FreeBSD/Linux Kernel Cross Reference
sys/net/if_strip.c

     /*      $NetBSD: if_strip.c,v 1.51 2004/01/19 16:12:51 atatat Exp $     */
     /*      from: NetBSD: if_sl.c,v 1.38 1996/02/13 22:00:23 christos Exp $ */
     
     /*
      * Copyright 1996 The Board of Trustees of The Leland Stanford
      * Junior University. All Rights Reserved.
      *
      * Permission to use, copy, modify, and distribute this
      * software and its documentation for any purpose and without
     * fee is hereby granted, provided that the above copyright
     * notice appear in all copies.  Stanford University
     * makes no representations about the suitability of this
     * software for any purpose.  It is provided "as is" without
     * express or implied warranty.
     *
     *
     * This driver was contributed by Jonathan Stone.
     *
     * Starmode Radio IP interface (STRIP) for Metricom wireless radio.
     * This STRIP driver assumes address resolution of IP addresses to
     * Metricom MAC addresses is done via local link-level routes.
     * The link-level addresses are entered as an 8-digit packed BCD number.
     * To add a route for a radio at IP address 10.1.2.3, with radio
     * address '1234-5678', reachable via interface strip0, use the command 
     *
     *      route add -host 10.1.2.3  -link strip0:12:34:56:78
     */
    
    
    /*
     * Copyright (c) 1987, 1989, 1992, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)if_sl.c     8.6 (Berkeley) 2/1/94
     */
    
    /*
     * Derived from: Serial Line interface written by Rick Adams (rick@seismo.gov)
     *
     * Rick Adams
     * Center for Seismic Studies
     * 1300 N 17th Street, Suite 1450
     * Arlington, Virginia 22209
     * (703)276-7900
     * rick@seismo.ARPA
     * seismo!rick
     *
     * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
     * N.B.: this belongs in netinet, not net, the way it stands now.
     * Should have a link-layer type designation, but wouldn't be
     * backwards-compatible.
     *
     * Converted to 4.3BSD Beta by Chris Torek.
     * Other changes made at Berkeley, based in part on code by Kirk Smith.
     * W. Jolitz added slip abort.
     *
     * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
     * Added priority queuing for "interactive" traffic; hooks for TCP
     * header compression; ICMP filtering (at 2400 baud, some cretin
     * pinging you can use up all your bandwidth).  Made low clist behavior
     * more robust and slightly less likely to hang serial line.
     * Sped up a bunch of things.
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: if_strip.c,v 1.51 2004/01/19 16:12:51 atatat Exp $");
    
    #include "strip.h"
    
    #include "opt_inet.h"
    #include "bpfilter.h"
    
    #include <sys/param.h>
    #include <sys/proc.h>
    #include <sys/mbuf.h>
   #include <sys/buf.h>
   #include <sys/dkstat.h>
   #include <sys/socket.h>
   #include <sys/ioctl.h>
   #include <sys/file.h>
   #include <sys/conf.h>
   #include <sys/tty.h>
   #include <sys/kernel.h>
   #if __NetBSD__
   #include <sys/systm.h>
   #include <sys/callout.h>
   #endif
   #include <sys/syslog.h>
   
   #include <machine/cpu.h>
   #include <machine/intr.h>
   
   #include <net/if.h>
   #include <net/if_dl.h>
   #include <net/if_types.h>
   #include <net/netisr.h>
   #include <net/route.h>
   
   #ifdef INET
   #include <netinet/in.h>
   #include <netinet/in_systm.h>
   #include <netinet/in_var.h>
   #include <netinet/ip.h>
   #else
   #error Starmode Radio IP configured without configuring inet?
   #endif
   
   #include <net/slcompress.h>
   #include <net/if_stripvar.h>
   #include <net/slip.h>
   
   #ifdef __NetBSD__       /* XXX -- jrs */
   typedef u_char ttychar_t;
   #else
   typedef char ttychar_t;
   #endif
   
   #if NBPFILTER > 0
   #include <sys/time.h>
   #include <net/bpf.h>
   #endif
   
   /*
    * SLMAX is a hard limit on input packet size.  To simplify the code
    * and improve performance, we require that packets fit in an mbuf
    * cluster, and if we get a compressed packet, there's enough extra
    * room to expand the header into a max length tcp/ip header (128
    * bytes).  So, SLMAX can be at most
    *      MCLBYTES - 128
    *
    * SLMTU is a hard limit on output packet size.  To insure good
    * interactive response, SLMTU wants to be the smallest size that
    * amortizes the header cost.  Remember that even with
    * type-of-service queuing, we have to wait for any in-progress
    * packet to finish.  I.e., we wait, on the average, 1/2 * mtu /
    * cps, where cps is the line speed in characters per second.
    * E.g., 533ms wait for a 1024 byte MTU on a 9600 baud line.  The
    * average compressed header size is 6-8 bytes so any MTU > 90
    * bytes will give us 90% of the line bandwidth.  A 100ms wait is
    * tolerable (500ms is not), so want an MTU around 296.  (Since TCP
    * will send 256 byte segments (to allow for 40 byte headers), the
    * typical packet size on the wire will be around 260 bytes).  In
    * 4.3tahoe+ systems, we can set an MTU in a route so we do that &
    * leave the interface MTU relatively high (so we don't IP fragment
    * when acting as a gateway to someone using a stupid MTU).
    *
    * Similar considerations apply to SLIP_HIWAT:  It's the amount of
    * data that will be queued 'downstream' of us (i.e., in clists
    * waiting to be picked up by the tty output interrupt).  If we
    * queue a lot of data downstream, it's immune to our t.o.s. queuing.
    * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
    * telnet/ftp will see a 1 sec wait, independent of the mtu (the
    * wait is dependent on the ftp window size but that's typically
    * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
    * the cost (in idle time on the wire) of the tty driver running
    * off the end of its clists & having to call back slstart for a
    * new packet.  For a tty interface with any buffering at all, this
    * cost will be zero.  Even with a totally brain dead interface (like
    * the one on a typical workstation), the cost will be <= 1 character
    * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
    * at most 1% while maintaining good interactive response.
    */
   #define BUFOFFSET       (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
   #define SLMAX           (MCLBYTES - BUFOFFSET)
   #define SLBUFSIZE       (SLMAX + BUFOFFSET)
   #define SLMTU           1100 /* XXX -- appromaximated. 1024 may be safer. */
   
   #define STRIP_MTU_ONWIRE (SLMTU + 20 + STRIP_HDRLEN) /* (2*SLMTU+2 in sl.c */
   
   
   #define SLIP_HIWAT      roundup(50,CBSIZE)
   
   /* This is a NetBSD-1.0 or later kernel. */
   #define CCOUNT(q)       ((q)->c_cc)
   
   
   #ifndef __NetBSD__                                      /* XXX - cgd */
   #define CLISTRESERVE    1024    /* Can't let clists get too low */
   #endif  /* !__NetBSD__ */
   
   /*
    * SLIP ABORT ESCAPE MECHANISM:
    *      (inspired by HAYES modem escape arrangement)
    *      1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
    *      within window time signals a "soft" exit from slip mode by remote end
    *      if the IFF_DEBUG flag is on.
    */
   #define ABT_ESC         '\033'  /* can't be t_intr - distant host must know it*/
   #define ABT_IDLE        1       /* in seconds - idle before an escape */
   #define ABT_COUNT       3       /* count of escapes for abort */
   #define ABT_WINDOW      (ABT_COUNT*2+2) /* in seconds - time to count */
   
   struct strip_softc strip_softc[NSTRIP];
   
   #define STRIP_FRAME_END         0x0D            /* carriage return */
   
   #ifndef __HAVE_GENERIC_SOFT_INTERRUPTS
   void    stripnetisr(void);
   #endif
   void    stripintr(void *);
   
   static int stripinit __P((struct strip_softc *));
   static  struct mbuf *strip_btom __P((struct strip_softc *, int));
   
   /*
    * STRIP header: '*' + modem address (dddd-dddd) + '*' + mactype ('SIP0')
    * A Metricom packet looks like this: *<address>*<key><payload><CR>
    *   eg. *0000-1164*SIP0<payload><CR>
    *
    */
   
   #define STRIP_ENCAP_SIZE(X) ((36) + (X)*65/64 + 2)
   #define STRIP_HDRLEN 15
   #define STRIP_MAC_ADDR_LEN 9
   
   /*
    * Star mode packet header.
    * (may be used for encapsulations other than STRIP.)
    */
   #define STARMODE_ADDR_LEN 11
   struct st_header {
           u_char starmode_addr[STARMODE_ADDR_LEN];
           u_char starmode_type[4];
   };
   
   /*
    * Forward declarations for Metricom-specific functions.
    * Ideally, these would be in a library and shared across
    * different STRIP implementations: *BSD, Linux, etc.
    *
    */
   static u_char* UnStuffData __P((u_char *src, u_char *end, u_char
                                   *dest, u_long dest_length)); 
   
   static u_char* StuffData __P((u_char *src, u_long length, u_char *dest,
                                 u_char **code_ptr_ptr));
   
   static void RecvErr __P((char *msg, struct strip_softc *sc));
   static void RecvErr_Message __P((struct strip_softc *strip_info,
                                   u_char *sendername, u_char *msg));
   void    strip_resetradio __P((struct strip_softc *sc, struct tty *tp));
   void    strip_proberadio __P((struct strip_softc *sc, struct tty *tp));
   void    strip_watchdog __P((struct ifnet *ifp));
   void    strip_sendbody __P((struct strip_softc *sc, struct mbuf *m));
   int     strip_newpacket __P((struct strip_softc *sc, u_char *ptr, u_char *end));
   void    strip_send __P((struct strip_softc *sc, struct mbuf *m0));
   
   void    strip_timeout __P((void *x));
   
   #ifdef DEBUG
   #define DPRINTF(x)      printf x
   #else
   #define DPRINTF(x)
   #endif
   
   
   
   /*
    * Radio reset macros.
    * The Metricom radios are not particularly well-designed for
    * use in packet mode (starmode).  There's no easy way to tell
    * when the radio is in starmode.  Worse, when the radios are reset
    * or power-cycled, they come back up in Hayes AT-emulation mode,
    * and there's no good way for this driver to tell.
    * We deal with this by peridically tickling the radio
    * with an invalid starmode command.  If the radio doesn't
    * respond with an error, the driver knows to reset the radio.
    */
   
   /* Radio-reset finite state machine (if_watchdog) callback rate, in seconds */
   #define STRIP_WATCHDOG_INTERVAL 5
   
   /* Period between intrusive radio probes, in seconds */
   #define ST_PROBE_INTERVAL 10
   
   /* Grace period for radio to answer probe, in seconds */
   #define ST_PROBERESPONSE_INTERVAL 2
   
   /* Be less agressive about repeated resetting. */
   #define STRIP_RESET_INTERVAL 5
   
   /*
    * We received a response from the radio that indicates it's in
    * star mode.  Clear any pending probe or reset timer.
    * Don't  probe radio again for standard polling interval.
    */
   #define CLEAR_RESET_TIMER(sc) \
    do {\
       (sc)->sc_state = ST_ALIVE;  \
       (sc)->sc_statetimo = time.tv_sec + ST_PROBE_INTERVAL;       \
   } while (/*CONSTCOND*/ 0)
   
   /*
    * we received a response from the radio that indicates it's crashed
    * out of starmode into Hayse mode. Reset it ASAP.
    */
   #define FORCE_RESET(sc) \
    do {\
       (sc)->sc_statetimo = time.tv_sec - 1; \
       (sc)->sc_state = ST_DEAD;   \
       /*(sc)->sc_if.if_timer = 0;*/ \
    } while (/*CONSTCOND*/ 0)
   
   #define RADIO_PROBE_TIMEOUT(sc) \
            ((sc)-> sc_statetimo > time.tv_sec)
   
   
   
   /*
    * Called from boot code to establish sl interfaces.
    */
   void
   stripattach(n)
           int n;
   {
           struct strip_softc *sc;
           int i = 0;
   
           for (sc = strip_softc; i < NSTRIP; sc++) {
                   sc->sc_unit = i;                /* XXX */
                   sprintf(sc->sc_if.if_xname, "strip%d", i++);
                   callout_init(&sc->sc_timo_ch);
                   sc->sc_if.if_softc = sc;
                   sc->sc_if.if_mtu = SLMTU;
                   sc->sc_if.if_flags = 0;
                   sc->sc_if.if_type = IFT_OTHER;
   #if 0
                   sc->sc_if.if_flags |= SC_AUTOCOMP /* | IFF_POINTOPOINT | IFF_MULTICAST*/;
   #endif
                   sc->sc_if.if_type = IFT_SLIP;
                   sc->sc_if.if_ioctl = stripioctl;
                   sc->sc_if.if_output = stripoutput;
                   sc->sc_if.if_dlt = DLT_SLIP;
                   sc->sc_fastq.ifq_maxlen = 32;
                   IFQ_SET_READY(&sc->sc_if.if_snd);
   
                   sc->sc_if.if_watchdog = strip_watchdog;
                   if_attach(&sc->sc_if);
                   if_alloc_sadl(&sc->sc_if);
   #if NBPFILTER > 0
                   bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
   #endif
           }
   }
   
   static int
   stripinit(sc)
           struct strip_softc *sc;
   {
           u_char *p;
   
           if (sc->sc_mbuf == NULL) {
                   sc->sc_mbuf = m_get(M_WAIT, MT_DATA);
                   m_clget(sc->sc_mbuf, M_WAIT);
           }
           sc->sc_ep = (u_char *) sc->sc_mbuf->m_ext.ext_buf +
               sc->sc_mbuf->m_ext.ext_size;
           sc->sc_mp = sc->sc_pktstart = (u_char *) sc->sc_mbuf->m_ext.ext_buf +
               BUFOFFSET;
   
           /* Get contiguous buffer in which to de-bytestuff/rll-decode input */
           if (sc->sc_rxbuf == NULL) {
                   p = (u_char *)malloc(MCLBYTES, M_DEVBUF, M_WAITOK);
                   if (p)
                           sc->sc_rxbuf = p + SLBUFSIZE - SLMAX;
                   else {
                           printf("%s: can't allocate input buffer\n",
                               sc->sc_if.if_xname);
                           sc->sc_if.if_flags &= ~IFF_UP;
                           return (0);
                   }
           }
   
           /* Get contiguous buffer in which to bytestuff/rll-encode output */
           if (sc->sc_txbuf == NULL) {
                   p = (u_char *)malloc(MCLBYTES, M_DEVBUF, M_WAITOK);
                   if (p)
                           sc->sc_txbuf = (u_char *)p + SLBUFSIZE - SLMAX;
                   else {
                           printf("%s: can't allocate buffer\n",
                               sc->sc_if.if_xname);
                           
                           sc->sc_if.if_flags &= ~IFF_UP;
                           return (0);
                   }
           }
   
           sl_compress_init(&sc->sc_comp);
   
           /* Initialize radio probe/reset state machine */
           sc->sc_state = ST_DEAD;         /* assumet the worst. */
           sc->sc_statetimo = time.tv_sec; /* do reset immediately */
   
           return (1);
   }
   
   /*
    * Line specific open routine.
    * Attach the given tty to the first available sl unit.
    */
   /* ARGSUSED */
   int
   stripopen(dev, tp)
           dev_t dev;
           struct tty *tp;
   {
           struct proc *p = curproc;               /* XXX */
           struct strip_softc *sc;
           int nstrip;
           int error;
   #ifdef __NetBSD__
           int s;
   #endif
   
           if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
                   return (error);
   
           if (tp->t_linesw->l_no == STRIPDISC)
                   return (0);
   
           for (nstrip = NSTRIP, sc = strip_softc; --nstrip >= 0; sc++) {
                   if (sc->sc_ttyp == NULL) {
   #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
                           sc->sc_si = softintr_establish(IPL_SOFTNET,
                               stripintr, sc);
   #endif
                           if (stripinit(sc) == 0) {
   #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
                                   softintr_disestablish(sc->sc_si);
   #endif
                                   return (ENOBUFS);
                           }
                           tp->t_sc = (caddr_t)sc;
                           sc->sc_ttyp = tp;
                           sc->sc_if.if_baudrate = tp->t_ospeed;
                           ttyflush(tp, FREAD | FWRITE);
   #ifdef __NetBSD__
                           /*
                            * Make sure tty output queue is large enough
                            * to hold a full-sized packet (including frame
                            * end, and a possible extra frame end).
                            * A   full-sized   of 65/64) *SLMTU bytes (because
                            * of escapes and clever RLL bytestuffing),
                            * plus frame header, and add two on for frame ends.
                            */
                           s = spltty();
                           if (tp->t_outq.c_cn < STRIP_MTU_ONWIRE) {
                                   sc->sc_oldbufsize = tp->t_outq.c_cn;
                                   sc->sc_oldbufquot = tp->t_outq.c_cq != 0;
   
                                   clfree(&tp->t_outq);
                                   error = clalloc(&tp->t_outq, 3*SLMTU, 0);
                                   if (error) {
                                           splx(s);
   #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
                                           softintr_disestablish(sc->sc_si);
   #endif
                                           /*
                                            * clalloc() might return -1 which
                                            * is no good, so we need to return
                                            * something else.
                                            */
                                           return (ENOMEM);
                                   }
                           } else
                                   sc->sc_oldbufsize = sc->sc_oldbufquot = 0;
                           splx(s);
   #endif /* __NetBSD__ */
                           s = spltty();
                           strip_resetradio(sc, tp);
                           splx(s);
   
                           /*
                            * Start the watchdog timer to get the radio
                            * "probe-for-death"/reset machine going.
                            */
                           sc->sc_if.if_timer = STRIP_WATCHDOG_INTERVAL;
   
                           return (0);
                   }
           }
           return (ENXIO);
   }
   
   /*
    * Line specific close routine.
    * Detach the tty from the strip unit.
    */
   void
   stripclose(tp)
           struct tty *tp;
   {
           struct strip_softc *sc;
           int s;
   
           ttywflush(tp);
           sc = tp->t_sc;
   
           if (sc != NULL) {
   #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
                   softintr_disestablish(sc->sc_si);
   #endif
                   s = splnet();
                   /*
                    * Cancel watchdog timer, which stops the "probe-for-death"/
                    * reset machine.
                    */
                   sc->sc_if.if_timer = 0;
                   if_down(&sc->sc_if);
                   IF_PURGE(&sc->sc_fastq);
                   splx(s);
   
                   s = spltty();
                   tp->t_linesw = linesw[0];       /* default line disc. */
                   tp->t_state = 0;
   
                   sc->sc_ttyp = NULL;
                   tp->t_sc = NULL;
   
                   m_freem(sc->sc_mbuf);
                   sc->sc_mbuf = NULL;
                   sc->sc_ep = sc->sc_mp = sc->sc_pktstart = NULL;
                   IF_PURGE(&sc->sc_inq);
   
                   /* XXX */
                   free((caddr_t)(sc->sc_rxbuf - SLBUFSIZE + SLMAX), M_DEVBUF);
                   sc->sc_rxbuf = NULL;
   
                   /* XXX */
                   free((caddr_t)(sc->sc_txbuf - SLBUFSIZE + SLMAX), M_DEVBUF);
                   sc->sc_txbuf = NULL;
   
                   if (sc->sc_flags & SC_TIMEOUT) {
                           callout_stop(&sc->sc_timo_ch);
                           sc->sc_flags &= ~SC_TIMEOUT;
                   }
   
                   /*
                    * If necessary, install a new outq buffer of the
                    * appropriate size.
                    */
                   if (sc->sc_oldbufsize != 0) {
                           clfree(&tp->t_outq);
                           clalloc(&tp->t_outq, sc->sc_oldbufsize,
                               sc->sc_oldbufquot);
                   }
                   splx(s);
           }
   }
   
   /*
    * Line specific (tty) ioctl routine.
    * Provide a way to get the sl unit number.
    */
   /* ARGSUSED */
   int
   striptioctl(tp, cmd, data, flag)
           struct tty *tp;
           u_long cmd;
           caddr_t data;
           int flag;
   {
           struct strip_softc *sc = (struct strip_softc *)tp->t_sc;
   
           switch (cmd) {
           case SLIOCGUNIT:
                   *(int *)data = sc->sc_unit;
                   break;
   
           default:
                   return (EPASSTHROUGH);
           }
           return (0);
   }
   
   /*
    * Take an mbuf chain  containing a STRIP packet (no link-level header),
    * byte-stuff (escape) it, and enqueue it on the tty send queue.
    */
   void
   strip_sendbody(sc, m)
           struct strip_softc  *sc;
           struct mbuf *m;
   {
           struct tty *tp = sc->sc_ttyp;
           u_char *dp = sc->sc_txbuf;
           struct mbuf *m2;
           int len;
           u_char *rllstate_ptr = NULL;
   
           while (m) {
                   if (m->m_len != 0) {
                           /*
                            * Byte-stuff/run-length encode this mbuf's data
                            * into the output buffer.
                            * XXX Note that chained calls to stuffdata()
                            * require that the stuffed data be left in the
                            * output buffer until the entire packet is encoded.
                            */
                           dp = StuffData(mtod(m, u_char *), m->m_len, dp,
                               &rllstate_ptr);
                   }
                   MFREE(m, m2);
                   m = m2;
           }
   
           /*
            * Put the entire stuffed packet into the tty output queue.
            */
           len = dp - sc->sc_txbuf;
           if (b_to_q((ttychar_t *)sc->sc_txbuf, len, &tp->t_outq)) {
                   if (sc->sc_if.if_flags & IFF_DEBUG)
                           addlog("%s: tty output overflow\n",
                               sc->sc_if.if_xname);
                   return;
           }
           sc->sc_if.if_obytes += len;
   }
   
   /* 
    * Send a STRIP packet.  Must be called at spltty().
    */
   void
   strip_send(sc, m0)
           struct strip_softc *sc;
           struct mbuf *m0;
   {
           struct tty *tp = sc->sc_ttyp;
           struct st_header *hdr;
   
           /*
            * Send starmode header (unstuffed).
            */
           hdr = mtod(m0, struct st_header *);
           if (b_to_q((ttychar_t *)hdr, STRIP_HDRLEN, &tp->t_outq)) {
                   if (sc->sc_if.if_flags & IFF_DEBUG)
                           addlog("%s: outq overflow writing header\n",
                                    sc->sc_if.if_xname);
                   m_freem(m0);
                   return;
           }
   
           m_adj(m0, sizeof(struct st_header));
   
           /* Byte-stuff and run-length encode the remainder of the packet. */
           strip_sendbody(sc, m0);
   
           if (putc(STRIP_FRAME_END, &tp->t_outq)) {
                   /*
                    * Not enough room.  Remove a char to make room
                    * and end the packet normally.
                    * If you get many collisions (more than one or two
                    * a day) you probably do not have enough clists
                    * and you should increase "nclist" in param.c.
                    */
                   (void) unputc(&tp->t_outq);
                   (void) putc(STRIP_FRAME_END, &tp->t_outq);
                   sc->sc_if.if_collisions++;
           } else {
                   ++sc->sc_if.if_obytes;
                   sc->sc_if.if_opackets++;
           }
   
           /*
            * If a radio probe is due now, append it to this packet rather
            * than waiting until the watchdog routine next runs.
            */
           if (time.tv_sec >= sc->sc_statetimo && sc->sc_state == ST_ALIVE)
                   strip_proberadio(sc, tp);
   }
   
   /*
    * Queue a packet.  Start transmission if not active.
    * Compression happens in stripintr(); if we do it here, IP TOS
    * will cause us to not compress "background" packets, because
    * ordering gets trashed.  It can be done for all packets in stripintr().
    */
   int
   stripoutput(ifp, m, dst, rt)
           struct ifnet *ifp;
           struct mbuf *m;
           struct sockaddr *dst;
           struct rtentry *rt;
   {
           struct strip_softc *sc = ifp->if_softc;
           struct ip *ip;
           struct st_header *shp;
           const u_char *dldst;            /* link-level next-hop */
           struct ifqueue *ifq;
           int s, error;
           u_char dl_addrbuf[STARMODE_ADDR_LEN+1];
           ALTQ_DECL(struct altq_pktattr pktattr;)
   
           /*
            * Verify tty line is up and alive.
            */
           if (sc->sc_ttyp == NULL) {
                   m_freem(m);
                   return (ENETDOWN);      /* sort of */
           }
           if ((sc->sc_ttyp->t_state & TS_CARR_ON) == 0 &&
               (sc->sc_ttyp->t_cflag & CLOCAL) == 0) {
                   m_freem(m);
                   return (EHOSTUNREACH);
           }
   
   #define SDL(a)          ((struct sockaddr_dl *) (a))
   
   #ifdef DEBUG
           if (rt) {
                   printf("stripout, rt: dst af%d gw af%d",
                       rt_key(rt)->sa_family, rt->rt_gateway->sa_family);
                   if (rt_key(rt)->sa_family == AF_INET)
                     printf(" dst %x",
                         ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr);
                   printf("\n");
           }
   #endif
           switch (dst->sa_family) {
           case AF_INET:
                   if (rt != NULL && rt->rt_gwroute != NULL)
                           rt = rt->rt_gwroute;
   
                   /* assume rt is never NULL */
                   if (rt == NULL || rt->rt_gateway->sa_family != AF_LINK
                       || SDL(rt->rt_gateway)->sdl_alen != ifp->if_addrlen) {
                           DPRINTF(("strip: could not arp starmode addr %x\n",
                            ((struct sockaddr_in *)dst)->sin_addr.s_addr));
                           m_freem(m);
                           return (EHOSTUNREACH);
                   }
                   /*bcopy(LLADDR(SDL(rt->rt_gateway)), dldst, ifp->if_addrlen);*/
                   dldst = LLADDR(SDL(rt->rt_gateway));
                   break;
   
           case AF_LINK:
                   /*bcopy(LLADDR(SDL(rt->rt_gateway)), dldst, ifp->if_addrlen);*/
                   dldst = LLADDR(SDL(dst));
                   break;
   
           default:
                   /*
                    * `Cannot happen' (see stripioctl).  Someday we will extend
                    * the line protocol to support other address families.
                    */
                   printf("%s: af %d not supported\n", sc->sc_if.if_xname,
                       dst->sa_family);
                   m_freem(m);
                   sc->sc_if.if_noproto++;
                   return (EAFNOSUPPORT);
           }
           
           ip = mtod(m, struct ip *);
           if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
                   m_freem(m);
                   return (ENETRESET);             /* XXX ? */
           }
           if ((ip->ip_tos & IPTOS_LOWDELAY) != 0
   #ifdef ALTQ
               && ALTQ_IS_ENABLED(&ifp->if_snd) == 0
   #endif
               )
                   ifq = &sc->sc_fastq;
           else
                   ifq = NULL;
   
           /*
            * Add local net header.  If no space in first mbuf,
            * add another.
            */
           M_PREPEND(m, sizeof(struct st_header), M_DONTWAIT);
           if (m == 0) {
                   DPRINTF(("strip: could not prepend starmode header\n"));
                   return (ENOBUFS);
           }
   
           /*
            * Unpack BCD route entry into an ASCII starmode address.
            */
           dl_addrbuf[0] = '*';
   
           dl_addrbuf[1] = ((dldst[0] >> 4) & 0x0f) + '';
           dl_addrbuf[2] = ((dldst[0]     ) & 0x0f) + '';
   
           dl_addrbuf[3] = ((dldst[1] >> 4) & 0x0f) + '';
           dl_addrbuf[4] = ((dldst[1]     ) & 0x0f) + '';
   
           dl_addrbuf[5] = '-';
   
           dl_addrbuf[6] = ((dldst[2] >> 4) & 0x0f) + '';
           dl_addrbuf[7] = ((dldst[2]     ) & 0x0f) + '';
   
           dl_addrbuf[8] = ((dldst[3] >> 4) & 0x0f) + '';
           dl_addrbuf[9] = ((dldst[3]     ) & 0x0f) + '';
   
           dl_addrbuf[10] = '*';
           dl_addrbuf[11] = 0;
           dldst = dl_addrbuf;
   
           shp = mtod(m, struct st_header *);
           bcopy((caddr_t)"SIP0", (caddr_t)&shp->starmode_type,
                   sizeof(shp->starmode_type));
   
           bcopy((const char *)dldst, (caddr_t)shp->starmode_addr,
                   sizeof (shp->starmode_addr));
   
           s = spltty();
           if (sc->sc_oqlen && sc->sc_ttyp->t_outq.c_cc == sc->sc_oqlen) {
                   struct timeval tv;
   
                   /* if output's been stalled for too long, and restart */
                   timersub(&time, &sc->sc_lastpacket, &tv);
                   if (tv.tv_sec > 0) {
                           DPRINTF(("stripoutput: stalled, resetting\n"));
                           sc->sc_otimeout++;
                           stripstart(sc->sc_ttyp);
                   }
           }
           splx(s);
   
           s = splnet();
           if (ifq != NULL) {
                   if (IF_QFULL(ifq)) {
                           IF_DROP(ifq);
                           m_freem(m);
                           error = ENOBUFS;
                   } else {
                           IF_ENQUEUE(ifq, m);
                           error = 0;
                   }
           } else
                   IFQ_ENQUEUE(&ifp->if_snd, m, &pktattr, error);
           if (error) {
                   splx(s);
                   ifp->if_oerrors++;
                   return (error);
           }
           sc->sc_lastpacket = time;
           splx(s);
   
           s = spltty();
           stripstart(sc->sc_ttyp);
           splx(s);
   
           return (0);
   }
   
   
   /*
    * Start output on interface.  Get another datagram
    * to send from the interface queue and map it to
    * the interface before starting output.
    *
    */
   void
   stripstart(tp)
           struct tty *tp;
   {
           struct strip_softc *sc = tp->t_sc;
   
           /*
            * If there is more in the output queue, just send it now.
            * We are being called in lieu of ttstart and must do what
            * it would.
            */
           if (tp->t_outq.c_cc != 0) {
                   (*tp->t_oproc)(tp);
                   if (tp->t_outq.c_cc > SLIP_HIWAT)
                           return;
           }
   
           /*
            * This happens briefly when the line shuts down.
            */
           if (sc == NULL)
                   return;
   #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
           softintr_schedule(sc->sc_si);
   #else
       {
           int s = splhigh();
           schednetisr(NETISR_STRIP);
           splx(s);
       }
   #endif
   }
   
   /*
    * Copy data buffer to mbuf chain; add ifnet pointer.
    */
   static struct mbuf *
   strip_btom(sc, len)
           struct strip_softc *sc;
           int len;
   {
           struct mbuf *m;
   
           /*
            * Allocate a new input buffer and swap.
            */
           m = sc->sc_mbuf;
           MGETHDR(sc->sc_mbuf, M_DONTWAIT, MT_DATA);
           if (sc->sc_mbuf == NULL) {
                   sc->sc_mbuf = m;
                   return (NULL);
           }
           MCLGET(sc->sc_mbuf, M_DONTWAIT);
           if ((sc->sc_mbuf->m_flags & M_EXT) == 0) {
                   m_freem(sc->sc_mbuf);
                   sc->sc_mbuf = m;
                   return (NULL);
           }
           sc->sc_ep = (u_char *) sc->sc_mbuf->m_ext.ext_buf +
               sc->sc_mbuf->m_ext.ext_size;
   
           m->m_data = sc->sc_pktstart;
   
           m->m_pkthdr.len = m->m_len = len;
           m->m_pkthdr.rcvif = &sc->sc_if;
           return (m);
   }
   
   /*
    * tty interface receiver interrupt.
    *
    * Called with a single char from the tty receiver interrupt; put
    * the char into the buffer containing a partial packet. If the
    * char is a packet delimiter, decapsulate the packet, wrap it in
    * an mbuf, and put it on the protocol input queue.
   */
   void
   stripinput(c, tp)
           int c;
           struct tty *tp;
   {
           struct strip_softc *sc;
           struct mbuf *m;
           int len;
   
           tk_nin++;
           sc = (struct strip_softc *)tp->t_sc;
           if (sc == NULL)
                   return;
           if (c & TTY_ERRORMASK || ((tp->t_state & TS_CARR_ON) == 0 &&
               (tp->t_cflag & CLOCAL) == 0)) {
                   sc->sc_flags |= SC_ERROR;
                   DPRINTF(("strip: input, error %x\n", c));        /* XXX */
                   return;
           }
           c &= TTY_CHARMASK;
   
           ++sc->sc_if.if_ibytes;
   
           /*
            * Accumulate characters until we see a frame terminator (\r).
            */
           switch (c) {
   
           case '\n':
                   /*
                    * Error message strings from the modem are terminated with
                    * \r\n. This driver interprets the  \r as a packet terminator.
                    * If the first character in a packet is a \n, drop it.
                    * (it can never be the first char of a vaild frame).
                    */
                   if (sc->sc_mp - sc->sc_pktstart == 0)
                           break;
   
           /* Fall through to */
   
           default:
                   if (sc->sc_mp < sc->sc_ep) {
                           *sc->sc_mp++ = c;
                   } else {
                           sc->sc_flags |= SC_ERROR;
                          goto error;
                  }
                  return;
  
          case STRIP_FRAME_END:
                  break;
          }
  
  
          /*
           * We only reach here if we see a CR delimiting a packet.
           */
  
  
          len = sc->sc_mp - sc->sc_pktstart;
  
  #ifdef XDEBUG
          if (len < 15 || sc->sc_flags & SC_ERROR)
                  printf("stripinput: end of pkt, len %d, err %d\n",
                      len, sc->sc_flags & SC_ERROR); /*XXX*/
  #endif
          if(sc->sc_flags & SC_ERROR) {
                  sc->sc_flags &= ~SC_ERROR;
                  addlog("%s: sc error flag set. terminating packet\n",
                          sc->sc_if.if_xname);
                  goto newpack;
          }
  
          /*
           * We have a frame.
           * Process an IP packet, ARP packet, AppleTalk packet,
           * AT command resposne, or Starmode error.
           */
          len = strip_newpacket(sc, sc->sc_pktstart, sc->sc_mp);
          if (len <= 1)
                  /* less than min length packet - ignore */
                  goto newpack;
  
          m = strip_btom(sc, len);
          if (m == NULL)
                  goto error;
  
          IF_ENQUEUE(&sc->sc_inq, m);
  #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
          softintr_schedule(sc->sc_si);
  #else
      {
          int s = splhigh();
          schednetisr(NETISR_STRIP);
          splx(s);
      }
  #endif
          goto newpack;
  
  error:
          sc->sc_if.if_ierrors++;
  
  newpack:
          sc->sc_mp = sc->sc_pktstart = (u_char *) sc->sc_mbuf->m_ext.ext_buf +
              BUFOFFSET;
  }
  
  #ifndef __HAVE_GENERIC_SOFT_INTERRUPTS
  void
  stripnetisr(void)
  {
          struct strip_softc *sc;
          int i;
  
          for (i = 0; i < NSTRIP; i++) {
                  sc = &strip_softc[i];
                  if (sc->sc_ttyp == NULL)
                          continue;
                  stripintr(sc);
          }
  }
  #endif
  
  void
  stripintr(void *arg)
  {
          struct strip_softc *sc = arg;
          struct tty *tp = sc->sc_ttyp;
          struct mbuf *m;
          int s, len;
          u_char *pktstart, c;
  #if NBPFILTER > 0
          u_char chdr[CHDR_LEN];
  #endif
  
          KASSERT(tp != NULL);
  
          /*
           * Output processing loop.
           */
          for (;;) {
                  struct ip *ip;
  #if NBPFILTER > 0
                  struct mbuf *bpf_m;
  #endif
  
                  /*
                   * Do not remove the packet from the queue if it
                   * doesn't look like it will fit into the current
                   * serial output queue (STRIP_MTU_ONWIRE, or
                   * Starmode header + 20 bytes + 4 bytes in case we
                   * have to probe the radio).
                   */
                  s = spltty();
                  if (tp->t_outq.c_cn - tp->t_outq.c_cc <
                      STRIP_MTU_ONWIRE + 4) {
                          splx(s);
                          break;
                  }
                  splx(s);
  
                  /*
                   * Get a packet and send it to the radio.
                   */
                  s = splnet();
                  IF_DEQUEUE(&sc->sc_fastq, m);
                  if (m)
                          sc->sc_if.if_omcasts++; /* XXX */
                  else
                          IFQ_DEQUEUE(&sc->sc_if.if_snd, m);
                  splx(s);
  
                  if (m == NULL)
                          break;
  
                  /*
                   * We do the header compression here rather than in
                   * stripoutput() because the packets will be out of
                   * order if we are using TOS queueing, and the
                   * connection ID compression will get munged when
                   * this happens.
                   */
  #if NBPFILTER > 0
                  if (sc->sc_if.if_bpf) {
                          /*
                           * We need to save the TCP/IP header before
                           * it's compressed.  To avoid complicated
                           * code, we just make a deep copy of the
                           * entire packet (since this is a serial
                           * line, packets should be short and/or the
                           * copy should be negligible cost compared
                           * to the packet transmission time).
                           */
                          bpf_m = m_dup(m, 0, M_COPYALL, M_DONTWAIT);
                  } else
                          bpf_m = NULL;
  #endif
                  if ((ip = mtod(m, struct ip *))->ip_p == IPPROTO_TCP) {
                          if (sc->sc_if.if_flags & SC_COMPRESS)
                                  *mtod(m, u_char *) |=
                                      sl_compress_tcp(m, ip,
                                      &sc->sc_comp, 1);
                  }
  #if NBPFILTER > 0
                  if (sc->sc_if.if_bpf && bpf_m != NULL) {
                          /*
                           * Put the SLIP pseudo-"link header" in
                           * place.  The compressed header is now
                           * at the beginning of the mbuf.
                           */
                          struct mbuf n;
                          u_char *hp;
  
                          n.m_flags = 0;
                          n.m_next = bpf_m;
                          n.m_data = n.m_dat;
                          n.m_len = SLIP_HDRLEN;
  
                          hp = mtod(&n, u_char *);
  
                          hp[SLX_DIR] = SLIPDIR_OUT;
                          memcpy(&hp[SLX_CHDR], mtod(m, caddr_t),
                              CHDR_LEN);
  
                          s = splnet();
                          bpf_mtap(sc->sc_if.if_bpf, &n);
                          splx(s);
                          m_freem(bpf_m);
                  }
  #endif
                  sc->sc_lastpacket = time;
  
                  s = spltty();
                  strip_send(sc, m);
  
                  /*
                   * We now have characters in the output queue,
                   * kick the serial port.
                   */
                  if (tp->t_outq.c_cc != 0)
                          (*tp->t_oproc)(tp);
                  splx(s);
          }
  
          /*
           * Input processing loop.
           */
          for (;;) {
                  s = spltty();
                  IF_DEQUEUE(&sc->sc_inq, m);
                  splx(s);
                  if (m == NULL)
                          break;
                  pktstart = mtod(m, u_char *);
                  len = m->m_pkthdr.len;
  #if NBPFILTER > 0
                  if (sc->sc_if.if_bpf) {
                          /*
                           * Save the compressed header, so we
                           * can tack it on later.  Note that we
                           * will end up copying garbage in come
                           * cases but this is okay.  We remember
                           * where the buffer started so we can
                           * compute the new header length.
                           */
                          memcpy(chdr, pktstart, CHDR_LEN);
                  }
  #endif /* NBPFILTER > 0 */
                  if ((c = (*pktstart & 0xf0)) != (IPVERSION << 4)) {
                          if (c & 0x80)
                                  c = TYPE_COMPRESSED_TCP;
                          else if (c == TYPE_UNCOMPRESSED_TCP)
                                  *pktstart &= 0x4f; /* XXX */
                          /*
                           * We've got something that's not an IP
                           * packet.  If compression is enabled,
                           * try to decompress it.  Otherwise, if
                           * `auto-enable' compression is on and
                           * it's a reasonable packet, decompress
                           * it and then enable compression.
                           * Otherwise, drop it.
                           */
                          if (sc->sc_if.if_flags & SC_COMPRESS) {
                                  len = sl_uncompress_tcp(&pktstart, len,
                                      (u_int)c, &sc->sc_comp);
                                  if (len <= 0) {
                                          m_freem(m);
                                          continue;
                                  }
                          } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
                              c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
                                  len = sl_uncompress_tcp(&pktstart, len,
                                      (u_int)c, &sc->sc_comp);
                                  if (len <= 0) {
                                          m_freem(m);
                                          continue;
                                  }
                                  sc->sc_if.if_flags |= SC_COMPRESS;
                          } else {
                                  m_freem(m);
                                  continue;
                          }
                  }
                  m->m_data = (caddr_t) pktstart;
                  m->m_pkthdr.len = m->m_len = len;
  #if NPBFILTER > 0
                  if (sc->sc_if.if_bpf) {
                          /*
                           * Put the SLIP pseudo-"link header" in place.
                           * Note this M_PREPEND() should never fail,
                           * swince we know we always have enough space
                           * in the input buffer.
                           */
                          u_char *hp;
  
                          M_PREPEND(m, SLIP_HDRLEN, M_DONTWAIT);
                          if (m == NULL)
                                  continue;
  
                          hp = mtod(m, u_char *);
                          hp[SLX_DIR] = SLIPDIR_IN;
                          memcpy(&hp[SLX_CHDR], chdr, CHDR_LEN);
  
                          s = splnet();
                          bpf_mtap(sc->sc_if.if_bpf, m);
                          splx(s);
  
                          m_adj(m, SLIP_HDRLEN);
                  }
  #endif
                  /*
                   * If the packet will fit into a single
                   * header mbuf, copy it into one, to save
                   * memory.
                   */
                  if (m->m_pkthdr.len < MHLEN) {
                          struct mbuf *n;
  
                          MGETHDR(n, M_DONTWAIT, MT_DATA);
                          M_COPY_PKTHDR(n, m);
                          memcpy(mtod(n, caddr_t), mtod(m, caddr_t),
                              m->m_pkthdr.len);
                          n->m_len = m->m_len;
                          m_freem(m);
                          m = n;
                  }
  
                  sc->sc_if.if_ipackets++;
                  sc->sc_lastpacket = time;
  
                  s = splnet();
                  if (IF_QFULL(&ipintrq)) {
                          IF_DROP(&ipintrq);
                          sc->sc_if.if_ierrors++;
                          sc->sc_if.if_iqdrops++;
                          m_freem(m);
                  } else {
                          IF_ENQUEUE(&ipintrq, m);
                          schednetisr(NETISR_IP);
                  }
                  splx(s);
          }
  }
  
  /*
   * Process an ioctl request.
   */
  int
  stripioctl(ifp, cmd, data)
          struct ifnet *ifp;
          u_long cmd;
          caddr_t data;
  {
          struct ifaddr *ifa = (struct ifaddr *)data;
          struct ifreq *ifr;
          int s, error = 0;
  
          s = splnet();
  
          switch (cmd) {
  
          case SIOCSIFADDR:
                  if (ifa->ifa_addr->sa_family == AF_INET)
                          ifp->if_flags |= IFF_UP;
                  else
                          error = EAFNOSUPPORT;
                  break;
  
          case SIOCSIFDSTADDR:
                  if (ifa->ifa_addr->sa_family != AF_INET)
                          error = EAFNOSUPPORT;
                  break;
  
          case SIOCADDMULTI:
          case SIOCDELMULTI:
                  ifr = (struct ifreq *)data;
                  if (ifr == 0) {
                          error = EAFNOSUPPORT;           /* XXX */
                          break;
                  }
                  switch (ifr->ifr_addr.sa_family) {
  
  #ifdef INET
                  case AF_INET:
                          break;
  #endif
  
                  default:
                          error = EAFNOSUPPORT;
                          break;
                  }
                  break;
  
          default:
                  error = EINVAL;
          }
          splx(s);
          return (error);
  }
  
  
  /*
   * Strip subroutines
   */
  
  /*
   * Set a radio into starmode.
   * Must be called at spltty().
   */
  void
  strip_resetradio(sc, tp)
          struct strip_softc *sc;
          struct tty *tp;
  {
  #if 0
          static ttychar_t InitString[] =
                  "\r\n\r\n\r\nat\r\n\r\n\r\nate0dt**starmode\r\n**\r\n";
  #else
          static ttychar_t InitString[] =
                  "\r\rat\r\r\rate0q1dt**starmode\r**\r";
  #endif
          int i;
  
          /*
           * XXX Perhaps flush  tty output queue?
           */
  
          if ((i = b_to_q(InitString, sizeof(InitString) - 1, &tp->t_outq))) {
                  printf("resetradio: %d chars didn't fit in tty queue\n", i);
                  return;
          }
          sc->sc_if.if_obytes += sizeof(InitString) - 1;
  
          /*
           * Assume the radio is still dead, so we can detect repeated
           * resets (perhaps the radio is disconnected, powered off, or
           * is so badlyhung it needs  powercycling.
           */
          sc->sc_state = ST_DEAD;
          sc->sc_lastpacket = time;
          sc->sc_statetimo = time.tv_sec + STRIP_RESET_INTERVAL;
  
          /*
           * XXX Does calling the tty output routine now help resets?
           */
          (*sc->sc_ttyp->t_oproc)(tp);
  }
  
  
  /*
   * Send an invalid starmode packet to the radio, to induce an error message
   * indicating the radio is in starmode.
   * Update the state machine to indicate a response is expected.
   * Either the radio answers, which will be caught by the parser,
   * or the watchdog will start resetting.
   *
   * NOTE: drops chars directly on the tty output queue.
   * should be caled at spl >= spltty.
   */
  void
  strip_proberadio(sc, tp)
          struct strip_softc *sc;
          struct tty *tp;
  {
  
          int overflow;
          const char *strip_probestr = "**";
  
          if (sc->sc_if.if_flags & IFF_DEBUG)
                  addlog("%s: attempting to probe radio\n", sc->sc_if.if_xname);
  
          overflow = b_to_q((const ttychar_t *)strip_probestr, 2, &tp->t_outq);
          if (overflow == 0) {
                  if (sc->sc_if.if_flags & IFF_DEBUG)
                          addlog("%s:: sent probe  to radio\n",
                                 sc->sc_if.if_xname);
                  /* Go to probe-sent state, set timeout accordingly. */
                  sc->sc_state = ST_PROBE_SENT;
                  sc->sc_statetimo = time.tv_sec + ST_PROBERESPONSE_INTERVAL;
          } else {
                  addlog("%s: incomplete probe, tty queue %d bytes overfull\n",
                          sc->sc_if.if_xname, overflow);
          }
  }
  
  
  #ifdef DEBUG
  static char *strip_statenames[] = {
          "Alive",
          "Probe sent, awaiting answer",
          "Probe not answered, resetting"
  };
  #endif
  
  
  /*
   * Timeout routine -- try to start more output.
   * Will be needed to make strip work on ptys.
   */
  void
  strip_timeout(x)
      void *x;
  {
      struct strip_softc *sc = (struct strip_softc *) x;
      struct tty *tp =  sc->sc_ttyp;
      int s;
  
      s = spltty();
      sc->sc_flags &= ~SC_TIMEOUT;
      stripstart(tp);
      splx(s);
  }
  
          
  /*
   * Strip watchdog routine.
   * The radio hardware is balky. When sent long packets or bursts of small
   * packets, the radios crash and reboots into Hayes-emulation mode.
   * The transmit-side machinery, the error parser, and strip_watchdog()
   * implement a simple finite state machine.
   *
   * We attempt to send a probe to the radio every ST_PROBE seconds. There
   * is no direct way to tell if the radio is in starmode, so we send it a
   * malformed starmode packet -- a frame with no destination address --
   * and expect to an "name missing" error response from the radio within
   * 1 second. If we hear such a response, we assume the radio is alive
   * for the next ST_PROBE seconds.
   * If we don't hear a starmode-error response from  the radio, we reset it.
   *
   * Probes, and parsing of error responses,  are normally done inside the send
   * and receive side respectively. This watchdog routine examines the
   * state-machine variables. If there are no packets to send to the radio
   * during an entire probe interval, strip_output  will not be called,
   * so we send a probe on its behalf.
   */
  void
  strip_watchdog(ifp)
          struct ifnet *ifp;
  {
          struct strip_softc *sc = ifp->if_softc;
          struct tty *tp =  sc->sc_ttyp;
  
          /*
           * Just punt if the line has been closed.
           */
          if (tp == NULL)
                  return;
  
  #ifdef DEBUG
          if (ifp->if_flags & IFF_DEBUG)
                  addlog("\n%s: in watchdog, state %s timeout %ld\n",
                         ifp->if_xname,
                         ((unsigned) sc->sc_state < 3) ?
                         strip_statenames[sc->sc_state] : "<<illegal state>>",
                         sc->sc_statetimo - time.tv_sec);
  #endif
  
          /*
           * If time in this state hasn't yet expired, return.
           */
          if ((ifp->if_flags & IFF_UP) ==  0 || sc->sc_statetimo > time.tv_sec) {
                  goto done;
          }
  
          /*
           * The time in the current state has expired.
           * Take appropriate action and advance FSA to the next state.
           */
          switch (sc->sc_state) {
                case ST_ALIVE:
                  /*
                   * A probe is due but we haven't piggybacked one on a packet.
                   * Send a probe now.
                   */
                  strip_proberadio(sc, sc->sc_ttyp);
                  (*tp->t_oproc)(tp);
                  break;
  
                case ST_PROBE_SENT:
                  /*
                   * Probe sent but no response within timeout. Reset.
                   */
                  addlog("%s: no answer to probe, resetting radio\n",
                         ifp->if_xname);
                  strip_resetradio(sc, sc->sc_ttyp);
                  ifp->if_oerrors++;
                  break;
  
                case ST_DEAD:
                  /*
                   * The radio has been sent a reset but didn't respond.
                   * XXX warn user to remove AC adaptor and battery,
                   * wait  5 secs, and replace.
                   */
                  addlog("%s: radio reset but not responding, Trying again\n",
                         ifp->if_xname);
                  strip_resetradio(sc, sc->sc_ttyp);
                  ifp->if_oerrors++;
                  break;
  
                default:
                  /* Cannot happen. To be safe, do  a reset. */
                  addlog("%s: %s %d, resetting\n",
                         sc->sc_if.if_xname,
                         "radio-reset finite-state machine in invalid state",
                         sc->sc_state);
                  strip_resetradio(sc, sc->sc_ttyp);
                  sc->sc_state = ST_DEAD;
                  break;
          }
  
        done:
          ifp->if_timer = STRIP_WATCHDOG_INTERVAL;
          return;
  }
  
  
  /*
   * The following bytestuffing and run-length encoding/decoding
   * functions are taken, with permission from Stuart Cheshire,
   * from the MosquitonNet strip driver for Linux.
   * XXX Linux style left intact, to ease folding in updates from
   * the Mosquitonet group.
   */
  
  
  /*
   * Process a received packet.
   */
  int
  strip_newpacket(sc, ptr, end)
          struct strip_softc *sc;
          u_char *ptr, *end;
  {
          int len = ptr - end;
          u_char *name, *name_end;
          u_int packetlen;
  
          /* Ignore empty lines */
          if (len == 0) return 0;
  
          /* Catch 'OK' responses which show radio has fallen out of starmode */
          if (len >= 2 && ptr[0] == 'O' && ptr[1] == 'K') {
                  printf("%s: Radio is back in AT command mode: will reset\n",
                      sc->sc_if.if_xname);
                  FORCE_RESET(sc);                /* Do reset ASAP */
          return 0;
          }
  
          /* Check for start of address marker, and then skip over it */
          if (*ptr != '*') {
                  /* Catch other error messages */
                  if (ptr[0] == 'E' && ptr[1] == 'R' && ptr[2] == 'R' && ptr[3] == '_')
                          RecvErr_Message(sc, NULL, ptr+4);
                           /* XXX what should the message above be? */
                  else {
                          RecvErr("No initial *", sc);
                          addlog("(len = %d)\n", len);
                       }
                  return 0;
          }
  
          /* skip the '*' */
          ptr++;
  
          /* Skip the return address */
          name = ptr;
          while (ptr < end && *ptr != '*')
                  ptr++;
  
          /* Check for end of address marker, and skip over it */
          if (ptr == end) {
                  RecvErr("No second *", sc);
                  return 0;
          }
          name_end = ptr++;
  
          /* Check for SRIP key, and skip over it */
          if (ptr[0] != 'S' || ptr[1] != 'I' || ptr[2] != 'P' || ptr[3] != '') {
                  if (ptr[0] == 'E' && ptr[1] == 'R' && ptr[2] == 'R' &&
                      ptr[3] == '_') { 
                          *name_end = 0;
                          RecvErr_Message(sc, name, ptr+4);
                   }
                  else RecvErr("No SRIP key", sc);
                  return 0;
          }
          ptr += 4;
  
          /* Decode start of the IP packet header */
          ptr = UnStuffData(ptr, end, sc->sc_rxbuf, 4);
          if (ptr == 0) {
                  RecvErr("Runt packet (hdr)", sc);
                  return 0;
          }
  
          /*
           * The STRIP bytestuff/RLL encoding has no explicit length
           * of the decoded packet.  Decode start of IP header, get the
           * IP header length and decode that many bytes in total.
           */
          packetlen = ((u_int16_t)sc->sc_rxbuf[2] << 8) | sc->sc_rxbuf[3];
  
  #ifdef DIAGNOSTIC
  #if 0
          printf("Packet %02x.%02x.%02x.%02x\n",
                  sc->sc_rxbuf[0], sc->sc_rxbuf[1],
                  sc->sc_rxbuf[2], sc->sc_rxbuf[3]);
          printf("Got %d byte packet\n", packetlen);
  #endif
  #endif
  
          /* Decode remainder of the IP packer */
          ptr = UnStuffData(ptr, end, sc->sc_rxbuf+4, packetlen-4);
          if (ptr == 0) {
                  RecvErr("Short packet", sc);
                  return 0;
          }
  
          /* XXX redundant copy */
          bcopy(sc->sc_rxbuf, sc->sc_pktstart, packetlen );
          return (packetlen);
  }
  
  
  /*
   * Stuffing scheme:
   * 00    Unused (reserved character)
   * 01-3F Run of 2-64 different characters
   * 40-7F Run of 1-64 different characters plus a single zero at the end
   * 80-BF Run of 1-64 of the same character
   * C0-FF Run of 1-64 zeroes (ASCII 0)
  */
  typedef enum
  {
          Stuff_Diff      = 0x00,
          Stuff_DiffZero  = 0x40,
          Stuff_Same      = 0x80,
          Stuff_Zero      = 0xC0,
          Stuff_NoCode    = 0xFF,         /* Special code, meaning no code selected */
          
          Stuff_CodeMask  = 0xC0,
          Stuff_CountMask = 0x3F,
          Stuff_MaxCount  = 0x3F,
          Stuff_Magic     = 0x0D          /* The value we are eliminating */
  } StuffingCode;
  
  /*
   * StuffData encodes the data starting at "src" for "length" bytes.
   * It writes it to the buffer pointed to by "dest" (which must be at least
   * as long as 1 + 65/64 of the input length). The output may be up to 1.6%
   * larger than the input for pathological input, but will usually be smaller.
   * StuffData returns the new value of the dest pointer as its result.
   *
   * "code_ptr_ptr" points to a "u_char *" which is used to hold
   * encoding state between calls, allowing an encoded packet to be
   * incrementally built up from small parts.
   * On the first call, the "u_char *" pointed to should be initialized
   * to NULL;  between subsequent calls the calling routine should leave
   * the value alone and simply pass it back unchanged so that the
   * encoder can recover its current state.
   */ 
  
  #define StuffData_FinishBlock(X) \
          (*code_ptr = (X) ^ Stuff_Magic, code = Stuff_NoCode)
  
  static u_char*
  StuffData(u_char *src, u_long length, u_char *dest, u_char **code_ptr_ptr)
  {
          u_char *end = src + length;
          u_char *code_ptr = *code_ptr_ptr;
          u_char code = Stuff_NoCode, count = 0;
          
          if (!length) return (dest);
          
          if (code_ptr) { /* Recover state from last call, if applicable */
                  code  = (*code_ptr ^ Stuff_Magic) & Stuff_CodeMask;
                  count = (*code_ptr ^ Stuff_Magic) & Stuff_CountMask;
          }
  
          while (src < end) {
                  switch (code) {
                  /*
                   * Stuff_NoCode: If no current code, select one
                   */
                  case Stuff_NoCode:
                          code_ptr = dest++;      /* Record where we're going to put this code */
                          count = 0;              /* Reset the count (zero means one instance) */
                                                          /* Tentatively start a new block */
                          if (*src == 0) {
                                  code = Stuff_Zero;
                                  src++;
                          } else {
                                  code = Stuff_Same;
                                  *dest++ = *src++ ^ Stuff_Magic;
                          }
                          /* Note: We optimistically assume run of same -- which will be */
                          /* fixed later in Stuff_Same if it turns out not to be true. */
                          break;
  
                  /*
                   * Stuff_Zero: We already have at least one zero encoded
                   */
                  case Stuff_Zero:
                          
                          /* If another zero, count it, else finish this code block */
                          if (*src == 0) {
                                  count++;
                                  src++;
                          } else
                                  StuffData_FinishBlock(Stuff_Zero + count);
                          break;
  
                  /*
                   * Stuff_Same: We already have at least one byte encoded
                   */
                  case Stuff_Same:
                          /* If another one the same, count it */
                          if ((*src ^ Stuff_Magic) == code_ptr[1]) {
                                  count++;
                                  src++;
                                  break;
                          }
                          /* else, this byte does not match this block. */
                          /* If we already have two or more bytes encoded, finish this code block */
                          if (count) {
                                  StuffData_FinishBlock(Stuff_Same + count);
                                  break;
                          }
                          /* else, we only have one so far, so switch to Stuff_Diff code */
                          code = Stuff_Diff; /* and fall through to Stuff_Diff case below */
  
                  case Stuff_Diff:        /* Stuff_Diff: We have at least two *different* bytes encoded */
                          /* If this is a zero, must encode a Stuff_DiffZero, and begin a new block */
                          if (*src == 0)
                                  StuffData_FinishBlock(Stuff_DiffZero + count);
                          /* else, if we have three in a row, it is worth starting a Stuff_Same block */
                          else if ((*src ^ Stuff_Magic) == dest[-1] && dest[-1] == dest[-2])
                                  {
                                  code += count-2;
                                  if (code == Stuff_Diff)
                                          code = Stuff_Same;
                                  StuffData_FinishBlock(code);
                                  code_ptr = dest-2;
                                  /* dest[-1] already holds the correct value */
                                  count = 2;              /* 2 means three bytes encoded */
                                  code = Stuff_Same;
                                  }
                          /* else, another different byte, so add it to the block */
                          else {
                                  *dest++ = *src ^ Stuff_Magic;
                                  count++;
                          }
                          src++;  /* Consume the byte */
                          break;
                  }
  
                  if (count == Stuff_MaxCount)
                          StuffData_FinishBlock(code + count);
                  }
          if (code == Stuff_NoCode)
                  *code_ptr_ptr = NULL;
          else {
                  *code_ptr_ptr = code_ptr;
                  StuffData_FinishBlock(code + count);
          }
  
          return (dest);
  }
  
  
  
  /*
   * UnStuffData decodes the data at "src", up to (but not including)
   * "end".  It writes the decoded data into the buffer pointed to by
   * "dst", up to a  maximum of "dst_length", and returns the new
   * value of "src" so that a follow-on call can read more data,
   * continuing from where the first left off. 
   *
   * There are three types of results:
   * 1. The source data runs out before extracting "dst_length" bytes:
   *    UnStuffData returns NULL to indicate failure.
   * 2. The source data produces exactly "dst_length" bytes:
   *    UnStuffData returns new_src = end to indicate that all bytes
   *    were consumed. 
   * 3. "dst_length" bytes are extracted, with more
   *     remaining. UnStuffData returns new_src < end to indicate that
   *     there are more bytes to be read.
   *
   * Note: The decoding may be dstructive, in that it may alter the
   * source data in the process of decoding it (this is necessary to
   * allow a follow-on  call to resume correctly).
   */
  
  static u_char*
  UnStuffData(u_char *src, u_char *end, u_char *dst, u_long dst_length)
  {
          u_char *dst_end = dst + dst_length;
  
          /* Sanity check */
          if (!src || !end || !dst || !dst_length)
                  return (NULL);
  
          while (src < end && dst < dst_end)
          {
                  int count = (*src ^ Stuff_Magic) & Stuff_CountMask;
                  switch ((*src ^ Stuff_Magic) & Stuff_CodeMask)
                          {
                          case Stuff_Diff:
                                  if (src+1+count >= end)
                                          return (NULL);
                                  do
                                  {
                                          *dst++ = *++src ^ Stuff_Magic;
                                  }
                                  while(--count >= 0 && dst < dst_end);
                                  if (count < 0)
                                          src += 1;
                                  else
                                   if (count == 0)
                                          *src = Stuff_Same ^ Stuff_Magic;
                                  else
                                          *src = (Stuff_Diff + count) ^ Stuff_Magic;
                                  break;
                          case Stuff_DiffZero:
                                  if (src+1+count >= end)
                                          return (NULL);
                                  do
                                  {
                                          *dst++ = *++src ^ Stuff_Magic;
                                  }
                                  while(--count >= 0 && dst < dst_end);
                                  if (count < 0)
                                          *src = Stuff_Zero ^ Stuff_Magic;
                                  else
                                          *src = (Stuff_DiffZero + count) ^ Stuff_Magic;
                                  break;
                          case Stuff_Same:
                                  if (src+1 >= end)
                                          return (NULL);
                                  do
                                  {
                                          *dst++ = src[1] ^ Stuff_Magic;
                                  }
                                  while(--count >= 0 && dst < dst_end);
                                  if (count < 0)
                                          src += 2;
                                  else
                                          *src = (Stuff_Same + count) ^ Stuff_Magic;
                                  break;
                          case Stuff_Zero:
                                  do
                                  {
                                          *dst++ = 0;
                                  }
                                  while(--count >= 0 && dst < dst_end);
                                  if (count < 0)
                                          src += 1;
                                  else
                                          *src = (Stuff_Zero + count) ^ Stuff_Magic;
                                  break;
                          }
          }
  
          if (dst < dst_end)
                  return (NULL);
          else
                  return (src);
  }
  
  
  
  /*
   * Log an error mesesage (for a packet received with errors?)
   * from the STRIP driver.
   */
  static void
  RecvErr(msg, sc)
          char *msg;
          struct strip_softc *sc;
  {
  #define MAX_RecErr      80
          u_char *ptr = sc->sc_pktstart;
          u_char *end = sc->sc_mp;
          u_char pkt_text[MAX_RecErr], *p = pkt_text;
          *p++ = '\"';
          while (ptr < end && p < &pkt_text[MAX_RecErr-4]) {
                  if (*ptr == '\\') {
                          *p++ = '\\';
                          *p++ = '\\';
                  } else if (*ptr >= 32 && *ptr <= 126)
                          *p++ = *ptr;
                  else {
                          sprintf(p, "\\%02x", *ptr);
                          p+= 3;
                  }
                  ptr++;
          }
  
          if (ptr == end) *p++ = '\"';
          *p++ = 0;
          addlog("%s: %13s : %s\n", sc->sc_if.if_xname, msg, pkt_text);
  
          sc->sc_if.if_ierrors++;
  }
  
  
  /*
   * Parse an error message from the radio.
   */
  static void
  RecvErr_Message(strip_info, sendername, msg)
          struct strip_softc *strip_info;
          u_char *sendername;
          /*const*/ u_char *msg;
  {
          static const char ERR_001[] = "001"; /* Not in StarMode! */
          static const char ERR_002[] = "002"; /* Remap handle */
          static const char ERR_003[] = "003"; /* Can't resolve name */
          static const char ERR_004[] = "004"; /* Name too small or missing */
          static const char ERR_005[] = "005"; /* Bad count specification */
          static const char ERR_006[] = "006"; /* Header too big */
          static const char ERR_007[] = "007"; /* Body too big */
          static const char ERR_008[] = "008"; /* Bad character in name */
          static const char ERR_009[] = "009"; /* No count or line terminator */
  
          char * if_name;
  
          if_name = strip_info->sc_if.if_xname;
  
          if (!strncmp(msg, ERR_001, sizeof(ERR_001)-1))
          {
                  RecvErr("radio error message:", strip_info);
                  addlog("%s: Radio %s is not in StarMode\n",
                          if_name, sendername);
          }
          else if (!strncmp(msg, ERR_002, sizeof(ERR_002)-1))
          {
                  RecvErr("radio error message:", strip_info);
  #ifdef notyet           /*Kernel doesn't have scanf!*/
                  int handle;
                  u_char newname[64];
                  sscanf(msg, "ERR_002 Remap handle &%d to name %s", &handle, newname);
                  addlog("%s: Radio name %s is handle %d\n",
                          if_name, newname, handle);
  #endif
          }
          else if (!strncmp(msg, ERR_003, sizeof(ERR_003)-1))
          {
                  RecvErr("radio error message:", strip_info);
                  addlog("%s: Destination radio name is unknown\n", if_name);
          }
          else if (!strncmp(msg, ERR_004, sizeof(ERR_004)-1)) {
                  /*
                   * The radio reports it got a badly-framed starmode packet
                   * from us; so it must me in starmode.
                   */
                  if (strip_info->sc_if.if_flags & IFF_DEBUG)
                          addlog("%s: radio responded to probe\n", if_name);
                  if (strip_info->sc_state == ST_DEAD) {
                          /* A successful reset... */
                          addlog("%s: Radio back in starmode\n", if_name);
                  }
                  CLEAR_RESET_TIMER(strip_info);
          }
          else if (!strncmp(msg, ERR_005, sizeof(ERR_005)-1))
                  RecvErr("radio error message:", strip_info);
          else if (!strncmp(msg, ERR_006, sizeof(ERR_006)-1))
                  RecvErr("radio error message:", strip_info);
          else if (!strncmp(msg, ERR_007, sizeof(ERR_007)-1))
           {
                  /*
                   *      Note: This error knocks the radio back into
                   *      command mode.
                   */
                  RecvErr("radio error message:", strip_info);
                  printf("%s: Error! Packet size too big for radio.",
                      if_name);
                  FORCE_RESET(strip_info);
          }
          else if (!strncmp(msg, ERR_008, sizeof(ERR_008)-1))
          {
                  RecvErr("radio error message:", strip_info);
                  printf("%s: Radio name contains illegal character\n",
                      if_name);
          }
          else if (!strncmp(msg, ERR_009, sizeof(ERR_009)-1))
                  RecvErr("radio error message:", strip_info);
          else {
                  addlog("failed to parse ]%3s[\n", msg);
                  RecvErr("unparsed radio error message:", strip_info);
          }
  }

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