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 tostring = tostring;
  12
  13 local xmlns_compression_feature = "http://jabber.org/features/compress"
  14 local xmlns_compression_protocol = "http://jabber.org/protocol/compress"
  15 local compression_stream_feature = st.stanza("compression", {xmlns=xmlns_compression_feature}):tag("method"):text("zlib"):up();
  16
  17 local compression_level = module:get_option("compression_level");
  18 -- if not defined assume admin wants best compression
  19 if compression_level == nil then compression_level = 9 end;
  20
  21
  22 compression_level = tonumber(compression_level);
  23 if not compression_level or compression_level < 1 or compression_level > 9 then
  24         module:log("warn", "Invalid compression level in config: %s", tostring(compression_level));
  25         module:log("warn", "Module loading aborted. Compression won't be available.");
  26         return;
  27 end
  28
  29 module:add_event_hook("stream-features",
  30                 function (session, features)
  31                         if not session.compressed then
  32                                 -- FIXME only advertise compression support when TLS layer has no compression enabled
  33                                 features:add_child(compression_stream_feature);
  34                         end
  35                 end
  36 );
  37
  38 -- TODO Support compression on S2S level too.
  39 module:add_handler({"c2s_unauthed", "c2s"}, "compress", xmlns_compression_protocol,
  40                 function(session, stanza)
  41                         -- fail if we are already compressed
  42                         if session.compressed then
  43                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  44                                 session.send(error_st);
  45                                 session.log("warn", "Tried to establish another compression layer.");
  46                                 return;
  47                         end
  48
  49                         -- checking if the compression method is supported
  50                         local method = stanza:child_with_name("method");
  51                         method = method and (method[1] or "");
  52                         if method == "zlib" then
  53                                 -- create deflate and inflate streams
  54                                 local status, deflate_stream = pcall(zlib.deflate, compression_level);
  55                                 if status == false then
  56                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  57                                         session.send(error_st);
  58                                         session.log("error", "Failed to create zlib.deflate filter.");
  59                                         module:log("error", "%s", tostring(deflate_stream));
  60                                         return
  61                                 end
  62
  63                                 local status, inflate_stream = pcall(zlib.inflate);
  64                                 if status == false then
  65                                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  66                                         session.send(error_st);
  67                                         session.log("error", "Failed to create zlib.inflate filter.");
  68                                         module:log("error", "%s", tostring(inflate_stream));
  69                                         return
  70                                 end
  71
  72                                 session.log("info", method.." compression selected.");
  73                                 session.send(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
  74                                 session:reset_stream();
  75
  76                                 -- setup compression for session.w
  77                                 local old_send = session.send;
  78
  79                                 session.send = function(t)
  80                                                 local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
  81                                                 if status == false then
  82                                                         session:close({
  83                                                                 condition = "undefined-condition";
  84                                                                 text = compressed;
  85                                                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
  86                                                         });
  87                                                         module:log("warn", "%s", tostring(compressed));
  88                                                         return;
  89                                                 end
  90                                                 old_send(compressed);
  91                                         end;
  92
  93                                 -- setup decompression for session.data
  94                                 local function setup_decompression(session)
  95                                         local old_data = session.data
  96                                         session.data = function(conn, data)
  97                                                         local status, decompressed, eof = pcall(inflate_stream, data);
  98                                                         if status == false then
  99                                                                 session:close({
 100                                                                         condition = "undefined-condition";
 101                                                                         text = decompressed;
 102                                                                         extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 103                                                                 });
 104                                                                 module:log("warn", "%s", tostring(decompressed));
 105                                                                 return;
 106                                                         end
 107                                                         old_data(conn, decompressed);
 108                                                 end;
 109                                 end
 110                                 setup_decompression(session);
 111
 112                                 local session_reset_stream = session.reset_stream;
 113                                 session.reset_stream = function(session)
 114                                                 session_reset_stream(session);
 115                                                 setup_decompression(session);
 116                                                 return true;
 117                                         end;
 118                                 session.compressed = true;
 119                         elseif method then
 120                                 session.log("info", "%s compression selected, but we don't support it.", tostring(method));
 121                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 122                                 session.send(error_st);
 123                         else
 124                                 session.send(st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed"));
 125                         end
 126                 end
 127 );