if_sl.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)if_sl.c	4.3		(ULTRIX)		2/1/91";
#endif lint
/*
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Based on -
 *	Van Jacobson ([e-mail]), Dec 31, 1989:
 *	- Initial distribution.
 *
 * As modified for Ultrix V4.0 by -
 *      Tim Theisen             Department of Computer Sciences
 *      [e-mail]         University of Wisconsin-Madison
 *      uwvax!tim               1210 West Dayton Street
 *      [phone]           Madison, WI   53706
 *
 * And finally the NSL version is by -
 *      Michael Reilly          Network Systems Lab
 *      [e-mail]      Digital Equipment corporation
 *                              505 Hamilton Avenue
 *                              Palo Alto, CA  94301
 *
 * For Ultrix V3.1 or V4.0 on a mips based DECstation
 *
 */

/*
 * NOTE:  You must define either ULTRIX_3 for an Ultrix V3.1 driver or
 *                               ULTRIX_4 for an Ultrix V4.0 driver
 */

/*
 * Serial Line interface
 *
 * Originally written by
 * 	Rick Adams
 * 	Center for Seismic Studies
 * 	1300 N 17th Street, Suite 1450
 * 	Arlington, Virginia 22209
 * 	[phone]
 * 	[e-mail]
 * 	seismo!rick
 *
 * Pounded on heavily by Chris Torek ([e-mail], 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.
 *
 * Hacked almost beyond recognition by Van Jacobson ([e-mail]).
 * 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); conditionals for Sun
 * OS 3.x in addition to 4.x BSD.  Made low clist behavior more robust
 * and slightly less likely to hang serial line.  Sped up a bunch of
 * things.
 */

/* originally from if_sl.c,v 1.11 84/10/04 12:54:47 rick Exp */
/* And from if_sl.c,v 1.12 90/08/20 14:24:28 tim Exp */

#define ULTRIX_4

#ifdef ultrix
#if !defined(ULTRIX_3) && !defined(ULTRIX_4)
#include "Either option ULTRIX_3 or ULTRIX_4 must be defined"
#endif
#endif

#include "sl.h"
#if NSL > 0

#if defined(ultrix) && defined(ULTRIX_3)
#include "../data/if_sl_data.c"
#endif

#if defined(ultrix) && defined(ULTRIX_4)
#include "../../data/if_sl_data.c"
#endif

#ifdef ultrix
#if defined(ULTRIX_3) && defined(ULTRIX_4)
#include "Error - both ULTRIX_3 and ULTRIX_4 are defined"
#endif
#endif

/*
 * The following are patchable defaults for the three options
 * in the interface flags word.  If desired, they should be set
 * by config file options SL_DOCOMPRESS, SL_ALLOWCOMPRESS and
 * SL_NOICMP.
 *
 *   sl_docompress	If = 1, compression for a line will default to "on"
 *
 *   sl_allowcompres	If = 1, compression for a line will default to "off"
 *			but will be turned on if a compressed packet is
 *			received. 
 *
 *   sl_noicmp		If = 1, outbound ICMP packets will be discarded.
 *			XXX - shouldn't have to set this but some cretin
 *			pinging us can drive our throughput to zero (not
 *			to mention the raft of quenches we'll get if we're
 *			unlucky enough to have to traverse the milnet.
 */
#ifndef SL_DOCOMPRESS
#define SL_DOCOMPRESS 0
#endif
#ifndef SL_ALLOWCOMPRESS
#define SL_ALLOWCOMPRESS 0
#endif
#ifndef SL_NOICMP
#define SL_NOICMP 0
#endif
int sl_docompress = SL_DOCOMPRESS;
int sl_allowcompress = SL_ALLOWCOMPRESS;
int sl_noicmp = SL_NOICMP;

/* Compatibility with 4.2 BSD (and variants) */
#ifndef MCLBYTES
#ifdef ultrix
#define MCLBYTES M_CLUSTERSZ
#else
#define MCLBYTES CLBYTES
#endif
#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, that there be enough extra room for the ifnet pointer that
 * IP input requires 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 - sizeof(struct ifnet *) - 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 **))
#define	SLMAX	(MCLBYTES - BUFOFFSET)
#define	SLMTU	296
#define	SLIP_HIWAT	roundup(50,CBSIZE)
#define	CLISTRESERVE	1024	/* Can't let clists get too low */

/*
 * The following disgusting hack gets around the problem that IP TOS
 * can't be set in BSD/Sun OS yet.  We want to put "interactive"
 * traffic on a high priority queue.  To decide if traffic is
 * interactive, we check that a) it is TCP and b) one of it's ports
 * if telnet, rlogin or ftp control.
 */
static u_short interactive_ports[8] = {
	0,	513,	0,	0,
	0,	21,	0,	23,
};
#define INTERACTIVE(p) (interactive_ports[(p) & 7] == (p))

#define FRAME_END		0xc0		/* Frame End */
#define FRAME_ESCAPE		0xdb		/* Frame Esc */
#define TRANS_FRAME_END		0xdc		/* transposed frame end */
#define TRANS_FRAME_ESCAPE	0xdd		/* transposed frame esc */

#ifdef sun
#define t_sc t_linep
#else
#define t_sc T_LINEP
#endif

#if defined(SL_NIT) && defined(NIT)
#include "../h/time.h"
#include "../net/nit.h"
#include "../netinet/if_ether.h"
extern struct nit_cb nitcb;
int sl_donit = 0;
#endif

/* Sun OS3.x doesn't have an MCLGET or MCLFREE.  Sun OS4.x doesn't
 * have an MCLFREE.  The code below should work on either Sun OS
 * (this driver, however will *NOT* work on a stock Sun OS4 system
 * because of the slow, broken, worthless, System-V "streams" tty
 * driver).
 *
 * All BSD systems since 4.1c have both MCLGET and MCLFREE.
 * However 4.2bsd had a second, unused parameter to MCLGET.  Some
 * versions of cpp may complain if you compile this routine under
 * a stock 4.2bsd.  For reasons I have never understood, various
 * vendors chose to break BSD in mysterious ways (e.g., DEC's Ultrix
 * changed the definition of m_off to make mbuf cluster use
 * a factor of two more costly -- no doubt this was done to encourage
 * the sale of faster processors since there is no technical
 * justification whatsoever for the change).  If you are stuck with
 * one of these abortions and, for reasons best known to yourself,
 * don't want to upgrade to the BSD network code freely available via
 * anonymous ftp from ucbarpa.berkeley.edu, the following macros
 * might give you a prototype to work from.  Then again, they might
 * not.  Good luck.
 */
#ifdef sun
#ifndef MCLGET
#define MCLGET(m) { int ms = splimp(); (void)mclget(m); (void) splx(ms); }
#endif
#ifndef MCLFREE
#define	MCLFREE(p) { \
	extern char *mclrefcnt; \
	struct mbuf mxxx; \
	mxxx.m_len = MCLBYTES; \
	mxxx.m_off = (int)p - (int)xm; \
	mxxx.m_cltype = 1; \
	mclput(&mxxx); \
	}
#endif
#endif

#ifdef ultrix
/* Ultrix 3.x on Vaxen misdefines the MCLGET macro to cause the m_len field
 * to be set to half of the amount actually allocated.  Thus this re-
 * definition is necessary.
 */

#if defined(vax) && defined(ULTRIX_3)
#undef MCLGET
#define MCLGET(m, p) \
        KM_ALLOC((p), struct mbuf *, M_CLUSTERSZ, KM_CLUSTER, KM_NOWAIT); \
        if((p)) { \
                (m)->m_cltype = M_CLTYPE1; (m)->m_clptr = (caddr_t) p; \
                m->m_off = (int)(p); m->m_len = M_CLUSTERSZ; \
                mbstat.m_clfree++; mbstat.m_clusters++; \
        }
#endif defined(vax) && defined(ULTRIX_3)

#ifndef MCLFREE
#define	MCLFREE(p) { \
	KM_FREE((p), KM_CLUSTER); \
	mbstat.m_clusters--; mbstat.m_clfree--; \
	}
#endif
#endif

int sloutput(), slioctl();

/*
 * Called from boot code to establish sl interfaces.
 */
slattach()
{
	register struct sl_softc *sc;
	register int i = 0;

#if defined(ultrix) && defined(ULTRIX_4)
	int s;
#endif

	if (sl_softc[0].sc_if.if_name == NULL) {
		for (sc = sl_softc; i < nNSL; sc++) {
			sc->sc_if.if_name = "sl";
			sc->sc_if.if_unit = i++;
			sc->sc_if.if_mtu = SLMTU;
			sc->sc_if.if_flags = IFF_POINTOPOINT;
			sc->sc_if.if_ioctl = slioctl;
			sc->sc_if.if_output = sloutput;
			sc->sc_if.if_snd.ifq_maxlen = 50;
			sc->sc_fastq.ifq_maxlen = 32;
#if defined(ultrix) && defined(ULTRIX_4)
			s = splnet();	/* SMP */
			if_attach(&sc->sc_if);
			splx(s);
#else
			if_attach(&sc->sc_if);
#endif
		}
	}
}

static int
slinit(sc)
	register struct sl_softc *sc;
{

	if (sc->sc_ep == (u_char *) 0) {
		struct mbuf m;

#ifdef ultrix
		struct mbuf *p;
		MCLGET((&m),p);
#else
		MCLGET((&m));
#endif
		if (m.m_len == MCLBYTES)
			sc->sc_ep = mtod(&m,u_char *) + (BUFOFFSET + SLMAX);
		else {
			printf("sl%d: can't allocate buffer\n", sc - sl_softc);
			sc->sc_if.if_flags &= ~IFF_UP;
			return (0);
		}
	}
	sc->sc_buf = sc->sc_ep - SLMAX;
	sc->sc_mp = sc->sc_buf;
	if (sl_docompress)
		sc->sc_if.if_flags |= IFF_D1;
	else 
		sc->sc_if.if_flags &=~ IFF_D1;
	if (sl_allowcompress)
		sc->sc_if.if_flags |= IFF_D2;
	else 
		sc->sc_if.if_flags &=~ IFF_D2;
	if (sl_noicmp)
		sc->sc_if.if_flags |= IFF_D3;
	else 
		sc->sc_if.if_flags &=~ IFF_D3;
	sl_compress_init(&sc->sc_comp);
	return (1);
}

/*
 * Line specific open routine.
 * Attach the given tty to the first available sl unit.
 */
/* ARGSUSED */
slopen(dev, tp)
	dev_t dev;
	register struct tty *tp;
{
	register struct sl_softc *sc;
	register int nsl;

	if (!suser())
		return (EPERM);

#ifdef ultrix
	slattach();
#define SLIPDISC SLPDISC
#endif

	if (tp->t_line == SLIPDISC)
		return (EBUSY);

	for (nsl = nNSL, sc = sl_softc; --nsl >= 0; sc++)
		if (sc->sc_ttyp == NULL) {
			if (slinit(sc) == 0)
				return (ENOBUFS);
			tp->t_sc = (caddr_t)sc;
			sc->sc_ttyp = tp;
			ttyflush(tp, FREAD | FWRITE);
			return (0);
		}
	return (ENXIO);
}

#ifdef sun
/* XXX - Sun OS3 is missing these 4bsd routines.
 *
 * Mark an interface down and notify protocols of
 * the transition.
 */
static void
if_down(ifp)
	register struct ifnet *ifp;
{
	register struct ifqueue *ifq = &ifp->if_snd;
	register struct mbuf *m, *n;

	ifp->if_flags &=~ IFF_UP;
	pfctlinput(PRC_IFDOWN, &ifp->if_addr);

	/* Flush the interface queue. */
	n = ifq->ifq_head;
	while (m = n) {
		n = m->m_act;
		m_freem(m);
	}
	ifq->ifq_head = 0;
	ifq->ifq_tail = 0;
	ifq->ifq_len = 0;
}

static void
if_rtdelete(ifp)
	register struct ifnet *ifp;
{
	static struct rtentry route;

	if (ifp->if_flags & IFF_ROUTE) {
		route.rt_dst = ifp->if_dstaddr;
		route.rt_gateway = ifp->if_addr;
		route.rt_flags = RTF_HOST|RTF_UP;
		(void) rtrequest(SIOCDELRT, &route);
		ifp->if_flags &=~ IFF_ROUTE;
	}
}
#endif

/*
 * Line specific close routine.
 * Detach the tty from the sl unit.
 * Mimics part of ttyclose().
 */
slclose(tp)
	struct tty *tp;
{
	register struct sl_softc *sc;
	int s;

	ttywflush(tp);
	tp->t_line = 0;
	s = splimp();
	sc = (struct sl_softc *)tp->t_sc;
	if (sc != NULL) {

#ifdef sun
		if_rtdelete(&sc->sc_if);
#endif

		if_down(&sc->sc_if);
		rtpurge(&sc->sc_if);
		in_reminterface(&sc->sc_if);
		sc->sc_if.if_addrlist = NULL;
		sc->sc_ttyp = NULL;
		tp->t_sc = NULL;
		MCLFREE((struct mbuf *)(sc->sc_ep - (SLMAX + BUFOFFSET)));
		sc->sc_ep = 0;
		sc->sc_mp = 0;
		sc->sc_buf = 0;
	}
	splx(s);
}

/*
 * Line specific (tty) ioctl routine.
 * Provide a way to get the sl unit number.
 */
/* ARGSUSED */
sltioctl(tp, cmd, data, flag)
	struct tty *tp;
	caddr_t data;
{

	if (cmd == TIOCGETD) {
		*(int *)data = ((struct sl_softc *)tp->t_sc)->sc_if.if_unit;
		return (0);
	}
	return (EINVAL);
}

/*
 * Queue a packet.  Start transmission if not active.
 */
sloutput(ifp, m, dst)
	register struct ifnet *ifp;
	register struct mbuf *m;
	struct sockaddr *dst;
{
	register struct sl_softc *sc;
	register struct ip *ip;
	register struct ifqueue *ifq;
	int s;

	/*
	 * `Cannot happen' (see slioctl).  Someday we will extend
	 * the line protocol to support other address families.
	 */
	if (dst->sa_family != AF_INET) {
		printf("sl%d: af%d not supported\n", ifp->if_unit,
			dst->sa_family);
		m_freem(m);
		return (EAFNOSUPPORT);