diff --git a/vendor/github.com/golang/protobuf/proto/extensions.go b/vendor/github.com/golang/protobuf/proto/extensions.go
index 42fc120..fa88add 100644
--- a/vendor/github.com/golang/protobuf/proto/extensions.go
+++ b/vendor/github.com/golang/protobuf/proto/extensions.go
@@ -1,356 +1,607 @@
-// Copyright 2010 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.
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2010 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 package proto
 
+/*
+ * Types and routines for supporting protocol buffer extensions.
+ */
+
 import (
 	"errors"
 	"fmt"
+	"io"
 	"reflect"
-
-	"google.golang.org/protobuf/encoding/protowire"
-	"google.golang.org/protobuf/proto"
-	"google.golang.org/protobuf/reflect/protoreflect"
-	"google.golang.org/protobuf/reflect/protoregistry"
-	"google.golang.org/protobuf/runtime/protoiface"
-	"google.golang.org/protobuf/runtime/protoimpl"
+	"strconv"
+	"sync"
 )
 
-type (
-	// ExtensionDesc represents an extension descriptor and
-	// is used to interact with an extension field in a message.
-	//
-	// Variables of this type are generated in code by protoc-gen-go.
-	ExtensionDesc = protoimpl.ExtensionInfo
-
-	// ExtensionRange represents a range of message extensions.
-	// Used in code generated by protoc-gen-go.
-	ExtensionRange = protoiface.ExtensionRangeV1
-
-	// Deprecated: Do not use; this is an internal type.
-	Extension = protoimpl.ExtensionFieldV1
-
-	// Deprecated: Do not use; this is an internal type.
-	XXX_InternalExtensions = protoimpl.ExtensionFields
-)
-
-// ErrMissingExtension reports whether the extension was not present.
+// ErrMissingExtension is the error returned by GetExtension if the named extension is not in the message.
 var ErrMissingExtension = errors.New("proto: missing extension")
 
+// ExtensionRange represents a range of message extensions for a protocol buffer.
+// Used in code generated by the protocol compiler.
+type ExtensionRange struct {
+	Start, End int32 // both inclusive
+}
+
+// extendableProto is an interface implemented by any protocol buffer generated by the current
+// proto compiler that may be extended.
+type extendableProto interface {
+	Message
+	ExtensionRangeArray() []ExtensionRange
+	extensionsWrite() map[int32]Extension
+	extensionsRead() (map[int32]Extension, sync.Locker)
+}
+
+// extendableProtoV1 is an interface implemented by a protocol buffer generated by the previous
+// version of the proto compiler that may be extended.
+type extendableProtoV1 interface {
+	Message
+	ExtensionRangeArray() []ExtensionRange
+	ExtensionMap() map[int32]Extension
+}
+
+// extensionAdapter is a wrapper around extendableProtoV1 that implements extendableProto.
+type extensionAdapter struct {
+	extendableProtoV1
+}
+
+func (e extensionAdapter) extensionsWrite() map[int32]Extension {
+	return e.ExtensionMap()
+}
+
+func (e extensionAdapter) extensionsRead() (map[int32]Extension, sync.Locker) {
+	return e.ExtensionMap(), notLocker{}
+}
+
+// notLocker is a sync.Locker whose Lock and Unlock methods are nops.
+type notLocker struct{}
+
+func (n notLocker) Lock()   {}
+func (n notLocker) Unlock() {}
+
+// extendable returns the extendableProto interface for the given generated proto message.
+// If the proto message has the old extension format, it returns a wrapper that implements
+// the extendableProto interface.
+func extendable(p interface{}) (extendableProto, error) {
+	switch p := p.(type) {
+	case extendableProto:
+		if isNilPtr(p) {
+			return nil, fmt.Errorf("proto: nil %T is not extendable", p)
+		}
+		return p, nil
+	case extendableProtoV1:
+		if isNilPtr(p) {
+			return nil, fmt.Errorf("proto: nil %T is not extendable", p)
+		}
+		return extensionAdapter{p}, nil
+	}
+	// Don't allocate a specific error containing %T:
+	// this is the hot path for Clone and MarshalText.
+	return nil, errNotExtendable
+}
+
 var errNotExtendable = errors.New("proto: not an extendable proto.Message")
 
-// HasExtension reports whether the extension field is present in m
-// either as an explicitly populated field or as an unknown field.
-func HasExtension(m Message, xt *ExtensionDesc) (has bool) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() {
+func isNilPtr(x interface{}) bool {
+	v := reflect.ValueOf(x)
+	return v.Kind() == reflect.Ptr && v.IsNil()
+}
+
+// XXX_InternalExtensions is an internal representation of proto extensions.
+//
+// Each generated message struct type embeds an anonymous XXX_InternalExtensions field,
+// thus gaining the unexported 'extensions' method, which can be called only from the proto package.
+//
+// The methods of XXX_InternalExtensions are not concurrency safe in general,
+// but calls to logically read-only methods such as has and get may be executed concurrently.
+type XXX_InternalExtensions struct {
+	// The struct must be indirect so that if a user inadvertently copies a
+	// generated message and its embedded XXX_InternalExtensions, they
+	// avoid the mayhem of a copied mutex.
+	//
+	// The mutex serializes all logically read-only operations to p.extensionMap.
+	// It is up to the client to ensure that write operations to p.extensionMap are
+	// mutually exclusive with other accesses.
+	p *struct {
+		mu           sync.Mutex
+		extensionMap map[int32]Extension
+	}
+}
+
+// extensionsWrite returns the extension map, creating it on first use.
+func (e *XXX_InternalExtensions) extensionsWrite() map[int32]Extension {
+	if e.p == nil {
+		e.p = new(struct {
+			mu           sync.Mutex
+			extensionMap map[int32]Extension
+		})
+		e.p.extensionMap = make(map[int32]Extension)
+	}
+	return e.p.extensionMap
+}
+
+// extensionsRead returns the extensions map for read-only use.  It may be nil.
+// The caller must hold the returned mutex's lock when accessing Elements within the map.
+func (e *XXX_InternalExtensions) extensionsRead() (map[int32]Extension, sync.Locker) {
+	if e.p == nil {
+		return nil, nil
+	}
+	return e.p.extensionMap, &e.p.mu
+}
+
+// ExtensionDesc represents an extension specification.
+// Used in generated code from the protocol compiler.
+type ExtensionDesc struct {
+	ExtendedType  Message     // nil pointer to the type that is being extended
+	ExtensionType interface{} // nil pointer to the extension type
+	Field         int32       // field number
+	Name          string      // fully-qualified name of extension, for text formatting
+	Tag           string      // protobuf tag style
+	Filename      string      // name of the file in which the extension is defined
+}
+
+func (ed *ExtensionDesc) repeated() bool {
+	t := reflect.TypeOf(ed.ExtensionType)
+	return t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
+}
+
+// Extension represents an extension in a message.
+type Extension struct {
+	// When an extension is stored in a message using SetExtension
+	// only desc and value are set. When the message is marshaled
+	// enc will be set to the encoded form of the message.
+	//
+	// When a message is unmarshaled and contains extensions, each
+	// extension will have only enc set. When such an extension is
+	// accessed using GetExtension (or GetExtensions) desc and value
+	// will be set.
+	desc *ExtensionDesc
+
+	// value is a concrete value for the extension field. Let the type of
+	// desc.ExtensionType be the "API type" and the type of Extension.value
+	// be the "storage type". The API type and storage type are the same except:
+	//	* For scalars (except []byte), the API type uses *T,
+	//	while the storage type uses T.
+	//	* For repeated fields, the API type uses []T, while the storage type
+	//	uses *[]T.
+	//
+	// The reason for the divergence is so that the storage type more naturally
+	// matches what is expected of when retrieving the values through the
+	// protobuf reflection APIs.
+	//
+	// The value may only be populated if desc is also populated.
+	value interface{}
+
+	// enc is the raw bytes for the extension field.
+	enc []byte
+}
+
+// SetRawExtension is for testing only.
+func SetRawExtension(base Message, id int32, b []byte) {
+	epb, err := extendable(base)
+	if err != nil {
+		return
+	}
+	extmap := epb.extensionsWrite()
+	extmap[id] = Extension{enc: b}
+}
+
+// isExtensionField returns true iff the given field number is in an extension range.
+func isExtensionField(pb extendableProto, field int32) bool {
+	for _, er := range pb.ExtensionRangeArray() {
+		if er.Start <= field && field <= er.End {
+			return true
+		}
+	}
+	return false
+}
+
+// checkExtensionTypes checks that the given extension is valid for pb.
+func checkExtensionTypes(pb extendableProto, extension *ExtensionDesc) error {
+	var pbi interface{} = pb
+	// Check the extended type.
+	if ea, ok := pbi.(extensionAdapter); ok {
+		pbi = ea.extendableProtoV1
+	}
+	if a, b := reflect.TypeOf(pbi), reflect.TypeOf(extension.ExtendedType); a != b {
+		return fmt.Errorf("proto: bad extended type; %v does not extend %v", b, a)
+	}
+	// Check the range.
+	if !isExtensionField(pb, extension.Field) {
+		return errors.New("proto: bad extension number; not in declared ranges")
+	}
+	return nil
+}
+
+// extPropKey is sufficient to uniquely identify an extension.
+type extPropKey struct {
+	base  reflect.Type
+	field int32
+}
+
+var extProp = struct {
+	sync.RWMutex
+	m map[extPropKey]*Properties
+}{
+	m: make(map[extPropKey]*Properties),
+}
+
+func extensionProperties(ed *ExtensionDesc) *Properties {
+	key := extPropKey{base: reflect.TypeOf(ed.ExtendedType), field: ed.Field}
+
+	extProp.RLock()
+	if prop, ok := extProp.m[key]; ok {
+		extProp.RUnlock()
+		return prop
+	}
+	extProp.RUnlock()
+
+	extProp.Lock()
+	defer extProp.Unlock()
+	// Check again.
+	if prop, ok := extProp.m[key]; ok {
+		return prop
+	}
+
+	prop := new(Properties)
+	prop.Init(reflect.TypeOf(ed.ExtensionType), "unknown_name", ed.Tag, nil)
+	extProp.m[key] = prop
+	return prop
+}
+
+// HasExtension returns whether the given extension is present in pb.
+func HasExtension(pb Message, extension *ExtensionDesc) bool {
+	// TODO: Check types, field numbers, etc.?
+	epb, err := extendable(pb)
+	if err != nil {
 		return false
 	}
-
-	// Check whether any populated known field matches the field number.
-	xtd := xt.TypeDescriptor()
-	if isValidExtension(mr.Descriptor(), xtd) {
-		has = mr.Has(xtd)
-	} else {
-		mr.Range(func(fd protoreflect.FieldDescriptor, _ protoreflect.Value) bool {
-			has = int32(fd.Number()) == xt.Field
-			return !has
-		})
+	extmap, mu := epb.extensionsRead()
+	if extmap == nil {
+		return false
 	}
-
-	// Check whether any unknown field matches the field number.
-	for b := mr.GetUnknown(); !has && len(b) > 0; {
-		num, _, n := protowire.ConsumeField(b)
-		has = int32(num) == xt.Field
-		b = b[n:]
-	}
-	return has
+	mu.Lock()
+	_, ok := extmap[extension.Field]
+	mu.Unlock()
+	return ok
 }
 
-// ClearExtension removes the extension field from m
-// either as an explicitly populated field or as an unknown field.
-func ClearExtension(m Message, xt *ExtensionDesc) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() {
+// ClearExtension removes the given extension from pb.
+func ClearExtension(pb Message, extension *ExtensionDesc) {
+	epb, err := extendable(pb)
+	if err != nil {
 		return
 	}
-
-	xtd := xt.TypeDescriptor()
-	if isValidExtension(mr.Descriptor(), xtd) {
-		mr.Clear(xtd)
-	} else {
-		mr.Range(func(fd protoreflect.FieldDescriptor, _ protoreflect.Value) bool {
-			if int32(fd.Number()) == xt.Field {
-				mr.Clear(fd)
-				return false
-			}
-			return true
-		})
-	}
-	clearUnknown(mr, fieldNum(xt.Field))
+	// TODO: Check types, field numbers, etc.?
+	extmap := epb.extensionsWrite()
+	delete(extmap, extension.Field)
 }
 
-// ClearAllExtensions clears all extensions from m.
-// This includes populated fields and unknown fields in the extension range.
-func ClearAllExtensions(m Message) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() {
-		return
-	}
-
-	mr.Range(func(fd protoreflect.FieldDescriptor, _ protoreflect.Value) bool {
-		if fd.IsExtension() {
-			mr.Clear(fd)
-		}
-		return true
-	})
-	clearUnknown(mr, mr.Descriptor().ExtensionRanges())
-}
-
-// GetExtension retrieves a proto2 extended field from m.
+// GetExtension retrieves a proto2 extended field from pb.
 //
 // If the descriptor is type complete (i.e., ExtensionDesc.ExtensionType is non-nil),
 // then GetExtension parses the encoded field and returns a Go value of the specified type.
 // If the field is not present, then the default value is returned (if one is specified),
 // otherwise ErrMissingExtension is reported.
 //
-// If the descriptor is type incomplete (i.e., ExtensionDesc.ExtensionType is nil),
-// then GetExtension returns the raw encoded bytes for the extension field.
-func GetExtension(m Message, xt *ExtensionDesc) (interface{}, error) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() || mr.Descriptor().ExtensionRanges().Len() == 0 {
-		return nil, errNotExtendable
+// If the descriptor is not type complete (i.e., ExtensionDesc.ExtensionType is nil),
+// then GetExtension returns the raw encoded bytes of the field extension.
+func GetExtension(pb Message, extension *ExtensionDesc) (interface{}, error) {
+	epb, err := extendable(pb)
+	if err != nil {
+		return nil, err
 	}
 
-	// Retrieve the unknown fields for this extension field.
-	var bo protoreflect.RawFields
-	for bi := mr.GetUnknown(); len(bi) > 0; {
-		num, _, n := protowire.ConsumeField(bi)
-		if int32(num) == xt.Field {
-			bo = append(bo, bi[:n]...)
-		}
-		bi = bi[n:]
-	}
-
-	// For type incomplete descriptors, only retrieve the unknown fields.
-	if xt.ExtensionType == nil {
-		return []byte(bo), nil
-	}
-
-	// If the extension field only exists as unknown fields, unmarshal it.
-	// This is rarely done since proto.Unmarshal eagerly unmarshals extensions.
-	xtd := xt.TypeDescriptor()
-	if !isValidExtension(mr.Descriptor(), xtd) {
-		return nil, fmt.Errorf("proto: bad extended type; %T does not extend %T", xt.ExtendedType, m)
-	}
-	if !mr.Has(xtd) && len(bo) > 0 {
-		m2 := mr.New()
-		if err := (proto.UnmarshalOptions{
-			Resolver: extensionResolver{xt},
-		}.Unmarshal(bo, m2.Interface())); err != nil {
+	if extension.ExtendedType != nil {
+		// can only check type if this is a complete descriptor
+		if err := checkExtensionTypes(epb, extension); err != nil {
 			return nil, err
 		}
-		if m2.Has(xtd) {
-			mr.Set(xtd, m2.Get(xtd))
-			clearUnknown(mr, fieldNum(xt.Field))
-		}
 	}
 
-	// Check whether the message has the extension field set or a default.
-	var pv protoreflect.Value
-	switch {
-	case mr.Has(xtd):
-		pv = mr.Get(xtd)
-	case xtd.HasDefault():
-		pv = xtd.Default()
-	default:
+	emap, mu := epb.extensionsRead()
+	if emap == nil {
+		return defaultExtensionValue(extension)
+	}
+	mu.Lock()
+	defer mu.Unlock()
+	e, ok := emap[extension.Field]
+	if !ok {
+		// defaultExtensionValue returns the default value or
+		// ErrMissingExtension if there is no default.
+		return defaultExtensionValue(extension)
+	}
+
+	if e.value != nil {
+		// Already decoded. Check the descriptor, though.
+		if e.desc != extension {
+			// This shouldn't happen. If it does, it means that
+			// GetExtension was called twice with two different
+			// descriptors with the same field number.
+			return nil, errors.New("proto: descriptor conflict")
+		}
+		return extensionAsLegacyType(e.value), nil
+	}
+
+	if extension.ExtensionType == nil {
+		// incomplete descriptor
+		return e.enc, nil
+	}
+
+	v, err := decodeExtension(e.enc, extension)
+	if err != nil {
+		return nil, err
+	}
+
+	// Remember the decoded version and drop the encoded version.
+	// That way it is safe to mutate what we return.
+	e.value = extensionAsStorageType(v)
+	e.desc = extension
+	e.enc = nil
+	emap[extension.Field] = e
+	return extensionAsLegacyType(e.value), nil
+}
+
+// defaultExtensionValue returns the default value for extension.
+// If no default for an extension is defined ErrMissingExtension is returned.
+func defaultExtensionValue(extension *ExtensionDesc) (interface{}, error) {
+	if extension.ExtensionType == nil {
+		// incomplete descriptor, so no default
 		return nil, ErrMissingExtension
 	}
 
-	v := xt.InterfaceOf(pv)
-	rv := reflect.ValueOf(v)
-	if isScalarKind(rv.Kind()) {
-		rv2 := reflect.New(rv.Type())
-		rv2.Elem().Set(rv)
-		v = rv2.Interface()
+	t := reflect.TypeOf(extension.ExtensionType)
+	props := extensionProperties(extension)
+
+	sf, _, err := fieldDefault(t, props)
+	if err != nil {
+		return nil, err
 	}
-	return v, nil
+
+	if sf == nil || sf.value == nil {
+		// There is no default value.
+		return nil, ErrMissingExtension
+	}
+
+	if t.Kind() != reflect.Ptr {
+		// We do not need to return a Ptr, we can directly return sf.value.
+		return sf.value, nil
+	}
+
+	// We need to return an interface{} that is a pointer to sf.value.
+	value := reflect.New(t).Elem()
+	value.Set(reflect.New(value.Type().Elem()))
+	if sf.kind == reflect.Int32 {
+		// We may have an int32 or an enum, but the underlying data is int32.
+		// Since we can't set an int32 into a non int32 reflect.value directly
+		// set it as a int32.
+		value.Elem().SetInt(int64(sf.value.(int32)))
+	} else {
+		value.Elem().Set(reflect.ValueOf(sf.value))
+	}
+	return value.Interface(), nil
 }
 
-// extensionResolver is a custom extension resolver that stores a single
-// extension type that takes precedence over the global registry.
-type extensionResolver struct{ xt protoreflect.ExtensionType }
+// decodeExtension decodes an extension encoded in b.
+func decodeExtension(b []byte, extension *ExtensionDesc) (interface{}, error) {
+	t := reflect.TypeOf(extension.ExtensionType)
+	unmarshal := typeUnmarshaler(t, extension.Tag)
 
-func (r extensionResolver) FindExtensionByName(field protoreflect.FullName) (protoreflect.ExtensionType, error) {
-	if xtd := r.xt.TypeDescriptor(); xtd.FullName() == field {
-		return r.xt, nil
-	}
-	return protoregistry.GlobalTypes.FindExtensionByName(field)
-}
+	// t is a pointer to a struct, pointer to basic type or a slice.
+	// Allocate space to store the pointer/slice.
+	value := reflect.New(t).Elem()
 
-func (r extensionResolver) FindExtensionByNumber(message protoreflect.FullName, field protoreflect.FieldNumber) (protoreflect.ExtensionType, error) {
-	if xtd := r.xt.TypeDescriptor(); xtd.ContainingMessage().FullName() == message && xtd.Number() == field {
-		return r.xt, nil
-	}
-	return protoregistry.GlobalTypes.FindExtensionByNumber(message, field)
-}
+	var err error
+	for {
+		x, n := decodeVarint(b)
+		if n == 0 {
+			return nil, io.ErrUnexpectedEOF
+		}
+		b = b[n:]
+		wire := int(x) & 7
 
-// GetExtensions returns a list of the extensions values present in m,
-// corresponding with the provided list of extension descriptors, xts.
-// If an extension is missing in m, the corresponding value is nil.
-func GetExtensions(m Message, xts []*ExtensionDesc) ([]interface{}, error) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() {
-		return nil, errNotExtendable
-	}
-
-	vs := make([]interface{}, len(xts))
-	for i, xt := range xts {
-		v, err := GetExtension(m, xt)
+		b, err = unmarshal(b, valToPointer(value.Addr()), wire)
 		if err != nil {
-			if err == ErrMissingExtension {
-				continue
-			}
-			return vs, err
+			return nil, err
 		}
-		vs[i] = v
+
+		if len(b) == 0 {
+			break
+		}
 	}
-	return vs, nil
+	return value.Interface(), nil
 }
 
-// SetExtension sets an extension field in m to the provided value.
-func SetExtension(m Message, xt *ExtensionDesc, v interface{}) error {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() || mr.Descriptor().ExtensionRanges().Len() == 0 {
-		return errNotExtendable
+// GetExtensions returns a slice of the extensions present in pb that are also listed in es.
+// The returned slice has the same length as es; missing extensions will appear as nil elements.
+func GetExtensions(pb Message, es []*ExtensionDesc) (extensions []interface{}, err error) {
+	epb, err := extendable(pb)
+	if err != nil {
+		return nil, err
 	}
-
-	rv := reflect.ValueOf(v)
-	if reflect.TypeOf(v) != reflect.TypeOf(xt.ExtensionType) {
-		return fmt.Errorf("proto: bad extension value type. got: %T, want: %T", v, xt.ExtensionType)
-	}
-	if rv.Kind() == reflect.Ptr {
-		if rv.IsNil() {
-			return fmt.Errorf("proto: SetExtension called with nil value of type %T", v)
+	extensions = make([]interface{}, len(es))
+	for i, e := range es {
+		extensions[i], err = GetExtension(epb, e)
+		if err == ErrMissingExtension {
+			err = nil
 		}
-		if isScalarKind(rv.Elem().Kind()) {
-			v = rv.Elem().Interface()
+		if err != nil {
+			return
 		}
 	}
+	return
+}
 
-	xtd := xt.TypeDescriptor()
-	if !isValidExtension(mr.Descriptor(), xtd) {
-		return fmt.Errorf("proto: bad extended type; %T does not extend %T", xt.ExtendedType, m)
+// ExtensionDescs returns a new slice containing pb's extension descriptors, in undefined order.
+// For non-registered extensions, ExtensionDescs returns an incomplete descriptor containing
+// just the Field field, which defines the extension's field number.
+func ExtensionDescs(pb Message) ([]*ExtensionDesc, error) {
+	epb, err := extendable(pb)
+	if err != nil {
+		return nil, err
 	}
-	mr.Set(xtd, xt.ValueOf(v))
-	clearUnknown(mr, fieldNum(xt.Field))
+	registeredExtensions := RegisteredExtensions(pb)
+
+	emap, mu := epb.extensionsRead()
+	if emap == nil {
+		return nil, nil
+	}
+	mu.Lock()
+	defer mu.Unlock()
+	extensions := make([]*ExtensionDesc, 0, len(emap))
+	for extid, e := range emap {
+		desc := e.desc
+		if desc == nil {
+			desc = registeredExtensions[extid]
+			if desc == nil {
+				desc = &ExtensionDesc{Field: extid}
+			}
+		}
+
+		extensions = append(extensions, desc)
+	}
+	return extensions, nil
+}
+
+// SetExtension sets the specified extension of pb to the specified value.
+func SetExtension(pb Message, extension *ExtensionDesc, value interface{}) error {
+	epb, err := extendable(pb)
+	if err != nil {
+		return err
+	}
+	if err := checkExtensionTypes(epb, extension); err != nil {
+		return err
+	}
+	typ := reflect.TypeOf(extension.ExtensionType)
+	if typ != reflect.TypeOf(value) {
+		return fmt.Errorf("proto: bad extension value type. got: %T, want: %T", value, extension.ExtensionType)
+	}
+	// nil extension values need to be caught early, because the
+	// encoder can't distinguish an ErrNil due to a nil extension
+	// from an ErrNil due to a missing field. Extensions are
+	// always optional, so the encoder would just swallow the error
+	// and drop all the extensions from the encoded message.
+	if reflect.ValueOf(value).IsNil() {
+		return fmt.Errorf("proto: SetExtension called with nil value of type %T", value)
+	}
+
+	extmap := epb.extensionsWrite()
+	extmap[extension.Field] = Extension{desc: extension, value: extensionAsStorageType(value)}
 	return nil
 }
 
-// SetRawExtension inserts b into the unknown fields of m.
-//
-// Deprecated: Use Message.ProtoReflect.SetUnknown instead.
-func SetRawExtension(m Message, fnum int32, b []byte) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() {
+// ClearAllExtensions clears all extensions from pb.
+func ClearAllExtensions(pb Message) {
+	epb, err := extendable(pb)
+	if err != nil {
 		return
 	}
-
-	// Verify that the raw field is valid.
-	for b0 := b; len(b0) > 0; {
-		num, _, n := protowire.ConsumeField(b0)
-		if int32(num) != fnum {
-			panic(fmt.Sprintf("mismatching field number: got %d, want %d", num, fnum))
-		}
-		b0 = b0[n:]
+	m := epb.extensionsWrite()
+	for k := range m {
+		delete(m, k)
 	}
-
-	ClearExtension(m, &ExtensionDesc{Field: fnum})
-	mr.SetUnknown(append(mr.GetUnknown(), b...))
 }
 
-// ExtensionDescs returns a list of extension descriptors found in m,
-// containing descriptors for both populated extension fields in m and
-// also unknown fields of m that are in the extension range.
-// For the later case, an type incomplete descriptor is provided where only
-// the ExtensionDesc.Field field is populated.
-// The order of the extension descriptors is undefined.
-func ExtensionDescs(m Message) ([]*ExtensionDesc, error) {
-	mr := MessageReflect(m)
-	if mr == nil || !mr.IsValid() || mr.Descriptor().ExtensionRanges().Len() == 0 {
-		return nil, errNotExtendable
-	}
+// A global registry of extensions.
+// The generated code will register the generated descriptors by calling RegisterExtension.
 
-	// Collect a set of known extension descriptors.
-	extDescs := make(map[protoreflect.FieldNumber]*ExtensionDesc)
-	mr.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
-		if fd.IsExtension() {
-			xt := fd.(protoreflect.ExtensionTypeDescriptor)
-			if xd, ok := xt.Type().(*ExtensionDesc); ok {
-				extDescs[fd.Number()] = xd
+var extensionMaps = make(map[reflect.Type]map[int32]*ExtensionDesc)
+
+// RegisterExtension is called from the generated code.
+func RegisterExtension(desc *ExtensionDesc) {
+	st := reflect.TypeOf(desc.ExtendedType).Elem()
+	m := extensionMaps[st]
+	if m == nil {
+		m = make(map[int32]*ExtensionDesc)
+		extensionMaps[st] = m
+	}
+	if _, ok := m[desc.Field]; ok {
+		panic("proto: duplicate extension registered: " + st.String() + " " + strconv.Itoa(int(desc.Field)))
+	}
+	m[desc.Field] = desc
+}
+
+// RegisteredExtensions returns a map of the registered extensions of a
+// protocol buffer struct, indexed by the extension number.
+// The argument pb should be a nil pointer to the struct type.
+func RegisteredExtensions(pb Message) map[int32]*ExtensionDesc {
+	return extensionMaps[reflect.TypeOf(pb).Elem()]
+}
+
+// extensionAsLegacyType converts an value in the storage type as the API type.
+// See Extension.value.
+func extensionAsLegacyType(v interface{}) interface{} {
+	switch rv := reflect.ValueOf(v); rv.Kind() {
+	case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
+		// Represent primitive types as a pointer to the value.
+		rv2 := reflect.New(rv.Type())
+		rv2.Elem().Set(rv)
+		v = rv2.Interface()
+	case reflect.Ptr:
+		// Represent slice types as the value itself.
+		switch rv.Type().Elem().Kind() {
+		case reflect.Slice:
+			if rv.IsNil() {
+				v = reflect.Zero(rv.Type().Elem()).Interface()
+			} else {
+				v = rv.Elem().Interface()
 			}
 		}
-		return true
-	})
+	}
+	return v
+}
 
-	// Collect a set of unknown extension descriptors.
-	extRanges := mr.Descriptor().ExtensionRanges()
-	for b := mr.GetUnknown(); len(b) > 0; {
-		num, _, n := protowire.ConsumeField(b)
-		if extRanges.Has(num) && extDescs[num] == nil {
-			extDescs[num] = nil
+// extensionAsStorageType converts an value in the API type as the storage type.
+// See Extension.value.
+func extensionAsStorageType(v interface{}) interface{} {
+	switch rv := reflect.ValueOf(v); rv.Kind() {
+	case reflect.Ptr:
+		// Represent slice types as the value itself.
+		switch rv.Type().Elem().Kind() {
+		case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
+			if rv.IsNil() {
+				v = reflect.Zero(rv.Type().Elem()).Interface()
+			} else {
+				v = rv.Elem().Interface()
+			}
 		}
-		b = b[n:]
-	}
-
-	// Transpose the set of descriptors into a list.
-	var xts []*ExtensionDesc
-	for num, xt := range extDescs {
-		if xt == nil {
-			xt = &ExtensionDesc{Field: int32(num)}
+	case reflect.Slice:
+		// Represent slice types as a pointer to the value.
+		if rv.Type().Elem().Kind() != reflect.Uint8 {
+			rv2 := reflect.New(rv.Type())
+			rv2.Elem().Set(rv)
+			v = rv2.Interface()
 		}
-		xts = append(xts, xt)
 	}
-	return xts, nil
-}
-
-// isValidExtension reports whether xtd is a valid extension descriptor for md.
-func isValidExtension(md protoreflect.MessageDescriptor, xtd protoreflect.ExtensionTypeDescriptor) bool {
-	return xtd.ContainingMessage() == md && md.ExtensionRanges().Has(xtd.Number())
-}
-
-// isScalarKind reports whether k is a protobuf scalar kind (except bytes).
-// This function exists for historical reasons since the representation of
-// scalars differs between v1 and v2, where v1 uses *T and v2 uses T.
-func isScalarKind(k reflect.Kind) bool {
-	switch k {
-	case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
-		return true
-	default:
-		return false
-	}
-}
-
-// clearUnknown removes unknown fields from m where remover.Has reports true.
-func clearUnknown(m protoreflect.Message, remover interface {
-	Has(protoreflect.FieldNumber) bool
-}) {
-	var bo protoreflect.RawFields
-	for bi := m.GetUnknown(); len(bi) > 0; {
-		num, _, n := protowire.ConsumeField(bi)
-		if !remover.Has(num) {
-			bo = append(bo, bi[:n]...)
-		}
-		bi = bi[n:]
-	}
-	if bi := m.GetUnknown(); len(bi) != len(bo) {
-		m.SetUnknown(bo)
-	}
-}
-
-type fieldNum protoreflect.FieldNumber
-
-func (n1 fieldNum) Has(n2 protoreflect.FieldNumber) bool {
-	return protoreflect.FieldNumber(n1) == n2
+	return v
 }