core/xmlhandlers.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2010 Matthew Wild
   3 -- Copyright (C) 2008-2010 Waqas Hussain
   4 --
   5 -- This project is MIT/X11 licensed. Please see the
   6 -- COPYING file in the source package for more information.
   7 --
   8
   9
  10
  11 require "util.stanza"
  12
  13 local st = stanza;
  14 local tostring = tostring;
  15 local t_insert = table.insert;
  16 local t_concat = table.concat;
  17
  18 local default_log = require "util.logger".init("xmlhandlers");
  19
  20 -- COMPAT: w/LuaExpat 1.1.0
  21 local lxp_supports_doctype = pcall(lxp.new, { StartDoctypeDecl = false });
  22
  23 if not lxp_supports_doctype then
  24         default_log("warn", "The version of LuaExpat on your system leaves Prosody "
  25                 .."vulnerable to denial-of-service attacks. You should upgrade to "
  26                 .."LuaExpat 1.1.1 or higher as soon as possible. See "
  27                 .."http://prosody.im/doc/depends#luaexpat for more information.");
  28 end
  29
  30 local error = error;
  31
  32 module "xmlhandlers"
  33
  34 local ns_prefixes = {
  35         ["http://www.w3.org/XML/1998/namespace"] = "xml";
  36 };
  37
  38 local xmlns_streams = "http://etherx.jabber.org/streams";
  39
  40 local ns_separator = "\1";
  41 local ns_pattern = "^([^"..ns_separator.."]*)"..ns_separator.."?(.*)$";
  42
  43 function init_xmlhandlers(session, stream_callbacks)
  44         local chardata = {};
  45         local xml_handlers = {};
  46         local log = session.log or default_log;
  47
  48         local cb_streamopened = stream_callbacks.streamopened;
  49         local cb_streamclosed = stream_callbacks.streamclosed;
  50         local cb_error = stream_callbacks.error or function(session, e) error("XML stream error: "..tostring(e)); end;
  51         local cb_handlestanza = stream_callbacks.handlestanza;
  52
  53         local stream_ns = stream_callbacks.stream_ns or xmlns_streams;
  54         local stream_tag = stream_ns..ns_separator..(stream_callbacks.stream_tag or "stream");
  55         local stream_error_tag = stream_ns..ns_separator..(stream_callbacks.error_tag or "error");
  56
  57         local stream_default_ns = stream_callbacks.default_ns;
  58
  59         local stanza;
  60         function xml_handlers:StartElement(tagname, attr)
  61                 if stanza and #chardata > 0 then
  62                         -- We have some character data in the buffer
  63                         stanza:text(t_concat(chardata));
  64                         chardata = {};
  65                 end
  66                 local curr_ns,name = tagname:match(ns_pattern);
  67                 if name == "" then
  68                         curr_ns, name = "", curr_ns;
  69                 end
  70
  71                 if curr_ns ~= stream_default_ns then
  72                         attr.xmlns = curr_ns;
  73                 end
  74
  75                 -- FIXME !!!!!
  76                 for i=1,#attr do
  77                         local k = attr[i];
  78                         attr[i] = nil;
  79                         local ns, nm = k:match(ns_pattern);
  80                         if nm ~= "" then
  81                                 ns = ns_prefixes[ns];
  82                                 if ns then
  83                                         attr[ns..":"..nm] = attr[k];
  84                                         attr[k] = nil;
  85                                 end
  86                         end
  87                 end
  88
  89                 if not stanza then --if we are not currently inside a stanza
  90                         if session.notopen then
  91                                 if tagname == stream_tag then
  92                                         if cb_streamopened then
  93                                                 cb_streamopened(session, attr);
  94                                         end
  95                                 else
  96                                         -- Garbage before stream?
  97                                         cb_error(session, "no-stream");
  98                                 end
  99                                 return;
 100                         end
 101                         if curr_ns == "jabber:client" and name ~= "iq" and name ~= "presence" and name ~= "message" then
 102                                 cb_error(session, "invalid-top-level-element");
 103                         end
 104
 105                         stanza = st.stanza(name, attr);
 106                 else -- we are inside a stanza, so add a tag
 107                         attr.xmlns = nil;
 108                         if curr_ns ~= stream_default_ns then
 109                                 attr.xmlns = curr_ns;
 110                         end
 111                         stanza:tag(name, attr);
 112                 end
 113         end
 114         function xml_handlers:CharacterData(data)
 115                 if stanza then
 116                         t_insert(chardata, data);
 117                 end
 118         end
 119         function xml_handlers:EndElement(tagname)
 120                 if stanza then
 121                         if #chardata > 0 then
 122                                 -- We have some character data in the buffer
 123                                 stanza:text(t_concat(chardata));
 124                                 chardata = {};
 125                         end
 126                         -- Complete stanza
 127                         if #stanza.last_add == 0 then
 128                                 if tagname ~= stream_error_tag then
 129                                         cb_handlestanza(session, stanza);
 130                                 else
 131                                         cb_error(session, "stream-error", stanza);
 132                                 end
 133                                 stanza = nil;
 134                         else
 135                                 stanza:up();
 136                         end
 137                 else
 138                         if tagname == stream_tag then
 139                                 if cb_streamclosed then
 140                                         cb_streamclosed(session);
 141                                 end
 142                         else
 143                                 local curr_ns,name = tagname:match(ns_pattern);
 144                                 if name == "" then
 145                                         curr_ns, name = "", curr_ns;
 146                                 end
 147                                 cb_error(session, "parse-error", "unexpected-element-close", name);
 148                         end
 149                         stanza, chardata = nil, {};
 150                 end
 151         end
 152
 153         local function restricted_handler()
 154                 cb_error(session, "parse-error", "restricted-xml", "Restricted XML, see RFC 6120 section 11.1.");
 155         end
 156
 157         if lxp_supports_doctype then
 158                 xml_handlers.StartDoctypeDecl = restricted_handler;
 159         end
 160         xml_handlers.Comment = restricted_handler;
 161         xml_handlers.ProcessingInstruction = restricted_handler;
 162
 163         return xml_handlers;
 164 end
 165
 166 return init_xmlhandlers;