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