-- Prosody IM

-- Copyright (C) 2009 Tobias Markmann

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local st = require "util.stanza";

local zlib = require "zlib";

local print = print

local xmlns_compression_feature = "http://jabber.org/features/compress"

local xmlns_compression_protocol = "http://jabber.org/protocol/compress"

local compression_stream_feature = st.stanza("compression", {xmlns=xmlns_compression_feature}):tag("method"):text("zlib"):up();

module:add_event_hook("stream-features",

		function (session, features)

			if not session.compressed then

				features:add_child(compression_stream_feature);

			end

		end

);

module:add_handler("c2s_unauthed", "compress", xmlns_compression_protocol,

		function(session, stanza)

			-- checking if the compression method is supported

			local method = stanza:child_with_name("method")[1];

			if method == "zlib" then

				session.log("info", method.." compression selected.");

				session.send(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));

				session:reset_stream();

				-- create deflate and inflate streams

				local deflate_stream = zlib.deflate(9);

				local inflate_stream = zlib.inflate();

				-- setup compression for session.w

				local old_send = session.send;

				session.send = function(t)

						local compressed, eof = deflate_stream(tostring(t), 'sync');

						old_send(compressed);

					end;

				-- setup decompression for session.data

				local function setup_decompression(session)

					local old_data = session.data

					session.data = function(conn, data)

							local decompressed, eof = inflate_stream(data);

							old_data(conn, decompressed);

						end;

				end

				setup_decompression(session);

				local session_reset_stream = session.reset_stream;

				session.reset_stream = function(session)

						session_reset_stream(session);

						setup_decompression(session);

						return true;

					end;

				session.compressed = true;

			else

				session.log("info", method.." compression selected. But we don't support it.");

				local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");

				session.send(error_st);

			end

		end

);