Made addon client and server exchange OOB messages on user cancel

this is needed to fix issue #2203

src/campaign_server/campaign_server.cpp

@@ -231,6 +231,13 @@ void server::handle_new_client(socket_ptr socket)
 					  );
 }
 
+void server::handle_out_of_band(socket_ptr socket, char data)
+{
+	socket->cancel();
+	socket->send(boost::asio::buffer(&data, 1), boost::asio::socket_base::message_out_of_band);
+	handle_new_client(socket);
+}
+
 void server::handle_request(socket_ptr socket, std::shared_ptr<simple_wml::document> doc)
 {
 	config data;

src/campaign_server/campaign_server.hpp

@@ -100,6 +100,7 @@ class server : public server_base
 	boost::asio::basic_waitable_timer<std::chrono::steady_clock> flush_timer_;
 
 	void handle_new_client(socket_ptr socket);
+	void handle_out_of_band(socket_ptr socket, char data);
 	void handle_request(socket_ptr socket, std::shared_ptr<simple_wml::document> doc);
 
 #ifndef _WIN32

src/network_asio.cpp

@@ -36,6 +36,7 @@ connection::connection(const std::string& host, const std::string& service)
 	, resolver_(io_service_)
 	, socket_(io_service_)
 	, done_(false)
+	, canceled_(false)
 	, write_buf_()
 	, read_buf_()
 	, handshake_response_()
@@ -139,11 +140,33 @@ void connection::cancel()
 		if(ec) {
 			WRN_NW << "Failed to cancel network operations: " << ec.message() << std::endl;
 		}
+		bytes_to_write_ = 0;
+		bytes_written_ = 0;
+		bytes_to_read_ = 0;
+		bytes_read_ = 0;
+
+		// send a message to server out-of-band so it would cancel transfer
+		socket_.send(boost::asio::buffer(&bytes_read_, 1), boost::asio::socket_base::message_out_of_band);
+
+		// drop data that server sent before canceling
+		canceled_ = true;
+		#define BOOST_ASIO_OS_DEF_SO_OOBINLINE SO_OOBINLINE
+		typedef boost::asio::detail::socket_option::boolean<
+			BOOST_ASIO_OS_DEF(SOL_SOCKET), BOOST_ASIO_OS_DEF(SO_OOBINLINE)>
+			  out_of_band_inline;
+		out_of_band_inline option(true);
+		socket_.set_option(option);
+
+		// TODO: this should be made async but changes to dialogs needed
+		std::unique_ptr<char[]> buf { new char[1024] };
+		while(canceled_) {
+			socket_.receive(boost::asio::buffer(buf.get(), 1024), boost::asio::socket_base::message_peek);
+			if(socket_.at_mark()) {
+				canceled_ = false;
+			}
+			socket_.receive(boost::asio::buffer(buf.get(), 1024));
+		}
 	}
-	bytes_to_write_ = 0;
-	bytes_written_ = 0;
-	bytes_to_read_ = 0;
-	bytes_read_ = 0;
 }
 
 std::size_t connection::is_write_complete(const boost::system::error_code& ec, std::size_t bytes_transferred)

src/network_asio.hpp

@@ -131,6 +131,7 @@ class connection
 	socket socket_;
 
 	bool done_;
+	bool canceled_;
 
 	std::unique_ptr<boost::asio::streambuf> write_buf_;
 	std::unique_ptr<boost::asio::streambuf> read_buf_;

src/server/server.cpp

@@ -514,6 +514,11 @@ void server::handle_new_client(socket_ptr socket)
 				   );
 }
 
+void server::handle_out_of_band(socket_ptr, char)
+{
+
+}
+
 void server::handle_version(socket_ptr socket)
 {
 	async_receive_doc(socket,

src/server/server.hpp

@@ -37,6 +37,7 @@ class server : public server_base
 
 private:
 	void handle_new_client(socket_ptr socket);
+	void handle_out_of_band(socket_ptr socket, char);
 
 	void handle_version(socket_ptr socket);
 	void read_version(socket_ptr socket, std::shared_ptr<simple_wml::document> doc);

src/server/server_base.cpp

@@ -120,6 +120,34 @@ void server_base::handle_handshake(const boost::system::error_code& error, socke
 				[=](const boost::system::error_code& error, size_t)
 					{ if(!check_error(error, socket)) this->handle_new_client(socket); }
 	);
+
+	read_oob_data(socket);
+}
+
+void server_base::read_oob_data(socket_ptr socket)
+{
+	boost::shared_array<char> buf { new char[1] };
+	socket_weak_ptr socket_weak { socket };
+	socket->async_receive(boost::asio::buffer(buf.get(), 1), boost::asio::socket_base::message_out_of_band,
+		[=](const boost::system::error_code& error, std::size_t)
+			{ this->handle_oob_data(error, socket_weak, buf); }
+		);
+}
+
+void server_base::handle_oob_data(const boost::system::error_code& error, socket_weak_ptr socket, boost::shared_array<char> buf)
+{
+	if(socket.expired())
+		return;
+	if(error) {
+		if(error.value() != boost::system::errc::invalid_argument) {
+			ERR_SERVER << client_address(socket.lock()) << "\terror reading out-of-band data: " << error.message() << std::endl;
+		}
+		return;
+	} else {
+		handle_out_of_band(socket.lock(), buf.get()[0]);
+	}
+
+	read_oob_data(socket.lock());
 }
 
 #ifndef _WIN32

src/server/server_base.hpp

@@ -26,6 +26,7 @@
 #include <boost/shared_array.hpp>
 
 typedef std::shared_ptr<boost::asio::ip::tcp::socket> socket_ptr;
+typedef std::weak_ptr<boost::asio::ip::tcp::socket> socket_weak_ptr;
 
 struct server_shutdown : public game::error
 {
@@ -55,7 +56,11 @@ class server_base
 	void serverside_handshake(socket_ptr socket);
 	void handle_handshake(const boost::system::error_code& error, socket_ptr socket, boost::shared_array<char> buf);
 
+	void read_oob_data(socket_ptr socket);
+	void handle_oob_data(const boost::system::error_code& error, socket_weak_ptr socket, boost::shared_array<char> buf);
+
 	virtual void handle_new_client(socket_ptr socket) = 0;
+	virtual void handle_out_of_band(socket_ptr socket, char) = 0;
 
 	virtual bool accepting_connections() const { return true; }
 	virtual std::string is_ip_banned(const std::string&) const { return std::string(); }