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. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)if_sl.c     8.6 (Berkeley) 2/1/94
  36  * $FreeBSD: src/sys/net/if_sl.c,v 1.84.2.2 2002/02/13 00:43:10 dillon Exp $
  37  * $DragonFly: src/sys/net/sl/if_sl.c,v 1.32 2008/05/14 11:59:23 sephe Exp $
  38  */
  39
  40 /*
  41  * Serial Line interface
  42  *
  43  * Rick Adams
  44  * Center for Seismic Studies
  45  * 1300 N 17th Street, Suite 1450
  46  * Arlington, Virginia 22209
  47  * (703)276-7900
  48  * rick@seismo.ARPA
  49  * seismo!rick
  50  *
  51  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
  52  * N.B.: this belongs in netinet, not net, the way it stands now.
  53  * Should have a link-layer type designation, but wouldn't be
  54  * backwards-compatible.
  55  *
  56  * Converted to 4.3BSD Beta by Chris Torek.
  57  * Other changes made at Berkeley, based in part on code by Kirk Smith.
  58  * W. Jolitz added slip abort.
  59  *
  60  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
  61  * Added priority queuing for "interactive" traffic; hooks for TCP
  62  * header compression; ICMP filtering (at 2400 baud, some cretin
  63  * pinging you can use up all your bandwidth).  Made low clist behavior
  64  * more robust and slightly less likely to hang serial line.
  65  * Sped up a bunch of things.
  66  */
  67
  68 #include "use_sl.h"
  69
  70 #include "opt_inet.h"
  71 #if !defined(KLD_MODULE)
  72 #include "opt_slip.h"
  73 #endif
  74 #include <sys/param.h>
  75 #include <sys/systm.h>
  76 #include <sys/proc.h>
  77 #include <sys/priv.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 #include <sys/thread2.h>
  90
  91 #include <net/if.h>
  92 #include <net/if_types.h>
  93 #include <net/ifq_var.h>
  94 #include <net/netisr.h>
  95
  96 #if INET
  97 #include <netinet/in.h>
  98 #include <netinet/in_systm.h>
  99 #include <netinet/in_var.h>
 100 #include <netinet/ip.h>
 101 #else
 102 #error "Huh? Slip without inet?"
 103 #endif
 104
 105 #include <net/slcompress.h>
 106 #include "if_slvar.h"
 107 #include <net/slip.h>
 108
 109 #include <net/bpf.h>
 110
 111 static void slattach (void *);
 112 PSEUDO_SET(slattach, if_sl);
 113
 114 /*
 115  * SLRMAX is a hard limit on input packet size.  To simplify the code
 116  * and improve performance, we require that packets fit in an mbuf
 117  * cluster, and if we get a compressed packet, there's enough extra
 118  * room to expand the header into a max length tcp/ip header (128
 119  * bytes).  So, SLRMAX can be at most
 120  *      MCLBYTES - 128
 121  *
 122  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 123  * small enough so that interactive use doesn't suffer, but large
 124  * enough to provide good performance. 552 is a good choice for SLMTU
 125  * because it is high enough to not fragment TCP packets being routed
 126  * through this host. Packet fragmentation is bad with SLIP because
 127  * fragment headers aren't compressed. The previous assumptions about
 128  * the best MTU value don't really hold when using modern modems with
 129  * BTLZ data compression because the modem buffers play a much larger
 130  * role in interactive performance than the MTU. The MTU can be changed
 131  * at any time to suit the specific environment with ifconfig(8), and
 132  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 133  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 134  * handles this better).
 135  *
 136  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 137  * of us (i.e., in clists waiting to be picked up by the tty output
 138  * interrupt).  If we queue a lot of data downstream, it's immune to
 139  * our t.o.s. queuing.
 140  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 141  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 142  * wait is dependent on the ftp window size but that's typically
 143  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 144  * the cost (in idle time on the wire) of the tty driver running
 145  * off the end of its clists & having to call back slstart for a
 146  * new packet.  For a tty interface with any buffering at all, this
 147  * cost will be zero.  Even with a totally brain dead interface (like
 148  * the one on a typical workstation), the cost will be <= 1 character
 149  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 150  * at most 1% while maintaining good interactive response.
 151  */
 152 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 153 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 154 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 155 #ifndef SLMTU
 156 #define SLMTU           552             /* default MTU */
 157 #endif
 158 #define SLTMAX          1500            /* maximum MTU */
 159 #define SLIP_HIWAT      roundup(50,CBSIZE)
 160 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 161
 162 /*
 163  * SLIP ABORT ESCAPE MECHANISM:
 164  *      (inspired by HAYES modem escape arrangement)
 165  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 166  *      within window time signals a "soft" exit from slip mode by remote end
 167  *      if the IFF_DEBUG flag is on.
 168  */
 169 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 170 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 171 #define ABT_COUNT       3       /* count of escapes for abort */
 172 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 173
 174 static struct sl_softc sl_softc[NSL];
 175
 176 #define FRAME_END               0xc0            /* Frame End */
 177 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 178 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 179 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 180
 181 static int slinit (struct sl_softc *);
 182 static struct mbuf *sl_btom (struct sl_softc *, int);
 183 static timeout_t sl_keepalive;
 184 static timeout_t sl_outfill;
 185 static int      slclose (struct tty *,int);
 186 static int      slinput (int, struct tty *);
 187 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 188 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct ucred *);
 189 static int      slopen (cdev_t, struct tty *);
 190 static int      sloutput (struct ifnet *,
 191             struct mbuf *, struct sockaddr *, struct rtentry *);
 192 static int      slstart (struct tty *);
 193
 194 static struct linesw slipdisc = {
 195         slopen,         slclose,        l_noread,       l_nowrite,
 196         sltioctl,       slinput,        slstart,        ttymodem,
 197         FRAME_END
 198 };
 199
 200 /*
 201  * Called from boot code to establish sl interfaces.
 202  */
 203 static void
 204 slattach(void *dummy)
 205 {
 206         struct sl_softc *sc;
 207         int i = 0;
 208
 209         lwkt_gettoken(&tty_token);
 210         linesw[SLIPDISC] = slipdisc;
 211
 212         for (sc = sl_softc; i < NSL; sc++) {
 213                 if_initname(&(sc->sc_if), "sl", i++);
 214                 sc->sc_if.if_mtu = SLMTU;
 215                 sc->sc_if.if_flags =
 216 #ifdef SLIP_IFF_OPTS
 217                     SLIP_IFF_OPTS;
 218 #else
 219                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 220 #endif
 221                 sc->sc_if.if_type = IFT_SLIP;
 222                 sc->sc_if.if_ioctl = slioctl;
 223                 sc->sc_if.if_output = sloutput;
 224                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 225                 ifq_set_ready(&sc->sc_if.if_snd);
 226                 sc->sc_fastq.ifq_maxlen = 32;
 227                 sc->sc_if.if_linkmib = sc;
 228                 sc->sc_if.if_linkmiblen = sizeof *sc;
 229                 callout_init_mp(&sc->sc_oftimeout);
 230                 callout_init_mp(&sc->sc_katimeout);
 231                 if_attach(&sc->sc_if, NULL);
 232                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 233         }
 234         lwkt_reltoken(&tty_token);
 235 }
 236
 237 static int
 238 slinit(struct sl_softc *sc)
 239 {
 240         lwkt_gettoken(&tty_token);
 241         if (sc->sc_ep == NULL)
 242                 sc->sc_ep = kmalloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 243         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 244         sc->sc_mp = sc->sc_buf;
 245         sl_compress_init(&sc->sc_comp, -1);
 246         lwkt_reltoken(&tty_token);
 247         return (1);
 248 }
 249
 250 /*
 251  * Line specific open routine.
 252  * Attach the given tty to the first available sl unit.
 253  */
 254 /* ARGSUSED */
 255 static int
 256 slopen(cdev_t dev, struct tty *tp)
 257 {
 258         struct sl_softc *sc;
 259         int nsl;
 260         int error;
 261         struct thread *td = curthread;  /* XXX */
 262
 263         error = priv_check(td, PRIV_ROOT);
 264         if (error)
 265                 return (error);
 266
 267         lwkt_gettoken(&tty_token);
 268         if (tp->t_line == SLIPDISC) {
 269                 lwkt_reltoken(&tty_token);
 270                 return (0);
 271         }
 272
 273         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 274                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 275                         if (slinit(sc) == 0) {
 276                                 lwkt_reltoken(&tty_token);
 277                                 return (ENOBUFS);
 278                         }
 279                         tp->t_sc = (caddr_t)sc;
 280                         sc->sc_ttyp = tp;
 281                         sc->sc_if.if_baudrate = tp->t_ospeed;
 282                         ttyflush(tp, FREAD | FWRITE);
 283
 284                         tp->t_line = SLIPDISC;
 285                         /*
 286                          * We don't use t_canq or t_rawq, so reduce their
 287                          * cblock resources to 0.  Reserve enough cblocks
 288                          * for t_outq to guarantee that we can fit a full
 289                          * packet if the SLIP_HIWAT check allows slstart()
 290                          * to loop.  Use the same value for the cblock
 291                          * limit since the reserved blocks should always
 292                          * be enough.  Reserving cblocks probably makes
 293                          * the CLISTRESERVE check unnecessary and wasteful.
 294                          */
 295                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 296                         clist_alloc_cblocks(&tp->t_outq,
 297                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 298                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 299                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 300
 301                         crit_enter();
 302                         if_up(&sc->sc_if);
 303                         crit_exit();
 304                         lwkt_reltoken(&tty_token);
 305                         return (0);
 306                 }
 307         lwkt_reltoken(&tty_token);
 308         return (ENXIO);
 309 }
 310
 311 /*
 312  * Line specific close routine.
 313  * Detach the tty from the sl unit.
 314  */
 315 static int
 316 slclose(struct tty *tp, int flag)
 317 {
 318         struct sl_softc *sc;
 319
 320         lwkt_gettoken(&tty_token);
 321         ttyflush(tp, FREAD | FWRITE);
 322         crit_enter();
 323
 324         clist_free_cblocks(&tp->t_outq);
 325         tp->t_line = 0;
 326         sc = (struct sl_softc *)tp->t_sc;
 327         if (sc != NULL) {
 328                 if (sc->sc_outfill) {
 329                         sc->sc_outfill = 0;
 330                         callout_stop(&sc->sc_oftimeout);
 331                 }
 332                 if (sc->sc_keepalive) {
 333                         sc->sc_keepalive = 0;
 334                         callout_stop(&sc->sc_katimeout);
 335                 }
 336                 if_down(&sc->sc_if);
 337                 sc->sc_flags &= SC_STATIC;
 338                 sc->sc_ttyp = NULL;
 339                 tp->t_sc = NULL;
 340                 if (sc->sc_ep) {
 341                         kfree(sc->sc_ep, M_DEVBUF);
 342                         sc->sc_ep = NULL;
 343                 }
 344                 sc->sc_mp = 0;
 345                 sc->sc_buf = 0;
 346         }
 347         crit_exit();
 348         lwkt_reltoken(&tty_token);
 349         return 0;
 350 }
 351
 352 /*
 353  * Line specific (tty) ioctl routine.
 354  * Provide a way to get the sl unit number.
 355  */
 356 /* ARGSUSED */
 357 static int
 358 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
 359 {
 360         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 361         int nsl;
 362
 363         crit_enter();
 364         lwkt_gettoken(&tty_token);
 365
 366         switch (cmd) {
 367         case SLIOCGUNIT:
 368                 *(int *)data = sc->sc_if.if_dunit;
 369                 break;
 370
 371         case SLIOCSUNIT:
 372                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 373                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 374                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 375                                     && nc->sc_ttyp == NULL
 376                                    ) {
 377                                         tmpnc = kmalloc(sizeof *tmpnc, M_TEMP,
 378                                                        M_WAITOK);
 379                                         *tmpnc = *nc;
 380                                         *nc = *sc;
 381                                         nc->sc_if = tmpnc->sc_if;
 382                                         tmpnc->sc_if = sc->sc_if;
 383                                         *sc = *tmpnc;
 384                                         kfree(tmpnc, M_TEMP);
 385                                         if (sc->sc_if.if_flags & IFF_UP) {
 386                                                 if_down(&sc->sc_if);
 387                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 388                                                         if_up(&nc->sc_if);
 389                                         } else if (nc->sc_if.if_flags & IFF_UP)
 390                                                 if_down(&nc->sc_if);
 391                                         sc->sc_flags &= ~SC_STATIC;
 392                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 393                                         tp->t_sc = sc = nc;
 394                                         clist_alloc_cblocks(&tp->t_outq,
 395                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 396                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 397                                         sl_compress_init(&sc->sc_comp, -1);
 398                                         goto slfound;
 399                                 }
 400                         }
 401                         lwkt_reltoken(&tty_token);
 402                         crit_exit();
 403                         return (ENXIO);
 404                 }
 405         slfound:
 406                 sc->sc_flags |= SC_STATIC;
 407                 break;
 408
 409         case SLIOCSKEEPAL:
 410                 sc->sc_keepalive = *(u_int *)data * hz;
 411                 if (sc->sc_keepalive) {
 412                         sc->sc_flags |= SC_KEEPALIVE;
 413                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 414                                         sl_keepalive, sc);
 415                 } else {
 416                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 417                                 callout_stop(&sc->sc_katimeout);
 418                                 sc->sc_flags &= ~SC_KEEPALIVE;
 419                         }
 420                 }
 421                 break;
 422
 423         case SLIOCGKEEPAL:
 424                 *(int *)data = sc->sc_keepalive / hz;
 425                 break;
 426
 427         case SLIOCSOUTFILL:
 428                 sc->sc_outfill = *(u_int *)data * hz;
 429                 if (sc->sc_outfill) {
 430                         sc->sc_flags |= SC_OUTWAIT;
 431                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 432                                         sl_outfill, sc);
 433                 } else {
 434                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 435                                 callout_stop(&sc->sc_oftimeout);
 436                                 sc->sc_flags &= ~SC_OUTWAIT;
 437                         }
 438                 }
 439                 break;
 440
 441         case SLIOCGOUTFILL:
 442                 *(int *)data = sc->sc_outfill / hz;
 443                 break;
 444
 445         default:
 446                 lwkt_reltoken(&tty_token);
 447                 crit_exit();
 448                 return (ENOIOCTL);
 449         }
 450         lwkt_reltoken(&tty_token);
 451         crit_exit();
 452         return (0);
 453 }
 454
 455 /*
 456  * Queue a packet.  Start transmission if not active.
 457  * Compression happens in slstart; if we do it here, IP TOS
 458  * will cause us to not compress "background" packets, because
 459  * ordering gets trashed.  It can be done for all packets in slstart.
 460  */
 461 static int
 462 sloutput_serialized(struct ifnet *ifp, struct ifaltq_subque *ifsq,
 463     struct mbuf *m, struct sockaddr *dst, struct rtentry *rtp)
 464 {
 465         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 466         struct ip *ip;
 467         int error;
 468         struct altq_pktattr pktattr;
 469
 470         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 471
 472         /*
 473          * `Cannot happen' (see slioctl).  Someday we will extend
 474          * the line protocol to support other address families.
 475          */
 476         if (dst->sa_family != AF_INET) {
 477                 kprintf("%s: af%d not supported\n", sc->sc_if.if_xname,
 478                         dst->sa_family);
 479                 m_freem(m);
 480                 IFNET_STAT_INC(&sc->sc_if, noproto, 1);
 481                 return (EAFNOSUPPORT);
 482         }
 483
 484         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 485                 m_freem(m);
 486                 return (ENETDOWN);
 487         }
 488         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 489                 m_freem(m);
 490                 return (EHOSTUNREACH);
 491         }
 492         ip = mtod(m, struct ip *);
 493         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 494                 m_freem(m);
 495                 return (ENETRESET);             /* XXX ? */
 496         }
 497
 498         crit_enter();
 499
 500         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 501                 if (IF_QFULL(&sc->sc_fastq)) {
 502                         IF_DROP(&sc->sc_fastq);
 503                         m_freem(m);
 504                         error = ENOBUFS;
 505                 } else {
 506                         IF_ENQUEUE(&sc->sc_fastq, m);
 507                         error = 0;
 508                 }
 509         } else {
 510                 error = ifsq_enqueue(ifsq, m, &pktattr);
 511         }
 512         if (error) {
 513                 IFNET_STAT_INC(&sc->sc_if, oerrors, 1);
 514                 crit_exit();
 515                 return (error);
 516         }
 517         if (sc->sc_ttyp->t_outq.c_cc == 0)
 518                 slstart(sc->sc_ttyp);
 519         crit_exit();
 520         return (0);
 521 }
 522
 523 static int
 524 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 525          struct rtentry *rtp)
 526 {
 527         struct ifaltq_subque *ifsq = ifq_get_subq_default(&ifp->if_snd);
 528         int error;
 529
 530         ifsq_serialize_hw(ifsq);
 531         error = sloutput_serialized(ifp, ifsq, m, dst, rtp);
 532         ifsq_deserialize_hw(ifsq);
 533
 534         return error;
 535 }
 536
 537 /*
 538  * Start output on interface.  Get another datagram
 539  * to send from the interface queue and map it to
 540  * the interface before starting output.
 541  */
 542 static int
 543 slstart(struct tty *tp)
 544 {
 545         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 546         struct ifaltq_subque *ifsq = ifq_get_subq_default(&sc->sc_if.if_snd);
 547         struct mbuf *m;
 548         u_char *cp;
 549         struct ip *ip;
 550         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 551         int len = 0;
 552
 553         lwkt_gettoken(&tty_token);
 554         for (;;) {
 555                 /*
 556                  * Call output process whether or not there is more in the
 557                  * output queue.  We are being called in lieu of ttstart
 558                  * and must do what it would.
 559                  */
 560                 (*tp->t_oproc)(tp);
 561
 562                 if (tp->t_outq.c_cc != 0) {
 563                         if (sc != NULL)
 564                                 sc->sc_flags &= ~SC_OUTWAIT;
 565                         if (tp->t_outq.c_cc > SLIP_HIWAT) {
 566                                 lwkt_reltoken(&tty_token);
 567                                 return 0;
 568                         }
 569                 }
 570
 571                 /*
 572                  * This happens briefly when the line shuts down.
 573                  */
 574                 if (sc == NULL) {
 575                         lwkt_reltoken(&tty_token);
 576                         return 0;
 577                 }
 578
 579                 /*
 580                  * Get a packet and send it to the interface.
 581                  */
 582                 crit_enter();
 583                 IF_DEQUEUE(&sc->sc_fastq, m);
 584                 if (m)
 585                         IFNET_STAT_INC(&sc->sc_if, omcasts, 1); /* XXX */
 586                 else
 587                         m = ifsq_dequeue(ifsq, NULL);
 588                 crit_exit();
 589                 if (m == NULL) {
 590                         lwkt_reltoken(&tty_token);
 591                         return 0;
 592                 }
 593
 594                 /*
 595                  * We do the header compression here rather than in sloutput
 596                  * because the packets will be out of order if we are using TOS
 597                  * queueing, and the connection id compression will get
 598                  * munged when this happens.
 599                  */
 600                 if (sc->sc_if.if_bpf) {
 601                         /*
 602                          * We need to save the TCP/IP header before it's
 603                          * compressed.  To avoid complicated code, we just
 604                          * copy the entire packet into a stack buffer (since
 605                          * this is a serial line, packets should be short
 606                          * and/or the copy should be negligible cost compared
 607                          * to the packet transmission time).
 608                          */
 609                         struct mbuf *m1 = m;
 610                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 611
 612                         len = 0;
 613                         do {
 614                                 int mlen = m1->m_len;
 615
 616                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 617                                 cp += mlen;
 618                                 len += mlen;
 619                         } while ((m1 = m1->m_next) != NULL);
 620                 }
 621                 ip = mtod(m, struct ip *);
 622                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 623                         if (sc->sc_if.if_flags & SC_COMPRESS)
 624                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 625                                     &sc->sc_comp, 1);
 626                 }
 627                 if (sc->sc_if.if_bpf) {
 628                         bpf_gettoken();
 629
 630                         if (sc->sc_if.if_bpf) {
 631                                 /*
 632                                  * Put the SLIP pseudo-"link header" in place.
 633                                  * The compressed header is now at the
 634                                  * beginning of the mbuf.
 635                                  */
 636                                 bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 637                                 bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR],
 638                                     CHDR_LEN);
 639                                 bpf_tap(sc->sc_if.if_bpf, bpfbuf,
 640                                     len + SLIP_HDRLEN);
 641                         }
 642
 643                         bpf_reltoken();
 644                 }
 645
 646                 /*
 647                  * If system is getting low on clists, just flush our
 648                  * output queue (if the stuff was important, it'll get
 649                  * retransmitted). Note that SLTMAX is used instead of
 650                  * the current if_mtu setting because connections that
 651                  * have already been established still use the original
 652                  * (possibly larger) mss.
 653                  */
 654                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 655                         m_freem(m);
 656                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 657                         continue;
 658                 }
 659
 660                 sc->sc_flags &= ~SC_OUTWAIT;
 661                 /*
 662                  * The extra FRAME_END will start up a new packet, and thus
 663                  * will flush any accumulated garbage.  We do this whenever
 664                  * the line may have been idle for some time.
 665                  */
 666                 if (tp->t_outq.c_cc == 0) {
 667                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 668                         clist_putc(FRAME_END, &tp->t_outq);
 669                 }
 670
 671                 while (m) {
 672                         u_char *ep;
 673
 674                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 675                         while (cp < ep) {
 676                                 /*
 677                                  * Find out how many bytes in the string we can
 678                                  * handle without doing something special.
 679                                  */
 680                                 u_char *bp = cp;
 681
 682                                 while (cp < ep) {
 683                                         switch (*cp++) {
 684                                         case FRAME_ESCAPE:
 685                                         case FRAME_END:
 686                                                 --cp;
 687                                                 goto out;
 688                                         }
 689                                 }
 690                                 out:
 691                                 if (cp > bp) {
 692                                         /*
 693                                          * Put n characters at once
 694                                          * into the tty output queue.
 695                                          */
 696                                         if (b_to_q((char *)bp, cp - bp,
 697                                             &tp->t_outq))
 698                                                 break;
 699                                         IFNET_STAT_INC(&sc->sc_if, obytes,
 700                                             cp - bp);
 701                                 }
 702                                 /*
 703                                  * If there are characters left in the mbuf,
 704                                  * the first one must be special..
 705                                  * Put it out in a different form.
 706                                  */
 707                                 if (cp < ep) {
 708                                         if (clist_putc(FRAME_ESCAPE, &tp->t_outq))
 709                                                 break;
 710                                         if (clist_putc(*cp++ == FRAME_ESCAPE ?
 711                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 712                                            &tp->t_outq)) {
 713                                                 clist_unputc(&tp->t_outq);
 714                                                 break;
 715                                         }
 716                                         IFNET_STAT_INC(&sc->sc_if, obytes, 2);
 717                                 }
 718                         }
 719                         m = m_free(m);
 720                 }
 721
 722                 if (clist_putc(FRAME_END, &tp->t_outq)) {
 723                         /*
 724                          * Not enough room.  Remove a char to make room
 725                          * and end the packet normally.
 726                          * If you get many collisions (more than one or two
 727                          * a day) you probably do not have enough clists
 728                          * and you should increase "nclist" in param.c.
 729                          */
 730                         clist_unputc(&tp->t_outq);
 731                         clist_putc(FRAME_END, &tp->t_outq);
 732                         IFNET_STAT_INC(&sc->sc_if, collisions, 1);
 733                 } else {
 734                         IFNET_STAT_INC(&sc->sc_if, obytes, 1);
 735                         IFNET_STAT_INC(&sc->sc_if, opackets, 1);
 736                 }
 737         }
 738         lwkt_reltoken(&tty_token);
 739         return 0;
 740 }
 741
 742 /*
 743  * Copy data buffer to mbuf chain; add ifnet pointer.
 744  */
 745 static struct mbuf *
 746 sl_btom(struct sl_softc *sc, int len)
 747 {
 748         struct mbuf *m;
 749
 750         if (len >= MCLBYTES)
 751                 return (NULL);
 752
 753         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 754         if (m == NULL)
 755                 return (NULL);
 756
 757         /*
 758          * If we have more than MHLEN bytes, it's cheaper to
 759          * queue the cluster we just filled & allocate a new one
 760          * for the input buffer.  Otherwise, fill the mbuf we
 761          * allocated above.  Note that code in the input routine
 762          * guarantees that packet will fit in a cluster.
 763          */
 764         if (len >= MHLEN) {
 765                 MCLGET(m, MB_DONTWAIT);
 766                 if ((m->m_flags & M_EXT) == 0) {
 767                         /*
 768                          * we couldn't get a cluster - if memory's this
 769                          * low, it's time to start dropping packets.
 770                          */
 771                         m_free(m);
 772                         return (NULL);
 773                 }
 774         }
 775         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 776         m->m_len = len;
 777         m->m_pkthdr.len = len;
 778         m->m_pkthdr.rcvif = &sc->sc_if;
 779         return (m);
 780 }
 781
 782 /*
 783  * tty interface receiver interrupt.
 784  */
 785 static int
 786 slinput(int c, struct tty *tp)
 787 {
 788         struct sl_softc *sc;
 789         struct mbuf *m;
 790         int len;
 791         u_char chdr[CHDR_LEN];
 792
 793         lwkt_gettoken(&tty_token);
 794         tk_nin++;
 795         sc = (struct sl_softc *)tp->t_sc;
 796         if (sc == NULL) {
 797                 lwkt_reltoken(&tty_token);
 798                 return 0;
 799         }
 800         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 801                 sc->sc_flags |= SC_ERROR;
 802                 lwkt_reltoken(&tty_token);
 803                 return 0;
 804         }
 805         c &= TTY_CHARMASK;
 806
 807         IFNET_STAT_INC(&sc->sc_if, ibytes, 1);
 808
 809         if (sc->sc_if.if_flags & IFF_DEBUG) {
 810                 if (c == ABT_ESC) {
 811                         /*
 812                          * If we have a previous abort, see whether
 813                          * this one is within the time limit.
 814                          */
 815                         if (sc->sc_abortcount &&
 816                             time_second >= sc->sc_starttime + ABT_WINDOW)
 817                                 sc->sc_abortcount = 0;
 818                         /*
 819                          * If we see an abort after "idle" time, count it;
 820                          * record when the first abort escape arrived.
 821                          */
 822                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 823                                 if (++sc->sc_abortcount == 1)
 824                                         sc->sc_starttime = time_second;
 825                                 if (sc->sc_abortcount >= ABT_COUNT) {
 826                                         slclose(tp,0);
 827                                         lwkt_reltoken(&tty_token);
 828                                         return 0;
 829                                 }
 830                         }
 831                 } else
 832                         sc->sc_abortcount = 0;
 833                 sc->sc_lasttime = time_second;
 834         }
 835
 836         switch (c) {
 837
 838         case TRANS_FRAME_ESCAPE:
 839                 if (sc->sc_escape)
 840                         c = FRAME_ESCAPE;
 841                 break;
 842
 843         case TRANS_FRAME_END:
 844                 if (sc->sc_escape)
 845                         c = FRAME_END;
 846                 break;
 847
 848         case FRAME_ESCAPE:
 849                 sc->sc_escape = 1;
 850                 lwkt_reltoken(&tty_token);
 851                 return 0;
 852
 853         case FRAME_END:
 854                 sc->sc_flags &= ~SC_KEEPALIVE;
 855                 if(sc->sc_flags & SC_ERROR) {
 856                         sc->sc_flags &= ~SC_ERROR;
 857                         goto newpack;
 858                 }
 859                 len = sc->sc_mp - sc->sc_buf;
 860                 if (len < 3)
 861                         /* less than min length packet - ignore */
 862                         goto newpack;
 863
 864                 if (sc->sc_if.if_bpf) {
 865                         /*
 866                          * Save the compressed header, so we
 867                          * can tack it on later.  Note that we
 868                          * will end up copying garbage in some
 869                          * cases but this is okay.  We remember
 870                          * where the buffer started so we can
 871                          * compute the new header length.
 872                          */
 873                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 874                 }
 875
 876                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 877                         if (c & 0x80)
 878                                 c = TYPE_COMPRESSED_TCP;
 879                         else if (c == TYPE_UNCOMPRESSED_TCP)
 880                                 *sc->sc_buf &= 0x4f; /* XXX */
 881                         /*
 882                          * We've got something that's not an IP packet.
 883                          * If compression is enabled, try to decompress it.
 884                          * Otherwise, if `auto-enable' compression is on and
 885                          * it's a reasonable packet, decompress it and then
 886                          * enable compression.  Otherwise, drop it.
 887                          */
 888                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 889                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 890                                                         (u_int)c, &sc->sc_comp);
 891                                 if (len <= 0)
 892                                         goto error;
 893                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 894                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 895                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 896                                                         (u_int)c, &sc->sc_comp);
 897                                 if (len <= 0)
 898                                         goto error;
 899                                 sc->sc_if.if_flags |= SC_COMPRESS;
 900                         } else
 901                                 goto error;
 902                 }
 903                 if (sc->sc_if.if_bpf) {
 904                         bpf_gettoken();
 905
 906                         if (sc->sc_if.if_bpf) {
 907                                 /*
 908                                  * Put the SLIP pseudo-"link header" in place.
 909                                  * We couldn't do this any earlier since
 910                                  * decompression probably moved the buffer
 911                                  * pointer.  Then, invoke BPF.
 912                                  */
 913                                 u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 914
 915                                 hp[SLX_DIR] = SLIPDIR_IN;
 916                                 bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 917                                 bpf_tap(sc->sc_if.if_bpf, hp,
 918                                     len + SLIP_HDRLEN);
 919                         }
 920
 921                         bpf_reltoken();
 922                 }
 923                 m = sl_btom(sc, len);
 924                 if (m == NULL)
 925                         goto error;
 926
 927                 IFNET_STAT_INC(&sc->sc_if, ipackets, 1);
 928
 929                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 930                         m_freem(m);
 931                         goto newpack;
 932                 }
 933
 934                 if (netisr_queue(NETISR_IP, m)) {
 935                         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 936                         IFNET_STAT_INC(&sc->sc_if, iqdrops, 1);
 937                 }
 938
 939                 goto newpack;
 940         }
 941         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 942                 *sc->sc_mp++ = c;
 943                 sc->sc_escape = 0;
 944                 lwkt_reltoken(&tty_token);
 945                 return 0;
 946         }
 947
 948         /* can't put lower; would miss an extra frame */
 949         sc->sc_flags |= SC_ERROR;
 950
 951 error:
 952         IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
 953 newpack:
 954         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 955         sc->sc_escape = 0;
 956         lwkt_reltoken(&tty_token);
 957         return 0;
 958 }
 959
 960 /*
 961  * Process an ioctl request.
 962  */
 963 static int
 964 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 965 {
 966         struct ifaddr *ifa = (struct ifaddr *)data;
 967         struct ifreq *ifr = (struct ifreq *)data;
 968         int error = 0;
 969
 970         crit_enter();
 971
 972         switch (cmd) {
 973
 974         case SIOCSIFFLAGS:
 975                 /*
 976                  * if.c will set the interface up even if we
 977                  * don't want it to.
 978                  */
 979                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 980                         ifp->if_flags &= ~IFF_UP;
 981                 }
 982                 break;
 983         case SIOCSIFADDR:
 984                 /*
 985                  * This is "historical" - set the interface up when
 986                  * setting the address.
 987                  */
 988                 if (ifa->ifa_addr->sa_family == AF_INET) {
 989                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 990                                 ifp->if_flags |= IFF_UP;
 991                 } else {
 992                         error = EAFNOSUPPORT;
 993                 }
 994                 break;
 995
 996         case SIOCSIFDSTADDR:
 997                 if (ifa->ifa_addr->sa_family != AF_INET)
 998                         error = EAFNOSUPPORT;
 999                 break;
1000
1001         case SIOCADDMULTI:
1002         case SIOCDELMULTI:
1003                 break;
1004
1005         case SIOCSIFMTU:
1006                 /*
1007                  * Set the interface MTU.
1008                  */
1009                 if (ifr->ifr_mtu > SLTMAX)
1010                         error = EINVAL;
1011                 else {
1012                         struct tty *tp;
1013
1014                         ifp->if_mtu = ifr->ifr_mtu;
1015                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
1016                         if (tp != NULL)
1017                                 clist_alloc_cblocks(&tp->t_outq,
1018                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
1019                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
1020                 }
1021                 break;
1022
1023         default:
1024                 error = EINVAL;
1025         }
1026
1027         crit_exit();
1028         return (error);
1029 }
1030
1031 static void
1032 sl_keepalive(void *chan)
1033 {
1034         struct sl_softc *sc = chan;
1035
1036         lwkt_gettoken(&tty_token);
1037         lwkt_gettoken(&proc_token);
1038         if (sc->sc_keepalive) {
1039                 if (sc->sc_flags & SC_KEEPALIVE)
1040                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
1041                 else
1042                         sc->sc_flags |= SC_KEEPALIVE;
1043                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
1044                                 sl_keepalive, sc);
1045         } else {
1046                 sc->sc_flags &= ~SC_KEEPALIVE;
1047         }
1048         lwkt_reltoken(&proc_token);
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 }