fix: support origin point for chainsync intersect (#296)

Fixes #292

state/chain.go

@@ -40,22 +40,24 @@ func newChainIterator(
 	startPoint ocommon.Point,
 	inclusive bool,
 ) (*ChainIterator, error) {
-	// Lookup start block in metadata DB
-	tmpBlock, err := models.BlockByPoint(ls.db, startPoint)
-	if err != nil {
-		if errors.Is(err, gorm.ErrRecordNotFound) {
-			return nil, ErrBlockNotFound
-		}
-		return nil, err
-	}
 	ci := &ChainIterator{
-		ls:          ls,
-		startPoint:  startPoint,
-		blockNumber: tmpBlock.Number,
+		ls:         ls,
+		startPoint: startPoint,
 	}
-	// Increment next block number is non-inclusive
-	if !inclusive {
-		ci.blockNumber++
+	// Lookup start block in metadata DB if not origin
+	if startPoint.Slot > 0 || len(startPoint.Hash) > 0 {
+		tmpBlock, err := models.BlockByPoint(ls.db, startPoint)
+		if err != nil {
+			if errors.Is(err, gorm.ErrRecordNotFound) {
+				return nil, ErrBlockNotFound
+			}
+			return nil, err
+		}
+		ci.blockNumber = tmpBlock.Number
+		// Increment next block number if non-inclusive
+		if !inclusive {
+			ci.blockNumber++
+		}
 	}
 	return ci, nil
 }

state/state.go

@@ -618,6 +618,7 @@ func (ls *LedgerState) GetIntersectPoint(
 ) (*ocommon.Point, error) {
 	tip := ls.Tip()
 	var ret ocommon.Point
+	foundOrigin := false
 	txn := ls.db.Transaction(false)
 	err := txn.Do(func(txn *database.Txn) error {
 		for _, point := range points {
@@ -629,6 +630,11 @@ func (ls *LedgerState) GetIntersectPoint(
 			if point.Slot < ret.Slot {
 				continue
 			}
+			// Check for special origin point
+			if point.Slot == 0 && len(point.Hash) == 0 {
+				foundOrigin = true
+				continue
+			}
 			// Lookup block in metadata DB
 			tmpBlock, err := models.BlockByPoint(ls.db, point)
 			if err != nil {
@@ -646,7 +652,7 @@ func (ls *LedgerState) GetIntersectPoint(
 	if err != nil {
 		return nil, err
 	}
-	if ret.Slot > 0 {
+	if ret.Slot > 0 || foundOrigin {
 		return &ret, nil
 	}
 	return nil, nil