fix race in proto handshake

net/secureservice/handshake/proto.go

@@ -11,19 +11,20 @@ type ProtoChecker struct {
 	AllowedProtoTypes []handshakeproto.ProtoType
 }
 
-func OutgoingProtoHandshake(ctx context.Context, conn net.Conn, pt handshakeproto.ProtoType) (err error) {
+func OutgoingProtoHandshake(ctx context.Context, conn net.Conn, pt handshakeproto.ProtoType) error {
 	if ctx == nil {
 		ctx = context.Background()
 	}
 	h := newHandshake()
 	done := make(chan struct{})
+	var err error
 	go func() {
 		defer close(done)
 		err = outgoingProtoHandshake(h, conn, pt)
 	}()
 	select {
 	case <-done:
-		return
+		return err
 	case <-ctx.Done():
 		_ = conn.Close()
 		return ctx.Err()
@@ -54,19 +55,23 @@ func outgoingProtoHandshake(h *handshake, conn net.Conn, pt handshakeproto.Proto
 	return HandshakeError{e: msg.ack.Error}
 }
 
-func IncomingProtoHandshake(ctx context.Context, conn net.Conn, pt ProtoChecker) (protoType handshakeproto.ProtoType, err error) {
+func IncomingProtoHandshake(ctx context.Context, conn net.Conn, pt ProtoChecker) (handshakeproto.ProtoType, error) {
 	if ctx == nil {
 		ctx = context.Background()
 	}
 	h := newHandshake()
 	done := make(chan struct{})
+	var (
+		protoType handshakeproto.ProtoType
+		err       error
+	)
 	go func() {
 		defer close(done)
 		protoType, err = incomingProtoHandshake(h, conn, pt)
 	}()
 	select {
 	case <-done:
-		return
+		return protoType, err
 	case <-ctx.Done():
 		_ = conn.Close()
 		return 0, ctx.Err()