core/s2smanager.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
  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, setmetatable
  20     = tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber, setmetatable;
  21
  22 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  23 local connlisteners_get = require "net.connlisteners".get;
  24 local initialize_filters = require "util.filters".initialize;
  25 local wrapclient = require "net.server".wrapclient;
  26 local modulemanager = require "core.modulemanager";
  27 local st = require "stanza";
  28 local stanza = st.stanza;
  29 local nameprep = require "util.encodings".stringprep.nameprep;
  30
  31 local fire_event = prosody.events.fire_event;
  32 local uuid_gen = require "util.uuid".generate;
  33
  34 local logger_init = require "util.logger".init;
  35
  36 local log = logger_init("s2smanager");
  37
  38 local sha256_hash = require "util.hashes".sha256;
  39
  40 local adns, dns = require "net.adns", require "net.dns";
  41 local config = require "core.configmanager";
  42 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  43 local dns_timeout = config.get("*", "core", "dns_timeout") or 15;
  44 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  45
  46 dns.settimeout(dns_timeout);
  47
  48 local prosody = _G.prosody;
  49 incoming_s2s = {};
  50 prosody.incoming_s2s = incoming_s2s;
  51 local incoming_s2s = incoming_s2s;
  52
  53 module "s2smanager"
  54
  55 function compare_srv_priorities(a,b)
  56         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  57 end
  58
  59 local bouncy_stanzas = { message = true, presence = true, iq = true };
  60 local function bounce_sendq(session, reason)
  61         local sendq = session.sendq;
  62         if sendq then
  63                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  64                 local dummy = {
  65                         type = "s2sin";
  66                         send = function(s)
  67                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  68                         end;
  69                         dummy = true;
  70                 };
  71                 for i, data in ipairs(sendq) do
  72                         local reply = data[2];
  73                         local xmlns = reply.attr.xmlns;
  74                         if not(xmlns) and bouncy_stanzas[reply.name] then
  75                                 reply.attr.type = "error";
  76                                 reply:tag("error", {type = "cancel"})
  77                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  78                                 if reason then
  79                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  80                                 end
  81                                 core_process_stanza(dummy, reply);
  82                         end
  83                         sendq[i] = nil;
  84                 end
  85                 session.sendq = nil;
  86         end
  87 end
  88
  89 function send_to_host(from_host, to_host, data)
  90         if not hosts[from_host] then
  91                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  92                 return false;
  93         end
  94         local host = hosts[from_host].s2sout[to_host];
  95         if host then
  96                 -- We have a connection to this host already
  97                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
  98                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  99
 100                         -- Queue stanza until we are able to send it
 101                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
 102                         else host.sendq = { {tostring(data), st.reply(data)} }; end
 103                         host.log("debug", "stanza [%s] queued ", data.name);
 104                 elseif host.type == "local" or host.type == "component" then
 105                         log("error", "Trying to send a stanza to ourselves??")
 106                         log("error", "Traceback: %s", get_traceback());
 107                         log("error", "Stanza: %s", tostring(data));
 108                 else
 109                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
 110                         -- FIXME
 111                         if host.from_host ~= from_host then
 112                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 113                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 114                         end
 115                         host.sends2s(data);
 116                         host.log("debug", "stanza sent over "..host.type);
 117                 end
 118         else
 119                 log("debug", "opening a new outgoing connection for this stanza");
 120                 local host_session = new_outgoing(from_host, to_host);
 121
 122                 -- Store in buffer
 123                 host_session.sendq = { {tostring(data), st.reply(data)} };
 124                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 125                 if (not host_session.connecting) and (not host_session.conn) then
 126                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 127                         destroy_session(host_session);
 128                 end
 129         end
 130 end
 131
 132 local open_sessions = 0;
 133
 134 function new_incoming(conn)
 135         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 136         if true then
 137                 session.trace = newproxy(true);
 138                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 139         end
 140         open_sessions = open_sessions + 1;
 141         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 142         session.log = log;
 143         local filter = initialize_filters(session);
 144         session.sends2s = function (t)
 145                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 146                 if t.name then
 147                         t = filter("stanzas/out", t);
 148                 end
 149                 if t then
 150                         t = filter("bytes/out", tostring(t));
 151                         if t then
 152                                 return w(conn, t);
 153                         end
 154                 end
 155         end
 156         incoming_s2s[session] = true;
 157         add_task(connect_timeout, function ()
 158                 if session.conn ~= conn or
 159                    session.type == "s2sin" then
 160                         return; -- Ok, we're connect[ed|ing]
 161                 end
 162                 -- Not connected, need to close session and clean up
 163                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 164                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 165                 session:close("connection-timeout");
 166         end);
 167         return session;
 168 end
 169
 170 function new_outgoing(from_host, to_host, connect)
 171                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 172                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 173                                        open_stream = session_open_stream };
 174
 175                 hosts[from_host].s2sout[to_host] = host_session;
 176
 177                 local log;
 178                 do
 179                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 180                         log = logger_init(conn_name);
 181                         host_session.log = log;
 182                 end
 183
 184                 initialize_filters(host_session);
 185
 186                 if connect ~= false then
 187                         -- Kick the connection attempting machine into life
 188                         attempt_connection(host_session);
 189                 end
 190
 191                 if not host_session.sends2s then
 192                         -- A sends2s which buffers data (until the stream is opened)
 193                         -- note that data in this buffer will be sent before the stream is authed
 194                         -- and will not be ack'd in any way, successful or otherwise
 195                         local buffer;
 196                         function host_session.sends2s(data)
 197                                 if not buffer then
 198                                         buffer = {};
 199                                         host_session.send_buffer = buffer;
 200                                 end
 201                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 202                                 buffer[#buffer+1] = data;
 203                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 204                         end
 205                 end
 206
 207                 return host_session;
 208 end
 209
 210
 211 function attempt_connection(host_session, err)
 212         local from_host, to_host = host_session.from_host, host_session.to_host;
 213         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
 214
 215         if not connect_host then
 216                 return false;
 217         end
 218
 219         if not err then -- This is our first attempt
 220                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 221                 host_session.connecting = true;
 222                 local handle;
 223                 handle = adns.lookup(function (answer)
 224                         handle = nil;
 225                         host_session.connecting = nil;
 226                         if answer then
 227                                 log("debug", to_host.." has SRV records, handling...");
 228                                 local srv_hosts = {};
 229                                 host_session.srv_hosts = srv_hosts;
 230                                 for _, record in ipairs(answer) do
 231                                         t_insert(srv_hosts, record.srv);
 232                                 end
 233                                 t_sort(srv_hosts, compare_srv_priorities);
 234
 235                                 local srv_choice = srv_hosts[1];
 236                                 host_session.srv_choice = 1;
 237                                 if srv_choice then
 238                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 239                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 240                                 end
 241                         else
 242                                 log("debug", to_host.." has no SRV records, falling back to A");
 243                         end
 244                         -- Try with SRV, or just the plain hostname if no SRV
 245                         local ok, err = try_connect(host_session, connect_host, connect_port);
 246                         if not ok then
 247                                 if not attempt_connection(host_session, err) then
 248                                         -- No more attempts will be made
 249                                         destroy_session(host_session, err);
 250                                 end
 251                         end
 252                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 253
 254                 return true; -- Attempt in progress
 255         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 256                 host_session.srv_choice = host_session.srv_choice + 1;
 257                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 258                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 259                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 260         else
 261                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 262                 -- We're out of options
 263                 return false;
 264         end
 265
 266         if not (connect_host and connect_port) then
 267                 -- Likely we couldn't resolve DNS
 268                 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));
 269                 return false;
 270         end
 271
 272         return try_connect(host_session, connect_host, connect_port);
 273 end
 274
 275 function try_connect(host_session, connect_host, connect_port)
 276         host_session.connecting = true;
 277         local handle;
 278         handle = adns.lookup(function (reply)
 279                 handle = nil;
 280                 host_session.connecting = nil;
 281
 282                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 283                 if not (reply and reply[#reply] and reply[#reply].a) then
 284                         local count = max_dns_depth;
 285                         reply = dns.peek(connect_host, "CNAME", "IN");
 286                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 287                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 288                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 289                                 count = count - 1;
 290                         end
 291                 end
 292                 -- end of CNAME resolving
 293
 294                 if reply and reply[#reply] and reply[#reply].a then
 295                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 296                         return make_connect(host_session, reply[#reply].a, connect_port);
 297                 else
 298                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 299                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 300                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 301                                 destroy_session(host_session, "DNS resolution failed"); -- End of the line, we can't
 302                         end
 303                 end
 304         end, connect_host, "A", "IN");
 305
 306         return true;
 307 end
 308
 309 function make_connect(host_session, connect_host, connect_port)
 310         (host_session.log or log)("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 311         -- Ok, we're going to try to connect
 312
 313         local from_host, to_host = host_session.from_host, host_session.to_host;
 314
 315         local conn, handler = socket.tcp()
 316
 317         if not conn then
 318                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 319                 return false, handler;
 320         end
 321
 322         conn:settimeout(0);
 323         local success, err = conn:connect(connect_host, connect_port);
 324         if not success and err ~= "timeout" then
 325                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 326                 return false, err;
 327         end
 328
 329         local cl = connlisteners_get("xmppserver");
 330         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 331         host_session.conn = conn;
 332
 333         local filter = initialize_filters(host_session);
 334         local w, log = conn.write, host_session.log;
 335         host_session.sends2s = function (t)
 336                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 337                 if t.name then
 338                         t = filter("stanzas/out", t);
 339                 end
 340                 if t then
 341                         t = filter("bytes/out", tostring(t));
 342                         if t then
 343                                 return w(conn, tostring(t));
 344                         end
 345                 end
 346         end
 347
 348         -- Register this outgoing connection so that xmppserver_listener knows about it
 349         -- otherwise it will assume it is a new incoming connection
 350         cl.register_outgoing(conn, host_session);
 351
 352         host_session:open_stream(from_host, to_host);
 353
 354         log("debug", "Connection attempt in progress...");
 355         add_task(connect_timeout, function ()
 356                 if host_session.conn ~= conn or
 357                    host_session.type == "s2sout" or
 358                    host_session.connecting then
 359                         return; -- Ok, we're connect[ed|ing]
 360                 end
 361                 -- Not connected, need to close session and clean up
 362                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 363                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 364                 host_session:close("connection-timeout");
 365         end);
 366         return true;
 367 end
 368
 369 function session_open_stream(session, from, to)
 370         session.sends2s(st.stanza("stream:stream", {
 371                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 372                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 373                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 374 end
 375
 376 function streamopened(session, attr)
 377         local send = session.sends2s;
 378
 379         -- TODO: #29: SASL/TLS on s2s streams
 380         session.version = tonumber(attr.version) or 0;
 381
 382         if session.secure == false then
 383                 session.secure = true;
 384         end
 385
 386         if session.direction == "incoming" then
 387                 -- Send a reply stream header
 388                 session.to_host = attr.to and nameprep(attr.to);
 389                 session.from_host = attr.from and nameprep(attr.from);
 390
 391                 session.streamid = uuid_gen();
 392                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 393                 if session.to_host then
 394                         if not hosts[session.to_host] then
 395                                 -- Attempting to connect to a host we don't serve
 396                                 session:close({
 397                                         condition = "host-unknown";
 398                                         text = "This host does not serve "..session.to_host
 399                                 });
 400                                 return;
 401                         elseif hosts[session.to_host].disallow_s2s then
 402                                 -- Attempting to connect to a host that disallows s2s
 403                                 session:close({
 404                                         condition = "policy-violation";
 405                                         text = "Server-to-server communication is not allowed to this host";
 406                                 });
 407                                 return;
 408                         end
 409                 end
 410                 send("<?xml version='1.0'?>");
 411                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 412                                 ["xmlns:stream"]='http://etherx.jabber.org/streams', id=session.streamid, from=session.to_host, to=session.from_host, version=(session.version > 0 and "1.0" or nil) }):top_tag());
 413                 if session.version >= 1.0 then
 414                         local features = st.stanza("stream:features");
 415
 416                         if session.to_host then
 417                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { origin = session, features = features });
 418                         else
 419                                 (session.log or log)("warn", "No 'to' on stream header from %s means we can't offer any features", session.from_host or "unknown host");
 420                         end
 421
 422                         log("debug", "Sending stream features: %s", tostring(features));
 423                         send(features);
 424                 end
 425         elseif session.direction == "outgoing" then
 426                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 427                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 428                 session.streamid = attr.id;
 429
 430                 -- Send unauthed buffer
 431                 -- (stanzas which are fine to send before dialback)
 432                 -- Note that this is *not* the stanza queue (which
 433                 -- we can only send if auth succeeds) :)
 434                 local send_buffer = session.send_buffer;
 435                 if send_buffer and #send_buffer > 0 then
 436                         log("debug", "Sending s2s send_buffer now...");
 437                         for i, data in ipairs(send_buffer) do
 438                                 session.sends2s(tostring(data));
 439                                 send_buffer[i] = nil;
 440                         end
 441                 end
 442                 session.send_buffer = nil;
 443
 444                 -- If server is pre-1.0, don't wait for features, just do dialback
 445                 if session.version < 1.0 then
 446                         if not session.dialback_verifying then
 447                                 log("debug", "Initiating dialback...");
 448                                 initiate_dialback(session);
 449                         else
 450                                 mark_connected(session);
 451                         end
 452                 end
 453         end
 454         session.notopen = nil;
 455 end
 456
 457 function streamclosed(session)
 458         (session.log or log)("debug", "Received </stream:stream>");
 459         session:close();
 460 end
 461
 462 function initiate_dialback(session)
 463         -- generate dialback key
 464         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 465         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 466         session.log("info", "sent dialback key on outgoing s2s stream");
 467 end
 468
 469 function generate_dialback(id, to, from)
 470         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 471 end
 472
 473 function verify_dialback(id, to, from, key)
 474         return key == generate_dialback(id, to, from);
 475 end
 476
 477 function make_authenticated(session, host)
 478         if not session.secure then
 479                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 480                 if config.get(local_host, "core", "s2s_require_encryption") then
 481                         session:close({
 482                                 condition = "policy-violation",
 483                                 text = "Encrypted server-to-server communication is required but was not "
 484                                        ..((session.direction == "outgoing" and "offered") or "used")
 485                         });
 486                 end
 487         end
 488         if session.type == "s2sout_unauthed" then
 489                 session.type = "s2sout";
 490         elseif session.type == "s2sin_unauthed" then
 491                 session.type = "s2sin";
 492                 if host then
 493                         session.hosts[host].authed = true;
 494                 end
 495         elseif session.type == "s2sin" and host then
 496                 session.hosts[host].authed = true;
 497         else
 498                 return false;
 499         end
 500         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 501
 502         mark_connected(session);
 503
 504         return true;
 505 end
 506
 507 -- Stream is authorised, and ready for normal stanzas
 508 function mark_connected(session)
 509         local sendq, send = session.sendq, session.sends2s;
 510
 511         local from, to = session.from_host, session.to_host;
 512
 513         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 514
 515         local send_to_host = send_to_host;
 516         function session.send(data) send_to_host(to, from, data); end
 517
 518         local event_data = { session = session };
 519         if session.type == "s2sout" then
 520                 prosody.events.fire_event("s2sout-established", event_data);
 521                 hosts[session.from_host].events.fire_event("s2sout-established", event_data);
 522         else
 523                 prosody.events.fire_event("s2sin-established", event_data);
 524                 hosts[session.to_host].events.fire_event("s2sin-established", event_data);
 525         end
 526
 527         if session.direction == "outgoing" then
 528                 if sendq then
 529                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 530                         for i, data in ipairs(sendq) do
 531                                 send(data[1]);
 532                                 sendq[i] = nil;
 533                         end
 534                         session.sendq = nil;
 535                 end
 536
 537                 session.srv_hosts = nil;
 538         end
 539 end
 540
 541 local resting_session = { -- Resting, not dead
 542                 destroyed = true;
 543                 type = "s2s_destroyed";
 544                 open_stream = function (session)
 545                         session.log("debug", "Attempt to open stream on resting session");
 546                 end;
 547                 close = function (session)
 548                         session.log("debug", "Attempt to close already-closed session");
 549                 end;
 550                 filter = function (type, data) return data; end;
 551         }; resting_session.__index = resting_session;
 552
 553 function retire_session(session)
 554         local log = session.log or log;
 555         for k in pairs(session) do
 556                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 557                         session[k] = nil;
 558                 end
 559         end
 560
 561         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 562         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 563         return setmetatable(session, resting_session);
 564 end
 565
 566 function destroy_session(session, reason)
 567         if session.destroyed then return; end
 568         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 569
 570         if session.direction == "outgoing" then
 571                 hosts[session.from_host].s2sout[session.to_host] = nil;
 572                 bounce_sendq(session, reason);
 573         elseif session.direction == "incoming" then
 574                 incoming_s2s[session] = nil;
 575         end
 576
 577         local event_data = { session = session, reason = reason };
 578         if session.type == "s2sout" then
 579                 prosody.events.fire_event("s2sout-destroyed", event_data);
 580                 if hosts[session.from_host] then
 581                         hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
 582                 end
 583         elseif session.type == "s2sin" then
 584                 prosody.events.fire_event("s2sin-destroyed", event_data);
 585                 if hosts[session.to_host] then
 586                         hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
 587                 end
 588         end
 589
 590         retire_session(session); -- Clean session until it is GC'd
 591 end
 592
 593 return _M;