node/nemtap: prevent zero epoch duration

Fallback to 240 blocks default epoch duration if unexpected zero value received.
Zero value is not acceptable, and it is hard to predict how the system reacts to
it (panic was observed at least once). Refs #3066.

Signed-off-by: Pavel Karpy <[email protected]>

cmd/neofs-node/config.go

@@ -743,6 +743,11 @@ func initBasics(c *cfg, key *keys.PrivateKey, stateStorage *state.PersistentStor
 
 	eDuration, err := nmWrap.EpochDuration()
 	fatalOnErr(err)
+	if eDuration == 0 {
+		c.log.Warn("zero epoch duration received, fallback to default value",
+			zap.Uint64("default applied value", defaultEpochDuration))
+		eDuration = defaultEpochDuration
+	}
 	nState.epochDuration.Store(eDuration)
 
 	ttl := c.applicationConfiguration.fsChain.cacheTTL

cmd/neofs-node/netmap.go

@@ -22,6 +22,11 @@ import (
 	"go.uber.org/zap"
 )
 
+// defaultEpochDuration sets default epoch duration. Should not be used in a
+// normal situations but if no info can be fetched, smth should be used as a
+// fallback value.
+const defaultEpochDuration = 240
+
 // primary solution of local network state dump.
 type networkState struct {
 	epoch         atomic.Uint64

cmd/neofs-node/reputation.go

@@ -230,6 +230,12 @@ func initReputationService(c *cfg) {
 				return
 			}
 
+			if duration == 0 {
+				c.log.Warn("zero epoch duration received, fallback to default value",
+					zap.Uint64("epoch", epoch), zap.Uint64("default applied value", defaultEpochDuration))
+				duration = defaultEpochDuration
+			}
+
 			c.networkState.epochDuration.Store(duration)
 
 			iterations, err := c.cfgNetmap.wrapper.EigenTrustIterations()