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 1.23 2006/01/14 11:05:18 swildner 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 #ifdef __i386__
 109 #include <i386/isa/intr_machdep.h>
 110 #endif
 111
 112 static void slattach (void *);
 113 PSEUDO_SET(slattach, if_sl);
 114
 115 /*
 116  * SLRMAX is a hard limit on input packet size.  To simplify the code
 117  * and improve performance, we require that packets fit in an mbuf
 118  * cluster, and if we get a compressed packet, there's enough extra
 119  * room to expand the header into a max length tcp/ip header (128
 120  * bytes).  So, SLRMAX can be at most
 121  *      MCLBYTES - 128
 122  *
 123  * SLMTU is the default transmit MTU. The transmit MTU should be kept
 124  * small enough so that interactive use doesn't suffer, but large
 125  * enough to provide good performance. 552 is a good choice for SLMTU
 126  * because it is high enough to not fragment TCP packets being routed
 127  * through this host. Packet fragmentation is bad with SLIP because
 128  * fragment headers aren't compressed. The previous assumptions about
 129  * the best MTU value don't really hold when using modern modems with
 130  * BTLZ data compression because the modem buffers play a much larger
 131  * role in interactive performance than the MTU. The MTU can be changed
 132  * at any time to suit the specific environment with ifconfig(8), and
 133  * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 134  * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 135  * handles this better).
 136  *
 137  * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 138  * of us (i.e., in clists waiting to be picked up by the tty output
 139  * interrupt).  If we queue a lot of data downstream, it's immune to
 140  * our t.o.s. queuing.
 141  * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 142  * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 143  * wait is dependent on the ftp window size but that's typically
 144  * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 145  * the cost (in idle time on the wire) of the tty driver running
 146  * off the end of its clists & having to call back slstart for a
 147  * new packet.  For a tty interface with any buffering at all, this
 148  * cost will be zero.  Even with a totally brain dead interface (like
 149  * the one on a typical workstation), the cost will be <= 1 character
 150  * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 151  * at most 1% while maintaining good interactive response.
 152  */
 153 #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
 154 #define SLRMAX          (MCLBYTES - BUFOFFSET)
 155 #define SLBUFSIZE       (SLRMAX + BUFOFFSET)
 156 #ifndef SLMTU
 157 #define SLMTU           552             /* default MTU */
 158 #endif
 159 #define SLTMAX          1500            /* maximum MTU */
 160 #define SLIP_HIWAT      roundup(50,CBSIZE)
 161 #define CLISTRESERVE    1024            /* Can't let clists get too low */
 162
 163 /*
 164  * SLIP ABORT ESCAPE MECHANISM:
 165  *      (inspired by HAYES modem escape arrangement)
 166  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 167  *      within window time signals a "soft" exit from slip mode by remote end
 168  *      if the IFF_DEBUG flag is on.
 169  */
 170 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
 171 #define ABT_IDLE        1       /* in seconds - idle before an escape */
 172 #define ABT_COUNT       3       /* count of escapes for abort */
 173 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
 174
 175 static struct sl_softc sl_softc[NSL];
 176
 177 #define FRAME_END               0xc0            /* Frame End */
 178 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
 179 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
 180 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
 181
 182 static int slinit (struct sl_softc *);
 183 static struct mbuf *sl_btom (struct sl_softc *, int);
 184 static timeout_t sl_keepalive;
 185 static timeout_t sl_outfill;
 186 static int      slclose (struct tty *,int);
 187 static int      slinput (int, struct tty *);
 188 static int      slioctl (struct ifnet *, u_long, caddr_t, struct ucred *);
 189 static int      sltioctl (struct tty *, u_long, caddr_t, int, struct thread *);
 190 static int      slopen (dev_t, struct tty *);
 191 static int      sloutput (struct ifnet *,
 192             struct mbuf *, struct sockaddr *, struct rtentry *);
 193 static int      slstart (struct tty *);
 194
 195 static struct linesw slipdisc = {
 196         slopen,         slclose,        l_noread,       l_nowrite,
 197         sltioctl,       slinput,        slstart,        ttymodem,
 198         FRAME_END
 199 };
 200
 201 /*
 202  * Called from boot code to establish sl interfaces.
 203  */
 204 static void
 205 slattach(void *dummy)
 206 {
 207         struct sl_softc *sc;
 208         int i = 0;
 209
 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(&sc->sc_oftimeout);
 230                 callout_init(&sc->sc_katimeout);
 231                 if_attach(&sc->sc_if, NULL);
 232                 bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
 233         }
 234 }
 235
 236 static int
 237 slinit(struct sl_softc *sc)
 238 {
 239         if (sc->sc_ep == NULL)
 240                 sc->sc_ep = malloc(SLBUFSIZE, M_DEVBUF, M_WAITOK);
 241         sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 242         sc->sc_mp = sc->sc_buf;
 243         sl_compress_init(&sc->sc_comp, -1);
 244         return (1);
 245 }
 246
 247 /*
 248  * Line specific open routine.
 249  * Attach the given tty to the first available sl unit.
 250  */
 251 /* ARGSUSED */
 252 static int
 253 slopen(dev_t dev, struct tty *tp)
 254 {
 255         struct sl_softc *sc;
 256         int nsl;
 257         int error;
 258         struct thread *td = curthread;  /* XXX */
 259
 260         error = suser(td);
 261         if (error)
 262                 return (error);
 263
 264         if (tp->t_line == SLIPDISC)
 265                 return (0);
 266
 267         for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++)
 268                 if (sc->sc_ttyp == NULL && !(sc->sc_flags & SC_STATIC)) {
 269                         if (slinit(sc) == 0)
 270                                 return (ENOBUFS);
 271                         tp->t_sc = (caddr_t)sc;
 272                         sc->sc_ttyp = tp;
 273                         sc->sc_if.if_baudrate = tp->t_ospeed;
 274                         ttyflush(tp, FREAD | FWRITE);
 275
 276                         tp->t_line = SLIPDISC;
 277                         /*
 278                          * We don't use t_canq or t_rawq, so reduce their
 279                          * cblock resources to 0.  Reserve enough cblocks
 280                          * for t_outq to guarantee that we can fit a full
 281                          * packet if the SLIP_HIWAT check allows slstart()
 282                          * to loop.  Use the same value for the cblock
 283                          * limit since the reserved blocks should always
 284                          * be enough.  Reserving cblocks probably makes
 285                          * the CLISTRESERVE check unnecessary and wasteful.
 286                          */
 287                         clist_alloc_cblocks(&tp->t_canq, 0, 0);
 288                         clist_alloc_cblocks(&tp->t_outq,
 289                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 290                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 291                         clist_alloc_cblocks(&tp->t_rawq, 0, 0);
 292
 293                         crit_enter();
 294                         if_up(&sc->sc_if);
 295                         crit_exit();
 296                         return (0);
 297                 }
 298         return (ENXIO);
 299 }
 300
 301 /*
 302  * Line specific close routine.
 303  * Detach the tty from the sl unit.
 304  */
 305 static int
 306 slclose(struct tty *tp, int flag)
 307 {
 308         struct sl_softc *sc;
 309
 310         ttyflush(tp, FREAD | FWRITE);
 311         crit_enter();
 312
 313         clist_free_cblocks(&tp->t_outq);
 314         tp->t_line = 0;
 315         sc = (struct sl_softc *)tp->t_sc;
 316         if (sc != NULL) {
 317                 if (sc->sc_outfill) {
 318                         sc->sc_outfill = 0;
 319                         callout_stop(&sc->sc_oftimeout);
 320                 }
 321                 if (sc->sc_keepalive) {
 322                         sc->sc_keepalive = 0;
 323                         callout_stop(&sc->sc_katimeout);
 324                 }
 325                 if_down(&sc->sc_if);
 326                 sc->sc_flags &= SC_STATIC;
 327                 sc->sc_ttyp = NULL;
 328                 tp->t_sc = NULL;
 329                 if (sc->sc_ep) {
 330                         free(sc->sc_ep, M_DEVBUF);
 331                         sc->sc_ep = NULL;
 332                 }
 333                 sc->sc_mp = 0;
 334                 sc->sc_buf = 0;
 335         }
 336         crit_exit();
 337         return 0;
 338 }
 339
 340 /*
 341  * Line specific (tty) ioctl routine.
 342  * Provide a way to get the sl unit number.
 343  */
 344 /* ARGSUSED */
 345 static int
 346 sltioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *p)
 347 {
 348         struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc, *tmpnc;
 349         int nsl;
 350
 351         crit_enter();
 352
 353         switch (cmd) {
 354         case SLIOCGUNIT:
 355                 *(int *)data = sc->sc_if.if_dunit;
 356                 break;
 357
 358         case SLIOCSUNIT:
 359                 if (sc->sc_if.if_dunit != *(u_int *)data) {
 360                         for (nsl = NSL, nc = sl_softc; --nsl >= 0; nc++) {
 361                                 if (   nc->sc_if.if_dunit == *(u_int *)data
 362                                     && nc->sc_ttyp == NULL
 363                                    ) {
 364                                         tmpnc = malloc(sizeof *tmpnc, M_TEMP,
 365                                                        M_WAITOK);
 366                                         *tmpnc = *nc;
 367                                         *nc = *sc;
 368                                         nc->sc_if = tmpnc->sc_if;
 369                                         tmpnc->sc_if = sc->sc_if;
 370                                         *sc = *tmpnc;
 371                                         free(tmpnc, M_TEMP);
 372                                         if (sc->sc_if.if_flags & IFF_UP) {
 373                                                 if_down(&sc->sc_if);
 374                                                 if (!(nc->sc_if.if_flags & IFF_UP))
 375                                                         if_up(&nc->sc_if);
 376                                         } else if (nc->sc_if.if_flags & IFF_UP)
 377                                                 if_down(&nc->sc_if);
 378                                         sc->sc_flags &= ~SC_STATIC;
 379                                         sc->sc_flags |= (nc->sc_flags & SC_STATIC);
 380                                         tp->t_sc = sc = nc;
 381                                         clist_alloc_cblocks(&tp->t_outq,
 382                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
 383                                             SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
 384                                         sl_compress_init(&sc->sc_comp, -1);
 385                                         goto slfound;
 386                                 }
 387                         }
 388                         crit_exit();
 389                         return (ENXIO);
 390                 }
 391         slfound:
 392                 sc->sc_flags |= SC_STATIC;
 393                 break;
 394
 395         case SLIOCSKEEPAL:
 396                 sc->sc_keepalive = *(u_int *)data * hz;
 397                 if (sc->sc_keepalive) {
 398                         sc->sc_flags |= SC_KEEPALIVE;
 399                         callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 400                                         sl_keepalive, sc);
 401                 } else {
 402                         if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
 403                                 callout_stop(&sc->sc_katimeout);
 404                                 sc->sc_flags &= ~SC_KEEPALIVE;
 405                         }
 406                 }
 407                 break;
 408
 409         case SLIOCGKEEPAL:
 410                 *(int *)data = sc->sc_keepalive / hz;
 411                 break;
 412
 413         case SLIOCSOUTFILL:
 414                 sc->sc_outfill = *(u_int *)data * hz;
 415                 if (sc->sc_outfill) {
 416                         sc->sc_flags |= SC_OUTWAIT;
 417                         callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
 418                                         sl_outfill, sc);
 419                 } else {
 420                         if ((sc->sc_flags & SC_OUTWAIT) != 0) {
 421                                 callout_stop(&sc->sc_oftimeout);
 422                                 sc->sc_flags &= ~SC_OUTWAIT;
 423                         }
 424                 }
 425                 break;
 426
 427         case SLIOCGOUTFILL:
 428                 *(int *)data = sc->sc_outfill / hz;
 429                 break;
 430
 431         default:
 432                 crit_exit();
 433                 return (ENOIOCTL);
 434         }
 435         crit_exit();
 436         return (0);
 437 }
 438
 439 /*
 440  * Queue a packet.  Start transmission if not active.
 441  * Compression happens in slstart; if we do it here, IP TOS
 442  * will cause us to not compress "background" packets, because
 443  * ordering gets trashed.  It can be done for all packets in slstart.
 444  */
 445 static int
 446 sloutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 447          struct rtentry *rtp)
 448 {
 449         struct sl_softc *sc = &sl_softc[ifp->if_dunit];
 450         struct ip *ip;
 451         int error;
 452         struct altq_pktattr pktattr;
 453
 454         ifq_classify(&ifp->if_snd, m, dst->sa_family, &pktattr);
 455
 456         /*
 457          * `Cannot happen' (see slioctl).  Someday we will extend
 458          * the line protocol to support other address families.
 459          */
 460         if (dst->sa_family != AF_INET) {
 461                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
 462                         dst->sa_family);
 463                 m_freem(m);
 464                 sc->sc_if.if_noproto++;
 465                 return (EAFNOSUPPORT);
 466         }
 467
 468         if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
 469                 m_freem(m);
 470                 return (ENETDOWN);
 471         }
 472         if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
 473                 m_freem(m);
 474                 return (EHOSTUNREACH);
 475         }
 476         ip = mtod(m, struct ip *);
 477         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
 478                 m_freem(m);
 479                 return (ENETRESET);             /* XXX ? */
 480         }
 481
 482         crit_enter();
 483
 484         if ((ip->ip_tos & IPTOS_LOWDELAY) && !ifq_is_enabled(&sc->sc_if.if_snd)) {
 485                 if (IF_QFULL(&sc->sc_fastq)) {
 486                         IF_DROP(&sc->sc_fastq);
 487                         m_freem(m);
 488                         error = ENOBUFS;
 489                 } else {
 490                         IF_ENQUEUE(&sc->sc_fastq, m);
 491                         error = 0;
 492                 }
 493         } else {
 494                 lwkt_serialize_enter(sc->sc_if.if_serializer);
 495                 error = ifq_enqueue(&sc->sc_if.if_snd, m, &pktattr);
 496                 lwkt_serialize_enter(sc->sc_if.if_serializer);
 497         }
 498         if (error) {
 499                 sc->sc_if.if_oerrors++;
 500                 crit_exit();
 501                 return (error);
 502         }
 503         if (sc->sc_ttyp->t_outq.c_cc == 0)
 504                 slstart(sc->sc_ttyp);
 505         crit_exit();
 506         return (0);
 507 }
 508
 509 /*
 510  * Start output on interface.  Get another datagram
 511  * to send from the interface queue and map it to
 512  * the interface before starting output.
 513  */
 514 static int
 515 slstart(struct tty *tp)
 516 {
 517         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
 518         struct mbuf *m;
 519         u_char *cp;
 520         struct ip *ip;
 521         u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
 522         int len = 0;
 523
 524         for (;;) {
 525                 /*
 526                  * Call output process whether or not there is more in the
 527                  * output queue.  We are being called in lieu of ttstart
 528                  * and must do what it would.
 529                  */
 530                 (*tp->t_oproc)(tp);
 531
 532                 if (tp->t_outq.c_cc != 0) {
 533                         if (sc != NULL)
 534                                 sc->sc_flags &= ~SC_OUTWAIT;
 535                         if (tp->t_outq.c_cc > SLIP_HIWAT)
 536                                 return 0;
 537                 }
 538
 539                 /*
 540                  * This happens briefly when the line shuts down.
 541                  */
 542                 if (sc == NULL)
 543                         return 0;
 544
 545                 /*
 546                  * Get a packet and send it to the interface.
 547                  */
 548                 crit_enter();
 549                 IF_DEQUEUE(&sc->sc_fastq, m);
 550                 if (m)
 551                         sc->sc_if.if_omcasts++;         /* XXX */
 552                 else
 553                         m = ifq_dequeue(&sc->sc_if.if_snd, NULL);
 554                 crit_exit();
 555                 if (m == NULL)
 556                         return 0;
 557
 558                 /*
 559                  * We do the header compression here rather than in sloutput
 560                  * because the packets will be out of order if we are using TOS
 561                  * queueing, and the connection id compression will get
 562                  * munged when this happens.
 563                  */
 564                 if (sc->sc_if.if_bpf) {
 565                         /*
 566                          * We need to save the TCP/IP header before it's
 567                          * compressed.  To avoid complicated code, we just
 568                          * copy the entire packet into a stack buffer (since
 569                          * this is a serial line, packets should be short
 570                          * and/or the copy should be negligible cost compared
 571                          * to the packet transmission time).
 572                          */
 573                         struct mbuf *m1 = m;
 574                         u_char *cp = bpfbuf + SLIP_HDRLEN;
 575
 576                         len = 0;
 577                         do {
 578                                 int mlen = m1->m_len;
 579
 580                                 bcopy(mtod(m1, caddr_t), cp, mlen);
 581                                 cp += mlen;
 582                                 len += mlen;
 583                         } while ((m1 = m1->m_next) != NULL);
 584                 }
 585                 ip = mtod(m, struct ip *);
 586                 if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
 587                         if (sc->sc_if.if_flags & SC_COMPRESS)
 588                                 *mtod(m, u_char *) |= sl_compress_tcp(m, ip,
 589                                     &sc->sc_comp, 1);
 590                 }
 591                 if (sc->sc_if.if_bpf) {
 592                         /*
 593                          * Put the SLIP pseudo-"link header" in place.  The
 594                          * compressed header is now at the beginning of the
 595                          * mbuf.
 596                          */
 597                         bpfbuf[SLX_DIR] = SLIPDIR_OUT;
 598                         bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
 599                         bpf_tap(sc->sc_if.if_bpf, bpfbuf, len + SLIP_HDRLEN);
 600                 }
 601
 602                 /*
 603                  * If system is getting low on clists, just flush our
 604                  * output queue (if the stuff was important, it'll get
 605                  * retransmitted). Note that SLTMAX is used instead of
 606                  * the current if_mtu setting because connections that
 607                  * have already been established still use the original
 608                  * (possibly larger) mss.
 609                  */
 610                 if (cfreecount < CLISTRESERVE + SLTMAX) {
 611                         m_freem(m);
 612                         sc->sc_if.if_collisions++;
 613                         continue;
 614                 }
 615
 616                 sc->sc_flags &= ~SC_OUTWAIT;
 617                 /*
 618                  * The extra FRAME_END will start up a new packet, and thus
 619                  * will flush any accumulated garbage.  We do this whenever
 620                  * the line may have been idle for some time.
 621                  */
 622                 if (tp->t_outq.c_cc == 0) {
 623                         ++sc->sc_if.if_obytes;
 624                         putc(FRAME_END, &tp->t_outq);
 625                 }
 626
 627                 while (m) {
 628                         u_char *ep;
 629
 630                         cp = mtod(m, u_char *); ep = cp + m->m_len;
 631                         while (cp < ep) {
 632                                 /*
 633                                  * Find out how many bytes in the string we can
 634                                  * handle without doing something special.
 635                                  */
 636                                 u_char *bp = cp;
 637
 638                                 while (cp < ep) {
 639                                         switch (*cp++) {
 640                                         case FRAME_ESCAPE:
 641                                         case FRAME_END:
 642                                                 --cp;
 643                                                 goto out;
 644                                         }
 645                                 }
 646                                 out:
 647                                 if (cp > bp) {
 648                                         /*
 649                                          * Put n characters at once
 650                                          * into the tty output queue.
 651                                          */
 652                                         if (b_to_q((char *)bp, cp - bp,
 653                                             &tp->t_outq))
 654                                                 break;
 655                                         sc->sc_if.if_obytes += cp - bp;
 656                                 }
 657                                 /*
 658                                  * If there are characters left in the mbuf,
 659                                  * the first one must be special..
 660                                  * Put it out in a different form.
 661                                  */
 662                                 if (cp < ep) {
 663                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
 664                                                 break;
 665                                         if (putc(*cp++ == FRAME_ESCAPE ?
 666                                            TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
 667                                            &tp->t_outq)) {
 668                                                 unputc(&tp->t_outq);
 669                                                 break;
 670                                         }
 671                                         sc->sc_if.if_obytes += 2;
 672                                 }
 673                         }
 674                         m = m_free(m);
 675                 }
 676
 677                 if (putc(FRAME_END, &tp->t_outq)) {
 678                         /*
 679                          * Not enough room.  Remove a char to make room
 680                          * and end the packet normally.
 681                          * If you get many collisions (more than one or two
 682                          * a day) you probably do not have enough clists
 683                          * and you should increase "nclist" in param.c.
 684                          */
 685                         unputc(&tp->t_outq);
 686                         putc(FRAME_END, &tp->t_outq);
 687                         sc->sc_if.if_collisions++;
 688                 } else {
 689                         ++sc->sc_if.if_obytes;
 690                         sc->sc_if.if_opackets++;
 691                 }
 692         }
 693         return 0;
 694 }
 695
 696 /*
 697  * Copy data buffer to mbuf chain; add ifnet pointer.
 698  */
 699 static struct mbuf *
 700 sl_btom(struct sl_softc *sc, int len)
 701 {
 702         struct mbuf *m;
 703
 704         if (len >= MCLBYTES)
 705                 return (NULL);
 706
 707         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 708         if (m == NULL)
 709                 return (NULL);
 710
 711         /*
 712          * If we have more than MHLEN bytes, it's cheaper to
 713          * queue the cluster we just filled & allocate a new one
 714          * for the input buffer.  Otherwise, fill the mbuf we
 715          * allocated above.  Note that code in the input routine
 716          * guarantees that packet will fit in a cluster.
 717          */
 718         if (len >= MHLEN) {
 719                 MCLGET(m, MB_DONTWAIT);
 720                 if ((m->m_flags & M_EXT) == 0) {
 721                         /*
 722                          * we couldn't get a cluster - if memory's this
 723                          * low, it's time to start dropping packets.
 724                          */
 725                         m_free(m);
 726                         return (NULL);
 727                 }
 728         }
 729         bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
 730         m->m_len = len;
 731         m->m_pkthdr.len = len;
 732         m->m_pkthdr.rcvif = &sc->sc_if;
 733         return (m);
 734 }
 735
 736 /*
 737  * tty interface receiver interrupt.
 738  */
 739 static int
 740 slinput(int c, struct tty *tp)
 741 {
 742         struct sl_softc *sc;
 743         struct mbuf *m;
 744         int len;
 745         u_char chdr[CHDR_LEN];
 746
 747         tk_nin++;
 748         sc = (struct sl_softc *)tp->t_sc;
 749         if (sc == NULL)
 750                 return 0;
 751         if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
 752                 sc->sc_flags |= SC_ERROR;
 753                 return 0;
 754         }
 755         c &= TTY_CHARMASK;
 756
 757         ++sc->sc_if.if_ibytes;
 758
 759         if (sc->sc_if.if_flags & IFF_DEBUG) {
 760                 if (c == ABT_ESC) {
 761                         /*
 762                          * If we have a previous abort, see whether
 763                          * this one is within the time limit.
 764                          */
 765                         if (sc->sc_abortcount &&
 766                             time_second >= sc->sc_starttime + ABT_WINDOW)
 767                                 sc->sc_abortcount = 0;
 768                         /*
 769                          * If we see an abort after "idle" time, count it;
 770                          * record when the first abort escape arrived.
 771                          */
 772                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
 773                                 if (++sc->sc_abortcount == 1)
 774                                         sc->sc_starttime = time_second;
 775                                 if (sc->sc_abortcount >= ABT_COUNT) {
 776                                         slclose(tp,0);
 777                                         return 0;
 778                                 }
 779                         }
 780                 } else
 781                         sc->sc_abortcount = 0;
 782                 sc->sc_lasttime = time_second;
 783         }
 784
 785         switch (c) {
 786
 787         case TRANS_FRAME_ESCAPE:
 788                 if (sc->sc_escape)
 789                         c = FRAME_ESCAPE;
 790                 break;
 791
 792         case TRANS_FRAME_END:
 793                 if (sc->sc_escape)
 794                         c = FRAME_END;
 795                 break;
 796
 797         case FRAME_ESCAPE:
 798                 sc->sc_escape = 1;
 799                 return 0;
 800
 801         case FRAME_END:
 802                 sc->sc_flags &= ~SC_KEEPALIVE;
 803                 if(sc->sc_flags & SC_ERROR) {
 804                         sc->sc_flags &= ~SC_ERROR;
 805                         goto newpack;
 806                 }
 807                 len = sc->sc_mp - sc->sc_buf;
 808                 if (len < 3)
 809                         /* less than min length packet - ignore */
 810                         goto newpack;
 811
 812                 if (sc->sc_if.if_bpf) {
 813                         /*
 814                          * Save the compressed header, so we
 815                          * can tack it on later.  Note that we
 816                          * will end up copying garbage in some
 817                          * cases but this is okay.  We remember
 818                          * where the buffer started so we can
 819                          * compute the new header length.
 820                          */
 821                         bcopy(sc->sc_buf, chdr, CHDR_LEN);
 822                 }
 823
 824                 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
 825                         if (c & 0x80)
 826                                 c = TYPE_COMPRESSED_TCP;
 827                         else if (c == TYPE_UNCOMPRESSED_TCP)
 828                                 *sc->sc_buf &= 0x4f; /* XXX */
 829                         /*
 830                          * We've got something that's not an IP packet.
 831                          * If compression is enabled, try to decompress it.
 832                          * Otherwise, if `auto-enable' compression is on and
 833                          * it's a reasonable packet, decompress it and then
 834                          * enable compression.  Otherwise, drop it.
 835                          */
 836                         if (sc->sc_if.if_flags & SC_COMPRESS) {
 837                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 838                                                         (u_int)c, &sc->sc_comp);
 839                                 if (len <= 0)
 840                                         goto error;
 841                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
 842                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
 843                                 len = sl_uncompress_tcp(&sc->sc_buf, len,
 844                                                         (u_int)c, &sc->sc_comp);
 845                                 if (len <= 0)
 846                                         goto error;
 847                                 sc->sc_if.if_flags |= SC_COMPRESS;
 848                         } else
 849                                 goto error;
 850                 }
 851                 if (sc->sc_if.if_bpf) {
 852                         /*
 853                          * Put the SLIP pseudo-"link header" in place.
 854                          * We couldn't do this any earlier since
 855                          * decompression probably moved the buffer
 856                          * pointer.  Then, invoke BPF.
 857                          */
 858                         u_char *hp = sc->sc_buf - SLIP_HDRLEN;
 859
 860                         hp[SLX_DIR] = SLIPDIR_IN;
 861                         bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
 862                         bpf_tap(sc->sc_if.if_bpf, hp, len + SLIP_HDRLEN);
 863                 }
 864                 m = sl_btom(sc, len);
 865                 if (m == NULL)
 866                         goto error;
 867
 868                 sc->sc_if.if_ipackets++;
 869
 870                 if ((sc->sc_if.if_flags & IFF_UP) == 0) {
 871                         m_freem(m);
 872                         goto newpack;
 873                 }
 874
 875                 if (netisr_queue(NETISR_IP, m)) {
 876                         sc->sc_if.if_ierrors++;
 877                         sc->sc_if.if_iqdrops++;
 878                 }
 879
 880                 goto newpack;
 881         }
 882         if (sc->sc_mp < sc->sc_ep + SLBUFSIZE) {
 883                 *sc->sc_mp++ = c;
 884                 sc->sc_escape = 0;
 885                 return 0;
 886         }
 887
 888         /* can't put lower; would miss an extra frame */
 889         sc->sc_flags |= SC_ERROR;
 890
 891 error:
 892         sc->sc_if.if_ierrors++;
 893 newpack:
 894         sc->sc_mp = sc->sc_buf = sc->sc_ep + SLBUFSIZE - SLRMAX;
 895         sc->sc_escape = 0;
 896         return 0;
 897 }
 898
 899 /*
 900  * Process an ioctl request.
 901  */
 902 static int
 903 slioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
 904 {
 905         struct ifaddr *ifa = (struct ifaddr *)data;
 906         struct ifreq *ifr = (struct ifreq *)data;
 907         int error = 0;
 908
 909         crit_enter();
 910
 911         switch (cmd) {
 912
 913         case SIOCSIFFLAGS:
 914                 /*
 915                  * if.c will set the interface up even if we
 916                  * don't want it to.
 917                  */
 918                 if (sl_softc[ifp->if_dunit].sc_ttyp == NULL) {
 919                         ifp->if_flags &= ~IFF_UP;
 920                 }
 921                 break;
 922         case SIOCSIFADDR:
 923                 /*
 924                  * This is "historical" - set the interface up when
 925                  * setting the address.
 926                  */
 927                 if (ifa->ifa_addr->sa_family == AF_INET) {
 928                         if (sl_softc[ifp->if_dunit].sc_ttyp != NULL)
 929                                 ifp->if_flags |= IFF_UP;
 930                 } else {
 931                         error = EAFNOSUPPORT;
 932                 }
 933                 break;
 934
 935         case SIOCSIFDSTADDR:
 936                 if (ifa->ifa_addr->sa_family != AF_INET)
 937                         error = EAFNOSUPPORT;
 938                 break;
 939
 940         case SIOCADDMULTI:
 941         case SIOCDELMULTI:
 942                 break;
 943
 944         case SIOCSIFMTU:
 945                 /*
 946                  * Set the interface MTU.
 947                  */
 948                 if (ifr->ifr_mtu > SLTMAX)
 949                         error = EINVAL;
 950                 else {
 951                         struct tty *tp;
 952
 953                         ifp->if_mtu = ifr->ifr_mtu;
 954                         tp = sl_softc[ifp->if_dunit].sc_ttyp;
 955                         if (tp != NULL)
 956                                 clist_alloc_cblocks(&tp->t_outq,
 957                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1,
 958                                     SLIP_HIWAT + 2 * ifp->if_mtu + 1);
 959                 }
 960                 break;
 961
 962         default:
 963                 error = EINVAL;
 964         }
 965
 966         crit_exit();
 967         return (error);
 968 }
 969
 970 static void
 971 sl_keepalive(void *chan)
 972 {
 973         struct sl_softc *sc = chan;
 974
 975         if (sc->sc_keepalive) {
 976                 if (sc->sc_flags & SC_KEEPALIVE)
 977                         pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
 978                 else
 979                         sc->sc_flags |= SC_KEEPALIVE;
 980                 callout_reset(&sc->sc_katimeout, sc->sc_keepalive,
 981                                 sl_keepalive, sc);
 982         } else {
 983                 sc->sc_flags &= ~SC_KEEPALIVE;
 984         }
 985 }
 986
 987 static void
 988 sl_outfill(void *chan)
 989 {
 990         struct sl_softc *sc = chan;
 991         struct tty *tp = sc->sc_ttyp;
 992
 993         if (sc->sc_outfill && tp != NULL) {
 994                 if (sc->sc_flags & SC_OUTWAIT) {
 995                         crit_enter();
 996                         ++sc->sc_if.if_obytes;
 997                         putc(FRAME_END, &tp->t_outq);
 998                         (*tp->t_oproc)(tp);
 999                         crit_exit();
1000                 } else
1001                         sc->sc_flags |= SC_OUTWAIT;
1002                 callout_reset(&sc->sc_oftimeout, sc->sc_outfill,
1003                                 sl_outfill, sc);
1004         } else {
1005                 sc->sc_flags &= ~SC_OUTWAIT;
1006         }
1007 }