[#84] Add GRPC layer of netmap service

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/network/transport/netmap/grpc/service.go

@@ -0,0 +1,35 @@
+package grpc
+
+import (
+	"context"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/netmap"
+	netmapGRPC "github.com/nspcc-dev/neofs-api-go/v2/netmap/grpc"
+)
+
+// Server wraps NeoFS API Netmap service and
+// provides gRPC Netmap service server interface.
+type Server struct {
+	srv netmap.Service
+}
+
+// New creates, initializes and returns Server instance.
+func New(c netmap.Service) *Server {
+	return &Server{
+		srv: c,
+	}
+}
+
+// LocalNodeInfo converts gRPC request message and passes it to internal netmap service.
+func (s *Server) LocalNodeInfo(
+	ctx context.Context,
+	req *netmapGRPC.LocalNodeInfoRequest) (*netmapGRPC.LocalNodeInfoResponse, error) {
+
+	resp, err := s.srv.LocalNodeInfo(ctx, netmap.LocalNodeInfoRequestFromGRPCMessage(req))
+	if err != nil {
+		// TODO: think about how we transport errors through gRPC
+		return nil, err
+	}
+
+	return netmap.LocalNodeInfoResponseToGRPCMessage(resp), nil
+}