BFD-FIB interactions

- single-hop BFD: attach a delegate to the appropriate adjacency
- multi-hop BFD [not supported yet]: attach a delegate to the FIB entry.

adjacency/fib_entry state tracks the BFD session state. when the state is down the object does not contribute forwarding hence and hence dependent objects will not use it.
For example, if a route is ECMP via two adjacencies and one of them is BFD down, then only the other is used to forward (i.e. we don't drop half the traffic).

Change-Id: I0ef53e20e73b067001a132cd0a3045408811a822
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 144 insertions, 0 deletions

diff --git a/src/vnet/adj/adj_delegate.c b/src/vnet/adj/adj_delegate.c
new file mode 100644
index 00000000000..701b36e2fd9
--- /dev/null
+++ b/src/vnet/adj/adj_delegate.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/adj/adj_delegate.h>
+#include <vnet/adj/adj.h>
+#include <vnet/adj/adj_internal.h>
+
+static adj_delegate_t *
+adj_delegate_find_i (const ip_adjacency_t *adj,
+                     adj_delegate_type_t type,
+                     u32 *index)
+{
+    adj_delegate_t *delegate;
+    int ii;
+
+    ii = 0;
+    vec_foreach(delegate, adj->ia_delegates)
+    {
+	if (delegate->ad_type == type)
+	{
+            if (NULL != index)
+                *index = ii;
+
+	    return (delegate);
+	}
+	else
+	{
+	    ii++;
+	}
+    }
+
+    return (NULL);
+}
+
+adj_delegate_t *
+adj_delegate_get (const ip_adjacency_t *adj,
+                  adj_delegate_type_t type)
+{
+    return (adj_delegate_find_i(adj, type, NULL));
+}
+
+void
+adj_delegate_remove (ip_adjacency_t *adj,
+                     adj_delegate_type_t type)
+{
+    adj_delegate_t *aed;
+    u32 index = ~0;
+
+    aed = adj_delegate_find_i(adj, type, &index);
+
+    ASSERT(NULL != aed);
+
+    vec_del1(adj->ia_delegates, index);
+}
+
+static int
+adj_delegate_cmp_for_sort (void * v1,
+                           void * v2)
+{
+    adj_delegate_t *delegate1 = v1, *delegate2 = v2;
+
+    return (delegate1->ad_type - delegate2->ad_type);
+}
+
+static void
+adj_delegate_init (ip_adjacency_t *adj,
+                   adj_delegate_type_t type)
+
+{
+    adj_delegate_t delegate = {
+	.ad_adj_index = adj_get_index(adj),
+	.ad_type = type,
+    };
+
+    vec_add1(adj->ia_delegates, delegate);
+    vec_sort_with_function(adj->ia_delegates,
+			   adj_delegate_cmp_for_sort);
+}
+
+adj_delegate_t *
+adj_delegate_find_or_add (ip_adjacency_t *adj,
+                          adj_delegate_type_t adt)
+{
+    adj_delegate_t *delegate;
+
+    delegate = adj_delegate_get(adj, adt);
+
+    if (NULL == delegate)
+    {
+	adj_delegate_init(adj, adt);
+    }
+
+    return (adj_delegate_get(adj, adt));
+}
+
+/**
+ * typedef for printing a delegate
+ */
+typedef u8 * (*adj_delegate_format_t)(const adj_delegate_t *aed,
+                                      u8 *s);
+
+/**
+ * Print a delegate that represents BFD tracking
+ */
+static u8 *
+adj_delegate_fmt_bfd (const adj_delegate_t *aed,
+                      u8 *s)
+{
+    s = format(s, "BFD:[state:%d index:%d]",
+               aed->ad_bfd_state,
+               aed->ad_bfd_index);
+
+    return (s);
+}
+
+/**
+ * A delegate type to formatter map
+ */
+static adj_delegate_format_t aed_formatters[] =
+{
+    [ADJ_DELEGATE_BFD] = adj_delegate_fmt_bfd,
+};
+
+u8 *
+format_adj_deletegate (u8 * s, va_list * args)
+{
+    adj_delegate_t *aed;
+
+    aed = va_arg (*args, adj_delegate_t *);
+
+    return (aed_formatters[aed->ad_type](aed, s));
+}