ARP/ND entries for the same address on different interfaces (VPP-848)

there are, intentionally, no validation checks in the ARP/ND code to prevent an ARP/ND entry from being installed for an address that is not local to the interface's sub-net. This is ok, since the adjacency/FIB code is designed to handle this case using the 'refinement' criteria - i.e. only installing a FIB entry for the address if the address 'refines' (i.e. is more specific than) the interface's sub-net.
However, the refinement criteria currently operates on the FIB entry's prefix (which is a /32, so on the address) and not on the next-hop in the path.
So, enter multiple ARP entries for the same address on different links, and this refinement criteria uses only the last added path, and so will remove the FIB entry should the ARP entries be added in the 'wrong' order.
This fix updates the refinement criteria to work on each path of the FIB entry. The entry is installed if one of the paths refines the covers and only paths refining the cover contribute forwarding.
Per-path refinement checks are stored in path-extensions. The patch is rather large as path-extension, which were previously used only for out-going MPLS labels, have been generalized.

Change-Id: I00be359148cb948c32c52109e832a70537a7920a
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 61 insertions, 11 deletions

diff --git a/src/vnet/fib/fib_entry_src_api.c b/src/vnet/fib/fib_entry_src_api.c
index 19db8819ede..f895886bc0e 100644
--- a/src/vnet/fib/fib_entry_src_api.c
+++ b/src/vnet/fib/fib_entry_src_api.c
@@ -13,9 +13,10 @@
  * limitations under the License.
  */
 
-#include "fib_entry.h"
-#include "fib_entry_src.h"
-#include "fib_path_list.h"
+#include <vnet/fib/fib_entry.h>
+#include <vnet/fib/fib_entry_src.h>
+#include <vnet/fib/fib_path_list.h>
+#include <vnet/fib/fib_path_ext.h>
 
 /**
  * Source initialisation Function 
@@ -35,45 +36,94 @@ fib_entry_src_api_deinit (fib_entry_src_t *src)
 
 static void
 fib_entry_src_api_path_swap (fib_entry_src_t *src,
-			     const fib_entry_t *entry,
+                             const fib_entry_t *entry,
 			     fib_path_list_flags_t pl_flags,
-			     const fib_route_path_t *paths)
+			     const fib_route_path_t *rpaths)
 {
+    const fib_route_path_t *rpath;
+
+    fib_path_ext_list_flush(&src->fes_path_exts);
+
     src->fes_pl = fib_path_list_create((FIB_PATH_LIST_FLAG_SHARED | pl_flags),
-				       paths);
+				       rpaths);
+
+    vec_foreach(rpath, rpaths)
+    {
+        if (NULL != rpath->frp_label_stack)
+        {
+            fib_path_ext_list_push_back(&src->fes_path_exts,
+                                        src->fes_pl,
+                                        FIB_PATH_EXT_MPLS,
+                                        rpath);
+        }
+    }
 }
 
 static void
 fib_entry_src_api_path_add (fib_entry_src_t *src,
 			    const fib_entry_t *entry,
 			    fib_path_list_flags_t pl_flags,
-			    const fib_route_path_t *paths)
+			    const fib_route_path_t *rpaths)
 {
+    const fib_route_path_t *rpath;
+
     if (FIB_NODE_INDEX_INVALID == src->fes_pl)
     {	
 	src->fes_pl =
-	    fib_path_list_create((FIB_PATH_LIST_FLAG_SHARED | pl_flags), paths);
+	    fib_path_list_create((FIB_PATH_LIST_FLAG_SHARED | pl_flags), rpaths);
     }
     else
     {
 	src->fes_pl =
 	    fib_path_list_copy_and_path_add(src->fes_pl,
 					    (FIB_PATH_LIST_FLAG_SHARED | pl_flags),
-					    paths);
+					    rpaths);
+    }
+
+    /*
+     * re-resolve all the path-extensions with the new path-list
+     */
+    fib_path_ext_list_resolve(&src->fes_path_exts, src->fes_pl);
+
+    /*
+     * if the path has a label we need to add a path extension
+     */
+    vec_foreach(rpath, rpaths)
+    {
+        if (NULL != rpath->frp_label_stack)
+        {
+            fib_path_ext_list_insert(&src->fes_path_exts,
+                                     src->fes_pl,
+                                     FIB_PATH_EXT_MPLS,
+                                     rpath);
+        }
     }
 }
 
 static void
 fib_entry_src_api_path_remove (fib_entry_src_t *src,
 			       fib_path_list_flags_t pl_flags,
-			       const fib_route_path_t *paths)
+			       const fib_route_path_t *rpaths)
 {
+    const fib_route_path_t *rpath;
+
     if (FIB_NODE_INDEX_INVALID != src->fes_pl)
     {
 	src->fes_pl =
 	    fib_path_list_copy_and_path_remove(src->fes_pl,
 					       (FIB_PATH_LIST_FLAG_SHARED | pl_flags),
-					       paths);
+					       rpaths);
+        /*
+         * remove the path-extension for the path
+         */
+        vec_foreach(rpath, rpaths)
+        {
+            fib_path_ext_list_remove(&src->fes_path_exts, FIB_PATH_EXT_MPLS, rpath);
+        };
+        /*
+         * resolve the remaining extensions
+         */
+        fib_path_ext_list_resolve(&src->fes_path_exts, src->fes_pl);
     }
 }