FIB Interpose Source

The interpose source allows the source/provider to insert/interpose
a DPO in the forwarding chain of the FIB entry ahead of the forwarding
provided by the next best source. For example if the API source (i.e
the 'control plane') has provided an adjacency for forwarding, then
an interpose source (e.g. a monitoring service) couold interpose a
replicatte DPO to copy the traffic to another location AND forward
using the API's adjacency.
To use the interose feature an existing source (i.e FIB_SOURCE_PLUGIN_HI)
cn specifiy as a flag FIB_ENTRY_FLAG_INTERPOSE and provide a DPO to
interpose. One might also consider using interpose in conjunction with
FIB_ENTRY_FLAG_COVER_INHERIT to ensure the interpose object affects
all prefixes in the sub-tree.

Change-Id: I8b2737b985f8f7c08123406d0491881def347b52
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 370 insertions, 0 deletions

diff --git a/src/vnet/fib/fib_entry_src_interpose.c b/src/vnet/fib/fib_entry_src_interpose.c
new file mode 100644
index 00000000000..c362328f473
--- /dev/null
+++ b/src/vnet/fib/fib_entry_src_interpose.c
@@ -0,0 +1,370 @@
+/*
+ * 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 <vlib/vlib.h>
+#include <vnet/ip/format.h>
+#include <vnet/ip/lookup.h>
+#include <vnet/adj/adj.h>
+#include <vnet/dpo/drop_dpo.h>
+
+#include "fib_entry_src.h"
+#include "fib_entry_src_rr.h"
+#include "fib_entry_cover.h"
+#include "fib_entry.h"
+#include "fib_table.h"
+
+/*
+ * Source initialisation Function
+ */
+static void
+fib_entry_src_interpose_init (fib_entry_src_t *src)
+{
+    src->u.interpose.fesi_cover = FIB_NODE_INDEX_INVALID;
+    src->u.interpose.fesi_sibling = FIB_NODE_INDEX_INVALID;
+}
+
+/*
+ * Source deinitialisation Function
+ */
+static void
+fib_entry_src_interpose_deinit (fib_entry_src_t *src)
+{
+    ASSERT(src->u.interpose.fesi_cover == FIB_NODE_INDEX_INVALID);
+
+    src->u.interpose.fesi_cover = FIB_NODE_INDEX_INVALID;
+    src->u.interpose.fesi_sibling = FIB_NODE_INDEX_INVALID;
+
+    dpo_reset(&src->u.interpose.fesi_dpo);
+}
+
+static fib_entry_src_t *
+fib_entry_src_rr_get_next_best (const fib_entry_src_t *src,
+                                const fib_entry_t *fib_entry)
+{
+    fib_entry_src_t *next_src, *best_src = NULL;
+    fib_source_t source;
+
+    FOR_EACH_SRC_ADDED(fib_entry, next_src, source,
+    ({
+        /*
+         * skip to the next best source after this one
+         */
+        if (source <= src->fes_src)
+        {
+            continue;
+        }
+        else
+        {
+            best_src = next_src;
+            break;
+        }
+    }));
+
+    return (best_src);
+}
+
+/*
+ * Source activation. Called when the source is the new best source on the entry
+ */
+static int
+fib_entry_src_interpose_activate (fib_entry_src_t *src,
+                                  const fib_entry_t *fib_entry)
+{
+    fib_entry_src_t *best_src;
+    fib_node_index_t old_pl;
+    fib_entry_t *cover;
+
+    old_pl = src->fes_pl;
+    src->fes_pl = FIB_NODE_INDEX_INVALID;
+
+    /*
+     * The goal here is to find a path-list that will contribute forwarding
+     * for the entry.
+     * First check this entry for other sources that have a path-list
+     */
+    best_src = fib_entry_src_rr_get_next_best(src, fib_entry);
+
+    if (NULL != best_src)
+    {
+        const fib_entry_src_vft_t *vft;
+
+        best_src->fes_flags |= FIB_ENTRY_SRC_FLAG_CONTRIBUTING;
+        vft = fib_entry_src_get_vft(best_src);
+        /*
+         * there is another source for this entry. activate it so it
+         * can provide forwarding
+         */
+        if (NULL != vft->fesv_activate)
+        {
+            if (vft->fesv_activate(best_src, fib_entry))
+            {
+                /*
+                 * next best source activated ok, use its path list
+                 */
+                src->fes_pl = best_src->fes_pl;
+            }
+        }
+        else
+        {
+            /*
+             * next best source does not require activation, use its path list
+             */
+            src->fes_pl = best_src->fes_pl;
+        }
+    }
+    else
+    {
+        /*
+         * find the covering prefix. become a dependent thereof.
+         * for IP there should always be a cover, though it may be the default route.
+         * For MPLS there is never a cover.
+         */
+        if (FIB_PROTOCOL_MPLS == fib_entry->fe_prefix.fp_proto)
+        {
+            src->fes_pl = fib_path_list_create_special(DPO_PROTO_MPLS,
+                                                       FIB_PATH_LIST_FLAG_DROP,
+                                                       NULL);
+        }
+        else
+        {
+            src->u.interpose.fesi_cover =
+                fib_table_get_less_specific(fib_entry->fe_fib_index,
+                                            &fib_entry->fe_prefix);
+
+            ASSERT(FIB_NODE_INDEX_INVALID != src->u.interpose.fesi_cover);
+
+            cover = fib_entry_get(src->u.interpose.fesi_cover);
+
+            src->u.interpose.fesi_sibling =
+                fib_entry_cover_track(cover, fib_entry_get_index(fib_entry));
+
+            /*
+             * if the cover is attached then install an attached-host path
+             * (like an adj-fib). Otherwise inherit the forwarding from the cover
+             */
+            if (FIB_ENTRY_FLAG_ATTACHED & fib_entry_get_flags_i(cover))
+            {
+                fib_entry_src_rr_resolve_via_connected(src, fib_entry, cover);
+            }
+            else
+            {
+                fib_entry_src_rr_use_covers_pl(src, fib_entry, cover);
+            }
+        }
+    }
+
+    fib_path_list_unlock(old_pl);
+    fib_path_list_lock(src->fes_pl);
+
+    /*
+     * return go for install
+     */
+    return (!0);
+}
+
+/**
+ * Source Deactivate.
+ * Called when the source is no longer best source on the entry
+ */
+static void
+fib_entry_src_interpose_deactivate (fib_entry_src_t *src,
+                                    const fib_entry_t *fib_entry)
+{
+    fib_entry_t *cover;
+
+    if (FIB_NODE_INDEX_INVALID != src->u.interpose.fesi_cover)
+    {
+        /*
+         * remove the depednecy on the covering entry, if that's
+         * what was contributing the path-list
+         */
+        cover = fib_entry_get(src->u.interpose.fesi_cover);
+        fib_entry_cover_untrack(cover, src->u.interpose.fesi_sibling);
+        src->u.interpose.fesi_cover = FIB_NODE_INDEX_INVALID;
+    }
+    else
+    {
+        fib_entry_src_t *best_src;
+
+        best_src = fib_entry_src_rr_get_next_best(src, fib_entry);
+
+        if (best_src)
+        {
+            best_src->fes_flags &= ~FIB_ENTRY_SRC_FLAG_CONTRIBUTING;
+            /*
+             * there is another source for this entry. activate it so it
+             * can provide forwarding
+             */
+            FIB_ENTRY_SRC_VFT_INVOKE(best_src, fesv_deactivate,
+                                     (best_src, fib_entry));
+        }
+    }
+
+    fib_path_list_unlock(src->fes_pl);
+    src->fes_pl = FIB_NODE_INDEX_INVALID;
+    src->fes_entry_flags &= ~FIB_ENTRY_FLAGS_RR_INHERITED;
+}
+
+static int
+fib_entry_src_interpose_reactivate (fib_entry_src_t *src,
+                                    const fib_entry_t *fib_entry)
+{
+    fib_entry_src_interpose_deactivate(src, fib_entry);
+    return (fib_entry_src_interpose_activate(src, fib_entry));
+}
+
+static fib_entry_src_cover_res_t
+fib_entry_src_interpose_cover_change (fib_entry_src_t *src,
+                                      const fib_entry_t *fib_entry)
+{
+    fib_entry_src_cover_res_t res = {
+       .install = !0,
+       .bw_reason = FIB_NODE_BW_REASON_FLAG_NONE,
+    };
+
+    if (FIB_NODE_INDEX_INVALID == src->u.interpose.fesi_cover)
+    {
+       /*
+        * the source may be added, but it is not active
+        * if it is not tracking the cover.
+        */
+       return (res);
+    }
+
+    /*
+     * this function is called when this entry's cover has a more specific
+     * entry inserted benaeth it. That does not necessarily mean that this
+     * entry is covered by the new prefix. check that
+     */
+    if (src->u.interpose.fesi_cover !=
+        fib_table_get_less_specific(fib_entry->fe_fib_index,
+                                    &fib_entry->fe_prefix))
+    {
+       fib_entry_src_interpose_deactivate(src, fib_entry);
+       fib_entry_src_interpose_activate(src, fib_entry);
+
+       /*
+        * dependent children need to re-resolve to the new forwarding info
+        */
+       res.bw_reason = FIB_NODE_BW_REASON_FLAG_EVALUATE;
+    }
+    return (res);
+}
+
+static void
+fib_entry_src_interpose_add (fib_entry_src_t *src,
+                             const fib_entry_t *entry,
+                             fib_entry_flag_t flags,
+                             dpo_proto_t proto,
+                             const dpo_id_t *dpo)
+{
+    dpo_copy(&src->u.interpose.fesi_dpo, dpo);
+}
+
+static void
+fib_entry_src_interpose_remove (fib_entry_src_t *src)
+{
+    dpo_reset(&src->u.interpose.fesi_dpo);
+}
+
+static void
+fib_entry_src_interpose_set_data (fib_entry_src_t *src,
+                                  const fib_entry_t *fib_entry,
+                                  const void *data)
+{
+    const dpo_id_t *dpo = data;
+
+    dpo_copy(&src->u.interpose.fesi_dpo, dpo);
+}
+
+/**
+ * Contribute forwarding to interpose in the chain
+ */
+const dpo_id_t* fib_entry_src_interpose_contribute(const fib_entry_src_t *src,
+                                                   const fib_entry_t *fib_entry)
+{
+    return (&src->u.interpose.fesi_dpo);
+}
+
+static void
+fib_entry_src_interpose_copy (const fib_entry_src_t *orig_src,
+                              const fib_entry_t *fib_entry,
+                              fib_entry_src_t *copy_src)
+{
+    copy_src->u.interpose.fesi_cover = orig_src->u.interpose.fesi_cover;
+
+    if (FIB_NODE_INDEX_INVALID != copy_src->u.interpose.fesi_cover)
+    {
+        fib_entry_t *cover;
+
+        cover = fib_entry_get(orig_src->u.interpose.fesi_cover);
+        copy_src->u.interpose.fesi_sibling =
+            fib_entry_cover_track(cover, fib_entry_get_index(fib_entry));
+    }
+
+    dpo_copy(&copy_src->u.interpose.fesi_dpo,
+             &orig_src->u.interpose.fesi_dpo);
+}
+
+static void
+fib_entry_src_interpose_flag_change (fib_entry_src_t *src,
+                                     const fib_entry_t *fib_entry,
+                                     fib_entry_flag_t new_flags)
+{
+    if (!(new_flags & FIB_ENTRY_FLAG_INTERPOSE))
+    {
+        /*
+         * stop tracking the source contributing forwarding
+         * and reset the interposer DPO
+         */
+        fib_entry_src_interpose_deactivate(src, fib_entry);
+        fib_entry_src_interpose_deinit(src);
+    }
+}
+
+static u8*
+fib_entry_src_interpose_format (fib_entry_src_t *src,
+                                u8* s)
+{
+    s = format(s, " cover:%d interpose:\n%U%U",
+               src->u.interpose.fesi_cover,
+               format_white_space, 6,
+               format_dpo_id, &src->u.interpose.fesi_dpo, 8);
+
+    return (s);
+}
+
+const static fib_entry_src_vft_t interpose_src_vft = {
+    .fesv_init = fib_entry_src_interpose_init,
+    .fesv_deinit = fib_entry_src_interpose_deinit,
+    .fesv_activate = fib_entry_src_interpose_activate,
+    .fesv_reactivate = fib_entry_src_interpose_reactivate,
+    .fesv_deactivate = fib_entry_src_interpose_deactivate,
+    .fesv_cover_change = fib_entry_src_interpose_cover_change,
+    .fesv_cover_update = fib_entry_src_rr_cover_update,
+    .fesv_format = fib_entry_src_interpose_format,
+    .fesv_add = fib_entry_src_interpose_add,
+    .fesv_remove = fib_entry_src_interpose_remove,
+    .fesv_contribute_interpose = fib_entry_src_interpose_contribute,
+    .fesv_set_data = fib_entry_src_interpose_set_data,
+    .fesv_copy = fib_entry_src_interpose_copy,
+    .fesv_flags_change = fib_entry_src_interpose_flag_change,
+};
+
+void
+fib_entry_src_interpose_register (void)
+{
+    fib_entry_src_register(FIB_SOURCE_INTERPOSE, &interpose_src_vft);
+}