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 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("compression_level");
  20 -- if not defined assume admin wants best compression
  21 if compression_level == nil then compression_level = 9 end;
  22
  23
  24 compression_level = tonumber(compression_level);
  25 if not compression_level or compression_level < 1 or compression_level > 9 then
  26         module:log("warn", "Invalid compression level in config: %s", tostring(compression_level));
  27         module:log("warn", "Module loading aborted. Compression won't be available.");
  28         return;
  29 end
  30
  31 module:hook("stream-features", function(event)
  32         local origin, features = event.origin, event.features;
  33         if not origin.compressed then
  34                 -- FIXME only advertise compression support when TLS layer has no compression enabled
  35                 features:add_child(compression_stream_feature);
  36         end
  37 end);
  38
  39 module:hook("s2s-stream-features", function(event)
  40         local origin, features = event.origin, event.features;
  41         -- FIXME only advertise compression support when TLS layer has no compression enabled
  42         if not origin.compressed then
  43                 features:add_child(compression_stream_feature);
  44         end
  45 end);
  46
  47 -- Hook to activate compression if remote server supports it.
  48 module:hook_stanza(xmlns_stream, "features",
  49                 function (session, stanza)
  50                         if not session.compressed then
  51                                 -- does remote server support compression?
  52                                 local comp_st = stanza:child_with_name("compression");
  53                                 if comp_st then
  54                                         -- do we support the mechanism
  55                                         for a in comp_st:children() do
  56                                                 local algorithm = a[1]
  57                                                 if algorithm == "zlib" then
  58                                                         session.sends2s(st.stanza("compress", {xmlns=xmlns_compression_protocol}):tag("method"):text("zlib"))
  59                                                         session.log("debug", "Enabled compression using zlib.")
  60                                                         return true;
  61                                                 end
  62                                         end
  63                                         session.log("debug", "Remote server supports no compression algorithm we support.")
  64                                 end
  65                         end
  66                 end
  67 , 250);
  68
  69
  70 -- returns either nil or a fully functional ready to use inflate stream
  71 local function get_deflate_stream(session)
  72         local status, deflate_stream = pcall(zlib.deflate, compression_level);
  73         if status == false then
  74                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  75                 (session.sends2s or session.send)(error_st);
  76                 session.log("error", "Failed to create zlib.deflate filter.");
  77                 module:log("error", "%s", tostring(deflate_stream));
  78                 return
  79         end
  80         return deflate_stream
  81 end
  82
  83 -- returns either nil or a fully functional ready to use inflate stream
  84 local function get_inflate_stream(session)
  85         local status, inflate_stream = pcall(zlib.inflate);
  86         if status == false then
  87                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
  88                 (session.sends2s or session.send)(error_st);
  89                 session.log("error", "Failed to create zlib.inflate filter.");
  90                 module:log("error", "%s", tostring(inflate_stream));
  91                 return
  92         end
  93         return inflate_stream
  94 end
  95
  96 -- setup compression for a stream
  97 local function setup_compression(session, deflate_stream)
  98         add_filter(session, "bytes/out", function(t)
  99                 local status, compressed, eof = pcall(deflate_stream, tostring(t), 'sync');
 100                 if status == false then
 101                         module:log("warn", "%s", tostring(compressed));
 102                         session:close({
 103                                 condition = "undefined-condition";
 104                                 text = compressed;
 105                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 106                         });
 107                         return;
 108                 end
 109                 return compressed;
 110         end);
 111 end
 112
 113 -- setup decompression for a stream
 114 local function setup_decompression(session, inflate_stream)
 115         add_filter(session, "bytes/in", function(data)
 116                 local status, decompressed, eof = pcall(inflate_stream, data);
 117                 if status == false then
 118                         module:log("warn", "%s", tostring(decompressed));
 119                         session:close({
 120                                 condition = "undefined-condition";
 121                                 text = decompressed;
 122                                 extra = st.stanza("failure", {xmlns="http://jabber.org/protocol/compress"}):tag("processing-failed");
 123                         });
 124                         return;
 125                 end
 126                 return decompressed;
 127         end);
 128 end
 129
 130 module:add_handler({"s2sout_unauthed", "s2sout"}, "compressed", xmlns_compression_protocol,
 131                 function(session ,stanza)
 132                         session.log("debug", "Activating compression...")
 133                         -- create deflate and inflate streams
 134                         local deflate_stream = get_deflate_stream(session);
 135                         if not deflate_stream then return end
 136
 137                         local inflate_stream = get_inflate_stream(session);
 138                         if not inflate_stream then return end
 139
 140                         -- setup compression for session.w
 141                         setup_compression(session, deflate_stream);
 142
 143                         -- setup decompression for session.data
 144                         setup_decompression(session, inflate_stream);
 145                         session:reset_stream();
 146                         local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
 147                                                                                 ["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
 148                         session.sends2s("<?xml version='1.0'?>");
 149                         session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
 150                         session.compressed = true;
 151                 end
 152 );
 153
 154 module:add_handler({"c2s_unauthed", "c2s", "s2sin_unauthed", "s2sin"}, "compress", xmlns_compression_protocol,
 155                 function(session, stanza)
 156                         -- fail if we are already compressed
 157                         if session.compressed then
 158                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
 159                                 (session.sends2s or session.send)(error_st);
 160                                 session.log("debug", "Client tried to establish another compression layer.");
 161                                 return;
 162                         end
 163
 164                         -- checking if the compression method is supported
 165                         local method = stanza:child_with_name("method");
 166                         method = method and (method[1] or "");
 167                         if method == "zlib" then
 168                                 session.log("debug", "zlib compression enabled.");
 169
 170                                 -- create deflate and inflate streams
 171                                 local deflate_stream = get_deflate_stream(session);
 172                                 if not deflate_stream then return end
 173
 174                                 local inflate_stream = get_inflate_stream(session);
 175                                 if not inflate_stream then return end
 176
 177                                 (session.sends2s or session.send)(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
 178                                 session:reset_stream();
 179
 180                                 -- setup compression for session.w
 181                                 setup_compression(session, deflate_stream);
 182
 183                                 -- setup decompression for session.data
 184                                 setup_decompression(session, inflate_stream);
 185
 186                                 session.compressed = true;
 187                         elseif method then
 188                                 session.log("debug", "%s compression selected, but we don't support it.", tostring(method));
 189                                 local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 190                                 (session.sends2s or session.send)(error_st);
 191                         else
 192                                 (session.sends2s or session.send)(st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed"));
 193                         end
 194                 end
 195 );
 196