chromeos/services/device_sync/remote_device_loader.h

// Copyright 2015 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.

#ifndef CHROMEOS_SERVICES_DEVICE_SYNC_REMOTE_DEVICE_LOADER_H_
#define CHROMEOS_SERVICES_DEVICE_SYNC_REMOTE_DEVICE_LOADER_H_

#include <memory>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "chromeos/components/multidevice/remote_device.h"
#include "chromeos/services/device_sync/proto/cryptauth_api.pb.h"

namespace chromeos {

namespace multidevice {
class SecureMessageDelegate;
}  // namespace multidevice

namespace device_sync {

// Loads a collection of chromeos::multidevice::RemoteDevice objects from the
// given cryptauth::ExternalDeviceInfo protos that were synced from CryptAuth.
// We need to derive the PSK, which is a symmetric key used to authenticate each
// remote device.
class RemoteDeviceLoader {
 public:
  class Factory {
   public:
    static std::unique_ptr<RemoteDeviceLoader> NewInstance(
        const std::vector<cryptauth::ExternalDeviceInfo>& device_info_list,
        const std::string& user_id,
        const std::string& user_private_key,
        std::unique_ptr<multidevice::SecureMessageDelegate>
            secure_message_delegate);

    static void SetInstanceForTesting(Factory* factory);

   protected:
    virtual std::unique_ptr<RemoteDeviceLoader> BuildInstance(
        const std::vector<cryptauth::ExternalDeviceInfo>& device_info_list,
        const std::string& user_id,
        const std::string& user_private_key,
        std::unique_ptr<multidevice::SecureMessageDelegate>
            secure_message_delegate);

   private:
    static Factory* factory_instance_;
  };

  // Creates the instance:
  // |device_info_list|: The cryptauth::ExternalDeviceInfo objects to convert to
  //                     chromeos::multidevice::RemoteDevice.
  // |user_private_key|: The private key of the user's local device. Used to
  //                     derive the PSK.
  // |secure_message_delegate|: Used to derive each persistent symmetric key.
  RemoteDeviceLoader(
      const std::vector<cryptauth::ExternalDeviceInfo>& device_info_list,
      const std::string& user_id,
      const std::string& user_private_key,
      std::unique_ptr<multidevice::SecureMessageDelegate>
          secure_message_delegate);

  virtual ~RemoteDeviceLoader();

  // Loads the chromeos::multidevice::RemoteDevice objects. |callback| will be
  // invoked upon completion.
  typedef base::Callback<void(const chromeos::multidevice::RemoteDeviceList&)>
      RemoteDeviceCallback;
  virtual void Load(const RemoteDeviceCallback& callback);

 private:
  // Called when the PSK is derived for each device. If the PSKs for all devices
  // have been derived, then we can invoke |callback_|.
  void OnPSKDerived(const cryptauth::ExternalDeviceInfo& device,
                    const std::string& psk);

  // The remaining devices whose PSK we're waiting on.
  std::vector<cryptauth::ExternalDeviceInfo> remaining_devices_;

  // The id of the user who the remote devices belong to.
  const std::string user_id_;

  // The private key of the user's local device.
  const std::string user_private_key_;

  // Performs the PSK key derivation.
  std::unique_ptr<multidevice::SecureMessageDelegate> secure_message_delegate_;

  // Invoked when the chromeos::multidevice::RemoteDevices are loaded.
  RemoteDeviceCallback callback_;

  // The collection of chromeos::multidevice::RemoteDevices to return.
  chromeos::multidevice::RemoteDeviceList remote_devices_;

  base::WeakPtrFactory<RemoteDeviceLoader> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(RemoteDeviceLoader);
};

}  // namespace device_sync

}  // namespace chromeos

#endif  // CHROMEOS_SERVICES_DEVICE_SYNC_REMOTE_DEVICE_LOADER_H_