blockchain sandbox: UTXO chain, p2p mining, attacker node

p2p/miner.go

@@ -0,0 +1,98 @@
+package p2p
+
+import (
+	"blockchain/chain"
+	"blockchain/config"
+	"crypto/sha256"
+	"encoding/hex"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type miner struct {
+	hashDelay *time.Duration
+	onMined   func(*chain.Block, time.Duration)
+	work      chan *chain.Block
+}
+
+func newMiner(hashDelay *time.Duration, onMined func(*chain.Block, time.Duration)) *miner {
+	return &miner{
+		hashDelay: hashDelay,
+		onMined:   onMined,
+		work:      make(chan *chain.Block, 1),
+	}
+}
+
+// SubmitWork sends a new block template to the miner.
+// If the miner is busy, the previous job is cancelled automatically.
+func (m *miner) SubmitWork(block *chain.Block) {
+	// drain old work if any
+	select {
+	case <-m.work:
+	default:
+	}
+	m.work <- block
+}
+
+func (m *miner) Run(stop <-chan struct{}) {
+	var (
+		cancel chan struct{}
+		done   chan bool
+		t0     time.Time
+		block  *chain.Block
+	)
+
+	for {
+		select {
+		case block = <-m.work:
+			// cancel previous mining if running
+			if cancel != nil {
+				close(cancel)
+				<-done
+			}
+			cancel = make(chan struct{})
+			done = make(chan bool, 1)
+			t0 = time.Now()
+			go func(b *chain.Block, c chan struct{}, d chan bool) {
+				d <- mine(b, c, *m.hashDelay)
+			}(block, cancel, done)
+
+		case ok := <-done:
+			cancel = nil
+			done = nil
+			if ok {
+				m.onMined(block, time.Since(t0))
+			}
+
+		case <-stop:
+			if cancel != nil {
+				close(cancel)
+			}
+			return
+		}
+	}
+}
+
+// mine перебирает nonce пока хеш не начнётся с нужного кол-ва нулей.
+func mine(block *chain.Block, cancel chan struct{}, hashDelay time.Duration) bool {
+	prefix := strings.Repeat("0", config.Default.Chain.Difficulty)
+	base := block.HashBase()
+	for {
+		select {
+		case <-cancel:
+			return false
+		default:
+		}
+		data := base + strconv.Itoa(block.Nonce)
+		h := sha256.Sum256([]byte(data))
+		block.Hash = hex.EncodeToString(h[:])
+		if strings.HasPrefix(block.Hash, prefix) {
+			return true
+		}
+		block.Nonce++
+		if hashDelay > 0 {
+			time.Sleep(hashDelay)
+		}
+	}
+}