Fixed header sync issue (#17)

* headers can now sync till infinity

* fixed empty hashStop getBlock payload + test

* added more test + more binary decoding/encoding

* bump version

VERSION

@@ -1 +1 @@
-0.7.0
+0.8.0

pkg/core/block.go

@@ -36,16 +36,32 @@ type BlockBase struct {
 
 // DecodeBinary implements the payload interface.
 func (b *BlockBase) DecodeBinary(r io.Reader) error {
-	binary.Read(r, binary.LittleEndian, &b.Version)
-	binary.Read(r, binary.LittleEndian, &b.PrevHash)
-	binary.Read(r, binary.LittleEndian, &b.MerkleRoot)
-	binary.Read(r, binary.LittleEndian, &b.Timestamp)
-	binary.Read(r, binary.LittleEndian, &b.Index)
-	binary.Read(r, binary.LittleEndian, &b.ConsensusData)
-	binary.Read(r, binary.LittleEndian, &b.NextConsensus)
+	if err := binary.Read(r, binary.LittleEndian, &b.Version); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.PrevHash); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.MerkleRoot); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.Timestamp); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.Index); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.ConsensusData); err != nil {
+		return err
+	}
+	if err := binary.Read(r, binary.LittleEndian, &b.NextConsensus); err != nil {
+		return err
+	}
 
 	var padding uint8
-	binary.Read(r, binary.LittleEndian, &padding)
+	if err := binary.Read(r, binary.LittleEndian, &padding); err != nil {
+		return err
+	}
 	if padding != 1 {
 		return fmt.Errorf("format error: padding must equal 1 got %d", padding)
 	}
@@ -86,6 +102,21 @@ func (b *BlockBase) encodeHashableFields(w io.Writer) error {
 	return err
 }
 
+// EncodeBinary implements the Payload interface
+func (b *BlockBase) EncodeBinary(w io.Writer) error {
+	if err := b.encodeHashableFields(w); err != nil {
+		return err
+	}
+
+	// padding
+	if err := binary.Write(w, binary.LittleEndian, uint8(1)); err != nil {
+		return err
+	}
+
+	// script
+	return b.Script.EncodeBinary(w)
+}
+
 // Header holds the head info of a block
 type Header struct {
 	BlockBase
@@ -115,7 +146,12 @@ func (h *Header) DecodeBinary(r io.Reader) error {
 
 // EncodeBinary  impelements the Payload interface.
 func (h *Header) EncodeBinary(w io.Writer) error {
-	return nil
+	if err := h.BlockBase.EncodeBinary(w); err != nil {
+		return err
+	}
+
+	// padding
+	return binary.Write(w, binary.LittleEndian, uint8(0))
 }
 
 // Block represents one block in the chain.

pkg/core/block_test.go

@@ -82,7 +82,10 @@ func newBlockBase() BlockBase {
 		Index:         1,
 		ConsensusData: 1111,
 		NextConsensus: util.Uint160{},
-		Script:        &Witness{},
+		Script: &Witness{
+			VerificationScript: []byte{0x0},
+			InvocationScript:   []byte{0x1},
+		},
 	}
 }
 

pkg/core/blockchain.go

@@ -191,6 +191,11 @@ func (bc *Blockchain) CurrentBlockHash() (hash util.Uint256) {
 	return bc.headerIndex[bc.currentBlockHeight]
 }
 
+// CurrentHeaderHash returns the hash of the latest known header.
+func (bc *Blockchain) CurrentHeaderHash() (hash util.Uint256) {
+	return bc.headerIndex[len(bc.headerIndex)-1]
+}
+
 // BlockHeight return the height/index of the latest block this node has.
 func (bc *Blockchain) BlockHeight() uint32 {
 	return bc.currentBlockHeight

pkg/core/blockchain_test.go

@@ -31,9 +31,9 @@ func TestAddHeaders(t *testing.T) {
 	startHash, _ := util.Uint256DecodeFromString("996e37358dc369912041f966f8c5d8d3a8255ba5dcbd3447f8a82b55db869099")
 	bc := NewBlockchain(NewMemoryStore(), log.New(os.Stdout, "", 0), startHash)
 
-	h1 := &Header{BlockBase: BlockBase{Version: 0, Index: 1}}
-	h2 := &Header{BlockBase: BlockBase{Version: 0, Index: 2}}
-	h3 := &Header{BlockBase: BlockBase{Version: 0, Index: 3}}
+	h1 := &Header{BlockBase: BlockBase{Version: 0, Index: 1, Script: &Witness{}}}
+	h2 := &Header{BlockBase: BlockBase{Version: 0, Index: 2, Script: &Witness{}}}
+	h3 := &Header{BlockBase: BlockBase{Version: 0, Index: 3, Script: &Witness{}}}
 
 	if err := bc.AddHeaders(h1, h2, h3); err != nil {
 		t.Fatal(err)

pkg/core/header_test.go

@@ -0,0 +1,61 @@
+package core
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"testing"
+	"time"
+
+	"github.com/CityOfZion/neo-go/pkg/util"
+)
+
+func TestHeaderEncodeDecode(t *testing.T) {
+	header := Header{BlockBase: BlockBase{
+		Version:       0,
+		PrevHash:      sha256.Sum256([]byte("prevhash")),
+		MerkleRoot:    sha256.Sum256([]byte("merkleroot")),
+		Timestamp:     uint32(time.Now().UTC().Unix()),
+		Index:         3445,
+		ConsensusData: 394949,
+		NextConsensus: util.Uint160{},
+		Script: &Witness{
+			InvocationScript:   []byte{0x10},
+			VerificationScript: []byte{0x11},
+		},
+	}}
+
+	buf := new(bytes.Buffer)
+	if err := header.EncodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
+
+	headerDecode := &Header{}
+	if err := headerDecode.DecodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
+	if header.Version != headerDecode.Version {
+		t.Fatal("expected both versions to be equal")
+	}
+	if !header.PrevHash.Equals(headerDecode.PrevHash) {
+		t.Fatal("expected both prev hashes to be equal")
+	}
+	if !header.MerkleRoot.Equals(headerDecode.MerkleRoot) {
+		t.Fatal("expected both merkle roots to be equal")
+	}
+	if header.Index != headerDecode.Index {
+		t.Fatal("expected both indexes to be equal")
+	}
+	if header.ConsensusData != headerDecode.ConsensusData {
+		t.Fatal("expected both consensus data fields to be equal")
+	}
+	if !header.NextConsensus.Equals(headerDecode.NextConsensus) {
+		t.Fatalf("expected both next consensus fields to be equal")
+	}
+
+	if bytes.Compare(header.Script.InvocationScript, headerDecode.Script.InvocationScript) != 0 {
+		t.Fatalf("expected equal invocation scripts %v and %v", header.Script.InvocationScript, headerDecode.Script.InvocationScript)
+	}
+	if bytes.Compare(header.Script.VerificationScript, headerDecode.Script.VerificationScript) != 0 {
+		t.Fatalf("expected equal verification scripts %v and %v", header.Script.VerificationScript, headerDecode.Script.VerificationScript)
+	}
+}

pkg/core/witness.go

@@ -32,5 +32,10 @@ func (wit *Witness) DecodeBinary(r io.Reader) error {
 
 // EncodeBinary implements the payload interface.
 func (wit *Witness) EncodeBinary(w io.Writer) error {
-	return nil
+	util.WriteVarUint(w, uint64(len(wit.InvocationScript)))
+	if err := binary.Write(w, binary.LittleEndian, wit.InvocationScript); err != nil {
+		return err
+	}
+	util.WriteVarUint(w, uint64(len(wit.VerificationScript)))
+	return binary.Write(w, binary.LittleEndian, wit.VerificationScript)
 }

pkg/network/payload/addr.go

@@ -49,7 +49,7 @@ func (p *AddrWithTime) EncodeBinary(w io.Writer) error {
 	return err
 }
 
-// AddressList holds a slice of AddrWithTime.
+// AddressList is a list with AddrWithTime.
 type AddressList struct {
 	Addrs []*AddrWithTime
 }

pkg/network/payload/addr_test.go

@@ -33,14 +33,13 @@ func TestEncodeDecodeAddr(t *testing.T) {
 
 func TestEncodeDecodeAddressList(t *testing.T) {
 	var lenList uint8 = 4
-	addrs := make([]*AddrWithTime, lenList)
+	addrList := &AddressList{make([]*AddrWithTime, lenList)}
 	for i := 0; i < int(lenList); i++ {
 		e, _ := util.EndpointFromString(fmt.Sprintf("127.0.0.1:200%d", i))
-		addrs[i] = NewAddrWithTime(e)
+		addrList.Addrs[i] = NewAddrWithTime(e)
 	}
 
 	buf := new(bytes.Buffer)
-	addrList := &AddressList{addrs}
 	if err := addrList.EncodeBinary(buf); err != nil {
 		t.Fatal(err)
 	}

pkg/network/payload/getblocks.go

@@ -2,7 +2,6 @@ package payload
 
 import (
 	"encoding/binary"
-	"fmt"
 	"io"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
@@ -18,21 +17,23 @@ type GetBlocks struct {
 
 // NewGetBlocks return a pointer to a GetBlocks object.
 func NewGetBlocks(start []util.Uint256, stop util.Uint256) *GetBlocks {
-	p := &GetBlocks{}
-	p.HashStart = start
-	p.HashStop = stop
-	return p
+	return &GetBlocks{
+		HashStart: start,
+		HashStop:  stop,
+	}
 }
 
 // DecodeBinary implements the payload interface.
 func (p *GetBlocks) DecodeBinary(r io.Reader) error {
 	lenStart := util.ReadVarUint(r)
-	fmt.Println(lenStart)
 	p.HashStart = make([]util.Uint256, lenStart)
-	err := binary.Read(r, binary.LittleEndian, &p.HashStart)
-	err = binary.Read(r, binary.LittleEndian, &p.HashStop)
 
-	fmt.Println(p)
+	if err := binary.Read(r, binary.LittleEndian, &p.HashStart); err != nil {
+		return err
+	}
+
+	// If the reader returns EOF we know the hashStop is not encoded.
+	err := binary.Read(r, binary.LittleEndian, &p.HashStop)
 	if err == io.EOF {
 		return nil
 	}
@@ -42,11 +43,20 @@ func (p *GetBlocks) DecodeBinary(r io.Reader) error {
 
 // EncodeBinary implements the payload interface.
 func (p *GetBlocks) EncodeBinary(w io.Writer) error {
-	err := util.WriteVarUint(w, uint64(len(p.HashStart)))
-	err = binary.Write(w, binary.LittleEndian, p.HashStart)
-	//err = binary.Write(w, binary.LittleEndian, p.HashStop)
+	if err := util.WriteVarUint(w, uint64(len(p.HashStart))); err != nil {
+		return err
+	}
+	if err := binary.Write(w, binary.LittleEndian, p.HashStart); err != nil {
+		return err
+	}
 
-	return err
+	// Only write hashStop if its not filled with zero bytes.
+	var emtpy util.Uint256
+	if p.HashStop != emtpy {
+		return binary.Write(w, binary.LittleEndian, p.HashStop)
+	}
+
+	return nil
 }
 
 // Size implements the payload interface.

pkg/network/payload/getblocks_test.go

@@ -1,58 +1,60 @@
 package payload
 
-// TODO: Currently the hashstop is not encoded, therefore this test will fail.
-// Need to figure some stuff how to handle this properly.
-// - anthdm 04/02/2018
+import (
+	"bytes"
+	"crypto/sha256"
+	"reflect"
+	"testing"
 
-// func TestGetBlocksEncodeDecode(t *testing.T) {
-// 	hash, _ := util.Uint256DecodeFromString("d42561e3d30e15be6400b6df2f328e02d2bf6354c41dce433bc57687c82144bf")
+	"github.com/CityOfZion/neo-go/pkg/util"
+)
 
-// 	start := []util.Uint256{
-// 		hash,
-// 		sha256.Sum256([]byte("a")),
-// 		sha256.Sum256([]byte("b")),
-// 		sha256.Sum256([]byte("c")),
-// 	}
-// 	stop := sha256.Sum256([]byte("d"))
+func TestGetBlockEncodeDecode(t *testing.T) {
+	start := []util.Uint256{
+		sha256.Sum256([]byte("a")),
+		sha256.Sum256([]byte("b")),
+		sha256.Sum256([]byte("c")),
+		sha256.Sum256([]byte("d")),
+	}
 
-// 	p := NewGetBlocks(start, stop)
-// 	buf := new(bytes.Buffer)
-// 	if err := p.EncodeBinary(buf); err != nil {
-// 		t.Fatal(err)
-// 	}
+	p := NewGetBlocks(start, util.Uint256{})
+	buf := new(bytes.Buffer)
+	if err := p.EncodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
 
-// 	pDecode := &GetBlocks{}
-// 	if err := pDecode.DecodeBinary(buf); err != nil {
-// 		t.Fatal(err)
-// 	}
+	pDecode := &GetBlocks{}
+	if err := pDecode.DecodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
 
-// 	if !reflect.DeepEqual(p, pDecode) {
-// 		t.Fatalf("expecting both getblocks payloads to be equal %v and %v", p, pDecode)
-// 	}
-// }
+	if !reflect.DeepEqual(p, pDecode) {
+		t.Fatalf("expected to have equal block payload %v and %v", p, pDecode)
+	}
+}
 
-// TODO: Currently the hashstop is not encoded, therefore this test will fail.
-// Need to figure some stuff how to handle this properly.
-// - anthdm 04/02/2018
-//
-// func TestGetBlocksWithEmptyHashStop(t *testing.T) {
-// 	start := []util.Uint256{
-// 		sha256.Sum256([]byte("a")),
-// 	}
-// 	stop := util.Uint256{}
+func TestGetBlockEncodeDecodeWithHashStop(t *testing.T) {
+	var (
+		start = []util.Uint256{
+			sha256.Sum256([]byte("a")),
+			sha256.Sum256([]byte("b")),
+			sha256.Sum256([]byte("c")),
+			sha256.Sum256([]byte("d")),
+		}
+		stop = sha256.Sum256([]byte("e"))
+	)
+	p := NewGetBlocks(start, stop)
+	buf := new(bytes.Buffer)
+	if err := p.EncodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
 
-// 	buf := new(bytes.Buffer)
-// 	p := NewGetBlocks(start, stop)
-// 	if err := p.EncodeBinary(buf); err != nil {
-// 		t.Fatal(err)
-// 	}
+	pDecode := &GetBlocks{}
+	if err := pDecode.DecodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
 
-// 	pDecode := &GetBlocks{}
-// 	if err := pDecode.DecodeBinary(buf); err != nil {
-// 		t.Fatal(err)
-// 	}
-
-// 	if !reflect.DeepEqual(p, pDecode) {
-// 		t.Fatalf("expecting both getblocks payloads to be equal %v and %v", p, pDecode)
-// 	}
-// }
+	if !reflect.DeepEqual(p, pDecode) {
+		t.Fatalf("expected to have equal block payload %v and %v", p, pDecode)
+	}
+}

pkg/network/payload/headers.go

@@ -30,6 +30,13 @@ func (p *Headers) DecodeBinary(r io.Reader) error {
 }
 
 // EncodeBinary implements the Payload interface.
-func (h *Headers) EncodeBinary(w io.Writer) error {
+func (p *Headers) EncodeBinary(w io.Writer) error {
+	util.WriteVarUint(w, uint64(len(p.Hdrs)))
+	for _, header := range p.Hdrs {
+		if err := header.EncodeBinary(w); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }

pkg/network/payload/headers_test.go

@@ -0,0 +1,55 @@
+package payload
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+
+	"github.com/CityOfZion/neo-go/pkg/core"
+)
+
+func TestHeadersEncodeDecode(t *testing.T) {
+	headers := &Headers{[]*core.Header{
+		&core.Header{
+			BlockBase: core.BlockBase{
+				Version: 0,
+				Index:   1,
+				Script: &core.Witness{
+					InvocationScript:   []byte{0x0},
+					VerificationScript: []byte{0x1},
+				},
+			}},
+		&core.Header{
+			BlockBase: core.BlockBase{
+				Version: 0,
+				Index:   2,
+				Script: &core.Witness{
+					InvocationScript:   []byte{0x0},
+					VerificationScript: []byte{0x1},
+				},
+			}},
+		&core.Header{
+			BlockBase: core.BlockBase{
+				Version: 0,
+				Index:   3,
+				Script: &core.Witness{
+					InvocationScript:   []byte{0x0},
+					VerificationScript: []byte{0x1},
+				},
+			}},
+	}}
+
+	buf := new(bytes.Buffer)
+	if err := headers.EncodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
+
+	headersDecode := &Headers{}
+	if err := headersDecode.DecodeBinary(buf); err != nil {
+		t.Fatal(err)
+	}
+
+	if !reflect.DeepEqual(headers, headersDecode) {
+		t.Fatalf("expected both header payload to be equal %+v and %+v", headers, headersDecode)
+	}
+}

pkg/network/peer.go

@@ -41,7 +41,8 @@ func (p *LocalPeer) version() *payload.Version {
 }
 
 func (p *LocalPeer) callVersion(msg *Message) error {
-	return p.s.handleVersionCmd(msg, p)
+	version := msg.Payload.(*payload.Version)
+	return p.s.handleVersionCmd(version, p)
 }
 
 func (p *LocalPeer) callVerack(msg *Message) error {

pkg/network/server.go

@@ -212,8 +212,7 @@ func (s *Server) handlePeerConnected(p Peer) error {
 	return p.callVersion(msg)
 }
 
-func (s *Server) handleVersionCmd(msg *Message, p Peer) error {
-	version := msg.Payload.(*payload.Version)
+func (s *Server) handleVersionCmd(version *payload.Version, p Peer) error {
 	if s.id == version.Nonce {
 		return errors.New("identical nonce")
 	}
@@ -230,8 +229,7 @@ func (s *Server) handleGetaddrCmd(msg *Message, p Peer) error {
 
 // The node can broadcast the object information it owns by this message.
 // The message can be sent automatically or can be used to answer getbloks messages.
-func (s *Server) handleInvCmd(msg *Message, p Peer) error {
-	inv := msg.Payload.(*payload.Inventory)
+func (s *Server) handleInvCmd(inv *payload.Inventory, p Peer) error {
 	if !inv.Type.Valid() {
 		return fmt.Errorf("invalid inventory type %s", inv.Type)
 	}
@@ -248,8 +246,7 @@ func (s *Server) handleInvCmd(msg *Message, p Peer) error {
 }
 
 // handleBlockCmd processes the received block.
-func (s *Server) handleBlockCmd(msg *Message, p Peer) error {
-	block := msg.Payload.(*core.Block)
+func (s *Server) handleBlockCmd(block *core.Block, p Peer) error {
 	hash, err := block.Hash()
 	if err != nil {
 		return err
@@ -262,8 +259,7 @@ func (s *Server) handleBlockCmd(msg *Message, p Peer) error {
 
 // After receiving the getaddr message, the node returns an addr message as response
 // and provides information about the known nodes on the network.
-func (s *Server) handleAddrCmd(msg *Message, p Peer) error {
-	addrList := msg.Payload.(*payload.AddressList)
+func (s *Server) handleAddrCmd(addrList *payload.AddressList, p Peer) error {
 	for _, addr := range addrList.Addrs {
 		if !s.peerAlreadyConnected(addr.Addr) {
 			// TODO: this is not transport abstracted.
@@ -285,13 +281,11 @@ func (s *Server) handleHeadersCmd(headers *payload.Headers, p Peer) error {
 
 		// Ask more headers if we are not in sync with the peer.
 		if s.bc.HeaderHeight() < p.version().StartHeight {
-			s.logger.Printf("header height %d peer height %d", s.bc.HeaderHeight(), p.version().StartHeight)
 			if err := s.askMoreHeaders(p); err != nil {
 				s.logger.Printf("getheaders RPC failed: %s", err)
 				return
 			}
 		}
-
 	}(context.TODO(), headers.Hdrs)
 
 	return nil
@@ -299,7 +293,7 @@ func (s *Server) handleHeadersCmd(headers *payload.Headers, p Peer) error {
 
 // Ask the peer for more headers We use the current block hash as start.
 func (s *Server) askMoreHeaders(p Peer) error {
-	start := []util.Uint256{s.bc.CurrentBlockHash()}
+	start := []util.Uint256{s.bc.CurrentHeaderHash()}
 	payload := payload.NewGetBlocks(start, util.Uint256{})
 	msg := newMessage(s.net, cmdGetHeaders, payload)
 

pkg/network/server_test.go

@@ -15,8 +15,7 @@ func TestHandleVersionFailWrongPort(t *testing.T) {
 	p := NewLocalPeer(s)
 
 	version := payload.NewVersion(1337, 1, "/NEO:0.0.0/", 0, true)
-	msg := newMessage(ModeDevNet, cmdVersion, version)
-	if err := s.handleVersionCmd(msg, p); err == nil {
+	if err := s.handleVersionCmd(version, p); err == nil {
 		t.Fatal("expected error got nil")
 	}
 }
@@ -28,8 +27,7 @@ func TestHandleVersionFailIdenticalNonce(t *testing.T) {
 	p := NewLocalPeer(s)
 
 	version := payload.NewVersion(s.id, 1, "/NEO:0.0.0/", 0, true)
-	msg := newMessage(ModeDevNet, cmdVersion, version)
-	if err := s.handleVersionCmd(msg, p); err == nil {
+	if err := s.handleVersionCmd(version, p); err == nil {
 		t.Fatal("expected error got nil")
 	}
 }
@@ -41,9 +39,7 @@ func TestHandleVersion(t *testing.T) {
 	p := NewLocalPeer(s)
 
 	version := payload.NewVersion(1337, p.addr().Port, "/NEO:0.0.0/", 0, true)
-	msg := newMessage(ModeDevNet, cmdVersion, version)
-
-	if err := s.handleVersionCmd(msg, p); err != nil {
+	if err := s.handleVersionCmd(version, p); err != nil {
 		t.Fatal(err)
 	}
 }

pkg/network/tcp.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 
+	"github.com/CityOfZion/neo-go/pkg/core"
 	"github.com/CityOfZion/neo-go/pkg/network/payload"
 	"github.com/CityOfZion/neo-go/pkg/util"
 )
@@ -84,10 +85,10 @@ func handleMessage(s *Server, p *TCPPeer) {
 
 		switch command {
 		case cmdVersion:
-			if err = s.handleVersionCmd(msg, p); err != nil {
+			version := msg.Payload.(*payload.Version)
+			if err = s.handleVersionCmd(version, p); err != nil {
 				break
 			}
-			version := msg.Payload.(*payload.Version)
 			p.nonce = version.Nonce
 			p.pVersion = version
 
@@ -106,19 +107,22 @@ func handleMessage(s *Server, p *TCPPeer) {
 			// start the protocol
 			go s.startProtocol(p)
 		case cmdAddr:
-			err = s.handleAddrCmd(msg, p)
+			addrList := msg.Payload.(*payload.AddressList)
+			err = s.handleAddrCmd(addrList, p)
 		case cmdGetAddr:
 			err = s.handleGetaddrCmd(msg, p)
 		case cmdInv:
-			err = s.handleInvCmd(msg, p)
+			inv := msg.Payload.(*payload.Inventory)
+			err = s.handleInvCmd(inv, p)
 		case cmdBlock:
-			err = s.handleBlockCmd(msg, p)
+			block := msg.Payload.(*core.Block)
+			err = s.handleBlockCmd(block, p)
 		case cmdConsensus:
 		case cmdTX:
 		case cmdVerack:
 			// If we receive a verack here we disconnect. We already handled the verack
 			// when we sended our version.
-			err = errors.New("received verack twice")
+			err = errors.New("verack already received")
 		case cmdGetHeaders:
 		case cmdGetBlocks:
 		case cmdGetData:
@@ -284,6 +288,7 @@ func (p *TCPPeer) writeLoop() {
 		p.disconnect()
 	}()
 
+	// resuse this buffer
 	buf := new(bytes.Buffer)
 	for {
 		t := <-p.send

pkg/util/uint160.go

@@ -22,3 +22,8 @@ func (u Uint160) ToSlice() []byte {
 func (u Uint160) String() string {
 	return hex.EncodeToString(u.ToSlice())
 }
+
+// Equals returns true if both Uint256 values are the same.
+func (u Uint160) Equals(other Uint160) bool {
+	return u.String() == other.String()
+}