service/low_energy_client.cc

//
//  Copyright (C) 2015 Google, Inc.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at:
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

#include "service/low_energy_client.h"

#include <base/logging.h>

#include "service/adapter.h"
#include "service/common/bluetooth/util/address_helper.h"
#include "service/logging_helpers.h"
#include "stack/include/bt_types.h"
#include "stack/include/hcidefs.h"

using std::lock_guard;
using std::mutex;

namespace bluetooth {

namespace {

// 31 + 31 for advertising data and scan response. This is the maximum length
// TODO(armansito): Fix the HAL to return a concatenated blob that contains the
// true length of each field and also provide a length parameter so that we
// can support advertising length extensions in the future.
const size_t kScanRecordLength = 62;

// Returns the length of the given scan record array. We have to calculate this
// based on the maximum possible data length and the TLV data. See TODO above
// |kScanRecordLength|.
size_t GetScanRecordLength(vector<uint8_t> bytes) {
  for (size_t i = 0, field_len = 0; i < kScanRecordLength;
       i += (field_len + 1)) {
    field_len = bytes[i];

    // Assert here that the data returned from the stack is correctly formatted
    // in TLV form and that the length of the current field won't exceed the
    // total data length.
    CHECK(i + field_len < kScanRecordLength);

    // If the field length is zero and we haven't reached the maximum length,
    // then we have found the length, as the stack will pad the data with zeros
    // accordingly.
    if (field_len == 0)
      return i;
  }

  // We have reached the end.
  return kScanRecordLength;
}

}  // namespace

// LowEnergyClient implementation
// ========================================================

LowEnergyClient::LowEnergyClient(
    Adapter& adapter, const UUID& uuid, int client_id)
    : adapter_(adapter),
      app_identifier_(uuid),
      client_id_(client_id),
      scan_started_(false),
      delegate_(nullptr) {
}

LowEnergyClient::~LowEnergyClient() {
  // Automatically unregister the client.
  VLOG(1) << "LowEnergyClient unregistering client: " << client_id_;

  // Unregister as observer so we no longer receive any callbacks.
  hal::BluetoothGattInterface::Get()->RemoveClientObserver(this);

  hal::BluetoothGattInterface::Get()->
      GetClientHALInterface()->unregister_client(client_id_);

  // Stop any scans started by this client.
  if (scan_started_.load())
    StopScan();
}

bool LowEnergyClient::Connect(const std::string& address, bool is_direct) {
  VLOG(2) << __func__ << "Address: " << address << " is_direct: " << is_direct;

  bt_bdaddr_t bda;
  util::BdAddrFromString(address, &bda);

  bt_status_t status = hal::BluetoothGattInterface::Get()->
      GetClientHALInterface()->connect(client_id_, &bda, is_direct,
                                       BT_TRANSPORT_LE);
  if (status != BT_STATUS_SUCCESS) {
    LOG(ERROR) << "HAL call to connect failed";
    return false;
  }

  return true;
}

bool LowEnergyClient::Disconnect(const std::string& address) {
  VLOG(2) << __func__ << "Address: " << address;

  bt_bdaddr_t bda;
  util::BdAddrFromString(address, &bda);

  std::map<const bt_bdaddr_t, int>::iterator conn_id;
  {
    lock_guard<mutex> lock(connection_fields_lock_);
    conn_id = connection_ids_.find(bda);
    if (conn_id == connection_ids_.end()) {
      LOG(WARNING) << "Can't disconnect, no existing connection to " << address;
      return false;
    }
  }

  bt_status_t status = hal::BluetoothGattInterface::Get()->
      GetClientHALInterface()->disconnect(client_id_, &bda, conn_id->second);
  if (status != BT_STATUS_SUCCESS) {
    LOG(ERROR) << "HAL call to disconnect failed";
    return false;
  }

  return true;
}

bool LowEnergyClient::SetMtu(const std::string& address, int mtu) {
  VLOG(2) << __func__ << "Address: " << address
          << " MTU: " << mtu;

  bt_bdaddr_t bda;
  util::BdAddrFromString(address, &bda);

  std::map<const bt_bdaddr_t, int>::iterator conn_id;
  {
    lock_guard<mutex> lock(connection_fields_lock_);
    conn_id = connection_ids_.find(bda);
    if (conn_id == connection_ids_.end()) {
      LOG(WARNING) << "Can't set MTU, no existing connection to " << address;
      return false;
    }
  }

  bt_status_t status = hal::BluetoothGattInterface::Get()->
      GetClientHALInterface()->configure_mtu(conn_id->second, mtu);
  if (status != BT_STATUS_SUCCESS) {
    LOG(ERROR) << "HAL call to set MTU failed";
    return false;
  }

  return true;
}

void LowEnergyClient::SetDelegate(Delegate* delegate) {
  lock_guard<mutex> lock(delegate_mutex_);
  delegate_ = delegate;
}

bool LowEnergyClient::StartScan(const ScanSettings& settings,
                                const std::vector<ScanFilter>& filters) {
  VLOG(2) << __func__;

  // Cannot start a scan if the adapter is not enabled.
  if (!adapter_.IsEnabled()) {
    LOG(ERROR) << "Cannot scan while Bluetooth is disabled";
    return false;
  }

  // TODO(jpawlowski): Push settings and filtering logic below the HAL.
  bt_status_t status = hal::BluetoothGattInterface::Get()->
      StartScan(client_id_);
  if (status != BT_STATUS_SUCCESS) {
    LOG(ERROR) << "Failed to initiate scanning for client: " << client_id_;
    return false;
  }

  scan_started_ = true;
  return true;
}

bool LowEnergyClient::StopScan() {
  VLOG(2) << __func__;

  // TODO(armansito): We don't support batch scanning yet so call
  // StopRegularScanForClient directly. In the future we will need to
  // conditionally call a batch scan API here.
  bt_status_t status = hal::BluetoothGattInterface::Get()->
      StopScan(client_id_);
  if (status != BT_STATUS_SUCCESS) {
    LOG(ERROR) << "Failed to stop scan for client: " << client_id_;
    return false;
  }

  scan_started_ = false;
  return true;
}

const UUID& LowEnergyClient::GetAppIdentifier() const {
  return app_identifier_;
}

int LowEnergyClient::GetInstanceId() const {
  return client_id_;
}

void LowEnergyClient::ScanResultCallback(
    hal::BluetoothGattInterface* gatt_iface,
    const bt_bdaddr_t& bda, int rssi, vector<uint8_t> adv_data) {
  // Ignore scan results if this client didn't start a scan.
  if (!scan_started_.load())
    return;

  lock_guard<mutex> lock(delegate_mutex_);
  if (!delegate_)
    return;

  // TODO(armansito): Apply software filters here.

  size_t record_len = GetScanRecordLength(adv_data);
  std::vector<uint8_t> scan_record(adv_data.begin(), adv_data.begin() + record_len);

  ScanResult result(BtAddrString(&bda), scan_record, rssi);

  delegate_->OnScanResult(this, result);
}

void LowEnergyClient::ConnectCallback(
      hal::BluetoothGattInterface* gatt_iface, int conn_id, int status,
      int client_id, const bt_bdaddr_t& bda) {
  if (client_id != client_id_)
    return;

  VLOG(1) << __func__ << "client_id: " << client_id << " status: " << status;

  {
    lock_guard<mutex> lock(connection_fields_lock_);
    auto success = connection_ids_.emplace(bda, conn_id);
    if (!success.second) {
      LOG(ERROR) << __func__ << " Insertion into connection_ids_ failed!";
    }
  }

  if (delegate_)
    delegate_->OnConnectionState(this, status, BtAddrString(&bda).c_str(),
                                 true);
}

void LowEnergyClient::DisconnectCallback(
      hal::BluetoothGattInterface* gatt_iface, int conn_id, int status,
      int client_id, const bt_bdaddr_t& bda) {
  if (client_id != client_id_)
    return;

  VLOG(1) << __func__ << " client_id: " << client_id << " status: " << status;
  {
    lock_guard<mutex> lock(connection_fields_lock_);
    if (!connection_ids_.erase(bda)) {
      LOG(ERROR) << __func__ << " Erasing from connection_ids_ failed!";
    }
  }

  if (delegate_)
    delegate_->OnConnectionState(this, status, BtAddrString(&bda).c_str(),
                                 false);
}

void LowEnergyClient::MtuChangedCallback(
      hal::BluetoothGattInterface* gatt_iface, int conn_id, int status,
      int mtu) {
  VLOG(1) << __func__ << " conn_id: " << conn_id << " status: " << status
          << " mtu: " << mtu;

  const bt_bdaddr_t *bda = nullptr;
  {
    lock_guard<mutex> lock(connection_fields_lock_);
    for (auto& connection: connection_ids_) {
      if (connection.second == conn_id) {
        bda = &connection.first;
        break;
      }
    }
  }

  if (!bda)
    return;

  const char *addr = BtAddrString(bda).c_str();
  if (delegate_)
    delegate_->OnMtuChanged(this, status, addr, mtu);
}

// LowEnergyClientFactory implementation
// ========================================================

LowEnergyClientFactory::LowEnergyClientFactory(Adapter& adapter)
    : adapter_(adapter) {
  hal::BluetoothGattInterface::Get()->AddClientObserver(this);
}

LowEnergyClientFactory::~LowEnergyClientFactory() {
  hal::BluetoothGattInterface::Get()->RemoveClientObserver(this);
}

bool LowEnergyClientFactory::RegisterInstance(
    const UUID& uuid,
    const RegisterCallback& callback) {
  VLOG(1) << __func__ << " - UUID: " << uuid.ToString();
  lock_guard<mutex> lock(pending_calls_lock_);

  if (pending_calls_.find(uuid) != pending_calls_.end()) {
    LOG(ERROR) << "Low-Energy client with given UUID already registered - "
               << "UUID: " << uuid.ToString();
    return false;
  }

  const btgatt_client_interface_t* hal_iface =
      hal::BluetoothGattInterface::Get()->GetClientHALInterface();
  bt_uuid_t app_uuid = uuid.GetBlueDroid();

  if (hal_iface->register_client(&app_uuid) != BT_STATUS_SUCCESS)
    return false;

  pending_calls_[uuid] = callback;

  return true;
}

void LowEnergyClientFactory::RegisterClientCallback(
    hal::BluetoothGattInterface* gatt_iface,
    int status, int client_id,
    const bt_uuid_t& app_uuid) {
  UUID uuid(app_uuid);

  VLOG(1) << __func__ << " - UUID: " << uuid.ToString();
  lock_guard<mutex> lock(pending_calls_lock_);

  auto iter = pending_calls_.find(uuid);
  if (iter == pending_calls_.end()) {
    VLOG(1) << "Ignoring callback for unknown app_id: " << uuid.ToString();
    return;
  }

  // No need to construct a client if the call wasn't successful.
  std::unique_ptr<LowEnergyClient> client;
  BLEStatus result = BLE_STATUS_FAILURE;
  if (status == BT_STATUS_SUCCESS) {
    client.reset(new LowEnergyClient(adapter_, uuid, client_id));

    gatt_iface->AddClientObserver(client.get());

    result = BLE_STATUS_SUCCESS;
  }

  // Notify the result via the result callback.
  iter->second(result, uuid, std::move(client));

  pending_calls_.erase(iter);
}

}  // namespace bluetooth