src/vnet/fib/fib_attached_export.c - fdio/vpp - Gitiles

 /*
  * 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/fib/fib_entry.h>
 #include <vnet/fib/fib_table.h>

 #include <vnet/fib/fib_attached_export.h>
 #include <vnet/fib/fib_entry_cover.h>
 #include <vnet/fib/fib_entry_src.h>
 #include <vnet/fib/fib_entry_delegate.h>
 #include <vnet/dpo/drop_dpo.h>

 /**
  * A description of the need to import routes from the export table
  */
 typedef struct fib_ae_import_t_
 {
     /**
      * The entry in the export table that this importer
      * is importing covereds from
      */
     fib_node_index_t faei_export_entry;

     /**
      * The attached entry in the import table
      */
     fib_node_index_t faei_import_entry;
     /**
      * the sibling index on the cover
      */
     u32 faei_export_sibling;

     /**
      * The index of the exporter tracker. Not set if the
      * export entry is not valid for export
      */
     fib_node_index_t faei_exporter;

     /**
      * A vector/list of imported entry indicies
      */
     fib_node_index_t *faei_importeds;

     /**
      * The FIB index and prefix we are tracking
      */
     fib_node_index_t faei_export_fib;
     fib_prefix_t faei_prefix;

     /**
      * The FIB index we are importing into
      */
     fib_node_index_t faei_import_fib;
 } fib_ae_import_t;

 /**
  * A description of the need to export routes to one or more export tables
  */
 typedef struct fib_ae_export_t_ {
     /**
      * The vector/list of import tracker indicies
      */
     fib_node_index_t *faee_importers;

     /**
      * THe connected entry this export is acting on behalf of
      */
     fib_node_index_t faee_ei;

     /**
      * Reference counting locks
      */
     u32 faee_locks;
 } fib_ae_export_t;

 /*
  * memory pools for the importers and exporters
  */
 static fib_ae_import_t *fib_ae_import_pool;
 static fib_ae_export_t *fib_ae_export_pool;

 static fib_ae_export_t *
 fib_entry_ae_add_or_lock (fib_node_index_t connected)
 {
     fib_entry_delegate_t *fed;
     fib_ae_export_t *export;
     fib_entry_t *entry;

     entry = fib_entry_get(connected);
     fed = fib_entry_delegate_find(entry,
                                   FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

     if (NULL == fed)
     {
         fed = fib_entry_delegate_find_or_add(entry,
                                              FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
 	pool_get_zero(fib_ae_export_pool, export);

 	fed->fd_index = (export - fib_ae_export_pool);
 	export->faee_ei = connected;
     }
     else
     {
 	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);
     }

     export->faee_locks++;

     return (export);
 }

 static void
 fib_entry_import_remove (fib_ae_import_t *import,
 			 fib_node_index_t entry_index)
 {
     u32 index;

     /*
      * find the index in the vector of the entry we are removing
      */
     index = vec_search(import->faei_importeds, entry_index);

     if (index < vec_len(import->faei_importeds))
     {
 	/*
 	 * this is an entry that was previously imported
 	 */
 	fib_table_entry_special_remove(import->faei_import_fib,
 				       fib_entry_get_prefix(entry_index),
 				       FIB_SOURCE_AE);

 	fib_entry_unlock(entry_index);
 	vec_del1(import->faei_importeds, index);
     }
 }

 static void
 fib_entry_import_add (fib_ae_import_t *import,
 		      fib_node_index_t entry_index)
 {
     fib_node_index_t *existing;
     fib_prefix_t prefix;

     /*
      * ensure we only add the exported entry once, since
      * sourcing prefixes in the table is reference counted
      */
     vec_foreach(existing, import->faei_importeds)
     {
 	if (*existing == entry_index)
 	{
 	    return;
 	}
     }

     /*
      * this is the first time this export entry has been imported
      * Add it to the import FIB and to the list of importeds.
      * make a copy of the prefix in case the underlying entry reallocs.
      */
     fib_prefix_copy(&prefix, fib_entry_get_prefix(entry_index));

     /*
      * don't import entries that have the same prefix the import entry
      */
     if (0 != fib_prefix_cmp(&prefix, &import->faei_prefix))
     {
         const dpo_id_t *dpo;

         dpo = fib_entry_contribute_ip_forwarding(entry_index);

         if (dpo_id_is_valid(dpo) && !dpo_is_drop(dpo))
         {
             fib_table_entry_special_dpo_add(import->faei_import_fib,
                                             &prefix,
                                             FIB_SOURCE_AE,
                                             (fib_entry_get_flags(entry_index) |
                                              FIB_ENTRY_FLAG_EXCLUSIVE),
                                             load_balance_get_bucket(dpo->dpoi_index, 0));

             fib_entry_lock(entry_index);
             vec_add1(import->faei_importeds, entry_index);
         }
         /*
          * else
          *   the entry currently has no valid forwarding. when it
          * does it will export itself
          */
     }
 }

 /**
  * Call back when walking a connected prefix's covered prefixes for import
  */
 static walk_rc_t
 fib_entry_covered_walk_import (fib_entry_t *cover,
 			       fib_node_index_t covered,
 			       void *ctx)
 {
     fib_ae_import_t *import = ctx;

     fib_entry_import_add(import, covered);

     return (WALK_CONTINUE);
 }

 /*
  * fib_entry_ae_import_add
  *
  * Add an importer to a connected entry
  */
 static void
 fib_ae_export_import_add (fib_ae_export_t *export,
 			  fib_ae_import_t *import)
 {
     fib_entry_t *entry;

     import->faei_exporter = (export - fib_ae_export_pool);
     entry = fib_entry_get(export->faee_ei);

     fib_entry_cover_walk(entry,
 			 fib_entry_covered_walk_import,
 			 import);
 }

 void
 fib_attached_export_import (fib_entry_t *fib_entry,
 			    fib_node_index_t export_fib)
 {
     fib_entry_delegate_t *fed;
     fib_ae_import_t *import;
     fib_node_index_t fei;

     /*
      * save index for later post-realloc retrieval
      */
     fei = fib_entry_get_index(fib_entry);

     pool_get_zero(fib_ae_import_pool, import);

     import->faei_import_fib = fib_entry->fe_fib_index;
     import->faei_export_fib = export_fib;
     import->faei_prefix = fib_entry->fe_prefix;
     import->faei_import_entry = fib_entry_get_index(fib_entry);
     import->faei_export_sibling = ~0;
     import->faei_exporter = FIB_NODE_INDEX_INVALID;

     /*
      * do an exact match in the export table
      */
     import->faei_export_entry =
 	fib_table_lookup_exact_match(import->faei_export_fib,
 				     &import->faei_prefix);

     if (FIB_NODE_INDEX_INVALID == import->faei_export_entry)
     {
 	/*
 	 * no exact matching entry in the export table. can't be good.
 	 * track the next best thing
 	 */
 	import->faei_export_entry =
 	    fib_table_lookup(import->faei_export_fib,
 			     &import->faei_prefix);
     }
     else
     {
 	/*
 	 * found the entry in the export table. import the
 	 * the prefixes that it covers.
 	 * only if the prefix found in the export FIB really is
 	 * attached do we want to import its covered
 	 */
 	if (FIB_ENTRY_FLAG_ATTACHED &
 	    fib_entry_get_flags_i(fib_entry_get(import->faei_export_entry)))
 	{
 	    fib_ae_export_t *export;

 	    export = fib_entry_ae_add_or_lock(import->faei_export_entry);
 	    vec_add1(export->faee_importers, (import - fib_ae_import_pool));
 	    fib_ae_export_import_add(export, import);
 	}
     }

     /*
      * track the entry in the export table so we can update appropriately
      * when it changes.
      * Exporting prefixes will have allocated new fib_entry_t objects, so the pool
      * may have realloc'd.
      */
     fib_entry = fib_entry_get(fei);
     import->faei_export_sibling =
 	fib_entry_cover_track(fib_entry_get(import->faei_export_entry), fei);

     fed = fib_entry_delegate_find_or_add(fib_entry,
                                          FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);
     fed->fd_index = (import - fib_ae_import_pool);
 }

 /**
  * \brief All the imported entries need to be purged
  */
 void
 fib_attached_export_purge (fib_entry_t *fib_entry)
 {
     fib_entry_delegate_t *fed;

     fed = fib_entry_delegate_find(fib_entry,
                                   FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);

     if (NULL != fed)
     {
  	fib_node_index_t *import_index;
 	fib_entry_t *export_entry;
 	fib_ae_import_t *import;
 	fib_ae_export_t *export;

 	import = pool_elt_at_index(fib_ae_import_pool, fed->fd_index);

 	/*
 	 * remove each imported entry
 	 */
 	vec_foreach(import_index, import->faei_importeds)
 	{
 	    fib_table_entry_delete(import->faei_import_fib,
 				   fib_entry_get_prefix(*import_index),
 				   FIB_SOURCE_AE);
 	    fib_entry_unlock(*import_index);
 	}
 	vec_free(import->faei_importeds);

 	/*
 	 * stop tracking the export entry
 	 */
 	if (~0 != import->faei_export_sibling)
 	{
 	    fib_entry_cover_untrack(fib_entry_get(import->faei_export_entry),
 				    import->faei_export_sibling);
 	}
 	import->faei_export_sibling = ~0;

 	/*
 	 * remove this import tracker from the export's list,
 	 * if it is attached to one. It won't be in the case the tracked
 	 * export entry is not an attached exact match.
 	 */
 	if (FIB_NODE_INDEX_INVALID != import->faei_exporter)
 	{
             fib_entry_delegate_t *fed;

 	    export_entry = fib_entry_get(import->faei_export_entry);

             fed = fib_entry_delegate_find(export_entry,
                                           FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
             ALWAYS_ASSERT(NULL != fed);

 	    export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

 	    u32 index = vec_search(export->faee_importers,
 				   (import - fib_ae_import_pool));

 	    ASSERT(index < vec_len(export->faee_importers));
 	    vec_del1(export->faee_importers, index);

 	    /*
 	     * free the exporter if there are no longer importers
 	     */
 	    if (0 == --export->faee_locks)
 	    {
                 vec_free (export->faee_importers);
 		pool_put(fib_ae_export_pool, export);
                 fib_entry_delegate_remove(export_entry,
                                           FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
 	    }
 	}

 	/*
 	 * free the import tracker
 	 */
 	pool_put(fib_ae_import_pool, import);
         fib_entry_delegate_remove(fib_entry,
                                   FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);
     }
 }

 void
 fib_attached_export_covered_added (fib_entry_t *cover,
 				   fib_node_index_t covered)
 {
     fib_entry_delegate_t *fed;

     fed = fib_entry_delegate_find(cover,
                                   FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

     if (NULL != fed)
     {
 	/*
 	 * the covering prefix is exporting to other tables
 	 */
  	fib_node_index_t *import_index;
 	fib_ae_import_t *import;
 	fib_ae_export_t *export;

 	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

 	/*
 	 * export the covered entry to each of the importers
 	 */
 	vec_foreach(import_index, export->faee_importers)
 	{
 	    import = pool_elt_at_index(fib_ae_import_pool, *import_index);

 	    fib_entry_import_add(import, covered);
 	}
     }
 }

 void
 fib_attached_export_covered_removed (fib_entry_t *cover,
 				     fib_node_index_t covered)
 {
     fib_entry_delegate_t *fed;

     fed = fib_entry_delegate_find(cover,
                                   FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

     if (NULL != fed)
     {
 	/*
 	 * the covering prefix is exporting to other tables
 	 */
  	fib_node_index_t *import_index;
 	fib_ae_import_t *import;
 	fib_ae_export_t *export;

 	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

 	/*
 	 * remove the covered entry from each of the importers
 	 */
 	vec_foreach(import_index, export->faee_importers)
 	{
 	    import = pool_elt_at_index(fib_ae_import_pool, *import_index);

 	    fib_entry_import_remove(import, covered);
 	}
     }
 }

 static void
 fib_attached_export_cover_modified_i (fib_entry_t *fib_entry)
 {
     fib_entry_delegate_t *fed;

     fed = fib_entry_delegate_find(fib_entry,
                                   FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);

     if (NULL != fed)
     {
 	fib_ae_import_t *import;
 	u32 export_fib;

 	/*
 	 * safe the temporaries we need from the existing import
 	 * since it will be toast after the purge.
 	 */
 	import = pool_elt_at_index(fib_ae_import_pool, fed->fd_index);
 	export_fib = import->faei_export_fib;

 	/*
 	 * keep it simple. purge anything that was previously imported.
 	 * then re-evaluate the need to import.
 	 */
 	fib_attached_export_purge(fib_entry);
 	fib_attached_export_import(fib_entry, export_fib);
     }
 }

 /**
  * \brief If this entry is tracking a cover (in another table)
  *        then that cover has changed. re-evaluate import.
  */
 void
 fib_attached_export_cover_change (fib_entry_t *fib_entry)
 {
     fib_attached_export_cover_modified_i(fib_entry);
 }

 /**
  * \brief If this entry is tracking a cover (in another table)
  *        then that cover has been updated. re-evaluate import.
  */
 void
 fib_attached_export_cover_update (fib_entry_t *fib_entry)
 {
     fib_attached_export_cover_modified_i(fib_entry);
 }

 u8*
 fib_ae_import_format (fib_node_index_t impi,
 		      u8* s)
 {
     fib_node_index_t *index;
     fib_ae_import_t *import;

     import = pool_elt_at_index(fib_ae_import_pool, impi);

     s = format(s, "\n  Attached-Import:%d:[", (import - fib_ae_import_pool));
     s = format(s, "export-prefix:%U ", format_fib_prefix, &import->faei_prefix);
     s = format(s, "export-entry:%d ", import->faei_export_entry);
     s = format(s, "export-sibling:%d ", import->faei_export_sibling);
     s = format(s, "exporter:%d ", import->faei_exporter);
     s = format(s, "export-fib:%d ", import->faei_export_fib);

     s = format(s, "import-entry:%d ", import->faei_import_entry);
     s = format(s, "import-fib:%d ", import->faei_import_fib);

     s = format(s, "importeds:[");
     vec_foreach(index, import->faei_importeds)
     {
         s = format(s, "%d, ", *index);
     }
     s = format(s, "]]");

     return (s);
 }

 u8*
 fib_ae_export_format (fib_node_index_t expi,
 		      u8* s)
 {
     fib_node_index_t *index;
     fib_ae_export_t *export;

     export = pool_elt_at_index(fib_ae_export_pool, expi);

     s = format(s, "\n  Attached-Export:%d:[", (export - fib_ae_export_pool));
     s = format(s, "export-entry:%d ", export->faee_ei);

     s = format(s, "importers:[");
     vec_foreach(index, export->faee_importers)
     {
         s = format(s, "%d, ", *index);
     }
     s = format(s, "]]");

     return (s);
 }
	/*
	* 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/fib/fib_entry.h>
	#include <vnet/fib/fib_table.h>

	#include <vnet/fib/fib_attached_export.h>
	#include <vnet/fib/fib_entry_cover.h>
	#include <vnet/fib/fib_entry_src.h>
	#include <vnet/fib/fib_entry_delegate.h>
	#include <vnet/dpo/drop_dpo.h>

	/**
	* A description of the need to import routes from the export table
	*/
	typedef struct fib_ae_import_t_
	{
	/**
	* The entry in the export table that this importer
	* is importing covereds from
	*/
	fib_node_index_t faei_export_entry;

	/**
	* The attached entry in the import table
	*/
	fib_node_index_t faei_import_entry;
	/**
	* the sibling index on the cover
	*/
	u32 faei_export_sibling;

	/**
	* The index of the exporter tracker. Not set if the
	* export entry is not valid for export
	*/
	fib_node_index_t faei_exporter;

	/**
	* A vector/list of imported entry indicies
	*/
	fib_node_index_t *faei_importeds;

	/**
	* The FIB index and prefix we are tracking
	*/
	fib_node_index_t faei_export_fib;
	fib_prefix_t faei_prefix;

	/**
	* The FIB index we are importing into
	*/
	fib_node_index_t faei_import_fib;
	} fib_ae_import_t;

	/**
	* A description of the need to export routes to one or more export tables
	*/
	typedef struct fib_ae_export_t_ {
	/**
	* The vector/list of import tracker indicies
	*/
	fib_node_index_t *faee_importers;

	/**
	* THe connected entry this export is acting on behalf of
	*/
	fib_node_index_t faee_ei;

	/**
	* Reference counting locks
	*/
	u32 faee_locks;
	} fib_ae_export_t;

	/*
	* memory pools for the importers and exporters
	*/
	static fib_ae_import_t *fib_ae_import_pool;
	static fib_ae_export_t *fib_ae_export_pool;

	static fib_ae_export_t *
	fib_entry_ae_add_or_lock (fib_node_index_t connected)
	{
	fib_entry_delegate_t *fed;
	fib_ae_export_t *export;
	fib_entry_t *entry;

	entry = fib_entry_get(connected);
	fed = fib_entry_delegate_find(entry,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

	if (NULL == fed)
	{
	fed = fib_entry_delegate_find_or_add(entry,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
	pool_get_zero(fib_ae_export_pool, export);

	fed->fd_index = (export - fib_ae_export_pool);
	export->faee_ei = connected;
	}
	else
	{
	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);
	}

	export->faee_locks++;

	return (export);
	}

	static void
	fib_entry_import_remove (fib_ae_import_t *import,
	fib_node_index_t entry_index)
	{
	u32 index;

	/*
	* find the index in the vector of the entry we are removing
	*/
	index = vec_search(import->faei_importeds, entry_index);

	if (index < vec_len(import->faei_importeds))
	{
	/*
	* this is an entry that was previously imported
	*/
	fib_table_entry_special_remove(import->faei_import_fib,
	fib_entry_get_prefix(entry_index),
	FIB_SOURCE_AE);

	fib_entry_unlock(entry_index);
	vec_del1(import->faei_importeds, index);
	}
	}

	static void
	fib_entry_import_add (fib_ae_import_t *import,
	fib_node_index_t entry_index)
	{
	fib_node_index_t *existing;
	fib_prefix_t prefix;

	/*
	* ensure we only add the exported entry once, since
	* sourcing prefixes in the table is reference counted
	*/
	vec_foreach(existing, import->faei_importeds)
	{
	if (*existing == entry_index)
	{
	return;
	}
	}

	/*
	* this is the first time this export entry has been imported
	* Add it to the import FIB and to the list of importeds.
	* make a copy of the prefix in case the underlying entry reallocs.
	*/
	fib_prefix_copy(&prefix, fib_entry_get_prefix(entry_index));

	/*
	* don't import entries that have the same prefix the import entry
	*/
	if (0 != fib_prefix_cmp(&prefix, &import->faei_prefix))
	{
	const dpo_id_t *dpo;

	dpo = fib_entry_contribute_ip_forwarding(entry_index);

	if (dpo_id_is_valid(dpo) && !dpo_is_drop(dpo))
	{
	fib_table_entry_special_dpo_add(import->faei_import_fib,
	&prefix,
	FIB_SOURCE_AE,
	(fib_entry_get_flags(entry_index) \|
	FIB_ENTRY_FLAG_EXCLUSIVE),
	load_balance_get_bucket(dpo->dpoi_index, 0));

	fib_entry_lock(entry_index);
	vec_add1(import->faei_importeds, entry_index);
	}
	/*
	* else
	* the entry currently has no valid forwarding. when it
	* does it will export itself
	*/
	}
	}

	/**
	* Call back when walking a connected prefix's covered prefixes for import
	*/
	static walk_rc_t
	fib_entry_covered_walk_import (fib_entry_t *cover,
	fib_node_index_t covered,
	void *ctx)
	{
	fib_ae_import_t *import = ctx;

	fib_entry_import_add(import, covered);

	return (WALK_CONTINUE);
	}

	/*
	* fib_entry_ae_import_add
	*
	* Add an importer to a connected entry
	*/
	static void
	fib_ae_export_import_add (fib_ae_export_t *export,
	fib_ae_import_t *import)
	{
	fib_entry_t *entry;

	import->faei_exporter = (export - fib_ae_export_pool);
	entry = fib_entry_get(export->faee_ei);

	fib_entry_cover_walk(entry,
	fib_entry_covered_walk_import,
	import);
	}

	void
	fib_attached_export_import (fib_entry_t *fib_entry,
	fib_node_index_t export_fib)
	{
	fib_entry_delegate_t *fed;
	fib_ae_import_t *import;
	fib_node_index_t fei;

	/*
	* save index for later post-realloc retrieval
	*/
	fei = fib_entry_get_index(fib_entry);

	pool_get_zero(fib_ae_import_pool, import);

	import->faei_import_fib = fib_entry->fe_fib_index;
	import->faei_export_fib = export_fib;
	import->faei_prefix = fib_entry->fe_prefix;
	import->faei_import_entry = fib_entry_get_index(fib_entry);
	import->faei_export_sibling = ~0;
	import->faei_exporter = FIB_NODE_INDEX_INVALID;

	/*
	* do an exact match in the export table
	*/
	import->faei_export_entry =
	fib_table_lookup_exact_match(import->faei_export_fib,
	&import->faei_prefix);

	if (FIB_NODE_INDEX_INVALID == import->faei_export_entry)
	{
	/*
	* no exact matching entry in the export table. can't be good.
	* track the next best thing
	*/
	import->faei_export_entry =
	fib_table_lookup(import->faei_export_fib,
	&import->faei_prefix);
	}
	else
	{
	/*
	* found the entry in the export table. import the
	* the prefixes that it covers.
	* only if the prefix found in the export FIB really is
	* attached do we want to import its covered
	*/
	if (FIB_ENTRY_FLAG_ATTACHED &
	fib_entry_get_flags_i(fib_entry_get(import->faei_export_entry)))
	{
	fib_ae_export_t *export;

	export = fib_entry_ae_add_or_lock(import->faei_export_entry);
	vec_add1(export->faee_importers, (import - fib_ae_import_pool));
	fib_ae_export_import_add(export, import);
	}
	}

	/*
	* track the entry in the export table so we can update appropriately
	* when it changes.
	* Exporting prefixes will have allocated new fib_entry_t objects, so the pool
	* may have realloc'd.
	*/
	fib_entry = fib_entry_get(fei);
	import->faei_export_sibling =
	fib_entry_cover_track(fib_entry_get(import->faei_export_entry), fei);

	fed = fib_entry_delegate_find_or_add(fib_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);
	fed->fd_index = (import - fib_ae_import_pool);
	}

	/**
	* \brief All the imported entries need to be purged
	*/
	void
	fib_attached_export_purge (fib_entry_t *fib_entry)
	{
	fib_entry_delegate_t *fed;

	fed = fib_entry_delegate_find(fib_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);

	if (NULL != fed)
	{
	fib_node_index_t *import_index;
	fib_entry_t *export_entry;
	fib_ae_import_t *import;
	fib_ae_export_t *export;

	import = pool_elt_at_index(fib_ae_import_pool, fed->fd_index);

	/*
	* remove each imported entry
	*/
	vec_foreach(import_index, import->faei_importeds)
	{
	fib_table_entry_delete(import->faei_import_fib,
	fib_entry_get_prefix(*import_index),
	FIB_SOURCE_AE);
	fib_entry_unlock(*import_index);
	}
	vec_free(import->faei_importeds);

	/*
	* stop tracking the export entry
	*/
	if (~0 != import->faei_export_sibling)
	{
	fib_entry_cover_untrack(fib_entry_get(import->faei_export_entry),
	import->faei_export_sibling);
	}
	import->faei_export_sibling = ~0;

	/*
	* remove this import tracker from the export's list,
	* if it is attached to one. It won't be in the case the tracked
	* export entry is not an attached exact match.
	*/
	if (FIB_NODE_INDEX_INVALID != import->faei_exporter)
	{
	fib_entry_delegate_t *fed;

	export_entry = fib_entry_get(import->faei_export_entry);

	fed = fib_entry_delegate_find(export_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
	ALWAYS_ASSERT(NULL != fed);

	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

	u32 index = vec_search(export->faee_importers,
	(import - fib_ae_import_pool));

	ASSERT(index < vec_len(export->faee_importers));
	vec_del1(export->faee_importers, index);

	/*
	* free the exporter if there are no longer importers
	*/
	if (0 == --export->faee_locks)
	{
	vec_free (export->faee_importers);
	pool_put(fib_ae_export_pool, export);
	fib_entry_delegate_remove(export_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);
	}
	}

	/*
	* free the import tracker
	*/
	pool_put(fib_ae_import_pool, import);
	fib_entry_delegate_remove(fib_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);
	}
	}

	void
	fib_attached_export_covered_added (fib_entry_t *cover,
	fib_node_index_t covered)
	{
	fib_entry_delegate_t *fed;

	fed = fib_entry_delegate_find(cover,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

	if (NULL != fed)
	{
	/*
	* the covering prefix is exporting to other tables
	*/
	fib_node_index_t *import_index;
	fib_ae_import_t *import;
	fib_ae_export_t *export;

	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

	/*
	* export the covered entry to each of the importers
	*/
	vec_foreach(import_index, export->faee_importers)
	{
	import = pool_elt_at_index(fib_ae_import_pool, *import_index);

	fib_entry_import_add(import, covered);
	}
	}
	}

	void
	fib_attached_export_covered_removed (fib_entry_t *cover,
	fib_node_index_t covered)
	{
	fib_entry_delegate_t *fed;

	fed = fib_entry_delegate_find(cover,
	FIB_ENTRY_DELEGATE_ATTACHED_EXPORT);

	if (NULL != fed)
	{
	/*
	* the covering prefix is exporting to other tables
	*/
	fib_node_index_t *import_index;
	fib_ae_import_t *import;
	fib_ae_export_t *export;

	export = pool_elt_at_index(fib_ae_export_pool, fed->fd_index);

	/*
	* remove the covered entry from each of the importers
	*/
	vec_foreach(import_index, export->faee_importers)
	{
	import = pool_elt_at_index(fib_ae_import_pool, *import_index);

	fib_entry_import_remove(import, covered);
	}
	}
	}

	static void
	fib_attached_export_cover_modified_i (fib_entry_t *fib_entry)
	{
	fib_entry_delegate_t *fed;

	fed = fib_entry_delegate_find(fib_entry,
	FIB_ENTRY_DELEGATE_ATTACHED_IMPORT);

	if (NULL != fed)
	{
	fib_ae_import_t *import;
	u32 export_fib;

	/*
	* safe the temporaries we need from the existing import
	* since it will be toast after the purge.
	*/
	import = pool_elt_at_index(fib_ae_import_pool, fed->fd_index);
	export_fib = import->faei_export_fib;

	/*
	* keep it simple. purge anything that was previously imported.
	* then re-evaluate the need to import.
	*/
	fib_attached_export_purge(fib_entry);
	fib_attached_export_import(fib_entry, export_fib);
	}
	}

	/**
	* \brief If this entry is tracking a cover (in another table)
	* then that cover has changed. re-evaluate import.
	*/
	void
	fib_attached_export_cover_change (fib_entry_t *fib_entry)
	{
	fib_attached_export_cover_modified_i(fib_entry);
	}

	/**
	* \brief If this entry is tracking a cover (in another table)
	* then that cover has been updated. re-evaluate import.
	*/
	void
	fib_attached_export_cover_update (fib_entry_t *fib_entry)
	{
	fib_attached_export_cover_modified_i(fib_entry);
	}

	u8*
	fib_ae_import_format (fib_node_index_t impi,
	u8* s)
	{
	fib_node_index_t *index;
	fib_ae_import_t *import;

	import = pool_elt_at_index(fib_ae_import_pool, impi);

	s = format(s, "\n Attached-Import:%d:[", (import - fib_ae_import_pool));
	s = format(s, "export-prefix:%U ", format_fib_prefix, &import->faei_prefix);
	s = format(s, "export-entry:%d ", import->faei_export_entry);
	s = format(s, "export-sibling:%d ", import->faei_export_sibling);
	s = format(s, "exporter:%d ", import->faei_exporter);
	s = format(s, "export-fib:%d ", import->faei_export_fib);

	s = format(s, "import-entry:%d ", import->faei_import_entry);
	s = format(s, "import-fib:%d ", import->faei_import_fib);

	s = format(s, "importeds:[");
	vec_foreach(index, import->faei_importeds)
	{
	s = format(s, "%d, ", *index);
	}
	s = format(s, "]]");

	return (s);
	}

	u8*
	fib_ae_export_format (fib_node_index_t expi,
	u8* s)
	{
	fib_node_index_t *index;
	fib_ae_export_t *export;

	export = pool_elt_at_index(fib_ae_export_pool, expi);

	s = format(s, "\n Attached-Export:%d:[", (export - fib_ae_export_pool));
	s = format(s, "export-entry:%d ", export->faee_ei);

	s = format(s, "importers:[");
	vec_foreach(index, export->faee_importers)
	{
	s = format(s, "%d, ", *index);
	}
	s = format(s, "]]");

	return (s);
	}