ospf6d: Helper functionality changes

Description:
	1. changes to process GRACE LSA packet.
	2. Validation changes to enter Helper role.
	3. Helper functionality during graceful restart.

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

1 files changed, 290 insertions, 6 deletions

diff --git a/ospf6d/ospf6_gr_helper.c b/ospf6d/ospf6_gr_helper.c
index a7a1b7cba..d03517115 100644
--- a/ospf6d/ospf6_gr_helper.c
+++ b/ospf6d/ospf6_gr_helper.c
@@ -1,5 +1,5 @@
 /*
- * OSPF6 Graceful Retsart helper functions.
+ * OSPF6 Graceful Restart helper functions.
  *
  * Copyright (C) 2021-22 Vmware, Inc.
  * Rajesh Kumar Girada
@@ -47,7 +47,7 @@
 #include "ospf6_neighbor.h"
 #include "ospf6_intra.h"
 #include "ospf6d.h"
-#include "ospf6_gr_helper.h"
+#include "ospf6_gr.h"
 #include "lib/json.h"
 #ifndef VTYSH_EXTRACT_PL
 #include "ospf6d/ospf6_gr_helper_clippy.c"
@@ -55,7 +55,7 @@
 
 DEFINE_MTYPE_STATIC(OSPF6D, OSPF6_GR_HELPER, "OSPF6 Graceful restart helper");
 
-unsigned char conf_debug_ospf6_gr = 0;
+unsigned char conf_debug_ospf6_gr;
 
 const char *ospf6_exit_reason_desc[] = {
 	"Unknown reason",     "Helper inprogress",	   "Topology Change",
@@ -119,6 +119,290 @@ static void ospf6_enable_rtr_hash_destroy(struct ospf6 *ospf6)
 	ospf6->ospf6_helper_cfg.enable_rtr_list = NULL;
 }
 
+/*
+ * Extracting tlv info from GRACE LSA.
+ *
+ * lsa
+ *   ospf6 grace lsa
+ *
+ * Returns:
+ * interval : grace interval.
+ * reason   : Restarting reason.
+ */
+static int ospf6_extract_grace_lsa_fields(struct ospf6_lsa *lsa,
+					  uint32_t *interval, uint8_t *reason)
+{
+	struct ospf6_lsa_header *lsah = NULL;
+	struct tlv_header *tlvh = NULL;
+	struct grace_tlv_graceperiod *gracePeriod;
+	struct grace_tlv_restart_reason *grReason;
+	uint16_t length = 0;
+	int sum = 0;
+
+	lsah = (struct ospf6_lsa_header *)lsa->header;
+
+	length = ntohs(lsah->length) - OSPF6_LSA_HEADER_SIZE;
+
+	for (tlvh = TLV_HDR_TOP(lsah); sum < length;
+	     tlvh = TLV_HDR_NEXT(tlvh)) {
+		switch (ntohs(tlvh->type)) {
+		case GRACE_PERIOD_TYPE:
+			gracePeriod = (struct grace_tlv_graceperiod *)tlvh;
+			*interval = ntohl(gracePeriod->interval);
+			sum += TLV_SIZE(tlvh);
+
+			/* Check if grace interval is valid */
+			if (*interval > OSPF6_MAX_GRACE_INTERVAL
+			    || *interval < OSPF6_MIN_GRACE_INTERVAL)
+				return OSPF6_FAILURE;
+			break;
+		case RESTART_REASON_TYPE:
+			grReason = (struct grace_tlv_restart_reason *)tlvh;
+			*reason = grReason->reason;
+			sum += TLV_SIZE(tlvh);
+
+			if (*reason >= OSPF6_GR_INVALID_REASON_CODE)
+				return OSPF6_FAILURE;
+			break;
+		default:
+			if (IS_DEBUG_OSPF6_GR_HELPER)
+				zlog_debug(
+					"%s, Ignoring unknown TLV type:%d",
+					__func__, ntohs(tlvh->type));
+		}
+	}
+
+	return OSPF6_SUCCESS;
+}
+
+/*
+ * Grace timer expiry handler.
+ * HELPER aborts its role at grace timer expiry.
+ *
+ * thread
+ *    thread pointer
+ *
+ * Returns:
+ *    Nothing
+ */
+static int ospf6_handle_grace_timer_expiry(struct thread *thread)
+{
+	struct ospf6_neighbor *nbr = THREAD_ARG(thread);
+
+	nbr->gr_helper_info.t_grace_timer = NULL;
+
+	// ospf6_gr_helper_exit(nbr, OSPF6_GR_HELPER_GRACE_TIMEOUT);
+	return OSPF6_SUCCESS;
+}
+
+/*
+ * API to check any change in the neighbor's
+ * retransmission list.
+ *
+ * nbr
+ *    ospf6 neighbor
+ *
+ * Returns:
+ *    TRUE  - if any change in the lsa.
+ *    FALSE - no change in the lsas.
+ */
+static bool ospf6_check_chg_in_rxmt_list(struct ospf6_neighbor *nbr)
+{
+	struct ospf6_lsa *lsa, *lsanext;
+
+	for (ALL_LSDB(nbr->retrans_list, lsa, lsanext)) {
+		struct ospf6_lsa *lsa_in_db = NULL;
+
+		/* Fetching the same copy of LSA form LSDB to validate the
+		 * topochange.
+		 */
+		lsa_in_db =
+			ospf6_lsdb_lookup(lsa->header->type, lsa->header->id,
+					  lsa->header->adv_router, lsa->lsdb);
+
+		if (lsa_in_db && lsa_in_db->tobe_acknowledged)
+			return OSPF6_TRUE;
+	}
+
+	return OSPF6_FALSE;
+}
+
+/*
+ * Process Grace LSA.If it is eligible move to HELPER role.
+ * Ref rfc3623 section 3.1 and rfc5187
+ *
+ * ospf
+ *    Ospf6 pointer.
+ *
+ * lsa
+ *    Grace LSA received from RESTARTER.
+ *
+ * restarter
+ *    ospf6 neighbour which requests 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 ospf6_process_grace_lsa(struct ospf6 *ospf6, struct ospf6_lsa *lsa,
+			    struct ospf6_neighbor *restarter)
+{
+	uint8_t restart_reason = 0;
+	uint32_t grace_interval = 0;
+	uint32_t actual_grace_interval = 0;
+	struct advRtr lookup;
+	int ret;
+
+	/* Extract the grace lsa packet fields */
+	ret = ospf6_extract_grace_lsa_fields(lsa, &grace_interval,
+					     &restart_reason);
+	if (ret != OSPF6_SUCCESS) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug("%s, Wrong Grace LSA packet.",
+				   __func__);
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	if (IS_DEBUG_OSPF6_GR_HELPER)
+		zlog_debug(
+			"%s, Grace LSA received from  %pI4, grace interval:%u, restart reason :%s",
+			__func__, &restarter->router_id,
+			grace_interval,
+			ospf6_restart_reason_desc[restart_reason]);
+
+	/* Verify Helper enabled globally */
+	if (!ospf6->ospf6_helper_cfg.is_helper_supported) {
+		/* Verify Helper support is enabled for the
+		 * current neighbour router-id.
+		 */
+		lookup.advRtrAddr = restarter->router_id;
+
+		if (!hash_lookup(ospf6->ospf6_helper_cfg.enable_rtr_list,
+				 &lookup)) {
+			if (IS_DEBUG_OSPF6_GR_HELPER)
+				zlog_debug(
+					"%s, HELPER support is disabled, So not a HELPER",
+					__func__);
+			restarter->gr_helper_info.rejected_reason =
+				OSPF6_HELPER_SUPPORT_DISABLED;
+			return OSPF6_GR_NOT_HELPER;
+		}
+	}
+
+	/* Check neighbour is in FULL state and
+	 * became a adjacency.
+	 */
+	if (!IS_NBR_STATE_FULL(restarter)) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, This Neighbour %pI6 is not in FULL state.",
+				__func__, &restarter->linklocal_addr);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_NOT_A_VALID_NEIGHBOUR;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* Based on the restart reason from grace lsa
+	 * check the current router is supporting or not
+	 */
+	if (ospf6->ospf6_helper_cfg.only_planned_restart
+	    && !OSPF6_GR_IS_PLANNED_RESTART(restart_reason)) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, Router supports only planned restarts but received the GRACE LSA due a unplanned restart",
+				__func__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_PLANNED_ONLY_RESTART;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/* Check the retransmission list of this
+	 * neighbour, check any change in lsas.
+	 */
+	if (ospf6->ospf6_helper_cfg.strict_lsa_check
+	    && restarter->retrans_list->count
+	    && ospf6_check_chg_in_rxmt_list(restarter)) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, Changed LSA in Rxmt list.So not Helper.",
+				__func__);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_TOPO_CHANGE_RTXMT_LIST;
+		return OSPF6_GR_NOT_HELPER;
+	}
+
+	/*LSA age must be less than the grace period */
+	if (ntohs(lsa->header->age) >= grace_interval) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, Grace LSA age(%d) is more than the grace interval(%d)",
+				__func__, lsa->header->age,
+				grace_interval);
+		restarter->gr_helper_info.rejected_reason =
+			OSPF6_HELPER_LSA_AGE_MORE;
+		return OSPF6_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 > ospf6->ospf6_helper_cfg.supported_grace_time) {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, Received grace period %d is larger than supported grace %d",
+				__func__, grace_interval,
+				ospf6->ospf6_helper_cfg.supported_grace_time);
+		actual_grace_interval =
+			ospf6->ospf6_helper_cfg.supported_grace_time;
+	}
+
+	if (OSPF6_GR_IS_ACTIVE_HELPER(restarter)) {
+		if (restarter->gr_helper_info.t_grace_timer)
+			THREAD_OFF(restarter->gr_helper_info.t_grace_timer);
+
+		if (ospf6->ospf6_helper_cfg.active_restarter_cnt > 0)
+			ospf6->ospf6_helper_cfg.active_restarter_cnt--;
+
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, Router is already acting as a HELPER for this nbr,so restart the grace timer",
+				__func__);
+	} else {
+		if (IS_DEBUG_OSPF6_GR_HELPER)
+			zlog_debug(
+				"%s, This Router becomes a HELPER for the neighbour %pI6",
+				__func__, &restarter->linklocal_addr);
+	}
+
+	/* Became a Helper to the RESTART neighbour.
+	 * change the helper status.
+	 */
+	restarter->gr_helper_info.gr_helper_status = OSPF6_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 = OSPF6_HELPER_REJECTED_NONE;
+
+	/* Increment the active restart nbr count */
+	ospf6->ospf6_helper_cfg.active_restarter_cnt++;
+
+	if (IS_DEBUG_OSPF6_GR_HELPER)
+		zlog_debug("%s, Grace timer started.interval:%u",
+			   __func__, actual_grace_interval);
+
+	/* Start the grace timer */
+	thread_add_timer(master, ospf6_handle_grace_timer_expiry, restarter,
+			 actual_grace_interval,
+			 &restarter->gr_helper_info.t_grace_timer);
+
+	return OSPF6_GR_ACTIVE_HELPER;
+}
+
 /* Debug commands */
 DEFPY(debug_ospf6_gr,
       debug_ospf6_gr_cmd,
@@ -136,7 +420,7 @@ DEFPY(debug_ospf6_gr,
 }
 
 /*
- * Initilise GR helper config datastructer.
+ * Initialize GR helper config data structure.
  *
  * ospf6
  *    ospf6 pointer
@@ -147,7 +431,7 @@ DEFPY(debug_ospf6_gr,
 void ospf6_gr_helper_init(struct ospf6 *ospf6)
 {
 	if (IS_DEBUG_OSPF6_GR_HELPER)
-		zlog_debug("%s, GR Helper init.", __PRETTY_FUNCTION__);
+		zlog_debug("%s, GR Helper init.", __func__);
 
 	ospf6->ospf6_helper_cfg.is_helper_supported = OSPF6_FALSE;
 	ospf6->ospf6_helper_cfg.strict_lsa_check = OSPF6_TRUE;
@@ -174,7 +458,7 @@ void ospf6_gr_helper_deinit(struct ospf6 *ospf6)
 {
 
 	if (IS_DEBUG_OSPF6_GR_HELPER)
-		zlog_debug("%s, GR helper deinit.", __PRETTY_FUNCTION__);
+		zlog_debug("%s, GR helper deinit.", __func__);
 
 	ospf6_enable_rtr_hash_destroy(ospf6);
 }