Add: use Game Coordinator to annouce public servers

src/network/network_coordinator.h

@@ -0,0 +1,51 @@
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file network_coordinator.h Part of the network protocol handling Game Coordinator requests. */
+
+#ifndef NETWORK_COORDINATOR_H
+#define NETWORK_COORDINATOR_H
+
+#include "core/tcp_coordinator.h"
+
+/**
+ * Game Coordinator communication.
+ *
+ * For servers:
+ *  - Server sends SERVER_REGISTER.
+ *  - Game Coordinator probes server to check if it can directly connect.
+ *  - Game Coordinator sends GC_REGISTER_ACK with type of connection.
+ *  - Server sends every 30 seconds SERVER_UPDATE.
+ */
+
+/** Class for handling the client side of the Game Coordinator connection. */
+class ClientNetworkCoordinatorSocketHandler : public NetworkCoordinatorSocketHandler {
+private:
+	std::chrono::steady_clock::time_point next_update; ///< When to send the next update (if server and public).
+
+protected:
+	bool Receive_GC_ERROR(Packet *p) override;
+	bool Receive_GC_REGISTER_ACK(Packet *p) override;
+
+public:
+	bool connecting; ///< Are we connecting to the Game Coordinator?
+
+	ClientNetworkCoordinatorSocketHandler() : connecting(false) {}
+
+	NetworkRecvStatus CloseConnection(bool error = true) override;
+	void SendReceive();
+
+	void Connect();
+
+	void Register();
+	void SendServerUpdate();
+};
+
+extern ClientNetworkCoordinatorSocketHandler _network_coordinator_client;
+
+#endif /* NETWORK_COORDINATOR_H */