ospf6d: fix setting of the forwarding address in AS-External LSAs

When redistributing a local route, ensure the forwarding address field
of AS-External LSAs is only set when the associated nexthop interface
is OSPF-enabled. This is necessary because the OSPF RFC requires that
the AS-External LSA forwarding address should be resolvable using an
intra-area or inter-area path.

Fixes #14462.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

diff --git a/ospf6d/ospf6_asbr.c b/ospf6d/ospf6_asbr.c
index 713dd820751c6749b8acd981518a52ddbea63816..99c3e162636b225cda12fafae27b0b1e40dfd5c9 100644 (file)
--- a/ospf6d/ospf6_asbr.c
+++ b/ospf6d/ospf6_asbr.c
@@ -1376,6 +1376,56 @@ ospf6_external_aggr_match(struct ospf6 *ospf6, struct prefix *p)
        return node->info;
 }
 
+static void ospf6_external_lsa_fwd_addr_set(struct ospf6 *ospf6,
+                                           const struct in6_addr *nexthop,
+                                           struct in6_addr *fwd_addr)
+{
+       struct vrf *vrf;
+       struct interface *ifp;
+       struct prefix nh;
+
+       /* Initialize forwarding address to zero. */
+       memset(fwd_addr, 0, sizeof(*fwd_addr));
+
+       vrf = vrf_lookup_by_id(ospf6->vrf_id);
+       if (!vrf)
+               return;
+
+       nh.family = AF_INET6;
+       nh.u.prefix6 = *nexthop;
+       nh.prefixlen = IPV6_MAX_BITLEN;
+
+       /*
+        * Use the route's nexthop as the forwarding address if it meets the
+        * following conditions:
+        * - It's a global address.
+        * - The associated nexthop interface is OSPF-enabled.
+        */
+       if (IN6_IS_ADDR_UNSPECIFIED(nexthop) || IN6_IS_ADDR_LINKLOCAL(nexthop))
+               return;
+
+       FOR_ALL_INTERFACES (vrf, ifp) {
+               struct ospf6_interface *oi = ifp->info;
+               struct connected *connected;
+               struct listnode *node;
+
+               if (!oi || CHECK_FLAG(oi->flag, OSPF6_INTERFACE_DISABLE))
+                       continue;
+
+               FOR_ALL_INTERFACES_ADDRESSES (ifp, connected, node) {
+                       if (connected->address->family != AF_INET6)
+                               continue;
+                       if (IN6_IS_ADDR_LINKLOCAL(&connected->address->u.prefix6))
+                               continue;
+                       if (!prefix_match(connected->address, &nh))
+                               continue;
+
+                       *fwd_addr = *nexthop;
+                       return;
+               }
+       }
+}
+
 void ospf6_asbr_redistribute_add(int type, ifindex_t ifindex,
                                 struct prefix *prefix,
                                 unsigned int nexthop_num,
@@ -1470,10 +1520,8 @@ void ospf6_asbr_redistribute_add(int type, ifindex_t ifindex,
 
                if (nexthop_num && nexthop) {
                        ospf6_route_add_nexthop(match, ifindex, nexthop);
-                       if (!IN6_IS_ADDR_UNSPECIFIED(nexthop)
-                           && !IN6_IS_ADDR_LINKLOCAL(nexthop))
-                               memcpy(&info->forwarding, nexthop,
-                                      sizeof(struct in6_addr));
+                       ospf6_external_lsa_fwd_addr_set(ospf6, nexthop,
+                                                       &info->forwarding);
                } else
                        ospf6_route_add_nexthop(match, ifindex, NULL);
 
@@ -1520,10 +1568,8 @@ void ospf6_asbr_redistribute_add(int type, ifindex_t ifindex,
        info->type = type;
        if (nexthop_num && nexthop) {
                ospf6_route_add_nexthop(route, ifindex, nexthop);
-               if (!IN6_IS_ADDR_UNSPECIFIED(nexthop)
-                   && !IN6_IS_ADDR_LINKLOCAL(nexthop))
-                       memcpy(&info->forwarding, nexthop,
-                              sizeof(struct in6_addr));
+               ospf6_external_lsa_fwd_addr_set(ospf6, nexthop,
+                                               &info->forwarding);
        } else
                ospf6_route_add_nexthop(route, ifindex, NULL);