if_bridge.c

来自「嵌入式操作系统ECOS的网络开发包」· C语言 代码 · 共 2,021 行 · 第 1/4 页

	/*
	 * Multicast packets get handled a little differently:
	 * If interface is:
	 *	-link0,-link1	(default) Forward all multicast
	 *			as broadcast.
	 *	-link0,link1	Drop non-IP multicast, forward
	 *			as broadcast IP multicast.
	 *	link0,-link1	Drop IP multicast, forward as
	 *			broadcast non-IP multicast.
	 *	link0,link1	Drop all multicast.
	 */
	if (m->m_flags & M_MCAST) {
		if ((sc->sc_if.if_flags &
		    (IFF_LINK0 | IFF_LINK1)) ==
		    (IFF_LINK0 | IFF_LINK1)) {
			m_freem(m);
			return;
		}
		if (sc->sc_if.if_flags & IFF_LINK0 &&
		    ETHERADDR_IS_IP_MCAST(dst)) {
			m_freem(m);
			return;
		}
		if (sc->sc_if.if_flags & IFF_LINK1 &&
		    !ETHERADDR_IS_IP_MCAST(dst)) {
			m_freem(m);
			return;
		}
	}

	if (ifl->bif_flags & IFBIF_BLOCKNONIP && bridge_blocknonip(&eh, m)) {
		m_freem(m);
		return;
	}

	if (SIMPLEQ_FIRST(&ifl->bif_brlin) &&
	    bridge_filterrule(SIMPLEQ_FIRST(&ifl->bif_brlin), &eh) ==
	    BRL_ACTION_BLOCK) {
		m_freem(m);
		return;
	}

#if defined(INET) && (defined(IPFILTER) || defined(IPFILTER_LKM))
	m = bridge_filter(sc, src_if, &eh, m);
	if (m == NULL)
		return;
#endif

	/*
	 * If the packet is a multicast or broadcast OR if we don't
	 * know any better, forward it to all interfaces.
	 */
	if ((m->m_flags & (M_BCAST | M_MCAST)) || dst_if == NULL) {
		sc->sc_if.if_imcasts++;
		s = splimp();
		bridge_broadcast(sc, src_if, &eh, m);
		splx(s);
		return;
	}

	/*
	 * At this point, we're dealing with a unicast frame going to a
	 * different interface
	 */
	if ((dst_if->if_flags & IFF_RUNNING) == 0) {
		m_freem(m);
		return;
	}
	ifl = LIST_FIRST(&sc->sc_iflist);
	while (ifl != NULL && ifl->ifp != dst_if)
		ifl = LIST_NEXT(ifl, next);
	if (SIMPLEQ_FIRST(&ifl->bif_brlout) &&
	    bridge_filterrule(SIMPLEQ_FIRST(&ifl->bif_brlout), &eh) ==
	    BRL_ACTION_BLOCK) {
		m_freem(m);
		return;
	}
	s = splimp();
	if (IF_QFULL(&dst_if->if_snd)) {
		sc->sc_if.if_oerrors++;
		m_freem(m);
		splx(s);
		return;
	}
	sc->sc_if.if_opackets++;
	sc->sc_if.if_obytes += m->m_pkthdr.len;
        // Also count the bytes in the outgoing interface; normally
        // done in if_ethersubr.c but here we bypass that route.
        dst_if->if_obytes += m->m_pkthdr.len;
	IF_ENQUEUE(&dst_if->if_snd, m);
	if ((dst_if->if_flags & IFF_OACTIVE) == 0)
		(*dst_if->if_start)(dst_if);
	splx(s);
}

/*
 * Receive input from an interface.  Queue the packet for bridging if its
 * not for us, and schedule an interrupt.
 */
struct mbuf *
bridge_input(ifp, eh, m)
	struct ifnet *ifp;
	struct ether_header *eh;
	struct mbuf *m;
{
	struct bridge_softc *sc;
	int s;
	struct bridge_iflist *ifl;
	struct arpcom *ac;
	struct mbuf *mc;

	/*
	 * Make sure this interface is a bridge member.
	 */
	if (ifp == NULL || ifp->if_bridge == NULL || m == NULL)
		return (m);

	if ((m->m_flags & M_PKTHDR) == 0)
		panic("bridge_input(): no HDR");

	sc = (struct bridge_softc *)ifp->if_bridge;
	if ((sc->sc_if.if_flags & IFF_RUNNING) == 0)
		return (m);

	if (m->m_flags & (M_BCAST | M_MCAST)) {
		/*
		 * make a copy of 'm' with 'eh' tacked on to the
		 * beginning.  Return 'm' for local processing
		 * and enqueue the copy.  Schedule netisr.
		 */
		mc = m_copym2(m, 0, M_COPYALL, M_NOWAIT);
		if (mc == NULL)
			return (m);
		M_PREPEND(mc, sizeof(struct ether_header), M_DONTWAIT);
		if (mc == NULL)
			return (m);
		bcopy(eh, mtod(mc, caddr_t), sizeof(struct ether_header));
		s = splimp();
		if (IF_QFULL(&sc->sc_if.if_snd)) {
			m_freem(mc);
			splx(s);
			return (m);
		}
		IF_ENQUEUE(&sc->sc_if.if_snd, mc);
		splx(s);
		schednetisr(NETISR_BRIDGE);
		return (m);
	}

	/*
	 * Unicast, make sure it's not for us.
	 */
	for (ifl = LIST_FIRST(&sc->sc_iflist);ifl; ifl = LIST_NEXT(ifl,next)) {
		if (ifl->ifp->if_type != IFT_ETHER)
			continue;
		ac = (struct arpcom *)ifl->ifp;
		if (bcmp(ac->ac_enaddr, eh->ether_dhost, ETHER_ADDR_LEN) == 0) {
			if (ifl->bif_flags & IFBIF_LEARNING)
				bridge_rtupdate(sc,
				    (struct ether_addr *)&eh->ether_shost,
				    ifp, 0, IFBAF_DYNAMIC);
			m->m_pkthdr.rcvif = ifl->ifp;
			return (m);
		}
		if (bcmp(ac->ac_enaddr, eh->ether_shost, ETHER_ADDR_LEN) == 0) {
			m_freem(m);
			return (NULL);
		}
	}
	M_PREPEND(m, sizeof(struct ether_header), M_DONTWAIT);
	if (m == NULL)
		return (NULL);
	bcopy(eh, mtod(m, caddr_t), sizeof(struct ether_header));
	s = splimp();
	if (IF_QFULL(&sc->sc_if.if_snd)) {
		m_freem(m);
		splx(s);
		return (NULL);
	}
	IF_ENQUEUE(&sc->sc_if.if_snd, m);
	splx(s);
	schednetisr(NETISR_BRIDGE);
	return (NULL);
}

/*
 * Send a frame to all interfaces that are members of the bridge
 * (except the one it came in on).  This code assumes that it is
 * running at splnet or higher.
 */
void
bridge_broadcast(sc, ifp, eh, m)
	struct bridge_softc *sc;
	struct ifnet *ifp;
	struct ether_header *eh;
	struct mbuf *m;
{
	struct bridge_iflist *p;
	struct mbuf *mc;
	int used = 0;

	for (p = LIST_FIRST(&sc->sc_iflist); p; p = LIST_NEXT(p, next)) {
		/*
		 * Don't retransmit out of the same interface where
		 * the packet was received from.
		 */
		if (p->ifp->if_index == ifp->if_index)
			continue;

		if ((p->bif_flags & IFBIF_DISCOVER) == 0 &&
		    (m->m_flags & (M_BCAST | M_MCAST)) == 0)
			continue;

		if ((p->ifp->if_flags & IFF_RUNNING) == 0)
			continue;

		if (IF_QFULL(&p->ifp->if_snd)) {
			sc->sc_if.if_oerrors++;
			continue;
		}

		if (SIMPLEQ_FIRST(&p->bif_brlout) &&
		    bridge_filterrule(SIMPLEQ_FIRST(&p->bif_brlout), eh) ==
		    BRL_ACTION_BLOCK)
			continue;

		/* If last one, reuse the passed-in mbuf */
		if (LIST_NEXT(p, next) == NULL) {
			mc = m;
			used = 1;
		} else {
			mc = m_copym(m, 0, M_COPYALL, M_DONTWAIT);
			if (mc == NULL) {
				sc->sc_if.if_oerrors++;
				continue;
			}
		}

		if (p->bif_flags & IFBIF_BLOCKNONIP &&
		    bridge_blocknonip(eh, mc)) {
			m_freem(mc);
			continue;
		}

		sc->sc_if.if_opackets++;
		sc->sc_if.if_obytes += mc->m_pkthdr.len;
		if (ifp && ((eh->ether_shost[0] & 1) == 0) )
			ifp->if_omcasts++;
                // Also count the bytes in the outgoing interface; normally
                // done in if_ethersubr.c but here we bypass that route.
                p->ifp->if_obytes += m->m_pkthdr.len;
		IF_ENQUEUE(&p->ifp->if_snd, mc);
		if ((p->ifp->if_flags & IFF_OACTIVE) == 0)
			(*p->ifp->if_start)(p->ifp);
	}

	if (!used)
		m_freem(m);
}

struct ifnet *
bridge_rtupdate(sc, ea, ifp, setflags, flags)
	struct bridge_softc *sc;
	struct ether_addr *ea;
	struct ifnet *ifp;
	int setflags;
	u_int8_t flags;
{
	struct bridge_rtnode *p, *q;
	u_int32_t h;
	int s, dir;

	s = splhigh();
	if (sc->sc_rts == NULL) {
		if (setflags && flags == IFBAF_STATIC) {
			sc->sc_rts = (struct bridge_rthead *)malloc(
			    BRIDGE_RTABLE_SIZE *
			    (sizeof(struct bridge_rthead)),M_DEVBUF,M_NOWAIT);

			if (sc->sc_rts == NULL)
				goto done;

			for (h = 0; h < BRIDGE_RTABLE_SIZE; h++)
				LIST_INIT(&sc->sc_rts[h]);
		} else
			goto done;
	}

	h = bridge_hash(ea);
	p = LIST_FIRST(&sc->sc_rts[h]);
	if (p == NULL) {
		if (sc->sc_brtcnt >= sc->sc_brtmax)
			goto done;
		p = (struct bridge_rtnode *)malloc(
		    sizeof(struct bridge_rtnode), M_DEVBUF, M_NOWAIT);
		if (p == NULL)
			goto done;

		bcopy(ea, &p->brt_addr, sizeof(p->brt_addr));
		p->brt_if = ifp;
		p->brt_age = 1;

		if (setflags)
			p->brt_flags = flags;
		else
			p->brt_flags = IFBAF_DYNAMIC;

		LIST_INSERT_HEAD(&sc->sc_rts[h], p, brt_next);
		sc->sc_brtcnt++;
		goto want;
	}

	do {
		q = p;
		p = LIST_NEXT(p, brt_next);

		dir = memcmp(ea, &q->brt_addr, sizeof(q->brt_addr));
		if (dir == 0) {
			if (setflags) {
				q->brt_if = ifp;
				q->brt_flags = flags;
			}

			if (q->brt_if == ifp)
				q->brt_age = 1;
			ifp = q->brt_if;
			goto want;
		}

		if (dir > 0) {
			if (sc->sc_brtcnt >= sc->sc_brtmax)
				goto done;
			p = (struct bridge_rtnode *)malloc(
			    sizeof(struct bridge_rtnode), M_DEVBUF, M_NOWAIT);
			if (p == NULL)
				goto done;

			bcopy(ea, &p->brt_addr, sizeof(p->brt_addr));
			p->brt_if = ifp;
			p->brt_age = 1;

			if (setflags)
				p->brt_flags = flags;
			else
				p->brt_flags = IFBAF_DYNAMIC;

			LIST_INSERT_BEFORE(q, p, brt_next);
			sc->sc_brtcnt++;
			goto want;
		}

		if (p == NULL) {
			if (sc->sc_brtcnt >= sc->sc_brtmax)
				goto done;
			p = (struct bridge_rtnode *)malloc(
			    sizeof(struct bridge_rtnode), M_DEVBUF, M_NOWAIT);
			if (p == NULL)
				goto done;

			bcopy(ea, &p->brt_addr, sizeof(p->brt_addr));
			p->brt_if = ifp;
			p->brt_age = 1;

			if (setflags)
				p->brt_flags = flags;
			else
				p->brt_flags = IFBAF_DYNAMIC;
			LIST_INSERT_AFTER(q, p, brt_next);
			sc->sc_brtcnt++;
			goto want;
		}
	} while (p != NULL);

done:
	ifp = NULL;
want:
	splx(s);
	return (ifp);
}

struct ifnet *
bridge_rtlookup(sc, ea)
	struct bridge_softc *sc;
	struct ether_addr *ea;
{
	struct bridge_rtnode *p;
	u_int32_t h;
	int s, dir;

	/*
	 * Lock out everything else
	 */
	s = splhigh();

	if (sc->sc_rts == NULL)
		goto fail;

	h = bridge_hash(ea);
	p = LIST_FIRST(&sc->sc_rts[h]);
	while (p != NULL) {
		dir = memcmp(ea, &p->brt_addr, sizeof(p->brt_addr));
		if (dir == 0) {
			splx(s);
			return (p->brt_if);
		}
		if (dir > 0)
			goto fail;
		p = LIST_NEXT(p, brt_next);
	}
fail:
	splx(s);
	return (NULL);
}

/*
 * The following hash function is adapted from 'Hash Functions' by Bob Jenkins
 * ("Algorithm Alley", Dr. Dobbs Journal, September 1997).
 * "You may use this code any way you wish, private, educational, or
 *  commercial.  It's free."
 */
#define	mix(a,b,c) \
	do {						\
		a -= b; a -= c; a ^= (c >> 13);		\
		b -= c; b -= a; b ^= (a << 8);		\
		c -= a; c -= b; c ^= (b >> 13);		\
		a -= b; a -= c; a ^= (c >> 12);		\
		b -= c; b -= a; b ^= (a << 16);		\
		c -= a; c -= b; c ^= (b >> 5);		\
		a -= b; a -= c; a ^= (c >> 3);		\
		b -= c; b -= a; b ^= (a << 10);		\
		c -= a; c -= b; c ^= (b >> 15);		\
	} while(0)

u_int32_t
bridge_hash(addr)
	struct ether_addr *addr;
{
	u_int32_t a = 0x9e3779b9, b = 0x9e3779b9, c = 0xdeadbeef;

	b += addr->ether_addr_octet[5] << 8;
	b += addr->ether_addr_octet[4];
	a += addr->ether_addr_octet[3] << 24;
	a += addr->ether_addr_octet[2] << 16;
	a += addr->ether_addr_octet[1] << 8;
	a += addr->ether_addr_octet[0];

	mix(a, b, c);
	return (c & BRIDGE_RTABLE_MASK);
}

/*
 * Trim the routing table so that we've got a number of routes
 * less than or equal to the maximum.
 */
void
bridge_rttrim(sc)
	struct bridge_softc *sc;
{
	struct bridge_rtnode *n, *p;
	int s, i;

	s = splhigh();
	if (sc->sc_rts == NULL)
		goto done;

	/*
	 * Make sure we have to trim the address table
	 */
	if (sc->sc_brtcnt <= sc->sc_brtmax)
		goto done;

	/*
	 * Force an aging cycle, this might trim enough addresses.
	 */
	splx(s);
	bridge_rtage(sc);
	s = splhigh();

	if (sc->sc_brtcnt <= sc->sc_brtmax)
		goto done;

	for (i = 0; i < BRIDGE_RTABLE_SIZE; i++) {
		n = LIST_FIRST(&sc->sc_rts[i]);
		while (n != NULL) {
			p = LIST_NEXT(n, brt_next);
			if ((n->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC) {
				LIST_REMOVE(n, brt_next);
				sc->sc_brtcnt--;
				free(n, M_DEVBUF);
				n = p;
				if (sc->sc_brtcnt <= sc->sc_brtmax)
					goto done;
			}
		}
	}

done:
	if (sc->sc_rts != NULL && sc->sc_brtcnt == 0 &&
	    (sc->sc_if.if_flags & IFF_UP) == 0) {
		free(sc->sc_rts, M_DEVBUF);
		sc->sc_rts = NULL;
	}

	splx(s);
}