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 1.15 2004/09/16 04:49:32 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                 callout_init(&sc->sc_oftimeout);
 231                 callout_init(&sc->sc_katimeout);
 232                 if_attach(&sc->sc_if);
 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 #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 == NULL)
 254                 sc->sc_ep = malloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 255         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 256         sc->sc_mp = sc->sc_buf;
 257         sl_compress_init(&sc->sc_comp, -1);
 258         return (1);
 259 }
 260
 261 /*
 262  * Line specific open routine.
 263  * Attach the given tty to the first available sl unit.
 264  */
 265 /* ARGSUSED */
 266 static int
 267 slopen(dev_t dev, struct tty *tp)
 268 {
 269         struct sl_softc *sc;
 270         int nsl;
 271         int s, error;
 272         struct thread *td = curthread;  /* XXX */
 273
 274         error = suser(td);
 275         if (error)
 276                 return (error);
 277
 278         if (tp->t_line == SLIPDISC)
 279                 return (0);
 280
 281         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 282                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 283                         if (slinit(sc) == 0)
 284                                 return (ENOBUFS);
 285                         tp->t_sc = (caddr_t)sc;
 286                         sc->sc_ttyp = tp;
 287                         sc->sc_if.if_baudrate = tp->t_ospeed;
 288                         ttyflush(tp, FREAD | FWRITE);
 289
 290                         tp->t_line = SLIPDISC;
 291                         /*
 292                          * We don't use t_canq or t_rawq, so reduce their
 293                          * cblock resources to 0.  Reserve enough cblocks
 294                          * for t_outq to guarantee that we can fit a full
 295                          * packet if the SLIP_HIWAT check allows slstart()
 296                          * to loop.  Use the same value for the cblock
 297                          * limit since the reserved blocks should always
 298                          * be enough.  Reserving cblocks probably makes
 299                          * the CLISTRESERVE check unnecessary and wasteful.
 300                          */
 301                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 302                         clist_alloc_cblocks(&tp->t_outq,
 303                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 304                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 305                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 306
 307                         s = splnet();
 308                         if_up(&sc->sc_if);
 309                         splx(s);
 310                         return (0);
 311                 }
 312         return (ENXIO);
 313 }
 314
 315 /*
 316  * Line specific close routine.
 317  * Detach the tty from the sl unit.
 318  */
 319 static int
 320 slclose(tp,flag)
 321         struct tty *tp;
 322         int flag;
 323 {
 324         struct sl_softc *sc;
 325         int s;
 326
 327         ttyflush(tp, FREAD | FWRITE);
 328         /*
 329          * XXX the placement of the following spl is misleading.  tty
 330          * interrupts must be blocked across line discipline switches
 331          * and throughout closes to avoid races.
 332          */
 333         s = splimp();           /* actually, max(spltty, splnet) */
 334         clist_free_cblocks(&tp->t_outq);
 335         tp->t_line = 0;
 336         sc = (struct sl_softc *)tp->t_sc;
 337         if (sc != NULL) {
 338                 if (sc->sc_outfill) {
 339                         sc->sc_outfill = 0;
 340                         callout_stop(&sc->sc_oftimeout);
 341                 }
 342                 if (sc->sc_keepalive) {
 343                         sc->sc_keepalive = 0;
 344                         callout_stop(&sc->sc_katimeout);
 345                 }
 346                 if_down(&sc->sc_if);
 347                 sc->sc_flags &= SC_STATIC;
 348                 sc->sc_ttyp = NULL;
 349                 tp->t_sc = NULL;
 350                 if (sc->sc_ep) {
 351                         free(sc->sc_ep, M_DEVBUF);
 352                         sc->sc_ep = NULL;
 353                 }
 354                 sc->sc_mp = 0;
 355                 sc->sc_buf = 0;
 356         }
 357         splx(s);
 358         return 0;
 359 }
 360
 361 /*
 362  * Line specific (tty) ioctl routine.
 363  * Provide a way to get the sl unit number.
 364  */
 365 /* ARGSUSED */
 366 static int
 367 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 368 {
 369         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 370         int s, nsl;
 371
 372         s = splimp();
 373         switch (cmd) {
 374         case SLIOCGUNIT:
 375                 *(int *)data = sc->sc_if.if_dunit;
 376                 break;
 377
 378         case SLIOCSUNIT:
 379                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 380                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 381                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 382                                     && nc->sc_ttyp == NULL
 383                                    ) {
 384                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 385                                                        M_WAITOK);
 386                                         *tmpnc = *nc;
 387                                         *nc = *sc;
 388                                         nc->sc_if = tmpnc->sc_if;
 389                                         tmpnc->sc_if = sc->sc_if;
 390                                         *sc = *tmpnc;
 391                                         free(tmpnc, M_TEMP);
 392                                         if (sc->sc_if.if_flags & IFF_UP) {
 393                                                 if_down(&sc->sc_if);
 394                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 395                                                         if_up(&nc->sc_if);
 396                                         } else if (nc->sc_if.if_flags & IFF_UP)
 397                                                 if_down(&nc->sc_if);
 398                                         sc->sc_flags &= ~SC_STATIC;
 399                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 400                                         tp->t_sc = sc = nc;
 401                                         clist_alloc_cblocks(&tp->t_outq,
 402                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 403                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 404                                         sl_compress_init(&sc->sc_comp, -1);
 405                                         goto slfound;
 406                                 }
 407                         }
 408                         splx(s);
 409                         return (ENXIO);
 410                 }
 411         slfound:
 412                 sc->sc_flags |= SC_STATIC;
 413                 break;
 414
 415         case SLIOCSKEEPAL:
 416                 sc->sc_keepalive = *(u_int *)data * hz;
 417                 if (sc->sc_keepalive) {
 418                         sc->sc_flags |= SC_KEEPALIVE;
 419                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 420                                         sl_keepalive, sc);
 421                 } else {
 422                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 423                                 callout_stop(&sc->sc_katimeout);
 424                                 sc->sc_flags &= ~SC_KEEPALIVE;
 425                         }
 426                 }
 427                 break;
 428
 429         case SLIOCGKEEPAL:
 430                 *(int *)data = sc->sc_keepalive / hz;
 431                 break;
 432
 433         case SLIOCSOUTFILL:
 434                 sc->sc_outfill = *(u_int *)data * hz;
 435                 if (sc->sc_outfill) {
 436                         sc->sc_flags |= SC_OUTWAIT;
 437                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 438                                         sl_outfill, sc);
 439                 } else {
 440                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 441                                 callout_stop(&sc->sc_oftimeout);
 442                                 sc->sc_flags &= ~SC_OUTWAIT;
 443                         }
 444                 }
 445                 break;
 446
 447         case SLIOCGOUTFILL:
 448                 *(int *)data = sc->sc_outfill / hz;
 449                 break;
 450
 451         default:
 452                 splx(s);
 453                 return (ENOIOCTL);
 454         }
 455         splx(s);
 456         return (0);
 457 }
 458
 459 /*
 460  * Queue a packet.  Start transmission if not active.
 461  * Compression happens in slstart; if we do it here, IP TOS
 462  * will cause us to not compress "background" packets, because
 463  * ordering gets trashed.  It can be done for all packets in slstart.
 464  */
 465 static int
 466 sloutput(ifp, m, dst, rtp)
 467         struct ifnet *ifp;
 468         struct mbuf *m;
 469         struct sockaddr *dst;
 470         struct rtentry *rtp;
 471 {
 472         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 473         struct ip *ip;
 474         struct ifqueue *ifq;
 475         int s;
 476
 477         /*
 478          * `Cannot happen' (see slioctl).  Someday we will extend
 479          * the line protocol to support other address families.
 480          */
 481         if (dst->sa_family != AF_INET) {
 482                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 483                         dst->sa_family);
 484                 m_freem(m);
 485                 sc->sc_if.if_noproto++;
 486                 return (EAFNOSUPPORT);
 487         }
 488
 489         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 490                 m_freem(m);
 491                 return (ENETDOWN);
 492         }
 493         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 494                 m_freem(m);
 495                 return (EHOSTUNREACH);
 496         }
 497         ifq = &sc->sc_if.if_snd;
 498         ip = mtod(m, struct ip *);
 499         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 500                 m_freem(m);
 501                 return (ENETRESET);             /* XXX ? */
 502         }
 503         if (ip->ip_tos & IPTOS_LOWDELAY)
 504                 ifq = &sc->sc_fastq;
 505         s = splimp();
 506         if (IF_QFULL(ifq)) {
 507                 IF_DROP(ifq);
 508                 m_freem(m);
 509                 splx(s);
 510                 sc->sc_if.if_oerrors++;
 511                 return (ENOBUFS);
 512         }
 513         IF_ENQUEUE(ifq, m);
 514         if (sc->sc_ttyp->t_outq.c_cc == 0)
 515                 slstart(sc->sc_ttyp);
 516         splx(s);
 517         return (0);
 518 }
 519
 520 /*
 521  * Start output on interface.  Get another datagram
 522  * to send from the interface queue and map it to
 523  * the interface before starting output.
 524  */
 525 static int
 526 slstart(tp)
 527         struct tty *tp;
 528 {
 529         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 530         struct mbuf *m;
 531         u_char *cp;
 532         struct ip *ip;
 533         int s;
 534         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 535         int len = 0;
 536
 537         for (;;) {
 538                 /*
 539                  * Call output process whether or not there is more in the
 540                  * output queue.  We are being called in lieu of ttstart
 541                  * and must do what it would.
 542                  */
 543                 (*tp->t_oproc)(tp);
 544
 545                 if (tp->t_outq.c_cc != 0) {
 546                         if (sc != NULL)
 547                                 sc->sc_flags &= ~SC_OUTWAIT;
 548                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 549                                 return 0;
 550                 }
 551
 552                 /*
 553                  * This happens briefly when the line shuts down.
 554                  */
 555                 if (sc == NULL)
 556                         return 0;
 557
 558                 /*
 559                  * Get a packet and send it to the interface.
 560                  */
 561                 s = splimp();
 562                 IF_DEQUEUE(&sc->sc_fastq, m);
 563                 if (m)
 564                         sc->sc_if.if_omcasts++;         /* XXX */
 565                 else
 566                         IF_DEQUEUE(&sc->sc_if.if_snd, m);
 567                 splx(s);
 568                 if (m == NULL)
 569                         return 0;
 570
 571                 /*
 572                  * We do the header compression here rather than in sloutput
 573                  * because the packets will be out of order if we are using TOS
 574                  * queueing, and the connection id compression will get
 575                  * munged when this happens.
 576                  */
 577                 if (sc->sc_if.if_bpf) {
 578                         /*
 579                          * We need to save the TCP/IP header before it's
 580                          * compressed.  To avoid complicated code, we just
 581                          * copy the entire packet into a stack buffer (since
 582                          * this is a serial line, packets should be short
 583                          * and/or the copy should be negligible cost compared
 584                          * to the packet transmission time).
 585                          */
 586                         struct mbuf *m1 = m;
 587                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 588
 589                         len = 0;
 590                         do {
 591                                 int mlen = m1->m_len;
 592
 593                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 594                                 cp += mlen;
 595                                 len += mlen;
 596                         } while ((m1 = m1->m_next) != NULL);
 597                 }
 598                 ip = mtod(m, struct ip *);
 599                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 600                         if (sc->sc_if.if_flags & SC_COMPRESS)
 601                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 602                                     &sc->sc_comp, 1);
 603                 }
 604                 if (sc->sc_if.if_bpf) {
 605                         /*
 606                          * Put the SLIP pseudo-"link header" in place.  The
 607                          * compressed header is now at the beginning of the
 608                          * mbuf.
 609                          */
 610                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 611                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 612                         bpf_tap(&sc->sc_if, bpfbuf, len + SLIP_HDRLEN);
 613                 }
 614
 615                 /*
 616                  * If system is getting low on clists, just flush our
 617                  * output queue (if the stuff was important, it'll get
 618                  * retransmitted). Note that SLTMAX is used instead of
 619                  * the current if_mtu setting because connections that
 620                  * have already been established still use the original
 621                  * (possibly larger) mss.
 622                  */
 623                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 624                         m_freem(m);
 625                         sc->sc_if.if_collisions++;
 626                         continue;
 627                 }
 628
 629                 sc->sc_flags &= ~SC_OUTWAIT;
 630                 /*
 631                  * The extra FRAME_END will start up a new packet, and thus
 632                  * will flush any accumulated garbage.  We do this whenever
 633                  * the line may have been idle for some time.
 634                  */
 635                 if (tp->t_outq.c_cc == 0) {
 636                         ++sc->sc_if.if_obytes;
 637                         (void) putc(FRAME_END, &tp->t_outq);
 638                 }
 639
 640                 while (m) {
 641                         u_char *ep;
 642
 643                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 644                         while (cp < ep) {
 645                                 /*
 646                                  * Find out how many bytes in the string we can
 647                                  * handle without doing something special.
 648                                  */
 649                                 u_char *bp = cp;
 650
 651                                 while (cp < ep) {
 652                                         switch (*cp++) {
 653                                         case FRAME_ESCAPE:
 654                                         case FRAME_END:
 655                                                 --cp;
 656                                                 goto out;
 657                                         }
 658                                 }
 659                                 out:
 660                                 if (cp > bp) {
 661                                         /*
 662                                          * Put n characters at once
 663                                          * into the tty output queue.
 664                                          */
 665                                         if (b_to_q((char *)bp, cp - bp,
 666                                             &tp->t_outq))
 667                                                 break;
 668                                         sc->sc_if.if_obytes += cp - bp;
 669                                 }
 670                                 /*
 671                                  * If there are characters left in the mbuf,
 672                                  * the first one must be special..
 673                                  * Put it out in a different form.
 674                                  */
 675                                 if (cp < ep) {
 676                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 677                                                 break;
 678                                         if (putc(*cp++ == FRAME_ESCAPE ?
 679                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 680                                            &tp->t_outq)) {
 681                                                 (void) unputc(&tp->t_outq);
 682                                                 break;
 683                                         }
 684                                         sc->sc_if.if_obytes += 2;
 685                                 }
 686                         }
 687                         m = m_free(m);
 688                 }
 689
 690                 if (putc(FRAME_END, &tp->t_outq)) {
 691                         /*
 692                          * Not enough room.  Remove a char to make room
 693                          * and end the packet normally.
 694                          * If you get many collisions (more than one or two
 695                          * a day) you probably do not have enough clists
 696                          * and you should increase "nclist" in param.c.
 697                          */
 698                         (void) unputc(&tp->t_outq);
 699                         (void) putc(FRAME_END, &tp->t_outq);
 700                         sc->sc_if.if_collisions++;
 701                 } else {
 702                         ++sc->sc_if.if_obytes;
 703                         sc->sc_if.if_opackets++;
 704                 }
 705         }
 706         return 0;
 707 }
 708
 709 /*
 710  * Copy data buffer to mbuf chain; add ifnet pointer.
 711  */
 712 static struct mbuf *
 713 sl_btom(sc, len)
 714         struct sl_softc *sc;
 715         int len;
 716 {
 717         struct mbuf *m;
 718
 719         if (len >= MCLBYTES)
 720                 return (NULL);
 721
 722         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 723         if (m == NULL)
 724                 return (NULL);
 725
 726         /*
 727          * If we have more than MHLEN bytes, it's cheaper to
 728          * queue the cluster we just filled & allocate a new one
 729          * for the input buffer.  Otherwise, fill the mbuf we
 730          * allocated above.  Note that code in the input routine
 731          * guarantees that packet will fit in a cluster.
 732          */
 733         if (len >= MHLEN) {
 734                 MCLGET(m, MB_DONTWAIT);
 735                 if ((m->m_flags & M_EXT) == 0) {
 736                         /*
 737                          * we couldn't get a cluster - if memory's this
 738                          * low, it's time to start dropping packets.
 739                          */
 740                         m_free(m);
 741                         return (NULL);
 742                 }
 743         }
 744         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 745         m->m_len = len;
 746         m->m_pkthdr.len = len;
 747         m->m_pkthdr.rcvif = &sc->sc_if;
 748         return (m);
 749 }
 750
 751 /*
 752  * tty interface receiver interrupt.
 753  */
 754 static int
 755 slinput(c, tp)
 756         int c;
 757         struct tty *tp;
 758 {
 759         struct sl_softc *sc;
 760         struct mbuf *m;
 761         int len;
 762         u_char chdr[CHDR_LEN];
 763
 764         tk_nin++;
 765         sc = (struct sl_softc *)tp->t_sc;
 766         if (sc == NULL)
 767                 return 0;
 768         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 769                 sc->sc_flags |= SC_ERROR;
 770                 return 0;
 771         }
 772         c &= TTY_CHARMASK;
 773
 774         ++sc->sc_if.if_ibytes;
 775
 776         if (sc->sc_if.if_flags & IFF_DEBUG) {
 777                 if (c == ABT_ESC) {
 778                         /*
 779                          * If we have a previous abort, see whether
 780                          * this one is within the time limit.
 781                          */
 782                         if (sc->sc_abortcount &&
 783                             time_second >= sc->sc_starttime + ABT_WINDOW)
 784                                 sc->sc_abortcount = 0;
 785                         /*
 786                          * If we see an abort after "idle" time, count it;
 787                          * record when the first abort escape arrived.
 788                          */
 789                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 790                                 if (++sc->sc_abortcount == 1)
 791                                         sc->sc_starttime = time_second;
 792                                 if (sc->sc_abortcount >= ABT_COUNT) {
 793                                         slclose(tp,0);
 794                                         return 0;
 795                                 }
 796                         }
 797                 } else
 798                         sc->sc_abortcount = 0;
 799                 sc->sc_lasttime = time_second;
 800         }
 801
 802         switch (c) {
 803
 804         case TRANS_FRAME_ESCAPE:
 805                 if (sc->sc_escape)
 806                         c = FRAME_ESCAPE;
 807                 break;
 808
 809         case TRANS_FRAME_END:
 810                 if (sc->sc_escape)
 811                         c = FRAME_END;
 812                 break;
 813
 814         case FRAME_ESCAPE:
 815                 sc->sc_escape = 1;
 816                 return 0;
 817
 818         case FRAME_END:
 819                 sc->sc_flags &= ~SC_KEEPALIVE;
 820                 if(sc->sc_flags & SC_ERROR) {
 821                         sc->sc_flags &= ~SC_ERROR;
 822                         goto newpack;
 823                 }
 824                 len = sc->sc_mp - sc->sc_buf;
 825                 if (len < 3)
 826                         /* less than min length packet - ignore */
 827                         goto newpack;
 828
 829                 if (sc->sc_if.if_bpf) {
 830                         /*
 831                          * Save the compressed header, so we
 832                          * can tack it on later.  Note that we
 833                          * will end up copying garbage in some
 834                          * cases but this is okay.  We remember
 835                          * where the buffer started so we can
 836                          * compute the new header length.
 837                          */
 838                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 839                 }
 840
 841                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 842                         if (c & 0x80)
 843                                 c = TYPE_COMPRESSED_TCP;
 844                         else if (c == TYPE_UNCOMPRESSED_TCP)
 845                                 *sc->sc_buf &= 0x4f; /* XXX */
 846                         /*
 847                          * We've got something that's not an IP packet.
 848                          * If compression is enabled, try to decompress it.
 849                          * Otherwise, if `auto-enable' compression is on and
 850                          * it's a reasonable packet, decompress it and then
 851                          * enable compression.  Otherwise, drop it.
 852                          */
 853                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 854                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 855                                                         (u_int)c, &sc->sc_comp);
 856                                 if (len <= 0)
 857                                         goto error;
 858                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 859                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 860                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 861                                                         (u_int)c, &sc->sc_comp);
 862                                 if (len <= 0)
 863                                         goto error;
 864                                 sc->sc_if.if_flags |= SC_COMPRESS;
 865                         } else
 866                                 goto error;
 867                 }
 868                 if (sc->sc_if.if_bpf) {
 869                         /*
 870                          * Put the SLIP pseudo-"link header" in place.
 871                          * We couldn't do this any earlier since
 872                          * decompression probably moved the buffer
 873                          * pointer.  Then, invoke BPF.
 874                          */
 875                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 876
 877                         hp[SLX_DIR] = SLIPDIR_IN;
 878                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 879                         bpf_tap(&sc->sc_if, hp, len + SLIP_HDRLEN);
 880                 }
 881                 m = sl_btom(sc, len);
 882                 if (m == NULL)
 883                         goto error;
 884
 885                 sc->sc_if.if_ipackets++;
 886
 887                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 888                         m_freem(m);
 889                         goto newpack;
 890                 }
 891
 892                 if (netisr_queue(NETISR_IP, m)) {
 893                         sc->sc_if.if_ierrors++;
 894                         sc->sc_if.if_iqdrops++;
 895                 }
 896
 897                 goto newpack;
 898         }
 899         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 900                 *sc->sc_mp++ = c;
 901                 sc->sc_escape = 0;
 902                 return 0;
 903         }
 904
 905         /* can't put lower; would miss an extra frame */
 906         sc->sc_flags |= SC_ERROR;
 907
 908 error:
 909         sc->sc_if.if_ierrors++;
 910 newpack:
 911         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 912         sc->sc_escape = 0;
 913         return 0;
 914 }
 915
 916 /*
 917  * Process an ioctl request.
 918  */
 919 static int
 920 slioctl(ifp, cmd, data, cr)
 921         struct ifnet *ifp;
 922         u_long cmd;
 923         caddr_t data;
 924         struct ucred *cr;
 925 {
 926         struct ifaddr *ifa = (struct ifaddr *)data;
 927         struct ifreq *ifr = (struct ifreq *)data;
 928         int s, error = 0;
 929
 930         s = splimp();
 931
 932         switch (cmd) {
 933
 934         case SIOCSIFFLAGS:
 935                 /*
 936                  * if.c will set the interface up even if we
 937                  * don't want it to.
 938                  */
 939                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 940                         ifp->if_flags &= ~IFF_UP;
 941                 }
 942                 break;
 943         case SIOCSIFADDR:
 944                 /*
 945                  * This is "historical" - set the interface up when
 946                  * setting the address.
 947                  */
 948                 if (ifa->ifa_addr->sa_family == AF_INET) {
 949                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 950                                 ifp->if_flags |= IFF_UP;
 951                 } else {
 952                         error = EAFNOSUPPORT;
 953                 }
 954                 break;
 955
 956         case SIOCSIFDSTADDR:
 957                 if (ifa->ifa_addr->sa_family != AF_INET)
 958                         error = EAFNOSUPPORT;
 959                 break;
 960
 961         case SIOCADDMULTI:
 962         case SIOCDELMULTI:
 963                 break;
 964
 965         case SIOCSIFMTU:
 966                 /*
 967                  * Set the interface MTU.
 968                  */
 969                 if (ifr->ifr_mtu > SLTMAX)
 970                         error = EINVAL;
 971                 else {
 972                         struct tty *tp;
 973
 974                         ifp->if_mtu = ifr->ifr_mtu;
 975                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 976                         if (tp != NULL)
 977                                 clist_alloc_cblocks(&tp->t_outq,
 978                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 979                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 980                 }
 981                 break;
 982
 983         default:
 984                 error = EINVAL;
 985         }
 986         splx(s);
 987         return (error);
 988 }
 989
 990 static void
 991 sl_keepalive(chan)
 992         void *chan;
 993 {
 994         struct sl_softc *sc = chan;
 995
 996         if (sc->sc_keepalive) {
 997                 if (sc->sc_flags & SC_KEEPALIVE)
 998                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 999                 else
1000                         sc->sc_flags |= SC_KEEPALIVE;
1001                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
1002                                 sl_keepalive, sc);
1003         } else {
1004                 sc->sc_flags &= ~SC_KEEPALIVE;
1005         }
1006 }
1007
1008 static void
1009 sl_outfill(chan)
1010         void *chan;
1011 {
1012         struct sl_softc *sc = chan;
1013         struct tty *tp = sc->sc_ttyp;
1014         int s;
1015
1016         if (sc->sc_outfill && tp != NULL) {
1017                 if (sc->sc_flags & SC_OUTWAIT) {
1018                         s = splimp ();
1019                         ++sc->sc_if.if_obytes;
1020                         (void) putc(FRAME_END, &tp->t_outq);
1021                         (*tp->t_oproc)(tp);
1022                         splx (s);
1023                 } else
1024                         sc->sc_flags |= SC_OUTWAIT;
1025                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1026                                 sl_outfill, sc);
1027         } else {
1028                 sc->sc_flags &= ~SC_OUTWAIT;
1029         }
1030 }