Move code to handle BPF and bridging for incoming Ethernet packets out

of the individual drivers and into the common routine ether_input().
Also, remove the (incomplete) hack for matching ethernet headers
in the ip_fw code.

The good news: net result of 1016 lines removed, and this should make
bridging now work with *all* Ethernet drivers.

The bad news: it's nearly impossible to test every driver, especially
for bridging, and I was unable to get much testing help on the mailing
lists.

Reviewed by:	freebsd-net

1 files changed, 23 insertions, 35 deletions

diff --git a/sys/net/bridge.c b/sys/net/bridge.c
index e3fcc3f..83b711e 100644
--- a/sys/net/bridge.c
+++ b/sys/net/bridge.c
@@ -31,9 +31,8 @@
  * A bridging table holds the source MAC address/dest. interface for each
  * known node. The table is indexed using an hash of the source address.
  *
- * Input packets are tapped near the end of the input routine in each
- * driver (near the call to bpf_mtap, or before the call to ether_input)
- * and analysed calling bridge_in(). Depending on the result, the packet
+ * Input packets are tapped near the beginning of ether_input(), and
+ * analysed by calling bridge_in(). Depending on the result, the packet
  * can be forwarded to one or more output interfaces using bdg_forward(),
  * and/or sent to the upper layer (e.g. in case of multicast).
  *
@@ -163,7 +162,7 @@ static struct bdg_softc *ifp2sc = NULL ;
 #define	IFP_CHK(ifp, x) \
 	if (ifp2sc[ifp->if_index].magic != 0xDEADBEEF) { x ; }
 
-#define	SAMECLUSTER(ifp,src,eh) \
+#define	SAMECLUSTER(ifp,src) \
 	(src == NULL || CLUSTER(ifp) == CLUSTER(src) )
 
 /*
@@ -473,11 +472,9 @@ bdginit(void *dummy)
 
 /*
  * bridge_in() is invoked to perform bridging decision on input packets.
+ *
  * On Input:
- *   m		packet to be bridged. The mbuf need not to hold the
- *		whole packet, only the first 14 bytes suffice. We
- *		assume them to be contiguous. No alignment assumptions
- *		because they are not a problem on i386 class machines.
+ *   eh		Ethernet header of the incoming packet.
  *
  * On Return: destination of packet, one of
  *   BDG_BCAST	broadcast
@@ -490,16 +487,12 @@ bdginit(void *dummy)
  * to fetch more of the packet, or simply drop it completely.
  */
 
-
 struct ifnet *
-bridge_in(struct mbuf *m)
+bridge_in(struct ifnet *ifp, struct ether_header *eh)
 {
     int index;
-    struct ifnet *ifp = m->m_pkthdr.rcvif,  *dst , *old ;
+    struct ifnet *dst , *old ;
     int dropit = MUTED(ifp) ;
-    struct ether_header *eh;
-
-    eh = mtod(m, struct ether_header *);
 
     /*
      * hash the source address
@@ -545,7 +538,7 @@ bridge_in(struct mbuf *m)
 	bcopy(eh->ether_shost, bdg_table[index].etheraddr, 6);
 	bdg_table[index].name = ifp ;
     }
-    dst = bridge_dst_lookup(m);
+    dst = bridge_dst_lookup(eh);
     /* Return values:
      *   BDG_BCAST, BDG_MCAST, BDG_LOCAL, BDG_UNKNOWN, BDG_DROP, ifp.
      * For muted interfaces, the first 3 are changed in BDG_LOCAL,
@@ -599,7 +592,7 @@ bridge_in(struct mbuf *m)
  *    *m0  -- pointer to the packet (NULL if still existent)
  */
 int
-bdg_forward (struct mbuf **m0, struct ifnet *dst)
+bdg_forward(struct mbuf **m0, struct ether_header *const eh, struct ifnet *dst)
 {
     struct ifnet *src = (*m0)->m_pkthdr.rcvif; /* could be NULL in output */
     struct ifnet *ifp, *last = NULL ;
@@ -608,8 +601,6 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
     int once = 0;      /* loop only once */
     struct mbuf *m ;
 
-    struct ether_header *eh = mtod(*m0, struct ether_header *); /* XXX */
-
     if (dst == BDG_DROP) { /* this should not happen */
 	printf("xx bdg_forward for BDG_DROP\n");
 	m_freem(*m0) ;
@@ -642,7 +633,6 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
      * ethernet header.
      */
     if (ip_fw_chk_ptr) {
-	u_int16_t dummy = 0 ;
 	struct ip_fw_chain *rule = NULL ;
 	int off;
 	struct ip *ip ;
@@ -658,7 +648,6 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 	    (*m0) = m = m->m_next ;
 
 	    src = m->m_pkthdr.rcvif; /* could be NULL in output */
-	    eh = mtod(m, struct ether_header *); /* XXX */
 	    canfree = 1 ; /* for sure, a copy is not needed later. */
 	    goto forward; /* HACK! I should obey the fw_one_pass */
 	}
@@ -680,7 +669,7 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 	     * Need to make a copy (and for good measure, make sure that
 	     * the header is contiguous). The original is still in *m0
 	     */
-	    int needed = min(MHLEN, 14+max_protohdr) ;
+	    int needed = min(MHLEN, max_protohdr) ;
 	    needed = min(needed, (*m0)->m_len ) ;
 
 	    m = m_copypacket( (*m0), M_DONTWAIT);
@@ -688,8 +677,7 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 	        printf("-- bdg: m_copypacket failed.\n") ;
 		return ENOBUFS ;
 	    }
-	    m = m_pullup(m, needed) ;
-	    if ( m == NULL ) {
+	    if (m->m_len < needed && (m = m_pullup(m, needed)) == NULL) {
 		printf("-- bdg: pullup failed.\n") ;
 		return ENOBUFS ;
 	    }
@@ -699,8 +687,7 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 	 * before calling the firewall, swap fields the same as IP does.
 	 * here we assume the pkt is an IP one and the header is contiguous
 	 */
-	eh = mtod(m, struct ether_header *);
-	ip = (struct ip *)(eh + 1 ) ;
+	ip = mtod(m, struct ip *);
 	NTOHS(ip->ip_len);
 	NTOHS(ip->ip_id);
 	NTOHS(ip->ip_off);
@@ -709,7 +696,7 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 	 * The third parameter to the firewall code is the dst.  interface.
 	 * Since we apply checks only on input pkts we use NULL.
 	 */
-	off = (*ip_fw_chk_ptr)(NULL, 0, NULL, &dummy, &m, &rule, NULL) ;
+	off = (*ip_fw_chk_ptr)(&ip, 0, NULL, NULL, &m, &rule, NULL);
 
 	if (m == NULL) { /* pkt discarded by firewall */
 	    /*
@@ -724,11 +711,9 @@ bdg_forward (struct mbuf **m0, struct ifnet *dst)
 
 	/*
 	 * If we get here, the firewall has passed the pkt, but the
-	 * mbuf pointer might have changed. Restore eh, ip, and the
-	 * fields NTOHS()'d. Then, if canfree==1, also restore *m0.
+	 * mbuf pointer might have changed. Restore the fields NTOHS()'d.
+	 * Then, if canfree==1, also restore *m0.
 	 */
-	eh = mtod(m, struct ether_header *);
-	ip = (struct ip *)(eh + 1 ) ;
 	HTONS(ip->ip_len);
 	HTONS(ip->ip_id);
 	HTONS(ip->ip_off);
@@ -774,11 +759,10 @@ forward:
      * but better than having packets corrupt!
      */
     if (canfree == 0 ) {
-	int needed = min(MHLEN, 14+max_protohdr) ;
+	int needed = min(MHLEN, max_protohdr) ;
 	needed = min(needed, (*m0)->m_len ) ;
 
-	*m0 = m_pullup( *m0, needed) ;
-	if ( *m0 == NULL ) {
+	if ((*m0)->m_len < needed && (*m0 = m_pullup(*m0, needed)) == NULL) {
 	    printf("-- bdg: pullup failed.\n") ;
 	    return ENOBUFS ;
 	}
@@ -795,9 +779,13 @@ forward:
 		return ENOBUFS ; /* the original is still there... */
 	    }
 	    /*
-	     * Last part of ether_output: queue pkt and start
+	     * Last part of ether_output: add header, queue pkt and start
 	     * output if interface not yet active.
 	     */
+	    M_PREPEND(m, ETHER_HDR_LEN, M_DONTWAIT);
+	    if (m == NULL)
+		    return ENOBUFS;
+	    bcopy(eh, mtod(m, struct ether_header *), ETHER_HDR_LEN);
 	    s = splimp();
 	    if (IF_QFULL(&last->if_snd)) {
 		IF_DROP(&last->if_snd);
@@ -828,7 +816,7 @@ forward:
 		! IF_QFULL(&ifp->if_snd) &&
 		(ifp->if_flags & (IFF_UP|IFF_RUNNING)) ==
 			 (IFF_UP|IFF_RUNNING) &&
-		SAMECLUSTER(ifp, src, eh) && !MUTED(ifp) )
+		SAMECLUSTER(ifp, src) && !MUTED(ifp) )
 	    last = ifp ;
 	ifp = ifp->if_link.tqe_next ;
 	if (ifp == NULL)