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 1.17 2005/02/11 22:25:57 joerg 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/ifq_var.h>
  93 #include <net/netisr.h>
  94
  95 #if INET
  96 #include <netinet/in.h>
  97 #include <netinet/in_systm.h>
  98 #include <netinet/in_var.h>
  99 #include <netinet/ip.h>
 100 #else
 101 #error "Huh? Slip without inet?"
 102 #endif
 103
 104 #include <net/slcompress.h>
 105 #include "if_slvar.h"
 106 #include <net/slip.h>
 107
 108 #include <net/bpf.h>
 109
 110 #ifdef __i386__
 111 #include <i386/isa/intr_machdep.h>
 112 #endif
 113
 114 static void slattach (void *);
 115 PSEUDO_SET(slattach, if_sl);
 116
 117 /*
 118  * SLRMAX is a hard limit on input packet size.  To simplify the code
 119  * and improve performance, we require that packets fit in an mbuf
 120  * cluster, and if we get a compressed packet, there's enough extra
 121  * room to expand the header into a max length tcp/ip header (128
 122  * bytes).  So, SLRMAX can be at most
 123  *      MCLBYTES - 128
 124  *
 125  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 126  * small enough so that interactive use doesn't suffer, but large
 127  * enough to provide good performance. 552 is a good choice for SLMTU
 128  * because it is high enough to not fragment TCP packets being routed
 129  * through this host. Packet fragmentation is bad with SLIP because
 130  * fragment headers aren't compressed. The previous assumptions about
 131  * the best MTU value don't really hold when using modern modems with
 132  * BTLZ data compression because the modem buffers play a much larger
 133  * role in interactive performance than the MTU. The MTU can be changed
 134  * at any time to suit the specific environment with ifconfig(8), and
 135  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 136  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 137  * handles this better).
 138  *
 139  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 140  * of us (i.e., in clists waiting to be picked up by the tty output
 141  * interrupt).  If we queue a lot of data downstream, it's immune to
 142  * our t.o.s. queuing.
 143  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 144  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 145  * wait is dependent on the ftp window size but that's typically
 146  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 147  * the cost (in idle time on the wire) of the tty driver running
 148  * off the end of its clists & having to call back slstart for a
 149  * new packet.  For a tty interface with any buffering at all, this
 150  * cost will be zero.  Even with a totally brain dead interface (like
 151  * the one on a typical workstation), the cost will be <= 1 character
 152  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 153  * at most 1% while maintaining good interactive response.
 154  */
 155 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 156 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 157 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 158 #ifndef SLMTU
 159 #define SLMTU           552             /* default MTU */
 160 #endif
 161 #define SLTMAX          1500            /* maximum MTU */
 162 #define SLIP_HIWAT      roundup(50,CBSIZE)
 163 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 164
 165 /*
 166  * SLIP ABORT ESCAPE MECHANISM:
 167  *      (inspired by HAYES modem escape arrangement)
 168  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 169  *      within window time signals a "soft" exit from slip mode by remote end
 170  *      if the IFF_DEBUG flag is on.
 171  */
 172 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 173 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 174 #define ABT_COUNT       3       /* count of escapes for abort */
 175 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 176
 177 static struct sl_softc sl_softc[NSL];
 178
 179 #define FRAME_END               0xc0            /* Frame End */
 180 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 181 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 182 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 183
 184 static int slinit (struct sl_softc *);
 185 static struct mbuf *sl_btom (struct sl_softc *, int);
 186 static timeout_t sl_keepalive;
 187 static timeout_t sl_outfill;
 188 static int      slclose (struct tty *,int);
 189 static int      slinput (int, struct tty *);
 190 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 191 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct thread *);
 192 static int      slopen (dev_t, struct tty *);
 193 static int      sloutput (struct ifnet *,
 194             struct mbuf *, struct sockaddr *, struct rtentry *);
 195 static int      slstart (struct tty *);
 196
 197 static struct linesw slipdisc = {
 198         slopen,         slclose,        l_noread,       l_nowrite,
 199         sltioctl,       slinput,        slstart,        ttymodem,
 200         FRAME_END
 201 };
 202
 203 /*
 204  * Called from boot code to establish sl interfaces.
 205  */
 206 static void
 207 slattach(dummy)
 208         void *dummy;
 209 {
 210         struct sl_softc *sc;
 211         int i = 0;
 212
 213         linesw[SLIPDISC] = slipdisc;
 214
 215         for (sc = sl_softc; i < NSL; sc++) {
 216                 if_initname(&(sc->sc_if), "sl", i++);
 217                 sc->sc_if.if_mtu = SLMTU;
 218                 sc->sc_if.if_flags =
 219 #ifdef SLIP_IFF_OPTS
 220                     SLIP_IFF_OPTS;
 221 #else
 222                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 223 #endif
 224                 sc->sc_if.if_type = IFT_SLIP;
 225                 sc->sc_if.if_ioctl = slioctl;
 226                 sc->sc_if.if_output = sloutput;
 227                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 228                 ifq_set_ready(&sc->sc_if.if_snd);
 229                 sc->sc_fastq.ifq_maxlen = 32;
 230                 sc->sc_if.if_linkmib = sc;
 231                 sc->sc_if.if_linkmiblen = sizeof *sc;
 232                 callout_init(&sc->sc_oftimeout);
 233                 callout_init(&sc->sc_katimeout);
 234                 if_attach(&sc->sc_if);
 235                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 236         }
 237 }
 238
 239 static int
 240 slinit(sc)
 241         struct sl_softc *sc;
 242 {
 243 #ifdef __i386__
 244         int s;
 245
 246         s = splhigh();
 247         tty_imask |= net_imask;
 248         net_imask = tty_imask;
 249         update_intr_masks();
 250         splx(s);
 251         if (bootverbose)
 252                 printf("new imasks: bio %x, tty %x, net %x\n",
 253                     bio_imask, tty_imask, net_imask);
 254 #endif
 255         if (sc->sc_ep == NULL)
 256                 sc->sc_ep = malloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 257         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 258         sc->sc_mp = sc->sc_buf;
 259         sl_compress_init(&sc->sc_comp, -1);
 260         return (1);
 261 }
 262
 263 /*
 264  * Line specific open routine.
 265  * Attach the given tty to the first available sl unit.
 266  */
 267 /* ARGSUSED */
 268 static int
 269 slopen(dev_t dev, struct tty *tp)
 270 {
 271         struct sl_softc *sc;
 272         int nsl;
 273         int s, error;
 274         struct thread *td = curthread;  /* XXX */
 275
 276         error = suser(td);
 277         if (error)
 278                 return (error);
 279
 280         if (tp->t_line == SLIPDISC)
 281                 return (0);
 282
 283         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 284                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 285                         if (slinit(sc) == 0)
 286                                 return (ENOBUFS);
 287                         tp->t_sc = (caddr_t)sc;
 288                         sc->sc_ttyp = tp;
 289                         sc->sc_if.if_baudrate = tp->t_ospeed;
 290                         ttyflush(tp, FREAD | FWRITE);
 291
 292                         tp->t_line = SLIPDISC;
 293                         /*
 294                          * We don't use t_canq or t_rawq, so reduce their
 295                          * cblock resources to 0.  Reserve enough cblocks
 296                          * for t_outq to guarantee that we can fit a full
 297                          * packet if the SLIP_HIWAT check allows slstart()
 298                          * to loop.  Use the same value for the cblock
 299                          * limit since the reserved blocks should always
 300                          * be enough.  Reserving cblocks probably makes
 301                          * the CLISTRESERVE check unnecessary and wasteful.
 302                          */
 303                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 304                         clist_alloc_cblocks(&tp->t_outq,
 305                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 306                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 307                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 308
 309                         s = splnet();
 310                         if_up(&sc->sc_if);
 311                         splx(s);
 312                         return (0);
 313                 }
 314         return (ENXIO);
 315 }
 316
 317 /*
 318  * Line specific close routine.
 319  * Detach the tty from the sl unit.
 320  */
 321 static int
 322 slclose(tp,flag)
 323         struct tty *tp;
 324         int flag;
 325 {
 326         struct sl_softc *sc;
 327         int s;
 328
 329         ttyflush(tp, FREAD | FWRITE);
 330         /*
 331          * XXX the placement of the following spl is misleading.  tty
 332          * interrupts must be blocked across line discipline switches
 333          * and throughout closes to avoid races.
 334          */
 335         s = splimp();           /* actually, max(spltty, splnet) */
 336         clist_free_cblocks(&tp->t_outq);
 337         tp->t_line = 0;
 338         sc = (struct sl_softc *)tp->t_sc;
 339         if (sc != NULL) {
 340                 if (sc->sc_outfill) {
 341                         sc->sc_outfill = 0;
 342                         callout_stop(&sc->sc_oftimeout);
 343                 }
 344                 if (sc->sc_keepalive) {
 345                         sc->sc_keepalive = 0;
 346                         callout_stop(&sc->sc_katimeout);
 347                 }
 348                 if_down(&sc->sc_if);
 349                 sc->sc_flags &= SC_STATIC;
 350                 sc->sc_ttyp = NULL;
 351                 tp->t_sc = NULL;
 352                 if (sc->sc_ep) {
 353                         free(sc->sc_ep, M_DEVBUF);
 354                         sc->sc_ep = NULL;
 355                 }
 356                 sc->sc_mp = 0;
 357                 sc->sc_buf = 0;
 358         }
 359         splx(s);
 360         return 0;
 361 }
 362
 363 /*
 364  * Line specific (tty) ioctl routine.
 365  * Provide a way to get the sl unit number.
 366  */
 367 /* ARGSUSED */
 368 static int
 369 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 370 {
 371         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 372         int s, nsl;
 373
 374         s = splimp();
 375         switch (cmd) {
 376         case SLIOCGUNIT:
 377                 *(int *)data = sc->sc_if.if_dunit;
 378                 break;
 379
 380         case SLIOCSUNIT:
 381                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 382                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 383                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 384                                     && nc->sc_ttyp == NULL
 385                                    ) {
 386                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 387                                                        M_WAITOK);
 388                                         *tmpnc = *nc;
 389                                         *nc = *sc;
 390                                         nc->sc_if = tmpnc->sc_if;
 391                                         tmpnc->sc_if = sc->sc_if;
 392                                         *sc = *tmpnc;
 393                                         free(tmpnc, M_TEMP);
 394                                         if (sc->sc_if.if_flags & IFF_UP) {
 395                                                 if_down(&sc->sc_if);
 396                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 397                                                         if_up(&nc->sc_if);
 398                                         } else if (nc->sc_if.if_flags & IFF_UP)
 399                                                 if_down(&nc->sc_if);
 400                                         sc->sc_flags &= ~SC_STATIC;
 401                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 402                                         tp->t_sc = sc = nc;
 403                                         clist_alloc_cblocks(&tp->t_outq,
 404                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 405                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 406                                         sl_compress_init(&sc->sc_comp, -1);
 407                                         goto slfound;
 408                                 }
 409                         }
 410                         splx(s);
 411                         return (ENXIO);
 412                 }
 413         slfound:
 414                 sc->sc_flags |= SC_STATIC;
 415                 break;
 416
 417         case SLIOCSKEEPAL:
 418                 sc->sc_keepalive = *(u_int *)data * hz;
 419                 if (sc->sc_keepalive) {
 420                         sc->sc_flags |= SC_KEEPALIVE;
 421                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 422                                         sl_keepalive, sc);
 423                 } else {
 424                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 425                                 callout_stop(&sc->sc_katimeout);
 426                                 sc->sc_flags &= ~SC_KEEPALIVE;
 427                         }
 428                 }
 429                 break;
 430
 431         case SLIOCGKEEPAL:
 432                 *(int *)data = sc->sc_keepalive / hz;
 433                 break;
 434
 435         case SLIOCSOUTFILL:
 436                 sc->sc_outfill = *(u_int *)data * hz;
 437                 if (sc->sc_outfill) {
 438                         sc->sc_flags |= SC_OUTWAIT;
 439                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 440                                         sl_outfill, sc);
 441                 } else {
 442                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 443                                 callout_stop(&sc->sc_oftimeout);
 444                                 sc->sc_flags &= ~SC_OUTWAIT;
 445                         }
 446                 }
 447                 break;
 448
 449         case SLIOCGOUTFILL:
 450                 *(int *)data = sc->sc_outfill / hz;
 451                 break;
 452
 453         default:
 454                 splx(s);
 455                 return (ENOIOCTL);
 456         }
 457         splx(s);
 458         return (0);
 459 }
 460
 461 /*
 462  * Queue a packet.  Start transmission if not active.
 463  * Compression happens in slstart; if we do it here, IP TOS
 464  * will cause us to not compress "background" packets, because
 465  * ordering gets trashed.  It can be done for all packets in slstart.
 466  */
 467 static int
 468 sloutput(ifp, m, dst, rtp)
 469         struct ifnet *ifp;
 470         struct mbuf *m;
 471         struct sockaddr *dst;
 472         struct rtentry *rtp;
 473 {
 474         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 475         struct ip *ip;
 476         int error, s;
 477         struct altq_pktattr pktattr;
 478
 479         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 480
 481         /*
 482          * `Cannot happen' (see slioctl).  Someday we will extend
 483          * the line protocol to support other address families.
 484          */
 485         if (dst->sa_family != AF_INET) {
 486                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 487                         dst->sa_family);
 488                 m_freem(m);
 489                 sc->sc_if.if_noproto++;
 490                 return (EAFNOSUPPORT);
 491         }
 492
 493         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 494                 m_freem(m);
 495                 return (ENETDOWN);
 496         }
 497         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 498                 m_freem(m);
 499                 return (EHOSTUNREACH);
 500         }
 501         ip = mtod(m, struct ip *);
 502         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 503                 m_freem(m);
 504                 return (ENETRESET);             /* XXX ? */
 505         }
 506         s = splimp();
 507         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 508                 if (IF_QFULL(&sc->sc_fastq)) {
 509                         IF_DROP(&sc->sc_fastq);
 510                         m_freem(m);
 511                         error = ENOBUFS;
 512                 } else {
 513                         IF_ENQUEUE(&sc->sc_fastq, m);
 514                         error = 0;
 515                 }
 516         } else {
 517                 error = ifq_enqueue(&sc->sc_if.if_snd, m, &pktattr);
 518         }
 519         if (error) {
 520                 sc->sc_if.if_oerrors++;
 521                 splx(s);
 522                 return (error);
 523         }
 524         if (sc->sc_ttyp->t_outq.c_cc == 0)
 525                 slstart(sc->sc_ttyp);
 526         splx(s);
 527         return (0);
 528 }
 529
 530 /*
 531  * Start output on interface.  Get another datagram
 532  * to send from the interface queue and map it to
 533  * the interface before starting output.
 534  */
 535 static int
 536 slstart(tp)
 537         struct tty *tp;
 538 {
 539         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 540         struct mbuf *m;
 541         u_char *cp;
 542         struct ip *ip;
 543         int s;
 544         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 545         int len = 0;
 546
 547         for (;;) {
 548                 /*
 549                  * Call output process whether or not there is more in the
 550                  * output queue.  We are being called in lieu of ttstart
 551                  * and must do what it would.
 552                  */
 553                 (*tp->t_oproc)(tp);
 554
 555                 if (tp->t_outq.c_cc != 0) {
 556                         if (sc != NULL)
 557                                 sc->sc_flags &= ~SC_OUTWAIT;
 558                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 559                                 return 0;
 560                 }
 561
 562                 /*
 563                  * This happens briefly when the line shuts down.
 564                  */
 565                 if (sc == NULL)
 566                         return 0;
 567
 568                 /*
 569                  * Get a packet and send it to the interface.
 570                  */
 571                 s = splimp();
 572                 IF_DEQUEUE(&sc->sc_fastq, m);
 573                 if (m)
 574                         sc->sc_if.if_omcasts++;         /* XXX */
 575                 else
 576                         m = ifq_dequeue(&sc->sc_if.if_snd);
 577                 splx(s);
 578                 if (m == NULL)
 579                         return 0;
 580
 581                 /*
 582                  * We do the header compression here rather than in sloutput
 583                  * because the packets will be out of order if we are using TOS
 584                  * queueing, and the connection id compression will get
 585                  * munged when this happens.
 586                  */
 587                 if (sc->sc_if.if_bpf) {
 588                         /*
 589                          * We need to save the TCP/IP header before it's
 590                          * compressed.  To avoid complicated code, we just
 591                          * copy the entire packet into a stack buffer (since
 592                          * this is a serial line, packets should be short
 593                          * and/or the copy should be negligible cost compared
 594                          * to the packet transmission time).
 595                          */
 596                         struct mbuf *m1 = m;
 597                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 598
 599                         len = 0;
 600                         do {
 601                                 int mlen = m1->m_len;
 602
 603                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 604                                 cp += mlen;
 605                                 len += mlen;
 606                         } while ((m1 = m1->m_next) != NULL);
 607                 }
 608                 ip = mtod(m, struct ip *);
 609                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 610                         if (sc->sc_if.if_flags & SC_COMPRESS)
 611                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 612                                     &sc->sc_comp, 1);
 613                 }
 614                 if (sc->sc_if.if_bpf) {
 615                         /*
 616                          * Put the SLIP pseudo-"link header" in place.  The
 617                          * compressed header is now at the beginning of the
 618                          * mbuf.
 619                          */
 620                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 621                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 622                         bpf_tap(sc->sc_if.if_bpf, bpfbuf, len + SLIP_HDRLEN);
 623                 }
 624
 625                 /*
 626                  * If system is getting low on clists, just flush our
 627                  * output queue (if the stuff was important, it'll get
 628                  * retransmitted). Note that SLTMAX is used instead of
 629                  * the current if_mtu setting because connections that
 630                  * have already been established still use the original
 631                  * (possibly larger) mss.
 632                  */
 633                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 634                         m_freem(m);
 635                         sc->sc_if.if_collisions++;
 636                         continue;
 637                 }
 638
 639                 sc->sc_flags &= ~SC_OUTWAIT;
 640                 /*
 641                  * The extra FRAME_END will start up a new packet, and thus
 642                  * will flush any accumulated garbage.  We do this whenever
 643                  * the line may have been idle for some time.
 644                  */
 645                 if (tp->t_outq.c_cc == 0) {
 646                         ++sc->sc_if.if_obytes;
 647                         (void) putc(FRAME_END, &tp->t_outq);
 648                 }
 649
 650                 while (m) {
 651                         u_char *ep;
 652
 653                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 654                         while (cp < ep) {
 655                                 /*
 656                                  * Find out how many bytes in the string we can
 657                                  * handle without doing something special.
 658                                  */
 659                                 u_char *bp = cp;
 660
 661                                 while (cp < ep) {
 662                                         switch (*cp++) {
 663                                         case FRAME_ESCAPE:
 664                                         case FRAME_END:
 665                                                 --cp;
 666                                                 goto out;
 667                                         }
 668                                 }
 669                                 out:
 670                                 if (cp > bp) {
 671                                         /*
 672                                          * Put n characters at once
 673                                          * into the tty output queue.
 674                                          */
 675                                         if (b_to_q((char *)bp, cp - bp,
 676                                             &tp->t_outq))
 677                                                 break;
 678                                         sc->sc_if.if_obytes += cp - bp;
 679                                 }
 680                                 /*
 681                                  * If there are characters left in the mbuf,
 682                                  * the first one must be special..
 683                                  * Put it out in a different form.
 684                                  */
 685                                 if (cp < ep) {
 686                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 687                                                 break;
 688                                         if (putc(*cp++ == FRAME_ESCAPE ?
 689                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 690                                            &tp->t_outq)) {
 691                                                 (void) unputc(&tp->t_outq);
 692                                                 break;
 693                                         }
 694                                         sc->sc_if.if_obytes += 2;
 695                                 }
 696                         }
 697                         m = m_free(m);
 698                 }
 699
 700                 if (putc(FRAME_END, &tp->t_outq)) {
 701                         /*
 702                          * Not enough room.  Remove a char to make room
 703                          * and end the packet normally.
 704                          * If you get many collisions (more than one or two
 705                          * a day) you probably do not have enough clists
 706                          * and you should increase "nclist" in param.c.
 707                          */
 708                         (void) unputc(&tp->t_outq);
 709                         (void) putc(FRAME_END, &tp->t_outq);
 710                         sc->sc_if.if_collisions++;
 711                 } else {
 712                         ++sc->sc_if.if_obytes;
 713                         sc->sc_if.if_opackets++;
 714                 }
 715         }
 716         return 0;
 717 }
 718
 719 /*
 720  * Copy data buffer to mbuf chain; add ifnet pointer.
 721  */
 722 static struct mbuf *
 723 sl_btom(sc, len)
 724         struct sl_softc *sc;
 725         int len;
 726 {
 727         struct mbuf *m;
 728
 729         if (len >= MCLBYTES)
 730                 return (NULL);
 731
 732         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 733         if (m == NULL)
 734                 return (NULL);
 735
 736         /*
 737          * If we have more than MHLEN bytes, it's cheaper to
 738          * queue the cluster we just filled & allocate a new one
 739          * for the input buffer.  Otherwise, fill the mbuf we
 740          * allocated above.  Note that code in the input routine
 741          * guarantees that packet will fit in a cluster.
 742          */
 743         if (len >= MHLEN) {
 744                 MCLGET(m, MB_DONTWAIT);
 745                 if ((m->m_flags & M_EXT) == 0) {
 746                         /*
 747                          * we couldn't get a cluster - if memory's this
 748                          * low, it's time to start dropping packets.
 749                          */
 750                         m_free(m);
 751                         return (NULL);
 752                 }
 753         }
 754         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 755         m->m_len = len;
 756         m->m_pkthdr.len = len;
 757         m->m_pkthdr.rcvif = &sc->sc_if;
 758         return (m);
 759 }
 760
 761 /*
 762  * tty interface receiver interrupt.
 763  */
 764 static int
 765 slinput(c, tp)
 766         int c;
 767         struct tty *tp;
 768 {
 769         struct sl_softc *sc;
 770         struct mbuf *m;
 771         int len;
 772         u_char chdr[CHDR_LEN];
 773
 774         tk_nin++;
 775         sc = (struct sl_softc *)tp->t_sc;
 776         if (sc == NULL)
 777                 return 0;
 778         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 779                 sc->sc_flags |= SC_ERROR;
 780                 return 0;
 781         }
 782         c &= TTY_CHARMASK;
 783
 784         ++sc->sc_if.if_ibytes;
 785
 786         if (sc->sc_if.if_flags & IFF_DEBUG) {
 787                 if (c == ABT_ESC) {
 788                         /*
 789                          * If we have a previous abort, see whether
 790                          * this one is within the time limit.
 791                          */
 792                         if (sc->sc_abortcount &&
 793                             time_second >= sc->sc_starttime + ABT_WINDOW)
 794                                 sc->sc_abortcount = 0;
 795                         /*
 796                          * If we see an abort after "idle" time, count it;
 797                          * record when the first abort escape arrived.
 798                          */
 799                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 800                                 if (++sc->sc_abortcount == 1)
 801                                         sc->sc_starttime = time_second;
 802                                 if (sc->sc_abortcount >= ABT_COUNT) {
 803                                         slclose(tp,0);
 804                                         return 0;
 805                                 }
 806                         }
 807                 } else
 808                         sc->sc_abortcount = 0;
 809                 sc->sc_lasttime = time_second;
 810         }
 811
 812         switch (c) {
 813
 814         case TRANS_FRAME_ESCAPE:
 815                 if (sc->sc_escape)
 816                         c = FRAME_ESCAPE;
 817                 break;
 818
 819         case TRANS_FRAME_END:
 820                 if (sc->sc_escape)
 821                         c = FRAME_END;
 822                 break;
 823
 824         case FRAME_ESCAPE:
 825                 sc->sc_escape = 1;
 826                 return 0;
 827
 828         case FRAME_END:
 829                 sc->sc_flags &= ~SC_KEEPALIVE;
 830                 if(sc->sc_flags & SC_ERROR) {
 831                         sc->sc_flags &= ~SC_ERROR;
 832                         goto newpack;
 833                 }
 834                 len = sc->sc_mp - sc->sc_buf;
 835                 if (len < 3)
 836                         /* less than min length packet - ignore */
 837                         goto newpack;
 838
 839                 if (sc->sc_if.if_bpf) {
 840                         /*
 841                          * Save the compressed header, so we
 842                          * can tack it on later.  Note that we
 843                          * will end up copying garbage in some
 844                          * cases but this is okay.  We remember
 845                          * where the buffer started so we can
 846                          * compute the new header length.
 847                          */
 848                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 849                 }
 850
 851                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 852                         if (c & 0x80)
 853                                 c = TYPE_COMPRESSED_TCP;
 854                         else if (c == TYPE_UNCOMPRESSED_TCP)
 855                                 *sc->sc_buf &= 0x4f; /* XXX */
 856                         /*
 857                          * We've got something that's not an IP packet.
 858                          * If compression is enabled, try to decompress it.
 859                          * Otherwise, if `auto-enable' compression is on and
 860                          * it's a reasonable packet, decompress it and then
 861                          * enable compression.  Otherwise, drop it.
 862                          */
 863                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 864                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 865                                                         (u_int)c, &sc->sc_comp);
 866                                 if (len <= 0)
 867                                         goto error;
 868                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 869                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 870                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 871                                                         (u_int)c, &sc->sc_comp);
 872                                 if (len <= 0)
 873                                         goto error;
 874                                 sc->sc_if.if_flags |= SC_COMPRESS;
 875                         } else
 876                                 goto error;
 877                 }
 878                 if (sc->sc_if.if_bpf) {
 879                         /*
 880                          * Put the SLIP pseudo-"link header" in place.
 881                          * We couldn't do this any earlier since
 882                          * decompression probably moved the buffer
 883                          * pointer.  Then, invoke BPF.
 884                          */
 885                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 886
 887                         hp[SLX_DIR] = SLIPDIR_IN;
 888                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 889                         bpf_tap(sc->sc_if.if_bpf, hp, len + SLIP_HDRLEN);
 890                 }
 891                 m = sl_btom(sc, len);
 892                 if (m == NULL)
 893                         goto error;
 894
 895                 sc->sc_if.if_ipackets++;
 896
 897                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 898                         m_freem(m);
 899                         goto newpack;
 900                 }
 901
 902                 if (netisr_queue(NETISR_IP, m)) {
 903                         sc->sc_if.if_ierrors++;
 904                         sc->sc_if.if_iqdrops++;
 905                 }
 906
 907                 goto newpack;
 908         }
 909         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 910                 *sc->sc_mp++ = c;
 911                 sc->sc_escape = 0;
 912                 return 0;
 913         }
 914
 915         /* can't put lower; would miss an extra frame */
 916         sc->sc_flags |= SC_ERROR;
 917
 918 error:
 919         sc->sc_if.if_ierrors++;
 920 newpack:
 921         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 922         sc->sc_escape = 0;
 923         return 0;
 924 }
 925
 926 /*
 927  * Process an ioctl request.
 928  */
 929 static int
 930 slioctl(ifp, cmd, data, cr)
 931         struct ifnet *ifp;
 932         u_long cmd;
 933         caddr_t data;
 934         struct ucred *cr;
 935 {
 936         struct ifaddr *ifa = (struct ifaddr *)data;
 937         struct ifreq *ifr = (struct ifreq *)data;
 938         int s, error = 0;
 939
 940         s = splimp();
 941
 942         switch (cmd) {
 943
 944         case SIOCSIFFLAGS:
 945                 /*
 946                  * if.c will set the interface up even if we
 947                  * don't want it to.
 948                  */
 949                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 950                         ifp->if_flags &= ~IFF_UP;
 951                 }
 952                 break;
 953         case SIOCSIFADDR:
 954                 /*
 955                  * This is "historical" - set the interface up when
 956                  * setting the address.
 957                  */
 958                 if (ifa->ifa_addr->sa_family == AF_INET) {
 959                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 960                                 ifp->if_flags |= IFF_UP;
 961                 } else {
 962                         error = EAFNOSUPPORT;
 963                 }
 964                 break;
 965
 966         case SIOCSIFDSTADDR:
 967                 if (ifa->ifa_addr->sa_family != AF_INET)
 968                         error = EAFNOSUPPORT;
 969                 break;
 970
 971         case SIOCADDMULTI:
 972         case SIOCDELMULTI:
 973                 break;
 974
 975         case SIOCSIFMTU:
 976                 /*
 977                  * Set the interface MTU.
 978                  */
 979                 if (ifr->ifr_mtu > SLTMAX)
 980                         error = EINVAL;
 981                 else {
 982                         struct tty *tp;
 983
 984                         ifp->if_mtu = ifr->ifr_mtu;
 985                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 986                         if (tp != NULL)
 987                                 clist_alloc_cblocks(&tp->t_outq,
 988                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 989                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 990                 }
 991                 break;
 992
 993         default:
 994                 error = EINVAL;
 995         }
 996         splx(s);
 997         return (error);
 998 }
 999
1000 static void
1001 sl_keepalive(chan)
1002         void *chan;
1003 {
1004         struct sl_softc *sc = chan;
1005
1006         if (sc->sc_keepalive) {
1007                 if (sc->sc_flags & SC_KEEPALIVE)
1008                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
1009                 else
1010                         sc->sc_flags |= SC_KEEPALIVE;
1011                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
1012                                 sl_keepalive, sc);
1013         } else {
1014                 sc->sc_flags &= ~SC_KEEPALIVE;
1015         }
1016 }
1017
1018 static void
1019 sl_outfill(chan)
1020         void *chan;
1021 {
1022         struct sl_softc *sc = chan;
1023         struct tty *tp = sc->sc_ttyp;
1024         int s;
1025
1026         if (sc->sc_outfill && tp != NULL) {
1027                 if (sc->sc_flags & SC_OUTWAIT) {
1028                         s = splimp ();
1029                         ++sc->sc_if.if_obytes;
1030                         (void) putc(FRAME_END, &tp->t_outq);
1031                         (*tp->t_oproc)(tp);
1032                         splx (s);
1033                 } else
1034                         sc->sc_flags |= SC_OUTWAIT;
1035                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1036                                 sl_outfill, sc);
1037         } else {
1038                 sc->sc_flags &= ~SC_OUTWAIT;
1039         }
1040 }