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

TURN is a last resort, used only if all other methods failed.
TURN is a relay approach to connect client and server together, where
openttd.org (by default) is the middleman.

It is very unlikely either the client or server cannot connect to
the STUN server, as they are both already connected to the Game
Coordinator. But in the odd case it does fail, estabilishing the
connection fails without any further possibility to recover.

1 files changed, 102 insertions, 0 deletions

diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index 1368ac0ad..a535962b5 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -2699,3 +2699,105 @@ void ShowNetworkCompanyPasswordWindow(Window *parent)
 
 	new NetworkCompanyPasswordWindow(&_network_company_password_window_desc, parent);
 }
+
+/**
+ * Window used for asking the user if he is okay using a TURN server.
+ */
+struct NetworkAskRelayWindow : public Window {
+	std::string connection_string; ///< The TURN server we want to connect to.
+	std::string token;             ///< The token for this connection.
+
+	NetworkAskRelayWindow(WindowDesc *desc, Window *parent, const std::string &connection_string, const std::string &token) : Window(desc), connection_string(connection_string), token(token)
+	{
+		this->parent = parent;
+		this->InitNested(0);
+	}
+
+	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
+	{
+		if (widget == WID_NAR_TEXT) {
+			*size = GetStringBoundingBox(STR_NETWORK_ASK_RELAY_TEXT);
+			size->height = GetStringHeight(STR_NETWORK_ASK_RELAY_TEXT, size->width - WD_FRAMETEXT_LEFT - WD_FRAMETEXT_RIGHT) + WD_FRAMETEXT_BOTTOM + WD_FRAMETEXT_TOP;
+		}
+	}
+
+	void DrawWidget(const Rect &r, int widget) const override
+	{
+		if (widget == WID_NAR_TEXT) {
+			DrawStringMultiLine(r.left + WD_FRAMETEXT_LEFT, r.right - WD_FRAMETEXT_RIGHT, r.top + WD_FRAMETEXT_TOP, r.bottom - WD_FRAMETEXT_BOTTOM, STR_NETWORK_ASK_RELAY_TEXT, TC_FROMSTRING, SA_CENTER);
+		}
+	}
+
+	void FindWindowPlacementAndResize(int def_width, int def_height) override
+	{
+		/* Position query window over the calling window, ensuring it's within screen bounds. */
+		this->left = Clamp(parent->left + (parent->width / 2) - (this->width / 2), 0, _screen.width - this->width);
+		this->top = Clamp(parent->top + (parent->height / 2) - (this->height / 2), 0, _screen.height - this->height);
+		this->SetDirty();
+	}
+
+	void SetStringParameters(int widget) const override
+	{
+		switch (widget) {
+			case WID_NAR_TEXT:
+				SetDParamStr(0, this->connection_string);
+				break;
+		}
+	}
+
+	void OnClick(Point pt, int widget, int click_count) override
+	{
+		switch (widget) {
+			case WID_NAR_NO:
+				_network_coordinator_client.ConnectFailure(this->token, 0);
+				this->Close();
+				break;
+
+			case WID_NAR_YES_ONCE:
+				_network_coordinator_client.StartTurnConnection(this->token);
+				this->Close();
+				break;
+
+			case WID_NAR_YES_ALWAYS:
+				_settings_client.network.use_relay_service = URS_ALLOW;
+				_network_coordinator_client.StartTurnConnection(this->token);
+				this->Close();
+				break;
+		}
+	}
+};
+
+static const NWidgetPart _nested_network_ask_relay_widgets[] = {
+	NWidget(NWID_HORIZONTAL),
+		NWidget(WWT_CLOSEBOX, COLOUR_RED),
+		NWidget(WWT_CAPTION, COLOUR_RED, WID_NAR_CAPTION), SetDataTip(STR_NETWORK_ASK_RELAY_CAPTION, STR_NULL),
+	EndContainer(),
+	NWidget(WWT_PANEL, COLOUR_RED), SetPIP(0, 0, 8),
+		NWidget(WWT_TEXT, COLOUR_RED, WID_NAR_TEXT), SetAlignment(SA_HOR_CENTER), SetFill(1, 1),
+		NWidget(NWID_HORIZONTAL, NC_EQUALSIZE), SetPIP(10, 15, 10),
+			NWidget(WWT_PUSHTXTBTN, COLOUR_YELLOW, WID_NAR_NO), SetMinimalSize(71, 12), SetFill(1, 1), SetDataTip(STR_NETWORK_ASK_RELAY_NO, STR_NULL),
+			NWidget(WWT_PUSHTXTBTN, COLOUR_YELLOW, WID_NAR_YES_ONCE), SetMinimalSize(71, 12), SetFill(1, 1), SetDataTip(STR_NETWORK_ASK_RELAY_YES_ONCE, STR_NULL),
+			NWidget(WWT_PUSHTXTBTN, COLOUR_YELLOW, WID_NAR_YES_ALWAYS), SetMinimalSize(71, 12), SetFill(1, 1), SetDataTip(STR_NETWORK_ASK_RELAY_YES_ALWAYS, STR_NULL),
+		EndContainer(),
+	EndContainer(),
+};
+
+static WindowDesc _network_ask_relay_desc(
+	WDP_CENTER, nullptr, 0, 0,
+	WC_NETWORK_ASK_RELAY, WC_NONE,
+	WDF_MODAL,
+	_nested_network_ask_relay_widgets, lengthof(_nested_network_ask_relay_widgets)
+);
+
+/**
+ * Show a modal confirmation window with "no" / "yes, once" / "yes, always" buttons.
+ * @param connection_string The relay server we want to connect to.
+ * @param token The token for this connection.
+ */
+void ShowNetworkAskRelay(const std::string &connection_string, const std::string &token)
+{
+	CloseWindowByClass(WC_NETWORK_ASK_RELAY);
+
+	Window *parent = FindWindowById(WC_MAIN_WINDOW, 0);
+	new NetworkAskRelayWindow(&_network_ask_relay_desc, parent, connection_string, token);
+}