op-node: Don't invoke p2p unsafe sync for old L2 blocks

op-node/node/node.go

@@ -378,12 +378,21 @@ func (n *OpNode) RequestL2Range(ctx context.Context, start, end eth.L2BlockRef)
 		return n.rpcSync.RequestL2Range(ctx, start, end)
 	}
 	if n.p2pNode != nil && n.p2pNode.AltSyncEnabled() {
+		if unixTimeStale(start.Time, 12*time.Hour) {
+			n.log.Debug("ignoring request to sync L2 range, timestamp is too old for p2p", "start", start, "end", end, "start_time", start.Time)
+			return nil
+		}
 		return n.p2pNode.RequestL2Range(ctx, start, end)
 	}
 	n.log.Debug("ignoring request to sync L2 range, no sync method available", "start", start, "end", end)
 	return nil
 }
 
+// unixTimeStale returns true if the unix timestamp is before the current time minus the supplied duration.
+func unixTimeStale(timestamp uint64, duration time.Duration) bool {
+	return time.Unix(int64(timestamp), 0).Before(time.Now().Add(-1 * duration))
+}
+
 func (n *OpNode) P2P() p2p.Node {
 	return n.p2pNode
 }

op-node/node/node_test.go

+package node
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestUnixTimeStale(t *testing.T) {
+	require.True(t, unixTimeStale(1_600_000_000, 1*time.Hour))
+	require.False(t, unixTimeStale(uint64(time.Now().Unix()), 1*time.Hour))
+}