Golang Block.MsgBlock方法代码示例

// connectBlock handles connecting the passed node/block to the end of the main
// (best) chain.
func (b *BlockChain) connectBlock(node *blockNode, block *btcutil.Block) error {
	// Make sure it's extending the end of the best chain.
	prevHash := &block.MsgBlock().Header.PrevBlock
	if b.bestChain != nil && !prevHash.IsEqual(b.bestChain.hash) {
		return fmt.Errorf("connectBlock must be called with a block " +
			"that extends the main chain")
	}

	// Insert the block into the database which houses the main chain.
	_, err := b.db.InsertBlock(block)
	if err != nil {
		return err
	}

	// Add the new node to the memory main chain indices for faster
	// lookups.
	node.inMainChain = true
	b.index[*node.hash] = node
	b.depNodes[*prevHash] = append(b.depNodes[*prevHash], node)

	// This node is now the end of the best chain.
	b.bestChain = node

	// Notify the caller that the block was connected to the main chain.
	// The caller would typically want to react with actions such as
	// updating wallets.
	b.sendNotification(NTBlockConnected, block)

	return nil
}

// checkProofOfWork ensures the block header bits which indicate the target
// difficulty is in min/max range and that the block hash is less than the
// target difficulty as claimed.
//
//
// The flags modify the behavior of this function as follows:
//  - BFNoPoWCheck: The check to ensure the block hash is less than the target
//    difficulty is not performed.
func checkProofOfWork(block *btcutil.Block, powLimit *big.Int, flags BehaviorFlags) error {
	// The target difficulty must be larger than zero.
	target := CompactToBig(block.MsgBlock().Header.Bits)
	if target.Sign() <= 0 {
		str := fmt.Sprintf("block target difficulty of %064x is too low",
			target)
		return ruleError(ErrUnexpectedDifficulty, str)
	}

	// The target difficulty must be less than the maximum allowed.
	if target.Cmp(powLimit) > 0 {
		str := fmt.Sprintf("block target difficulty of %064x is "+
			"higher than max of %064x", target, powLimit)
		return ruleError(ErrUnexpectedDifficulty, str)
	}

	// The block hash must be less than the claimed target unless the flag
	// to avoid proof of work checks is set.
	if flags&BFNoPoWCheck != BFNoPoWCheck {
		// The block hash must be less than the claimed target.
		blockHash, err := block.Sha()
		if err != nil {
			return err
		}
		hashNum := ShaHashToBig(blockHash)
		if hashNum.Cmp(target) > 0 {
			str := fmt.Sprintf("block hash of %064x is higher than "+
				"expected max of %064x", hashNum, target)
			return ruleError(ErrHighHash, str)
		}
	}

	return nil
}

// CheckConnectBlock performs several checks to confirm connecting the passed
// block to the main chain does not violate any rules.  An example of some of
// the checks performed are ensuring connecting the block would not cause any
// duplicate transaction hashes for old transactions that aren't already fully
// spent, double spends, exceeding the maximum allowed signature operations
// per block, invalid values in relation to the expected block subsidy, or fail
// transaction script validation.
//
// This function is NOT safe for concurrent access.
func (b *BlockChain) CheckConnectBlock(block *btcutil.Block) error {
	prevNode := b.bestChain
	blockSha, _ := block.Sha()
	newNode := newBlockNode(&block.MsgBlock().Header, blockSha, block.Height())
	if prevNode != nil {
		newNode.parent = prevNode
		newNode.workSum.Add(prevNode.workSum, newNode.workSum)
	}

	return b.checkConnectBlock(newNode, block)
}

// DropAfterBlockBySha will remove any blocks from the database after
// the given block.
func (db *LevelDb) DropAfterBlockBySha(sha *btcwire.ShaHash) (rerr error) {
	db.dbLock.Lock()
	defer db.dbLock.Unlock()
	defer func() {
		if rerr == nil {
			rerr = db.processBatches()
		} else {
			db.lBatch().Reset()
		}
	}()

	startheight := db.nextBlock - 1

	keepidx, err := db.getBlkLoc(sha)
	if err != nil {
		// should the error here be normalized ?
		log.Tracef("block loc failed %v ", sha)
		return err
	}

	for height := startheight; height > keepidx; height = height - 1 {
		var blk *btcutil.Block
		blksha, buf, err := db.getBlkByHeight(height)
		if err != nil {
			return err
		}
		blk, err = btcutil.NewBlockFromBytes(buf)
		if err != nil {
			return err
		}

		for _, tx := range blk.MsgBlock().Transactions {
			err = db.unSpend(tx)
			if err != nil {
				return err
			}
		}
		// rather than iterate the list of tx backward, do it twice.
		for _, tx := range blk.Transactions() {
			var txUo txUpdateObj
			txUo.delete = true
			db.txUpdateMap[*tx.Sha()] = &txUo
		}
		db.lBatch().Delete(shaBlkToKey(blksha))
		db.lBatch().Delete(int64ToKey(height))
	}

	db.nextBlock = keepidx + 1

	return nil
}

// addOrphanBlock adds the passed block (which is already determined to be
// an orphan prior calling this function) to the orphan pool.  It lazily cleans
// up any expired blocks so a separate cleanup poller doesn't need to be run.
// It also imposes a maximum limit on the number of outstanding orphan
// blocks and will remove the oldest received orphan block if the limit is
// exceeded.
func (b *BlockChain) addOrphanBlock(block *btcutil.Block) {
	// Remove expired orphan blocks.
	for _, oBlock := range b.orphans {
		if time.Now().After(oBlock.expiration) {
			b.removeOrphanBlock(oBlock)
			continue
		}

		// Update the oldest orphan block pointer so it can be discarded
		// in case the orphan pool fills up.
		if b.oldestOrphan == nil || oBlock.expiration.Before(b.oldestOrphan.expiration) {
			b.oldestOrphan = oBlock
		}
	}

	// Limit orphan blocks to prevent memory exhaustion.
	if len(b.orphans)+1 > maxOrphanBlocks {
		// Remove the oldest orphan to make room for the new one.
		b.removeOrphanBlock(b.oldestOrphan)
		b.oldestOrphan = nil
	}

	// Get the block sha.  It is safe to ignore the error here since any
	// errors would've been caught prior to calling this function.
	blockSha, _ := block.Sha()

	// Protect concurrent access.  This is intentionally done here instead
	// of near the top since removeOrphanBlock does its own locking and
	// the range iterator is not invalidated by removing map entries.
	b.orphanLock.Lock()
	defer b.orphanLock.Unlock()

	// Insert the block into the orphan map with an expiration time
	// 1 hour from now.
	expiration := time.Now().Add(time.Hour)
	oBlock := &orphanBlock{
		block:      block,
		expiration: expiration,
	}
	b.orphans[*blockSha] = oBlock

	// Add to previous hash lookup index for faster dependency lookups.
	prevHash := &block.MsgBlock().Header.PrevBlock
	b.prevOrphans[*prevHash] = append(b.prevOrphans[*prevHash], oBlock)

	return
}

// getPrevNodeFromBlock returns a block node for the block previous to the
// passed block (the passed block's parent).  When it is already in the memory
// block chain, it simply returns it.  Otherwise, it loads the previous block
// from the block database, creates a new block node from it, and returns it.
// The returned node will be nil if the genesis block is passed.
func (b *BlockChain) getPrevNodeFromBlock(block *btcutil.Block) (*blockNode, error) {
	// Genesis block.
	prevHash := &block.MsgBlock().Header.PrevBlock
	if prevHash.IsEqual(zeroHash) {
		return nil, nil
	}

	// Return the existing previous block node if it's already there.
	if bn, ok := b.index[*prevHash]; ok {
		return bn, nil
	}

	// Dynamically load the previous block from the block database, create
	// a new block node for it, and update the memory chain accordingly.
	prevBlockNode, err := b.loadBlockNode(prevHash)
	if err != nil {
		return nil, err
	}
	return prevBlockNode, nil
}

// checkBlockScripts executes and validates the scripts for all transactions in
// the passed block.
func checkBlockScripts(block *btcutil.Block, txStore TxStore) error {
	// Setup the script validation flags.  Blocks created after the BIP0016
	// activation time need to have the pay-to-script-hash checks enabled.
	var flags txscript.ScriptFlags
	if block.MsgBlock().Header.Timestamp.After(txscript.Bip16Activation) {
		flags |= txscript.ScriptBip16
	}

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

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

	// Validate all of the inputs.
	validator := newTxValidator(txStore, flags)
	if err := validator.Validate(txValItems); err != nil {
		return err
	}

	return nil
}

// ProcessBlock is the main workhorse for handling insertion of new blocks into
// the block chain.  It includes functionality such as rejecting duplicate
// blocks, ensuring blocks follow all rules, orphan handling, and insertion into
// the block chain along with best chain selection and reorganization.
//
// It returns a bool which indicates whether or not the block is an orphan and
// any errors that occurred during processing.  The returned bool is only valid
// when the error is nil.
func (b *BlockChain) ProcessBlock(block *btcutil.Block, timeSource MedianTimeSource, flags BehaviorFlags) (bool, error) {
	fastAdd := flags&BFFastAdd == BFFastAdd
	dryRun := flags&BFDryRun == BFDryRun

	blockHash, err := block.Sha()
	if err != nil {
		return false, err
	}
	log.Tracef("Processing block %v", blockHash)

	// The block must not already exist in the main chain or side chains.
	exists, err := b.blockExists(blockHash)
	if err != nil {
		return false, err
	}
	if exists {
		str := fmt.Sprintf("already have block %v", blockHash)
		return false, ruleError(ErrDuplicateBlock, str)
	}

	// The block must not already exist as an orphan.
	if _, exists := b.orphans[*blockHash]; exists {
		str := fmt.Sprintf("already have block (orphan) %v", blockHash)
		return false, ruleError(ErrDuplicateBlock, str)
	}

	// Perform preliminary sanity checks on the block and its transactions.
	err = checkBlockSanity(block, b.netParams.PowLimit, timeSource, flags)
	if err != nil {
		return false, err
	}

	// Find the previous checkpoint and perform some additional checks based
	// on the checkpoint.  This provides a few nice properties such as
	// preventing old side chain blocks before the last checkpoint,
	// rejecting easy to mine, but otherwise bogus, blocks that could be
	// used to eat memory, and ensuring expected (versus claimed) proof of
	// work requirements since the previous checkpoint are met.
	blockHeader := &block.MsgBlock().Header
	checkpointBlock, err := b.findPreviousCheckpoint()
	if err != nil {
		return false, err
	}
	if checkpointBlock != nil {
		// Ensure the block timestamp is after the checkpoint timestamp.
		checkpointHeader := &checkpointBlock.MsgBlock().Header
		checkpointTime := checkpointHeader.Timestamp
		if blockHeader.Timestamp.Before(checkpointTime) {
			str := fmt.Sprintf("block %v has timestamp %v before "+
				"last checkpoint timestamp %v", blockHash,
				blockHeader.Timestamp, checkpointTime)
			return false, ruleError(ErrCheckpointTimeTooOld, str)
		}
		if !fastAdd {
			// Even though the checks prior to now have already ensured the
			// proof of work exceeds the claimed amount, the claimed amount
			// is a field in the block header which could be forged.  This
			// check ensures the proof of work is at least the minimum
			// expected based on elapsed time since the last checkpoint and
			// maximum adjustment allowed by the retarget rules.
			duration := blockHeader.Timestamp.Sub(checkpointTime)
			requiredTarget := CompactToBig(b.calcEasiestDifficulty(
				checkpointHeader.Bits, duration))
			currentTarget := CompactToBig(blockHeader.Bits)
			if currentTarget.Cmp(requiredTarget) > 0 {
				str := fmt.Sprintf("block target difficulty of %064x "+
					"is too low when compared to the previous "+
					"checkpoint", currentTarget)
				return false, ruleError(ErrDifficultyTooLow, str)
			}
		}
	}

	// Handle orphan blocks.
	prevHash := &blockHeader.PrevBlock
	if !prevHash.IsEqual(zeroHash) {
		prevHashExists, err := b.blockExists(prevHash)
		if err != nil {
			return false, err
		}
		if !prevHashExists {
			if !dryRun {
				log.Infof("Adding orphan block %v with parent %v",
					blockHash, prevHash)
				b.addOrphanBlock(block)
			}

			return true, nil
		}
	}

	// The block has passed all context independent checks and appears sane
//.........这里部分代码省略.........

// 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.
func (b *BlockChain) IsCheckpointCandidate(block *btcutil.Block) (bool, error) {
	// Checkpoints must be enabled.
	if b.noCheckpoints {
		return false, fmt.Errorf("checkpoints are disabled")
	}

	blockHash, err := block.Sha()
	if err != nil {
		return false, err
	}

	// A checkpoint must be in the main chain.
	exists, err := b.db.ExistsSha(blockHash)
	if err != nil {
		return false, err
	}
	if !exists {
		return false, nil
	}

	// A checkpoint must be at least CheckpointConfirmations blocks before
	// the end of the main chain.
	blockHeight := block.Height()
	_, mainChainHeight, err := b.db.NewestSha()
	if err != nil {
		return false, err
	}
	if blockHeight > (mainChainHeight - CheckpointConfirmations) {
		return false, nil
	}

	// Get the previous block.
	prevHash := &block.MsgBlock().Header.PrevBlock
	prevBlock, err := b.db.FetchBlockBySha(prevHash)
	if err != nil {
		return false, err
	}

	// Get the next block.
	nextHash, err := b.db.FetchBlockShaByHeight(blockHeight + 1)
	if err != nil {
		return false, err
	}
	nextBlock, err := b.db.FetchBlockBySha(nextHash)
	if err != nil {
		return false, 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 := prevBlock.MsgBlock().Header.Timestamp
	curTime := block.MsgBlock().Header.Timestamp
	nextTime := nextBlock.MsgBlock().Header.Timestamp
	if prevTime.After(curTime) || nextTime.Before(curTime) {
		return false, nil
	}

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

	return true, nil
}

// 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 checkProofOfWork.
func checkBlockSanity(block *btcutil.Block, powLimit *big.Int, timeSource MedianTimeSource, flags BehaviorFlags) error {
	// A block must have at least one transaction.
	msgBlock := block.MsgBlock()
	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 > btcwire.MaxBlockPayload {
		str := fmt.Sprintf("block contains too many transactions - "+
			"got %d, max %d", numTx, btcwire.MaxBlockPayload)
		return ruleError(ErrTooManyTransactions, str)
	}

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

	// Ensure the proof of work bits in the block header is in min/max range
	// and the block hash is less than the target value described by the
	// bits.
	err := checkProofOfWork(block, powLimit, flags)
	if err != nil {
		return err
	}

	// A block timestamp must not have a greater precision than one second.
	// This check is necessary because Go time.Time values support
	// nanosecond precision whereas the consensus rules only apply to
	// seconds and it's much nicer to deal with standard Go time values
	// instead of converting to seconds everywhere.
	header := &block.MsgBlock().Header
	if !header.Timestamp.Equal(time.Unix(header.Timestamp.Unix(), 0)) {
		str := fmt.Sprintf("block timestamp of %v has a higher "+
			"precision than one second", header.Timestamp)
		return ruleError(ErrInvalidTime, str)
	}

	// Ensure the block time is not too far in the future.
	maxTimestamp := timeSource.AdjustedTime().Add(time.Second *
		MaxTimeOffsetSeconds)
	if header.Timestamp.After(maxTimestamp) {
		str := fmt.Sprintf("block timestamp of %v is too far in the "+
			"future", header.Timestamp)
		return ruleError(ErrTimeTooNew, 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)
			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())
	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
//.........这里部分代码省略.........

// InsertBlock inserts raw block and transaction data from a block into the
// database.  The first block inserted into the database will be treated as the
// genesis block.  Every subsequent block insert requires the referenced parent
// block to already exist.
func (db *LevelDb) InsertBlock(block *btcutil.Block) (height int64, rerr error) {
	db.dbLock.Lock()
	defer db.dbLock.Unlock()
	defer func() {
		if rerr == nil {
			rerr = db.processBatches()
		} else {
			db.lBatch().Reset()
		}
	}()

	blocksha, err := block.Sha()
	if err != nil {
		log.Warnf("Failed to compute block sha %v", blocksha)
		return 0, err
	}
	mblock := block.MsgBlock()
	rawMsg, err := block.Bytes()
	if err != nil {
		log.Warnf("Failed to obtain raw block sha %v", blocksha)
		return 0, err
	}
	txloc, err := block.TxLoc()
	if err != nil {
		log.Warnf("Failed to obtain raw block sha %v", blocksha)
		return 0, err
	}

	// Insert block into database
	newheight, err := db.insertBlockData(blocksha, &mblock.Header.PrevBlock,
		rawMsg)
	if err != nil {
		log.Warnf("Failed to insert block %v %v %v", blocksha,
			&mblock.Header.PrevBlock, err)
		return 0, err
	}

	// At least two blocks in the long past were generated by faulty
	// miners, the sha of the transaction exists in a previous block,
	// detect this condition and 'accept' the block.
	for txidx, tx := range mblock.Transactions {
		txsha, err := block.TxSha(txidx)
		if err != nil {
			log.Warnf("failed to compute tx name block %v idx %v err %v", blocksha, txidx, err)
			return 0, err
		}
		spentbuflen := (len(tx.TxOut) + 7) / 8
		spentbuf := make([]byte, spentbuflen, spentbuflen)
		if len(tx.TxOut)%8 != 0 {
			for i := uint(len(tx.TxOut) % 8); i < 8; i++ {
				spentbuf[spentbuflen-1] |= (byte(1) << i)
			}
		}

		err = db.insertTx(txsha, newheight, txloc[txidx].TxStart, txloc[txidx].TxLen, spentbuf)
		if err != nil {
			log.Warnf("block %v idx %v failed to insert tx %v %v err %v", blocksha, newheight, &txsha, txidx, err)
			return 0, err
		}

		// Some old blocks contain duplicate transactions
		// Attempt to cleanly bypass this problem by marking the
		// first as fully spent.
		// http://blockexplorer.com/b/91812 dup in 91842
		// http://blockexplorer.com/b/91722 dup in 91880
		if newheight == 91812 {
			dupsha, err := btcwire.NewShaHashFromStr("d5d27987d2a3dfc724e359870c6644b40e497bdc0589a033220fe15429d88599")
			if err != nil {
				panic("invalid sha string in source")
			}
			if txsha.IsEqual(dupsha) {
				// marking TxOut[0] as spent
				po := btcwire.NewOutPoint(dupsha, 0)
				txI := btcwire.NewTxIn(po, []byte("garbage"))

				var spendtx btcwire.MsgTx
				spendtx.AddTxIn(txI)
				err = db.doSpend(&spendtx)
				if err != nil {
					log.Warnf("block %v idx %v failed to spend tx %v %v err %v", blocksha, newheight, &txsha, txidx, err)
				}
			}
		}
		if newheight == 91722 {
			dupsha, err := btcwire.NewShaHashFromStr("e3bf3d07d4b0375638d5f1db5255fe07ba2c4cb067cd81b84ee974b6585fb468")
			if err != nil {
				panic("invalid sha string in source")
			}
			if txsha.IsEqual(dupsha) {
				// marking TxOut[0] as spent
				po := btcwire.NewOutPoint(dupsha, 0)
				txI := btcwire.NewTxIn(po, []byte("garbage"))

				var spendtx btcwire.MsgTx
				spendtx.AddTxIn(txI)
				err = db.doSpend(&spendtx)
//.........这里部分代码省略.........

// InsertBlock inserts raw block and transaction data from a block into the
// database.  The first block inserted into the database will be treated as the
// genesis block.  Every subsequent block insert requires the referenced parent
// block to already exist.  This is part of the database.Db interface
// implementation.
func (db *MemDb) InsertBlock(block *btcutil.Block) (int64, error) {
	db.Lock()
	defer db.Unlock()

	if db.closed {
		return 0, ErrDbClosed
	}

	blockHash, err := block.Sha()
	if err != nil {
		return 0, err
	}

	// Reject the insert if the previously reference block does not exist
	// except in the case there are no blocks inserted yet where the first
	// inserted block is assumed to be a genesis block.
	msgBlock := block.MsgBlock()
	if _, exists := db.blocksBySha[msgBlock.Header.PrevBlock]; !exists {
		if len(db.blocks) > 0 {
			return 0, database.ErrPrevShaMissing
		}
	}

	// 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[btcwire.ShaHash]int{}
	transactions := block.Transactions()
	for i, tx := range transactions {
		txInFlight[*tx.Sha()] = i
	}

	// Loop through all transactions and inputs to ensure there are no error
	// conditions that would prevent them from be inserted into the db.
	// Although these checks could could be done in the loop below, checking
	// for error conditions up front means the code below doesn't have to
	// deal with rollback on errors.
	newHeight := int64(len(db.blocks))
	for i, tx := range transactions {
		// Two old blocks contain duplicate transactions due to being
		// mined by faulty miners and accepted by the origin Satoshi
		// client.  Rules have since been added to the ensure this
		// problem can no longer happen, but the two duplicate
		// transactions which were originally accepted are forever in
		// the block chain history and must be dealth with specially.
		// http://blockexplorer.com/b/91842
		// http://blockexplorer.com/b/91880
		if newHeight == 91842 && tx.Sha().IsEqual(dupTxHash91842) {
			continue
		}

		if newHeight == 91880 && tx.Sha().IsEqual(dupTxHash91880) {
			continue
		}

		for _, txIn := range tx.MsgTx().TxIn {
			if isCoinbaseInput(txIn) {
				continue
			}

			// 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.
			prevOut := &txIn.PreviousOutPoint
			if inFlightIndex, ok := txInFlight[prevOut.Hash]; ok {
				if i <= inFlightIndex {
					log.Warnf("InsertBlock: requested hash "+
						" of %s does not exist in-flight",
						tx.Sha())
					return 0, database.ErrTxShaMissing
				}
			} else {
				originTxns, exists := db.txns[prevOut.Hash]
				if !exists {
					log.Warnf("InsertBlock: requested hash "+
						"of %s by %s does not exist",
						prevOut.Hash, tx.Sha())
					return 0, database.ErrTxShaMissing
				}
				originTxD := originTxns[len(originTxns)-1]
				if prevOut.Index > uint32(len(originTxD.spentBuf)) {
					log.Warnf("InsertBlock: requested hash "+
						"of %s with index %d does not "+
						"exist", tx.Sha(), prevOut.Index)
					return 0, database.ErrTxShaMissing
				}
			}
		}

		// Prevent duplicate transactions in the same block.
		if inFlightIndex, exists := txInFlight[*tx.Sha()]; exists &&
			inFlightIndex < i {
			log.Warnf("Block contains duplicate transaction %s",
				tx.Sha())
//.........这里部分代码省略.........

// maybeAcceptBlock potentially accepts a block into the memory block chain.
// It performs several validation checks which depend on its position within
// the block chain before adding it.  The block is expected to have already gone
// through ProcessBlock before calling this function with it.
//
// The flags modify the behavior of this function as follows:
//  - BFFastAdd: The somewhat expensive BIP0034 validation is not performed.
//  - BFDryRun: The memory chain index will not be pruned and no accept
//    notification will be sent since the block is not being accepted.
func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) error {
	fastAdd := flags&BFFastAdd == BFFastAdd
	dryRun := flags&BFDryRun == BFDryRun

	// Get a block node for the block previous to this one.  Will be nil
	// if this is the genesis block.
	prevNode, err := b.getPrevNodeFromBlock(block)
	if err != nil {
		log.Errorf("getPrevNodeFromBlock: %v", err)
		return err
	}

	// The height of this block is one more than the referenced previous
	// block.
	blockHeight := int64(0)
	if prevNode != nil {
		blockHeight = prevNode.height + 1
	}
	block.SetHeight(blockHeight)

	blockHeader := &block.MsgBlock().Header
	if !fastAdd {
		// Ensure the difficulty specified in the block header matches
		// the calculated difficulty based on the previous block and
		// difficulty retarget rules.
		expectedDifficulty, err := b.calcNextRequiredDifficulty(prevNode,
			block.MsgBlock().Header.Timestamp)
		if err != nil {
			return err
		}
		blockDifficulty := blockHeader.Bits
		if blockDifficulty != expectedDifficulty {
			str := "block difficulty of %d is not the expected value of %d"
			str = fmt.Sprintf(str, blockDifficulty, expectedDifficulty)
			return ruleError(ErrUnexpectedDifficulty, str)
		}

		// Ensure the timestamp for the block header is after the
		// median time of the last several blocks (medianTimeBlocks).
		medianTime, err := b.calcPastMedianTime(prevNode)
		if err != nil {
			log.Errorf("calcPastMedianTime: %v", err)
			return err
		}
		if !blockHeader.Timestamp.After(medianTime) {
			str := "block timestamp of %v is not after expected %v"
			str = fmt.Sprintf(str, blockHeader.Timestamp,
				medianTime)
			return ruleError(ErrTimeTooOld, str)
		}

		// Ensure all transactions in the block are finalized.
		for _, tx := range block.Transactions() {
			if !IsFinalizedTransaction(tx, blockHeight,
				blockHeader.Timestamp) {
				str := fmt.Sprintf("block contains "+
					"unfinalized transaction %v", tx.Sha())
				return ruleError(ErrUnfinalizedTx, str)
			}
		}

	}

	// Ensure chain matches up to predetermined checkpoints.
	// It's safe to ignore the error on Sha since it's already cached.
	blockHash, _ := block.Sha()
	if !b.verifyCheckpoint(blockHeight, blockHash) {
		str := fmt.Sprintf("block at height %d does not match "+
			"checkpoint hash", blockHeight)
		return ruleError(ErrBadCheckpoint, str)
	}

	// Find the previous checkpoint and prevent blocks which fork the main
	// chain before it.  This prevents storage of new, otherwise valid,
	// blocks which build off of old blocks that are likely at a much easier
	// difficulty and therefore could be used to waste cache and disk space.
	checkpointBlock, err := b.findPreviousCheckpoint()
	if err != nil {
		return err
	}
	if checkpointBlock != nil && blockHeight < checkpointBlock.Height() {
		str := fmt.Sprintf("block at height %d forks the main chain "+
			"before the previous checkpoint at height %d",
			blockHeight, checkpointBlock.Height())
		return ruleError(ErrForkTooOld, str)
	}

	if !fastAdd {
		// Reject version 1 blocks once a majority of the network has
		// upgraded.  This is part of BIP0034.
		if blockHeader.Version < 2 {
//.........这里部分代码省略.........