Improve the "UDP port 20595" connection error dialog

Add a unique disconnect reason for timeouts of connection attempts.
Rewrite the displayed error message and provide a link directly to the FAQ entry.
(The old message was very misleading and only brought players on the
wrong track during troubleshooting)

binaries/data/mods/public/gui/common/network.js

@@ -58,35 +58,43 @@ function getValidPort(port)
 /**
  * Must be kept in sync with source/network/NetHost.h
  */
-function getDisconnectReason(id, wasConnected)
+function getDisconnectReason(id)
 {
 	switch (id)
 	{
-	case 0: return wasConnected ? "" :
-		translate("This is often caused by UDP port 20595 not being forwarded on the host side, by a firewall, or anti-virus software.");
-	case 1: return translate("The host has ended the game.");
-	case 2: return translate("Incorrect network protocol version.");
-	case 3: return translate("Game is loading, please try again later.");
-	case 4: return translate("Game has already started, no observers allowed.");
-	case 5: return translate("You have been kicked.");
-	case 6: return translate("You have been banned.");
-	case 7: return translate("Player name in use. If you were disconnected, retry in few seconds.");
-	case 8: return translate("Server full.");
-	case 9: return translate("Secure lobby authentication failed. Join via lobby.");
-	case 10: return translate("Error: Server failed to allocate a unique client identifier.");
-	case 11: return translate("Error: Client commands were ready for an unexpected game turn.");
-	case 12: return translate("Error: Client simulated an unexpected game turn.");
-	case 13: return translate("Password is invalid.");
-	case 14: return translate("Could not find an unused port for the enet STUN client.");
-	case 15: return translate("Could not find the STUN endpoint.");
-	case 16: return translate("Different game engine versions or different mods loaded.");
+	case 0: return translate("An unknown error ocurred.");
+	case 1: return translate("The connection request has timed out.");
+	case 2: return translate("The host has ended the game.");
+	case 3: return translate("Incorrect network protocol version.");
+	case 4: return translate("Game is loading, please try again later.");
+	case 5: return translate("Game has already started, no observers allowed.");
+	case 6: return translate("You have been kicked.");
+	case 7: return translate("You have been banned.");
+	case 8: return translate("Player name in use. If you were disconnected, retry in few seconds.");
+	case 9: return translate("Server full.");
+	case 10: return translate("Secure lobby authentication failed. Join via lobby.");
+	case 11: return translate("Error: Server failed to allocate a unique client identifier.");
+	case 12: return translate("Error: Client commands were ready for an unexpected game turn.");
+	case 13: return translate("Error: Client simulated an unexpected game turn.");
+	case 14: return translate("Password is invalid.");
+	case 15: return translate("Could not find an unused port for the enet STUN client.");
+	case 16: return translate("Could not find the STUN endpoint.");
+	case 17: return translate("Different game engine versions or different mods loaded.");
+
 	default:
 		warn("Unknown disconnect-reason ID received: " + id);
 		return sprintf(translate("\\[Invalid value %(id)s]"), { "id": id });
 	}
 }
 
-function getHandshakeDisconnectMessage(mismatchType, clientMismatchInfo, serverMismatchInfo)
+function getRequestTimeOutMessage()
+{
+	return (Engine.HasXmppClient() ? "" : translate("Please ensure that you entered the correct server name or IP address, and port number.\n\n")) +
+		translate("If you haven't yet, try to connect again and to different hosts." +
+		"\nIf the issue persists or occurs regularly, visit the official FAQ for detailed guidance and troubleshooting steps.");
+}
+
+function getMismatchMessage(mismatchType, clientMismatchInfo, serverMismatchInfo)
 {
 	switch (mismatchType)
 	{
@@ -107,26 +115,46 @@ function getHandshakeDisconnectMessage(mismatchType, clientMismatchInfo, serverM
 /**
  * Show the disconnect reason in a message box.
  *
- * @param {number} reason
+ * @param {Object} message
+ * @param {boolean} wasConnected
  */
-function reportDisconnect(reason, wasConnected)
+function reportDisconnect(message, wasConnected)
 {
-	messageBox(
-		400, 200,
-		(wasConnected ?
-			translate("Lost connection to the server.") :
-			translate("Failed to connect to the server.")
-		) + "\n\n" + getDisconnectReason(reason, wasConnected),
-		translate("Disconnected")
-	);
+	if (message.reason === 0)
+		reportConnectionRequestTimeOut();
+	else if (message.reason == 16)
+		reportMismatchingSoftwareVersions(message.mismatch_type, message.client_mismatch, message.server_mismatch);
+	else
+		messageBox(
+			400, 200,
+			(wasConnected ?
+				translate("Lost connection to the server.") :
+				translate("Failed to connect to the server.")
+			) + "\n\n" + getDisconnectReason(message.reason),
+			translate("Disconnected")
+		);
 }
 
-function reportHandshakeDisconnect(mismatchType, clientMismatch, serverMismatch)
+async function reportConnectionRequestTimeOut()
+{
+	const buttonIndex = await messageBox(
+		600, 230,
+		translate("Failed to connect to the server.") + " " + getDisconnectReason(1) + "\n\n" + getRequestTimeOutMessage(),
+		translate("Connection Error"),
+		[translate("Close"), translate("Open FAQ")]
+	);
+	if (buttonIndex === 1)
+		openURL("https://gitea.wildfiregames.com/0ad/0ad/wiki/FAQ#what-shall-i-do-when-joining-multiplayer-matches-fails-with-an-error-message");
+
+	return;
+}
+
+function reportMismatchingSoftwareVersions(mismatchType, clientMismatch, serverMismatch)
 {
 	messageBox(
 		400, 200,
 	        translate("Failed to connect to the server.")
-		+ "\n\n" + getHandshakeDisconnectMessage(mismatchType, clientMismatch, serverMismatch),
+		+ "\n\n" + getMismatchMessage(mismatchType, clientMismatch, serverMismatch),
 		translate("Disconnected")
 	);
 }

binaries/data/mods/public/gui/gamesetup_mp/gamesetup_mp.js

@@ -317,8 +317,8 @@ function pollAndHandleNetworkClient(loadSavedGame)
 					if (message.reason === 16)
 						reportHandshakeDisconnect(message.mismatch_type, message.client_mismatch_component, message.server_mismatch_component);
 					else
-						reportDisconnect(message.reason, false);
-					return true;
+						reportDisconnect(message, false);
+					return;
 
 				default:
 					error("Unrecognised netstatus type: " + message.status);

source/network/NetHost.h

@@ -62,6 +62,7 @@ typedef std::map<CStr, PlayerAssignment> PlayerAssignmentMap; // map from GUID -
 enum NetDisconnectReason
 {
 	NDR_UNKNOWN = 0,
+	NDR_CONNECTION_REQUEST_TIMED_OUT,
 	NDR_SERVER_SHUTDOWN,
 	NDR_INCORRECT_PROTOCOL_VERSION,
 	NDR_SERVER_LOADING,

source/network/NetSession.cpp

@@ -135,6 +135,7 @@ void CNetClientSession::Poll()
 		enet_address_get_host_ip(&event.peer->address, hostname, ARRAY_SIZE(hostname));
 		LOGMESSAGE("Net client: Connected to %s:%u", hostname, (unsigned int)event.peer->address.port);
 		m_Connected = true;
+		m_WasConnected = true;
 
 		m_IncomingMessages.push(event);
 	}
@@ -178,7 +179,10 @@ void CNetClientSession::ProcessPolledMessages()
 		else if (event.type == ENET_EVENT_TYPE_DISCONNECT)
 		{
 			// This deletes the session, so we must break;
-			m_Client.HandleDisconnect(event.data);
+			if (event.data == 0 && !m_WasConnected)
+				m_Client.HandleDisconnect(NDR_CONNECTION_REQUEST_TIMED_OUT);
+			else
+				m_Client.HandleDisconnect(event.data);
 			break;
 		}
 		else if (event.type == ENET_EVENT_TYPE_RECEIVE)

source/network/NetSession.h

@@ -126,9 +126,12 @@ private:
 	// Net messages to send on the next flush() call.
 	boost::lockfree::queue<ENetPacket*> m_OutgoingMessages;
 
-	// Last know state. If false, flushing errors are silenced.
+	// Last known state. If false, flushing errors are silenced.
 	bool m_Connected = false;
 
+	// Whether this session was ever connected to the server.
+	bool m_WasConnected = false;
+
 	// Wrapper around enet stats - those are atomic as the code is lock-free.
 	std::atomic<u32> m_LastReceivedTime;
 	std::atomic<u32> m_MeanRTT;