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/malloc.h>
  76 #include <sys/mbuf.h>
  77 #include <sys/dkstat.h>
  78 #include <sys/socket.h>
  79 #include <sys/sockio.h>
  80 #include <sys/fcntl.h>
  81 #include <sys/signalvar.h>
  82 #include <sys/tty.h>
  83 #include <sys/clist.h>
  84 #include <sys/kernel.h>
  85 #include <sys/conf.h>
  86 #include <sys/thread2.h>
  87
  88 #include <net/if.h>
  89 #include <net/if_types.h>
  90 #include <net/ifq_var.h>
  91 #include <net/netisr.h>
  92
  93 #if INET
  94 #include <netinet/in.h>
  95 #include <netinet/in_systm.h>
  96 #include <netinet/in_var.h>
  97 #include <netinet/ip.h>
  98 #else
  99 #error "Huh? Slip without inet?"
 100 #endif
 101
 102 #include <net/slcompress.h>
 103 #include "if_slvar.h"
 104 #include <net/slip.h>
 105
 106 #include <net/bpf.h>
 107
 108 static void slattach (void *);
 109 PSEUDO_SET(slattach, if_sl);
 110
 111 /*
 112  * SLRMAX is a hard limit on input packet size.  To simplify the code
 113  * and improve performance, we require that packets fit in an mbuf
 114  * cluster, and if we get a compressed packet, there's enough extra
 115  * room to expand the header into a max length tcp/ip header (128
 116  * bytes).  So, SLRMAX can be at most
 117  *      MCLBYTES - 128
 118  *
 119  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 120  * small enough so that interactive use doesn't suffer, but large
 121  * enough to provide good performance. 552 is a good choice for SLMTU
 122  * because it is high enough to not fragment TCP packets being routed
 123  * through this host. Packet fragmentation is bad with SLIP because
 124  * fragment headers aren't compressed. The previous assumptions about
 125  * the best MTU value don't really hold when using modern modems with
 126  * BTLZ data compression because the modem buffers play a much larger
 127  * role in interactive performance than the MTU. The MTU can be changed
 128  * at any time to suit the specific environment with ifconfig(8), and
 129  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 130  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 131  * handles this better).
 132  *
 133  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 134  * of us (i.e., in clists waiting to be picked up by the tty output
 135  * interrupt).  If we queue a lot of data downstream, it's immune to
 136  * our t.o.s. queuing.
 137  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 138  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 139  * wait is dependent on the ftp window size but that's typically
 140  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 141  * the cost (in idle time on the wire) of the tty driver running
 142  * off the end of its clists & having to call back slstart for a
 143  * new packet.  For a tty interface with any buffering at all, this
 144  * cost will be zero.  Even with a totally brain dead interface (like
 145  * the one on a typical workstation), the cost will be <= 1 character
 146  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 147  * at most 1% while maintaining good interactive response.
 148  */
 149 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 150 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 151 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 152 #ifndef SLMTU
 153 #define SLMTU           552             /* default MTU */
 154 #endif
 155 #define SLTMAX          1500            /* maximum MTU */
 156 #define SLIP_HIWAT      roundup(50,CBSIZE)
 157 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 158
 159 /*
 160  * SLIP ABORT ESCAPE MECHANISM:
 161  *      (inspired by HAYES modem escape arrangement)
 162  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 163  *      within window time signals a "soft" exit from slip mode by remote end
 164  *      if the IFF_DEBUG flag is on.
 165  */
 166 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 167 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 168 #define ABT_COUNT       3       /* count of escapes for abort */
 169 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 170
 171 static struct sl_softc sl_softc[NSL];
 172
 173 #define FRAME_END               0xc0            /* Frame End */
 174 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 175 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 176 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 177
 178 static int slinit (struct sl_softc *);
 179 static struct mbuf *sl_btom (struct sl_softc *, int);
 180 static timeout_t sl_keepalive;
 181 static timeout_t sl_outfill;
 182 static int      slclose (struct tty *,int);
 183 static int      slinput (int, struct tty *);
 184 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 185 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct ucred *);
 186 static int      slopen (cdev_t, struct tty *);
 187 static int      sloutput (struct ifnet *,
 188             struct mbuf *, struct sockaddr *, struct rtentry *);
 189 static int      slstart (struct tty *);
 190
 191 static struct linesw slipdisc = {
 192         slopen,         slclose,        l_noread,       l_nowrite,
 193         sltioctl,       slinput,        slstart,        ttymodem,
 194         FRAME_END
 195 };
 196
 197 /*
 198  * Called from boot code to establish sl interfaces.
 199  */
 200 static void
 201 slattach(void *dummy)
 202 {
 203         struct sl_softc *sc;
 204         int i = 0;
 205
 206         linesw[SLIPDISC] = slipdisc;
 207
 208         for (sc = sl_softc; i < NSL; sc++) {
 209                 if_initname(&(sc->sc_if), "sl", i++);
 210                 sc->sc_if.if_mtu = SLMTU;
 211                 sc->sc_if.if_flags =
 212 #ifdef SLIP_IFF_OPTS
 213                     SLIP_IFF_OPTS;
 214 #else
 215                     IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
 216 #endif
 217                 sc->sc_if.if_type = IFT_SLIP;
 218                 sc->sc_if.if_ioctl = slioctl;
 219                 sc->sc_if.if_output = sloutput;
 220                 ifq_set_maxlen(&sc->sc_if.if_snd, 50);
 221                 ifq_set_ready(&sc->sc_if.if_snd);
 222                 sc->sc_fastq.ifq_maxlen = 32;
 223                 sc->sc_if.if_linkmib = sc;
 224                 sc->sc_if.if_linkmiblen = sizeof *sc;
 225                 callout_init(&sc->sc_oftimeout);
 226                 callout_init(&sc->sc_katimeout);
 227                 if_attach(&sc->sc_if, NULL);
 228                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 229         }
 230 }
 231
 232 static int
 233 slinit(struct sl_softc *sc)
 234 {
 235         if (sc->sc_ep == NULL)
 236                 sc->sc_ep = kmalloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 237         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 238         sc->sc_mp = sc->sc_buf;
 239         sl_compress_init(&sc->sc_comp, -1);
 240         return (1);
 241 }
 242
 243 /*
 244  * Line specific open routine.
 245  * Attach the given tty to the first available sl unit.
 246  */
 247 /* ARGSUSED */
 248 static int
 249 slopen(cdev_t dev, struct tty *tp)
 250 {
 251         struct sl_softc *sc;
 252         int nsl;
 253         int error;
 254         struct thread *td = curthread;  /* XXX */
 255
 256         error = suser(td);
 257         if (error)
 258                 return (error);
 259
 260         if (tp->t_line == SLIPDISC)
 261                 return (0);
 262
 263         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 264                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 265                         if (slinit(sc) == 0)
 266                                 return (ENOBUFS);
 267                         tp->t_sc = (caddr_t)sc;
 268                         sc->sc_ttyp = tp;
 269                         sc->sc_if.if_baudrate = tp->t_ospeed;
 270                         ttyflush(tp, FREAD | FWRITE);
 271
 272                         tp->t_line = SLIPDISC;
 273                         /*
 274                          * We don't use t_canq or t_rawq, so reduce their
 275                          * cblock resources to 0.  Reserve enough cblocks
 276                          * for t_outq to guarantee that we can fit a full
 277                          * packet if the SLIP_HIWAT check allows slstart()
 278                          * to loop.  Use the same value for the cblock
 279                          * limit since the reserved blocks should always
 280                          * be enough.  Reserving cblocks probably makes
 281                          * the CLISTRESERVE check unnecessary and wasteful.
 282                          */
 283                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 284                         clist_alloc_cblocks(&tp->t_outq,
 285                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 286                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 287                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 288
 289                         crit_enter();
 290                         if_up(&sc->sc_if);
 291                         crit_exit();
 292                         return (0);
 293                 }
 294         return (ENXIO);
 295 }
 296
 297 /*
 298  * Line specific close routine.
 299  * Detach the tty from the sl unit.
 300  */
 301 static int
 302 slclose(struct tty *tp, int flag)
 303 {
 304         struct sl_softc *sc;
 305
 306         ttyflush(tp, FREAD | FWRITE);
 307         crit_enter();
 308
 309         clist_free_cblocks(&tp->t_outq);
 310         tp->t_line = 0;
 311         sc = (struct sl_softc *)tp->t_sc;
 312         if (sc != NULL) {
 313                 if (sc->sc_outfill) {
 314                         sc->sc_outfill = 0;
 315                         callout_stop(&sc->sc_oftimeout);
 316                 }
 317                 if (sc->sc_keepalive) {
 318                         sc->sc_keepalive = 0;
 319                         callout_stop(&sc->sc_katimeout);
 320                 }
 321                 if_down(&sc->sc_if);
 322                 sc->sc_flags &= SC_STATIC;
 323                 sc->sc_ttyp = NULL;
 324                 tp->t_sc = NULL;
 325                 if (sc->sc_ep) {
 326                         kfree(sc->sc_ep, M_DEVBUF);
 327                         sc->sc_ep = NULL;
 328                 }
 329                 sc->sc_mp = 0;
 330                 sc->sc_buf = 0;
 331         }
 332         crit_exit();
 333         return 0;
 334 }
 335
 336 /*
 337  * Line specific (tty) ioctl routine.
 338  * Provide a way to get the sl unit number.
 339  */
 340 /* ARGSUSED */
 341 static int
 342 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
 343 {
 344         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 345         int nsl;
 346
 347         crit_enter();
 348
 349         switch (cmd) {
 350         case SLIOCGUNIT:
 351                 *(int *)data = sc->sc_if.if_dunit;
 352                 break;
 353
 354         case SLIOCSUNIT:
 355                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 356                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 357                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 358                                     && nc->sc_ttyp == NULL
 359                                    ) {
 360                                         tmpnc = kmalloc(sizeof *tmpnc, M_TEMP,
 361                                                        M_WAITOK);
 362                                         *tmpnc = *nc;
 363                                         *nc = *sc;
 364                                         nc->sc_if = tmpnc->sc_if;
 365                                         tmpnc->sc_if = sc->sc_if;
 366                                         *sc = *tmpnc;
 367                                         kfree(tmpnc, M_TEMP);
 368                                         if (sc->sc_if.if_flags & IFF_UP) {
 369                                                 if_down(&sc->sc_if);
 370                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 371                                                         if_up(&nc->sc_if);
 372                                         } else if (nc->sc_if.if_flags & IFF_UP)
 373                                                 if_down(&nc->sc_if);
 374                                         sc->sc_flags &= ~SC_STATIC;
 375                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 376                                         tp->t_sc = sc = nc;
 377                                         clist_alloc_cblocks(&tp->t_outq,
 378                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 379                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 380                                         sl_compress_init(&sc->sc_comp, -1);
 381                                         goto slfound;
 382                                 }
 383                         }
 384                         crit_exit();
 385                         return (ENXIO);
 386                 }
 387         slfound:
 388                 sc->sc_flags |= SC_STATIC;
 389                 break;
 390
 391         case SLIOCSKEEPAL:
 392                 sc->sc_keepalive = *(u_int *)data * hz;
 393                 if (sc->sc_keepalive) {
 394                         sc->sc_flags |= SC_KEEPALIVE;
 395                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 396                                         sl_keepalive, sc);
 397                 } else {
 398                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 399                                 callout_stop(&sc->sc_katimeout);
 400                                 sc->sc_flags &= ~SC_KEEPALIVE;
 401                         }
 402                 }
 403                 break;
 404
 405         case SLIOCGKEEPAL:
 406                 *(int *)data = sc->sc_keepalive / hz;
 407                 break;
 408
 409         case SLIOCSOUTFILL:
 410                 sc->sc_outfill = *(u_int *)data * hz;
 411                 if (sc->sc_outfill) {
 412                         sc->sc_flags |= SC_OUTWAIT;
 413                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 414                                         sl_outfill, sc);
 415                 } else {
 416                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 417                                 callout_stop(&sc->sc_oftimeout);
 418                                 sc->sc_flags &= ~SC_OUTWAIT;
 419                         }
 420                 }
 421                 break;
 422
 423         case SLIOCGOUTFILL:
 424                 *(int *)data = sc->sc_outfill / hz;
 425                 break;
 426
 427         default:
 428                 crit_exit();
 429                 return (ENOIOCTL);
 430         }
 431         crit_exit();
 432         return (0);
 433 }
 434
 435 /*
 436  * Queue a packet.  Start transmission if not active.
 437  * Compression happens in slstart; if we do it here, IP TOS
 438  * will cause us to not compress "background" packets, because
 439  * ordering gets trashed.  It can be done for all packets in slstart.
 440  */
 441 static int
 442 sloutput_serialized(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 443                     struct rtentry *rtp)
 444 {
 445         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 446         struct ip *ip;
 447         int error;
 448         struct altq_pktattr pktattr;
 449
 450         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 451
 452         /*
 453          * `Cannot happen' (see slioctl).  Someday we will extend
 454          * the line protocol to support other address families.
 455          */
 456         if (dst->sa_family != AF_INET) {
 457                 kprintf("%s: af%d not supported\n", sc->sc_if.if_xname,
 458                         dst->sa_family);
 459                 m_freem(m);
 460                 sc->sc_if.if_noproto++;
 461                 return (EAFNOSUPPORT);
 462         }
 463
 464         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 465                 m_freem(m);
 466                 return (ENETDOWN);
 467         }
 468         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 469                 m_freem(m);
 470                 return (EHOSTUNREACH);
 471         }
 472         ip = mtod(m, struct ip *);
 473         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 474                 m_freem(m);
 475                 return (ENETRESET);             /* XXX ? */
 476         }
 477
 478         crit_enter();
 479
 480         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 481                 if (IF_QFULL(&sc->sc_fastq)) {
 482                         IF_DROP(&sc->sc_fastq);
 483                         m_freem(m);
 484                         error = ENOBUFS;
 485                 } else {
 486                         IF_ENQUEUE(&sc->sc_fastq, m);
 487                         error = 0;
 488                 }
 489         } else {
 490                 error = ifq_enqueue(&sc->sc_if.if_snd, m, &pktattr);
 491         }
 492         if (error) {
 493                 sc->sc_if.if_oerrors++;
 494                 crit_exit();
 495                 return (error);
 496         }
 497         if (sc->sc_ttyp->t_outq.c_cc == 0)
 498                 slstart(sc->sc_ttyp);
 499         crit_exit();
 500         return (0);
 501 }
 502
 503 static int
 504 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 505          struct rtentry *rtp)
 506 {
 507         int error;
 508
 509         lwkt_serialize_enter(ifp->if_serializer);
 510         error = sloutput_serialized(ifp, m, dst, rtp);
 511         lwkt_serialize_exit(ifp->if_serializer);
 512
 513         return error;
 514 }
 515
 516 /*
 517  * Start output on interface.  Get another datagram
 518  * to send from the interface queue and map it to
 519  * the interface before starting output.
 520  */
 521 static int
 522 slstart(struct tty *tp)
 523 {
 524         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 525         struct mbuf *m;
 526         u_char *cp;
 527         struct ip *ip;
 528         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 529         int len = 0;
 530
 531         for (;;) {
 532                 /*
 533                  * Call output process whether or not there is more in the
 534                  * output queue.  We are being called in lieu of ttstart
 535                  * and must do what it would.
 536                  */
 537                 (*tp->t_oproc)(tp);
 538
 539                 if (tp->t_outq.c_cc != 0) {
 540                         if (sc != NULL)
 541                                 sc->sc_flags &= ~SC_OUTWAIT;
 542                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 543                                 return 0;
 544                 }
 545
 546                 /*
 547                  * This happens briefly when the line shuts down.
 548                  */
 549                 if (sc == NULL)
 550                         return 0;
 551
 552                 /*
 553                  * Get a packet and send it to the interface.
 554                  */
 555                 crit_enter();
 556                 IF_DEQUEUE(&sc->sc_fastq, m);
 557                 if (m)
 558                         sc->sc_if.if_omcasts++;         /* XXX */
 559                 else
 560                         m = ifq_dequeue(&sc->sc_if.if_snd, NULL);
 561                 crit_exit();
 562                 if (m == NULL)
 563                         return 0;
 564
 565                 /*
 566                  * We do the header compression here rather than in sloutput
 567                  * because the packets will be out of order if we are using TOS
 568                  * queueing, and the connection id compression will get
 569                  * munged when this happens.
 570                  */
 571                 if (sc->sc_if.if_bpf) {
 572                         /*
 573                          * We need to save the TCP/IP header before it's
 574                          * compressed.  To avoid complicated code, we just
 575                          * copy the entire packet into a stack buffer (since
 576                          * this is a serial line, packets should be short
 577                          * and/or the copy should be negligible cost compared
 578                          * to the packet transmission time).
 579                          */
 580                         struct mbuf *m1 = m;
 581                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 582
 583                         len = 0;
 584                         do {
 585                                 int mlen = m1->m_len;
 586
 587                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 588                                 cp += mlen;
 589                                 len += mlen;
 590                         } while ((m1 = m1->m_next) != NULL);
 591                 }
 592                 ip = mtod(m, struct ip *);
 593                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 594                         if (sc->sc_if.if_flags & SC_COMPRESS)
 595                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 596                                     &sc->sc_comp, 1);
 597                 }
 598                 if (sc->sc_if.if_bpf) {
 599                         /*
 600                          * Put the SLIP pseudo-"link header" in place.  The
 601                          * compressed header is now at the beginning of the
 602                          * mbuf.
 603                          */
 604                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 605                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 606                         bpf_tap(sc->sc_if.if_bpf, bpfbuf, len + SLIP_HDRLEN);
 607                 }
 608
 609                 /*
 610                  * If system is getting low on clists, just flush our
 611                  * output queue (if the stuff was important, it'll get
 612                  * retransmitted). Note that SLTMAX is used instead of
 613                  * the current if_mtu setting because connections that
 614                  * have already been established still use the original
 615                  * (possibly larger) mss.
 616                  */
 617                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 618                         m_freem(m);
 619                         sc->sc_if.if_collisions++;
 620                         continue;
 621                 }
 622
 623                 sc->sc_flags &= ~SC_OUTWAIT;
 624                 /*
 625                  * The extra FRAME_END will start up a new packet, and thus
 626                  * will flush any accumulated garbage.  We do this whenever
 627                  * the line may have been idle for some time.
 628                  */
 629                 if (tp->t_outq.c_cc == 0) {
 630                         ++sc->sc_if.if_obytes;
 631                         clist_putc(FRAME_END, &tp->t_outq);
 632                 }
 633
 634                 while (m) {
 635                         u_char *ep;
 636
 637                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 638                         while (cp < ep) {
 639                                 /*
 640                                  * Find out how many bytes in the string we can
 641                                  * handle without doing something special.
 642                                  */
 643                                 u_char *bp = cp;
 644
 645                                 while (cp < ep) {
 646                                         switch (*cp++) {
 647                                         case FRAME_ESCAPE:
 648                                         case FRAME_END:
 649                                                 --cp;
 650                                                 goto out;
 651                                         }
 652                                 }
 653                                 out:
 654                                 if (cp > bp) {
 655                                         /*
 656                                          * Put n characters at once
 657                                          * into the tty output queue.
 658                                          */
 659                                         if (b_to_q((char *)bp, cp - bp,
 660                                             &tp->t_outq))
 661                                                 break;
 662                                         sc->sc_if.if_obytes += cp - bp;
 663                                 }
 664                                 /*
 665                                  * If there are characters left in the mbuf,
 666                                  * the first one must be special..
 667                                  * Put it out in a different form.
 668                                  */
 669                                 if (cp < ep) {
 670                                         if (clist_putc(FRAME_ESCAPE, &tp->t_outq))
 671                                                 break;
 672                                         if (clist_putc(*cp++ == FRAME_ESCAPE ?
 673                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 674                                            &tp->t_outq)) {
 675                                                 clist_unputc(&tp->t_outq);
 676                                                 break;
 677                                         }
 678                                         sc->sc_if.if_obytes += 2;
 679                                 }
 680                         }
 681                         m = m_free(m);
 682                 }
 683
 684                 if (clist_putc(FRAME_END, &tp->t_outq)) {
 685                         /*
 686                          * Not enough room.  Remove a char to make room
 687                          * and end the packet normally.
 688                          * If you get many collisions (more than one or two
 689                          * a day) you probably do not have enough clists
 690                          * and you should increase "nclist" in param.c.
 691                          */
 692                         clist_unputc(&tp->t_outq);
 693                         clist_putc(FRAME_END, &tp->t_outq);
 694                         sc->sc_if.if_collisions++;
 695                 } else {
 696                         ++sc->sc_if.if_obytes;
 697                         sc->sc_if.if_opackets++;
 698                 }
 699         }
 700         return 0;
 701 }
 702
 703 /*
 704  * Copy data buffer to mbuf chain; add ifnet pointer.
 705  */
 706 static struct mbuf *
 707 sl_btom(struct sl_softc *sc, int len)
 708 {
 709         struct mbuf *m;
 710
 711         if (len >= MCLBYTES)
 712                 return (NULL);
 713
 714         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 715         if (m == NULL)
 716                 return (NULL);
 717
 718         /*
 719          * If we have more than MHLEN bytes, it's cheaper to
 720          * queue the cluster we just filled & allocate a new one
 721          * for the input buffer.  Otherwise, fill the mbuf we
 722          * allocated above.  Note that code in the input routine
 723          * guarantees that packet will fit in a cluster.
 724          */
 725         if (len >= MHLEN) {
 726                 MCLGET(m, MB_DONTWAIT);
 727                 if ((m->m_flags & M_EXT) == 0) {
 728                         /*
 729                          * we couldn't get a cluster - if memory's this
 730                          * low, it's time to start dropping packets.
 731                          */
 732                         m_free(m);
 733                         return (NULL);
 734                 }
 735         }
 736         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 737         m->m_len = len;
 738         m->m_pkthdr.len = len;
 739         m->m_pkthdr.rcvif = &sc->sc_if;
 740         return (m);
 741 }
 742
 743 /*
 744  * tty interface receiver interrupt.
 745  */
 746 static int
 747 slinput(int c, struct tty *tp)
 748 {
 749         struct sl_softc *sc;
 750         struct mbuf *m;
 751         int len;
 752         u_char chdr[CHDR_LEN];
 753
 754         tk_nin++;
 755         sc = (struct sl_softc *)tp->t_sc;
 756         if (sc == NULL)
 757                 return 0;
 758         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 759                 sc->sc_flags |= SC_ERROR;
 760                 return 0;
 761         }
 762         c &= TTY_CHARMASK;
 763
 764         ++sc->sc_if.if_ibytes;
 765
 766         if (sc->sc_if.if_flags & IFF_DEBUG) {
 767                 if (c == ABT_ESC) {
 768                         /*
 769                          * If we have a previous abort, see whether
 770                          * this one is within the time limit.
 771                          */
 772                         if (sc->sc_abortcount &&
 773                             time_second >= sc->sc_starttime + ABT_WINDOW)
 774                                 sc->sc_abortcount = 0;
 775                         /*
 776                          * If we see an abort after "idle" time, count it;
 777                          * record when the first abort escape arrived.
 778                          */
 779                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 780                                 if (++sc->sc_abortcount == 1)
 781                                         sc->sc_starttime = time_second;
 782                                 if (sc->sc_abortcount >= ABT_COUNT) {
 783                                         slclose(tp,0);
 784                                         return 0;
 785                                 }
 786                         }
 787                 } else
 788                         sc->sc_abortcount = 0;
 789                 sc->sc_lasttime = time_second;
 790         }
 791
 792         switch (c) {
 793
 794         case TRANS_FRAME_ESCAPE:
 795                 if (sc->sc_escape)
 796                         c = FRAME_ESCAPE;
 797                 break;
 798
 799         case TRANS_FRAME_END:
 800                 if (sc->sc_escape)
 801                         c = FRAME_END;
 802                 break;
 803
 804         case FRAME_ESCAPE:
 805                 sc->sc_escape = 1;
 806                 return 0;
 807
 808         case FRAME_END:
 809                 sc->sc_flags &= ~SC_KEEPALIVE;
 810                 if(sc->sc_flags & SC_ERROR) {
 811                         sc->sc_flags &= ~SC_ERROR;
 812                         goto newpack;
 813                 }
 814                 len = sc->sc_mp - sc->sc_buf;
 815                 if (len < 3)
 816                         /* less than min length packet - ignore */
 817                         goto newpack;
 818
 819                 if (sc->sc_if.if_bpf) {
 820                         /*
 821                          * Save the compressed header, so we
 822                          * can tack it on later.  Note that we
 823                          * will end up copying garbage in some
 824                          * cases but this is okay.  We remember
 825                          * where the buffer started so we can
 826                          * compute the new header length.
 827                          */
 828                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 829                 }
 830
 831                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 832                         if (c & 0x80)
 833                                 c = TYPE_COMPRESSED_TCP;
 834                         else if (c == TYPE_UNCOMPRESSED_TCP)
 835                                 *sc->sc_buf &= 0x4f; /* XXX */
 836                         /*
 837                          * We've got something that's not an IP packet.
 838                          * If compression is enabled, try to decompress it.
 839                          * Otherwise, if `auto-enable' compression is on and
 840                          * it's a reasonable packet, decompress it and then
 841                          * enable compression.  Otherwise, drop it.
 842                          */
 843                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 844                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 845                                                         (u_int)c, &sc->sc_comp);
 846                                 if (len <= 0)
 847                                         goto error;
 848                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 849                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 850                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 851                                                         (u_int)c, &sc->sc_comp);
 852                                 if (len <= 0)
 853                                         goto error;
 854                                 sc->sc_if.if_flags |= SC_COMPRESS;
 855                         } else
 856                                 goto error;
 857                 }
 858                 if (sc->sc_if.if_bpf) {
 859                         /*
 860                          * Put the SLIP pseudo-"link header" in place.
 861                          * We couldn't do this any earlier since
 862                          * decompression probably moved the buffer
 863                          * pointer.  Then, invoke BPF.
 864                          */
 865                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 866
 867                         hp[SLX_DIR] = SLIPDIR_IN;
 868                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 869                         bpf_tap(sc->sc_if.if_bpf, hp, len + SLIP_HDRLEN);
 870                 }
 871                 m = sl_btom(sc, len);
 872                 if (m == NULL)
 873                         goto error;
 874
 875                 sc->sc_if.if_ipackets++;
 876
 877                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 878                         m_freem(m);
 879                         goto newpack;
 880                 }
 881
 882                 if (netisr_queue(NETISR_IP, m)) {
 883                         sc->sc_if.if_ierrors++;
 884                         sc->sc_if.if_iqdrops++;
 885                 }
 886
 887                 goto newpack;
 888         }
 889         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 890                 *sc->sc_mp++ = c;
 891                 sc->sc_escape = 0;
 892                 return 0;
 893         }
 894
 895         /* can't put lower; would miss an extra frame */
 896         sc->sc_flags |= SC_ERROR;
 897
 898 error:
 899         sc->sc_if.if_ierrors++;
 900 newpack:
 901         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 902         sc->sc_escape = 0;
 903         return 0;
 904 }
 905
 906 /*
 907  * Process an ioctl request.
 908  */
 909 static int
 910 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 911 {
 912         struct ifaddr *ifa = (struct ifaddr *)data;
 913         struct ifreq *ifr = (struct ifreq *)data;
 914         int error = 0;
 915
 916         crit_enter();
 917
 918         switch (cmd) {
 919
 920         case SIOCSIFFLAGS:
 921                 /*
 922                  * if.c will set the interface up even if we
 923                  * don't want it to.
 924                  */
 925                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 926                         ifp->if_flags &= ~IFF_UP;
 927                 }
 928                 break;
 929         case SIOCSIFADDR:
 930                 /*
 931                  * This is "historical" - set the interface up when
 932                  * setting the address.
 933                  */
 934                 if (ifa->ifa_addr->sa_family == AF_INET) {
 935                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 936                                 ifp->if_flags |= IFF_UP;
 937                 } else {
 938                         error = EAFNOSUPPORT;
 939                 }
 940                 break;
 941
 942         case SIOCSIFDSTADDR:
 943                 if (ifa->ifa_addr->sa_family != AF_INET)
 944                         error = EAFNOSUPPORT;
 945                 break;
 946
 947         case SIOCADDMULTI:
 948         case SIOCDELMULTI:
 949                 break;
 950
 951         case SIOCSIFMTU:
 952                 /*
 953                  * Set the interface MTU.
 954                  */
 955                 if (ifr->ifr_mtu > SLTMAX)
 956                         error = EINVAL;
 957                 else {
 958                         struct tty *tp;
 959
 960                         ifp->if_mtu = ifr->ifr_mtu;
 961                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 962                         if (tp != NULL)
 963                                 clist_alloc_cblocks(&tp->t_outq,
 964                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 965                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 966                 }
 967                 break;
 968
 969         default:
 970                 error = EINVAL;
 971         }
 972
 973         crit_exit();
 974         return (error);
 975 }
 976
 977 static void
 978 sl_keepalive(void *chan)
 979 {
 980         struct sl_softc *sc = chan;
 981
 982         if (sc->sc_keepalive) {
 983                 if (sc->sc_flags & SC_KEEPALIVE)
 984                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 985                 else
 986                         sc->sc_flags |= SC_KEEPALIVE;
 987                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 988                                 sl_keepalive, sc);
 989         } else {
 990                 sc->sc_flags &= ~SC_KEEPALIVE;
 991         }
 992 }
 993
 994 static void
 995 sl_outfill(void *chan)
 996 {
 997         struct sl_softc *sc = chan;
 998         struct tty *tp = sc->sc_ttyp;
 999
1000         if (sc->sc_outfill && tp != NULL) {
1001                 if (sc->sc_flags & SC_OUTWAIT) {
1002                         crit_enter();
1003                         ++sc->sc_if.if_obytes;
1004                         clist_putc(FRAME_END, &tp->t_outq);
1005                         (*tp->t_oproc)(tp);
1006                         crit_exit();
1007                 } else
1008                         sc->sc_flags |= SC_OUTWAIT;
1009                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1010                                 sl_outfill, sc);
1011         } else {
1012                 sc->sc_flags &= ~SC_OUTWAIT;
1013         }
1014 }