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:hook("stanza/http://jabber.org/protocol/compress:compressed", function(event)
 131         local session = event.origin;
 132
 133         if session.type == "s2sout_unauthed" or session.type == "s2sout" then
 134                 session.log("debug", "Activating compression...")
 135                 -- create deflate and inflate streams
 136                 local deflate_stream = get_deflate_stream(session);
 137                 if not deflate_stream then return true; end
 138
 139                 local inflate_stream = get_inflate_stream(session);
 140                 if not inflate_stream then return true; end
 141
 142                 -- setup compression for session.w
 143                 setup_compression(session, deflate_stream);
 144
 145                 -- setup decompression for session.data
 146                 setup_decompression(session, inflate_stream);
 147                 session:reset_stream();
 148                 local default_stream_attr = {xmlns = "jabber:server", ["xmlns:stream"] = "http://etherx.jabber.org/streams",
 149                                                                         ["xmlns:db"] = 'jabber:server:dialback', version = "1.0", to = session.to_host, from = session.from_host};
 150                 session.sends2s("<?xml version='1.0'?>");
 151                 session.sends2s(st.stanza("stream:stream", default_stream_attr):top_tag());
 152                 session.compressed = true;
 153                 return true;
 154         end
 155 end);
 156
 157 module:hook("stanza/http://jabber.org/protocol/compress:compress", function(event)
 158         local session, stanza = event.origin, event.stanza;
 159
 160         if session.type == "c2s" or session.type == "s2sin" or session.type == "c2s_unauthed" or session.type == "s2sin_unauthed" then
 161                 -- fail if we are already compressed
 162                 if session.compressed then
 163                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed");
 164                         (session.sends2s or session.send)(error_st);
 165                         session.log("debug", "Client tried to establish another compression layer.");
 166                         return true;
 167                 end
 168
 169                 -- checking if the compression method is supported
 170                 local method = stanza:child_with_name("method");
 171                 method = method and (method[1] or "");
 172                 if method == "zlib" then
 173                         session.log("debug", "zlib compression enabled.");
 174
 175                         -- create deflate and inflate streams
 176                         local deflate_stream = get_deflate_stream(session);
 177                         if not deflate_stream then return true; end
 178
 179                         local inflate_stream = get_inflate_stream(session);
 180                         if not inflate_stream then return true; end
 181
 182                         (session.sends2s or session.send)(st.stanza("compressed", {xmlns=xmlns_compression_protocol}));
 183                         session:reset_stream();
 184
 185                         -- setup compression for session.w
 186                         setup_compression(session, deflate_stream);
 187
 188                         -- setup decompression for session.data
 189                         setup_decompression(session, inflate_stream);
 190
 191                         session.compressed = true;
 192                 elseif method then
 193                         session.log("debug", "%s compression selected, but we don't support it.", tostring(method));
 194                         local error_st = st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("unsupported-method");
 195                         (session.sends2s or session.send)(error_st);
 196                 else
 197                         (session.sends2s or session.send)(st.stanza("failure", {xmlns=xmlns_compression_protocol}):tag("setup-failed"));
 198                 end
 199                 return true;
 200         end
 201 end);
 202