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-- Prosody IM
-- Copyright (C) 2009-2012 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 tostring = tostring;
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 add_filter = require "util.filters".add_filter;
local compression_level = module:get_option_number("compression_level", 7);
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:hook("stream-features", function(event)
local origin, features = event.origin, event.features;
if not origin.compressed and origin.type == "c2s" 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(event)
local origin, features = event.origin, event.features;
-- FIXME only advertise compression support when TLS layer has no compression enabled
if not origin.compressed and origin.type == "s2sin" 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 and session.type == "s2sout" 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("debug", "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", "%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 = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
(session.sends2s or session.send)(error_st);
session.log("error", "Failed to create zlib.inflate filter.");
module:log("error", "%s", tostring(inflate_stream));
return
end
return inflate_stream
end
-- setup compression for a stream
local function setup_compression(session, deflate_stream)
add_filter(session, "bytes/out", function(t)
local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
if status == false then
module:log("warn", "%s", tostring(compressed));
session:close({
condition = "undefined-condition";
text = compressed;
extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
});
return;
end
return compressed;
end);
end
-- setup decompression for a stream
local function setup_decompression(session, inflate_stream)
add_filter(session, "bytes/in", function(data)
local status, decompressed, eof = pcall(inflate_stream, data);
if status == false then
module:log("warn", "%s", tostring(decompressed));
session:close({
condition = "undefined-condition";
text = decompressed;
extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
});
return;
end
return decompressed;
end);
end
module:hook("stanza/http://jabber.org/protocol/compress:compressed", function(event)
local session = event.origin;
if session.type == "s2sout" then
session.log("debug", "Activating compression...")
-- create deflate and inflate streams
local deflate_stream = get_deflate_stream(session);
if not deflate_stream then return true; end
local inflate_stream = get_inflate_stream(session);
if not inflate_stream then return true; end
-- setup compression for session.w
setup_compression(session, deflate_stream);
-- setup decompression for session.data
setup_decompression(session, inflate_stream);
session:reset_stream();
session:open_stream(session.from_host, session.to_host);
session.compressed = true;
return true;
end
end);
module:hook("stanza/http://jabber.org/protocol/compress:compress", function(event)
local session, stanza = event.origin, event.stanza;
if session.type == "c2s" or session.type == "s2sin" then
-- fail if we are already compressed
if session.compressed then
local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
(session.sends2s or session.send)(error_st);
session.log("debug", "Client tried to establish another compression layer.");
return true;
end
-- checking if the compression method is supported
local method = stanza:child_with_name("method");
method = method and (method[1] or "");
if method == "zlib" then
session.log("debug", "zlib compression enabled.");
-- create deflate and inflate streams
local deflate_stream = get_deflate_stream(session);
if not deflate_stream then return true; end
local inflate_stream = get_inflate_stream(session);
if not inflate_stream then return true; 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);
session.compressed = true;
elseif method then
session.log("debug", "%s compression selected, but we don't support it.", tostring(method));
local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
(session.sends2s or session.send)(error_st);
else
(session.sends2s or session.send)(st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed"));
end
return true;
end
end);
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