--- a/core/modulemanager.lua	Sat Sep 07 18:54:59 2019 +0200
+++ b/core/modulemanager.lua	Sun Sep 08 19:45:39 2019 +0200
@@ -24,7 +24,7 @@
 local ipairs, pairs, type, t_insert = ipairs, pairs, type, table.insert;
 
 local autoload_modules = {prosody.platform, "presence", "message", "iq", "offline", "c2s", "s2s", "s2s_auth_certs"};
-local component_inheritable_modules = {"tls", "saslauth", "dialback", "iq", "s2s"};
+local component_inheritable_modules = {"tls", "saslauth", "dialback", "iq", "s2s", "s2s_bidi"};
 
 -- We need this to let modules access the real global namespace
 local _G = _G;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/mod_s2s_bidi.lua	Sun Sep 08 19:45:39 2019 +0200
@@ -0,0 +1,38 @@
+-- Prosody IM
+-- Copyright (C) 2019 Kim Alvefur
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+local st = require "util.stanza";
+
+local xmlns_bidi_feature = "urn:xmpp:features:bidi"
+local xmlns_bidi = "urn:xmpp:bidi";
+
+module:hook("s2s-stream-features", function(event)
+	local origin, features = event.origin, event.features;
+	if origin.type == "s2sin_unauthed" then
+		features:tag("bidi", { xmlns = xmlns_bidi_feature }):up();
+	end
+end);
+
+module:hook_tag("http://etherx.jabber.org/streams", "features", function (session, stanza)
+	if session.type == "s2sout_unauthed" then
+		local bidi = stanza:get_child("bidi", xmlns_bidi_feature);
+		if bidi then
+			session.incoming = true;
+			session.log("debug", "Requesting bidirectional stream");
+			session.sends2s(st.stanza("bidi", { xmlns = xmlns_bidi }));
+		end
+	end
+end, 200);
+
+module:hook_tag("urn:xmpp:bidi", "bidi", function(session)
+	if session.type == "s2sin_unauthed" then
+		session.log("debug", "Requested bidirectional stream");
+		session.outgoing = true;
+		return true;
+	end
+end);
+