neoneo-go/pkg/core/block_base.go

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package core
import (
"fmt"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/crypto/hash"
"github.com/CityOfZion/neo-go/pkg/io"
"github.com/CityOfZion/neo-go/pkg/util"
)
// BlockBase holds the base info of a block
type BlockBase struct {
// Version of the block.
Version uint32 `json:"version"`
// hash of the previous block.
PrevHash util.Uint256 `json:"previousblockhash"`
// Root hash of a transaction list.
MerkleRoot util.Uint256 `json:"merkleroot"`
// 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.
Timestamp uint32 `json:"time"`
// index/height of the block
Index uint32 `json:"height"`
// Random number also called nonce
ConsensusData uint64 `json:"nonce"`
// Contract address of the next miner
NextConsensus util.Uint160 `json:"next_consensus"`
// Padding that is fixed to 1
_ uint8
// Script used to validate the block
Script *transaction.Witness `json:"script"`
// Hash of this block, created when binary encoded (double SHA256).
hash util.Uint256
// Hash of the block used to verify it (single SHA256).
verificationHash util.Uint256
}
// Verify verifies the integrity of the BlockBase.
func (b *BlockBase) Verify() bool {
// TODO: Need a persisted blockchain for this.
return true
}
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// Hash returns the hash of the block.
func (b *BlockBase) Hash() util.Uint256 {
if b.hash.Equals(util.Uint256{}) {
b.createHash()
}
return b.hash
}
// VerificationHash returns the hash of the block used to verify it.
func (b *BlockBase) VerificationHash() util.Uint256 {
if b.verificationHash.Equals(util.Uint256{}) {
if b.createHash() != nil {
panic("failed to compute hash!")
}
}
return b.verificationHash
}
// DecodeBinary implements Serializable interface.
func (b *BlockBase) DecodeBinary(br *io.BinReader) {
b.decodeHashableFields(br)
var padding uint8
br.ReadLE(&padding)
if padding != 1 {
br.Err = fmt.Errorf("format error: padding must equal 1 got %d", padding)
return
}
b.Script = &transaction.Witness{}
b.Script.DecodeBinary(br)
}
// EncodeBinary implements Serializable interface
func (b *BlockBase) EncodeBinary(bw *io.BinWriter) {
b.encodeHashableFields(bw)
bw.WriteLE(uint8(1))
b.Script.EncodeBinary(bw)
}
// getHashableData returns serialized hashable data of the block.
func (b *BlockBase) getHashableData() ([]byte, error) {
buf := io.NewBufBinWriter()
b.encodeHashableFields(buf.BinWriter)
if buf.Err != nil {
return nil, buf.Err
}
return buf.Bytes(), nil
}
// 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() error {
bb, err := b.getHashableData()
if err != nil {
return err
}
b.hash = hash.DoubleSha256(bb)
b.verificationHash = hash.Sha256(bb)
return nil
}
// encodeHashableFields will only encode the fields used for hashing.
// see Hash() for more information about the fields.
func (b *BlockBase) encodeHashableFields(bw *io.BinWriter) {
bw.WriteLE(b.Version)
bw.WriteLE(b.PrevHash)
bw.WriteLE(b.MerkleRoot)
bw.WriteLE(b.Timestamp)
bw.WriteLE(b.Index)
bw.WriteLE(b.ConsensusData)
bw.WriteLE(b.NextConsensus)
}
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// decodeHashableFields decodes the fields used for hashing.
// see Hash() for more information about the fields.
func (b *BlockBase) decodeHashableFields(br *io.BinReader) {
br.ReadLE(&b.Version)
br.ReadLE(&b.PrevHash)
br.ReadLE(&b.MerkleRoot)
br.ReadLE(&b.Timestamp)
br.ReadLE(&b.Index)
br.ReadLE(&b.ConsensusData)
br.ReadLE(&b.NextConsensus)
// Make the hash of the block here so we dont need to do this
// again.
if br.Err == nil {
br.Err = b.createHash()
}
}