bgpd: Refine restarter operation - R-bit & F-bit

Introduce BGP-wide flags to denote if BGP has started gracefully
and GR is in progress or not. Use this for setting of the R-bit in
the GR capability, and not a timer which is set for any new
instance creation. Mark graceful restart is complete when the
deferred path selection has been done and route sync with zebra as
well as deferred EOR advertisement has been initiated.

Introduce a function to check on F-bit setting rather than just
base it on configuration.

Subsequent commits will extend these functionalities.

Signed-off-by: Vivek Venkatraman <vivek@nvidia.com>

1 files changed, 63 insertions, 2 deletions

diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index 77955fd5c..3c5826113 100644
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -167,6 +167,8 @@ struct bgp_master {
 #define BM_FLAG_GR_RESTARTER		 (1 << 3)
 #define BM_FLAG_GR_DISABLED		 (1 << 4)
 #define BM_FLAG_GR_PRESERVE_FWD		 (1 << 5)
+#define BM_FLAG_GRACEFUL_RESTART	 (1 << 6)
+#define BM_FLAG_GR_COMPLETE		 (1 << 7)
 
 #define BM_FLAG_GR_CONFIGURED (BM_FLAG_GR_RESTARTER | BM_FLAG_GR_DISABLED)
 
@@ -176,6 +178,9 @@ struct bgp_master {
 	uint32_t select_defer_time;
 	uint32_t rib_stale_time;
 
+	time_t startup_time;
+	time_t gr_completion_time;
+
 	bool terminating;	/* global flag that sigint terminate seen */
 
 	/* TOS value for outgoing packets in BGP connections */
@@ -305,9 +310,9 @@ struct graceful_restart_info {
 	/* Best route select */
 	struct event *t_route_select;
 	/* AFI, SAFI enabled */
-	bool af_enabled[AFI_MAX][SAFI_MAX];
+	bool af_enabled;
 	/* Route update completed */
-	bool route_sync[AFI_MAX][SAFI_MAX];
+	bool route_sync;
 };
 
 enum global_mode {
@@ -559,6 +564,9 @@ struct bgp {
 	 */
 	enum zebra_gr_mode present_zebra_gr_state;
 
+	/* Is deferred path selection still not complete? */
+	bool gr_route_sync_pending;
+
 	/* BGP Per AF flags */
 	uint16_t af_flags[AFI_MAX][SAFI_MAX];
 #define BGP_CONFIG_DAMPENING				(1 << 0)
@@ -2754,6 +2762,59 @@ static inline bool bgp_in_graceful_shutdown(struct bgp *bgp)
 	        !!CHECK_FLAG(bm->flags, BM_FLAG_GRACEFUL_SHUTDOWN));
 }
 
+static inline bool bgp_in_graceful_restart(void)
+{
+	/* True if BGP has (re)started gracefully (based on flags
+	 * noted at startup) and GR is not complete.
+	 */
+	return (CHECK_FLAG(bm->flags, BM_FLAG_GRACEFUL_RESTART) &&
+		!CHECK_FLAG(bm->flags, BM_FLAG_GR_COMPLETE));
+}
+
+static inline bool bgp_is_graceful_restart_complete(void)
+{
+	/* True if BGP has (re)started gracefully (based on flags
+	 * noted at startup) and GR is marked as complete.
+	 */
+	return (CHECK_FLAG(bm->flags, BM_FLAG_GRACEFUL_RESTART) &&
+		CHECK_FLAG(bm->flags, BM_FLAG_GR_COMPLETE));
+}
+
+static inline void bgp_update_gr_completion(void)
+{
+	struct listnode *node, *nnode;
+	struct bgp *bgp;
+
+	/*
+	 * Check and mark GR complete. This is done when deferred
+	 * path selection has been completed for all instances and
+	 * route-advertisement/EOR and route-sync with zebra has
+	 * been invoked.
+	 */
+	if (!CHECK_FLAG(bm->flags, BM_FLAG_GRACEFUL_RESTART) ||
+	    CHECK_FLAG(bm->flags, BM_FLAG_GR_COMPLETE))
+		return;
+
+	for (ALL_LIST_ELEMENTS(bm->bgp, node, nnode, bgp)) {
+		if (bgp->gr_route_sync_pending)
+			return;
+	}
+
+	SET_FLAG(bm->flags, BM_FLAG_GR_COMPLETE);
+	bm->gr_completion_time = monotime(NULL);
+}
+
+static inline bool bgp_gr_is_forwarding_preserved(struct bgp *bgp)
+{
+	/*
+	 * Is forwarding state preserved? Based either on config
+	 * or if BGP restarted gracefully.
+	 * TBD: Additional AFI/SAFI based checks etc.
+	 */
+	return (CHECK_FLAG(bm->flags, BM_FLAG_GRACEFUL_RESTART) ||
+		CHECK_FLAG(bgp->flags, BGP_FLAG_GR_PRESERVE_FWD));
+}
+
 /* For benefit of rfapi */
 extern struct peer *peer_new(struct bgp *bgp);