// dbIndexDisconnectBlock removes all of the index entries associated with the
// given block using the provided indexer and updates the tip of the indexer
// accordingly. An error will be returned if the current tip for the indexer is
// not the passed block.
func dbIndexDisconnectBlock(dbTx database.Tx, indexer Indexer, block *btcutil.Block, view *blockchain.UtxoViewpoint) error {
// Assert that the block being disconnected is the current tip of the
// index.
idxKey := indexer.Key()
curTipHash, _, err := dbFetchIndexerTip(dbTx, idxKey)
if err != nil {
return err
}
if !curTipHash.IsEqual(block.Hash()) {
return AssertError(fmt.Sprintf("dbIndexDisconnectBlock must "+
"be called with the block at the current index tip "+
"(%s, tip %s, block %s)", indexer.Name(),
curTipHash, block.Hash()))
}
// Notify the indexer with the disconnected block so it can remove all
// of the appropriate entries.
if err := indexer.DisconnectBlock(dbTx, block, view); err != nil {
return err
}
// Update the current index tip.
prevHash := &block.MsgBlock().Header.PrevBlock
return dbPutIndexerTip(dbTx, idxKey, prevHash, block.Height()-1)
}
// ConnectBlock is invoked by the index manager when a new block has been
// connected to the main chain. This indexer adds a mapping for each address
// the transactions in the block involve.
//
// This is part of the Indexer interface.
func (idx *AddrIndex) ConnectBlock(dbTx database.Tx, block *btcutil.Block, view *blockchain.UtxoViewpoint) error {
// The offset and length of the transactions within the serialized
// block.
txLocs, err := block.TxLoc()
if err != nil {
return err
}
// Get the internal block ID associated with the block.
blockID, err := dbFetchBlockIDByHash(dbTx, block.Hash())
if err != nil {
return err
}
// Build all of the address to transaction mappings in a local map.
addrsToTxns := make(writeIndexData)
idx.indexBlock(addrsToTxns, block, view)
// Add all of the index entries for each address.
addrIdxBucket := dbTx.Metadata().Bucket(addrIndexKey)
for addrKey, txIdxs := range addrsToTxns {
for _, txIdx := range txIdxs {
err := dbPutAddrIndexEntry(addrIdxBucket, addrKey,
blockID, txLocs[txIdx])
if err != nil {
return err
}
}
}
return nil
}
// maybeAcceptBlock potentially accepts a block into the block chain and, if
// accepted, returns whether or not it is on the main 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:
// - BFDryRun: The memory chain index will not be pruned and no accept
// notification will be sent since the block is not being accepted.
//
// The flags are also passed to checkBlockContext and connectBestChain. See
// their documentation for how the flags modify their behavior.
//
// This function MUST be called with the chain state lock held (for writes).
func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
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 false, err
}
// The height of this block is one more than the referenced previous
// block.
blockHeight := int32(0)
if prevNode != nil {
blockHeight = prevNode.height + 1
}
block.SetHeight(blockHeight)
// 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
}
// Create a new block node for the block and add it to the in-memory
// block chain (could be either a side chain or the main chain).
blockHeader := &block.MsgBlock().Header
newNode := newBlockNode(blockHeader, block.Hash(), blockHeight)
if prevNode != nil {
newNode.parent = prevNode
newNode.height = blockHeight
newNode.workSum.Add(prevNode.workSum, newNode.workSum)
}
// 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
}
// Notify the caller that the new block was accepted into the block
// chain. The caller would typically want to react by relaying the
// inventory to other peers.
if !dryRun {
b.chainLock.Unlock()
b.sendNotification(NTBlockAccepted, block)
b.chainLock.Lock()
}
return isMainChain, 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
}
// DisconnectBlock is invoked by the index manager when a block has been
// disconnected from the main chain. This indexer removes the
// hash-to-transaction mapping for every transaction in the block.
//
// This is part of the Indexer interface.
func (idx *TxIndex) DisconnectBlock(dbTx database.Tx, block *btcutil.Block, view *blockchain.UtxoViewpoint) error {
// Remove all of the transactions in the block from the index.
if err := dbRemoveTxIndexEntries(dbTx, block); err != nil {
return err
}
// Remove the block ID index entry for the block being disconnected and
// decrement the current internal block ID to account for it.
if err := dbRemoveBlockIDIndexEntry(dbTx, block.Hash()); err != nil {
return err
}
idx.curBlockID--
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 safe for concurrent access.
func (b *BlockChain) CheckConnectBlock(block *btcutil.Block) error {
b.chainLock.Lock()
defer b.chainLock.Unlock()
prevNode := b.bestNode
newNode := newBlockNode(&block.MsgBlock().Header, block.Hash(),
prevNode.height+1)
newNode.parent = prevNode
newNode.workSum.Add(prevNode.workSum, newNode.workSum)
// Leave the spent txouts entry nil in the state since the information
// is not needed and thus extra work can be avoided.
view := NewUtxoViewpoint()
view.SetBestHash(prevNode.hash)
return b.checkConnectBlock(newNode, block, view, nil)
}
// ConnectBlock is invoked by the index manager when a new block has been
// connected to the main chain. This indexer adds a hash-to-transaction mapping
// for every transaction in the passed block.
//
// This is part of the Indexer interface.
func (idx *TxIndex) ConnectBlock(dbTx database.Tx, block *btcutil.Block, view *blockchain.UtxoViewpoint) error {
// Increment the internal block ID to use for the block being connected
// and add all of the transactions in the block to the index.
newBlockID := idx.curBlockID + 1
if err := dbAddTxIndexEntries(dbTx, block, newBlockID); err != nil {
return err
}
// Add the new block ID index entry for the block being connected and
// update the current internal block ID accordingly.
err := dbPutBlockIDIndexEntry(dbTx, block.Hash(), newBlockID)
if err != nil {
return err
}
idx.curBlockID = newBlockID
return nil
}
// submitBlock submits the passed block to network after ensuring it passes all
// of the consensus validation rules.
func (m *CPUMiner) submitBlock(block *btcutil.Block) bool {
m.submitBlockLock.Lock()
defer m.submitBlockLock.Unlock()
// Ensure the block is not stale since a new block could have shown up
// while the solution was being found. Typically that condition is
// detected and all work on the stale block is halted to start work on
// a new block, but the check only happens periodically, so it is
// possible a block was found and submitted in between.
msgBlock := block.MsgBlock()
if !msgBlock.Header.PrevBlock.IsEqual(m.g.BestSnapshot().Hash) {
log.Debugf("Block submitted via CPU miner with previous "+
"block %s is stale", msgBlock.Header.PrevBlock)
return false
}
// Process this block using the same rules as blocks coming from other
// nodes. This will in turn relay it to the network like normal.
isOrphan, err := m.cfg.ProcessBlock(block, blockchain.BFNone)
if err != nil {
// Anything other than a rule violation is an unexpected error,
// so log that error as an internal error.
if _, ok := err.(blockchain.RuleError); !ok {
log.Errorf("Unexpected error while processing "+
"block submitted via CPU miner: %v", err)
return false
}
log.Debugf("Block submitted via CPU miner rejected: %v", err)
return false
}
if isOrphan {
log.Debugf("Block submitted via CPU miner is an orphan")
return false
}
// The block was accepted.
coinbaseTx := block.MsgBlock().Transactions[0].TxOut[0]
log.Infof("Block submitted via CPU miner accepted (hash %s, "+
"amount %v)", block.Hash(), btcutil.Amount(coinbaseTx.Value))
return true
}
// dbIndexConnectBlock adds all of the index entries associated with the
// given block using the provided indexer and updates the tip of the indexer
// accordingly. An error will be returned if the current tip for the indexer is
// not the previous block for the passed block.
func dbIndexConnectBlock(dbTx database.Tx, indexer Indexer, block *btcutil.Block, view *blockchain.UtxoViewpoint) error {
// Assert that the block being connected properly connects to the
// current tip of the index.
idxKey := indexer.Key()
curTipHash, _, err := dbFetchIndexerTip(dbTx, idxKey)
if err != nil {
return err
}
if !curTipHash.IsEqual(&block.MsgBlock().Header.PrevBlock) {
return AssertError(fmt.Sprintf("dbIndexConnectBlock must be "+
"called with a block that extends the current index "+
"tip (%s, tip %s, block %s)", indexer.Name(),
curTipHash, block.Hash()))
}
// Notify the indexer with the connected block so it can index it.
if err := indexer.ConnectBlock(dbTx, block, view); err != nil {
return err
}
// Update the current index tip.
return dbPutIndexerTip(dbTx, idxKey, block.Hash(), block.Height())
}
// 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
}
// CreateBlock creates a new block building from the previous block with a
// specified blockversion and timestamp. If the timestamp passed is zero (not
// initialized), then the timestamp of the previous block will be used plus 1
// second is used. Passing nil for the previous block results in a block that
// builds off of the genesis block for the specified chain.
func CreateBlock(prevBlock *btcutil.Block, inclusionTxs []*btcutil.Tx,
blockVersion int32, blockTime time.Time,
miningAddr btcutil.Address, net *chaincfg.Params) (*btcutil.Block, error) {
var (
prevHash *chainhash.Hash
blockHeight int32
prevBlockTime time.Time
)
// If the previous block isn't specified, then we'll construct a block
// that builds off of the genesis block for the chain.
if prevBlock == nil {
prevHash = net.GenesisHash
blockHeight = 1
prevBlockTime = net.GenesisBlock.Header.Timestamp.Add(time.Minute)
} else {
prevHash = prevBlock.Hash()
blockHeight = prevBlock.Height() + 1
prevBlockTime = prevBlock.MsgBlock().Header.Timestamp
}
// If a target block time was specified, then use that as the header's
// timestamp. Otherwise, add one second to the previous block unless
// it's the genesis block in which case use the current time.
var ts time.Time
switch {
case !blockTime.IsZero():
ts = blockTime
default:
ts = prevBlockTime.Add(time.Second)
}
extraNonce := uint64(0)
coinbaseScript, err := standardCoinbaseScript(blockHeight, extraNonce)
if err != nil {
return nil, err
}
coinbaseTx, err := createCoinbaseTx(coinbaseScript, blockHeight,
miningAddr, net)
if err != nil {
return nil, err
}
// Create a new block ready to be solved.
blockTxns := []*btcutil.Tx{coinbaseTx}
if inclusionTxs != nil {
blockTxns = append(blockTxns, inclusionTxs...)
}
merkles := blockchain.BuildMerkleTreeStore(blockTxns, false)
var block wire.MsgBlock
block.Header = wire.BlockHeader{
Version: blockVersion,
PrevBlock: *prevHash,
MerkleRoot: *merkles[len(merkles)-1],
Timestamp: ts,
Bits: net.PowLimitBits,
}
for _, tx := range blockTxns {
if err := block.AddTransaction(tx.MsgTx()); err != nil {
return nil, err
}
}
found := solveBlock(&block.Header, net.PowLimit)
if !found {
return nil, errors.New("Unable to solve block")
}
utilBlock := btcutil.NewBlock(&block)
utilBlock.SetHeight(blockHeight)
return utilBlock, nil
}
// 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
}
// 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.
//
// When no errors occurred during processing, the first return value indicates
// whether or not the block is on the main chain and the second indicates
// whether or not the block is an orphan.
//
// This function is safe for concurrent access.
func (b *BlockChain) ProcessBlock(block *btcutil.Block, flags BehaviorFlags) (bool, bool, error) {
b.chainLock.Lock()
defer b.chainLock.Unlock()
fastAdd := flags&BFFastAdd == BFFastAdd
dryRun := flags&BFDryRun == BFDryRun
blockHash := block.Hash()
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, false, err
}
if exists {
str := fmt.Sprintf("already have block %v", blockHash)
return false, 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, false, ruleError(ErrDuplicateBlock, str)
}
// Perform preliminary sanity checks on the block and its transactions.
err = checkBlockSanity(block, b.chainParams.PowLimit, b.timeSource, flags)
if err != nil {
return false, 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, 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, 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, false, ruleError(ErrDifficultyTooLow, str)
}
}
}
// Handle orphan blocks.
prevHash := &blockHeader.PrevBlock
prevHashExists, err := b.blockExists(prevHash)
if err != nil {
return false, false, err
}
if !prevHashExists {
if !dryRun {
log.Infof("Adding orphan block %v with parent %v",
blockHash, prevHash)
b.addOrphanBlock(block)
}
return false, true, nil
}
// The block has passed all context independent checks and appears sane
// enough to potentially accept it into the block chain.
isMainChain, err := b.maybeAcceptBlock(block, flags)
if err != nil {
return false, false, err
}
// Don't process any orphans or log when the dry run flag is set.
if !dryRun {
// Accept any orphan blocks that depend on this block (they are
// no longer orphans) and repeat for those accepted blocks until
// there are no more.
err := b.processOrphans(blockHash, flags)
if err != nil {
return false, false, err
}
log.Debugf("Accepted block %v", blockHash)
}
return isMainChain, false, nil
}
