135 lines
2.5 KiB
Go
135 lines
2.5 KiB
Go
package main
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import (
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"fmt"
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"log"
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"github.com/boltdb/bolt"
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)
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const dbFile = "blockchain.db"
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const blocksBucket = "blocks"
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const genesisCoinbase = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
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// Blockchain keeps a sequence of Blocks
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type Blockchain struct {
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tip []byte
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db *bolt.DB
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}
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// BlockchainIterator is used to iterate over blockchain blocks
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type BlockchainIterator struct {
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currentHash []byte
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db *bolt.DB
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}
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// AddBlock saves provided data as a block in the blockchain
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func (bc *Blockchain) AddBlock(transactions []*Transaction) {
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var lastHash []byte
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err := bc.db.View(func(tx *bolt.Tx) error {
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b := tx.Bucket([]byte(blocksBucket))
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lastHash = b.Get([]byte("l"))
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return nil
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})
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if err != nil {
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log.Panic(err)
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}
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newBlock := NewBlock(transactions, lastHash)
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err = bc.db.Update(func(tx *bolt.Tx) error {
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b := tx.Bucket([]byte(blocksBucket))
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err := b.Put(newBlock.Hash, newBlock.Serialize())
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if err != nil {
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log.Panic(err)
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}
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err = b.Put([]byte("l"), newBlock.Hash)
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if err != nil {
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log.Panic(err)
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}
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bc.tip = newBlock.Hash
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return nil
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})
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}
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// Iterator ...
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func (bc *Blockchain) Iterator() *BlockchainIterator {
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bci := &BlockchainIterator{bc.tip, bc.db}
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return bci
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}
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// Next returns next block starting from the tip
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func (i *BlockchainIterator) Next() *Block {
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var block *Block
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err := i.db.View(func(tx *bolt.Tx) error {
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b := tx.Bucket([]byte(blocksBucket))
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encodedBlock := b.Get(i.currentHash)
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block = DeserializeBlock(encodedBlock)
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return nil
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})
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if err != nil {
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log.Panic(err)
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}
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i.currentHash = block.PrevBlockHash
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return block
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}
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// NewBlockchain creates a new Blockchain with genesis Block
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func NewBlockchain(address string) *Blockchain {
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var tip []byte
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db, err := bolt.Open(dbFile, 0600, nil)
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if err != nil {
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log.Panic(err)
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}
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err = db.Update(func(tx *bolt.Tx) error {
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b := tx.Bucket([]byte(blocksBucket))
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if b == nil {
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fmt.Println("No existing blockchain found. Creating a new one...")
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cbtx := NewCoinbaseTX(address, genesisCoinbase)
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genesis := NewGenesisBlock(cbtx)
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b, err := tx.CreateBucket([]byte(blocksBucket))
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if err != nil {
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log.Panic(err)
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}
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err = b.Put(genesis.Hash, genesis.Serialize())
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if err != nil {
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log.Panic(err)
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}
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err = b.Put([]byte("l"), genesis.Hash)
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if err != nil {
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log.Panic(err)
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}
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tip = genesis.Hash
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} else {
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tip = b.Get([]byte("l"))
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}
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return nil
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})
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if err != nil {
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log.Panic(err)
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}
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bc := Blockchain{tip, db}
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return &bc
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}
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