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
  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", "c2s_authed"}, "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 status, deflate_stream = pcall(zlib.deflate, compression_level);
  49                                 if status == false then
  50                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  51                                         session.send(error_st);
  52                                         session:log("error", "Failed to create zlib.deflate filter.");
  53                                         module:log("error", deflate_stream);
  54                                         return
  55                                 end
  56
  57                                 local status, inflate_stream = pcall(zlib.inflate);
  58                                 if status == false then
  59                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  60                                         session.send(error_st);
  61                                         session:log("error", "Failed to create zlib.deflate filter.");
  62                                         module:log("error", inflate_stream);
  63                                         return
  64                                 end
  65
  66                                 -- setup compression for session.w
  67                                 local old_send = session.send;
  68
  69                                 session.send = function(t)
  70                                                 local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
  71                                                 if status == false then
  72                                                         session:close({
  73                                                                 condition = "undefined-condition";
  74                                                                 text = compressed;
  75                                                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
  76                                                         });
  77                                                         module:log("error", compressed);
  78                                                         return;
  79                                                 end
  80                                                 old_send(compressed);
  81                                         end;
  82
  83                                 -- setup decompression for session.data
  84                                 local function setup_decompression(session)
  85                                         local old_data = session.data
  86                                         session.data = function(conn, data)
  87                                                         local status, decompressed, eof = pcall(inflate_stream, data);
  88                                                         if status == false then
  89                                                                 session:close({
  90                                                                         condition = "undefined-condition";
  91                                                                         text = decompressed;
  92                                                                         extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
  93                                                                 });
  94                                                                 module:log("error", decompressed);
  95                                                                 return;
  96                                                         end
  97                                                         old_data(conn, decompressed);
  98                                                 end;
  99                                 end
 100                                 setup_decompression(session);
 101
 102                                 local session_reset_stream = session.reset_stream;
 103                                 session.reset_stream = function(session)
 104                                                 session_reset_stream(session);
 105                                                 setup_decompression(session);
 106                                                 return true;
 107                                         end;
 108                                 session.compressed = true;
 109                         else
 110                                 session.log("info", method.." compression selected. But we don't support it.");
 111                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 112                                 session.send(error_st);
 113                         end
 114                 end
 115 );