protocol: refactor getblocks payload

closes #890

pkg/network/payload/getblocks.go

@@ -1,6 +1,8 @@
 package payload
 
 import (
+	"errors"
+
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 )
@@ -13,27 +15,30 @@ const (
 // GetBlocks contains fields and methods to be shared with the
 type GetBlocks struct {
 	// hash of latest block that node requests
-	HashStart []util.Uint256
-	// hash of last block that node requests
-	HashStop util.Uint256
+	HashStart util.Uint256
+	Count     int16
 }
 
 // NewGetBlocks returns a pointer to a GetBlocks object.
-func NewGetBlocks(start []util.Uint256, stop util.Uint256) *GetBlocks {
+func NewGetBlocks(start util.Uint256, count int16) *GetBlocks {
 	return &GetBlocks{
 		HashStart: start,
-		HashStop:  stop,
+		Count:     count,
 	}
 }
 
 // DecodeBinary implements Serializable interface.
 func (p *GetBlocks) DecodeBinary(br *io.BinReader) {
-	br.ReadArray(&p.HashStart)
-	br.ReadBytes(p.HashStop[:])
+	p.HashStart.DecodeBinary(br)
+	p.Count = int16(br.ReadU16LE())
+	if p.Count < -1 || p.Count == 0 {
+		br.Err = errors.New("invalid count")
+	}
+
 }
 
 // EncodeBinary implements Serializable interface.
 func (p *GetBlocks) EncodeBinary(bw *io.BinWriter) {
-	bw.WriteArray(p.HashStart)
-	bw.WriteBytes(p.HashStop[:])
+	p.HashStart.EncodeBinary(bw)
+	bw.WriteU16LE(uint16(p.Count))
 }

pkg/network/payload/getblocks_test.go

@@ -5,31 +5,24 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/internal/testserdes"
-	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/require"
 )
 
 func TestGetBlockEncodeDecode(t *testing.T) {
-	start := []util.Uint256{
-		hash.Sha256([]byte("a")),
-		hash.Sha256([]byte("b")),
-		hash.Sha256([]byte("c")),
-		hash.Sha256([]byte("d")),
-	}
+	start := hash.Sha256([]byte("a"))
 
-	p := NewGetBlocks(start, util.Uint256{})
+	p := NewGetBlocks(start, 124)
 	testserdes.EncodeDecodeBinary(t, p, new(GetBlocks))
-}
 
-func TestGetBlockEncodeDecodeWithHashStop(t *testing.T) {
-	var (
-		start = []util.Uint256{
-			hash.Sha256([]byte("a")),
-			hash.Sha256([]byte("b")),
-			hash.Sha256([]byte("c")),
-			hash.Sha256([]byte("d")),
-		}
-		stop = hash.Sha256([]byte("e"))
-	)
-	p := NewGetBlocks(start, stop)
-	testserdes.EncodeDecodeBinary(t, p, new(GetBlocks))
+	// invalid count
+	p = NewGetBlocks(start, -2)
+	data, err := testserdes.EncodeBinary(p)
+	require.NoError(t, err)
+	require.Error(t, testserdes.DecodeBinary(data, new(GetBlocks)))
+
+	// invalid count
+	p = NewGetBlocks(start, 0)
+	data, err = testserdes.EncodeBinary(p)
+	require.NoError(t, err)
+	require.Error(t, testserdes.DecodeBinary(data, new(GetBlocks)))
 }

pkg/network/server.go

@@ -535,21 +535,18 @@ func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error {
 
 // handleGetBlocksCmd processes the getblocks request.
 func (s *Server) handleGetBlocksCmd(p Peer, gb *payload.GetBlocks) error {
-	if len(gb.HashStart) < 1 {
-		return errInvalidHashStart
+	count := gb.Count
+	if gb.Count < 0 || gb.Count > payload.MaxHashesCount {
+		count = payload.MaxHashesCount
 	}
-	startHash := gb.HashStart[0]
-	if startHash.Equals(gb.HashStop) {
-		return nil
-	}
-	start, err := s.chain.GetHeader(startHash)
+	start, err := s.chain.GetHeader(gb.HashStart)
 	if err != nil {
 		return err
 	}
 	blockHashes := make([]util.Uint256, 0)
-	for i := start.Index + 1; i < start.Index+1+payload.MaxHashesCount; i++ {
+	for i := start.Index + 1; i < start.Index+uint32(count); i++ {
 		hash := s.chain.GetHeaderHash(int(i))
-		if hash.Equals(util.Uint256{}) || hash.Equals(gb.HashStop) {
+		if hash.Equals(util.Uint256{}) {
 			break
 		}
 		blockHashes = append(blockHashes, hash)
@@ -565,19 +562,19 @@ func (s *Server) handleGetBlocksCmd(p Peer, gb *payload.GetBlocks) error {
 
 // handleGetHeadersCmd processes the getheaders request.
 func (s *Server) handleGetHeadersCmd(p Peer, gh *payload.GetBlocks) error {
-	if len(gh.HashStart) < 1 {
-		return errInvalidHashStart
+	count := gh.Count
+	if gh.Count < 0 || gh.Count > payload.MaxHashesCount {
+		count = payload.MaxHashesCount
 	}
-	startHash := gh.HashStart[0]
-	start, err := s.chain.GetHeader(startHash)
+	start, err := s.chain.GetHeader(gh.HashStart)
 	if err != nil {
 		return err
 	}
 	resp := payload.Headers{}
 	resp.Hdrs = make([]*block.Header, 0, payload.MaxHeadersAllowed)
-	for i := start.Index + 1; i < start.Index+1+payload.MaxHeadersAllowed; i++ {
+	for i := start.Index + 1; i < start.Index+uint32(count); i++ {
 		hash := s.chain.GetHeaderHash(int(i))
-		if hash.Equals(util.Uint256{}) || hash.Equals(gh.HashStop) {
+		if hash.Equals(util.Uint256{}) {
 			break
 		}
 		header, err := s.chain.GetHeader(hash)
@@ -637,10 +634,9 @@ func (s *Server) handleGetAddrCmd(p Peer) error {
 }
 
 // requestHeaders sends a getheaders message to the peer.
-// The peer will respond with headers op to a count of 2000.
+// The peer will respond with headers op to a count of 500.
 func (s *Server) requestHeaders(p Peer) error {
-	start := []util.Uint256{s.chain.CurrentHeaderHash()}
-	payload := payload.NewGetBlocks(start, util.Uint256{})
+	payload := payload.NewGetBlocks(s.chain.CurrentHeaderHash(), -1)
 	return p.EnqueueP2PMessage(NewMessage(CMDGetHeaders, payload))
 }