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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.
// Windows headers
#include <windows.h> // NOLINT
#include <win32/windns.h> // NOLINT
// Standard C/C++ headers
#include <exception>
#include <functional>
#include <memory>
#include <string>
// Nearby connections headers
#include "absl/base/thread_annotations.h"
#include "absl/container/flat_hash_map.h"
#include "absl/container/flat_hash_set.h"
#include "absl/synchronization/mutex.h"
#include "absl/types/optional.h"
#include "platform/api/wifi_lan.h"
#include "platform/base/exception.h"
#include "platform/base/input_stream.h"
#include "platform/base/output_stream.h"
#include "platform/public/count_down_latch.h"
#include "platform/public/mutex.h"
// WinRT headers
#include "platform/impl/windows/generated/winrt/Windows.Devices.Enumeration.h"
#include "platform/impl/windows/generated/winrt/Windows.Foundation.Collections.h"
#include "platform/impl/windows/generated/winrt/Windows.Foundation.h"
#include "platform/impl/windows/generated/winrt/Windows.Networking.Connectivity.h"
#include "platform/impl/windows/generated/winrt/Windows.Networking.ServiceDiscovery.Dnssd.h"
#include "platform/impl/windows/generated/winrt/Windows.Networking.Sockets.h"
#include "platform/impl/windows/generated/winrt/Windows.Storage.Streams.h"
#include "platform/impl/windows/generated/winrt/base.h"
namespace location {
namespace nearby {
namespace windows {
using winrt::fire_and_forget;
using winrt::Windows::Devices::Enumeration::DeviceInformation;
using winrt::Windows::Devices::Enumeration::DeviceInformationKind;
using winrt::Windows::Devices::Enumeration::DeviceInformationUpdate;
using winrt::Windows::Devices::Enumeration::DeviceWatcher;
using winrt::Windows::Foundation::IInspectable;
using winrt::Windows::Foundation::Collections::IMapView;
using winrt::Windows::Networking::HostName;
using winrt::Windows::Networking::Connectivity::NetworkInformation;
using winrt::Windows::Networking::ServiceDiscovery::Dnssd::
using winrt::Windows::Networking::ServiceDiscovery::Dnssd::
using winrt::Windows::Networking::ServiceDiscovery::Dnssd::DnssdServiceInstance;
using winrt::Windows::Networking::Sockets::StreamSocket;
using winrt::Windows::Networking::Sockets::StreamSocketListener;
using winrt::Windows::Networking::Sockets::
using winrt::Windows::Networking::Sockets::StreamSocketListenerInformation;
using winrt::Windows::Storage::Streams::Buffer;
using winrt::Windows::Storage::Streams::DataReader;
using winrt::Windows::Storage::Streams::IBuffer;
using winrt::Windows::Storage::Streams::IInputStream;
using winrt::Windows::Storage::Streams::InputStreamOptions;
using winrt::Windows::Storage::Streams::IOutputStream;
// WifiLanSocket wraps the socket functions to read and write stream.
// In WiFi LAN, A WifiLanSocket will be passed to StartAcceptingConnections's
// call back when StreamSocketListener got connect. When call API to connect to
// remote WiFi LAN service, also will return a WifiLanSocket to caller.
class WifiLanSocket : public api::WifiLanSocket {
explicit WifiLanSocket(StreamSocket socket);
WifiLanSocket(WifiLanSocket&) = default;
WifiLanSocket(WifiLanSocket&&) = default;
~WifiLanSocket() override;
WifiLanSocket& operator=(const WifiLanSocket&) = default;
WifiLanSocket& operator=(WifiLanSocket&&) = default;
// Returns the InputStream of the WifiLanSocket.
// On error, returned stream will report Exception::kIo on any operation.
// The returned object is not owned by the caller, and can be invalidated once
// the WifiLanSocket object is destroyed.
InputStream& GetInputStream() override;
// Returns the OutputStream of the WifiLanSocket.
// On error, returned stream will report Exception::kIo on any operation.
// The returned object is not owned by the caller, and can be invalidated once
// the WifiLanSocket object is destroyed.
OutputStream& GetOutputStream() override;
// Returns Exception::kIo on error, Exception::kSuccess otherwise.
Exception Close() override;
// A simple wrapper to handle input stream of socket
class SocketInputStream : public InputStream {
SocketInputStream(IInputStream input_stream);
~SocketInputStream() = default;
ExceptionOr<ByteArray> Read(std::int64_t size) override;
ExceptionOr<size_t> Skip(size_t offset) override;
Exception Close() override;
IInputStream input_stream_{nullptr};
// A simple wrapper to handle output stream of socket
class SocketOutputStream : public OutputStream {
SocketOutputStream(IOutputStream output_stream);
~SocketOutputStream() = default;
Exception Write(const ByteArray& data) override;
Exception Flush() override;
Exception Close() override;
IOutputStream output_stream_{nullptr};
// Internal properties
StreamSocket stream_soket_{nullptr};
SocketInputStream input_stream_{nullptr};
SocketOutputStream output_stream_{nullptr};
// WifiLanServerSocket provides the support to server socket, this server socket
// accepts connection from clients.
class WifiLanServerSocket : public api::WifiLanServerSocket {
explicit WifiLanServerSocket(int port = 0);
WifiLanServerSocket(WifiLanServerSocket&) = default;
WifiLanServerSocket(WifiLanServerSocket&&) = default;
~WifiLanServerSocket() override;
WifiLanServerSocket& operator=(const WifiLanServerSocket&) = default;
WifiLanServerSocket& operator=(WifiLanServerSocket&&) = default;
// Returns ip address.
std::string GetIPAddress() const override;
// Returns port.
int GetPort() const override;
// Sets port
void SetPort(int port) { port_ = port; }
StreamSocketListener GetSocketListener() const {
return stream_socket_listener_;
// 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.
std::unique_ptr<api::WifiLanSocket> Accept() override;
// Called by the server side of a connection before passing ownership of
// WifiLanServerSocker 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.
Exception Close() override;
// Binds to local port
bool listen();
// The listener is accepting incoming connections
fire_and_forget Listener_ConnectionReceived(
StreamSocketListener listener,
StreamSocketListenerConnectionReceivedEventArgs const& args);
// Retrieves IP addresses from local machine
std::vector<std::string> GetIpAddresses();
mutable absl::Mutex mutex_;
absl::CondVar cond_;
std::deque<StreamSocket> pending_sockets_ ABSL_GUARDED_BY(mutex_);
StreamSocketListener stream_socket_listener_{nullptr};
winrt::event_token listener_event_token_{};
// Close notifier
std::function<void()> close_notifier_ = nullptr;
// IP addresses of the computer. mDNS uses them to advertise.
std::vector<std::string> ip_addresses_{};
// Cache socket not be picked by upper layer
int port_ = 0;
bool closed_ = false;
// Container of operations that can be performed over the WifiLan medium.
class WifiLanMedium : public api::WifiLanMedium {
~WifiLanMedium() override = default;
// Starts to advertising
bool StartAdvertising(const NsdServiceInfo& nsd_service_info) override;
// Stops to advertising
bool StopAdvertising(const NsdServiceInfo& nsd_service_info) override;
// Starts to discovery
bool StartDiscovery(const std::string& service_type,
DiscoveredServiceCallback callback) override;
// Returns true once WifiLan discovery for service_type is well and truly
// stopped; after this returns, there must be no more invocations of the
// DiscoveredServiceCallback passed in to StartDiscovery() for service_type.
bool StopDiscovery(const std::string& service_type) override;
std::unique_ptr<api::WifiLanSocket> ConnectToService(
const NsdServiceInfo& remote_service_info,
CancellationFlag* cancellation_flag) override;
std::unique_ptr<api::WifiLanSocket> ConnectToService(
const std::string& ip_address, int port,
CancellationFlag* cancellation_flag) override;
std::unique_ptr<api::WifiLanServerSocket> ListenForService(
int port = 0) override;
// DnsServiceDeRegister is a async process, after operation finish, callback
// will call this method to notify the waiting method StopAdvertising to
// continue.
void NotifyDnsServiceUnregistered(DWORD status);
absl::optional<std::pair<std::int32_t, std::int32_t>> GetDynamicPortRange()
override {
return absl::nullopt;
// mDNS text attributes
static constexpr std::string_view KEY_ENDPOINT_INFO = "n";
// mDNS information for advertising and discovery
static constexpr std::wstring_view MDNS_HOST_NAME = L"Windows.local";
static constexpr std::string_view MDNS_INSTANCE_NAME_FORMAT = "%s.%slocal";
static constexpr std::string_view MDNS_DEVICE_SELECTOR_FORMAT =
"55e86ada0e54}\" "
"AND System.Devices.Dnssd.ServiceName:=\"%s._tcp\" AND "
// Nsd status
static const int MEDIUM_STATUS_IDLE = 0;
static const int MEDIUM_STATUS_ACCEPTING = (1 << 0);
static const int MEDIUM_STATUS_ADVERTISING = (1 << 1);
static const int MEDIUM_STATUS_DISCOVERING = (1 << 2);
// In the class, not using ENUM to describe the mDNS states, because a little
// complicate to combine all states based on accepting, advertising and
// discovery.
bool IsIdle() { return medium_status_ == 0; }
bool IsAccepting() { return (medium_status_ & MEDIUM_STATUS_ACCEPTING) != 0; }
bool IsAdvertising() {
return (medium_status_ & MEDIUM_STATUS_ADVERTISING) != 0;
bool IsDiscovering() {
return (medium_status_ & MEDIUM_STATUS_DISCOVERING) != 0;
// From mDNS device information, to build NsdServiceInfo.
// the properties are from DeviceInformation and DeviceInformationUpdate.
// The API gets IP addresses, service name and text attributes of mDNS
// from these properties,
NsdServiceInfo GetNsdServiceInformation(
IMapView<winrt::hstring, IInspectable> properties);
// mDNS callbacks for advertising and discovery
fire_and_forget Watcher_DeviceAdded(DeviceWatcher sender,
DeviceInformation deviceInfo);
fire_and_forget Watcher_DeviceUpdated(
DeviceWatcher sender, DeviceInformationUpdate deviceInfoUpdate);
fire_and_forget Watcher_DeviceRemoved(
DeviceWatcher sender, DeviceInformationUpdate deviceInfoUpdate);
static void Advertising_StopCompleted(DWORD Status, PVOID pQueryContext,
// Gets error message from exception pointer
std::string GetErrorMessage(std::exception_ptr eptr);
// Dns-sd related properties
// Advertising properties
DnssdServiceInstance dnssd_service_instance_{nullptr};
DnssdRegistrationResult dnssd_regirstraion_result_{nullptr};
// Stop advertising properties
DNS_SERVICE_INSTANCE dns_service_instance_{nullptr};
DNS_SERVICE_REGISTER_REQUEST dns_service_register_request_;
std::unique_ptr<std::wstring> dns_service_instance_name_{nullptr};
std::unique_ptr<CountDownLatch> dns_service_stop_latch_;
DWORD dns_service_stop_status_;
// Discovery properties
DeviceWatcher device_watcher_{nullptr};
winrt::event_token device_watcher_added_event_token;
winrt::event_token device_watcher_updated_event_token;
winrt::event_token device_watcher_removed_event_token;
// callback for discovery
api::WifiLanMedium::DiscoveredServiceCallback discovered_service_callback_;
// Protects to access some members
absl::Mutex mutex_;
// Medium Status
int medium_status_ = MEDIUM_STATUS_IDLE;
// Keep the server socket listener pointer
WifiLanServerSocket* server_socket_ptr_ ABSL_GUARDED_BY(mutex_) = nullptr;
} // namespace windows
} // namespace nearby
} // namespace location