[DECNET]: Only use local routers

The attached patch makes DECnet routing only use routers from the same
area - rather than the highest rated router seen.

In theory there should not be an out-of-area router on a local network
but some networks are bridged rather than properly routed. VMS seems
to behave similarly: if I bring up a VMS node with no router then it
can't see anything else on the global network.

Signed-off-by: Patrick Caulfield <patrick@tykepenguin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
index 8d0cc3cf3e49..33ab256cfd4a 100644
--- a/net/decnet/dn_neigh.c
+++ b/net/decnet/dn_neigh.c
@@ -408,11 +408,14 @@ int dn_neigh_router_hello(struct sk_buff *skb)
                         }
                 }
 
-                if (!dn_db->router) {
-                        dn_db->router = neigh_clone(neigh);
-                } else {
-                        if (msg->priority > ((struct dn_neigh *)dn_db->router)->priority)
-                                neigh_release(xchg(&dn_db->router, neigh_clone(neigh)));
+                /* Only use routers in our area */
+                if ((dn_ntohs(src)>>10) == dn_ntohs((decnet_address)>>10)) {
+                        if (!dn_db->router) {
+                                dn_db->router = neigh_clone(neigh);
+                        } else {
+                                if (msg->priority > ((struct dn_neigh *)dn_db->router)->priority)
+                                        neigh_release(xchg(&dn_db->router, neigh_clone(neigh)));
+                        }
                 }
                 write_unlock(&neigh->lock);
                 neigh_release(neigh);