ClientInterface: add a function to verify (correctly) if user limit was reached (#6258)

* ClientInterface: add a function to verify (correctly) if user limit was reached

CS_HelloSent is a better indicator of active slots than CS_Created, which are session objects created after init packet reception

Switch existing checks to ClientInterface::isUserLimitReached()

Use range-based for loop for getClientIds() used function too

This will fix #6254 (not the memory overhead if init is flooded)

src/clientiface.cpp

@@ -633,6 +633,16 @@ std::vector<u16> ClientInterface::getClientIDs(ClientState min_state)
 	return reply;
 }
 
+/**
+ * Verify if user limit was reached.
+ * User limit count all clients from HelloSent state (MT protocol user) to Active state
+ * @return true if user limit was reached
+ */
+bool ClientInterface::isUserLimitReached()
+{
+	return getClientIDs(CS_HelloSent).size() >= g_settings->getU16("max_users");
+}
+
 void ClientInterface::step(float dtime)
 {
 	m_print_info_timer += dtime;