--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_auto_answer_disco_info/README.markdown	Wed Mar 07 17:11:49 2018 +0100
@@ -0,0 +1,10 @@
+---
+summary: Answers disco#info queries on the behalf of the recipient
+---
+
+Description
+===========
+
+This module intercepts disco#info queries and checks if we already know the
+capabilities of this session, in which case we don’t transmit the iq and answer
+it ourselves.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_auto_answer_disco_info/mod_auto_answer_disco_info.lua	Wed Mar 07 17:11:49 2018 +0100
@@ -0,0 +1,28 @@
+module:depends("cache_c2s_caps");
+
+local st = require "util.stanza";
+
+local function iq_stanza_handler(event)
+	local origin, stanza = event.origin, event.stanza;
+	local type = stanza.attr.type;
+
+	local query = stanza:get_child("query", "http://jabber.org/protocol/disco#info");
+	if type ~= "get" or query == nil then
+		return;
+	end
+
+	local to = stanza.attr.to;
+	local node = query.attr.node;
+
+	local target_session = full_sessions[to];
+	local disco_info = target_session.caps_cache;
+	if disco_info ~= nil and (node == nil or node == disco_info.attr.node) then
+		local iq = st.reply(stanza);
+		iq:add_child(st.clone(disco_info));
+		module:log("debug", "Answering disco#info on the behalf of the recipient")
+		module:send(iq);
+		return true;
+	end
+end
+
+module:hook("iq/full", iq_stanza_handler, 1);