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//
// Copyright 2016 The Android Open Source Project
//
// 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_scanner.h"
#include "service/adapter.h"
#include "service/logging_helpers.h"
#include "stack/include/bt_types.h"
#include "stack/include/hcidefs.h"
#include <base/bind.h>
#include <base/callback.h>
#include <base/logging.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(std::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
// LowEnergyScanner implementation
// ========================================================
LowEnergyScanner::LowEnergyScanner(Adapter& adapter, const Uuid& uuid,
int scanner_id)
: adapter_(adapter),
app_identifier_(uuid),
scanner_id_(scanner_id),
scan_started_(false),
delegate_(nullptr) {}
LowEnergyScanner::~LowEnergyScanner() {
// Automatically unregister the scanner.
VLOG(1) << "LowEnergyScanner unregistering scanner: " << scanner_id_;
// Unregister as observer so we no longer receive any callbacks.
hal::BluetoothGattInterface::Get()->RemoveScannerObserver(this);
hal::BluetoothGattInterface::Get()->GetScannerHALInterface()->Unregister(
scanner_id_);
// Stop any scans started by this client.
if (scan_started_.load()) StopScan();
}
void LowEnergyScanner::SetDelegate(Delegate* delegate) {
lock_guard<mutex> lock(delegate_mutex_);
delegate_ = delegate;
}
bool LowEnergyScanner::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(scanner_id_);
if (status != BT_STATUS_SUCCESS) {
LOG(ERROR) << "Failed to initiate scanning for client: " << scanner_id_;
return false;
}
scan_started_ = true;
return true;
}
bool LowEnergyScanner::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(scanner_id_);
if (status != BT_STATUS_SUCCESS) {
LOG(ERROR) << "Failed to stop scan for client: " << scanner_id_;
return false;
}
scan_started_ = false;
return true;
}
const Uuid& LowEnergyScanner::GetAppIdentifier() const {
return app_identifier_;
}
int LowEnergyScanner::GetInstanceId() const { return scanner_id_; }
void LowEnergyScanner::ScanResultCallback(
hal::BluetoothGattInterface* gatt_iface, const RawAddress& bda, int rssi,
std::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);
}
// LowEnergyScannerFactory implementation
// ========================================================
LowEnergyScannerFactory::LowEnergyScannerFactory(Adapter& adapter)
: adapter_(adapter) {
hal::BluetoothGattInterface::Get()->AddScannerObserver(this);
}
LowEnergyScannerFactory::~LowEnergyScannerFactory() {
hal::BluetoothGattInterface::Get()->RemoveScannerObserver(this);
}
bool LowEnergyScannerFactory::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 scanner with given Uuid already registered - "
<< "Uuid: " << uuid.ToString();
return false;
}
BleScannerInterface* hal_iface =
hal::BluetoothGattInterface::Get()->GetScannerHALInterface();
hal_iface->RegisterScanner(
base::Bind(&LowEnergyScannerFactory::RegisterScannerCallback,
base::Unretained(this), callback, uuid));
pending_calls_.insert(uuid);
return true;
}
void LowEnergyScannerFactory::RegisterScannerCallback(
const RegisterCallback& callback, const Uuid& app_uuid, uint8_t scanner_id,
uint8_t status) {
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 scanner if the call wasn't successful.
std::unique_ptr<LowEnergyScanner> scanner;
BLEStatus result = BLE_STATUS_FAILURE;
if (status == BT_STATUS_SUCCESS) {
scanner.reset(new LowEnergyScanner(adapter_, uuid, scanner_id));
hal::BluetoothGattInterface::Get()->AddScannerObserver(scanner.get());
result = BLE_STATUS_SUCCESS;
}
// Notify the result via the result callback.
callback(result, app_uuid, std::move(scanner));
pending_calls_.erase(iter);
}
} // namespace bluetooth