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"}, "compress", xmlns_compression_protocol,
  39                 function(session, stanza)
  40                         -- fail if we are already compressed
  41                         if session.compressed then
  42                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
  43                                 session.send(error_st);
  44                                 session:log("warn", "Tried to establish another compression layer.");
  45                         end
  46
  47                         -- checking if the compression method is supported
  48                         local method = stanza:child_with_name("method")[1];
  49                         if method == "zlib" then
  50                                 session.log("info", method.." compression selected.");
  51                                 session.send(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
  52                                 session:reset_stream();
  53
  54                                 -- create deflate and inflate streams
  55                                 local status, deflate_stream = pcall(zlib.deflate, compression_level);
  56                                 if status == false then
  57                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  58                                         session.send(error_st);
  59                                         session:log("error", "Failed to create zlib.deflate filter.");
  60                                         module:log("error", deflate_stream);
  61                                         return
  62                                 end
  63
  64                                 local status, inflate_stream = pcall(zlib.inflate);
  65                                 if status == false then
  66                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  67                                         session.send(error_st);
  68                                         session:log("error", "Failed to create zlib.deflate filter.");
  69                                         module:log("error", inflate_stream);
  70                                         return
  71                                 end
  72
  73                                 -- setup compression for session.w
  74                                 local old_send = session.send;
  75
  76                                 session.send = function(t)
  77                                                 local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
  78                                                 if status == false then
  79                                                         session:close({
  80                                                                 condition = "undefined-condition";
  81                                                                 text = compressed;
  82                                                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
  83                                                         });
  84                                                         module:log("warn", compressed);
  85                                                         return;
  86                                                 end
  87                                                 old_send(compressed);
  88                                         end;
  89
  90                                 -- setup decompression for session.data
  91                                 local function setup_decompression(session)
  92                                         local old_data = session.data
  93                                         session.data = function(conn, data)
  94                                                         local status, decompressed, eof = pcall(inflate_stream, data);
  95                                                         if status == false then
  96                                                                 session:close({
  97                                                                         condition = "undefined-condition";
  98                                                                         text = decompressed;
  99                                                                         extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 100                                                                 });
 101                                                                 module:log("warn", decompressed);
 102                                                                 return;
 103                                                         end
 104                                                         old_data(conn, decompressed);
 105                                                 end;
 106                                 end
 107                                 setup_decompression(session);
 108
 109                                 local session_reset_stream = session.reset_stream;
 110                                 session.reset_stream = function(session)
 111                                                 session_reset_stream(session);
 112                                                 setup_decompression(session);
 113                                                 return true;
 114                                         end;
 115                                 session.compressed = true;
 116                         else
 117                                 session.log("info", method.." compression selected. But we don't support it.");
 118                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 119                                 session.send(error_st);
 120                         end
 121                 end
 122 );