ADJ: midchain delegate to performing stacking

this can be used by e.g. tunnels so it doesn't need to be
implemented for each tunnel type.

Change-Id: I0790f89aa49f83421612b35108cce67693285999
Signed-off-by: Neale Ranns <nranns@cisco.com>

5 files changed, 237 insertions, 5 deletions

diff --git a/src/vnet/adj/adj.c b/src/vnet/adj/adj.c
index 3ca3d6015f9..9d18dbf2727 100644
--- a/src/vnet/adj/adj.c
+++ b/src/vnet/adj/adj.c
@@ -537,10 +537,32 @@ static fib_node_back_walk_rc_t
 adj_back_walk_notify (fib_node_t *node,
 		      fib_node_back_walk_ctx_t *ctx)
 {
-    /*
-     * Que pasa. yo soj en el final!
-     */
-    ASSERT(0);
+    ip_adjacency_t *adj;
+
+    adj = ADJ_FROM_NODE(node);
+
+    switch (adj->lookup_next_index)
+    {
+    case IP_LOOKUP_NEXT_MIDCHAIN:
+        adj_midchain_delegate_restack(adj_get_index(adj));
+        break;
+    case IP_LOOKUP_NEXT_ARP:
+    case IP_LOOKUP_NEXT_REWRITE:
+    case IP_LOOKUP_NEXT_BCAST:
+    case IP_LOOKUP_NEXT_GLEAN:
+    case IP_LOOKUP_NEXT_MCAST:
+    case IP_LOOKUP_NEXT_MCAST_MIDCHAIN:
+    case IP_LOOKUP_NEXT_DROP:
+    case IP_LOOKUP_NEXT_PUNT:
+    case IP_LOOKUP_NEXT_LOCAL:
+    case IP_LOOKUP_NEXT_ICMP_ERROR:
+    case IP_LOOKUP_N_NEXT:
+        /*
+         * Que pasa. yo soj en el final!
+         */
+        ASSERT(0);
+        break;
+    }
 
     return (FIB_NODE_BACK_WALK_CONTINUE);
 }
diff --git a/src/vnet/adj/adj_delegate.c b/src/vnet/adj/adj_delegate.c
index 15dcb02afaa..cd5301c1e77 100644
--- a/src/vnet/adj/adj_delegate.c
+++ b/src/vnet/adj/adj_delegate.c
@@ -25,7 +25,7 @@ static adj_delegate_vft_t *ad_vfts;
 /**
  * The value of the last dynamically allocated delegeate value
  */
-static adj_delegate_type_t ad_max_id = ADJ_DELEGATE_BFD;
+static adj_delegate_type_t ad_max_id = ADJ_DELEGATE_LAST;
 
 static adj_delegate_t *
 adj_delegate_find_i (const ip_adjacency_t *adj,
diff --git a/src/vnet/adj/adj_delegate.h b/src/vnet/adj/adj_delegate.h
index 13bf911c5a6..f6da245bb52 100644
--- a/src/vnet/adj/adj_delegate.h
+++ b/src/vnet/adj/adj_delegate.h
@@ -36,8 +36,14 @@ typedef enum adj_delegate_type_t_ {
      * BFD session state
      */
     ADJ_DELEGATE_BFD,
+    /**
+     * Stacking of a midchain's nexthop
+     */
+    ADJ_DELEGATE_MIDCHAIN,
 } adj_delegate_type_t;
 
+#define ADJ_DELEGATE_LAST (ADJ_DELEGATE_MIDCHAIN)
+
 /**
  * Adj delegate. This object is attached to the adjacency.
  */
diff --git a/src/vnet/adj/adj_midchain.h b/src/vnet/adj/adj_midchain.h
index 24fea427a6b..1f5deaecd95 100644
--- a/src/vnet/adj/adj_midchain.h
+++ b/src/vnet/adj/adj_midchain.h
@@ -118,4 +118,25 @@ extern void adj_midchain_module_init(void);
  */
 extern u8* format_adj_midchain(u8* s, va_list *ap);
 
+/**
+ * @brief
+ *  create/attach a midchain delegate and stack it on the prefix passed
+ * @param ai - the index of the adjacency to stack
+ * @param fib_index - The FIB index of the prefix on which to stack
+ * @param pfx - The prefix on which to stack
+ */
+extern void adj_midchain_delegate_stack(adj_index_t ai,
+                                        u32 fib_index,
+                                        const fib_prefix_t *pfx);
+
+/**
+ * @brief restack a midchain delegate
+ */
+extern void adj_midchain_delegate_restack(adj_index_t ai);
+
+/**
+ * @brief unstack a midchain delegate (this stacks it on a drop)
+ */
+extern void adj_midchain_delegate_unstack(adj_index_t ai);
+
 #endif
diff --git a/src/vnet/adj/adj_midchain_delegate.c b/src/vnet/adj/adj_midchain_delegate.c
new file mode 100644
index 00000000000..922283e92cf
--- /dev/null
+++ b/src/vnet/adj/adj_midchain_delegate.c
@@ -0,0 +1,183 @@
+/*
+ * 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_midchain.h>
+#include <vnet/fib/fib_table.h>
+
+/**
+ * Midchain stacker delegate
+ */
+typedef struct adj_midchain_delegate_t_
+{
+    /**
+     * the Fib Entry we are stacked on
+     */
+    fib_node_index_t amd_fei;
+
+    /**
+     * The sibling entry on the FIB entry
+     */
+    u32 amd_sibling;
+} adj_midchain_delegate_t;
+
+/**
+ * Pool of delegates
+ */
+static adj_midchain_delegate_t *amd_pool;
+
+static inline const adj_midchain_delegate_t*
+adj_midchain_from_const_base (const adj_delegate_t *ad)
+{
+    if (NULL != ad)
+    {
+        return (pool_elt_at_index(amd_pool, ad->ad_index));
+    }
+    return (NULL);
+}
+
+static void
+adj_midchain_delegate_restack_i (adj_index_t ai,
+                                 adj_midchain_delegate_t *amd)
+{
+    if (vnet_sw_interface_is_admin_up (vnet_get_main (),
+                                       adj_get_sw_if_index(ai)) &&
+        (FIB_NODE_INDEX_INVALID != amd->amd_fei))
+    {
+        const fib_prefix_t *pfx;
+
+        pfx = fib_entry_get_prefix(amd->amd_fei);
+
+        adj_nbr_midchain_stack_on_fib_entry (
+            ai,
+            amd->amd_fei,
+            fib_forw_chain_type_from_fib_proto(pfx->fp_proto));
+    }
+    else
+    {
+        adj_nbr_midchain_unstack (ai);
+    }
+}
+
+void
+adj_midchain_delegate_restack (adj_index_t ai)
+{
+    adj_midchain_delegate_t *amd;
+    ip_adjacency_t *adj;
+    adj_delegate_t *ad;
+
+    /*
+     * if there's a delegate already use that
+     */
+    adj = adj_get(ai);
+    ad = adj_delegate_get(adj, ADJ_DELEGATE_MIDCHAIN);
+
+    if (NULL != ad)
+    {
+        amd = pool_elt_at_index(amd_pool, ad->ad_index);
+
+        adj_midchain_delegate_restack_i(ai, amd);
+    }
+    /*
+     * else
+     *  nothing to stack
+     */
+}
+
+void
+adj_midchain_delegate_stack (adj_index_t ai,
+                             u32 fib_index,
+                             const fib_prefix_t *pfx)
+{
+    adj_midchain_delegate_t *amd;
+    ip_adjacency_t *adj;
+    adj_delegate_t *ad;
+
+    /*
+     * if there's a delegate already use that
+     */
+    adj = adj_get(ai);
+    ad = adj_delegate_get(adj, ADJ_DELEGATE_MIDCHAIN);
+
+    if (NULL != ad)
+    {
+        amd = pool_elt_at_index(amd_pool, ad->ad_index);
+    }
+    else
+    {
+        pool_get(amd_pool, amd);
+        amd->amd_fei = FIB_NODE_INDEX_INVALID;
+        adj_delegate_add(adj, ADJ_DELEGATE_MIDCHAIN, amd - amd_pool);
+
+        amd->amd_fei = fib_table_entry_special_add(fib_index,
+                                                   pfx,
+                                                   FIB_SOURCE_RR,
+                                                   FIB_ENTRY_FLAG_NONE);
+        amd->amd_sibling = fib_entry_child_add(amd->amd_fei,
+                                               FIB_NODE_TYPE_ADJ,
+                                               ai);
+    }
+    adj_midchain_delegate_restack_i(ai, amd);
+}
+
+void
+adj_midchain_delegate_unstack (adj_index_t ai)
+{
+    adj_nbr_midchain_unstack(ai);
+}
+
+static void
+adj_midchain_delegate_adj_deleted (adj_delegate_t *ad)
+{
+    adj_midchain_delegate_t *amd;
+
+    amd = pool_elt_at_index(amd_pool, ad->ad_index);
+
+    fib_entry_child_remove (amd->amd_fei, amd->amd_sibling);
+    fib_table_entry_delete_index (amd->amd_fei, FIB_SOURCE_RR);
+
+    pool_put(amd_pool, amd);
+}
+
+/**
+ * Print a delegate that represents MIDCHAIN tracking
+ */
+static u8 *
+adj_midchain_delegate_fmt (const adj_delegate_t *aed, u8 *s)
+{
+    const adj_midchain_delegate_t *amd = adj_midchain_from_const_base(aed);
+
+    s = format(s, "MIDCHAIN:[fib-entry:%d]", amd->amd_fei);
+
+    return (s);
+}
+
+const static adj_delegate_vft_t adj_delegate_vft = {
+  .adv_format = adj_midchain_delegate_fmt,
+  .adv_adj_deleted = adj_midchain_delegate_adj_deleted,
+};
+
+static clib_error_t *
+adj_midchain_delegate_module_init (vlib_main_t * vm)
+{
+    clib_error_t * error = NULL;
+
+    adj_delegate_register_type (ADJ_DELEGATE_MIDCHAIN, &adj_delegate_vft);
+
+    return (error);
+}
+
+VLIB_INIT_FUNCTION (adj_midchain_delegate_module_init);
+