reflection/serverreflection.go - third_party/grpc/grpc-go - Git at Google

 /*
  *
  * Copyright 2016 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  */

 //go:generate protoc --go_out=plugins=grpc:. grpc_reflection_v1alpha/reflection.proto

 /*
 Package reflection implements server reflection service.

 The service implemented is defined in:
 https://github.com/grpc/grpc/blob/master/src/proto/grpc/reflection/v1alpha/reflection.proto.

 To register server reflection on a gRPC server:
 	import "google.golang.org/grpc/reflection"

 	s := grpc.NewServer()
 	pb.RegisterYourOwnServer(s, &server{})

 	// Register reflection service on gRPC server.
 	reflection.Register(s)

 	s.Serve(lis)

 */
 package reflection // import "google.golang.org/grpc/reflection"

 import (
 	"bytes"
 	"compress/gzip"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"reflect"
 	"sort"
 	"sync"

 	"github.com/golang/protobuf/proto"
 	dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	rpb "google.golang.org/grpc/reflection/grpc_reflection_v1alpha"
 	"google.golang.org/grpc/status"
 )

 type serverReflectionServer struct {
 	s *grpc.Server

 	initSymbols  sync.Once
 	serviceNames []string
 	symbols      map[string]*dpb.FileDescriptorProto // map of fully-qualified names to files
 }

 // Register registers the server reflection service on the given gRPC server.
 func Register(s *grpc.Server) {
 	rpb.RegisterServerReflectionServer(s, &serverReflectionServer{
 		s: s,
 	})
 }

 // protoMessage is used for type assertion on proto messages.
 // Generated proto message implements function Descriptor(), but Descriptor()
 // is not part of interface proto.Message. This interface is needed to
 // call Descriptor().
 type protoMessage interface {
 	Descriptor() ([]byte, []int)
 }

 func (s *serverReflectionServer) getSymbols() (svcNames []string, symbolIndex map[string]*dpb.FileDescriptorProto) {
 	s.initSymbols.Do(func() {
 		serviceInfo := s.s.GetServiceInfo()

 		s.symbols = map[string]*dpb.FileDescriptorProto{}
 		s.serviceNames = make([]string, 0, len(serviceInfo))
 		processed := map[string]struct{}{}
 		for svc, info := range serviceInfo {
 			s.serviceNames = append(s.serviceNames, svc)
 			fdenc, ok := parseMetadata(info.Metadata)
 			if !ok {
 				continue
 			}
 			fd, err := decodeFileDesc(fdenc)
 			if err != nil {
 				continue
 			}
 			s.processFile(fd, processed)
 		}
 		sort.Strings(s.serviceNames)
 	})

 	return s.serviceNames, s.symbols
 }

 func (s *serverReflectionServer) processFile(fd *dpb.FileDescriptorProto, processed map[string]struct{}) {
 	filename := fd.GetName()
 	if _, ok := processed[filename]; ok {
 		return
 	}
 	processed[filename] = struct{}{}

 	prefix := fd.GetPackage()

 	for _, msg := range fd.MessageType {
 		s.processMessage(fd, prefix, msg)
 	}
 	for _, en := range fd.EnumType {
 		s.processEnum(fd, prefix, en)
 	}
 	for _, ext := range fd.Extension {
 		s.processField(fd, prefix, ext)
 	}
 	for _, svc := range fd.Service {
 		svcName := fqn(prefix, svc.GetName())
 		s.symbols[svcName] = fd
 		for _, meth := range svc.Method {
 			name := fqn(svcName, meth.GetName())
 			s.symbols[name] = fd
 		}
 	}

 	for _, dep := range fd.Dependency {
 		fdenc := proto.FileDescriptor(dep)
 		fdDep, err := decodeFileDesc(fdenc)
 		if err != nil {
 			continue
 		}
 		s.processFile(fdDep, processed)
 	}
 }

 func (s *serverReflectionServer) processMessage(fd *dpb.FileDescriptorProto, prefix string, msg *dpb.DescriptorProto) {
 	msgName := fqn(prefix, msg.GetName())
 	s.symbols[msgName] = fd

 	for _, nested := range msg.NestedType {
 		s.processMessage(fd, msgName, nested)
 	}
 	for _, en := range msg.EnumType {
 		s.processEnum(fd, msgName, en)
 	}
 	for _, ext := range msg.Extension {
 		s.processField(fd, msgName, ext)
 	}
 	for _, fld := range msg.Field {
 		s.processField(fd, msgName, fld)
 	}
 	for _, oneof := range msg.OneofDecl {
 		oneofName := fqn(msgName, oneof.GetName())
 		s.symbols[oneofName] = fd
 	}
 }

 func (s *serverReflectionServer) processEnum(fd *dpb.FileDescriptorProto, prefix string, en *dpb.EnumDescriptorProto) {
 	enName := fqn(prefix, en.GetName())
 	s.symbols[enName] = fd

 	for _, val := range en.Value {
 		valName := fqn(enName, val.GetName())
 		s.symbols[valName] = fd
 	}
 }

 func (s *serverReflectionServer) processField(fd *dpb.FileDescriptorProto, prefix string, fld *dpb.FieldDescriptorProto) {
 	fldName := fqn(prefix, fld.GetName())
 	s.symbols[fldName] = fd
 }

 func fqn(prefix, name string) string {
 	if prefix == "" {
 		return name
 	}
 	return prefix + "." + name
 }

 // fileDescForType gets the file descriptor for the given type.
 // The given type should be a proto message.
 func (s *serverReflectionServer) fileDescForType(st reflect.Type) (*dpb.FileDescriptorProto, error) {
 	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(protoMessage)
 	if !ok {
 		return nil, fmt.Errorf("failed to create message from type: %v", st)
 	}
 	enc, _ := m.Descriptor()

 	return decodeFileDesc(enc)
 }

 // decodeFileDesc does decompression and unmarshalling on the given
 // file descriptor byte slice.
 func decodeFileDesc(enc []byte) (*dpb.FileDescriptorProto, error) {
 	raw, err := decompress(enc)
 	if err != nil {
 		return nil, fmt.Errorf("failed to decompress enc: %v", err)
 	}

 	fd := new(dpb.FileDescriptorProto)
 	if err := proto.Unmarshal(raw, fd); err != nil {
 		return nil, fmt.Errorf("bad descriptor: %v", err)
 	}
 	return fd, nil
 }

 // decompress does gzip decompression.
 func decompress(b []byte) ([]byte, error) {
 	r, err := gzip.NewReader(bytes.NewReader(b))
 	if err != nil {
 		return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
 	}
 	out, err := ioutil.ReadAll(r)
 	if err != nil {
 		return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
 	}
 	return out, nil
 }

 func typeForName(name string) (reflect.Type, error) {
 	pt := proto.MessageType(name)
 	if pt == nil {
 		return nil, fmt.Errorf("unknown type: %q", name)
 	}
 	st := pt.Elem()

 	return st, nil
 }

 func fileDescContainingExtension(st reflect.Type, ext int32) (*dpb.FileDescriptorProto, error) {
 	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(proto.Message)
 	if !ok {
 		return nil, fmt.Errorf("failed to create message from type: %v", st)
 	}

 	var extDesc *proto.ExtensionDesc
 	for id, desc := range proto.RegisteredExtensions(m) {
 		if id == ext {
 			extDesc = desc
 			break
 		}
 	}

 	if extDesc == nil {
 		return nil, fmt.Errorf("failed to find registered extension for extension number %v", ext)
 	}

 	return decodeFileDesc(proto.FileDescriptor(extDesc.Filename))
 }

 func (s *serverReflectionServer) allExtensionNumbersForType(st reflect.Type) ([]int32, error) {
 	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(proto.Message)
 	if !ok {
 		return nil, fmt.Errorf("failed to create message from type: %v", st)
 	}

 	exts := proto.RegisteredExtensions(m)
 	out := make([]int32, 0, len(exts))
 	for id := range exts {
 		out = append(out, id)
 	}
 	return out, nil
 }

 // fileDescEncodingByFilename finds the file descriptor for given filename,
 // does marshalling on it and returns the marshalled result.
 func (s *serverReflectionServer) fileDescEncodingByFilename(name string) ([]byte, error) {
 	enc := proto.FileDescriptor(name)
 	if enc == nil {
 		return nil, fmt.Errorf("unknown file: %v", name)
 	}
 	fd, err := decodeFileDesc(enc)
 	if err != nil {
 		return nil, err
 	}
 	return proto.Marshal(fd)
 }

 // parseMetadata finds the file descriptor bytes specified meta.
 // For SupportPackageIsVersion4, m is the name of the proto file, we
 // call proto.FileDescriptor to get the byte slice.
 // For SupportPackageIsVersion3, m is a byte slice itself.
 func parseMetadata(meta interface{}) ([]byte, bool) {
 	// Check if meta is the file name.
 	if fileNameForMeta, ok := meta.(string); ok {
 		return proto.FileDescriptor(fileNameForMeta), true
 	}

 	// Check if meta is the byte slice.
 	if enc, ok := meta.([]byte); ok {
 		return enc, true
 	}

 	return nil, false
 }

 // fileDescEncodingContainingSymbol finds the file descriptor containing the given symbol,
 // does marshalling on it and returns the marshalled result.
 // The given symbol can be a type, a service or a method.
 func (s *serverReflectionServer) fileDescEncodingContainingSymbol(name string) ([]byte, error) {
 	_, symbols := s.getSymbols()
 	fd := symbols[name]
 	if fd == nil {
 		// Check if it's a type name that was not present in the
 		// transitive dependencies of the registered services.
 		if st, err := typeForName(name); err == nil {
 			fd, err = s.fileDescForType(st)
 			if err != nil {
 				return nil, err
 			}
 		}
 	}

 	if fd == nil {
 		return nil, fmt.Errorf("unknown symbol: %v", name)
 	}

 	return proto.Marshal(fd)
 }

 // fileDescEncodingContainingExtension finds the file descriptor containing given extension,
 // does marshalling on it and returns the marshalled result.
 func (s *serverReflectionServer) fileDescEncodingContainingExtension(typeName string, extNum int32) ([]byte, error) {
 	st, err := typeForName(typeName)
 	if err != nil {
 		return nil, err
 	}
 	fd, err := fileDescContainingExtension(st, extNum)
 	if err != nil {
 		return nil, err
 	}
 	return proto.Marshal(fd)
 }

 // allExtensionNumbersForTypeName returns all extension numbers for the given type.
 func (s *serverReflectionServer) allExtensionNumbersForTypeName(name string) ([]int32, error) {
 	st, err := typeForName(name)
 	if err != nil {
 		return nil, err
 	}
 	extNums, err := s.allExtensionNumbersForType(st)
 	if err != nil {
 		return nil, err
 	}
 	return extNums, nil
 }

 // ServerReflectionInfo is the reflection service handler.
 func (s *serverReflectionServer) ServerReflectionInfo(stream rpb.ServerReflection_ServerReflectionInfoServer) error {
 	for {
 		in, err := stream.Recv()
 		if err == io.EOF {
 			return nil
 		}
 		if err != nil {
 			return err
 		}

 		out := &rpb.ServerReflectionResponse{
 			ValidHost:       in.Host,
 			OriginalRequest: in,
 		}
 		switch req := in.MessageRequest.(type) {
 		case *rpb.ServerReflectionRequest_FileByFilename:
 			b, err := s.fileDescEncodingByFilename(req.FileByFilename)
 			if err != nil {
 				out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
 					ErrorResponse: &rpb.ErrorResponse{
 						ErrorCode:    int32(codes.NotFound),
 						ErrorMessage: err.Error(),
 					},
 				}
 			} else {
 				out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
 					FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
 				}
 			}
 		case *rpb.ServerReflectionRequest_FileContainingSymbol:
 			b, err := s.fileDescEncodingContainingSymbol(req.FileContainingSymbol)
 			if err != nil {
 				out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
 					ErrorResponse: &rpb.ErrorResponse{
 						ErrorCode:    int32(codes.NotFound),
 						ErrorMessage: err.Error(),
 					},
 				}
 			} else {
 				out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
 					FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
 				}
 			}
 		case *rpb.ServerReflectionRequest_FileContainingExtension:
 			typeName := req.FileContainingExtension.ContainingType
 			extNum := req.FileContainingExtension.ExtensionNumber
 			b, err := s.fileDescEncodingContainingExtension(typeName, extNum)
 			if err != nil {
 				out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
 					ErrorResponse: &rpb.ErrorResponse{
 						ErrorCode:    int32(codes.NotFound),
 						ErrorMessage: err.Error(),
 					},
 				}
 			} else {
 				out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
 					FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
 				}
 			}
 		case *rpb.ServerReflectionRequest_AllExtensionNumbersOfType:
 			extNums, err := s.allExtensionNumbersForTypeName(req.AllExtensionNumbersOfType)
 			if err != nil {
 				out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
 					ErrorResponse: &rpb.ErrorResponse{
 						ErrorCode:    int32(codes.NotFound),
 						ErrorMessage: err.Error(),
 					},
 				}
 			} else {
 				out.MessageResponse = &rpb.ServerReflectionResponse_AllExtensionNumbersResponse{
 					AllExtensionNumbersResponse: &rpb.ExtensionNumberResponse{
 						BaseTypeName:    req.AllExtensionNumbersOfType,
 						ExtensionNumber: extNums,
 					},
 				}
 			}
 		case *rpb.ServerReflectionRequest_ListServices:
 			svcNames, _ := s.getSymbols()
 			serviceResponses := make([]*rpb.ServiceResponse, len(svcNames))
 			for i, n := range svcNames {
 				serviceResponses[i] = &rpb.ServiceResponse{
 					Name: n,
 				}
 			}
 			out.MessageResponse = &rpb.ServerReflectionResponse_ListServicesResponse{
 				ListServicesResponse: &rpb.ListServiceResponse{
 					Service: serviceResponses,
 				},
 			}
 		default:
 			return status.Errorf(codes.InvalidArgument, "invalid MessageRequest: %v", in.MessageRequest)
 		}

 		if err := stream.Send(out); err != nil {
 			return err
 		}
 	}
 }
	/*
	*
	* Copyright 2016 gRPC authors.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	*/

	//go:generate protoc --go_out=plugins=grpc:. grpc_reflection_v1alpha/reflection.proto

	/*
	Package reflection implements server reflection service.

	The service implemented is defined in:
	https://github.com/grpc/grpc/blob/master/src/proto/grpc/reflection/v1alpha/reflection.proto.

	To register server reflection on a gRPC server:
	import "google.golang.org/grpc/reflection"

	s := grpc.NewServer()
	pb.RegisterYourOwnServer(s, &server{})

	// Register reflection service on gRPC server.
	reflection.Register(s)

	s.Serve(lis)

	*/
	package reflection // import "google.golang.org/grpc/reflection"

	import (
	"bytes"
	"compress/gzip"
	"fmt"
	"io"
	"io/ioutil"
	"reflect"
	"sort"
	"sync"

	"github.com/golang/protobuf/proto"
	dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	rpb "google.golang.org/grpc/reflection/grpc_reflection_v1alpha"
	"google.golang.org/grpc/status"
	)

	type serverReflectionServer struct {
	s *grpc.Server

	initSymbols sync.Once
	serviceNames []string
	symbols map[string]*dpb.FileDescriptorProto // map of fully-qualified names to files
	}

	// Register registers the server reflection service on the given gRPC server.
	func Register(s *grpc.Server) {
	rpb.RegisterServerReflectionServer(s, &serverReflectionServer{
	s: s,
	})
	}

	// protoMessage is used for type assertion on proto messages.
	// Generated proto message implements function Descriptor(), but Descriptor()
	// is not part of interface proto.Message. This interface is needed to
	// call Descriptor().
	type protoMessage interface {
	Descriptor() ([]byte, []int)
	}

	func (s serverReflectionServer) getSymbols() (svcNames []string, symbolIndex map[string]dpb.FileDescriptorProto) {
	s.initSymbols.Do(func() {
	serviceInfo := s.s.GetServiceInfo()

	s.symbols = map[string]*dpb.FileDescriptorProto{}
	s.serviceNames = make([]string, 0, len(serviceInfo))
	processed := map[string]struct{}{}
	for svc, info := range serviceInfo {
	s.serviceNames = append(s.serviceNames, svc)
	fdenc, ok := parseMetadata(info.Metadata)
	if !ok {
	continue
	}
	fd, err := decodeFileDesc(fdenc)
	if err != nil {
	continue
	}
	s.processFile(fd, processed)
	}
	sort.Strings(s.serviceNames)
	})

	return s.serviceNames, s.symbols
	}

	func (s serverReflectionServer) processFile(fd dpb.FileDescriptorProto, processed map[string]struct{}) {
	filename := fd.GetName()
	if _, ok := processed[filename]; ok {
	return
	}
	processed[filename] = struct{}{}

	prefix := fd.GetPackage()

	for _, msg := range fd.MessageType {
	s.processMessage(fd, prefix, msg)
	}
	for _, en := range fd.EnumType {
	s.processEnum(fd, prefix, en)
	}
	for _, ext := range fd.Extension {
	s.processField(fd, prefix, ext)
	}
	for _, svc := range fd.Service {
	svcName := fqn(prefix, svc.GetName())
	s.symbols[svcName] = fd
	for _, meth := range svc.Method {
	name := fqn(svcName, meth.GetName())
	s.symbols[name] = fd
	}
	}

	for _, dep := range fd.Dependency {
	fdenc := proto.FileDescriptor(dep)
	fdDep, err := decodeFileDesc(fdenc)
	if err != nil {
	continue
	}
	s.processFile(fdDep, processed)
	}
	}

	func (s serverReflectionServer) processMessage(fd dpb.FileDescriptorProto, prefix string, msg *dpb.DescriptorProto) {
	msgName := fqn(prefix, msg.GetName())
	s.symbols[msgName] = fd

	for _, nested := range msg.NestedType {
	s.processMessage(fd, msgName, nested)
	}
	for _, en := range msg.EnumType {
	s.processEnum(fd, msgName, en)
	}
	for _, ext := range msg.Extension {
	s.processField(fd, msgName, ext)
	}
	for _, fld := range msg.Field {
	s.processField(fd, msgName, fld)
	}
	for _, oneof := range msg.OneofDecl {
	oneofName := fqn(msgName, oneof.GetName())
	s.symbols[oneofName] = fd
	}
	}

	func (s serverReflectionServer) processEnum(fd dpb.FileDescriptorProto, prefix string, en *dpb.EnumDescriptorProto) {
	enName := fqn(prefix, en.GetName())
	s.symbols[enName] = fd

	for _, val := range en.Value {
	valName := fqn(enName, val.GetName())
	s.symbols[valName] = fd
	}
	}

	func (s serverReflectionServer) processField(fd dpb.FileDescriptorProto, prefix string, fld *dpb.FieldDescriptorProto) {
	fldName := fqn(prefix, fld.GetName())
	s.symbols[fldName] = fd
	}

	func fqn(prefix, name string) string {
	if prefix == "" {
	return name
	}
	return prefix + "." + name
	}

	// fileDescForType gets the file descriptor for the given type.
	// The given type should be a proto message.
	func (s serverReflectionServer) fileDescForType(st reflect.Type) (dpb.FileDescriptorProto, error) {
	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(protoMessage)
	if !ok {
	return nil, fmt.Errorf("failed to create message from type: %v", st)
	}
	enc, _ := m.Descriptor()

	return decodeFileDesc(enc)
	}

	// decodeFileDesc does decompression and unmarshalling on the given
	// file descriptor byte slice.
	func decodeFileDesc(enc []byte) (*dpb.FileDescriptorProto, error) {
	raw, err := decompress(enc)
	if err != nil {
	return nil, fmt.Errorf("failed to decompress enc: %v", err)
	}

	fd := new(dpb.FileDescriptorProto)
	if err := proto.Unmarshal(raw, fd); err != nil {
	return nil, fmt.Errorf("bad descriptor: %v", err)
	}
	return fd, nil
	}

	// decompress does gzip decompression.
	func decompress(b []byte) ([]byte, error) {
	r, err := gzip.NewReader(bytes.NewReader(b))
	if err != nil {
	return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
	}
	out, err := ioutil.ReadAll(r)
	if err != nil {
	return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
	}
	return out, nil
	}

	func typeForName(name string) (reflect.Type, error) {
	pt := proto.MessageType(name)
	if pt == nil {
	return nil, fmt.Errorf("unknown type: %q", name)
	}
	st := pt.Elem()

	return st, nil
	}

	func fileDescContainingExtension(st reflect.Type, ext int32) (*dpb.FileDescriptorProto, error) {
	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(proto.Message)
	if !ok {
	return nil, fmt.Errorf("failed to create message from type: %v", st)
	}

	var extDesc *proto.ExtensionDesc
	for id, desc := range proto.RegisteredExtensions(m) {
	if id == ext {
	extDesc = desc
	break
	}
	}

	if extDesc == nil {
	return nil, fmt.Errorf("failed to find registered extension for extension number %v", ext)
	}

	return decodeFileDesc(proto.FileDescriptor(extDesc.Filename))
	}

	func (s *serverReflectionServer) allExtensionNumbersForType(st reflect.Type) ([]int32, error) {
	m, ok := reflect.Zero(reflect.PtrTo(st)).Interface().(proto.Message)
	if !ok {
	return nil, fmt.Errorf("failed to create message from type: %v", st)
	}

	exts := proto.RegisteredExtensions(m)
	out := make([]int32, 0, len(exts))
	for id := range exts {
	out = append(out, id)
	}
	return out, nil
	}

	// fileDescEncodingByFilename finds the file descriptor for given filename,
	// does marshalling on it and returns the marshalled result.
	func (s *serverReflectionServer) fileDescEncodingByFilename(name string) ([]byte, error) {
	enc := proto.FileDescriptor(name)
	if enc == nil {
	return nil, fmt.Errorf("unknown file: %v", name)
	}
	fd, err := decodeFileDesc(enc)
	if err != nil {
	return nil, err
	}
	return proto.Marshal(fd)
	}

	// parseMetadata finds the file descriptor bytes specified meta.
	// For SupportPackageIsVersion4, m is the name of the proto file, we
	// call proto.FileDescriptor to get the byte slice.
	// For SupportPackageIsVersion3, m is a byte slice itself.
	func parseMetadata(meta interface{}) ([]byte, bool) {
	// Check if meta is the file name.
	if fileNameForMeta, ok := meta.(string); ok {
	return proto.FileDescriptor(fileNameForMeta), true
	}

	// Check if meta is the byte slice.
	if enc, ok := meta.([]byte); ok {
	return enc, true
	}

	return nil, false
	}

	// fileDescEncodingContainingSymbol finds the file descriptor containing the given symbol,
	// does marshalling on it and returns the marshalled result.
	// The given symbol can be a type, a service or a method.
	func (s *serverReflectionServer) fileDescEncodingContainingSymbol(name string) ([]byte, error) {
	_, symbols := s.getSymbols()
	fd := symbols[name]
	if fd == nil {
	// Check if it's a type name that was not present in the
	// transitive dependencies of the registered services.
	if st, err := typeForName(name); err == nil {
	fd, err = s.fileDescForType(st)
	if err != nil {
	return nil, err
	}
	}
	}

	if fd == nil {
	return nil, fmt.Errorf("unknown symbol: %v", name)
	}

	return proto.Marshal(fd)
	}

	// fileDescEncodingContainingExtension finds the file descriptor containing given extension,
	// does marshalling on it and returns the marshalled result.
	func (s *serverReflectionServer) fileDescEncodingContainingExtension(typeName string, extNum int32) ([]byte, error) {
	st, err := typeForName(typeName)
	if err != nil {
	return nil, err
	}
	fd, err := fileDescContainingExtension(st, extNum)
	if err != nil {
	return nil, err
	}
	return proto.Marshal(fd)
	}

	// allExtensionNumbersForTypeName returns all extension numbers for the given type.
	func (s *serverReflectionServer) allExtensionNumbersForTypeName(name string) ([]int32, error) {
	st, err := typeForName(name)
	if err != nil {
	return nil, err
	}
	extNums, err := s.allExtensionNumbersForType(st)
	if err != nil {
	return nil, err
	}
	return extNums, nil
	}

	// ServerReflectionInfo is the reflection service handler.
	func (s *serverReflectionServer) ServerReflectionInfo(stream rpb.ServerReflection_ServerReflectionInfoServer) error {
	for {
	in, err := stream.Recv()
	if err == io.EOF {
	return nil
	}
	if err != nil {
	return err
	}

	out := &rpb.ServerReflectionResponse{
	ValidHost: in.Host,
	OriginalRequest: in,
	}
	switch req := in.MessageRequest.(type) {
	case *rpb.ServerReflectionRequest_FileByFilename:
	b, err := s.fileDescEncodingByFilename(req.FileByFilename)
	if err != nil {
	out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
	ErrorResponse: &rpb.ErrorResponse{
	ErrorCode: int32(codes.NotFound),
	ErrorMessage: err.Error(),
	},
	}
	} else {
	out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
	FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
	}
	}
	case *rpb.ServerReflectionRequest_FileContainingSymbol:
	b, err := s.fileDescEncodingContainingSymbol(req.FileContainingSymbol)
	if err != nil {
	out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
	ErrorResponse: &rpb.ErrorResponse{
	ErrorCode: int32(codes.NotFound),
	ErrorMessage: err.Error(),
	},
	}
	} else {
	out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
	FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
	}
	}
	case *rpb.ServerReflectionRequest_FileContainingExtension:
	typeName := req.FileContainingExtension.ContainingType
	extNum := req.FileContainingExtension.ExtensionNumber
	b, err := s.fileDescEncodingContainingExtension(typeName, extNum)
	if err != nil {
	out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
	ErrorResponse: &rpb.ErrorResponse{
	ErrorCode: int32(codes.NotFound),
	ErrorMessage: err.Error(),
	},
	}
	} else {
	out.MessageResponse = &rpb.ServerReflectionResponse_FileDescriptorResponse{
	FileDescriptorResponse: &rpb.FileDescriptorResponse{FileDescriptorProto: [][]byte{b}},
	}
	}
	case *rpb.ServerReflectionRequest_AllExtensionNumbersOfType:
	extNums, err := s.allExtensionNumbersForTypeName(req.AllExtensionNumbersOfType)
	if err != nil {
	out.MessageResponse = &rpb.ServerReflectionResponse_ErrorResponse{
	ErrorResponse: &rpb.ErrorResponse{
	ErrorCode: int32(codes.NotFound),
	ErrorMessage: err.Error(),
	},
	}
	} else {
	out.MessageResponse = &rpb.ServerReflectionResponse_AllExtensionNumbersResponse{
	AllExtensionNumbersResponse: &rpb.ExtensionNumberResponse{
	BaseTypeName: req.AllExtensionNumbersOfType,
	ExtensionNumber: extNums,
	},
	}
	}
	case *rpb.ServerReflectionRequest_ListServices:
	svcNames, _ := s.getSymbols()
	serviceResponses := make([]*rpb.ServiceResponse, len(svcNames))
	for i, n := range svcNames {
	serviceResponses[i] = &rpb.ServiceResponse{
	Name: n,
	}
	}
	out.MessageResponse = &rpb.ServerReflectionResponse_ListServicesResponse{
	ListServicesResponse: &rpb.ListServiceResponse{
	Service: serviceResponses,
	},
	}
	default:
	return status.Errorf(codes.InvalidArgument, "invalid MessageRequest: %v", in.MessageRequest)
	}

	if err := stream.Send(out); err != nil {
	return err
	}
	}
	}