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
  17 module:add_event_hook("stream-features",
  18                 function (session, features)
  19                         if not session.compressed then features:add_child(compression_stream_feature); end
  20                 end
  21 );
  22
  23 module:add_handler("c2s_unauthed", "compress", xmlns_compression_protocol,
  24                 function(session, stanza)
  25                         -- checking if the compression method is supported
  26                         local method = stanza:child_with_name("method")[1];
  27                         if method == "zlib" then
  28                                 session.log("info", method.." compression selected.");
  29                                 session.send(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
  30                                 session:reset_stream();
  31
  32                                 -- create deflate and inflate streams
  33                                 local deflate_stream = zlib.deflate(9);
  34                                 local inflate_stream = zlib.inflate();
  35
  36                                 -- setup compression for session.w
  37                                 local old_send = session.send;
  38
  39                                 session.send = function(t)
  40                                                 local compressed, eof = deflate_stream(tostring(t), 'sync');
  41                                                 old_send(compressed);
  42                                         end;
  43
  44                                 -- setup decompression for session.data
  45                                 local function setup_decompression(session)
  46                                         local old_data = session.data
  47                                         session.data = function(conn, data)
  48                                                         local decompressed, eof = inflate_stream(data);
  49                                                         old_data(conn, decompressed);
  50                                                 end;
  51                                 end
  52                                 setup_decompression(session);
  53
  54                                 local session_reset_stream = session.reset_stream;
  55                                 session.reset_stream = function(session)
  56                                                 session_reset_stream(session);
  57                                                 setup_decompression(session);
  58                                                 return true;
  59                                         end;
  60                                 session.compressed = true;
  61                         else
  62                                 session.log("info", method.." compression selected. But we don't support it.");
  63                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
  64                                 session.send(error_st);
  65                         end
  66                 end
  67 );