SLIP because
 129  * fragment headers aren't compressed. The previous assumptions about
 130  * the best MTU value don't really hold when using modern modems with
 131  * BTLZ data compression because the modem buffers play a much larger
 132  * role in interactive performance than the MTU. The MTU can be changed
 133  * at any time to suit the specific environment with ifconfig(8), and
 134  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 135  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 136  * handles this better).
 137  *
 138  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 139  * of us (i.e., in clists waiting to be picked up by the tty output
 140  * interrupt).  If we queue a lot of data downstream, it's immune to
 141  * our t.o.s. queuing.
 142  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 143  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 144  * wait is dependent on the ftp window size but that's typically
 145  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 146  * the cost (in idle time on the wire) of the tty driver running
 147  * off the end of its clists & having to call back slstart for a
 148  * new packet.  For a tty interface with any buffering at all, this
 149  * cost will be zero.  Even with a totally brain dead interface (like
 150  * the one on a typical workstation), the cost will be <= 1 character
 151  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 152  * at most 1% while maintaining good interactive response.
 153  */
 154 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 155 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 156 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 157 #ifndef SLMTU
 158 #define SLMTU           552             /* default MTU */
 159 #endif
 160 #define SLTMAX          1500            /* maximum MTU */
 161 #define SLIP_HIWAT      roundup(50,CBSIZE)
 162 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 163
 164 /*
 165  * SLIP ABORT ESCAPE MECHANISM:
 166  *      (inspired by HAYES modem escape arrangement)
 167  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 168  *      within window time signals a "soft" exit from slip mode by remote end
 169  *      if the IFF_DEBUG flag is on.
 170  */
 171 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 172 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 173 #define ABT_COUNT       3       /* count of escapes for abort */
 174 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 175
 176 static struct sl_softc sl_softc[NSL];
 177
 178 #define FRAME_END               0xc0            /* Frame End */
 179 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 180 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 181 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 182
 183 static int slinit (struct sl_softc *);
 184 static struct mbuf *sl_btom (struct sl_softc *, int);
 185 static timeout_t sl_keepalive;
 186 static timeout_t sl_outfill;
 187 static int      slclose (struct tty *,int);
 188 static int      slinput (int, struct tty *);
 189 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 190 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct thread *);
 191 static int      slopen (dev_t, struct tty *);
 192 static int      sloutput (struct ifnet *,
 193             struct mbuf *, struct sockaddr *, struct rtentry *);
 194 static int      slstart (struct tty *);
 195
 196 static struct linesw slipdisc = {
 197         slopen,         slclose,        l_noread,       l_nowrite,
 198         sltioctl,       slinput,        slstart,        ttymodem,
 199         FRAME_END
 200 };
 201
 202 /*
 203  * Called from boot code to establish sl interfaces.
 204  */
 205 static void
 206 slattach(dummy)
 207         void *dummy;
 208 {
 209         struct sl_softc *sc;
 210         int i = 0;
 211
 212         linesw[SLIPDISC] = slipdisc;
 213
 214         for (sc = sl_softc; i < NSL; sc++) {
 215                 if_initname(&(sc->sc_if), "sl", i++);
 216                 sc->sc_if.if_mtu = SLMTU;
 217                 sc->sc_if.if_flags =
 218 #ifdef SLIP_IFF_OPTS
 219                     SLIP_IFF_OPTS;
 220 #else
 221                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 222 #endif
 223                 sc->sc_if.if_type = IFT_SLIP;
 224                 sc->sc_if.if_ioctl = slioctl;
 225                 sc->sc_if.if_output = sloutput;
 226                 sc->sc_if.if_snd.ifq_maxlen = 50;
 227                 sc->sc_fastq.ifq_maxlen = 32;
 228                 sc->sc_if.if_linkmib = sc;
 229                 sc->sc_if.if_linkmiblen = sizeof *sc;
 230                 if_attach(&sc->sc_if);
 231                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 232         }
 233 }
 234
 235 static int
 236 slinit(sc)
 237         struct sl_softc *sc;
 238 {
 239         caddr_t p;
 240
 241 #ifdef __i386__
 242         int s;
 243
 244         s = splhigh();
 245         tty_imask |= net_imask;
 246         net_imask = tty_imask;
 247         update_intr_masks();
 248         splx(s);
 249         if (bootverbose)
 250                 printf("new imasks: bio %x, tty %x, net %x\n",
 251                     bio_imask, tty_imask, net_imask);
 252 #endif
 253         if (sc->sc_ep == (u_char *) 0) {
 254                 MCLALLOC(p, M_WAIT);
 255                 if (p)
 256                         sc->sc_ep = (u_char *)p + SLBUFSIZE;
 257                 else {
 258                         printf("sl%ld: can't allocate buffer\n",
 259                             (long)(sc - sl_softc));
 260                         return (0);
 261                 }
 262         }
 263         sc->sc_buf = sc->sc_ep - SLRMAX;
 264         sc->sc_mp = sc->sc_buf;
 265         sl_compress_init(&sc->sc_comp, -1);
 266         return (1);
 267 }
 268
 269 /*
 270  * Line specific open routine.
 271  * Attach the given tty to the first available sl unit.
 272  */
 273 /* ARGSUSED */
 274 static int
 275 slopen(dev_t dev, struct tty *tp)
 276 {
 277         struct sl_softc *sc;
 278         int nsl;
 279         int s, error;
 280         struct thread *td = curthread;  /* XXX */
 281
 282         error = suser(td);
 283         if (error)
 284                 return (error);
 285
 286         if (tp->t_line == SLIPDISC)
 287                 return (0);
 288
 289         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 290                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 291                         if (slinit(sc) == 0)
 292                                 return (ENOBUFS);
 293                         tp->t_sc = (caddr_t)sc;
 294                         sc->sc_ttyp = tp;
 295                         sc->sc_if.if_baudrate = tp->t_ospeed;
 296                         ttyflush(tp, FREAD | FWRITE);
 297
 298                         tp->t_line = SLIPDISC;
 299                         /*
 300                          * We don't use t_canq or t_rawq, so reduce their
 301                          * cblock resources to 0.  Reserve enough cblocks
 302                          * for t_outq to guarantee that we can fit a full
 303                          * packet if the SLIP_HIWAT check allows slstart()
 304                          * to loop.  Use the same value for the cblock
 305                          * limit since the reserved blocks should always
 306                          * be enough.  Reserving cblocks probably makes
 307                          * the CLISTRESERVE check unnecessary and wasteful.
 308                          */
 309                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 310                         clist_alloc_cblocks(&tp->t_outq,
 311                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 312                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 313                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 314
 315                         s = splnet();
 316                         if_up(&sc->sc_if);
 317                         splx(s);
 318                         return (0);
 319                 }
 320         return (ENXIO);
 321 }
 322
 323 /*
 324  * Line specific close routine.
 325  * Detach the tty from the sl unit.
 326  */
 327 static int
 328 slclose(tp,flag)
 329         struct tty *tp;
 330         int flag;
 331 {
 332         struct sl_softc *sc;
 333         int s;
 334
 335         ttyflush(tp, FREAD | FWRITE);
 336         /*
 337          * XXX the placement of the following spl is misleading.  tty
 338          * interrupts must be blocked across line discipline switches
 339          * and throughout closes to avoid races.
 340          */
 341         s = splimp();           /* actually, max(spltty, splnet) */
 342         clist_free_cblocks(&tp->t_outq);
 343         tp->t_line = 0;
 344         sc = (struct sl_softc *)tp->t_sc;
 345         if (sc != NULL) {
 346                 if (sc->sc_outfill) {
 347                         sc->sc_outfill = 0;
 348                         untimeout(sl_outfill, sc, sc->sc_ofhandle);
 349                 }
 350                 if (sc->sc_keepalive) {
 351                         sc->sc_keepalive = 0;
 352                         untimeout(sl_keepalive, sc, sc->sc_kahandle);
 353                 }
 354                 if_down(&sc->sc_if);
 355                 sc->sc_flags &= SC_STATIC;
 356                 sc->sc_ttyp = NULL;
 357                 tp->t_sc = NULL;
 358                 m_mclfree((caddr_t)(sc->sc_ep - SLBUFSIZE));
 359                 sc->sc_ep = 0;
 360                 sc->sc_mp = 0;
 361                 sc->sc_buf = 0;
 362         }
 363         splx(s);
 364         return 0;
 365 }
 366
 367 /*
 368  * Line specific (tty) ioctl routine.
 369  * Provide a way to get the sl unit number.
 370  */
 371 /* ARGSUSED */
 372 static int
 373 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 374 {
 375         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 376         int s, nsl;
 377
 378         s = splimp();
 379         switch (cmd) {
 380         case SLIOCGUNIT:
 381                 *(int *)data = sc->sc_if.if_dunit;
 382                 break;
 383
 384         case SLIOCSUNIT:
 385                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 386                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 387                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 388                                     && nc->sc_ttyp == NULL
 389                                    ) {
 390                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 391                                                        M_WAITOK);
 392                                         *tmpnc = *nc;
 393                                         *nc = *sc;
 394                                         nc->sc_if = tmpnc->sc_if;
 395                                         tmpnc->sc_if = sc->sc_if;
 396                                         *sc = *tmpnc;
 397                                         free(tmpnc, M_TEMP);
 398                                         if (sc->sc_if.if_flags & IFF_UP) {
 399                                                 if_down(&sc->sc_if);
 400                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 401                                                         if_up(&nc->sc_if);
 402                                         } else if (nc->sc_if.if_flags & IFF_UP)
 403                                                 if_down(&nc->sc_if);
 404                                         sc->sc_flags &= ~SC_STATIC;
 405                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 406                                         tp->t_sc = sc = nc;
 407                                         clist_alloc_cblocks(&tp->t_outq,
 408                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 409                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 410                                         sl_compress_init(&sc->sc_comp, -1);
 411                                         goto slfound;
 412                                 }
 413                         }
 414                         splx(s);
 415                         return (ENXIO);
 416                 }
 417         slfound:
 418                 sc->sc_flags |= SC_STATIC;
 419                 break;
 420
 421         case SLIOCSKEEPAL:
 422                 sc->sc_keepalive = *(u_int *)data * hz;
 423                 if (sc->sc_keepalive) {
 424                         sc->sc_flags |= SC_KEEPALIVE;
 425                         sc->sc_kahandle = timeout(sl_keepalive, sc,
 426                                                   sc->sc_keepalive);
 427                 } else {
 428                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 429                                 untimeout(sl_keepalive, sc, sc->sc_kahandle);
 430                                 sc->sc_flags &= ~SC_KEEPALIVE;
 431                         }
 432                 }
 433                 break;
 434
 435         case SLIOCGKEEPAL:
 436                 *(int *)data = sc->sc_keepalive / hz;
 437                 break;
 438
 439         case SLIOCSOUTFILL:
 440                 sc->sc_outfill = *(u_int *)data * hz;
 441                 if (sc->sc_outfill) {
 442                         sc->sc_flags |= SC_OUTWAIT;
 443                         sc->sc_ofhandle = timeout(sl_outfill, sc,
 444                                                   sc->sc_outfill);
 445                 } else {
 446                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 447                                 untimeout(sl_outfill, sc, sc->sc_ofhandle);
 448                                 sc->sc_flags &= ~SC_OUTWAIT;
 449                         }
 450                 }
 451                 break;
 452
 453         case SLIOCGOUTFILL:
 454                 *(int *)data = sc->sc_outfill / hz;
 455                 break;
 456
 457         default:
 458                 splx(s);
 459                 return (ENOIOCTL);
 460         }
 461         splx(s);
 462         return (0);
 463 }
 464
 465 /*
 466  * Queue a packet.  Start transmission if not active.
 467  * Compression happens in slstart; if we do it here, IP TOS
 468  * will cause us to not compress "background" packets, because
 469  * ordering gets trashed.  It can be done for all packets in slstart.
 470  */
 471 static int
 472 sloutput(ifp, m, dst, rtp)
 473         struct ifnet *ifp;
 474         struct mbuf *m;
 475         struct sockaddr *dst;
 476         struct rtentry *rtp;
 477 {
 478         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 479         struct ip *ip;
 480         struct ifqueue *ifq;
 481         int s;
 482
 483         /*
 484          * `Cannot happen' (see slioctl).  Someday we will extend
 485          * the line protocol to support other address families.
 486          */
 487         if (dst->sa_family != AF_INET) {
 488                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 489                         dst->sa_family);
 490                 m_freem(m);
 491                 sc->sc_if.if_noproto++;
 492                 return (EAFNOSUPPORT);
 493         }
 494
 495         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 496                 m_freem(m);
 497                 return (ENETDOWN);
 498         }
 499         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 500                 m_freem(m);
 501                 return (EHOSTUNREACH);
 502         }
 503         ifq = &sc->sc_if.if_snd;
 504         ip = mtod(m, struct ip *);
 505         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 506                 m_freem(m);
 507                 return (ENETRESET);             /* XXX ? */
 508         }
 509         if (ip->ip_tos & IPTOS_LOWDELAY)
 510                 ifq = &sc->sc_fastq;
 511         s = splimp();
 512         if (IF_QFULL(ifq)) {
 513                 IF_DROP(ifq);
 514                 m_freem(m);
 515                 splx(s);
 516                 sc->sc_if.if_oerrors++;
 517                 return (ENOBUFS);
 518         }
 519         IF_ENQUEUE(ifq, m);
 520         if (sc->sc_ttyp->t_outq.c_cc == 0)
 521                 slstart(sc->sc_ttyp);
 522         splx(s);
 523         return (0);
 524 }
 525
 526 /*
 527  * Start output on interface.  Get another datagram
 528  * to send from the interface queue and map it to
 529  * the interface before starting output.
 530  */
 531 static int
 532 slstart(tp)
 533         struct tty *tp;
 534 {
 535         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 536         struct mbuf *m;
 537         u_char *cp;
 538         struct ip *ip;
 539         int s;
 540         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 541         int len = 0;
 542
 543         for (;;) {
 544                 /*
 545                  * Call output process whether or not there is more in the
 546                  * output queue.  We are being called in lieu of ttstart
 547                  * and must do what it would.
 548                  */
 549                 (*tp->t_oproc)(tp);
 550
 551                 if (tp->t_outq.c_cc != 0) {
 552                         if (sc != NULL)
 553                                 sc->sc_flags &= ~SC_OUTWAIT;
 554                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 555                                 return 0;
 556                 }
 557
 558                 /*
 559                  * This happens briefly when the line shuts down.
 560                  */
 561                 if (sc == NULL)
 562                         return 0;
 563
 564                 /*
 565                  * Get a packet and send it to the interface.
 566                  */
 567                 s = splimp();
 568                 IF_DEQUEUE(&sc->sc_fastq, m);
 569                 if (m)
 570                         sc->sc_if.if_omcasts++;         /* XXX */
 571                 else
 572                         IF_DEQUEUE(&sc->sc_if.if_snd, m);
 573                 splx(s);
 574                 if (m == NULL)
 575                         return 0;
 576
 577                 /*
 578                  * We do the header compression here rather than in sloutput
 579                  * because the packets will be out of order if we are using TOS
 580                  * queueing, and the connection id compression will get
 581                  * munged when this happens.
 582                  */
 583                 if (sc->sc_if.if_bpf) {
 584                         /*
 585                          * We need to save the TCP/IP header before it's
 586                          * compressed.  To avoid complicated code, we just
 587                          * copy the entire packet into a stack buffer (since
 588                          * this is a serial line, packets should be short
 589                          * and/or the copy should be negligible cost compared
 590                          * to the packet transmission time).
 591                          */
 592                         struct mbuf *m1 = m;
 593                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 594
 595                         len = 0;
 596                         do {
 597                                 int mlen = m1->m_len;
 598
 599                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 600                                 cp += mlen;
 601                                 len += mlen;
 602                         } while ((m1 = m1->m_next) != NULL);
 603                 }
 604                 ip = mtod(m, struct ip *);
 605                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 606                         if (sc->sc_if.if_flags & SC_COMPRESS)
 607                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 608                                     &sc->sc_comp, 1);
 609                 }
 610                 if (sc->sc_if.if_bpf) {
 611                         /*
 612                          * Put the SLIP pseudo-"link header" in place.  The
 613                          * compressed header is now at the beginning of the
 614                          * mbuf.
 615                          */
 616                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 617                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 618                         bpf_tap(&sc->sc_if, bpfbuf, len + SLIP_HDRLEN);
 619                 }
 620
 621                 /*
 622                  * If system is getting low on clists, just flush our
 623                  * output queue (if the stuff was important, it'll get
 624                  * retransmitted). Note that SLTMAX is used instead of
 625                  * the current if_mtu setting because connections that
 626                  * have already been established still use the original
 627                  * (possibly larger) mss.
 628                  */
 629                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 630                         m_freem(m);
 631                         sc->sc_if.if_collisions++;
 632                         continue;
 633                 }
 634
 635                 sc->sc_flags &= ~SC_OUTWAIT;
 636                 /*
 637                  * The extra FRAME_END will start up a new packet, and thus
 638                  * will flush any accumulated garbage.  We do this whenever
 639                  * the line may have been idle for some time.
 640                  */
 641                 if (tp->t_outq.c_cc == 0) {
 642                         ++sc->sc_if.if_obytes;
 643                         (void) putc(FRAME_END, &tp->t_outq);
 644                 }
 645
 646                 while (m) {
 647                         u_char *ep;
 648
 649                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 650                         while (cp < ep) {
 651                                 /*
 652                                  * Find out how many bytes in the string we can
 653                                  * handle without doing something special.
 654                                  */
 655                                 u_char *bp = cp;
 656
 657                                 while (cp < ep) {
 658                                         switch (*cp++) {
 659                                         case FRAME_ESCAPE:
 660                                         case FRAME_END:
 661                                                 --cp;
 662                                                 goto out;
 663                                         }
 664                                 }
 665                                 out:
 666                                 if (cp > bp) {
 667                                         /*
 668                                          * Put n characters at once
 669                                          * into the tty output queue.
 670                                          */
 671                                         if (b_to_q((char *)bp, cp - bp,
 672                                             &tp->t_outq))
 673                                                 break;
 674                                         sc->sc_if.if_obytes += cp - bp;
 675                                 }
 676                                 /*
 677                                  * If there are characters left in the mbuf,
 678                                  * the first one must be special..
 679                                  * Put it out in a different form.
 680                                  */
 681                                 if (cp < ep) {
 682                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 683                                                 break;
 684                                         if (putc(*cp++ == FRAME_ESCAPE ?
 685                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 686                                            &tp->t_outq)) {
 687                                                 (void) unputc(&tp->t_outq);
 688                                                 break;
 689                                         }
 690                                         sc->sc_if.if_obytes += 2;
 691                                 }
 692                         }
 693                         m = m_free(m);
 694                 }
 695
 696                 if (putc(FRAME_END, &tp->t_outq)) {
 697                         /*
 698                          * Not enough room.  Remove a char to make room
 699                          * and end the packet normally.
 700                          * If you get many collisions (more than one or two
 701                          * a day) you probably do not have enough clists
 702                          * and you should increase "nclist" in param.c.
 703                          */
 704                         (void) unputc(&tp->t_outq);
 705                         (void) putc(FRAME_END, &tp->t_outq);
 706                         sc->sc_if.if_collisions++;
 707                 } else {
 708                         ++sc->sc_if.if_obytes;
 709                         sc->sc_if.if_opackets++;
 710                 }
 711         }
 712         return 0;
 713 }
 714
 715 /*
 716  * Copy data buffer to mbuf chain; add ifnet pointer.
 717  */
 718 static struct mbuf *
 719 sl_btom(sc, len)
 720         struct sl_softc *sc;
 721         int len;
 722 {
 723         struct mbuf *m;
 724
 725         MGETHDR(m, M_DONTWAIT, MT_DATA);
 726         if (m == NULL)
 727                 return (NULL);
 728
 729         /*
 730          * If we have more than MHLEN bytes, it's cheaper to
 731          * queue the cluster we just filled & allocate a new one
 732          * for the input buffer.  Otherwise, fill the mbuf we
 733          * allocated above.  Note that code in the input routine
 734          * guarantees that packet will fit in a cluster.
 735          */
 736         if (len >= MHLEN) {
 737                 MCLGET(m, M_DONTWAIT);
 738                 if ((m->m_flags & M_EXT) == 0) {
 739                         /*
 740                          * we couldn't get a cluster - if memory's this
 741                          * low, it's time to start dropping packets.
 742                          */
 743                         (void) m_free(m);
 744                         return (NULL);
 745                 }
 746                 sc->sc_ep = mtod(m, u_char *) + SLBUFSIZE;
 747                 m->m_data = (caddr_t)sc->sc_buf;
 748                 m->m_ext.ext_buf = (caddr_t)((intptr_t)sc->sc_buf &~ MCLOFSET);
 749         } else
 750                 bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 751
 752         m->m_len = len;
 753         m->m_pkthdr.len = len;
 754         m->m_pkthdr.rcvif = &sc->sc_if;
 755         return (m);
 756 }
 757
 758 /*
 759  * tty interface receiver interrupt.
 760  */
 761 static int
 762 slinput(c, tp)
 763         int c;
 764         struct tty *tp;
 765 {
 766         struct sl_softc *sc;
 767         struct mbuf *m;
 768         int len;
 769         u_char chdr[CHDR_LEN];
 770
 771         tk_nin++;
 772         sc = (struct sl_softc *)tp->t_sc;
 773         if (sc == NULL)
 774                 return 0;
 775         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 776                 sc->sc_flags |= SC_ERROR;
 777                 return 0;
 778         }
 779         c &= TTY_CHARMASK;
 780
 781         ++sc->sc_if.if_ibytes;
 782
 783         if (sc->sc_if.if_flags & IFF_DEBUG) {
 784                 if (c == ABT_ESC) {
 785                         /*
 786                          * If we have a previous abort, see whether
 787                          * this one is within the time limit.
 788                          */
 789                         if (sc->sc_abortcount &&
 790                             time_second >= sc->sc_starttime + ABT_WINDOW)
 791                                 sc->sc_abortcount = 0;
 792                         /*
 793                          * If we see an abort after "idle" time, count it;
 794                          * record when the first abort escape arrived.
 795                          */
 796                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 797                                 if (++sc->sc_abortcount == 1)
 798                                         sc->sc_starttime = time_second;
 799                                 if (sc->sc_abortcount >= ABT_COUNT) {
 800                                         slclose(tp,0);
 801                                         return 0;
 802                                 }
 803                         }
 804                 } else
 805                         sc->sc_abortcount = 0;
 806                 sc->sc_lasttime = time_second;
 807         }
 808
 809         switch (c) {
 810
 811         case TRANS_FRAME_ESCAPE:
 812                 if (sc->sc_escape)
 813                         c = FRAME_ESCAPE;
 814                 break;
 815
 816         case TRANS_FRAME_END:
 817                 if (sc->sc_escape)
 818                         c = FRAME_END;
 819                 break;
 820
 821         case FRAME_ESCAPE:
 822                 sc->sc_escape = 1;
 823                 return 0;
 824
 825         case FRAME_END:
 826                 sc->sc_flags &= ~SC_KEEPALIVE;
 827                 if(sc->sc_flags & SC_ERROR) {
 828                         sc->sc_flags &= ~SC_ERROR;
 829                         goto newpack;
 830                 }
 831                 len = sc->sc_mp - sc->sc_buf;
 832                 if (len < 3)
 833                         /* less than min length packet - ignore */
 834                         goto newpack;
 835
 836                 if (sc->sc_if.if_bpf) {
 837                         /*
 838                          * Save the compressed header, so we
 839                          * can tack it on later.  Note that we
 840                          * will end up copying garbage in some
 841                          * cases but this is okay.  We remember
 842                          * where the buffer started so we can
 843                          * compute the new header length.
 844                          */
 845                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 846                 }
 847
 848                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 849                         if (c & 0x80)
 850                                 c = TYPE_COMPRESSED_TCP;
 851                         else if (c == TYPE_UNCOMPRESSED_TCP)
 852                                 *sc->sc_buf &= 0x4f; /* XXX */
 853                         /*
 854                          * We've got something that's not an IP packet.
 855                          * If compression is enabled, try to decompress it.
 856                          * Otherwise, if `auto-enable' compression is on and
 857                          * it's a reasonable packet, decompress it and then
 858                          * enable compression.  Otherwise, drop it.
 859                          */
 860                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 861                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 862                                                         (u_int)c, &sc->sc_comp);
 863                                 if (len <= 0)
 864                                         goto error;
 865                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 866                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 867                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 868                                                         (u_int)c, &sc->sc_comp);
 869                                 if (len <= 0)
 870                                         goto error;
 871                                 sc->sc_if.if_flags |= SC_COMPRESS;
 872                         } else
 873                                 goto error;
 874                 }
 875                 if (sc->sc_if.if_bpf) {
 876                         /*
 877                          * Put the SLIP pseudo-"link header" in place.
 878                          * We couldn't do this any earlier since
 879                          * decompression probably moved the buffer
 880                          * pointer.  Then, invoke BPF.
 881                          */
 882                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 883
 884                         hp[SLX_DIR] = SLIPDIR_IN;
 885                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 886                         bpf_tap(&sc->sc_if, hp, len + SLIP_HDRLEN);
 887                 }
 888                 m = sl_btom(sc, len);
 889                 if (m == NULL)
 890                         goto error;
 891
 892                 sc->sc_if.if_ipackets++;
 893
 894                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 895                         m_freem(m);
 896                         goto newpack;
 897                 }
 898
 899                 if (netisr_queue(NETISR_IP, m)) {
 900                         sc->sc_if.if_ierrors++;
 901                         sc->sc_if.if_iqdrops++;
 902                 }
 903
 904                 goto newpack;
 905         }
 906         if (sc->sc_mp < sc->sc_ep) {
 907                 *sc->sc_mp++ = c;
 908                 sc->sc_escape = 0;
 909                 return 0;
 910         }
 911
 912         /* can't put lower; would miss an extra frame */
 913         sc->sc_flags |= SC_ERROR;
 914
 915 error:
 916         sc->sc_if.if_ierrors++;
 917 newpack:
 918         sc->sc_mp = sc->sc_buf = sc->sc_ep - SLRMAX;
 919         sc->sc_escape = 0;
 920         return 0;
 921 }
 922
 923 /*
 924  * Process an ioctl request.
 925  */
 926 static int
 927 slioctl(ifp, cmd, data, cr)
 928         struct ifnet *ifp;
 929         u_long cmd;
 930         caddr_t data;
 931         struct ucred *cr;
 932 {
 933         struct ifaddr *ifa = (struct ifaddr *)data;
 934         struct ifreq *ifr = (struct ifreq *)data;
 935         int s, error = 0;
 936
 937         s = splimp();
 938
 939         switch (cmd) {
 940
 941         case SIOCSIFFLAGS:
 942                 /*
 943                  * if.c will set the interface up even if we
 944                  * don't want it to.
 945                  */
 946                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 947                         ifp->if_flags &= ~IFF_UP;
 948                 }
 949                 break;
 950         case SIOCSIFADDR:
 951                 /*
 952                  * This is "historical" - set the interface up when
 953                  * setting the address.
 954                  */
 955                 if (ifa->ifa_addr->sa_family == AF_INET) {
 956                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 957                                 ifp->if_flags |= IFF_UP;
 958                 } else {
 959                         error = EAFNOSUPPORT;
 960                 }
 961                 break;
 962
 963         case SIOCSIFDSTADDR:
 964                 if (ifa->ifa_addr->sa_family != AF_INET)
 965                         error = EAFNOSUPPORT;
 966                 break;
 967
 968         case SIOCADDMULTI:
 969         case SIOCDELMULTI:
 970                 break;
 971
 972         case SIOCSIFMTU:
 973                 /*
 974                  * Set the interface MTU.
 975                  */
 976                 if (ifr->ifr_mtu > SLTMAX)
 977                         error = EINVAL;
 978                 else {
 979                         struct tty *tp;
 980
 981                         ifp->if_mtu = ifr->ifr_mtu;
 982                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 983                         if (tp != NULL)
 984                                 clist_alloc_cblocks(&tp->t_outq,
 985                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 986                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 987                 }
 988                 break;
 989
 990         default:
 991                 error = EINVAL;
 992         }
 993         splx(s);
 994         return (error);
 995 }
 996
 997 static void
 998 sl_keepalive(chan)
 999         void *chan;
1000 {
1001         struct sl_softc *sc = chan;
1002
1003         if (sc->sc_keepalive) {
1004                 if (sc->sc_flags & SC_KEEPALIVE)
1005                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
1006                 else
1007                         sc->sc_flags |= SC_KEEPALIVE;
1008                 sc->sc_kahandle = timeout(sl_keepalive, sc, sc->sc_keepalive);
1009         } else {
1010                 sc->sc_flags &= ~SC_KEEPALIVE;
1011         }
1012 }
1013
1014 static void
1015 sl_outfill(chan)
1016         void *chan;
1017 {
1018         struct sl_softc *sc = chan;
1019         struct tty *tp = sc->sc_ttyp;
1020         int s;
1021
1022         if (sc->sc_outfill && tp != NULL) {
1023                 if (sc->sc_flags & SC_OUTWAIT) {
1024                         s = splimp ();
1025                         ++sc->sc_if.if_obytes;
1026                         (void) putc(FRAME_END, &tp->t_outq);
1027                         (*tp->t_oproc)(tp);
1028                         splx (s);
1029                 } else
1030                         sc->sc_flags |= SC_OUTWAIT;
1031                 sc->sc_ofhandle = timeout(sl_outfill, sc, sc->sc_outfill);
1032         } else {
1033                 sc->sc_flags &= ~SC_OUTWAIT;
1034         }
1035 }