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                         if reply and not(reply.attr.xmlns) and bouncy_stanzas[reply.name] then
  74                                 reply.attr.type = "error";
  75                                 reply:tag("error", {type = "cancel"})
  76                                         :tag("remote-server-not-found", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):up();
  77                                 if reason then
  78                                         reply:tag("text", {xmlns = "urn:ietf:params:xml:ns:xmpp-stanzas"}):text("Connection failed: "..reason):up();
  79                                 end
  80                                 core_process_stanza(dummy, reply);
  81                         end
  82                         sendq[i] = nil;
  83                 end
  84                 session.sendq = nil;
  85         end
  86 end
  87
  88 function send_to_host(from_host, to_host, data)
  89         if not hosts[from_host] then
  90                 log("warn", "Attempt to send stanza from %s - a host we don't serve", from_host);
  91                 return false;
  92         end
  93         local host = hosts[from_host].s2sout[to_host];
  94         if host then
  95                 -- We have a connection to this host already
  96                 if host.type == "s2sout_unauthed" and (data.name ~= "db:verify" or not host.dialback_key) then
  97                         (host.log or log)("debug", "trying to send over unauthed s2sout to "..to_host);
  98
  99                         -- Queue stanza until we are able to send it
 100                         if host.sendq then t_insert(host.sendq, {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)});
 101                         else host.sendq = { {tostring(data), data.attr.type ~= "error" and data.attr.type ~= "result" and st.reply(data)} }; end
 102                         host.log("debug", "stanza [%s] queued ", data.name);
 103                 elseif host.type == "local" or host.type == "component" then
 104                         log("error", "Trying to send a stanza to ourselves??")
 105                         log("error", "Traceback: %s", get_traceback());
 106                         log("error", "Stanza: %s", tostring(data));
 107                         return false;
 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), data.attr.type ~= "error" and data.attr.type ~= "result" and 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                         if not destroy_session(host_session, "Connection failed") then
 128                                 -- Already destroyed, we need to bounce our stanza
 129                                 bounce_sendq(host_session, host_session.destruction_reason);
 130                         end
 131                         return false;
 132                 end
 133         end
 134         return true;
 135 end
 136
 137 local open_sessions = 0;
 138
 139 function new_incoming(conn)
 140         local session = { conn = conn, type = "s2sin_unauthed", direction = "incoming", hosts = {} };
 141         if true then
 142                 session.trace = newproxy(true);
 143                 getmetatable(session.trace).__gc = function () open_sessions = open_sessions - 1; end;
 144         end
 145         open_sessions = open_sessions + 1;
 146         local w, log = conn.write, logger_init("s2sin"..tostring(conn):match("[a-f0-9]+$"));
 147         session.log = log;
 148         local filter = initialize_filters(session);
 149         session.sends2s = function (t)
 150                 log("debug", "sending: %s", t.top_tag and t:top_tag() or t:match("^([^>]*>?)"));
 151                 if t.name then
 152                         t = filter("stanzas/out", t);
 153                 end
 154                 if t then
 155                         t = filter("bytes/out", tostring(t));
 156                         if t then
 157                                 return w(conn, t);
 158                         end
 159                 end
 160         end
 161         incoming_s2s[session] = true;
 162         add_task(connect_timeout, function ()
 163                 if session.conn ~= conn or
 164                    session.type == "s2sin" then
 165                         return; -- Ok, we're connect[ed|ing]
 166                 end
 167                 -- Not connected, need to close session and clean up
 168                 (session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 169                     session.from_host or "(unknown)", session.to_host or "(unknown)");
 170                 session:close("connection-timeout");
 171         end);
 172         return session;
 173 end
 174
 175 function new_outgoing(from_host, to_host, connect)
 176                 local host_session = { to_host = to_host, from_host = from_host, host = from_host,
 177                                        notopen = true, type = "s2sout_unauthed", direction = "outgoing",
 178                                        open_stream = session_open_stream };
 179
 180                 hosts[from_host].s2sout[to_host] = host_session;
 181
 182                 host_session.close = destroy_session; -- This gets replaced by xmppserver_listener later
 183
 184                 local log;
 185                 do
 186                         local conn_name = "s2sout"..tostring(host_session):match("[a-f0-9]*$");
 187                         log = logger_init(conn_name);
 188                         host_session.log = log;
 189                 end
 190
 191                 initialize_filters(host_session);
 192
 193                 if connect ~= false then
 194                         -- Kick the connection attempting machine into life
 195                         if not attempt_connection(host_session) then
 196                                 -- Intentionally not returning here, the
 197                                 -- session is needed, connected or not
 198                                 destroy_session(host_session);
 199                         end
 200                 end
 201
 202                 if not host_session.sends2s then
 203                         -- A sends2s which buffers data (until the stream is opened)
 204                         -- note that data in this buffer will be sent before the stream is authed
 205                         -- and will not be ack'd in any way, successful or otherwise
 206                         local buffer;
 207                         function host_session.sends2s(data)
 208                                 if not buffer then
 209                                         buffer = {};
 210                                         host_session.send_buffer = buffer;
 211                                 end
 212                                 log("debug", "Buffering data on unconnected s2sout to %s", to_host);
 213                                 buffer[#buffer+1] = data;
 214                                 log("debug", "Buffered item %d: %s", #buffer, tostring(data));
 215                         end
 216                 end
 217
 218                 return host_session;
 219 end
 220
 221
 222 function attempt_connection(host_session, err)
 223         local from_host, to_host = host_session.from_host, host_session.to_host;
 224         local connect_host, connect_port = to_host and idna_to_ascii(to_host), 5269;
 225
 226         if not connect_host then
 227                 return false;
 228         end
 229
 230         if not err then -- This is our first attempt
 231                 log("debug", "First attempt to connect to %s, starting with SRV lookup...", to_host);
 232                 host_session.connecting = true;
 233                 local handle;
 234                 handle = adns.lookup(function (answer)
 235                         handle = nil;
 236                         host_session.connecting = nil;
 237                         if answer then
 238                                 log("debug", to_host.." has SRV records, handling...");
 239                                 local srv_hosts = {};
 240                                 host_session.srv_hosts = srv_hosts;
 241                                 for _, record in ipairs(answer) do
 242                                         t_insert(srv_hosts, record.srv);
 243                                 end
 244                                 t_sort(srv_hosts, compare_srv_priorities);
 245
 246                                 local srv_choice = srv_hosts[1];
 247                                 host_session.srv_choice = 1;
 248                                 if srv_choice then
 249                                         connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 250                                         log("debug", "Best record found, will connect to %s:%d", connect_host, connect_port);
 251                                 end
 252                         else
 253                                 log("debug", to_host.." has no SRV records, falling back to A");
 254                         end
 255                         -- Try with SRV, or just the plain hostname if no SRV
 256                         local ok, err = try_connect(host_session, connect_host, connect_port);
 257                         if not ok then
 258                                 if not attempt_connection(host_session, err) then
 259                                         -- No more attempts will be made
 260                                         destroy_session(host_session, err);
 261                                 end
 262                         end
 263                 end, "_xmpp-server._tcp."..connect_host..".", "SRV");
 264
 265                 return true; -- Attempt in progress
 266         elseif host_session.srv_hosts and #host_session.srv_hosts > host_session.srv_choice then -- Not our first attempt, and we also have SRV
 267                 host_session.srv_choice = host_session.srv_choice + 1;
 268                 local srv_choice = host_session.srv_hosts[host_session.srv_choice];
 269                 connect_host, connect_port = srv_choice.target or to_host, srv_choice.port or connect_port;
 270                 host_session.log("info", "Connection failed (%s). Attempt #%d: This time to %s:%d", tostring(err), host_session.srv_choice, connect_host, connect_port);
 271         else
 272                 host_session.log("info", "Out of connection options, can't connect to %s", tostring(host_session.to_host));
 273                 -- We're out of options
 274                 return false;
 275         end
 276
 277         if not (connect_host and connect_port) then
 278                 -- Likely we couldn't resolve DNS
 279                 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));
 280                 return false;
 281         end
 282
 283         return try_connect(host_session, connect_host, connect_port);
 284 end
 285
 286 function try_connect(host_session, connect_host, connect_port)
 287         host_session.connecting = true;
 288         local handle;
 289         handle = adns.lookup(function (reply, err)
 290                 handle = nil;
 291                 host_session.connecting = nil;
 292
 293                 -- COMPAT: This is a compromise for all you CNAME-(ab)users :)
 294                 if not (reply and reply[#reply] and reply[#reply].a) then
 295                         local count = max_dns_depth;
 296                         reply = dns.peek(connect_host, "CNAME", "IN");
 297                         while count > 0 and reply and reply[#reply] and not reply[#reply].a and reply[#reply].cname do
 298                                 log("debug", "Looking up %s (DNS depth is %d)", tostring(reply[#reply].cname), count);
 299                                 reply = dns.peek(reply[#reply].cname, "A", "IN") or dns.peek(reply[#reply].cname, "CNAME", "IN");
 300                                 count = count - 1;
 301                         end
 302                 end
 303                 -- end of CNAME resolving
 304
 305                 if reply and reply[#reply] and reply[#reply].a then
 306                         log("debug", "DNS reply for %s gives us %s", connect_host, reply[#reply].a);
 307                         local ok, err = make_connect(host_session, reply[#reply].a, connect_port);
 308                         if not ok then
 309                                 if not attempt_connection(host_session, err or "closed") then
 310                                         err = err and (": "..err) or "";
 311                                         destroy_session(host_session, "Connection failed"..err);
 312                                 end
 313                         end
 314                 else
 315                         log("debug", "DNS lookup failed to get a response for %s", connect_host);
 316                         if not attempt_connection(host_session, "name resolution failed") then -- Retry if we can
 317                                 log("debug", "No other records to try for %s - destroying", host_session.to_host);
 318                                 err = err and (": "..err) or "";
 319                                 destroy_session(host_session, "DNS resolution failed"..err); -- End of the line, we can't
 320                         end
 321                 end
 322         end, connect_host, "A", "IN");
 323
 324         return true;
 325 end
 326
 327 function make_connect(host_session, connect_host, connect_port)
 328         (host_session.log or log)("info", "Beginning new connection attempt to %s (%s:%d)", host_session.to_host, connect_host, connect_port);
 329         -- Ok, we're going to try to connect
 330
 331         local from_host, to_host = host_session.from_host, host_session.to_host;
 332
 333         local conn, handler = socket.tcp();
 334
 335         if not conn then
 336                 log("warn", "Failed to create outgoing connection, system error: %s", handler);
 337                 return false, handler;
 338         end
 339
 340         conn:settimeout(0);
 341         local success, err = conn:connect(connect_host, connect_port);
 342         if not success and err ~= "timeout" then
 343                 log("warn", "s2s connect() to %s (%s:%d) failed: %s", host_session.to_host, connect_host, connect_port, err);
 344                 return false, err;
 345         end
 346
 347         local cl = connlisteners_get("xmppserver");
 348         conn = wrapclient(conn, connect_host, connect_port, cl, cl.default_mode or 1 );
 349         host_session.conn = conn;
 350
 351         local filter = initialize_filters(host_session);
 352         local w, log = conn.write, host_session.log;
 353         host_session.sends2s = function (t)
 354                 log("debug", "sending: %s", (t.top_tag and t:top_tag()) or t:match("^[^>]*>?"));
 355                 if t.name then
 356                         t = filter("stanzas/out", t);
 357                 end
 358                 if t then
 359                         t = filter("bytes/out", tostring(t));
 360                         if t then
 361                                 return w(conn, tostring(t));
 362                         end
 363                 end
 364         end
 365
 366         -- Register this outgoing connection so that xmppserver_listener knows about it
 367         -- otherwise it will assume it is a new incoming connection
 368         cl.register_outgoing(conn, host_session);
 369
 370         host_session:open_stream(from_host, to_host);
 371
 372         log("debug", "Connection attempt in progress...");
 373         add_task(connect_timeout, function ()
 374                 if host_session.conn ~= conn or
 375                    host_session.type == "s2sout" or
 376                    host_session.connecting then
 377                         return; -- Ok, we're connect[ed|ing]
 378                 end
 379                 -- Not connected, need to close session and clean up
 380                 (host_session.log or log)("warn", "Destroying incomplete session %s->%s due to inactivity",
 381                     host_session.from_host or "(unknown)", host_session.to_host or "(unknown)");
 382                 host_session:close("connection-timeout");
 383         end);
 384         return true;
 385 end
 386
 387 function session_open_stream(session, from, to)
 388         session.sends2s(st.stanza("stream:stream", {
 389                 xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 390                 ["xmlns:stream"]='http://etherx.jabber.org/streams',
 391                 from=from, to=to, version='1.0', ["xml:lang"]='en'}):top_tag());
 392 end
 393
 394 function streamopened(session, attr)
 395         local send = session.sends2s;
 396
 397         -- TODO: #29: SASL/TLS on s2s streams
 398         session.version = tonumber(attr.version) or 0;
 399
 400         if session.secure == false then
 401                 session.secure = true;
 402         end
 403
 404         if session.direction == "incoming" then
 405                 -- Send a reply stream header
 406                 session.to_host = attr.to and nameprep(attr.to);
 407                 session.from_host = attr.from and nameprep(attr.from);
 408
 409                 session.streamid = uuid_gen();
 410                 (session.log or log)("debug", "incoming s2s received <stream:stream>");
 411                 if session.to_host then
 412                         if not hosts[session.to_host] then
 413                                 -- Attempting to connect to a host we don't serve
 414                                 session:close({
 415                                         condition = "host-unknown";
 416                                         text = "This host does not serve "..session.to_host
 417                                 });
 418                                 return;
 419                         elseif hosts[session.to_host].disallow_s2s then
 420                                 -- Attempting to connect to a host that disallows s2s
 421                                 session:close({
 422                                         condition = "policy-violation";
 423                                         text = "Server-to-server communication is not allowed to this host";
 424                                 });
 425                                 return;
 426                         end
 427                 end
 428                 send("<?xml version='1.0'?>");
 429                 send(stanza("stream:stream", { xmlns='jabber:server', ["xmlns:db"]='jabber:server:dialback',
 430                                 ["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());
 431                 if session.version >= 1.0 then
 432                         local features = st.stanza("stream:features");
 433
 434                         if session.to_host then
 435                                 hosts[session.to_host].events.fire_event("s2s-stream-features", { origin = session, features = features });
 436                         else
 437                                 (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");
 438                         end
 439
 440                         log("debug", "Sending stream features: %s", tostring(features));
 441                         send(features);
 442                 end
 443         elseif session.direction == "outgoing" then
 444                 -- If we are just using the connection for verifying dialback keys, we won't try and auth it
 445                 if not attr.id then error("stream response did not give us a streamid!!!"); end
 446                 session.streamid = attr.id;
 447
 448                 -- Send unauthed buffer
 449                 -- (stanzas which are fine to send before dialback)
 450                 -- Note that this is *not* the stanza queue (which
 451                 -- we can only send if auth succeeds) :)
 452                 local send_buffer = session.send_buffer;
 453                 if send_buffer and #send_buffer > 0 then
 454                         log("debug", "Sending s2s send_buffer now...");
 455                         for i, data in ipairs(send_buffer) do
 456                                 session.sends2s(tostring(data));
 457                                 send_buffer[i] = nil;
 458                         end
 459                 end
 460                 session.send_buffer = nil;
 461
 462                 -- If server is pre-1.0, don't wait for features, just do dialback
 463                 if session.version < 1.0 then
 464                         if not session.dialback_verifying then
 465                                 log("debug", "Initiating dialback...");
 466                                 initiate_dialback(session);
 467                         else
 468                                 mark_connected(session);
 469                         end
 470                 end
 471         end
 472         session.notopen = nil;
 473 end
 474
 475 function streamclosed(session)
 476         (session.log or log)("debug", "Received </stream:stream>");
 477         session:close();
 478 end
 479
 480 function initiate_dialback(session)
 481         -- generate dialback key
 482         session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
 483         session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
 484         session.log("info", "sent dialback key on outgoing s2s stream");
 485 end
 486
 487 function generate_dialback(id, to, from)
 488         return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
 489 end
 490
 491 function verify_dialback(id, to, from, key)
 492         return key == generate_dialback(id, to, from);
 493 end
 494
 495 function make_authenticated(session, host)
 496         if not session.secure then
 497                 local local_host = session.direction == "incoming" and session.to_host or session.from_host;
 498                 if config.get(local_host, "core", "s2s_require_encryption") then
 499                         session:close({
 500                                 condition = "policy-violation",
 501                                 text = "Encrypted server-to-server communication is required but was not "
 502                                        ..((session.direction == "outgoing" and "offered") or "used")
 503                         });
 504                 end
 505         end
 506         if session.type == "s2sout_unauthed" then
 507                 session.type = "s2sout";
 508         elseif session.type == "s2sin_unauthed" then
 509                 session.type = "s2sin";
 510                 if host then
 511                         if not session.hosts[host] then session.hosts[host] = {}; end
 512                         session.hosts[host].authed = true;
 513                 end
 514         elseif session.type == "s2sin" and host then
 515                 if not session.hosts[host] then session.hosts[host] = {}; end
 516                 session.hosts[host].authed = true;
 517         else
 518                 return false;
 519         end
 520         session.log("debug", "connection %s->%s is now authenticated", session.from_host or "(unknown)", session.to_host or "(unknown)");
 521
 522         mark_connected(session);
 523
 524         return true;
 525 end
 526
 527 -- Stream is authorised, and ready for normal stanzas
 528 function mark_connected(session)
 529         local sendq, send = session.sendq, session.sends2s;
 530
 531         local from, to = session.from_host, session.to_host;
 532
 533         session.log("info", session.direction.." s2s connection "..from.."->"..to.." complete");
 534
 535         local send_to_host = send_to_host;
 536         function session.send(data) return send_to_host(to, from, data); end
 537
 538         local event_data = { session = session };
 539         if session.type == "s2sout" then
 540                 prosody.events.fire_event("s2sout-established", event_data);
 541                 hosts[session.from_host].events.fire_event("s2sout-established", event_data);
 542         else
 543                 prosody.events.fire_event("s2sin-established", event_data);
 544                 hosts[session.to_host].events.fire_event("s2sin-established", event_data);
 545         end
 546
 547         if session.direction == "outgoing" then
 548                 if sendq then
 549                         session.log("debug", "sending "..#sendq.." queued stanzas across new outgoing connection to "..session.to_host);
 550                         for i, data in ipairs(sendq) do
 551                                 send(data[1]);
 552                                 sendq[i] = nil;
 553                         end
 554                         session.sendq = nil;
 555                 end
 556
 557                 session.srv_hosts = nil;
 558         end
 559 end
 560
 561 local resting_session = { -- Resting, not dead
 562                 destroyed = true;
 563                 type = "s2s_destroyed";
 564                 open_stream = function (session)
 565                         session.log("debug", "Attempt to open stream on resting session");
 566                 end;
 567                 close = function (session)
 568                         session.log("debug", "Attempt to close already-closed session");
 569                 end;
 570                 filter = function (type, data) return data; end;
 571         }; resting_session.__index = resting_session;
 572
 573 function retire_session(session, reason)
 574         local log = session.log or log;
 575         for k in pairs(session) do
 576                 if k ~= "trace" and k ~= "log" and k ~= "id" then
 577                         session[k] = nil;
 578                 end
 579         end
 580
 581         session.destruction_reason = reason;
 582
 583         function session.send(data) log("debug", "Discarding data sent to resting session: %s", tostring(data)); end
 584         function session.data(data) log("debug", "Discarding data received from resting session: %s", tostring(data)); end
 585         return setmetatable(session, resting_session);
 586 end
 587
 588 function destroy_session(session, reason)
 589         if session.destroyed then return; end
 590         (session.log or log)("info", "Destroying "..tostring(session.direction).." session "..tostring(session.from_host).."->"..tostring(session.to_host));
 591
 592         if session.direction == "outgoing" then
 593                 hosts[session.from_host].s2sout[session.to_host] = nil;
 594                 bounce_sendq(session, reason);
 595         elseif session.direction == "incoming" then
 596                 incoming_s2s[session] = nil;
 597         end
 598
 599         local event_data = { session = session, reason = reason };
 600         if session.type == "s2sout" then
 601                 prosody.events.fire_event("s2sout-destroyed", event_data);
 602                 if hosts[session.from_host] then
 603                         hosts[session.from_host].events.fire_event("s2sout-destroyed", event_data);
 604                 end
 605         elseif session.type == "s2sin" then
 606                 prosody.events.fire_event("s2sin-destroyed", event_data);
 607                 if hosts[session.to_host] then
 608                         hosts[session.to_host].events.fire_event("s2sin-destroyed", event_data);
 609                 end
 610         end
 611
 612         retire_session(session, reason); -- Clean session until it is GC'd
 613         return true;
 614 end
 615
 616 return _M;