sys/net/sl/if_sl.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1987, 1989, 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)if_sl.c     8.6 (Berkeley) 2/1/94
  32  * $FreeBSD: src/sys/net/if_sl.c,v 1.84.2.2 2002/02/13 00:43:10 dillon Exp $
  33  */
  34
  35 /*
  36  * Serial Line interface
  37  *
  38  * Rick Adams
  39  * Center for Seismic Studies
  40  * 1300 N 17th Street, Suite 1450
  41  * Arlington, Virginia 22209
  42  * (703)276-7900
  43  * rick@seismo.ARPA
  44  * seismo!rick
  45  *
  46  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  47  * N.B.: this belongs in netinet, not net, the way it stands now.
  48  * Should have a link-layer type designation, but wouldn't be
  49  * backwards-compatible.
  50  *
  51  * Converted to 4.3BSD Beta by Chris Torek.
  52  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  53  * W. Jolitz added slip abort.
  54  *
  55  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  56  * Added priority queuing for "interactive" traffic; hooks for TCP
  57  * header compression; ICMP filtering (at 2400 baud, some cretin
  58  * pinging you can use up all your bandwidth).  Made low clist behavior
  59  * more robust and slightly less likely to hang serial line.
  60  * Sped up a bunch of things.
  61  */
  62
  63 #include "use_sl.h"
  64
  65 #include "opt_inet.h"
  66 #if !defined(KLD_MODULE)
  67 #include "opt_slip.h"
  68 #endif
  69 #include <sys/param.h>
  70 #include <sys/systm.h>
  71 #include <sys/proc.h>
  72 #include <sys/priv.h>
  73 #include <sys/malloc.h>
  74 #include <sys/mbuf.h>
  75 #include <sys/dkstat.h>
  76 #include <sys/socket.h>
  77 #include <sys/sockio.h>
  78 #include <sys/fcntl.h>
  79 #include <sys/signalvar.h>
  80 #include <sys/tty.h>
  81 #include <sys/clist.h>
  82 #include <sys/kernel.h>
  83 #include <sys/conf.h>
  84 #include <sys/thread2.h>
  85
  86 #include <net/if.h>
  87 #include <net/if_types.h>
  88 #include <net/ifq_var.h>
  89 #include <net/netisr.h>
  90
  91 #if INET
  92 #include <netinet/in.h>
  93 #include <netinet/in_systm.h>
  94 #include <netinet/in_var.h>
  95 #include <netinet/ip.h>
  96 #else
  97 #error "Huh? Slip without inet?"
  98 #endif
  99
 100 #include <net/slcompress.h>
 101 #include "if_slvar.h"
 102 #include <net/slip.h>
 103
 104 #include <net/bpf.h>
 105
 106 static void slattach (void *);
 107 PSEUDO_SET(slattach, if_sl);
 108
 109 /*
 110  * SLRMAX is a hard limit on input packet size.  To simplify the code
 111  * and improve performance, we require that packets fit in an mbuf
 112  * cluster, and if we get a compressed packet, there's enough extra
 113  * room to expand the header into a max length tcp/ip header (128
 114  * bytes).  So, SLRMAX can be at most
 115  *      MCLBYTES - 128
 116  *
 117  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 118  * small enough so that interactive use doesn't suffer, but large
 119  * enough to provide good performance. 552 is a good choice for SLMTU
 120  * because it is high enough to not fragment TCP packets being routed
 121  * through this host. Packet fragmentation is bad with SLIP because
 122  * fragment headers aren't compressed. The previous assumptions about
 123  * the best MTU value don't really hold when using modern modems with
 124  * BTLZ data compression because the modem buffers play a much larger
 125  * role in interactive performance than the MTU. The MTU can be changed
 126  * at any time to suit the specific environment with ifconfig(8), and
 127  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 128  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 129  * handles this better).
 130  *
 131  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 132  * of us (i.e., in clists waiting to be picked up by the tty output
 133  * interrupt).  If we queue a lot of data downstream, it's immune to
 134  * our t.o.s. queuing.
 135  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 136  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 137  * wait is dependent on the ftp window size but that's typically
 138  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 139  * the cost (in idle time on the wire) of the tty driver running
 140  * off the end of its clists & having to call back slstart for a
 141  * new packet.  For a tty interface with any buffering at all, this
 142  * cost will be zero.  Even with a totally brain dead interface (like
 143  * the one on a typical workstation), the cost will be <= 1 character
 144  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 145  * at most 1% while maintaining good interactive response.
 146  */
 147 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 148 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 149 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 150 #ifndef SLMTU
 151 #define SLMTU           552             /* default MTU */
 152 #endif
 153 #define SLTMAX          1500            /* maximum MTU */
 154 #define SLIP_HIWAT      roundup(50,CBSIZE)
 155 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 156
 157 /*
 158  * SLIP ABORT ESCAPE MECHANISM:
 159  *      (inspired by HAYES modem escape arrangement)
 160  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 161  *      within window time signals a "soft" exit from slip mode by remote end
 162  *      if the IFF_DEBUG flag is on.
 163  */
 164 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 165 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 166 #define ABT_COUNT       3       /* count of escapes for abort */
 167 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 168
 169 static struct sl_softc sl_softc[NSL];
 170
 171 #define FRAME_END               0xc0            /* Frame End */
 172 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 173 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 174 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 175
 176 static int slinit (struct sl_softc *);
 177 static struct mbuf *sl_btom (struct sl_softc *, int);
 178 static timeout_t sl_keepalive;
 179 static timeout_t sl_outfill;
 180 static int      slclose (struct tty *,int);
 181 static int      slinput (int, struct tty *);
 182 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 183 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct ucred *);
 184 static int      slopen (cdev_t, struct tty *);
 185 static int      sloutput (struct ifnet *,
 186             struct mbuf *, struct sockaddr *, struct rtentry *);
 187 static int      slstart (struct tty *);
 188
 189 static struct linesw slipdisc = {
 190         slopen,         slclose,        l_noread,       l_nowrite,
 191         sltioctl,       slinput,        slstart,        ttymodem,
 192         FRAME_END
 193 };
 194
 195 /*
 196  * Called from boot code to establish sl interfaces.
 197  */
 198 static void
 199 slattach(void *dummy)
 200 {
 201         struct sl_softc *sc;
 202         int i = 0;
 203
 204         lwkt_gettoken(&tty_token);
 205         linesw[SLIPDISC] = slipdisc;
 206
 207         for (sc = sl_softc; i < NSL; sc++) {
 208                 if_initname(&(sc->sc_if), "sl", i++);
 209                 sc->sc_if.if_mtu = SLMTU;
 210                 sc->sc_if.if_flags =
 211 #ifdef SLIP_IFF_OPTS
 212                     SLIP_IFF_OPTS;
 213 #else
 214                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 215 #endif
 216                 sc->sc_if.if_type = IFT_SLIP;
 217                 sc->sc_if.if_ioctl = slioctl;
 218                 sc->sc_if.if_output = sloutput;
 219                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 220                 ifq_set_ready(&sc->sc_if.if_snd);
 221                 sc->sc_fastq.ifq_maxlen = 32;
 222                 sc->sc_if.if_linkmib = sc;
 223                 sc->sc_if.if_linkmiblen = sizeof *sc;
 224                 callout_init_mp(&sc->sc_oftimeout);
 225                 callout_init_mp(&sc->sc_katimeout);
 226                 if_attach(&sc->sc_if, NULL);
 227                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 228         }
 229         lwkt_reltoken(&tty_token);
 230 }
 231
 232 static int
 233 slinit(struct sl_softc *sc)
 234 {
 235         lwkt_gettoken(&tty_token);
 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         lwkt_reltoken(&tty_token);
 242         return (1);
 243 }
 244
 245 /*
 246  * Line specific open routine.
 247  * Attach the given tty to the first available sl unit.
 248  */
 249 /* ARGSUSED */
 250 static int
 251 slopen(cdev_t dev, struct tty *tp)
 252 {
 253         struct sl_softc *sc;
 254         int nsl;
 255         int error;
 256         struct thread *td = curthread;  /* XXX */
 257
 258         error = priv_check(td, PRIV_ROOT);
 259         if (error)
 260                 return (error);
 261
 262         lwkt_gettoken(&tty_token);
 263         if (tp->t_line == SLIPDISC) {
 264                 lwkt_reltoken(&tty_token);
 265                 return (0);
 266         }
 267
 268         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 269                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 270                         if (slinit(sc) == 0) {
 271                                 lwkt_reltoken(&tty_token);
 272                                 return (ENOBUFS);
 273                         }
 274                         tp->t_sc = (caddr_t)sc;
 275                         sc->sc_ttyp = tp;
 276                         sc->sc_if.if_baudrate = tp->t_ospeed;
 277                         ttyflush(tp, FREAD | FWRITE);
 278
 279                         tp->t_line = SLIPDISC;
 280                         /*
 281                          * We don't use t_canq or t_rawq, so reduce their
 282                          * cblock resources to 0.  Reserve enough cblocks
 283                          * for t_outq to guarantee that we can fit a full
 284                          * packet if the SLIP_HIWAT check allows slstart()
 285                          * to loop.  Use the same value for the cblock
 286                          * limit since the reserved blocks should always
 287                          * be enough.  Reserving cblocks probably makes
 288                          * the CLISTRESERVE check unnecessary and wasteful.
 289                          */
 290                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 291                         clist_alloc_cblocks(&tp->t_outq,
 292                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 293                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 294                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 295
 296                         crit_enter();
 297                         if_up(&sc->sc_if);
 298                         crit_exit();
 299                         lwkt_reltoken(&tty_token);
 300                         return (0);
 301                 }
 302         lwkt_reltoken(&tty_token);
 303         return (ENXIO);
 304 }
 305
 306 /*
 307  * Line specific close routine.
 308  * Detach the tty from the sl unit.
 309  */
 310 static int
 311 slclose(struct tty *tp, int flag)
 312 {
 313         struct sl_softc *sc;
 314
 315         lwkt_gettoken(&tty_token);
 316         ttyflush(tp, FREAD | FWRITE);
 317         crit_enter();
 318
 319         clist_free_cblocks(&tp->t_outq);
 320         tp->t_line = 0;
 321         sc = (struct sl_softc *)tp->t_sc;
 322         if (sc != NULL) {
 323                 if (sc->sc_outfill) {
 324                         sc->sc_outfill = 0;
 325                         callout_stop(&sc->sc_oftimeout);
 326                 }
 327                 if (sc->sc_keepalive) {
 328                         sc->sc_keepalive = 0;
 329                         callout_stop(&sc->sc_katimeout);
 330                 }
 331                 if_down(&sc->sc_if);
 332                 sc->sc_flags &= SC_STATIC;
 333                 sc->sc_ttyp = NULL;
 334                 tp->t_sc = NULL;
 335                 if (sc->sc_ep) {
 336                         kfree(sc->sc_ep, M_DEVBUF);
 337                         sc->sc_ep = NULL;
 338                 }
 339                 sc->sc_mp = 0;
 340                 sc->sc_buf = 0;
 341         }
 342         crit_exit();
 343         lwkt_reltoken(&tty_token);
 344         return 0;
 345 }
 346
 347 /*
 348  * Line specific (tty) ioctl routine.
 349  * Provide a way to get the sl unit number.
 350  */
 351 /* ARGSUSED */
 352 static int
 353 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
 354 {
 355         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 356         int nsl;
 357
 358         crit_enter();
 359         lwkt_gettoken(&tty_token);
 360
 361         switch (cmd) {
 362         case SLIOCGUNIT:
 363                 *(int *)data = sc->sc_if.if_dunit;
 364                 break;
 365
 366         case SLIOCSUNIT:
 367                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 368                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 369                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 370                                     && nc->sc_ttyp == NULL
 371                                    ) {
 372                                         tmpnc = kmalloc(sizeof *tmpnc, M_TEMP,
 373                                                        M_WAITOK);
 374                                         *tmpnc = *nc;
 375                                         *nc = *sc;
 376                                         nc->sc_if = tmpnc->sc_if;
 377                                         tmpnc->sc_if = sc->sc_if;
 378                                         *sc = *tmpnc;
 379                                         kfree(tmpnc, M_TEMP);
 380                                         if (sc->sc_if.if_flags & IFF_UP) {
 381                                                 if_down(&sc->sc_if);
 382                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 383                                                         if_up(&nc->sc_if);
 384                                         } else if (nc->sc_if.if_flags & IFF_UP)
 385                                                 if_down(&nc->sc_if);
 386                                         sc->sc_flags &= ~SC_STATIC;
 387                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 388                                         tp->t_sc = sc = nc;
 389                                         clist_alloc_cblocks(&tp->t_outq,
 390                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 391                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 392                                         sl_compress_init(&sc->sc_comp, -1);
 393                                         goto slfound;
 394                                 }
 395                         }
 396                         lwkt_reltoken(&tty_token);
 397                         crit_exit();
 398                         return (ENXIO);
 399                 }
 400         slfound:
 401                 sc->sc_flags |= SC_STATIC;
 402                 break;
 403
 404         case SLIOCSKEEPAL:
 405                 sc->sc_keepalive = *(u_int *)data * hz;
 406                 if (sc->sc_keepalive) {
 407                         sc->sc_flags |= SC_KEEPALIVE;
 408                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 409                                         sl_keepalive, sc);
 410                 } else {
 411                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 412                                 callout_stop(&sc->sc_katimeout);
 413                                 sc->sc_flags &= ~SC_KEEPALIVE;
 414                         }
 415                 }
 416                 break;
 417
 418         case SLIOCGKEEPAL:
 419                 *(int *)data = sc->sc_keepalive / hz;
 420                 break;
 421
 422         case SLIOCSOUTFILL:
 423                 sc->sc_outfill = *(u_int *)data * hz;
 424                 if (sc->sc_outfill) {
 425                         sc->sc_flags |= SC_OUTWAIT;
 426                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 427                                         sl_outfill, sc);
 428                 } else {
 429                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 430                                 callout_stop(&sc->sc_oftimeout);
 431                                 sc->sc_flags &= ~SC_OUTWAIT;
 432                         }
 433                 }
 434                 break;
 435
 436         case SLIOCGOUTFILL:
 437                 *(int *)data = sc->sc_outfill / hz;
 438                 break;
 439
 440         default:
 441                 lwkt_reltoken(&tty_token);
 442                 crit_exit();
 443                 return (ENOIOCTL);
 444         }
 445         lwkt_reltoken(&tty_token);
 446         crit_exit();
 447         return (0);
 448 }
 449
 450 /*
 451  * Queue a packet.  Start transmission if not active.
 452  * Compression happens in slstart; if we do it here, IP TOS
 453  * will cause us to not compress "background" packets, because
 454  * ordering gets trashed.  It can be done for all packets in slstart.
 455  */
 456 static int
 457 sloutput_serialized(struct ifnet *ifp, struct ifaltq_subque *ifsq,
 458     struct mbuf *m, struct sockaddr *dst, struct rtentry *rtp)
 459 {
 460         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 461         struct ip *ip;
 462         int error;
 463         struct altq_pktattr pktattr;
 464
 465         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 466
 467         /*
 468          * `Cannot happen' (see slioctl).  Someday we will extend
 469          * the line protocol to support other address families.
 470          */
 471         if (dst->sa_family != AF_INET) {
 472                 kprintf("%s: af%d not supported\n", sc->sc_if.if_xname,
 473                         dst->sa_family);
 474                 m_freem(m);
 475                 IFNET_STAT_INC(&sc->sc_if, noproto, 1);
 476                 return (EAFNOSUPPORT);
 477         }
 478
 479         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 480                 m_freem(m);
 481                 return (ENETDOWN);
 482         }
 483         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 484                 m_freem(m);
 485                 return (EHOSTUNREACH);
 486         }
 487         ip = mtod(m, struct ip *);
 488         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 489                 m_freem(m);
 490                 return (ENETRESET);             /* XXX ? */
 491         }
 492
 493         crit_enter();
 494
 495         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 496                 if (IF_QFULL(&sc->sc_fastq)) {
 497                         IF_DROP(&sc->sc_fastq);
 498                         m_freem(m);
 499                         error = ENOBUFS;
 500                 } else {
 501                         IF_ENQUEUE(&sc->sc_fastq, m);
 502                         error = 0;
 503                 }
 504         } else {
 505                 error = ifsq_enqueue(ifsq, m, &pktattr);
 506         }
 507         if (error) {
 508                 IFNET_STAT_INC(&sc->sc_if, oerrors, 1);
 509                 crit_exit();
 510                 return (error);
 511         }
 512         if (sc->sc_ttyp->t_outq.c_cc == 0)
 513                 slstart(sc->sc_ttyp);
 514         crit_exit();
 515         return (0);
 516 }
 517
 518 static int
 519 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 520          struct rtentry *rtp)
 521 {
 522         struct ifaltq_subque *ifsq = ifq_get_subq_default(&ifp->if_snd);
 523         int error;
 524
 525         ifsq_serialize_hw(ifsq);
 526         error = sloutput_serialized(ifp, ifsq, m, dst, rtp);
 527         ifsq_deserialize_hw(ifsq);
 528
 529         return error;
 530 }
 531
 532 /*
 533  * Start output on interface.  Get another datagram
 534  * to send from the interface queue and map it to
 535  * the interface before starting output.
 536  */
 537 static int
 538 slstart(struct tty *tp)
 539 {
 540         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 541         struct ifaltq_subque *ifsq = ifq_get_subq_default(&sc->sc_if.if_snd);
 542         struct mbuf *m;
 543         u_char *cp;
 544         struct ip *ip;
 545         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 546         int len = 0;
 547
 548         lwkt_gettoken(&tty_token);
 549         for (;;) {
 550                 /*
 551                  * Call output process whether or not there is more in the
 552                  * output queue.  We are being called in lieu of ttstart
 553                  * and must do what it would.
 554                  */
 555                 (*tp->t_oproc)(tp);
 556
 557                 if (tp->t_outq.c_cc != 0) {
 558                         if (sc != NULL)
 559                                 sc->sc_flags &= ~SC_OUTWAIT;
 560                         if (tp->t_outq.c_cc > SLIP_HIWAT) {
 561                                 lwkt_reltoken(&tty_token);
 562                                 return 0;
 563                         }
 564                 }
 565
 566                 /*
 567                  * This happens briefly when the line shuts down.
 568                  */
 569                 if (sc == NULL) {
 570                         lwkt_reltoken(&tty_token);
 571                         return 0;
 572                 }
 573
 574                 /*
 575                  * Get a packet and send it to the interface.
 576                  */
 577                 crit_enter();
 578                 IF_DEQUEUE(&sc->sc_fastq, m);
 579                 if (m)
 580                         IFNET_STAT_INC(&sc->sc_if, omcasts, 1); /* XXX */
 581                 else
 582                         m = ifsq_dequeue(ifsq);
 583                 crit_exit();
 584                 if (m == NULL) {
 585                         lwkt_reltoken(&tty_token);
 586                         return 0;
 587                 }
 588
 589                 /*
 590                  * We do the header compression here rather than in sloutput
 591                  * because the packets will be out of order if we are using TOS
 592                  * queueing, and the connection id compression will get
 593                  * munged when this happens.
 594                  */
 595                 if (sc->sc_if.if_bpf) {
 596                         /*
 597                          * We need to save the TCP/IP header before it's
 598                          * compressed.  To avoid complicated code, we just
 599                          * copy the entire packet into a stack buffer (since
 600                          * this is a serial line, packets should be short
 601                          * and/or the copy should be negligible cost compared
 602                          * to the packet transmission time).
 603                          */
 604                         struct mbuf *m1 = m;
 605                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 606
 607                         len = 0;
 608                         do {
 609                                 int mlen = m1->m_len;
 610
 611                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 612                                 cp += mlen;
 613                                 len += mlen;
 614                         } while ((m1 = m1->m_next) != NULL);
 615                 }
 616                 ip = mtod(m, struct ip *);
 617                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 618                         if (sc->sc_if.if_flags & SC_COMPRESS)
 619                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 620                                     &sc->sc_comp, 1);
 621                 }
 622                 if (sc->sc_if.if_bpf) {
 623                         bpf_gettoken();
 624
 625                         if (sc->sc_if.if_bpf) {
 626                                 /*
 627                                  * Put the SLIP pseudo-"link header" in place.
 628                                  * The compressed header is now at the
 629                                  * beginning of the mbuf.
 630                                  */
 631                                 bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 632                                 bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR],
 633                                     CHDR_LEN);
 634                                 bpf_tap(sc->sc_if.if_bpf, bpfbuf,
 635                                     len + SLIP_HDRLEN);
 636                         }
 637
 638                         bpf_reltoken();
 639                 }
 640
 641                 /*
 642                  * If system is getting low on clists, just flush our
 643                  * output queue (if the stuff was important, it'll get
 644                  * retransmitted). Note that SLTMAX is used instead of
 645                  * the current if_mtu setting because connections that
 646                  * have already been established still use the original
 647                  * (possibly larger) mss.
 648                  */
 649                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 650                         m_freem(m);
 651                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 652                         continue;
 653                 }
 654
 655                 sc->sc_flags &= ~SC_OUTWAIT;
 656                 /*
 657                  * The extra FRAME_END will start up a new packet, and thus
 658                  * will flush any accumulated garbage.  We do this whenever
 659                  * the line may have been idle for some time.
 660                  */
 661                 if (tp->t_outq.c_cc == 0) {
 662                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 663                         clist_putc(FRAME_END, &tp->t_outq);
 664                 }
 665
 666                 while (m) {
 667                         u_char *ep;
 668
 669                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 670                         while (cp < ep) {
 671                                 /*
 672                                  * Find out how many bytes in the string we can
 673                                  * handle without doing something special.
 674                                  */
 675                                 u_char *bp = cp;
 676
 677                                 while (cp < ep) {
 678                                         switch (*cp++) {
 679                                         case FRAME_ESCAPE:
 680                                         case FRAME_END:
 681                                                 --cp;
 682                                                 goto out;
 683                                         }
 684                                 }
 685                                 out:
 686                                 if (cp > bp) {
 687                                         /*
 688                                          * Put n characters at once
 689                                          * into the tty output queue.
 690                                          */
 691                                         if (b_to_q((char *)bp, cp - bp,
 692                                             &tp->t_outq))
 693                                                 break;
 694                                         IFNET_STAT_INC(&sc->sc_if, obytes,
 695                                             cp - bp);
 696                                 }
 697                                 /*
 698                                  * If there are characters left in the mbuf,
 699                                  * the first one must be special..
 700                                  * Put it out in a different form.
 701                                  */
 702                                 if (cp < ep) {
 703                                         if (clist_putc(FRAME_ESCAPE, &tp->t_outq))
 704                                                 break;
 705                                         if (clist_putc(*cp++ == FRAME_ESCAPE ?
 706                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 707                                            &tp->t_outq)) {
 708                                                 clist_unputc(&tp->t_outq);
 709                                                 break;
 710                                         }
 711                                         IFNET_STAT_INC(&sc->sc_if, obytes, 2);
 712                                 }
 713                         }
 714                         m = m_free(m);
 715                 }
 716
 717                 if (clist_putc(FRAME_END, &tp->t_outq)) {
 718                         /*
 719                          * Not enough room.  Remove a char to make room
 720                          * and end the packet normally.
 721                          * If you get many collisions (more than one or two
 722                          * a day) you probably do not have enough clists
 723                          * and you should increase "nclist" in param.c.
 724                          */
 725                         clist_unputc(&tp->t_outq);
 726                         clist_putc(FRAME_END, &tp->t_outq);
 727                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 728                 } else {
 729                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 730                         IFNET_STAT_INC(&sc->sc_if, opackets, 1);
 731                 }
 732         }
 733         lwkt_reltoken(&tty_token);
 734         return 0;
 735 }
 736
 737 /*
 738  * Copy data buffer to mbuf chain; add ifnet pointer.
 739  */
 740 static struct mbuf *
 741 sl_btom(struct sl_softc *sc, int len)
 742 {
 743         struct mbuf *m;
 744
 745         if (len >= MCLBYTES)
 746                 return (NULL);
 747
 748         MGETHDR(m, M_NOWAIT, MT_DATA);
 749         if (m == NULL)
 750                 return (NULL);
 751
 752         /*
 753          * If we have more than MHLEN bytes, it's cheaper to
 754          * queue the cluster we just filled & allocate a new one
 755          * for the input buffer.  Otherwise, fill the mbuf we
 756          * allocated above.  Note that code in the input routine
 757          * guarantees that packet will fit in a cluster.
 758          */
 759         if (len >= MHLEN) {
 760                 MCLGET(m, M_NOWAIT);
 761                 if ((m->m_flags & M_EXT) == 0) {
 762                         /*
 763                          * we couldn't get a cluster - if memory's this
 764                          * low, it's time to start dropping packets.
 765                          */
 766                         m_free(m);
 767                         return (NULL);
 768                 }
 769         }
 770         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 771         m->m_len = len;
 772         m->m_pkthdr.len = len;
 773         m->m_pkthdr.rcvif = &sc->sc_if;
 774         return (m);
 775 }
 776
 777 /*
 778  * tty interface receiver interrupt.
 779  */
 780 static int
 781 slinput(int c, struct tty *tp)
 782 {
 783         struct sl_softc *sc;
 784         struct mbuf *m;
 785         int len;
 786         u_char chdr[CHDR_LEN];
 787
 788         lwkt_gettoken(&tty_token);
 789         tk_nin++;
 790         sc = (struct sl_softc *)tp->t_sc;
 791         if (sc == NULL) {
 792                 lwkt_reltoken(&tty_token);
 793                 return 0;
 794         }
 795         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 796                 sc->sc_flags |= SC_ERROR;
 797                 lwkt_reltoken(&tty_token);
 798                 return 0;
 799         }
 800         c &= TTY_CHARMASK;
 801
 802         IFNET_STAT_INC(&sc->sc_if, ibytes, 1);
 803
 804         if (sc->sc_if.if_flags & IFF_DEBUG) {
 805                 if (c == ABT_ESC) {
 806                         /*
 807                          * If we have a previous abort, see whether
 808                          * this one is within the time limit.
 809                          */
 810                         if (sc->sc_abortcount &&
 811                             time_uptime >= sc->sc_starttime + ABT_WINDOW)
 812                                 sc->sc_abortcount = 0;
 813                         /*
 814                          * If we see an abort after "idle" time, count it;
 815                          * record when the first abort escape arrived.
 816                          */
 817                         if (time_uptime >= sc->sc_lasttime + ABT_IDLE) {
 818                                 if (++sc->sc_abortcount == 1)
 819                                         sc->sc_starttime = time_uptime;
 820                                 if (sc->sc_abortcount >= ABT_COUNT) {
 821                                         slclose(tp,0);
 822                                         lwkt_reltoken(&tty_token);
 823                                         return 0;
 824                                 }
 825                         }
 826                 } else
 827                         sc->sc_abortcount = 0;
 828                 sc->sc_lasttime = time_uptime;
 829         }
 830
 831         switch (c) {
 832
 833         case TRANS_FRAME_ESCAPE:
 834                 if (sc->sc_escape)
 835                         c = FRAME_ESCAPE;
 836                 break;
 837
 838         case TRANS_FRAME_END:
 839                 if (sc->sc_escape)
 840                         c = FRAME_END;
 841                 break;
 842
 843         case FRAME_ESCAPE:
 844                 sc->sc_escape = 1;
 845                 lwkt_reltoken(&tty_token);
 846                 return 0;
 847
 848         case FRAME_END:
 849                 sc->sc_flags &= ~SC_KEEPALIVE;
 850                 if(sc->sc_flags & SC_ERROR) {
 851                         sc->sc_flags &= ~SC_ERROR;
 852                         goto newpack;
 853                 }
 854                 len = sc->sc_mp - sc->sc_buf;
 855                 if (len < 3)
 856                         /* less than min length packet - ignore */
 857                         goto newpack;
 858
 859                 if (sc->sc_if.if_bpf) {
 860                         /*
 861                          * Save the compressed header, so we
 862                          * can tack it on later.  Note that we
 863                          * will end up copying garbage in some
 864                          * cases but this is okay.  We remember
 865                          * where the buffer started so we can
 866                          * compute the new header length.
 867                          */
 868                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 869                 }
 870
 871                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 872                         if (c & 0x80)
 873                                 c = TYPE_COMPRESSED_TCP;
 874                         else if (c == TYPE_UNCOMPRESSED_TCP)
 875                                 *sc->sc_buf &= 0x4f; /* XXX */
 876                         /*
 877                          * We've got something that's not an IP packet.
 878                          * If compression is enabled, try to decompress it.
 879                          * Otherwise, if `auto-enable' compression is on and
 880                          * it's a reasonable packet, decompress it and then
 881                          * enable compression.  Otherwise, drop it.
 882                          */
 883                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 884                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 885                                                         (u_int)c, &sc->sc_comp);
 886                                 if (len <= 0)
 887                                         goto error;
 888                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 889                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 890                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 891                                                         (u_int)c, &sc->sc_comp);
 892                                 if (len <= 0)
 893                                         goto error;
 894                                 sc->sc_if.if_flags |= SC_COMPRESS;
 895                         } else
 896                                 goto error;
 897                 }
 898                 if (sc->sc_if.if_bpf) {
 899                         bpf_gettoken();
 900
 901                         if (sc->sc_if.if_bpf) {
 902                                 /*
 903                                  * Put the SLIP pseudo-"link header" in place.
 904                                  * We couldn't do this any earlier since
 905                                  * decompression probably moved the buffer
 906                                  * pointer.  Then, invoke BPF.
 907                                  */
 908                                 u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 909
 910                                 hp[SLX_DIR] = SLIPDIR_IN;
 911                                 bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 912                                 bpf_tap(sc->sc_if.if_bpf, hp,
 913                                     len + SLIP_HDRLEN);
 914                         }
 915
 916                         bpf_reltoken();
 917                 }
 918                 m = sl_btom(sc, len);
 919                 if (m == NULL)
 920                         goto error;
 921
 922                 IFNET_STAT_INC(&sc->sc_if, ipackets, 1);
 923
 924                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 925                         m_freem(m);
 926                         goto newpack;
 927                 }
 928
 929                 if (netisr_queue(NETISR_IP, m)) {
 930                         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 931                         IFNET_STAT_INC(&sc->sc_if, iqdrops, 1);
 932                 }
 933
 934                 goto newpack;
 935         }
 936         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 937                 *sc->sc_mp++ = c;
 938                 sc->sc_escape = 0;
 939                 lwkt_reltoken(&tty_token);
 940                 return 0;
 941         }
 942
 943         /* can't put lower; would miss an extra frame */
 944         sc->sc_flags |= SC_ERROR;
 945
 946 error:
 947         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 948 newpack:
 949         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 950         sc->sc_escape = 0;
 951         lwkt_reltoken(&tty_token);
 952         return 0;
 953 }
 954
 955 /*
 956  * Process an ioctl request.
 957  */
 958 static int
 959 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 960 {
 961         struct ifaddr *ifa = (struct ifaddr *)data;
 962         struct ifreq *ifr = (struct ifreq *)data;
 963         int error = 0;
 964
 965         crit_enter();
 966
 967         switch (cmd) {
 968
 969         case SIOCSIFFLAGS:
 970                 /*
 971                  * if.c will set the interface up even if we
 972                  * don't want it to.
 973                  */
 974                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 975                         ifp->if_flags &= ~IFF_UP;
 976                 }
 977                 break;
 978         case SIOCSIFADDR:
 979                 /*
 980                  * This is "historical" - set the interface up when
 981                  * setting the address.
 982                  */
 983                 if (ifa->ifa_addr->sa_family == AF_INET) {
 984                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 985                                 ifp->if_flags |= IFF_UP;
 986                 } else {
 987                         error = EAFNOSUPPORT;
 988                 }
 989                 break;
 990
 991         case SIOCSIFDSTADDR:
 992                 if (ifa->ifa_addr->sa_family != AF_INET)
 993                         error = EAFNOSUPPORT;
 994                 break;
 995
 996         case SIOCADDMULTI:
 997         case SIOCDELMULTI:
 998                 break;
 999
1000         case SIOCSIFMTU:
1001                 /*
1002                  * Set the interface MTU.
1003                  */
1004                 if (ifr->ifr_mtu > SLTMAX)
1005                         error = EINVAL;
1006                 else {
1007                         struct tty *tp;
1008
1009                         ifp->if_mtu = ifr->ifr_mtu;
1010                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
1011                         if (tp != NULL)
1012                                 clist_alloc_cblocks(&tp->t_outq,
1013                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
1014                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
1015                 }
1016                 break;
1017
1018         default:
1019                 error = EINVAL;
1020         }
1021
1022         crit_exit();
1023         return (error);
1024 }
1025
1026 static void
1027 sl_keepalive(void *chan)
1028 {
1029         struct sl_softc *sc = chan;
1030         struct pgrp *pg;
1031
1032         lwkt_gettoken(&tty_token);
1033         if (sc->sc_keepalive) {
1034                 if (sc->sc_flags & SC_KEEPALIVE) {
1035                         pg = sc->sc_ttyp->t_pgrp;
1036                         if (pg) {
1037                                 pgref(pg);
1038                                 pgsignal (pg, SIGURG, 1);
1039                                 pgrel(pg);
1040                         }
1041                 } else {
1042                         sc->sc_flags |= SC_KEEPALIVE;
1043                 }
1044                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
1045                                 sl_keepalive, sc);
1046         } else {
1047                 sc->sc_flags &= ~SC_KEEPALIVE;
1048         }
1049         lwkt_reltoken(&tty_token);
1050 }
1051
1052 static void
1053 sl_outfill(void *chan)
1054 {
1055         struct sl_softc *sc = chan;
1056         struct tty *tp = sc->sc_ttyp;
1057
1058         lwkt_gettoken(&tty_token);
1059
1060         if (sc->sc_outfill && tp != NULL) {
1061                 if (sc->sc_flags & SC_OUTWAIT) {
1062                         crit_enter();
1063                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
1064                         clist_putc(FRAME_END, &tp->t_outq);
1065                         (*tp->t_oproc)(tp);
1066                         crit_exit();
1067                 } else
1068                         sc->sc_flags |= SC_OUTWAIT;
1069                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1070                                 sl_outfill, sc);
1071         } else {
1072                 sc->sc_flags &= ~SC_OUTWAIT;
1073         }
1074         lwkt_reltoken(&tty_token);
1075 }