HttpService/Frontend improvements (#782)

- zenhttp: added `GetServiceUri()`/`GetExternalHost()`
  - enables code to quickly generate an externally reachable URI for a given service
- frontend: improved Uri handling (better defaults)
  - added support for 404 page (to make it easier to find a good URL)

1 files changed, 16 insertions, 0 deletions

diff --git a/src/zenhttp/include/zenhttp/httpserver.h b/src/zenhttp/include/zenhttp/httpserver.h
index 350532126..00cbc6c14 100644
--- a/src/zenhttp/include/zenhttp/httpserver.h
+++ b/src/zenhttp/include/zenhttp/httpserver.h
@@ -219,8 +219,21 @@ public:
 	void RequestExit();
 	void Close();
 
+	/** Returns a canonical http:// URI for the given service, using the external
+	 *  IP and the port the server is actually listening on. Only valid
+	 *  after Initialize() has returned successfully.
+	 */
+	std::string GetServiceUri(const HttpService* Service) const;
+
+	/** Returns the external host string (IP or hostname) determined during Initialize().
+	 *  Only valid after Initialize() has returned successfully.
+	 */
+	std::string_view GetExternalHost() const { return m_ExternalHost; }
+
 private:
 	std::vector<HttpService*> m_KnownServices;
+	int						  m_EffectivePort = 0;
+	std::string				  m_ExternalHost;
 
 	virtual void OnRegisterService(HttpService& Service)				   = 0;
 	virtual int	 OnInitialize(int BasePort, std::filesystem::path DataDir) = 0;
@@ -228,6 +241,9 @@ private:
 	virtual void OnRun(bool IsInteractiveSession)						   = 0;
 	virtual void OnRequestExit()										   = 0;
 	virtual void OnClose()												   = 0;
+
+protected:
+	virtual std::string OnGetExternalHost() const;
 };
 
 struct HttpServerPluginConfig