Feature: allow the use of STUN to connect client and server together

This method doesn't require port-forwarding to be used, and works for
most common NAT routers in home setups. But, for sure it doesn't work
for all setups, and not everyone will be able to use this.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/network/network_stun.h b/src/network/network_stun.h
new file mode 100644
index 000000000..8ffbff500
--- /dev/null
+++ b/src/network/network_stun.h
@@ -0,0 +1,34 @@
+/*
+ * 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_stun.h Part of the network protocol handling STUN requests. */
+
+#ifndef NETWORK_STUN_H
+#define NETWORK_STUN_H
+
+#include "core/tcp_stun.h"
+
+/** Class for handling the client side of the STUN connection. */
+class ClientNetworkStunSocketHandler : public NetworkStunSocketHandler {
+private:
+	std::string token;        ///< Token of this STUN handler.
+	uint8 family = AF_UNSPEC; ///< Family of this STUN handler.
+	bool sent_result = false; ///< Did we sent the result of the STUN connection?
+
+public:
+	TCPConnecter *connecter = nullptr; ///< Connecter instance.
+	NetworkAddress local_addr;         ///< Local addresses of the socket.
+
+	NetworkRecvStatus CloseConnection(bool error = true) override;
+	void SendReceive();
+
+	void Connect(const std::string &token, uint8 family);
+
+	static std::unique_ptr<ClientNetworkStunSocketHandler> Stun(const std::string &token, uint8 family);
+};
+
+#endif /* NETWORK_STUN_H */