mod_http_oauth2: Fix use of arbitrary ports in loopback redirect URIs Per draft-ietf-oauth-v2-1-08#section-8.4.2 > The authorization server MUST allow any port to be specified at the > time of the request for loopback IP redirect URIs, to accommodate > clients that obtain an available ephemeral port from the operating > system at the time of the request. Uncertain if it should normalize the host part, but it also seems harmless to treat IPv6 and IPv4 the same here. One thing is that "localhost" is NOT RECOMMENDED because it can sometimes be pointed to non-loopback interfaces via DNS or hosts file.

local st = require "util.stanza";

local whitelist = module:get_option_inherited_set("s2s_whitelist", {});

module:hook("route/remote", function (event)
	if not whitelist:contains(event.to_host) then
		module:send(st.error_reply(event.stanza, "cancel", "not-allowed", "Communication with this domain is restricted"));
		return true;
	end
end, 100);

module:hook("s2s-stream-features", function (event)
	if not whitelist:contains(event.origin.from_host) then
		event.origin:close({
			condition = "policy-violation";
			text = "Communication with this domain is restricted";
		});
	end
end, 1000);