transactions

blockchain/transaction.go

@@ -0,0 +1,97 @@
+package blockchain
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/gob"
+	"encoding/hex"
+	"fmt"
+	"log"
+)
+
+type Transaction struct {
+	ID      []byte
+	Inputs  []TxInput
+	Outputs []TxOutput
+}
+
+type TxOutput struct {
+	Value  int
+	PubKey string
+}
+
+type TxInput struct {
+	ID  []byte
+	Out int
+	Sig string
+}
+
+func (tx *Transaction) SetID() {
+	var encoded bytes.Buffer
+	var hash [32]byte
+
+	encode := gob.NewEncoder(&encoded)
+	err := encode.Encode(tx)
+	Handle(err)
+
+	hash = sha256.Sum256(encoded.Bytes())
+	tx.ID = hash[:]
+}
+
+func CoinbaseTx(to, data string) *Transaction {
+	if data == "" {
+		data = fmt.Sprintf("COints to %s", to)
+	}
+
+	txin := TxInput{[]byte{}, -1, data}
+	txout := TxOutput{100, to}
+
+	tx := Transaction{nil, []TxInput{txin}, []TxOutput{txout}}
+	tx.SetID()
+
+	return &tx
+}
+
+func NewTransaction(from, to string, amount int, chain *BlockChain) *Transaction {
+	var inputs []TxInput
+	var outputs []TxOutput
+
+	acc, validOutputs := chain.FindSpendableOutputs(from, amount)
+
+	if acc < amount {
+		log.Panic("Error: not enough funds")
+	}
+
+	for txid, outs := range validOutputs {
+		txID, err := hex.DecodeString(txid)
+		Handle(err)
+
+		for _, out := range outs {
+			input := TxInput{txID, out, from}
+			inputs = append(inputs, input)
+		}
+	}
+
+	outputs = append(outputs, TxOutput{amount, to})
+
+	if acc > amount {
+		outputs = append(outputs, TxOutput{acc - amount, from})
+	}
+
+	tx := Transaction{nil, inputs, outputs}
+	tx.SetID()
+
+	return &tx
+}
+
+func (tx *Transaction) IsCoinbase() bool {
+	return len(tx.Inputs) == 1 && len(tx.Inputs[0].ID) == 0 && tx.Inputs[0].Out == -1
+}
+
+func (in *TxInput) CanUnlock(data string) bool {
+	return in.Sig == data
+}
+
+func (out *TxOutput) CanBeUnlocked(data string) bool {
+	return out.PubKey == data
+}