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 1.21 2005/11/28 17:13:46 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
  66 #include "use_sl.h"
  67
  68 #include "opt_inet.h"
  69 #if !defined(KLD_MODULE)
  70 #include "opt_slip.h"
  71 #endif
  72 #include <sys/param.h>
  73 #include <sys/systm.h>
  74 #include <sys/proc.h>
  75 #include <sys/malloc.h>
  76 #include <sys/mbuf.h>
  77 #include <sys/dkstat.h>
  78 #include <sys/socket.h>
  79 #include <sys/sockio.h>
  80 #include <sys/fcntl.h>
  81 #include <sys/signalvar.h>
  82 #include <sys/tty.h>
  83 #include <sys/clist.h>
  84 #include <sys/kernel.h>
  85 #include <sys/conf.h>
  86 #include <sys/thread2.h>
  87
  88 #include <net/if.h>
  89 #include <net/if_types.h>
  90 #include <net/ifq_var.h>
  91 #include <net/netisr.h>
  92
  93 #if INET
  94 #include <netinet/in.h>
  95 #include <netinet/in_systm.h>
  96 #include <netinet/in_var.h>
  97 #include <netinet/ip.h>
  98 #else
  99 #error "Huh? Slip without inet?"
 100 #endif
 101
 102 #include <net/slcompress.h>
 103 #include "if_slvar.h"
 104 #include <net/slip.h>
 105
 106 #include <net/bpf.h>
 107
 108 #ifdef __i386__
 109 #include <i386/isa/intr_machdep.h>
 110 #endif
 111
 112 static void slattach (void *);
 113 PSEUDO_SET(slattach, if_sl);
 114
 115 /*
 116  * SLRMAX is a hard limit on input packet size.  To simplify the code
 117  * and improve performance, we require that packets fit in an mbuf
 118  * cluster, and if we get a compressed packet, there's enough extra
 119  * room to expand the header into a max length tcp/ip header (128
 120  * bytes).  So, SLRMAX can be at most
 121  *      MCLBYTES - 128
 122  *
 123  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 124  * small enough so that interactive use doesn't suffer, but large
 125  * enough to provide good performance. 552 is a good choice for SLMTU
 126  * because it is high enough to not fragment TCP packets being routed
 127  * through this host. Packet fragmentation is bad with SLIP because
 128  * fragment headers aren't compressed. The previous assumptions about
 129  * the best MTU value don't really hold when using modern modems with
 130  * BTLZ data compression because the modem buffers play a much larger
 131  * role in interactive performance than the MTU. The MTU can be changed
 132  * at any time to suit the specific environment with ifconfig(8), and
 133  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 134  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 135  * handles this better).
 136  *
 137  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 138  * of us (i.e., in clists waiting to be picked up by the tty output
 139  * interrupt).  If we queue a lot of data downstream, it's immune to
 140  * our t.o.s. queuing.
 141  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 142  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 143  * wait is dependent on the ftp window size but that's typically
 144  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 145  * the cost (in idle time on the wire) of the tty driver running
 146  * off the end of its clists & having to call back slstart for a
 147  * new packet.  For a tty interface with any buffering at all, this
 148  * cost will be zero.  Even with a totally brain dead interface (like
 149  * the one on a typical workstation), the cost will be <= 1 character
 150  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 151  * at most 1% while maintaining good interactive response.
 152  */
 153 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 154 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 155 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 156 #ifndef SLMTU
 157 #define SLMTU           552             /* default MTU */
 158 #endif
 159 #define SLTMAX          1500            /* maximum MTU */
 160 #define SLIP_HIWAT      roundup(50,CBSIZE)
 161 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 162
 163 /*
 164  * SLIP ABORT ESCAPE MECHANISM:
 165  *      (inspired by HAYES modem escape arrangement)
 166  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 167  *      within window time signals a "soft" exit from slip mode by remote end
 168  *      if the IFF_DEBUG flag is on.
 169  */
 170 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 171 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 172 #define ABT_COUNT       3       /* count of escapes for abort */
 173 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 174
 175 static struct sl_softc sl_softc[NSL];
 176
 177 #define FRAME_END               0xc0            /* Frame End */
 178 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 179 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 180 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 181
 182 static int slinit (struct sl_softc *);
 183 static struct mbuf *sl_btom (struct sl_softc *, int);
 184 static timeout_t sl_keepalive;
 185 static timeout_t sl_outfill;
 186 static int      slclose (struct tty *,int);
 187 static int      slinput (int, struct tty *);
 188 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 189 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct thread *);
 190 static int      slopen (dev_t, struct tty *);
 191 static int      sloutput (struct ifnet *,
 192             struct mbuf *, struct sockaddr *, struct rtentry *);
 193 static int      slstart (struct tty *);
 194
 195 static struct linesw slipdisc = {
 196         slopen,         slclose,        l_noread,       l_nowrite,
 197         sltioctl,       slinput,        slstart,        ttymodem,
 198         FRAME_END
 199 };
 200
 201 /*
 202  * Called from boot code to establish sl interfaces.
 203  */
 204 static void
 205 slattach(dummy)
 206         void *dummy;
 207 {
 208         struct sl_softc *sc;
 209         int i = 0;
 210
 211         linesw[SLIPDISC] = slipdisc;
 212
 213         for (sc = sl_softc; i < NSL; sc++) {
 214                 if_initname(&(sc->sc_if), "sl", i++);
 215                 sc->sc_if.if_mtu = SLMTU;
 216                 sc->sc_if.if_flags =
 217 #ifdef SLIP_IFF_OPTS
 218                     SLIP_IFF_OPTS;
 219 #else
 220                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 221 #endif
 222                 sc->sc_if.if_type = IFT_SLIP;
 223                 sc->sc_if.if_ioctl = slioctl;
 224                 sc->sc_if.if_output = sloutput;
 225                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 226                 ifq_set_ready(&sc->sc_if.if_snd);
 227                 sc->sc_fastq.ifq_maxlen = 32;
 228                 sc->sc_if.if_linkmib = sc;
 229                 sc->sc_if.if_linkmiblen = sizeof *sc;
 230                 callout_init(&sc->sc_oftimeout);
 231                 callout_init(&sc->sc_katimeout);
 232                 if_attach(&sc->sc_if, NULL);
 233                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 234         }
 235 }
 236
 237 static int
 238 slinit(sc)
 239         struct sl_softc *sc;
 240 {
 241         if (sc->sc_ep == NULL)
 242                 sc->sc_ep = malloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 243         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 244         sc->sc_mp = sc->sc_buf;
 245         sl_compress_init(&sc->sc_comp, -1);
 246         return (1);
 247 }
 248
 249 /*
 250  * Line specific open routine.
 251  * Attach the given tty to the first available sl unit.
 252  */
 253 /* ARGSUSED */
 254 static int
 255 slopen(dev_t dev, struct tty *tp)
 256 {
 257         struct sl_softc *sc;
 258         int nsl;
 259         int error;
 260         struct thread *td = curthread;  /* XXX */
 261
 262         error = suser(td);
 263         if (error)
 264                 return (error);
 265
 266         if (tp->t_line == SLIPDISC)
 267                 return (0);
 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                                 return (ENOBUFS);
 273                         tp->t_sc = (caddr_t)sc;
 274                         sc->sc_ttyp = tp;
 275                         sc->sc_if.if_baudrate = tp->t_ospeed;
 276                         ttyflush(tp, FREAD | FWRITE);
 277
 278                         tp->t_line = SLIPDISC;
 279                         /*
 280                          * We don't use t_canq or t_rawq, so reduce their
 281                          * cblock resources to 0.  Reserve enough cblocks
 282                          * for t_outq to guarantee that we can fit a full
 283                          * packet if the SLIP_HIWAT check allows slstart()
 284                          * to loop.  Use the same value for the cblock
 285                          * limit since the reserved blocks should always
 286                          * be enough.  Reserving cblocks probably makes
 287                          * the CLISTRESERVE check unnecessary and wasteful.
 288                          */
 289                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 290                         clist_alloc_cblocks(&tp->t_outq,
 291                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 292                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 293                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 294
 295                         crit_enter();
 296                         if_up(&sc->sc_if);
 297                         crit_exit();
 298                         return (0);
 299                 }
 300         return (ENXIO);
 301 }
 302
 303 /*
 304  * Line specific close routine.
 305  * Detach the tty from the sl unit.
 306  */
 307 static int
 308 slclose(tp,flag)
 309         struct tty *tp;
 310         int flag;
 311 {
 312         struct sl_softc *sc;
 313
 314         ttyflush(tp, FREAD | FWRITE);
 315         crit_enter();
 316
 317         clist_free_cblocks(&tp->t_outq);
 318         tp->t_line = 0;
 319         sc = (struct sl_softc *)tp->t_sc;
 320         if (sc != NULL) {
 321                 if (sc->sc_outfill) {
 322                         sc->sc_outfill = 0;
 323                         callout_stop(&sc->sc_oftimeout);
 324                 }
 325                 if (sc->sc_keepalive) {
 326                         sc->sc_keepalive = 0;
 327                         callout_stop(&sc->sc_katimeout);
 328                 }
 329                 if_down(&sc->sc_if);
 330                 sc->sc_flags &= SC_STATIC;
 331                 sc->sc_ttyp = NULL;
 332                 tp->t_sc = NULL;
 333                 if (sc->sc_ep) {
 334                         free(sc->sc_ep, M_DEVBUF);
 335                         sc->sc_ep = NULL;
 336                 }
 337                 sc->sc_mp = 0;
 338                 sc->sc_buf = 0;
 339         }
 340         crit_exit();
 341         return 0;
 342 }
 343
 344 /*
 345  * Line specific (tty) ioctl routine.
 346  * Provide a way to get the sl unit number.
 347  */
 348 /* ARGSUSED */
 349 static int
 350 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 351 {
 352         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 353         int nsl;
 354
 355         crit_enter();
 356
 357         switch (cmd) {
 358         case SLIOCGUNIT:
 359                 *(int *)data = sc->sc_if.if_dunit;
 360                 break;
 361
 362         case SLIOCSUNIT:
 363                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 364                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 365                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 366                                     && nc->sc_ttyp == NULL
 367                                    ) {
 368                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 369                                                        M_WAITOK);
 370                                         *tmpnc = *nc;
 371                                         *nc = *sc;
 372                                         nc->sc_if = tmpnc->sc_if;
 373                                         tmpnc->sc_if = sc->sc_if;
 374                                         *sc = *tmpnc;
 375                                         free(tmpnc, M_TEMP);
 376                                         if (sc->sc_if.if_flags & IFF_UP) {
 377                                                 if_down(&sc->sc_if);
 378                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 379                                                         if_up(&nc->sc_if);
 380                                         } else if (nc->sc_if.if_flags & IFF_UP)
 381                                                 if_down(&nc->sc_if);
 382                                         sc->sc_flags &= ~SC_STATIC;
 383                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 384                                         tp->t_sc = sc = nc;
 385                                         clist_alloc_cblocks(&tp->t_outq,
 386                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 387                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 388                                         sl_compress_init(&sc->sc_comp, -1);
 389                                         goto slfound;
 390                                 }
 391                         }
 392                         crit_exit();
 393                         return (ENXIO);
 394                 }
 395         slfound:
 396                 sc->sc_flags |= SC_STATIC;
 397                 break;
 398
 399         case SLIOCSKEEPAL:
 400                 sc->sc_keepalive = *(u_int *)data * hz;
 401                 if (sc->sc_keepalive) {
 402                         sc->sc_flags |= SC_KEEPALIVE;
 403                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 404                                         sl_keepalive, sc);
 405                 } else {
 406                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 407                                 callout_stop(&sc->sc_katimeout);
 408                                 sc->sc_flags &= ~SC_KEEPALIVE;
 409                         }
 410                 }
 411                 break;
 412
 413         case SLIOCGKEEPAL:
 414                 *(int *)data = sc->sc_keepalive / hz;
 415                 break;
 416
 417         case SLIOCSOUTFILL:
 418                 sc->sc_outfill = *(u_int *)data * hz;
 419                 if (sc->sc_outfill) {
 420                         sc->sc_flags |= SC_OUTWAIT;
 421                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 422                                         sl_outfill, sc);
 423                 } else {
 424                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 425                                 callout_stop(&sc->sc_oftimeout);
 426                                 sc->sc_flags &= ~SC_OUTWAIT;
 427                         }
 428                 }
 429                 break;
 430
 431         case SLIOCGOUTFILL:
 432                 *(int *)data = sc->sc_outfill / hz;
 433                 break;
 434
 435         default:
 436                 crit_exit();
 437                 return (ENOIOCTL);
 438         }
 439         crit_exit();
 440         return (0);
 441 }
 442
 443 /*
 444  * Queue a packet.  Start transmission if not active.
 445  * Compression happens in slstart; if we do it here, IP TOS
 446  * will cause us to not compress "background" packets, because
 447  * ordering gets trashed.  It can be done for all packets in slstart.
 448  */
 449 static int
 450 sloutput(ifp, m, dst, rtp)
 451         struct ifnet *ifp;
 452         struct mbuf *m;
 453         struct sockaddr *dst;
 454         struct rtentry *rtp;
 455 {
 456         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 457         struct ip *ip;
 458         int error;
 459         struct altq_pktattr pktattr;
 460
 461         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 462
 463         /*
 464          * `Cannot happen' (see slioctl).  Someday we will extend
 465          * the line protocol to support other address families.
 466          */
 467         if (dst->sa_family != AF_INET) {
 468                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 469                         dst->sa_family);
 470                 m_freem(m);
 471                 sc->sc_if.if_noproto++;
 472                 return (EAFNOSUPPORT);
 473         }
 474
 475         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 476                 m_freem(m);
 477                 return (ENETDOWN);
 478         }
 479         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 480                 m_freem(m);
 481                 return (EHOSTUNREACH);
 482         }
 483         ip = mtod(m, struct ip *);
 484         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 485                 m_freem(m);
 486                 return (ENETRESET);             /* XXX ? */
 487         }
 488
 489         crit_enter();
 490
 491         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 492                 if (IF_QFULL(&sc->sc_fastq)) {
 493                         IF_DROP(&sc->sc_fastq);
 494                         m_freem(m);
 495                         error = ENOBUFS;
 496                 } else {
 497                         IF_ENQUEUE(&sc->sc_fastq, m);
 498                         error = 0;
 499                 }
 500         } else {
 501                 lwkt_serialize_enter(sc->sc_if.if_serializer);
 502                 error = ifq_enqueue(&sc->sc_if.if_snd, m, &pktattr);
 503                 lwkt_serialize_enter(sc->sc_if.if_serializer);
 504         }
 505         if (error) {
 506                 sc->sc_if.if_oerrors++;
 507                 crit_exit();
 508                 return (error);
 509         }
 510         if (sc->sc_ttyp->t_outq.c_cc == 0)
 511                 slstart(sc->sc_ttyp);
 512         crit_exit();
 513         return (0);
 514 }
 515
 516 /*
 517  * Start output on interface.  Get another datagram
 518  * to send from the interface queue and map it to
 519  * the interface before starting output.
 520  */
 521 static int
 522 slstart(tp)
 523         struct tty *tp;
 524 {
 525         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 526         struct mbuf *m;
 527         u_char *cp;
 528         struct ip *ip;
 529         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 530         int len = 0;
 531
 532         for (;;) {
 533                 /*
 534                  * Call output process whether or not there is more in the
 535                  * output queue.  We are being called in lieu of ttstart
 536                  * and must do what it would.
 537                  */
 538                 (*tp->t_oproc)(tp);
 539
 540                 if (tp->t_outq.c_cc != 0) {
 541                         if (sc != NULL)
 542                                 sc->sc_flags &= ~SC_OUTWAIT;
 543                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 544                                 return 0;
 545                 }
 546
 547                 /*
 548                  * This happens briefly when the line shuts down.
 549                  */
 550                 if (sc == NULL)
 551                         return 0;
 552
 553                 /*
 554                  * Get a packet and send it to the interface.
 555                  */
 556                 crit_enter();
 557                 IF_DEQUEUE(&sc->sc_fastq, m);
 558                 if (m)
 559                         sc->sc_if.if_omcasts++;         /* XXX */
 560                 else
 561                         m = ifq_dequeue(&sc->sc_if.if_snd, NULL);
 562                 crit_exit();
 563                 if (m == NULL)
 564                         return 0;
 565
 566                 /*
 567                  * We do the header compression here rather than in sloutput
 568                  * because the packets will be out of order if we are using TOS
 569                  * queueing, and the connection id compression will get
 570                  * munged when this happens.
 571                  */
 572                 if (sc->sc_if.if_bpf) {
 573                         /*
 574                          * We need to save the TCP/IP header before it's
 575                          * compressed.  To avoid complicated code, we just
 576                          * copy the entire packet into a stack buffer (since
 577                          * this is a serial line, packets should be short
 578                          * and/or the copy should be negligible cost compared
 579                          * to the packet transmission time).
 580                          */
 581                         struct mbuf *m1 = m;
 582                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 583
 584                         len = 0;
 585                         do {
 586                                 int mlen = m1->m_len;
 587
 588                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 589                                 cp += mlen;
 590                                 len += mlen;
 591                         } while ((m1 = m1->m_next) != NULL);
 592                 }
 593                 ip = mtod(m, struct ip *);
 594                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 595                         if (sc->sc_if.if_flags & SC_COMPRESS)
 596                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 597                                     &sc->sc_comp, 1);
 598                 }
 599                 if (sc->sc_if.if_bpf) {
 600                         /*
 601                          * Put the SLIP pseudo-"link header" in place.  The
 602                          * compressed header is now at the beginning of the
 603                          * mbuf.
 604                          */
 605                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 606                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 607                         bpf_tap(sc->sc_if.if_bpf, bpfbuf, len + SLIP_HDRLEN);
 608                 }
 609
 610                 /*
 611                  * If system is getting low on clists, just flush our
 612                  * output queue (if the stuff was important, it'll get
 613                  * retransmitted). Note that SLTMAX is used instead of
 614                  * the current if_mtu setting because connections that
 615                  * have already been established still use the original
 616                  * (possibly larger) mss.
 617                  */
 618                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 619                         m_freem(m);
 620                         sc->sc_if.if_collisions++;
 621                         continue;
 622                 }
 623
 624                 sc->sc_flags &= ~SC_OUTWAIT;
 625                 /*
 626                  * The extra FRAME_END will start up a new packet, and thus
 627                  * will flush any accumulated garbage.  We do this whenever
 628                  * the line may have been idle for some time.
 629                  */
 630                 if (tp->t_outq.c_cc == 0) {
 631                         ++sc->sc_if.if_obytes;
 632                         (void) putc(FRAME_END, &tp->t_outq);
 633                 }
 634
 635                 while (m) {
 636                         u_char *ep;
 637
 638                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 639                         while (cp < ep) {
 640                                 /*
 641                                  * Find out how many bytes in the string we can
 642                                  * handle without doing something special.
 643                                  */
 644                                 u_char *bp = cp;
 645
 646                                 while (cp < ep) {
 647                                         switch (*cp++) {
 648                                         case FRAME_ESCAPE:
 649                                         case FRAME_END:
 650                                                 --cp;
 651                                                 goto out;
 652                                         }
 653                                 }
 654                                 out:
 655                                 if (cp > bp) {
 656                                         /*
 657                                          * Put n characters at once
 658                                          * into the tty output queue.
 659                                          */
 660                                         if (b_to_q((char *)bp, cp - bp,
 661                                             &tp->t_outq))
 662                                                 break;
 663                                         sc->sc_if.if_obytes += cp - bp;
 664                                 }
 665                                 /*
 666                                  * If there are characters left in the mbuf,
 667                                  * the first one must be special..
 668                                  * Put it out in a different form.
 669                                  */
 670                                 if (cp < ep) {
 671                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 672                                                 break;
 673                                         if (putc(*cp++ == FRAME_ESCAPE ?
 674                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 675                                            &tp->t_outq)) {
 676                                                 (void) unputc(&tp->t_outq);
 677                                                 break;
 678                                         }
 679                                         sc->sc_if.if_obytes += 2;
 680                                 }
 681                         }
 682                         m = m_free(m);
 683                 }
 684
 685                 if (putc(FRAME_END, &tp->t_outq)) {
 686                         /*
 687                          * Not enough room.  Remove a char to make room
 688                          * and end the packet normally.
 689                          * If you get many collisions (more than one or two
 690                          * a day) you probably do not have enough clists
 691                          * and you should increase "nclist" in param.c.
 692                          */
 693                         (void) unputc(&tp->t_outq);
 694                         (void) putc(FRAME_END, &tp->t_outq);
 695                         sc->sc_if.if_collisions++;
 696                 } else {
 697                         ++sc->sc_if.if_obytes;
 698                         sc->sc_if.if_opackets++;
 699                 }
 700         }
 701         return 0;
 702 }
 703
 704 /*
 705  * Copy data buffer to mbuf chain; add ifnet pointer.
 706  */
 707 static struct mbuf *
 708 sl_btom(sc, len)
 709         struct sl_softc *sc;
 710         int len;
 711 {
 712         struct mbuf *m;
 713
 714         if (len >= MCLBYTES)
 715                 return (NULL);
 716
 717         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 718         if (m == NULL)
 719                 return (NULL);
 720
 721         /*
 722          * If we have more than MHLEN bytes, it's cheaper to
 723          * queue the cluster we just filled & allocate a new one
 724          * for the input buffer.  Otherwise, fill the mbuf we
 725          * allocated above.  Note that code in the input routine
 726          * guarantees that packet will fit in a cluster.
 727          */
 728         if (len >= MHLEN) {
 729                 MCLGET(m, MB_DONTWAIT);
 730                 if ((m->m_flags & M_EXT) == 0) {
 731                         /*
 732                          * we couldn't get a cluster - if memory's this
 733                          * low, it's time to start dropping packets.
 734                          */
 735                         m_free(m);
 736                         return (NULL);
 737                 }
 738         }
 739         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 740         m->m_len = len;
 741         m->m_pkthdr.len = len;
 742         m->m_pkthdr.rcvif = &sc->sc_if;
 743         return (m);
 744 }
 745
 746 /*
 747  * tty interface receiver interrupt.
 748  */
 749 static int
 750 slinput(c, tp)
 751         int c;
 752         struct tty *tp;
 753 {
 754         struct sl_softc *sc;
 755         struct mbuf *m;
 756         int len;
 757         u_char chdr[CHDR_LEN];
 758
 759         tk_nin++;
 760         sc = (struct sl_softc *)tp->t_sc;
 761         if (sc == NULL)
 762                 return 0;
 763         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 764                 sc->sc_flags |= SC_ERROR;
 765                 return 0;
 766         }
 767         c &= TTY_CHARMASK;
 768
 769         ++sc->sc_if.if_ibytes;
 770
 771         if (sc->sc_if.if_flags & IFF_DEBUG) {
 772                 if (c == ABT_ESC) {
 773                         /*
 774                          * If we have a previous abort, see whether
 775                          * this one is within the time limit.
 776                          */
 777                         if (sc->sc_abortcount &&
 778                             time_second >= sc->sc_starttime + ABT_WINDOW)
 779                                 sc->sc_abortcount = 0;
 780                         /*
 781                          * If we see an abort after "idle" time, count it;
 782                          * record when the first abort escape arrived.
 783                          */
 784                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 785                                 if (++sc->sc_abortcount == 1)
 786                                         sc->sc_starttime = time_second;
 787                                 if (sc->sc_abortcount >= ABT_COUNT) {
 788                                         slclose(tp,0);
 789                                         return 0;
 790                                 }
 791                         }
 792                 } else
 793                         sc->sc_abortcount = 0;
 794                 sc->sc_lasttime = time_second;
 795         }
 796
 797         switch (c) {
 798
 799         case TRANS_FRAME_ESCAPE:
 800                 if (sc->sc_escape)
 801                         c = FRAME_ESCAPE;
 802                 break;
 803
 804         case TRANS_FRAME_END:
 805                 if (sc->sc_escape)
 806                         c = FRAME_END;
 807                 break;
 808
 809         case FRAME_ESCAPE:
 810                 sc->sc_escape = 1;
 811                 return 0;
 812
 813         case FRAME_END:
 814                 sc->sc_flags &= ~SC_KEEPALIVE;
 815                 if(sc->sc_flags & SC_ERROR) {
 816                         sc->sc_flags &= ~SC_ERROR;
 817                         goto newpack;
 818                 }
 819                 len = sc->sc_mp - sc->sc_buf;
 820                 if (len < 3)
 821                         /* less than min length packet - ignore */
 822                         goto newpack;
 823
 824                 if (sc->sc_if.if_bpf) {
 825                         /*
 826                          * Save the compressed header, so we
 827                          * can tack it on later.  Note that we
 828                          * will end up copying garbage in some
 829                          * cases but this is okay.  We remember
 830                          * where the buffer started so we can
 831                          * compute the new header length.
 832                          */
 833                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 834                 }
 835
 836                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 837                         if (c & 0x80)
 838                                 c = TYPE_COMPRESSED_TCP;
 839                         else if (c == TYPE_UNCOMPRESSED_TCP)
 840                                 *sc->sc_buf &= 0x4f; /* XXX */
 841                         /*
 842                          * We've got something that's not an IP packet.
 843                          * If compression is enabled, try to decompress it.
 844                          * Otherwise, if `auto-enable' compression is on and
 845                          * it's a reasonable packet, decompress it and then
 846                          * enable compression.  Otherwise, drop it.
 847                          */
 848                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 849                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 850                                                         (u_int)c, &sc->sc_comp);
 851                                 if (len <= 0)
 852                                         goto error;
 853                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 854                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 855                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 856                                                         (u_int)c, &sc->sc_comp);
 857                                 if (len <= 0)
 858                                         goto error;
 859                                 sc->sc_if.if_flags |= SC_COMPRESS;
 860                         } else
 861                                 goto error;
 862                 }
 863                 if (sc->sc_if.if_bpf) {
 864                         /*
 865                          * Put the SLIP pseudo-"link header" in place.
 866                          * We couldn't do this any earlier since
 867                          * decompression probably moved the buffer
 868                          * pointer.  Then, invoke BPF.
 869                          */
 870                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 871
 872                         hp[SLX_DIR] = SLIPDIR_IN;
 873                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 874                         bpf_tap(sc->sc_if.if_bpf, hp, len + SLIP_HDRLEN);
 875                 }
 876                 m = sl_btom(sc, len);
 877                 if (m == NULL)
 878                         goto error;
 879
 880                 sc->sc_if.if_ipackets++;
 881
 882                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 883                         m_freem(m);
 884                         goto newpack;
 885                 }
 886
 887                 if (netisr_queue(NETISR_IP, m)) {
 888                         sc->sc_if.if_ierrors++;
 889                         sc->sc_if.if_iqdrops++;
 890                 }
 891
 892                 goto newpack;
 893         }
 894         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 895                 *sc->sc_mp++ = c;
 896                 sc->sc_escape = 0;
 897                 return 0;
 898         }
 899
 900         /* can't put lower; would miss an extra frame */
 901         sc->sc_flags |= SC_ERROR;
 902
 903 error:
 904         sc->sc_if.if_ierrors++;
 905 newpack:
 906         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 907         sc->sc_escape = 0;
 908         return 0;
 909 }
 910
 911 /*
 912  * Process an ioctl request.
 913  */
 914 static int
 915 slioctl(ifp, cmd, data, cr)
 916         struct ifnet *ifp;
 917         u_long cmd;
 918         caddr_t data;
 919         struct ucred *cr;
 920 {
 921         struct ifaddr *ifa = (struct ifaddr *)data;
 922         struct ifreq *ifr = (struct ifreq *)data;
 923         int error = 0;
 924
 925         crit_enter();
 926
 927         switch (cmd) {
 928
 929         case SIOCSIFFLAGS:
 930                 /*
 931                  * if.c will set the interface up even if we
 932                  * don't want it to.
 933                  */
 934                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 935                         ifp->if_flags &= ~IFF_UP;
 936                 }
 937                 break;
 938         case SIOCSIFADDR:
 939                 /*
 940                  * This is "historical" - set the interface up when
 941                  * setting the address.
 942                  */
 943                 if (ifa->ifa_addr->sa_family == AF_INET) {
 944                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 945                                 ifp->if_flags |= IFF_UP;
 946                 } else {
 947                         error = EAFNOSUPPORT;
 948                 }
 949                 break;
 950
 951         case SIOCSIFDSTADDR:
 952                 if (ifa->ifa_addr->sa_family != AF_INET)
 953                         error = EAFNOSUPPORT;
 954                 break;
 955
 956         case SIOCADDMULTI:
 957         case SIOCDELMULTI:
 958                 break;
 959
 960         case SIOCSIFMTU:
 961                 /*
 962                  * Set the interface MTU.
 963                  */
 964                 if (ifr->ifr_mtu > SLTMAX)
 965                         error = EINVAL;
 966                 else {
 967                         struct tty *tp;
 968
 969                         ifp->if_mtu = ifr->ifr_mtu;
 970                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 971                         if (tp != NULL)
 972                                 clist_alloc_cblocks(&tp->t_outq,
 973                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 974                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 975                 }
 976                 break;
 977
 978         default:
 979                 error = EINVAL;
 980         }
 981
 982         crit_exit();
 983         return (error);
 984 }
 985
 986 static void
 987 sl_keepalive(chan)
 988         void *chan;
 989 {
 990         struct sl_softc *sc = chan;
 991
 992         if (sc->sc_keepalive) {
 993                 if (sc->sc_flags & SC_KEEPALIVE)
 994                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 995                 else
 996                         sc->sc_flags |= SC_KEEPALIVE;
 997                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 998                                 sl_keepalive, sc);
 999         } else {
1000                 sc->sc_flags &= ~SC_KEEPALIVE;
1001         }
1002 }
1003
1004 static void
1005 sl_outfill(chan)
1006         void *chan;
1007 {
1008         struct sl_softc *sc = chan;
1009         struct tty *tp = sc->sc_ttyp;
1010
1011         if (sc->sc_outfill && tp != NULL) {
1012                 if (sc->sc_flags & SC_OUTWAIT) {
1013                         crit_enter();
1014                         ++sc->sc_if.if_obytes;
1015                         (void) putc(FRAME_END, &tp->t_outq);
1016                         (*tp->t_oproc)(tp);
1017                         crit_exit();
1018                 } else
1019                         sc->sc_flags |= SC_OUTWAIT;
1020                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1021                                 sl_outfill, sc);
1022         } else {
1023                 sc->sc_flags &= ~SC_OUTWAIT;
1024         }
1025 }