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97 lines
2.0 KiB
97 lines
2.0 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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"encoding/hex"
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"fmt"
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"log"
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)
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// Transaction represents a Bitcoin transaction
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type Transaction struct {
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ID []byte
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TxInput []TXInput
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TxOutput []TXOutput
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}
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// TXOutput is the struct of transaction output in a transaction.
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type TXOutput struct {
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Value int
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Address string
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}
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// TXInput is the struct of transaction input in a transaction.
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type TXInput struct {
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TxID []byte
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TxOutputIndex int
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Address string
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}
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// DefaultCoinbaseValue is the default value of coinbase transaction.
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const DefaultCoinbaseValue = 10
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// SetID sets ID of a transaction
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func (tx *Transaction) SetID() {
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var encoded bytes.Buffer
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var hash [32]byte
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enc := gob.NewEncoder(&encoded)
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err := enc.Encode(tx)
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if err != nil {
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log.Panic(err)
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}
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hash = sha256.Sum256(encoded.Bytes())
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tx.ID = hash[:]
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}
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// NewCoinbaseTX creates a new coinbase transaction
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func NewCoinbaseTX(to, data string) *Transaction {
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if data == "" {
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data = fmt.Sprintf("Reward to '%s'", to)
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}
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txin := TXInput{[]byte{}, -1, data}
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txout := TXOutput{DefaultCoinbaseValue, to}
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tx := Transaction{nil, []TXInput{txin}, []TXOutput{txout}}
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tx.SetID()
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return &tx
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}
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// NewUTXOTransaction creates a new transaction
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func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transaction {
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var inputs []TXInput
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var outputs []TXOutput
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acc, validOutputs := bc.FindSpendableOutputs(from, amount)
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if acc < amount {
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log.Panic("ERROR: Not enough funds")
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}
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// Build a list of inputs
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for txid, outs := range validOutputs {
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txID, err := hex.DecodeString(txid)
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if err != nil {
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log.Panic(err)
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}
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for _, out := range outs {
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input := TXInput{txID, out, from}
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inputs = append(inputs, input)
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}
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}
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// Build a list of outputs
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outputs = append(outputs, TXOutput{amount, to})
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if acc > amount {
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outputs = append(outputs, TXOutput{acc - amount, from}) // a change
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}
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tx := Transaction{nil, inputs, outputs}
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tx.SetID()
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return &tx
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}
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