enable/disable the internal ip notifier with new setting (#2487)

include/libtorrent/aux_/session_impl.hpp

@@ -614,10 +614,12 @@ namespace aux {
 				, error_code const& e);
 #endif
 
+			void start_ip_notifier();
 			void start_lsd();
 			natpmp* start_natpmp();
 			upnp* start_upnp();
 
+			void stop_ip_notifier();
 			void stop_lsd();
 			void stop_natpmp();
 			void stop_upnp();
@@ -715,6 +717,7 @@ namespace aux {
 			void update_max_failcount();
 			void update_resolver_cache_timeout();
 
+			void update_ip_notifier();
 			void update_upnp();
 			void update_natpmp();
 			void update_lsd();

include/libtorrent/settings_pack.hpp

@@ -716,6 +716,16 @@ namespace libtorrent {
 			// any.
 			proxy_tracker_connections,
 
+			// Starts and stops the internal IP table route changes notifier.
+			//
+			// The current implementation supports multiple platforms, and it is
+			// recommended to have it enable, but you may want to disable it if
+			// it's supported but unreliable, or if you have a better way to
+			// detect the changes. In the later case, you should manually call
+			// ``session_handle::reopen_network_sockets`` to ensure network
+			// changes are taken in consideration.
+			enable_ip_notifier,
+
 			max_bool_setting_internal
 		};
 

simulation/test_session.cpp

@@ -64,3 +64,51 @@ TORRENT_TEST(seed_mode)
 		});
 }
 
+TORRENT_TEST(ip_notifier_setting)
+{
+	int s_tick = 0;
+	int working_count = 0;
+
+	setup_swarm(1, swarm_test::upload
+		// add session
+		, [](lt::settings_pack& pack)
+		{
+			pack.set_int(settings_pack::tick_interval, 1000);
+			pack.set_int(settings_pack::alert_mask, alert::all_categories);
+		}
+		// add torrent
+		, [](lt::add_torrent_params& params) {}
+		// on alert
+		, [&s_tick, &working_count](lt::alert const* a, lt::session& ses)
+		{
+			std::string const msg = a->message();
+			if (msg.find("received error on_ip_change:") != std::string::npos)
+			{
+				TEST_CHECK(s_tick == 0 || s_tick == 2);
+				working_count++;
+			}
+		}
+		// terminate
+		, [&s_tick](int ticks, lt::session& ses) -> bool {
+
+			if (ticks == 1)
+			{
+				settings_pack sp;
+				sp.set_bool(settings_pack::enable_ip_notifier, false);
+				ses.apply_settings(sp);
+			}
+			else if (ticks == 2)
+			{
+				settings_pack sp;
+				sp.set_bool(settings_pack::enable_ip_notifier, true);
+				ses.apply_settings(sp);
+			}
+
+			s_tick = ticks;
+
+			// exit after 3 seconds
+			return ticks > 3;
+		});
+
+	TEST_EQUAL(working_count, 2);
+}

src/ip_notifier.cpp

@@ -91,7 +91,7 @@ struct ip_change_notifier_impl final : ip_change_notifier
 	{
 		using namespace std::placeholders;
 		m_socket.async_receive(boost::asio::buffer(m_buf)
-			, std::bind(&ip_change_notifier_impl::on_notify, this, _1, _2, std::move(cb)));
+			, std::bind(&ip_change_notifier_impl::on_notify, _1, _2, std::move(cb)));
 	}
 
 	void cancel() override
@@ -101,7 +101,7 @@ private:
 	netlink::socket m_socket;
 	std::array<char, 4096> m_buf;
 
-	void on_notify(error_code const& ec, std::size_t bytes_transferred
+	static void on_notify(error_code const& ec, std::size_t bytes_transferred
 		, std::function<void(error_code const&)> const& cb)
 	{
 		TORRENT_UNUSED(bytes_transferred);

src/session_impl.cpp

@@ -412,7 +412,6 @@ namespace aux {
 #endif
 			)
 		, m_work(new io_service::work(m_io_service))
-		, m_ip_notifier(create_ip_notifier(m_io_service))
 #if TORRENT_USE_I2P
 		, m_i2p_conn(m_io_service)
 #endif
@@ -589,9 +588,6 @@ namespace aux {
 		session_log(" done starting session");
 #endif
 
-		m_ip_notifier->async_wait([this](error_code const& e)
-			{ this->wrap(&session_impl::on_ip_change, e); });
-
 		apply_settings_pack_impl(*pack, true);
 
 		// call update_* after settings set initialized
@@ -606,6 +602,7 @@ namespace aux {
 		update_unchoke_limit();
 		update_disk_threads();
 		update_resolver_cache_timeout();
+		update_ip_notifier();
 		update_upnp();
 		update_natpmp();
 		update_lsd();
@@ -885,11 +882,10 @@ namespace aux {
 		m_abort = true;
 		error_code ec;
 
-		m_ip_notifier->cancel();
-
 #if TORRENT_USE_I2P
 		m_i2p_conn.close(ec);
 #endif
+		stop_ip_notifier();
 		stop_lsd();
 		stop_upnp();
 		stop_natpmp();
@@ -1737,7 +1733,7 @@ namespace {
 		else
 			session_log("received error on_ip_change: %d, %s", ec.value(), ec.message().c_str());
 #endif
-		if (ec || m_abort) return;
+		if (ec || m_abort || !m_ip_notifier) return;
 		m_ip_notifier->async_wait([this] (error_code const& e)
 			{ this->wrap(&session_impl::on_ip_change, e); });
 		reopen_network_sockets(session_handle::reopen_map_ports);
@@ -5249,6 +5245,14 @@ namespace {
 		m_outgoing_sockets.update_proxy(proxy());
 	}
 
+	void session_impl::update_ip_notifier()
+	{
+		if (m_settings.get_bool(settings_pack::enable_ip_notifier))
+			start_ip_notifier();
+		else
+			stop_ip_notifier();
+	}
+
 	void session_impl::update_upnp()
 	{
 		if (m_settings.get_bool(settings_pack::enable_upnp))
@@ -6527,6 +6531,17 @@ namespace {
 	}
 #endif
 
+	void session_impl::start_ip_notifier()
+	{
+		INVARIANT_CHECK;
+
+		if (m_ip_notifier) return;
+
+		m_ip_notifier = create_ip_notifier(m_io_service);
+		m_ip_notifier->async_wait([this](error_code const& e)
+			{ this->wrap(&session_impl::on_ip_change, e); });
+	}
+
 	void session_impl::start_lsd()
 	{
 		INVARIANT_CHECK;
@@ -6599,6 +6614,14 @@ namespace {
 		if (m_natpmp) m_natpmp->delete_mapping(handle);
 	}
 
+	void session_impl::stop_ip_notifier()
+	{
+		if (!m_ip_notifier) return;
+
+		m_ip_notifier->cancel();
+		m_ip_notifier.reset();
+	}
+
 	void session_impl::stop_lsd()
 	{
 		if (m_lsd)

src/settings_pack.cpp

@@ -199,6 +199,7 @@ constexpr int CLOSE_FILE_INTERVAL = 0;
 		SET(proxy_peer_connections, true, nullptr),
 		SET(auto_sequential, true, &session_impl::update_auto_sequential),
 		SET(proxy_tracker_connections, true, nullptr),
+		SET(enable_ip_notifier, true, &session_impl::update_ip_notifier),
 	}});
 
 	aux::array<int_setting_entry_t, settings_pack::num_int_settings> const int_settings