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 = require "core.eventmanager".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 60;
  46 local max_dns_depth = config.get("*", "core", "dns_max_depth") or 3;
  47
  48 incoming_s2s = {};
  49 _G.prosody.incoming_s2s = incoming_s2s;
  50 local incoming_s2s = incoming_s2s;
  51
  52 module "s2smanager"
  53
  54 function compare_srv_priorities(a,b)
  55         return a.priority < b.priority or (a.priority == b.priority and a.weight > b.weight);
  56 end
  57
  58 local function bounce_sendq(session, reason)
  59         local sendq = session.sendq;
  60         if sendq then
  61                 session.log("info", "sending error replies for "..#sendq.." queued stanzas because of failed outgoing connection to "..tostring(session.to_host));
  62                 local dummy = {
  63                         type = "s2sin";
  64                         send = function(s)
  65                                 (session.log or log)("error", "Replying to to an s2s error reply, please report this! Traceback: %s", get_traceback());
  66                         end;
  67                         dummy = true;
  68                 };
  69                 for i, data in ipairs(sendq) do
  70                         local reply = data[2];
  71                         local xmlns = reply.attr.xmlns;
  72                         if not xmlns then
  73                                 reply.attr.type = "error";
  74                                 reply:tag("error", {type = "cancel"})
  75                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  76                                 if reason then
  77                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  78                                 end
  79                                 core_process_stanza(dummy, reply);
  80                         end
  81                         sendq[i] = nil;
  82                 end
  83                 session.sendq = nil;
  84         end
  85 end
  86
  87 function send_to_host(from_host, to_host, data)
  88         if not hosts[from_host] then
  89                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  90                 return false;
  91         end
  92         local host = hosts[from_host].s2sout[to_host];
  93         if host then
  94                 -- We have a connection to this host already
  95                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
  96                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  97
  98                         -- Queue stanza until we are able to send it
  99                         if host.sendq then t_insert(host.sendq, {tostring(data), st.reply(data)});
 100                         else host.sendq = { {tostring(data), st.reply(data)} }; end
 101                         host.log("debug", "stanza [%s] queued ", data.name);
 102                 elseif host.type == "local" or host.type == "component" then
 103                         log("error", "Trying to send a stanza to ourselves??")
 104                         log("error", "Traceback: %s", get_traceback());
 105                         log("error", "Stanza: %s", tostring(data));
 106                 else
 107                         (host.log or log)("debug", "going to send stanza to "..to_host.." from "..from_host);
 108                         -- FIXME
 109                         if host.from_host ~= from_host then
 110                                 log("error", "WARNING! This might, possibly, be a bug, but it might not...");
 111                                 log("error", "We are going to send from %s instead of %s", tostring(host.from_host), tostring(from_host));
 112                         end
 113                         host.sends2s(data);
 114                         host.log("debug", "stanza sent over "..host.type);
 115                 end
 116         else
 117                 log("debug", "opening a new outgoing connection for this stanza");
 118                 local host_session = new_outgoing(from_host, to_host);
 119
 120                 -- Store in buffer
 121                 host_session.sendq = { {tostring(data), st.reply(data)} };
 122                 log("debug", "stanza [%s] queued until connection complete", tostring(data.name));
 123                 if (not host_session.connecting) and (not host_session.conn) then
 124                         log("warn", "Connection to %s failed already, destroying session...", to_host);
 125                         destroy_session(host_session);
 126                 end
 127         end
 128 end
 129
 130 local open_sessions = 0;
 131
 132 function new_incoming(conn)
 133         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 134         if true then
 135                 session.trace = newproxy(true);
 136                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 137         end
 138         open_sessions = open_sessions + 1;
 139         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 140         session.log = log;
 141         local filter = initialize_filters(session);
 142         session.sends2s = function (t)
 143                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 144                 if t.name then
 145                         t = filter("stanzas/out", t);
 146                 end
 147                 if t then
 148                         t = filter("bytes/out", tostring(t));
 149                         if t then
 150                                 return w(conn, t);
 151                         end
 152                 end
 153         end
 154         incoming_s2s[session] = true;
 155         add_task(connect_timeout, function ()
 156                 if session.conn ~= conn or
 157                    session.type == "s2sin" then
 158                         return; -- Ok, we're connect[ed|ing]
 159                 end
 160                 -- Not connected, need to close session and clean up
 161                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 162                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 163                 session:close("connection-timeout");
 164         end);
 165         return session;
 166 end
 167
 168 function new_outgoing(from_host, to_host, connect)
 169                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 170                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 171                                        open_stream = session_open_stream };
 172
 173                 hosts[from_host].s2sout[to_host] = host_session;
 174
 175                 local log;
 176                 do
 177                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 178                         log = logger_init(conn_name);
 179                         host_session.log = log;
 180                 end
 181
 182                 initialize_filters(host_session);
 183
 184                 if connect ~= false then
 185                         -- Kick the connection attempting machine into life
 186                         attempt_connection(host_session);
 187                 end
 188
 189                 if not host_session.sends2s then
 190                         -- A sends2s which buffers data (until the stream is opened)
 191                         -- note that data in this buffer will be sent before the stream is authed
 192                         -- and will not be ack'd in any way, successful or otherwise
 193                         local buffer;
 194                         function host_session.sends2s(data)
 195                                 if not buffer then
 196                                         buffer = {};
 197                                         host_session.send_buffer = buffer;
 198                                 end
 199                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 200                                 buffer[#buffer+1] = data;
 201                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 202                         end
 203                 end
 204
 205                 return host_session;
 206 end
 207
 208
 209 function attempt_connection(host_session, err)
 210         local from_host, to_host = host_session.from_host, host_session.to_host;
 211         local connect_host, connect_port = idna_to_ascii(to_host), 5269;
 212
 213         if not connect_host then
 214                 return false;
 215         end
 216
 217         if not err then -- This is our first attempt
 218                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 219                 host_session.connecting = true;
 220                 local handle;
 221                 handle = adns.lookup(function (answer)
 222                         handle = nil;
 223                         host_session.connecting = nil;
 224                         if answer then
 225                                 log("debug", to_host.." has SRV records, handling...");
 226                                 local srv_hosts = {};
 227                                 host_session.srv_hosts = srv_hosts;
 228                                 for _, record in ipairs(answer) do
 229                                         t_insert(srv_hosts, record.srv);
 230                                 end
 231                                 t_sort(srv_hosts, compare_srv_priorities);
 232
 233                                 local srv_choice = srv_hosts[1];
 234                                 host_session.srv_choice = 1;
 235                                 if srv_choice then
 236                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 237                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 238                                 end
 239                         else
 240                                 log("debug", to_host.." has no SRV records, falling back to A");
 241                         end
 242                         -- Try with SRV, or just the plain hostname if no SRV
 243                         local ok, err = try_connect(host_session, connect_host, connect_port);
 244                         if not ok then
 245                                 if not attempt_connection(host_session, err) then
 246                                         -- No more attempts will be made
 247                                         destroy_session(host_session, err);
 248                                 end
 249                         end
 250                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 251
 252                 -- Set handler for DNS timeout
 253                 add_task(dns_timeout, function ()
 254                         if handle then
 255                                 adns.cancel(handle, true);
 256                         end
 257                 end);
 258
 259                 return true; -- Attempt in progress
 260         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 261                 host_session.srv_choice = host_session.srv_choice + 1;
 262                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 263                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 264                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 265         else
 266                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 267                 -- We're out of options
 268                 return false;
 269         end
 270
 271         if not (connect_host and connect_port) then
 272                 -- Likely we couldn't resolve DNS
 273                 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));
 274                 return false;
 275         end
 276
 277         return try_connect(host_session, connect_host, connect_port);
 278 end
 279
 280 function try_connect(host_session, connect_host, connect_port)
 281         host_session.connecting = true;
 282         local handle;
 283         handle = adns.lookup(function (reply)
 284                 handle = nil;
 285                 host_session.connecting = nil;
 286
 287                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 288                 if not (reply and reply[#reply] and reply[#reply].a) then
 289                         local count = max_dns_depth;
 290                         reply = dns.peek(connect_host, "CNAME", "IN");
 291                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 292                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 293                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 294                                 count = count - 1;
 295                         end
 296                 end
 297                 -- end of CNAME resolving
 298
 299                 if reply and reply[#reply] and reply[#reply].a then
 300                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 301                         return make_connect(host_session, reply[#reply].a, connect_port);
 302                 else
 303                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 304                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 305                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 306                                 destroy_session(host_session, "DNS resolution failed"); -- End of the line, we can't
 307                         end
 308                 end
 309         end, connect_host, "A", "IN");
 310
 311         -- Set handler for DNS timeout
 312         add_task(dns_timeout, function ()
 313                 if handle then
 314                         adns.cancel(handle, true);
 315                 end
 316         end);
 317
 318         return true;
 319 end
 320
 321 function make_connect(host_session, connect_host, connect_port)
 322         (host_session.log or log)("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 323         -- Ok, we're going to try to connect
 324
 325         local from_host, to_host = host_session.from_host, host_session.to_host;
 326
 327         local conn, handler = socket.tcp()
 328
 329         if not conn then
 330                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 331                 return false, handler;
 332         end
 333
 334         conn:settimeout(0);
 335         local success, err = conn:connect(connect_host, connect_port);
 336         if not success and err ~= "timeout" then
 337                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 338                 return false, err;
 339         end
 340
 341         local cl = connlisteners_get("xmppserver");
 342         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 343         host_session.conn = conn;
 344
 345         -- Register this outgoing connection so that xmppserver_listener knows about it
 346         -- otherwise it will assume it is a new incoming connection
 347         cl.register_outgoing(conn, host_session);
 348
 349         local filter = initialize_filters(host_session);
 350         local w, log = conn.write, host_session.log;
 351         host_session.sends2s = function (t)
 352                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 353                 if t.name then
 354                         t = filter("stanzas/out", t);
 355                 end
 356                 if t then
 357                         t = filter("bytes/out", tostring(t));
 358                         if t then
 359                                 return w(conn, tostring(t));
 360                         end
 361                 end
 362         end
 363
 364         host_session:open_stream(from_host, to_host);
 365
 366         log("debug", "Connection attempt in progress...");
 367         add_task(connect_timeout, function ()
 368                 if host_session.conn ~= conn or
 369                    host_session.type == "s2sout" or
 370                    host_session.connecting then
 371                         return; -- Ok, we're connect[ed|ing]
 372                 end
 373                 -- Not connected, need to close session and clean up
 374                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 375                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 376                 host_session:close("connection-timeout");
 377         end);
 378         return true;
 379 end
 380
 381 function session_open_stream(session, from, to)
 382         session.sends2s(st.stanza("stream:stream", {
 383                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 384                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 385                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 386 end
 387
 388 function streamopened(session, attr)
 389         local send = session.sends2s;
 390
 391         -- TODO: #29: SASL/TLS on s2s streams
 392         session.version = tonumber(attr.version) or 0;
 393
 394         if session.secure == false then
 395                 session.secure = true;
 396         end
 397
 398         if session.direction == "incoming" then
 399                 -- Send a reply stream header
 400                 session.to_host = attr.to and nameprep(attr.to);
 401                 session.from_host = attr.from and nameprep(attr.from);
 402
 403                 session.streamid = uuid_gen();
 404                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 405                 if session.to_host and not hosts[session.to_host] then
 406                         -- Attempting to connect to a host we don't serve
 407                         session:close({ condition = "host-unknown"; text = "This host does not serve "..session.to_host });
 408                         return;
 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
 519         if session.direction == "outgoing" then
 520                 if sendq then
 521                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 522                         for i, data in ipairs(sendq) do
 523                                 send(data[1]);
 524                                 sendq[i] = nil;
 525                         end
 526                         session.sendq = nil;
 527                 end
 528
 529                 session.srv_hosts = nil;
 530         end
 531 end
 532
 533 local resting_session = { -- Resting, not dead
 534                 destroyed = true;
 535                 type = "s2s_destroyed";
 536                 open_stream = function (session)
 537                         session.log("debug", "Attempt to open stream on resting session");
 538                 end;
 539                 close = function (session)
 540                         session.log("debug", "Attempt to close already-closed session");
 541                 end;
 542         }; resting_session.__index = resting_session;
 543
 544 function retire_session(session)
 545         local log = session.log or log;
 546         for k in pairs(session) do
 547                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 548                         session[k] = nil;
 549                 end
 550         end
 551
 552         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 553         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 554         return setmetatable(session, resting_session);
 555 end
 556
 557 function destroy_session(session, reason)
 558         if session.destroyed then return; end
 559         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 560
 561         if session.direction == "outgoing" then
 562                 hosts[session.from_host].s2sout[session.to_host] = nil;
 563                 bounce_sendq(session, reason);
 564         elseif session.direction == "incoming" then
 565                 incoming_s2s[session] = nil;
 566         end
 567
 568         retire_session(session); -- Clean session until it is GC'd
 569 end
 570
 571 return _M;