Golang Block.Transactions方法代码示例

// checkBIP0030 ensures blocks do not contain duplicate transactions which
// 'overwrite' older transactions that are not fully spent.  This prevents an
// attack where a coinbase and all of its dependent transactions could be
// duplicated to effectively revert the overwritten transactions to a single
// confirmation thereby making them vulnerable to a double spend.
//
// For more details, see https://en.bitcoin.it/wiki/BIP_0030 and
// http://r6.ca/blog/20120206T005236Z.html.
//
// This function MUST be called with the chain state lock held (for reads).
func (b *BlockChain) checkBIP0030(node *blockNode, block *btcutil.Block, view *UtxoViewpoint) error {
	// Fetch utxo details for all of the transactions in this block.
	// Typically, there will not be any utxos for any of the transactions.
	fetchSet := make(map[chainhash.Hash]struct{})
	for _, tx := range block.Transactions() {
		fetchSet[*tx.Hash()] = struct{}{}
	}
	err := view.fetchUtxos(b.db, fetchSet)
	if err != nil {
		return err
	}

	// Duplicate transactions are only allowed if the previous transaction
	// is fully spent.
	for _, tx := range block.Transactions() {
		txEntry := view.LookupEntry(tx.Hash())
		if txEntry != nil && !txEntry.IsFullySpent() {
			str := fmt.Sprintf("tried to overwrite transaction %v "+
				"at block height %d that is not fully spent",
				tx.Hash(), txEntry.blockHeight)
			return ruleError(ErrOverwriteTx, str)
		}
	}

	return nil
}

// indexBlock extract all of the standard addresses from all of the transactions
// in the passed block and maps each of them to the assocaited transaction using
// the passed map.
func (idx *AddrIndex) indexBlock(data writeIndexData, block *btcutil.Block, view *blockchain.UtxoViewpoint) {
	for txIdx, tx := range block.Transactions() {
		// Coinbases do not reference any inputs.  Since the block is
		// required to have already gone through full validation, it has
		// already been proven on the first transaction in the block is
		// a coinbase.
		if txIdx != 0 {
			for _, txIn := range tx.MsgTx().TxIn {
				// The view should always have the input since
				// the index contract requires it, however, be
				// safe and simply ignore any missing entries.
				origin := &txIn.PreviousOutPoint
				entry := view.LookupEntry(&origin.Hash)
				if entry == nil {
					continue
				}

				pkScript := entry.PkScriptByIndex(origin.Index)
				idx.indexPkScript(data, pkScript, txIdx)
			}
		}

		for _, txOut := range tx.MsgTx().TxOut {
			idx.indexPkScript(data, txOut.PkScript, txIdx)
		}
	}
}

// dbAddTxIndexEntries uses an existing database transaction to add a
// transaction index entry for every transaction in the passed block.
func dbAddTxIndexEntries(dbTx database.Tx, block *btcutil.Block, blockID uint32) error {
	// The offset and length of the transactions within the serialized
	// block.
	txLocs, err := block.TxLoc()
	if err != nil {
		return err
	}

	// As an optimization, allocate a single slice big enough to hold all
	// of the serialized transaction index entries for the block and
	// serialize them directly into the slice.  Then, pass the appropriate
	// subslice to the database to be written.  This approach significantly
	// cuts down on the number of required allocations.
	offset := 0
	serializedValues := make([]byte, len(block.Transactions())*txEntrySize)
	for i, tx := range block.Transactions() {
		putTxIndexEntry(serializedValues[offset:], blockID, txLocs[i])
		endOffset := offset + txEntrySize
		err := dbPutTxIndexEntry(dbTx, tx.Hash(),
			serializedValues[offset:endOffset:endOffset])
		if err != nil {
			return err
		}
		offset += txEntrySize
	}

	return nil
}

// makeUtxoView creates a mock unspent transaction output view by using the
// transaction index in order to look up all inputs referenced by the
// transactions in the block.  This is sometimes needed when catching indexes up
// because many of the txouts could actually already be spent however the
// associated scripts are still required to index them.
func makeUtxoView(dbTx database.Tx, block *btcutil.Block) (*blockchain.UtxoViewpoint, error) {
	view := blockchain.NewUtxoViewpoint()
	for txIdx, tx := range block.Transactions() {
		// Coinbases do not reference any inputs.  Since the block is
		// required to have already gone through full validation, it has
		// already been proven on the first transaction in the block is
		// a coinbase.
		if txIdx == 0 {
			continue
		}

		// Use the transaction index to load all of the referenced
		// inputs and add their outputs to the view.
		for _, txIn := range tx.MsgTx().TxIn {
			originOut := &txIn.PreviousOutPoint
			originTx, err := dbFetchTx(dbTx, &originOut.Hash)
			if err != nil {
				return nil, err
			}

			view.AddTxOuts(btcutil.NewTx(originTx), 0)
		}
	}

	return view, nil
}

func assertTxInBlock(t *harnessTest, block *btcutil.Block, txid *wire.ShaHash) {
	for _, tx := range block.Transactions() {
		if bytes.Equal(txid[:], tx.Sha()[:]) {
			return
		}
	}

	t.Fatalf("funding tx was not included in block")
}

// dbRemoveTxIndexEntries uses an existing database transaction to remove the
// latest transaction entry for every transaction in the passed block.
func dbRemoveTxIndexEntries(dbTx database.Tx, block *btcutil.Block) error {
	for _, tx := range block.Transactions() {
		err := dbRemoveTxIndexEntry(dbTx, tx.Hash())
		if err != nil {
			return err
		}
	}

	return nil
}

// connectTransactions updates the view by adding all new utxos created by all
// of the transactions in the passed block, marking all utxos the transactions
// spend as spent, and setting the best hash for the view to the passed block.
// In addition, when the 'stxos' argument is not nil, it will be updated to
// append an entry for each spent txout.
func (view *UtxoViewpoint) connectTransactions(block *btcutil.Block, stxos *[]spentTxOut) error {
	for _, tx := range block.Transactions() {
		err := view.connectTransaction(tx, block.Height(), stxos)
		if err != nil {
			return err
		}
	}

	// Update the best hash for view to include this block since all of its
	// transactions have been connected.
	view.SetBestHash(block.Hash())
	return nil
}

// fetchInputUtxos loads utxo details about the input transactions referenced
// by the transactions in the given block into the view from the database as
// needed.  In particular, referenced entries that are earlier in the block are
// added to the view and entries that are already in the view are not modified.
func (view *UtxoViewpoint) fetchInputUtxos(db database.DB, block *btcutil.Block) error {
	// Build a map of in-flight transactions because some of the inputs in
	// this block could be referencing other transactions earlier in this
	// block which are not yet in the chain.
	txInFlight := map[chainhash.Hash]int{}
	transactions := block.Transactions()
	for i, tx := range transactions {
		txInFlight[*tx.Hash()] = i
	}

	// Loop through all of the transaction inputs (except for the coinbase
	// which has no inputs) collecting them into sets of what is needed and
	// what is already known (in-flight).
	txNeededSet := make(map[chainhash.Hash]struct{})
	for i, tx := range transactions[1:] {
		for _, txIn := range tx.MsgTx().TxIn {
			// It is acceptable for a transaction input to reference
			// the output of another transaction in this block only
			// if the referenced transaction comes before the
			// current one in this block.  Add the outputs of the
			// referenced transaction as available utxos when this
			// is the case.  Otherwise, the utxo details are still
			// needed.
			//
			// NOTE: The >= is correct here because i is one less
			// than the actual position of the transaction within
			// the block due to skipping the coinbase.
			originHash := &txIn.PreviousOutPoint.Hash
			if inFlightIndex, ok := txInFlight[*originHash]; ok &&
				i >= inFlightIndex {

				originTx := transactions[inFlightIndex]
				view.AddTxOuts(originTx, block.Height())
				continue
			}

			// Don't request entries that are already in the view
			// from the database.
			if _, ok := view.entries[*originHash]; ok {
				continue
			}

			txNeededSet[*originHash] = struct{}{}
		}
	}

	// Request the input utxos from the database.
	return view.fetchUtxosMain(db, txNeededSet)
}

// ValidateWitnessCommitment validates the witness commitment (if any) found
// within the coinbase transaction of the passed block.
func ValidateWitnessCommitment(blk *btcutil.Block) error {
	coinbaseTx := blk.Transactions()[0]
	witnessCommitment, witnessFound := ExtractWitnessCommitment(coinbaseTx)

	// If we can't find a witness commitment in any of the coinbase's
	// outputs, then the block MUST NOT contain any transactions with
	// witness data.
	if !witnessFound {
		for _, tx := range blk.Transactions() {
			msgTx := tx.MsgTx()
			if msgTx.HasWitness() {
				str := fmt.Sprintf("block contains transaction with witness" +
					" data, yet no witness commitment present")
				return ruleError(ErrUnexpectedWitness, str)
			}
		}
		return nil
	}

	// At this point the block contains a witness commitment, so the
	// coinbase transaction MUST have exactly one witness element within
	// its witness data and that element must be exactly
	// CoinbaseWitnessDataLen bytes.
	coinbaseWitness := coinbaseTx.MsgTx().TxIn[0].Witness
	if len(coinbaseWitness) != 1 {
		str := fmt.Sprintf("the coinbase transaction has %d items in "+
			"its witness stack when only one is allowed",
			len(coinbaseWitness))
		return ruleError(ErrInvalidWitnessCommitment, str)
	}
	witnessNonce := coinbaseWitness[0]
	if len(witnessNonce) != CoinbaseWitnessDataLen {
		str := fmt.Sprintf("the coinbase transaction witness nonce "+
			"has %d bytes when it must be %d bytes",
			len(witnessNonce), CoinbaseWitnessDataLen)
		return ruleError(ErrInvalidWitnessCommitment, str)
	}

	// Finally, with the preliminary checks out of the way, we can check if
	// the extracted witnessCommitment is equal to:
	// SHA256(witnessMerkleRoot || witnessNonce). Where witnessNonce is the
	// coinbase transaction's only witness item.
	witnessMerkleTree := BuildMerkleTreeStore(blk.Transactions(), true)
	witnessMerkleRoot := witnessMerkleTree[len(witnessMerkleTree)-1]

	witnessPreimage := make([]byte, 64)
	copy(witnessPreimage[:], witnessMerkleRoot[:])
	copy(witnessPreimage[32:], witnessNonce)

	if !bytes.Equal(chainhash.DoubleHashB(witnessPreimage), witnessCommitment) {
		str := "witness commitment does not match"
		return ruleError(ErrWitnessCommitmentMismatch, str)
	}

	return nil
}

// IsCheckpointCandidate returns whether or not the passed block is a good
// checkpoint candidate.
//
// The factors used to determine a good checkpoint are:
//  - The block must be in the main chain
//  - The block must be at least 'CheckpointConfirmations' blocks prior to the
//    current end of the main chain
//  - The timestamps for the blocks before and after the checkpoint must have
//    timestamps which are also before and after the checkpoint, respectively
//    (due to the median time allowance this is not always the case)
//  - The block must not contain any strange transaction such as those with
//    nonstandard scripts
//
// The intent is that candidates are reviewed by a developer to make the final
// decision and then manually added to the list of checkpoints for a network.
//
// This function is safe for concurrent access.
func (b *BlockChain) IsCheckpointCandidate(block *btcutil.Block) (bool, error) {
	b.chainLock.RLock()
	defer b.chainLock.RUnlock()

	// Checkpoints must be enabled.
	if b.noCheckpoints {
		return false, fmt.Errorf("checkpoints are disabled")
	}

	var isCandidate bool
	err := b.db.View(func(dbTx database.Tx) error {
		// A checkpoint must be in the main chain.
		blockHeight, err := dbFetchHeightByHash(dbTx, block.Hash())
		if err != nil {
			// Only return an error if it's not due to the block not
			// being in the main chain.
			if !isNotInMainChainErr(err) {
				return err
			}
			return nil
		}

		// Ensure the height of the passed block and the entry for the
		// block in the main chain match.  This should always be the
		// case unless the caller provided an invalid block.
		if blockHeight != block.Height() {
			return fmt.Errorf("passed block height of %d does not "+
				"match the main chain height of %d",
				block.Height(), blockHeight)
		}

		// A checkpoint must be at least CheckpointConfirmations blocks
		// before the end of the main chain.
		mainChainHeight := b.bestNode.height
		if blockHeight > (mainChainHeight - CheckpointConfirmations) {
			return nil
		}

		// Get the previous block header.
		prevHash := &block.MsgBlock().Header.PrevBlock
		prevHeader, err := dbFetchHeaderByHash(dbTx, prevHash)
		if err != nil {
			return err
		}

		// Get the next block header.
		nextHeader, err := dbFetchHeaderByHeight(dbTx, blockHeight+1)
		if err != nil {
			return err
		}

		// A checkpoint must have timestamps for the block and the
		// blocks on either side of it in order (due to the median time
		// allowance this is not always the case).
		prevTime := prevHeader.Timestamp
		curTime := block.MsgBlock().Header.Timestamp
		nextTime := nextHeader.Timestamp
		if prevTime.After(curTime) || nextTime.Before(curTime) {
			return nil
		}

		// A checkpoint must have transactions that only contain
		// standard scripts.
		for _, tx := range block.Transactions() {
			if isNonstandardTransaction(tx) {
				return nil
			}
		}

		// All of the checks passed, so the block is a candidate.
		isCandidate = true
		return nil
	})
	return isCandidate, err
}

// checkBlockScripts executes and validates the scripts for all transactions in
// the passed block using multiple goroutines.
func checkBlockScripts(block *btcutil.Block, utxoView *UtxoViewpoint,
	scriptFlags txscript.ScriptFlags, sigCache *txscript.SigCache,
	hashCache *txscript.HashCache) error {

	// First determine if segwit is active according to the scriptFlags. If
	// it isn't then we don't need to interact with the HashCache.
	segwitActive := scriptFlags&txscript.ScriptVerifyWitness == txscript.ScriptVerifyWitness

	// Collect all of the transaction inputs and required information for
	// validation for all transactions in the block into a single slice.
	numInputs := 0
	for _, tx := range block.Transactions() {
		numInputs += len(tx.MsgTx().TxIn)
	}
	txValItems := make([]*txValidateItem, 0, numInputs)
	for _, tx := range block.Transactions() {
		sha := tx.Hash()

		// If the HashCache is present, and it doesn't yet contain the
		// partial sighashes for this transaction, then we add the
		// sighashes for the transaction. This allows us to take
		// advantage of the potential speed savings due to the new
		// digest algorithm (BIP0143).
		if segwitActive && hashCache != nil &&
			!hashCache.ContainsHashes(sha) {
			hashCache.AddSigHashes(tx.MsgTx())
		}

		var cachedHashes *txscript.TxSigHashes
		if segwitActive {
			if hashCache != nil {
				cachedHashes, _ = hashCache.GetSigHashes(sha)
			} else {
				cachedHashes = txscript.NewTxSigHashes(tx.MsgTx())
			}
		}

		for txInIdx, txIn := range tx.MsgTx().TxIn {
			// Skip coinbases.
			if txIn.PreviousOutPoint.Index == math.MaxUint32 {
				continue
			}

			txVI := &txValidateItem{
				txInIndex: txInIdx,
				txIn:      txIn,
				tx:        tx,
				sigHashes: cachedHashes,
			}
			txValItems = append(txValItems, txVI)
		}
	}

	// Validate all of the inputs.
	validator := newTxValidator(utxoView, scriptFlags, sigCache, hashCache)
	start := time.Now()
	if err := validator.Validate(txValItems); err != nil {
		return err
	}
	elapsed := time.Since(start)

	log.Tracef("block %v took %v to verify", block.Hash(), elapsed)

	// If the HashCache is present, once we have validated the block, we no
	// longer need the cached hashes for these transactions, so we purge
	// them from the cache.
	if segwitActive && hashCache != nil {
		for _, tx := range block.Transactions() {
			hashCache.PurgeSigHashes(tx.Hash())
		}
	}

	return nil
}

// disconnectTransactions updates the view by removing all of the transactions
// created by the passed block, restoring all utxos the transactions spent by
// using the provided spent txo information, and setting the best hash for the
// view to the block before the passed block.
func (view *UtxoViewpoint) disconnectTransactions(block *btcutil.Block, stxos []spentTxOut) error {
	// Sanity check the correct number of stxos are provided.
	if len(stxos) != countSpentOutputs(block) {
		return AssertError("disconnectTransactions called with bad " +
			"spent transaction out information")
	}

	// Loop backwards through all transactions so everything is unspent in
	// reverse order.  This is necessary since transactions later in a block
	// can spend from previous ones.
	stxoIdx := len(stxos) - 1
	transactions := block.Transactions()
	for txIdx := len(transactions) - 1; txIdx > -1; txIdx-- {
		tx := transactions[txIdx]

		// Clear this transaction from the view if it already exists or
		// create a new empty entry for when it does not.  This is done
		// because the code relies on its existence in the view in order
		// to signal modifications have happened.
		isCoinbase := txIdx == 0
		entry := view.entries[*tx.Hash()]
		if entry == nil {
			entry = newUtxoEntry(tx.MsgTx().Version, isCoinbase,
				block.Height())
			view.entries[*tx.Hash()] = entry
		}
		entry.modified = true
		entry.sparseOutputs = make(map[uint32]*utxoOutput)

		// Loop backwards through all of the transaction inputs (except
		// for the coinbase which has no inputs) and unspend the
		// referenced txos.  This is necessary to match the order of the
		// spent txout entries.
		if isCoinbase {
			continue
		}
		for txInIdx := len(tx.MsgTx().TxIn) - 1; txInIdx > -1; txInIdx-- {
			// Ensure the spent txout index is decremented to stay
			// in sync with the transaction input.
			stxo := &stxos[stxoIdx]
			stxoIdx--

			// When there is not already an entry for the referenced
			// transaction in the view, it means it was fully spent,
			// so create a new utxo entry in order to resurrect it.
			txIn := tx.MsgTx().TxIn[txInIdx]
			originHash := &txIn.PreviousOutPoint.Hash
			originIndex := txIn.PreviousOutPoint.Index
			entry := view.entries[*originHash]
			if entry == nil {
				entry = newUtxoEntry(stxo.version,
					stxo.isCoinBase, stxo.height)
				view.entries[*originHash] = entry
			}

			// Mark the entry as modified since it is either new
			// or will be changed below.
			entry.modified = true

			// Restore the specific utxo using the stxo data from
			// the spend journal if it doesn't already exist in the
			// view.
			output, ok := entry.sparseOutputs[originIndex]
			if !ok {
				// Add the unspent transaction output.
				entry.sparseOutputs[originIndex] = &utxoOutput{
					spent:      false,
					compressed: stxo.compressed,
					amount:     stxo.amount,
					pkScript:   stxo.pkScript,
				}
				continue
			}

			// Mark the existing referenced transaction output as
			// unspent.
			output.spent = false
		}
	}

	// Update the best hash for view to the previous block since all of the
	// transactions for the current block have been disconnected.
	view.SetBestHash(&block.MsgBlock().Header.PrevBlock)
	return nil
}

// checkBlockContext peforms several validation checks on the block which depend
// on its position within the block chain.
//
// The flags modify the behavior of this function as follows:
//  - BFFastAdd: The transaction are not checked to see if they are finalized
//    and the somewhat expensive BIP0034 validation is not performed.
//
// The flags are also passed to checkBlockHeaderContext.  See its documentation
// for how the flags modify its behavior.
//
// This function MUST be called with the chain state lock held (for writes).
func (b *BlockChain) checkBlockContext(block *btcutil.Block, prevNode *blockNode, flags BehaviorFlags) error {
	// The genesis block is valid by definition.
	if prevNode == nil {
		return nil
	}

	// Perform all block header related validation checks.
	header := &block.MsgBlock().Header
	err := b.checkBlockHeaderContext(header, prevNode, flags)
	if err != nil {
		return err
	}

	// Query for the Version Bits state for the segwit soft-fork
	// deployment. If segwit is active, we'll switch over to enforcing all
	// the new rules.
	segwitState, err := b.deploymentState(prevNode, chaincfg.DeploymentSegwit)
	if err != nil {
		return err
	}

	// If segwit is active, then we'll need to fully validate the new
	// witness commitment for adherance to the rules.
	if segwitState == ThresholdActive {
		// Validate the witness commitment (if any) within the block.
		// This involves asserting that if the coinbase contains the
		// special commitment output, then this merkle root matches a
		// computed merkle root of all the wtxid's of the transactions
		// within the block. In addition, various other checks against
		// the coinbase's witness stack.
		if err := ValidateWitnessCommitment(block); err != nil {
			return err
		}
	}

	fastAdd := flags&BFFastAdd == BFFastAdd
	if !fastAdd {
		// Obtain the latest state of the deployed CSV soft-fork in
		// order to properly guard the new validation behavior based on
		// the current BIP 9 version bits state.
		csvState, err := b.deploymentState(prevNode, chaincfg.DeploymentCSV)
		if err != nil {
			return err
		}

		// Once the CSV soft-fork is fully active, we'll switch to
		// using the current median time past of the past block's
		// timestamps for all lock-time based checks.
		blockTime := header.Timestamp
		if csvState == ThresholdActive {
			medianTime, err := b.calcPastMedianTime(prevNode)
			if err != nil {
				return err
			}

			blockTime = medianTime
		}

		// The height of this block is one more than the referenced
		// previous block.
		blockHeight := prevNode.height + 1

		// Ensure all transactions in the block are finalized.
		for _, tx := range block.Transactions() {
			if !IsFinalizedTransaction(tx, blockHeight,
				blockTime) {

				str := fmt.Sprintf("block contains unfinalized "+
					"transaction %v", tx.Hash())
				return ruleError(ErrUnfinalizedTx, str)
			}
		}

		// Ensure coinbase starts with serialized block heights for
		// blocks whose version is the serializedHeightVersion or newer
		// once a majority of the network has upgraded.  This is part of
		// BIP0034.
		if ShouldHaveSerializedBlockHeight(header) &&
			blockHeight >= b.chainParams.BIP0034Height {

			coinbaseTx := block.Transactions()[0]
			err := checkSerializedHeight(coinbaseTx, blockHeight)
			if err != nil {
				return err
			}
		}
	}

	return nil
//.........这里部分代码省略.........

// checkBlockSanity performs some preliminary checks on a block to ensure it is
// sane before continuing with block processing.  These checks are context free.
//
// The flags do not modify the behavior of this function directly, however they
// are needed to pass along to checkBlockHeaderSanity.
func checkBlockSanity(block *btcutil.Block, powLimit *big.Int, timeSource MedianTimeSource, flags BehaviorFlags) error {
	msgBlock := block.MsgBlock()
	header := &msgBlock.Header
	err := checkBlockHeaderSanity(header, powLimit, timeSource, flags)
	if err != nil {
		return err
	}

	// A block must have at least one transaction.
	numTx := len(msgBlock.Transactions)
	if numTx == 0 {
		return ruleError(ErrNoTransactions, "block does not contain "+
			"any transactions")
	}

	// A block must not have more transactions than the max block payload.
	if numTx > wire.MaxBlockPayload {
		str := fmt.Sprintf("block contains too many transactions - "+
			"got %d, max %d", numTx, wire.MaxBlockPayload)
		return ruleError(ErrTooManyTransactions, str)
	}

	// A block must not exceed the maximum allowed block payload when
	// serialized.
	serializedSize := msgBlock.SerializeSizeStripped()
	if serializedSize > MaxBlockBaseSize {
		str := fmt.Sprintf("serialized block is too big - got %d, "+
			"max %d", serializedSize, MaxBlockBaseSize)
		return ruleError(ErrBlockTooBig, str)
	}

	// The first transaction in a block must be a coinbase.
	transactions := block.Transactions()
	if !IsCoinBase(transactions[0]) {
		return ruleError(ErrFirstTxNotCoinbase, "first transaction in "+
			"block is not a coinbase")
	}

	// A block must not have more than one coinbase.
	for i, tx := range transactions[1:] {
		if IsCoinBase(tx) {
			str := fmt.Sprintf("block contains second coinbase at "+
				"index %d", i+1)
			return ruleError(ErrMultipleCoinbases, str)
		}
	}

	// Do some preliminary checks on each transaction to ensure they are
	// sane before continuing.
	for _, tx := range transactions {
		err := CheckTransactionSanity(tx)
		if err != nil {
			return err
		}
	}

	// Build merkle tree and ensure the calculated merkle root matches the
	// entry in the block header.  This also has the effect of caching all
	// of the transaction hashes in the block to speed up future hash
	// checks.  Bitcoind builds the tree here and checks the merkle root
	// after the following checks, but there is no reason not to check the
	// merkle root matches here.
	merkles := BuildMerkleTreeStore(block.Transactions(), false)
	calculatedMerkleRoot := merkles[len(merkles)-1]
	if !header.MerkleRoot.IsEqual(calculatedMerkleRoot) {
		str := fmt.Sprintf("block merkle root is invalid - block "+
			"header indicates %v, but calculated value is %v",
			header.MerkleRoot, calculatedMerkleRoot)
		return ruleError(ErrBadMerkleRoot, str)
	}

	// Check for duplicate transactions.  This check will be fairly quick
	// since the transaction hashes are already cached due to building the
	// merkle tree above.
	existingTxHashes := make(map[chainhash.Hash]struct{})
	for _, tx := range transactions {
		hash := tx.Hash()
		if _, exists := existingTxHashes[*hash]; exists {
			str := fmt.Sprintf("block contains duplicate "+
				"transaction %v", hash)
			return ruleError(ErrDuplicateTx, str)
		}
		existingTxHashes[*hash] = struct{}{}
	}

	// The number of signature operations must be less than the maximum
	// allowed per block.
	totalSigOps := 0
	for _, tx := range transactions {
		// We could potentially overflow the accumulator so check for
		// overflow.
		lastSigOps := totalSigOps
		totalSigOps += (CountSigOps(tx) * WitnessScaleFactor)
		if totalSigOps < lastSigOps || totalSigOps > MaxBlockSigOpsCost {
			str := fmt.Sprintf("block contains too many signature "+
//.........这里部分代码省略.........

// checkConnectBlock performs several checks to confirm connecting the passed
// block to the chain represented by the passed view does not violate any rules.
// In addition, the passed view is updated to spend all of the referenced
// outputs and add all of the new utxos created by block.  Thus, the view will
// represent the state of the chain as if the block were actually connected and
// consequently the best hash for the view is also updated to passed block.
//
// The CheckConnectBlock function makes use of this function to perform the
// bulk of its work.  The only difference is this function accepts a node which
// may or may not require reorganization to connect it to the main chain whereas
// CheckConnectBlock creates a new node which specifically connects to the end
// of the current main chain and then calls this function with that node.
//
// See the comments for CheckConnectBlock for some examples of the type of
// checks performed by this function.
//
// This function MUST be called with the chain state lock held (for writes).
func (b *BlockChain) checkConnectBlock(node *blockNode, block *btcutil.Block, view *UtxoViewpoint, stxos *[]spentTxOut) error {
	// If the side chain blocks end up in the database, a call to
	// CheckBlockSanity should be done here in case a previous version
	// allowed a block that is no longer valid.  However, since the
	// implementation only currently uses memory for the side chain blocks,
	// it isn't currently necessary.

	// The coinbase for the Genesis block is not spendable, so just return
	// an error now.
	if node.hash.IsEqual(b.chainParams.GenesisHash) {
		str := "the coinbase for the genesis block is not spendable"
		return ruleError(ErrMissingTx, str)
	}

	// Ensure the view is for the node being checked.
	if !view.BestHash().IsEqual(node.parentHash) {
		return AssertError(fmt.Sprintf("inconsistent view when "+
			"checking block connection: best hash is %v instead "+
			"of expected %v", view.BestHash(), node.hash))
	}

	// BIP0030 added a rule to prevent blocks which contain duplicate
	// transactions that 'overwrite' older transactions which are not fully
	// spent.  See the documentation for checkBIP0030 for more details.
	//
	// There are two blocks in the chain which violate this rule, so the
	// check must be skipped for those blocks.  The isBIP0030Node function
	// is used to determine if this block is one of the two blocks that must
	// be skipped.
	//
	// In addition, as of BIP0034, duplicate coinbases are no longer
	// possible due to its requirement for including the block height in the
	// coinbase and thus it is no longer possible to create transactions
	// that 'overwrite' older ones.  Therefore, only enforce the rule if
	// BIP0034 is not yet active.  This is a useful optimization because the
	// BIP0030 check is expensive since it involves a ton of cache misses in
	// the utxoset.
	if !isBIP0030Node(node) && (node.height < b.chainParams.BIP0034Height) {
		err := b.checkBIP0030(node, block, view)
		if err != nil {
			return err
		}
	}

	// Load all of the utxos referenced by the inputs for all transactions
	// in the block don't already exist in the utxo view from the database.
	//
	// These utxo entries are needed for verification of things such as
	// transaction inputs, counting pay-to-script-hashes, and scripts.
	err := view.fetchInputUtxos(b.db, block)
	if err != nil {
		return err
	}

	// BIP0016 describes a pay-to-script-hash type that is considered a
	// "standard" type.  The rules for this BIP only apply to transactions
	// after the timestamp defined by txscript.Bip16Activation.  See
	// https://en.bitcoin.it/wiki/BIP_0016 for more details.
	enforceBIP0016 := node.timestamp.After(txscript.Bip16Activation)

	// Query for the Version Bits state for the segwit soft-fork
	// deployment. If segwit is active, we'll switch over to enforcing all
	// the new rules.
	segwitState, err := b.deploymentState(node.parent, chaincfg.DeploymentSegwit)
	if err != nil {
		return err
	}
	enforceSegWit := segwitState == ThresholdActive

	// The number of signature operations must be less than the maximum
	// allowed per block.  Note that the preliminary sanity checks on a
	// block also include a check similar to this one, but this check
	// expands the count to include a precise count of pay-to-script-hash
	// signature operations in each of the input transaction public key
	// scripts.
	transactions := block.Transactions()
	totalSigOpCost := 0
	for i, tx := range transactions {
		// Since the first (and only the first) transaction has
		// already been verified to be a coinbase transaction,
		// use i == 0 as an optimization for the flag to
		// countP2SHSigOps for whether or not the transaction is
		// a coinbase transaction rather than having to do a
//.........这里部分代码省略.........