diff --git a/vendor/google.golang.org/protobuf/internal/impl/message.go b/vendor/google.golang.org/protobuf/internal/impl/message.go
new file mode 100644
index 0000000..7dd994b
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/message.go
@@ -0,0 +1,215 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package impl
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"google.golang.org/protobuf/internal/genname"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// MessageInfo provides protobuf related functionality for a given Go type
+// that represents a message. A given instance of MessageInfo is tied to
+// exactly one Go type, which must be a pointer to a struct type.
+//
+// The exported fields must be populated before any methods are called
+// and cannot be mutated after set.
+type MessageInfo struct {
+	// GoReflectType is the underlying message Go type and must be populated.
+	GoReflectType reflect.Type // pointer to struct
+
+	// Desc is the underlying message descriptor type and must be populated.
+	Desc pref.MessageDescriptor
+
+	// Exporter must be provided in a purego environment in order to provide
+	// access to unexported fields.
+	Exporter exporter
+
+	// OneofWrappers is list of pointers to oneof wrapper struct types.
+	OneofWrappers []interface{}
+
+	initMu   sync.Mutex // protects all unexported fields
+	initDone uint32
+
+	reflectMessageInfo // for reflection implementation
+	coderMessageInfo   // for fast-path method implementations
+}
+
+// exporter is a function that returns a reference to the ith field of v,
+// where v is a pointer to a struct. It returns nil if it does not support
+// exporting the requested field (e.g., already exported).
+type exporter func(v interface{}, i int) interface{}
+
+// getMessageInfo returns the MessageInfo for any message type that
+// is generated by our implementation of protoc-gen-go (for v2 and on).
+// If it is unable to obtain a MessageInfo, it returns nil.
+func getMessageInfo(mt reflect.Type) *MessageInfo {
+	m, ok := reflect.Zero(mt).Interface().(pref.ProtoMessage)
+	if !ok {
+		return nil
+	}
+	mr, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *MessageInfo })
+	if !ok {
+		return nil
+	}
+	return mr.ProtoMessageInfo()
+}
+
+func (mi *MessageInfo) init() {
+	// This function is called in the hot path. Inline the sync.Once logic,
+	// since allocating a closure for Once.Do is expensive.
+	// Keep init small to ensure that it can be inlined.
+	if atomic.LoadUint32(&mi.initDone) == 0 {
+		mi.initOnce()
+	}
+}
+
+func (mi *MessageInfo) initOnce() {
+	mi.initMu.Lock()
+	defer mi.initMu.Unlock()
+	if mi.initDone == 1 {
+		return
+	}
+
+	t := mi.GoReflectType
+	if t.Kind() != reflect.Ptr && t.Elem().Kind() != reflect.Struct {
+		panic(fmt.Sprintf("got %v, want *struct kind", t))
+	}
+	t = t.Elem()
+
+	si := mi.makeStructInfo(t)
+	mi.makeReflectFuncs(t, si)
+	mi.makeCoderMethods(t, si)
+
+	atomic.StoreUint32(&mi.initDone, 1)
+}
+
+// getPointer returns the pointer for a message, which should be of
+// the type of the MessageInfo. If the message is of a different type,
+// it returns ok==false.
+func (mi *MessageInfo) getPointer(m pref.Message) (p pointer, ok bool) {
+	switch m := m.(type) {
+	case *messageState:
+		return m.pointer(), m.messageInfo() == mi
+	case *messageReflectWrapper:
+		return m.pointer(), m.messageInfo() == mi
+	}
+	return pointer{}, false
+}
+
+type (
+	SizeCache       = int32
+	WeakFields      = map[int32]protoreflect.ProtoMessage
+	UnknownFields   = []byte
+	ExtensionFields = map[int32]ExtensionField
+)
+
+var (
+	sizecacheType       = reflect.TypeOf(SizeCache(0))
+	weakFieldsType      = reflect.TypeOf(WeakFields(nil))
+	unknownFieldsType   = reflect.TypeOf(UnknownFields(nil))
+	extensionFieldsType = reflect.TypeOf(ExtensionFields(nil))
+)
+
+type structInfo struct {
+	sizecacheOffset offset
+	weakOffset      offset
+	unknownOffset   offset
+	extensionOffset offset
+
+	fieldsByNumber        map[pref.FieldNumber]reflect.StructField
+	oneofsByName          map[pref.Name]reflect.StructField
+	oneofWrappersByType   map[reflect.Type]pref.FieldNumber
+	oneofWrappersByNumber map[pref.FieldNumber]reflect.Type
+}
+
+func (mi *MessageInfo) makeStructInfo(t reflect.Type) structInfo {
+	si := structInfo{
+		sizecacheOffset: invalidOffset,
+		weakOffset:      invalidOffset,
+		unknownOffset:   invalidOffset,
+		extensionOffset: invalidOffset,
+
+		fieldsByNumber:        map[pref.FieldNumber]reflect.StructField{},
+		oneofsByName:          map[pref.Name]reflect.StructField{},
+		oneofWrappersByType:   map[reflect.Type]pref.FieldNumber{},
+		oneofWrappersByNumber: map[pref.FieldNumber]reflect.Type{},
+	}
+
+fieldLoop:
+	for i := 0; i < t.NumField(); i++ {
+		switch f := t.Field(i); f.Name {
+		case genname.SizeCache, genname.SizeCacheA:
+			if f.Type == sizecacheType {
+				si.sizecacheOffset = offsetOf(f, mi.Exporter)
+			}
+		case genname.WeakFields, genname.WeakFieldsA:
+			if f.Type == weakFieldsType {
+				si.weakOffset = offsetOf(f, mi.Exporter)
+			}
+		case genname.UnknownFields, genname.UnknownFieldsA:
+			if f.Type == unknownFieldsType {
+				si.unknownOffset = offsetOf(f, mi.Exporter)
+			}
+		case genname.ExtensionFields, genname.ExtensionFieldsA, genname.ExtensionFieldsB:
+			if f.Type == extensionFieldsType {
+				si.extensionOffset = offsetOf(f, mi.Exporter)
+			}
+		default:
+			for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
+				if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
+					n, _ := strconv.ParseUint(s, 10, 64)
+					si.fieldsByNumber[pref.FieldNumber(n)] = f
+					continue fieldLoop
+				}
+			}
+			if s := f.Tag.Get("protobuf_oneof"); len(s) > 0 {
+				si.oneofsByName[pref.Name(s)] = f
+				continue fieldLoop
+			}
+		}
+	}
+
+	// Derive a mapping of oneof wrappers to fields.
+	oneofWrappers := mi.OneofWrappers
+	for _, method := range []string{"XXX_OneofFuncs", "XXX_OneofWrappers"} {
+		if fn, ok := reflect.PtrTo(t).MethodByName(method); ok {
+			for _, v := range fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))}) {
+				if vs, ok := v.Interface().([]interface{}); ok {
+					oneofWrappers = vs
+				}
+			}
+		}
+	}
+	for _, v := range oneofWrappers {
+		tf := reflect.TypeOf(v).Elem()
+		f := tf.Field(0)
+		for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
+			if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
+				n, _ := strconv.ParseUint(s, 10, 64)
+				si.oneofWrappersByType[tf] = pref.FieldNumber(n)
+				si.oneofWrappersByNumber[pref.FieldNumber(n)] = tf
+				break
+			}
+		}
+	}
+
+	return si
+}
+
+func (mi *MessageInfo) New() protoreflect.Message {
+	return mi.MessageOf(reflect.New(mi.GoReflectType.Elem()).Interface())
+}
+func (mi *MessageInfo) Zero() protoreflect.Message {
+	return mi.MessageOf(reflect.Zero(mi.GoReflectType).Interface())
+}
+func (mi *MessageInfo) Descriptor() protoreflect.MessageDescriptor { return mi.Desc }