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,
  20       setmetatable
  21     = tostring, pairs, ipairs, getmetatable, newproxy, error, tonumber,
  22       setmetatable;
  23
  24 local idna_to_ascii = require "util.encodings".idna.to_ascii;
  25 local connlisteners_get = require "net.connlisteners".get;
  26 local initialize_filters = require "util.filters".initialize;
  27 local wrapclient = require "net.server".wrapclient;
  28 local modulemanager = require "core.modulemanager";
  29 local st = require "stanza";
  30 local stanza = st.stanza;
  31 local nameprep = require "util.encodings".stringprep.nameprep;
  32
  33 local fire_event = prosody.events.fire_event;
  34 local uuid_gen = require "util.uuid".generate;
  35
  36 local logger_init = require "util.logger".init;
  37
  38 local log = logger_init("s2smanager");
  39
  40 local sha256_hash = require "util.hashes".sha256;
  41
  42 local adns, dns = require "net.adns", require "net.dns";
  43 local config = require "core.configmanager";
  44 local connect_timeout = config.get("*", "core", "s2s_timeout") or 60;
  45 local dns_timeout = config.get("*", "core", "dns_timeout") or 15;
  46 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  47
  48 dns.settimeout(dns_timeout);
  49
  50 local prosody = _G.prosody;
  51 incoming_s2s = {};
  52 prosody.incoming_s2s = incoming_s2s;
  53 local incoming_s2s = incoming_s2s;
  54
  55 module "s2smanager"
  56
  57 function compare_srv_priorities(a,b)
  58         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  59 end
  60
  61 local bouncy_stanzas = { message = true, presence = true, iq = true };
  62 local function bounce_sendq(session, reason)
  63         local sendq = session.sendq;
  64         if sendq then
  65                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  66                 local dummy = {
  67                         type = "s2sin";
  68                         send = function(s)
  69                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  70                         end;
  71                         dummy = true;
  72                 };
  73                 for i, data in ipairs(sendq) do
  74                         local reply = data[2];
  75                         local xmlns = reply.attr.xmlns;
  76                         if not(xmlns) and bouncy_stanzas[reply.name] then
  77                                 reply.attr.type = "error";
  78                                 reply:tag("error", {type = "cancel"})
  79                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  80                                 if reason then
  81                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  82                                 end
  83                                 core_process_stanza(dummy, reply);
  84                         end
  85                         sendq[i] = nil;
  86                 end
  87                 session.sendq = nil;
  88         end
  89 end
  90
  91 function send_to_host(from_host, to_host, data)
  92         if not hosts[from_host] then
  93                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  94                 return false;
  95         end
  96         local host = hosts[from_host].s2sout[to_host];
  97         if host then
  98                 -- We have a connection to this host already
  99                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
 100                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
 101
 102                         -- Queue stanza until we are able to send it
 103                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
 104                         else host.sendq = { {tostring(data), st.reply(data)} }; end
 105                         host.log("debug", "stanza [%s] queued ", data.name);
 106                 elseif host.type == "local" or host.type == "component" then
 107                         log("error", "Trying to send a stanza to ourselves??")
 108                         log("error", "Traceback: %s", get_traceback());
 109                         log("error", "Stanza: %s", tostring(data));
 110                 else
 111                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
 112                         -- FIXME
 113                         if host.from_host ~= from_host then
 114                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 115                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 116                         end
 117                         host.sends2s(data);
 118                         host.log("debug", "stanza sent over "..host.type);
 119                 end
 120         else
 121                 log("debug", "opening a new outgoing connection for this stanza");
 122                 local host_session = new_outgoing(from_host, to_host);
 123
 124                 -- Store in buffer
 125                 host_session.sendq = { {tostring(data), st.reply(data)} };
 126                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 127                 if (not host_session.connecting) and (not host_session.conn) then
 128                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 129                         destroy_session(host_session);
 130                 end
 131         end
 132 end
 133
 134 local open_sessions = 0;
 135
 136 function new_incoming(conn)
 137         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 138         if true then
 139                 session.trace = newproxy(true);
 140                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 141         end
 142         open_sessions = open_sessions + 1;
 143         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 144         session.log = log;
 145         local filter = initialize_filters(session);
 146         session.sends2s = function (t)
 147                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 148                 if t.name then
 149                         t = filter("stanzas/out", t);
 150                 end
 151                 if t then
 152                         t = filter("bytes/out", tostring(t));
 153                         if t then
 154                                 return w(conn, t);
 155                         end
 156                 end
 157         end
 158         incoming_s2s[session] = true;
 159         add_task(connect_timeout, function ()
 160                 if session.conn ~= conn or
 161                    session.type == "s2sin" then
 162                         return; -- Ok, we're connect[ed|ing]
 163                 end
 164                 -- Not connected, need to close session and clean up
 165                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 166                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 167                 session:close("connection-timeout");
 168         end);
 169         return session;
 170 end
 171
 172 function new_outgoing(from_host, to_host, connect)
 173                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 174                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 175                                        open_stream = session_open_stream };
 176
 177                 hosts[from_host].s2sout[to_host] = host_session;
 178
 179                 local log;
 180                 do
 181                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 182                         log = logger_init(conn_name);
 183                         host_session.log = log;
 184                 end
 185
 186                 initialize_filters(host_session);
 187
 188                 if connect ~= false then
 189                         -- Kick the connection attempting machine into life
 190                         attempt_connection(host_session);
 191                 end
 192
 193                 if not host_session.sends2s then
 194                         -- A sends2s which buffers data (until the stream is opened)
 195                         -- note that data in this buffer will be sent before the stream is authed
 196                         -- and will not be ack'd in any way, successful or otherwise
 197                         local buffer;
 198                         function host_session.sends2s(data)
 199                                 if not buffer then
 200                                         buffer = {};
 201                                         host_session.send_buffer = buffer;
 202                                 end
 203                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 204                                 buffer[#buffer+1] = data;
 205                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 206                         end
 207                 end
 208
 209                 return host_session;
 210 end
 211
 212
 213 function attempt_connection(host_session, err)
 214         local from_host, to_host = host_session.from_host, host_session.to_host;
 215         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
 216
 217         if not connect_host then
 218                 return false;
 219         end
 220
 221         if not err then -- This is our first attempt
 222                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 223                 host_session.connecting = true;
 224                 local handle;
 225                 handle = adns.lookup(function (answer)
 226                         handle = nil;
 227                         host_session.connecting = nil;
 228                         if answer then
 229                                 log("debug", to_host.." has SRV records, handling...");
 230                                 local srv_hosts = {};
 231                                 host_session.srv_hosts = srv_hosts;
 232                                 for _, record in ipairs(answer) do
 233                                         t_insert(srv_hosts, record.srv);
 234                                 end
 235                                 t_sort(srv_hosts, compare_srv_priorities);
 236
 237                                 local srv_choice = srv_hosts[1];
 238                                 host_session.srv_choice = 1;
 239                                 if srv_choice then
 240                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 241                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 242                                 end
 243                         else
 244                                 log("debug", to_host.." has no SRV records, falling back to A");
 245                         end
 246                         -- Try with SRV, or just the plain hostname if no SRV
 247                         local ok, err = try_connect(host_session, connect_host, connect_port);
 248                         if not ok then
 249                                 if not attempt_connection(host_session, err) then
 250                                         -- No more attempts will be made
 251                                         destroy_session(host_session, err);
 252                                 end
 253                         end
 254                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 255
 256                 return true; -- Attempt in progress
 257         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 258                 host_session.srv_choice = host_session.srv_choice + 1;
 259                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 260                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 261                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 262         else
 263                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 264                 -- We're out of options
 265                 return false;
 266         end
 267
 268         if not (connect_host and connect_port) then
 269                 -- Likely we couldn't resolve DNS
 270                 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));
 271                 return false;
 272         end
 273
 274         return try_connect(host_session, connect_host, connect_port);
 275 end
 276
 277 function try_connect(host_session, connect_host, connect_port)
 278         host_session.connecting = true;
 279         local handle;
 280         handle = adns.lookup(function (reply)
 281                 handle = nil;
 282                 host_session.connecting = nil;
 283
 284                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 285                 if not (reply and reply[#reply] and reply[#reply].a) then
 286                         local count = max_dns_depth;
 287                         reply = dns.peek(connect_host, "CNAME", "IN");
 288                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 289                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 290                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 291                                 count = count - 1;
 292                         end
 293                 end
 294                 -- end of CNAME resolving
 295
 296                 if reply and reply[#reply] and reply[#reply].a then
 297                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 298                         return make_connect(host_session, reply[#reply].a, connect_port);
 299                 else
 300                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 301                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 302                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 303                                 destroy_session(host_session, "DNS resolution failed"); -- End of the line, we can't
 304                         end
 305                 end
 306         end, connect_host, "A", "IN");
 307
 308         return true;
 309 end
 310
 311 function make_connect(host_session, connect_host, connect_port)
 312         (host_session.log or log)("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 313         -- Ok, we're going to try to connect
 314
 315         local from_host, to_host = host_session.from_host, host_session.to_host;
 316
 317         local conn, handler = socket.tcp()
 318
 319         if not conn then
 320                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 321                 return false, handler;
 322         end
 323
 324         conn:settimeout(0);
 325         local success, err = conn:connect(connect_host, connect_port);
 326         if not success and err ~= "timeout" then
 327                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 328                 return false, err;
 329         end
 330
 331         local cl = connlisteners_get("xmppserver");
 332         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 333         host_session.conn = conn;
 334
 335         local filter = initialize_filters(host_session);
 336         local w, log = conn.write, host_session.log;
 337         host_session.sends2s = function (t)
 338                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 339                 if t.name then
 340                         t = filter("stanzas/out", t);
 341                 end
 342                 if t then
 343                         t = filter("bytes/out", tostring(t));
 344                         if t then
 345                                 return w(conn, tostring(t));
 346                         end
 347                 end
 348         end
 349
 350         -- Register this outgoing connection so that xmppserver_listener knows about it
 351         -- otherwise it will assume it is a new incoming connection
 352         cl.register_outgoing(conn, host_session);
 353
 354         host_session:open_stream(from_host, to_host);
 355
 356         log("debug", "Connection attempt in progress...");
 357         add_task(connect_timeout, function ()
 358                 if host_session.conn ~= conn or
 359                    host_session.type == "s2sout" or
 360                    host_session.connecting then
 361                         return; -- Ok, we're connect[ed|ing]
 362                 end
 363                 -- Not connected, need to close session and clean up
 364                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 365                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 366                 host_session:close("connection-timeout");
 367         end);
 368         return true;
 369 end
 370
 371 function session_open_stream(session, from, to)
 372         session.sends2s(st.stanza("stream:stream", {
 373                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 374                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 375                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 376 end
 377
 378 function streamopened(session, attr)
 379         local send = session.sends2s;
 380
 381         -- TODO: #29: SASL/TLS on s2s streams
 382         session.version = tonumber(attr.version) or 0;
 383
 384         if session.secure == false then
 385                 session.secure = true;
 386         end
 387
 388         if session.direction == "incoming" then
 389                 -- Send a reply stream header
 390                 session.to_host = attr.to and nameprep(attr.to);
 391                 session.from_host = attr.from and nameprep(attr.from);
 392
 393                 session.streamid = uuid_gen();
 394                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 395                 if session.to_host then
 396                         if not hosts[session.to_host] then
 397                                 -- Attempting to connect to a host we don't serve
 398                                 session:close({
 399                                         condition = "host-unknown";
 400                                         text = "This host does not serve "..session.to_host
 401                                 });
 402                                 return;
 403                         elseif hosts[session.to_host].disallow_s2s then
 404                                 -- Attempting to connect to a host that disallows s2s
 405                                 session:close({
 406                                         condition = "policy-violation";
 407                                         text = "Server-to-server communication is not allowed to this host";
 408                                 });
 409                                 return;
 410                         end
 411                 end
 412                 send("<?xml version='1.0'?>");
 413                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 414                                 ["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());
 415                 if session.version >= 1.0 then
 416                         local features = st.stanza("stream:features");
 417
 418                         if session.to_host then
 419                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { origin = session, features = features });
 420                         else
 421                                 (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");
 422                         end
 423
 424                         log("debug", "Sending stream features: %s", tostring(features));
 425                         send(features);
 426                 end
 427         elseif session.direction == "outgoing" then
 428                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 429                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 430                 session.streamid = attr.id;
 431
 432                 -- Send unauthed buffer
 433                 -- (stanzas which are fine to send before dialback)
 434                 -- Note that this is *not* the stanza queue (which
 435                 -- we can only send if auth succeeds) :)
 436                 local send_buffer = session.send_buffer;
 437                 if send_buffer and #send_buffer > 0 then
 438                         log("debug", "Sending s2s send_buffer now...");
 439                         for i, data in ipairs(send_buffer) do
 440                                 session.sends2s(tostring(data));
 441                                 send_buffer[i] = nil;
 442                         end
 443                 end
 444                 session.send_buffer = nil;
 445
 446                 -- If server is pre-1.0, don't wait for features, just do dialback
 447                 if session.version < 1.0 then
 448                         if not session.dialback_verifying then
 449                                 log("debug", "Initiating dialback...");
 450                                 initiate_dialback(session);
 451                         else
 452                                 mark_connected(session);
 453                         end
 454                 end
 455         end
 456         session.notopen = nil;
 457 end
 458
 459 function streamclosed(session)
 460         (session.log or log)("debug", "Received </stream:stream>");
 461         session:close();
 462 end
 463
 464 function initiate_dialback(session)
 465         -- generate dialback key
 466         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 467         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 468         session.log("info", "sent dialback key on outgoing s2s stream");
 469 end
 470
 471 function generate_dialback(id, to, from)
 472         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 473 end
 474
 475 function verify_dialback(id, to, from, key)
 476         return key == generate_dialback(id, to, from);
 477 end
 478
 479 function make_authenticated(session, host)
 480         if not session.secure then
 481                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 482                 if config.get(local_host, "core", "s2s_require_encryption") then
 483                         session:close({
 484                                 condition = "policy-violation",
 485                                 text = "Encrypted server-to-server communication is required but was not "
 486                                        ..((session.direction == "outgoing" and "offered") or "used")
 487                         });
 488                 end
 489         end
 490         if session.type == "s2sout_unauthed" then
 491                 session.type = "s2sout";
 492         elseif session.type == "s2sin_unauthed" then
 493                 session.type = "s2sin";
 494                 if host then
 495                         session.hosts[host].authed = true;
 496                 end
 497         elseif session.type == "s2sin" and host then
 498                 session.hosts[host].authed = true;
 499         else
 500                 return false;
 501         end
 502         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 503
 504         mark_connected(session);
 505
 506         return true;
 507 end
 508
 509 -- Stream is authorised, and ready for normal stanzas
 510 function mark_connected(session)
 511         local sendq, send = session.sendq, session.sends2s;
 512
 513         local from, to = session.from_host, session.to_host;
 514
 515         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 516
 517         local send_to_host = send_to_host;
 518         function session.send(data) send_to_host(to, from, data); end
 519
 520         local event_data = { session = session };
 521         if session.type == "s2sout" then
 522                 prosody.events.fire_event("s2sout-established", event_data);
 523                 hosts[session.from_host].events.fire_event("s2sout-established", event_data);
 524         else
 525                 prosody.events.fire_event("s2sin-established", event_data);
 526                 hosts[session.to_host].events.fire_event("s2sin-established", event_data);
 527         end
 528
 529         if session.direction == "outgoing" then
 530                 if sendq then
 531                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 532                         for i, data in ipairs(sendq) do
 533                                 send(data[1]);
 534                                 sendq[i] = nil;
 535                         end
 536                         session.sendq = nil;
 537                 end
 538
 539                 session.srv_hosts = nil;
 540         end
 541 end
 542
 543 local resting_session = { -- Resting, not dead
 544                 destroyed = true;
 545                 type = "s2s_destroyed";
 546                 open_stream = function (session)
 547                         session.log("debug", "Attempt to open stream on resting session");
 548                 end;
 549                 close = function (session)
 550                         session.log("debug", "Attempt to close already-closed session");
 551                 end;
 552                 filter = function (type, data) return data; end;
 553         }; resting_session.__index = resting_session;
 554
 555 function retire_session(session)
 556         local log = session.log or log;
 557         for k in pairs(session) do
 558                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 559                         session[k] = nil;
 560                 end
 561         end
 562
 563         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 564         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 565         return setmetatable(session, resting_session);
 566 end
 567
 568 function destroy_session(session, reason)
 569         if session.destroyed then return; end
 570         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 571
 572         if session.direction == "outgoing" then
 573                 hosts[session.from_host].s2sout[session.to_host] = nil;
 574                 bounce_sendq(session, reason);
 575         elseif session.direction == "incoming" then
 576                 incoming_s2s[session] = nil;
 577         end
 578
 579         local event_data = { session = session, reason = reason };
 580         if session.type == "s2sout" then
 581                 prosody.events.fire_event("s2sout-destroyed", event_data);
 582                 if hosts[session.from_host] then
 583                         hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
 584                 end
 585         elseif session.type == "s2sin" then
 586                 prosody.events.fire_event("s2sin-destroyed", event_data);
 587                 if hosts[session.to_host] then
 588                         hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
 589                 end
 590         end
 591
 592         retire_session(session); -- Clean session until it is GC'd
 593 end
 594
 595 return _M;