bgpd: Code to handle BGP aggregate's as-path.

With this commit:
1) 'struct bgp_aggregate' is moved to bgp_route.h from bgp_route.c
2) Hashes to accommodate the as-path, communities, extended-communities and
   large-communities attributes of all the routes aggregated by an
   aggregate route is introduced in 'struct bgp_aggregate'.
3) Place-holders for the aggregate route's as-path, communities,
   extended-communities and large-communities attributes are introduced in
   'struct bgp_aggregate'.
4) The code to manage the as-path of the routes that are aggregatable under
   a configured aggregate-address is introduced.
5) The code to compute the aggregate-route's as-path is introduced.

Signed-off-by: NaveenThanikachalam <nthanikachal@vmware.com>

bgpd/bgp_aspath.c

@@ -212,6 +212,9 @@ static struct assegment *assegment_append_asns(struct assegment *seg,
 {
 	as_t *newas;
 
+	if (!seg)
+		return seg;
+
 	newas = XREALLOC(MTYPE_AS_SEG_DATA, seg->as,
 			 ASSEGMENT_DATA_SIZE(seg->length + num, 1));
 
@@ -1372,7 +1375,8 @@ static struct aspath *aspath_merge(struct aspath *as1, struct aspath *as2)
 	while (last && last->next)
 		last = last->next;
 
-	last->next = as2->segments;
+	if (last)
+		last->next = as2->segments;
 	as2->segments = new;
 	aspath_str_update(as2, false);
 	return as2;
@@ -1447,7 +1451,8 @@ struct aspath *aspath_prepend(struct aspath *as1, struct aspath *as2)
 		 * bypass the merged seg2, and attach any chain after it
 		 * to chain descending from as2's head
 		 */
-		as2segtail->next = as2seghead->next;
+		if (as2segtail)
+			as2segtail->next = as2seghead->next;
 
 		/* as2->segments is now referenceless and useless */
 		assegment_free(as2seghead);
@@ -2096,3 +2101,110 @@ void aspath_print_all_vty(struct vty *vty)
 				       void *))aspath_show_all_iterator,
 		     vty);
 }
+
+static struct aspath *bgp_aggr_aspath_lookup(struct bgp_aggregate *aggregate,
+					     struct aspath *aspath)
+{
+	return hash_lookup(aggregate->aspath_hash, aspath);
+}
+
+static void *bgp_aggr_aspath_hash_alloc(void *p)
+{
+	struct aspath *ref = (struct aspath *)p;
+	struct aspath *aspath = NULL;
+
+	aspath = aspath_dup(ref);
+	return aspath;
+}
+
+static void bgp_aggr_aspath_prepare(struct hash_backet *hb, void *arg)
+{
+	struct aspath *asmerge = NULL;
+	struct aspath *hb_aspath = hb->data;
+	struct aspath **aggr_aspath = arg;
+
+	if (*aggr_aspath) {
+		asmerge = aspath_aggregate(*aggr_aspath, hb_aspath);
+		aspath_free(*aggr_aspath);
+		*aggr_aspath = asmerge;
+	} else
+		*aggr_aspath = aspath_dup(hb_aspath);
+}
+
+void bgp_aggr_aspath_remove(void *arg)
+{
+	struct aspath *aspath = arg;
+
+	aspath_free(aspath);
+}
+
+void bgp_compute_aggregate_aspath(struct bgp_aggregate *aggregate,
+				  struct aspath *aspath)
+{
+	struct aspath *aggr_aspath = NULL;
+
+	if ((aggregate == NULL) || (aspath == NULL))
+		return;
+
+	/* Create hash if not already created.
+	 */
+	if (aggregate->aspath_hash == NULL)
+		aggregate->aspath_hash = hash_create(
+					aspath_key_make, aspath_cmp,
+					"BGP Aggregator as-path hash");
+
+	aggr_aspath = bgp_aggr_aspath_lookup(aggregate, aspath);
+	if (aggr_aspath == NULL) {
+		/* Insert as-path into hash.
+		 */
+		aggr_aspath = hash_get(aggregate->aspath_hash, aspath,
+				       bgp_aggr_aspath_hash_alloc);
+
+		/* Compute aggregate's as-path.
+		 */
+		hash_iterate(aggregate->aspath_hash,
+			     bgp_aggr_aspath_prepare,
+			     &aggregate->aspath);
+	}
+
+	/* Increment refernce counter.
+	 */
+	aggr_aspath->refcnt++;
+}
+
+void bgp_remove_aspath_from_aggregate(struct bgp_aggregate *aggregate,
+				      struct aspath *aspath)
+{
+	struct aspath *aggr_aspath = NULL;
+	struct aspath *ret_aspath = NULL;
+
+	if ((aggregate == NULL) || (aspath == NULL))
+		return;
+
+	if (aggregate->aspath_hash == NULL)
+		return;
+
+	/* Look-up the aspath in the hash.
+	 */
+	aggr_aspath = bgp_aggr_aspath_lookup(aggregate, aspath);
+	if (aggr_aspath) {
+		aggr_aspath->refcnt--;
+
+		if (aggr_aspath->refcnt == 0) {
+			ret_aspath = hash_release(aggregate->aspath_hash,
+						  aggr_aspath);
+			aspath_free(ret_aspath);
+
+			/* Remove aggregate's old as-path.
+			 */
+			aspath_free(aggregate->aspath);
+			aggregate->aspath = NULL;
+
+			/* Compute aggregate's as-path.
+			 */
+			hash_iterate(aggregate->aspath_hash,
+				     bgp_aggr_aspath_prepare,
+				     &aggregate->aspath);
+		}
+	}
+}

bgpd/bgp_aspath.h

@@ -22,6 +22,7 @@
 #define _QUAGGA_BGP_ASPATH_H
 
 #include "lib/json.h"
+#include "bgpd/bgp_route.h"
 
 /* AS path segment type.  */
 #define AS_SET                       1
@@ -130,4 +131,10 @@ extern unsigned int aspath_has_as4(struct aspath *);
 /* For SNMP BGP4PATHATTRASPATHSEGMENT, might be useful for debug */
 extern uint8_t *aspath_snmp_pathseg(struct aspath *, size_t *);
 
+extern void bgp_compute_aggregate_aspath(struct bgp_aggregate *aggregate,
+					 struct aspath *aspath);
+extern void bgp_remove_aspath_from_aggregate(struct bgp_aggregate *aggregate,
+					     struct aspath *aspath);
+extern void bgp_aggr_aspath_remove(void *arg);
+
 #endif /* _QUAGGA_BGP_ASPATH_H */

bgpd/bgp_route.c

@@ -5513,33 +5513,6 @@ DEFPY(ipv6_bgp_network,
 		label_index ? (uint32_t)label_index : BGP_INVALID_LABEL_INDEX);
 }
 
-/* Aggreagete address:
-
-  advertise-map  Set condition to advertise attribute
-  as-set         Generate AS set path information
-  attribute-map  Set attributes of aggregate
-  route-map      Set parameters of aggregate
-  summary-only   Filter more specific routes from updates
-  suppress-map   Conditionally filter more specific routes from updates
-  <cr>
- */
-struct bgp_aggregate {
-	/* Summary-only flag. */
-	uint8_t summary_only;
-
-	/* AS set generation. */
-	uint8_t as_set;
-
-	/* Route-map for aggregated route. */
-	struct route_map *map;
-
-	/* Suppress-count. */
-	unsigned long count;
-
-	/* SAFI configuration. */
-	safi_t safi;
-};
-
 static struct bgp_aggregate *bgp_aggregate_new(void)
 {
 	return XCALLOC(MTYPE_BGP_AGGREGATE, sizeof(struct bgp_aggregate));

bgpd/bgp_route.h

@@ -272,6 +272,71 @@ struct bgp_static {
 	struct prefix gatewayIp;
 };
 
+/* Aggreagete address:
+ *
+ *  advertise-map  Set condition to advertise attribute
+ *  as-set         Generate AS set path information
+ *  attribute-map  Set attributes of aggregate
+ *  route-map      Set parameters of aggregate
+ *  summary-only   Filter more specific routes from updates
+ *  suppress-map   Conditionally filter more specific routes from updates
+ *  <cr>
+ */
+struct bgp_aggregate {
+	/* Summary-only flag. */
+	uint8_t summary_only;
+
+	/* AS set generation. */
+	uint8_t as_set;
+
+	/* Route-map for aggregated route. */
+	struct route_map *map;
+
+	/* Suppress-count. */
+	unsigned long count;
+
+	/* Count of routes of origin type incomplete under this aggregate. */
+	unsigned long incomplete_origin_count;
+
+	/* Count of routes of origin type egp under this aggregate. */
+	unsigned long egp_origin_count;
+
+	/* Hash containing the communities of all the
+	 * routes under this aggregate.
+	 */
+	struct hash *community_hash;
+
+	/* Hash containing the extended communities of all the
+	 * routes under this aggregate.
+	 */
+	struct hash *ecommunity_hash;
+
+	/* Hash containing the large communities of all the
+	 * routes under this aggregate.
+	 */
+	struct hash *lcommunity_hash;
+
+	/* Hash containing the AS-Path of all the
+	 * routes under this aggregate.
+	 */
+	struct hash *aspath_hash;
+
+	/* Aggregate route's community. */
+	struct community *community;
+
+	/* Aggregate route's extended community. */
+	struct ecommunity *ecommunity;
+
+	/* Aggregate route's large community. */
+	struct lcommunity *lcommunity;
+
+	/* Aggregate route's as-path. */
+	struct aspath *aspath;
+
+	/* SAFI configuration. */
+	safi_t safi;
+};
+
 #define BGP_NEXTHOP_AFI_FROM_NHLEN(nhlen)                                      \
 	((nhlen) < IPV4_MAX_BYTELEN                                            \
 		 ? 0                                                           \