plugins/mod_compression.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2009-2012 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 xmlns_stream = "http://etherx.jabber.org/streams";
  16 local compression_stream_feature = st.stanza("compression", {xmlns=xmlns_compression_feature}):tag("method"):text("zlib"):up();
  17 local add_filter = require "util.filters".add_filter;
  18
  19 local compression_level = module:get_option_number("compression_level", 7);
  20
  21 if not compression_level or compression_level < 1 or compression_level > 9 then
  22         module:log("warn", "Invalid compression level in config: %s", tostring(compression_level));
  23         module:log("warn", "Module loading aborted. Compression won't be available.");
  24         return;
  25 end
  26
  27 module:hook("stream-features", function(event)
  28         local origin, features = event.origin, event.features;
  29         if not origin.compressed and origin.type == "c2s" then
  30                 features:add_child(compression_stream_feature);
  31         end
  32 end);
  33
  34 module:hook("s2s-stream-features", function(event)
  35         local origin, features = event.origin, event.features;
  36         if not origin.compressed and origin.type == "s2sin" then
  37                 features:add_child(compression_stream_feature);
  38         end
  39 end);
  40
  41 -- Hook to activate compression if remote server supports it.
  42 module:hook_stanza(xmlns_stream, "features",
  43                 function (session, stanza)
  44                         if not session.compressed and session.type == "s2sout" then
  45                                 -- does remote server support compression?
  46                                 local comp_st = stanza:get_child("compression", xmlns_compression_feature);
  47                                 if comp_st then
  48                                         -- do we support the mechanism
  49                                         for a in comp_st:childtags("method") do
  50                                                 local algorithm = a:get_text();
  51                                                 if algorithm == "zlib" then
  52                                                         session.sends2s(st.stanza("compress", {xmlns=xmlns_compression_protocol}):tag("method"):text("zlib"))
  53                                                         session.log("debug", "Enabled compression using zlib.")
  54                                                         return true;
  55                                                 end
  56                                         end
  57                                         session.log("debug", "Remote server supports no compression algorithm we support.")
  58                                 end
  59                         end
  60                 end
  61 , 250);
  62
  63
  64 -- returns either nil or a fully functional ready to use inflate stream
  65 local function get_deflate_stream(session)
  66         local status, deflate_stream = pcall(zlib.deflate, compression_level);
  67         if status == false then
  68                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  69                 (session.sends2s or session.send)(error_st);
  70                 session.log("error", "Failed to create zlib.deflate filter.");
  71                 module:log("error", "%s", tostring(deflate_stream));
  72                 return
  73         end
  74         return deflate_stream
  75 end
  76
  77 -- returns either nil or a fully functional ready to use inflate stream
  78 local function get_inflate_stream(session)
  79         local status, inflate_stream = pcall(zlib.inflate);
  80         if status == false then
  81                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  82                 (session.sends2s or session.send)(error_st);
  83                 session.log("error", "Failed to create zlib.inflate filter.");
  84                 module:log("error", "%s", tostring(inflate_stream));
  85                 return
  86         end
  87         return inflate_stream
  88 end
  89
  90 -- setup compression for a stream
  91 local function setup_compression(session, deflate_stream)
  92         add_filter(session, "bytes/out", function(t)
  93                 local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
  94                 if status == false then
  95                         module:log("warn", "%s", tostring(compressed));
  96                         session:close({
  97                                 condition = "undefined-condition";
  98                                 text = compressed;
  99                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 100                         });
 101                         return;
 102                 end
 103                 return compressed;
 104         end);
 105 end
 106
 107 -- setup decompression for a stream
 108 local function setup_decompression(session, inflate_stream)
 109         add_filter(session, "bytes/in", function(data)
 110                 local status, decompressed, eof = pcall(inflate_stream, data);
 111                 if status == false then
 112                         module:log("warn", "%s", tostring(decompressed));
 113                         session:close({
 114                                 condition = "undefined-condition";
 115                                 text = decompressed;
 116                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 117                         });
 118                         return;
 119                 end
 120                 return decompressed;
 121         end);
 122 end
 123
 124 module:hook("stanza/http://jabber.org/protocol/compress:compressed", function(event)
 125         local session = event.origin;
 126
 127         if session.type == "s2sout" then
 128                 session.log("debug", "Activating compression...")
 129                 -- create deflate and inflate streams
 130                 local deflate_stream = get_deflate_stream(session);
 131                 if not deflate_stream then return true; end
 132
 133                 local inflate_stream = get_inflate_stream(session);
 134                 if not inflate_stream then return true; end
 135
 136                 -- setup compression for session.w
 137                 setup_compression(session, deflate_stream);
 138
 139                 -- setup decompression for session.data
 140                 setup_decompression(session, inflate_stream);
 141                 session:reset_stream();
 142                 session:open_stream(session.from_host, session.to_host);
 143                 session.compressed = true;
 144                 return true;
 145         end
 146 end);
 147
 148 module:hook("stanza/http://jabber.org/protocol/compress:failure", function(event)
 149         local err = event.stanza:get_child();
 150         (event.origin.log or module._log)("warn", "Compression setup failed (%s)", err and err.name or "unknown reason");
 151         return true;
 152 end);
 153
 154 module:hook("stanza/http://jabber.org/protocol/compress:compress", function(event)
 155         local session, stanza = event.origin, event.stanza;
 156
 157         if session.type == "c2s" or session.type == "s2sin" then
 158                 -- fail if we are already compressed
 159                 if session.compressed then
 160                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
 161                         (session.sends2s or session.send)(error_st);
 162                         session.log("debug", "Client tried to establish another compression layer.");
 163                         return true;
 164                 end
 165
 166                 -- checking if the compression method is supported
 167                 local method = stanza:get_child_text("method");
 168                 if method == "zlib" then
 169                         session.log("debug", "zlib compression enabled.");
 170
 171                         -- create deflate and inflate streams
 172                         local deflate_stream = get_deflate_stream(session);
 173                         if not deflate_stream then return true; end
 174
 175                         local inflate_stream = get_inflate_stream(session);
 176                         if not inflate_stream then return true; end
 177
 178                         (session.sends2s or session.send)(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
 179                         session:reset_stream();
 180
 181                         -- setup compression for session.w
 182                         setup_compression(session, deflate_stream);
 183
 184                         -- setup decompression for session.data
 185                         setup_decompression(session, inflate_stream);
 186
 187                         session.compressed = true;
 188                 elseif method then
 189                         session.log("debug", "%s compression selected, but we don't support it.", tostring(method));
 190                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 191                         (session.sends2s or session.send)(error_st);
 192                 else
 193                         (session.sends2s or session.send)(st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed"));
 194                 end
 195                 return true;
 196         end
 197 end);
 198