--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_smacks/mod_smacks.lua	Thu Jun 03 01:08:58 2010 +0100
@@ -0,0 +1,123 @@
+local st = require "util.stanza";
+
+local t_insert, t_remove = table.insert, table.remove;
+local tonumber, tostring = tonumber, tostring;
+
+local xmlns_sm = "urn:xmpp:sm:2";
+
+local sm_attr = { xmlns = xmlns_sm };
+
+module:add_event_hook("stream-features",
+		function (session, features)
+			features:tag("sm", sm_attr):tag("optional"):up():up();
+		end);
+
+module:hook("s2s-stream-features",
+		function (data)
+			data.features:tag("sm", sm_attr):tag("optional"):up():up();
+		end);
+
+module:hook_stanza(xmlns_sm, "enable",
+		function (session, stanza)
+			module:log("debug", "Enabling stream management");
+			session.smacks = true;
+			session.handled_stanza_count = 0;
+			-- Overwrite process_stanza() and send()
+			local queue, queue_length = {}, 0;
+			session.outgoing_stanza_queue, session.outgoing_stanza_count = queue, queue_length;
+			local _send = session.send;
+			function session.send(stanza)
+				local attr = stanza.attr;
+				if attr and not attr.xmlns then -- Stanza in default stream namespace
+					queue_length = queue_length + 1;
+					session.outgoing_stanza_count = queue_length;
+					queue[queue_length] = st.reply(stanza);
+				end
+				local ok, err = _send(stanza);
+				if ok then
+					return _send(st.stanza("r", { xmlns = xmlns_sm }));
+				end
+				return ok, err;
+			end
+			_send(st.stanza("enabled", sm_attr));
+			return true;
+		end);
+
+module:hook_stanza(xmlns_sm, "r", function (origin, stanza)
+	if not origin.smacks then
+		module:log("debug", "Received ack request from non-smack-enabled session");
+		return;
+	end
+	module:log("debug", "Received ack request, acking for %d", origin.handled_stanza_count);
+	-- Reply with <a>
+	origin.send(st.stanza("a", { xmlns = xmlns_sm, h = tostring(origin.handled_stanza_count) }));
+	return true;
+end);
+
+module:hook_stanza(xmlns_sm, "a", function (origin, stanza)
+	if not origin.smacks then return; end
+	
+	-- Remove handled stanzas from outgoing_stanza_queue
+	local handled_stanza_count = tonumber(stanza.attr.h)+1;
+	for i=1,handled_stanza_count do
+		t_remove(origin.outgoing_stanza_queue, 1);
+	end
+	return true;
+end);
+
+--TODO: Optimise... incoming stanzas should be handled by a per-session
+-- function that has a counter as an upvalue (no table indexing for increments,
+-- and won't slow non-198 sessions). We can also then remove the .handled flag
+-- on stanzas
+
+function catch_all_incoming_stanzas(data)
+	local origin, stanza = data.origin, data.stanza;
+	if origin.smacks and not stanza.handled then
+		stanza.handled = true;
+		origin.handled_stanza_count = origin.handled_stanza_count + 1;
+		module:log("debug", "Handled %d stanzas", origin.handled_stanza_count);
+	end
+end
+module:hook("message/bare", catch_all_incoming_stanzas, 1000);
+module:hook("message/full", catch_all_incoming_stanzas, 1000);
+module:hook("message/host", catch_all_incoming_stanzas, 1000);
+
+module:hook("presence/bare", catch_all_incoming_stanzas, 1000);
+module:hook("presence/full", catch_all_incoming_stanzas, 1000);
+module:hook("presence/host", catch_all_incoming_stanzas, 1000);
+
+module:hook("iq/bare", catch_all_incoming_stanzas, 1000);
+module:hook("iq/full", catch_all_incoming_stanzas, 1000);
+module:hook("iq/host", catch_all_incoming_stanzas, 1000);
+
+function handle_unacked_stanzas(session)
+	local queue = session.outgoing_stanza_queue;
+	local error_attr = { type = "cancel" };
+	if #queue > 0 then
+		for i=1,#queue do
+			local reply = queue[i];
+			if reply.attr.to ~= session.full_jid then
+				reply.attr.type = "error";
+				reply:tag("error", error_attr)
+					:tag("recipient-unavailable", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"});
+				core_process_stanza(session, queue[i]);
+			end
+			queue[i] = nil;
+		end
+	end
+end
+
+local _destroy_session = sessionmanager.destroy_session;
+function sessionmanager.destroy_session(session, err)
+	if session.smacks then
+		local queue = session.outgoing_stanza_queue;
+		if #queue > 0 then
+			module:log("warn", "Destroying session with %d unacked stanzas:", #queue);
+			for i=1,#queue do
+				module:log("warn", "::%s", tostring(queue[i]));
+			end
+			handle_unacked_stanzas(session);
+		end
+	end
+	return _destroy_session(session, err);
+end