Fix: report reuse of invite-code and switch to local game-type (#9487)

This prevents two servers battling for the same invite-code. Now
the last one wins.

src/lang/english.txt

@@ -2285,6 +2285,7 @@ STR_NETWORK_MESSAGE_SERVER_REBOOT                               :{WHITE}The serv
 STR_NETWORK_MESSAGE_KICKED                                      :*** {RAW_STRING} was kicked. Reason: ({RAW_STRING})
 
 STR_NETWORK_ERROR_COORDINATOR_REGISTRATION_FAILED               :{WHITE}Server registration failed
+STR_NETWORK_ERROR_COORDINATOR_REUSE_OF_INVITE_CODE              :{WHITE}Another server with the same invite-code registered itself. Switching to "local" game-type.
 STR_NETWORK_ERROR_COORDINATOR_ISOLATED                          :{WHITE}Your server doesn't allow remote connections
 STR_NETWORK_ERROR_COORDINATOR_ISOLATED_DETAIL                   :{WHITE}Other players won't be able to connect to your server
 

src/network/core/config.h

@@ -50,7 +50,7 @@ static const uint16 COMPAT_MTU                      = 1460;           ///< Numbe
 static const byte NETWORK_GAME_ADMIN_VERSION        =    1;           ///< What version of the admin network do we use?
 static const byte NETWORK_GAME_INFO_VERSION         =    6;           ///< What version of game-info do we use?
 static const byte NETWORK_COMPANY_INFO_VERSION      =    6;           ///< What version of company info is this?
-static const byte NETWORK_COORDINATOR_VERSION       =    5;           ///< What version of game-coordinator-protocol do we use?
+static const byte NETWORK_COORDINATOR_VERSION       =    6;           ///< What version of game-coordinator-protocol do we use?
 
 static const uint NETWORK_NAME_LENGTH               =   80;           ///< The maximum length of the server name and map name, in bytes including '\0'
 static const uint NETWORK_COMPANY_NAME_LENGTH       =  128;           ///< The maximum length of the company name, in bytes including '\0'

src/network/core/tcp_coordinator.h

@@ -61,9 +61,10 @@ enum ConnectionType {
  * The type of error from the Game Coordinator.
  */
 enum NetworkCoordinatorErrorType {
-	NETWORK_COORDINATOR_ERROR_UNKNOWN,             ///< There was an unknown error.
-	NETWORK_COORDINATOR_ERROR_REGISTRATION_FAILED, ///< Your request for registration failed.
-	NETWORK_COORDINATOR_ERROR_INVALID_INVITE_CODE, ///< The invite code given is invalid.
+	NETWORK_COORDINATOR_ERROR_UNKNOWN,              ///< There was an unknown error.
+	NETWORK_COORDINATOR_ERROR_REGISTRATION_FAILED,  ///< Your request for registration failed.
+	NETWORK_COORDINATOR_ERROR_INVALID_INVITE_CODE,  ///< The invite code given is invalid.
+	NETWORK_COORDINATOR_ERROR_REUSE_OF_INVITE_CODE, ///< The invite code is used by another (newer) server.
 };
 
 /** Base socket handler for all Game Coordinator TCP sockets. */

src/network/network_coordinator.cpp

@@ -135,7 +135,6 @@ bool ClientNetworkCoordinatorSocketHandler::Receive_GC_ERROR(Packet *p)
 			return false;
 
 		case NETWORK_COORDINATOR_ERROR_REGISTRATION_FAILED:
-			SetDParamStr(0, detail);
 			ShowErrorMessage(STR_NETWORK_ERROR_COORDINATOR_REGISTRATION_FAILED, STR_JUST_RAW_STRING, WL_ERROR);
 
 			/* To prevent that we constantly try to reconnect, switch to local game. */
@@ -159,6 +158,15 @@ bool ClientNetworkCoordinatorSocketHandler::Receive_GC_ERROR(Packet *p)
 			return true;
 		}
 
+		case NETWORK_COORDINATOR_ERROR_REUSE_OF_INVITE_CODE:
+			ShowErrorMessage(STR_NETWORK_ERROR_COORDINATOR_REUSE_OF_INVITE_CODE, STR_JUST_RAW_STRING, WL_ERROR);
+
+			/* To prevent that we constantly battle for the same invite-code, switch to local game. */
+			_settings_client.network.server_game_type = SERVER_GAME_TYPE_LOCAL;
+
+			this->CloseConnection();
+			return false;
+
 		default:
 			Debug(net, 0, "Invalid error type {} received from Game Coordinator", error);
 			this->CloseConnection();