plugins/mod_compression.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2009 Tobias Markmann
   3 --
   4 -- This project is MIT/X11 licensed. Please see the
   5 -- COPYING file in the source package for more information.
   6 --
   7
   8 local st = require "util.stanza";
   9 local zlib = require "zlib";
  10 local pcall = pcall;
  11 local xmlns_compression_feature = "http://jabber.org/features/compress"
  12 local xmlns_compression_protocol = "http://jabber.org/protocol/compress"
  13 local xmlns_stream = "http://etherx.jabber.org/streams";
  14 local compression_stream_feature = st.stanza("compression", {xmlns=xmlns_compression_feature}):tag("method"):text("zlib"):up();
  15
  16 local compression_level = module:get_option("compression_level");
  17 -- if not defined assume admin wants best compression
  18 if compression_level == nil then compression_level = 9 end;
  19
  20
  21 compression_level = tonumber(compression_level);
  22 if not compression_level or compression_level < 1 or compression_level > 9 then
  23         module:log("warn", "Invalid compression level in config: %s", tostring(compression_level));
  24         module:log("warn", "Module loading aborted. Compression won't be available.");
  25         return;
  26 end
  27
  28 module:hook("stream-features", function(event)
  29         local origin, features = event.origin, event.features;
  30         if not origin.compressed then
  31                 -- FIXME only advertise compression support when TLS layer has no compression enabled
  32                 features:add_child(compression_stream_feature);
  33         end
  34 end);
  35
  36 module:hook("s2s-stream-features", function(event)
  37         local origin, features = event.origin, event.features;
  38         -- FIXME only advertise compression support when TLS layer has no compression enabled
  39         if not origin.compressed then
  40                 features:add_child(compression_stream_feature);
  41         end
  42 end);
  43
  44 -- Hook to activate compression if remote server supports it.
  45 module:hook_stanza(xmlns_stream, "features",
  46                 function (session, stanza)
  47                         if not session.compressed then
  48                                 -- does remote server support compression?
  49                                 local comp_st = stanza:child_with_name("compression");
  50                                 if comp_st then
  51                                         -- do we support the mechanism
  52                                         for a in comp_st:children() do
  53                                                 local algorithm = a[1]
  54                                                 if algorithm == "zlib" then
  55                                                         session.sends2s(st.stanza("compress", {xmlns=xmlns_compression_protocol}):tag("method"):text("zlib"))
  56                                                         session.log("info", "Enabled compression using zlib.")
  57                                                         return true;
  58                                                 end
  59                                         end
  60                                         session.log("debug", "Remote server supports no compression algorithm we support.")
  61                                 end
  62                         end
  63                 end
  64 , 250);
  65
  66
  67 -- returns either nil or a fully functional ready to use inflate stream
  68 local function get_deflate_stream(session)
  69         local status, deflate_stream = pcall(zlib.deflate, compression_level);
  70         if status == false then
  71                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  72                 (session.sends2s or session.send)(error_st);
  73                 session.log("error", "Failed to create zlib.deflate filter.");
  74                 module:log("error", deflate_stream);
  75                 return
  76         end
  77         return deflate_stream
  78 end
  79
  80 -- returns either nil or a fully functional ready to use inflate stream
  81 local function get_inflate_stream(session)
  82         local status, inflate_stream = pcall(zlib.inflate);
  83         if status == false then
  84                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  85                 (session.sends2s or session.send)(error_st);
  86                 session.log("error", "Failed to create zlib.deflate filter.");
  87                 module:log("error", inflate_stream);
  88                 return
  89         end
  90         return inflate_stream
  91 end
  92
  93 -- setup compression for a stream
  94 local function setup_compression(session, deflate_stream)
  95         local old_send = (session.sends2s or session.send);
  96
  97         local new_send = function(t)
  98                         --TODO: Better code injection in the sending process
  99                         session.log(t)
 100                         local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
 101                         if status == false then
 102                                 session:close({
 103                                         condition = "undefined-condition";
 104                                         text = compressed;
 105                                         extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 106                                 });
 107                                 module:log("warn", compressed);
 108                                 return;
 109                         end
 110                         session.conn:write(compressed);
 111                 end;
 112
 113         if session.sends2s then session.sends2s = new_send
 114         elseif session.send then session.send = new_send end
 115 end
 116
 117 -- setup decompression for a stream
 118 local function setup_decompression(session, inflate_stream)
 119         local old_data = session.data
 120         session.data = function(conn, data)
 121                         local status, decompressed, eof = pcall(inflate_stream, data);
 122                         if status == false then
 123                                 session:close({
 124                                         condition = "undefined-condition";
 125                                         text = decompressed;
 126                                         extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 127                                 });
 128                                 module:log("warn", decompressed);
 129                                 return;
 130                         end
 131                         old_data(conn, decompressed);
 132                 end;
 133 end
 134
 135 module:add_handler({"s2sout_unauthed", "s2sout"}, "compressed", xmlns_compression_protocol,
 136                 function(session ,stanza)
 137                         session.log("debug", "Activating compression...")
 138                         -- create deflate and inflate streams
 139                         local deflate_stream = get_deflate_stream(session);
 140                         if not deflate_stream then return end
 141
 142                         local inflate_stream = get_inflate_stream(session);
 143                         if not inflate_stream then return end
 144
 145                         -- setup compression for session.w
 146                         setup_compression(session, deflate_stream);
 147
 148                         -- setup decompression for session.data
 149                         setup_decompression(session, inflate_stream);
 150                         local session_reset_stream = session.reset_stream;
 151                         session.reset_stream = function(session)
 152                                         session_reset_stream(session);
 153                                         setup_decompression(session, inflate_stream);
 154                                         return true;
 155                                 end;
 156                         session:reset_stream();
 157                         local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
 158                                                                                 ["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
 159                         session.sends2s("<?xml version='1.0'?>");
 160                         session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
 161                         session.compressed = true;
 162                 end
 163 );
 164
 165 module:add_handler({"c2s_unauthed", "c2s", "s2sin_unauthed", "s2sin"}, "compress", xmlns_compression_protocol,
 166                 function(session, stanza)
 167                         -- fail if we are already compressed
 168                         if session.compressed then
 169                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 170                                 (session.sends2s or session.send)(error_st);
 171                                 session.log("warn", "Tried to establish another compression layer.");
 172                         end
 173
 174                         -- checking if the compression method is supported
 175                         local method = stanza:child_with_name("method")[1];
 176                         if method == "zlib" then
 177                                 session.log("debug", method.." compression selected.");
 178
 179                                 -- create deflate and inflate streams
 180                                 local deflate_stream = get_deflate_stream(session);
 181                                 if not deflate_stream then return end
 182
 183                                 local inflate_stream = get_inflate_stream(session);
 184                                 if not inflate_stream then return end
 185
 186                                 (session.sends2s or session.send)(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
 187                                 session:reset_stream();
 188
 189                                 -- setup compression for session.w
 190                                 setup_compression(session, deflate_stream);
 191
 192                                 -- setup decompression for session.data
 193                                 setup_decompression(session, inflate_stream);
 194
 195                                 local session_reset_stream = session.reset_stream;
 196                                 session.reset_stream = function(session)
 197                                                 session_reset_stream(session);
 198                                                 setup_decompression(session, inflate_stream);
 199                                                 return true;
 200                                         end;
 201                                 session.compressed = true;
 202                         else
 203                                 session.log("warn", method.." compression selected. But we don't support it.");
 204                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 205                                 (session.sends2s or session.send)(error_st);
 206                         end
 207                 end
 208 );
 209