tunneling: Reduce priority of multicast tunnels.

It's possible to have an incoming packet that matches both a unicast
and multicast tunnel if the source address corresponds to the remote_ip
of a unicast tunnel and the destination is multicast.  Currently this
will match the multicast tunnel but in reality the unicast tunnel
should probably be considered more specific.  This is actually a
common situation in protocols that use a combination of multicast
for flooding and unicast for responses.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

diff --git a/datapath/tunnel.c b/datapath/tunnel.c
index 9bb9cef..6c0e9b7 100644 (file)
--- a/datapath/tunnel.c
+++ b/datapath/tunnel.c
@@ -288,26 +288,7 @@ struct vport *tnl_find_port(__be32 saddr, __be32 daddr, __be64 key,
 {
        struct port_lookup_key lookup;
        struct vport *vport;
-
-       if (ipv4_is_multicast(saddr)) {
-               lookup.saddr = 0;
-               lookup.daddr = saddr;
-               if (key_remote_ports) {
-                       lookup.tunnel_type = tunnel_type | TNL_T_KEY_EXACT;
-                       lookup.in_key = key;
-                       vport = port_table_lookup(&lookup, mutable);
-                       if (vport)
-                               return vport;
-               }
-               if (remote_ports) {
-                       lookup.tunnel_type = tunnel_type | TNL_T_KEY_MATCH;
-                       lookup.in_key = 0;
-                       vport = port_table_lookup(&lookup, mutable);
-                       if (vport)
-                               return vport;
-               }
-               return NULL;
-       }
+       bool is_multicast = ipv4_is_multicast(saddr);
 
        lookup.saddr = saddr;
        lookup.daddr = daddr;
@@ -315,7 +296,7 @@ struct vport *tnl_find_port(__be32 saddr, __be32 daddr, __be64 key,
        /* First try for exact match on in_key. */
        lookup.in_key = key;
        lookup.tunnel_type = tunnel_type | TNL_T_KEY_EXACT;
-       if (key_local_remote_ports) {
+       if (!is_multicast && key_local_remote_ports) {
                vport = port_table_lookup(&lookup, mutable);
                if (vport)
                        return vport;
@@ -332,7 +313,7 @@ struct vport *tnl_find_port(__be32 saddr, __be32 daddr, __be64 key,
        /* Then try matches that wildcard in_key. */
        lookup.in_key = 0;
        lookup.tunnel_type = tunnel_type | TNL_T_KEY_MATCH;
-       if (local_remote_ports) {
+       if (!is_multicast && local_remote_ports) {
                vport = port_table_lookup(&lookup, mutable);
                if (vport)
                        return vport;
@@ -344,6 +325,25 @@ struct vport *tnl_find_port(__be32 saddr, __be32 daddr, __be64 key,
                        return vport;
        }
 
+       if (is_multicast) {
+               lookup.saddr = 0;
+               lookup.daddr = saddr;
+               if (key_remote_ports) {
+                       lookup.tunnel_type = tunnel_type | TNL_T_KEY_EXACT;
+                       lookup.in_key = key;
+                       vport = port_table_lookup(&lookup, mutable);
+                       if (vport)
+                               return vport;
+               }
+               if (remote_ports) {
+                       lookup.tunnel_type = tunnel_type | TNL_T_KEY_MATCH;
+                       lookup.in_key = 0;
+                       vport = port_table_lookup(&lookup, mutable);
+                       if (vport)
+                               return vport;
+               }
+       }
+
        return NULL;
 }