neoneo-go/pkg/core/block.go

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package core
import (
"bytes"
"crypto/sha256"
"encoding/binary"
"fmt"
"io"
"log"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/util"
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)
// BlockBase holds the base info of a block
type BlockBase struct {
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Version uint32
// hash of the previous block.
PrevHash util.Uint256
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// Root hash of a transaction list.
MerkleRoot util.Uint256
// The time stamp of each block must be later than previous block's time stamp.
// Generally the difference of two block's time stamp is about 15 seconds and imprecision is allowed.
// The height of the block must be exactly equal to the height of the previous block plus 1.
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Timestamp uint32
// index/height of the block
Index uint32
// Random number also called nonce
ConsensusData uint64
// Contract addresss of the next miner
NextConsensus util.Uint160
// fixed to 1
_ uint8 // padding
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// Script used to validate the block
Script *transaction.Witness
// hash of this block, created when binary encoded.
hash util.Uint256
}
// DecodeBinary implements the payload interface.
func (b *BlockBase) DecodeBinary(r io.Reader) error {
if err := binary.Read(r, binary.LittleEndian, &b.Version); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.PrevHash); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.MerkleRoot); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.Timestamp); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.Index); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.ConsensusData); err != nil {
return err
}
if err := binary.Read(r, binary.LittleEndian, &b.NextConsensus); err != nil {
return err
}
var padding uint8
if err := binary.Read(r, binary.LittleEndian, &padding); err != nil {
return err
}
if padding != 1 {
return fmt.Errorf("format error: padding must equal 1 got %d", padding)
}
b.Script = &transaction.Witness{}
if err := b.Script.DecodeBinary(r); err != nil {
return err
}
// Make the hash of the block here so we dont need to do this
// again.
hash, err := b.createHash()
if err != nil {
return err
}
b.hash = hash
return nil
}
// Hash return the hash of the block.
func (b *BlockBase) Hash() util.Uint256 {
return b.hash
}
// createHash creates the hash of the block.
// When calculating the hash value of the block, instead of calculating the entire block,
// only first seven fields in the block head will be calculated, which are
// version, PrevBlock, MerkleRoot, timestamp, and height, the nonce, NextMiner.
// Since MerkleRoot already contains the hash value of all transactions,
// the modification of transaction will influence the hash value of the block.
func (b *BlockBase) createHash() (hash util.Uint256, err error) {
buf := new(bytes.Buffer)
if err = b.encodeHashableFields(buf); err != nil {
return hash, err
}
// Double hash the encoded fields.
hash = sha256.Sum256(buf.Bytes())
hash = sha256.Sum256(hash.Bytes())
return hash, nil
}
// encodeHashableFields will only encode the fields used for hashing.
// see Hash() for more information about the fields.
func (b *BlockBase) encodeHashableFields(w io.Writer) error {
if err := binary.Write(w, binary.LittleEndian, &b.Version); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, &b.PrevHash); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, &b.MerkleRoot); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, &b.Timestamp); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, &b.Index); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, &b.ConsensusData); err != nil {
return err
}
return binary.Write(w, binary.LittleEndian, &b.NextConsensus)
}
// EncodeBinary implements the Payload interface
func (b *BlockBase) EncodeBinary(w io.Writer) error {
if err := b.encodeHashableFields(w); err != nil {
return err
}
if err := binary.Write(w, binary.LittleEndian, uint8(1)); err != nil {
return err
}
return b.Script.EncodeBinary(w)
}
// Header holds the head info of a block
type Header struct {
BlockBase
_ uint8 // padding fixed to 0
}
// Verify the integrity of the header
func (h *Header) Verify() bool {
return true
}
// DecodeBinary impelements the Payload interface.
func (h *Header) DecodeBinary(r io.Reader) error {
if err := h.BlockBase.DecodeBinary(r); err != nil {
return err
}
var padding uint8
binary.Read(r, binary.LittleEndian, &padding)
if padding != 0 {
return fmt.Errorf("format error: padding must equal 0 got %d", padding)
}
return nil
}
// EncodeBinary impelements the Payload interface.
func (h *Header) EncodeBinary(w io.Writer) error {
if err := h.BlockBase.EncodeBinary(w); err != nil {
return err
}
return binary.Write(w, binary.LittleEndian, uint8(0))
}
// Block represents one block in the chain.
type Block struct {
BlockBase
Transactions []*transaction.Transaction
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}
// Header returns a pointer to the head of the block (BlockHead).
func (b *Block) Header() *Header {
return &Header{
BlockBase: b.BlockBase,
}
}
// Verify the integrity of the block.
func (b *Block) Verify(full bool) bool {
// The first TX has to be a miner transaction.
if b.Transactions[0].Type != transaction.MinerType {
return false
}
// If the first TX is a minerTX then all others cant.
for _, tx := range b.Transactions[1:] {
if tx.Type == transaction.MinerType {
return false
}
}
// TODO: When full is true, do a full verification.
if full {
log.Println("full verification of blocks is not yet implemented")
}
return true
}
// EncodeBinary encodes the block to the given writer.
func (b *Block) EncodeBinary(w io.Writer) error {
return nil
}
// DecodeBinary decodes the block from the given reader.
func (b *Block) DecodeBinary(r io.Reader) error {
if err := b.BlockBase.DecodeBinary(r); err != nil {
return err
}
lentx := util.ReadVarUint(r)
b.Transactions = make([]*transaction.Transaction, lentx)
for i := 0; i < int(lentx); i++ {
b.Transactions[i] = &transaction.Transaction{}
if err := b.Transactions[i].DecodeBinary(r); err != nil {
return err
}
}
return nil
}