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// Copyright 2020 Google LLC
// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <memory>
#include <string>
#include "absl/container/flat_hash_map.h"
#include "absl/container/flat_hash_set.h"
#include "absl/strings/escaping.h"
#include "absl/synchronization/mutex.h"
#include "platform/api/ble.h"
#include "platform/base/byte_array.h"
#include "platform/base/input_stream.h"
#include "platform/base/output_stream.h"
#include "platform/impl/g3/bluetooth_adapter.h"
#include "platform/impl/g3/bluetooth_classic.h"
#include "platform/impl/g3/multi_thread_executor.h"
#include "platform/impl/g3/pipe.h"
namespace location {
namespace nearby {
namespace g3 {
class BleMedium;
class BleSocket : public api::BleSocket {
BleSocket() = default;
explicit BleSocket(BlePeripheral* peripheral) : peripheral_(peripheral) {}
~BleSocket() override;
// Connect to another BleSocket, to form a functional low-level channel.
// from this point on, and until Close is called, connection exists.
void Connect(BleSocket& other) ABSL_LOCKS_EXCLUDED(mutex_);
// Returns the InputStream of this connected BleSocket.
InputStream& GetInputStream() override ABSL_LOCKS_EXCLUDED(mutex_);
// Returns the OutputStream of this connected BleSocket.
// This stream is for local side to write.
OutputStream& GetOutputStream() override ABSL_LOCKS_EXCLUDED(mutex_);
// Returns address of a remote BleSocket or nullptr.
BleSocket* GetRemoteSocket() ABSL_LOCKS_EXCLUDED(mutex_);
// Returns true if connection exists to the (possibly closed) remote socket.
bool IsConnected() const ABSL_LOCKS_EXCLUDED(mutex_);
// Returns true if socket is closed.
bool IsClosed() const ABSL_LOCKS_EXCLUDED(mutex_);
// Returns Exception::kIo on error, Exception::kSuccess otherwise.
Exception Close() override ABSL_LOCKS_EXCLUDED(mutex_);
// Returns valid BlePeripheral pointer if there is a connection, and
// nullptr otherwise.
BlePeripheral* GetRemotePeripheral() override ABSL_LOCKS_EXCLUDED(mutex_);
// Returns true if connection exists to the (possibly closed) remote socket.
bool IsConnectedLocked() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
// Returns InputStream of our side of a connection.
// This is what the remote side is supposed to read from.
// This is a helper for GetInputStream() method.
InputStream& GetLocalInputStream() ABSL_LOCKS_EXCLUDED(mutex_);
// Returns OutputStream of our side of a connection.
// This is what the local size is supposed to write to.
// This is a helper for GetOutputStream() method.
OutputStream& GetLocalOutputStream() ABSL_LOCKS_EXCLUDED(mutex_);
// Output pipe is initialized by constructor, it remains always valid, until
// it is closed. it represents output part of a local socket. Input part of a
// local socket comes from the peer socket, after connection.
std::shared_ptr<Pipe> output_{new Pipe};
std::shared_ptr<Pipe> input_;
mutable absl::Mutex mutex_;
BlePeripheral* peripheral_;
BleSocket* remote_socket_ ABSL_GUARDED_BY(mutex_) = nullptr;
bool closed_ ABSL_GUARDED_BY(mutex_) = false;
class BleServerSocket {
// Blocks until either:
// - at least one incoming connection request is available, or
// - ServerSocket is closed.
// On success, returns connected socket, ready to exchange data.
// Returns nullptr on error.
// Once error is reported, it is permanent, and ServerSocket has to be closed.
// Called by the server side of a connection.
// Returns BleSocket to the server side.
// If not null, returned socket is connected to its remote (client-side) peer.
std::unique_ptr<api::BleSocket> Accept(BlePeripheral* peripheral)
// Blocks until either:
// - connection is available, or
// - server socket is closed, or
// - error happens.
// Called by the client side of a connection.
// Returns true, if socket is successfully connected.
bool Connect(BleSocket& socket) ABSL_LOCKS_EXCLUDED(mutex_);
// Called by the server side of a connection before passing ownership of
// BleServerSocker to user, to track validity of a pointer to this
// server socket,
void SetCloseNotifier(std::function<void()> notifier)
// Returns Exception::kIo on error, Exception::kSuccess otherwise.
// Calls close_notifier if it was previously set, and marks socket as closed.
Exception Close() ABSL_LOCKS_EXCLUDED(mutex_);
Exception DoClose() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
absl::Mutex mutex_;
absl::CondVar cond_;
absl::flat_hash_set<BleSocket*> pending_sockets_ ABSL_GUARDED_BY(mutex_);
std::function<void()> close_notifier_ ABSL_GUARDED_BY(mutex_);
bool closed_ ABSL_GUARDED_BY(mutex_) = false;
// Container of operations that can be performed over the BLE medium.
class BleMedium : public api::BleMedium {
explicit BleMedium(api::BluetoothAdapter& adapter);
~BleMedium() override;
// Returns true once the Ble advertising has been initiated.
bool StartAdvertising(
const std::string& service_id, const ByteArray& advertisement_bytes,
const std::string& fast_advertisement_service_uuid) override
bool StopAdvertising(const std::string& service_id) override
// Returns true once the Ble scanning has been initiated.
bool StartScanning(const std::string& service_id,
const std::string& fast_advertisement_service_uuid,
DiscoveredPeripheralCallback callback) override
// Returns true once Ble scanning for service_id is well and truly
// stopped; after this returns, there must be no more invocations of the
// DiscoveredPeripheralCallback passed in to StartScanning() for service_id.
bool StopScanning(const std::string& service_id) override
// Returns true once Ble socket connection requests to service_id can be
// accepted.
bool StartAcceptingConnections(const std::string& service_id,
AcceptedConnectionCallback callback) override
bool StopAcceptingConnections(const std::string& service_id) override
// Connects to existing remote Ble peripheral.
// On success, returns a new BleSocket.
// On error, returns nullptr.
std::unique_ptr<api::BleSocket> Connect(
api::BlePeripheral& remote_peripheral, const std::string& service_id,
CancellationFlag* cancellation_flag) override ABSL_LOCKS_EXCLUDED(mutex_);
BluetoothAdapter& GetAdapter() { return *adapter_; }
static constexpr int kMaxConcurrentAcceptLoops = 5;
struct AdvertisingInfo {
bool Empty() const { return service_id.empty(); }
void Clear() { service_id.clear(); }
std::string service_id;
struct ScanningInfo {
bool Empty() const { return service_id.empty(); }
void Clear() { service_id.clear(); }
std::string service_id;
absl::Mutex mutex_;
BluetoothAdapter* adapter_; // Our device adapter; read-only.
// A thread pool dedicated to running all the accept loops from
// StartAdvertising().
MultiThreadExecutor accept_loops_runner_{kMaxConcurrentAcceptLoops};
std::atomic_bool acceptance_thread_running_ = false;
// A thread pool dedicated to wait to complete the accept_loops_runner_.
MultiThreadExecutor close_accept_loops_runner_{kMaxConcurrentAcceptLoops};
// A server socket is established when start advertising.
std::unique_ptr<BleServerSocket> server_socket_;
AdvertisingInfo advertising_info_ ABSL_GUARDED_BY(mutex_);
ScanningInfo scanning_info_ ABSL_GUARDED_BY(mutex_);
} // namespace g3
} // namespace nearby
} // namespace location