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 1.32 2008/05/14 11:59:23 sephe Exp $
  36  */
  37
  38 /*
  39  * Serial Line interface
  40  *
  41  * Rick Adams
  42  * Center for Seismic Studies
  43  * 1300 N 17th Street, Suite 1450
  44  * Arlington, Virginia 22209
  45  * (703)276-7900
  46  * rick@seismo.ARPA
  47  * seismo!rick
  48  *
  49  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  50  * N.B.: this belongs in netinet, not net, the way it stands now.
  51  * Should have a link-layer type designation, but wouldn't be
  52  * backwards-compatible.
  53  *
  54  * Converted to 4.3BSD Beta by Chris Torek.
  55  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  56  * W. Jolitz added slip abort.
  57  *
  58  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  59  * Added priority queuing for "interactive" traffic; hooks for TCP
  60  * header compression; ICMP filtering (at 2400 baud, some cretin
  61  * pinging you can use up all your bandwidth).  Made low clist behavior
  62  * more robust and slightly less likely to hang serial line.
  63  * Sped up a bunch of things.
  64  */
  65
  66 #include "use_sl.h"
  67
  68 #include "opt_inet.h"
  69 #if !defined(KLD_MODULE)
  70 #include "opt_slip.h"
  71 #endif
  72 #include <sys/param.h>
  73 #include <sys/systm.h>
  74 #include <sys/proc.h>
  75 #include <sys/priv.h>
  76 #include <sys/malloc.h>
  77 #include <sys/mbuf.h>
  78 #include <sys/dkstat.h>
  79 #include <sys/socket.h>
  80 #include <sys/sockio.h>
  81 #include <sys/fcntl.h>
  82 #include <sys/signalvar.h>
  83 #include <sys/tty.h>
  84 #include <sys/clist.h>
  85 #include <sys/kernel.h>
  86 #include <sys/conf.h>
  87 #include <sys/thread2.h>
  88
  89 #include <net/if.h>
  90 #include <net/if_types.h>
  91 #include <net/ifq_var.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 static void slattach (void *);
 110 PSEUDO_SET(slattach, if_sl);
 111
 112 /*
 113  * SLRMAX is a hard limit on input packet size.  To simplify the code
 114  * and improve performance, we require that packets fit in an mbuf
 115  * cluster, and if we get a compressed packet, there's enough extra
 116  * room to expand the header into a max length tcp/ip header (128
 117  * bytes).  So, SLRMAX can be at most
 118  *      MCLBYTES - 128
 119  *
 120  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 121  * small enough so that interactive use doesn't suffer, but large
 122  * enough to provide good performance. 552 is a good choice for SLMTU
 123  * because it is high enough to not fragment TCP packets being routed
 124  * through this host. Packet fragmentation is bad with SLIP because
 125  * fragment headers aren't compressed. The previous assumptions about
 126  * the best MTU value don't really hold when using modern modems with
 127  * BTLZ data compression because the modem buffers play a much larger
 128  * role in interactive performance than the MTU. The MTU can be changed
 129  * at any time to suit the specific environment with ifconfig(8), and
 130  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 131  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 132  * handles this better).
 133  *
 134  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 135  * of us (i.e., in clists waiting to be picked up by the tty output
 136  * interrupt).  If we queue a lot of data downstream, it's immune to
 137  * our t.o.s. queuing.
 138  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 139  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 140  * wait is dependent on the ftp window size but that's typically
 141  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 142  * the cost (in idle time on the wire) of the tty driver running
 143  * off the end of its clists & having to call back slstart for a
 144  * new packet.  For a tty interface with any buffering at all, this
 145  * cost will be zero.  Even with a totally brain dead interface (like
 146  * the one on a typical workstation), the cost will be <= 1 character
 147  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 148  * at most 1% while maintaining good interactive response.
 149  */
 150 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 151 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 152 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 153 #ifndef SLMTU
 154 #define SLMTU           552             /* default MTU */
 155 #endif
 156 #define SLTMAX          1500            /* maximum MTU */
 157 #define SLIP_HIWAT      roundup(50,CBSIZE)
 158 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 159
 160 /*
 161  * SLIP ABORT ESCAPE MECHANISM:
 162  *      (inspired by HAYES modem escape arrangement)
 163  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 164  *      within window time signals a "soft" exit from slip mode by remote end
 165  *      if the IFF_DEBUG flag is on.
 166  */
 167 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 168 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 169 #define ABT_COUNT       3       /* count of escapes for abort */
 170 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 171
 172 static struct sl_softc sl_softc[NSL];
 173
 174 #define FRAME_END               0xc0            /* Frame End */
 175 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 176 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 177 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 178
 179 static int slinit (struct sl_softc *);
 180 static struct mbuf *sl_btom (struct sl_softc *, int);
 181 static timeout_t sl_keepalive;
 182 static timeout_t sl_outfill;
 183 static int      slclose (struct tty *,int);
 184 static int      slinput (int, struct tty *);
 185 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 186 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct ucred *);
 187 static int      slopen (cdev_t, struct tty *);
 188 static int      sloutput (struct ifnet *,
 189             struct mbuf *, struct sockaddr *, struct rtentry *);
 190 static int      slstart (struct tty *);
 191
 192 static struct linesw slipdisc = {
 193         slopen,         slclose,        l_noread,       l_nowrite,
 194         sltioctl,       slinput,        slstart,        ttymodem,
 195         FRAME_END
 196 };
 197
 198 /*
 199  * Called from boot code to establish sl interfaces.
 200  */
 201 static void
 202 slattach(void *dummy)
 203 {
 204         struct sl_softc *sc;
 205         int i = 0;
 206
 207         linesw[SLIPDISC] = slipdisc;
 208
 209         for (sc = sl_softc; i < NSL; sc++) {
 210                 if_initname(&(sc->sc_if), "sl", i++);
 211                 sc->sc_if.if_mtu = SLMTU;
 212                 sc->sc_if.if_flags =
 213 #ifdef SLIP_IFF_OPTS
 214                     SLIP_IFF_OPTS;
 215 #else
 216                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 217 #endif
 218                 sc->sc_if.if_type = IFT_SLIP;
 219                 sc->sc_if.if_ioctl = slioctl;
 220                 sc->sc_if.if_output = sloutput;
 221                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 222                 ifq_set_ready(&sc->sc_if.if_snd);
 223                 sc->sc_fastq.ifq_maxlen = 32;
 224                 sc->sc_if.if_linkmib = sc;
 225                 sc->sc_if.if_linkmiblen = sizeof *sc;
 226                 callout_init(&sc->sc_oftimeout);
 227                 callout_init(&sc->sc_katimeout);
 228                 if_attach(&sc->sc_if, NULL);
 229                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 230         }
 231 }
 232
 233 static int
 234 slinit(struct sl_softc *sc)
 235 {
 236         if (sc->sc_ep == NULL)
 237                 sc->sc_ep = kmalloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 238         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 239         sc->sc_mp = sc->sc_buf;
 240         sl_compress_init(&sc->sc_comp, -1);
 241         return (1);
 242 }
 243
 244 /*
 245  * Line specific open routine.
 246  * Attach the given tty to the first available sl unit.
 247  */
 248 /* ARGSUSED */
 249 static int
 250 slopen(cdev_t dev, struct tty *tp)
 251 {
 252         struct sl_softc *sc;
 253         int nsl;
 254         int error;
 255         struct thread *td = curthread;  /* XXX */
 256
 257         error = priv_check(td, PRIV_ROOT);
 258         if (error)
 259                 return (error);
 260
 261         if (tp->t_line == SLIPDISC)
 262                 return (0);
 263
 264         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 265                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 266                         if (slinit(sc) == 0)
 267                                 return (ENOBUFS);
 268                         tp->t_sc = (caddr_t)sc;
 269                         sc->sc_ttyp = tp;
 270                         sc->sc_if.if_baudrate = tp->t_ospeed;
 271                         ttyflush(tp, FREAD | FWRITE);
 272
 273                         tp->t_line = SLIPDISC;
 274                         /*
 275                          * We don't use t_canq or t_rawq, so reduce their
 276                          * cblock resources to 0.  Reserve enough cblocks
 277                          * for t_outq to guarantee that we can fit a full
 278                          * packet if the SLIP_HIWAT check allows slstart()
 279                          * to loop.  Use the same value for the cblock
 280                          * limit since the reserved blocks should always
 281                          * be enough.  Reserving cblocks probably makes
 282                          * the CLISTRESERVE check unnecessary and wasteful.
 283                          */
 284                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 285                         clist_alloc_cblocks(&tp->t_outq,
 286                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 287                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 288                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 289
 290                         crit_enter();
 291                         if_up(&sc->sc_if);
 292                         crit_exit();
 293                         return (0);
 294                 }
 295         return (ENXIO);
 296 }
 297
 298 /*
 299  * Line specific close routine.
 300  * Detach the tty from the sl unit.
 301  */
 302 static int
 303 slclose(struct tty *tp, int flag)
 304 {
 305         struct sl_softc *sc;
 306
 307         ttyflush(tp, FREAD | FWRITE);
 308         crit_enter();
 309
 310         clist_free_cblocks(&tp->t_outq);
 311         tp->t_line = 0;
 312         sc = (struct sl_softc *)tp->t_sc;
 313         if (sc != NULL) {
 314                 if (sc->sc_outfill) {
 315                         sc->sc_outfill = 0;
 316                         callout_stop(&sc->sc_oftimeout);
 317                 }
 318                 if (sc->sc_keepalive) {
 319                         sc->sc_keepalive = 0;
 320                         callout_stop(&sc->sc_katimeout);
 321                 }
 322                 if_down(&sc->sc_if);
 323                 sc->sc_flags &= SC_STATIC;
 324                 sc->sc_ttyp = NULL;
 325                 tp->t_sc = NULL;
 326                 if (sc->sc_ep) {
 327                         kfree(sc->sc_ep, M_DEVBUF);
 328                         sc->sc_ep = NULL;
 329                 }
 330                 sc->sc_mp = 0;
 331                 sc->sc_buf = 0;
 332         }
 333         crit_exit();
 334         return 0;
 335 }
 336
 337 /*
 338  * Line specific (tty) ioctl routine.
 339  * Provide a way to get the sl unit number.
 340  */
 341 /* ARGSUSED */
 342 static int
 343 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
 344 {
 345         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 346         int nsl;
 347
 348         crit_enter();
 349
 350         switch (cmd) {
 351         case SLIOCGUNIT:
 352                 *(int *)data = sc->sc_if.if_dunit;
 353                 break;
 354
 355         case SLIOCSUNIT:
 356                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 357                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 358                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 359                                     && nc->sc_ttyp == NULL
 360                                    ) {
 361                                         tmpnc = kmalloc(sizeof *tmpnc, M_TEMP,
 362                                                        M_WAITOK);
 363                                         *tmpnc = *nc;
 364                                         *nc = *sc;
 365                                         nc->sc_if = tmpnc->sc_if;
 366                                         tmpnc->sc_if = sc->sc_if;
 367                                         *sc = *tmpnc;
 368                                         kfree(tmpnc, M_TEMP);
 369                                         if (sc->sc_if.if_flags & IFF_UP) {
 370                                                 if_down(&sc->sc_if);
 371                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 372                                                         if_up(&nc->sc_if);
 373                                         } else if (nc->sc_if.if_flags & IFF_UP)
 374                                                 if_down(&nc->sc_if);
 375                                         sc->sc_flags &= ~SC_STATIC;
 376                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 377                                         tp->t_sc = sc = nc;
 378                                         clist_alloc_cblocks(&tp->t_outq,
 379                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 380                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 381                                         sl_compress_init(&sc->sc_comp, -1);
 382                                         goto slfound;
 383                                 }
 384                         }
 385                         crit_exit();
 386                         return (ENXIO);
 387                 }
 388         slfound:
 389                 sc->sc_flags |= SC_STATIC;
 390                 break;
 391
 392         case SLIOCSKEEPAL:
 393                 sc->sc_keepalive = *(u_int *)data * hz;
 394                 if (sc->sc_keepalive) {
 395                         sc->sc_flags |= SC_KEEPALIVE;
 396                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 397                                         sl_keepalive, sc);
 398                 } else {
 399                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 400                                 callout_stop(&sc->sc_katimeout);
 401                                 sc->sc_flags &= ~SC_KEEPALIVE;
 402                         }
 403                 }
 404                 break;
 405
 406         case SLIOCGKEEPAL:
 407                 *(int *)data = sc->sc_keepalive / hz;
 408                 break;
 409
 410         case SLIOCSOUTFILL:
 411                 sc->sc_outfill = *(u_int *)data * hz;
 412                 if (sc->sc_outfill) {
 413                         sc->sc_flags |= SC_OUTWAIT;
 414                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 415                                         sl_outfill, sc);
 416                 } else {
 417                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 418                                 callout_stop(&sc->sc_oftimeout);
 419                                 sc->sc_flags &= ~SC_OUTWAIT;
 420                         }
 421                 }
 422                 break;
 423
 424         case SLIOCGOUTFILL:
 425                 *(int *)data = sc->sc_outfill / hz;
 426                 break;
 427
 428         default:
 429                 crit_exit();
 430                 return (ENOIOCTL);
 431         }
 432         crit_exit();
 433         return (0);
 434 }
 435
 436 /*
 437  * Queue a packet.  Start transmission if not active.
 438  * Compression happens in slstart; if we do it here, IP TOS
 439  * will cause us to not compress "background" packets, because
 440  * ordering gets trashed.  It can be done for all packets in slstart.
 441  */
 442 static int
 443 sloutput_serialized(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 444                     struct rtentry *rtp)
 445 {
 446         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 447         struct ip *ip;
 448         int error;
 449         struct altq_pktattr pktattr;
 450
 451         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 452
 453         /*
 454          * `Cannot happen' (see slioctl).  Someday we will extend
 455          * the line protocol to support other address families.
 456          */
 457         if (dst->sa_family != AF_INET) {
 458                 kprintf("%s: af%d not supported\n", sc->sc_if.if_xname,
 459                         dst->sa_family);
 460                 m_freem(m);
 461                 sc->sc_if.if_noproto++;
 462                 return (EAFNOSUPPORT);
 463         }
 464
 465         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 466                 m_freem(m);
 467                 return (ENETDOWN);
 468         }
 469         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 470                 m_freem(m);
 471                 return (EHOSTUNREACH);
 472         }
 473         ip = mtod(m, struct ip *);
 474         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 475                 m_freem(m);
 476                 return (ENETRESET);             /* XXX ? */
 477         }
 478
 479         crit_enter();
 480
 481         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 482                 if (IF_QFULL(&sc->sc_fastq)) {
 483                         IF_DROP(&sc->sc_fastq);
 484                         m_freem(m);
 485                         error = ENOBUFS;
 486                 } else {
 487                         IF_ENQUEUE(&sc->sc_fastq, m);
 488                         error = 0;
 489                 }
 490         } else {
 491                 error = ifq_enqueue(&sc->sc_if.if_snd, m, &pktattr);
 492         }
 493         if (error) {
 494                 sc->sc_if.if_oerrors++;
 495                 crit_exit();
 496                 return (error);
 497         }
 498         if (sc->sc_ttyp->t_outq.c_cc == 0)
 499                 slstart(sc->sc_ttyp);
 500         crit_exit();
 501         return (0);
 502 }
 503
 504 static int
 505 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 506          struct rtentry *rtp)
 507 {
 508         int error;
 509
 510         lwkt_serialize_enter(ifp->if_serializer);
 511         error = sloutput_serialized(ifp, m, dst, rtp);
 512         lwkt_serialize_exit(ifp->if_serializer);
 513
 514         return error;
 515 }
 516
 517 /*
 518  * Start output on interface.  Get another datagram
 519  * to send from the interface queue and map it to
 520  * the interface before starting output.
 521  */
 522 static int
 523 slstart(struct tty *tp)
 524 {
 525         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 526         struct mbuf *m;
 527         u_char *cp;
 528         struct ip *ip;
 529         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 530         int len = 0;
 531
 532         for (;;) {
 533                 /*
 534                  * Call output process whether or not there is more in the
 535                  * output queue.  We are being called in lieu of ttstart
 536                  * and must do what it would.
 537                  */
 538                 (*tp->t_oproc)(tp);
 539
 540                 if (tp->t_outq.c_cc != 0) {
 541                         if (sc != NULL)
 542                                 sc->sc_flags &= ~SC_OUTWAIT;
 543                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 544                                 return 0;
 545                 }
 546
 547                 /*
 548                  * This happens briefly when the line shuts down.
 549                  */
 550                 if (sc == NULL)
 551                         return 0;
 552
 553                 /*
 554                  * Get a packet and send it to the interface.
 555                  */
 556                 crit_enter();
 557                 IF_DEQUEUE(&sc->sc_fastq, m);
 558                 if (m)
 559                         sc->sc_if.if_omcasts++;         /* XXX */
 560                 else
 561                         m = ifq_dequeue(&sc->sc_if.if_snd, NULL);
 562                 crit_exit();
 563                 if (m == NULL)
 564                         return 0;
 565
 566                 /*
 567                  * We do the header compression here rather than in sloutput
 568                  * because the packets will be out of order if we are using TOS
 569                  * queueing, and the connection id compression will get
 570                  * munged when this happens.
 571                  */
 572                 if (sc->sc_if.if_bpf) {
 573                         /*
 574                          * We need to save the TCP/IP header before it's
 575                          * compressed.  To avoid complicated code, we just
 576                          * copy the entire packet into a stack buffer (since
 577                          * this is a serial line, packets should be short
 578                          * and/or the copy should be negligible cost compared
 579                          * to the packet transmission time).
 580                          */
 581                         struct mbuf *m1 = m;
 582                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 583
 584                         len = 0;
 585                         do {
 586                                 int mlen = m1->m_len;
 587
 588                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 589                                 cp += mlen;
 590                                 len += mlen;
 591                         } while ((m1 = m1->m_next) != NULL);
 592                 }
 593                 ip = mtod(m, struct ip *);
 594                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 595                         if (sc->sc_if.if_flags & SC_COMPRESS)
 596                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 597                                     &sc->sc_comp, 1);
 598                 }
 599                 if (sc->sc_if.if_bpf) {
 600                         /*
 601                          * Put the SLIP pseudo-"link header" in place.  The
 602                          * compressed header is now at the beginning of the
 603                          * mbuf.
 604                          */
 605                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 606                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 607                         bpf_tap(sc->sc_if.if_bpf, bpfbuf, len + SLIP_HDRLEN);
 608                 }
 609
 610                 /*
 611                  * If system is getting low on clists, just flush our
 612                  * output queue (if the stuff was important, it'll get
 613                  * retransmitted). Note that SLTMAX is used instead of
 614                  * the current if_mtu setting because connections that
 615                  * have already been established still use the original
 616                  * (possibly larger) mss.
 617                  */
 618                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 619                         m_freem(m);
 620                         sc->sc_if.if_collisions++;
 621                         continue;
 622                 }
 623
 624                 sc->sc_flags &= ~SC_OUTWAIT;
 625                 /*
 626                  * The extra FRAME_END will start up a new packet, and thus
 627                  * will flush any accumulated garbage.  We do this whenever
 628                  * the line may have been idle for some time.
 629                  */
 630                 if (tp->t_outq.c_cc == 0) {
 631                         ++sc->sc_if.if_obytes;
 632                         clist_putc(FRAME_END, &tp->t_outq);
 633                 }
 634
 635                 while (m) {
 636                         u_char *ep;
 637
 638                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 639                         while (cp < ep) {
 640                                 /*
 641                                  * Find out how many bytes in the string we can
 642                                  * handle without doing something special.
 643                                  */
 644                                 u_char *bp = cp;
 645
 646                                 while (cp < ep) {
 647                                         switch (*cp++) {
 648                                         case FRAME_ESCAPE:
 649                                         case FRAME_END:
 650                                                 --cp;
 651                                                 goto out;
 652                                         }
 653                                 }
 654                                 out:
 655                                 if (cp > bp) {
 656                                         /*
 657                                          * Put n characters at once
 658                                          * into the tty output queue.
 659                                          */
 660                                         if (b_to_q((char *)bp, cp - bp,
 661                                             &tp->t_outq))
 662                                                 break;
 663                                         sc->sc_if.if_obytes += cp - bp;
 664                                 }
 665                                 /*
 666                                  * If there are characters left in the mbuf,
 667                                  * the first one must be special..
 668                                  * Put it out in a different form.
 669                                  */
 670                                 if (cp < ep) {
 671                                         if (clist_putc(FRAME_ESCAPE, &tp->t_outq))
 672                                                 break;
 673                                         if (clist_putc(*cp++ == FRAME_ESCAPE ?
 674                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 675                                            &tp->t_outq)) {
 676                                                 clist_unputc(&tp->t_outq);
 677                                                 break;
 678                                         }
 679                                         sc->sc_if.if_obytes += 2;
 680                                 }
 681                         }
 682                         m = m_free(m);
 683                 }
 684
 685                 if (clist_putc(FRAME_END, &tp->t_outq)) {
 686                         /*
 687                          * Not enough room.  Remove a char to make room
 688                          * and end the packet normally.
 689                          * If you get many collisions (more than one or two
 690                          * a day) you probably do not have enough clists
 691                          * and you should increase "nclist" in param.c.
 692                          */
 693                         clist_unputc(&tp->t_outq);
 694                         clist_putc(FRAME_END, &tp->t_outq);
 695                         sc->sc_if.if_collisions++;
 696                 } else {
 697                         ++sc->sc_if.if_obytes;
 698                         sc->sc_if.if_opackets++;
 699                 }
 700         }
 701         return 0;
 702 }
 703
 704 /*
 705  * Copy data buffer to mbuf chain; add ifnet pointer.
 706  */
 707 static struct mbuf *
 708 sl_btom(struct sl_softc *sc, int len)
 709 {
 710         struct mbuf *m;
 711
 712         if (len >= MCLBYTES)
 713                 return (NULL);
 714
 715         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 716         if (m == NULL)
 717                 return (NULL);
 718
 719         /*
 720          * If we have more than MHLEN bytes, it's cheaper to
 721          * queue the cluster we just filled & allocate a new one
 722          * for the input buffer.  Otherwise, fill the mbuf we
 723          * allocated above.  Note that code in the input routine
 724          * guarantees that packet will fit in a cluster.
 725          */
 726         if (len >= MHLEN) {
 727                 MCLGET(m, MB_DONTWAIT);
 728                 if ((m->m_flags & M_EXT) == 0) {
 729                         /*
 730                          * we couldn't get a cluster - if memory's this
 731                          * low, it's time to start dropping packets.
 732                          */
 733                         m_free(m);
 734                         return (NULL);
 735                 }
 736         }
 737         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 738         m->m_len = len;
 739         m->m_pkthdr.len = len;
 740         m->m_pkthdr.rcvif = &sc->sc_if;
 741         return (m);
 742 }
 743
 744 /*
 745  * tty interface receiver interrupt.
 746  */
 747 static int
 748 slinput(int c, struct tty *tp)
 749 {
 750         struct sl_softc *sc;
 751         struct mbuf *m;
 752         int len;
 753         u_char chdr[CHDR_LEN];
 754
 755         tk_nin++;
 756         sc = (struct sl_softc *)tp->t_sc;
 757         if (sc == NULL)
 758                 return 0;
 759         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 760                 sc->sc_flags |= SC_ERROR;
 761                 return 0;
 762         }
 763         c &= TTY_CHARMASK;
 764
 765         ++sc->sc_if.if_ibytes;
 766
 767         if (sc->sc_if.if_flags & IFF_DEBUG) {
 768                 if (c == ABT_ESC) {
 769                         /*
 770                          * If we have a previous abort, see whether
 771                          * this one is within the time limit.
 772                          */
 773                         if (sc->sc_abortcount &&
 774                             time_second >= sc->sc_starttime + ABT_WINDOW)
 775                                 sc->sc_abortcount = 0;
 776                         /*
 777                          * If we see an abort after "idle" time, count it;
 778                          * record when the first abort escape arrived.
 779                          */
 780                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 781                                 if (++sc->sc_abortcount == 1)
 782                                         sc->sc_starttime = time_second;
 783                                 if (sc->sc_abortcount >= ABT_COUNT) {
 784                                         slclose(tp,0);
 785                                         return 0;
 786                                 }
 787                         }
 788                 } else
 789                         sc->sc_abortcount = 0;
 790                 sc->sc_lasttime = time_second;
 791         }
 792
 793         switch (c) {
 794
 795         case TRANS_FRAME_ESCAPE:
 796                 if (sc->sc_escape)
 797                         c = FRAME_ESCAPE;
 798                 break;
 799
 800         case TRANS_FRAME_END:
 801                 if (sc->sc_escape)
 802                         c = FRAME_END;
 803                 break;
 804
 805         case FRAME_ESCAPE:
 806                 sc->sc_escape = 1;
 807                 return 0;
 808
 809         case FRAME_END:
 810                 sc->sc_flags &= ~SC_KEEPALIVE;
 811                 if(sc->sc_flags & SC_ERROR) {
 812                         sc->sc_flags &= ~SC_ERROR;
 813                         goto newpack;
 814                 }
 815                 len = sc->sc_mp - sc->sc_buf;
 816                 if (len < 3)
 817                         /* less than min length packet - ignore */
 818                         goto newpack;
 819
 820                 if (sc->sc_if.if_bpf) {
 821                         /*
 822                          * Save the compressed header, so we
 823                          * can tack it on later.  Note that we
 824                          * will end up copying garbage in some
 825                          * cases but this is okay.  We remember
 826                          * where the buffer started so we can
 827                          * compute the new header length.
 828                          */
 829                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 830                 }
 831
 832                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 833                         if (c & 0x80)
 834                                 c = TYPE_COMPRESSED_TCP;
 835                         else if (c == TYPE_UNCOMPRESSED_TCP)
 836                                 *sc->sc_buf &= 0x4f; /* XXX */
 837                         /*
 838                          * We've got something that's not an IP packet.
 839                          * If compression is enabled, try to decompress it.
 840                          * Otherwise, if `auto-enable' compression is on and
 841                          * it's a reasonable packet, decompress it and then
 842                          * enable compression.  Otherwise, drop it.
 843                          */
 844                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 845                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 846                                                         (u_int)c, &sc->sc_comp);
 847                                 if (len <= 0)
 848                                         goto error;
 849                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 850                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 851                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 852                                                         (u_int)c, &sc->sc_comp);
 853                                 if (len <= 0)
 854                                         goto error;
 855                                 sc->sc_if.if_flags |= SC_COMPRESS;
 856                         } else
 857                                 goto error;
 858                 }
 859                 if (sc->sc_if.if_bpf) {
 860                         /*
 861                          * Put the SLIP pseudo-"link header" in place.
 862                          * We couldn't do this any earlier since
 863                          * decompression probably moved the buffer
 864                          * pointer.  Then, invoke BPF.
 865                          */
 866                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 867
 868                         hp[SLX_DIR] = SLIPDIR_IN;
 869                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 870                         bpf_tap(sc->sc_if.if_bpf, hp, len + SLIP_HDRLEN);
 871                 }
 872                 m = sl_btom(sc, len);
 873                 if (m == NULL)
 874                         goto error;
 875
 876                 sc->sc_if.if_ipackets++;
 877
 878                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 879                         m_freem(m);
 880                         goto newpack;
 881                 }
 882
 883                 if (netisr_queue(NETISR_IP, m)) {
 884                         sc->sc_if.if_ierrors++;
 885                         sc->sc_if.if_iqdrops++;
 886                 }
 887
 888                 goto newpack;
 889         }
 890         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 891                 *sc->sc_mp++ = c;
 892                 sc->sc_escape = 0;
 893                 return 0;
 894         }
 895
 896         /* can't put lower; would miss an extra frame */
 897         sc->sc_flags |= SC_ERROR;
 898
 899 error:
 900         sc->sc_if.if_ierrors++;
 901 newpack:
 902         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 903         sc->sc_escape = 0;
 904         return 0;
 905 }
 906
 907 /*
 908  * Process an ioctl request.
 909  */
 910 static int
 911 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 912 {
 913         struct ifaddr *ifa = (struct ifaddr *)data;
 914         struct ifreq *ifr = (struct ifreq *)data;
 915         int error = 0;
 916
 917         crit_enter();
 918
 919         switch (cmd) {
 920
 921         case SIOCSIFFLAGS:
 922                 /*
 923                  * if.c will set the interface up even if we
 924                  * don't want it to.
 925                  */
 926                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 927                         ifp->if_flags &= ~IFF_UP;
 928                 }
 929                 break;
 930         case SIOCSIFADDR:
 931                 /*
 932                  * This is "historical" - set the interface up when
 933                  * setting the address.
 934                  */
 935                 if (ifa->ifa_addr->sa_family == AF_INET) {
 936                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 937                                 ifp->if_flags |= IFF_UP;
 938                 } else {
 939                         error = EAFNOSUPPORT;
 940                 }
 941                 break;
 942
 943         case SIOCSIFDSTADDR:
 944                 if (ifa->ifa_addr->sa_family != AF_INET)
 945                         error = EAFNOSUPPORT;
 946                 break;
 947
 948         case SIOCADDMULTI:
 949         case SIOCDELMULTI:
 950                 break;
 951
 952         case SIOCSIFMTU:
 953                 /*
 954                  * Set the interface MTU.
 955                  */
 956                 if (ifr->ifr_mtu > SLTMAX)
 957                         error = EINVAL;
 958                 else {
 959                         struct tty *tp;
 960
 961                         ifp->if_mtu = ifr->ifr_mtu;
 962                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 963                         if (tp != NULL)
 964                                 clist_alloc_cblocks(&tp->t_outq,
 965                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 966                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 967                 }
 968                 break;
 969
 970         default:
 971                 error = EINVAL;
 972         }
 973
 974         crit_exit();
 975         return (error);
 976 }
 977
 978 static void
 979 sl_keepalive(void *chan)
 980 {
 981         struct sl_softc *sc = chan;
 982
 983         if (sc->sc_keepalive) {
 984                 if (sc->sc_flags & SC_KEEPALIVE)
 985                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 986                 else
 987                         sc->sc_flags |= SC_KEEPALIVE;
 988                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 989                                 sl_keepalive, sc);
 990         } else {
 991                 sc->sc_flags &= ~SC_KEEPALIVE;
 992         }
 993 }
 994
 995 static void
 996 sl_outfill(void *chan)
 997 {
 998         struct sl_softc *sc = chan;
 999         struct tty *tp = sc->sc_ttyp;
1000
1001         if (sc->sc_outfill && tp != NULL) {
1002                 if (sc->sc_flags & SC_OUTWAIT) {
1003                         crit_enter();
1004                         ++sc->sc_if.if_obytes;
1005                         clist_putc(FRAME_END, &tp->t_outq);
1006                         (*tp->t_oproc)(tp);
1007                         crit_exit();
1008                 } else
1009                         sc->sc_flags |= SC_OUTWAIT;
1010                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1011                                 sl_outfill, sc);
1012         } else {
1013                 sc->sc_flags &= ~SC_OUTWAIT;
1014         }
1015 }