if_sl.c

基于组件方式开发操作系统的OSKIT源代码

	register struct tty *tp;
{
	register struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
	register struct mbuf *m;
	register u_char *cp;
	register struct ip *ip;
	int s;
	struct mbuf *m2;
#if NBPFILTER > 0
	u_char bpfbuf[SLTMAX + SLIP_HDRLEN];
	register int len = 0;
#endif

	for (;;) {
		/*
		 * Call output process whether or not there is more in the
		 * output queue.  We are being called in lieu of ttstart
		 * and must do what it would.
		 */
		(*tp->t_oproc)(tp);

		if (tp->t_outq.c_cc != 0) {
			if (sc != NULL)
				sc->sc_flags &= ~SC_OUTWAIT;
			if (tp->t_outq.c_cc > SLIP_HIWAT)
				return 0;
		}

		/*
		 * This happens briefly when the line shuts down.
		 */
		if (sc == NULL)
			return 0;

		/*
		 * 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)
			return 0;

		/*
		 * We do the header compression here rather than in sloutput
		 * 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
			 * 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);
		}
#endif
		ip = mtod(m, struct ip *);
		if (ip->ip_v == IPVERSION && 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) {
			/*
			 * 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_if, bpfbuf, len + SLIP_HDRLEN);
		}
#endif

		/*
		 * If system is getting low on clists, just flush our
		 * output queue (if the stuff was important, it'll get
		 * retransmitted). Note that SLTMAX is used instead of
		 * the current if_mtu setting because connections that
		 * have already been established still use the original
		 * (possibly larger) mss.
		 */
		if (cfreecount < CLISTRESERVE + SLTMAX) {
			m_freem(m);
			sc->sc_if.if_collisions++;
			continue;
		}

		sc->sc_flags &= ~SC_OUTWAIT;
		/*
		 * The extra FRAME_END will start up a new packet, and thus
		 * will flush any accumulated garbage.  We do this whenever
		 * the line may have been idle for some time.
		 */
		if (tp->t_outq.c_cc == 0) {
			++sc->sc_if.if_obytes;
			(void) putc(FRAME_END, &tp->t_outq);
		}

		while (m) {
			register u_char *ep;

			cp = mtod(m, u_char *); ep = cp + m->m_len;
			while (cp < ep) {
				/*
				 * Find out how many bytes in the string we can
				 * handle without doing something special.
				 */
				register u_char *bp = cp;

				while (cp < ep) {
					switch (*cp++) {
					case FRAME_ESCAPE:
					case FRAME_END:
						--cp;
						goto out;
					}
				}
				out:
				if (cp > bp) {
					/*
					 * Put n characters at once
					 * into the tty output queue.
					 */
					if (b_to_q((char *)bp, cp - bp,
					    &tp->t_outq))
						break;
					sc->sc_if.if_obytes += cp - bp;
				}
				/*
				 * If there are characters left in the mbuf,
				 * the first one must be special..
				 * Put it out in a different form.
				 */
				if (cp < ep) {
					if (putc(FRAME_ESCAPE, &tp->t_outq))
						break;
					if (putc(*cp++ == FRAME_ESCAPE ?
					   TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
					   &tp->t_outq)) {
						(void) unputc(&tp->t_outq);
						break;
					}
					sc->sc_if.if_obytes += 2;
				}
			}
			MFREE(m, m2);
			m = m2;
		}

		if (putc(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(FRAME_END, &tp->t_outq);
			sc->sc_if.if_collisions++;
		} else {
			++sc->sc_if.if_obytes;
			sc->sc_if.if_opackets++;
		}
	}
	return 0;
}

/*
 * Copy data buffer to mbuf chain; add ifnet pointer.
 */
static struct mbuf *
sl_btom(sc, len)
	register struct sl_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)((intptr_t)sc->sc_buf &~ MCLOFSET);
	} 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.
 */
static int
slinput(c, tp)
	register int c;
	register struct tty *tp;
{
	register struct sl_softc *sc;
	register struct mbuf *m;
	register int len;
	int s;
#if NBPFILTER > 0
	u_char chdr[CHDR_LEN];
#endif

	tk_nin++;
	sc = (struct sl_softc *)tp->t_sc;
	if (sc == NULL)
		return 0;
	if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
		sc->sc_flags |= SC_ERROR;
		return 0;
	}
	c &= TTY_CHARMASK;

	++sc->sc_if.if_ibytes;

	if (sc->sc_if.if_flags & IFF_DEBUG) {
		if (c == ABT_ESC) {
			/*
			 * If we have a previous abort, see whether
			 * this one is within the time limit.
			 */
			if (sc->sc_abortcount &&
			    time_second >= sc->sc_starttime + ABT_WINDOW)
				sc->sc_abortcount = 0;
			/*
			 * If we see an abort after "idle" time, count it;
			 * record when the first abort escape arrived.
			 */
			if (time_second >= sc->sc_lasttime + ABT_IDLE) {
				if (++sc->sc_abortcount == 1)
					sc->sc_starttime = time_second;
				if (sc->sc_abortcount >= ABT_COUNT) {
					slclose(tp,0);
					return 0;
				}
			}
		} else
			sc->sc_abortcount = 0;
		sc->sc_lasttime = time_second;
	}

	switch (c) {

	case TRANS_FRAME_ESCAPE:
		if (sc->sc_escape)
			c = FRAME_ESCAPE;
		break;

	case TRANS_FRAME_END:
		if (sc->sc_escape)
			c = FRAME_END;
		break;

	case FRAME_ESCAPE:
		sc->sc_escape = 1;
		return 0;

	case FRAME_END:
		sc->sc_flags &= ~SC_KEEPALIVE;
		if(sc->sc_flags & SC_ERROR) {
			sc->sc_flags &= ~SC_ERROR;
			goto newpack;
		}
		len = sc->sc_mp - sc->sc_buf;
		if (len < 3)
			/* less than min length packet - ignore */
			goto newpack;

#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 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_if.if_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_if, hp, len + SLIP_HDRLEN);
		}
#endif
		m = sl_btom(sc, len);
		if (m == NULL)
			goto error;

		sc->sc_if.if_ipackets++;

		if ((sc->sc_if.if_flags & IFF_UP) == 0) {
			m_freem(m);
			goto newpack;
		}

		s = splimp();
		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);
		goto newpack;
	}
	if (sc->sc_mp < sc->sc_ep) {
		*sc->sc_mp++ = c;
		sc->sc_escape = 0;
		return 0;
	}

	/* can't put lower; would miss an extra frame */
	sc->sc_flags |= SC_ERROR;

error:
	sc->sc_if.if_ierrors++;
newpack:
	sc->sc_mp = sc->sc_buf = sc->sc_ep - SLRMAX;
	sc->sc_escape = 0;
	return 0;
}

/*
 * Process an ioctl request.
 */
static int
slioctl(ifp, cmd, data)
	register struct ifnet *ifp;
	u_long cmd;
	caddr_t data;
{
	register struct ifaddr *ifa = (struct ifaddr *)data;
	register struct ifreq *ifr = (struct ifreq *)data;
	register int s, error = 0;

	s = splimp();

	switch (cmd) {

	case SIOCSIFFLAGS:
		/*
		 * if.c will set the interface up even if we
		 * don't want it to.
		 */
		if (sl_softc[ifp->if_unit].sc_ttyp == NULL) {
			ifp->if_flags &= ~IFF_UP;
		}
		break;
	case SIOCSIFADDR:
		/*
		 * This is "historical" - set the interface up when
		 * setting the address.
		 */
		if (ifa->ifa_addr->sa_family == AF_INET) {
			if (sl_softc[ifp->if_unit].sc_ttyp != NULL)
				if_up(ifp);
		} else {
			error = EAFNOSUPPORT;
		}
		break;

	case SIOCSIFDSTADDR:
		if (ifa->ifa_addr->sa_family != AF_INET)
			error = EAFNOSUPPORT;
		break;

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		break;

	case SIOCSIFMTU:
		/*
		 * Set the interface MTU.
		 */
		if (ifr->ifr_mtu > SLTMAX)
			error = EINVAL;
		else {
			struct tty *tp;

			ifp->if_mtu = ifr->ifr_mtu;
			tp = sl_softc[ifp->if_unit].sc_ttyp;
			if (tp != NULL)
				clist_alloc_cblocks(&tp->t_outq,
				    SLIP_HIWAT + 2 * ifp->if_mtu + 1,
				    SLIP_HIWAT + 2 * ifp->if_mtu + 1);
		}
		break;

	default:
		error = EINVAL;
	}
	splx(s);
	return (error);
}

static void
sl_keepalive(chan)
	void *chan;
{
	struct sl_softc *sc = chan;

	if (sc->sc_keepalive) {
		if (sc->sc_flags & SC_KEEPALIVE)
			pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
		else
			sc->sc_flags |= SC_KEEPALIVE;
		sc->sc_kahandle = timeout(sl_keepalive, sc, sc->sc_keepalive);
	} else {
		sc->sc_flags &= ~SC_KEEPALIVE;
	}
}

static void
sl_outfill(chan)
	void *chan;
{
	struct sl_softc *sc = chan;
	register struct tty *tp = sc->sc_ttyp;
	int s;

	if (sc->sc_outfill && tp != NULL) {
		if (sc->sc_flags & SC_OUTWAIT) {
			s = splimp ();
			++sc->sc_if.if_obytes;
			(void) putc(FRAME_END, &tp->t_outq);
			(*tp->t_oproc)(tp);
			splx (s);
		} else
			sc->sc_flags |= SC_OUTWAIT;
		sc->sc_ofhandle = timeout(sl_outfill, sc, sc->sc_outfill);
	} else {
		sc->sc_flags &= ~SC_OUTWAIT;
	}
}

#endif