Recovers header if hash is not found in DB on startup

core/headerchain.go

@@ -454,9 +454,9 @@ func (hc *HeaderChain) loadLastState() error {
 		if chead := hc.GetHeaderByHash(head); chead != nil {
 			hc.currentHeader.Store(chead)
 		} else {
-			// This is only done if during the stop, currenthead hash was not stored
-			// properly and it doesn't crash the nodes
-			hc.currentHeader.Store(hc.genesisHeader)
+			// Recover the current header
+			log.Info("Recovering Current Header")
+			hc.currentHeader.Store(hc.RecoverCurrentHeader())
 		}
 	}
 
@@ -640,6 +640,30 @@ func (hc *HeaderChain) GetHeaderOrCandidate(hash common.Hash, number uint64) *ty
 	return header
 }
 
+// RecoverCurrentHeader retrieves the current head header of the canonical chain. The
+// header is retrieved from the HeaderChain's internal cache
+func (hc *HeaderChain) RecoverCurrentHeader() *types.Header {
+	// Start logarithmic ascent to find the upper bound
+	high := uint64(1)
+	for hc.GetHeaderByNumber(high) != nil {
+		high *= 2
+	}
+	// Run binary search to find the max header
+	low := high / 2
+	for low <= high {
+		mid := (low + high) / 2
+		if hc.GetHeaderByNumber(mid) != nil {
+			low = mid + 1
+		} else {
+			high = mid - 1
+		}
+	}
+	header := hc.GetHeaderByNumber(high)
+	log.Info("Header Recovered: ", "hash", header.Hash().String())
+
+	return header
+}
+
 // GetHeaderOrCandidateByHash retrieves a block header from the database by hash, caching it if
 // found.
 func (hc *HeaderChain) GetHeaderOrCandidateByHash(hash common.Hash) *types.Header {