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