diff --git a/vendor/google.golang.org/protobuf/internal/impl/validate.go b/vendor/google.golang.org/protobuf/internal/impl/validate.go
new file mode 100644
index 0000000..08cfb60
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/validate.go
@@ -0,0 +1,576 @@
+// Copyright 2019 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"
+	"math"
+	"math/bits"
+	"reflect"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/internal/encoding/messageset"
+	"google.golang.org/protobuf/internal/flags"
+	"google.golang.org/protobuf/internal/genid"
+	"google.golang.org/protobuf/internal/strs"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	preg "google.golang.org/protobuf/reflect/protoregistry"
+	piface "google.golang.org/protobuf/runtime/protoiface"
+)
+
+// ValidationStatus is the result of validating the wire-format encoding of a message.
+type ValidationStatus int
+
+const (
+	// ValidationUnknown indicates that unmarshaling the message might succeed or fail.
+	// The validator was unable to render a judgement.
+	//
+	// The only causes of this status are an aberrant message type appearing somewhere
+	// in the message or a failure in the extension resolver.
+	ValidationUnknown ValidationStatus = iota + 1
+
+	// ValidationInvalid indicates that unmarshaling the message will fail.
+	ValidationInvalid
+
+	// ValidationValid indicates that unmarshaling the message will succeed.
+	ValidationValid
+)
+
+func (v ValidationStatus) String() string {
+	switch v {
+	case ValidationUnknown:
+		return "ValidationUnknown"
+	case ValidationInvalid:
+		return "ValidationInvalid"
+	case ValidationValid:
+		return "ValidationValid"
+	default:
+		return fmt.Sprintf("ValidationStatus(%d)", int(v))
+	}
+}
+
+// Validate determines whether the contents of the buffer are a valid wire encoding
+// of the message type.
+//
+// This function is exposed for testing.
+func Validate(mt pref.MessageType, in piface.UnmarshalInput) (out piface.UnmarshalOutput, _ ValidationStatus) {
+	mi, ok := mt.(*MessageInfo)
+	if !ok {
+		return out, ValidationUnknown
+	}
+	if in.Resolver == nil {
+		in.Resolver = preg.GlobalTypes
+	}
+	o, st := mi.validate(in.Buf, 0, unmarshalOptions{
+		flags:    in.Flags,
+		resolver: in.Resolver,
+	})
+	if o.initialized {
+		out.Flags |= piface.UnmarshalInitialized
+	}
+	return out, st
+}
+
+type validationInfo struct {
+	mi               *MessageInfo
+	typ              validationType
+	keyType, valType validationType
+
+	// For non-required fields, requiredBit is 0.
+	//
+	// For required fields, requiredBit's nth bit is set, where n is a
+	// unique index in the range [0, MessageInfo.numRequiredFields).
+	//
+	// If there are more than 64 required fields, requiredBit is 0.
+	requiredBit uint64
+}
+
+type validationType uint8
+
+const (
+	validationTypeOther validationType = iota
+	validationTypeMessage
+	validationTypeGroup
+	validationTypeMap
+	validationTypeRepeatedVarint
+	validationTypeRepeatedFixed32
+	validationTypeRepeatedFixed64
+	validationTypeVarint
+	validationTypeFixed32
+	validationTypeFixed64
+	validationTypeBytes
+	validationTypeUTF8String
+	validationTypeMessageSetItem
+)
+
+func newFieldValidationInfo(mi *MessageInfo, si structInfo, fd pref.FieldDescriptor, ft reflect.Type) validationInfo {
+	var vi validationInfo
+	switch {
+	case fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic():
+		switch fd.Kind() {
+		case pref.MessageKind:
+			vi.typ = validationTypeMessage
+			if ot, ok := si.oneofWrappersByNumber[fd.Number()]; ok {
+				vi.mi = getMessageInfo(ot.Field(0).Type)
+			}
+		case pref.GroupKind:
+			vi.typ = validationTypeGroup
+			if ot, ok := si.oneofWrappersByNumber[fd.Number()]; ok {
+				vi.mi = getMessageInfo(ot.Field(0).Type)
+			}
+		case pref.StringKind:
+			if strs.EnforceUTF8(fd) {
+				vi.typ = validationTypeUTF8String
+			}
+		}
+	default:
+		vi = newValidationInfo(fd, ft)
+	}
+	if fd.Cardinality() == pref.Required {
+		// Avoid overflow. The required field check is done with a 64-bit mask, with
+		// any message containing more than 64 required fields always reported as
+		// potentially uninitialized, so it is not important to get a precise count
+		// of the required fields past 64.
+		if mi.numRequiredFields < math.MaxUint8 {
+			mi.numRequiredFields++
+			vi.requiredBit = 1 << (mi.numRequiredFields - 1)
+		}
+	}
+	return vi
+}
+
+func newValidationInfo(fd pref.FieldDescriptor, ft reflect.Type) validationInfo {
+	var vi validationInfo
+	switch {
+	case fd.IsList():
+		switch fd.Kind() {
+		case pref.MessageKind:
+			vi.typ = validationTypeMessage
+			if ft.Kind() == reflect.Slice {
+				vi.mi = getMessageInfo(ft.Elem())
+			}
+		case pref.GroupKind:
+			vi.typ = validationTypeGroup
+			if ft.Kind() == reflect.Slice {
+				vi.mi = getMessageInfo(ft.Elem())
+			}
+		case pref.StringKind:
+			vi.typ = validationTypeBytes
+			if strs.EnforceUTF8(fd) {
+				vi.typ = validationTypeUTF8String
+			}
+		default:
+			switch wireTypes[fd.Kind()] {
+			case protowire.VarintType:
+				vi.typ = validationTypeRepeatedVarint
+			case protowire.Fixed32Type:
+				vi.typ = validationTypeRepeatedFixed32
+			case protowire.Fixed64Type:
+				vi.typ = validationTypeRepeatedFixed64
+			}
+		}
+	case fd.IsMap():
+		vi.typ = validationTypeMap
+		switch fd.MapKey().Kind() {
+		case pref.StringKind:
+			if strs.EnforceUTF8(fd) {
+				vi.keyType = validationTypeUTF8String
+			}
+		}
+		switch fd.MapValue().Kind() {
+		case pref.MessageKind:
+			vi.valType = validationTypeMessage
+			if ft.Kind() == reflect.Map {
+				vi.mi = getMessageInfo(ft.Elem())
+			}
+		case pref.StringKind:
+			if strs.EnforceUTF8(fd) {
+				vi.valType = validationTypeUTF8String
+			}
+		}
+	default:
+		switch fd.Kind() {
+		case pref.MessageKind:
+			vi.typ = validationTypeMessage
+			if !fd.IsWeak() {
+				vi.mi = getMessageInfo(ft)
+			}
+		case pref.GroupKind:
+			vi.typ = validationTypeGroup
+			vi.mi = getMessageInfo(ft)
+		case pref.StringKind:
+			vi.typ = validationTypeBytes
+			if strs.EnforceUTF8(fd) {
+				vi.typ = validationTypeUTF8String
+			}
+		default:
+			switch wireTypes[fd.Kind()] {
+			case protowire.VarintType:
+				vi.typ = validationTypeVarint
+			case protowire.Fixed32Type:
+				vi.typ = validationTypeFixed32
+			case protowire.Fixed64Type:
+				vi.typ = validationTypeFixed64
+			case protowire.BytesType:
+				vi.typ = validationTypeBytes
+			}
+		}
+	}
+	return vi
+}
+
+func (mi *MessageInfo) validate(b []byte, groupTag protowire.Number, opts unmarshalOptions) (out unmarshalOutput, result ValidationStatus) {
+	mi.init()
+	type validationState struct {
+		typ              validationType
+		keyType, valType validationType
+		endGroup         protowire.Number
+		mi               *MessageInfo
+		tail             []byte
+		requiredMask     uint64
+	}
+
+	// Pre-allocate some slots to avoid repeated slice reallocation.
+	states := make([]validationState, 0, 16)
+	states = append(states, validationState{
+		typ: validationTypeMessage,
+		mi:  mi,
+	})
+	if groupTag > 0 {
+		states[0].typ = validationTypeGroup
+		states[0].endGroup = groupTag
+	}
+	initialized := true
+	start := len(b)
+State:
+	for len(states) > 0 {
+		st := &states[len(states)-1]
+		for len(b) > 0 {
+			// Parse the tag (field number and wire type).
+			var tag uint64
+			if b[0] < 0x80 {
+				tag = uint64(b[0])
+				b = b[1:]
+			} else if len(b) >= 2 && b[1] < 128 {
+				tag = uint64(b[0]&0x7f) + uint64(b[1])<<7
+				b = b[2:]
+			} else {
+				var n int
+				tag, n = protowire.ConsumeVarint(b)
+				if n < 0 {
+					return out, ValidationInvalid
+				}
+				b = b[n:]
+			}
+			var num protowire.Number
+			if n := tag >> 3; n < uint64(protowire.MinValidNumber) || n > uint64(protowire.MaxValidNumber) {
+				return out, ValidationInvalid
+			} else {
+				num = protowire.Number(n)
+			}
+			wtyp := protowire.Type(tag & 7)
+
+			if wtyp == protowire.EndGroupType {
+				if st.endGroup == num {
+					goto PopState
+				}
+				return out, ValidationInvalid
+			}
+			var vi validationInfo
+			switch {
+			case st.typ == validationTypeMap:
+				switch num {
+				case genid.MapEntry_Key_field_number:
+					vi.typ = st.keyType
+				case genid.MapEntry_Value_field_number:
+					vi.typ = st.valType
+					vi.mi = st.mi
+					vi.requiredBit = 1
+				}
+			case flags.ProtoLegacy && st.mi.isMessageSet:
+				switch num {
+				case messageset.FieldItem:
+					vi.typ = validationTypeMessageSetItem
+				}
+			default:
+				var f *coderFieldInfo
+				if int(num) < len(st.mi.denseCoderFields) {
+					f = st.mi.denseCoderFields[num]
+				} else {
+					f = st.mi.coderFields[num]
+				}
+				if f != nil {
+					vi = f.validation
+					if vi.typ == validationTypeMessage && vi.mi == nil {
+						// Probable weak field.
+						//
+						// TODO: Consider storing the results of this lookup somewhere
+						// rather than recomputing it on every validation.
+						fd := st.mi.Desc.Fields().ByNumber(num)
+						if fd == nil || !fd.IsWeak() {
+							break
+						}
+						messageName := fd.Message().FullName()
+						messageType, err := preg.GlobalTypes.FindMessageByName(messageName)
+						switch err {
+						case nil:
+							vi.mi, _ = messageType.(*MessageInfo)
+						case preg.NotFound:
+							vi.typ = validationTypeBytes
+						default:
+							return out, ValidationUnknown
+						}
+					}
+					break
+				}
+				// Possible extension field.
+				//
+				// TODO: We should return ValidationUnknown when:
+				//   1. The resolver is not frozen. (More extensions may be added to it.)
+				//   2. The resolver returns preg.NotFound.
+				// In this case, a type added to the resolver in the future could cause
+				// unmarshaling to begin failing. Supporting this requires some way to
+				// determine if the resolver is frozen.
+				xt, err := opts.resolver.FindExtensionByNumber(st.mi.Desc.FullName(), num)
+				if err != nil && err != preg.NotFound {
+					return out, ValidationUnknown
+				}
+				if err == nil {
+					vi = getExtensionFieldInfo(xt).validation
+				}
+			}
+			if vi.requiredBit != 0 {
+				// Check that the field has a compatible wire type.
+				// We only need to consider non-repeated field types,
+				// since repeated fields (and maps) can never be required.
+				ok := false
+				switch vi.typ {
+				case validationTypeVarint:
+					ok = wtyp == protowire.VarintType
+				case validationTypeFixed32:
+					ok = wtyp == protowire.Fixed32Type
+				case validationTypeFixed64:
+					ok = wtyp == protowire.Fixed64Type
+				case validationTypeBytes, validationTypeUTF8String, validationTypeMessage:
+					ok = wtyp == protowire.BytesType
+				case validationTypeGroup:
+					ok = wtyp == protowire.StartGroupType
+				}
+				if ok {
+					st.requiredMask |= vi.requiredBit
+				}
+			}
+
+			switch wtyp {
+			case protowire.VarintType:
+				if len(b) >= 10 {
+					switch {
+					case b[0] < 0x80:
+						b = b[1:]
+					case b[1] < 0x80:
+						b = b[2:]
+					case b[2] < 0x80:
+						b = b[3:]
+					case b[3] < 0x80:
+						b = b[4:]
+					case b[4] < 0x80:
+						b = b[5:]
+					case b[5] < 0x80:
+						b = b[6:]
+					case b[6] < 0x80:
+						b = b[7:]
+					case b[7] < 0x80:
+						b = b[8:]
+					case b[8] < 0x80:
+						b = b[9:]
+					case b[9] < 0x80 && b[9] < 2:
+						b = b[10:]
+					default:
+						return out, ValidationInvalid
+					}
+				} else {
+					switch {
+					case len(b) > 0 && b[0] < 0x80:
+						b = b[1:]
+					case len(b) > 1 && b[1] < 0x80:
+						b = b[2:]
+					case len(b) > 2 && b[2] < 0x80:
+						b = b[3:]
+					case len(b) > 3 && b[3] < 0x80:
+						b = b[4:]
+					case len(b) > 4 && b[4] < 0x80:
+						b = b[5:]
+					case len(b) > 5 && b[5] < 0x80:
+						b = b[6:]
+					case len(b) > 6 && b[6] < 0x80:
+						b = b[7:]
+					case len(b) > 7 && b[7] < 0x80:
+						b = b[8:]
+					case len(b) > 8 && b[8] < 0x80:
+						b = b[9:]
+					case len(b) > 9 && b[9] < 2:
+						b = b[10:]
+					default:
+						return out, ValidationInvalid
+					}
+				}
+				continue State
+			case protowire.BytesType:
+				var size uint64
+				if len(b) >= 1 && b[0] < 0x80 {
+					size = uint64(b[0])
+					b = b[1:]
+				} else if len(b) >= 2 && b[1] < 128 {
+					size = uint64(b[0]&0x7f) + uint64(b[1])<<7
+					b = b[2:]
+				} else {
+					var n int
+					size, n = protowire.ConsumeVarint(b)
+					if n < 0 {
+						return out, ValidationInvalid
+					}
+					b = b[n:]
+				}
+				if size > uint64(len(b)) {
+					return out, ValidationInvalid
+				}
+				v := b[:size]
+				b = b[size:]
+				switch vi.typ {
+				case validationTypeMessage:
+					if vi.mi == nil {
+						return out, ValidationUnknown
+					}
+					vi.mi.init()
+					fallthrough
+				case validationTypeMap:
+					if vi.mi != nil {
+						vi.mi.init()
+					}
+					states = append(states, validationState{
+						typ:     vi.typ,
+						keyType: vi.keyType,
+						valType: vi.valType,
+						mi:      vi.mi,
+						tail:    b,
+					})
+					b = v
+					continue State
+				case validationTypeRepeatedVarint:
+					// Packed field.
+					for len(v) > 0 {
+						_, n := protowire.ConsumeVarint(v)
+						if n < 0 {
+							return out, ValidationInvalid
+						}
+						v = v[n:]
+					}
+				case validationTypeRepeatedFixed32:
+					// Packed field.
+					if len(v)%4 != 0 {
+						return out, ValidationInvalid
+					}
+				case validationTypeRepeatedFixed64:
+					// Packed field.
+					if len(v)%8 != 0 {
+						return out, ValidationInvalid
+					}
+				case validationTypeUTF8String:
+					if !utf8.Valid(v) {
+						return out, ValidationInvalid
+					}
+				}
+			case protowire.Fixed32Type:
+				if len(b) < 4 {
+					return out, ValidationInvalid
+				}
+				b = b[4:]
+			case protowire.Fixed64Type:
+				if len(b) < 8 {
+					return out, ValidationInvalid
+				}
+				b = b[8:]
+			case protowire.StartGroupType:
+				switch {
+				case vi.typ == validationTypeGroup:
+					if vi.mi == nil {
+						return out, ValidationUnknown
+					}
+					vi.mi.init()
+					states = append(states, validationState{
+						typ:      validationTypeGroup,
+						mi:       vi.mi,
+						endGroup: num,
+					})
+					continue State
+				case flags.ProtoLegacy && vi.typ == validationTypeMessageSetItem:
+					typeid, v, n, err := messageset.ConsumeFieldValue(b, false)
+					if err != nil {
+						return out, ValidationInvalid
+					}
+					xt, err := opts.resolver.FindExtensionByNumber(st.mi.Desc.FullName(), typeid)
+					switch {
+					case err == preg.NotFound:
+						b = b[n:]
+					case err != nil:
+						return out, ValidationUnknown
+					default:
+						xvi := getExtensionFieldInfo(xt).validation
+						if xvi.mi != nil {
+							xvi.mi.init()
+						}
+						states = append(states, validationState{
+							typ:  xvi.typ,
+							mi:   xvi.mi,
+							tail: b[n:],
+						})
+						b = v
+						continue State
+					}
+				default:
+					n := protowire.ConsumeFieldValue(num, wtyp, b)
+					if n < 0 {
+						return out, ValidationInvalid
+					}
+					b = b[n:]
+				}
+			default:
+				return out, ValidationInvalid
+			}
+		}
+		if st.endGroup != 0 {
+			return out, ValidationInvalid
+		}
+		if len(b) != 0 {
+			return out, ValidationInvalid
+		}
+		b = st.tail
+	PopState:
+		numRequiredFields := 0
+		switch st.typ {
+		case validationTypeMessage, validationTypeGroup:
+			numRequiredFields = int(st.mi.numRequiredFields)
+		case validationTypeMap:
+			// If this is a map field with a message value that contains
+			// required fields, require that the value be present.
+			if st.mi != nil && st.mi.numRequiredFields > 0 {
+				numRequiredFields = 1
+			}
+		}
+		// If there are more than 64 required fields, this check will
+		// always fail and we will report that the message is potentially
+		// uninitialized.
+		if numRequiredFields > 0 && bits.OnesCount64(st.requiredMask) != numRequiredFields {
+			initialized = false
+		}
+		states = states[:len(states)-1]
+	}
+	out.n = start - len(b)
+	if initialized {
+		out.initialized = true
+	}
+	return out, ValidationValid
+}