CSM: Use server-like (and safe) HTTP API instead of Mainmenu-like

builtin/client/util.lua

@@ -58,3 +58,23 @@ end
 function core.get_nearby_objects(radius)
 	return core.get_objects_inside_radius(core.localplayer:get_pos(), radius)
 end
+
+-- HTTP callback interface
+
+function core.http_add_fetch(httpenv)
+	httpenv.fetch = function(req, callback)
+		local handle = httpenv.fetch_async(req)
+
+		local function update_http_status()
+			local res = httpenv.fetch_async_get(handle)
+			if res.completed then
+				callback(res)
+			else
+				core.after(0, update_http_status)
+			end
+		end
+		core.after(0, update_http_status)
+	end
+
+	return httpenv
+end

src/script/lua_api/l_http.cpp

@@ -239,8 +239,18 @@ int ModApiHttp::l_get_http_api(lua_State *L)
 void ModApiHttp::Initialize(lua_State *L, int top)
 {
 #if USE_CURL
-	API_FCT(get_http_api);
-	API_FCT(request_http_api);
+
+	bool isMainmenu = false;
+#ifndef SERVER
+	isMainmenu = ModApiBase::getGuiEngine(L) != nullptr;
+#endif
+
+	if (isMainmenu) {
+		API_FCT(get_http_api);
+	} else {
+		API_FCT(request_http_api);
+	}
+
 #endif
 }