status-go/vendor/github.com/btcsuite/btcutil/block.go

244 lines
7.7 KiB
Go

// Copyright (c) 2013-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcutil
import (
"bytes"
"fmt"
"io"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
)
// OutOfRangeError describes an error due to accessing an element that is out
// of range.
type OutOfRangeError string
// BlockHeightUnknown is the value returned for a block height that is unknown.
// This is typically because the block has not been inserted into the main chain
// yet.
const BlockHeightUnknown = int32(-1)
// Error satisfies the error interface and prints human-readable errors.
func (e OutOfRangeError) Error() string {
return string(e)
}
// Block defines a bitcoin block that provides easier and more efficient
// manipulation of raw blocks. It also memoizes hashes for the block and its
// transactions on their first access so subsequent accesses don't have to
// repeat the relatively expensive hashing operations.
type Block struct {
msgBlock *wire.MsgBlock // Underlying MsgBlock
serializedBlock []byte // Serialized bytes for the block
blockHash *chainhash.Hash // Cached block hash
blockHeight int32 // Height in the main block chain
transactions []*Tx // Transactions
txnsGenerated bool // ALL wrapped transactions generated
}
// MsgBlock returns the underlying wire.MsgBlock for the Block.
func (b *Block) MsgBlock() *wire.MsgBlock {
// Return the cached block.
return b.msgBlock
}
// Bytes returns the serialized bytes for the Block. This is equivalent to
// calling Serialize on the underlying wire.MsgBlock, however it caches the
// result so subsequent calls are more efficient.
func (b *Block) Bytes() ([]byte, error) {
// Return the cached serialized bytes if it has already been generated.
if len(b.serializedBlock) != 0 {
return b.serializedBlock, nil
}
// Serialize the MsgBlock.
w := bytes.NewBuffer(make([]byte, 0, b.msgBlock.SerializeSize()))
err := b.msgBlock.Serialize(w)
if err != nil {
return nil, err
}
serializedBlock := w.Bytes()
// Cache the serialized bytes and return them.
b.serializedBlock = serializedBlock
return serializedBlock, nil
}
// Hash returns the block identifier hash for the Block. This is equivalent to
// calling BlockHash on the underlying wire.MsgBlock, however it caches the
// result so subsequent calls are more efficient.
func (b *Block) Hash() *chainhash.Hash {
// Return the cached block hash if it has already been generated.
if b.blockHash != nil {
return b.blockHash
}
// Cache the block hash and return it.
hash := b.msgBlock.BlockHash()
b.blockHash = &hash
return &hash
}
// Tx returns a wrapped transaction (btcutil.Tx) for the transaction at the
// specified index in the Block. The supplied index is 0 based. That is to
// say, the first transaction in the block is txNum 0. This is nearly
// equivalent to accessing the raw transaction (wire.MsgTx) from the
// underlying wire.MsgBlock, however the wrapped transaction has some helpful
// properties such as caching the hash so subsequent calls are more efficient.
func (b *Block) Tx(txNum int) (*Tx, error) {
// Ensure the requested transaction is in range.
numTx := uint64(len(b.msgBlock.Transactions))
if txNum < 0 || uint64(txNum) > numTx {
str := fmt.Sprintf("transaction index %d is out of range - max %d",
txNum, numTx-1)
return nil, OutOfRangeError(str)
}
// Generate slice to hold all of the wrapped transactions if needed.
if len(b.transactions) == 0 {
b.transactions = make([]*Tx, numTx)
}
// Return the wrapped transaction if it has already been generated.
if b.transactions[txNum] != nil {
return b.transactions[txNum], nil
}
// Generate and cache the wrapped transaction and return it.
newTx := NewTx(b.msgBlock.Transactions[txNum])
newTx.SetIndex(txNum)
b.transactions[txNum] = newTx
return newTx, nil
}
// Transactions returns a slice of wrapped transactions (btcutil.Tx) for all
// transactions in the Block. This is nearly equivalent to accessing the raw
// transactions (wire.MsgTx) in the underlying wire.MsgBlock, however it
// instead provides easy access to wrapped versions (btcutil.Tx) of them.
func (b *Block) Transactions() []*Tx {
// Return transactions if they have ALL already been generated. This
// flag is necessary because the wrapped transactions are lazily
// generated in a sparse fashion.
if b.txnsGenerated {
return b.transactions
}
// Generate slice to hold all of the wrapped transactions if needed.
if len(b.transactions) == 0 {
b.transactions = make([]*Tx, len(b.msgBlock.Transactions))
}
// Generate and cache the wrapped transactions for all that haven't
// already been done.
for i, tx := range b.transactions {
if tx == nil {
newTx := NewTx(b.msgBlock.Transactions[i])
newTx.SetIndex(i)
b.transactions[i] = newTx
}
}
b.txnsGenerated = true
return b.transactions
}
// TxHash returns the hash for the requested transaction number in the Block.
// The supplied index is 0 based. That is to say, the first transaction in the
// block is txNum 0. This is equivalent to calling TxHash on the underlying
// wire.MsgTx, however it caches the result so subsequent calls are more
// efficient.
func (b *Block) TxHash(txNum int) (*chainhash.Hash, error) {
// Attempt to get a wrapped transaction for the specified index. It
// will be created lazily if needed or simply return the cached version
// if it has already been generated.
tx, err := b.Tx(txNum)
if err != nil {
return nil, err
}
// Defer to the wrapped transaction which will return the cached hash if
// it has already been generated.
return tx.Hash(), nil
}
// TxLoc returns the offsets and lengths of each transaction in a raw block.
// It is used to allow fast indexing into transactions within the raw byte
// stream.
func (b *Block) TxLoc() ([]wire.TxLoc, error) {
rawMsg, err := b.Bytes()
if err != nil {
return nil, err
}
rbuf := bytes.NewBuffer(rawMsg)
var mblock wire.MsgBlock
txLocs, err := mblock.DeserializeTxLoc(rbuf)
if err != nil {
return nil, err
}
return txLocs, err
}
// Height returns the saved height of the block in the block chain. This value
// will be BlockHeightUnknown if it hasn't already explicitly been set.
func (b *Block) Height() int32 {
return b.blockHeight
}
// SetHeight sets the height of the block in the block chain.
func (b *Block) SetHeight(height int32) {
b.blockHeight = height
}
// NewBlock returns a new instance of a bitcoin block given an underlying
// wire.MsgBlock. See Block.
func NewBlock(msgBlock *wire.MsgBlock) *Block {
return &Block{
msgBlock: msgBlock,
blockHeight: BlockHeightUnknown,
}
}
// NewBlockFromBytes returns a new instance of a bitcoin block given the
// serialized bytes. See Block.
func NewBlockFromBytes(serializedBlock []byte) (*Block, error) {
br := bytes.NewReader(serializedBlock)
b, err := NewBlockFromReader(br)
if err != nil {
return nil, err
}
b.serializedBlock = serializedBlock
return b, nil
}
// NewBlockFromReader returns a new instance of a bitcoin block given a
// Reader to deserialize the block. See Block.
func NewBlockFromReader(r io.Reader) (*Block, error) {
// Deserialize the bytes into a MsgBlock.
var msgBlock wire.MsgBlock
err := msgBlock.Deserialize(r)
if err != nil {
return nil, err
}
b := Block{
msgBlock: &msgBlock,
blockHeight: BlockHeightUnknown,
}
return &b, nil
}
// NewBlockFromBlockAndBytes returns a new instance of a bitcoin block given
// an underlying wire.MsgBlock and the serialized bytes for it. See Block.
func NewBlockFromBlockAndBytes(msgBlock *wire.MsgBlock, serializedBlock []byte) *Block {
return &Block{
msgBlock: msgBlock,
serializedBlock: serializedBlock,
blockHeight: BlockHeightUnknown,
}
}