ppp.c

经典的ppp程序

	 * has dropped below the low-water mark.
	 */
	if (us->lowerq != 0)
	    qenable(RD(us->lowerq));
		
    } else {
	/*
	 * A network protocol stream.  Put a DLPI header on each
	 * packet and send it on.
	 * (Actually, it seems that the IP module will happily
	 * accept M_DATA messages without the DL_UNITDATA_IND header.)
	 */
	while ((mp = getq(q)) != 0) {
	    if (!canputnext(q)) {
		putbq(q, mp);
		break;
	    }
#ifndef NO_DLPI
	    proto = PPP_PROTOCOL(mp->b_rptr);
	    mp->b_rptr += PPP_HDRLEN;
	    hdr = allocb(sizeof(dl_unitdata_ind_t) + 2 * sizeof(uint),
			 BPRI_MED);
	    if (hdr == 0) {
		/* XXX should put it back and use bufcall */
		freemsg(mp);
		continue;
	    }
	    hdr->b_datap->db_type = M_PROTO;
	    ud = (dl_unitdata_ind_t *) hdr->b_wptr;
	    hdr->b_wptr += sizeof(dl_unitdata_ind_t) + 2 * sizeof(uint);
	    hdr->b_cont = mp;
	    ud->dl_primitive = DL_UNITDATA_IND;
	    ud->dl_dest_addr_length = sizeof(uint);
	    ud->dl_dest_addr_offset = sizeof(dl_unitdata_ind_t);
	    ud->dl_src_addr_length = sizeof(uint);
	    ud->dl_src_addr_offset = ud->dl_dest_addr_offset + sizeof(uint);
#if DL_CURRENT_VERSION >= 2
	    ud->dl_group_address = 0;
#endif
	    /* Send the DLPI client the data with the SAP they requested,
	       (e.g. ETHERTYPE_IP) rather than the PPP protocol number
	       (e.g. PPP_IP) */
	    ((uint *)(ud + 1))[0] = us->req_sap;	/* dest SAP */
	    ((uint *)(ud + 1))[1] = us->req_sap;	/* src SAP */
	    putnext(q, hdr);
#else /* NO_DLPI */
	    putnext(q, mp);
#endif /* NO_DLPI */
	}
	/*
	 * Now that we have consumed some packets from this queue,
	 * enable the control stream's read service routine so that we
	 * can process any packets for us that might have got queued
	 * there for flow control reasons.
	 */
	if (us->ppa)
	    qenable(us->ppa->q);
    }

    return 0;
}

static upperstr_t *
find_dest(ppa, proto)
    upperstr_t *ppa;
    int proto;
{
    upperstr_t *us;

    for (us = ppa->next; us != 0; us = us->next)
	if (proto == us->sap)
	    break;
    return us;
}

#if defined (SOL2)
/*
 * Test upstream promiscuous conditions. As of now, only pass IPv4 and
 * Ipv6 packets upstream (let PPP packets be decoded elsewhere).
 */
static upperstr_t *
find_promisc(us, proto)
    upperstr_t *us;
    int proto;
{

    if ((proto != PPP_IP) && (proto != PPP_IPV6))
	return (upperstr_t *)0;

    for ( ; us; us = us->next) {
	if ((us->flags & US_PROMISC) && (us->state == DL_IDLE))
	    return us;
    }

    return (upperstr_t *)0;
}

/*
 * Prepend an empty Ethernet header to msg for snoop, et al.
 */
static mblk_t *
prepend_ether(us, mp, proto)
    upperstr_t *us;
    mblk_t *mp;
    int proto;
{
    mblk_t *eh;
    int type;

    if ((eh = allocb(sizeof(struct ether_header), BPRI_HI)) == 0) {
	freemsg(mp);
	return (mblk_t *)0;
    }

    if (proto == PPP_IP)
	type = ETHERTYPE_IP;
    else if (proto == PPP_IPV6)
	type = ETHERTYPE_IPV6;
    else 
	type = proto;	    /* What else? Let decoder decide */

    eh->b_wptr += sizeof(struct ether_header);
    bzero((caddr_t)eh->b_rptr, sizeof(struct ether_header));
    ((struct ether_header *)eh->b_rptr)->ether_type = htons((short)type);
    eh->b_cont = mp;
    return (eh);
}

/*
 * Prepend DL_UNITDATA_IND mblk to msg
 */
static mblk_t *
prepend_udind(us, mp, proto)
    upperstr_t *us;
    mblk_t *mp;
    int proto;
{
    dl_unitdata_ind_t *dlu;
    mblk_t *dh;
    size_t size;

    size = sizeof(dl_unitdata_ind_t);
    if ((dh = allocb(size, BPRI_MED)) == 0) {
	freemsg(mp);
	return (mblk_t *)0;
    }

    dh->b_datap->db_type = M_PROTO;
    dh->b_wptr = dh->b_datap->db_lim;
    dh->b_rptr = dh->b_wptr - size;

    dlu = (dl_unitdata_ind_t *)dh->b_rptr;
    dlu->dl_primitive = DL_UNITDATA_IND;
    dlu->dl_dest_addr_length = 0;
    dlu->dl_dest_addr_offset = sizeof(dl_unitdata_ind_t);
    dlu->dl_src_addr_length = 0;
    dlu->dl_src_addr_offset = sizeof(dl_unitdata_ind_t);
    dlu->dl_group_address = 0;

    dh->b_cont = mp;
    return (dh);
}

/*
 * For any recognized promiscuous streams, send data upstream
 */
static void
promisc_sendup(ppa, mp, proto, skip)
    upperstr_t *ppa;
    mblk_t *mp;
    int proto, skip;
{
    mblk_t *dup_mp, *dup_dup_mp;
    upperstr_t *prus, *nprus;

    if ((prus = find_promisc(ppa, proto)) != 0) {
	if (dup_mp = dupmsg(mp)) {

	    if (skip)
		dup_mp->b_rptr += PPP_HDRLEN;

	    for ( ; nprus = find_promisc(prus->next, proto); 
		    prus = nprus) {

		if (dup_dup_mp = dupmsg(dup_mp)) {
		    if (canputnext(prus->q)) {
			if (prus->flags & US_RAWDATA) {
			    dup_dup_mp = prepend_ether(prus, dup_dup_mp, proto);
			    putnext(prus->q, dup_dup_mp);
			} else {
			    dup_dup_mp = prepend_udind(prus, dup_dup_mp, proto);
			    putnext(prus->q, dup_dup_mp);
			}
		    } else {
			DPRINT("ppp_urput: data to promisc q dropped\n");
			freemsg(dup_dup_mp);
		    }
		}
	    }

	    if (canputnext(prus->q)) {
		if (prus->flags & US_RAWDATA) {
		    dup_mp = prepend_ether(prus, dup_mp, proto);
		    putnext(prus->q, dup_mp);
		} else {
		    dup_mp = prepend_udind(prus, dup_mp, proto);
		    putnext(prus->q, dup_mp);
		}
	    } else {
		DPRINT("ppp_urput: data to promisc q dropped\n");
		freemsg(dup_mp);
	    }
	}
    }
}
#endif /* defined(SOL2) */

/*
 * We simply put the message on to the associated upper control stream
 * (either here or in ppplrsrv).  That way we enter the perimeters
 * before looking through the list of attached streams to decide which
 * stream it should go up.
 */
static int
ppplrput(q, mp)
    queue_t *q;
    mblk_t *mp;
{
    queue_t *uq;
    struct iocblk *iop;

    switch (mp->b_datap->db_type) {
    case M_IOCTL:
	iop = (struct iocblk *) mp->b_rptr;
	iop->ioc_error = EINVAL;
	mp->b_datap->db_type = M_IOCNAK;
	qreply(q, mp);
	return 0;
    case M_FLUSH:
	if (*mp->b_rptr & FLUSHR)
	    flushq(q, FLUSHDATA);
	if (*mp->b_rptr & FLUSHW) {
	    *mp->b_rptr &= ~FLUSHR;
	    qreply(q, mp);
	} else
	    freemsg(mp);
	return 0;
    }

    /*
     * If we can't get the lower lock straight away, queue this one
     * rather than blocking, to avoid the possibility of deadlock.
     */
    if (!TRYLOCK_LOWER_R) {
	putq(q, mp);
	return 0;
    }

    /*
     * Check that we're still connected to the driver.
     */
    uq = (queue_t *) q->q_ptr;
    if (uq == 0) {
	UNLOCK_LOWER;
	DPRINT1("ppplrput: q = %x, uq = 0??\n", q);
	freemsg(mp);
	return 0;
    }

    /*
     * Try to forward the message to the put routine for the upper
     * control stream for this lower stream.
     * If there are already messages queued here, queue this one so
     * they don't get out of order.
     */
    if (queclass(mp) == QPCTL || (qsize(q) == 0 && canput(uq)))
	put(uq, mp);
    else
	putq(q, mp);

    UNLOCK_LOWER;
    return 0;
}

static int
ppplrsrv(q)
    queue_t *q;
{
    mblk_t *mp;
    queue_t *uq;

    /*
     * Packets get queued here for flow control reasons
     * or if the lrput routine couldn't get the lower lock
     * without blocking.
     */
    LOCK_LOWER_R;
    uq = (queue_t *) q->q_ptr;
    if (uq == 0) {
	UNLOCK_LOWER;
	flushq(q, FLUSHALL);
	DPRINT1("ppplrsrv: q = %x, uq = 0??\n", q);
	return 0;
    }
    while ((mp = getq(q)) != 0) {
	if (queclass(mp) == QPCTL || canput(uq))
	    put(uq, mp);
	else {
	    putbq(q, mp);
	    break;
	}
    }
    UNLOCK_LOWER;
    return 0;
}

static int
putctl2(q, type, code, val)
    queue_t *q;
    int type, code, val;
{
    mblk_t *mp;

    mp = allocb(2, BPRI_HI);
    if (mp == 0)
	return 0;
    mp->b_datap->db_type = type;
    mp->b_wptr[0] = code;
    mp->b_wptr[1] = val;
    mp->b_wptr += 2;
    putnext(q, mp);
    return 1;
}

static int
putctl4(q, type, code, val)
    queue_t *q;
    int type, code, val;
{
    mblk_t *mp;

    mp = allocb(4, BPRI_HI);
    if (mp == 0)
	return 0;
    mp->b_datap->db_type = type;
    mp->b_wptr[0] = code;
    ((short *)mp->b_wptr)[1] = val;
    mp->b_wptr += 4;
    putnext(q, mp);
    return 1;
}

static void
debug_dump(q, mp)
    queue_t *q;
    mblk_t *mp;
{
    upperstr_t *us;
    queue_t *uq, *lq;

    DPRINT("ppp upper streams:\n");
    for (us = minor_devs; us != 0; us = us->nextmn) {
	uq = us->q;
	DPRINT3(" %d: q=%x rlev=%d",
		us->mn, uq, (uq? qsize(uq): 0));
	DPRINT3(" wlev=%d flags=0x%b", (uq? qsize(WR(uq)): 0),
		us->flags, "\020\1priv\2control\3blocked\4last");
	DPRINT3(" state=%x sap=%x req_sap=%x", us->state, us->sap,
		us->req_sap);
	if (us->ppa == 0)
	    DPRINT(" ppa=?\n");
	else
	    DPRINT1(" ppa=%d\n", us->ppa->ppa_id);
	if (us->flags & US_CONTROL) {
	    lq = us->lowerq;
	    DPRINT3("    control for %d lq=%x rlev=%d",
		    us->ppa_id, lq, (lq? qsize(RD(lq)): 0));
	    DPRINT3(" wlev=%d mru=%d mtu=%d\n",
		    (lq? qsize(lq): 0), us->mru, us->mtu);
	}
    }
    mp->b_datap->db_type = M_IOCACK;
    qreply(q, mp);
}

#ifdef FILTER_PACKETS
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>

#define MAX_IPHDR    128     /* max TCP/IP header size */


/* The following table contains a hard-coded list of protocol/port pairs.
 * Any matching packets are either discarded unconditionally, or, 
 * if ok_if_link_up is non-zero when a connection does not currently exist
 * (i.e., they go through if the connection is present, but never initiate
 * a dial-out).
 * This idea came from a post by [e-mail] (David Mazieres)
 */
static struct pktfilt_tab { 
	int proto; 
	u_short port; 
	u_short ok_if_link_up; 
} pktfilt_tab[] = {
	{ IPPROTO_UDP,	520,	1 },	/* RIP, ok to pass if link is up */
	{ IPPROTO_UDP,	123,	1 },	/* NTP, don't keep up the link for it */
	{ -1, 		0,	0 }	/* terminator entry has port == -1 */
};


static int
ip_hard_filter(us, mp, outbound)
    upperstr_t *us;
    mblk_t *mp;
    int outbound;
{
    struct ip *ip;
    struct pktfilt_tab *pft;
    mblk_t *temp_mp;
    int proto;
    int len, hlen;


    /* Note, the PPP header has already been pulled up in all cases */
    proto = PPP_PROTOCOL(mp->b_rptr);
    if (us->flags & US_DBGLOG)
        DPRINT3("ppp/%d: filter, proto=0x%x, out=%d\n", us->mn, proto, outbound);

    switch (proto)
    {
    case PPP_IP:
	if ((mp->b_wptr - mp->b_rptr) == PPP_HDRLEN && mp->b_cont != 0) {
	    temp_mp = mp->b_cont;
    	    len = msgdsize(temp_mp);
	    hlen = (len < MAX_IPHDR) ? len : MAX_IPHDR;
	    PULLUP(temp_mp, hlen);
	    if (temp_mp == 0) {
		DPRINT2("ppp/%d: filter, pullup next failed, len=%d\n", 
			us->mn, hlen);
		mp->b_cont = 0;		/* PULLUP() freed the rest */
	        freemsg(mp);
	        return 0;
	    }
	    ip = (struct ip *)mp->b_cont->b_rptr;
	}
	else {
	    len = msgdsize(mp);
	    hlen = (len < (PPP_HDRLEN+MAX_IPHDR)) ? len : (PPP_HDRLEN+MAX_IPHDR);
	    PULLUP(mp, hlen);
	    if (mp == 0) {
		DPRINT2("ppp/%d: filter, pullup failed, len=%d\n", 
			us->mn, hlen);
	        return 0;
	    }
	    ip = (struct ip *)(mp->b_rptr + PPP_HDRLEN);
	}

	/* For IP traffic, certain packets (e.g., RIP) may be either
	 *   1.  ignored - dropped completely
	 *   2.  will not initiate a connection, but
	 *       will be passed if a connection is currently up.
	 */
	for (pft=pktfilt_tab; pft->proto != -1; pft++) {
	    if (ip->ip_p == pft->proto) {
		switch(pft->proto) {
		case IPPROTO_UDP:
		    if (((struct udphdr *) &((int *)ip)[ip->ip_hl])->uh_dport
				== htons(pft->port)) goto endfor;
		    break;
		case IPPROTO_TCP:
		    if (((struct tcphdr *) &((int *)ip)[ip->ip_hl])->th_dport
				== htons(pft->port)) goto endfor;
		    break;
		}	
	    }
	}
	endfor:
	if (pft->proto != -1) {
	    if (us->flags & US_DBGLOG)
		DPRINT3("ppp/%d: found IP pkt, proto=0x%x (%d)\n", 
				us->mn, pft->proto, pft->port);
	    /* Discard if not connected, or if not pass_with_link_up */
	    /* else, if link is up let go by, but don't update time */
	    return pft->ok_if_link_up? -1: 0;
	}
        break;
    } /* end switch (proto) */

    return 1;
}
#endif /* FILTER_PACKETS */