plugins/mod_dialback.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 local hosts = _G.hosts;
  10
  11 local log = module._log;
  12
  13 local st = require "util.stanza";
  14 local sha256_hash = require "util.hashes".sha256;
  15 local nameprep = require "util.encodings".stringprep.nameprep;
  16 local uuid_gen = require"util.uuid".generate;
  17
  18 local xmlns_stream = "http://etherx.jabber.org/streams";
  19
  20 local dialback_requests = setmetatable({}, { __mode = 'v' });
  21
  22 local dialback_secret = module.host .. module:get_option_string("dialback_secret", uuid_gen());
  23
  24 function module.save()
  25         return { dialback_secret = dialback_secret };
  26 end
  27
  28 function module.restore(state)
  29         dialback_secret = state.dialback_secret;
  30 end
  31
  32 function generate_dialback(id, to, from)
  33         return sha256_hash(id..to..dialback_secret, true);
  34 end
  35
  36 function initiate_dialback(session)
  37         -- generate dialback key
  38         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  39         session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
  40         session.log("debug", "sent dialback key on outgoing s2s stream");
  41 end
  42
  43 function verify_dialback(id, to, from, key)
  44         return key == generate_dialback(id, to, from);
  45 end
  46
  47 module:hook("stanza/jabber:server:dialback:verify", function(event)
  48         local origin, stanza = event.origin, event.stanza;
  49
  50         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  51                 -- We are being asked to verify the key, to ensure it was generated by us
  52                 origin.log("debug", "verifying that dialback key is ours...");
  53                 local attr = stanza.attr;
  54                 if attr.type then
  55                         module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
  56                                 origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
  57                         return true;
  58                 end
  59                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  60                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  61                 local type;
  62                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  63                         type = "valid"
  64                 else
  65                         type = "invalid"
  66                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  67                 end
  68                 origin.log("debug", "verified dialback key... it is %s", type);
  69                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  70                 return true;
  71         end
  72 end);
  73
  74 module:hook("stanza/jabber:server:dialback:result", function(event)
  75         local origin, stanza = event.origin, event.stanza;
  76
  77         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  78                 -- he wants to be identified through dialback
  79                 -- We need to check the key with the Authoritative server
  80                 local attr = stanza.attr;
  81                 local to, from = nameprep(attr.to), nameprep(attr.from);
  82
  83                 if not hosts[to] then
  84                         -- Not a host that we serve
  85                         origin.log("warn", "%s tried to connect to %s, which we don't serve", from, to);
  86                         origin:close("host-unknown");
  87                         return true;
  88                 elseif not from then
  89                         origin:close("improper-addressing");
  90                 end
  91
  92                 origin.hosts[from] = { dialback_key = stanza[1] };
  93
  94                 dialback_requests[from.."/"..origin.streamid] = origin;
  95
  96                 -- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
  97                 -- on streams. We fill in the session's to/from here instead.
  98                 if not origin.from_host then
  99                         origin.from_host = from;
 100                 end
 101                 if not origin.to_host then
 102                         origin.to_host = to;
 103                 end
 104
 105                 origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
 106                 module:fire_event("route/remote", {
 107                         from_host = to, to_host = from;
 108                         stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
 109                 });
 110                 return true;
 111         end
 112 end);
 113
 114 module:hook("stanza/jabber:server:dialback:verify", function(event)
 115         local origin, stanza = event.origin, event.stanza;
 116
 117         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 118                 local attr = stanza.attr;
 119                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
 120                 if dialback_verifying and attr.from == origin.to_host then
 121                         local valid;
 122                         if attr.type == "valid" then
 123                                 module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from });
 124                                 valid = "valid";
 125                         else
 126                                 -- Warn the original connection that is was not verified successfully
 127                                 log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
 128                                 valid = "invalid";
 129                         end
 130                         if dialback_verifying.destroyed then
 131                                 log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the db result", tostring(dialback_verifying):match("%w+$"));
 132                         else
 133                                 dialback_verifying.sends2s(
 134                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 135                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 136                         end
 137                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 138                 end
 139                 return true;
 140         end
 141 end);
 142
 143 module:hook("stanza/jabber:server:dialback:result", function(event)
 144         local origin, stanza = event.origin, event.stanza;
 145
 146         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 147                 -- Remote server is telling us whether we passed dialback
 148
 149                 local attr = stanza.attr;
 150                 if not hosts[attr.to] then
 151                         origin:close("host-unknown");
 152                         return true;
 153                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 154                         -- This isn't right
 155                         origin:close("invalid-id");
 156                         return true;
 157                 end
 158                 if stanza.attr.type == "valid" then
 159                         module:fire_event("s2s-authenticated", { session = origin, host = attr.from });
 160                 else
 161                         origin:close("not-authorized", "dialback authentication failed");
 162                 end
 163                 return true;
 164         end
 165 end);
 166
 167 module:hook_stanza("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza)
 168         if origin.external_auth == "failed" then
 169                 module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
 170                 initiate_dialback(origin);
 171                 return true;
 172         end
 173 end, 100);
 174
 175 module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
 176         if not origin.external_auth or origin.external_auth == "failed" then
 177                 module:log("debug", "Initiating dialback...");
 178                 initiate_dialback(origin);
 179                 return true;
 180         end
 181 end, 100);
 182
 183 module:hook("s2sout-authenticate-legacy", function (event)
 184         module:log("debug", "Initiating dialback...");
 185         initiate_dialback(event.origin);
 186         return true;
 187 end, 100);
 188
 189 -- Offer dialback to incoming hosts
 190 module:hook("s2s-stream-features", function (data)
 191         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 192 end);