diff --git a/vendor/google.golang.org/protobuf/internal/impl/pointer_unsafe.go b/vendor/google.golang.org/protobuf/internal/impl/pointer_unsafe.go
new file mode 100644
index 0000000..9ecf23a
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/pointer_unsafe.go
@@ -0,0 +1,174 @@
+// 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.
+
+// +build !purego,!appengine
+
+package impl
+
+import (
+	"reflect"
+	"sync/atomic"
+	"unsafe"
+)
+
+const UnsafeEnabled = true
+
+// Pointer is an opaque pointer type.
+type Pointer unsafe.Pointer
+
+// offset represents the offset to a struct field, accessible from a pointer.
+// The offset is the byte offset to the field from the start of the struct.
+type offset uintptr
+
+// offsetOf returns a field offset for the struct field.
+func offsetOf(f reflect.StructField, x exporter) offset {
+	return offset(f.Offset)
+}
+
+// IsValid reports whether the offset is valid.
+func (f offset) IsValid() bool { return f != invalidOffset }
+
+// invalidOffset is an invalid field offset.
+var invalidOffset = ^offset(0)
+
+// zeroOffset is a noop when calling pointer.Apply.
+var zeroOffset = offset(0)
+
+// pointer is a pointer to a message struct or field.
+type pointer struct{ p unsafe.Pointer }
+
+// pointerOf returns p as a pointer.
+func pointerOf(p Pointer) pointer {
+	return pointer{p: unsafe.Pointer(p)}
+}
+
+// pointerOfValue returns v as a pointer.
+func pointerOfValue(v reflect.Value) pointer {
+	return pointer{p: unsafe.Pointer(v.Pointer())}
+}
+
+// pointerOfIface returns the pointer portion of an interface.
+func pointerOfIface(v interface{}) pointer {
+	type ifaceHeader struct {
+		Type unsafe.Pointer
+		Data unsafe.Pointer
+	}
+	return pointer{p: (*ifaceHeader)(unsafe.Pointer(&v)).Data}
+}
+
+// IsNil reports whether the pointer is nil.
+func (p pointer) IsNil() bool {
+	return p.p == nil
+}
+
+// Apply adds an offset to the pointer to derive a new pointer
+// to a specified field. The pointer must be valid and pointing at a struct.
+func (p pointer) Apply(f offset) pointer {
+	if p.IsNil() {
+		panic("invalid nil pointer")
+	}
+	return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}
+}
+
+// AsValueOf treats p as a pointer to an object of type t and returns the value.
+// It is equivalent to reflect.ValueOf(p.AsIfaceOf(t))
+func (p pointer) AsValueOf(t reflect.Type) reflect.Value {
+	return reflect.NewAt(t, p.p)
+}
+
+// AsIfaceOf treats p as a pointer to an object of type t and returns the value.
+// It is equivalent to p.AsValueOf(t).Interface()
+func (p pointer) AsIfaceOf(t reflect.Type) interface{} {
+	// TODO: Use tricky unsafe magic to directly create ifaceHeader.
+	return p.AsValueOf(t).Interface()
+}
+
+func (p pointer) Bool() *bool                           { return (*bool)(p.p) }
+func (p pointer) BoolPtr() **bool                       { return (**bool)(p.p) }
+func (p pointer) BoolSlice() *[]bool                    { return (*[]bool)(p.p) }
+func (p pointer) Int32() *int32                         { return (*int32)(p.p) }
+func (p pointer) Int32Ptr() **int32                     { return (**int32)(p.p) }
+func (p pointer) Int32Slice() *[]int32                  { return (*[]int32)(p.p) }
+func (p pointer) Int64() *int64                         { return (*int64)(p.p) }
+func (p pointer) Int64Ptr() **int64                     { return (**int64)(p.p) }
+func (p pointer) Int64Slice() *[]int64                  { return (*[]int64)(p.p) }
+func (p pointer) Uint32() *uint32                       { return (*uint32)(p.p) }
+func (p pointer) Uint32Ptr() **uint32                   { return (**uint32)(p.p) }
+func (p pointer) Uint32Slice() *[]uint32                { return (*[]uint32)(p.p) }
+func (p pointer) Uint64() *uint64                       { return (*uint64)(p.p) }
+func (p pointer) Uint64Ptr() **uint64                   { return (**uint64)(p.p) }
+func (p pointer) Uint64Slice() *[]uint64                { return (*[]uint64)(p.p) }
+func (p pointer) Float32() *float32                     { return (*float32)(p.p) }
+func (p pointer) Float32Ptr() **float32                 { return (**float32)(p.p) }
+func (p pointer) Float32Slice() *[]float32              { return (*[]float32)(p.p) }
+func (p pointer) Float64() *float64                     { return (*float64)(p.p) }
+func (p pointer) Float64Ptr() **float64                 { return (**float64)(p.p) }
+func (p pointer) Float64Slice() *[]float64              { return (*[]float64)(p.p) }
+func (p pointer) String() *string                       { return (*string)(p.p) }
+func (p pointer) StringPtr() **string                   { return (**string)(p.p) }
+func (p pointer) StringSlice() *[]string                { return (*[]string)(p.p) }
+func (p pointer) Bytes() *[]byte                        { return (*[]byte)(p.p) }
+func (p pointer) BytesPtr() **[]byte                    { return (**[]byte)(p.p) }
+func (p pointer) BytesSlice() *[][]byte                 { return (*[][]byte)(p.p) }
+func (p pointer) WeakFields() *weakFields               { return (*weakFields)(p.p) }
+func (p pointer) Extensions() *map[int32]ExtensionField { return (*map[int32]ExtensionField)(p.p) }
+
+func (p pointer) Elem() pointer {
+	return pointer{p: *(*unsafe.Pointer)(p.p)}
+}
+
+// PointerSlice loads []*T from p as a []pointer.
+// The value returned is aliased with the original slice.
+// This behavior differs from the implementation in pointer_reflect.go.
+func (p pointer) PointerSlice() []pointer {
+	// Super-tricky - p should point to a []*T where T is a
+	// message type. We load it as []pointer.
+	return *(*[]pointer)(p.p)
+}
+
+// AppendPointerSlice appends v to p, which must be a []*T.
+func (p pointer) AppendPointerSlice(v pointer) {
+	*(*[]pointer)(p.p) = append(*(*[]pointer)(p.p), v)
+}
+
+// SetPointer sets *p to v.
+func (p pointer) SetPointer(v pointer) {
+	*(*unsafe.Pointer)(p.p) = (unsafe.Pointer)(v.p)
+}
+
+// Static check that MessageState does not exceed the size of a pointer.
+const _ = uint(unsafe.Sizeof(unsafe.Pointer(nil)) - unsafe.Sizeof(MessageState{}))
+
+func (Export) MessageStateOf(p Pointer) *messageState {
+	// Super-tricky - see documentation on MessageState.
+	return (*messageState)(unsafe.Pointer(p))
+}
+func (ms *messageState) pointer() pointer {
+	// Super-tricky - see documentation on MessageState.
+	return pointer{p: unsafe.Pointer(ms)}
+}
+func (ms *messageState) messageInfo() *MessageInfo {
+	mi := ms.LoadMessageInfo()
+	if mi == nil {
+		panic("invalid nil message info; this suggests memory corruption due to a race or shallow copy on the message struct")
+	}
+	return mi
+}
+func (ms *messageState) LoadMessageInfo() *MessageInfo {
+	return (*MessageInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&ms.atomicMessageInfo))))
+}
+func (ms *messageState) StoreMessageInfo(mi *MessageInfo) {
+	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&ms.atomicMessageInfo)), unsafe.Pointer(mi))
+}
+
+type atomicNilMessage struct{ p unsafe.Pointer } // p is a *messageReflectWrapper
+
+func (m *atomicNilMessage) Init(mi *MessageInfo) *messageReflectWrapper {
+	if p := atomic.LoadPointer(&m.p); p != nil {
+		return (*messageReflectWrapper)(p)
+	}
+	w := &messageReflectWrapper{mi: mi}
+	atomic.CompareAndSwapPointer(&m.p, nil, (unsafe.Pointer)(w))
+	return (*messageReflectWrapper)(atomic.LoadPointer(&m.p))
+}