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75 lines
1.7 KiB
75 lines
1.7 KiB
package blockchain
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import (
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"bytes"
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"crypto/sha256"
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"encoding/gob"
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"fmt"
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"log"
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"time"
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)
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// Block keeps block headers.
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type Block struct {
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Timestamp int64
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Transactions []*Transaction
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PrevBlockHash []byte
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Hash []byte
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}
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// Serialize serializes the block
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func (b *Block) Serialize() []byte {
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var result bytes.Buffer
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encoder := gob.NewEncoder(&result)
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err := encoder.Encode(b)
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if err != nil {
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log.Panic(err)
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}
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return result.Bytes()
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}
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// DeserializeBlock deserializes a block
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func DeserializeBlock(d []byte) *Block {
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var block Block
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decoder := gob.NewDecoder(bytes.NewReader(d))
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err := decoder.Decode(&block)
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if err != nil {
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log.Panic(err)
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}
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return &block
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}
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// Used for debuging.
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func (b *Block) String() string {
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res := fmt.Sprintf("Block created at %v\n", b.Timestamp)
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for id, tx := range b.Transactions {
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res += fmt.Sprintf("Transaction %v: %v\n", id, *tx)
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}
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res += fmt.Sprintf("previous blockhash: %v\n", b.PrevBlockHash)
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res += fmt.Sprintf("hash: %v\n", b.Hash)
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return res
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}
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// HashTransactions returns a hash of the transactions in the block
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func (b *Block) HashTransactions() []byte {
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var txHashes [][]byte
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var txHash [32]byte
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for _, tx := range b.Transactions {
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txHashes = append(txHashes, tx.ID)
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}
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txHash = sha256.Sum256(bytes.Join(txHashes, []byte{}))
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return txHash[:]
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}
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// NewBlock creates and returns Block.
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func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
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block := &Block{time.Now().Unix(), transactions, prevBlockHash, []byte{}}
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block.Hash = block.HashTransactions()
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return block
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}
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// NewGenesisBlock creates and returns genesis Block.
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func NewGenesisBlock(coinbase *Transaction) *Block {
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return NewBlock([]*Transaction{coinbase}, []byte{})
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}
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