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mod_xxxx/verse/plugins/compression.lua

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2015-11-25 13:42:19 -05:00
-- Copyright (C) 2009-2010 Matthew Wild
-- Copyright (C) 2009-2010 Tobias Markmann
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
local verse = require "verse";
local zlib = require "zlib";
local xmlns_compression_feature = "http://jabber.org/features/compress"
local xmlns_compression_protocol = "http://jabber.org/protocol/compress"
local xmlns_stream = "http://etherx.jabber.org/streams";
local compression_level = 9;
-- returns either nil or a fully functional ready to use inflate stream
local function get_deflate_stream(session)
local status, deflate_stream = pcall(zlib.deflate, compression_level);
if status == false then
local error_st = verse.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
session:send(error_st);
session:error("Failed to create zlib.deflate filter: %s", tostring(deflate_stream));
return
end
return deflate_stream
end
-- returns either nil or a fully functional ready to use inflate stream
local function get_inflate_stream(session)
local status, inflate_stream = pcall(zlib.inflate);
if status == false then
local error_st = verse.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
session:send(error_st);
session:error("Failed to create zlib.inflate filter: %s", tostring(inflate_stream));
return
end
return inflate_stream
end
-- setup compression for a stream
local function setup_compression(session, deflate_stream)
function session:send(t)
--TODO: Better code injection in the sending process
local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
if status == false then
session:close({
condition = "undefined-condition";
text = compressed;
extra = verse.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("processing-failed");
});
session:warn("Compressed send failed: %s", tostring(compressed));
return;
end
session.conn:write(compressed);
end;
end
-- setup decompression for a stream
local function setup_decompression(session, inflate_stream)
local old_data = session.data
session.data = function(conn, data)
session:debug("Decompressing data...");
local status, decompressed, eof = pcall(inflate_stream, data);
if status == false then
session:close({
condition = "undefined-condition";
text = decompressed;
extra = verse.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("processing-failed");
});
stream:warn("%s", tostring(decompressed));
return;
end
return old_data(conn, decompressed);
end;
end
function verse.plugins.compression(stream)
local function handle_features(features)
if not stream.compressed then
-- does remote server support compression?
local comp_st = features:child_with_name("compression");
if comp_st then
-- do we support the mechanism
for a in comp_st:children() do
local algorithm = a[1]
if algorithm == "zlib" then
stream:send(verse.stanza("compress", {xmlns=xmlns_compression_protocol}):tag("method"):text("zlib"))
stream:debug("Enabled compression using zlib.")
return true;
end
end
session:debug("Remote server supports no compression algorithm we support.")
end
end
end
local function handle_compressed(stanza)
if stanza.name == "compressed" then
stream:debug("Activating compression...")
-- create deflate and inflate streams
local deflate_stream = get_deflate_stream(stream);
if not deflate_stream then return end
local inflate_stream = get_inflate_stream(stream);
if not inflate_stream then return end
-- setup compression for stream.w
setup_compression(stream, deflate_stream);
-- setup decompression for stream.data
setup_decompression(stream, inflate_stream);
stream.compressed = true;
stream:reopen();
elseif stanza.name == "failure" then
stream:warn("Failed to establish compression");
end
end
stream:hook("stream-features", handle_features, 250);
stream:hook("stream/"..xmlns_compression_protocol, handle_compressed);
end