[CrOS Tether] Create MessageWrapper, a wrapper class for proto messages sent for tethering. This cl…

chromeos/components/tether/message_wrapper.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <google/protobuf/message_lite.h>
+#include <memory>
+
+#include "base/macros.h"
+#include "chromeos/components/tether/proto/tether.pb.h"
+
+namespace chromeos {
+
+namespace tether {
+
+// Wraps a message sent between devices. To send a message over the wire,
+// construct a MessageWrapper by passing the message's proto as a constructor
+// parameter, then call |ToRawMessage()| and send the resulting string. When a
+// message has been received, pass it to |FromRawMessage()| to create a
+// MessageWrapper object, then use |GetMessageType()| to determine the type of
+// message that has been received. To access the wrapped proto for a received
+// message, call |GetProto()| and cast the result to the associated message
+// class.
+class MessageWrapper {
+ public:
+  // Creates a MessageWrapper from a raw string received from a remote device.
+  // Returns |nullptr| if the received message is not a valid tethering message.
+  static std::unique_ptr<MessageWrapper> FromRawMessage(
+      const std::string& message);
+
+  MessageWrapper(const ConnectTetheringRequest& request);
+  MessageWrapper(const ConnectTetheringResponse& response);
+  MessageWrapper(const DisconnectTetheringRequest& request);
+  MessageWrapper(const KeepAliveTickle& tickle);
+  MessageWrapper(const TetherAvailabilityRequest& request);
+  MessageWrapper(const TetherAvailabilityResponse& response);
+
+  ~MessageWrapper();
+
+  std::shared_ptr<google::protobuf::MessageLite> GetProto() const;
+  MessageType GetMessageType() const;
+
+  // To send a message to a remote device, use ToRawMessage() and send the
+  // result over the wire.
+  std::string ToRawMessage() const;
+
+ protected:
+  MessageWrapper(const MessageType& type,
+                 std::shared_ptr<google::protobuf::MessageLite> proto);
+
+ private:
+  MessageType type_;
+  std::shared_ptr<google::protobuf::MessageLite> proto_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessageWrapper);
+};
+
+}  // namespace tether
+
+}  // namespace chromeos