[DEV-25] Modified accept.go to account for multiple previous hashes..

blockdag/accept.go

@@ -24,61 +24,72 @@ import (
 func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
 	// The height of this block is one more than the referenced previous
 	// block.
-	prevHash := &block.MsgBlock().Header.PrevBlock
-	prevNode := b.index.LookupNode(prevHash)
-	if prevNode == nil {
-		str := fmt.Sprintf("previous block %s is unknown", prevHash)
-		return false, ruleError(ErrPreviousBlockUnknown, str)
-	} else if b.index.NodeStatus(prevNode).KnownInvalid() {
-		str := fmt.Sprintf("previous block %s is known to be invalid", prevHash)
-		return false, ruleError(ErrInvalidAncestorBlock, str)
-	}
+	prevHeader := &block.MsgBlock().Header
+	numPrevHashes := prevHeader.NumPrevBlocks
+	prevHashes := prevHeader.PrevBlocks
 
-	blockHeight := prevNode.height + 1
-	block.SetHeight(blockHeight)
+	var isMainChain bool
+	for i := byte(0); i < numPrevHashes; i++ {
+		prevHash := prevHashes[i]
+		node := b.index.LookupNode(&prevHash)
+		if node == nil {
+			str := fmt.Sprintf("previous block %s is unknown", prevHashes)
+			return false, ruleError(ErrPreviousBlockUnknown, str)
+		} else if b.index.NodeStatus(node).KnownInvalid() {
+			str := fmt.Sprintf("previous block %s is known to be invalid", prevHashes)
+			return false, ruleError(ErrInvalidAncestorBlock, str)
+		}
 
-	// The block must pass all of the validation rules which depend on the
-	// position of the block within the block chain.
-	err := b.checkBlockContext(block, prevNode, flags)
-	if err != nil {
-		return false, err
-	}
+		blockHeight := node.height + 1
+		block.SetHeight(blockHeight)
 
-	// Insert the block into the database if it's not already there.  Even
-	// though it is possible the block will ultimately fail to connect, it
-	// has already passed all proof-of-work and validity tests which means
-	// it would be prohibitively expensive for an attacker to fill up the
-	// disk with a bunch of blocks that fail to connect.  This is necessary
-	// since it allows block download to be decoupled from the much more
-	// expensive connection logic.  It also has some other nice properties
-	// such as making blocks that never become part of the main chain or
-	// blocks that fail to connect available for further analysis.
-	err = b.db.Update(func(dbTx database.Tx) error {
-		return dbStoreBlock(dbTx, block)
-	})
-	if err != nil {
-		return false, err
-	}
+		// The block must pass all of the validation rules which depend on the
+		// position of the block within the block chain.
+		err := b.checkBlockContext(block, node, flags)
+		if err != nil {
+			return false, err
+		}
 
-	// Create a new block node for the block and add it to the node index. Even
-	// if the block ultimately gets connected to the main chain, it starts out
-	// on a side chain.
-	blockHeader := &block.MsgBlock().Header
-	newNode := newBlockNode(blockHeader, prevNode)
-	newNode.status = statusDataStored
+		// Insert the block into the database if it's not already there.  Even
+		// though it is possible the block will ultimately fail to connect, it
+		// has already passed all proof-of-work and validity tests which means
+		// it would be prohibitively expensive for an attacker to fill up the
+		// disk with a bunch of blocks that fail to connect.  This is necessary
+		// since it allows block download to be decoupled from the much more
+		// expensive connection logic.  It also has some other nice properties
+		// such as making blocks that never become part of the main chain or
+		// blocks that fail to connect available for further analysis.
+		err = b.db.Update(func(dbTx database.Tx) error {
+			return dbStoreBlock(dbTx, block)
+		})
+		if err != nil {
+			return false, err
+		}
 
-	b.index.AddNode(newNode)
-	err = b.index.flushToDB()
-	if err != nil {
-		return false, err
-	}
+		// Create a new block node for the block and add it to the node index. Even
+		// if the block ultimately gets connected to the main chain, it starts out
+		// on a side chain.
+		blockHeader := &block.MsgBlock().Header
+		newNode := newBlockNode(blockHeader, node)
+		newNode.status = statusDataStored
 
-	// Connect the passed block to the chain while respecting proper chain
-	// selection according to the chain with the most proof of work.  This
-	// also handles validation of the transaction scripts.
-	isMainChain, err := b.connectBestChain(newNode, block, flags)
-	if err != nil {
-		return false, err
+		b.index.AddNode(newNode)
+		err = b.index.flushToDB()
+		if err != nil {
+			return false, err
+		}
+
+		// Connect the passed block to the chain while respecting proper chain
+		// selection according to the chain with the most proof of work.  This
+		// also handles validation of the transaction scripts.
+		isMainChain, err := b.connectBestChain(newNode, block, flags)
+		if err != nil {
+			return false, err
+		}
+
+		if !isMainChain {
+			break
+		}
 	}
 
 	// Notify the caller that the new block was accepted into the block