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 print = print
  11
  12 local xmlns_compression_feature = "http://jabber.org/features/compress"
  13 local xmlns_compression_protocol = "http://jabber.org/protocol/compress"
  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
  18 -- if not defined assume admin wants best compression
  19 if compression_level == nil then compression_level = 9 end;
  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:add_event_hook("stream-features",
  29                 function (session, features)
  30                         if not session.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
  37 -- TODO Support compression on S2S level too.
  38 module:add_handler("c2s_unauthed", "compress", xmlns_compression_protocol,
  39                 function(session, stanza)
  40                         -- checking if the compression method is supported
  41                         local method = stanza:child_with_name("method")[1];
  42                         if method == "zlib" then
  43                                 session.log("info", method.." compression selected.");
  44                                 session.send(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
  45                                 session:reset_stream();
  46
  47                                 -- create deflate and inflate streams
  48                                 local deflate_stream = zlib.deflate(compression_level);
  49                                 local inflate_stream = zlib.inflate();
  50
  51                                 -- setup compression for session.w
  52                                 local old_send = session.send;
  53
  54                                 session.send = function(t)
  55                                                 local compressed, eof = deflate_stream(tostring(t), 'sync');
  56                                                 old_send(compressed);
  57                                         end;
  58
  59                                 -- setup decompression for session.data
  60                                 local function setup_decompression(session)
  61                                         local old_data = session.data
  62                                         session.data = function(conn, data)
  63                                                         local decompressed, eof = inflate_stream(data);
  64                                                         old_data(conn, decompressed);
  65                                                 end;
  66                                 end
  67                                 setup_decompression(session);
  68
  69                                 local session_reset_stream = session.reset_stream;
  70                                 session.reset_stream = function(session)
  71                                                 session_reset_stream(session);
  72                                                 setup_decompression(session);
  73                                                 return true;
  74                                         end;
  75                                 session.compressed = true;
  76                         else
  77                                 session.log("info", method.." compression selected. But we don't support it.");
  78                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
  79                                 session.send(error_st);
  80                         end
  81                 end
  82 );