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-- 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 pcall = pcall;
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_stream_feature = st.stanza("compression", {xmlns=xmlns_compression_feature}):tag("method"):text("zlib"):up();
local compression_level = module:get_option("compression_level");
-- if not defined assume admin wants best compression
if compression_level == nil then compression_level = 9 end;
compression_level = tonumber(compression_level);
if not compression_level or compression_level < 1 or compression_level > 9 then
module:log("warn", "Invalid compression level in config: %s", tostring(compression_level));
module:log("warn", "Module loading aborted. Compression won't be available.");
return;
end
module:add_event_hook("stream-features",
function (session, features)
if not session.compressed then
-- FIXME only advertise compression support when TLS layer has no compression enabled
features:add_child(compression_stream_feature);
end
end
);
module:hook("s2s-stream-features",
function (data)
local session, features = data.session, data.features;
-- FIXME only advertise compression support when TLS layer has no compression enabled
if not session.compressed then
features:add_child(compression_stream_feature);
end
end
);
-- Hook to activate compression if remote server supports it.
module:hook_stanza(xmlns_stream, "features",
function (session, stanza)
if not session.compressed then
-- does remote server support compression?
local comp_st = stanza: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
session.sends2s(st.stanza("compress", {xmlns=xmlns_compression_protocol}):tag("method"):text("zlib"))
session.log("info", "Enabled compression using zlib.")
return true;
end
end
session.log("debug", "Remote server supports no compression algorithm we support.")
end
end
end
, 250);
-- 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 = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
(session.sends2s or session.send)(error_st);
session.log("error", "Failed to create zlib.deflate filter.");
module:log("error", 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 = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
(session.sends2s or session.send)(error_st);
session.log("error", "Failed to create zlib.deflate filter.");
module:log("error", inflate_stream);
return
end
return inflate_stream
end
-- setup compression for a stream
local function setup_compression(session, deflate_stream)
local old_send = (session.sends2s or session.send);
local new_send = function(t)
--TODO: Better code injection in the sending process
session.log(t)
local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
if status == false then
session:close({
condition = "undefined-condition";
text = compressed;
extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
});
module:log("warn", compressed);
return;
end
session.conn:write(compressed);
end;
if session.sends2s then session.sends2s = new_send
elseif session.send then session.send = new_send end
end
-- setup decompression for a stream
local function setup_decompression(session, inflate_stream)
local old_data = session.data
session.data = function(conn, data)
local status, decompressed, eof = pcall(inflate_stream, data);
if status == false then
session:close({
condition = "undefined-condition";
text = decompressed;
extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
});
module:log("warn", decompressed);
return;
end
old_data(conn, decompressed);
end;
end
module:add_handler({"s2sout_unauthed", "s2sout"}, "compressed", xmlns_compression_protocol,
function(session ,stanza)
session.log("debug", "Activating compression...")
-- create deflate and inflate streams
deflate_stream = get_deflate_stream(session);
if not deflate_stream then return end
inflate_stream = get_inflate_stream(session);
if not inflate_stream then return end
-- setup compression for session.w
setup_compression(session, deflate_stream);
-- setup decompression for session.data
setup_decompression(session, inflate_stream);
local session_reset_stream = session.reset_stream;
session.reset_stream = function(session)
session_reset_stream(session);
setup_decompression(session, inflate_stream);
return true;
end;
session:reset_stream();
local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
session.sends2s("<?xml version='1.0'?>");
session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
session.compressed = true;
end
);
module:add_handler({"c2s_unauthed", "c2s", "s2sin_unauthed", "s2sin"}, "compress", xmlns_compression_protocol,
function(session, stanza)
-- fail if we are already compressed
if session.compressed then
local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
(session.sends2s or session.send)(error_st);
session.log("warn", "Tried to establish another compression layer.");
end
-- 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.");
-- create deflate and inflate streams
deflate_stream = get_deflate_stream(session);
if not deflate_stream then return end
inflate_stream = get_inflate_stream(session);
if not inflate_stream then return end
(session.sends2s or session.send)(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
session:reset_stream();
-- setup compression for session.w
setup_compression(session, deflate_stream);
-- setup decompression for session.data
setup_decompression(session, inflate_stream);
local session_reset_stream = session.reset_stream;
session.reset_stream = function(session)
session_reset_stream(session);
setup_decompression(session, inflate_stream);
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.sends2s or session.send)(error_st);
end
end
);
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