139 lines
2.7 KiB
Go
139 lines
2.7 KiB
Go
package main
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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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"os"
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)
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const subsidy = 10
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// Transaction represents a blockchain transaction
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type Transaction struct {
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ID []byte
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Vin []TXInput
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Vout []TXOutput
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}
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// IsCoinbase checks whether the transaction is a coinbase
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func (tx Transaction) IsCoinbase() bool {
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return len(tx.Vin) == 1 && len(tx.Vin[0].Txid) == 0 && tx.Vin[0].Vout == -1
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}
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// SetID sets the 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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exitWithError(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{
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Txid: []byte{},
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Vout: -1,
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ScriptSig: data,
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}
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txout := TXOutput{
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Value: subsidy,
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ScriptPubKey: to,
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}
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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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fmt.Println("ERROR: Not enough funds")
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os.Exit(1)
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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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fmt.Println(err)
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os.Exit(1)
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}
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for _, out := range outs {
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input := TXInput{
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Txid: txID,
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Vout: out,
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ScriptSig: from,
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}
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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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output := TXOutput{
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Value: amount,
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ScriptPubKey: to,
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}
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outputs = append(outputs, output)
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if acc > amount {
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// There is some change
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chgOutput := TXOutput{
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Value: acc - amount,
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ScriptPubKey: from,
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}
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outputs = append(outputs, chgOutput)
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}
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tx := Transaction{
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ID: nil,
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Vin: inputs,
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Vout: outputs,
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}
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tx.SetID()
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return &tx
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}
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// TXInput represents a transaction input
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type TXInput struct {
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Txid []byte
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Vout int
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ScriptSig string
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}
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// CanUnlockOutputWith checks whether the unlockingData (address) initiated the transaction
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func (in *TXInput) CanUnlockOutputWith(unlockingData string) bool {
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return in.ScriptSig == unlockingData
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}
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// TXOutput represents a transaction output
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type TXOutput struct {
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Value int
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ScriptPubKey string
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}
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// CanBeUnlockedWith checks if the output can be unlocked with the provided data
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func (out *TXOutput) CanBeUnlockedWith(unlockingData string) bool {
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return out.ScriptPubKey == unlockingData
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}
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