if_ppp.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

    /*
     * Grab a packet to send: first try the fast queue, then the
     * normal queue.
     */
    rtems_bsdnet_semaphore_obtain();
    IF_DEQUEUE(&sc->sc_fastq, m);
    if (m == NULL)
	IF_DEQUEUE(&sc->sc_if.if_snd, m);
    rtems_bsdnet_semaphore_release();

    if (m == NULL)
	return NULL;

    ++sc->sc_stats.ppp_opackets;

    /*
     * Extract the ppp header of the new packet.
     * The ppp header will be in one mbuf.
     */
    cp = mtod(m, u_char *);
    address = PPP_ADDRESS(cp);
    control = PPP_CONTROL(cp);
    protocol = PPP_PROTOCOL(cp);

    switch (protocol) {
    case PPP_IP:
#ifdef VJC
	/*
	 * If the packet is a TCP/IP packet, see if we can compress it.
	 */
	if ((sc->sc_flags & SC_COMP_TCP) && sc->sc_comp != NULL) {
	    struct ip *ip;
	    int type;

	    mp = m;
	    ip = (struct ip *) (cp + PPP_HDRLEN);
	    if (mp->m_len <= PPP_HDRLEN) {
		mp = mp->m_next;
		if (mp == NULL)
		    break;
		ip = mtod(mp, struct ip *);
	    }
	    /* this code assumes the IP/TCP header is in one non-shared mbuf */
	    if (ip->ip_p == IPPROTO_TCP) {
		type = vj_compress_tcp(mp, ip, sc->sc_comp,
				       !(sc->sc_flags & SC_NO_TCP_CCID));
		switch (type) {
		case TYPE_UNCOMPRESSED_TCP:
		    protocol = PPP_VJC_UNCOMP;
		    break;
		case TYPE_COMPRESSED_TCP:
		    protocol = PPP_VJC_COMP;
		    cp = mtod(m, u_char *);
		    cp[0] = address;	/* header has moved */
		    cp[1] = control;
		    cp[2] = 0;
		    break;
		}
		cp[3] = protocol;	/* update protocol in PPP header */
	    }
	}
#endif	/* VJC */
	break;

#ifdef PPP_COMPRESS
    case PPP_CCP:
	ppp_ccp(sc, m, 0);
	break;
#endif	/* PPP_COMPRESS */
    }

#ifdef PPP_COMPRESS
    if (protocol != PPP_LCP && protocol != PPP_CCP
	&& sc->sc_xc_state && (sc->sc_flags & SC_COMP_RUN)) {
	struct mbuf *mcomp = NULL;
	int slen, clen;

	slen = 0;
	for (mp = m; mp != NULL; mp = mp->m_next)
	    slen += mp->m_len;
	clen = (*sc->sc_xcomp->compress)
	    (sc->sc_xc_state, &mcomp, m, slen, sc->sc_if.if_mtu + PPP_HDRLEN);
	if (mcomp != NULL) {
	    if (sc->sc_flags & SC_CCP_UP) {
		/* Send the compressed packet instead of the original. */
		m_freem(m);
		m = mcomp;
		cp = mtod(m, u_char *);
		protocol = cp[3];
	    } else {
		/* Can't transmit compressed packets until CCP is up. */
		m_freem(mcomp);
	    }
	}
    }
#endif	/* PPP_COMPRESS */

    /*
     * Compress the address/control and protocol, if possible.
     */
    if (sc->sc_flags & SC_COMP_AC && address == PPP_ALLSTATIONS &&
	control == PPP_UI && protocol != PPP_ALLSTATIONS &&
	protocol != PPP_LCP) {
	/* can compress address/control */
	m->m_data += 2;
	m->m_len -= 2;
    }
    if (sc->sc_flags & SC_COMP_PROT && protocol < 0xFF) {
	/* can compress protocol */
	if (mtod(m, u_char *) == cp) {
	    cp[2] = cp[1];	/* move address/control up */
	    cp[1] = cp[0];
	}
	++m->m_data;
	--m->m_len;
    }

    return m;
}

/*
 * Software interrupt routine, called at splsoftnet.
 */
void
pppintr(void)
{
}

#ifdef PPP_COMPRESS
/*
 * Handle a CCP packet.  `rcvd' is 1 if the packet was received,
 * 0 if it is about to be transmitted.
 */
static void
ppp_ccp(sc, m, rcvd)
    struct ppp_softc *sc;
    struct mbuf *m;
    int rcvd;
{
    u_char *dp, *ep;
    struct mbuf *mp;
    int slen, s;

    /*
     * Get a pointer to the data after the PPP header.
     */
    if (m->m_len <= PPP_HDRLEN) {
	mp = m->m_next;
	if (mp == NULL)
	    return;
	dp = (mp != NULL)? mtod(mp, u_char *): NULL;
    } else {
	mp = m;
	dp = mtod(mp, u_char *) + PPP_HDRLEN;
    }

    ep = mtod(mp, u_char *) + mp->m_len;
    if (dp + CCP_HDRLEN > ep)
	return;
    slen = CCP_LENGTH(dp);
    if (dp + slen > ep) {
	if (sc->sc_flags & SC_DEBUG)
	    printf("if_ppp/ccp: not enough data in mbuf (%p+%x > %p+%x)\n",
		   dp, slen, mtod(mp, u_char *), mp->m_len);
	return;
    }

    switch (CCP_CODE(dp)) {
    case CCP_CONFREQ:
    case CCP_TERMREQ:
    case CCP_TERMACK:
	/* CCP must be going down - disable compression */
	if (sc->sc_flags & SC_CCP_UP) {
	    s = splimp();
	    sc->sc_flags &= ~(SC_CCP_UP | SC_COMP_RUN | SC_DECOMP_RUN);
	    splx(s);
	}
	break;

    case CCP_CONFACK:
	if (sc->sc_flags & SC_CCP_OPEN && !(sc->sc_flags & SC_CCP_UP)
	    && slen >= CCP_HDRLEN + CCP_OPT_MINLEN
	    && slen >= CCP_OPT_LENGTH(dp + CCP_HDRLEN) + CCP_HDRLEN) {
	    if (!rcvd) {
		/* we're agreeing to send compressed packets. */
		if (sc->sc_xc_state != NULL
		    && (*sc->sc_xcomp->comp_init)
			(sc->sc_xc_state, dp + CCP_HDRLEN, slen - CCP_HDRLEN,
			 sc->sc_if.if_unit, 0, sc->sc_flags & SC_DEBUG)) {
		    s = splimp();
		    sc->sc_flags |= SC_COMP_RUN;
		    splx(s);
		}
	    } else {
		/* peer is agreeing to send compressed packets. */
		if (sc->sc_rc_state != NULL
		    && (*sc->sc_rcomp->decomp_init)
			(sc->sc_rc_state, dp + CCP_HDRLEN, slen - CCP_HDRLEN,
			 sc->sc_if.if_unit, 0, sc->sc_mru,
			 sc->sc_flags & SC_DEBUG)) {
		    s = splimp();
		    sc->sc_flags |= SC_DECOMP_RUN;
		    sc->sc_flags &= ~(SC_DC_ERROR | SC_DC_FERROR);
		    splx(s);
		}
	    }
	}
	break;

    case CCP_RESETACK:
	if (sc->sc_flags & SC_CCP_UP) {
	    if (!rcvd) {
		if (sc->sc_xc_state && (sc->sc_flags & SC_COMP_RUN))
		    (*sc->sc_xcomp->comp_reset)(sc->sc_xc_state);
	    } else {
		if (sc->sc_rc_state && (sc->sc_flags & SC_DECOMP_RUN)) {
		    (*sc->sc_rcomp->decomp_reset)(sc->sc_rc_state);
		    s = splimp();
		    sc->sc_flags &= ~SC_DC_ERROR;
		    splx(s);
		}
	    }
	}
	break;
    }
}

/*
 * CCP is down; free (de)compressor state if necessary.
 */
static void
ppp_ccp_closed(sc)
    struct ppp_softc *sc;
{
    if (sc->sc_xc_state) {
	(*sc->sc_xcomp->comp_free)(sc->sc_xc_state);
	sc->sc_xc_state = NULL;
    }
    if (sc->sc_rc_state) {
	(*sc->sc_rcomp->decomp_free)(sc->sc_rc_state);
	sc->sc_rc_state = NULL;
    }
}
#endif /* PPP_COMPRESS */

/*
 * Process a received PPP packet, doing decompression as necessary.
 * Should be called at splsoftnet.
 */
#define COMPTYPE(proto)	((proto) == PPP_VJC_COMP? TYPE_COMPRESSED_TCP: \
			 TYPE_UNCOMPRESSED_TCP)

static struct mbuf *
ppp_inproc(sc, m)
    struct ppp_softc *sc;
    struct mbuf *m;
{
    struct mbuf  *mf = (struct mbuf *)0;
    struct ifnet *ifp = &sc->sc_if;
    struct ifqueue *inq;
    int s, ilen, proto, rv; 
    u_char *cp, adrs, ctrl;
    struct mbuf *mp;
#ifdef PPP_COMPRESS
    struct mbuf *dmp = NULL;
#endif
#ifdef VJC
    u_char *iphdr;
    u_int hlen; 
    int xlen;
#endif

    sc->sc_stats.ppp_ipackets++;

    if (sc->sc_flags & SC_LOG_INPKT) {
	ilen = 0;
	for (mp = m; mp != NULL; mp = mp->m_next)
	    ilen += mp->m_len;
	printf("ppp%d: got %d bytes\n", ifp->if_unit, ilen);
	pppdumpm(m);
    }

    cp = mtod(m, u_char *);
    adrs = PPP_ADDRESS(cp);
    ctrl = PPP_CONTROL(cp);
    proto = PPP_PROTOCOL(cp);

    if (m->m_flags & M_ERRMARK) {
	m->m_flags &= ~M_ERRMARK;
	s = splimp();
	sc->sc_flags |= SC_VJ_RESET;
	splx(s);
    }

#ifdef PPP_COMPRESS
    /*
     * Decompress this packet if necessary, update the receiver's
     * dictionary, or take appropriate action on a CCP packet.
     */
    if (proto == PPP_COMP && sc->sc_rc_state && (sc->sc_flags & SC_DECOMP_RUN)
	&& !(sc->sc_flags & SC_DC_ERROR) && !(sc->sc_flags & SC_DC_FERROR)) {
	/* decompress this packet */
	rv = (*sc->sc_rcomp->decompress)(sc->sc_rc_state, m, &dmp);
	if (rv == DECOMP_OK) {
	    m_freem(m);
	    if (dmp == NULL) {
		/* no error, but no decompressed packet produced */
		return mf;
	    }
	    m = dmp;
	    cp = mtod(m, u_char *);
	    proto = PPP_PROTOCOL(cp);

	} else {
	    /*
	     * An error has occurred in decompression.
	     * Pass the compressed packet up to pppd, which may take
	     * CCP down or issue a Reset-Req.
	     */
	    if (sc->sc_flags & SC_DEBUG)
		printf("ppp%d: decompress failed %d\n", ifp->if_unit, rv);
	    s = splimp();
	    sc->sc_flags |= SC_VJ_RESET;
	    if (rv == DECOMP_ERROR)
		sc->sc_flags |= SC_DC_ERROR;
	    else
		sc->sc_flags |= SC_DC_FERROR;
	    splx(s);
	}

    } else {
	if (sc->sc_rc_state && (sc->sc_flags & SC_DECOMP_RUN)) {
	    (*sc->sc_rcomp->incomp)(sc->sc_rc_state, m);
	}
	if (proto == PPP_CCP) {
	    ppp_ccp(sc, m, 1);
	}
    }
#endif

    ilen = 0;
    for (mp = m; mp != NULL; mp = mp->m_next)
	ilen += mp->m_len;

#ifdef VJC
    if (sc->sc_flags & SC_VJ_RESET) {
	/*
	 * If we've missed a packet, we must toss subsequent compressed
	 * packets which don't have an explicit connection ID.
	 */
	if (sc->sc_comp)
	    vj_uncompress_tcp(NULL, 0, TYPE_ERROR, sc->sc_comp);
	s = splimp();
	sc->sc_flags &= ~SC_VJ_RESET;
	splx(s);
    }

    /*
     * See if we have a VJ-compressed packet to uncompress.
     */
    if (proto == PPP_VJC_COMP) {
	if ((sc->sc_flags & SC_REJ_COMP_TCP) || sc->sc_comp == 0)
	    goto bad;

	xlen = vj_uncompress_tcp_core(cp + PPP_HDRLEN, m->m_len - PPP_HDRLEN,
				      ilen - PPP_HDRLEN, TYPE_COMPRESSED_TCP,
				      sc->sc_comp, &iphdr, &hlen);

	if (xlen <= 0) {
	    if (sc->sc_flags & SC_DEBUG)
		printf("ppp%d: VJ uncompress failed on type comp\n",
			ifp->if_unit);
	    goto bad;
	}

	/* Copy the PPP and IP headers into a new mbuf. */
	MGETHDR(mp, M_DONTWAIT, MT_DATA);
	if (mp == NULL)
	    goto bad;
	mp->m_len = 0;
	mp->m_next = NULL;
	if (hlen + PPP_HDRLEN > MHLEN) {
	    MCLGET(mp, M_DONTWAIT);
	    if (M_TRAILINGSPACE(mp) < hlen + PPP_HDRLEN) {
		m_freem(mp);
		goto bad;	/* lose if big headers and no clusters */
	    }
	}
	cp = mtod(mp, u_char *);
	cp[0] = adrs;
	cp[1] = ctrl;
	cp[2] = 0;
	cp[3] = PPP_IP;
	proto = PPP_IP;
	bcopy(iphdr, cp + PPP_HDRLEN, hlen);
	mp->m_len = hlen + PPP_HDRLEN;

	/*
	 * Trim the PPP and VJ headers off the old mbuf
	 * and stick the new and old mbufs together.
	 */
	m->m_data += PPP_HDRLEN + xlen;
	m->m_len -= PPP_HDRLEN + xlen;
	if (m->m_len <= M_TRAILINGSPACE(mp)) {
	    bcopy(mtod(m, u_char *), mtod(mp, u_char *) + mp->m_len, m->m_len);
	    mp->m_len += m->m_len;
	    MFREE(m, mp->m_next);
	} else
	    mp->m_next = m;
	m = mp;
	ilen += hlen - xlen;

    } else if (proto == PPP_VJC_UNCOMP) {
	if ((sc->sc_flags & SC_REJ_COMP_TCP) || sc->sc_comp == 0)
	    goto bad;

	xlen = vj_uncompress_tcp_core(cp + PPP_HDRLEN, m->m_len - PPP_HDRLEN,
				      ilen - PPP_HDRLEN, TYPE_UNCOMPRESSED_TCP,
				      sc->sc_comp, &iphdr, &hlen);

	if (xlen < 0) {
	    if (sc->sc_flags & SC_DEBUG)
		printf("ppp%d: VJ uncompress failed on type uncomp\n",
			ifp->if_unit);
	    goto bad;
	}

	proto = PPP_IP;
	cp[3] = PPP_IP;
    }
#endif /* VJC */

    /*
     * If the packet will fit in a header mbuf, don't waste a
     * whole cluster on it.
     */
    if (ilen <= MHLEN && M_IS_CLUSTER(m)) {
	MGETHDR(mp, M_DONTWAIT, MT_DATA);
	if (mp != NULL) {
	    m_copydata(m, 0, ilen, mtod(mp, caddr_t));
            /* instead of freeing - return cluster mbuf so it can be reused */
            /* m_freem(m); */
            mf = m;
	    m = mp;
	    m->m_len = ilen;
	}
    }
    m->m_pkthdr.len = ilen;
    m->m_pkthdr.rcvif = ifp;

    if ((proto & 0x8000) == 0) {
#ifdef PPP_FILTER
	/*
	 * See whether we want to pass this packet, and
	 * if it counts as link activity.
	 */
	adrs = *mtod(m, u_char *);	/* save address field */
	*mtod(m, u_char *) = 0;		/* indicate inbound */
	if (sc->sc_pass_filt.bf_insns != 0
	    && bpf_filter(sc->sc_pass_filt.bf_insns, (u_char *) m,
			  ilen, 0) == 0) {
	    /* drop this packet */
	    m_freem(m);
	    return mf;
	}
	if (sc->sc_active_filt.bf_insns == 0
	    || bpf_filter(sc->sc_active_filt.bf_insns, (u_char *) m, ilen, 0))
	    sc->sc_last_recv = time.tv_sec;

	*mtod(m, u_char *) = adrs;
#else
	/*
	 * Record the time that we received this packet.
	 */
	microtime(&ppp_time);
	sc->sc_last_recv = ppp_time.tv_sec;
#endif /* PPP_FILTER */
    }

#if NBPFILTER > 0
    /* See if bpf wants to look at the packet. */
    if (sc->sc_bpf)
	bpf_mtap(sc->sc_bpf, m);
#endif

    rv = 0;
    switch (proto) {
#ifdef INET
    case PPP_IP:
	/*
	 * IP packet - take off the ppp header and pass it up to IP.
	 */
	if ((ifp->if_flags & IFF_UP) == 0
	    || sc->sc_npmode[NP_IP] != NPMODE_PASS) {
	    /* interface is down - drop the packet. */
	    m_freem(m);
	    return mf;
	}
	m->m_pkthdr.len -= PPP_HDRLEN;
	m->m_data += PPP_HDRLEN;
	m->m_len -= PPP_HDRLEN;
	schednetisr(NETISR_IP);
	inq = &ipintrq;
	break;
#endif

    default:
	/*
	 * Some other protocol - place on input queue for read().
	 */
	inq = &sc->sc_inq;
	rv = 1;
	break;
    }

    /*
     * Put the packet on the appropriate input queue.
     */
    s = splimp();
    if (IF_QFULL(inq)) {
	IF_DROP(inq);
	splx(s);
	if (sc->sc_flags & SC_DEBUG)
	    printf("ppp%d: input queue full\n", ifp->if_unit);
	ifp->if_iqdrops++;
	goto bad;
    }
    IF_ENQUEUE(inq, m);
    splx(s);

    ifp->if_ipackets++;
    ifp->if_ibytes += ilen;
    microtime(&ppp_time);
    ifp->if_lastchange = ppp_time;

    if (rv) {
      (*sc->sc_ctlp)(sc);
    }

    return mf;

 bad:
    m_freem(m);
    sc->sc_if.if_ierrors++;
    sc->sc_stats.ppp_ierrors++;
    return mf;
}

#define MAX_DUMP_BYTES	128

static void
pppdumpm(m0)
    struct mbuf *m0;
{
    char buf[3*MAX_DUMP_BYTES+4];
    char *bp = buf;
    struct mbuf *m;
    static char digits[] = "0123456789abcdef";

    for (m = m0; m; m = m->m_next) {
	int l = m->m_len;
	u_char *rptr = (u_char *)m->m_data;

	while (l--) {
	    if (bp > buf + sizeof(buf) - 4)
		goto done;
	    *bp++ = digits[*rptr >> 4]; /* convert byte to ascii hex */
	    *bp++ = digits[*rptr++ & 0xf];
	}

	if (m->m_next) {
	    if (bp > buf + sizeof(buf) - 3)
		goto done;
	    *bp++ = '|';
	} else
	    *bp++ = ' ';
    }
done:
    if (m)
	*bp++ = '>';
    *bp = 0;
    printf("%s\n", buf);
}

#endif	/* NPPP > 0 */