[CrOS Tether]: Create BleConnectionManager, which manages secure connections between the current de…

chromeos/components/tether/ble_connection_manager.cc

+// 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 "chromeos/components/tether/ble_connection_manager.h"
+
+#include "chromeos/components/tether/ble_constants.h"
+#include "components/cryptauth/ble/bluetooth_low_energy_weave_client_connection.h"
+#include "components/proximity_auth/logging/logging.h"
+#include "device/bluetooth/bluetooth_uuid.h"
+
+namespace chromeos {
+
+namespace tether {
+
+namespace {
+const char kTetherFeature[] = "magic_tether";
+const int64_t kAdvertisingTimeoutMillis = 12000;
+const int64_t kShortErrorTimeoutMillis = 100;

[Ryan Hansberry, 2017/02/16 19:29:35]

Didn't we agree to make this 0?

[Kyle Horimoto, 2017/02/17 01:06:52]

Done.

+}  // namespace
+
+// static
+std::string BleConnectionManager::MessageTypeToString(
+    const MessageType& reason) {
+  switch (reason) {
+    case MessageType::TETHER_AVAILABILITY_REQUEST:
+      return "[TetherAvailabilityRequest]";
+    case MessageType::CONNECT_TETHERING_REQUEST:
+      return "[ConnectTetheringRequest]";
+    case MessageType::KEEP_ALIVE_TICKLE:
+      return "[KeepAliveTickle]";
+    case MessageType::DISCONNECT_TETHERING_REQUEST:
+      return "[DisconnectTetheringRequest]";
+    default:
+      return "[invalid MessageType]";
+  }
+}
+
+BleConnectionManager::ConnectionMetadata::ConnectionMetadata(
+    const cryptauth::RemoteDevice remote_device,
+    std::shared_ptr<base::Timer> timer,
+    base::WeakPtr<BleConnectionManager> manager)
+    : remote_device_(remote_device),
+      connection_attempt_timeout_timer_(timer),
+      manager_(manager),
+      weak_ptr_factory_(this) {}
+
+BleConnectionManager::ConnectionMetadata::~ConnectionMetadata() {}
+
+void BleConnectionManager::ConnectionMetadata::RegisterConnectionReason(
+    const MessageType& connection_reason) {
+  active_connection_reasons_.insert(connection_reason);
+}
+
+void BleConnectionManager::ConnectionMetadata::UnregisterConnectionReason(
+    const MessageType& connection_reason) {
+  active_connection_reasons_.erase(connection_reason);
+}
+
+bool BleConnectionManager::ConnectionMetadata::HasReasonForConnection() const {
+  return !active_connection_reasons_.empty();
+}
+
+bool BleConnectionManager::ConnectionMetadata::HasEstablishedConnection()
+    const {
+  return secure_channel_.get();
+}
+
+cryptauth::SecureChannel::Status
+BleConnectionManager::ConnectionMetadata::GetStatus() const {

[Ryan Hansberry, 2017/02/16 19:29:35]

Why not always return secure_channel's status unless it is null? (why does the
timer need to factor into this)

[Kyle Horimoto, 2017/02/17 01:06:52]

If the ConnectionMetadata is associated with a device that is "in line" to
attempt a connection (i.e., other devices have occupied the available
advertising slots), it is DISCONNECTED. Thus, we need to check if the timer is
active to determine if it is CONNECTING.

[Ryan Hansberry, 2017/02/17 01:59:05]

Got it. Please add a brief comment explaining that.

[Kyle Horimoto, 2017/02/17 02:08:52]

Done.

+  if (connection_attempt_timeout_timer_->IsRunning()) {
+    return cryptauth::SecureChannel::Status::CONNECTING;
+  } else if (!HasEstablishedConnection()) {
+    return cryptauth::SecureChannel::Status::DISCONNECTED;
+  }
+
+  return secure_channel_->status();
+}
+
+void BleConnectionManager::ConnectionMetadata::StartConnectionAttemptTimer(
+    bool use_short_error_timeout) {
+  DCHECK(!secure_channel_);
+  DCHECK(!connection_attempt_timeout_timer_->IsRunning());
+
+  int64_t timeout_millis = use_short_error_timeout ? kShortErrorTimeoutMillis
+                                                   : kAdvertisingTimeoutMillis;
+
+  connection_attempt_timeout_timer_->Start(
+      FROM_HERE, base::TimeDelta::FromMilliseconds(timeout_millis),
+      base::Bind(&ConnectionMetadata::OnConnectionAttemptTimeout,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void BleConnectionManager::ConnectionMetadata::OnConnectionAttemptTimeout() {
+  manager_->OnConnectionAttemptTimeout(remote_device_);
+}
+
+void BleConnectionManager::ConnectionMetadata::SetSecureChannel(
+    std::unique_ptr<cryptauth::SecureChannel> secure_channel) {
+  DCHECK(!secure_channel_);
+
+  // The connection has succeeded, so cancel the timeout.
+  connection_attempt_timeout_timer_->Stop();
+
+  secure_channel_ = std::move(secure_channel);
+  secure_channel_->AddObserver(this);
+  secure_channel_->Initialize();
+}
+
+void BleConnectionManager::ConnectionMetadata::SendMessage(
+    const std::string& payload) {
+  DCHECK(GetStatus() == cryptauth::SecureChannel::Status::AUTHENTICATED);
+  secure_channel_->SendMessage(std::string(kTetherFeature), payload);
+}
+
+void BleConnectionManager::ConnectionMetadata::OnSecureChannelStatusChanged(
+    cryptauth::SecureChannel* secure_channel,
+    const cryptauth::SecureChannel::Status& old_status,
+    const cryptauth::SecureChannel::Status& new_status) {
+  DCHECK(secure_channel_.get() == secure_channel);
+
+  if (new_status == cryptauth::SecureChannel::Status::CONNECTING) {
+    // BleConnectionManager already broadcasts "disconnected => connecting"
+    // status updates when a connection attempt begins, so there is no need to
+    // handle this case.
+    return;
+  }
+
+  if (new_status == cryptauth::SecureChannel::Status::DISCONNECTED) {
+    secure_channel_->RemoveObserver(this);
+    secure_channel_.reset();
+
+    manager_->OnSecureChannelStatusChanged(
+        remote_device_, old_status,
+        cryptauth::SecureChannel::Status::DISCONNECTED);
+    return;

[Ryan Hansberry, 2017/02/16 19:29:35]

returning early is unnecessary. let it fall through to the end of the method to
one call of manager_->OnSecureChannelStatusChanged

[Kyle Horimoto, 2017/02/17 01:06:52]

Done.

+  }
+
+  manager_->OnSecureChannelStatusChanged(remote_device_, old_status,
+                                         new_status);
+}
+
+void BleConnectionManager::ConnectionMetadata::OnMessageReceived(
+    cryptauth::SecureChannel* secure_channel,
+    const std::string& feature,
+    const std::string& payload) {
+  DCHECK(secure_channel_.get() == secure_channel);
+  if (feature != std::string(kTetherFeature)) {
+    // If the message received was not a tether feature, ignore it.
+    return;
+  }
+
+  manager_->SendMessageReceivedEvent(remote_device_, payload);
+}
+
+std::unique_ptr<base::Timer> BleConnectionManager::TimerFactory::CreateTimer() {
+  return base::MakeUnique<base::OneShotTimer>();
+}
+
+BleConnectionManager::BleConnectionManager(
+    std::unique_ptr<Delegate> delegate,
+    scoped_refptr<device::BluetoothAdapter> adapter,
+    const LocalDeviceDataProvider* local_device_data_provider,
+    const cryptauth::RemoteBeaconSeedFetcher* remote_beacon_seed_fetcher,
+    cryptauth::BluetoothThrottler* bluetooth_throttler)
+    : BleConnectionManager(
+          std::move(delegate),
+          adapter,
+          // TODO(khorimoto): Inject |adapter| into |BleScanner|.
+          base::MakeUnique<BleScanner>(local_device_data_provider),
+          base::MakeUnique<BleAdvertiser>(adapter,
+                                          local_device_data_provider,
+                                          remote_beacon_seed_fetcher),
+          base::MakeUnique<BleAdvertisementDeviceQueue>(),
+          base::WrapUnique<TimerFactory>(new TimerFactory()),
+          bluetooth_throttler) {}
+
+BleConnectionManager::BleConnectionManager(
+    std::unique_ptr<Delegate> delegate,
+    scoped_refptr<device::BluetoothAdapter> adapter,
+    std::unique_ptr<BleScanner> ble_scanner,
+    std::unique_ptr<BleAdvertiser> ble_advertiser,
+    std::unique_ptr<BleAdvertisementDeviceQueue> device_queue,
+    std::unique_ptr<TimerFactory> timer_factory,
+    cryptauth::BluetoothThrottler* bluetooth_throttler)
+    : delegate_(std::move(delegate)),
+      adapter_(adapter),
+      ble_scanner_(std::move(ble_scanner)),
+      ble_advertiser_(std::move(ble_advertiser)),
+      device_queue_(std::move(device_queue)),
+      timer_factory_(std::move(timer_factory)),
+      bluetooth_throttler_(bluetooth_throttler),
+      weak_ptr_factory_(this) {
+  ble_scanner_->AddObserver(this);
+}
+
+BleConnectionManager::~BleConnectionManager() {
+  ble_scanner_->RemoveObserver(this);
+}
+
+void BleConnectionManager::RegisterRemoteDevice(
+    const cryptauth::RemoteDevice& remote_device,
+    const MessageType& connection_reason) {
+  PA_LOG(INFO) << "Registering device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs() << " for reason "
+               << MessageTypeToString(connection_reason);
+
+  std::shared_ptr<ConnectionMetadata> data =
+      GetConnectionMetadata(remote_device);
+  if (!data) {
+    data = AddMetadataForDevice(remote_device);
+  }
+
+  data->RegisterConnectionReason(connection_reason);
+  UpdateConnectionAttempts();
+}
+
+void BleConnectionManager::UnregisterRemoteDevice(
+    const cryptauth::RemoteDevice& remote_device,
+    const MessageType& connection_reason) {
+  PA_LOG(INFO) << "Unregistering device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs() << " for reason "
+               << MessageTypeToString(connection_reason);
+
+  std::shared_ptr<ConnectionMetadata> data =
+      GetConnectionMetadata(remote_device);
+  if (!data) {
+    // If the device was not registered, there is nothing to do.
+    return;
+  }
+
+  data->UnregisterConnectionReason(connection_reason);
+  if (!data->HasReasonForConnection()) {
+    cryptauth::SecureChannel::Status status_before_disconnect =
+        data->GetStatus();
+    device_to_metadata_map_.erase(remote_device);
+    if (status_before_disconnect ==
+        cryptauth::SecureChannel::Status::CONNECTING) {
+      StopConnectionAttemptAndMoveToEndOfQueue(remote_device);
+    }
+    if (status_before_disconnect !=
+        cryptauth::SecureChannel::Status::DISCONNECTED) {
+      // Send a status update for the disconnection.
+      SendSecureChannelStatusChangeEvent(
+          remote_device, status_before_disconnect,
+          cryptauth::SecureChannel::Status::DISCONNECTED);
+    }
+  }
+
+  UpdateConnectionAttempts();
+}
+
+void BleConnectionManager::SendMessage(
+    const cryptauth::RemoteDevice& remote_device,
+    const std::string& message) {
+  std::shared_ptr<ConnectionMetadata> data =
+      GetConnectionMetadata(remote_device);
+  if (!data ||
+      data->GetStatus() != cryptauth::SecureChannel::Status::AUTHENTICATED) {
+    PA_LOG(ERROR) << "Attempted to send a message to device with ID "
+                  << remote_device.GetTruncatedDeviceIdForLogs() << ". "
+                  << "Message: \"" << message << "\"";
+    return;
+  }
+
+  PA_LOG(INFO) << "Sending message to device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs() << ". "
+               << "Message: \"" << message << "\"";
+  data->SendMessage(message);
+}
+
+void BleConnectionManager::AddObserver(Observer* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void BleConnectionManager::RemoveObserver(Observer* observer) {
+  observer_list_.RemoveObserver(observer);
+}
+
+void BleConnectionManager::OnReceivedAdvertisementFromDevice(
+    const std::string& device_address,
+    cryptauth::RemoteDevice remote_device) {
+  std::shared_ptr<ConnectionMetadata> data =
+      GetConnectionMetadata(remote_device);
+  if (!data) {
+    // If an advertisement  is received from a device that is not registered,
+    // ignore it.
+    PA_LOG(WARNING) << "Received an advertisement from a device which is not "
+                    << "registered. Bluetooth address: " << device_address
+                    << ", Remote Device ID: " << remote_device.GetDeviceId();
+    return;
+  }
+
+  PA_LOG(INFO) << "Received advertisement from device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs() << ". "
+               << "Starting authentication handshake to that device.";
+
+  // Create a connection to that device.
+  std::unique_ptr<cryptauth::Connection> connection =
+      cryptauth::weave::BluetoothLowEnergyWeaveClientConnection::Factory::
+          NewInstance(remote_device, device_address, adapter_,
+                      device::BluetoothUUID(std::string(kGattServerUuid)),
+                      bluetooth_throttler_);
+  PA_LOG(INFO) << "3 " << connection.get();

[Ryan Hansberry, 2017/02/16 19:29:35]

Are these leftover debug logs?

[Kyle Horimoto, 2017/02/17 01:06:52]

Yes; removed.

+  std::unique_ptr<cryptauth::SecureChannel> secure_channel =
+      cryptauth::SecureChannel::Factory::NewInstance(
+          std::move(connection), delegate_->CreateSecureChannelDelegate());
+  PA_LOG(INFO) << "4 " << secure_channel.get();
+  data->SetSecureChannel(std::move(secure_channel));
+
+  // Stop trying to connect to that device, since a connection already exists.
+  StopConnectionAttemptAndMoveToEndOfQueue(remote_device);
+  UpdateConnectionAttempts();
+}
+
+std::shared_ptr<BleConnectionManager::ConnectionMetadata>
+BleConnectionManager::GetConnectionMetadata(
+    const cryptauth::RemoteDevice& remote_device) {
+  const auto map_iter = device_to_metadata_map_.find(remote_device);
+  if (map_iter == device_to_metadata_map_.end()) {
+    return nullptr;
+  }
+
+  return map_iter->second;
+}
+
+std::shared_ptr<BleConnectionManager::ConnectionMetadata>
+BleConnectionManager::AddMetadataForDevice(
+    const cryptauth::RemoteDevice& remote_device) {
+  std::shared_ptr<ConnectionMetadata> existing_data =
+      GetConnectionMetadata(remote_device);
+  if (existing_data) {
+    return existing_data;
+  }
+
+  std::unique_ptr<base::Timer> timer = timer_factory_->CreateTimer();
+  device_to_metadata_map_.insert(
+      std::pair<cryptauth::RemoteDevice, std::shared_ptr<ConnectionMetadata>>(
+          remote_device,
+          std::shared_ptr<ConnectionMetadata>(
+              new ConnectionMetadata(remote_device, std::move(timer),
+                                     weak_ptr_factory_.GetWeakPtr()))));
+  return device_to_metadata_map_.at(remote_device);
+}
+
+void BleConnectionManager::UpdateConnectionAttempts() {
+  UpdateAdvertisementQueue();
+
+  std::vector<cryptauth::RemoteDevice> should_advertise_to =
+      device_queue_->GetDevicesToWhichToAdvertise();
+  DCHECK(should_advertise_to.size() <=
+         static_cast<size_t>(kMaxConcurrentAdvertisements));
+
+  for (const auto& remote_device : should_advertise_to) {
+    std::shared_ptr<ConnectionMetadata> associated_data =
+        GetConnectionMetadata(remote_device);
+    if (associated_data->GetStatus() !=
+        cryptauth::SecureChannel::Status::CONNECTING) {
+      // If there is no active attempt to connect to a device at the front of
+      // the queue, start a connection attempt.
+      StartConnectionAttempt(remote_device);
+    }
+  }
+}
+
+void BleConnectionManager::UpdateAdvertisementQueue() {
+  std::vector<cryptauth::RemoteDevice> devices_for_queue;
+  for (const auto& map_entry : device_to_metadata_map_) {
+    if (map_entry.second->HasEstablishedConnection()) {
+      // If there is already an active connection to the device, there is no
+      // need to advertise to the device to bootstrap a connection.
+      continue;
+    }
+
+    devices_for_queue.push_back(map_entry.first);
+  }
+
+  device_queue_->SetDevices(devices_for_queue);
+}
+
+void BleConnectionManager::StartConnectionAttempt(
+    const cryptauth::RemoteDevice& remote_device) {
+  std::shared_ptr<ConnectionMetadata> data =
+      GetConnectionMetadata(remote_device);
+  DCHECK(data);
+
+  PA_LOG(INFO) << "Starting connection attempt to device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs();
+
+  // Send a "disconnected => connecting" update to alert clients that a
+  // connection attempt for |remote_device| is underway.
+  SendSecureChannelStatusChangeEvent(
+      remote_device, cryptauth::SecureChannel::Status::DISCONNECTED,
+      cryptauth::SecureChannel::Status::CONNECTING);
+
+  bool success = ble_scanner_->RegisterScanFilterForDevice(remote_device) &&
+                 ble_advertiser_->StartAdvertisingToDevice(remote_device);
+
+  // Start a timer; if a connection is unable to be created before the timer
+  // fires, a timeout occurs. Note that if this class is unable to start both
+  // the scanner and advertiser successfully (i.e., |success| is |false|), a
+  // short error timeout is set instead of the full timeout, which has the
+  // effect of quickly sending out "disconnected => connecting => disconnecting"
+  // status updates. A short timeout is used here instead of a special case in
+  // order to route all connection failures through the same code path.
+  data->StartConnectionAttemptTimer(/* use_short_error_timeout */ !success);

[Ryan Hansberry, 2017/02/16 19:29:35]

The param comment should come after the param.

[Kyle Horimoto, 2017/02/17 01:06:52]

Done.

+}
+
+void BleConnectionManager::StopConnectionAttemptAndMoveToEndOfQueue(
+    const cryptauth::RemoteDevice& remote_device) {
+  PA_LOG(INFO) << "Stopping connection attempt to device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs();
+
+  ble_scanner_->UnregisterScanFilterForDevice(remote_device);
+  ble_advertiser_->StopAdvertisingToDevice(remote_device);
+
+  device_queue_->MoveDeviceToEnd(remote_device.GetDeviceId());
+}
+
+void BleConnectionManager::OnConnectionAttemptTimeout(
+    const cryptauth::RemoteDevice& remote_device) {
+  PA_LOG(INFO) << "Connection attempt timed out for device with ID "
+               << remote_device.GetTruncatedDeviceIdForLogs();
+
+  StopConnectionAttemptAndMoveToEndOfQueue(remote_device);
+
+  // Send a "connecting => disconnected" update to alert clients that a
+  // connection attempt for |remote_device| has failed.
+  SendSecureChannelStatusChangeEvent(
+      remote_device, cryptauth::SecureChannel::Status::CONNECTING,
+      cryptauth::SecureChannel::Status::DISCONNECTED);
+
+  UpdateConnectionAttempts();
+}
+
+void BleConnectionManager::OnSecureChannelStatusChanged(
+    const cryptauth::RemoteDevice& remote_device,
+    const cryptauth::SecureChannel::Status& old_status,
+    const cryptauth::SecureChannel::Status& new_status) {
+  SendSecureChannelStatusChangeEvent(remote_device, old_status, new_status);
+  UpdateConnectionAttempts();
+}
+
+void BleConnectionManager::SendMessageReceivedEvent(
+    const cryptauth::RemoteDevice& remote_device,
+    const std::string& payload) {
+  PA_LOG(INFO) << "Broadcasting message received event: "
+               << "Device ID \"" << remote_device.GetTruncatedDeviceIdForLogs()
+               << "\" received message \"" << payload << "\".";
+  for (auto& observer : observer_list_) {
+    observer.OnMessageReceived(remote_device, payload);
+  }
+}
+
+void BleConnectionManager::SendSecureChannelStatusChangeEvent(
+    const cryptauth::RemoteDevice& remote_device,
+    const cryptauth::SecureChannel::Status& old_status,
+    const cryptauth::SecureChannel::Status& new_status) {
+  PA_LOG(INFO) << "Broadcasting status change event: "
+               << "Device ID \"" << remote_device.GetTruncatedDeviceIdForLogs()
+               << "\": " << cryptauth::SecureChannel::StatusToString(old_status)
+               << " => "
+               << cryptauth::SecureChannel::StatusToString(new_status);
+  for (auto& observer : observer_list_) {
+    observer.OnSecureChannelStatusChanged(remote_device, old_status,
+                                          new_status);
+  }
+}
+
+}  // namespace tether
+
+}  // namespace chromeos