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