Function enable_socket_qos

src/platform/windows/misc.cpp:1616–1723

* @brief Enables QoS on the given socket for traffic to the specified destination. * @param native_socket The native socket handle. * @param address The destination address for traffic sent on this socket. * @param port The destination port for traffic sent on this socket. * @param data_type The type of traffic sent on this socket. * @param dscp_tagging Specifies whether to enable D

   * @param dscp_tagging Specifies whether to enable DSCP tagging on outgoing traffic.
   */
  std::unique_ptr<deinit_t> enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type, bool dscp_tagging) {
    SOCKADDR_IN saddr_v4;
    SOCKADDR_IN6 saddr_v6;
    PSOCKADDR dest_addr;
    bool using_connect_hack = false;

    // Windows doesn't support any concept of traffic priority without DSCP tagging
    if (!dscp_tagging) {
      return nullptr;
    }

    static std::once_flag load_qwave_once_flag;
    std::call_once(load_qwave_once_flag, []() {
      // qWAVE is not installed by default on Windows Server, so we load it dynamically
      HMODULE qwave = LoadLibraryExA("qwave.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
      if (!qwave) {
        BOOST_LOG(debug) << "qwave.dll is not available on this OS"sv;
        return;
      }

      fn_QOSCreateHandle = (decltype(fn_QOSCreateHandle)) GetProcAddress(qwave, "QOSCreateHandle");
      fn_QOSAddSocketToFlow = (decltype(fn_QOSAddSocketToFlow)) GetProcAddress(qwave, "QOSAddSocketToFlow");
      fn_QOSRemoveSocketFromFlow = (decltype(fn_QOSRemoveSocketFromFlow)) GetProcAddress(qwave, "QOSRemoveSocketFromFlow");

      if (!fn_QOSCreateHandle || !fn_QOSAddSocketToFlow || !fn_QOSRemoveSocketFromFlow) {
        BOOST_LOG(error) << "qwave.dll is missing exports?"sv;

        fn_QOSCreateHandle = nullptr;
        fn_QOSAddSocketToFlow = nullptr;
        fn_QOSRemoveSocketFromFlow = nullptr;

        FreeLibrary(qwave);
        return;
      }

      QOS_VERSION qos_version {1, 0};
      if (!fn_QOSCreateHandle(&qos_version, &qos_handle)) {
        auto winerr = GetLastError();
        BOOST_LOG(warning) << "QOSCreateHandle() failed: "sv << winerr;
        return;
      }
    });

    // If qWAVE is unavailable, just return
    if (!fn_QOSAddSocketToFlow || !qos_handle) {
      return nullptr;
    }

    auto disconnect_fg = util::fail_guard([&]() {
      if (using_connect_hack) {
        SOCKADDR_IN6 empty = {};
        empty.sin6_family = AF_INET6;
        if (connect((SOCKET) native_socket, (PSOCKADDR) &empty, sizeof(empty)) < 0) {
          auto wsaerr = WSAGetLastError();
          BOOST_LOG(error) << "qWAVE dual-stack workaround failed: "sv << wsaerr;
        }
      }
    });