1 //
2 // Copyright 2016 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at:
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16
17 #include "service/low_energy_scanner.h"
18
19 #include <base/bind.h>
20 #include <base/logging.h>
21
22 #include "service/adapter.h"
23 #include "service/logging_helpers.h"
24 #include "stack/include/bt_types.h"
25 #include "stack/include/hcidefs.h"
26
27 using std::lock_guard;
28 using std::mutex;
29
30 namespace bluetooth {
31
32 namespace {
33
34 // 31 + 31 for advertising data and scan response. This is the maximum length
35 // TODO(armansito): Fix the HAL to return a concatenated blob that contains the
36 // true length of each field and also provide a length parameter so that we
37 // can support advertising length extensions in the future.
38 const size_t kScanRecordLength = 62;
39
40 // Returns the length of the given scan record array. We have to calculate this
41 // based on the maximum possible data length and the TLV data. See TODO above
42 // |kScanRecordLength|.
GetScanRecordLength(std::vector<uint8_t> bytes)43 size_t GetScanRecordLength(std::vector<uint8_t> bytes) {
44 for (size_t i = 0, field_len = 0; i < kScanRecordLength;
45 i += (field_len + 1)) {
46 field_len = bytes[i];
47
48 // Assert here that the data returned from the stack is correctly formatted
49 // in TLV form and that the length of the current field won't exceed the
50 // total data length.
51 CHECK(i + field_len < kScanRecordLength);
52
53 // If the field length is zero and we haven't reached the maximum length,
54 // then we have found the length, as the stack will pad the data with zeros
55 // accordingly.
56 if (field_len == 0) return i;
57 }
58
59 // We have reached the end.
60 return kScanRecordLength;
61 }
62
63 } // namespace
64
65 // LowEnergyScanner implementation
66 // ========================================================
67
LowEnergyScanner(Adapter & adapter,const Uuid & uuid,int scanner_id)68 LowEnergyScanner::LowEnergyScanner(Adapter& adapter, const Uuid& uuid,
69 int scanner_id)
70 : adapter_(adapter),
71 app_identifier_(uuid),
72 scanner_id_(scanner_id),
73 scan_started_(false),
74 delegate_(nullptr) {}
75
~LowEnergyScanner()76 LowEnergyScanner::~LowEnergyScanner() {
77 // Automatically unregister the scanner.
78 VLOG(1) << "LowEnergyScanner unregistering scanner: " << scanner_id_;
79
80 // Unregister as observer so we no longer receive any callbacks.
81 hal::BluetoothGattInterface::Get()->RemoveScannerObserver(this);
82
83 hal::BluetoothGattInterface::Get()->GetScannerHALInterface()->Unregister(
84 scanner_id_);
85
86 // Stop any scans started by this client.
87 if (scan_started_.load()) StopScan();
88 }
89
SetDelegate(Delegate * delegate)90 void LowEnergyScanner::SetDelegate(Delegate* delegate) {
91 lock_guard<mutex> lock(delegate_mutex_);
92 delegate_ = delegate;
93 }
94
StartScan(const ScanSettings & settings,const std::vector<ScanFilter> & filters)95 bool LowEnergyScanner::StartScan(const ScanSettings& settings,
96 const std::vector<ScanFilter>& filters) {
97 VLOG(2) << __func__;
98
99 // Cannot start a scan if the adapter is not enabled.
100 if (!adapter_.IsEnabled()) {
101 LOG(ERROR) << "Cannot scan while Bluetooth is disabled";
102 return false;
103 }
104
105 // TODO(jpawlowski): Push settings and filtering logic below the HAL.
106 bt_status_t status =
107 hal::BluetoothGattInterface::Get()->StartScan(scanner_id_);
108 if (status != BT_STATUS_SUCCESS) {
109 LOG(ERROR) << "Failed to initiate scanning for client: " << scanner_id_;
110 return false;
111 }
112
113 scan_started_ = true;
114 return true;
115 }
116
StopScan()117 bool LowEnergyScanner::StopScan() {
118 VLOG(2) << __func__;
119
120 // TODO(armansito): We don't support batch scanning yet so call
121 // StopRegularScanForClient directly. In the future we will need to
122 // conditionally call a batch scan API here.
123 bt_status_t status =
124 hal::BluetoothGattInterface::Get()->StopScan(scanner_id_);
125 if (status != BT_STATUS_SUCCESS) {
126 LOG(ERROR) << "Failed to stop scan for client: " << scanner_id_;
127 return false;
128 }
129
130 scan_started_ = false;
131 return true;
132 }
133
GetAppIdentifier() const134 const Uuid& LowEnergyScanner::GetAppIdentifier() const {
135 return app_identifier_;
136 }
137
GetInstanceId() const138 int LowEnergyScanner::GetInstanceId() const { return scanner_id_; }
139
ScanResultCallback(hal::BluetoothGattInterface * gatt_iface,const RawAddress & bda,int rssi,std::vector<uint8_t> adv_data)140 void LowEnergyScanner::ScanResultCallback(
141 hal::BluetoothGattInterface* gatt_iface, const RawAddress& bda, int rssi,
142 std::vector<uint8_t> adv_data) {
143 // Ignore scan results if this client didn't start a scan.
144 if (!scan_started_.load()) return;
145
146 lock_guard<mutex> lock(delegate_mutex_);
147 if (!delegate_) return;
148
149 // TODO(armansito): Apply software filters here.
150
151 size_t record_len = GetScanRecordLength(adv_data);
152 std::vector<uint8_t> scan_record(adv_data.begin(),
153 adv_data.begin() + record_len);
154
155 ScanResult result(BtAddrString(&bda), scan_record, rssi);
156
157 delegate_->OnScanResult(this, result);
158 }
159
160 // LowEnergyScannerFactory implementation
161 // ========================================================
162
LowEnergyScannerFactory(Adapter & adapter)163 LowEnergyScannerFactory::LowEnergyScannerFactory(Adapter& adapter)
164 : adapter_(adapter) {
165 hal::BluetoothGattInterface::Get()->AddScannerObserver(this);
166 }
167
~LowEnergyScannerFactory()168 LowEnergyScannerFactory::~LowEnergyScannerFactory() {
169 hal::BluetoothGattInterface::Get()->RemoveScannerObserver(this);
170 }
171
RegisterInstance(const Uuid & uuid,const RegisterCallback & callback)172 bool LowEnergyScannerFactory::RegisterInstance(
173 const Uuid& uuid, const RegisterCallback& callback) {
174 VLOG(1) << __func__ << " - Uuid: " << uuid.ToString();
175 lock_guard<mutex> lock(pending_calls_lock_);
176
177 if (pending_calls_.find(uuid) != pending_calls_.end()) {
178 LOG(ERROR) << "Low-Energy scanner with given Uuid already registered - "
179 << "Uuid: " << uuid.ToString();
180 return false;
181 }
182
183 BleScannerInterface* hal_iface =
184 hal::BluetoothGattInterface::Get()->GetScannerHALInterface();
185
186 hal_iface->RegisterScanner(
187 base::Bind(&LowEnergyScannerFactory::RegisterScannerCallback,
188 base::Unretained(this), callback, uuid));
189
190 pending_calls_.insert(uuid);
191
192 return true;
193 }
194
RegisterScannerCallback(const RegisterCallback & callback,const Uuid & app_uuid,uint8_t scanner_id,uint8_t status)195 void LowEnergyScannerFactory::RegisterScannerCallback(
196 const RegisterCallback& callback, const Uuid& app_uuid, uint8_t scanner_id,
197 uint8_t status) {
198 Uuid uuid(app_uuid);
199
200 VLOG(1) << __func__ << " - Uuid: " << uuid.ToString();
201 lock_guard<mutex> lock(pending_calls_lock_);
202
203 auto iter = pending_calls_.find(uuid);
204 if (iter == pending_calls_.end()) {
205 VLOG(1) << "Ignoring callback for unknown app_id: " << uuid.ToString();
206 return;
207 }
208
209 // No need to construct a scanner if the call wasn't successful.
210 std::unique_ptr<LowEnergyScanner> scanner;
211 BLEStatus result = BLE_STATUS_FAILURE;
212 if (status == BT_STATUS_SUCCESS) {
213 scanner.reset(new LowEnergyScanner(adapter_, uuid, scanner_id));
214
215 hal::BluetoothGattInterface::Get()->AddScannerObserver(scanner.get());
216
217 result = BLE_STATUS_SUCCESS;
218 }
219
220 // Notify the result via the result callback.
221 callback(result, app_uuid, std::move(scanner));
222
223 pending_calls_.erase(iter);
224 }
225
226 } // namespace bluetooth
227