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 sha256_hmac = require "util.hashes".hmac_sha256;
  16 local nameprep = require "util.encodings".stringprep.nameprep;
  17
  18 local xmlns_stream = "http://etherx.jabber.org/streams";
  19
  20 local dialback_requests = setmetatable({}, { __mode = 'v' });
  21
  22 function generate_dialback(id, to, from)
  23         return sha256_hmac(sha256_hash(hosts[from].dialback_secret), to .. ' ' .. from .. ' ' .. id, true);
  24 end
  25
  26 function initiate_dialback(session)
  27         -- generate dialback key
  28         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  29         session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
  30         session.log("info", "sent dialback key on outgoing s2s stream");
  31 end
  32
  33 function verify_dialback(id, to, from, key)
  34         return key == generate_dialback(id, to, from);
  35 end
  36
  37 module:hook("stanza/jabber:server:dialback:verify", function(event)
  38         local origin, stanza = event.origin, event.stanza;
  39
  40         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  41                 -- We are being asked to verify the key, to ensure it was generated by us
  42                 origin.log("debug", "verifying that dialback key is ours...");
  43                 local attr = stanza.attr;
  44                 if attr.type then
  45                         module:log("warn", "Ignoring incoming session from %s claiming a dialback key for %s is %s",
  46                                 origin.from_host or "(unknown)", attr.from or "(unknown)", attr.type);
  47                         return true;
  48                 end
  49                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  50                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  51                 local type;
  52                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  53                         type = "valid"
  54                 else
  55                         type = "invalid"
  56                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  57                 end
  58                 origin.log("debug", "verified dialback key... it is %s", type);
  59                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  60                 return true;
  61         end
  62 end);
  63
  64 module:hook("stanza/jabber:server:dialback:result", function(event)
  65         local origin, stanza = event.origin, event.stanza;
  66
  67         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  68                 -- he wants to be identified through dialback
  69                 -- We need to check the key with the Authoritative server
  70                 local attr = stanza.attr;
  71                 local to, from = nameprep(attr.to), nameprep(attr.from);
  72
  73                 if not hosts[to] then
  74                         -- Not a host that we serve
  75                         origin.log("info", "%s tried to connect to %s, which we don't serve", from, to);
  76                         origin:close("host-unknown");
  77                         return true;
  78                 elseif not from then
  79                         origin:close("improper-addressing");
  80                 end
  81
  82                 origin.hosts[from] = { dialback_key = stanza[1] };
  83
  84                 dialback_requests[from.."/"..origin.streamid] = origin;
  85
  86                 -- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
  87                 -- on streams. We fill in the session's to/from here instead.
  88                 if not origin.from_host then
  89                         origin.from_host = from;
  90                 end
  91                 if not origin.to_host then
  92                         origin.to_host = to;
  93                 end
  94
  95                 origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
  96                 module:fire_event("route/remote", {
  97                         from_host = to, to_host = from;
  98                         stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
  99                 });
 100                 return true;
 101         end
 102 end);
 103
 104 module:hook("stanza/jabber:server:dialback:verify", function(event)
 105         local origin, stanza = event.origin, event.stanza;
 106
 107         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 108                 local attr = stanza.attr;
 109                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
 110                 if dialback_verifying and attr.from == origin.to_host then
 111                         local valid;
 112                         if attr.type == "valid" then
 113                                 module:fire_event("s2s-authenticated", { session = dialback_verifying, host = attr.from });
 114                                 valid = "valid";
 115                         else
 116                                 -- Warn the original connection that is was not verified successfully
 117                                 log("warn", "authoritative server for %s denied the key", attr.from or "(unknown)");
 118                                 valid = "invalid";
 119                         end
 120                         if dialback_verifying.destroyed then
 121                                 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+$"));
 122                         else
 123                                 dialback_verifying.sends2s(
 124                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 125                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 126                         end
 127                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 128                 end
 129                 return true;
 130         end
 131 end);
 132
 133 module:hook("stanza/jabber:server:dialback:result", function(event)
 134         local origin, stanza = event.origin, event.stanza;
 135
 136         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 137                 -- Remote server is telling us whether we passed dialback
 138
 139                 local attr = stanza.attr;
 140                 if not hosts[attr.to] then
 141                         origin:close("host-unknown");
 142                         return true;
 143                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 144                         -- This isn't right
 145                         origin:close("invalid-id");
 146                         return true;
 147                 end
 148                 if stanza.attr.type == "valid" then
 149                         module:fire_event("s2s-authenticated", { session = origin, host = attr.from });
 150                 else
 151                         origin:close("not-authorized", "dialback authentication failed");
 152                 end
 153                 return true;
 154         end
 155 end);
 156
 157 module:hook_stanza("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza)
 158         if origin.external_auth == "failed" then
 159                 module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
 160                 initiate_dialback(origin);
 161                 return true;
 162         end
 163 end, 100);
 164
 165 module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
 166         if not origin.external_auth or origin.external_auth == "failed" then
 167                 module:log("debug", "Initiating dialback...");
 168                 initiate_dialback(origin);
 169                 return true;
 170         end
 171 end, 100);
 172
 173 module:hook("s2sout-authenticate-legacy", function (event)
 174         module:log("debug", "Initiating dialback...");
 175         initiate_dialback(event.origin);
 176         return true;
 177 end, 100);
 178
 179 -- Offer dialback to incoming hosts
 180 module:hook("s2s-stream-features", function (data)
 181         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 182 end);