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 1.14 2004/07/31 07:52:54 dillon Exp $
  36  */
  37
  38 /*
  39  * Serial Line interface
  40  *
  41  * Rick Adams
  42  * Center for Seismic Studies
  43  * 1300 N 17th Street, Suite 1450
  44  * Arlington, Virginia 22209
  45  * (703)276-7900
  46  * rick@seismo.ARPA
  47  * seismo!rick
  48  *
  49  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  50  * N.B.: this belongs in netinet, not net, the way it stands now.
  51  * Should have a link-layer type designation, but wouldn't be
  52  * backwards-compatible.
  53  *
  54  * Converted to 4.3BSD Beta by Chris Torek.
  55  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  56  * W. Jolitz added slip abort.
  57  *
  58  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  59  * Added priority queuing for "interactive" traffic; hooks for TCP
  60  * header compression; ICMP filtering (at 2400 baud, some cretin
  61  * pinging you can use up all your bandwidth).  Made low clist behavior
  62  * more robust and slightly less likely to hang serial line.
  63  * Sped up a bunch of things.
  64  *
  65  * Note that splimp() is used throughout to block both (tty) input
  66  * interrupts and network activity; thus, splimp must be >= spltty.
  67  */
  68
  69 #include "use_sl.h"
  70
  71 #include "opt_inet.h"
  72 #if !defined(KLD_MODULE)
  73 #include "opt_slip.h"
  74 #endif
  75 #include <sys/param.h>
  76 #include <sys/systm.h>
  77 #include <sys/proc.h>
  78 #include <sys/malloc.h>
  79 #include <sys/mbuf.h>
  80 #include <sys/dkstat.h>
  81 #include <sys/socket.h>
  82 #include <sys/sockio.h>
  83 #include <sys/fcntl.h>
  84 #include <sys/signalvar.h>
  85 #include <sys/tty.h>
  86 #include <sys/clist.h>
  87 #include <sys/kernel.h>
  88 #include <sys/conf.h>
  89
  90 #include <net/if.h>
  91 #include <net/if_types.h>
  92 #include <net/netisr.h>
  93
  94 #if INET
  95 #include <netinet/in.h>
  96 #include <netinet/in_systm.h>
  97 #include <netinet/in_var.h>
  98 #include <netinet/ip.h>
  99 #else
 100 #error "Huh? Slip without inet?"
 101 #endif
 102
 103 #include <net/slcompress.h>
 104 #include "if_slvar.h"
 105 #include <net/slip.h>
 106
 107 #include <net/bpf.h>
 108
 109 #ifdef __i386__
 110 #include <i386/isa/intr_machdep.h>
 111 #endif
 112
 113 static void slattach (void *);
 114 PSEUDO_SET(slattach, if_sl);
 115
 116 /*
 117  * SLRMAX is a hard limit on input packet size.  To simplify the code
 118  * and improve performance, we require that packets fit in an mbuf
 119  * cluster, and if we get a compressed packet, there's enough extra
 120  * room to expand the header into a max length tcp/ip header (128
 121  * bytes).  So, SLRMAX can be at most
 122  *      MCLBYTES - 128
 123  *
 124  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 125  * small enough so that interactive use doesn't suffer, but large
 126  * enough to provide good performance. 552 is a good choice for SLMTU
 127  * because it is high enough to not fragment TCP packets being routed
 128  * through this host. Packet fragmentation is bad with SLIP because
 129  * fragment headers aren't compressed. The previous assumptions about
 130  * the best MTU value don't really hold when using modern modems with
 131  * BTLZ data compression because the modem buffers play a much larger
 132  * role in interactive performance than the MTU. The MTU can be changed
 133  * at any time to suit the specific environment with ifconfig(8), and
 134  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 135  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 136  * handles this better).
 137  *
 138  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 139  * of us (i.e., in clists waiting to be picked up by the tty output
 140  * interrupt).  If we queue a lot of data downstream, it's immune to
 141  * our t.o.s. queuing.
 142  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 143  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 144  * wait is dependent on the ftp window size but that's typically
 145  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 146  * the cost (in idle time on the wire) of the tty driver running
 147  * off the end of its clists & having to call back slstart for a
 148  * new packet.  For a tty interface with any buffering at all, this
 149  * cost will be zero.  Even with a totally brain dead interface (like
 150  * the one on a typical workstation), the cost will be <= 1 character
 151  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 152  * at most 1% while maintaining good interactive response.
 153  */
 154 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 155 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 156 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 157 #ifndef SLMTU
 158 #define SLMTU           552             /* default MTU */
 159 #endif
 160 #define SLTMAX          1500            /* maximum MTU */
 161 #define SLIP_HIWAT      roundup(50,CBSIZE)
 162 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 163
 164 /*
 165  * SLIP ABORT ESCAPE MECHANISM:
 166  *      (inspired by HAYES modem escape arrangement)
 167  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 168  *      within window time signals a "soft" exit from slip mode by remote end
 169  *      if the IFF_DEBUG flag is on.
 170  */
 171 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 172 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 173 #define ABT_COUNT       3       /* count of escapes for abort */
 174 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 175
 176 static struct sl_softc sl_softc[NSL];
 177
 178 #define FRAME_END               0xc0            /* Frame End */
 179 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 180 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 181 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 182
 183 static int slinit (struct sl_softc *);
 184 static struct mbuf *sl_btom (struct sl_softc *, int);
 185 static timeout_t sl_keepalive;
 186 static timeout_t sl_outfill;
 187 static int      slclose (struct tty *,int);
 188 static int      slinput (int, struct tty *);
 189 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 190 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct thread *);
 191 static int      slopen (dev_t, struct tty *);
 192 static int      sloutput (struct ifnet *,
 193             struct mbuf *, struct sockaddr *, struct rtentry *);
 194 static int      slstart (struct tty *);
 195
 196 static struct linesw slipdisc = {
 197         slopen,         slclose,        l_noread,       l_nowrite,
 198         sltioctl,       slinput,        slstart,        ttymodem,
 199         FRAME_END
 200 };
 201
 202 /*
 203  * Called from boot code to establish sl interfaces.
 204  */
 205 static void
 206 slattach(dummy)
 207         void *dummy;
 208 {
 209         struct sl_softc *sc;
 210         int i = 0;
 211
 212         linesw[SLIPDISC] = slipdisc;
 213
 214         for (sc = sl_softc; i < NSL; sc++) {
 215                 if_initname(&(sc->sc_if), "sl", i++);
 216                 sc->sc_if.if_mtu = SLMTU;
 217                 sc->sc_if.if_flags =
 218 #ifdef SLIP_IFF_OPTS
 219                     SLIP_IFF_OPTS;
 220 #else
 221                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 222 #endif
 223                 sc->sc_if.if_type = IFT_SLIP;
 224                 sc->sc_if.if_ioctl = slioctl;
 225                 sc->sc_if.if_output = sloutput;
 226                 sc->sc_if.if_snd.ifq_maxlen = 50;
 227                 sc->sc_fastq.ifq_maxlen = 32;
 228                 sc->sc_if.if_linkmib = sc;
 229                 sc->sc_if.if_linkmiblen = sizeof *sc;
 230                 if_attach(&sc->sc_if);
 231                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 232         }
 233 }
 234
 235 static int
 236 slinit(sc)
 237         struct sl_softc *sc;
 238 {
 239 #ifdef __i386__
 240         int s;
 241
 242         s = splhigh();
 243         tty_imask |= net_imask;
 244         net_imask = tty_imask;
 245         update_intr_masks();
 246         splx(s);
 247         if (bootverbose)
 248                 printf("new imasks: bio %x, tty %x, net %x\n",
 249                     bio_imask, tty_imask, net_imask);
 250 #endif
 251         if (sc->sc_ep == NULL)
 252                 sc->sc_ep = malloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 253         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 254         sc->sc_mp = sc->sc_buf;
 255         sl_compress_init(&sc->sc_comp, -1);
 256         return (1);
 257 }
 258
 259 /*
 260  * Line specific open routine.
 261  * Attach the given tty to the first available sl unit.
 262  */
 263 /* ARGSUSED */
 264 static int
 265 slopen(dev_t dev, struct tty *tp)
 266 {
 267         struct sl_softc *sc;
 268         int nsl;
 269         int s, error;
 270         struct thread *td = curthread;  /* XXX */
 271
 272         error = suser(td);
 273         if (error)
 274                 return (error);
 275
 276         if (tp->t_line == SLIPDISC)
 277                 return (0);
 278
 279         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 280                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 281                         if (slinit(sc) == 0)
 282                                 return (ENOBUFS);
 283                         tp->t_sc = (caddr_t)sc;
 284                         sc->sc_ttyp = tp;
 285                         sc->sc_if.if_baudrate = tp->t_ospeed;
 286                         ttyflush(tp, FREAD | FWRITE);
 287
 288                         tp->t_line = SLIPDISC;
 289                         /*
 290                          * We don't use t_canq or t_rawq, so reduce their
 291                          * cblock resources to 0.  Reserve enough cblocks
 292                          * for t_outq to guarantee that we can fit a full
 293                          * packet if the SLIP_HIWAT check allows slstart()
 294                          * to loop.  Use the same value for the cblock
 295                          * limit since the reserved blocks should always
 296                          * be enough.  Reserving cblocks probably makes
 297                          * the CLISTRESERVE check unnecessary and wasteful.
 298                          */
 299                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 300                         clist_alloc_cblocks(&tp->t_outq,
 301                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 302                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 303                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 304
 305                         s = splnet();
 306                         if_up(&sc->sc_if);
 307                         splx(s);
 308                         return (0);
 309                 }
 310         return (ENXIO);
 311 }
 312
 313 /*
 314  * Line specific close routine.
 315  * Detach the tty from the sl unit.
 316  */
 317 static int
 318 slclose(tp,flag)
 319         struct tty *tp;
 320         int flag;
 321 {
 322         struct sl_softc *sc;
 323         int s;
 324
 325         ttyflush(tp, FREAD | FWRITE);
 326         /*
 327          * XXX the placement of the following spl is misleading.  tty
 328          * interrupts must be blocked across line discipline switches
 329          * and throughout closes to avoid races.
 330          */
 331         s = splimp();           /* actually, max(spltty, splnet) */
 332         clist_free_cblocks(&tp->t_outq);
 333         tp->t_line = 0;
 334         sc = (struct sl_softc *)tp->t_sc;
 335         if (sc != NULL) {
 336                 if (sc->sc_outfill) {
 337                         sc->sc_outfill = 0;
 338                         untimeout(sl_outfill, sc, sc->sc_ofhandle);
 339                 }
 340                 if (sc->sc_keepalive) {
 341                         sc->sc_keepalive = 0;
 342                         untimeout(sl_keepalive, sc, sc->sc_kahandle);
 343                 }
 344                 if_down(&sc->sc_if);
 345                 sc->sc_flags &= SC_STATIC;
 346                 sc->sc_ttyp = NULL;
 347                 tp->t_sc = NULL;
 348                 if (sc->sc_ep) {
 349                         free(sc->sc_ep, M_DEVBUF);
 350                         sc->sc_ep = NULL;
 351                 }
 352                 sc->sc_mp = 0;
 353                 sc->sc_buf = 0;
 354         }
 355         splx(s);
 356         return 0;
 357 }
 358
 359 /*
 360  * Line specific (tty) ioctl routine.
 361  * Provide a way to get the sl unit number.
 362  */
 363 /* ARGSUSED */
 364 static int
 365 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 366 {
 367         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 368         int s, nsl;
 369
 370         s = splimp();
 371         switch (cmd) {
 372         case SLIOCGUNIT:
 373                 *(int *)data = sc->sc_if.if_dunit;
 374                 break;
 375
 376         case SLIOCSUNIT:
 377                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 378                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 379                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 380                                     && nc->sc_ttyp == NULL
 381                                    ) {
 382                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 383                                                        M_WAITOK);
 384                                         *tmpnc = *nc;
 385                                         *nc = *sc;
 386                                         nc->sc_if = tmpnc->sc_if;
 387                                         tmpnc->sc_if = sc->sc_if;
 388                                         *sc = *tmpnc;
 389                                         free(tmpnc, M_TEMP);
 390                                         if (sc->sc_if.if_flags & IFF_UP) {
 391                                                 if_down(&sc->sc_if);
 392                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 393                                                         if_up(&nc->sc_if);
 394                                         } else if (nc->sc_if.if_flags & IFF_UP)
 395                                                 if_down(&nc->sc_if);
 396                                         sc->sc_flags &= ~SC_STATIC;
 397                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 398                                         tp->t_sc = sc = nc;
 399                                         clist_alloc_cblocks(&tp->t_outq,
 400                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 401                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 402                                         sl_compress_init(&sc->sc_comp, -1);
 403                                         goto slfound;
 404                                 }
 405                         }
 406                         splx(s);
 407                         return (ENXIO);
 408                 }
 409         slfound:
 410                 sc->sc_flags |= SC_STATIC;
 411                 break;
 412
 413         case SLIOCSKEEPAL:
 414                 sc->sc_keepalive = *(u_int *)data * hz;
 415                 if (sc->sc_keepalive) {
 416                         sc->sc_flags |= SC_KEEPALIVE;
 417                         sc->sc_kahandle = timeout(sl_keepalive, sc,
 418                                                   sc->sc_keepalive);
 419                 } else {
 420                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 421                                 untimeout(sl_keepalive, sc, sc->sc_kahandle);
 422                                 sc->sc_flags &= ~SC_KEEPALIVE;
 423                         }
 424                 }
 425                 break;
 426
 427         case SLIOCGKEEPAL:
 428                 *(int *)data = sc->sc_keepalive / hz;
 429                 break;
 430
 431         case SLIOCSOUTFILL:
 432                 sc->sc_outfill = *(u_int *)data * hz;
 433                 if (sc->sc_outfill) {
 434                         sc->sc_flags |= SC_OUTWAIT;
 435                         sc->sc_ofhandle = timeout(sl_outfill, sc,
 436                                                   sc->sc_outfill);
 437                 } else {
 438                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 439                                 untimeout(sl_outfill, sc, sc->sc_ofhandle);
 440                                 sc->sc_flags &= ~SC_OUTWAIT;
 441                         }
 442                 }
 443                 break;
 444
 445         case SLIOCGOUTFILL:
 446                 *(int *)data = sc->sc_outfill / hz;
 447                 break;
 448
 449         default:
 450                 splx(s);
 451                 return (ENOIOCTL);
 452         }
 453         splx(s);
 454         return (0);
 455 }
 456
 457 /*
 458  * Queue a packet.  Start transmission if not active.
 459  * Compression happens in slstart; if we do it here, IP TOS
 460  * will cause us to not compress "background" packets, because
 461  * ordering gets trashed.  It can be done for all packets in slstart.
 462  */
 463 static int
 464 sloutput(ifp, m, dst, rtp)
 465         struct ifnet *ifp;
 466         struct mbuf *m;
 467         struct sockaddr *dst;
 468         struct rtentry *rtp;
 469 {
 470         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 471         struct ip *ip;
 472         struct ifqueue *ifq;
 473         int s;
 474
 475         /*
 476          * `Cannot happen' (see slioctl).  Someday we will extend
 477          * the line protocol to support other address families.
 478          */
 479         if (dst->sa_family != AF_INET) {
 480                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 481                         dst->sa_family);
 482                 m_freem(m);
 483                 sc->sc_if.if_noproto++;
 484                 return (EAFNOSUPPORT);
 485         }
 486
 487         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 488                 m_freem(m);
 489                 return (ENETDOWN);
 490         }
 491         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 492                 m_freem(m);
 493                 return (EHOSTUNREACH);
 494         }
 495         ifq = &sc->sc_if.if_snd;
 496         ip = mtod(m, struct ip *);
 497         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 498                 m_freem(m);
 499                 return (ENETRESET);             /* XXX ? */
 500         }
 501         if (ip->ip_tos & IPTOS_LOWDELAY)
 502                 ifq = &sc->sc_fastq;
 503         s = splimp();
 504         if (IF_QFULL(ifq)) {
 505                 IF_DROP(ifq);
 506                 m_freem(m);
 507                 splx(s);
 508                 sc->sc_if.if_oerrors++;
 509                 return (ENOBUFS);
 510         }
 511         IF_ENQUEUE(ifq, m);
 512         if (sc->sc_ttyp->t_outq.c_cc == 0)
 513                 slstart(sc->sc_ttyp);
 514         splx(s);
 515         return (0);
 516 }
 517
 518 /*
 519  * Start output on interface.  Get another datagram
 520  * to send from the interface queue and map it to
 521  * the interface before starting output.
 522  */
 523 static int
 524 slstart(tp)
 525         struct tty *tp;
 526 {
 527         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 528         struct mbuf *m;
 529         u_char *cp;
 530         struct ip *ip;
 531         int s;
 532         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 533         int len = 0;
 534
 535         for (;;) {
 536                 /*
 537                  * Call output process whether or not there is more in the
 538                  * output queue.  We are being called in lieu of ttstart
 539                  * and must do what it would.
 540                  */
 541                 (*tp->t_oproc)(tp);
 542
 543                 if (tp->t_outq.c_cc != 0) {
 544                         if (sc != NULL)
 545                                 sc->sc_flags &= ~SC_OUTWAIT;
 546                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 547                                 return 0;
 548                 }
 549
 550                 /*
 551                  * This happens briefly when the line shuts down.
 552                  */
 553                 if (sc == NULL)
 554                         return 0;
 555
 556                 /*
 557                  * Get a packet and send it to the interface.
 558                  */
 559                 s = splimp();
 560                 IF_DEQUEUE(&sc->sc_fastq, m);
 561                 if (m)
 562                         sc->sc_if.if_omcasts++;         /* XXX */
 563                 else
 564                         IF_DEQUEUE(&sc->sc_if.if_snd, m);
 565                 splx(s);
 566                 if (m == NULL)
 567                         return 0;
 568
 569                 /*
 570                  * We do the header compression here rather than in sloutput
 571                  * because the packets will be out of order if we are using TOS
 572                  * queueing, and the connection id compression will get
 573                  * munged when this happens.
 574                  */
 575                 if (sc->sc_if.if_bpf) {
 576                         /*
 577                          * We need to save the TCP/IP header before it's
 578                          * compressed.  To avoid complicated code, we just
 579                          * copy the entire packet into a stack buffer (since
 580                          * this is a serial line, packets should be short
 581                          * and/or the copy should be negligible cost compared
 582                          * to the packet transmission time).
 583                          */
 584                         struct mbuf *m1 = m;
 585                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 586
 587                         len = 0;
 588                         do {
 589                                 int mlen = m1->m_len;
 590
 591                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 592                                 cp += mlen;
 593                                 len += mlen;
 594                         } while ((m1 = m1->m_next) != NULL);
 595                 }
 596                 ip = mtod(m, struct ip *);
 597                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 598                         if (sc->sc_if.if_flags & SC_COMPRESS)
 599                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 600                                     &sc->sc_comp, 1);
 601                 }
 602                 if (sc->sc_if.if_bpf) {
 603                         /*
 604                          * Put the SLIP pseudo-"link header" in place.  The
 605                          * compressed header is now at the beginning of the
 606                          * mbuf.
 607                          */
 608                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 609                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 610                         bpf_tap(&sc->sc_if, bpfbuf, len + SLIP_HDRLEN);
 611                 }
 612
 613                 /*
 614                  * If system is getting low on clists, just flush our
 615                  * output queue (if the stuff was important, it'll get
 616                  * retransmitted). Note that SLTMAX is used instead of
 617                  * the current if_mtu setting because connections that
 618                  * have already been established still use the original
 619                  * (possibly larger) mss.
 620                  */
 621                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 622                         m_freem(m);
 623                         sc->sc_if.if_collisions++;
 624                         continue;
 625                 }
 626
 627                 sc->sc_flags &= ~SC_OUTWAIT;
 628                 /*
 629                  * The extra FRAME_END will start up a new packet, and thus
 630                  * will flush any accumulated garbage.  We do this whenever
 631                  * the line may have been idle for some time.
 632                  */
 633                 if (tp->t_outq.c_cc == 0) {
 634                         ++sc->sc_if.if_obytes;
 635                         (void) putc(FRAME_END, &tp->t_outq);
 636                 }
 637
 638                 while (m) {
 639                         u_char *ep;
 640
 641                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 642                         while (cp < ep) {
 643                                 /*
 644                                  * Find out how many bytes in the string we can
 645                                  * handle without doing something special.
 646                                  */
 647                                 u_char *bp = cp;
 648
 649                                 while (cp < ep) {
 650                                         switch (*cp++) {
 651                                         case FRAME_ESCAPE:
 652                                         case FRAME_END:
 653                                                 --cp;
 654                                                 goto out;
 655                                         }
 656                                 }
 657                                 out:
 658                                 if (cp > bp) {
 659                                         /*
 660                                          * Put n characters at once
 661                                          * into the tty output queue.
 662                                          */
 663                                         if (b_to_q((char *)bp, cp - bp,
 664                                             &tp->t_outq))
 665                                                 break;
 666                                         sc->sc_if.if_obytes += cp - bp;
 667                                 }
 668                                 /*
 669                                  * If there are characters left in the mbuf,
 670                                  * the first one must be special..
 671                                  * Put it out in a different form.
 672                                  */
 673                                 if (cp < ep) {
 674                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 675                                                 break;
 676                                         if (putc(*cp++ == FRAME_ESCAPE ?
 677                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 678                                            &tp->t_outq)) {
 679                                                 (void) unputc(&tp->t_outq);
 680                                                 break;
 681                                         }
 682                                         sc->sc_if.if_obytes += 2;
 683                                 }
 684                         }
 685                         m = m_free(m);
 686                 }
 687
 688                 if (putc(FRAME_END, &tp->t_outq)) {
 689                         /*
 690                          * Not enough room.  Remove a char to make room
 691                          * and end the packet normally.
 692                          * If you get many collisions (more than one or two
 693                          * a day) you probably do not have enough clists
 694                          * and you should increase "nclist" in param.c.
 695                          */
 696                         (void) unputc(&tp->t_outq);
 697                         (void) putc(FRAME_END, &tp->t_outq);
 698                         sc->sc_if.if_collisions++;
 699                 } else {
 700                         ++sc->sc_if.if_obytes;
 701                         sc->sc_if.if_opackets++;
 702                 }
 703         }
 704         return 0;
 705 }
 706
 707 /*
 708  * Copy data buffer to mbuf chain; add ifnet pointer.
 709  */
 710 static struct mbuf *
 711 sl_btom(sc, len)
 712         struct sl_softc *sc;
 713         int len;
 714 {
 715         struct mbuf *m;
 716
 717         if (len >= MCLBYTES)
 718                 return (NULL);
 719
 720         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 721         if (m == NULL)
 722                 return (NULL);
 723
 724         /*
 725          * If we have more than MHLEN bytes, it's cheaper to
 726          * queue the cluster we just filled & allocate a new one
 727          * for the input buffer.  Otherwise, fill the mbuf we
 728          * allocated above.  Note that code in the input routine
 729          * guarantees that packet will fit in a cluster.
 730          */
 731         if (len >= MHLEN) {
 732                 MCLGET(m, MB_DONTWAIT);
 733                 if ((m->m_flags & M_EXT) == 0) {
 734                         /*
 735                          * we couldn't get a cluster - if memory's this
 736                          * low, it's time to start dropping packets.
 737                          */
 738                         m_free(m);
 739                         return (NULL);
 740                 }
 741         }
 742         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 743         m->m_len = len;
 744         m->m_pkthdr.len = len;
 745         m->m_pkthdr.rcvif = &sc->sc_if;
 746         return (m);
 747 }
 748
 749 /*
 750  * tty interface receiver interrupt.
 751  */
 752 static int
 753 slinput(c, tp)
 754         int c;
 755         struct tty *tp;
 756 {
 757         struct sl_softc *sc;
 758         struct mbuf *m;
 759         int len;
 760         u_char chdr[CHDR_LEN];
 761
 762         tk_nin++;
 763         sc = (struct sl_softc *)tp->t_sc;
 764         if (sc == NULL)
 765                 return 0;
 766         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 767                 sc->sc_flags |= SC_ERROR;
 768                 return 0;
 769         }
 770         c &= TTY_CHARMASK;
 771
 772         ++sc->sc_if.if_ibytes;
 773
 774         if (sc->sc_if.if_flags & IFF_DEBUG) {
 775                 if (c == ABT_ESC) {
 776                         /*
 777                          * If we have a previous abort, see whether
 778                          * this one is within the time limit.
 779                          */
 780                         if (sc->sc_abortcount &&
 781                             time_second >= sc->sc_starttime + ABT_WINDOW)
 782                                 sc->sc_abortcount = 0;
 783                         /*
 784                          * If we see an abort after "idle" time, count it;
 785                          * record when the first abort escape arrived.
 786                          */
 787                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 788                                 if (++sc->sc_abortcount == 1)
 789                                         sc->sc_starttime = time_second;
 790                                 if (sc->sc_abortcount >= ABT_COUNT) {
 791                                         slclose(tp,0);
 792                                         return 0;
 793                                 }
 794                         }
 795                 } else
 796                         sc->sc_abortcount = 0;
 797                 sc->sc_lasttime = time_second;
 798         }
 799
 800         switch (c) {
 801
 802         case TRANS_FRAME_ESCAPE:
 803                 if (sc->sc_escape)
 804                         c = FRAME_ESCAPE;
 805                 break;
 806
 807         case TRANS_FRAME_END:
 808                 if (sc->sc_escape)
 809                         c = FRAME_END;
 810                 break;
 811
 812         case FRAME_ESCAPE:
 813                 sc->sc_escape = 1;
 814                 return 0;
 815
 816         case FRAME_END:
 817                 sc->sc_flags &= ~SC_KEEPALIVE;
 818                 if(sc->sc_flags & SC_ERROR) {
 819                         sc->sc_flags &= ~SC_ERROR;
 820                         goto newpack;
 821                 }
 822                 len = sc->sc_mp - sc->sc_buf;
 823                 if (len < 3)
 824                         /* less than min length packet - ignore */
 825                         goto newpack;
 826
 827                 if (sc->sc_if.if_bpf) {
 828                         /*
 829                          * Save the compressed header, so we
 830                          * can tack it on later.  Note that we
 831                          * will end up copying garbage in some
 832                          * cases but this is okay.  We remember
 833                          * where the buffer started so we can
 834                          * compute the new header length.
 835                          */
 836                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 837                 }
 838
 839                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 840                         if (c & 0x80)
 841                                 c = TYPE_COMPRESSED_TCP;
 842                         else if (c == TYPE_UNCOMPRESSED_TCP)
 843                                 *sc->sc_buf &= 0x4f; /* XXX */
 844                         /*
 845                          * We've got something that's not an IP packet.
 846                          * If compression is enabled, try to decompress it.
 847                          * Otherwise, if `auto-enable' compression is on and
 848                          * it's a reasonable packet, decompress it and then
 849                          * enable compression.  Otherwise, drop it.
 850                          */
 851                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 852                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 853                                                         (u_int)c, &sc->sc_comp);
 854                                 if (len <= 0)
 855                                         goto error;
 856                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 857                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 858                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 859                                                         (u_int)c, &sc->sc_comp);
 860                                 if (len <= 0)
 861                                         goto error;
 862                                 sc->sc_if.if_flags |= SC_COMPRESS;
 863                         } else
 864                                 goto error;
 865                 }
 866                 if (sc->sc_if.if_bpf) {
 867                         /*
 868                          * Put the SLIP pseudo-"link header" in place.
 869                          * We couldn't do this any earlier since
 870                          * decompression probably moved the buffer
 871                          * pointer.  Then, invoke BPF.
 872                          */
 873                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 874
 875                         hp[SLX_DIR] = SLIPDIR_IN;
 876                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 877                         bpf_tap(&sc->sc_if, hp, len + SLIP_HDRLEN);
 878                 }
 879                 m = sl_btom(sc, len);
 880                 if (m == NULL)
 881                         goto error;
 882
 883                 sc->sc_if.if_ipackets++;
 884
 885                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 886                         m_freem(m);
 887                         goto newpack;
 888                 }
 889
 890                 if (netisr_queue(NETISR_IP, m)) {
 891                         sc->sc_if.if_ierrors++;
 892                         sc->sc_if.if_iqdrops++;
 893                 }
 894
 895                 goto newpack;
 896         }
 897         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 898                 *sc->sc_mp++ = c;
 899                 sc->sc_escape = 0;
 900                 return 0;
 901         }
 902
 903         /* can't put lower; would miss an extra frame */
 904         sc->sc_flags |= SC_ERROR;
 905
 906 error:
 907         sc->sc_if.if_ierrors++;
 908 newpack:
 909         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 910         sc->sc_escape = 0;
 911         return 0;
 912 }
 913
 914 /*
 915  * Process an ioctl request.
 916  */
 917 static int
 918 slioctl(ifp, cmd, data, cr)
 919         struct ifnet *ifp;
 920         u_long cmd;
 921         caddr_t data;
 922         struct ucred *cr;
 923 {
 924         struct ifaddr *ifa = (struct ifaddr *)data;
 925         struct ifreq *ifr = (struct ifreq *)data;
 926         int s, error = 0;
 927
 928         s = splimp();
 929
 930         switch (cmd) {
 931
 932         case SIOCSIFFLAGS:
 933                 /*
 934                  * if.c will set the interface up even if we
 935                  * don't want it to.
 936                  */
 937                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 938                         ifp->if_flags &= ~IFF_UP;
 939                 }
 940                 break;
 941         case SIOCSIFADDR:
 942                 /*
 943                  * This is "historical" - set the interface up when
 944                  * setting the address.
 945                  */
 946                 if (ifa->ifa_addr->sa_family == AF_INET) {
 947                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 948                                 ifp->if_flags |= IFF_UP;
 949                 } else {
 950                         error = EAFNOSUPPORT;
 951                 }
 952                 break;
 953
 954         case SIOCSIFDSTADDR:
 955                 if (ifa->ifa_addr->sa_family != AF_INET)
 956                         error = EAFNOSUPPORT;
 957                 break;
 958
 959         case SIOCADDMULTI:
 960         case SIOCDELMULTI:
 961                 break;
 962
 963         case SIOCSIFMTU:
 964                 /*
 965                  * Set the interface MTU.
 966                  */
 967                 if (ifr->ifr_mtu > SLTMAX)
 968                         error = EINVAL;
 969                 else {
 970                         struct tty *tp;
 971
 972                         ifp->if_mtu = ifr->ifr_mtu;
 973                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 974                         if (tp != NULL)
 975                                 clist_alloc_cblocks(&tp->t_outq,
 976                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 977                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 978                 }
 979                 break;
 980
 981         default:
 982                 error = EINVAL;
 983         }
 984         splx(s);
 985         return (error);
 986 }
 987
 988 static void
 989 sl_keepalive(chan)
 990         void *chan;
 991 {
 992         struct sl_softc *sc = chan;
 993
 994         if (sc->sc_keepalive) {
 995                 if (sc->sc_flags & SC_KEEPALIVE)
 996                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 997                 else
 998                         sc->sc_flags |= SC_KEEPALIVE;
 999                 sc->sc_kahandle = timeout(sl_keepalive, sc, sc->sc_keepalive);
1000         } else {
1001                 sc->sc_flags &= ~SC_KEEPALIVE;
1002         }
1003 }
1004
1005 static void
1006 sl_outfill(chan)
1007         void *chan;
1008 {
1009         struct sl_softc *sc = chan;
1010         struct tty *tp = sc->sc_ttyp;
1011         int s;
1012
1013         if (sc->sc_outfill && tp != NULL) {
1014                 if (sc->sc_flags & SC_OUTWAIT) {
1015                         s = splimp ();
1016                         ++sc->sc_if.if_obytes;
1017                         (void) putc(FRAME_END, &tp->t_outq);
1018                         (*tp->t_oproc)(tp);
1019                         splx (s);
1020                 } else
1021                         sc->sc_flags |= SC_OUTWAIT;
1022                 sc->sc_ofhandle = timeout(sl_outfill, sc, sc->sc_outfill);
1023         } else {
1024                 sc->sc_flags &= ~SC_OUTWAIT;
1025         }
1026 }