cmd/network: Consider max checkpoint creation time for trust

Prevents a problem where the most recent checkpoint target height
is still being created on the remote nodes, but second oldest
target height would be already older than the suggested trust.

This is only relevant when configuring runtime where state is much
bigger. In such case if you are connected to remote nodes that
preserve many runtime state versions, checkpoint creation time is
significant.

Author: martintomazic

cmd/network/trust.go

@@ -20,6 +20,11 @@ const (
 	// be able to fetch and verify light headers and finally detect and penalize a possible
 	// byzantine behavior. This value intentionally overestimates the actual time required.
 	maxVerificationTime = 24 * time.Hour
+
+	// maxCpCreationTime defines the upper bound within which remote node should produce
+	// checkpoint. This value intentionally overestimates the actual time required,
+	// assuming nodes with very bulky NodeDB, where checkpoint creation is slow.
+	maxCpCreationTime = 36 * time.Hour
 )
 
 var trustCmd = &cobra.Command{
@@ -94,11 +99,12 @@ func calcTrust(ctx context.Context, conn connection.Connection) (config.TrustCon
 	}
 	trustPeriod := calcTrustPeriod(debondingPeriod)
 
-	// Going back the whole checkpoint interval guarantees there should be at least
-	// one target checkpoint height inside this interval.
-	candidate, err := conn.Consensus().Core().GetBlock(ctx, latest.Height-cpInterval)
+	// Going back the whole checkpoint interval plus max checkpoint creation time guarantees there wil be at least
+	// one target checkpoint height from the trust height onwards, for which remote nodes already created a checkpoint.
+	candidateHeight := latest.Height - cpInterval - int64(maxCpCreationTime/blkTime)
+	candidate, err := conn.Consensus().Core().GetBlock(ctx, candidateHeight)
 	if err != nil {
-		return config.TrustConfig{}, fmt.Errorf("failed to get candidate trust (height: %d): %w", candidate.Height, err)
+		return config.TrustConfig{}, fmt.Errorf("failed to get candidate trust (height: %d): %w", candidateHeight, err)
 	}
 
 	// Sanity check: the trusted root must not be older than the sum of the trust