The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/if_sl.c

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    1 /*      $NetBSD: if_sl.c,v 1.136 2022/10/26 23:42:42 riastradh Exp $    */
    2 
    3 /*
    4  * Copyright (c) 1987, 1989, 1992, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  *      @(#)if_sl.c     8.9 (Berkeley) 1/9/95
   32  */
   33 
   34 /*
   35  * Serial Line interface
   36  *
   37  * Rick Adams
   38  * Center for Seismic Studies
   39  * 1300 N 17th Street, Suite 1450
   40  * Arlington, Virginia 22209
   41  * (703)276-7900
   42  * rick@seismo.ARPA
   43  * seismo!rick
   44  *
   45  * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
   46  * N.B.: this belongs in netinet, not net, the way it stands now.
   47  * Should have a link-layer type designation, but wouldn't be
   48  * backwards-compatible.
   49  *
   50  * Converted to 4.3BSD Beta by Chris Torek.
   51  * Other changes made at Berkeley, based in part on code by Kirk Smith.
   52  * W. Jolitz added slip abort.
   53  *
   54  * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
   55  * Added priority queuing for "interactive" traffic; hooks for TCP
   56  * header compression; ICMP filtering (at 2400 baud, some cretin
   57  * pinging you can use up all your bandwidth).  Made low clist behavior
   58  * more robust and slightly less likely to hang serial line.
   59  * Sped up a bunch of things.
   60  */
   61 
   62 #include <sys/cdefs.h>
   63 __KERNEL_RCSID(0, "$NetBSD: if_sl.c,v 1.136 2022/10/26 23:42:42 riastradh Exp $");
   64 
   65 #ifdef _KERNEL_OPT
   66 #include "opt_inet.h"
   67 #endif
   68 
   69 #include <sys/param.h>
   70 #include <sys/proc.h>
   71 #include <sys/malloc.h>
   72 #include <sys/mbuf.h>
   73 #include <sys/buf.h>
   74 #include <sys/dkstat.h>
   75 #include <sys/socket.h>
   76 #include <sys/ioctl.h>
   77 #include <sys/file.h>
   78 #include <sys/conf.h>
   79 #include <sys/tty.h>
   80 #include <sys/kernel.h>
   81 #include <sys/socketvar.h>
   82 #if __NetBSD__
   83 #include <sys/systm.h>
   84 #include <sys/kauth.h>
   85 #endif
   86 #include <sys/cpu.h>
   87 #include <sys/intr.h>
   88 #include <sys/device.h>
   89 #include <sys/module.h>
   90 
   91 #include <net/if.h>
   92 #include <net/if_types.h>
   93 #include <net/route.h>
   94 
   95 #ifdef INET
   96 #include <netinet/in.h>
   97 #include <netinet/in_systm.h>
   98 #include <netinet/in_var.h>
   99 #include <netinet/ip.h>
  100 #endif
  101 
  102 #include <net/slcompress.h>
  103 #include <net/if_slvar.h>
  104 #include <net/slip.h>
  105 #include <net/ppp_defs.h>
  106 #include <net/if_ppp.h>
  107 
  108 #include <sys/time.h>
  109 #include <net/bpf.h>
  110 
  111 #include "ioconf.h"
  112 
  113 /*
  114  * SLMAX is a hard limit on input packet size.  To simplify the code
  115  * and improve performance, we require that packets fit in an mbuf
  116  * cluster, and if we get a compressed packet, there's enough extra
  117  * room to expand the header into a max length tcp/ip header (128
  118  * bytes).  So, SLMAX can be at most
  119  *      MCLBYTES - 128
  120  *
  121  * SLMTU is a hard limit on output packet size.  To insure good
  122  * interactive response, SLMTU wants to be the smallest size that
  123  * amortizes the header cost.  (Remember that even with
  124  * type-of-service queuing, we have to wait for any in-progress
  125  * packet to finish.  I.e., we wait, on the average, 1/2 * mtu /
  126  * cps, where cps is the line speed in characters per second.
  127  * E.g., 533ms wait for a 1024 byte MTU on a 9600 baud line.  The
  128  * average compressed header size is 6-8 bytes so any MTU > 90
  129  * bytes will give us 90% of the line bandwidth.  A 100ms wait is
  130  * tolerable (500ms is not), so want an MTU around 296.  (Since TCP
  131  * will send 256 byte segments (to allow for 40 byte headers), the
  132  * typical packet size on the wire will be around 260 bytes).  In
  133  * 4.3tahoe+ systems, we can set an MTU in a route so we do that &
  134  * leave the interface MTU relatively high (so we don't IP fragment
  135  * when acting as a gateway to someone using a stupid MTU).
  136  *
  137  * Similar considerations apply to SLIP_HIWAT:  It's the amount of
  138  * data that will be queued 'downstream' of us (i.e., in clists
  139  * waiting to be picked up by the tty output interrupt).  If we
  140  * queue a lot of data downstream, it's immune to 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 SLMAX           (MCLBYTES - BUFOFFSET)
  155 #define SLBUFSIZE       (SLMAX + BUFOFFSET)
  156 #ifndef SLMTU
  157 #define SLMTU           296
  158 #endif
  159 #if (SLMTU < 3)
  160 #error SLMTU way too small.
  161 #endif
  162 #define SLIP_HIWAT      roundup(50, TTROUND)
  163 #ifndef __NetBSD__                                      /* XXX - cgd */
  164 #define CLISTRESERVE    1024    /* Can't let clists get too low */
  165 #endif  /* !__NetBSD__ */
  166 
  167 /*
  168  * SLIP ABORT ESCAPE MECHANISM:
  169  *      (inspired by HAYES modem escape arrangement)
  170  *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
  171  *      within window time signals a "soft" exit from slip mode by remote end
  172  *      if the IFF_DEBUG flag is on.
  173  */
  174 #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
  175 #define ABT_IDLE        1       /* in seconds - idle before an escape */
  176 #define ABT_COUNT       3       /* count of escapes for abort */
  177 #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
  178 
  179 static int              sl_clone_create(struct if_clone *, int);
  180 static int              sl_clone_destroy(struct ifnet *);
  181 
  182 static LIST_HEAD(, sl_softc) sl_softc_list;
  183 
  184 struct if_clone sl_cloner =
  185     IF_CLONE_INITIALIZER("sl", sl_clone_create, sl_clone_destroy);
  186 
  187 #define FRAME_END               0xc0            /* Frame End */
  188 #define FRAME_ESCAPE            0xdb            /* Frame Esc */
  189 #define TRANS_FRAME_END         0xdc            /* transposed frame end */
  190 #define TRANS_FRAME_ESCAPE      0xdd            /* transposed frame esc */
  191 
  192 static void     slintr(void *);
  193 
  194 static int      slcreate(struct sl_softc *);
  195 static struct mbuf *sl_btom(struct sl_softc *, int);
  196 
  197 static int      slclose(struct tty *, int);
  198 static int      slinput(int, struct tty *);
  199 static int      slioctl(struct ifnet *, u_long, void *);
  200 static int      slopen(dev_t, struct tty *);
  201 static int      sloutput(struct ifnet *, struct mbuf *, const struct sockaddr *,
  202                          const struct rtentry *);
  203 static int      slstart(struct tty *);
  204 static int      sltioctl(struct tty *, u_long, void *, int, struct lwp *);
  205 
  206 static struct linesw slip_disc = {
  207         .l_name = "slip",
  208         .l_open = slopen,
  209         .l_close = slclose,
  210         .l_read = ttyerrio,
  211         .l_write = ttyerrio,
  212         .l_ioctl = sltioctl,
  213         .l_rint = slinput,
  214         .l_start = slstart,
  215         .l_modem = nullmodem,
  216         .l_poll = ttyerrpoll
  217 };
  218 
  219 void
  220 slattach(int n __unused)
  221 {
  222 
  223         /*
  224          * Nothing to do here, initialization is handled by the
  225          * module initialization code in slinit() below).
  226          */
  227 }
  228 
  229 static void
  230 slinit(void)
  231 {
  232 
  233         if (ttyldisc_attach(&slip_disc) != 0)
  234                 panic("%s", __func__);
  235         LIST_INIT(&sl_softc_list);
  236         if_clone_attach(&sl_cloner);
  237 }
  238 
  239 static int
  240 sldetach(void)
  241 {
  242         int error = 0;
  243 
  244         if (!LIST_EMPTY(&sl_softc_list))
  245                 error = EBUSY;
  246 
  247         if (error == 0)
  248                 error = ttyldisc_detach(&slip_disc);
  249 
  250         if (error == 0)
  251                 if_clone_detach(&sl_cloner);
  252 
  253         return error;
  254 }
  255 
  256 static int
  257 sl_clone_create(struct if_clone *ifc, int unit)
  258 {
  259         struct sl_softc *sc;
  260 
  261         sc = malloc(sizeof(*sc), M_DEVBUF, M_WAIT|M_ZERO);
  262         sc->sc_unit = unit;
  263         if_initname(&sc->sc_if, ifc->ifc_name, unit);
  264         sc->sc_if.if_softc = sc;
  265         sc->sc_if.if_mtu = SLMTU;
  266         sc->sc_if.if_flags = IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
  267         sc->sc_if.if_type = IFT_SLIP;
  268         sc->sc_if.if_ioctl = slioctl;
  269         sc->sc_if.if_output = sloutput;
  270         sc->sc_if.if_dlt = DLT_SLIP;
  271         IFQ_SET_MAXLEN(&sc->sc_fastq, 32);
  272         IFQ_LOCK_INIT(&sc->sc_fastq);
  273         IFQ_SET_READY(&sc->sc_if.if_snd);
  274         if_attach(&sc->sc_if);
  275         if_alloc_sadl(&sc->sc_if);
  276         bpf_attach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
  277         LIST_INSERT_HEAD(&sl_softc_list, sc, sc_iflist);
  278         return 0;
  279 }
  280 
  281 static int
  282 sl_clone_destroy(struct ifnet *ifp)
  283 {
  284         struct sl_softc *sc = (struct sl_softc *)ifp->if_softc;
  285 
  286         if (sc->sc_ttyp != NULL)
  287                 return EBUSY;   /* Not removing it */
  288 
  289         LIST_REMOVE(sc, sc_iflist);
  290 
  291         bpf_detach(ifp);
  292         if_detach(ifp);
  293 
  294         IFQ_LOCK_DESTROY(&sc->sc_fastq);
  295 
  296         free(sc, M_DEVBUF);
  297         return 0;
  298 }
  299 
  300 static int
  301 slcreate(struct sl_softc *sc)
  302 {
  303 
  304         if (sc->sc_mbuf == NULL) {
  305                 sc->sc_mbuf = m_gethdr(M_WAIT, MT_DATA);
  306                 m_clget(sc->sc_mbuf, M_WAIT);
  307         }
  308         sc->sc_ep = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
  309             sc->sc_mbuf->m_ext.ext_size;
  310         sc->sc_mp = sc->sc_pktstart = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
  311             BUFOFFSET;
  312 
  313 #ifdef INET
  314         sl_compress_init(&sc->sc_comp);
  315 #endif
  316 
  317         return 1;
  318 }
  319 
  320 /*
  321  * Line specific open routine.
  322  * Attach the given tty to the first available sl unit.
  323  */
  324 /* ARGSUSED */
  325 static int
  326 slopen(dev_t dev, struct tty *tp)
  327 {
  328         struct lwp *l = curlwp;         /* XXX */
  329         struct sl_softc *sc;
  330         int error;
  331 
  332         error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE_SLIP,
  333             KAUTH_REQ_NETWORK_INTERFACE_SLIP_ADD, NULL, NULL, NULL);
  334         if (error)
  335                 return error;
  336 
  337         if (tp->t_linesw == &slip_disc)
  338                 return 0;
  339 
  340         LIST_FOREACH(sc, &sl_softc_list, sc_iflist)
  341                 if (sc->sc_ttyp == NULL) {
  342                         sc->sc_si = softint_establish(SOFTINT_NET,
  343                             slintr, sc);
  344                         if (sc->sc_si == NULL)
  345                                 return ENOMEM;
  346                         if (slcreate(sc) == 0) {
  347                                 softint_disestablish(sc->sc_si);
  348                                 return ENOBUFS;
  349                         }
  350                         tp->t_sc = (void *)sc;
  351                         sc->sc_ttyp = tp;
  352                         sc->sc_if.if_baudrate = tp->t_ospeed;
  353                         ttylock(tp);
  354                         tp->t_state |= TS_ISOPEN | TS_XCLUDE;
  355                         ttyflush(tp, FREAD | FWRITE);
  356                         /*
  357                          * make sure tty output queue is large enough
  358                          * to hold a full-sized packet (including frame
  359                          * end, and a possible extra frame end).  full-sized
  360                          * packet occupies a max of 2*SLMAX bytes (because
  361                          * of possible escapes), and add two on for frame
  362                          * ends.
  363                          */
  364                         if (tp->t_outq.c_cn < 2 * SLMAX + 2) {
  365                                 sc->sc_oldbufsize = tp->t_outq.c_cn;
  366                                 sc->sc_oldbufquot = tp->t_outq.c_cq != 0;
  367 
  368                                 clfree(&tp->t_outq);
  369                                 ttyunlock(tp);
  370                                 error = clalloc(&tp->t_outq, 2 * SLMAX + 2, 0);
  371                                 if (error) {
  372                                         softint_disestablish(sc->sc_si);
  373                                         /*
  374                                          * clalloc() might return -1 which
  375                                          * is no good, so we need to return
  376                                          * something else.
  377                                          */
  378                                         return ENOMEM; /* XXX ?! */
  379                                 }
  380                         } else {
  381                                 sc->sc_oldbufsize = sc->sc_oldbufquot = 0;
  382                                 ttyunlock(tp);
  383                         }
  384                         return 0;
  385                 }
  386         return ENXIO;
  387 }
  388 
  389 /*
  390  * Line specific close routine.
  391  * Detach the tty from the sl unit.
  392  */
  393 static int
  394 slclose(struct tty *tp, int flag)
  395 {
  396         struct sl_softc *sc;
  397         int s;
  398 
  399         ttywflush(tp);
  400         sc = tp->t_sc;
  401 
  402         if (sc != NULL) {
  403                 softint_disestablish(sc->sc_si);
  404                 s = splnet();
  405                 if_down(&sc->sc_if);
  406                 IF_PURGE(&sc->sc_fastq);
  407                 splx(s);
  408 
  409                 s = spltty();
  410                 ttyldisc_release(tp->t_linesw);
  411                 tp->t_linesw = ttyldisc_default();
  412                 tp->t_state = 0;
  413 
  414                 sc->sc_ttyp = NULL;
  415                 tp->t_sc = NULL;
  416 
  417                 m_freem(sc->sc_mbuf);
  418                 sc->sc_mbuf = NULL;
  419                 sc->sc_ep = sc->sc_mp = sc->sc_pktstart = NULL;
  420                 IF_PURGE(&sc->sc_inq);
  421 
  422                 /*
  423                  * If necessary, install a new outq buffer of the
  424                  * appropriate size.
  425                  */
  426                 if (sc->sc_oldbufsize != 0) {
  427                         clfree(&tp->t_outq);
  428                         clalloc(&tp->t_outq, sc->sc_oldbufsize,
  429                             sc->sc_oldbufquot);
  430                 }
  431                 splx(s);
  432         }
  433 
  434         return 0;
  435 }
  436 
  437 /*
  438  * Line specific (tty) ioctl routine.
  439  * Provide a way to get the sl unit number.
  440  */
  441 /* ARGSUSED */
  442 static int
  443 sltioctl(struct tty *tp, u_long cmd, void *data, int flag,
  444     struct lwp *l)
  445 {
  446         struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
  447 
  448         /*
  449          * XXX
  450          * This function can be called without KERNEL_LOCK when caller's
  451          * struct cdevsw is set D_MPSAFE. Is KERNEL_LOCK required?
  452          */
  453 
  454         switch (cmd) {
  455         case SLIOCGUNIT:
  456                 *(int *)data = sc->sc_unit;     /* XXX */
  457                 break;
  458 
  459         default:
  460                 return EPASSTHROUGH;
  461         }
  462         return 0;
  463 }
  464 
  465 /*
  466  * Queue a packet.  Start transmission if not active.
  467  * Compression happens in slintr(); if we do it here, IP TOS
  468  * will cause us to not compress "background" packets, because
  469  * ordering gets trashed.  It can be done for all packets in slintr().
  470  */
  471 static int
  472 sloutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
  473     const struct rtentry *rtp)
  474 {
  475         struct sl_softc *sc = ifp->if_softc;
  476         struct ip *ip;
  477         struct ifqueue *ifq = NULL;
  478         int s, error;
  479 
  480         IFQ_CLASSIFY(&ifp->if_snd, m, dst->sa_family);
  481 
  482         /*
  483          * `Cannot happen' (see slioctl).  Someday we will extend
  484          * the line protocol to support other address families.
  485          */
  486         if (dst->sa_family != AF_INET) {
  487                 printf("%s: af%d not supported\n", sc->sc_if.if_xname,
  488                     dst->sa_family);
  489                 m_freem(m);
  490                 if_statinc(&sc->sc_if, if_noproto);
  491                 return EAFNOSUPPORT;
  492         }
  493 
  494         if (sc->sc_ttyp == NULL) {
  495                 m_freem(m);
  496                 return ENETDOWN;        /* sort of */
  497         }
  498         if ((sc->sc_ttyp->t_state & TS_CARR_ON) == 0 &&
  499             (sc->sc_ttyp->t_cflag & CLOCAL) == 0) {
  500                 m_freem(m);
  501                 printf("%s: no carrier and not local\n", sc->sc_if.if_xname);
  502                 return EHOSTUNREACH;
  503         }
  504         ip = mtod(m, struct ip *);
  505 #ifdef INET
  506         if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
  507                 m_freem(m);
  508                 return ENETRESET;               /* XXX ? */
  509         }
  510 #endif
  511 
  512         s = spltty();
  513         if (sc->sc_oqlen && sc->sc_ttyp->t_outq.c_cc == sc->sc_oqlen) {
  514                 struct bintime bt;
  515 
  516                 /* if output's been stalled for too long, and restart */
  517                 getbinuptime(&bt);
  518                 bintime_sub(&bt, &sc->sc_lastpacket);
  519                 if (bt.sec > 0) {
  520                         sc->sc_otimeout++;
  521                         slstart(sc->sc_ttyp);
  522                 }
  523         }
  524         splx(s);
  525 
  526         s = splnet();
  527 #ifdef INET
  528         if ((ip->ip_tos & IPTOS_LOWDELAY) != 0)
  529                 ifq = &sc->sc_fastq;
  530 #endif
  531         if ((error = ifq_enqueue2(ifp, ifq, m)) != 0) {
  532                 splx(s);
  533                 return error;
  534         }
  535         getbinuptime(&sc->sc_lastpacket);
  536         splx(s);
  537 
  538         s = spltty();
  539         if ((sc->sc_oqlen = sc->sc_ttyp->t_outq.c_cc) == 0)
  540                 slstart(sc->sc_ttyp);
  541         splx(s);
  542 
  543         return 0;
  544 }
  545 
  546 /*
  547  * Start output on interface.  Get another datagram
  548  * to send from the interface queue and map it to
  549  * the interface before starting output.
  550  */
  551 static int
  552 slstart(struct tty *tp)
  553 {
  554         struct sl_softc *sc = tp->t_sc;
  555 
  556         /*
  557          * If there is more in the output queue, just send it now.
  558          * We are being called in lieu of ttstart and must do what
  559          * it would.
  560          */
  561         if (tp->t_outq.c_cc != 0) {
  562                 (*tp->t_oproc)(tp);
  563                 if (tp->t_outq.c_cc > SLIP_HIWAT)
  564                         return 0;
  565         }
  566 
  567         /*
  568          * This happens briefly when the line shuts down.
  569          */
  570         if (sc == NULL)
  571                 return 0;
  572         softint_schedule(sc->sc_si);
  573         return 0;
  574 }
  575 
  576 /*
  577  * Copy data buffer to mbuf chain; add ifnet pointer.
  578  */
  579 static struct mbuf *
  580 sl_btom(struct sl_softc *sc, int len)
  581 {
  582         struct mbuf *m;
  583 
  584         /*
  585          * Allocate a new input buffer and swap.
  586          */
  587         m = sc->sc_mbuf;
  588         MGETHDR(sc->sc_mbuf, M_DONTWAIT, MT_DATA);
  589         if (sc->sc_mbuf == NULL) {
  590                 sc->sc_mbuf = m;
  591                 return NULL;
  592         }
  593         MCLGET(sc->sc_mbuf, M_DONTWAIT);
  594         if ((sc->sc_mbuf->m_flags & M_EXT) == 0) {
  595                 m_freem(sc->sc_mbuf);
  596                 sc->sc_mbuf = m;
  597                 return NULL;
  598         }
  599         sc->sc_ep = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
  600             sc->sc_mbuf->m_ext.ext_size;
  601 
  602         m->m_data = sc->sc_pktstart;
  603 
  604         m->m_pkthdr.len = m->m_len = len;
  605         m_set_rcvif(m, &sc->sc_if);
  606         return m;
  607 }
  608 
  609 /*
  610  * tty interface receiver interrupt.
  611  */
  612 static int
  613 slinput(int c, struct tty *tp)
  614 {
  615         struct sl_softc *sc;
  616         struct mbuf *m;
  617         int len;
  618 
  619         tk_nin++;
  620         sc = (struct sl_softc *)tp->t_sc;
  621         if (sc == NULL)
  622                 return 0;
  623         if ((c & TTY_ERRORMASK) || ((tp->t_state & TS_CARR_ON) == 0 &&
  624             (tp->t_cflag & CLOCAL) == 0)) {
  625                 sc->sc_flags |= SC_ERROR;
  626                 return 0;
  627         }
  628         c &= TTY_CHARMASK;
  629 
  630         if_statinc(&sc->sc_if, if_ibytes);
  631 
  632         if (sc->sc_if.if_flags & IFF_DEBUG) {
  633                 if (c == ABT_ESC) {
  634                         /*
  635                          * If we have a previous abort, see whether
  636                          * this one is within the time limit.
  637                          */
  638                         if (sc->sc_abortcount &&
  639                             time_second >= sc->sc_starttime + ABT_WINDOW)
  640                                 sc->sc_abortcount = 0;
  641                         /*
  642                          * If we see an abort after "idle" time, count it;
  643                          * record when the first abort escape arrived.
  644                          */
  645                         if (time_second >= sc->sc_lasttime + ABT_IDLE) {
  646                                 if (++sc->sc_abortcount == 1)
  647                                         sc->sc_starttime = time_second;
  648                                 if (sc->sc_abortcount >= ABT_COUNT) {
  649                                         slclose(tp, 0);
  650                                         return 0;
  651                                 }
  652                         }
  653                 } else
  654                         sc->sc_abortcount = 0;
  655                 sc->sc_lasttime = time_second;
  656         }
  657 
  658         switch (c) {
  659 
  660         case TRANS_FRAME_ESCAPE:
  661                 if (sc->sc_escape)
  662                         c = FRAME_ESCAPE;
  663                 break;
  664 
  665         case TRANS_FRAME_END:
  666                 if (sc->sc_escape)
  667                         c = FRAME_END;
  668                 break;
  669 
  670         case FRAME_ESCAPE:
  671                 sc->sc_escape = 1;
  672                 return 0;
  673 
  674         case FRAME_END:
  675                 if (sc->sc_flags & SC_ERROR) {
  676                         sc->sc_flags &= ~SC_ERROR;
  677                         goto newpack;
  678                 }
  679                 len = sc->sc_mp - sc->sc_pktstart;
  680                 if (len < 3)
  681                         /* less than min length packet - ignore */
  682                         goto newpack;
  683 
  684                 m = sl_btom(sc, len);
  685                 if (m == NULL)
  686                         goto error;
  687 
  688                 IF_ENQUEUE(&sc->sc_inq, m);
  689                 softint_schedule(sc->sc_si);
  690                 goto newpack;
  691         }
  692         if (sc->sc_mp < sc->sc_ep) {
  693                 *sc->sc_mp++ = c;
  694                 sc->sc_escape = 0;
  695                 return 0;
  696         }
  697 
  698         /* can't put lower; would miss an extra frame */
  699         sc->sc_flags |= SC_ERROR;
  700 
  701 error:
  702         if_statinc(&sc->sc_if, if_ierrors);
  703 newpack:
  704         sc->sc_mp = sc->sc_pktstart = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
  705             BUFOFFSET;
  706         sc->sc_escape = 0;
  707 
  708         return 0;
  709 }
  710 
  711 static void
  712 slintr(void *arg)
  713 {
  714         struct sl_softc *sc = arg;
  715         struct tty *tp = sc->sc_ttyp;
  716         struct mbuf *m, *n;
  717         int s, len;
  718         u_char *pktstart;
  719         u_char chdr[CHDR_LEN];
  720 
  721         KASSERT(tp != NULL);
  722 
  723         /*
  724          * Output processing loop.
  725          */
  726         mutex_enter(softnet_lock);
  727         for (;;) {
  728                 struct mbuf *m2;
  729                 struct mbuf *bpf_m;
  730 
  731                 /*
  732                  * Do not remove the packet from the queue if it
  733                  * doesn't look like it will fit into the current
  734                  * serial output queue.  With a packet full of
  735                  * escapes, this could be as bad as MTU*2+2.
  736                  */
  737                 s = spltty();
  738                 if (tp->t_outq.c_cn - tp->t_outq.c_cc <
  739                     2 * sc->sc_if.if_mtu + 2) {
  740                         splx(s);
  741                         break;
  742                 }
  743                 splx(s);
  744 
  745                 /*
  746                  * Get a packet and send it to the interface.
  747                  */
  748                 s = splnet();
  749                 IF_DEQUEUE(&sc->sc_fastq, m);
  750                 if (m)
  751                         if_statinc(&sc->sc_if, if_omcasts);     /* XXX */
  752                 else
  753                         IFQ_DEQUEUE(&sc->sc_if.if_snd, m);
  754                 splx(s);
  755 
  756                 if (m == NULL)
  757                         break;
  758 
  759                 /*
  760                  * We do the header compression here rather than in
  761                  * sloutput() because the packets will be out of order
  762                  * if we are using TOS queueing, and the connection
  763                  * ID compression will get munged when this happens.
  764                  */
  765                 if (sc->sc_if.if_bpf) {
  766                         /*
  767                          * We need to save the TCP/IP header before
  768                          * it's compressed.  To avoid complicated
  769                          * code, we just make a deep copy of the
  770                          * entire packet (since this is a serial
  771                          * line, packets should be short and/or the
  772                          * copy should be negligible cost compared
  773                          * to the packet transmission time).
  774                          */
  775                         bpf_m = m_dup(m, 0, M_COPYALL, M_DONTWAIT);
  776                 } else
  777                         bpf_m = NULL;
  778 #ifdef INET
  779                 struct ip *ip;
  780                 if ((ip = mtod(m, struct ip *))->ip_p == IPPROTO_TCP) {
  781                         if (sc->sc_if.if_flags & SC_COMPRESS)
  782                                 *mtod(m, u_char *) |=
  783                                     sl_compress_tcp(m, ip, &sc->sc_comp, 1);
  784                 }
  785 #endif
  786                 if (bpf_m)
  787                         bpf_mtap_sl_out(&sc->sc_if, mtod(m, u_char *), bpf_m);
  788                 getbinuptime(&sc->sc_lastpacket);
  789 
  790                 s = spltty();
  791 
  792                 /*
  793                  * The extra FRAME_END will start up a new packet,
  794                  * and thus will flush any accumulated garbage.  We
  795                  * do this whenever the line may have been idle for
  796                  * some time.
  797                  */
  798                 if (tp->t_outq.c_cc == 0) {
  799                         if_statinc(&sc->sc_if, if_obytes);
  800                         (void)putc(FRAME_END, &tp->t_outq);
  801                 }
  802 
  803                 while (m) {
  804                         u_char *bp, *cp, *ep;
  805 
  806                         bp = cp = mtod(m, u_char *);
  807                         ep = cp + m->m_len;
  808                         while (cp < ep) {
  809                                 /*
  810                                  * Find out how many bytes in the
  811                                  * string we can handle without
  812                                  * doing something special.
  813                                  */
  814                                 while (cp < ep) {
  815                                         switch (*cp++) {
  816                                         case FRAME_ESCAPE:
  817                                         case FRAME_END:
  818                                                 cp--;
  819                                                 goto out;
  820                                         }
  821                                 }
  822                                 out:
  823                                 if (cp > bp) {
  824                                         /*
  825                                          * Put N characters at once
  826                                          * into the tty output queue.
  827                                          */
  828                                         if (b_to_q(bp, cp - bp, &tp->t_outq))
  829                                                 break;
  830                                         if_statadd(&sc->sc_if, if_obytes,
  831                                             cp - bp);
  832                                 }
  833                                 /*
  834                                  * If there are characters left in
  835                                  * the mbuf, the first one must be
  836                                  * special..  Put it out in a different
  837                                  * form.
  838                                  */
  839                                 if (cp < ep) {
  840                                         if (putc(FRAME_ESCAPE, &tp->t_outq))
  841                                                 break;
  842                                         if (putc(*cp++ == FRAME_ESCAPE ?
  843                                             TRANS_FRAME_ESCAPE :
  844                                             TRANS_FRAME_END,
  845                                             &tp->t_outq)) {
  846                                                 (void)unputc(&tp->t_outq);
  847                                                 break;
  848                                         }
  849                                         if_statadd(&sc->sc_if, if_obytes, 2);
  850                                 }
  851                                 bp = cp;
  852                         }
  853                         m = m2 = m_free(m);
  854                 }
  855 
  856                 if (putc(FRAME_END, &tp->t_outq)) {
  857                         /*
  858                          * Not enough room.  Remove a char to make
  859                          * room and end the packet normally.  If
  860                          * you get many collisions (more than one
  861                          * or two a day), you probably do not have
  862                          * enough clists and you should increase
  863                          * "nclist" in param.c
  864                          */
  865                         (void)unputc(&tp->t_outq);
  866                         (void)putc(FRAME_END, &tp->t_outq);
  867                         if_statinc(&sc->sc_if, if_collisions);
  868                 } else {
  869                         if_statadd2(&sc->sc_if, if_obytes, 1, if_opackets, 1);
  870                 }
  871 
  872                 /*
  873                  * We now have characters in the output queue,
  874                  * kick the serial port.
  875                  */
  876                 (*tp->t_oproc)(tp);
  877                 splx(s);
  878         }
  879 
  880         /*
  881          * Input processing loop.
  882          */
  883         for (;;) {
  884                 s = spltty();
  885                 IF_DEQUEUE(&sc->sc_inq, m);
  886                 splx(s);
  887                 if (m == NULL)
  888                         break;
  889                 pktstart = mtod(m, u_char *);
  890                 len = m->m_pkthdr.len;
  891                 if (sc->sc_if.if_bpf) {
  892                         /*
  893                          * Save the compressed header, so we
  894                          * can tack it on later.  Note that we
  895                          * will end up copying garbage in some
  896                          * cases but this is okay.  We remember
  897                          * where the buffer started so we can
  898                          * compute the new header length.
  899                          */
  900                         memcpy(chdr, pktstart, CHDR_LEN);
  901                 }
  902 #ifdef INET
  903                 u_char c;
  904                 if ((c = (*pktstart & 0xf0)) != (IPVERSION << 4)) {
  905                         if (c & 0x80)
  906                                 c = TYPE_COMPRESSED_TCP;
  907                         else if (c == TYPE_UNCOMPRESSED_TCP)
  908                                 *pktstart &= 0x4f; /* XXX */
  909                         /*
  910                          * We've got something that's not an IP
  911                          * packet.  If compression is enabled,
  912                          * try to decompress it.  Otherwise, if
  913                          * `auto-enable' compression is on and
  914                          * it's a reasonable packet, decompress
  915                          * it and then enable compression.
  916                          * Otherwise, drop it.
  917                          */
  918                         if (sc->sc_if.if_flags & SC_COMPRESS) {
  919                                 len = sl_uncompress_tcp(&pktstart, len,
  920                                     (u_int)c, &sc->sc_comp);
  921                                 if (len <= 0) {
  922                                         m_freem(m);
  923                                         continue;
  924                                 }
  925                         } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
  926                             c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
  927                                 len = sl_uncompress_tcp(&pktstart, len,
  928                                     (u_int)c, &sc->sc_comp);
  929                                 if (len <= 0) {
  930                                         m_freem(m);
  931                                         continue;
  932                                 }
  933                                 sc->sc_if.if_flags |= SC_COMPRESS;
  934                         } else {
  935                                 m_freem(m);
  936                                 continue;
  937                         }
  938                 }
  939 #endif
  940                 m->m_data = (void *) pktstart;
  941                 m->m_pkthdr.len = m->m_len = len;
  942                 if (sc->sc_if.if_bpf) {
  943                         bpf_mtap_sl_in(&sc->sc_if, chdr, &m);
  944                         if (m == NULL)
  945                                 continue;
  946                 }
  947                 /*
  948                  * If the packet will fit into a single
  949                  * header mbuf, try to copy it into one,
  950                  * to save memory.
  951                  */
  952                 if ((m->m_pkthdr.len < MHLEN) &&
  953                     (n = m_gethdr(M_DONTWAIT, MT_DATA))) {
  954                         int pktlen;
  955 
  956                         pktlen = m->m_pkthdr.len;
  957                         m_move_pkthdr(n, m);
  958                         memcpy(mtod(n, void *), mtod(m, void *), pktlen);
  959                         n->m_len = m->m_len;
  960                         m_freem(m);
  961                         m = n;
  962                 }
  963 
  964                 if_statinc(&sc->sc_if, if_ipackets);
  965                 getbinuptime(&sc->sc_lastpacket);
  966 
  967 #ifdef INET
  968                 s = splnet();
  969                 if (__predict_false(!pktq_enqueue(ip_pktq, m, 0))) {
  970                         if_statadd2(&sc->sc_if, if_ierrors, 1, if_iqdrops, 1);
  971                         m_freem(m);
  972                 }
  973                 splx(s);
  974 #endif
  975         }
  976         mutex_exit(softnet_lock);
  977 }
  978 
  979 /*
  980  * Process an ioctl request.
  981  */
  982 static int
  983 slioctl(struct ifnet *ifp, u_long cmd, void *data)
  984 {
  985         struct ifaddr *ifa = (struct ifaddr *)data;
  986         struct ifreq *ifr = (struct ifreq *)data;
  987         int s = splnet(), error = 0;
  988         struct sl_softc *sc = ifp->if_softc;
  989         struct ppp_stats *psp;
  990         struct ppp_comp_stats *pcp;
  991 
  992         switch (cmd) {
  993 
  994         case SIOCINITIFADDR:
  995                 if (ifa->ifa_addr->sa_family == AF_INET)
  996                         ifp->if_flags |= IFF_UP;
  997                 else
  998                         error = EAFNOSUPPORT;
  999                 break;
 1000 
 1001         case SIOCSIFDSTADDR:
 1002                 if (ifreq_getaddr(cmd, ifr)->sa_family != AF_INET)
 1003                         error = EAFNOSUPPORT;
 1004                 break;
 1005 
 1006         case SIOCSIFMTU:
 1007                 if ((ifr->ifr_mtu < 3) || (ifr->ifr_mtu > SLMAX)) {
 1008                     error = EINVAL;
 1009                     break;
 1010                 }
 1011                 /*FALLTHROUGH*/
 1012         case SIOCGIFMTU:
 1013                 if ((error = ifioctl_common(&sc->sc_if, cmd, data)) == ENETRESET)
 1014                         error = 0;
 1015                 break;
 1016 
 1017         case SIOCADDMULTI:
 1018         case SIOCDELMULTI:
 1019                 if (ifr == 0) {
 1020                         error = EAFNOSUPPORT;           /* XXX */
 1021                         break;
 1022                 }
 1023                 switch (ifreq_getaddr(cmd, ifr)->sa_family) {
 1024 
 1025 #ifdef INET
 1026                 case AF_INET:
 1027                         break;
 1028 #endif
 1029 
 1030                 default:
 1031                         error = EAFNOSUPPORT;
 1032                         break;
 1033                 }
 1034                 break;
 1035 
 1036         case SIOCGPPPSTATS: {
 1037                 struct if_data ifi;
 1038 
 1039                 if_export_if_data(&sc->sc_if, &ifi, false);
 1040                 psp = &((struct ifpppstatsreq *) data)->stats;
 1041                 (void)memset(psp, 0, sizeof(*psp));
 1042                 psp->p.ppp_ibytes = ifi.ifi_ibytes;
 1043                 psp->p.ppp_ipackets = ifi.ifi_ipackets;
 1044                 psp->p.ppp_ierrors = ifi.ifi_ierrors;
 1045                 psp->p.ppp_obytes = ifi.ifi_obytes;
 1046                 psp->p.ppp_opackets = ifi.ifi_opackets;
 1047                 psp->p.ppp_oerrors = ifi.ifi_oerrors;
 1048 #ifdef INET
 1049                 psp->vj.vjs_packets = sc->sc_comp.sls_packets;
 1050                 psp->vj.vjs_compressed = sc->sc_comp.sls_compressed;
 1051                 psp->vj.vjs_searches = sc->sc_comp.sls_searches;
 1052                 psp->vj.vjs_misses = sc->sc_comp.sls_misses;
 1053                 psp->vj.vjs_uncompressedin = sc->sc_comp.sls_uncompressedin;
 1054                 psp->vj.vjs_compressedin = sc->sc_comp.sls_compressedin;
 1055                 psp->vj.vjs_errorin = sc->sc_comp.sls_errorin;
 1056                 psp->vj.vjs_tossed = sc->sc_comp.sls_tossed;
 1057 #endif
 1058             }
 1059                 break;
 1060 
 1061         case SIOCGPPPCSTATS:
 1062                 pcp = &((struct ifpppcstatsreq *) data)->stats;
 1063                 (void)memset(pcp, 0, sizeof(*pcp));
 1064                 break;
 1065 
 1066         default:
 1067                 error = ifioctl_common(ifp, cmd, data);
 1068                 break;
 1069         }
 1070         splx(s);
 1071         return error;
 1072 }
 1073 
 1074 
 1075 /*
 1076  * Module infrastructure
 1077  */
 1078 
 1079 #include "if_module.h"
 1080 
 1081 IF_MODULE(MODULE_CLASS_DRIVER, sl, "slcompress");

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