ospfd: Grace LSA processing

Description:
	1. Grace LSA processing.
	2. Validations to become a Helper. rfc3623 section 3.1

Signed-off-by: Rajesh Girada <rgirada@vmware.com>

ospfd/ospf_flood.c

@@ -337,6 +337,45 @@ int ospf_flood(struct ospf *ospf, struct ospf_neighbor *nbr,
 	SET_FLAG(new->flags, OSPF_LSA_RECEIVED);
 	(void)ospf_lsa_is_self_originated(ospf, new); /* Let it set the flag */
 
+	/* Received Grace LSA */
+	if (IS_GRACE_LSA(new)) {
+
+		if (IS_LSA_MAXAGE(new)) {
+
+			/*  Handling Max age grace LSA.*/
+			if (IS_DEBUG_OSPF_GR_HELPER)
+				zlog_debug(
+					"%s, Received a maxage GRACE-LSA from router %s",
+					__PRETTY_FUNCTION__,
+					inet_ntoa(new->data->adv_router));
+
+			if (current) {
+				ospf_process_maxage_grace_lsa(ospf, new, nbr);
+			} else {
+				if (IS_DEBUG_OSPF_GR_HELPER)
+					zlog_debug(
+						"%s, Grace LSA doesn't exist in lsdb, so discarding grace lsa",
+						__PRETTY_FUNCTION__);
+				return -1;
+			}
+		} else {
+			if (IS_DEBUG_OSPF_GR_HELPER)
+				zlog_debug(
+					"%s, Received a GRACE-LSA from router %s",
+					__PRETTY_FUNCTION__,
+					inet_ntoa(new->data->adv_router));
+
+			if (ospf_process_grace_lsa(ospf, new, nbr)
+			    == OSPF_GR_NOT_HELPER) {
+				if (IS_DEBUG_OSPF_GR_HELPER)
+					zlog_debug(
+						"%s, Not moving to HELPER role, So discarding grace LSA",
+						__PRETTY_FUNCTION__);
+				return -1;
+			}
+		}
+	}
+
 	/* Install the new LSA in the link state database
 	   (replacing the current database copy).  This may cause the
 	   routing table calculation to be scheduled.  In addition,

ospfd/ospf_gr_helper.c

@@ -50,6 +50,31 @@
 #include "ospfd/ospf_ism.h"
 #include "ospfd/ospf_gr_helper.h"
 
+const char *ospf_exit_reason_desc[] = {
+	"Unknown reason",
+	"Helper inprogress",
+	"Topology Change",
+	"Grace timer expairy",
+	"Successful graceful restart",
+};
+
+const char *ospf_restart_reason_desc[] = {
+	"Unknown restart",
+	"Software restart",
+	"Software reload/upgrade",
+	"Switch to redundant control processor",
+};
+
+const char *ospf_rejected_reason_desc[] = {
+	"Unknown reason",
+	"Helper support disabled",
+	"Neighbour is not in FULL state",
+	"Supports only planned restart but received for unplanned",
+	"Topo change due to change in lsa rxmt list",
+	"LSA age is more than Grace interval",
+};
+
+static bool ospf_check_change_in_rxmt_list(struct ospf_neighbor *nbr);
 
 static unsigned int ospf_enable_rtr_hash_key(const void *data)
 {
@@ -105,9 +130,9 @@ void ospf_gr_helper_init(struct ospf *ospf)
 	if (IS_DEBUG_OSPF_GR_HELPER)
 		zlog_debug("%s, GR Helper init.", __PRETTY_FUNCTION__);
 
-	ospf->is_helper_supported = OSPF_FALSE;
-	ospf->strict_lsa_check = OSPF_TRUE;
-	ospf->only_planned_restart = OSPF_FALSE;
+	ospf->is_helper_supported = OSPF_GR_FALSE;
+	ospf->strict_lsa_check = OSPF_GR_TRUE;
+	ospf->only_planned_restart = OSPF_GR_FALSE;
 	ospf->supported_grace_time = OSPF_MAX_GRACE_INTERVAL;
 	ospf->last_exit_reason = OSPF_GR_HELPER_EXIT_NONE;
 	ospf->active_restarter_cnt = 0;
@@ -134,3 +159,379 @@ void ospf_gr_helper_stop(struct ospf *ospf)
 
 	ospf_enable_rtr_hash_destroy(ospf);
 }
+
+/*
+ * Extracting tlv info from GRACE LSA.
+ *
+ * lsa
+ *   ospf grace lsa
+ *
+ * Returns:
+ * interval : grace interval.
+ * addr     : RESTARTER address.
+ * reason   : Restarting reason.
+ */
+static int ospf_extract_grace_lsa_fields(struct ospf_lsa *lsa,
+					 uint32_t *interval,
+					 struct in_addr *addr, uint8_t *reason)
+{
+	struct lsa_header *lsah = NULL;
+	struct tlv_header *tlvh = NULL;
+	struct grace_tlv_graceperiod *grace_period;
+	struct grace_tlv_restart_reason *gr_reason;
+	struct grace_tlv_restart_addr *restart_addr;
+	uint16_t length = 0;
+	int sum = 0;
+
+	lsah = (struct lsa_header *)lsa->data;
+
+	length = ntohs(lsah->length) - OSPF_LSA_HEADER_SIZE;
+
+	for (tlvh = TLV_HDR_TOP(lsah); sum < length;
+	     tlvh = TLV_HDR_NEXT(tlvh)) {
+		switch (ntohs(tlvh->type)) {
+		case GRACE_PERIOD_TYPE:
+			grace_period = (struct grace_tlv_graceperiod *)tlvh;
+			*interval = ntohl(grace_period->interval);
+			sum += TLV_SIZE(tlvh);
+
+			/* Check if grace interval is valid */
+			if (*interval > OSPF_MAX_GRACE_INTERVAL
+			    || *interval < OSPF_MIN_GRACE_INTERVAL)
+				return OSPF_GR_FAILURE;
+			break;
+		case RESTART_REASON_TYPE:
+			gr_reason = (struct grace_tlv_restart_reason *)tlvh;
+			*reason = gr_reason->reason;
+			sum += TLV_SIZE(tlvh);
+
+			if (*reason >= OSPF_GR_INVALID_REASON_CODE)
+				return OSPF_GR_FAILURE;
+			break;
+		case RESTARTER_IP_ADDR_TYPE:
+			restart_addr = (struct grace_tlv_restart_addr *)tlvh;
+			addr->s_addr = restart_addr->addr.s_addr;
+			sum += TLV_SIZE(tlvh);
+			break;
+		default:
+			if (IS_DEBUG_OSPF_GR_HELPER)
+				zlog_debug(
+					"%s, Malformed packet.Invalid TLV type:%d",
+					__PRETTY_FUNCTION__, ntohs(tlvh->type));
+			return OSPF_GR_FAILURE;
+		}
+	}
+
+	return OSPF_GR_SUCCESS;
+}
+
+/*
+ * Grace timer expiry handler.
+ * HELPER aborts its role at grace timer expiry.
+ *
+ * thread
+ *    thread pointer
+ *
+ * Returns:
+ *    Nothing
+ */
+static int ospf_handle_grace_timer_expiry(struct thread *thread)
+{
+	struct ospf_neighbor *nbr = THREAD_ARG(thread);
+
+	nbr->gr_helper_info.t_grace_timer = NULL;
+
+	ospf_gr_helper_exit(nbr, OSPF_GR_HELPER_GRACE_TIMEOUT);
+	return OSPF_GR_SUCCESS;
+}
+
+/*
+ * Process Grace LSA.If it is eligible move to HELPER role.
+ * Ref rfc3623 section 3.1
+ *
+ * ospf
+ *    Ospf pointer.
+ *
+ * lsa
+ *    Grace LSA received from RESTARTER.
+ *
+ * nbr
+ *    ospf neighbour which requets the router to act as
+ *    HELPER.
+ *
+ * Returns:
+ *    status.
+ *    If supported as HELPER : OSPF_GR_HELPER_INPROGRESS
+ *    If Not supported as HELPER : OSPF_GR_HELPER_NONE
+ */
+int ospf_process_grace_lsa(struct ospf *ospf, struct ospf_lsa *lsa,
+			   struct ospf_neighbor *nbr)
+{
+	struct in_addr restart_addr = {0};
+	uint8_t restart_reason = 0;
+	uint32_t grace_interval = 0;
+	uint32_t actual_grace_interval = 0;
+	struct advRtr lookup;
+	struct ospf_neighbor *restarter = NULL;
+	struct ospf_interface *oi = nbr->oi;
+	int ret;
+
+
+	/* Extract the grace lsa packet fields */
+	ret = ospf_extract_grace_lsa_fields(lsa, &grace_interval, &restart_addr,
+					    &restart_reason);
+	if (ret != OSPF_GR_SUCCESS) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug("%s, Wrong Grace LSA packet.",
+				   __PRETTY_FUNCTION__);
+		return OSPF_GR_NOT_HELPER;
+	}
+
+	if (IS_DEBUG_OSPF_GR_HELPER)
+		zlog_debug(
+			"%s, Grace LSA received from %s, grace interval:%u, restartreason :%s",
+			__PRETTY_FUNCTION__, inet_ntoa(restart_addr),
+			grace_interval, ospf_restart_reason_desc[restart_reason]);
+
+	/* Incase of broadcast links, if RESTARTER is DR_OTHER,
+	 * grace LSA might be received from DR, so need to get
+	 * actual neighbour info , here RESTARTER.
+	 */
+	if (oi->type != OSPF_IFTYPE_POINTOPOINT) {
+		restarter = ospf_nbr_lookup_by_addr(oi->nbrs, &restart_addr);
+
+		if (!restarter) {
+			if (IS_DEBUG_OSPF_GR_HELPER)
+				zlog_debug(
+					"%s, Restarter is not a nbr(%s) for this router.",
+					__PRETTY_FUNCTION__,
+					inet_ntoa(restart_addr));
+			return OSPF_GR_NOT_HELPER;
+		}
+	} else
+		restarter = nbr;
+
+	/* Verify Helper enabled globally */
+	if (!ospf->is_helper_supported) {
+		/* Verify that Helper support is enabled for the
+		 * current neighbour router-id.
+		 */
+		lookup.advRtrAddr.s_addr = restarter->router_id.s_addr;
+
+		if (!hash_lookup(ospf->enable_rtr_list, &lookup)) {
+			if (IS_DEBUG_OSPF_GR_HELPER)
+				zlog_debug(
+					"%s, HELPER support is disabled, So not a HELPER",
+					__PRETTY_FUNCTION__);
+			restarter->gr_helper_info.rejected_reason =
+				OSPF_HELPER_SUPPORT_DISABLED;
+			return OSPF_GR_NOT_HELPER;
+		}
+	}
+
+
+	/* Check neighbour is in FULL state and
+	 * became a adjacency.
+	 */
+	if (!IS_NBR_STATE_FULL(restarter)) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, This Neighbour %s is not in FULL state.",
+				__PRETTY_FUNCTION__, inet_ntoa(restarter->src));
+		restarter->gr_helper_info.rejected_reason =
+			OSPF_HELPER_NOT_A_VALID_NEIGHBOUR;
+		return OSPF_GR_NOT_HELPER;
+	}
+
+	/* Based on the restart reason from grace lsa
+	 * check the current router is supporting or not
+	 */
+	if (ospf->only_planned_restart
+	    && !OSPF_GR_IS_PLANNED_RESTART(restart_reason)) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, Router supports only planned restarts but received the GRACE LSA for an unplanned restart.",
+				__PRETTY_FUNCTION__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF_HELPER_PLANNED_ONLY_RESTART;
+		return OSPF_GR_NOT_HELPER;
+	}
+
+	/* Check the retranmission list of this
+	 * neighbour, check any change in lsas.
+	 */
+	if (ospf->strict_lsa_check && !ospf_ls_retransmit_isempty(restarter)
+	    && ospf_check_change_in_rxmt_list(restarter)) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, Changed LSA in Rxmt list. So not Helper.",
+				__PRETTY_FUNCTION__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF_HELPER_TOPO_CHANGE_RTXMT_LIST;
+		return OSPF_GR_NOT_HELPER;
+	}
+
+	/*LSA age must be less than the grace period */
+	if (ntohs(lsa->data->ls_age) >= grace_interval) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, Grace LSA age(%d) is more than the graceinterval(%d)",
+				__PRETTY_FUNCTION__, lsa->data->ls_age,
+				grace_interval);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF_HELPER_LSA_AGE_MORE;
+		return OSPF_GR_NOT_HELPER;
+	}
+
+	/* check supported grace period configured
+	 * if configured, use this to start the grace
+	 * timer otherwise use the interval received
+	 * in grace LSA packet.
+	 */
+	actual_grace_interval = grace_interval;
+	if (grace_interval > ospf->supported_grace_time) {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, Received grace period %d is larger than supported grace %d",
+				__PRETTY_FUNCTION__, grace_interval,
+				ospf->supported_grace_time);
+		actual_grace_interval = ospf->supported_grace_time;
+	}
+
+	if (OSPF_GR_IS_ACTIVE_HELPER(restarter)) {
+		if (restarter->gr_helper_info.t_grace_timer)
+			THREAD_OFF(restarter->gr_helper_info.t_grace_timer);
+
+		if (ospf->active_restarter_cnt > 0)
+			ospf->active_restarter_cnt--;
+
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, Router is already acting as a HELPER for this nbr,so restart the grace timer",
+				__PRETTY_FUNCTION__);
+	} else {
+		if (IS_DEBUG_OSPF_GR_HELPER)
+			zlog_debug(
+				"%s, This Router becomes a HELPER for the neighbour %s",
+				__PRETTY_FUNCTION__, inet_ntoa(restarter->src));
+	}
+
+	/* Became a Helper to the RESTART neighbour.
+	 * Change the helper status.
+	 */
+	restarter->gr_helper_info.gr_helper_status = OSPF_GR_ACTIVE_HELPER;
+	restarter->gr_helper_info.recvd_grace_period = grace_interval;
+	restarter->gr_helper_info.actual_grace_period = actual_grace_interval;
+	restarter->gr_helper_info.gr_restart_reason = restart_reason;
+	restarter->gr_helper_info.rejected_reason = OSPF_HELPER_REJECTED_NONE;
+
+	/* Incremnet the active restarer count */
+	ospf->active_restarter_cnt++;
+
+	if (IS_DEBUG_OSPF_GR_HELPER)
+		zlog_debug("%s, Grace timer started.interval:%d",
+			   __PRETTY_FUNCTION__, actual_grace_interval);
+
+	/* Start the grace timer */
+	thread_add_timer(master, ospf_handle_grace_timer_expiry, restarter,
+			 actual_grace_interval,
+			 &restarter->gr_helper_info.t_grace_timer);
+
+	return OSPF_GR_ACTIVE_HELPER;
+}
+
+/*
+ * API to check any change in the neighbor's
+ * retransmission list.
+ *
+ * nbr
+ *    ospf neighbor
+ *
+ * Returns:
+ *    TRUE  - if any change in the lsa.
+ *    FALSE - no change in the lsas.
+ */
+static bool ospf_check_change_in_rxmt_list(struct ospf_neighbor *nbr)
+{
+	struct route_node *rn;
+	struct ospf_lsa *lsa;
+	struct route_table *tbl;
+
+	tbl = nbr->ls_rxmt.type[OSPF_ROUTER_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+	tbl = nbr->ls_rxmt.type[OSPF_NETWORK_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+
+	tbl = nbr->ls_rxmt.type[OSPF_SUMMARY_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+
+	tbl = nbr->ls_rxmt.type[OSPF_ASBR_SUMMARY_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+
+	tbl = nbr->ls_rxmt.type[OSPF_AS_EXTERNAL_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+
+	tbl = nbr->ls_rxmt.type[OSPF_AS_NSSA_LSA].db;
+	LSDB_LOOP (tbl, rn, lsa)
+		if (lsa->to_be_acknowledged)
+			return OSPF_GR_TRUE;
+
+	return OSPF_GR_FALSE;
+}
+
+/*
+ * Api to exit from HELPER role to take all actions
+ * required at exit.
+ * Ref rfc3623 section 3.2
+ *
+ * ospf
+ *    Ospf pointer.
+ *
+ * nbr
+ *    Ospf neighbour for which it is acting as HELPER.
+ *
+ * reason
+ *    The reason for exiting from HELPER.
+ *
+ * Returns:
+ *    Nothing.
+ */
+void ospf_gr_helper_exit(struct ospf_neighbor *nbr,
+			 enum ospf_helper_exit_reason reason)
+{
+	return;
+}
+
+/*
+ * Process Maxage Grace LSA.
+ * It is a indication for successfull completion of GR.
+ * If router acting as HELPER, It exits from helper role.
+ *
+ * ospf
+ *    Ospf pointer.
+ *
+ * lsa
+ *    Grace LSA received from RESTARTER.
+ *
+ * nbr
+ *    ospf neighbour which requets the router to act as
+ *    HELPER.
+ *
+ * Returns:
+ *    Nothing.
+ */
+void ospf_process_maxage_grace_lsa(struct ospf *ospf, struct ospf_lsa *lsa,
+				   struct ospf_neighbor *nbr)
+{
+	return;
+}

ospfd/ospf_gr_helper.h

@@ -154,4 +154,10 @@ struct advRtr {
 
 extern void ospf_gr_helper_init(struct ospf *);
 extern void ospf_gr_helper_stop(struct ospf *ospf);
-#endif /* _ZEBRA_OSPF_GR_HELPER_H */
+extern int ospf_process_grace_lsa(struct ospf *ospf, struct ospf_lsa *lsa,
+				  struct ospf_neighbor *nbr);
+extern void ospf_gr_helper_exit(struct ospf_neighbor *nbr,
+				enum ospf_helper_exit_reason reason);
+void ospf_process_maxage_grace_lsa(struct ospf *ospf, struct ospf_lsa *lsa,
+				   struct ospf_neighbor *nbr);
+#endif /* _ZEBRA_OSPF_HELPER_H */

ospfd/ospf_lsa.h

@@ -119,6 +119,9 @@ struct ospf_lsa {
 
 	/* VRF Id */
 	vrf_id_t vrf_id;
+
+	/*For topo chg detection in HELPER role*/
+	bool to_be_acknowledged;
 };
 
 /* OSPF LSA Link Type. */

ospfd/ospf_nsm.c

@@ -144,7 +144,7 @@ static void nsm_timer_set(struct ospf_neighbor *nbr)
 /* 10.4 of RFC2328, indicate whether an adjacency is appropriate with
  * the given neighbour
  */
-static int nsm_should_adj(struct ospf_neighbor *nbr)
+int nsm_should_adj(struct ospf_neighbor *nbr)
 {
 	struct ospf_interface *oi = nbr->oi;
 

ospfd/ospf_nsm.h

@@ -81,7 +81,7 @@ extern void ospf_check_nbr_loading(struct ospf_neighbor *);
 extern int ospf_db_summary_isempty(struct ospf_neighbor *);
 extern int ospf_db_summary_count(struct ospf_neighbor *);
 extern void ospf_db_summary_clear(struct ospf_neighbor *);
-
+extern int nsm_should_adj(struct ospf_neighbor *nbr);
 DECLARE_HOOK(ospf_nsm_change,
 	     (struct ospf_neighbor * on, int state, int oldstate),
 	     (on, state, oldstate))