reject NEW_TOKEN frames with empty tokens

internal/wire/frame_parser_test.go

@@ -295,7 +295,7 @@ var _ = Describe("Frame parsing", func() {
 			&ResetStreamFrame{},
 			&StopSendingFrame{},
 			&CryptoFrame{},
-			&NewTokenFrame{},
+			&NewTokenFrame{Token: []byte("lorem ipsum")},
 			&StreamFrame{Data: []byte("foobar")},
 			&MaxDataFrame{},
 			&MaxStreamDataFrame{},

internal/wire/new_token_frame.go

@@ -2,6 +2,7 @@ package wire
 
 import (
 	"bytes"
+	"errors"
 	"io"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
@@ -24,6 +25,9 @@ func parseNewTokenFrame(r *bytes.Reader, _ protocol.VersionNumber) (*NewTokenFra
 	if uint64(r.Len()) < tokenLen {
 		return nil, io.EOF
 	}
+	if tokenLen == 0 {
+		return nil, errors.New("Token must not be empty.")
+	}
 	token := make([]byte, int(tokenLen))
 	if _, err := io.ReadFull(r, token); err != nil {
 		return nil, err

internal/wire/new_token_frame_test.go

@@ -24,6 +24,14 @@ var _ = Describe("NEW_TOKEN frame", func() {
 			Expect(b.Len()).To(BeZero())
 		})
 
+		It("rejects empty tokens", func() {
+			data := []byte{0x7}
+			data = append(data, encodeVarInt(uint64(0))...)
+			b := bytes.NewReader(data)
+			_, err := parseNewTokenFrame(b, protocol.VersionWhatever)
+			Expect(err).To(MatchError("Token must not be empty."))
+		})
+
 		It("errors on EOFs", func() {
 			token := "Lorem ipsum dolor sit amet, consectetur adipiscing elit"
 			data := []byte{0x7}