mod_http: Allow disabling CORS in the http_cors_override option and by default

Fixes #1779.

Due to an oversight in the logic, if the user set 'enabled' to false in an
override, it would disable the item's requested CORS settings, but still apply
Prosody's default CORS policy.

This change ensures that 'enabled = false' will now disable CORS entirely for
the requested item.

Due to the new structure of the code, it was necessary to have a flag to say
whether CORS is to be applied at all. Rather than hard-coding 'true' here, I
chose to add a new option: 'http_default_cors_enabled'. This is a boolean that
allows the operator to disable Prosody's default CORS policy entirely (the one
that is used when a module or config does not override it). This makes it
easier to disable CORS and then selectively enable it only on services you
want it on.

1 files changed, 11 insertions, 4 deletions

diff --git a/plugins/mod_http.lua b/plugins/mod_http.lua
index b26adb1c..66012239 100644
--- a/plugins/mod_http.lua
+++ b/plugins/mod_http.lua
@@ -37,6 +37,7 @@ local opt_headers = module:get_option_set("access_control_allow_headers", { "Con
 local opt_origins = module:get_option_set("access_control_allow_origins");
 local opt_credentials = module:get_option_boolean("access_control_allow_credentials", false);
 local opt_max_age = module:get_option_number("access_control_max_age", 2 * 60 * 60);
+local opt_default_cors = module:get_option_boolean("http_default_cors_enabled", true);
 
 local function get_http_event(host, app_path, key)
 	local method, path = key:match("^(%S+)%s+(.+)$");
@@ -183,7 +184,11 @@ function module.add_host(module)
 						app_origins = set.new(cors.origins)._items;
 					end
 				end
+			elseif cors.enabled == false then
+				cors = nil;
 			end
+		else
+			cors = opt_default_cors;
 		end
 
 		local streaming = event.item.streaming_uploads;
@@ -228,12 +233,14 @@ function module.add_host(module)
 				if not app_handlers[event_name] then
 					app_handlers[event_name] = {
 						main = handler;
-						cors = cors_handler;
-						options = options_handler;
+						cors = cors and cors_handler;
+						options = cors and options_handler;
 					};
 					module:hook_object_event(server, event_name, handler);
-					module:hook_object_event(server, event_name, cors_handler, 1);
-					module:hook_object_event(server, options_event_name, options_handler, -1);
+					if cors then
+						module:hook_object_event(server, event_name, cors_handler, 1);
+						module:hook_object_event(server, options_event_name, options_handler, -1);
+					end
 				else
 					module:log("warn", "App %s added handler twice for '%s', ignoring", app_name, event_name);
 				end