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 format = string.format;
  10
  11 local hosts = _G.hosts;
  12 local s2s_make_authenticated = require "core.s2smanager".make_authenticated;
  13
  14 local log = module._log;
  15
  16 local st = require "util.stanza";
  17 local sha256_hash = require "util.hashes".sha256;
  18
  19 local xmlns_stream = "http://etherx.jabber.org/streams";
  20
  21 local dialback_requests = setmetatable({}, { __mode = 'v' });
  22
  23 function generate_dialback(id, to, from)
  24         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
  25 end
  26
  27 function initiate_dialback(session)
  28         -- generate dialback key
  29         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
  30         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
  31         session.log("info", "sent dialback key on outgoing s2s stream");
  32 end
  33
  34 function verify_dialback(id, to, from, key)
  35         return key == generate_dialback(id, to, from);
  36 end
  37
  38 module:hook("stanza/jabber:server:dialback:verify", function(event)
  39         local origin, stanza = event.origin, event.stanza;
  40
  41         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  42                 -- We are being asked to verify the key, to ensure it was generated by us
  43                 origin.log("debug", "verifying that dialback key is ours...");
  44                 local attr = stanza.attr;
  45                 -- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
  46                 --if attr.from ~= origin.to_host then error("invalid-from"); end
  47                 local type;
  48                 if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
  49                         type = "valid"
  50                 else
  51                         type = "invalid"
  52                         origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
  53                 end
  54                 origin.log("debug", "verified dialback key... it is %s", type);
  55                 origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
  56                 return true;
  57         end
  58 end);
  59
  60 module:hook("stanza/jabber:server:dialback:result", function(event)
  61         local origin, stanza = event.origin, event.stanza;
  62
  63         if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
  64                 -- he wants to be identified through dialback
  65                 -- We need to check the key with the Authoritative server
  66                 local attr = stanza.attr;
  67                 origin.hosts[attr.from] = { dialback_key = stanza[1] };
  68
  69                 if not hosts[attr.to] then
  70                         -- Not a host that we serve
  71                         origin.log("info", "%s tried to connect to %s, which we don't serve", attr.from, attr.to);
  72                         origin:close("host-unknown");
  73                         return true;
  74                 end
  75
  76                 dialback_requests[attr.from.."/"..origin.streamid] = origin;
  77
  78                 if not origin.from_host then
  79                         -- Just used for friendlier logging
  80                         origin.from_host = attr.from;
  81                 end
  82                 if not origin.to_host then
  83                         -- Just used for friendlier logging
  84                         origin.to_host = attr.to;
  85                 end
  86
  87                 origin.log("debug", "asking %s if key %s belongs to them", attr.from, stanza[1]);
  88                 origin.send(st.stanza("db:verify", { from = attr.to, to = attr.from, id = origin.streamid }):text(stanza[1]));
  89                 return true;
  90         end
  91 end);
  92
  93 module:hook("stanza/jabber:server:dialback:verify", function(event)
  94         local origin, stanza = event.origin, event.stanza;
  95
  96         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
  97                 local attr = stanza.attr;
  98                 local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
  99                 module:log("debug", tostring(dialback_verifying).." "..attr.from.." "..origin.to_host);
 100                 if dialback_verifying and attr.from == origin.to_host then
 101                         local valid;
 102                         if attr.type == "valid" then
 103                                 s2s_make_authenticated(dialback_verifying, attr.from);
 104                                 valid = "valid";
 105                         else
 106                                 -- Warn the original connection that is was not verified successfully
 107                                 log("warn", "authoritative server for "..(attr.from or "(unknown)").." denied the key");
 108                                 valid = "invalid";
 109                         end
 110                         if not dialback_verifying.sends2s then
 111                                 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+$"));
 112                         else
 113                                 dialback_verifying.sends2s(
 114                                                 st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
 115                                                                 :text(dialback_verifying.hosts[attr.from].dialback_key));
 116                         end
 117                         dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
 118                 end
 119                 return true;
 120         end
 121 end);
 122
 123 module:hook("stanza/jabber:server:dialback:result", function(event)
 124         local origin, stanza = event.origin, event.stanza;
 125
 126         if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
 127                 -- Remote server is telling us whether we passed dialback
 128
 129                 local attr = stanza.attr;
 130                 if not hosts[attr.to] then
 131                         origin:close("host-unknown");
 132                         return true;
 133                 elseif hosts[attr.to].s2sout[attr.from] ~= origin then
 134                         -- This isn't right
 135                         origin:close("invalid-id");
 136                         return true;
 137                 end
 138                 if stanza.attr.type == "valid" then
 139                         s2s_make_authenticated(origin, attr.from);
 140                 else
 141                         origin:close("not-authorized", "dialback authentication failed");
 142                 end
 143                 return true;
 144         end
 145 end);
 146
 147 module:hook_stanza("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza)
 148         if origin.external_auth == "failed" then
 149                 module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
 150                 initiate_dialback(origin);
 151                 return true;
 152         end
 153 end, 100);
 154
 155 module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
 156         if not origin.external_auth or origin.external_auth == "failed" then
 157                 module:log("debug", "Initiating dialback...");
 158                 initiate_dialback(origin);
 159                 return true;
 160         end
 161 end, 100);
 162
 163 module:hook("s2s-authenticate-legacy", function (event)
 164         module:log("debug", "Initiating dialback...");
 165         initiate_dialback(event.origin);
 166         return true;
 167 end, 100);
 168
 169 -- Offer dialback to incoming hosts
 170 module:hook("s2s-stream-features", function (data)
 171         data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
 172 end);