sync

1 files changed, 1714 insertions, 0 deletions

diff --git a/sys/net/if_strip.c b/sys/net/if_strip.c
new file mode 100644
index 00000000000..7256fdcc4ef
--- /dev/null
+++ b/sys/net/if_strip.c
@@ -0,0 +1,1714 @@
+/*	$NetBSD: if_strip.c,v 1.2 1996/05/19 22:09:36 jonathan 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 st0, use the command 
+ *
+ *	route add -host 10.1.2.3  -link st0:12:34:56:78
+ */
+
+
+/*
+ * 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. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. 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.
+ * 
+ * Note that splimp() is used throughout to block both (tty) input
+ * interrupts and network activity; thus, splimp must be >= spltty.
+ */
+
+#include "strip.h"
+#if NSTRIP > 0
+
+#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/tty.h>
+#include <sys/kernel.h>
+#include <sys/conf.h>
+#if __NetBSD__
+#include <sys/systm.h>
+#endif
+#include <sys/syslog.h>
+
+#include <machine/cpu.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/netisr.h>
+#include <net/route.h>
+
+#if 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.
+ */
+#if NBPFILTER > 0
+#define	BUFOFFSET	(128+sizeof(struct ifnet **)+SLIP_HDRLEN)
+#else
+#define	BUFOFFSET	(128+sizeof(struct ifnet **))
+#endif
+#define	SLMAX		(MCLBYTES - BUFOFFSET)
+#define	SLBUFSIZE	(SLMAX + BUFOFFSET)
+#define SLMTU		1200 /*XXX*/
+
+#define	SLIP_HIWAT	roundup(50,CBSIZE)
+
+#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 st_softc st_softc[NSTRIP];
+
+#define STRIP_FRAME_END		0x0D		/* carriage return */
+
+
+static int stripinit __P((struct st_softc *));
+static 	struct mbuf *strip_btom __P((struct st_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 RecErr __P((char *msg, struct st_softc *sc));
+static void RecERR_Message __P((struct st_softc *strip_info,
+				u_char *sendername, u_char *msg));
+void	resetradio __P((struct st_softc *sc, struct tty *tp));
+void	strip_esc __P((struct st_softc *sc, struct mbuf *m));
+int	strip_newpacket __P((struct st_softc *sc, u_char *ptr, u_char *end));
+struct mbuf * strip_send __P((struct st_softc *sc, struct mbuf *m0));
+
+
+#ifdef DEBUG
+void ipdump __P((const char *msg, u_char *p, int len));
+void stripdump __P((const char *msg, u_char *p, int len));
+void stripdumpm __P((const char *msg, struct mbuf *m, int len));
+#define DPRINTF(x)	printf x
+#define TXPRINTF(x)	printf x/* causes outrageous delays */
+#define RXPRINTF(x)	printf x /* causes outrageous delays */
+#else
+#define DPRINTF(x)
+#define TXPRINTF(x)
+#define RXPRINTF(x)
+#endif
+
+#define XDPRINTF(x)	/* really verbose debugging */
+
+
+/*
+ * 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.
+ */
+
+#define FORCE_RESET(sc) \
+ do {\
+    printf("strip: XXX: reset state-machine not yet implemented in *BSD\n"); \
+ } while (0)
+
+#define CLEAR_RESET_TIMER(sc) \
+ do {\
+    printf("strip: clearing  reset timeout: not yet implemented in *BSD\n"); \
+ } while (0)
+
+
+
+/*
+ * Called from boot code to establish sl interfaces.
+ */
+void
+stripattach(n)
+	int n;
+{
+	register struct st_softc *sc;
+	register int i = 0;
+
+	for (sc = st_softc; i < NSTRIP; sc++) {
+		sprintf(sc->sc_if.if_xname, "st%d", i++);
+		sc->sc_if.if_softc = sc;
+		sc->sc_unit = i;		/* XXX */
+		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_snd.ifq_maxlen = 50;
+		sc->sc_fastq.ifq_maxlen = 32;
+		if_attach(&sc->sc_if);
+#if NBPFILTER > 0
+		bpfattach(&sc->sc_bpf, &sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
+#endif
+	}
+}
+
+static int
+stripinit(sc)
+	register struct st_softc *sc;
+{
+	register caddr_t p;
+
+	if (sc->sc_ep == (u_char *) 0) {
+		MCLALLOC(p, M_WAIT);
+		if (p)
+			sc->sc_ep = (u_char *)p + SLBUFSIZE;
+		else {
+			printf("sl%d: can't allocate buffer\n", sc - st_softc);
+			sc->sc_if.if_flags &= ~IFF_UP;
+			return (0);
+		}
+	}
+
+	/* get buffer in which to unstuff input */
+	if (sc->sc_rxbuf == (u_char *) 0) {
+		MCLALLOC(p, M_WAIT);
+		if (p)
+			sc->sc_rxbuf = (u_char *)p + SLBUFSIZE - SLMAX;
+		else {
+			printf("sl%d: can't allocate buffer\n", sc - st_softc);
+			sc->sc_if.if_flags &= ~IFF_UP;
+			return (0);
+		}
+	}
+
+	/* get buffer in which to stuff output */
+	if (sc->sc_txbuf == (u_char *) 0) {
+		MCLALLOC(p, M_WAIT);
+		if (p)
+			sc->sc_txbuf = (u_char *)p + SLBUFSIZE - SLMAX;
+		else {
+			printf("sl%d: can't allocate buffer\n", sc - st_softc);
+			
+			sc->sc_if.if_flags &= ~IFF_UP;
+			return (0);
+		}
+	}
+
+	sc->sc_buf = sc->sc_ep - SLMAX;
+	sc->sc_mp = sc->sc_buf;
+	sl_compress_init(&sc->sc_comp, -1);
+
+	return (1);
+}
+
+/*
+ * Line specific open routine.
+ * Attach the given tty to the first available sl unit.
+ */
+/* ARGSUSED */
+int
+stripopen(dev, tp)
+	dev_t dev;
+	register struct tty *tp;
+{
+	struct proc *p = curproc;		/* XXX */
+	register struct st_softc *sc;
+	register int nstrip;
+	int error;
+#ifdef __NetBSD__
+	int s;
+#endif
+
+	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
+		return (error);
+
+	if (tp->t_line == STRIPDISC)
+		return (0);
+
+	for (nstrip = NSTRIP, sc = st_softc; --nstrip >= 0; sc++)
+		if (sc->sc_ttyp == NULL) {
+			if (stripinit(sc) == 0)
+				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).  full-sized
+			 * packet occupies a max of 2*SLMTU bytes (because
+			 * of possible escapes), and add two on for frame
+			 * ends.
+			 */
+			s = spltty();
+			if (tp->t_outq.c_cn < 2*SLMTU+2) {
+				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);
+					return(error);
+				}
+			} else
+				sc->sc_oldbufsize = sc->sc_oldbufquot = 0;
+			splx(s);
+#endif /* __NetBSD__ */
+			s = spltty();
+			resetradio(sc, tp);
+			splx(s);
+
+			return (0);
+		}
+	return (ENXIO);
+}
+
+/*
+ * Line specific close routine.
+ * Detach the tty from the sl unit.
+ */
+void
+stripclose(tp)
+	struct tty *tp;
+{
+	register struct st_softc *sc;
+	int s;
+
+	ttywflush(tp);
+
+	DPRINTF(("stripclose: closing\n"));
+	s = splimp();		/* actually, max(spltty, splsoftnet) */
+	tp->t_line = 0;
+	sc = (struct st_softc *)tp->t_sc;
+	if (sc != NULL) {
+		if_down(&sc->sc_if);
+		sc->sc_ttyp = NULL;
+		tp->t_sc = NULL;
+		MCLFREE((caddr_t)(sc->sc_ep - SLBUFSIZE));
+		MCLFREE((caddr_t)(sc->sc_rxbuf - SLBUFSIZE + SLMAX)); /* XXX */
+		MCLFREE((caddr_t)(sc->sc_txbuf - SLBUFSIZE + SLMAX)); /* XXX */
+		sc->sc_ep = 0;
+		sc->sc_mp = 0;
+		sc->sc_buf = 0;
+		sc->sc_rxbuf = 0;
+		sc->sc_txbuf = 0;
+	}
+#ifdef __NetBSD__
+	/* 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);
+	}
+#endif
+	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 st_softc *sc = (struct st_softc *)tp->t_sc;
+
+	switch (cmd) {
+	case SLIOCGUNIT:
+		*(int *)data = sc->sc_unit;
+		break;
+
+	default:
+		return (-1);
+	}
+	return (0);
+}
+
+/*XXX*/
+/*
+ * Take an mbuf chain  containing a SLIP packet, byte-stuff (escape)
+ * the packet, and enqueue it on the tty send queue.
+ */
+void
+strip_esc(sc, m)
+	struct st_softc  *sc;
+	struct mbuf *m;
+{
+	register struct tty *tp = sc->sc_ttyp;
+	register u_char *cp;
+	register u_char *ep;
+	struct mbuf *m2;
+	register int len;
+	u_char         *stuffstate = NULL;
+
+	while (m) {
+		cp = mtod(m, u_char *); ep = cp + m->m_len;
+		/*
+		 * Find out how many bytes in the string we can
+		 * handle without doing something special.
+		 */
+		ep = StuffData(cp, m->m_len, sc->sc_txbuf, &stuffstate);
+		len = ep - sc->sc_txbuf;
+
+		/*
+		 * Put n characters at once
+		 * into the tty output queue.
+		 */
+		if (b_to_q((ttychar_t *)sc->sc_txbuf,
+			   len, &tp->t_outq))
+			goto bad;
+		sc->sc_if.if_obytes += len;
+		MFREE(m, m2);
+		m = m2;
+	}
+	return;
+
+bad:
+	m_freem(m);
+	return;
+}
+
+/* 
+ *  Prepend a STRIP header to the packet.
+ * (based on 4.4bsd if_ppp)
+ */
+struct mbuf *
+strip_send(sc, m0)
+    struct st_softc *sc;
+    struct mbuf *m0;
+{
+	register 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)) {
+	  	TXPRINTF(("prepend: outq overflow\n"));
+		m_freem(m0);
+	}
+
+	/* XXX undo M_PREPEND() */
+	m0->m_data += sizeof(struct st_header);
+	m0->m_len -= sizeof(struct st_header);
+	if (m0 && m0->m_flags & M_PKTHDR)
+		m0->m_pkthdr.len -= sizeof(struct st_header);
+	
+
+	strip_esc(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++;
+	}
+	return(m0);
+}
+
+
+
+/*
+ * Queue a packet.  Start transmission if not active.
+ * Compression happens in slstart; 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 slstart.
+ */
+int
+stripoutput(ifp, m, dst, rt)
+	struct ifnet *ifp;
+	register struct mbuf *m;
+	struct sockaddr *dst;
+	struct rtentry *rt;
+{
+	register struct st_softc *sc = ifp->if_softc;
+	register struct ip *ip;
+	register struct ifqueue *ifq;
+	register struct st_header *shp;
+	register const u_char *dldst;		/* link-level next-hop */
+	int s;
+	u_char dl_addrbuf[STARMODE_ADDR_LEN+1];
+
+
+	/*
+	 * 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:
+		/* XXX untested */
+
+                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);
+	}
+	
+	ifq = &sc->sc_if.if_snd;
+	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)
+		ifq = &sc->sc_fastq;
+
+	/*
+	 * 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) + '0';
+	dl_addrbuf[2] = ((dldst[0]     ) & 0x0f) + '0';
+
+	dl_addrbuf[3] = ((dldst[1] >> 4) & 0x0f) + '0';
+	dl_addrbuf[4] = ((dldst[1]     ) & 0x0f) + '0';
+
+	dl_addrbuf[5] = '-';
+
+	dl_addrbuf[6] = ((dldst[2] >> 4) & 0x0f) + '0';
+	dl_addrbuf[7] = ((dldst[2]     ) & 0x0f) + '0';
+
+	dl_addrbuf[8] = ((dldst[3] >> 4) & 0x0f) + '0';
+	dl_addrbuf[9] = ((dldst[3]     ) & 0x0f) + '0';
+
+	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((caddr_t)dldst, (caddr_t)shp->starmode_addr,
+		sizeof (shp->starmode_addr));
+
+	TXPRINTF(("strip address is %16s\n", (char *)shp));
+
+	s = splimp();
+	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_if.if_lastchange, &tv);
+		if (tv.tv_sec > 0) {
+ /*XXX*/  		DPRINTF(("stripoutput: stalled, resetting\n"));
+			sc->sc_otimeout++;
+			stripstart(sc->sc_ttyp);
+		}
+	}
+	if (IF_QFULL(ifq)) {
+		IF_DROP(ifq);
+		m_freem(m);
+		splx(s);
+		sc->sc_if.if_oerrors++;
+ /*XXX*/  	TXPRINTF(("stripoutput: ifq full\n"));
+		return (ENOBUFS);
+	}
+	IF_ENQUEUE(ifq, m);
+	sc->sc_if.if_lastchange = time;
+	if ((sc->sc_oqlen = sc->sc_ttyp->t_outq.c_cc) == 0) {
+ /*XXX*/  		TXPRINTF(("stripoutput: enqueued pkt, restarting\n"));
+		stripstart(sc->sc_ttyp);
+	}
+/* XXX FIXME */
+	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)
+	register struct tty *tp;
+{
+	register struct st_softc *sc = (struct st_softc *)tp->t_sc;
+	register struct mbuf *m;
+	register struct ip *ip;
+	int s;
+#if NBPFILTER > 0
+	u_char bpfbuf[SLMTU + SLIP_HDRLEN];
+	register int len = 0;
+#endif
+#ifndef __NetBSD__					/* XXX - cgd */
+	extern int cfreecount;
+#endif
+	for (;;) {
+/*XXX*/		TXPRINTF(("stripstart\n"));
+		/*
+		 * 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) {
+			  	TXPRINTF(("stripstart: outq past SLIP_HIWAT\n"));
+#if 0
+				/* XXX can't  just stop output on
+				   framed  packet-radio links!
+				   */
+				return;
+#endif
+			}
+		}
+		/*
+		 * This happens briefly when the line shuts down.
+		 */
+		if (sc == NULL) {
+		  	TXPRINTF(("(shutdown)\n"));
+			return;
+		}
+
+#if 0						 	/* XXX - jrs*/
+#if defined(__NetBSD__)					/* XXX - cgd */
+		/*
+		 * Do not remove the packet from the IP queue if it
+		 * doesn't look like the packet will fit into the
+		 * current serial output queue, with a packet full of
+		 * escapes this could be as bad as SLMTU*2+2.
+		 */
+		if (tp->t_outq.c_cn - tp->t_outq.c_cc < 2*SLMTU+2)
+			return;
+#endif /* __NetBSD__ */
+#endif
+		/*
+		 * Get a packet and send it to the interface.
+		 */
+		s = splimp();
+		IF_DEQUEUE(&sc->sc_fastq, m);
+		if (m)
+			sc->sc_if.if_omcasts++;		/* XXX */
+		else
+			IF_DEQUEUE(&sc->sc_if.if_snd, m);
+		splx(s);
+		if (m == NULL) {
+/*XXX*/			TXPRINTF(("(empty q)\n"));
+			return;
+		}
+		/*
+		 * 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_bpf) {
+			/*
+			 * We need to save the TCP/IP header before it's
+			 * compressed.  To avoid complicated code, we just
+			 * copy the entire packet into a stack buffer (since
+			 * this is a serial line, packets should be short
+			 * and/or the copy should be negligible cost compared
+			 * to the packet transmission time).
+			 */
+			register struct mbuf *m1 = m;
+			register u_char *cp = bpfbuf + SLIP_HDRLEN;
+
+			len = 0;
+			do {
+				register int mlen = m1->m_len;
+
+				bcopy(mtod(m1, caddr_t), cp, mlen);
+				cp += mlen;
+				len += mlen;
+			} while ((m1 = m1->m_next) != 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_bpf) {
+			/*
+			 * Put the SLIP pseudo-"link header" in place.  The
+			 * compressed header is now at the beginning of the
+			 * mbuf.
+			 */
+			bpfbuf[SLX_DIR] = SLIPDIR_OUT;
+			bcopy(mtod(m, caddr_t), &bpfbuf[SLX_CHDR], CHDR_LEN);
+			bpf_tap(sc->sc_bpf, bpfbuf, len + SLIP_HDRLEN);
+		}
+#endif
+		sc->sc_if.if_lastchange = time;
+
+#ifndef __NetBSD__					/* XXX - cgd */
+		/*
+		 * If system is getting low on clists, just flush our
+		 * output queue (if the stuff was important, it'll get
+		 * retransmitted).
+		 */
+		if (cfreecount < CLISTRESERVE + SLMTU) {
+			m_freem(m);
+			sc->sc_if.if_collisions++;
+			continue;
+		}
+#endif /* !__NetBSD__ */
+
+
+		if (strip_send(sc, m) == NULL) {
+/*XXX*/	 	 	DPRINTF(("stripsend: failed to send pkt\n"));
+		}
+	}
+}
+
+
+
+/*
+ * Copy data buffer to mbuf chain; add ifnet pointer.
+ */
+static struct mbuf *
+strip_btom(sc, len)
+	register struct st_softc *sc;
+	register int len;
+{
+	register struct mbuf *m;
+
+	MGETHDR(m, M_DONTWAIT, MT_DATA);
+	if (m == NULL)
+		return (NULL);
+
+	/*
+	 * If we have more than MHLEN bytes, it's cheaper to
+	 * queue the cluster we just filled & allocate a new one
+	 * for the input buffer.  Otherwise, fill the mbuf we
+	 * allocated above.  Note that code in the input routine
+	 * guarantees that packet will fit in a cluster.
+	 */
+	if (len >= MHLEN) {
+		MCLGET(m, M_DONTWAIT);
+		if ((m->m_flags & M_EXT) == 0) {
+			/*
+			 * we couldn't get a cluster - if memory's this
+			 * low, it's time to start dropping packets.
+			 */
+			(void) m_free(m);
+			return (NULL);
+		}
+		sc->sc_ep = mtod(m, u_char *) + SLBUFSIZE;
+		m->m_data = (caddr_t)sc->sc_buf;
+		m->m_ext.ext_buf = (caddr_t)((long)sc->sc_buf &~ MCLOFSET);
+		TXPRINTF(("strip_btom: new cluster for sc_buf\n"));
+		XDPRINTF(("XXX 1: sc_buf %x end %x hardlim %x\n",
+			 sc->sc_buf, sc->sc_mp, sc->sc_ep));
+	} else
+		bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);
+
+	m->m_len = len;
+	m->m_pkthdr.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)
+	register int c;
+	register struct tty *tp;
+{
+	register struct st_softc *sc;
+	register struct mbuf *m;
+	register int len;
+	int s;
+#if NBPFILTER > 0
+	u_char chdr[CHDR_LEN];
+#endif
+
+	tk_nin++;
+	sc = (struct st_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;
+
+	switch (c) {
+
+#ifdef notanymore
+	case 0x0a:
+	/* (leading newline characters are ignored) */
+		if (sc->sc_mp - sc->sc_buf == 0)
+		  return;
+#endif
+
+
+	case STRIP_FRAME_END:
+		len = sc->sc_mp - sc->sc_buf;
+
+#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;
+			goto newpack;
+		}
+
+		len = strip_newpacket(sc, sc->sc_buf, sc->sc_mp);
+		if (len <= 1)
+			/* less than min length packet - ignore */
+			goto newpack;
+#if DEBUG > 1
+		ipdump("after destuff", sc->sc_buf, len);
+#endif /* DEBUG */		
+
+
+
+#if NBPFILTER > 0
+		if (sc->sc_bpf) {
+			/*
+			 * Save the compressed header, so we
+			 * can tack it on later.  Note that we
+			 * will end up copying garbage in some
+			 * cases but this is okay.  We remember
+			 * where the buffer started so we can
+			 * compute the new header length.
+			 */
+			bcopy(sc->sc_buf, chdr, CHDR_LEN);
+		}
+#endif
+
+		if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
+			if (c & 0x80)
+				c = TYPE_COMPRESSED_TCP;
+			else if (c == TYPE_UNCOMPRESSED_TCP)
+				*sc->sc_buf &= 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(&sc->sc_buf, len,
+							(u_int)c, &sc->sc_comp);
+				if (len <= 0)
+					goto error;
+			} else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
+			    c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
+				len = sl_uncompress_tcp(&sc->sc_buf, len,
+							(u_int)c, &sc->sc_comp);
+				if (len <= 0)
+					goto error;
+				sc->sc_if.if_flags |= SC_COMPRESS;
+			} else
+				goto error;
+		}
+#if NBPFILTER > 0
+		if (sc->sc_bpf) {
+			/*
+			 * Put the SLIP pseudo-"link header" in place.
+			 * We couldn't do this any earlier since
+			 * decompression probably moved the buffer
+			 * pointer.  Then, invoke BPF.
+			 */
+			register u_char *hp = sc->sc_buf - SLIP_HDRLEN;
+
+			hp[SLX_DIR] = SLIPDIR_IN;
+			bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
+			bpf_tap(sc->sc_bpf, hp, len + SLIP_HDRLEN);
+		}
+#endif
+		m = strip_btom(sc, len);
+		if (m == NULL)
+			goto error;
+
+		sc->sc_if.if_ipackets++;
+		sc->sc_if.if_lastchange = time;
+		s = splimp();
+		if (IF_QFULL(&ipintrq)) {
+			IF_DROP(&ipintrq);
+			DPRINTF(("stripinput: ipintrq full\n"));
+			sc->sc_if.if_ierrors++;
+			sc->sc_if.if_iqdrops++;
+			m_freem(m);
+		} else {
+			IF_ENQUEUE(&ipintrq, m);
+			schednetisr(NETISR_IP);
+		}
+		splx(s);
+		goto newpack;
+	}
+
+	if (sc->sc_mp < sc->sc_ep) {
+		*sc->sc_mp++ = c;
+		/*sc->sc_escape = 0;*/
+		return;
+	}
+
+	/* can't put lower; would miss an extra frame */
+	sc->sc_flags |= SC_ERROR;
+	DPRINTF(("stripinput: overran buf\n"));
+	goto quiet_error;
+
+error:
+	RXPRINTF(("stripinput: error\n"));
+quiet_error:
+	sc->sc_if.if_ierrors++;
+	goto quiet_newpack;
+
+newpack:
+	/*DPRINTF(("stripinput: newpack\n"));*/	 /* XXX */
+quiet_newpack:
+	sc->sc_mp = sc->sc_buf = sc->sc_ep - SLMAX;
+	/*sc->sc_escape = 0;*/
+}
+
+/*
+ * Process an ioctl request.
+ */
+int
+stripioctl(ifp, cmd, data)
+	register struct ifnet *ifp;
+	u_long cmd;
+	caddr_t data;
+{
+	register struct ifaddr *ifa = (struct ifaddr *)data;
+	register struct ifreq *ifr;
+	register int s = splimp(), error = 0;
+
+	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:
+
+#ifdef DEBUG
+	  printf("stripioctl: unknown request 0x%lx\n", cmd);
+#endif
+		error = EINVAL;
+	}
+	splx(s);
+	return (error);
+}
+/*
+ * Strip subroutines
+ */
+
+/*
+ * Set a radio into starmode.
+ */
+void
+resetradio(sc, tp)
+	struct st_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\rate0dt**starmode\r*\r";
+#endif
+	register int i;
+
+
+	DPRINTF(("strip: resetting radio\n"));
+	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;
+
+#ifdef linux /*XXX*/
+	/* reset the watchdog counter */
+	sc->watchdog_doprobe = jiffies + 10 * HZ;
+	sc->watchdog_doreset = jiffies + 1 * HZ;
+#endif
+	/*XXX jrs DANGEROUS - does this help? */
+	sc->sc_if.if_lastchange = time;
+
+	/*XXX jrs DANGEROUS - does this work? */
+	(*sc->sc_ttyp->t_oproc)(tp);
+}
+
+
+/*
+ * XXX
+ * The following is taken, with permisino of the author, from
+ * the LInux strip  driver. 
+ */
+
+
+/*
+ * Process a received packet.
+ */
+int
+strip_newpacket(sc, ptr, end)
+	struct st_softc *sc;
+	register u_char *ptr, *end;
+{
+	register int len = ptr - end;
+	register 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] == '_')
+			RecERR_Message(sc, NULL, ptr); /* XXX stuart? */
+		else {
+			RecErr("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) {
+		RecErr("No second *", sc);
+		XDPRINTF(("XXX 3: sc_buf %x ptr %x end %x mp %x hardlim %x\n",
+			 sc->sc_buf, ptr, end, sc->sc_mp, sc->sc_ep));
+		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] != '0') {
+		if (ptr[0] == 'E' && ptr[1] == 'R' && ptr[2] == 'R' &&
+		    ptr[3] == '_') { 
+			*name_end = 0;
+			RecERR_Message(sc, name, ptr);
+		 }
+		else RecErr("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) {
+		RecErr("Runt packet (hdr)", sc);
+		return 0;
+	}
+
+	/* XXX is this the IP header length, or what? */
+	packetlen = ((u_short)sc->sc_rxbuf[2] << 8) | sc->sc_rxbuf[3];
+/*	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); */
+
+	/* Decode remainder of the IP packer */
+	ptr = UnStuffData(ptr, end, sc->sc_rxbuf+4, packetlen-4);
+	if (!ptr) {
+		RecErr("Short packet", sc);
+		return 0;
+	}
+
+	/* XXX*/ bcopy(sc->sc_rxbuf, sc->sc_buf, packetlen );
+
+#ifdef linux
+	strip_bump(sc, packetlen);
+#endif
+	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_CodeMask;
+		count = *code_ptr & 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
+ * "dest", up to a  maximum of "dest_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 "dest_length" bytes:
+ *    UnStuffData returns NULL to indicate failure.
+ * 2. The source data produces exactly "dest_length" bytes:
+ *    UnStuffData returns new_src = end to indicate that all bytes
+ *    were consumed. 
+ * 3. "dest_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 destructive, 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 *dest, u_long dest_length)
+{
+	u_char *dest_end = dest + dest_length;
+
+	if (!src || !end || !dest || !dest_length)
+		return(NULL);	/* Sanity check */
+
+	while (src < end && dest < dest_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
+					*dest++ = *++src ^ Stuff_Magic;
+				while(--count >= 0 && dest < dest_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
+					*dest++ = *++src ^ Stuff_Magic;
+				while(--count >= 0 && dest < dest_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
+					*dest++ = src[1] ^ Stuff_Magic;
+				while(--count >= 0 && dest < dest_end);
+				if (count < 0)
+					src += 2;
+				else
+					*src = (Stuff_Same + count) ^ Stuff_Magic;
+				break;
+			case Stuff_Zero:
+				do
+					*dest++ = 0;
+				while(--count >= 0 && dest < dest_end);
+				if (count < 0)
+					src += 1;
+				else
+					*src = (Stuff_Zero + count) ^ Stuff_Magic;
+				break;
+			}
+	}
+
+	if (dest < dest_end)
+		return(NULL);
+	else
+		return(src);
+}
+
+
+
+/*
+ * Log an error mesesage (for a packet received with errors?)
+ * rom the STRIP driver.
+ * XXX check with original author.
+ */
+static void
+RecErr(msg, sc)
+	char *msg;
+	struct st_softc *sc;
+{
+	static const int MAX_RecErr = 80;
+	u_char *ptr = sc->sc_buf;
+	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("%13s : %s\n", msg, pkt_text);
+
+#ifdef linux
+	set_bit(SLF_ERROR, &sc->flags);
+	sc->rx_errors++;
+#endif /* linux */
+	sc->sc_if.if_ierrors++;
+}
+
+/*
+ * Log an error message for a packet recieved from a remote Metricom
+ * radio.  Update the radio-reset timer if the message is one that
+ * is generated only in starmode.
+ *
+ * We only call this function when we have an error message from
+ * the radio, which can only happen after seeing a frame delimeter
+ * in the input-side routine; so it's safe to call the output side
+ * to reset the radio.
+ */
+static void
+RecERR_Message(sc, sendername, msg)
+	struct st_softc *sc;
+	u_char *sendername;
+	u_char *msg;
+{
+	static const char ERR_001[] = "ERR_001 Not in StarMode!";
+	static const char ERR_002[] = "ERR_002 Remap handle";
+	static const char ERR_003[] = "ERR_003 Can't resolve name";
+	static const char ERR_004[] = "ERR_004 Name too small or missing";
+	static const char ERR_007[] = "ERR_007 Body too big";
+	static const char ERR_008[] = "ERR_008 Bad character in name";
+
+	if (!strncmp(msg, ERR_001, sizeof(ERR_001)-1)) {
+		printf("Radio %s is not in StarMode\n", sendername);
+	}
+	else if (!strncmp(msg, ERR_002, sizeof(ERR_002)-1)) {
+#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);
+		printf("Radio name %s is handle %d\n", newname, handle);
+#endif
+		}
+	else if (!strncmp(msg, ERR_003, sizeof(ERR_003)-1)) {
+		printf("Radio name <unspecified> is unknown (\"Can't resolve name\" error)\n");
+		}
+	else if (!strncmp(msg, ERR_004, sizeof(ERR_004)-1)) {
+		CLEAR_RESET_TIMER(sc);
+		/* printf("%s: Received tickle response; clearing watchdog_doreset timer.\n",
+			sc->sc_if.if_xname); */
+	}
+	else if (!strncmp(msg, ERR_007, sizeof(ERR_007)-1)) {
+		/* Note: This error knoks the radio back into command mode. */
+		printf("Error! Packet size <unspecified> is too big for radio.");
+		FORCE_RESET(sc);		/* Do reset ASAP */
+		}
+	else if (!strncmp(msg, ERR_008, sizeof(ERR_008)-1)) {
+		printf("Name <unspecified> contains illegal character\n");
+		}
+	else RecErr("Error Msg:", sc);
+}
+
+#ifdef DEBUG
+void
+stripdumpm(msg, m, len)
+     	const char *msg;
+	struct mbuf *m;
+{
+  stripdump(msg, mtod(m, u_char*), len);
+  /*XXX*/
+}
+
+void
+stripdump(msg, p, len)
+	const char *msg;
+	u_char *p;
+	int len;
+{
+	register int i;
+
+
+	printf(msg);
+	for (i = 0; i < STRIP_HDRLEN; i++)
+		printf("%c", p[i]);
+	printf("\n");
+
+	p += STRIP_HDRLEN;
+	for (i = 0; i < 32; i++) {
+	  	printf("%02x ", p[i]);
+	}
+		printf("\n");
+}
+
+void
+ipdump(msg, p, len)
+	const char *msg;
+	u_char *p;
+	int len;
+{
+	register int i;
+
+	printf(msg);
+	for (i = 0; i < 32; i++) {
+	  	printf("%02x ", p[i]);
+	}
+		printf("\n");
+}
+
+#endif /* DEBUG */
+#endif /* NSTRIP > 0 */