IP Multicast FIB (mfib)

 - IPv[46] mfib tables with support for (*,G/m), (*,G) and (S,G) exact and longest prefix match
 - Replication represented via a new replicate DPO.
 - RPF configuration and data-plane checking
 - data-plane signals sent to listening control planes.

The functions of multicast forwarding entries differ from their unicast conterparts, so we introduce a new mfib_table_t and mfib_entry_t objects. However, we re-use the fib_path_list to resolve and build the entry's output list. the fib_path_list provides the service to construct a replicate DPO for multicast.

'make tests' is added to with two new suites; TEST=mfib, this is invocation of the CLI command 'test mfib' which deals with many path add/remove, flag set/unset scenarios, TEST=ip-mcast, data-plane forwarding tests.

Updated applications to use the new MIFB functions;
  - IPv6 NS/RA.
  - DHCPv6
 unit tests for these are undated accordingly.

Change-Id: I49ec37b01f1b170335a5697541c8fd30e6d3a961
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/fib/ip4_fib.c b/src/vnet/fib/ip4_fib.c
index f6ebce0..e8211c8 100644
--- a/src/vnet/fib/ip4_fib.c
+++ b/src/vnet/fib/ip4_fib.c
@@ -378,16 +378,13 @@
     ip4_fib_mtrie_add_del_route(fib, *addr, len, dpo->dpoi_index, 1); // DELETE
 }
 
-static void
-ip4_fib_table_show_all (ip4_fib_t *fib,
-			vlib_main_t * vm)
+void
+ip4_fib_table_walk (ip4_fib_t *fib,
+                    fib_table_walk_fn_t fn,
+                    void *ctx)
 {
-    fib_node_index_t *fib_entry_indicies;
-    fib_node_index_t *fib_entry_index;
     int i;
 
-    fib_entry_indicies = NULL;
-
     for (i = 0; i < ARRAY_LEN (fib->fib_entry_by_dst_address); i++)
     {
 	uword * hash = fib->fib_entry_by_dst_address[i];
@@ -398,14 +395,45 @@
 
 	    hash_foreach_pair (p, hash,
 	    ({
-		vec_add1(fib_entry_indicies, p->value[0]);
+		fn(p->value[0], ctx);
 	    }));
 	}
     }
+}
 
-    vec_sort_with_function(fib_entry_indicies, fib_entry_cmp_for_sort);
+/**
+ * Walk show context
+ */
+typedef struct ip4_fib_show_walk_ctx_t_
+{
+    fib_node_index_t *ifsw_indicies;
+} ip4_fib_show_walk_ctx_t;
 
-    vec_foreach(fib_entry_index, fib_entry_indicies)
+static int
+ip4_fib_show_walk_cb (fib_node_index_t fib_entry_index,
+                      void *arg)
+{
+    ip4_fib_show_walk_ctx_t *ctx = arg;
+
+    vec_add1(ctx->ifsw_indicies, fib_entry_index);
+
+    return (1);
+}
+
+static void
+ip4_fib_table_show_all (ip4_fib_t *fib,
+			vlib_main_t * vm)
+{
+    ip4_fib_show_walk_ctx_t ctx = {
+        .ifsw_indicies = NULL,
+    };
+    fib_node_index_t *fib_entry_index;
+
+    ip4_fib_table_walk(fib, ip4_fib_show_walk_cb, &ctx);
+    vec_sort_with_function(ctx.ifsw_indicies,
+                           fib_entry_cmp_for_sort);
+
+    vec_foreach(fib_entry_index, ctx.ifsw_indicies)
     {
 	vlib_cli_output(vm, "%U",
                         format_fib_entry,
@@ -413,7 +441,7 @@
                         FIB_ENTRY_FORMAT_BRIEF);
     }
 
-    vec_free(fib_entry_indicies);
+    vec_free(ctx.ifsw_indicies);
 }
 
 static void