ospfd: Core logic implementation.

Description:
Code changes involves.
	1. Count the no.of router LSAs received with DC options bit set,
	   supporting do not age(DNA).
	2. If no of router LSAs received with DC bit set is equal to total
	   no of LSAs in the router lsdb, then all the routers in the
	   area support do not age processing.
	3. Flood the self originated LSAs with DNA flag if all routers in the area
	   supports the feature.
	4. Stop aging of the LSAs recived with DO_NOT_AGE bit set from
	   other routers.
	5. Self originated DO_NOT_AGE lsas will still be aging in their own
	   database.

Signed-off-by: Manoj Naragund <mnaragund@vmware.com>

1 files changed, 137 insertions, 0 deletions

diff --git a/ospfd/ospf_flood.c b/ospfd/ospf_flood.c
index 4bbeee2d74..e3896b4535 100644
--- a/ospfd/ospf_flood.c
+++ b/ospfd/ospf_flood.c
@@ -50,6 +50,75 @@
 
 extern struct zclient *zclient;
 
+/** @brief Function to refresh type-5 and type-7 DNA
+ *	   LSAs when we receive an indication LSA.
+ *  @param Ospf instance.
+ *  @return Void.
+ */
+void ospf_refresh_dna_type5_and_type7_lsas(struct ospf *ospf)
+{
+	struct route_node *rn;
+	struct ospf_lsa *lsa = NULL;
+
+	LSDB_LOOP (EXTERNAL_LSDB(ospf), rn, lsa)
+		if (IS_LSA_SELF(lsa) &&
+		    CHECK_FLAG(lsa->data->ls_age, DO_NOT_AGE))
+			ospf_lsa_refresh(ospf, lsa);
+
+	LSDB_LOOP (NSSA_LSDB(ospf), rn, lsa)
+		if (IS_LSA_SELF(lsa) &&
+		    CHECK_FLAG(lsa->data->ls_age, DO_NOT_AGE))
+			ospf_lsa_refresh(ospf, lsa);
+}
+
+/** @brief Function to update area flood reduction states.
+ *  @param area pointer.
+ *  @return Void.
+ */
+void ospf_area_update_fr_state(struct ospf_area *area)
+{
+	unsigned int count_router_lsas = 0;
+
+	if (area == NULL)
+		return;
+
+	count_router_lsas =
+		(unsigned int)(ospf_lsdb_count(area->lsdb, OSPF_ROUTER_LSA) -
+			       ospf_lsdb_count_self(area->lsdb,
+						    OSPF_ROUTER_LSA));
+
+	if (count_router_lsas >
+	    (unsigned int)area->fr_info.router_lsas_recv_dc_bit) {
+		area->fr_info.enabled = false;
+		area->fr_info.area_dc_clear = true;
+		return;
+	} else if (count_router_lsas <
+		   (unsigned int)area->fr_info.router_lsas_recv_dc_bit) {
+		/* This can never happen, total number of router lsas received
+		 * can never be less than router lsas received with dc bit set
+		 */
+		OSPF_LOG_ERR("%s: Counter mismatch for area %pI4", __func__,
+			     &area->area_id);
+		OSPF_LOG_ERR(
+			"%s: router LSAs in lsdb %d router LSAs recvd with dc bit set %d",
+			__func__, count_router_lsas,
+			area->fr_info.router_lsas_recv_dc_bit);
+		return;
+	}
+
+	area->fr_info.area_dc_clear = false;
+
+	if (OSPF_FR_CONFIG(area->ospf, area)) {
+		if (!area->fr_info.enabled) {
+			area->fr_info.enabled = true;
+			area->fr_info.state_changed = true;
+		}
+	} else {
+		area->fr_info.enabled = false;
+		area->fr_info.area_dc_clear = true;
+	}
+}
+
 /* Do the LSA acking specified in table 19, Section 13.5, row 2
  * This get called from ospf_flood_out_interface. Declared inline
  * for speed. */
@@ -428,6 +497,55 @@ int ospf_flood(struct ospf *ospf, struct ospf_neighbor *nbr,
 	if (!(new = ospf_lsa_install(ospf, oi, new)))
 		return -1; /* unknown LSA type or any other error condition */
 
+	/* check if the installed LSA is an indication LSA */
+	if (ospf_check_indication_lsa(new) && !IS_LSA_SELF(new) &&
+	    !IS_LSA_MAXAGE(new)) {
+		new->area->fr_info.area_ind_lsa_recvd = true;
+		/* check if there are already type 5 LSAs originated
+		 * with DNA bit set, if yes reoriginate those LSAs.
+		 */
+		ospf_refresh_dna_type5_and_type7_lsas(ospf);
+	}
+
+	/* Check if we recived an indication LSA flush on backbone
+	 * network.
+	 */
+	ospf_recv_indication_lsa_flush(new);
+
+	if (new->area && OSPF_FR_CONFIG(ospf, new->area)) {
+		struct lsa_header const *lsah = new->data;
+
+		if (!CHECK_FLAG(lsah->options, OSPF_OPTION_DC) &&
+		    !ospf_check_indication_lsa(new)) {
+
+			new->area->fr_info.area_dc_clear = true;
+			/* check of previously area supported flood reduction */
+			if (new->area->fr_info.enabled) {
+				new->area->fr_info.enabled = false;
+				OSPF_LOG_DEBUG(
+					IS_DEBUG_OSPF_EVENT,
+					"Flood Reduction STATE on -> off by %s LSA",
+					dump_lsa_key(new));
+				/* if yes update all the lsa to the area the
+				 * new LSAs will have DNA bit set to 0.
+				 */
+				ospf_refresh_area_self_lsas(new->area);
+			}
+		} else if (!new->area->fr_info.enabled) {
+			/* check again after installing new LSA that area
+			 * supports flood reduction.
+			 */
+			ospf_area_update_fr_state(new->area);
+			if (new->area->fr_info.enabled) {
+				OSPF_LOG_DEBUG(
+					IS_DEBUG_OSPF_EVENT,
+					"Flood Reduction STATE off -> on by %s LSA",
+					dump_lsa_key(new));
+				ospf_refresh_area_self_lsas(new->area);
+			}
+		}
+	}
+
 	/* Acknowledge the receipt of the LSA by sending a Link State
 	   Acknowledgment packet back out the receiving interface. */
 	if (lsa_ack_flag)
@@ -465,6 +583,25 @@ int ospf_flood_through_interface(struct ospf_interface *oi,
 	if (!ospf_if_is_enable(oi))
 		return 0;
 
+	/* If flood reduction is configured, set the DC bit on the lsa. */
+	if (IS_LSA_SELF(lsa)) {
+		if (OSPF_FR_CONFIG(oi->area->ospf, oi->area)) {
+			if (!ospf_check_indication_lsa(lsa)) {
+				SET_FLAG(lsa->data->options, OSPF_OPTION_DC);
+				ospf_lsa_checksum(lsa->data);
+			}
+		} else if (CHECK_FLAG(lsa->data->options, OSPF_OPTION_DC)) {
+			UNSET_FLAG(lsa->data->options, OSPF_OPTION_DC);
+			ospf_lsa_checksum(lsa->data);
+		}
+
+		/* If flood reduction is enabled then set DNA bit on the
+		 * self lsas.
+		 */
+		if (oi->area->fr_info.enabled)
+			SET_FLAG(lsa->data->ls_age, DO_NOT_AGE);
+	}
+
 	/* Remember if new LSA is added to a retransmit list. */
 	retx_flag = 0;