core/s2smanager.lua

   1 -- Prosody IM
   2 -- Copyright (C) 2008-2009 Matthew Wild
   3 -- Copyright (C) 2008-2009 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 local hosts = hosts;
  12 local sessions = sessions;
  13 local core_process_stanza = function(a, b) core_process_stanza(a, b); end
  14 local add_task = require "util.timer".add_task;
  15 local socket = require "socket";
  16 local format = string.format;
  17 local t_insert, t_sort = table.insert, table.sort;
  18 local get_traceback = debug.traceback;
  19 local tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber
  20     = tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber;
  21
  22 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  23 local connlisteners_get = require "net.connlisteners".get;
  24 local wrapclient = require "net.server".wrapclient;
  25 local modulemanager = require "core.modulemanager";
  26 local st = require "stanza";
  27 local stanza = st.stanza;
  28 local nameprep = require "util.encodings".stringprep.nameprep;
  29
  30 local uuid_gen = require "util.uuid".generate;
  31
  32 local logger_init = require "util.logger".init;
  33
  34 local log = logger_init("s2smanager");
  35
  36 local sha256_hash = require "util.hashes".sha256;
  37
  38 local dialback_secret = uuid_gen();
  39
  40 local adns = require "net.adns";
  41
  42 local dns_timeout = config.get("*", "core", "dns_timeout") or 60;
  43
  44 incoming_s2s = {};
  45 local incoming_s2s = incoming_s2s;
  46
  47 module "s2smanager"
  48
  49 local function compare_srv_priorities(a,b) return a.priority < b.priority or a.weight < b.weight; end
  50
  51 local function bounce_sendq(session)
  52         local sendq = session.sendq;
  53         if sendq then
  54                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  55                 local dummy = {
  56                         type = "s2sin";
  57                         send = function(s)
  58                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  59                         end;
  60                         dummy = true;
  61                 };
  62                 for i, data in ipairs(sendq) do
  63                         local reply = data[2];
  64                         local xmlns = reply.attr.xmlns;
  65                         if not xmlns or xmlns == "jabber:client" or xmlns == "jabber:server" then
  66                                 reply.attr.type = "error";
  67                                 reply:tag("error", {type = "cancel"})
  68                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  69                                 core_process_stanza(dummy, reply);
  70                         end
  71                         sendq[i] = nil;
  72                 end
  73                 session.sendq = nil;
  74         end
  75 end
  76
  77 function send_to_host(from_host, to_host, data)
  78         local host = hosts[from_host].s2sout[to_host];
  79         if host then
  80                 -- We have a connection to this host already
  81                 if host.type == "s2sout_unauthed" and data.name ~= "db:verify" and ((not data.xmlns) or data.xmlns == "jabber:client" or data.xmlns == "jabber:server") then
  82                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  83                         if not host.notopen and not host.dialback_key and host.sends2s then
  84                                 host.log("debug", "dialback had not been initiated");
  85                                 initiate_dialback(host);
  86                         end
  87
  88                         -- Queue stanza until we are able to send it
  89                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
  90                         else host.sendq = { {tostring(data), st.reply(data)} }; end
  91                         host.log("debug", "stanza [%s] queued ", data.name);
  92                 elseif host.type == "local" or host.type == "component" then
  93                         log("error", "Trying to send a stanza to ourselves??")
  94                         log("error", "Traceback: %s", get_traceback());
  95                         log("error", "Stanza: %s", tostring(data));
  96                 else
  97                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
  98                         -- FIXME
  99                         if host.from_host ~= from_host then
 100                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 101                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 102                         end
 103                         host.sends2s(data);
 104                         host.log("debug", "stanza sent over "..host.type);
 105                 end
 106         else
 107                 log("debug", "opening a new outgoing connection for this stanza");
 108                 local host_session = new_outgoing(from_host, to_host);
 109                 -- Store in buffer
 110                 host_session.sendq = { {tostring(data), st.reply(data)} };
 111                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 112                 if (not host_session.connecting) and (not host_session.conn) then
 113                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 114                         destroy_session(host_session);
 115                 end
 116         end
 117 end
 118
 119 local open_sessions = 0;
 120
 121 function new_incoming(conn)
 122         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 123         if true then
 124                 session.trace = newproxy(true);
 125                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 126         end
 127         open_sessions = open_sessions + 1;
 128         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 129         session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
 130         incoming_s2s[session] = true;
 131         return session;
 132 end
 133
 134 function new_outgoing(from_host, to_host)
 135                 local host_session = { to_host = to_host, from_host = from_host, notopen = true, type = "s2sout_unauthed", direction = "outgoing" };
 136                 hosts[from_host].s2sout[to_host] = host_session;
 137
 138                 local log;
 139                 do
 140                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 141                         log = logger_init(conn_name);
 142                         host_session.log = log;
 143                 end
 144
 145                 -- This is the first call, can't fail (the first step is DNS lookup)
 146                 attempt_connection(host_session);
 147
 148                 if not host_session.sends2s then
 149                         -- A sends2s which buffers data (until the stream is opened)
 150                         -- note that data in this buffer will be sent before the stream is authed
 151                         -- and will not be ack'd in any way, successful or otherwise
 152                         local buffer;
 153                         function host_session.sends2s(data)
 154                                 if not buffer then
 155                                         buffer = {};
 156                                         host_session.send_buffer = buffer;
 157                                 end
 158                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 159                                 buffer[#buffer+1] = data;
 160                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 161                         end
 162
 163                 end
 164
 165                 return host_session;
 166 end
 167
 168
 169 function attempt_connection(host_session, err)
 170         local from_host, to_host = host_session.from_host, host_session.to_host;
 171         local connect_host, connect_port = idna_to_ascii(to_host), 5269;
 172
 173         if not err then -- This is our first attempt
 174                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 175                 host_session.connecting = true;
 176                 local answer, handle;
 177                 handle = adns.lookup(function (answer)
 178                         handle = nil;
 179                         host_session.connecting = nil;
 180                         if answer then
 181                                 log("debug", to_host.." has SRV records, handling...");
 182                                 local srv_hosts = {};
 183                                 host_session.srv_hosts = srv_hosts;
 184                                 for _, record in ipairs(answer) do
 185                                         t_insert(srv_hosts, record.srv);
 186                                 end
 187                                 t_sort(srv_hosts, compare_srv_priorities);
 188
 189                                 local srv_choice = srv_hosts[1];
 190                                 host_session.srv_choice = 1;
 191                                 if srv_choice then
 192                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 193                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 194                                 end
 195                         else
 196                                 log("debug", to_host.." has no SRV records, falling back to A");
 197                         end
 198                         -- Try with SRV, or just the plain hostname if no SRV
 199                         local ok, err = try_connect(host_session, connect_host, connect_port);
 200                         if not ok then
 201                                 if not attempt_connection(host_session, err) then
 202                                         -- No more attempts will be made
 203                                         destroy_session(host_session);
 204                                 end
 205                         end
 206                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 207
 208                 -- Set handler for DNS timeout
 209                 add_task(dns_timeout, function ()
 210                         if handle then
 211                                 adns.cancel(handle, true);
 212                         end
 213                 end);
 214
 215                 log("debug", "DNS lookup for %s sent, waiting for response before we can connect", to_host);
 216                 return true; -- Attempt in progress
 217         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 218                 host_session.srv_choice = host_session.srv_choice + 1;
 219                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 220                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 221                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 222         else
 223                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 224                 -- We're out of options
 225                 return false;
 226         end
 227
 228         if not (connect_host and connect_port) then
 229                 -- Likely we couldn't resolve DNS
 230                 log("warn", "Hmm, we're without a host (%s) and port (%s) to connect to for %s, giving up :(", tostring(connect_host), tostring(connect_port), tostring(to_host));
 231                 return false;
 232         end
 233
 234         return try_connect(host_session, connect_host, connect_port);
 235 end
 236
 237 function try_connect(host_session, connect_host, connect_port)
 238         host_session.log("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 239         -- Ok, we're going to try to connect
 240
 241         local from_host, to_host = host_session.from_host, host_session.to_host;
 242
 243         local conn, handler = socket.tcp()
 244
 245         conn:settimeout(0);
 246         local success, err = conn:connect(connect_host, connect_port);
 247         if not success and err ~= "timeout" then
 248                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 249                 return false, err;
 250         end
 251
 252         local cl = connlisteners_get("xmppserver");
 253         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1, hosts[from_host].ssl_ctx, false );
 254         host_session.conn = conn;
 255
 256         -- Register this outgoing connection so that xmppserver_listener knows about it
 257         -- otherwise it will assume it is a new incoming connection
 258         cl.register_outgoing(conn, host_session);
 259
 260         local w = conn.write;
 261         host_session.sends2s = function (t) log("debug", "sending: %s", tostring(t)); w(tostring(t)); end
 262
 263         conn.write(format([[<stream:stream xmlns='jabber:server' xmlns:db='jabber:server:dialback' xmlns:stream='http://etherx.jabber.org/streams' from='%s' to='%s' version='1.0' xml:lang='en'>]], from_host, to_host));
 264         log("debug", "Connection attempt in progress...");
 265         return true;
 266 end
 267
 268 function streamopened(session, attr)
 269         local send = session.sends2s;
 270
 271         -- TODO: #29: SASL/TLS on s2s streams
 272         session.version = 0; --tonumber(attr.version) or 0;
 273
 274         if session.version >= 1.0 and not (attr.to and attr.from) then
 275                 log("warn", (session.to_host or "(unknown)").." failed to specify 'to' or 'from' hostname as per RFC");
 276         end
 277
 278         if session.direction == "incoming" then
 279                 -- Send a reply stream header
 280                 session.to_host = attr.to and nameprep(attr.to);
 281                 session.from_host = attr.from and nameprep(attr.from);
 282
 283                 session.streamid = uuid_gen();
 284                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 285                 send("<?xml version='1.0'?>");
 286                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 287                                 ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host }):top_tag());
 288                 if session.to_host and not hosts[session.to_host] then
 289                         -- Attempting to connect to a host we don't serve
 290                         session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
 291                         return;
 292                 end
 293                 if session.version >= 1.0 then
 294                         send(st.stanza("stream:features")
 295                                         :tag("dialback", { xmlns='urn:xmpp:features:dialback' }):tag("optional"):up():up());
 296                 end
 297         elseif session.direction == "outgoing" then
 298                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 299                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 300                 session.streamid = attr.id;
 301
 302                 -- Send unauthed buffer
 303                 -- (stanzas which are fine to send before dialback)
 304                 -- Note that this is *not* the stanza queue (which
 305                 -- we can only send if auth succeeds) :)
 306                 local send_buffer = session.send_buffer;
 307                 if send_buffer and #send_buffer > 0 then
 308                         log("debug", "Sending s2s send_buffer now...");
 309                         for i, data in ipairs(send_buffer) do
 310                                 session.sends2s(tostring(data));
 311                                 send_buffer[i] = nil;
 312                         end
 313                 end
 314                 session.send_buffer = nil;
 315
 316                 if not session.dialback_verifying then
 317                         initiate_dialback(session);
 318                 else
 319                         mark_connected(session);
 320                 end
 321         end
 322
 323         session.notopen = nil;
 324 end
 325
 326 function streamclosed(session)
 327         (session.log or log)("debug", "</stream:stream>");
 328         if session.sends2s then
 329                 session.sends2s("</stream:stream>");
 330         end
 331         session.notopen = true;
 332 end
 333
 334 function initiate_dialback(session)
 335         -- generate dialback key
 336         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 337         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 338         session.log("info", "sent dialback key on outgoing s2s stream");
 339 end
 340
 341 function generate_dialback(id, to, from)
 342         return sha256_hash(id..to..from..dialback_secret, true);
 343 end
 344
 345 function verify_dialback(id, to, from, key)
 346         return key == generate_dialback(id, to, from);
 347 end
 348
 349 function make_authenticated(session, host)
 350         if session.type == "s2sout_unauthed" then
 351                 session.type = "s2sout";
 352         elseif session.type == "s2sin_unauthed" then
 353                 session.type = "s2sin";
 354                 if host then
 355                         session.hosts[host].authed = true;
 356                 end
 357         elseif session.type == "s2sin" and host then
 358                 session.hosts[host].authed = true;
 359         else
 360                 return false;
 361         end
 362         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 363
 364         mark_connected(session);
 365
 366         return true;
 367 end
 368
 369 function mark_connected(session)
 370         local sendq, send = session.sendq, session.sends2s;
 371
 372         local from, to = session.from_host, session.to_host;
 373
 374         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 375
 376         local send_to_host = send_to_host;
 377         function session.send(data) send_to_host(to, from, data); end
 378
 379
 380         if session.direction == "outgoing" then
 381                 if sendq then
 382                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 383                         for i, data in ipairs(sendq) do
 384                                 send(data[1]);
 385                                 sendq[i] = nil;
 386                         end
 387                         session.sendq = nil;
 388                 end
 389
 390                 session.srv_hosts = nil;
 391         end
 392 end
 393
 394 function destroy_session(session)
 395         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 396
 397         if session.direction == "outgoing" then
 398                 hosts[session.from_host].s2sout[session.to_host] = nil;
 399                 bounce_sendq(session);
 400         elseif session.direction == "incoming" then
 401                 incoming_s2s[session] = nil;
 402         end
 403
 404         for k in pairs(session) do
 405                 if k ~= "trace" then
 406                         session[k] = nil;
 407                 end
 408         end
 409 end
 410
 411 return _M;